• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.425-431
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• 2006

There are two kinds of police authorities in Korean railway industry, that is, the Special Judicial Police and the Local Subway Police. The existence of two separate entities for common objective of railway security has given rise to problems including inefficiency in performance and lack of customers-focused police service and synergic effects. The purpose of this study is to search for solutions to rail crimes that allows for rapid spatial movements since they take place on fast moving trains.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1449-1463
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• 2008

This paper considers three different models with two functional forms, Cobb-Douglas and Translog, for the stochastic frontier production function of food manufacturing industry of Bangladesh over the period 1981-1982 to 1999-2000. The models are proposed by Battese and Coelli (1992, 1995) and Huang and Liu (1994). The technical efficiency, total factor productivity, technological change and technical efficiency change have been estimated in the frontier models. The results indicate that 41.47%, 59.30% and 70.98% of the potential output are being realized in this sector. The mean increments in total factor productivity are approximately 2%, 9% and 4% respectively.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.558-568
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• 2005

There are two kinds of police authorities in Korea. One is the Special Judicial Police, under the authority of the Ministry of Construction and Transportation, charged with maintenance of public order on trains, in stations and other places of business operated by the Korea Railway Corporation. The other is the Local Subway Police, belonging to the Local Police Agencies, whose jurisdiction covers trains, station and other areas managed and operated by local governments. The existence of two separate entities for common objective of railway security has given rise to problems including inefficiency in performance and lack of technical knowledge and synergic effects. This study looks at the need for resolving those problems by restructuring and expanding the Special Judicial Police to bring railway security under a single authority and an integrated railway security systems operation.

• Progress in Superconductivity and Cryogenics
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• v.18 no.3
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• pp.30-34
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• 2016

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

• Journal of Korea Multimedia Society
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• v.18 no.6
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• pp.753-762
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• 2015

As the computer graphic technology has developed rapidly, the management of visual effects production has also changed. However, the insufficient rest and the inefficiency of communication have resulted in more pressure which would weaken the strength of the whole team. For searching the possible solution, this research has applied the SCRUM in VFX production and analyzed the impact of SCRUM for VFX project management. SCRUM was first used in the projects of software development, but now there are already many successful examples of introducing SCRUM into their facilities in various fields. This paper has used SCRUM in the experimental group and present methodology in VFX project management in the control group for the same project. Based on the analysis of the questionnaire investigation from both group with using t-test for data analysis, it has confirmed the credibility of the questions in the questionnaire index as α > 0.72. With the result of analysis based on the corresponding samples of the t-test, it shows the diversity of SCRUM for project management, and the convenience of communication within the team can enhance the team strength. Follow-up research will attend to provide more suggestions for applying SCRUM in other areas in project management.

• Journal of Power Electronics
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• v.9 no.2
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• pp.215-223
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• 2009

A design methodology for transformers including integrated and center-tapped structures for LLC resonant converters is proposed. In the LLC resonant converter, the resonant inductor in the primary side can be merged in the transformer as a leakage inductance. And, the absence of the secondary filter inductor creates low voltage stress on the secondary rectifiers and is cost-effective. A center-tapped structure of the transformer secondary side is widely used in commercial applications because of its higher efficiency and lower cost than full-bridge structures in the rectifying stages. However, this transformer structure has problems of resonance imbalance and transformer inefficiency caused by leakage inductance imbalance in the secondary side and the position of the air-gap in the transformer, respectively. In this paper, gain curves and soft-switching conditions are derived by first harmonic approximation (FHA) and operating circuit simulation. In addition, the effects of the transformer including integrated and center-tapped structures are analyzed by new FHA models and simulations to obtain an optimal design. Finally, the effects of the air-gap position are analyzed by an electromagnetic field simulator. The proposed analysis and design are verified by experimental results with a 385W LLC resonant converter.

• The Journal of Fisheries Business Administration
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• v.47 no.1
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• pp.1-20
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• 2016

The purpose of this study is to assess the effects of outlook project for olive flounder, from the view point of price stabilization, market efficiency, and causality of the prices in different distribution channels. Analytical results show that the volatility of producer price of olive flounder has been significantly mitigated after the implementation of the outlook project. The market efficiency is estimated to be improved after implementing the outlook project although there is an inefficiency on price determination process in some producing regions. The causality test on the producer and wholesale price shows that producing stage leads the wholesale stage in forming the prices. It is found that Jeju leads the flounder price on the size of 500g and 2kg, while Wando leads the price of 1kg size. These estimation result as whole indicate that outlook project for olive flounder has accomplished the intended goals.

• Journal of the Ergonomics Society of Korea
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• v.15 no.1
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• pp.1-14
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• 1996

Menu-driven interfaces are frequently employed for user interfaces on many electronic products. Due to space constraint, a single or multi-line display is popularly used to show menu items unlike the software interfaces. Single or multi-line display present 8 .approx. 21. characters on an LCD screen and the user selects items using a series of button pushes. Multi-line displays are different from the single-line ones in the following aspects. First, they can present multiple line of information at the same time. Second, they can present menu items in a various way compared to single-line ones. However, due to their space constraint multi-line displays have many limitations compared to ordinary displays which usually use 14" screens. Therefore, guidelines are necessary for designing efficent multi-line display menus interfaces. In this study, a human factors experiment was conducted to examine the effects of three design variables which might affect the usability of a multi-line display menus. Factors investigated include menu structure, number of lines on the display, and item presentation method. Usability of the multi-line display menus was measured quantitatively in terms of four different aspects: speed, accuracy, inefficiency and preference. The analysis of variance was used not only to analyze the main effects of the factors and their interactions but also to see the differences between the single-line display menus and multi-line display ones. A set of design guidelines drawn from this study can be applied to the design of the user interfaces of a various types of electronic consumer products.

• The Journal of Information Technology
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• v.1 no.1
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• pp.1-11
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• 1998

Today's firms face task of achieving competencies in two somewhat mutually exclusive areas. That is, due to fierce competition in the market, firms need to provide better products and services without losing cost advantage. In this respect, effective logistics management is one of the process that can yield a foundation of competitive advantage. Many firms are already using integrative supply chain management to achieve mutual goals of each firms within the supply chain. However, it is highly likely that inefficiency will occur because of different operations systems and organizational characters of each firms. Information system is receiving attentions as to reduce inefficiencies and gain competitive advantage. This study analyzes the effects of information integration on logistics performance to search the role of information system in supply chain management.

• 사회경제평론
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• v.31 no.3
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• pp.1-27
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• 2018

We evaluate the income-led growth policies introduced in the first year of 'the Moon Government', and try to find ways to extend policy packages. We emphasize the expansion of fountain effects, reinforcing trickle-down effects, and fiscal expansion. Nevertheless, we still face two deep problems. It is hard to reverse the long-run downward growth trend due to population decline. It is also hard to overcome the chronic inefficiency in resource allocations originated from the Korea-specific monopolistic structure. We still can take advantage of income-led policy, but the growth effect will be limited if our efforts just remain in mild improvement of income distribution. We have to challenge the broader reform agenda if we really aim at great paradigm shift.