• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.406-408
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• 1999

In order to reduce the overall size and cost, researchers attempted to integrate the functions of power factor correction(PFC) and isolated dc-dc conversion into single power stage. However, single-stage isolated PFC converters have higher voltage stress and heavier loss when compared with a normal dc-dc converters. In this paper, we propose to add active clamping circuit to keep the switch voltage stress low and to achieve soft switching of electronic devices.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.577-587
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• 2017

The recent IMO MEPC regulation on EEDI, EEOI and increased fuel cost has worsened the financial condition of the small and medium sized passenger ferry companies, and it is situated to acquire the economic ships with a pretty high resistance performance. The purpose of this research is to develop a design method on the efficient gooseneck bulb for the middle-sized passenger ferry operated in the Far East Asian seas. The hull forms are designed by varying the gooseneck bulb parameters to find the changes on the resistance performance according to the shape of bulb. The numerical series tests are made to derive the regression equation for estimating the resistance through analyzing the data statistically. This equation is set as an objective function, and then using the optimization algorithm searches for the optimal combination of the design variables. After a hull form is designed corresponding to optimized parameters.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1859-1870
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• 2009

Suin line is expected to be opened completely in 2015 by three stages. And the line between Suwon and Incheon(54.0km) is under construction to supply the users of southwestern area transportation convenience. The route of Suin line will be constructed to share partly with Ansan line and connect directly with Bundang line to the east and Kyeongin line to the west. That's why a lot of difficulty in train and rolling stock operation IS expected. This paper proposes an alternative plan of train operation when the line is opened partly and completely and makes an optimally alternative plan through the analyses of transportation demand, the change of human resources of operation sector according to train operation plan by an alternative proposal and operation cost.

• Journal of the Korean Professional Engineers Association
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• v.42 no.6
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• pp.47-52
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• 2009

According to increasing demand of water mainly due to the growth of population and increased water consumption, many countries either face or worry about the shortage of fresh water. Proportionately, importance and efforts of each country to develop the potable water has been gradually increasing as well. Among others, desalination of seawater has been developed to one of the solutions mainly from the middle east and other arid regions to produce large quantity of fresh water from seawater. We installed beach seawater collector wells to develop the filtered seawater supply for desalination in a refinery. We came to a conclusion that the beach seawater collector well is one of the recommendable alternatives of seawater pre-treatment for desalination applications with lower operating cost and higher efficiency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.602-606
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• 2015

This paper presents a ZigBee wireless communication system for remote diagnosis in overhead distribution power lines. The system is divided in three parts in the functional aspect - a host computer module, a remote controller module and a diagnostic system module. The host computer module designed as USB interface transmits control signals and receive data measured by sensor. The remote controller module operates the diagnostic system. Diagnostic system module communicates with internal main controller and host computer USB. Multiple communication channel is adopted for simultaneous operations of several diagnostic system. Dedicated protocol for each module is developed. The system is designed with a focus on low cost and small size suitable for lightweight and small diagnostic system.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.63-76
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• 2009

On the basis of a Stochastic Frontier Approach (SFA), this paper analyses revenue efficiencies for the same sample of Korean and Japanese railways in the papers which analyze cost efficiencies using a generalized translog functional form. The paper also compares the results of revenue efficiencies with cost efficiencies and evaluates the effects of managerial autonomy and privatization on the firm-specific efficiencies. The results show that the average estimate of revenue inefficiency is 7.02% when the term of inefficiency is assumed to be distributed as a half-normal and 6.98% as a exponential for the total sample. Also, standardized inefficiencies in revenues (7.5%) are greater than those in costs (2.1%). JR East and JR West are found to be most efficient on the revenue side and on the cost side respectively while JNR and JR Kyushu are worst efficient on the both sides. Finally, the correlations between efficiencies in revenues and costs also between efficiencies and privatization are positively correlated. The results suggest that the most independent companies, with increased managerial autonomy via privatization, are the most efficient in both revenues and costs.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.34
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• pp.23-37
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• 2007

Since 1964, HSR, which was opened in Japan, has had a hoge impact on the world. Historically, HSR has similar characteristics to the Roman Road, which promoted rapid movement and hada great influence on international society as transport infrastructure. Recently the development of HSR has become more rapid because of economic, environmental and external cost concern, emphasizing Environmentally Sustainable Transport(EST). In particular, the external cost has become more important factor for justifying HSR. The successful factors of HSR are high demand and cost minimal construction costs. There are two successful HSR models, the Japanese and the French. The former operates based on high demand oriented and the latter focuses on its minimizing costs. The demand orientated model means HSR carries over 100,000 passengers per day as in Japan and Far East Asian countries. The cost minimized model focuses on lower operation and construction costs as in France. In particular, Germany carries both passengers and freight on HSR. The construction costs in Germany are in between those of Japan and France. In future, Korea, Taiwan and China HSR will follow Japan's successful model because of high population density and concentration of economic activity along railway lines. This paper supports Vickerman's argument that HSR is justified where there is a demand of between 12 million and 15 million railway passenger a year(about 40thousand persons/day) between two urban center. This will be shown in the future in Korea, in Taiwan and China. Finally, this paper reviews that HSR activates at 250km/h for dedicated new lines and 200km/h for upgraded lines. In particular, it is successful in area of high population density and cost minimizing technology.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.65-78
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• 2006

This paper investigates the cost structure ot the Korea and Japan railroad industry with respect to density, scale and scope economies as well as productivity growth rate using a generalized trans)og multiproduct cost function model. The paper then assumes that the Korea and Japan railway companies pi·educe three outputs (incumbent railway passenger-kilometers. Shinkansen passenger-kilometers, ton-kilometers of freight) using four input factors (labor, fuel, maintenance, rolling stock and capital). The specified cost function includes foul other independent variables: track lengths to reflect network effects, two dummies to reflect nation and ownership effects, and time trend as a proxy for technical change. The simultaneous equation system consisting of a cost function and three input share equations is estimated with the Zellner's iterative seemingly unrelated regression. The unbalanced panel data used in the paper, a total of 154 observations. are collected from the annual records of the Korea National Railroad (KNR) for the yews $1977{\sim}2003$, Japan National Railways (JNR) for the years $1977{\sim}1984$. seven Japan Railways (JR's) for the years $1987{\sim}2003$. The findings show that the Korean and Japanese railways exhibit product-specific and overall economies of density but product-specific diseconomies of scale with respect to incumbent railway passenger-kilometers, Shinkansen-kilometers and ton-kilometers. However, the railways experience mild overall economies of scale which result from economies of scope associated with the joint production of incumbent railway/Shinkansen and feight, freight/incumbent railway and Shinkansen except Shinkansen/incumbent railway and freight. In addition, the economies of density and scale in the KNR, JR east, JR central, and JR west companies at the point of the years $1990{\sim}2003$ average is generally analogous to the above results at the point of sample average. There also appear to be economies of ssope associated with the joint Production of the incumbent railway and Shinkansen in JR central but diseconomies of scope in JR East and JR West. The findings also indicate that the productivity growth rate of the privately-owned JR's is larger than that of the government-owned KNR.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.4
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• pp.606-618
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• 2010

The study investigated how 'word of mouth' originates in the chain restaurant industry. It has long been acknowledged that 'word of mouth' is a critical factor for the success of a restaurant business due to its targetability and cost effectiveness. A review of the literature revealed four antecedents of 'word of mouth': service quality, perceived value, satisfaction, and relationship quality. Based on the theoretical/empirical relationships between those constructs, a structural model composed of the hypotheses was proposed. The structural model was tested with data collected from 471 chain restaurant patrons. The structural equation modeling analysis revealed that five constructs in the proposed model are interrelated, and during this process, word of mouth is formed in the chain restaurant industry. A positive relationship between service quality and satisfaction (0.265, p<0.05), service quality and perceived value (0.831, p<0.05), service quality and relationship quality (0.465, p< 0.05), and service quality and WOM (0.263, p< 0.05) were found, indicating that service quality is a key prerequisite for word of mouth and other constructs proposed in the model. It was revealed that perceived value doe not have a direct impact on WOM formation (t=1.275, p=0.202), but a positive relationship between perceived value and satisfaction (0.293, p<0.05) and between satisfaction and WOM (0.627, p< 0.05) were found. Therefore, it was concluded that patrons' perceived value influences word of mouth formation, but that impact is mediated by satisfaction. During this process, relationship quality also plays a mediating role in generating word of mouth. Based on data analysis, theoretical/managerial implications are discussed.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.2
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• pp.253-263
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• 2008

This study examined the menu management and utilization of cooking equipment at school foodservice operations in the Chonbuk area. Self-administered questionnaires were collected from a total of 193 school dietitians. Statistical data analysis was completed using the SPSS v. 11.5 program. The results are summarized as follows. Among the 193 schools, 58.5% were elementary schools and 41.5% were middle and high schools. Approximately 97% of the schools prepared meals in the conventional manner. Among the school, 68.4% had a menu cycle of 1${\sim}$2 weeks. The frequency of using convenience foods was significantly different between the elementary schools and middle and high schools(p<0.001). Approximately 45% of the dietitians responded that the most important details for menu planning were menu variety and consumer preference. However, 66.8% of the dietitians responded that a key problem for menu planning was limited and worn-out kitchen equipment. Although the cost of purchasing cooking equipment is high, most dietitians responded they have high needs for equipment in order to meet of the quantity demands of food production. In terms of utilized cooking equipment, most schools had mixers, vegetable cutters, choppers, dish washers, etc. Yet the amenities most often lacking were meat slicers, composting machines, ovens, and griddles. In utilizing the cooking equipment, there was no significant difference between the dietitians in the elementary(3.67) schools and those in the middle and high school foodservice systems(3.70); however, the utilization level was poor. Therefore, governmental regulatory agencies should review and finance support for purchasing cooking equipment. Finally, purchasing analysis was conducted regarding the dietitians' opinions on menu recipes and useful equipment.