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H<sub>2</sub>O/LiBr+HO(CH<sub>2</sub>)<sub>3</sub>OH계 공냉형 이중효용 흡수식 냉방시스템의 사이클 해석
권오경,문춘근,윤정인,Kwon, Oh-Kyung,Moon, Choon-Geun,Yoon, Jung-In 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.2
A cycle analysis was achieved to predict the characteristics by comprehensive modeling and simulation of an air-cooled, double-effect absorption system using a new $H_2O/LiBr+HO(CH_2)_3OH$ solution. The simulation results showed that the new working fluid may provide the crystallization limit 8% higher than the conventional $H_2O/LiBr$ solution. With a crystallization margin of 3wt%(weight%), the optimal solution distribution ratio was found in the range of 36 to 40%. Variation of cooling air Inlet temperature has a sensitive effect on the cooling COP and corrosion problem. The simulation of heat exchangers with UA value revealed that the absorber and the evaporator are relatively important for an air-cooled system compared with the condenser and the low temperature generator. The effect of cooling air flow rate, circulation weak solution flow rate and chilled water inlet temperature were also examined. The new working fluid may provide the COP approximately 5% higher than the conventional $H_2O/LiBr$ solution.
권오경,이참미,성우경,Kwon, Oh-Kyung,Yi, Chang-Mi,Sung, Woo-Kyung 한국의류산업학회 1999 한국의류산업학회지 Vol.1 No.2
The thermal properies of the pure linen fabrics available in the market and linen blended woven fabrics were measured at the moisture content of 0%, 20%, 40% and 60% using KES-F7 system (Thermo Iabo II type). The experimental properties were statistically analyzed by the rate of water absorbent. The main results were as follows; There is a positive correlation between the thermal insulation value (TIV) and thickness of pure linen fabrics and linen blended woven fabrics by water absorption. Whereas an negative correlation exists between the TIV and cover factor. There is a high positive correlation among the thermal conductivity (k), thickness and weight of pure linen fabrics and linen blended woven fabrics by water absorption. Wherase a high negative correlation exist between the k and air' permeability (Ap). There is a high positive correlation between the feeling of warmth/coldness and bulk density of pure linen and linen blended woven fabrics by water absorption. Wherase a high negative correlation exists between the feeling of warmth/coldness and porosity. There is a negative correlation between TIV and $q_{max}$ of pure linen fabrics and linen blended woven fabrics. The higher the rate of water absorbent, the lower the TIV. This means that TIV decreases by water absorption. As for the thermal property by rate of water absorbent $q_{max}$ and k increase by water absorption and reach max-value at 60% rate of water absorbent. The TIV decreases by water absorption and has +value at 0% rate of water absorbent, whereas it has -value with a feeling of coldness at 20%, 40%. and 60% rate of water absorbent.
Properties of Zn O Varistor Fabricated by Seed Grain Method
권오경,마재평,백수현,Kwon, Oh Kyung,Mah, Jae Pyung,Paek, Su Hyon The Institute of Electronics and Information Engin 1987 전자공학회논문지 Vol.24 No.3
We investgated I-V cahracteristics and relationship between microstructures and electrical properties in the specimens fabricated by seed grain method for low voltage Zn O varistor. Breaksown voltage was mainly dependent on seed grain size, and could be cntrolled to 10V/mm -15V/mm by sintering temperature and time. In non-seed grain method breakdown voltage generally agreed with final grain size, but did not always agree with it by the change of barrier phase distribution in case of the method using seed grains.
권오경,이창미,김묘향,박희웅,Kwon, Oh-Kyung,Yi, Chang-Mi,Kim, Myo-Hyang,Park, Hee-Ung 한국의류산업학회 1999 한국의류산업학회지 Vol.1 No.3
This study was conducted to examine the fatigue phenomenon of mechanical properties in tencel fabrics by repeated washing & shear and tensile deformation. The obtained results are as follows. After performing repeated shear tensile deformation, RT of tencel showed higher increase rate than that of cotton and rayon, whereas its WT and EM was a smaller decrease rate than that of them. This means that tencel's resistance to tensile deformation was the greatest. In the repeated washing and shear tensile deformation, tencel's 2HB, 2HG and 2HG5 showed a remarkable increase rate. In terms of deformation frequency, the greatest change rate appeared at the time of 1000 cycles of repeated shear tensile deformation and 15 times of repeated washing. In the hand value and THV, KOSHI showed a higher increase rate for tencel than for cotton and rayon in both repeated washing and shear tensile deformation, and NUMERI showed a higher increase rate. In the THV the change rate of rayon and cotton could be rarely seen but for tencel, it decreased. tencel's change rate of thermal insulation value by materials was 1.08%, and it increased as the washing frequency increased, compared to the grey fabrics, whereas the change rates of cotton and rayon were 0.74% and 0.22%, respectively. The qmax decreased in the order of cotton>tencel>rayon as the washing frequency increased.
권오경,임수길,성기석,최병렬 ( Oh Kyung Kwon,Soo,Kil Lim,Ki Suk Seong,Byung Ryul Choi ) 한국환경농학회 1997 한국환경농학회지 Vol.16 No.4
For the selection of plants contained pesticidal active conpounds, 31 families 59 species of native plants were collected and biological activites of their crude extracts against brown planthopper (Nilaparvata lugens), Xanthomonas oryzae pv. oryzae and allelopathy were examined. Among the screened plants, the crude extracts from the leaves of Ricinus communis and Sophora angustifolia showed 100% and 82% of mortality on brown planthopper at the concentration of 1% (w/v) respectively. Mixed crude extracts of Sophora angustifolia root and Meha azedarach seed exhibited 128∼155% of synergistic effects on the mortality of brown planthopper. In case of fungicidal activity, the crude extracts from the leaves of 8 plants including Chrysanthemum indicum were inhibitory of the growth of Xanthomonas oryzae pv. oryzae at 1%(w/v) soluction. Seed germination of radish (Raphanus sativas) and barnyardgrass (Echinochloa crus-galli) was inhibited by 0.5%(w/v) leaf extracts of Pinus densiflora and Quercus acutissima. MeOH extracts of Pinus denislora leaves gave 100% inhibition in seed germintion of radish at 2%(w/v) soluction and showed a complete inhibition in seedling growth of barnyardgrass as well as radish at 5% solution.
권오경,윤정인,윤재호,Kwon, Oh-Kyung,Yoon, Jung-In,Yun, Jae-Ho 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.5
This study was concerned with the enhancement of mass transfer by surfactant added to the aqueous solution of LiBr. Different vertical inner tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare tube, groove tube, corrugate tube and inserted spring tubes. The additive concentration of normal octyl alcohol as a surfactant is about 0.08mass%. The Sherwood number was measured as a function of film Reynolds number 20~200. The experimental results were compared with those which use no surfactant. The enhancement of mass transfer by Marangoni convection effect which was generated by addition of the surfactant is proved for each testing tube Especially, it is clarified that the tube with the spring has the highest enhancement effect. A correlation of the experimental mass transfer data for the bare, groove, corrugate and insert spring tubes results expressed as the form of Sh=cㆍ Re$_{f}$ $^{n}$ .
지그재그채널 PCHE의 각도에 따른 열전달 및 압력강하특성
권오경(Oh-Kyung Kwon),최미진(Mi-Jin Choi),최영종(Young-Jong Choi) 대한설비공학회 2009 설비공학 논문집 Vol.21 No.9
The objectives of this paper are to study the characteristics of heat transfer and pressure drop of the zigzag channel PCHE using diffusion bonding technology by numerical analysis. PCHE of five types are designed, which are zigzag channel angle 180°, 160°, 140°, 120° and 100°. The zigzag PCHE was numerically investigated for Reynolds number in a range of 150~800. The temperatures of the hot side were performed at 80℃ while that of the cold side was conducted at 20℃. The results show that the performance of heat transfer rate for zigzag channel 100° increases about 11.5% compared to that of zigzag channel 180°. On the other hand, the performance of pressure drop for zigzag channel 100° is remarkably higher than that of zigzag channel 180°, about 2.4 times.