• 한국추진공학회지
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• 제14권1호
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• pp.29-39
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• 2010

증기분사 재생 가스터빈 시스템의 성능을 해석하고 최적 운전조건을 분석하였다. 해석모델을 통해 압력비, 증기분사율, 주위온도나 터빈입구온도 등의 설계변수들이 시스템의 열효율, 연료소모율, 비동력등 성능에 미치는 영향을 최적 운전조건에서 분석하였다. 해석결과들은 증기분사가 재생 가스터빈시스템의 열효율과 비동력을 대폭 향상시킬 수 있음을 보여주었다.

• 대한기계학회논문집A
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• 제28권9호
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• pp.1422-1428
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• 2004

In this paper, computer simulation model of handrail band including pulley-driving system is developed to calculate handrail slippage. This handrail simulation model is validated with test result within operating range and used to predict its slippage behavior with respect to variation of 4 different design parameters considering the applicability into the real handrail system. Based upon this parameter study, optimal condition for handrail slippage improvement is proposed without time-consuming and costly experiments of the real handrail system. And then performance improvement of handrail slippage complied with safety code is achieved after applying the optimal condition into the real handrail band system.

• 대한조선학회논문집
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• 제49권1호
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• pp.33-44
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• 2012

In this study, the optimal operating conditions for the dual mixed refrigerant(DMR) cycle were determined by considering the power efficiency. The DMR cycle consists of compressors, heat exchangers, seawater coolers, valves, phase separators, tees, and common headers, and the operating conditions include the equipment's flow rate, pressure, temperature, and refrigerant composition per flow. First, a mathematical model of the DMR cycle was formulated in this study by referring to the results of a past study that formulated a mathematical model of the single mixed refrigerant(SMR) cycle, which consists of compressors, heat exchangers, seawater coolers, and valves, and by considering as well the tees, phase separators, and common headers. Finally, in this study, the optimal operating conditions from the formulated mathematical model was obtained using a hybrid optimization method that consists of the genetic algorithm(GA) and sequential quadratic programming(SQP). Moreover, the required power at the obtained conditions was decreased by 1.4% compared with the corresponding value from the past relevant study of Venkatarathnam.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.552-559
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• 2020

This paper presents an observer-based chattering free robust optimal control scheme to regulate the total power of a nuclear reactor. The non-linear model of nuclear reactor is linearized around a steady state operating point to obtain a linear model for which an optimal second order integral sliding mode controller is designed. A second order integral sliding mode observer is also designed to estimate the unmeasurable states. In order to avoid the chattering effect, the discontinuous input of both observer and controller are designed using the super-twisting algorithm. The proposed controller is realized by combining an optimal linear tracking controller with a second order integral sliding mode controller to ensure minimum control effort and robustness of the closed-loop system in the presence of uncertainties. The condition for the selection of gains of discontinuous control based on the super-twisting algorithm is derived using a strict Lyapunov function. Performance of the proposed observer based control scheme is demonstrated through non-linear simulation studies.

• International Journal of Precision Engineering and Manufacturing
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• 제4권6호
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• pp.38-43
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• 2003

In this study, the optimal dynamic absorbing system for the gas operated HIF (high implusive force) device has been investigated. For this purpose, firstly, the dynamic behavior of human body induced by impulsive disturbances has been analyzed through a series of experimental works using the devised test setup. The characteristics of linear impulse has been compared under some conditions of support system. In order to design the optimal dynamic absorbing system, the parameter optimization process has been performed based on the simplified isolation system model under constraints of moving displacement and transmitted force. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation in the actual operating condition.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.170-178
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• 2005

Multi-hole type oxygen combustion burner was developed for industrial gasification and smelting furnace. We investigated characteristics of flame, radiation transfer, and soot emission in the convectional oxygen burner with respect to the feeding condition of fuel and oxygen. Regarding the results of the conventional burner, we designed new burners which have larger fuel consumption rate and radiation heat transfer. We changed the size and hole number and shape of the exit plane of the burner. In addition, the performance of the burner was tested with respect to the feeding condition of the fuel and air: Normal Diffusion flame(NDF) and Inverse Diffusion Flame(IDF). We investigated the flame configuration, radiation heat transfer, and soot formation by using a CCD camera, heat flux meter, and Laser Induced Incadescence(LII), respectively. The stable operating condition was obtained by the flame configuration and the flame of the burner which has dented exit plane was more stable in whole operating conditions. The characteristics of radiative heat transfer were sensitive to the feeding condition of reactants and the flame of 75% primary oxygen and 25% secondary oxygen of the IDF case shows maximum radiation heat transfer. The soot volume fraction of the flame was measured in the axial direction of the flame and the amount of soot volume fraction is proportion to the radiation heat transfer. As a result, we can get the optimal operating condition of the newly designed burner which enhances the characteristics of flame stabilization and radiation heat transfer.

• 산업공학
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• 제24권4호
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• pp.274-280
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• 2011

Delayed access to surgery may lead to deterioration in the patient condition, poor clinical outcomes, increase in the probability of emergency admission, or even death. The purpose of this work is to decide the number of patients selected from a waiting list and to schedule them in accordance with the operating room capacity in the next period. We formulate the problem as an infinite horizon Markov Decision Process (MDP), which attempts to strike a balance between the patient waiting times and overtime works. Structural properties of the proposed model are investigated to facilitate the solution procedure. The proposed procedure modifies the conventional value iteration method along with the binary search technique. An example of the optimal policy is provided, and computational results are given to show that the proposed procedure improves computational efficiency.

• 설비공학논문집
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• 제3권4호
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• pp.276-285
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• 1991

The transient heat transfer characteristics in the radiant heating panel were predicted by numerical analysis. Thermal behaviors of panel, such as temperature distributions in panel and convective and radiative heat fluxes in panel surface with respect to time were obtained. Heating hours per day, rate of energy supplied and maximum temperature differences at panel surface were also compared for several important parameters. The performance and thermal comfort of heating panel were studied and compared for various operating and design conditions such as pipe pitch, pipe location, pipe diameter and flow rate of hot water for the purpose of producing useful data, which can be used for the test and decision of efficient operating condition of the conventional heating systems or the optimal design of the new panel heating systems.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.337-342
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• 2018

도시유역에서 발생되는 내수침수를 방어하는 수단으로 구조적 대책인 빗물펌프장이 있으나 현실적 적용에 어려움이 있기 때문에 비구조적 대책 등이 보안되어야 한다. 본 연구에서는 빗물펌프장 실무운영 담당자의 의견을 반영한 최소의 월류량을 가지는 펌프의 최적운영수위를 결정하였다. 빗물펌프장의 최적운영수위를 산정하기 위해 최적화 기법인 GA(Genetic Algorithm)을 이용하였으며, 도시유역의 강우-유출 모형인 SWMM(Ver.5.1) DLL과 연계하였다. 제약조건으로는 펌프의 효율을 극대화하는데 까지의 걸리는 시간을 고려하였으며, 최적운영수위를 산정한 결과 전체적으로 기존운영수위보다 낮은 운영 수위에서 월류량이 감소하였다. 대부분 펌프의 경우 각 펌프 호기의 운영 범위에서 가장 낮은 운영 수위가 선정되었다. 초기 펌프의 운영하는 것이 월류량을 저감할 수 있는 것으로 판단되며 이 후 펌프 운영 조건 변경을 하여도 월류 저감에 변화는 없는 것으로 나타났다. 내수침수 저감정도는 약 1%~2%로 산출되었으며, 하류지역에서 발생되는 월류량을 저감하는 정도이지만, 펌프의 운영적 관점에서 기계적 및 실무적 관점의 접근에 따른 효과적인 운영이라 판단된다. 향후, 펌프의 운영조건 등을 고려한다면, 펌프의 효율을 증대하고 내수침수를 저감하는데 도움이 되리라 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.403-407
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a greenhouse culture facility for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex in Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.