• International Journal of Ocean System Engineering
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• v.3 no.2
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• pp.77-89
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• 2013

The propeller performance has been investigated using a benchmark Duisburg Test Case ship with RANSE. First, the hydrodynamic characteristics of propeller in case of open water have been analyzed by a commercial CFD program and the results are compared with those of experimental data. Later, the flow around the bare hull has been solved and the frictional resistance value and form factor of the ship have been obtained and compared with those of ITTC57 formulation and experimental results for validation. The free surface effect has been ignored. A good agreement has been obtained between the results of RANSE and experiments at both stages. Then the ship - propeller interaction problem was solved by RANSE and the differences in thrust, torque and efficiency of propeller as compared with the open-water numerical results have been discussed.

• 한국IT서비스학회:학술대회논문집
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• 2007.11a
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• pp.679-684
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• 2007

This paper proposes a scheme to estimate the technical efficiency of trucks in logistics as performance measure by Data Envelopment Analysis (DEA). The result of technical efficiency estimation shows that there exists a substantial opportunity for improvement in technical efficiency of trucks and also the heterogeneity in the technical efficiency among trucks.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.10-15
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• 1998

In Japan, digital HDTV services via broadcasting satellite are planned to start in 2000. NHK has developed an HDTV codec conforming to the MPEG-2 $MPHL$ and estimated the coded picture quality with diverse image sequences. This paper shows the codec specifications and presents the result of the picture quality assessment.

• Journal of Convergence for Information Technology
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• v.11 no.5
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• pp.94-103
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• 2021

This study aims to propose technical trading rules for Bitcoin futures and empirically analyze investment performance. Investment strategies include standard trading rules such as VMA, TRB, FR, MACD, RSI, BB, using Bitcoin futures daily data from December 18, 2017 to March 31, 2021. The trend-following rules showed higher investment performance than the comparative strategy B&H. Compared to KOSPI200 index futures, Bitcoin futures investment performance was higher. In particular, the investment performance has increased significantly in Sortino Ratio, which reflects downside risk. This study can find academic significance in that it is the first attempt to systematically analyze the investment performance of standard technical trading rules of Bitcoin futures. In future research, it is necessary to improve investment performance through the use of deep learning models or machine learning models to predict the price of Bitcoin futures.

• Journal of Korea Trade
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• v.25 no.4
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• pp.108-127
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• 2021

Purpose - On the basis of knowledge transfer theory, we empirically explored how three types of human resource (HR) innovation knowledge exchange within a Chaebol drive the global subsidiary performance of the headquarters (HQ) of a Chaebol's globally affiliated companies. Design/methodology - Using a sample of 176 Korean HQ firms of the top 53 Chaebols and 1,061 of their foreign manufacturing subsidiaries (n = 1,061), we tested the relationship between the exchange of explorative and exploitative sustainable HR innovation knowledge among HQ firms of Chaebols, their subsequent transfer of technical HR knowledge via technical schemas, and the subsequent impact on the global subsidiary performance. Findings - The Chaebols' decisions about the three strategic knowledge management options (i.e., the degree of exchange of explorative and exploitative technological HR innovation knowledge and the extent of HQ-subsidiary HR knowledge transfer) have highly significant relationships with the global subsidiary performance. The results help explains the conditions under which the explorative versus exchange of exploitative sustainable HR innovation knowledge pays off by showing the moderating role of the degree of HQ-to-subsidiary technical HR knowledge transfer, at least in the case of the Chaebol as one representative type of the emerging-market business groups. Originality/value - As the first of its kind in the field of sustainable HR innovation knowledge management at the business group level, the present study makes a clear contribution in demonstrating how the performance of Chaebols' manufacturing subsidiaries depends greatly on their strategy for management of knowledge, as reflected in the choices they make about sharing both explorative and exploitative sustainable HR innovation knowledge among HQ firms and the subsequent transfer of HQ's sustainable HR innovation knowledge to the foreign subsidiaries.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.277-280
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• 2006

Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision-making based on conventional mathematics that combines qualitative and quantitative concepts always exhibit difficulty in modelling actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection and preventive measures. However, the objectives of maximising the degree of technical performance, maximising the safety levels and minimising the costs incurred are usually in conflict, and the evaluation of the technical performance, safety and costs is always associated with uncertainties, especially for a novel system at the initial concept design stage. In this paper, a design-decision support framework using a composite structure methodology grounded in approximate reasoning approach and evidential reasoning method is suggested for design evaluation of machinery space of a ship engine room at the initial stages. It is a Multiple Attribute Decision-Making (MADM) or Multiple Criteria Decision Making (MCDM) framework, which provides a juxtaposition of cost, safety and technical performance of a system during evaluation to assist decision makers in selecting the winning design/procurement proposal that best satisfies the requirement in hand. An illustrative example is used to demonstrate the application of the proposed framework.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.197-202
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• 2020

The business incubator is a useful system to help start-up companies, providing various supporting systems from the technical supporting system to human resources supporting system. This article investigates the moderating effect of technical support and competence support of business incubators' on the relationship between founder's experiences and performance of the company. A total 201 sample were used to empirically test the hypotheses. The results of the study partially supported the hypotheses, implying the needs of specific supporting systems for start-ups. Managerial implications are also discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.11
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• pp.699-704
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• 2011

The compressor's efficiency affects on the fuel consumption of the vehicle because the compressors for car air-conditioning system are operated by engine-driven. Especially, the refrigerant is being changed recently from R134a to substitution refrigerant to protect environment pollution that people concerned about. However, that leads to lower efficiency of the car airconditioning system and worse fuel consumption of the vehicle. Thus, this paper is focused on the methods for improvement of the compressor's efficiency that affects on the fuel consumption of the vehicle by numerical analysis for compressor's performance and the measurement of cylinder volume and pressure when the compressor is being operated.

• Journal of Agricultural Extension & Community Development
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• v.23 no.2
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• pp.145-156
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• 2016

The purpose of this study is to analyze the farms growing domestic kiwi fruit 'Gold' on their management performance and efficiency in order to reduce the risks involved with introducing new kind of crops for growing, and suggest improvements. First, the result of analysis showed that domestic kiwi fruit 'Gold' growers' income were higher than the average growers due to the fruit's high unit price and productivity. Second, the analysis of management efficiency resulted in scale efficiency having greater impact on inefficiency rather than pure technical efficiency. As for the analysis of technical efficiency, the depreciation costs of agricultural facilities had the greatest influence on its inefficiency. Third, inefficient farms put in excessive inputs across the board, while labor costs(self labor cost + hired labor cost) were the largest factor of optimal inputs according to the models of technical efficiency and pure technical efficiency. Fourth, because of greater reliance on mechanical tools from rising labor costs, there's a need for individual farms to avoid buying farming equipments and instead share the equipments of nearby farms and agricultural cooperatives, or start renting agricultural machines from companies.

• Steel and Composite Structures
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• v.23 no.5
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• pp.557-570
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• 2017

In this study, the seismic performance levels of four bridges are determined using finite element modeling based on ambient vibration testing. The study includes finite element modeling, analytical modal analyses, ambient vibration testing and earthquake analyses of the bridges. For the purpose, four prestressed precast I beam bridges that were constructed for the Ankara-Sivas high speed railway line are selected for analytical and experimental studies. In the study, firstly a literature review related to the dynamic behavior of bridges especially precast beam bridges is given and then the formulation part related to ambient vibration testing and structural performance according to Turkish Seismic Code (2007) is presented. Next, 3D finite element models of the bridge are described and modeled using LARSA 4D software, and analytical dynamic characteristics are obtained. Then ambient vibration testing conducted on the bridges under natural excitations and experimental natural frequencies are estimated. Lastly, time history analyses of the bridges under the 1999 Kocaeli, 1992 Erzincan, and 1999 Duzce Earthquakes are performed and seismic performance levels according to TSC2007 are determined. The results show that the damage on the bridges is all under the minimum damage limit which is in the minimum damage region under all three earthquakes.