• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.226-229
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• 2005

본 논문에서는 송전선로 도체의 경년열화(thermal deterioration)를 평가하기 위해 확률적 기법을 도입하였다. 선로의 경년열화를 나타내기 위해 선로의 장력(tensile strength) 감소를 계산하며 이는 해당 선로의 과거 전류 이력과 선로가 위치한 지역의 과거 기상데이터 및 부하량의 변화를 통해 산출한다 첫째로, 과거 데이터를 통해 확률분포를 구한 후 모든 데이터는 통계적으로 서로 간에 독립적이라는 가정 하에 Monte-Carlo Simulation을 수행하였다. 둘째로, 과거 데이터의 이력을 시간순서대로 추종하여 1시간 단위로 장력변화를 누적하는 순차적 계산(dynamic calculation)을 수행하였으며 그 결과를 MCS 기법과 비교하였다 주로 백분율로 표현하는 도체의 장력 감소분은 송전선로의 수명을 결정하는데 사용할 수 있는 중요한 지수이때, 계통계획에 있어서 유용한 기준으로 사용할 수 있을 것이다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3077-3087
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• 1998

본 논문에서는 분산 멀티미디어 환경에서 데이터 크기의 가변성과 네트워크의 부하변동으로 인하여 발생하는 미디어 불연속성을 방지하면서 동기화를 보장하는 클라이언트 버퍼 안정화 알고리즘을 제안한다. 제안 알고리즘은 클라이언트의 상황에 맞도록 산출된 미디어스크림의 제어량과 제어시간이 포함된 제어 메시지를 멀티미디어 서버로 전송함으로써 클라이언트 버퍼를 안정화 시킬 수 있다. 클라이언트는 주기단위로 수신측의 자원과 네트워크의 상태를 예측하여 오버런 혹은 스타베이션이 발생할 징후가 보이면 제어 메시지를 생성하는데, 제어값들은 클라이언트의 상황과 멀티미디어 서버의 미디어스트림전송 메커니즘 및 네트워크의 상태를 고려하여 생성된다. 본 알고리즘의 특징은 미디어스트림의 과도한 드롭으로 인한 질 저하를 방지하며, 특히 네트워크의 부하변동이 클 경우에는 빠른 속도로 시스템을 안정화시킨다.

• JOURNAL OF ELECTRICAL WORLD
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• s.266
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• pp.59-64
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• 1999

에너지수요 구조개혁이란 관점에서 볼 때 전력부하 평준화의 한 수단으로서 빙축열이용 공조시스템의 채용과 그 신장이 현저하다. 빙축열이용 공주시스템은 다른 축열이용시스템(예를 들면 수축열)에 비하여 단위체적당의 축열량을 크게 할 수 있어 자 스페이스를 도모할 수 있다. 또 취급이 간단하여 환경에의 영향부하가 적다는 점 등 시대를 대표하는 공조시스템이라 할 수 있다. 미쓰비시전기에서는 타사에 앞서 선진적인 빙축열이용 공조시스템을 개발$\cdot$판매하고 있으며 기종 갖추기, 성능 공히 업계 톱클래스를 유지하고 있다. 채용이 넓어지고 있는 중$\cdot$소규모 빙축열이용 공조시스템은 패키지 에어컨 방식과 Chiller방식으로 대별된다. 전자는 야간전력으로 만든 얼음으로 냉매를 냉각하여 냉방능력을 높여 에너지이용효율(COP)을 올림으로써 주간전력에너지를 삭감하는 것이다. 후자는 야간전력으로 만든 얼음으로 공조용 순환수를 냉각하여 주간에 냉방으로 이용하는 것이다. 어느 방식이나 야간의 전력으로 만들어진 얼음으로 주간에 필요한 전력에너지를 충당하고 있어, 주간전력의 야간전력으로의 시프트를 달성할 수 있는 시스템이다.

• Journal of Korean Port Research
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• v.14 no.2
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• pp.155-163
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• 2000

A discrete system has interpreted by using the network model, and PERT network is one of these methods. For the purpose of analysing the real system, it is necessary to measure the parameter of the real system. And system identification problem is to assume the parameter of a real system when we get to know the system model, the input data and output data. System identification method has been only developed to a system of which a structure has expressed a differential equation or a polynomial expression. But it has been scarcely developed yet in that case of network model. The aim of this paper is to examine a changes when new system is introduced to the present system. The changes are as follows : how the present system will be changed, when the changes will be happened. In this paper, genetic algorithm is used to assume the parameter.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.101-108
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• 1999

A discrete system has interpreted by using the network model, and PERT network is one of these methods. For the purpose of analysing the real system. it is necessary to measure the parameter of the real system. And system identification problem is to assume the parameter of a real system when we get to know the system model, the input data and output data. System identification method has been only developed to a system of which a structure has expressed a differential equation or a polynomial expression. But it has been scarcely developed yet in that case of network model. The aim of this paper is to examine a changes when new system isn introduced to the present system, The changes are as follows: how the present system will be changed, when the changes will be happened. In this paper, genetic algorithm is used to assume the parameter.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.131-137
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• 1998

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuated on the variation of insolation, temperature and load. Photovoltaic system needs an inverter which can interface the dc output power of solar cell with the residential ac load. The inverter has to supply a sinusoidal current and voltage to the load and the utility line with a high power factor. This paper proposes an utility interactive photovoltaic system designed with a step-up chopper and a PWM voltage source inverter. The step-up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power points of solar cell without any influence on the variation of insolation and temperature. The voltage source inverter operates in a manner that its output voltage is in phase with the utility voltage. The inverter supplies an ac power with high factor and low level of harmonics to the load and the utility power system.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.175-180
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• 2008

The objective of this study was to investigate biosorption of organic matter on EPS(Extracellular Polymeric Substances) at different SRT(Sludge Retention Time) in a SBR(Sequencing Batch Reactor) process, which was operated with the following operation steps : Fill-React-Settle-Decant-Idle. The hydraulic retention time was set to be 24 hours. The results obtained from this study showed that the organic removal efficiency per unit microbial biomass decreased with increasing SRT, and the corresponding EPS amount also did. The percent removal of organic by biosorption increased with SRT, and it reached to 53.2% at SRT of 30 days. However, the highest biosorption per microbial biomass(48.6 mgCOD/gVSS) was found at SRT of 2 days. The EPS analysis was performed by measuring TSS, TCOD$_{Cr}$, and TKN. The EPS production per unit microbial biomass was observed to be high at a low SRT. Due to the above result, the floc formation was hindered and therefore poor settlement of sludge resulted in decreasing the COD removal efficiency. It was therefore concluded that the consideration of the system design should include the characteristic of EPS as well as other factors such as SRT, MLSS, and organic loading.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.749-755
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• 2013

The purposes of this research are to know the optimal gab and electric pressure (voltage) of electrode-plates coated with activated carbon and also to study their arrangement through dust removal efficiency. From the experimental results of attached dust mass at different electrode-plate gab, the frequency of attachment and detachment of dust was more increased as electrode-plate gab was closer. In attached dust mass per unit area of electrode-plate, the farther electrode gab, the more increased. But in total attached dust mass, the closer electrode gab, the more removed. From the experimental results, the optimal electrode arrangement in dust removal chamber was considered that the forward parts of chamber need to be increased the number of electrode-plate, the backward parts to be increased them. The dust attachment have no relation with electric pressure while showing high removal efficiency under condition of 5 kV of voltage and 2 cm of electrode-plates gab.

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.80-86
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• 2000

The future costs of energy and the cost of the repair of apartment buildings are expected to rise continuously in proportion to the initial costs. Therefore it has become important for these increasing costs to be incorporated and reflected in the design of the building. Systems such as structure and services for the buildings remain constant, but a number of the walls and windows can vary and thus have a major influence on the total construction and running costs of a building. The critical factor in the apartment unit design for the optimization of life cycle cost (LCC) is the ratio of the x and y axis of the walls in the unit plan. This paper demonstrates how to achieve the optimal size and thus optimize the LCC of the building.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.1-7
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• 1998

Due to the increase in capacity of auxiliary machinery in power plant, the importance of energy saving has been greatly emphasized. If the speed of fans or pumps is controlled in accordance with the variation of load, large electric energy can be saved. Large capacity inverter, 2MVA GTO inverter, has been developed by operating two of 1MVA unit inverters in parallel. The parallel operation of the unit inverter is accomplished through two output transformers of which the secondary windings are connected in series. The system is composed of one control cubicle, one rectifier cubicle and 2 unit inverter cubicles. This inverter system was applied to the sea water lift pump(SLP) driven by a 6.6KV 1500KW induction motor in Seo-Inchon power plant to save the electric energy. The parallel operation of inverters by 180 degrees apart in switching frequency helps to reduce the harmonic components.