• Journal of Animal Science and Technology
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• 제47권1호
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• pp.107-114
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• 2005

Experiments were carried out to evaluate the air speed distribution of an enclosed nursery pig bay in summer and winter. The data taken by experiments were compared to validate with the calculated air speeds by a commercial CFD code, FLUENT. Air basically enters into the bay through perforated circular ducts overhanged on the ceiling, leaves through a exhaust fan attached on the end-wall of the bay. Air speeds were measured as 2 ${\sim}$ 2.5 mls at the perforated holes in the duct in winter and 7 mls in summer. The validation showed that a CFD simulaton is one of feasible methods to predict airspeed distribution in the nursery pig bay.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.35-42
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• 1999

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But established simulation studies using simulation language have restrictions in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, in this paper addresses object-oriented simulation of container terminal system using a DEVS formalism. In a step of system modeling, using a DEVS formalism aim at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model was developed and verified through the simulation of some alternatives.

• 대한임베디드공학회논문지
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• 제18권2호
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• pp.67-73
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• 2023

Tree routing is one of appropriate routing schemes in wireless sensor network because the complexity of this approach is relatively low. But, congestion at a specific node may happen because a parent node toward a sink node is usually selected in one hop way, specially where large number of node are deployed. As feasible solution for this problem, multiple paths and sinks schemes can be applied. However, the performance of these schemes are not proved and analyzed yet. In this paper, we conduct diverse simulaton scenarios performance evaluation for these cases to identify the improvement and analyze the impact of schemes. The performance is measured in the aspects of packet transmission rate, throughput, and end-to-end delay as a function of amount of network traffic.

• ETRI Journal
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• 제44권1호
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• pp.105-116
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• 2022

In this study, a novel group-indexed orthogonal frequency division multiplexing index modulation (OFDM-IM) scheme is proposed to achieve a tradeoff between spectral efficiency (SE) and bit-error-rate (BER) performance. In the proposed scheme, the total subcarriers in a group are divided into subgroups, and additional bits are transmitted by subgroup indexing, unlike the conventional OFDM-IM scheme, which uses index bits to select active subcarriers. With the proposed scheme, the additional degree of freedom provided by the number of active subgroups selected provides a tradeoff between spectral efficiency and BER performance. Decoding is performed in steps to reduce computional complexity in the decoder design. Simulaton results show that the number of active subgroups selected influences the proposed scheme's performance in terms of energy efficiency, spectral efficiency, and BER performance.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.58-65
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• 2013

In this paper, we propose that a model based design for an electric motor cycle system using ASM (Automotive Simulation Models). Before prototyping a realistic electric motorcycle, a reliable simulation program is required to test the capacities of the power sources and optimize the parameters of an electric motorcycle. Because ASM is based on Simulink, we can design the drivetrain and powertrain of the vehicle model systems easily. To verify the electric motorcycle system analysis of design parameters such as max power, capacity, state of charge and slope angle is carried out by the simulation and experimental method. The predicted results by the development model were in good agreement with the experimentally obtained results. Therefore, the proposed electric motorcycle model can effectively reduce the expenses during the designing of an electric motorcycle system.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.380-387
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• 2015

Various forms of passive shock absorber have developed to supplement performance which is poorer than that of active shock absorber. It is called 'Hybrid Conventional Damper (HCD)'. Frequency sensing shock absorber that this study will cover belongs to the HCD. This study aims to demonstrate that performance of frequency sensing shock absorber is superior than that of passive shock absorber. Study process is as follows. Firstly, analysis models for both passive shock absorber and frequency sensing shock absorber are developed to secure reliability. Then, elements which cause difference of ride quality are found out through comparison of hysteresis characteristics. By comparison of frequency characteristic, furthermore, damping principle of frequency sensing shock absorber is understood. Also, it determines if the absorber performs well even though maximum excitation speed is changed. Finally, the study proves that performance of frequency sensing shock absorber is superior than that of passive shock absorber after comparing change of damping power in excitation condition that various frequencies are mixed.

• 전력전자학회논문지
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• 제14권3호
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• pp.188-196
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• 2009

슈퍼커패시터는 전력밀도가 높고 사이클 수명이 길며 깨끗한 특성으로 인해 신재생에너지원의 동특성 보상 및 배터리의 동작시간이나 수명연장을 목적으로 널리 사용되고 있다. 본 논문에서는 개선된 슈퍼커패시터의 동특성 모델을 전기화학적 임피던스 분광법(Electrochemical Impedance Spectroscopy)을 이용하여 개발한다. 개발된 모델은 슈퍼커패시터의 정확한 동적 행동을 예측하거나 특정 충전상태(State-Of-Charge)에서의 정확한 정전용량 값을 계산하는데 사용될 수 있다. 주파수영역에서 개발된 모델은 Matlab/Simulink 시뮬레이션을 위하여 시간영역으로 등가 변환된다. 시뮬레이션 결과는 실험 결과와 일치하였으며, 이를 통해 개발된 모델의 유용함과 정확성을 증명하였다.

• 대한간호학회지
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• 제48권5호
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• pp.588-600
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• 2018

Purpose: The purpose of this study was to test a model of nursing competencies of nursing simulation learners. The conceptual model was based on the theory of Jeffries's simulaton theory. Methods: Data collection was conducted in October 2017 for 310 students from two nursing universities in Kyungbuk area for 20 days. Data analysis methods were covariance structure analysis using SPSS 21.0 and AMOS 22.0 statistical programs. Results: The hypothetical model was a good fit for the data. The model fit indices were comparative fit index=.97, normed fit index=.94, Tucker-Lewis Index=.97, root mean square error of approximation=.44, and standardized root mean square residual=.04. Teacher factors were directly related to simulation design characteristics, and it was confirmed that the curriculum, classroom operation and teaching method of the instructors were important factors. Learner factors were found to have a direct effect on nursing competence, self-confidence, and clinical performance that belong to nursing capacity. In particular, the results of this study indicate that the simulation design characteristics have a partial mediating effect on learner factors and clinical performance, and a complete mediating effect on learner factors and clinical judgment ability. Conclusion: In order to improve the learner's clinical performance and clinical judgment ability, it is necessary to conduct practical training through nursing simulation besides preparing the learner and the educator.

• 전기전자학회논문지
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• 제22권1호
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• pp.6-13
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• 2018

고신뢰 CPS 개발을 위해서는 M&S는 매우 중요하다. 각각의 CPS 시스템의 다른 부분을 모델링하기 위해 각각의 다른 시뮬레이션 프로그램들을 사용하기 때문에 어떤 CPS 전체 시스템을 하나의 시뮬레이션 툴에서 모델링하기는 쉽지 않다. FMI는 다른 시뮬레이션 툴들 간에 M&S를 위한 표준이다. 또한, DDS는 대규모의 실시간 데이터 전송에 적합한 통신 미들웨어이다. 따라서 이 논문에서는 DDS를 이용하는 FMI기반의 CPS 실시간 분산 시뮬레이션 프레임워크를 제안한다. 제안하는 프레임워크의 성능 평가를 위해서 IEEE HLA/RTI와 OMG DDS 미들웨어를 사용해서 분산 시뮬레이션을 수행하고 전체 시뮬레이션 수행 시간을 측정하고 비교해보았다. 성능 평가 결과를 통해서 DDS를 사용하는 시뮬레이션 수행 속도가 HLA/RTI를 사용하는 것에 비해 최소 1.14배 이상 빠른 것을 확인할 수 있었다.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.103-110
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• 2011

The aim of this study was to analysis the Heating/cooling performance and Daylighting performance of Solar Window System built in apartments. the solar window is the idea to integrate daylight as a third form of solar energy into a PV/Solar Collector system. The process of this study is as follows: 1)Solar Window system was designed through the investigation of previous paper and work. 2)The simulation program(Lightscape3.2) was used in daylighting performance analysis. the reference model of simulation was made up to analysis daylighting performance on Solar Window system. 3)The simulation program(ESP-r, Therm5.0, Window6.0) was used in energy performance analysis. the reference model of simulation was made up to analysis energy and daylighting performance on Solar Window system. 4)The Size of Simulation model for daylighting and heating/cooling energy analysis was $148.5m^2$ 5)The lighting performance analysis was carried out with various variants, such as the size and installed area of Solar Window system. 6)Energy performance simulation was carried out with various variants, such as Integrated U-value of Solar Window system according to its position, installed angle and insulation thickness. Consequently, When Solar Window system is equipped with balcony window of Apartment, Annual heating and cooling energy of reference model was cut down at the average of $4.1kWh/m^2$ or 4.2%.