• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.322-325
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• 1999

We fabricated 18cm YBCO coated conductor comprising a YBCO superconducting film and CeO$_2$/YSZ/CeO$_2$ buffer films deposited on a biaxially textured Ni tape. For those film fabrications, we developed a new method, the cylindrical holder in a double chamber. This is alternative to the reel-to-reef method which is commonly tried to fabricate a long YBCO coated tape. We will discuss about the superconducting properties of the 18cm long YBCO coated tapes.

• Journal of Biosystems Engineering
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• 제31권5호
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• pp.395-402
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• 2006

Mixed heat transfer in an indirected NIR (Near Infrared Ray) dry chamber was investigated numerical analysis. It is Important that the miked heat transfer effects on double parameters which the Reynolds number and the position of emit lamp. Reynolds number are based on the outer diameter of the cylinder range from 103 to $30{\times}105$. Four difference heat transfer regimes of behavior are apparent: forced convection and radiation on the outer surface of the cylinder, pure conduction, pure natural convection and radiation between lamp surface and inner surface of the cylinder. The temperature and flow patterns are illustrated by iso-contour lines for the double parameters. Also presented are results on the convective heat transfer flux and the radiative heat transfer flux as increased with Reynolds number.

• Journal of the Optical Society of Korea
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• 제10권4호
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• pp.157-161
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• 2006

A synchrotron light source is useful in the vacuum ultraviolet (VUV) regime for olecular spectroscopy, such as photo absorption, photoionization, and dissociative hotoionization. In this research, we used a double-ion chamber (DIC) to measure hotoabsorption cross sections of a NO molecule in the wavelength range from 90 to 135 nm of 3B1 beam-line of the Pohang synchrotron light source with the resolution of the onochromator being 0.06 nm. The appearance wavelength for ionization was measured to be $134.19{\pm}0.09nm$ that is placed in the middle of the reported values though they don't agree with each other within the relative error limits. The auxiliary experimental works ave been done to test if there are any systematic error sources. The resultant ross-sections agree with previous results in general.

• 한국농공학회논문집
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• 제55권6호
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• pp.121-125
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• 2013

This study was carried out to provide a valuable reference which could reduce heating loss of air-inflated double PO film. Therefore, this study was aimed to choose the best air space thickness and injected air temperature. The characteristics of heat transmission variation at experimental materials were measured and analysed in the laboratory. The experiment was conducted of two layers of PO film, each 0.15 mm tick, sandwiching 110, 175, 225 mm of inflated air with 1 m sides. Environmental control lab was constantly controlled with $-10^{\circ}C$ and experiment chamber was constantly changed with 0, 5, 10, $15^{\circ}C$. The analysis of heat transfer showed that heat transmission does not have a direct correlation with Air Space thickness and injected air temperature. But when inside and outside temperature difference of chamber was great, supply of outside air to Air Space had an advantage at reduction of heating load. It was required to examine accurate analysis at a real greenhouse.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.149-152
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• 2008

30톤급 액체로켓엔진 실물형 연소기의 형상에 따른 연소특성속도에 대한 연구를 수행하였다. 본 연구에서 연소기의 형상은 연소기 헤드와 분리가 가능한 내열재 및 채널 냉각형 연소실(${\varepsilon}$=3.2), 그리고 일체형인 팽창비가 각각 3.5와 12인 재생냉각형 연소기이다. 연소압력은 약 53${\sim}$60 bar 그리고 추진제 유량은 약 89 kg/s이고, 적용된 분사기는 리세스수가 1.0인 동축 와류형이다. 설계점 연소시험에서 팽창비가 12인 일체형 재생냉각 방식의 연소기가 가장 큰 연소특성속도를 보였는데 이는 추진제인 케로신이 분무되기 전 챔버 냉각으로 인한 온도 상승에 따른 엔탈피의 증가 및 연소압력의 증가에 기인한 것이다.

• KIEAE Journal
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• 제7권5호
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• pp.53-58
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• 2007

In order to predict the indoor air pollutant, the VOCs emission rate is used through small chamber in the design process. However, the small chamber method has limitations as the convective mass transfer coefficient, the most important factor when predicting VOCs contamination of indoor air, is different between the small chamber result and the measured data in the actual building. Furthermore, the existing studies which analyzed mass transfer coefficient in the small chamber were directed on the small chambers developed at the time and FLEC(Field and Laboratory Emission Cell), thus, are different from the current small chamber which has been changed with improvements. The purpose of this study is to determine the emission rate of pollutant in multi-layered building materials, and predict the indoor pollutant concentration through the CFD(Computational of Fluid Dynamics) and CRIAQ2 based on the mass transfer coefficient on singled-layered building material by using the current small chamber widely used in Korea. Futhermore, this study used the new convective mass transfer coefficient(hm') which indicates the existing convective mass transfer coefficient(hm) including VOC partition coefficient(k). Also, formaldehyde was selected as target pollutant.

• 한국태양에너지학회 논문집
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• 제27권2호
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• pp.111-119
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• 2007

The annual mean temperature of South Korea has risen by $1.3^{\circ}C$ for last 100 years by urbanization and industrialization. Especially, the frequency of unusual hot weather in summer increases for a long time and the frequency of unusual cold weather in winter clearly decreases. In recently, The considerable portion of curtain wall system is appled to building skin in domestic. As related to this, the Korea Institute of Construction Technology devised the box typed double skin facade(It is occasionally called as FDFS : Functional Double Facade System) as an alternative that reflects the distinctive local climate and saves cooling energy. Two mock-ups($49m^*4.9m$) applied to single skin(curtain wall) and double skin each were monitored under the outdoor condition. Therefore, the characteristics of natural ventilation and cooling energy consumption of each window had been analyzed in real time. The results of this study are summarized as follow, Analysis of the experiment on an air conditioner: the indoor temperature of the chamber with FDFS is lower than that of the chamber with single skin facades by $3{\sim}6$ degrees(C). A temperature variation of about $1{\sim}2$ degrees between the 0.2m and 1.7m height of the mock-up occurs in FDFS, while that of about maximum 7 degrees occurs in single skin facade at noon with abundant intensity of solar accident. Also, 67 percent of energy consumption for air conditioning has been saved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.198-203
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• 2001

This paper discusses an experimental method for measuring the insertion loss (IL) performance of a double panel that are used in vehicles. Instead of two adjacent reverberation chambers which are generally used to measure the transmission loss (TL) of the large sound isolation materials, air-borne sound insulation tester was utilized to determine the IL and articulation index (AI) of standardized deadening materials. In comparison to reverberation chamber method, air-borne sound insulation tester method is more space-saving, more time-saving and more simple to the automotive acoustics. From the empirical results, it is verified that the performance of deadening materials is closely connected with thickness of panels, type of filling material that is filled into a double panel, and area ratio of double panel.

• 한국정밀공학회지
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• 제21권2호
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• pp.195-202
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• 2004

This paper presents the fabrication and evaluation of mechanical behavior for a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, the middle plate, the upper plate and the tube that connects inlet and outlet of the pump. The lower plate includes the channel and the chamber, and the plain middle plate are made of glass and actuated by the piezoelectric translator. Channels and a chamber on the lower plate are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The upper plate does the roll of a pump cover and has inlet/outlet/electric holes. Three plates are laminated by the aligner and bonded by the anodic bonding process. Flow simulation is performed using error-reduced finite volume method (FVM). As results of the flow simulation and experiments, the single chamber pump has severe flow problems, such as a backflow and large fluctuation of a flow rate. It is proved that the double-chamber micropump proposed in this paper can reduce the drawback of the single-chamber one.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.131-136
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• 2003

Experimental study on combustion characteristics of double swirl coaxial injectors has been conducted for the assessment of critical design parameters of injectors. A subscale thrust chamber has been fabricated with a water-cooled copper nozzle, which allows a chamber to be reused without replacing parts. Two different designs of injectors have been tested for the understanding of the effects of recess length on combustion. Clearly, the recess length drastically affects the combustion efficiency and hydraulic characteristics of the injector. Internal mixing of propellants in the injector with the recess number of two increases a combustion efficiency and reveals sound combustion although a pressure drop required for the similar amount of mass flow rates increases compared with the injector of the recess number of one.