• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1265-1268
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• 2009

In this paper, the effect of a flow barrier and bypass on the cooling performance for a straight fin heat sink is presented. Both side directions and upward direction of bypass are controlled using various ducts which have different width and heights. In addition, a flow barrier is used to control flow toward heat sink. Through experiments, the distance from leading edge of a heat sink to a flow barrier is varied for various bypasses under fixed volume flow rate condition. This study shows possibility to improve cooling performance when bypass and a flow barrier exist.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.11
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• pp.1127-1133
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• 2012

A finned-tube-type evaporator module has been proposed for a 2 t/h-class water-tube-type industrial boiler with multiple burners. The geometry of the fins was changed at each module to equalize the evaporation. The modules were designed by considering the energy balance at each row rather than by following a conventional bulk design procedure. The designed module was built into a 2 t/h-class water-tube-type boiler, and its performance was tested. A numerical simulation was also conducted to evaluate the two- or three-dimensional effects of factors such as the inlet conditions. The numerical simulation also included the conjugate heat transfer problem to predict the fin tip temperature. The heat transfer coefficient with fins is lower than that obtained from the empirical correlation of a bare tube. The fin tip temperature from CFD is higher than that from the analytical solution.

• Korean Journal of Ichthyology
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• v.33 no.3
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• pp.167-176
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• 2021

This study was carried out to clarify the egg, larvae and juveniles development of Abbottina springeri. For the experiments, the matured adults were collected at the Seowon-cheon, Dangjin-si, Chungcheongnam-do, in Korea. The amount of spawning of female A. springeri was about 1,225~2,100 (1,662±437, n=10). The fertilized eggs were circular in shape and 1.05~1.13 (1.08±0.02, n=30) mm in diameter. The hatching time was required 72 hours to 80 hours after fertilization under water temperature of 22℃. The newly hatched larvae were 2.10~2.23 (2.16±0.04, n=10) mm in total length and had egg yolk in the abdomen but the mouth was not opened. At 5 days after hatching, the preflexion larvae were 3.19~3.30 (3.24±0.03, n=10) mm in total length and the most of yolk-sac was absorbed. At the 15 days after hatching, the flexion larvae were 4.97~5.30 (5.13±0.12, n=10) mm in total length and the tip of the caudal fin was began to bend upward. At the 25 days after hatching, the postflexion larvae were 8.97~9.60 (9.44±0.16, n=10) mm in total length and the tip of the caudal fin was bent at 45°. At the 35 days after hatching, the juvenile were 12.0~13.5 (12.7±0.53, n=10) mm in total length and all fin-rays (iii7 dorsal fin, iii6 anal fin, i7 ventral fins) were reached a constant number of each part.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.203-208
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• 2020

This study was carried out to clarify the larvae and juveniles of egg development and autonomous development of Hemibarbus longirostris from Korea, and to obtain basic data for species conservation and seed production. The shape of the egg was circular and sticky. The average size of the eggs was 2.01 mm (n=10). At 185 hours after fertilization, more than 50% of the total embryos were hatched. The newly hatched larvae had an average total length of 8.10 mm (n=5) and had egg yolk in the abdomen. At 3 days after hatching, the larvae absorbed all egg yolk was average total length 8.64 mm. On the 6 days after hatching, the caudal tip of the notochord started to curve upwards was average total length 10.9 mm. At 70 days after hatching, the average total length 37.9 mm. The number of fins was i 8-10 in dorsal fin, iii 7 in the anal fin, and ii 5 in the ventral fin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.265-270
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• 2012

A finned tube type heat exchange module has been proposed for a multi-burner water tube boiler. Fin density and length increase in streamwise direction to equalize the evaporation for each module, which makes it difficult to apply conventional bulk design procedure. The design program has been improved by updating data for every row of tubes along the flow. A numerical simulation has been also conducted to evaluate the effect of inlet conditions and validated with experiment. The heat transfer of the first row has been underpredicted by the conventional Zhukauskas correlation, since the acceleration of the flow due to the blockage is not fully inflected. The fin tip temperature is also underpredicted by Bessel solution, because of the interaction with neighboring fins.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1140-1149
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• 2004

The absorption characteristics of water vapor into a LiBr-H$_2$O solution flowing down on finned inclined surfaces are numerically investigated in order to study the absorbing performances of different surface shapes of finned tubes as an absorber element. A three-dimensional numerical model is developed. The momentum, energy, and diffusion equations are solved simultaneously using a finite difference method. In order to obtain the temperature and concentration distributions, the Runge-Kutta and the Successive over relaxation methods are used. The flat, circular, elliptic, and parabolic shapes of the tube surfaces are considered in order to find the optimal surface shapes for absorption. In addition, the effects of the fin intervals and Reynolds numbers are studied. The results show that the absorption mainly happens near the fin tip due to the temperature and concentration gradient, and the absorbing performance of the parabolic surface is better than those of the other surfaces.

• Proceedings of the Zoological Society Korea Conference
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• 1998.04a
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• pp.33-33
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• 1998

The most recent, Jeong and Nakabo (1997) described Raja koreana as a new species based on an adult female specimen collected from the southwestern coast of Korean Peninsula. Raja koreana has several unique characters not shared with any other supraspecific taxa of Rajoidei, but it was provisionally included in the genus Raja because of having no information of its clasper. Later, two mature males and a few specimens of the species were collected from near the type locality. Therefore, a new genus should be erected for this species. The new genus is characterized by the followings: Rostral shaft straight, narrow and thick in depth: unsegmented base with filamentous cartilage. Dorsal surface of tail with a row of distinct thorns along midline, patches of distinct thorns anterior to first dorsal fin and between first and second dorsal fins in bathe sexes; most thorns directed anteriorly, and thornlets directed posteriorly. Scapulocoracoid comparatively short and high, rear corner high, without anterior bridge, postventral fenestra expanded. Distal tip of accessory terminal 1 claspser cartilage well separated from the tip of accessory terminal 2 clasper cartilage.

• Journal of the Korean Society of Visualization
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• v.5 no.2
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• pp.20-25
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• 2007

The geometry of a commercial passenger airplane is realized based on a Boeing 747-400 model through the photographic scanning and reverse engineering. The each element consisting of the plane such as fuselage, wing, vertical fin, stabilizer and engines, is individually generated and then the whole body is assembled by the photomodeler. The maximum error in the realized airplane is about 1.4% comparing with the real one. The three-dimensional inviscid steady compressible governing equations are solved in the unstructured tetrahedron grid system, and in a finite volume method using STAR-CD when the airplane flies at the cruise condition. The pressure distribution on the surface and the wing-tip vortices are visualized, and in addition to the aerodynamics coefficients, lift and drag are estimated.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.244-252
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• 2023

This study compared the morphological and molecular characteristics of the two Pampus spp. in Korea, Japan and China to clarify the long-confused taxonomic status of the two Korean pomfrets named as "Byeong-eo" and "Deok-dae". Among them "Byeong-eo" was identified as Pampus punctatissimus in having the following morphological traits: patch of wavy ridges extending beyond the anterior tip of the pectoral fin, the groove on the lower ridge of gill cover absent, and the number of vertebrae 34. On the other hand, "Deok-dae" was identified as Pampus argenteus in having the following morphological traits: patch of wavy ridges not reaching to the anterior tip of the pectoral fin, the groove on the lower ridge of gill cover reaching to the lower jaw, and the number of vertebrae 38~42. In addition, "Byeong-eo" almost corresponded to P. punctatissimus from Japan in the mitochondrial DNA cytochrome c oxidase subunit I sequences (genetic distance=0.1%), while "Deokdae" showed genetic distance of 0.3% when compared to P. argenteus from China. Our comprehensive results suggest the validify of P. punctatissimus for "Byeong-eo", and P. argenteus for "Deok-dae".

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.179-188
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• 1981

The authors made an investigation concerning the geographical distribution and some major differentiations in morphological characteristics associated with the each habitat, of the pond smelt, Hypomesus olidus, which was introduced into Korea more than 50 years ago. Major characteristics utilized for the comparison study were upper jaw (maxillary), number of fin rays, scale structure, vertebral count, number of pyloric caeca, number of gill rakers, and the relative measurements of these and other internal characters. 1. The main areas of natural distribution are Paro Lake, Soyang Lake, Han River, Euirim Lake, and Ogjeong Lake (or Unam Lake) and the tributaries of these waters. 2. Morphological variations varied when the mean values of measurements from each area were compared with the standard measurement value by mosaic comparison, and in some instances a significant variation was found. 3. The most significant variations were found in the number of fin rays of pectoral and anal fins; the lengths from the tip of snout to the origin of pectoral fin, from snout to ventral fin, and from snout to anal fin, relative to standard body length; eye depth relative to head length; upper jaw: the number of pyloric caeca and the scale structure. Variations, on the other hand, by each habitat were not clear in the numbers of ventral and dorsal fin rays, gill rakers, vertebrae and lateral line scale : and the depth of caudal peduncle and distance from the tip of snout to the origin of dorsal fin relative to standard body length. 4. The scales of pond smelt showed some differences in the shape of scales, the shape and position of the focus and the number of ridges according to the scale positions on the body. No radii were present. The relations between longitudinal and transverse diameters of the scale suggest that the pond smelts of Soyang Lake and Un-am Lake are closely related, and those of Han River and Euirim Lake are also closely related. 5. The geographical variations in morphology of the pond smelt seem to have resulted from the variations in turbidity, water temperature, salinity (rather conductivity) and currents. 6. From the results obtained, it may be concluded that such factors as supramaxillary, relation between scale length and its breadth, number of caudal vertebrae and eye depth relative to head length may be used as the key characters for the classification of geographical varieties of Pond smelt.