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에스트로겐 투여가 난소절제로 유도된 백서의 골다공증에 미치는 효과에 관한 실험적 연구
허균행,김경욱,이재훈 단국대학교 치의학연구소 1994 논문집 Vol.6 No.2
Osteoporosis is a state of reduced bone mass per unit volume with a normal ratio of mineral to matrix. There were many methods for osteoporosis, and estrogen is one of them. In this study, 30 female rats were ovariectomized to make a state of estrogen deficiency and induce osteoporosis. After 13 weeks, 15 ovariectomized rats were injected 6 times with 60㎍/㎏ of estradiol by 1 week interval (experimental group). The remaining 15 ovariectomized rats were used as control group. According to the time schedule, both of them were sacrified and femur were harvested. Paraffin sections were stained with HematoxylinEosin staining and modified Gomori's Trichrome staining, and observed under light microscope. The results were as follows : 1. There were no significant bony changes between the experimental and control group of cancellous bone. 2. The density of cortical bone showed increasing with time in experimental group. 3. The resorption of cortical bone in experimental group was less than that of control group.
Jae-Haeng Heo,Jae-Kun Lyu,Mun-Kyeom Kim,Jong-Keun Park 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.6
Electric power transmission utilities make an effort to maximize profit by reducing their electricity supply and operation costs while maintaining their reliability. The development of maintenance strategies for aged components is one of the more effective ways to achieve this goal. The reliability centered approach is a key method in providing optimal maintenance strategies. It considers the tradeoffs between the upfront maintenance costs and the potential costs incurred by reliability losses. This paper discusses the application of the Particle Swarm Optimization (PSO) technique used to find the optimal maintenance strategy for a transmission component in order to achieve the minimum total expected cost composed of Generation Cost (GC), Maintenance Cost (MC), Repair Cost (RC) and Outage Cost (OC). Three components of a transmission system are considered: overhead lines, underground cables and insulators are considered. In regards to aged and aging component, a component state model that uses a modified Markov chain is proposed. A simulation has been performed on an IEEE 9-bus system. The results from this simulation are quite encouraging, and then the proposed approach will be useful in practical maintenance scheduling.
Heo, Jae-Haeng,Lyu, Jae-Kun,Kim, Mun-Kyeom,Park, Jong-Keun The Korean Institute of Electrical Engineers 2012 Journal of Electrical Engineering & Technology Vol.7 No.6
Electric power transmission utilities make an effort to maximize profit by reducing their electricity supply and operation costs while maintaining their reliability. The development of maintenance strategies for aged components is one of the more effective ways to achieve this goal. The reliability centered approach is a key method in providing optimal maintenance strategies. It considers the tradeoffs between the upfront maintenance costs and the potential costs incurred by reliability losses. This paper discusses the application of the Particle Swarm Optimization (PSO) technique used to find the optimal maintenance strategy for a transmission component in order to achieve the minimum total expected cost composed of Generation Cost (GC), Maintenance Cost (MC), Repair Cost (RC) and Outage Cost (OC). Three components of a transmission system are considered: overhead lines, underground cables and insulators are considered. In regards to aged and aging component, a component state model that uses a modified Markov chain is proposed. A simulation has been performed on an IEEE 9-bus system. The results from this simulation are quite encouraging, and then the proposed approach will be useful in practical maintenance scheduling.
Maintenance Priority Index of Overhead Transmission Lines for Reliability Centered Approach
Heo, Jae-Haeng,Kim, Mun-Kyeom,Kim, Dam,Lyu, Jae-Kun,Kang, Yong-Cheol,Park, Jong-Keun The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Overhead transmission lines are crucial components in power transmission systems. Well-designed maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.
Maintenance Priority Index of Overhead Transmission Lines for Reliability Centered Approach
Jae-Haeng Heo,Mun-Kyeom Kim,Dam Kim,Jae-Kun Lyu,Yong-Cheol Kang,Jong-Keun Park 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Overhead transmission lines are crucial components in power transmission systems. Welldesigned maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.
Jae-Haeng Heo,Mun-Kyeom Kim,Geun-Pyo Park,Yong Tae Yoon,Jong Keun Park,Sang-Seung Lee,Dong-Hyeon Kim IEEE 2011 IEEE transactions on power delivery Vol.26 No.4
<P>Electric power transmission utilities try to maximize profit by reducing electricity supply costs and operation costs while maintaining their reliability. Developing maintenance strategies is one of the effective ways to achieve these profitable goals. The reliability-centered maintenance approach is a key method in providing optimal maintenance strategies. It considers the tradeoffs between the upfront maintenance costs and the potential costs of reliability losses. Since a transmission system is a group of different kinds of equipment and the reliability of the electric facilities varies with time, an equipment state model using a modified semi-Markov chain is proposed. In addition, a genetic algorithm is used to find the optimal maintenance strategies from a large class of possible maintenance scenarios. These optimal maintenance strategies have been tested on an IEEE 9-bus system and an IEEE 118-bus system; the results show that the proposed method minimizes the total expected costs.</P>
배전계통의 다양한 유지보수 기법을 적용한 신뢰도 기반 최적 유지보수 모델
허재행(Heo Jae Haeng),정하섭(Jung Ha Sub),김유창(Kim You Chang),손진만(Son Jin Man),박종근(Park Jong Keun) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
앞으로 진행되는 배전계통의 자유화 환경에서 각 배전사업자들은 고객에게 높은 신뢰수준의 전력을 값싸게 공급하려 할 것이다. 높은 수준의 신뢰수준을 유지하기 위해서 배전계통내의 component의 점검을 통하여 고장의 원인이 될 만한 것들을 찾아내고 고장이 일어나기 전에 그것을 유지보수 하여야 한다. 이 문제는 대상 component를 얼마나 자주 점검 및 보수를 해야 하는가 라는 문제가 된다. 하지만 그에 따른 비용도 소요가 될 것이다. 본 논문에서는 점검 과 보수 과정의 model을 Markov model 로 사용하였으며 대상 component의 상태에 따라서 다른 보수 기법을 적용함으로써 점검비용과 보수비용 정전비용을 최소화 하는 점검 주기를 찾았다. 또한 제안된 방법을 실제 시스템과 유사한 모의시스템에 적용하였다.
분산전원을 포함한 배전계통에서 설치비용과 유지보수 비용을 고려한 병렬 캐패시터-리액터 Bank의 최적 설치 위치 선정
허재행(Jae-Haeng Heo),류재근(Jae-Kun Lyu),이우리(Woo-Ri Lee),박종영(Jong-Young Park),박종근(Jong-Keun Park) 대한전기학회 2013 전기학회논문지 Vol.62 No.11
This paper proposes the allocation method for capacitor-reactor banks in a distribution system with dispersed generators to reduce the installation costs, the maintenance costs and minimize the loss of electrical energy. The expected lifetime and maintenance period of devices with moving parts depends on the total number of operations, which affects the replacement and maintenance period for aging equipment under a limited budget. In this paper, the expected device lifetimes and the maintenance period are included in the formulation, and the optimal operation status of the devices is determined using a genetic algorithm. The optimal numbers and locations for capacitor-reactor banks are determined based on the optimal operation status. Simulation results in a 69-bus distribution system with the dispersed generator show that the proposed technique performs better than conventional methods.
도시철도 부하특성을 고려한 ESS의 최적 운영방안 연구
허재행(Jae-Haeng Heo),신승권(Seungkwon Shin),박종영(Jong-young Park),김형익(Hyeongig Kim) 대한전기학회 2015 전기학회논문지 Vol.64 No.10
This paper proposes the optimal operation of ESS (Energy Storage System) in the substation of urban railway in an economical point of view. Since the load patterns of urban railway have different characteristics with the general power demand pattern, the characteristics motivate us to develop the optimal operation algorithm for ESS under Korean electricity billing system. We also introduce two different ESS operation strategies for peak load shaving and electricity consumption charge minimization respectively, and formulate each scheme. Historical data from Namgwangju substation are used for economical comparison of the strategies. The results show that the proposed algorithm is the most cost-effective ESS operation scheme among the strategies and reduces around 5 percent of electric charges compared to the charge without ESS operation.