• 제목/요약/키워드: Double layer duct

검색결과 6건 처리시간 0.01초

이중덕트를 이용한 U자형 감요수조의 주기조절 실험 연구 (Experimental Study on the Period Control of an U-tube Type Anti-Rolling Tank by using a Double Layer Duct)

  • 주영광;김용직;하영록
    • 대한조선학회논문집
    • /
    • 제52권2호
    • /
    • pp.135-142
    • /
    • 2015
  • The Anti-Rolling Tank(ART) has an advantage over the other roll stabilizing devices, when ship is staying and working at one site of sea. An important design point of ART is the tank tuning, that is, matching the tank natural period to the ship's roll natural period. Since the load condition and consequently the roll natural period of ship is to be changed widely, the natural period of ART also has to be changed widely. In case of the existing U-tube type ART with a single layer duct, the tank natural period can be changed in a relatively narrow range. This paper suggests a new U-tube type ART system using a double layer duct to enable wide change of ART natural period. Through the roll experiments performed in regular beam waves for a box-type model ship, it is shown that the double layer duct ART has about two times wider period range and a better reducing effect of roll magnitude than the single layer duct ART.

Double pancake 코일 내부의 절연구성 연구 (Dielectric composition of the double pancake coil interior)

  • 정종만;백승명;곽동순;이정원;김상현
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
    • /
    • pp.210-213
    • /
    • 2002
  • For insulation design of the superconducting transformer, many types of insulation tests should be carried out. To clarify the components of insulation for superconducting transformer, there are main four parts as 1ike that turn-to-turn interior of each primary and secondary windings, layer-to-layer between primary and secondary windings, and winding to grounded structures. The insulation components should meet the required withstand voltage of the system and enough safety factors must included. As the fundamental insulation characteristics, we tested surface flashover voltage of spacer that would place between the coils and would take the role of both cooling duct and insulator. The structure of spacer in practice vary depending on coil type, in this work we considered double pancake coil for the superconducting transformer. In this study we tested flashover voltages of several arrangement of spacer.

  • PDF

스크램제트 엔진 흡입구의 기본설계 연구 (Preliminary Design Study of the Scramjet Engine Intake)

  • 강상훈;이양지;양수석
    • 한국추진공학회지
    • /
    • 제9권3호
    • /
    • pp.38-48
    • /
    • 2005
  • 극초음속 비행체의 엔진으로 주목받고 있는 스크램제트 엔진의 핵심기술 개발을 위해 엔진흡입구의 설계방법에 대해서 연구하고 두 가지 형태의 흡입구를 설계하였다. 기본 외형은 충격파 관계식을 비롯한 비점성 관계식 및 기하학적 관계식을 통하여 설정하였고 점성효과를 고려한 배출덕트를 설치하였다. 설계된 흡입구는 전산해석을 통해 설계의 적합성 및 성능을 검증하였다. 전산해석 결과, 이중쐐기형 흡입구는 단일쐐기형 흡입구보다 전압력회복율과 유량손실측면에서 우수한 성능을 보였다.

PIV 기법을 이용한 모형철도터널 직관덕트에서 유동 분포 계측 및 수치해석 결과와의 비교분석 (MEASUREMENT OF FLOW DISTRIBUTION IN A STRAIGHT DUCT OF RAILWAY TUNNEL MOCK-UP USING PIV AND COMPARISON WITH NUMERICAL SIMULATION)

  • 장용준;정우성;박일순
    • 한국전산유체공학회지
    • /
    • 제15권3호
    • /
    • pp.39-45
    • /
    • 2010
  • The turbulent flows in a tunnel mock-up($10L{\times}0.5W{\times}0.25H$ m3 : scale reduction 1/20) with rectangular cross section were investigated. The instantaneous velocity fields of Re = 49,029, 89,571 were measured by the 2-D PIV system which is consisted of double pulsed Nd:Yag laser and the tracer particles in the straight-duct mock-up where the flows were fully developed. The mean velocity profiles were taken from the ensemble averages of 1,000 instantaneous velocity fields. Simultaneously, numerical simulations(RANS) were performed to compare with experimental data using STREAM code. Non-linear eddy viscosity model (NLEVM : Abe-Jang-Leschziner Eddy Viscosity Model) was employed to resolve the turbulent flows in the duct. The calculated mean velocity profiles were well compared with PIV results. In the log-law profiles, the experimental data were in good agreement with numerical simulations all the way to the wake region except the viscous sub-layer (near wall region).

자연산 조피볼락, Sebastes schlegeli의 소화관에 기생하는 Hysterothylacium sp.와 Anisakis simplex (Nematoda: Anisakidae)의 형태학적 비교 및 숙주의 조직병리학적 반응 (Morphological Comparison Hysterothylacium sp. and Anisakis simplex (Nematoda: Anisakidae) from Wild Black Rockfish, Sebastes schlegeli, and Histopathological Host Reaction)

  • 박정준;박명애;최혜승;김석렬
    • Applied Microscopy
    • /
    • 제41권3호
    • /
    • pp.205-213
    • /
    • 2011
  • 조피볼락, Sebastes schlegeli 소화관 주변에는 다수의 아니사키 스가 기생하고 있었으며, 몇몇 개체들은 간의 표면에 존재하고 있었다. 유전학적 결과 조피볼락에 기생한 아니사키스는 3종으로 분석되었으며, Hysterothylacium sp.가 가장 많이 분포하고 있었다. Hysterothylacium sp.는 Anisakis simplex보다 짧고 가늘었다. 두 종 모두 전방부분에는 lip, 입, 신경환, 분비공, 분비관이 관찰되었다. 두 종 모두 중간부분에는 식도, 위, 장이 존재하고 있었 지만, intestinal ceacum과 ventricular appendage는 Hysterothylacium sp.에서만 관찰되었다. Hysterothylacium sp.의 후방부분 끝에는 conical nodulose apex이 관찰되었지만, A. simplex의 후방부분 끝에는 spine이 관찰되었다. SEM으로 관찰한 결과 Hysterothylacium sp.의 입 주위에는 3개의 lip이 존재하고 있었는데, dorsal lip은 넓이 65 ${\mu}m$ 내외였고, 한쌍의 lateroventral lip은 넓이 60 ${\mu}m$ 내 외였다. Lip의 표면에는 넓이 8 ${\mu}m$ 내외의 유두돌기 한쌍이 존재하고 있었다. Hysterothylacium sp.와 A. simplex의 충체 넓이는 각각 480 ${\mu}m$와 900 ${\mu}m$ 내외로 측정되었다. Hysterothylacium sp. 의 lateral alae는 높이 7 ${\mu}m$ 내외였으며, cornical nodulose apex에 존재하는 돌기는 지름 약 3.3 ${\mu}m$였다. A. simplex의 후방부분 끝 에는 높이 약 20 ${\mu}m$의 spine이 관찰되었다. 조피볼락 장의 내강 에 존재하는 아니사키스들은 대부분 Hysterothylacium sp.였고, 점막주름 근처 혹은 점막하층에 기생하고 있었다. 아니사키스의 기생으로 인하여 숙주의 점막상피에는 다수의 점액세포가 증가하였다.

설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
    • /
    • 제26권12호
    • /
    • pp.605-619
    • /
    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.