• Korean Journal of Construction Engineering and Management
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• v.15 no.3
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• pp.103-112
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• 2014

Since recent construction projects become larger and complicated, the level of difficulty of management skill is rising, and the risk is increasing accordingly so the necessity of improving management skill of projects is increasing. In order to solve this problem, Construction Management system was preferentially introduced in construction projects but in case of domestic construction industry, separate contracts by business boundary are being made so the actual state is that the function of the Construction Management system is not properly operated over the overall projects. The partial operation of Construction Management system like this may impose many restrictions on converged and combined projects such as smart grid and intelligent buildings etc. in the future. For improvement of management skill of domestic construction projects, the competence of project management skill by work areas that can overcome heterogeneity of the current project management skill shall be secured, and any factor that impedes cooperation ability shall be found and that shall be solved. Therefore, the difference of work competency of project management system of construction and electrical construction is to be analyzed by utilizing IPA model in this study, and a plan to introduce the project management system of electrical construction for efficient operation of projects is to be looked into.

• Journal of Korea Port Economic Association
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• v.33 no.2
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• pp.53-82
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• 2017

The purpose of this study is to show the clustering trend and compare empirical results, as well as to choose the clustering ports for 3 Korean ports (Busan, Incheon, and Gwangyang) by using meta-frontier DEA (Data Envelopment Analysis) and integer models on 38 Asian container ports over the period 2005-2014. The models consider 4 input variables (birth length, depth, total area, and number of cranes) and 1 output variable (container TEU). The main empirical results of the study are as follows. First, the meta-frontier DEA for Chinese seaports identifies as most efficient ports (in decreasing order) Shanghai, Hongkong, Ningbo, Qingdao, and Guangzhou, while efficient Korean seaports are Busan, Incheon, and Gwangyang. Second, the clustering results of the integer model show that the Busan port should cluster with Dubai, Hongkong, Shanghai, Guangzhou, Ningbo, Qingdao, Singapore, and Kaosiung, while Incheon and Gwangyang should cluster with Shahid Rajaee, Haifa, Khor Fakkan, Tanjung Perak, Osaka, Keelong, and Bangkok ports. Third, clustering through the integer model sharply increases the group efficiency of Incheon (401.84%) and Gwangyang (354.25%), but not that of the Busan port. Fourth, the efficiency ranking comparison between the two models before and after the clustering using the Wilcoxon signed-rank test is matched with the average level of group efficiency (57.88 %) and the technology gap ratio (80.93%). The policy implication of this study is that Korean port policy planners should employ meta-frontier DEA, as well as integer models when clustering is needed among Asian container ports for enhancing the efficiency. In addition Korean seaport managers and port authorities should introduce port development and management plans accounting for the reference and clustered seaports after careful analysis.

• Journal of Information Display
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• v.9 no.4
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• pp.21-29
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• 2008

We studied both the wavelength and intensity dependent photo-responses (photofield-effect) in amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). During the a-IGZO TFT illumination with the wavelength range from $460\sim660$ nm (visible range), the off-state drain current $(I_{DS_off})$ only slightly increased while a large increase was observed for the wavelength below 400 nm. The observed results are consistent with the optical gap of $\sim$3.05eV extracted from the absorption measurement. The a-IGZO TFT properties under monochromatic illumination ($\lambda$=420nm) with different intensity was also investigated and $I_{DS_off}$ was found to increase with the light intensity. Throughout the study, the field-effect mobility $(\mu_{eff})$ is almost unchanged. But due to photo-generated charge trapping, a negative threshold voltage $(V_{th})$ shift is observed. The mathematical analysis of the photofield-effect suggests that a highly efficient UV photocurrent conversion process in TFT off-region takes place. Finally, a-IGZO mid-gap density-of-states (DOS) was extracted and is more than an order of magnitude lower than reported value for hydrogenated amorphous silicon (a-Si:H), which can explain a good switching properties observed for a-IGZO TFTs.

• The Korean Journal of Financial Management
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• v.15 no.1
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• pp.1-30
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• 1998

본(本) 연구(硏究)는 한국증권시장에서 대표적 대용시장(代用市場)포트폴리오인 한국종합주가지수(韓國綜合株價指數)와 동일가중지수(同一加重指數)의 효율성에 대한 검증을 Hansen(1982)의 다변량의 GMM에 의하여 실시하고자 하였다. 이를 위하여 먼저, 주식수익률자료(株式收益率資料)에 근거한 산업별(産業別)포트폴리오수익률과 초과시장수익률모형(超過市場收益率模型)의 오차항(誤差項)이 정규분포(正規分布)를 벗어남을 증명함으로써 GMM검증방법(檢證方法)의 정당성을 찾고자 하였다. 정규분포에 대한 검증방법(檢證方法)으로서 왜도와 첨도의 검증과 이를 결합한 Jarque-Bera(1980)검증(檢證)을 실시하였다. 둘째로, Hansen(1982)의 GMM을 대용시장(代用市場)포트폴리오의 효율성(效率性) 검증(檢證)에 적용하는 방법에 대한 연구들인 Mackinlay-Richardson(1991), Harvey-Zhou(1993)와 Campbell-Lo-Mackilay(1997) 등을 기초로하여 이들의 방법론을 개선한 3가지의 효율성(效率性) 검증방법(檢證方法)을 제시하였다. 셋째로, 이상의 검증방법(檢證方法)들을 토대로 1980년 1월부터 1997년 6월까지 월별주식수익률(月別株式收益率)의 자료(資料)를 11업종으로 분류하여 산업별(産業別)포트폴리오수익률(收益率)과 초과시장수익률모형(超過市場收益率模型)에 의한 오차항(誤差項)이 정규분포(正規分布)를 따르는지와 아울러 대용시장(代用市場)포트폴리오의 효율성을 검증하였다. 검증결과(檢證結果), 산업별(産業別)포트폴리오수익률과 오차항(誤差項)은 대부분 정규성이 기각(棄却)되어 GMM검증방법(檢證方法)의 정당성이 입증되었다. 따라서 GMM에 의한 효율성(效率性)을 검증한 결과, 한국종합주가지수(韓國綜合株價指數)의 경우에는 평균-분산(平均-分散)프론티어(mean-variance frontier)상(上)에서의 대용시장(代用市場)포트폴리오의 효율성(效率性)은 기각(棄却) 할 수 없는 것으로 나타났으나 평균수익률(平均收益率)이 GMVP의 수익률보다 낮았기 때문에 효율적(效率的) 프론티어(efficient frontier)상(上)의 대용시장(代用市場)포트폴리오의 효율성(效率性)은 기각(棄却)되어 대용시장지수로서의 문제점이 있는 것으로 나타났다. 그러나 동일가중지수(同一加重指數)는 평균수익률이 GMVP의 수익률보다 높을 뿐만아니라 효율적(效率的) 프론티어상(上)의 대용시장(代用市場)포트폴리오의 효율성(效率性)도 채택되어 한국종합주가지수(韓國綜合株價指數)보다 우월한 지수(指數)인 것으로 나타났다.

• Korean Journal of Community Nutrition
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• v.12 no.2
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• pp.178-188
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• 2007

This study was performed to suggest a new efficiency measurement indicator is necessary for evaluating management efficiency of food service operations in contract-managed foodservice companies, to distinguish efficient food service providers and inefficient ones by measuring comparative efficiency among food service operations, and to provide guidance for effective management through showing benchmarking targets for improving inefficient food service providers. The subjects of this study were the 93 B&I foodservice Operations of a domestic contract food service company. The analysis was conducted using CCR model in DEA model. A software, 'Frontier analyst', was used for the analysis. Based on the results derived from comparison of efficiency evaluation classified by providers with use of DEA, it was possible to identify efficient food providers and inefficient providers, and subsequently provide benchmarking guidelines for improvement of the inefficient groups. In analyzing the differences between the results of DEA efficiency evaluation by detailed operation status of food service providers, there was significant difference of efficiency outcomes in terms of contract types, while there was no significant difference in terms of business condition.

• The Journal of Fisheries Business Administration
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• v.47 no.1
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• pp.63-86
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• 2016

The purpose of this study is to investigate production efficiency of Oceans and Fisheries Human Resources Development Programs Efficiency using Bootstrap-DEA. The study extracts 33 officials curriculum, 11 fisheries managers curriculum for its analytical. First, the study estimates technical, pure technical, and scale efficiency of each curriculums based on traditional DEA under the assumption of CRS and VRS. 8(official 7, managers 1) curriculums are identified as efficient DMUs under the CCR-model, and 13(official 10, managers 3) under the BCC-model. We provide inputs that allow inefficient curriculum to be efficient DMUs on a production frontier, and a reference set for their bench-marking. Second, rank test, Wilcoxon-Mann-Whitney test to find a statistical significance of heterogeneity existing in efficiences between Bootstrap-DEA tenical vs Bootstrap-DEA pure technical was no significant difference. We have identified that G10, 11, 12 13, 25, 31, 33, 39 curriculums are the most efficiently produced in the technical and pure technical efficiency. Also we managed to measure the inefficiency which exists in efficiently produced curriculums when estimating the bias corrected efficiency scores. In Technical efficiency, Operation and facility was significant at the 10%. In Pure technical efficiency, facility was significant at the 10%.

• Industrial Engineering and Management Systems
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• v.12 no.2
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• pp.151-160
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• 2013

In the past decades, several algorithms based on evolutionary approaches have been proposed for solving job shop scheduling problems (JSP), which is well-known as one of the most difficult combinatorial optimization problems. Most of them have concentrated on finding optimal solutions of a single objective, i.e., makespan, or total weighted tardiness. However, real-world scheduling problems generally involve multiple objectives which must be considered simultaneously. This paper proposes an efficient particle swarm optimization based approach to find a Pareto front for multi-objective JSP. The objective is to simultaneously minimize makespan and total tardiness of jobs. The proposed algorithm employs an Elite group to store the updated non-dominated solutions found by the whole swarm and utilizes those solutions as the guidance for particle movement. A single swarm with a mixture of four groups of particles with different movement strategies is adopted to search for Pareto solutions. The performance of the proposed method is evaluated on a set of benchmark problems and compared with the results from the existing algorithms. The experimental results demonstrate that the proposed algorithm is capable of providing a set of diverse and high-quality non-dominated solutions.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.239-247
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• 2021

Conventional banks are often considered more efficient than Islamic banks because they have been operating for decades, but Islamic banks have shown rapid development recently. Therefore, this study mainly aims to compare the level of efficiency of conventional banks and Islamic banks and which ones have the best level of efficiency. This study employs panel data using Stochastic Frontier Analysis (SFA) as the data analysis technique. The data used is annual data from 13 conventional banks and 13 Islamic banks in Indonesia during the 2014-2019 period. The result shows no significant difference in the efficiency of conventional banks and Islamic banks. This result is presumably influenced by the small size of the bank and the total number of banks used in the study. The data used in the study is limited to the period from 2014 to 2019. The variables utilized are also limited to the availability of financial report data which is publicly published. This study provides additional empirical evidence regarding conventional banks' and Islamic banks' efficiency in Indonesian banking by using the latest data. While theoretically, Islamic banks are expected to be more efficient than conventional banks, this study did not find any strong support for the case in Indonesia during the observation period.

• Journal of Information Processing Systems
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• v.18 no.5
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• pp.637-649
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• 2022

Investors aim to increase their profitability by investing in the stock market. An adroit strategy for minimizing related risk lies through diversifying portfolio operationalization. In this paper, we propose a six-step stocks portfolio selection model. This model is based on data mining clustering techniques that reflect the ensuing impact of the political, economic, legal, and corporate governance in Mongolia. As a dataset, we have selected stock exchange trading price, financial statements, and operational reports of top-20 highly capitalized stocks that were traded at the Mongolian Stock Exchange from 2013 to 2017. In order to cluster the stock returns and risks, we have used k-means clustering techniques. We have combined both k-means clustering with Markowitz's portfolio theory to create an optimal and efficient portfolio. We constructed an efficient frontier, creating 15 portfolios, and computed the weight of stocks in each portfolio. From these portfolio options, the investor is given a choice to choose any one option.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.306-309
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• 2005

We consider the multi-objective optimization of a multi-service arrayed-waveguide grating-based single-hop metro WDM network with the two conflicting objectives of maximizing throughput while minimizing delay. We develop and evaluate a genetic algorithm based methodology for finding the optimal throughput-delay tradeoff curve, the so-called Pareto-optimal frontier. Our methodology provides the network architecture and the Medium Access Control protocol parameters that achieve the Pareto-optima in a computationally efficient manner. The numerical results obtained with our methodology provide the Pareto-optimal network planning and operation solution for a wide range of traffic scenarios. The presented methodology is applicable to other networks with a similar throughput-delay tradeoff.