희망과 도약의 2016년! - "진화하는 규제 품질의 KINS"

김무환,Kim, Mu-Hwan 한국원자력산업회의 2016 원자력산업 Vol.36 No.1

고온 실린더의 미스트 냉각

김무환,이수관,박지만,이필종,Kim, Mu-Hwan,Lee, Su-Gwan,Park, Ji-Man,Lee, Pil-Jong 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.3

Heat treatment such as quenching of a high-temperature cylinder is being used on steel to produce high strength levels. Especially, the mist cooling with the high and uniform surface heat flux rate s expected to contribute for better products. The experimental mist cooling curve is produced for better understanding, and two distinct heat transfer regions are recognized from the cooling curve produced. It is shown that the liquid film evaporation dominated region follows the film boiling-dominated region as decreasing the temperature of test cylinder by mist flow. Based on the intuitive view from some previous investigations, a simplified model with some assumptions is introduced to explain the mist cooling curve, and it is shown that the estimation agrees well with our experimental data. In the meanwhile, it is known that the wetting temperature, at which surface heat flux rate is a maximum, increases with mass flow rate ratio of water to air ($\varkappa$ < 10). However, based on our experimental data, it is explained that there exists a critical mass flow rate ratio, at which the wetting temperature is maximum, in the range of 3 < $\varkappa$ < 130. Also, it is described that despite of the same value of $\varkappa$, the wetting temperature may increase with mist velocity.

학교급식이 초등학생의 식행동에 미친 영향에 대한 아동과 어머니의 인식 비교

김무환(Mu-Hwan Kim),이경애(Kyoung-Ae Lee) 한국식품영양과학회 2003 한국식품영양과학회지 Vol.32 No.4

본 연구에서는 초등학교 아동과 어머니를 대상으로 학교 급식이 아동의 식행동에 미치는 영향을 조사ㆍ비교하여 초등학교에서의 바람직한 급식지도와 학교급식의 균형적인 목적달성을 위한 식생활교육 방향 설정에 도움이 되는 기초 자료를 제시하고자 초등학교 6학년생 425명(남자 215명, 여자 210명)과 어머니 412명을 대상으로 설문 조사를 실시하였다. 조사결과, 학교급식은 초등학생들에게 식사에 대해 바른 이해를 도모하며 편식교정에 효과적이고 간식 섭취에 긍정적인 효과를 보였다. 또한 학교급식을 통하여 초등학생들은 바람직한 식생활태도와 식사예절을 지니게 되었으며 아동의 식생활 위생관리에도 효과적이었다. 그러나 간식섭취(간식의시기, 간식으로 적합한 식품의 선택과 적절한 양), 아침식사 반드시 하기, 식사중 책이나 텔레비전 시청하지 않기, 어른이 드신 후 식사하기 등 가정에서의 식사와 관련이 큰 항목들에 있어서는 ‘급식 후에도 여전히 그렇지 않다’는 의견이 다른 항목에서보다 많아 이에 대한 보다 세심한 지도가 필요하며 특히 바람직한 식습관 형성과 올바른 식사 방법 지도에서 학교급식이 효과를 거두기 위해서는 가정과 연계한 지속적인 지도가 있어야 하겠다. 학교급식이 아동의 식행동에 미치는 효과는 아동 성별간이나 어머니의 직업 유무에 따라서는 단지 몇 항목을 제외하고는 차이가 없었으나 아동과 어머니간에는 2개 항목을 제외한 모든 항목에서 차이를 보였으며 아동보다 어머니들이 학교급식이 아동의 식행동에 미치는 영향에 대해 더 긍정적이었다. 이는 최근의 어머니들은 과거에 비해 아동의 식생활교육에 대해 학교교육에 대한 의존도가 높아졌다는 것을 의미한다. 결론적으로 학교급식은 어릴 때부터 아동들의 잘못된 식행동을 바로 잡아 신체적, 정신적인 성장 발달의 정상화를 이루고 보다 좋은 식습관을 형성시키는 데 도움을 준다고 할 수 있다. 그러므로 성장기 아동의 식생활 습관이 성인기의 건강에까지 영향을 미친다는 점을 고려하여 앞으로 영양사 뿐 아니라 초등 교사들도 학교 급식을 하나의 교육활동으로 간주하여 보다 적극적인 자세로 지도에 임할 필요가 있다고 생각되며 이러한 효과를 극대화하기 위해서는 가정과 연계한 지도도 이루어져야 할 것이다. This study compared the perceptions of children and their mothers of the effects of school lunch programs on the children's dietary behaviors in elementary schools. Questionnaires were answered by 425 elementary school students and their 412 mothers in the Busan area. The results indicated: The school lunch program had positive effects on children's dietary behaviors such as understanding healthy meals, correcting unbalanced diets, snack intake, attitude toward the meal, table manners, and table hygiene. However, there were still some negative habits in the home related to snack time, reading books or watching television during mealtime, eating foods before seniors have started. The gender of the children and whether the mothers worked or not produced no significant differences (in most cases). Still mothers more positively perceived the effect of school lunch programs on their children's dietary behaviors than did the children themselves. Thus, the school lunch program had positive effects for a balanced diet and making good eating habits. And, therefore, teachers-as well as the dieticians-should actively regard the school lunch program as an educational activity which can produce positive effects for a balanced diet, and make every endeavor to strengthen their relationship with the home.

건축물 캐노피의 풍하중에 따른 지지단 반력 평가

김무환(Kim Mu-Hwan),홍성일(Hong Sung-Il),곽철승(Kwak Chul-Sung),조강표(Cho Kang-Pyo) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

Canopies are attached to buildings usually as a cantilever type excepting long one supported by columms . The upper and lower surfaces of a canopy can be largely affected by winds. For this reason, wind load as well as dead loads should be considered in the design of canopies. In the previous study, wind pressure distribution on the canopy were investigated according to the installation heights and inclinations of a canopy. In this study, vertical and moment reactions at the support of a canopy are approximately computed by integrating wind pressures according to its installation heights and inclinations, and the reactions are compared by the installation heights and inclinations. In Korea, design wind loads for canopies are not prepared and are being approximated by structural engineers in practice. Accordingly, the method for estimating wind loads to be employed in the design of canopies is required.

건축물의 캐노피의 풍압분포

김무환(Kim Mu-Hwan),홍성일(Hong Song-Il),조강표(Cho Kang-Pyo) 대한건축학회 2008 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.28 No.1(구조계)

Most of the buildings are used for residential purposes and thus provided with different types of projections for the convenience of the users of the building. This paper presents change of distribution of wind pressure coefficient on canopies of buildings. Four different angles of canopies were considered and also the position of canopy were changed. The pressure distribution on canopies were shown based on mean, max and min values.

전기장을 이용한 핵비등 열전달 촉진에 관한 실험적 연구

권영철,김무환,강인식,Gwon, Yeong-Cheol,Kim, Mu-Hwan,Gang, In-Sik 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12

To understand EHD nucleate boiling heat transfer enhancement, EHD effects on R-113 nucleate boiling heat transfer in a non-uniform electric field were investigated. The pool boiling heat transfer and the dynamic behavior of bubbles in d.c./a.c. electric fields under a saturated or subcooled boiling were studied by using a plate-wire electrode and a high speed camera. From the pool boiling heat transfer study, the shift of the pool boiling curve, the increase of the heat transfer and the delay of ONB and CHF points to higher heat fluxes were observed. From the dynamic behavior of bubbles, it was observed that bubbles departed away from the whole surface of the heated wire in radial direction due to EHD effects by a nonuniform electric field. With increasing applied voltages, the bubble size decreased and the active nucleation site and the departure number of bubbles showed the different trend. The present study indicates that the EHD nucleate boiling heat transfer is closely connection with the dynamic behavior of bubbles and the secondary flow induced near the heated surface. Therefore, the basic studies on the bubble behavior such as bubble frequency, bubble diameter, bubble velocity and flow characteristics are necessary for complete understanding of the enhancement mechanism of the boiling heat transfer using an electric field.

균일전기장에 의한 기포와 액적의 변형에 관한 연구

권영철,김무환,강인석,조혜정,김석준,Gwon, Yeong-Cheol,Kim, Mu-Hwan,Gang, In-Seok,Cho, Hae-Jung,Kim, Suk-Joon 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.6

In the present study, the characteristics of the electrical deformation of a bubble and a drop under a uniform electric field have been investigated to understand EHD heat transfer enhancement by an electric field. The deformation of the bubble and the drop have been studied theoretically using an electric normal stress acting on their interfaces and assured by the numerical analysis and the experiment. From the variation of bubble volume and free energy, it is found that a bubble is compressed in an electric field and free energy had larger value with increasing W and the permittivity of a dielectric fluid. The electric normal stress induced on the interface of the bubble and the drop is different. Because of the surface charge induced at the drop interface, the electric normal stress acting on the drop is much larger than that of the bubble. The drop is, therefore, deformed much more than the bubble. In addition, the experimental and numerical results show that the aspect ratio and the contact angle of the bubble increase with increasing W.

2열 휜 튜브 열교환기의 공기측 압력강하 및 열전달 특성을 고찰하기 위한 확대 모형실험

강희찬,김무환,Gang, Hui-Chan,Kim, Mu-Hwan 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.1

This work is performed to investigate the pressure drop and heat transfer characteristics in the air side of finned-tube heat exchanger for air conditioner. Experimental apparatus and method are described to simulate the heat exchanger performance by using the three times enlarged model. The pressure drop and heat transfer coefficient were measured and compared for the heat exchangers with a plane fin and a commercial strip fin. The measured data for the strip fin agree well with those of prototype within a few percentages. For the plane fin, the measured data had similar trend to Gray & Webb's correlation at high air velocity, however a new correlation is needed to give more accurate prediction at low air velocity. It is found that most heat was transferred around the front row of the two-row heat exchanger, and the ratio of thermal load at the front tube row was increased for decreasing air velocity.

기술초대석 - 건축물 캐노피에 작용하는 풍하중의 산정

조강표,홍성일,김무환,Jo, Gang-Pyo,Hong, Seong-Il,Kim, Mu-Hwan 한국건축구조기술사회 2009 건축구조 Vol.16 No.3

초고층 건축물의 공력학적 설계에 의한 풍진동 저감 효과

홍성일(Hong Sung-Il),김무환(Kim Mu-Hwan),이옥진(Lee Ok-Jin),조강표(Cho Kang-Pyo) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

Modern tall buildings having multiplex functions are increasing in height for the powerful use of land by the development of construction skills, the progress of structural analysis techniques, the concentration of population, and industrial and economic development of modern society. Wind-induced vibration of tall buildings are mainly due to buffeting, vortex and wake. Also, wind-induced responses of buildings are different according to the geometry of buildings, structural characteristics such as stiffness, mass and damping, and turbulent characteristics of wind. In this paper, wind-tunnel experiments are performed using variables such as the plane and elevation shapes and aerodynamic apparatus of buildings. The square, equilateral triangular and circular sections were selected as plane shapes of buildings, and the setback and tapered types were tried for the circular section. Also, wind-induced responses were investigated for a total of nine models having equivalent effective slenderness ratios by attaching ribs and spirals to the circular model, the setback type model, and the tapered type model. From the results of the experiments, wind-induced response was the least for the circular section, and the wind-induced response for the setback type was much smaller than that of the tapered type. The ribs and spirals as aerodynamic apparatus had the similar damping effects in the cross-wind direction.