• 한국가구학회지
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• 제12권2호
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• pp.29-38
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• 2001

This study was carried out to develope a new process of flattening bamboo pieces(3 months old) by two steps of utilizing microwave oven and hot press. Internode bamboo pieces were impregnated with low molecular weight phenol formaldehyde resin (PF) under vacuum of 76 cmHg, heated in a household microwave oven in 1 minute, pressed on the temperature of $145^{\circ}C$ by the hot press for 10 minute, and then cooled by the cold press in their flattened form. The physical and mechanical . Properties of compressed flattened bamboo were as follows: 1) PF1(Mw:427) and PF2(Mw:246) sol. met the success of flattening of internode bamboo pieces in both of P. bambusoides and P. nigra var. PF2 showed the more plasticity to flatten the bamboo than PFI. The PF2 sol. with low molecular weight(Mw:246) gave the more weight gain than that of PF1 in the equal concentration. PF1 of 5% (NVC) and PF2 of 10% (NVC) sol. gave the best result for physical and mechanical properties and from a economical view point. 2) The PFI of 5% (NVC) sol. with low molecular weight decreased the water absorption of 62-63% and increased the bending strength (MaR) of 80-90%, compression strength of 43-54%. 3) The PF2 of 10% (NVC) sol. with low molecular weight decreased the water absorption of 56-57% and increased the bending strength (MaR) of 64-86%, compression strength of 39-63%.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.318-325
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• 2000

Dynamic behaviors of saturated-fatty acids $C_{16}$, $C_{18}$, $C_{20}$ and 8A5H with azobenzene were measured by displacement current method when the molecules are stimulated by pressure light and heat. When a barrier was compressed I-A, $\pi$-A isotherms of $C_{16}$, $C_{18}$, and $C_{20}$ were similar to each other but the displacement current of $C_{20}$ which has a long alkyl chain was relatively low. 8A5H showed the form of double liquid films and had a reversible reaction when a barrier was compressed and then expanded. When the molecules of 8A5H were stimulated by 365[nm] light the positive currents which were generated by the structural changes from trans to cis were measured. But the negative currents of the structural changes from cis to trans by 450[nm] light were too weak to detect. When the temperature of the water subphase was increased the surface pressures of the monolayers were increased early because of the thermal activations of the molecules and the double liquid films of 8A5H were disappeared above 40[$^{\circ}C$]EX>].

• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.91-96
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• 2002

This study was carried out to estimate the property of dimensional stability of heat compression of italian poplar wood with low density. Firstly, two levels of pressure conditions were applied using the closed and open-press system. The thermal treatment temperatures were 180℃ and 200℃, respectively. Water absorption tests were conducted in water bath at 25℃ and 100℃ for 35 hours and 1 hour, respectively. The compression rates of wood were 47 percent, 60 percent, and 73 percent, respectively. From these tests, it was found that the dimensional stability of the closed-press system was superior to that of the open-press system. Furthermore, the dimensional stability of compressed wood in the closed-press system was better at 200℃ than 180℃. In compression rate, dimensional stability of 73 percent compression rate was the best result. Considering these results, the best conditions for the dimensional stability of compressed wood were those of the closed-compressing system at high temperatures above 200℃ and larger compression rate. Therefore, it was concluded that the dimensional stability of wood is improved at higher temperature and larger deformation.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.203-206
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• 2005

The objective of study on composite cylinder for alternative fuel vehicle is to develop safe, efficient, and commercially viable, on-board fuel storage system for the fuel cell vehicle or natural gas vehicle that use highly compressed gaseous fuel such as hydrogen or natural gas. This study presents the whole procedure of development and certification of a type 3 composite cylinder of 207bar service pressure and 70 liter water capacity, which includes design/analysis, processing of filament winding, and validation through various testing and evaluation. Design methods of liner configuration and winding patterns are presented. Three dimensional, nonlinear finite element analysis techniques are used to predict burst pressure and failure mode. Design and analysis techniques are verified through burst and cycling tests. The full qualification test methods and results for validation and certification are presented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.655-660
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• 2000

Animation technique from the PIV database is particularly emphasized to give macroscopic and quantitative description of complex flow fields. This paper shows animation construction and application example for the post-processing of PIV data. As examples, first case is a pitching airfoil immersed in tree surface water circulating tunnel. Second case is a wake of a model-ship. Third case of PIV data is a large scale surface flow field. Obtained images are processed in time sequence by PIV exclusive routines where an efficient and reliable cross correlation algorithm is included for vector identification. All. animation Jobs are implemented completely on single personal computer environment. Compressed digital images are obtained initially by Motion-JPEG board and various An files are finally obtained through graphic processes.

• Membrane and Water Treatment
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• 제8권5호
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• pp.499-515
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• 2017

The purpose of this study was to investigate membrane fouling caused by microalgal cells in submerged membrane systems consisting of polymeric and ceramic microfiltration membranes. In this study, one polymeric (flat-sheet, pore size: $0.2{\mu}m$) and two ceramic (flat-sheet, pore size: $0.2{\mu}m$ and cylindrical, pore size: $1{\mu}m$) membranes were used. Physical cleaning was performed with water and air to determine the potential for reversible and irreversible membrane fouling. The study results showed that substantial irreversible membrane fouling (after four filtration cycles, irreversible fouling degree 27% (cleaning with water) and 38% (cleaning with air)) occurs in the polymeric membrane. In cleaning studies performed using water and air on ceramic membranes, it was observed that compressed air was more effective (recovery rate: 87-91%) for membrane cleaning. The harvesting performance of the membranes was examined through critical flux experiments. The critical flux values for polymeric membrane with a pore size of $0.20{\mu}m$ and ceramic membranes with a pore size of $0.20{\mu}m$ and $1{\mu}m$ were ${\leq}95L/m^2hour$, ${\leq}70L/m^2hour$ and ${\leq}55L/m^2hour$, respectively. It was determined that critical flux varies depending on the membrane material and the pore size. To obtain more information on membrane fouling caused by microalgal cells, the characterization of the fouled polymeric membrane was performed. This study concluded that ceramic membranes with a pore size of $0.2-1{\mu}m$ in the submerged membrane system could be efficiently used for microalgae harvesting by cleaning the membrane with compressed air at regular intervals.

• 멤브레인
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• 제31권6호
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• pp.443-455
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• 2021

본 연구에서는 낮은 막 저항을 가지는 알칼리 수전해 시스템 적용을 위한 격리막 제조를 위하여 PPS (Polyphenylene sulfide)를 지지체로 사용하고 Polysulfone과 무기물 첨가제를 이용하여 격리막을 제조한 뒤, 지지체의 두께와 다공도에 대한 영향을 분석하였다. 지지체로 사용된 PPS 펠트를 온도(100℃, 150℃, 200℃)와 압력(1톤, 2톤, 3톤, 5톤)의 변수를 두어 압축을 진행하여 두께를 조절하고자 하였으며, 무기입자로서 친수성이 높고 내알칼리성이 뛰어난 BaTiO₃와 ZrO₂를 사용하여 polysulfone과 함께 슬러리를 제조하고 압축한 PPS 펠트 위에 캐스팅하여 다공성 격리막을 제조할 수 있었다. 전자주사현미경(SEM)을 통해 압축 조건에 따른 분리막의 모폴로지 변화를 확인하고, 기공도를 계산하였으며, 압축 조건이 증가할수록 두께와 기공도가 감소하는 경향을 확인하였다. 수전해용 격리막으로서 사용이 가능한지를 확인하기 위하여 다양한 특성 평가를 진행하였다. 기계적강도를 측정한 결과 압축 조건(온도와 압력)이 증가할수록 인장강도가 점차 증가하는 경향을 확인하였다. 최종적으로 내알칼리성 테스트를 통하여 제조한 다공성 격리막이 우수한 내알칼리성을 가지는 것을 확인하였고, I-V 테스트를 통하여 100℃와 150℃ 조건에서 압축된 막들이 기존의 압축하지 않은 막보다 낮은 전압을 가지며 성능이 향상되었다는 것을 확인하였다.

• 한국분무공학회지
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• 제9권3호
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• pp.15-21
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• 2004

The removal of the dusts in the subway stations, tunnels, factories and buildings becomes issue for comfortable indoor and outdoor conditions. There has been used an automatic self-cleaning filter system to collect the dusts. In general, the collected particles are removed by water spray nozzles. The new design for improving the cleaning efficiency of collected dusts and reducing the supplied water is the concept of the plane array of demister filters and the twin-fluid nozzle for mixing compressed air and water in the automatic self-cleaning filter system. Results show that the cleaning efficiency of twin-nozzle filter systems is 99.1%, compared to 47% in the conventional filter system. Therefore the automatic self-cleaning filter system using twin-fluid nozzle filter systems reduces water supplied in the filter system, and increases cleaning efficiency and drying efficiency.

• 한국터널지하공간학회 논문집
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• 제18권5호
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• pp.413-418
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• 2016

최근 한중, 한일 해저터널과 같은 대규모 프로젝트가 구체화되고 있으며, 해저터널에 대한 관심이 높아지고 있다. 해저터널은 일반 지상터널에 비해 열차화재에 따른 대규모 피해가 발생할 수 있으며, 기존의 일반터널 방재설계 이외에도 효율적인 소화방안에 관한 연구가 필요하다. 이에 따라, 본 연구에서는 열차화재를 구난역에서 신속하게 진압하기 위하여, 일반적인 포 소화설비를 개량한 '압축공기포(CAF) 소화설비'를 활용한 실물 화재실험을 7차례 수행하였다. 실험은 가상의 터널에 구난역을 설치하고 KTX 열차의 1 량 규모의 가상열차를 대상으로 실시하였다. 압축공기포를 화원에 직접 분사한 경우에 햅탄(Heptane) 원료 30 L의 가연물을 1분 이내에 소화시켰다. 본 실험 연구를 통하여 해저터널 구난역 열차화재 소화설비에 압축공기 포 소화설비가 적합한지 확인하였으며, 해저터널 외에 일반터널에서도 CAF가 갖는 장점을 활용하여 빠르고 손쉬운 소화가 가능하도록 노즐 각도 및 설치위치 등을 변경하여 소화수와 소화약제를 최소화하기 위하여 추가로 실험 연구를 진행해야 한다고 판단된다.

• Journal of Korean Society for Atmospheric Environment
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• 제23권E1호
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• pp.10-15
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• 2007

The gas hydrates are probably most sensitive to climate change since they are stable only under specific conditions of high pressure and low temperature. One of the main factors responsible for formation of gas hydrates is the saturation of the gases with water vapor. Quantitative phase equilibrium data and understanding of the roles of water component in the phase behavior of the heterogeneous water-hydrocarbon-hydrate mixture are of importance and of engineering value. In this study, the water content of ethylene gas in equilibrium with hydrate and water phases were analyzed by theoretical and experimental methods at temperatures between 274.15 up to 291.75 K and pressures between 593.99 to 8,443.18 kPa. The experimental and theoretical enhancement factors (EF) for the water content of ethylene gas and the fugacity coefficients of water and ethylene in gas phase were determined and compared with each other over the entire range of pressure carried out in this experiment. In order to get the theoretical enhancement factors, the modified Redlich-Kwong equation of state was used. The Peng-Robinson equations and modified Redlich-Kwong equations of state were used to get the fugacity coefficients for ethylene and water in the gas phase. The results predicted by both equations agree very well with the experimental values for the fugacity coefficients of the compressed ethylene gas containing small amount of water, whereas, those of water vapor do not in the ethylene rich gas at high temperature for hydrate formation locus.