• 한국지하수토양환경학회지:지하수토양환경
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• 제19권4호
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• pp.31-44
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• 2014

In the present study, a few of recently developed geostatistical models are comparatively studied. The models are two-point statistics based sequential indicator simulation (SISIM) and generalized coupled Markov chain (GCMC), multi-point statistics single normal equation simulation (SNESIM), and object based model of FLUVSIM (fluvial simulation) that predicts structures of target object from the provided geometric information. Out of the models, SNESIM and FLUVSIM require additional information other than conditioning data such as training map and geometry, respectively, which generally claim demanding additional resources. For the comparative studies, three-dimensional fluvial reservoir model is developed considering the genetic information and the samples, as input data for the models, are acquired by mimicking realistic sampling (i.e. random sampling). For SNESIM and FLUVSIM, additional training map and the geometry data are synthesized based on the same information used for the objective model. For the comparisons of the predictabilities of the models, two different measures are employed. In the first measure, the ensemble probability maps of the models are developed from multiple realizations, which are compared in depth to the objective model. In the second measure, the developed realizations are converted to hydrogeologic properties and the groundwater flow simulation results are compared to that of the objective model. From the comparisons, it is found that the predictability of GCMC outperforms the other models in terms of the first measure. On the other hand, in terms of the second measure, the both predictabilities of GCMC and SNESIM are outstanding out of the considered models. The excellences of GCMC model in the comparisons may attribute to the incorporations of directional non-stationarity and the non-linear prediction structure. From the results, it is concluded that the various geostatistical models need to be comprehensively considered and comparatively analyzed for appropriate characterizations.

• International Journal of Automotive Technology
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• 제7권4호
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• pp.459-468
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• 2006

The objective of this paper is the development of the forward-looking dynamic simulation model of a hybrid electric vehicle(HEV) for a fuel economy study. The specification of the vehicle is determined based on two factors, engine peak power to curb weight ratio and specific engine power. The steady state efficiency models of the powertrain components are explained in detail. These include a spark ignition direct injection(SIDI) engine, an integrated starter alternator(ISA), and an infinitely variable transmission(IVT). The paper describes the integration of these models into a forward facing dynamic simulation diagram using the AMESim environment. Appropriate vehicle and driver models have been added and described. The controller was designed in Simulink and was combined with the physical powertrain model by the co-simulation interface. Finally, the simulation results of the HEV are compared with those of a baseline vehicle in order to demonstrate the fuel economy potential. Results for the vehicle speed error and the fuel economy over standard driving cycles are illustrated.

• 한국정보처리학회논문지
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• 제5권4호
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• pp.883-891
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• 1998

본 논문에서는 원소오토마타 모델의 시뮬레이션에서 SIMD형 병렬성을 이용하는 방법을 제안한다. 제안된 방법에서는 SIMD 병렬성을 이용하여 시뮬레이션에 사용되는 컴퓨터 내에 들어 있는 ALU의 이용도를 높이고 시뮬레이션 시간을 줄인다. 그래서 몇 개의 원소들을 결합하여 하나의 표준 크기의 컴퓨터 단어로 만들고 그 원소들의 상태를 동시에 변환시킨다. 제안된 시뮬레이션 방법의 성능을 보이기 위하여, 본 논문에서는 두 가지 원소오토마타 모델을 세 가지 하드웨어 환경에서 시뮬레이션 하였다. 실험결과로부터, 모든 경우에서 시뮬레이션 속도가 매우 크게 향상되었다. 특히 최상의 경우에는 제안된 시뮬레이션 방법에 의한 속도 향상이 20배에 달하는 경우도 있었다.

• 한국시뮬레이션학회논문지
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• 제5권1호
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• pp.53-66
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• 1996

Container handling facilities in Korean ports have increased rapidly according to Korean industrialization and the worldwide containerization. Over 98% of total containers handles in Korean ports are handled in Puan ports. This paper presents the estimation method of annual container handling capacity of container terminals by the computer simulation models. Simulation models are developed utilizing SIMAN IV simulation package. Annual handling capacity of real container terminals such as BCTOC and PECT was estimated by the proposed simulation models. Also, Annual handling capaicty of planned or expected terminals in Puan port was estimated. The comparisons between container forecast demand and estimated handling capacity of Pusan port from 1996 through 2001 were made. It showed that Pusan port will have over two million TEU handling capacity shortage during that period and will face enormous port congestion. Lastly, mid term and long-term capacity expansion plansof container terminals in korean ports were discussed.

• 한국시뮬레이션학회논문지
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• 제8권1호
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• pp.113-138
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• 1999

Driven by the explosive expansion and acceptance of the Internet and its multimedia front-end, the Web, a new generation of the modeling and simulation tools have come up with the name of Web-Based Simulation (WBS). Most of WBS libraries inherit its powerful advantages from Java. However, there are cases where explicit specification of models or interface objects is more desirable than the black-box programs. This paper presents an XML-based DEVS (Discrete Event System Specification) markup language for sharing simulation models on the Web. DEVS provides a system-theoretic formalism for the language while XML supports platform-independent data access. This paper focuses on the design of such a language.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권4호
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• pp.159-169
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• 2003

Five two-phase closed loop thermosyphons (TLTs) specially designed and constructed for the present study are one small scale loop, two medium scale loops (MSLI and MSLII) and two large scale loops (LSLI and LSLII). Two simulation models based on thermal resistance network, lumped and sectorial, are presented. In the Lumped model, the evaporator section is dealt as one lumped boiling section. Whereas, in the Sectorial model, all possible phenomena which would occur in the evaporator section due to the two-phase boiling process are considered in detail. Flow regimes, the flow transitions between flow regimes and other two-phase parameters involved in two-phase flows are carefully analyzed. In the present study, the results of two different simulation models are compared with experimental results. The comparisons showed that the simulation results by the Lumped model and by the Sectorial model did not show any partiality for the model used for the simulation. The simulation results according to the correlations show the various results in the large different range.

• Journal of the Korean Statistical Society
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• 제30권3호
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• pp.387-406
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• 2001

Adaptive estimators for a class of nonlinear time series models has been proposed by several authors. Koul and Schick(1997) proposed the adaptive estimators without sample splitting for location-type time series models. They also showed by simulation that the adaptive estimators without sample splitting have smaller mean squared errors than those of the adaptive estimators with sample splitting. the present paper generalized the result in a case of location-scale type nonlinear time series models by simulation.

• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.895-903
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• 2009

The penalized partial likelihood based on restricted maximum likelihood method has been widely used for the inference of frailty models. However, the standard-error estimate for frailty parameter estimator can be downwardly biased. In this paper we show that such underestimation can be corrected by using hierarchical likelihood. In particular, the hierarchical likelihood gives a statistically efficient procedure for various random-effect models including frailty models. The proposed method is illustrated via a numerical example and simulation study. The simulation results demonstrate that the corrected standard-error estimate largely improves such bias.

• 한국시뮬레이션학회논문지
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• 제8권4호
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• pp.61-72
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• 1999

This paper presents an estimation method of container handling capacity and selection of resource allocation strategies of container terminals using the computer simulation models. Simulation models are developed to model container terminal consisting of 4 berths considering the berth allocation strategies, crane allocation strategies and the total number of container cranes using Arena simulation package. The proposed models do not consider the yard operations and gate operations. All the input parameters for the models are estimated on the basis of the existing container terminal operation data and the planning data for the automated container terminal planned by Korean government. Four berth allocation strategies and three crane allocation strategies are considered. The total number of container cranes considered ranges from 12 to 15. Non-terminating simulation techniques are utilized for the performance comparison among alternatives. The performance measures such as average ship turnaround time, average ship waiting time, average ship service time, the number of containers handled per year, and the number of ships processed per year are used. The result shows that the berth allocation strategy minimizing the sum of the number of ships waiting, the number of busy container cranes and number of ships handled performs better than any other berth allocation strategies. In addition, the crane allocation strategy allocating up to 5 container cranes per berth performs better than any other crane allocation strategies. Finally there are no significant performance differences among the alternatives consisting of different total number of container cranes allocated.

• 한국시뮬레이션학회논문지
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• 제25권4호
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• pp.117-126
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• 2016

전투지휘훈련의 목적은 컴퓨터 기반의 시뮬레이션 모델을 활용하여 지휘관과 참모들의 지휘통제 및 의사결정 능력을 향상시키는데 있다. 본 연구는 전투지휘훈련을 위한 시뮬레이션 모델에 지휘통제 모델을 포함시키는 방법을 제시한다. 지휘통제 모델을 포함시킴으로써 모델 상에서 모의되는 개별 전투개체 또는 단위부대는 게이머를 통하지 않고 전술적 통제수단으로 구성된 상급부대의 명령을 직접 입력받아 처리할 수 있다. 본 연구에서는 그러한 지휘통제 및 의사결정 과정을 이산사건시스템명세 (DEVS) 형식론을 활용하여 모델로 명세하였다. 또한 본 연구에서는 개체단위 기반의 지휘통제 및 의사결정 과정 모델과 현재 연대 및 대대급에서 활용 중인 전투21모델에서의 모의 결과를 비교하여 사례를 제시하였다. 본 연구에서는 지휘통제 및 의사결정 과정 모델이 갖는 장점 및 기대효과 등을 제시한다.