• 한국터널지하공간학회 논문집
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• 제19권3호
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• pp.517-532
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• 2017

도심지 터널에 주로 적용되는 횡류식 환기방식은 환기구간 거리가 길어질수록 환기성능이 저하되므로 균일한 풍량분배가 필요하다. 본 연구에서는 환기구간 거리가 길어져도 균일한 풍량분배를 통해 설계값의 환기성능을 확보할 수 있도록 급배기구의 개도율을 최적화하는 프로그램을 개발하였으며, TUNVEN DUCT 프로그램과의 비교를 통해 프로그램의 예측 성능을 검증하였다. 이를 위해 반횡류 급기 환기방식을 적용하였으며, 두 프로그램은 유사한 포트 크기 및 풍량 분배를 예측하고 있으며, 계산값의 변동범위는 각각 11.71% 와 1.36% 인 것으로 나타났다. 이 프로그램은 다양한 터널 연장 및 급배기 포트 설치 조건에 대한 신속한 분석이 가능하므로, 횡류식 및 반횡류 환기방식의 포트 최적화 설계에 상당히 유용할 것으로 판단된다.

• 대한기계학회논문집B
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• 제34권8호
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• pp.749-754
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• 2010

비강의 3 가지 생리학적 주요기능은 공기조절, filtering, 후각기능이다. 비강 내 공기유동특성에 대한 지식은 비강 호흡의 생,병리학적 측면을 기반으로 한다. 본 연구실에서는 정상 및 변형된 비강 모델 내 유동에 관하여 일정유량 및 주기유동 하에서 다양한 PIV 실험들을 진행해 왔다. 비대칭 비강을 가진 환자들 중에 일부는 고통을 느끼거나 불편함을 호소하는 반면 그렇지 않은 환자들도 있다. 이 원인을 밝히기 위하여 비중격이 휘어진 비대칭 모델에 대하여 PIV 및 수치해석적인 연구를 진행하였다. 이를 위하여 이비인후과 의사로부터 모델에 관한 CT 데이터를 제공받아 PIV 및 수치해석을 통해 호기 및 흡기시의 RMS 값 및 속도 분포를 얻었다. 모델에 따라 좌우 유량이 크게 다른 것을 확인할 수 있었고 이것이 고통을 느끼는 원인중에 하나가 될 수 있다.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.98-106
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• 2002

The airflow characteristics of an air-conditioning duct with multiple diffusers were investigated through one-dimensional analysis, CFD simulation and experimental measurement. One-dimensional program based on Bernoulli's equation and minor loss equations was developed in order to evaluate the air distribution rate at each diffuser. In CFD simulation, three-dimensional flow characteristics inside air-conditioning duct were computed for incompressible viscous flow, adopting the RNG k-$\xi$turbulence model. Also, in an effort to equalize the discharge flow rate at each outlet, the optimization procedure has been performed to obtain the optimum diffuser area. In this process, square of difference between maximum discharge rate and minimum discharge rate is used as an object function. Diffuser area and discharge velocity are established as constraints. After optimization process, determined design variables are applied again in CFD simulation and experiment to validate the optimized result by one-dimensional program. Comparison with the experimental data of airflow rate distribution showed that the developed program seems to be acceptable and can be useful design tool for an automotive air-conditioning duct in an initial design stage.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.798-803
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• 2009

In this study, dimensionless correlations of frost properties (i.e. the thickness and surface temperature of frost) on heat exchanger fin with nonuniform temperature distribution are proposed from frosting experiments. We analyzed the local fin temperature distribution, frost thickness and frost surface temperature on a 2D fin; in the airflow direction and the direction perpendicular to airflow. As a result, the frost growth on the fin had a close relation with fin heat conduction. The dimensionless correlations for the average frost properties were expressed as a function of dimensionless temperature, humidity ratio, Reynolds number, and Fourier number. These correlations agreed well with experimental data with the error less than 14%.

• 한국산업보건학회지
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• 제11권1호
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• pp.78-84
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• 2001

A CFD simulation of airflow and temperature field in a heated room has been described in this paper. The thermal wall jet created by a radiator greatly influences the airflow pattern, temperature distribution. The area close La a heat source has a higher risk of air-borne contamination and imposes a harmful effect on occupants in that area. The predicted flow field, temperature results show good agreement with the measured data. As the results were compared with experimental data, the applicability of CFD was satisfactorily verified. Also, the CFD simulation can capture the natural convective flow features. If a CFD simulation is applied ventilation design with a heat source, An effective design will be attained. Further study is required to improve the accuracy of CFD simulation.

• 대한기계학회논문집B
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• 제26권7호
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• pp.1022-1030
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• 2002

The experiments were performed with a $31{\times}31{\times}7mm^3$ simulated 3-dimensional module on the thermal conductive board of a parallel plate channel. The convective thermal conductance for the path from the module surface directly to airflow and conjugate thermal conductance for the path leading from the module to the floor by way of a module support, then, to the airflow were determined with several combinations of module-support-construction(210, 0.32, 0.021 K/W)/floor-material(398, 0.236W/mK) and channel height(15-30mm). As the result, it was found that the conjugate thermal conductance and the temperature distribution around the module depend on the thermal resistance of the module support, and the channel height. These configurations were designed to investigate on the feasibility of using the substrate as an effective heat spreader in the forced convective air-cooling of surface mounted heat source. The experimental results were discussed in the light of interactive nature of heat transfer through two paths, one directed from the module to the airflow and the other via the module support and the floor to the air.

• 한국가시화정보학회지
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• 제9권3호
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• pp.65-70
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• 2011

Three major physiological functions of nose can be described as air-conditioning, filtering and smelling. Detailed knowledge of airflow characteristics in nasal cavities is essential to understanding of the physiological and pathological aspects of nasal breathing. In our laboratory, a series of experimental investigations have been conducted on the airflows in normal and abnormal nasal cavity models by means of PIV under both constant and periodic flow conditions. In this work, more specifically experimental and numerical results on the surgically modified inferior turbinate model were presented. With the high resolution CT data and a careful treatment of the model surface under the ENT doctor's advice yielded quite sophisticated cavity models for the PIV experiment. Physiological nature of the airflow was discussed in terms of velocity distribution and vortical structure for constant inspirational flow. Since the inferior and middle turbinate are key determinants of nasal airflow, the turbinectomy obviously altered the main stream direction. This phenomenon may cause local changes in physiological function and the flow resistance.

• 도시과학
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• 제8권1호
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• pp.25-31
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• 2019

Infiltration affects indoor environmental and air quality and energy consumptions in buildings. Especially, airflow and the infiltration are more remarkable in high-rise buildings due to the air-driving forces (stack and wind effects). Thus, it is important to understand infiltration distributions in high-rise residential buildings. In this study, the weather-driven infiltration is characterized from the viewpoint of interactions between external wind and stack effect in high-rise residential buildings. To calculate accurately the annual infiltration distributions, this study also suggests an airflow and thermal simulation method with a two-step calibration of air-leakage data. The simulated results show (1) how the interaction between stack and wind effects induce infiltration types (outdoor and interzone air infiltration) and (2) how much the interzone air infiltration (being ignored in previous studies) occurs due to the stack effect, as well as the outdoor air infiltration rates.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2004년도 동계학술대회 논문집
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• pp.33-33
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• 2004

• 한국안전학회지
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• 제14권3호
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• pp.33-39
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• 1999

In a compartment fire with openings, convective heat transfer consists of natural convection from the hot bodies and forced convection by airflow through the openings. The same finite volume method that was applied to pure natural convection in part I was utilized without modification to the square cavity with two openings. The objective of this study is to investigate effects of the openings on temperature distribution. Flow patterns, temperature distribution and heat transfer were compared for different Rayleigh numbers and with and without the openings.