Search results for: Jung Y. Huang
821 Support Vector Regression with Weighted Least Absolute Deviations
Authors: Kang-Mo Jung
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Least squares support vector machine (LS-SVM) is a penalized regression which considers both fitting and generalization ability of a model. However, the squared loss function is very sensitive to even single outlier. We proposed a weighted absolute deviation loss function for the robustness of the estimates in least absolute deviation support vector machine. The proposed estimates can be obtained by a quadratic programming algorithm. Numerical experiments on simulated datasets show that the proposed algorithm is competitive in view of robustness to outliers.Keywords: least absolute deviation, quadratic programming, robustness, support vector machine, weight
Procedia PDF Downloads 525820 Design of Functional Safe Motor Control Systems in Automotive Applications
Authors: Jae-Woo Kim, Kyung-Jung Lee, Hyun-Sik Ahn
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This paper presents a design methodology for the motor driven automotive subsystems with the consideration of the functional safety. There are many such modules in vehicles which use DC/AC motors for an electronic throttle control system, a motor driven power steering, a motor driven seat belt systems and for HVAC systems. The functional safety for the automotive electrical and electronic parts are standardized as ISO 26262, but the development procedure is very complex to be followed. We focus on the functional safe motor controller design process and show the designed motor controller hardware satisfies the required safety integrity level by using metric calculations with the safety mechanism.Keywords: AUTOSAR, MDPS, Simulink, software component
Procedia PDF Downloads 411819 Bio-Electrochemical Process Coupled with MnO2 Nanowires for Wastewater Treatment
Authors: A. Giwa, S. M. Jung, W. Fang, J. Kong, S. W. Hasan
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MnO2 nanowires were developed as filtration media for wastewater treatment that uniquely combines several advantages. The resulting material demonstrated strong capability to remove the pollution of heavy metal ions and organic contents in water. In addition, the manufacture process of such material is practical and economical. In this work, MnO2 nanowires were integrated with the state-of-art bio-electrochemical system for wastewater treatment, to overcome problems currently encountered with organic, inorganic, heavy metal, and microbe removal, and to minimize the unit footprint (land/space occupation) at low cost. Results showed that coupling the bio-electrochemical with MnO2 resulted in very encouraging results with higher removal efficiencies of such pollutants.Keywords: bio-electrochemical, nanowires, novel, wastewater
Procedia PDF Downloads 385818 Effect of Y Addition on the Microstructure and Mechanical Properties of Sn-Zn Eutectic Alloy
Authors: Jung-Ho Moon, Tae Kwon Ha
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The effect of Yttrium addition on the microstructure and mechanical properties of Sn-Zn eutectic alloy, which has been attracting intensive focus as a Pb-free solder material, was investigated in this study. Phase equilibrium has been calculated by using FactSage® to evaluate the composition and fraction of equilibrium intermetallic compounds and construct a phase diagram. In the case of Sn-8.8 Zn eutectic alloy, the as-cast microstructure was typical lamellar. With addition of 0.25 wt. %Y, a large amount of pro-eutectic phases have been observed and various YZnx intermetallic compounds were expected to successively form during cooling. Hardness of Sn-8.8 Zn alloy was not affected by Y-addition and both alloys could be rolled by 90% at room temperature.Keywords: Sn-Zn eutectic alloy, yttrium, FactSage®, microstructure, mechanical properties
Procedia PDF Downloads 466817 Template-Assisted Synthesis of IrO2 Nanopores Membrane Electrode Assembly
Authors: Zhuo-Xin Lu, Yan Shi, Chang-Feng Yan, Ying Huang, Yuan Gan, Zhi-Da Wang
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With TiO2 nanotube arrays (TNTA) as template, a IrO2 nanopores membrane electrode assembly (MEA) was synthesized by a novel depositi-assemble-etch strategy. By analysing the morphology of IrO2/TNTA and cyclic voltammetry (CV) curve at different deposition cycles, we proposed a reasonable scheme for the process of IrO2 electrodeposition on TNTA. The current density of IrO2/TNTA at 1.5V vs RHE reaches 5.12mA/cm2 after 55 cycles deposition, which shows promising performance for its high OER activity after template removal.Keywords: electrodeposition, IrO2 nanopores, MEA, OER
Procedia PDF Downloads 444816 A Case Study of Limited Dynamic Voltage Frequency Scaling in Low-Power Processors
Authors: Hwan Su Jung, Ahn Jun Gil, Jong Tae Kim
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Power management techniques are necessary to save power in the microprocessor. By changing the frequency and/or operating voltage of processor, DVFS can control power consumption. In this paper, we perform a case study to find optimal power state transition for DVFS. We propose the equation to find the optimal ratio between executions of states while taking into account the deadline of processing time and the power state transition delay overhead. The experiment is performed on the Cortex-M4 processor, and average 6.5% power saving is observed when DVFS is applied under the deadline condition.Keywords: deadline, dynamic voltage frequency scaling, power state transition
Procedia PDF Downloads 454815 The Sustainability of Public Debt in Taiwan
Authors: Chiung-Ju Huang
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This study examines whether the Taiwan’s public debt is sustainable utilizing an unrestricted two-regime threshold autoregressive (TAR) model with an autoregressive unit root. The empirical results show that Taiwan’s public debt appears as a nonlinear series and is stationary in regime 1 but not in regime 2. This result implies that while Taiwan’s public debt was mostly sustainable over the 1996 to 2013 period examined in the study, it may no longer be sustainable in the most recent two years as the public debt ratio has increased cumulatively to 3.618%.Keywords: nonlinearity, public debt, sustainability, threshold autoregressive model
Procedia PDF Downloads 448814 Biodegradation Effects onto Source Identification of Diesel Fuel Contaminated Soils
Authors: Colin S. Chen, Chien-Jung Tien, Hsin-Jan Huang
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For weathering studies, the change of chemical constituents by biodegradation effect in diesel-contaminated soils are important factors to be considered, especially when there is a prolonged period of weathering processes. The objective was to evaluate biodegradation effects onto hydrocarbon fingerprinting and distribution patterns of diesel fuels, fuel source screening and differentiation, source-specific marker compounds, and diagnostic ratios of diesel fuel constituents by laboratory and field studies. Biodegradation processes of diesel contaminated soils were evaluated by experiments lasting for 15 and 12 months, respectively. The degradation of diesel fuel in top soils was affected by organic carbon content and biomass of microorganisms in soils. Higher depletion of total petroleum hydrocarbon (TPH), n-alkanes, and polynuclear aromatic hydrocarbons (PAHs) and their alkyl homologues was observed in soils containing higher organic carbon content and biomass. Decreased ratio of selected isoprenoids (i.e., pristane (Pr) and phytane (Ph)) including n-C17/pristane and n-C18/phytane was observed. The ratio of pristane/phytane was remained consistent for a longer period of time. At the end of the experimental period, a decrease of pristane/phytane was observed. Biomarker compounds of bicyclic sesquiterpanes (BS) were less susceptible to the effects of biodegradation. The ratios of characteristic factors such as C15 sesquiterpane/ 8β(H)-drimane (BS3/BS5), C15 sesquiterpane/ 8β(H)-drimane (BS4/BS5), 8β(H)-drimane/8β(H)-homodrimane (BS5/BS10), and C15 sesquiterpane/8β(H)-homodrimane (BS3/BS10) could be adopted for source identification of diesel fuels in top soil. However, for biodegradation processes lasted for six months but shorter than nine months, only BS3/BS5 and BS3/BS10 could be distinguished in two diesel fuels. In subsoil experiments (contaminated soil located 50 cm below), the ratios of characteristic factors including BS3/BS5, BS4/BS5, and BS5/BS10 were valid for source identification of two diesel fuels for nine month biodegradation. At the early stage of contamination, biomass of soil decreased significantly. However, 6 and 7 dominant species were found in soils in top soil experiments, respectively. With less oxygen and nutrients in subsoil, less biomass of microorganisms was observed in subsoils. Only 2 and 4 diesel-degrading species of microorganisms were identified in two soils, respectively. Parameters of double ratio such as fluorene/C1-fluorene: C2-phenanthrene/C3-phenanthrene (C0F/C1F:C2P/C3P) in both top and subsoil, C2-naphthalene/C2-phenanthrene: C1-phenanthrene/C3-phenanthrene (C2N/C2P:C1P/C3P), and C1-phenanthrene/C1-fluorene: C3-naphthalene/C3-phenanthrene (C1P/C1F:C3N/C3P) in subsoil could serve as forensic indicators in diesel contaminated sites. BS3/BS10:BS4/BS5 could be used in 6 to 9 months of biodegradation processes. Results of principal component analysis (PCA) indicated that source identification of diesel fuels in top soil could only be perofrmed for weathering process less than 6 months. For subsoil, identification can be conducted for weathering process less than 9 months. Ratio of isoprenoids (pristane and phytane) and PAHs might be affected by biodegradation in spilled sites. The ratios of bicyclic sesquiterpanes could serve as forensic indicators in diesel-contaminated soils. Finally, source identification was attemped for samples collected from different fuel contaminated sites by using the unique pattern of sesquiterpanes. It was anticipated that the information generated from this study would be adopted by decision makers to evaluate the liability of cleanup in diesel contaminated sites.Keywords: biodegradation, diagnostic ratio, diesel fuel, environmental forensics
Procedia PDF Downloads 227813 Insulation Properties of Rod-Plane Electrode Covered with ATH/SIR Nano-Composite in Dry-Air
Authors: Jae-Yong Sim, Jung-Hun Kwon, Ji-Sung Park, Kee-Joe Lim
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One of the latest trends for insulation systems to improve the insulation performance is the use of eco-friendly hybrid insulation using compressed dry-air. Despite the excellent insulation performance of sulphurhexafluoride (SF6) gas, its use has been restricted due to the problems with significant global warming potential (GWP). Accordingly, lightning impulse performance of the hybrid insulation system covered with an aluminum trihydrate/silicone rubber (ATH/SIR) nanocomposite was examined in air at atmospheric pressure and in compressed air at pressures between 0.2 and 0.6 MPa. In the experiments, the most common breakdown path took place along the surface of the covered rod. The insulation reliability after several discharges should be guaranteed in hybrid insulation. On the other hand, the surface of the covered rod was carbonized after several discharges. Therefore, nanoscale ATH can be used as a reinforcement of covered dielectrics to inhibit carbonization on the surface of a covered rod. The results were analyzed in terms of the surface resistivity of the cover dielectrics.Keywords: nanocomposite, hybrid insulation, ATH, dry-air
Procedia PDF Downloads 448812 Adaptive Transmission Scheme Based on Channel State in Dual-Hop System
Authors: Seung-Jun Yu, Yong-Jun Kim, Jung-In Baik, Hyoung-Kyu Song
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In this paper, a dual-hop relay based on channel state is studied. In the conventional relay scheme, a relay uses the same modulation method without reference to channel state. But, a relay uses an adaptive modulation method with reference to channel state. If the channel state is poor, a relay eliminates latter 2 bits and uses Quadrature Phase Shift Keying (QPSK) modulation. If channel state is good, a relay modulates the received symbols with 16-QAM symbols by using 4 bits. The performance of the proposed scheme for Symbol Error Rate (SER) and throughput is analyzed.Keywords: adaptive transmission, channel state, dual-hop, hierarchical modulation, relay
Procedia PDF Downloads 377811 A Proposal of Local Indentation Techniques for Mechanical Property Evaluation
Authors: G. B. Lim, C. H. Jeon, K. H. Jung
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General light metal alloys are often developed in the material of transportation equipment such as automobiles and aircraft. Among the light metal alloys, magnesium is the lightest structural material with superior specific strength and many attractive physical and mechanical properties. However, magnesium alloys were difficult to obtain the mechanical properties at warm temperature. The aims of present work were to establish an analytical relation between mechanical properties and plastic flow induced by local indentation. An experimental investigation of the local strain distribution was carried out using a specially designed local indentation equipment in conjunction with ARAMIS based on digital image correlation method.Keywords: indentation, magnesium, mechanical property, lightweight material, ARAMIS
Procedia PDF Downloads 490810 Improved Performance Scheme for Joint Transmission in Downlink Coordinated Multi-Point Transmission
Authors: Young-Su Ryu, Su-Hyun Jung, Myoung-Jin Kim, Hyoung-Kyu Song
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In this paper, improved performance scheme for joint transmission is proposed in downlink (DL) coordinated multi-point(CoMP) in case of constraint transmission power. This scheme is that serving transmission point (TP) request a joint transmission to inter-TP and selects one pre-coding technique according to channel state information(CSI) from user equipment(UE). The simulation results show that the bit error rate(BER) and throughput performances of the proposed scheme provide high spectral efficiency and reliable data at the cell edge.Keywords: CoMP, joint transmission, minimum mean square error, zero-forcing, zero-forcing dirty paper coding
Procedia PDF Downloads 550809 Institutional Segmantation and Country Clustering: Implications for Multinational Enterprises Over Standardized Management
Authors: Jung-Hoon Han, Jooyoung Kwak
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Distances between cultures, institutions are gaining academic attention once again since the classical debate on the validity of globalization. Despite the incessant efforts to define international segments with various concepts, no significant attempts have been made considering the institutional dimensions. Resource-based theory and institutional theory provides useful insights in assessing market environment and understanding when and how MNEs loose or gain advantages. This study consists of two parts: identifying institutional clusters and predicting the effect of MNEs’ origin on the applicability of competitive advantages. MNEs in one country cluster are expected to use similar management systems.Keywords: institutional theory, resource-based theory, institutional environment, cultural dimensions, cluster analysis, standardized management
Procedia PDF Downloads 485808 On Fault Diagnosis of Asynchronous Sequential Machines with Parallel Composition
Authors: Jung-Min Yang
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Fault diagnosis of composite asynchronous sequential machines with parallel composition is addressed in this paper. An adversarial input can infiltrate one of two submachines comprising the composite asynchronous machine, causing an unauthorized state transition. The objective is to characterize the condition under which the controller can diagnose any fault occurrence. Two control configurations, state feedback and output feedback, are considered in this paper. In the case of output feedback, the exact estimation of the state is impossible since the current state is inaccessible and the output feedback is given as the form of burst. A simple example is provided to demonstrate the proposed methodology.Keywords: asynchronous sequential machines, parallel composition, fault diagnosis, corrective control
Procedia PDF Downloads 297807 Industry Openness, Human Capital and Wage Inequality: Evidence from Chinese Manufacturing Firms
Authors: Qiong Huang, Satish Chand
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This paper uses a primary data from 670 Chinese manufacturing firms, together with the newly introduced regressionbased inequality decomposition method, to study the effect of openness on wage inequality. We find that openness leads to a positive industry wage premium, but its contribution to firm-level wage inequality is relatively small, only 4.69%. The major contributor to wage inequality is human capital, which could explain 14.3% of wage inequality across sample firms.Keywords: openness, human capital, wage inequality, decomposition, China
Procedia PDF Downloads 422806 Factors Drive Consumers to Purchase Digital Music: An Empirical Study
Authors: Chechen Liao, Yi-Jen Huang, Yu-Ting Lu
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This study explores and complements digital aspects. In this study, we construct a research model based on the theory of reasoned action and extend it with the advantages and disadvantages of intangibility (convenience, perceived risk), some characteristics of digital products (price, variety, trialability), and factors related to entertainment (perceived playfulness) to predict what consumers really consider when they buy digital music. Eight hypotheses were tested and supported. Finally, we prove that the theory of reasoned action is still valid in the field of digital products.Keywords: digital music, digital product, theory of reasoned action
Procedia PDF Downloads 440805 Efficient Model Selection in Linear and Non-Linear Quantile Regression by Cross-Validation
Authors: Yoonsuh Jung, Steven N. MacEachern
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Check loss function is used to define quantile regression. In the prospect of cross validation, it is also employed as a validation function when underlying truth is unknown. However, our empirical study indicates that the validation with check loss often leads to choosing an over estimated fits. In this work, we suggest a modified or L2-adjusted check loss which rounds the sharp corner in the middle of check loss. It has a large effect of guarding against over fitted model in some extent. Through various simulation settings of linear and non-linear regressions, the improvement of check loss by L2 adjustment is empirically examined. This adjustment is devised to shrink to zero as sample size grows.Keywords: cross-validation, model selection, quantile regression, tuning parameter selection
Procedia PDF Downloads 435804 Metallacyclodimeric Array Containing Both Suprachannels and Cages: Selective Reservoir and Recognition of Diiodomethane
Authors: Daseul Lee, Jeong Jun Lee, Ok-Sang Jung
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Self-assembly of a series of ZnX2 (X- = Cl-, Br-, and I-) with 2,3-bis(4’-nicotinamidephenoxy)naphthalene (L) as a new bidentate pyridyl-donor ligand yields systematic metallacyclodimeric unit, [ZnX2L]2. The supramolecule constitutes a characteristically stacked forming both 1D suprachannels and cages. Weak C-H⋯π and inter-digitated π⋯π interactions are main driving forces in the formation of both suprachannels and cages. The slightly different features between the suprachannel and cage have been investigated by 1H NMR and TG analysis, which solvent quantitatively exchange within only suprachannels. Photo-unstable CH2I2 molecules are stabilized via capturing within suprachannels, which is monitored by UV-Vis spectroscopy. Furthermore, the photoluminescence intensity, from the chromophore naphthyl moiety of [ZnCl2L]2, gradually decreases with the addition of CH2I2. And washing off the CH2I2 by dichloromethane returned the PL intensity back to its approximately original signal.Keywords: metallacyclodimer, suprachannel, π⋯π interaction, molecular recognition
Procedia PDF Downloads 321803 Tolerating Input Faults in Asynchronous Sequential Machines
Authors: Jung-Min Yang
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A method of tolerating input faults for input/state asynchronous sequential machines is proposed. A corrective controller is placed in front of the considered asynchronous machine to realize model matching with a reference model. The value of the external input transmitted to the closed-loop system may change by fault. We address the existence condition for the controller that can counteract adverse effects of any input fault while maintaining the objective of model matching. A design procedure for constructing the controller is outlined. The proposed reachability condition for the controller design is validated in an illustrative example.Keywords: asynchronous sequential machines, corrective control, fault tolerance, input faults, model matching
Procedia PDF Downloads 420802 Comparison of Wind Fragility for Window System in the Simplified 10 and 15-Story Building Considering Exposure Category
Authors: Viriyavudh Sim, WooYoung Jung
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Window system in high rise building is occasionally subjected to an excessive wind intensity, particularly during typhoon. The failure of window system did not affect overall safety of structural performance; however, it could endanger the safety of the residents. In this paper, comparison of fragility curves for window system of two residential buildings was studied. The probability of failure for individual window was determined with Monte Carlo Simulation method. Then, lognormal cumulative distribution function was used to represent the fragility. The results showed that windows located on the edge of leeward wall were more susceptible to wind load and the probability of failure for each window panel increased at higher floors.Keywords: wind fragility, window system, high rise building, wind disaster
Procedia PDF Downloads 312801 The Flexural Strength of Fiber-Reinforced Polymer Cement Mortars Using UM Resin
Authors: Min Ho Kwon, Woo Young Jung, Hyun Su Seo
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A Polymer Cement Mortar (PCM) has been widely used as the material of repair and restoration work for concrete structure; however a PCM usually induces an environmental pollutant. Therefore, there is a need to develop PCM which is less impact to environments. Usually, UM resin is known to be harmless to the environment. Accordingly, in this paper, the properties of the PCM using UM resin were studied. The general cement mortar and UM resin was mixed in the specified ratio. A certain percentage of PVA fibers, steel fibers and mixed fibers (PVA fiber and steel fiber) were added to enhance the flexural strength. The flexural tests were performed in order to investigate the flexural strength of each PCM. Experimental results showed that the strength of proposed PCM using UM resin is improved when they are compared with general cement mortar.Keywords: polymer cement mortar, UM resin, compressive strength, PVA fiber, steel fiber
Procedia PDF Downloads 342800 Forecasting of Grape Juice Flavor by Using Support Vector Regression
Authors: Ren-Jieh Kuo, Chun-Shou Huang
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The research of juice flavor forecasting has become more important in China. Due to the fast economic growth in China, many different kinds of juices have been introduced to the market. If a beverage company can understand their customers’ preference well, the juice can be served more attractively. Thus, this study intends to introduce the basic theory and computing process of grapes juice flavor forecasting based on support vector regression (SVR). Applying SVR, BPN and LR to forecast the flavor of grapes juice in real data, the result shows that SVR is more suitable and effective at predicting performance.Keywords: flavor forecasting, artificial neural networks, Support Vector Regression, China
Procedia PDF Downloads 492799 Big Data Analysis with RHadoop
Authors: Ji Eun Shin, Byung Ho Jung, Dong Hoon Lim
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It is almost impossible to store or analyze big data increasing exponentially with traditional technologies. Hadoop is a new technology to make that possible. R programming language is by far the most popular statistical tool for big data analysis based on distributed processing with Hadoop technology. With RHadoop that integrates R and Hadoop environment, we implemented parallel multiple regression analysis with different sizes of actual data. Experimental results showed our RHadoop system was much faster as the number of data nodes increases. We also compared the performance of our RHadoop with lm function and big lm packages available on big memory. The results showed that our RHadoop was faster than other packages owing to paralleling processing with increasing the number of map tasks as the size of data increases.Keywords: big data, Hadoop, parallel regression analysis, R, RHadoop
Procedia PDF Downloads 435798 Remanufacturing and Integrity Assessment of a 27-Year-Old 25kV Gas Insulated Switchgear: A Comprehensive Study on Dismantling, Inspection, and Testing
Authors: Yechan Kim, Bonhyuk Ku, Minkyung Jung, Hyoungku Kang
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This study presents the remanufacturing of a 25kV gas insulated switchgear (GIS) that operated indoors for 27 years before being decommissioned due to aging. The research involved a detailed process of dismantling, visual inspection, component-wise examination, and various testing methodologies to assess the equipment's condition. The focus was on evaluating the GIS's integrity and feasibility for remanufacturing. The results highlight the potential of remanufacturing in extending the life of electrical power equipment, offering insights into the best practices, challenges, and technical considerations of such an undertaking. This contributes to a sustainable approach in the power industry, emphasizing the reuse and restoration of aging equipment.Keywords: remanufacturing, dismantling, gas insulated switchgear, sustainability, life extension
Procedia PDF Downloads 75797 Microstructure and Hot Deformation Behavior of Fe-20Cr-5Al Alloy
Authors: Jung-Ho Moon, Tae Kwon Ha
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Abstract—High temperature deformation behavior of cast Fe-20Cr-5Al alloy has been investigated in this study by performing tensile and compression tests at temperatures from 1100 to 1200oC. Rectangular ingots of which the dimensions were 300×300×100 in millimeter were cast using vacuum induction melting. Phase equilibrium was calculated using the FactSage®, thermodynamic software and database. Tensile strength of cast Fe-20Cr-5Al alloy was 4 MPa at 1200oC. With temperature decreased, tensile strength increased rapidly and reached up to 13 MPa at 1100oC. Elongation also increased from 18 to 80% with temperature decreased from 1200oC to 1100oC. Microstructure observation revealed that M23C6 carbide was precipitated along the grain boundary and within the matrix.Keywords: 20 Cr-5Al ferritic stainless, high temperature deformation, aging treatment, microstructure, mechanical properties
Procedia PDF Downloads 448796 Wind Fragility of Window Glass in 10-Story Apartment with Two Different Window Models
Authors: Viriyavudh Sim, WooYoung Jung
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Damage due to high wind is not limited to load resistance components such as beam and column. The majority of damage is due to breach in the building envelope such as broken roof, window, and door. In this paper, wind fragility of window glass in residential apartment was determined to compare the difference between two window configuration models. Monte Carlo Simulation method had been used to derive damage data and analytical fragilities were constructed. Fragility of window system showed that window located in leeward wall had higher probability of failure, especially those close to the edge of structure. Between the two window models, Model 2 had higher probability of failure, this was due to the number of panel in this configuration.Keywords: wind fragility, glass window, high rise building, wind disaster
Procedia PDF Downloads 254795 A Pedagogical Study of Computational Design in a Simulated Building Information Modeling-Cloud Environment
Authors: Jaehwan Jung, Sung-Ah Kim
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Building Information Modeling (BIM) provides project stakeholders with various information about property and geometry of entire component as a 3D object-based parametric building model. BIM represents a set of Information and solutions that are expected to improve collaborative work process and quality of the building design. To improve collaboration among project participants, the BIM model should provide the necessary information to remote participants in real time and manage the information in the process. The purpose of this paper is to propose a process model that can apply effective architectural design collaborative work process in architectural design education in BIM-Cloud environment.Keywords: BIM, cloud computing, collaborative design, digital design education
Procedia PDF Downloads 429794 Preparation and Characterization of α–Alumina with Low Sodium Oxide
Authors: Gyung Soo Jeon, Hong Bae Kim, Chi Jung Oh
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In order to prepare the α-alumina with low content of sodium oxide from aluminum trihydroxide as a reactant, three kinds of methods were employed as follows; the mixture of Chamotte (aggregate composed of silica and alumina), ammonium chloride and aluminum fluoride with aluminum trihydroxide under 1600°C, respectively. The sodium oxide in α-alumina produced above methods was analyzed by XRF and the particle size distribution was determined by particle size analyzer, and the specific surface area of α-alumina was measured by BET method, and phase of α-alumina produced was confirmed by XRD. Acknowledgement: This research was supported by Development Program of Technical Innovation funded by Korea Technology and Information Promotion Agency for SMEs (KTIP-2016-S2401821).Keywords: α-alumina, sodium oxide, aluminum trihydroxide, Chamotte, ammonium chloride, aluminum fluoride
Procedia PDF Downloads 313793 Effect of Flow Holes on Heat Release Performance of Extruded-Type Heat Sink
Authors: Jung Hyun Kim, Gyo Woo Lee
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In this study, the enhancement of the heat release performance of an extruded-type heat sink to prepare the large-capacity solar inverter thru the flow holes in the base plate near the heat sources was investigated. Optimal location and number of the holes in the baseplate were determined by using a commercial computation program. The heat release performance of the shape-modified heat sink was measured experimentally and compared with that of the simulation. The heat sink with 12 flow holes in the 18-mm-thick base plate has a 8.1% wider heat transfer area, a 2.5% more mass flow of air, and a 2.7% higher heat release rate than those of the original heat sink. Also, the surface temperature of the base plate was lowered 1.5°C by the holes.Keywords: heat sink, forced convection, heat transfer, performance evaluation, flow holes
Procedia PDF Downloads 531792 Investigation on Fischer-Tropsch Synthesis over Cobalt-Gadolinium Catalyst
Authors: Jian Huang, Weixin Qian, Haitao Zhang, Weiyong Ying
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Cobalt-gadolinium catalyst for Fischer-Tropsch synthesis was prepared by impregnation method with commercial silica gel, and its texture properties were characterized by BET, XRD, and TPR. The catalytic performance of the catalyst was tested in a fixed bed reactor. The results showed that the addition of gadolinium to the cobalt catalyst might decrease the size of cobalt particles, and increased the dispersion of catalytic active cobalt phases. The carbon number distributions for the catalysts was calculated by ASF equation.Keywords: Fischer-Tropsch synthesis, cobalt-based catalysts, gadolinium, carbon number distributions
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