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Study on Characteristics of Heat Transfer and Flow in Plate Heat Exchanger
김진화(Zhen-Hua Jin),이광성(Kwang-sung Lee),지명국(Myoung-Kuk Ji),정한식(Han-Shik Chung),정효민(Hyo-Min Jeong) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
In present work, experiments conducted to investigate the heat transfer characteristics and relationship between operating parameters and production of fresh water as output of the system. Plate Heat Exchanger (PHE) applied in vacuum evaporator for product fresh water that system intended to efficiently use low grade heat. PHE have become popular in chemical, power, food and refrigeration industries due to the efficient heat transfer performance, extremely compact design and flexibility of extend or modify to suit changed duty. The heat transfer part contains corrugated plates with 60 degree of chevron angle which verified by many researchers and commonly apply. Fresh water can be produced from saline water under near vacuum pressure by operating ejector. Consequently, evaporating temperature stay around 51-57 ℃ so it is possible to use any low grade heat source or renewable source. The maximum fresh water produced by freshwater generator with plat heat exchanger applied in the study was designed as 1.0 Ton/day.
증기 구동식 진공 시스템을 이용한 해수 냉각 특성에 관한 실험적 연구
최민식(Min-Sik Choi),金鎭花(Zhen-Hua Jin),신유식(You-Sik Shin),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung),배태열(Tae-Yeol Bae) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
A steam ejector is a device which is used to transport vapor or liquid at low pressure to a higher pressure or to make vacuum as its simplicity and reliability. It is widely used in refrigeration system, power system and food industry etc. This study showed the water cooling system by using a steam ejector to drop water temperature by about 5℃ from 25℃ or higher. In this study, to replace the present water cooling system, we focused on a water cooling system operated by the latent heat of evaporation, thus this system needs a vacuum pressure to evaporate the water in enclosed tank. The water cooling effects are depended on the vacuum pressure in the enclosed tank, and the cooling water is generated by the latent heat of evaporation. As the experimental results, the absolute vacuum pressure was obtained about 8~12㎜Hg by using a steam ejector. The necessary time to reach this vacuum pressure was about 5minutes and the temperature difference of the water were obtained about 5℃.
홍경천(紅景天)추출물(KH101)이 강제유영 흰쥐의 피로회복에 미치는 영향
정혁상,김은영,심은섭,이현삼,문은정,김진화,김선여,손영주,손낙원,Jung, Hyuk-Sang,Kim, Eun-Young,Shim, Eun-Sheb,Lee, Hyun-Sam,Moon, Eun-Jung,Jin, Zhen-Hua,Kim, Sun-Yeou,Sohn, Young-Joo,Sohn, Nak-Won 대한한방내과학회 2008 大韓韓方內科學會誌 Vol.29 No.4
Objectives : Rhodiola rosea has been used in herbal medicine to treat various conditions, such as antimelancholia, antifatigue, improvement of work competence and prevention of altitude sickness. In this study, we investigated effects of Rhodiola rosea extract (KH101) on fatigue in forced swimming rats. Methods : Sprague-Dawley rats were induced with fatigue by forced swimming, then rats in each group were treated with KH101. We observed changes of glucose, LDH and cortisol in serum and LDH, glycogen, hexokinase, citrate synthase MDH, SDH and CK in muscle. Results : Obtained results were as follows: 1. Continuance times of exercise significantly increased in all groups at day 1, in the 50 mg/kg concentration group at day 2, in all groups at day 3 and in the 50 mg/kg conc. group at day 4. 2. In serum, glucose significantly decreased in all concentration groups. 3. In the soleus muscle, LDH significantly decreased in the 50 mg/kg concentration group. HK significantly decreased in the 100 mg/kg conc. group. SDH significantly increased in the 100 mg/kg conc. MDH were significantly decreased in all conc. groups. 4. In the gastrocnemius muscle, HK significantly decreased in all concentration groups, while MDH significantly increased all conc. groups. Conclusions : It is concluded that the KH101 has and anti-fatigue effect in rats. Additional studies are needed to find the mechanism of the association between each single herb.
저속 고토오크 모터용 Gerotor Profile 설계 및 이 끝 틈새에 따른 모터 성능특성 연구
서종수(Jong-Soo Seo),김보한(Bo-Han Kim),金鎭花(Zhen-Hua Jin),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. The influence of the tip clearance between circular tooth and roller pin has been explored by experimental data in this paper. At the same time a improvement method of gerotor profile for getting optimum tip clearance are also analyzed.
다중효용 담수설비용 열압축기의 디퓨져 형상에 관한 연구
최두열(Du-youl Choi),정한식(Han-shik Chung),정효민(Hyo-min Jeong),김진화(Zhen-hua Jin),김필환(Pil-hwan Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
A thermocompressor is the equipment which compresses a vapor to a desired discharge pressure. Since it was first used as the evacuation pump for a surface condenser, it has been widely adopted for energy saving systems due to its high working confidence. In the present study, the geometrical analysis of the shape between the jet nozzle and the diffuser inlet, the drag force was calculated by means of the integrated equation of motion and the computational fluid dynamic (CFD) package called FLUENT. The computer simulations were performed to investigate the effects by the various suction flow rates, the distance from jet nozzle outlet to the diffuser inlet and the dimensions of the diffuser inlet section through the iterative calculation. In addition, the results from the CFD analysis on the thermocompressor and the experiments were compared for the verification of the CFD results. Furthermore, in this study, a special attention was paid on the performance of the thermocompressor by varying the diffuser convergence angle of 0.0°, 0.5°, 1.0°, 2.0°, 3.5° and 4.5°. With the increase of the diffuser convergence angle, the suction capacity was improved up to the degree of 2.0° while it was decreased over the degree of 2.0°.
부영민 ( Yung Min Bu ),백선경 ( Sun Kyung Baek ),김진화 ( Zhen Hua Jin ),강동호 ( Tong Ho Kang ),노승주 ( Seung Ju Rho ),김호철 ( Ho Cheol Kim ) 대한본초학회 2004 大韓本草學會誌 Vol.19 No.2
N/A Objectives: The root of Rhodiola sachalinensis A. bor (RS), which has been used to strengthen qi(補氣), reduce heat of lung (淸縮), nourish heart (養心), stop bleeding (止血), reduce edema(消腫) for the treatment of fatigue, amnesia, bleeding and edema. It`s flavour and channel tropism is sweet (甘), acting on the lung (肺). The purpose of the study we report here was to determine the neuroprotective effect of the roots of RS on transient focal cerebral ischemia in SD rats. Methods: The root of RS was lyophilized after extraction with 85% methanol. We occluded middle cerebral artery for 90 minutes and reperfused for 24 hours. The brain slices were stained by 2 % 2, 3, 5-triphenyltetrazolium chloride and the infarct volume was measured by graphic analyzer. Results: The root extracts of RS showed significant neuroprotective effects (100 mg/kg, p〈0.05) compared with control group. The neuroprotective efficacy was about 35%. Immunohistochemical data explained the protective effects of RS via attenuation of COX-2 induction in neocortex and inhibition of microglia activation in the penumbral region. Conclusions: The root of RS has neuroprotective effects on transient focal cerebral ischemia in Spargue-Dawley rats and the mechanism might be the attenuation of COX-2 induction and microglial activation.