• 한국작물학회:학술대회논문집
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• 한국작물학회 1999년도 춘계 학술대회지
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• pp.53-54
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• 1999

• 산업공학
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• 제11권3호
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• pp.55-63
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• 1998

In this study we consider a CONWIP system in which the processing times at each station follow an exponential distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied instantaneously are assumed to be lost. We assume that the lot size at each station is greater than one. For this system we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of parts at each station, average number of parts at each station and the proportion of lost demands. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. A recursive technique is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method were compared with those obtained by simulation. Comparisons with simulation have shown that the accuracy of the approximate method is acceptable.

• 한국실내디자인학회논문집
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• 제23권1호
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• pp.172-180
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• 2014

A railway station appears in the form of multi-use station building where cultural and commercial elements such as shopping and leisure are mixed, getting out of simple space configuration oriented to the space for station work, where a passenger stays for a little while. Now, a railway station is a place expanded to the inside of city, and builds a relationship with urban fabric, and therefore it should receive the social change in the time together with the surrounding infrastructure, and should inevitably form the urban environment. And it should become the 'Place' so as to be capable of playing a role of buffer and a role of regional gateway landmark by making users included in the inside through various uses with regard to the dispersed urban connection. Hence, this study is intended to examine the planning through the place branding of railway station. In the method of research, the characteristics that place branding had was investigated, and an analysis was made on the basis of 10 place branding strategic elements and 6 railway design guidelines. And it was intended to set a direction in which the existing place branding strategy could be applied to the railway station, and was intended to derive the place branding planning strategic elements of railway station. Hence, the planning can be classified into the following 5 kinds in connection with railway station. First, identity should be embodied through the strategy of constructing the symbolic image of railway station. Second, a role of mediating variously approaching flows in the city should be played. Third, the spatial layout of railway station, which can increase the efficiency of use, should be arranged. Fourth, special characteristics should be intensified through creative storytelling that stimulates emotion. Fifth, an organic change is gradually necessary for sustainability. These planning elements should be applied in harmonious combination. Therefore, a new railway station can be maded by building identity and placeness and by giving the value through these planning directions in the future.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.380-385
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• 2004

Railway stations are functional buildings. Their primarily role is to help passengers or freights complete their trip safely, easily, comfortably, and to improve the railway operating system. However, some urban stations are lately taking the form of what is called a station complex, and some regional stations are being constructed together with local public facilities. Roles of railway station are changing. Therefore, meeting user, railway operator, local resident, and government needs, roles of railway station would include multi-functional complex, high quality terminal, community center.

• 한국조경학회지
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• 제31권4호
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• pp.39-48
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• 2003

The Office of Korean National Railroads announced a design competition for Kwangyang Station and sought design proposals in October of 2002. The authors collaborated on a landscape design for Kwangyang Station and earned first prize in the competition. The Office decided to construct outdoor public spaces of Kwangyang Station for railroad users, visitors and staff, and local residents. The landscape design covers the following: site inventory and analysis; integration of design program and site analysis; evaluation of design concept; selecting a winning design alternative; schematic design including circulation form and spatial form; and design development including subarea design. In the design process, the authors focused on the integration and interpretation of site conditions as related to the Kwangyang Station building. They also collectively analyzed and considered the physical development of the outdoor spaces of Kwangyang Station. The following are some of the major areas in the design of the outdoor spaces of Kwangyang Station: 1) a plaza for waiting, 2) an entry area for passengers, 3) a train cafeteria, 4) a cultural plaza, 5) an image wall, and 6) a symbolic pond. The plaza for waiting is created as a place for users to wait and rest. The entry area for passengers provides an area for pedestrians approaching, passing and strolling. The train cafeteria features trains, lawns, grasses and trees. The cultural plaza is a main area representing the regional characteristics of Kwangyang. This plaza also provides an area for various public events. The image wall is meant to be an exhibition space for displaying the advancements of Korean National Railroads in sculptural image forms. The symbolic pond consists of an area with symbolic water features and several sculptures with artistic value. In the authors' design, the outdoor spaces of Kwangyang station are created as a new type of public realm with function, regional quality, original identity, cultural context, symbolic meaning and images, and beauty. The designed spaces would be one of the most representative places of interest and attraction in Kwangyang.

• 한국경영과학회지
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• 제23권3호
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• pp.153-168
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• 1998

In this study we consider a CONWIP system in which the processing times at each station follow an exponential distribution and the demands for the finished Products arrive according to a compound Poisson process. The demands that are not satisfied instantaneously are assumed to be backordered. For this system we develop an approximation method to obtain the performance measures such as steady state probabilities of the number of parts at each station, the proportion of backordered demands, the average number of backordered demands and the mean waiting time of a backordered demand. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. A matrix geometric method is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method were compared with those obtained by simulation. Comparisons with simulation have shown that the approximate method provides fairly good results.

• 전자공학회논문지
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• 제52권3호
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• pp.19-24
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• 2015

본 논문에서는 massive multiple-input multiple-output (MIMO) 기반의 wireless powered communication network (WPCN)에서 에너지 효율을 향상시키기 위한 기지국 안테나 수 최적화 기법을 제안한다. 제안하는 기법은 massive MIMO 시스템의 채널 hardening 특성을 이용하여 채널 이득을 안테나 수에 대한 식으로 근사한다. 그리고 근사화 된 최적화 문제에 편미분을 적용한 후 Lambert-W 함수를 이용하여 최적해를 closed form으로 찾는다. 모의실험을 통해 제안하는 기법의 근사 과정과 최적화 문제를 해결하는 방법이 적절함을 보이고, closed form 해가 exhaustive search 방법으로 찾은 해와 오차가 크지 않음을 확인한다.

• 한국경영과학회지
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• 제31권3호
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• pp.63-79
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• 2006

In this study we consider a CONWIP system in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied immediately are either backordered or lost according to the number of demands that exist at their arrival Instants. For this system we develop an approximation method to calculate performance measures such as steady state probabilities of the number of parts at each station, proportion of lost demands and the mean number of backordered demands. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product-form approximation method. A recursive technique is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method are compared with those obtained by simulation. Comparisons with simulation show that the approximation method provides fairly good results.

• 건축역사연구
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• 제15권2호
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• pp.7-22
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• 2006

The Industrial Revolution brought a variety of new forms of structure, and as a group they are usually called 'industrial architecture'. Steam engines contributed greatly to architecture with a unique structure called 'water tower' to provide water for steam engines, especially the adoption of it. This study is to examine the changes of the building materials and architectural features of the water towers of railway stations built in the early twentieth century in South Korea. This study also attempts to describe the modern features of the industrial architecture, which did not get a chance to be noticed. Through this examination on water tower, which is a part of industrial architecture with sheer integration of function and pure geometric form, we would like to find the meaning of modern architecture in Korea. As we can see in the Korean oldest railway station water tower constructed in masonry at Yeonsan Station in 1911, early water towers were divided into the masonry machine room and the steel water tank. However, the masonry structure was soon turned into concrete structure with its formal features maintained as it was. The steel water tank was also replaced with concrete structure. As a result, while its basic structure remained, concrete structure had substituted for the every components of water tower. Concrete-built water towers were the high-tech architecture of that time and the most perfect structures built in concrete. Nevertheless, the perfection of the water tower form and the technology it attained were not transferred to other modern and contemporary architecture in South Korea. Since the subject to railway station water towers was the Japanese government, and steam engines were replaced with diesels in the midst of a complicated domestic situation after the independence, the need for water towers in railway stations disappeared and therefore, it became ignored and was difficult to look over the architectural features and values of early railway station water towers.

• 한국통신학회논문지
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• 제41권8호
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• pp.924-927
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• 2016

In this paper, we consider a cumulative distribution function (CDF)-based opportunistic scheduling for downlink transmission in a cellular network consisting of a base station and multiple mobile stations. We present a closed-form formula for the average starvation period of each mobile station (i.e., the length of the time interval between two successive scheduling points of a mobile station) over Markov time-varying channels. Based on our formula, we investigate the starvation period of the CDF-based scheduling for various system parameters.