• 한국추진공학회지
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• 제15권2호
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• pp.50-55
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• 2011

고성능 로켓엔진에 사용되는 다단연소싸이클의 주요 부품인 예연소기 개발 과정에서 브레이징 접합부를 모사하는 시편에 대한 강도 시험을 수행하고 유한 요소 해석 결과와 비교하였다. 진공 브레이징 되는 헤드의 산화제 분사기 및 진공 가압 브레이징되는 냉각채널 접합부를 모사할 수 있는 시편을 설계 및 제작하고 파단 시험을 수행하였다. 두 시편 모두 접합부가 아닌 모재에서 파단이 발생하였다. 그리고 해석을 통하여 예측된 파단 부위와 변형율이 시험 결과와 잘 일치하였다.

• Smart Structures and Systems
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• 제3권4호
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• pp.475-494
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• 2007

This paper deals with the development of an innovative distributed construction system based on smart prefabricated concrete elements for the real-time condition assessment of civil infrastructure. So far, two reduced-scale prototypes have been produced, each consisting of a $0.2{\times}0.3{\times}5.6$ m RC beam specifically designed for permanent instrumentation with 8 long-gauge Fiber Optic Sensors (FOS) at the lower edge. The sensing system is Fiber Bragg Grating (FBG)-based and can measure finite displacements both static and dynamic with a sample frequency of 625 Hz per channel. The performance of the system underwent validation in the laboratory. The scope of the experiment was to correlate changes in the dynamic response of the beams with different damage scenarios, using a direct modal strain approach. Each specimen was dynamically characterized in the undamaged state and in various damage conditions, simulating different cracking levels and recurrent deterioration scenarios, including cover spalling and corrosion of the reinforcement. The location and the extent of damage are evaluated by calculating damage indices which take account of changes in frequency and in strain-mode-shapes. The outcomes of the experiment demonstrate how the damage distribution detected by the system is fully compatible with the damage extent appraised by inspection.

• 한국전산유체공학회지
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• 제3권2호
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• pp.39-51
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• 1998

This paper describes the analysis of flow field around an automobile. The governing equations of the 3-D unsteady incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror. To validate the capability of simulating the flow around a ground vehicle, the flows around the Ahmed body with 12.5$^{\circ}$ and 30$^{\circ}$ of slant angles are simulated and good agreements with experiment and other numerical results are achieved. To validate Chimera grid technique, the flow field around a cylinder was also calculated. The computed results are also well agreed with other numerical results and experiment. After code validations, the flow phenomena around the ground vehicle are evidently shown. The flow around the side-view mirror is also well simulated using the Chimera grid technique.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.123-128
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• 1992

In Experiment 1, when fasted chicks were fed diets containing various sources of protein for 3 days, the activities of lipogenic enzymes (acetyl-CoA carboxylase, fatty acid synthetase, citrate cleavage enzyme and malic enzyme) in the liver of growing chicks were significantly lower in the soybean protein or gluten diet than in the casein or fish protein diet. Triglycride contents of the liver and plasma of chicks fed the casein or fish protein diet were significantly lower than that of those fed soybean protein or gluten diet. In Experiment 2, the effects of dietary amino acid mixture simulating casein or protein on the activities of hepatic lipogenic enzymes were examined. The activities of acetyl-CoA carboxylase and fatty acid synthetase in the liver of chicks fed the casein diet were significantly higher than that of those fed the soybean protein diet or two diets of amino acid mixtures. Furthermore, there were no significant differences between the two diets of amino acid mixture based on casein or soybean protein. However, the activities of malic enzyme and citrate cleavage enzyme tended to be lower in the soybean-type amino acid diet than in the casein-type amino acid diet. Thus, some effects can be ascribed to the protein itself and some to the amino acid composition of the protein sources.

• Journal of Welding and Joining
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• 제31권5호
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• pp.7-14
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• 2013

The legitimacy of dominating factor in the high accuracy prediction of welding distortion was investigated for butt welding and fillet welding. When out-of-plane distortion was measured by the experiment objecting to butt welding, if tack welding was easily performed, the position of a neutral axis was variously changed by the irregularity. Then, there have been a case that out-of-plane distortion was generated in the unexpected direction. This case should be especially noted. New model for the experiment was proposed so as to solve this problem. As it was elucidated by the case of fillet welding, it was verified that the analysis should be carried out with satisfying the yield condition (especially at high temperature above 700 degree Celsius) and with closely simulating the penetration shape (heat input in weld metal) in order to solve the proposition that is the high accuracy prediction of welding distortion. It was confirmed that residual stress is highly predicted because welding distortion is highly predicted, too.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.115-115
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• 1999

To demonstrate the applicability of RELAP5 to the prediction of the onset offlooding in the hot leg at the reflux condensation phase during mid-loop operation, numerical analysis is performed for the counter-current flow in a horizontal pipe with the inclined riser using the RELAP5/MOD3.2.2b code. It is found that the RELAP5, simulating the CCFL phenomena using interfacial friction along with the flow regime map in the horizontal pipe, produces unsatisfactory results. Under the CCFL condition, it is observed that large oscillation exists in the flow rate, void fraction, and etc. and the liquid flow rate is much lower than that predicted by the CCFL model measured in the experiment. The CCFL model of RELAP5 for the vertical volume is extended to the model for the horizontal and inclined volumes. The horizontal volume flow regime map and interfacial friction model coupled to the CCFL model are modified. And a new correlation developed from Kang's experiment is implemented to the CCFL model of RELAP5. With this modified RELAP5, the analysis of CCFL phenomena in the horizontal pipe and hot leg geometry is performed, and produces reasonable results in comparison with experimental data.

• 대한안전경영과학회지
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• 제15권1호
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• pp.271-281
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• 2013

In the trend toward globalization, cross-cultural teams in organizations are becoming more and more common. In particular, the influence of China and Western Europe on the global economy is getting increased. With this trend, it is important to understand cross-cultural characteristics for group decision making in managerial environments. This study aims at analyzing cross-cultural differences between China and Western Europe in light of the effect of group discussion in group decision making. An experiment simulating a decision of a car purchase was conducted. A total of 48 subjects (24 Chinese and 24 Western Europeans) assigned in decision groups were asked to judge relative importance ratios of nine factors affecting their purchase decisions using the AHP program developed for the experiment. Three dependent variables (consistency, satisfaction, and consensus) were measured. Chinese were slightly more consistent than Western Europeans in discussion-involved group decision making. In terms of decision satisfaction, Western Europeans were more satisfied with discussion-included decisions than discussion-excluded decisions. Chinese, on the contrary, did not show a significant difference. There was no significant difference between two cultures in decision consensus.

• 유통과학연구
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• 제19권11호
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• pp.59-68
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• 2021

Purpose: The Covid-19 pandemic has had excessively severe impacts on all the nodes and edges of any supply chain due to changes in consumer behaviours and lockdown restrictions from governments among countries. This article aims to provide a simulating experiment on how a supply chain deals with supply disruption risks by flexibility in the inventory level of each sector as a buffer considering the overall cost to fulfil demand in the market. Research design, data and methodology: Agent-based simulation techniques are used to determine the cost-efficiency and customer waiting time related to varying inventory levels of each member in the supply chain when using inventory buffers. Findings: This study has shown that any sudden changes in the inventory level of each sector are likely to impact the rest of the supply chain. Among all sectors, the wholesaler will be impacted more severely than others. Also, the manufacturing sector is the most suitable node to adjust inventory depending on its manufacturing ability. Conclusion: The findings of the study provide insightful implications for decision-makers to adjust inventory levels and policymakers to maintain manufacturing activities in the context of the pandemic restrictions to deal with the excessive demand and potential supply disruption risks.

• 대한토목학회논문집
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• 제39권1호
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• pp.175-181
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• 2019

근사 Riemann 해법으로 흐름률을 계산할 때 Hwang의 기법을 이용하여 불연속 지형에 따른 흐름 저항으로서 계단에 따른 정수압, 추력, 벽 반사 등을 검토하였다. 광정 위어 실험과 비교했을 때 추력을 이용하여 모의한 결과가 셋 중에서 가장 우수하였다. 계단에 따른 추력을 고려한 Hwang의 기법을 측면 위어 실험에 적용하였으며, 실험 결과와 잘 일치함을 확인하였다. 기존 수심적분 모형에 비해 정확도 저하가 조금 있으나, 계산 시간을 약 20 %로 줄일 수 있어 감수할 만한 수준이었다.

• Corrosion Science and Technology
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• 제21권5호
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• pp.348-359
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• 2022

Interest in electric vehicle is on the rise due to global eco-friendly policies. To improve the efficiency of electric vehicles, it is essential to reduce weights of components. Since electric vehicles have various electronic equipment, the research on stray current corrosion is required. In this research, a galvanostatic corrosion experiment was performed on 6061-T6 Al alloy for electric vehicle battery housing using chloride concentration and applied current density as variables in a solution simulating an acid rain environment. As a result of the experiment, when chloride concentration and applied current density were increased, corrosion damage became larger. In particular, pitting damage was dominant at an applied current density of 0.1 mA/cm². Pitting damage over the entire surface was found at a current density of 1.0 mA/cm². In conclusion, chloride concentration had a relatively large effect on localized corrosion. The applied current density had a great effect on uniform corrosion. However, in the case of applied current density, localized corrosion was also greatly affected by interaction with chloride.