R410A를 사용하는 멀티에어컨 시스템을 위한 사이클 시뮬레이션 프로그램 개발

김영재,박인섭,김학희,윤백,길성호 한국산학기술학회 2002 한국산학기술학회논문지 Vol.3 No.3

본 연구에서 R410A륜 사용하는 멀티에어컨 시스템의 성능(성능계수, 용량, 소비전력 등)을 정상 상태에서 모사할수 있는 Multi_Cycle이라 명명된 컴퓨터 모사 프로그램을 개발하였다. 컴퓨터 시뮬레이션 프로그램을 검증하기 위해서 일련의 사례 연구를 수행하였으며, 이에 대해서 설명하였다. Multi_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 조작조건과 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. In this study, the computer program called Multi_Cycle, which simulates the steady-state performance (coefficient of performance, capacity, power consumption and etc.) of multi- airconditioning systems using R410A, was developed. In order to validate the simulation program, a series of case studies were carried out. The Multi_Cycle consists of several subroutines for simulating indoor units, outdoor unit, compressor, and expansion devices, and for estimating the thermodynamic and transport properties of the refrigerants and moist air, It would appear to be advantageous to use the Multi_Cycle for a performance analysis when considering various kinds of refrigerants and the complex operating conditions of each unit making up the multi-airconditioner cycle. Moreover, the Multi_Cycle would seem to be useful tool in optimizing a multi-airconditioning system and establishing economical and efficient operating conditions in the multi-airconditioner cycle. In the present study, the Multi_Cycle was programmed with Digital Visual Fortran for the main simulation code and Visual Basic for the graphic user interface.

75톤급 액체로켓엔진 정상상태 과정의 수학적 모델링 및 시뮬레이션

이계림,차지형,고상호,박순영,정은환 항공우주시스템공학회 2017 항공우주시스템공학회지 Vol.11 No.5

본 논문은 75톤급 개방형(Open-cycle) 액체로켓엔진(Liquid Propellant Rocket Engine, LPRE)의 수학적모델링 및 정상상태(Steady state)에서의 시뮬레이션을 수행한 내용을 다룬다. 액체로켓엔진의 각 구성품들은 열역학 및 동역학적 특성을 이용하여 크게 7개로 분류할 수 있으나, 본 논문의 액체로켓엔진 시뮬레이션 모델을 간단화하기 위해 열전달 모델링을 생략하여 4개의 지배방정식(Govern equation)을 이용하였다. 정상상태에서의 실험 데이터와 시뮬레이션 데이터의 오차율을 통해 모델링을 확인하였으며 공칭작동점에서의 선형화 모델을 이용하여 안정성을 판단하였다. 또한, 시뮬레이션 모델링을 검증하기 위해실험 데이터의 과도응답을 비교하였다. This paper deals with mathematical modeling of a 75-ton open-cycle Liquid Propellant Rocket Engine (LPRE) and the steady state simulation based on a nominal operating point. Each component of open-cycle LPRE may be classified into seven major categories using thermodynamics and dynamics characteristics. To simplify the simulation model of LPRE in this paper, we used four govern equations with assuming no heat transfer process. We confirmed the mathematical model of LPRE by using the error ratio and comparing the experiment data and simulation data in steady state, and checked the stability with the linearized model. Finally, we demonstrated the simulation model as compared to the transient response of experimental data.

Combining Life Cycle Assessment and Manufacturing System Simulation: Evaluating Dynamic Impacts from Renewable Energy Supply on Product-Specific Environmental Footprints

Jan-Markus Rödger,Jan Beier,Malte Schönemann,Christine Schulze,Sebastian Thiede,Niki Bey,Christoph Herrmann,Michael Z. Hauschil 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

The eco-efficiency of actual production processes is still one dominating research area in engineering. However, neglecting the environmental impacts of production equipment, technical building services and energy supply might lead to sub-optimization or burden-shifting and thus reduced effectiveness. As an established method used in sustainability management, Life Cycle Assessment aims at calculating the environmental impacts from all life cycle stages of a product or system. In order to cope with shortcomings of the static character of life cycle models and data gaps this approach combines Life Cycle Assessment with manufacturing system simulation. Therefore, the two life cycles of product and production system are merged to assess environmental sustainability on product level. Manufacturing simulation covers the production system and Life Cycle Assessment is needed to relate the results to the final product. This combined approach highlights the influences from dynamic effects in manufacturing systems on resulting life cycle impact from both product and production system. Furthermore, the importance of considering indirect peripheral equipment and its effects on the manufacturing system operation in terms of output and energy demands is underlined. The environmental flows are converted into impacts for the five recommended environmental impact categories. Thus, it can be demonstrate that Life Cycle Assessment can enhance the process simulation and help identify hot-spots along the life cycle. The combined methodology is applied for analysing a case study in fourteen scenarios for the integration of volatile energy sources into energy flexible manufacturing control.

효율적인 듀얼 사이클을 위한 야드 트랙터 통제 시스템

정창윤(Chang Yun Chung),신재영(Jae Young Shin) 한국항해항만학회 2011 한국항해항만학회 학술대회논문집 Vol.2011 No.추계

전체 수·출입 공급망 사슬관리에 있어서 항만의 운영 효율성은 아주 중요하다. 컨테이너 터미널에서는 안벽작업의 효율성을 극대화하기 위하여 더블 사이클과 듀얼 사이클 방법이 소개 되었고, 야드 트랙터 할당의 효율성을 높이기 위해서 야드 트랙터(YT) 풀링 방법이 제시되었다. 모형은 시뮬레이션 분석 소프트웨어인 Arena를 이용하여 수립되었다. Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. If, however, we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. Especially, using the existing yard operation method, it is difficult to support to dual and double cycle operation. Therefore, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation. We developed a simulation model using simulation analysis software, Arena.

효율적인 듀얼 사이클을 위한 야드 트랙터 통제 방법

정창윤(Chang Yun Chung),신재영(Jae Young Shin) 한국항해항만학회 2012 한국항해항만학회지 Vol.36 No.1

오늘날 글로벌 수·출입 공급망 내에서 항만 하역작업의 효율성은 아주 중요하다. 해상운송에서는 컨테이너화와 더불어 늘어나는 화물량을 극복하기 위해서 초대형선의 운항이 일반화 되고 있다. 따라서 컨테이너 터미널의 관리자들은 안벽작업의 효율성을 극대화하기 위하여 더블 사이클과 듀얼 사이클 방법을 시도하고 있다. 또한, 야드 트랙터의 할당의 효율성을 높이기 위해서 야드 트랙터 풀링 방법이 제시 되었다. 본 논문에서는 기존의 풀링 방법들과 듀얼 사이클을 고려한 풀링 방법의 비교를 통해서 듀얼 사이클의 효율성을 분석하였다. YT 할당 모형은 시뮬레이션 분석 소프트웨어인 Arena를 이용하여 수립되었다. 실험결과 듀얼 사이클이 많은 것이 항상 크레인 생산성을 높이는 것은 아닌 것으로 분석되었다. Recent global supply chain, improving the efficiency of container shipping process is very important. In the overseas shipping of goods, the voyage of super containership is common to overcome amount of increasing cargo. Thus, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for maximizing the productivity of quay side. Yard Tractors(YTs) pooling methods also are introduced for increasing the efficiency of assignment of YTs. In this paper, we analyzed the efficiency of dual cycling through comparing existing pooling methods with the modified method for the dual cycling. We developed a simulation model using simulation analysis software, Arena. The result of experiment shown that the more dual cycling don't always increase the gross crane rate(GCR), which means productivity of quay cranes(QCs) per hour.

컨테이너 터미널의 효율적인 듀얼 사이클을 위한 야드 운영

정창윤(Chang Yun Chung),신재영(Jae Young Shin) 한국항해항만학회 2011 한국항해항만학회지 Vol.35 No.1

최근 컨테이너 터미널의 관리자들은 안벽의 생산성을 높이기 위해서 양·적하를 동시에 할 수 있는 더블 사이클이나 듀얼 사이클을 시도하고 있다. 하지만 실제 터미널의 데이터를 이용하여 듀얼 사이클을 발생시켰을 경우 YT(Yard Tractor) 배정 방법이나, QC(Quay Crane)의 작업의 속도, 야드의 수출컨테이너 위치 등에 따라 효율성이 저하될 수 있다. 특히 기존의 야드 운영방식으로는 듀얼 사이클이나 더블 사이클을 효율적으로 지원하기 어렵다. 따라서 본 논문에서는 실제 터미널에서 듀얼 사이클을 사용할 때 효율성을 더 높일 수 있는 터미널 야드 운영방법을 제시한다. 모형은 시뮬레이션 분석 소프트웨어인 Arena를 이용하여 수립되었다. Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. If, however, we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. Especially, using the existing yard operation method, it is difficult to support to dual and double cycle operation. Therefore, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation. We developed a simulation model using simulation analysis software, Arena.

Performance comparison between bypass cycle and injection cycle for sub-cooling methods in multi-split variable refrigerant flow (VRF) system in hot seasons

Min, Byungchae,Jang, Seokhoon,Lee, Taemin,Bae, Heunghee,Moon, Cheoreon,Choi, Gyungmin IPC Science and Technology Press 2019 International journal of refrigeration Vol.107 No.-

<P><B>Abstract</B></P> <P>In this study, the performance of a multi-split VRF system using the bypass cycle and injection cycle is evaluated using the numerical simulation as a possible sub-cooling method to prevent flash gas generation in liquid pipelines. The simulation for the multi-split VRF system is developed by considering the applications of the bypass cycle and injection cycle, and is validated with experimental data. The bypass cycle and injection cycle in the multi-split VRF system yield improvements in their cooling capacities of the order of 3.22% and 13.43%, respectively, and energy efficient ratio (EER) of the order of 1.98% and 1.72%, respectively. The input power of the injection cycle is reduced by up to 4.45% when the performance of the multi-split VRF systems with bypass cycle and injection cycle is compared under the same cooling capacity conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The bypass cycle and injection cycle in a multi-split VRF system help increase the sub-cooling degree at inlet of EEV. </LI> <LI> Energy efficiency ratio (EER) of the multi-split VRF system increases with application of the bypass cycle and injection cycle. </LI> <LI> Performance of the VRF system with the injection cycle is more efficient under the same cooling capacity. </LI> </UL> </P>

An assessment of the biodiesel low-temperature combustion engine under transient cycles using single-cylinder engine experiment and cycle simulation

Kim, J.,Kim, K.,Oh, S.,Lee, S. Pergamon Press 2016 ENERGY Vol.95 No.-

An operational strategy was developed to implement LTC (low-temperature combustion) with 50% biodiesel blended fuel (B50), named B-LTC, and evaluated under a combination of a single-cylinder engine experiment and a cycle simulation. The fuel consumption, regulated emissions, and exhaust gas temperature maps were constructed from experiments in a single-cylinder diesel engine at the speed range between 1000 and 1600 rev/min. A dataset of pumping and friction of a 6-cylinder diesel engine was employed to construct a 6000-cm<SUP>3</SUP> B-LTC engine from the SCRE (single-cylinder research engine) experimental results. The engine maps of the virtual 6-cylinder B-LTC engine were then input into a zero-dimensional (0-D) model for the transient-cycle simulation. The cycle simulation was performed under the two representative transient cycles, namely the WHTC (worldwide harmonized transient cycle) and the NRTC (non-road transient cycle). The WHTC simulation estimated the engine-out CSNO<SUB>x</SUB> (cycle-specific NO<SUB>x</SUB>) of 0.94 g/kWh, which was lowered to 0.30 g/kWh by the SCR (selective catalytic reduction), while CSFC (cycle-specific fuel consumption) and cycle-specific soot (CSsoot) were 310 g/kWh and 0.01 g/kWh, respectively. The NRTC simulation results also showed that the engine-out CSsoot emission was 0.01 g/kWh. The urea-dosing SCR model reduced CSNO<SUB>x</SUB> from 0.99 g/kWh to 0.25 g/kWh. The CSFC was 274 g/kWh in the NRTC simulation.

논문 : 경기변동을 이용한 기술보증의 부도율 추정 방법에 관한 연구

김상봉 ( Sang Bong Kim ) 명지대학교 금융지식연구소 2013 금융지식연구 Vol.11 No.2

본 연구는 경기변동을 이용하여 기술보증기금의 부도율을 추정하고 밴드(band)를 설정한 다. 기술보증기금의 자료를 이용하여 연도별 정태적 풀(static Pool)을 이용하여 연간부도율을 계산하고 평균 부도율 스무딩(smoothing)을 이용하여 등급간 부도율을 조정하는 방법을 도입 한다. 또한, 경기변동을 반영하기 위하여 중소제조업 생산지수를 이용하고, 경제현황 별 연도 별 추정부도율과 master Scale을 추정하고 경기변동은 2사이클 경기변동과 4사이클 경기변동을 반영하여 부도율을 각각 산출하였다. 마지막으로 부트스트랩 방법과 몬테카를로 시뮬레 이션을 이용하여 밴드를 설정한다. 실증분석 결과, 중소제조업 생산지수는 7개의 주기를 가 지는 것으로 나타나고 있으며 4사이클의 경우 불황과 회복보다 호황과 후퇴의 평균기간이 길게 나타난다. 또한, 2사이클의 경우 상승기간이 하강기간보다 긴 것으로 나타나고 있다. 이러한 주기를 이용한 4사이클의 master scale은 신용등급별로 0.07%∼25.08%, 2사이클의 경우 0.07%∼24.12%의 범위를 나타내고 있었다. 부트스트랩을 이용하는 경우 4사이클의 밴드는 하한이 0.7%∼6.26%, 상한이 0.07%∼47.98%로 나타나고 있으며 2사이클의 밴드는 하한이 0.07%∼5.09%, 상한이 0.07%∼34.91%로 나타나고 있다. 몬테카를로 시뮬레이션을 이용하는 경우 4사이클의 밴드는 하한이 0.00%∼6%, 상한이 0.07%∼20.02%, 2사이클의 밴드는 하한이 0.00%∼5.50%, 상한이 0.07%∼19.57%로 나타나고 있다. 따라서 부트스트랩으로 구한 등급의 범위보다 몬테카를로 시뮬레이션을 이용한 밴드가 보다 작게 나타나고 있었다. This study extracts a short-term business cycle in the long-term business cycle and then estimates probabilities of default (PD) for KIBO and bands. For estimating PD, we compose annual static pools and calculate historical annual PD before adjusting each grade PD with averaged PD smoothing. With historical PD, reflecting the business cycle is employed. Since most debtors of KIBO are nearly in short and middle manufacturing industry, the portfolio quality of KIBO are very close to Short and Middle Manufacturing Index (SMM Index). Thus, variance and each cycle of SMM Index have been valuable ingredients for estimating the disjunct grade PD of KIBO. However, the simply calculated business cycle could not signify recent trend, we exponentially average the business cycle weighted on recentness and calculate estimated PD with the master scale by separated fluctuation sections. The business cycle including 2-cycle and 4-cycle is used for calculating PD. Finally, we can estimate PD and the master scale of KIBO. Futhermore, using bootstrap method and Monte-Carlo simulation are applicable for bands of the PD. As results, the SMM index has seven periods. With these periods, the master scale of 4-cycle is between 0.07% and 25.08%. In addition, that of 2-cycle is between 0.07% and 24.12%. In case of bootstrap methods, bands is smaller than Monte-Carlo simulation.

CYCLE-SIMULATION TURBULENCE MODELLING OF IC ENGINES

M. SJERIĆ,D. KOZARAC,K. ORMUŽ 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.1

Numerical simulations of IC engines are of high interest for automotive engineers worldwide. The simulation models should be as fast as possible, low-computational effort and predictive tool. The correct prediction of turbulence level inside the combustion chamber of spark ignition engines is the most important factor influencing to the engine working cycle. This paper presents a development of the k-ε turbulence model applied to the commercial cycle-simulation software with the high emphasis on the intake part. The validation was performed on two engine geometries with the variation of engine speed and load comparing the cycle-simulation results of the turbulent kinetic energy and in-cylinder temperature with 3-D CFD results. In order to apply the cycle-simulation turbulence model for the simulation of entire engine map, the parameterization model of turbulence constants was proposed. The parameterized turbulence model was optimized using NLPQL optimization algorithm where the single set of turbulence model parameters for each engine was found. A good agreement of the turbulent kinetic energy during the expansion was achieved when the turbulence affects the flame front propagation and combustion rate as well.