• 유통과학연구
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• 제10권7호
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• pp.13-22
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• 2012

The effect of the September 2008 global financial crisis weighed heavily on stock markets around the world. The purpose of this study is to empirically investigate the impact of the crisis on Amman Stock Exchange. Event study methodology has been adopted on a period of 24 months, from January 2008 to December 2009. Monthly average abnormal returns across a sample of 52 industrial and services companies have been tested separately. The results reveal that Amman Stock Exchange experienced significant negative abnormal returns in the fourth quarter of the year 2008. However, there were no significant abnormal returns observed thereafter. This means that Amman Stock Exchange managed to overcome its adverse consequences. Since the event study tests for market efficiency, as well, the results show that Amman Stock Exchange reaction is consistent with the semi-strong form of the efficient market hypothesis.

• International Journal of Control, Automation, and Systems
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• 제4권5호
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• pp.575-591
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• 2006

In a previous research, we presented the Grid Method and confirmed it as a systematic and efficient problem formulation method for the task-oriented design of robot kinematics. However, our previous research was limited in two ways. First, it gave only a local optimum due to its use of a local optimization technique. Second, it used constant weights for a cost function chosen by the manual weights tuning algorithm, thereby showing low efficiency in finding an optimal solution. To overcome these two limitations, therefore, this paper presents a global optimization technique and an adaptive weights tuning algorithm to solve a formulated problem using the Grid Method. The efficiencies of the proposed algorithms have been confirmed through the kinematic design examples of various robot manipulators.

• Coupled systems mechanics
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• 제6권4호
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• pp.501-522
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• 2017

This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.

• Steel and Composite Structures
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• 제20권3호
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• pp.693-718
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• 2016

This paper presents a finite element procedure based on Bridging multi-scale method (BMM) in order to incorporate the effect of local/cross-sectional deformations (e.g., flange local buckling and web crippling) on the global behaviour of thin-walled members made of fibre-reinforced polymer composite laminates. This method allows the application of local shell elements in critical regions of an existing beam-type model. Therefore, it obviates the need for using computationally expensive shell elements in the whole domain of the structure, which is otherwise necessary to capture the effect of the localized behaviour. Consequently, highly accurate analysis results can be achieved with this method by using significantly smaller finite element model, compared to the existing methods. The proposed method can be used for composite polymer laminates with arbitrary fibre orientation directions in different layers of the material, and under various loading conditions. Comparison with full shell-type finite element analysis results are made in order to illustrate the efficiency and accuracy of the proposed technique.

• 전기학회논문지
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• 제65권9호
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• pp.1618-1625
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• 2016

Electric motor systems account for more than half of all electric systems and the amount of energy consumption of those is almost 70 percent of total energy consumption of electric motor systems in industry. As electric motor systems are very responsible for global electricity savings and environment protection. Many international organizations are supporting standards and policy development processes to improve the efficiency of electric motor systems. Many standards are being developed at technical committee of IEC that has been required in order to support the implementation of efficiency regulations. High efficiency standards and levels for electric motor systems are slowly being introduced and compulsory in many countries. Therefore understanding the international efficiency evaluation standards and the regulation of electric motor systems of each country is important. This paper presents the current status and trends of international evaluation standards and regulations about the efficiency of electric motor systems.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2008년도 추계 공동 국제학술대회
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• pp.316-321
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• 2008

In the present emerging global economy, as the focus is shifted from manufacturing to service sector, the efficiency of service operations is crucial for the county's sustainable growth and development. As one of the fastest growing service sector industries in South Korea, the call center has become an inevitable part of customer service for most companies. Despite of the strategic importance of the call center, there has been no empirical study on the efficiency of call center service operations in the literature. The main purpose of this study is to evaluate the technical efficiency of call center services so as to not only identify the current status of call center service operations, but also suggest ways to improve service operations efficiency. For this purpose, we apply a non-parametric efficiency measurement method, DEA (Data Envelopment Analysis), to domestic call centers in order to compare their relative efficiency. Based on DEA evaluations, we provided specific directions for the inefficient call centers to possibly improve their operation efficiencies. It is expected that the measurement methods suggested in this study can be applied to various issues such as service KS certification, service operations management, and the productivity analysis of service personnel.

• 한국태양에너지학회 논문집
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• 제32권4호
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• pp.65-70
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• 2012

Each country has implemented various environmental policies to prevent natural disasters and destruction of ecosystem caused by global wanning. The republic of Korea also was performed building energy efficiency rating certification system as part of paradigm of 'Low carbon green growth' since 2010. However, the status on the building energy efficiency rating certification system has not been analyzed. In this study, We analyzed the elements affecting the energy efficiency of small office buildings focusing the status and certification cases of the building energy efficiency rating system. As a result, it is judged that thermal performance contribution of the building envelope is not high in the buildings certificated the first grade of the building energy efficiency rating system.

• 국제지역연구
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• 제22권2호
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• pp.61-91
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• 2018

본 연구는 신용보증제도가 효과성 높은 중소기업지원 수단의 하나로서, 그 성과를 업무성격이 다른 국내 공공기관들과 비교하는 것보다 매우 유사한 형태로 운영되고 있는 일본, 대만 신용보증기관과의 글로벌 효율성 비교가 훨씬 유용할 수 있다는 측면에서 3개국 70개 기관의 2016년도 효율성을 DEA모형과 초효율성 모형을 통해 분석하였다. 분석결과, 우리나라 신용보증기관들의 효율성이 일본에 비해 다소 높은 것으로 나타났으며, 효율적으로 운영되고 있는 DMU의 숫자도 비교적 적정한 것으로 분석되었다. 초효율성점수는 히로시마, 대만SMEG, 부산, 지바, 시즈오카, 울산, 기보 순으로 나타났다. 또한, 대부분의 신용보증기관들은 규모수익상태가 체증규모수익상태에 있는 것으로 분석되어 적정수준의 투입 증가전략을 추진하는 것이 효율적일 수 있는 것으로 판단된다. 또한, 우리나라와 일본간 효율성 격차는 통계적으로도 유의한 차이를 보였다. 정책적 시사점으로는 첫째, 일본 신용보증제도의 동향에 대한 주기적 분석이 필요하며, 둘째, 신용보증규모가 국가경제 및 중소기업정책에 미치는 영향을 파악하여야 하고, 셋째, 효율성 결정요인에 관한 분석이 필요하며, 넷째, 비효율의 원인을 고려하여 효율성 개선전략의 방향성을 정립하여야 하고, 다섯째, 다각적인 측면에서 효율성 측정이 이루어질 필요가 있음을 제시하였다.

• 한국항만경제학회지
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• 제27권2호
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• pp.261-273
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• 2011

현재의 물류산업은 인수 합병을 통한 거대기업이 출현하고 있으며 세계물류시장은 계속 경쟁적으로 진행되고 있다. 글로벌물류기업은 세계 각지역에 생산에서 폐기까지 물류관리를 효율적으로 진행하기 위하여 종합적인 물류서비스를 수행한다. 종합물류기업으로 성장하기 위해서는 종합물류기업의 솔루션을 효과적으로 제시할 수 있는 전문적 물류지식과 정보기술을 가지고 있다. 정부는 글로벌 경쟁력 있는 물류기업이 육성을 위하여 수직 수평적으로 통합하였다 정부가 동북아 물류시장의 중심지화 전략을 추구하기 위하여 종합물류기업 인증제도를 시행한지 6년이 경과 되었다. 본 연구는 CCR 모형과 BCC 모형을 이용하여 대형종합물류기업 9개에 관하여 효율성을 비교 분석하였다. 우리나라는 현재31개 종합물류기업 가운데 9개 기업은 단독으로 종합물류기업으로 인증을 받고 있다. 효율성이 100%로 나타난 가장 효율적인 종합물류기업은 글로비스이며 2005-2010년에 6년동안 계속적으로 가장 효율성이 높았다. 글로비스는 2010년에 현재의 투입요소의 조합을 최소 6배 이상 늘려도 100%의 효율성을 유지할 수 있는 것으로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.283-286
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• 2002

The mixing of fuel and oxidizer and each mass distribution of unlike split triplet(F-O-O-F) injector for liquid rocket which are known to affect the combustion efficiency significantly, has been investigated using PLLIF technique. Experiment is conducted to investigate the effect of mixture ratio(MiR), momentum ratio(MoR) and impinging angle on mixing efficiency. The mixing efficiency, which is introduced by Rupe, gives the global chracteristic of spray mixing. Experiment far comparison with triplet injector(F-O-F), which has same momentum ratio and impinging angle with split triplet injector is conducted.