• 전기학회논문지
• /
• 제63권1호
• /
• pp.70-75
• /
• 2014

TMR(triple modular redundant) digital excitation system with simulator is developed for tuning optimal control parameters during commissioning test and coping with system faults rapidly. A new system which mocks up virtual generator, turbine, grid can simulate as if excitation system is connected to a real generator system by setting four switches. The maintenance crew using the simulator is able to test perfectly the phase controller rectifiers, field breaker, sequence relays as well as TMR controller of the excitation system. Commissioning and performance results about the excitation system with simulator is discussed. The trial product was installed and operated at a 500MW thermal power plant after the commissioning test.

• 대한산업공학회지
• /
• 제25권4호
• /
• pp.466-475
• /
• 1999

A backward Dynamic Programming(DP) model for the optimal facility replacement decision problem during a finite planning horizon is presented. Multiple alternative challengers to a current defender are considered. All facilities are assumed to have finite service lives. The objective of the DP model is to maximize the profit over a finite planning horizon. As for the cost elements, purchasing cost, maintenance costs and repair costs as well as salvage value are considered. The time to failure is assumed to follow a weibull distribution and the maximum likelihood estimation of Weibull parameters is used to evaluate the expected cost of repair. To evaluate the revenue, the rate of operation during a specified period is employed. The cash flow component of each challenger can vary independently according to the time of occurrence and the item can be extended easily. The effects of inflation and the time value of money are considered. The algorithm is illustrated with a numerical example. A MATLAB implementation of the model is used to identify the optimal sequence and timing of the replacement.

• Nuclear Engineering and Technology
• /
• 제34권2호
• /
• pp.176-185
• /
• 2002

A 4-bundle shift refuelling method of CANDU6 F/H (Fuel Handling) System is analyzed to assess the operational flexibility and capacity of F/H system. The current 8-bundle shift refuelling scheme requires to refuel eight fuel bundles from a single fuel channel, and to refuel 14 fuel channels in a week on average assuming that the reactor is in a steady state. The analysis showed that the 4-bundle shift refuelling method increases F/M (Fuelling Machine) duty cycle and operator load. However, the fuellin’g method change from the 8- to 4-bundle shift refuelling ill not require additional team of operators. A marginal increase in the maintenance cost may be resulted in by the change of fuelling method and the increase of fatigue usage factors requires some components to be replaced during the FM lifetime.

• 한국임상수의학회지
• /
• 제39권5호
• /
• pp.282-285
• /
• 2022

Compulsive behavior is a sequence of movements usually derived from normal maintenance behaviors that are performed out of context in a repetitive, exaggerated, ritualistic, and sustained manner. In general, the treatment plan includes environmental management, behavior modifications, and psychotropic medications, however, the prognosis is varied. In this case report, a 9-year-old neutered male miniature poodle presented with a lifelong history of tail chasing and mutilation. Based on the behavioral history, observations, and physical examination, compulsive disorder was diagnosed. The dog's compulsive tail chasing behavior improved only with a combination of psychotropic medications, including fluoxetine, trazodone, and gabapentin.

• Radiation Oncology Journal
• /
• 제13권2호
• /
• pp.129-142
• /
• 1995

Purpose: Traditionally the patients with early stage non-Hodgkin's lymphoma of the head and neck was treated with radiotherapy. But the results were not satisfactory due to distant relapse. Although combined treatment with radiotherapy and chemotherapy was tried with some improved results and chemotherapy alone was also tried in recent years, the choice of treatment for the patients with early stage non-Hodgkin's lymphoma of the head and neck has not been defined Therefore, in order to determine the optimum treatment method, we analysed retrospectively the outcomes of the patients with Ann Arbor stage I and II non-Hodgkin's lymphoma localized to the head and neck who were treated at Severance Hospital. Materials and Methods: 159 patients with stage I and II non-Hodgkin's lymphoma localized to the head and neck were treated at our hospital from January, 1979 to December, 1992. Of these patients, 114 patients whose primary sites were Waldeyer's ring or nodal region, and received prescribed radiation dose and/or more than 2 cycles of chemotherapy. were selected to analyze the outcomes according to the treatment methods ( radiotherapy alone, chemotherapy alone. and combined treatment with radiotherapy and chemotherapy ). Results: Five year overall actuarial survival of the patients whose Primary site was Waldeyer's ring was $62.5\%.$ and that of the Patients whose primary site was nodal region was $53.8\%$ There was no statistically significant difference between survivals of both groups. Initial response rate to radiotherapy. chemotherapy, and combined treatment was $92\%,\;83\%,\;94\%$ respectively, and 5 year relapse free survival was $49.9\%,\;52.4\%,\;58.5\%$ respectively ( statistically not significant ). In the patients with stage I. 3 year relapse free survival of chemotherapy alone group was $75\%$ and superior to other treatment groups. In the Patients with stage II, combined treatment group revealed the best result with $60.1\%$ of 3 year relapse free survival. The effect of sequential schedule of each treatment method in the Patients who were treated by combined modality was analyzed and the sequence of primary chemotherapy + radiotherapy + maintenance chemotherapy showed the best result ( 3 year relapse free survival was $79.1\%).$ There was no significant survival difference between BACOP regimen and CHOP regimen. Response to treatment was only one significant (p(0.005) prognostic factor on univariate analysis and age and mass size was marginally significant ( p(0.1). On multivariate analysis, age (p=0.026) and mass size (p=0.013) were significant prognostic factor for the relapse free survival. Conclusion: In summary, the patients who have non-Hodgkin's lymphoma of the head and neck with stage I and mass size smaller than 10 cm, can be treated by chemotherapy alone, but remainder should be treated by combined treatment method and the best combination schedule was the sequence of initial chemotherapy followed by radiotherapy and maintenance chemotherapy.

• 한국구조물진단유지관리공학회 논문집
• /
• 제9권4호
• /
• pp.159-168
• /
• 2005

본 연구는 다양한 적층 배열을 갖는 비등방성을 보이는 첨단 복합 신소재 판구조물의 유한 차분 비선형 해석을 수행한다. 복잡한 편미분 방정식으로 표현되는 역학문제들을 수치해석 하는 경우 본 연구에서 사용한 유한차분법은 유한요소법에 비하여 체눈 생성 및 수치적분 과정을 피할 수 장점을 갖는다. 유한차분법을 이용한 많은 연구들은 단지 에너지 방법을 사용한 고정 혹은 단순 경계조건에 대하여 수행되었다. 그러나 이러한 접근방법은 자유경계에 대하여 불가피하게 발생하는 가상점 문제를 충분히 만족시킬 수 없다. 그러므로 본 연구에서는 임의의 경계조건을 갖는 비등방성 복합 적층한의 비선형 거동 문제를 보다 효과적으로 해결할 수 있는 유한차분식을 정식화 하였다. 적층 배열 변화를 비롯한 다양한 매개변수에 대하여 본 연구에서 제안한 접근방법을 사용하여 적층판의 복잡한 비선형 거동을 분석하였다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제8권2호
• /
• pp.247-258
• /
• 2004

복합적층 곡선패널의 비감쇠 강제진동문제를 해결하기 위한 쉘 요소를 제안하였다. 본 연구에서는 절점당 6개의 자유도를 갖는 4절점 EAS 쉘요소를 사용하였다. EAS 방법을 이용하여 전단잠김과 면내잠김 현상을 극복하였으며, 전단보정계수를 사용하지 않고 분포형상함수에 의해 두께방향에 따른 전단변형을 포물선으로 분포시킨 수정된 1차전단변형이론을 적용하였다. Newmark 직접적분법이 시간에 관한 운동방정식의 적분과 시간이력을 해결하기 위해 적용되었다. 곡선패널의 기하학적 조건과 화이버 보강각도 및 적층조건 등의 매개변수 변화에 따른 강제진동응답을 분석하였다.

• Journal of Microbiology and Biotechnology
• /
• 제19권1호
• /
• pp.23-36
• /
• 2009

In the present work, the metabolic network of primary metabolism of the slow-growing myxobacterium Sorangium cellulosum was reconstructed from the annotated genome sequence of the type strain So ce56. During growth on glucose as the carbon source and asparagine as the nitrogen source, So ce56 showed a very low growth rate of $0.23\;d^{-1}$, equivalent to a doubling time of 3 days. Based on a complete stoichiometric and isotopomer model of the central metabolism, $^{13}C$ metabolic flux analysis was carried out for growth with glucose as carbon and asparagine as nitrogen sources. Normalized to the uptake flux for glucose (100%), cells recruited glycolysis (51%) and the pentose phosphate pathway (48%) as major catabolic pathways. The Entner-Doudoroff pathway and glyoxylate shunt were not active. A high flux through the TCA cycle (118%) enabled a strong formation of ATP, but cells revealed a rather low yield for biomass. Inspection of fluxes linked to energy metabolism revealed that S. cellulosum utilized only 10% of the ATP formed for growth, whereas 90% is required for maintenance. This explains the apparent discrepancy between the relatively low biomass yield and the high flux through the energy-delivering TCA cycle. The total flux of NADPH supply (216%) was higher than the demand for anabolism (156%), indicating additional reactions for balancing of NADPH. The cells further exhibited a highly active metabolic cycle, interconverting $C_3$ and $C_4$ metabolites of glycolysis and the TCA cycle. The present work provides the first insight into fluxes of the primary metabolism of myxobacteria, especially for future investigation on the supply of cofactors, building blocks, and energy in myxobacteria, producing natural compounds of biotechnological interest.

• 한국구조물진단유지관리공학회 논문집
• /
• 제11권6호
• /
• pp.113-120
• /
• 2007

연약지반에 시공되는 보강토옹벽과 개비온옹벽에 대해서 옹벽의 안정성을 확보하기 위해 필요한 적정 치환영역을 유한요소해석을 통해 검토하였다. 해석은 연약토층의 압밀단계를 포함하여 시공순서를 모사하는 단계별 해석방법으로 수행되었다. 적정 치환영역의 제안을 위한 첫 단계로 치환깊이를 변화시킨 경우들에 대해서 시공단계에 따른 벽체 및 주변 지반의 거동을 조사하는 일련의 해석을 수행하였다. 이들 해석결과를 문헌연구를 통하여 설정한 옹벽의 안정성을 보장할 수 있는 벽체변위, 지반의 침하량 및 전단변형율 등의 한계값과 비교, 평가하였다. 그 결과, 본 연구에서 검토한 지반조건에서 벽체의 높이가 변하는 경우에 대한 적정 치환영역을 벽체의 높이에 대한 치환깊이의 비로 나타내는 시공표준도를 제안하였다

• 한국구조물진단유지관리공학회 논문집
• /
• 제9권3호
• /
• pp.178-186
• /
• 2005

본 연구에서는 장기공용 중 외부강선보강공법에 의하여 보강된 PSC Beam교량에 대한 강선 파단 시험을 통하여 보강효과를 분석하였다. 외부강선 보강효과를 분석하기 위하여 기 보강된 강선을 인위적으로 절단하면서, 교량의 처짐과 변형률을 측정하였다. 또한 강선절단 전과 후에 재하시험을 실시하여 교량의 거동변화를 평가하였다. 실험결과에 의하면 외부강선 절단 전과 후의 재하시험을 통하여 보강효과가 교량의 거동특성을 크게 변화시키지는 않지만, 보강시의 긴장력에 의하여 고유진동수는 증가하였다. 외부강선 절단시의 처짐과 응력 계측결과로부터 보강효과가 충분히 유지되고 있다는 것을 확인할 수 있었으며, 구조해석 결과와도 잘 일치하였다. 따라서 외부강선을 이용하여 노후교량을 보강할 경우 정밀구조해석을 통하여 그 효과를 예측할 수 있을 것으로 판단된다.