• Journal of the Korea Society for Simulation
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• v.31 no.1
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• pp.29-41
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• 2022

As one of the alternatives to solve the problem of unstable food supply and demand imbalance caused by abnormal climate change, the need for plant factories is increasing. Airflow in plant factory is recognized as one of important factor of plant which influence transpiration and heat transfer. On the other hand, Digital Twin (DT) is getting attention as a means of providing various services that are impossible only with the real system by replicating the real system in the virtual world. This study aimed to develop a digital twin model for airflow prediction that can predict airflow in various situations by applying the concept of digital twin to a plant factory in operation. To this end, first, the mathematical formalism of the digital twin model for airflow analysis in plant factories is presented, and based on this, the information necessary for airflow prediction modeling of a plant factory in operation is specified. Then, the shape of the plant factory is implemented in CAD and the DT model is developed by combining the computational fluid dynamics (CFD) components for airflow behavior analysis. Finally, the DT model for high-accuracy airflow prediction is completed through the validation of the model and the machine learning-based calibration process by comparing the simulation analysis result of the DT model with the actual airflow value collected from the plant factory.

• Fire Science and Engineering
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• v.24 no.6
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• pp.153-159
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• 2010

In this study, we confirmed the fact that air egress velocity of pressure differential system installed at vestibule of smokeproof stairway in domestic high-rise building becomes back-flow to stair-lobby at upper vestibule. Rather it do not back-flow to the livingroom. when fire occur and the door opens to escape from fire zone. so we carry out actual and computational fluid dynamics measurement. In the case upward 45 gradient of supply damper's blade, The simulation results that air flow of upper vestible is steady but back-flow phenomenon occurred at the bottom. However, in the case of $4m^2$, direction of the flow was ideal to living room. If a vestibule’s area is smaller, it must be designed and built according to performance-based design.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.351-359
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• 2004

Velocity-type repisratory air flow transducer measures dynamic pressure converted from air velocity based on the we1l-known Bernoulli's principle. It requires multiple velocity sampling holes on the flow plane. Measurement error theoretica1ly estimated by computer simulation was demonstrated to significantly reduce by unequally locating the velocity sampling holes. The flow plane was divided into multiple equi-area rings and the sampling holes were located on the circles also equally dividing each ring's area, which decreased measurement error down to 1/5 of the simple equi-radius ring division method. Also, less than 1 ％ relative error was estimated with 4 or more sampling holes. The present technique was less sensitive by <1/2 to the velocity profile change compared to the euqi-radius sampling. Therefore, the present unequal distance velocity sampling technique should be of great use to design the structure of the velocity-type respiratory air flow transducer.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.2
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• pp.161-170
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• 2008

푸쉬-풀 환기시스템은 도금조와 같이 흡인해야 할 거리가 상대적으로 긴 경우에 많이 사용되고 있다. 그러나, 창문이나 출입문을 통한 방해기류가 푸쉬-풀 환기시스템의 오염물질 제어효율을 심각하게 훼손시키고 있다고 추측하고 있으나 이에 대한 세부적인 연구가 부족한 상태에 있다. 따라서, 본 연구에서는 전산유체역학(Computational fluid dynamics)을 이용하여 푸쉬-풀 환기시스템에서의 방해기류의 방향과 세기가 흡인효율에 어떠한 영향을 미치는지에 대해 평가해 보았다. 선형흡인효율(Linear capture efficiency) 방법을 이용하여 푸쉬-풀 환기시스템에서 가상의 개방조에서 발생한 오염물질이 푸쉬-풀 시스템에 의하여 포집되지 못하고 누출되는 구역이 어딘지를 찾아낼 수 있었다. 전산유체역학 컴퓨터시뮬레이션은 AIRPAK2.1 (FLUENT CODE) 소프트웨어를 사용하였다. 푸쉬-풀 후드시스템에 방해기류가 강하게 작용하면 상대적으로 강한 와류가 발생하는데, 일반적인 난류모델인 ${\kappa}-{\varepsilon}$모델은 와류현상을 충분히 보여주지 못한 반면에 RNG 모델을 사용했을 때 실험결과를 적절히 모사해낼 수 있었다. RNG 모델을 이용하여 세가지 방향, 즉 푸쉬에서 풀 방향으로, 풀에서 푸쉬 방향으로 그리고 그에 수직되는 방향으로 방해기류가 있을 때의 푸쉬-풀 환기시스템의 흡인효율을 분석하였다. 방해기류가 0.25m/s이하일 때에는 흡인효율이 거의 떨어지지 않았으나, 방해기류가 0.6m/s에서 흡인효율이 40-70%로 떨어짐을 알 수 있었다. 따라서, 방해기류를 감소시킬 수 있는 방안에 대해서도 연구를 해야 되겠지만, 방해기류 존재 하에서 충분한 흡인 효율을 유지할 수 있는 푸쉬-풀 후드 설계기준에 대한 연구도 필요할 것으로 판단된다.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1036-1041
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• 2008

Double facade systems are often paid attention of as an effective energy saving measure for curtain wall buildings. However, it is not easy to install the system in existing buildings and requires substantial investment. An innovative double window system is proposed in this study which can be installed with exiting window systems in a cost effective way. the proposed system is connected to existing return ducts to make airflow between the existing window and the newly installed window. To ensure the best performance of the proposed system, simulation-based analysis was implemented in which airflow characteristics of inside double window were examined according to air pressures of return duct and window material by using computer simulation ESP-r. the overview of the proposed system and the results of the simulation-based analysis are presented in this paper.

• Journal of Korean Society of Disaster and Security
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• v.13 no.1
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• pp.51-58
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• 2020

This paper analyzes the effect of airflow of ceiling air conditioner on the operation of sprinkler head using a simulation program. The simulation space is 10 m × 7 m × 3 m, and the size of the fire is 0.8 m × 0.8 m × 0.6 m. The cold air flow from the air conditioner is at 25℃ and the wind speed is divided into three cases : 10 ㎧, 8.5 ㎧, and 7.5 ㎧. Simulation results show that all cases had operating delays compared to when the air conditioner was not running, and the sprinkler head did not operate until 10 minutes had elapsed at 10 ㎧ wind speed. These results confirmed that the sprinkler head was delayed in the air conditioning space and the worst result of early evolution failure was observed in strong winds such as 10 ㎧.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.1
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• pp.23-27
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• 2011

This study analyzes about the variation of pressure and stream velocity according to the movement of tail wing. The pressure at the front part of airplane becomes lower than at the rear part and the stream velocity has decreased by being bumped against the wing of airplane. The pressure at the front part of rudder becomes higher than at its rear part according to the movement of rudder among the tail wings of airplane. The more stream velocity becomes decreased, the more rudder spreads out. As the tail wing of airplane folds, the pressure at its front part becomes higher. And the pressure at its rear part becomes lower than at its front part. The more tail wing of airplane folds, the more stream velocity becomes decreased.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.42-47
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• 2011

This study aims to choose installation location of wind power system and analyze influence factors of wind power system by shape of super high-raise building by using CFD simulation. As a result of this study, wind power system is more applicable to streamlined building than normal building. Round openings are seemed to be the most efficient shape for building integrated wind power system in types applying venturi effect. Safety and vibration should be considered in the case of application of wind power system between the buildings.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.193-194
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• 2022

본 연구에서는 특별피난계단의 전실에 설치되는 부속실제연설비가 화재 시 발생한 연기가 부속실 내로 역류하지 않는 급기댐퍼의 적정한 설치위치를 알아보고자 하였으며, 이를 확인하기 위하여 FDS(Fire Dynamics Simulator)을 사용 하였다. 시뮬레이션 Case 총 15가지로 구분하고, 방연풍속은 총 64개의 지점에서 측정하는 시뮬레이션을 수행하였다. 시뮬레이션 결과 출입문 상부 및 하부에서 역 기류가 발행하는 Case가 있었으며, 대부분 출입문 하부에서의 연기 유입이 예상되는 경우가 많았다. 방연풍속은 측정 포인트 64점에서 관련기준에 단 한 곳도 미달하지 않고 만족하는 경우는 총 단 4가지 Case로서 매우 제한적인 것을 알 수 있었다. 그만큼 급기댐퍼의 위치 및 급기방향에 따라 부속실 제연설비의 성능이 다양하게 나타날 수 있다는 것이다. 본 연구를 바탕으로 앞으로 실물실험을 통하여 구체적인 자료가 입증되길 바라고, 더불어 부속실 제연설비의 성능을 개선하는 데 있어 도움이 되었으면 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.249-254
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• 2002

온실에서 환기는 외기와의 공기교환을 통한 온도 및 습도의 조절뿐만 아니라 이산화탄소 등의 가스농도를 조절함으로써 온실내 공기의 쾌적성 확보와 실내기류의 형성으로 인한 작물의 생육촉진에도 중요한 역할을 담당한다. 그러므로, 작물생육환경의 최적화를 통한 품질향상 및 수확량 증대를 목적으로 하는 온실재배에 있어서 환기특성 분석 및 공기유동 예측은 가장 기본적인 설계요소라 할 수 있다. (중략)