• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.157.3-157
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• 2001

In this paper, the optimal maintenance scheduling for turbine with considering maintenance replacement rate was proposed in order to reduce the maintenance cost during the whole period of operation, meanwhile keeping current reliability of turbine. The proposed method is only based on a few limited available data with various factors relating to maintenance replacement and repair of turbine. The proposed method will be adopted by Kyushu Electric Power Co., Inc. from April in 2002 to determine the maintenance schedule of thermal power plants.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.59-63
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• 2011

Friction damping is one of the attractive vibration control technique for space structures due to its simplicity and large damping capacity. However, passive approaches for friction damping have a limitation because energy is no longer dissipated at sticking. In order to overcome this problem, semi-active control methods to adjust normal force at frictional interface have been studied in previous researches. In this paper, two semi-active friction control method is compared by simulating SDOF model of truss structure. The first approach is on-off control to maximize rate of energy dissipation, whereas the second concept is variable friction force control to minimize amplitude ratio for each half period. The maximum friction force, control variable in on-off control method, is obtained to minimize 1% settling time, and is different from optimal friction force in passive control. Simulation results show that performance of on-off control is better than that of variable friction force control in terms of settling time and controlled friction force.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1430-1437
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• 2005

It is very important to achieve a high reproducibility in the ultrasonic measurement of bone mineral density. In this study, we examined number of sampling waveform, control of temperature, diameter of region of interest as factors to improve reproducibility. We decided the optimal number of waveforms to be converted to frequency domain as period of 1. We have minimized the effects of variable temperature and constrained generation of micro bubble by keeping temperature within a range of $32\pm0.5^{\circ}C$ with a precise temperature controlling algorithm. We also found the optimal diameter of region of interest to be 13mm. In this paper, we demonstrated the improved reproducibility by controlling various factors affecting the ultrasonic measurement of bone mineral density.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 춘계학술대회논문집
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• pp.129-134
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• 2003

In this paper, we determine optimal reduction in the lead time and setup cost for some stochastic inventory models. And we propose more general model that allow the backorder rate as a control variable. We first assume that the lead time demand follows a normal distribution. And we assume that the backorder rate is dependent on the length of lead time through the amount of shortages. The stochastic models analyzed in this paper are the classical continuous and periodic review policy models with a mixture of backorders and lost sales. For each of these models, we provide a sufficient conditions for the uniqueness of the optimal operating policy. We also develop algorithms for solving these models and provide illustrative numerical examples.

• 한국동물위생학회지
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• 제23권3호
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• pp.289-299
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• 2000

The study was performed to investigate the distributions of swine pleuropneumonia in Kyongbuk western area by the enzyme-linked immunosorbent assay (ELISA). Sera collected from 400 slaughtered pigs in 3 slaughter houses during the period from May 1999 to october 1999 were tested to detect antibodies against A pleuropneumonie serotype 2 and 5. The optimal dilution of CBE antigen, conjugate and serum for this ELISA were determined 1 : 400, 1 : 20,000, 1 100, respectively. The optimal dilution of OW antigen, conjugate and serum for this ELISA were determined 1 : In, 1 : 20,000, 1 : 200, respectively. Cut-off value in this ELISA was determined by mean absorbance (at 492 nm) of negative control sera added with the triple value of the standard deviation. Cut-off value in ELISA by CBE and OMP antigen were 1.134 and 1.217, respectively. By the ELISA, positive reaction rates to A pleuropneumoniae serotype 2 and 5 for CBE antigen were 38.8% and 18.8%, and for OMP antigen were 42.8% and 23.5% of the 400 samples, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.331-343
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• 2015

We propose a distributed medium access control protocol for cognitive radio networks to opportunistically utilize multiple channels. Under the proposed protocol, cognitive radio nodes forecast and rank channel availability observing primary users' activities on the channels for a period of time by time series analyzing using smoothing models for seasonal data by Winters' method. The proposed approach protects primary users, mitigates channel access delay, and increases network performance. We analyze the optimal time to sense channels to avoid conflict with the primary users. We simulate and compare the proposed protocol with the existing protocol. The results show that the proposed approach utilizes channels more efficiently.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.527-533
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• 1998

An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses, and has been therefor recognizedas the perfered PWM method, especially in the case of digital implementation. Three-phase invertor voltage control by space vector modulation consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The prefered switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by suing the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.60.1-60
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• 2001

In recent years, distributed control systems(DCS) using fieldbus such as CAN have been being applied to process systems but it is very difficult to design the DCS in order to guarantee the given end-to-end constraints such as precedence constraints, time constraints, and periods and priorities of tasks and messages. This paper presents a scheduling method to guarantee the given end-to-end constraints. The presented scheduling method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to be applied to a general DCS that has multiple loops with several types of constraints, where each loop consists of ...

• Journal of Animal Science and Technology
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• 제48권6호
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• pp.897-906
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• 2006

본 연구는 셀레늄강화 한우고기 생산을 위하여 셀레늄강화 버섯폐배지(Se-SMC)가 함유된 셀레늄사료(사료내 셀레늄함량: 0.9ppm)를 활용하여 급여사양기간(2개월, 3개월, 4개월)을 달리 하였을 때, 비육후기 거세한우의 조직 내 셀레늄 함량과 혈중 글루타치온 과산화효소(GSH-Px) 활성에 미치는 영향을 조사하여 최대 포화축적기간을 제시하고자 실시하였다. 본 연구에 사용된 비육후기 거세한우는 30두로 각 급여기간(2개월: 평균 체중 677kg, 3개월: 평균 체중 610kg 및 4개월: 평균 체중 524kg)에 대한 대조구 및 Se-SMC 급여구로 나누어 처리구당 5두씩 배치하여 총 6처리구로 구분하여 실시하였다. 대조구와 Se-SMC 급여구에 사용된 실험사료는 0.1과 0.9ppm의 셀레늄을 각각 함유하였다. 각 급여기간이 종료되면 도축하여 후지와 간을 채취하였으며 이를 셀레늄 함량분석에 이용하였다. 그리고 혈중 셀레늄 농도 및 글루타치온 과산화효소활성을 분석하기 위하여 도축 시에 채혈을 실시하였다. 건물섭취량은 Se-SMC 급여 및 급여기간에 의하여 유의한 차이가 나타나지 않았다. 또한 일당증체량은 대조구 및 Se-SMC 급여구간 그리고 급여기간 간에 유의한 차이가 나타나지 않았을 뿐만 아니라 총증체량 또한 각 급여기간내 대조구와 Se-SMC 급여구 간에 유의한 차이가 나타나지 않았다. Se-SMC 급여는 혈중 셀레늄농도를 유의하게 증가시켰으나(P<0.001), 급여기간에 따른 혈중셀레늄 농도에는 유의한 영향을 미치지 않았다. 아울러 혈중 GSH-Px 활성은 혈중 셀레늄농도에서 나타난 양상과 유사한 경향을 나타내었고, 급여기간에 의한 효과는 나타나지 않았다. 후지내 셀레늄 함량은 급여기간(P<0.05)이 증가함에 따라, 그리고 Se-SMC 급여(P<0.001)에 의하여 유의하게 증가하였다. 하지만, Se-SMC의 3개월 급여군과 4개월 급여군 간에는 유의한 차이가 나타나지 않았다. 간내 셀레늄 함량은 Se-SMC의 급여기간이 증가함에 따라 다소 증가하는 경향을 나타내었으나 유의한 효과는 나타나지 않았다. 하지만, 동일한 급여기간 내 Se-SMC는 대조구에 비하여 유의하게 높았다(P<0.01).이상의 결과로부터 근육내 셀레늄 축적을 위한 적정 Se-SMC 급여기간은 후지와 간내 셀레늄 함량을 고려할 때 약 2 내지 3개월의 급여가 충분할 것으로 사료된다.

• 수산해양교육연구
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• 제12권2호
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• pp.142-151
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• 2000

The studies on the electronic control fuel injection system for a DI diesel engine have done for reducing the exhaust emission and improving fuel consumption. The electronic control fuel injection system is classified into a common rail system, a unit injector system and a high pressure injection system. The characteristics of these systems are largely depends on the operating characteristics of its solenoid that have high speed on-off operation. In order to improve these characteristics of fuel injection system, it is necessary to design the optimal shape of solenoid and select the input method of its power source. It was proposed HELENOID, COLENOID, DISOLE, and Multipole Solenoid in the studies of design for the optimal shape of solenoid. The studies on the energizing method, input method for power of solenoid were dealt with the conventional energizing method, the chopping method and the pre-energizing method. In order to find out the high response characteristics of solenoid, it is necessary to test the performance of optimally designed solenoid with a new energizing method. In this paper, the solenoid of multi-pole type with plat armature and its power control unit to control input current by the chopping method designed, and its response tests were performed according to its energizing conditions. As a result, the maximum input current for solenoid was controlled by the period of first stage exciting current and chopping duty ratio of control stage exciting current, and the fastest "on" time was able to get 0.46ms. The conditions of fastest "on" time was 0.3ms for first stage exciting current, 0.16ms for control exciting current and 75% for chopping duty ratio.