• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1034-1039
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• 2004

The row-by-row heat transfer characteristics of fin-and-tube heat exchangers having wavy fins were experimentally investigated. Three samples having different rows (one, two and three) were tested. Results show that the heat transfer coefficient is strongly dependent on the tube row. The heat transfer coefficient of the first row is larger than those of second or third rows. However, the difference decreases as the Reynolds number increases. The heat transfer coefficients of the second and the third row are approximately the same, probably due to increased mixing of bulk flow by wavy channels. Although samples have different tube row, the heat transfer coefficients of same row are approximately the same.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.149-155
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• 2007

The row-by-row heat transfer characteristics of fin-and-tube heat exchangers were experimentally investigated. Three wavy fin samples having different rows (one, two and three) and one plain fin sample (three row) were tested for $600{\leq}Re_{D}{\leq}4,000$. The heat transfer data were obtained for individual rows, and the corresponding heat transfer coefficients were reduced from the data. Results showed that the heat transfer coefficients were strongly dependent on the tube row. The heat transfer coefficient decreased as the tube row increased. However, the row effect was different depending on the fin shape. For the wavy fin, the row effect significantly decreased as the Reynolds number increased, yielding approximately the same heat transfer coefficients at $Re_{D}{\approx}2,500$. For the plain fin, however, the row effect lasted for the whole Reynolds number range. The increased mixing of bulk flow by wavy channels appears to induce high heat transfer coefficient (accordingly diminishing row effect) at downstream rows. The heat transfer coefficients of individual rows were higher for heat exchangers having larger tube rows.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.646-655
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• 1995

본 연구에서는 기저역행렬의 계산방법에 따른 효율적인 자료구조를 실험적으로 검토하고, 입력자료방식과 효율화 방법을 제안하여 구현하였다. 기저역행렬의 계산방법에 따른 효율적인 자료구조는 명시형에서는 연결리스트 방식이 유리하였으며, 상하분해형에서는 연결 리스트 방법과 Gustavson 방법이 비슷한 효율을 보였다. 새로운 비영요소의 도입이 많은 경우일수록 연결 리스트가 효율적인 자료구조인 것으로 분석된다. 그리고 MPS자료의 입력방식과 효율화 방안에서는 각 열별로 행 정렬을 실시하고 해싱(hashing)함수를 도입하여 효율화를 기하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.3
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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.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.95-101
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• 2008

The wind speed reduction capability of forest belt of Caragana Korshinskili Kom in Yanchi, Ningxia province in China is as follows. 1. At the height of 0.5 m, the windbreak effect is 3-Strip (30.22%) > 2-Strip (26.53%) > 1-Strip (16.28%) from 1H (H = Tree Height) to 5H, and the windbreak effect is 2-Strip (16.11%) > 3-Strip (12.79%) > 1-Strip (9.82%) for greater than 7H. Further analysis of 2-Strip and 3-Strip revealed that the wind reduction effect of 2-Strip spread to 44H and 3-Strip spread to 27H. This result implies that 3-Strip is most effective for short distances and 2-Strip is most effective for long distances. 2. At the height of 1.0m, the wind speed was relatively constant and the reduction rate of wind speed had a minimal variation, with the reduction rate of 1-Strip (8.04%), 2-Strip (8.23%), and 3-Strip (7.43%). 3. The sandbreak effect is 2-Strip (55.28%) > 3-Strip (37.13%) > 1-Strip (20.87%). Especially, The rate of sandbreak of 1H (86.06%) of 2-Strip is most effective value in whole data.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.150-156
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• 1983

Five cases of Diphyllobothrium latum infection were proved by collection of worms after treatment with bithionol, niclosamide or praziquantel, during 1975~1983. The patients were 4 males and one female aged 10~64 years residing in Seoul or Wando-gun, Chollanam-do, Korea. All of them remembered the history of eating several kinds of raw marine fish and 2 persons said they ate the raw mesh of perch, Lateolabrax japcnicus. Three amcnE them experienced abdominal pain, 2 natural discharge of a chain of segments, but none revealed any sign of anemia. The average egg size in stool varied $59~67{\times}41~48{\mu\textrm{m}}$ according to cases. The eggs were characterised by ovoid to elliptical shape, terminal operculum, and distinct abopercular protuberance. One naturally discharged segment (30cm) and 4 complete strobilae (320~680cm) with scolices obtained after treatments were examined. The morphological characters of proglottids such as rosette-form uterus with 3~6 loops, vaginal pore included in the cirrus sac, separated seminal vesicle from cirrus sac, etc. were all compatible with D. latum. These are the 7th~11th cases of D. latum infection proved by worms in Korea.