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탈수소 열처리 공정에 의한 원심주조 메탈베어링의 제조 시스템
김정훈(Jeung-Hun Kim),김충구(Chung-Gu Kim),변재영(Jea-Young Byen),이은숙(Eun-Suk Lee),양지웅(Ji-Yung Yang),최원식(Won-Sik Choi) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.5
Centrifugal casting is suitable for producing hollow-products using centrifugal force. Bush type metal bearings are the key parts that facilitate the rotational movement of various machinery. Metal bearings produced by conventional centrifugal casting machines show rotational imbalance. Therefore, after injecting a large amount of material, the product"s precision is secured in the secondary processing. Rotational imbalance is caused by the force acting on the rotary disc plate. In order to minimize rotational imbalance, NASTRAN was used for the optimal design and structural analysis. It was concluded that the rotating plate of the conventional centrifugal casting machine should be prevented from tilting. For this purpose, the location & thickness of the stiffeners were obtained through the optimum design. In the conventional centrifugal casting machine, both ends of the product are lower in temperature than the center part, so internal stress occurs. This solves this problem by inserting a heating coil into the rotating plate.
설문조사에 의한 근로자 중심의 안전분임토의를 통한 건설업 위험성 평가 개선방안 사례연구
김정훈 ( Jeung Hun Kim ),오태근 ( Tae Keun Oh ) 한국안전학회(구 한국산업안전학회) 2016 한국안전학회지 Vol.31 No.5
The current risk assessment system do not reflect workers’ various opinion. However, the worker actually are in the center of work field and are exposed to accidents. In this regard, this study suggests enhanced risk assessment by ``safety circle discussion`` on workers’ hand. The self-administered surveys on supervisors and workers were done for the effect analysis of the safety circle discussion. According to the question investigation, even though the current risk assessment causes difficulties in preventing accidents by unsafe behaviors, the worker-oriented safety circle discussion establishing measures for risk factors of each work type will be able to prevent accidents more effectively. Also, it can positively contribute to safety health awareness, industrial accident prevention, accurate recognition on risk factors, improving safety facilities/work conditions, workers`` compliance to safety health rules. Lastly, most respondents agreed that it is necessary to form organic relationship through circle discussion and deriving safety inspections that workers participate.
하이브리드 열교환기 적용 컴팩트 고압 스팀 유닛 개발에 관한 기초 연구
김정훈(Jeung-Hoon Kim),임계훈(Gye-Hun Lim),김승현(Seung-Hyun Kim),진철규(Chul-Kyu Jin),박재홍(Jae-Hong Park),조성열(Sung-youl Cho),홍인기(In-Ki Hong),이상래(Sang-Rae Lee) 대한설비공학회 2015 대한설비공학회 학술발표대회논문집 Vol.2015 No.11
In the various plants such as power plant and petro-chemical plant and industrial facilities such as unit factory, the demand of heating and hot-water supply system using steam are more and more increasing. Compact steam unit is one of good solution in terms of energy reuse as system for making hot water and hot-water supply water using closed-loop system. It was intended to understand the characteristics of heat transfer and pressure drop using hybrid heat exchanger to apply high pressure compact steam unit(CSU) for industrial plants and unit factory by experimental methods. The experimental results are the followings. Heat balance between hot side and cold side was within ± 5 %. j factor was increased linearly as the Reynolds number was increased. And, Overall heat transfer coefficient exceeded 4,750 kcal/㎡h℃ when the flow velocity was 0.5 m/s above on both first test(narrow gap side) and second test(wide gap side). And, f factor was decreased as the Reynolds number was increased. Finally, pressure drop per unit length was below 0.5 bar/m on both first test(narrow gap side) and second test(wide gap side).
극세관 헬리컬 코일 증발관내 R-22의 열전달 및 압력손실 특성
김주원,김정훈,서석기,김정훈,김종수,Kim, Ju-Won,Kim, Jeong-Hun,Seo, Seok-Ki,Kim, Jeung-Hoon,Kim, Jong-Soo 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.5
To make compact evaporator, experiments that show characteristics of evaporating heat transfer and pressure drop in the helically coiled small diameter tube were taken in this research. The experiments were performed with HCFC-22 in the helically coiled small diameter tube; inner diameter=1.0(mm), tube length=2.0(m), and curvature diameter=31, 34, 46.2(mm). The experiments were also carried out with the following test conditions; saturation pressure=0.588(MPa), mass velocity=$150{\sim}500(kg/m^2s)$, and heat flux=$1{\sim}5(kW/m^2)$. The experiment results are that the empirical correlation to predict heat transfer coefficient for single phase flow in helically coiled small diameter tube was obtained. It was found that dry-out is occurred at low-quality region for evaporation heat transfer because of breaking of annular liquid film. The friction factor of single phase flow of helically coiled tube was agreed with Prandtl's correlation. Finally, It was proposed for correlation that can precisely predict the friction factor of two phase flow of helically coiled tube.
열전소자와 PHP를 이용한 화장품 냉장고의 냉각성능에 관한 연구
이승훈(Seung-Hun Lee),공상운(Sang-Un Gong),김정훈(Jeung-Hoon Kim),김종수(Jong-Soo Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The purpose of this study is to improve the cooling performance of a cosmetic refrigerator using a thermoelectric module combined with a pulsating heat pipe. The pulsating heat pipe was used as a heat spreader and a heat sink for a thermoelectric module. Heat was absorbed and dissipated by combined the heat sink equipped with fans. Experiments with a 1 thermoelectric module (5.3 A/15.4 V, size: 40×40×4 ㎜) and a pulsating heat pipe (working fluid charging ratio, etc.) were performed. For the thermoelectric cooling system with a pulsating heat pipe, the temperatures in the cosmetic refrigerator are recorded and then compared with those of lumped system analysis. The results indicates that cooling capacity increases as temperature difference between hot and cold surface decreases.