• Archives of Plastic Surgery
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• 제37권6호
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• pp.769-774
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• 2010

Purpose: As the soft tissue defect around the knee is difficult to reconstruct, local flap or free flap is used. Distally based anterolateral thigh pedicled flap introduced by Zhang uses sufficient reverse flow supplied from the vascular network around the knee. We report successful reconstruction of defect around knee by this method. Methods: Four patients with skin & soft tissue defect around knee have been treated for reconstruction using the distally based anterolateral thigh pedicled flap. First, the doppler was used to check the perforator flap of the descending branch of the lateral circumflex femoral artery and to draw and dissect the perforator flap as much as needed. After the dissection, the proximal of the descending branch was clamped and checked for sufficient supply of blood flow from the reverse flow and then ligated. It was dissected along the descending branch and in order to prevent damage to the joined parts of the descending branch and the lateral superior geniculate artery, a more careful ligation was done starting from 10 cm superior to the knee. The defect was reconstructed after securing enough vascular pedicle to cover all the damaged parts. Results: Not all patients suffered from flap necrosis. In case of the patient with chronic osteomyelitis, slight venous congestion was observed right after the surgery but it disappeared the following day. All three patients had no occurences of additional complications. Conclusion: Distally based anterolateral thigh pedicled flap was enough to provide large flap for knee reconstruction. It had sufficient blood flow and vascular pedicle. It also had taken short operation time compared to the free flap operation. The distally based anterolateral thigh pedicled flap used by the authors is a very useful way of reconstructing the area around knee.

• Archives of Plastic Surgery
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• 제49권3호
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• pp.444-447
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• 2022

Reconstruction of soft tissue defects around the knee is challenging, and the most common solution is to use various locoregional flaps or, in some difficult cases, a free flap. The distally based anterolateral thigh (dALT) flap is a commonly used flap that relies on reverse blood flow from the descending branch of the lateral circumflex femoral artery (d-LCFA). Here, we present the case of an anteromedial knee reconstruction using a dALT flap after resection of a pleomorphic undifferentiated sarcoma. The tumor resection resulted in a 14 × 7 cm defect, and a dALT flap, measuring 20 × 8 cm was elevated. During the surgery, we found a robust oblique branch of the LCFA (o-LCFA) sending off two sizable perforators to the anterolateral thigh region, whereas the d-LCFA was relatively small with no usable perforators. Therefore, we harvested a dALT flap relying on reverse flow from the o-LCFA. The patient's postoperative course was uneventful, and the flap survived without complications. This report demonstrates that reverse flow from the o-LCFA may be an alternative to nourish a dALT flap in cases where the d-LCFA is hypoplastic or suitable perforators from the d-LCFA are unavailable.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.125-125
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• 2023

Estuarine dams are dams constructed in estuaries for reasons such as securing freshwater resources, controlling water levels, and hydroelectric power generation. These estuarine dams alter the flow of freshwater to the coastal ocean and the tidal properties of the estuaries which has implications for the estuaries' circulation and sediment transport. A previous study has analyzed the effect of estuarine dams on 1D (along-channel) circulation and sediment transport. However, the effect of estuarine dams on the transverse variability of along-channel and across-channel circulation and sediment transport has not been studied and is not known. In this study, a coupled hydrodynamic-sediment dynamic numerical model (COAWST) was used to analyze the transverse variability of along-channel and across-channel flow and sediment transport in estuaries with estuarine dams. The estuarine dam was found to change the 3D structure of circulation and sediment transport, and the result was found to depend on the estuarine type (i.e., strongly stratified (SS) or well-mixed (WM) estuary). The SS estuary had inflow in the channel and outflow over the shoals, consistent with estuarine circulation. Longer discharge interval reduced the estuarine circulation. The WM estuary had inflow over the shoals and outflow in the channel, consistent with tide-induced circulation. As the estuarine dam was located nearer to the estuary mouth, the tide-induced circulation was reduced and replaced with estuarine circulation. The lateral circualtion was the greatest in the tide-dominated estuaries. It was reduced and changed direction due to differential advection change as the dam was located nearer the mouth. Overall, the WM estuary transverse flow structure changed the most. Lateral sediment flux was important in all estuaries, particularly for transporting sediments to the tidal flats.

• 대한기계학회논문집B
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• 제22권4호
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• pp.530-541
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• 1998

Heat transfer augmentation in a rib-roughened duct is affected by the rib configurations, such as rib height, angle of attack, shape, rib to rib pitch, and aspect ratio of a duct. These have been the main subjects in studying the average heat transfer and the friction loss of the fully developed flow. Investigating distributions of local heat transfer coefficients and flow patterns in a duct with the rib turbulators is necessary to find the characteristics of heat transfer augmentation and to decide the optimal configurations of ribs. In the present study the numerical analyses and the mass transfer experiments are performed to understand the flow through a rib roughened duct and the heat transfer characteristics with various angles of attack of ribs. A pair of counter-rotating secondary flow in a duct has a main effect on the lateral distributions of local mass transfer coefficients. Downwash of the rotating secondary flow, reattachment of main flow between ribs and the vortices near ribs and wall enhanced the mass transfer locally up to 8 times of that in case of the duct without ribs.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2491-2498
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• 2020

The paper concentrates on an experimental study of the pressure drop in double-layered packed beds formed by glass spheres, having the configuration of horizontal and vertical stratification. Both single-phase and two-phase flow tests are performed. The pressure drop during the test is recorded and the measured data are compared with those of homogeneous beds consisting of mono-size particles. The results show that for the horizontally stratified bed with fine particles atop coarse particles, the pressure drop in top layer is found higher than those of homogenous bed consisting of the same smaller size particles, while the measured pressure drop of bottom part is similar with those of similar homogenous bed. But for the homologous bed with upside-down structure, the stratification has little or no effect on the pressure drop of the horizontally stratified bed, and the pressure drop of each layer is almost same as that of homogeneous bed packed with corresponding spheres. Additionally, in vertically stratified bed, the pressure drops on the left and right side is almost equal and between those in homogeneous beds. It is speculated that vertically stratified structure may lead to lateral flow which redistributes the flow rate in different parts of packed bed.

• 한국가구학회지
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• 제18권4호
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• pp.307-311
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• 2007

An experiment was conducted to know the essential oil penetration depth in radial and longitudinal direction of Prunus sargentii. Oil penetration depth was found greater than radial flow depth. Vessel conducted oil more than wood fiber. In radial direction, body ray parenchyma was found more permeable than marginal ray parenchyma and it was about 138% times higher. Furthermore penetration depth of oil in intercellular space was greater than ray parenchyma and it was about 250% higher than ray parenchymas. Initial flow speed was found high and then it gradually decreased.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.77-83
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• 2007

This paper presents numerical and experimental works for simultaneous pumping and mixing small liquid using asymmetric microelectrode arrays, based on AC electroosmotic flows. To this end, four arrangements of electrode pairs were considered with diagonal/herringbone shapes. Numerical simulations were made of three-dimensional geometries by using the linear theory. The results indicated that the helical flow motions induced by the electrode arrays play a significant role in the mixing enhancement. The pumping performance was influenced by the slip velocity at the center region of the channel compared to that near the side walls. To validate the numerical predictions, the microfluidic devices were made through MEMS. The flow rate was obtained by using micro PIV, increasing the applied frequency. The electrolyte was potassium chloride solution. The flow patterns above electrodes were visualized to see lateral flow for mixing. The experimental results showed good agreements with the numerical predictions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2670-2675
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• 2008

We introduce a new type of surface microscope using hydrodynamic phenomena. The fluid flow through the opening of the pipette probe is blocked at short distances between the probe and the surface, thus increasing the pressure loss. Therefore, a scanning flow impedance microscope (SFIM) can image the surface topology by scanning the probe with measuring the pressure loss. The SFIM can display the topology regardless of surface hardness, surface electrical conductivity, and surrounding fluid. The present letter contains the first experimental results on surface topography obtained with this novel microscope. The preliminary results in air demonstrate the lateral resolution of the SFIM is very close to the inner diameter of the probe.

• 대한환경공학회지
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• 제27권12호
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• pp.1305-1310
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• 2005

하상여과에서 집수관의 최적 설계를 위한 방편으로 여러 개의 모래통을 이용하여 모형 집수관 실험을 수행하였다. 집수정의 수위, 집수관의 직경, 집수관의 길이, 그리고 모래의 투수계수를 변화시키면서 모형 집수관을 운영하였으며, 집수관 표면에서의 잔류 수두와 집수관 각 부위에서의 여과수 유입율, 그리고 집수정에서의 산출유량을 측정하였다. 실험결과 모래층에서의 저항에 비해 집수관에서의 저항이 작아서 집수관 표면에서의 잔류수두가 수평에 가까운 경우 효율적인 집수관임을 알 수 있었다. 집수관의 여과수 유입율은 집수정에 근접할수록 지수함수적으로 증가하였고, 집수관의 직경이 작을수록 그리고, 대수층의 투수계수가 클수록 이 지수함수의 기울기는 증가하였다. 집수관의 길이와 직경이 증가하면 산출유량은 증가하지만 그 한계생산성은 감소하였다. 효율적인 하상여과를 위해서는 집수관에서의 축방향 유속을 줄이는 것이 중요함을 알 수 있었으며, 본 연구의 조건에서는 이 유속이 1 m/sec를 넘을 경우 우물의 효율이 크게 감소함을 알 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.331-337
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• 2017

A simple strategy is proposed herein for attaining uniform current distribution in direct methanol fuel cells by varying the catalyst loading over the electrode. In order to use the same total catalyst amount for a serpentine flow field, three spatial variation types of catalyst loading were selected: enhancing the cathode catalyst loading (i) near the cathode outlet, (ii) near the cathode inlet, and (iii) near the lateral areas. These variations in catalyst loading are shown to improve the homogeneity of the current distribution, particularly at lower currents and lower air-flow rates. Among these three variations, increased loading near the lateral areas was shown to contribute most to achieving a homogenous current distribution. The mechanism underlying each catalyst loading variation method is different; very high catalyst-loading is shown to decrease the homogeneity of the distribution, which may be caused by water management in the thick catalyst layer thereof.