• Journal of Advanced Marine Engineering and Technology
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• 제25권3호
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• pp.552-562
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• 2001

Measurement of average of heat transfer and friction coefficients were obtained with air flowing through electrically heated ducts having square, rectangular(aspect ration, 5), and triangular cross section for range of surface temperature from $540^{\circ}$to $1780^{\circ}$ R and Reynolds number from 1000 to 330,000. The results indicates that the effect of heat flux on correlations of the average heat transfer and friction coefficients is similar to that obtained for circular tubes in previous investigation and was nearly eliminated by evaluating the physical properties and density of the air a film temperature halfway between the average surface and fluid bulk temperatures, With the Nusselt and Reynolds numbers on the hydraulic diameter of the ducts, the data for the noncircular ducts could be represented by the same equations obtained in the previous investigation for circular tubes. Correlation of the average difference between the surface corner and midwall temperatures for the square duct was in agreement with predicted values from a previous analysis. However, for the rectangular and triangular ducts, the measured corner temperature was greater by approximately 20 and 35 percent, respectively, than the values predicted by analysis.

• 수산해양기술연구
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• 제18권1호
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• pp.47-53
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• 1982

본 논문은 비균일대칭성 열Flux인 수직사각 Duct내의 층류조합대류 열전달 효과를 해석하기 위하여 그 유동의 특성 지배 방정식 및 비균일 열Flux의 경계조건을 무차원화 시켜 이를 Galerkin's 방법에 의해 유한요소식으로 정식화하고 이에 대하여 R 하(a) 수 및 압력구배 변수에 대해서 Duct 내의 온도분포, 속도분포 및 Nusselt 수의 값을 계산하였고 온도분포를 열 Flux가 일정 및 없는 경우와 비교하였으며 또 닥트내의 열전달 특성을 R 하(a) 수, 응력구배변수 및 Corner에 따른 변호경향을 조사하였다. 그 결과 1. 본 해석의 경계벽 온도분포 계산치와 유효자료들과의 비교에서 열 Flux가 일정 또는 없는 경우는 그 값이 일치하였다. 2. 닥트내의 온도분포와 Nusselt수의 값은 R 하(a) 수 및 압력구배 변수에 비례하여 증감하였다. 3. Nusselt수는 Corner에서 유속지연에 의한 온도분포의 특성 때문에 그 값이 감소하였으며 최대치는 0.7부근이었다

• 한국전산유체공학회지
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• 제8권2호
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• pp.8-15
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• 2003

Three nonlinear κ-ε models with the wall function method are applied to the fully developed turbulent flow in a triangular subchannel of a bare rod bundle. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and wall shear stress are compared in details both qualitatively and quantitatively with both each other and experimental data. The nonlinear κ-ε models by Speziale[1] and Myong and Kasagi[2] are found to be capable of predicting accurately noncircular duct flows involving turbulence-driven secondary motion. The nonlinear κ-ε model by Shih et aL.[3] adopted in a commercial code is found to be unable to predict accurately noncircular flows with the prediction level of secondary flows one order less than that of the experiment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.241-247
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with ones roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones in the range we studied.

• 동력기계공학회지
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• 제5권2호
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• pp.30-35
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one wall roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at $e/D_e=0.0476$, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicate that the triangular type rib has a substantially higher efficiency index than any other ones in the range we studied.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2190-2203
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• 2004

A combined procedure for two-dimensional Delaunay mesh generation algorithm and an adaptive remeshing technique with higher-order compressible flow solver is presented. A pseudo-code procedure is described for the adaptive remeshing technique. The flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is proposed. The scheme eliminates nonphysical flow solutions such as the spurious bump of the carbuncle phenomenon observed from the bow shock of the flow over a blunt body and the oscillation in the odd-even grid perturbation in a straight duct for the Quirk's odd-even decoupling test. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. The performance of the combined procedure is evaluated on unstructured triangular meshes by solving several steady-state and transient high-speed compressible flow problems.

• 환경생물
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• 제39권4호
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• pp.523-525
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• 2021

Two species of the genus Oxytate L. Koch, 1878 have been recorded in Korea to date. The spider fauna was surveyed in the mountainous terrain of Mt. Hallasan National Park in 2019. A female of Oxytate lobia sp. nov. was collected with a sweep net between shrubs in mixed forests during a seasonal spider survey and is described with measurements, morphological illustrations, and a diagnosis. The new species can be easily distinguished from similar species within the genus by the long copulatory duct conjugated with a spermatheca, a pair of triangular pits at the bottom, and no ditches.

• 대한영상의학회지
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• 제83권5호
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• pp.991-1002
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• 2022

담도폐쇄증은 신생아 담즙 정체의 드물지만 중요한 원인이다. 적절한 치료와 예후를 위해서는 정확한 조기 진단이 중요하다. 본 종설에서는 초음파 검사, MRI, 간담도 핵의학스캔, 담관조영술 등의 영상 검사에서 담도폐쇄증의 영상 소견을 검토하였다. 지금까지 알려진 주요 영상의학적 소견들은 담낭의 비정상적인 모양과 크기, 간문맥 주변의 비후를 나타내는 'triangular cord' sign, 총담관이 보이지 않고, 간동맥 혈류가 증가하는 소견 등과 함께 동반된 기형의 유무들을 보이는 것이다. 담도폐쇄증의 진단을 위해 초음파 검사, MRI, 간담도 핵의학 스캔, 담관조영술 등의 여러 영상 검사들을 시행하며, 1차 영상 검사로 초음파 검사가 중요하다. 본 종설에서는 각 영상 검사들에서 지금까지 알려진 담도폐쇄증의 소견들과 함께 조기 신생아기에서 담도폐쇄증 진단의 어려움, 그리고 간 섬유화를 예측하기 위한 영상의 역할도 검토하였다. 본 종설이 담도폐쇄증 진단에 도움이 되길 바란다.

• Archives of Plastic Surgery
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• 제36권1호
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• pp.109-112
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• 2009

Purpose: Squamous cell carcinoma(SCC) of the lower lip is the most common malignant tumor comprising 90% of all lip SCC. The typical picture of SCC of the lower lip is of an ulcerated lesion with raised margins. Surgery is the treatment of choice for SCC of lower lip. Depending on the location and size of the tumor, different types of flaps are used. We used new method - 'both buccal mucosa transposition flap' for the reconstruction of the near total mucosal defect of the lower lip. Methods: This 67 - year - old men presented with the crusted $1cm{\times}1cm$ sized ulceration of the lower lip that was arised 30 years ago. There were no size and color change, except the bleeding and ulceration. At first, We diagnosed the SCC through the incisinal biopsy. Then We performed the wide excision of the tumor and reconstruction of the lower lip. After the excision of the whole tumor, the defect was measured at $8cm{\times}3.5cm$. We designed the buccal mucosa transposition flap taking care to avoid the parotid duct. The flap was made in a triangular shape for the reconstruction of defected lower lip. The donor site defect can be sutured primarily. Results: A patient in this study had no postoperative complications such as necrosis, dehiscence, infection of the flap or donor site. Reconstructed lower lip is relatively close to that of the natural lip; More satisfactory aesthetic and functional results can be obtained by using this technique rather than other techniques. Conclusion: 'Both buccal mucosa transposition flap' is reliable method for the reconstruction of the large lower lip mucosal defect. The operation is simple and performed in one stage, with no postoperative complications. This technique can offer consistently good functional and esthetic outcomes after reconstruction of lower lip mucosal defect.