• 한국터널지하공간학회 논문집
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• 제19권2호
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• pp.319-333
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• 2017

초장대 해저터널의 건설은 건설공간의 제약 및 건설비용 측면에서, 공사중에 사용되는 환기 시스템 설치에 유리한 조건을 갖고 있지 않다. 공사중 환기시스템을 제공하기 위해, 환기갱이 설치되는 인공섬들이 해저터널의 루트를 따라서 일부위치마다 건설됨으로써, 건설 비용이 많이 소요된다. 따라서 이러한 인공섬의 수를 최소화하는 것이 경제적으로 필요하다. 그러나 이것은 환기갱 사이의 거리가 더 길어지게 되므로, 필요한 환기풍량을 이송하기 위한 높은 팬 압력으로 인해 환기 덕트 접속부에서 누풍이 더 많이 발생하게 된다. 선행 연구에서 공기 누설이 중요한 문제임을 조명하였다. 본 연구는 개선된 덕트 접속 방식을 개발하기 위한 실험들을 소개하고, 또한 SIA 의 "S" 등급 누풍율 및 다양한 조건들을 비교하여 터널 연장에 따른 달성된 누풍율의 환기 성능을 제시한다. 본 연구의 결과로 누풍율이 $1.46mm^2/m^2$인 새로운 접속방식을 개발하였으며, 개선된 방식이 30 km규모의 장대터널에 적합한 것으로 분석되었다.

• 설비공학논문집
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• 제20권10호
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• pp.696-701
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• 2008

From Feb. 2006, the ventilating systems with air exchange rate of over 0.7times/hour are installed at the apartment houses (over 100 units). Installation cost and maintenance cost are very important factors for ventilating system because consumers have to pay the expenses of that system. Especially small apartment needs more considerations because small apartment is comparatively the economically weak part. The purpose of this study is to the performance evaluation of the hybrid ventilation system for small apartment houses. Hybrid system 1 consists of natural ventilation system and duct type exhaust diffusers. Hybrid system 2 has natural ventilation system and toilet exhaust system with static pressure fan. Infiltration of test apartment houses with ventilation system is under 0.1 times/hour. Mean air age of hybrid system 1 is 1.52 hours and hybrid system 2 is 1.42 hours. Mean ventilation effectiveness of hybrid system 2(93%) is higher than that of hybrid system 1(81%).

• 한국산학기술학회논문지
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• 제21권9호
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• pp.610-616
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• 2020

본 연구에서는 대한민국 해군 함정의 하절기 운용 및 적도지병 파병 간 발생하고 있는 VRTU 과열로 인한 고온경보 발생과 장비정지 발생현상을 해결하기 위하여 해군 군수사령부 함정기술연구소와 공동연구를 수행하였다. 열전소자 냉각장치 설치에 따른 냉각효과를 확인하고, 전산 열 유동해석을 수행하여 VRTU 내부 열 유동특성을 분석하였다. 또 해석을 통해 기관실(디젤엔진룸) 내부의 온도분포를 살펴보고 VRTU 과열방지를 위한 최적의 설치위치를 알아보았다. 분석결과, 냉각장치를 설치함에 따라 VRTU 내부 평균 체적온도가 약 10 ℃ 감소하는 것을 확인하였으며 냉각장치에 설치된 Fan은 열 순환을 원활하게 하여 냉각효과를 높였다. 기관실 내부는 디젤엔진 상부에서 높은 온도분포를 나타냈고 통풍관 디퓨저 하부에서 가장 낮은 온도분포를 보였다. 열전소자 냉각장치는 높은 냉각성능을 나타내었으며, VRTU는 과열방지를 위하여 기관실의 통풍관 디퓨저 하부에 설치하는 것이 적절할 것으로 판단된다.

• 토지주택연구
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• 제3권1호
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• pp.89-96
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• 2012

본 연구는 공동주택에서 하이브리드 환기시스템의 적용성을 검토하고, 하이브리드 환기시스템의 성능을 향상하기 위해 CFD시뮬레이션을 이용하여 설계방안을 제시하고자 하였다. 연구대상으로는 전용 $51m^2$, $84m^2$의 공동주택을 선정하였으며, 하이브리드 환기시스템은 창틀자연급기와 각실을 덕트로 연결하여 배기하는 시스템(Hybrid 1)과 창틀자연급기와 욕실 거실배기가 혼합된 시스템(Hybrid 2)을 적용하였다. 이때 각 시스템별 배기구의 위치를 변수로 하여 CFD를 수행하였다. $51m^2$, $84m^2$ 모두 Hybrid 2가 Hybrid 1보다 환기효율이 우수한 것으로 나타났으며, 평균공기연령 또한 낮은 것으로 나타났다. Hybrid 1의 경우, 덕트 배기구의 위치가 각 실 입구에 설치하는 것보다 실 안쪽 모서리에 설치하여 기류이동을 많이 유발할 수 있는 유형이 효과적인 것으로 나타났다. Hybrid 2의 경우, 욕실 고정압팬에 덕트를 연결하여 거실중심에 배기구를 설치하는 시스템이 환기효율이 가장 우수한 것으로 나타났다. 그러나 $51m^2$의 경우 Hybrid 2가 Hybrid 1보다 20%의 향상된 환기효율을 나타낸 반면, $84m^2$의 경우는 14%의 향상된 환기효율을 나타내 공동주택 규모에 따른 적정한 하이브리드 환기시스템에 대한 검토가 필요하다.

• 한국항공운항학회지
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• 제26권2호
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• pp.83-90
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• 2018

This paper describes a case study on the design factor analysis of vertical wind tunnel for skydiver's training or experiencing of paradropping exercise in the air. The case study of vertical wind tunnel design is to provide the knowledges on effects of parameter's variation when it is applied to overall or partial duct of tunnel circuit. The analysis of design parameters based on pressure loss are produced one by one through the tunnel components from the flight chamber because the wind tunnel must satisfy the requirement of flight chamber such as flow speed, quality and quantity. Results shows the various effects of parameter variation with pressure loss in the wind tunnel circuit. Pressure loss should be based on the determination of fan and power system which can be selected from market or new design.

• KIEAE Journal
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• 제4권3호
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• pp.87-94
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• 2004

The purpose of this study is to improve thermal environment of telecommunication equipment rooms that hold TDX-10, TDX-100, 5ESS-2000, PCM of the latest telecommunication equipment. Analysis program is used the commercial CFD code, Star-CD and DOE-2.1E. The result has been compared by the energy consumption and the temperature contour at the 1 m height of room for each case. Different methods such as the relocation of the existing air-conditioner, the inflow of the ambient air into room, the installation of the forced fan and the cooling system equipment of the duct-connection type have been used to test for improvement of thermal environment. The analysis shows that most efficient method is the inflow of the ambient air into room but auxiliary equipment should be needed to prevent the local thermal spot.

• 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.

• 한국축산시설환경학회지
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• 제20권1호
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• pp.9-14
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• 2014

This survey was conducted to give the basic information for ventilation systems of weaned pig house to establish the acceptable ventilation system in Korea. A total of 11 farms were surveyed in this study and 1 more farm in each province was regionally selected. The general information, inlet and outlet ventilation system, alley in house, space allowance of weaned pigs and manure management were surveyed. Space allowance of weaned pig in 82% of surveyed farms met the legal standard. Side wall inlet and outlet ventilation system were 82% and 73% of surveyed farms, respectively. Moreover, 73% farms have alley in the pig house to control temperature of inlet air. In this survey, both planar slot and circular duct inlet system and side wall fan outlet system could be a favorable ventilation system in weaned pig house.

• 설비공학논문집
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• 제22권3호
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• pp.171-179
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• 2010

Thermal performance of louver fin and plate fin in a thermoelectric cooling system with a duct-flow type fan arrangement is analytically evaluated. The thermoelectric cooling system consists of a thermoelectric module and two heat exchanger fins. The analytic results show that the optimized louver fin has lower thermal resistance than plate fin. The COP and heat absorbed rate of the thermoelectric cooling system with optimized louver fins are 10.3% and 5.8% higher than optimized plate fins, respectively.

• Advances in aircraft and spacecraft science
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• 제1권3호
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• pp.353-378
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• 2014

This paper deals with the early development of the Anuloid, an innovative disk-shaped VTOL aircraft. The Anuloid concept is based on the following three main features: the use of a ducted fan powered by a turboshaft for the lift production to take-off and fly; the Coanda effect that is developed through the circular internal duct and the bottom portion of the aircraft to provide further lift and control capabilities; the adoption of a system of ducted fixed and swiveling radial and circumferential vanes for the anti-torque mechanism and the flight control. The early studies have been focused on the CFD analysis of the Coanda effect and of the control vanes; the flyability analysis of the aircraft in terms of static performances and static and dynamic stability; the preliminary structural design of the aircraft. The results show that the Coanda effect is stable in most of the flight phases, vertical flight has satisfactory flyability qualities, whereas horizontal flight shows dynamic instability, requiring the development of an automatic control system.