• 대한기계학회논문집
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• 제19권1호
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• pp.231-239
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• 1995

This paper describes a computer simulation of the triple effect, water-lithium bromide absorption cooling cycles. The performance of the absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature, the working solution concentrations, the ratio of the amount of the weak solution to the high, middle and low temperature generators, and the temperature difference of each solution heat exchanger. The efficiency of different cycles has been studied and the simulation results show that higher coefficient of performance could be obtained for the parallel cycle of constant solution distribution rate. As a result of this analysis, the optimum designs and operating conditions were determined based on the operating conditions and coefficient of performance.

• Journal of Advanced Marine Engineering and Technology
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• 제26권2호
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• pp.248-255
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• 2002

Miller cycle was studied and analyzed by engine performance simulation to achieve very low fuel consumption and to meet the IMO NOx regulation on a medium speed diesel engine. Based on the performance simulation results the intake valve closing time for HYUNDAI HiMSEN 6H21/32 engine was set at 0deg.ABDC(After Bottom Dead Center). Also, the simulation results indicated that significant NOx reduction could be achieved with low reduction of fuel consumption. The performance simulation investigated the effect of compression ratio and turbocharger on fuel consumption and NOx concentration in combination with Miller cycle. The results indicated a significant reduction of fuel consumption with keeping NOx concentration. The results of performance simulation were compared with measured data to verify simulation results. The comparison showed the maximum error was 2.34% in exhaust temperature. Also, the experimental result showed that improvement in BSFC(Brake Specific Fuel Consumption) was 5.8g/kwh with keeping NOx level similar to simulation result.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.294-298
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• 1999

In this paper, through simulations, we find the second derivative SPA(Smoothed Perturbation Analysis) estimates of mean busy cycle with respect to a given parameter in a Markov renewal process which is generated by two exponential distributions. We compare these SPA estimates with the traditional SD(symetric difference) estimates.

• 설비공학논문집
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• 제15권6호
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• pp.471-479
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• 2003

A simulation on the performance of a transcritical $CO_2$ heat pump system is carried out to investigate its characteristics for various operating conditions. Cycle simulation models are established for a steady-state simulation and are verified by comparing experimental data. Based on correlations and methods available in the literature, the processes in individual components of the transcritical cycle are simulated to analyze the performance of $CO_2$ transcritical heat pump system. The simulation models are good enough to predict the performance of a $CO_2$ transcritical cycle. Simulation results are provided to show the relative effects when varying the size of internal heat exchanger and the discharge pressure of a compressor.

• 한국기계가공학회지
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• 제14권1호
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• pp.1-8
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• 2015

Productivity of machining using machine tools is affected by cutting conditions such as cutting speed, feedrate and depth. However, undesirable conditions that lengthen the machining cycle and shorten the tool life occur frequently because determination of cutting condition is known to depend on human experience. This paper presents a method of cycle reduction by removing undesirable conditions. For cycle reduction, maximum cutting load is determined using commercial FEM simulation code. The feedrate in the NC program is altered based on a predetermined cutting load value. To make a decision on the proposed effectiveness, a simulation is performed for the brake hub parts of an automobile. From the evaluation, it was found that the cycle reduction was under 15%.

• 한국항만학회지
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• 제10권2호
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• pp.43-50
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• 1996

The purpose of this paper is to develop the cycle time simulation system for the various types of container cranes - container cranes, RMGC, RTGC, OHBC. First, the paper describes the derivation of the cycle time formula for crane simulation and the development of the simulation logic. And, the paper includes details on the design and implementation of the computer simulation system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.255-262
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• 2008

The simulation of refrigeration cycle is important since the experimental approach is too costly and time-consuming. The present simulation focuses on the effect of capillary tube-suction line heat exchangers (CT-SLHX), which are widely used in small vapor compression refrigeration systems. The simulation of steady states is based on fundamental conservation equations of mass and energy. These equations are solved simultaneously through iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tubes. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP). These results can be used in either design calculation of capillary tube length for refrigeration cycle or effect of suction line heat exchanging on refrigeration cycle.

• 한국산학기술학회논문지
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• 제3권3호
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• pp.210-215
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• 2002

본 연구에서 R410A를 사용하는 멀티에어컨 시스템의 성능(성능계수, 용량, 소비전력 등)을 정상 상태에서 모사할 수 있는 Multi_Cycle이라 명명된 컴퓨터 모사 프로그램을 개발하였다. 컴퓨터 시뮬레이션 프로그램을 검증하기 위해서 일련의 사례 연구를 수행하였으며, 이에 대해서 설명하였다. Mulli_Cycle은 실내기, 실외기, 압축기와 팽창 밸브 모사를 위한 부프로그램 및 냉매와 습공기의 열역학적 물성치와 전달 물성치 예측을 위한 부프로그램으로 구성되어있다. 멀티에어컨 사이클을 구성하고 있는 각 유닛의 복잡한 조자조건과 다양한 종류의 냉매를 고려해야 하는 멀티에어컨의 성능 분석시 Multi_Cycle의 사용은 많은 도움이 될 것이다. 나아가, Multi_Cycle은 멀티에어컨 시스템을 최적화하고, 경제적이고 효율적인 운전 조건을 확립하는데 매우 유용한 도구가 될 수 있을 것이다. Multi_Cycle의 주시뮬레이션 코드는 Digital Visual Fortran으로 프로그램 되었으며 그래픽 사용자 인터페이스(GUI)는 Visual Basic으로 프로그램 되었다.

• 항공우주기술
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• 제11권1호
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• pp.145-157
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• 2012

상평면상에서 추력기를 사용하는 자세제어 시스템의 리밋 사이클을 해석하는 새로운 기법이 논문에 의해서 제안되었다. 그러나 이것은 소프트 시뮬레이션상에서 Haloulakos 방식보다 제안 방식이 정확함을 보였지만, 실제 시스템으로 검증하지는 못하였다. 그래서 저자의 제안 방식을 KSLV-I 추력기 자세제어 시스템에 대한 실시간 모의시험으로 검증하고, 리밋 사이클 해석에 대하여 실시간 모의시험 결과와 이론적으로 구한 값을 비교/분석하였다.

• 한국시뮬레이션학회논문지
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• 제21권1호
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• pp.1-8
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• 2012

최근들어, 글로벌 조선소들은 친환경 선박 건조와 환경 친화적 생산 공정에 큰 관심을 보이고 있다. 이러한 추세에 따라 이 연구는 조선소 레이아웃에 전 과정 평가를 적용하는 연구를 수행하였다. 전 과정 평가는 제품과 시스템의 전수명주기와 관련된 환경적 영향을 평가하는 기법으로 특정 산업분야에서 ISO 14040 표준에 따라 적용연구가 수행되고 있다. 전 과정 평가를 조선소 레이아웃에 적용하기 위해 조선소 레이아웃 계획 프레임워크를 분석하고, 조선소 레이아웃에 대한 목록분석을 수행하였으며, 환경적 영향에 대한 이산 사건 시뮬레이션 모델을 구축하였다.