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마이크로 Pin Fin 화학반응기에서 수소화붕소나트륨 수용액의 압력강하 및 탈수소 화학반응 연구
정기문(Ki Moon Jung),최석현(Seok Hyun Choi),이희준(Hee Joon Lee) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.6
수소화붕소나트륨은 안정적으로 수소가 저장된 물질이며, 촉매반응으로 수소를 용이하게 분리할 수 있다. 본 연구에서는 탈수소 반응률을 높이기 위해 비표면적이 큰 마이크로 pin fin 화학반응기를 제작하여 수소화붕소나트륨 수용액의 압력강하 및 탈수소 화학반응 실험을 수행하였다. 나노공정을 이용하여 실리콘웨이퍼에 높이 300 μm, 직경 50 μm의 pin fin을 축간격 1.3, 횡간격 1.5으로 엇갈림 배열하였다. 수소화붕소나트륨 수용액은 5~20 wt.% 농도로 Re수 1~60으로 공급되었으며, 초고속카메라를 이용하여 탈수소반응 유동양상을 관찰하였다. 실험 결과 마이크로 pin fin 화학반응기는 동일 수력학적직경을 가지는 직관 마이크로채널 화학반응기보다 화학반응 성능이 2.45배 우수한 반면, 압력강하는 1.5배 증가하였다. Dehydrogenation from the hydrolysis of a sodium borohydride (NaBH4) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.%) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a NaBH4 solution over both a single microchannel with a hydraulic diameter of 300 μm and a staggered array of micro pin fins in the microchannel with hydraulic diameter of 50 μm. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.%. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.
Effects of Aerobic Exercise using Virtual Reality Program on Vital Capacity of Male Smokers
Ki-Moon Jung(정기문),Eun-Jin Ryu(류은진),Hyun-Jin Kim(김현진) 한국엔터테인먼트산업학회 2016 한국엔터테인먼트산업학회논문지 Vol.10 No.6
본 연구는 20대의 흡연 남성을 대상으로 가상현실 게임을 이용한 운동 프로그램이 호흡능력에 미치는 영향을 알아보고자 연구하였다. 대상자는 건강한 대학교 재학생을 대상으로 하였으며, 흡연자를 대상으로 무작위로 가상현실 그룹과 트래드밀 그룹으로 나누었다. 두 그룹은 각각 운동프로그램을 4주 동안, 주 3회, 30분 동안 실시하였으며, 측정방법은 피크플로우를 사용하여 대상자들의 최대 호기량을 측정하였다. 결과에서 가상현실 군과 트레드밀 군에서 운동 후에 유의한 차이를 나타내었으며, 군 간 비교에서는 4주 후에 유의한 차이를 나타내었다. 본 연구 결과 가상현실프로그램이 20대 흡연 남성에의 호흡에 유의한 차이를 나타낸 것을 알 수 있었으며, 본 연구를 기초로 하여 호흡기 문제에 대한 연구가 활발히 진행될 것이라고 생각된다. This study made male smokers perform an exercise program using virtual reality game that can be played easily and pleasantly to investigate the effects of the program on their respiratory ability and to present basis of developing programs for intensifying ability to promote the ability of males. The subjects were male smokers in a college who were physically and mentally healthy; they were randomly divided into a group of virtual reality program (n=30) and a group of treadmill (n=30). The two groups of subjects performed an exercise program using virtual reality or using treadmills. Virtual reality and Treadmill programs were carried out 30 minutes, three times per week, for four weeks. This study used a peak flow meter to measure the maximal expiratory volume of normal people. The maximal expiratory volume of the virtual reality and treadmill groups showed significant difference. In between group comparison, significant difference was observed after the four-week intervention. This study was performed to identify effects of virtual reality program on respiration of male smokers, and the results showed that the program induced significant differences in respiration of the male smokers. This study may provide a basis for investigating effects of such program on respiratory function.
삼중효용 흡수식 냉동기용 수직관식 고온재생기의 작동 특성에 관한 실험적 연구
정기문(Ki-Moon Jung),김성민(Seong-Min Kim),김선창(Seon-Chang Kim),전동순(Dong-Soon Jeon) 대한설비공학회 2018 설비공학 논문집 Vol.30 No.6
In this study, the operating characteristics of a vertical tube type high temperature generator for use in a triple effect absorption chiller were experimentally investigated. The test section of a vertical single tube high temperature generator was made of a stainless steel tube featuring a length of 1 m and an outer diameter of 60.5 mm. The working fluid used in this study was LiBr aqueous solution. Electric band heaters were attached to the outer surface of the test section in order to supply uniform heat flux to the test section. The inlet concentration and the temperature of the weak solution were fixed at 56.4% and 179.7℃, respectively. The effects of the heat flux and the mass flow rate of the weak solution on concentration differences, the solution circulating ratio, and the heat transfer coefficient were all investigated. It was found that the concentration difference increased and the solution circulating ratio decreased with increases in the heat flux. Under the same heat flux condition but with a lower mass flow rate of the weak solution, a larger concentration difference was found. It was also found that the averaged heat transfer coefficients for a mass flow rate of 20.1 g/s were lower than those for a mass flow rate of 14.2 g/s at each heat flux.
정기문(Ki-Moon Jung),전동순(Dong-Soon Jeon),김선창(Seon-Chang Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this paper, the design optimization of HTG(high temperature generator) for triple absorption chiller was performed. The fractional factorial DOE was used in screening phase to select the main design factor. Inside tube diameter, inner wall diameter, outer wall diameter and combustion chamber length were selected as a main design factor. The main design factors for HTG were optimized by response surface method.
마이크로 pin fin 화학반응기에서 수소화붕소나트륨 수용액의 압력강하 및 탈수소 화학반응 연구
정기문(Ki Moon Jung),최석현(Seok Hyun Choi),정문선(Moon-Sun Chung),이희준(Hee Joon Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Many types of hydrogen storages have been studied recently paying attention to hydrogen storage and release. Among those, dehydrogenation from the hydrolysis of a sodium borohydride (NaBH₄) solution has been of much interest owing to its high theoretical hydrogen storage capacity (10.8 wt.%) and potentially safe operation. However, most of researchers have focused on chemical characteristics such as NaBH4 hydrolysis, catalysts, and synthesis, but not on the mechanical design of a chemical reactor for hydrogen generation. To design an efficient chemical reactor, size (which should be compact) and pressure drop, reaction rate are of great importance. Therefore, a microchannel is promising for the design of a dehydrogenation reactor owing to its very large reacting surface area per unit volume. Moreover, micro size pin fin structures could be manufactured on the bottom of microchannel surface for even more extended reacting surface area and contact catalytic reaction. An experiment study has been performed on catalytic reaction rate and pressure drop of NaBH4 solution over both a single microchannel with a hydraulic diameter of 300 ㎛ and a staggered array of micro pin fins with hydraulic diameter of 50 ㎛ in the microchannel. Catalytic reaction rates and pressure drops were obtained over Reynolds numbers from 1 to 60 and solution concentration from 5 to 20 wt.%. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times more in pin fin microchannel than in a single microchannel, respectively.
삼중효용 흡수식 냉동기용 수직 단관 고온재생기의 성능 평가
정기문(Ki Moon Jung),김선창(Seon Chang Kim),전동순(Dong Soon Jeon) 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
In this paper, the performance evaluation of a vertical single tube high temperature generator for triple effect absorption chiller was conducted. The band heaters, which supplies a heat flux of 5.6 to 27.8 kW/m2 were used. Experimental results show that the difference of concentraion increased with increasing heat flux. On the contrary, the solution flow ratio decreased withe increasing heat flux. Under the same heat flux condition, we obtained the higher difference of concentraion at a lower mass flow rate of LiBr aqueous solution.
마이크로 Pin Fin 채널에서 비등 열전달 및 유동 가시화
정기문(Ki Moon Jung),이희준(Hee Joon Lee) 한국가시화정보학회 2015 한국가시화정보학회 학술발표대회 논문집 Vol.2015 No.12
Boiling experiments were conducted to study two-phase pressure drop and heat transfer coefficient in a staggered micro pin fin array microchannel of degassed water. From the results, at vapor quality to 0.042, it is shown that the boiling heat transfer coefficient was decreased as the quality increased. And it is found that the heat transfer coefficient is hardly dependent on mass flux. The data also showed that the pressure drop increased with increasing mass flux. Through visualization, we found that The bubbles generated between the fins, started to grow and moved down stream. And we observed that the stationary vapor pocket where bubbles did not flow.
작약감초탕이 미성숙 흰쥐에서 난포성숙 및 Estrogen생성에 미치는 효과
정기경,강석연,김태균,김창옥,문애리,유경자,이송득,류항묵,김승희,Jung, Ki-Kyung,Kang, Seog-Youn,Kim, Tae-Gyun,Kim, Chang-Ok,Moon, A-Ree,Ryu, Kyung-Za,Lee, Song-Deuk,Ryeu, Hang-Mook,Kim, Seung-Hee 한국생약학회 1997 생약학회지 Vol.28 No.3
The traditional herbal medicine, Jackyakgamcho-tang(JGT), was reported to decrease serum testosterone levels and make pregnancy possibel in anovulatory woman and rat. JGT contains Paeoniae Radix(PR) and Glycyrrhizae Radix(GR) in equal amount. This study was designed to investigate the effect of JGT and its components(PR, GR, paeoniflorin and glycyrrhizin) on uterine and ovarian responses, follicular development, and estrogen secretion in the immature rat. The samples(water extracts of JGT, PR, GR; pure compound of paeoniflorin and glycyrrhizin) were administered orally to rats from the 21th day of age to the 28th or 30th days of age for 7 or 9 days. JGT(400mg/kg) and PR(100mg/kg, 200mg/kg) treatments significantly increased serum estradiol above levels in control rats, but both GR and glycyrrhizin had no effect on this parameter. Gross observation and histological analysis revealed that an increased number of growing follicules was observed in the ovaries of JGT and PR treated rat. However the lutenized follicles and ova present in the oviducts were not observed in all rats except one treated with estrogen as a positive control. These results indicate that JGT stimulates the estrogen production and follicular maturation in the immature rat and PR is the main component to induce such reaction.