• 설비공학논문집
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• 제16권3호
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• pp.280-286
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• 2004

An experimental study is peformed to examine the heat transfer performance of individual rows of fin-tube heat exchangers. The heat transfer performance is measured using an air-enthalpy type calorimeter. The examined heat exchangers consist of 7mm tube and fin patterns of them are slit and louver types. Equivalent fin spacings are 18 fins per inch(fpi) for all samples, and the number of tube rows are two. In order to confirm that thermal boundary condition on fins of each row are the same, physically separated between two rows as well as connected heat exchangers are used. The frontal air velocity is varied from 0.7 to 2.5㎧. Heat transfer performance for each row is measured. It is observed that the heat transfer coefficient of the second row is smaller than that of the first row at low Reynolds number while larger at high Reynolds number.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.633-638
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• 2006

This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers with various fin types. A total of 8 samples of heat exchangers are tested. Fin patterns tested are slit, louver and plate fins. Each fin type has three cases of number of tube rows(N=1, 2, 3) and two different fin pitches. The results are plotted in terms of Colburn j-factor and friction factor f with respect to Reynolds number in the range of 200 to 510.

• 한국화재소방학회논문지
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• 제29권6호
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• pp.1-5
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• 2015

본 논문은 편백 루버에 붕산, 붕사 및 인산암모늄 수용액을 가압함침 후 외부 복사열원(25, 30 및 $50kW/m^2$)에 따른 점화시간, 임계 열유속 및 질량감소속도 등의 연소특성을 측정하였다. 실험에 사용된 시료의 크기는 $100{\times}100{\times}10mm$이며, 각 외부 복사열원에서 5분간 변화를 3회 반복 측정하였다. 연구결과, $25kW/m^2$의 외부 복사열원에 있어서 착화시간은 Type C-H를 제외하고는 17.4~21.3%의 지연효과를 나타낸 반면 35 및 $50kW/m^2$에서는 큰 차이가 없음을 알 수 있었으며, 평균질량감소속도는 Type A-H와 Type D-H에서 Type N-H보다 낮게 측정되었다. 또한, 외부 복사열원에 따른 착화시간으로부터 임계 열유속은 $14.79{\sim}17.17kW/m^2$로 $10.7kW/m^2$인 Type N-H보다 38.22~60.46% 높게 예측됨에 따라 초기 화재시 화재확대에 대한 지연효과가 있을 것으로 예상된다.

• 공업화학
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• 제17권5호
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• pp.476-482
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• 2006

본 연구에서는 핀-관 열교환기의 공기측 열전달 및 마찰특성을 조사하기 위하여 8종의 열교환기에 대하여 난방조건에서 실험을 수행하였다. 핀-관 열교환기의 성능 비교평가를 위하여 공기엔탈피식 칼로리미터를 이용하였다. 실험에 사용된 핀은 슬릿, 루버, 평판형이며, 관경은 7.0 mm, 열수는 1, 2, 3열 그리고 4종의 관회로에 대해 j 계수와 마찰계수를 획득하였다. 실험을 통해서 핀형상, 핀피치, 열수 그리고 관회로의 변화에 대한 핀-관 열교환기의 공기측 열전달 및 마찰거동을 조사하였다. 실험결과는 관회로의 구성이 열교환기의 열전달과 마찰과 관련이 있음을 보여주었다. 동일 핀피치의 열교환기의 경우에 저 Re 수에서는 1열의 열전달성능이 우수하나 Re 수가 증가할수록 j 계수의 거동은 역전함을 보였다. 그리고 2열의 열교환기에서 핀종류에 따라 공기측 열전달성능과 마찰계수가 다르게 나타남을 확인하였다.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.538-545
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• 2020

화력발전소의 옥외 저탄장은 주변 지역의 환경오염 문제로 인하여 국내외적으로 옥내 저탄장으로 전환되고 있는 추세이다. 하지만 옥내 저탄장의 경우 실내의 석탄 비산과 유해가스의 발생이 문제가 되고 있다. 본 연구는 옥내 저탄장 내부를 외기의 풍속 및 풍향에 따른 내부 유동장 특성과 환기량을 분석하여 환기 방안을 제시하고자 한다. 옥내 저탄장 내부에서의 실제 유동 측정 정보를 기반으로 하여 CFD 해석을 수행하였다. 외기 풍향이 동풍일 때 풍속이 6 m/s인 경우와 2 m/s인 경우를 비교해본 결과는 6 m/s일 때 Monitor louver로 배출되는 유속이 2 m/s일 때보다 빠르며 재순환 영역이 뚜렷하게 나타났다. 또한 외기 풍향이 서풍일 경우에도 동풍과 경향이 비슷함을 확인하였다. 풍속에 따른 환기량을 확인한 결과는 풍속이 6 m/s인 경우에는 환기 횟수는 13.1회, 2 m/s인 경우에는 4.4회의 환기가 가능하다. 풍속이 2 m/s인 경우에 일반 공장의 시간당 필요 환기 횟수에 미치지 못하여 다소 개선이 필요한 실정이다.

• 한국실내디자인학회논문집
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• 제23권6호
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• pp.14-21
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• 2014

Kengo Kuma is one of the features of the building is 'natural architecture'. He is saying that the construction of the building in which he is seeking is a natural material of construction is only applied to the issue as to whether the material nature, but that the relationship between humans, the environment, natural point of view in his book. Like repeating units are part of the two hundred ninety-four came mainly small ways to create a relationship, or have architectural features make up the sum of his architecture. I present a comprehensive study is reported in terms of that the 'grain' of such a small part of the unit, according to the architecture of Kengo Kuma mainly granulation characteristics of the construction of one of the practical expression studies Kengo Kuma. Is represented as louvers, check pattern, hole, granulation unit such trend, but have become developed in other directions such simple types are combined. Analysis and particle characteristics in terms of the architectural space of Kengo Kuma, serve as the purpose of the present study reveal that each of the features that have a meaning in the construction of any Kengo Kuma.

• 대한기계학회논문집B
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• 제21권1호
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• pp.113-124
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• 1997

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.

• 대한기계학회논문집B
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• 제29권9호
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• pp.1032-1041
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• 2005

This study is performed to investigate the heat transfer characteristics of heat exchanger according to the arrangement of fins as well as fin configuration by using the four times enlarged model. Friction factor, Colburn j factor and goodness factors are compared to each other to estimate performance of each case for 4 different kinds of fins, which are plain, single side slit, double side slit and louver fin. Results show that heat transfer would be altered by fin arrangement and that friction loss is more affected by fin configurations than by the fin arrangements. In particular, heat transfer depends more on the shape of front row than that of rear row. The heat transfer rate of combined fin arrangement increases a lot more under the same pressure drop than that of conventional fin arrangement. This indicates that the heat exchanger of higher efficiency would be designed by the proper combination of fins, of different shapes.

• 한국실내디자인학회논문집
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• 제13권2호
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• pp.64-71
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• 2004

This study attempts to clarify inter-relationship between design expression in the surface of contemporary multi-family housing and physical trends in this digital age. The study examines characteristics of housing design influenced from new digital technology in the forms of metaphor such as dematerialization, fluidity and mobility. Currently constructed multi-family housing in Europe after 1990 has been analyzed to find digital reflections in the surfaces. As a conclusion, findings are as follows; In this digital age, a house is considered as a base in the forms of boxes and containers to network to outer worlds. In a complex of multi-family housing, public spaces move to the inside and become parts of private domain. Therefore, a house directly faces a street/outer world without transitional areas and devices. The facades of housing become delicate skins to control private domain in the inside and the world in the outside. In this digital age, the surfaces of housing are designed by ways of wrapping and screening. Printing and mapping methods are used to surface design because they are manipulative and flexible methods in design like graphic design. Screening devices using louvers and shutters are powerful tools to make random and unpredictable images. If units of a louver and a shutter were pixels, a whole surface would be a digital screen. In such assumption, the facade of buildings reflects digital screen to interface while the louvers in operation reflect clicking to network. As a conclusion, design expression in surfaces in-between of multi-family housing is a metaphor of digital mechanism.

• Journal of Plant Biotechnology
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• 제8권1호
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• pp.1-8
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• 2006

The differential response of soybean cultivars with or without sulfur (S) application was observed under fold conditions. Plant biomass decreased by sulfur deficiency but the reduction was less in Bragg variety about 26 % relative to the control than other ones over 45%, probably due to less reduction in loaves and pods. The photosynthetic rate of Bragg cultivar was also unaffected by the absence of sulfur application while it depressed in other lines. Soybean cultivars were compared in terms of storage protein, protein quality and biomass production by application of sulfur nutrition. The storage protein concentration tended to decrease without sulfur application in all the cultivars, however the differential response of protein quality only by 11S/7S ratio to sulfur nutrition status was observed: For instance, Bragg cultivar had higher biomass and protein production but protein quality decreased at sulfur deficiency. On the other hand, biomass and protein production in other cultivars remained louver at sulfur deficiency but protein quality differed genetically in spite of sulfur nutrition status. These results suggest that the response of soybean to sulfur nutrition is controlled by genotypic difference and sulfur supply status.