• 한국해양환경ㆍ에너지학회지
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• 제11권4호
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• pp.227-231
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• 2008

본 연구에서는 연안사질 조간대에 표착된 기름의 방제를 위한 화학적 방제법의 적용 가능성을 파악하기 위해서 사질 조간대에서 유처리분산제의 살포에 의한 해수침투량의 변화 및 표착유의 거동을 검토하는 것을 목적으로 하여, 모의 조간대 실험장치를 이용하여 실험을 실시하였다. 파도에너지가 비교적 작은 사질 조간대에서 표착된 원유에 의해서 해수의 침투량이 감소되었으나, 분산제를 살포함으로 인해 해수침투량이 약 30% 증가되는 것을 알 수 있었다. 사질 조간대에 표착한 원유는 토양표층 2 cm부분에서 가장 농도가 높은 경향을 나타내었으며, 유화분산제를 살포하였을 경우 침투된 기름이 작은 입자로 분산되어 토양중으로 분산되었다. 따라서 표착된 원유에 분산제를 살포함으로 인해 저서생물의 생존에 필수적인 용존산소, 영양염, 유기물 등의 공급이 회복되어 저서생물에게 생존에 긍정적인 영향을 미칠 것으로 판단된다. 또한 표착된 기름에 유처리분산제를 살포함으로 인해 표착된 기름이 작은 유적으로 분산되어 비 표면적의 증대로 인한 기름분해 미생물의 분해가 촉진되어 표착유의 처리에 효과적일 것으로 사료된다.

• Journal of Chest Surgery
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• 제32권2호
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• pp.164-170
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• 1999

배경: 미만성 침윤성 폐질환의 확진을 위해 많은 환자들에게 폐생검이 시행되고 있다. 개흉 폐생검에서의 작은 절개로 얻을 수 있는 제한된 시야와는 달리, 흉강경을 통한 폐생검은거의 전 폐실질을 관찰한 후 생검할 수 있는 장점과 전통적인 개흉으로 생길 수 있는 유병률을 감소시킬 수 있다는 장점을 가지고 있다. 본 연구에서는 미만성 침윤성 폐질환의 진단에 있어, 흉강경 폐생검(TLB)과 개흉 폐생검(OLB)을 효율성과 안전성의 측면에서 비교하였다. 대상 및 방법: 1993년 3월부터 1997년 8월까지 81명의 환자에게 폐생검을 시행하였으며, 이 중 51명에게 기존의 개흉 폐생검을, 30명에게는 비디오 흉강경 폐생검을 시행하였다. 결과:수술 시간은 TLB에서 63분, OLB에서 79분이었고(p=0.04), 생검 조직 절편의 크기(TLB 7.8 cm3, OLB 6.9 cm3 : p=0.72)와 진단률(TLB 100%, OLB 96%)은 두 군간의 차이가 없었다. 술후 재원 일수는 TLB에서 OLB보다 유의하게 짧았고(TLB 13일, OLB 22일 : p=0.01), 흉관 거치일, 진통제 투여 횟수는 차이가 없었으나 진통제 투여 기간은 TLB에서 유의하게 짧았다(TLB 2.5일, OLB 5.2일, p=0.05). 합병증은 TLB에서 2례(6.67%), OLB에서 4례(7.84%)가 있었으며, 두 군 모두에서 수술로 인한 사망례는 없었다. 결론: 흉강경 폐생검이 미만성 침윤성 폐질환의 진단에 있어서, 기존의 개흉 폐생검의 훌륭한 대안이 될 수 있다고 생각한다.

• 해양환경안전학회지
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• 제25권6호
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• pp.795-801
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• 2019

층류 경계층 내 반구에 의해 유기되는 말굽와류를 흡입 제어했을 때 후류영역에서의 마찰저항 변화를 측정하였다. 이를 위해 회류수조에서 유동가시화를 실시하여 최적의 자유유속, 반구 크기 및 흡입제어 구멍 크기를 결정하였고, 반구 후류영역에 설치된 평판과 연결된 동력계로 표면 마찰저항 감소를 측정하는 실험을 수행하였다. 평판에 설치된 반구 전방에는 유입 유동에 의해 반구를 감싸는 말굽와류가 생성되며 그 주위 와도 방향에 의해 후류영역으로는 빠른 유속의 유동이 유입되어 머리핀 와류 생성을 촉진시킨다. 따라서 반구 전방에 생성되는 말굽와류 세기를 흡입 제어에 의해 약화시킴으로써 반구 좌우측으로 길게 형성된 유속방향 와류가 후류영역으로 공급하는 에너지는 감소하게 된다. 즉, 반구 전방의 말굽와류를 제어함으로써 후류영역으로부터 생성되는 헤어핀 와류 발생 주파수가 줄어 들게 된다. 염료 주입을 이용한 유동 가시화 영상을 해석한 결과로 머리핀 와류의 발생 빈도가 흡입제어에 의해 36.4 % 감소되었고, 후류영역에서 측정된 표면 마찰저항은 2.3 % 감소되는 것으로 나타났다.

• Journal of Gastric Cancer
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• 제18권2호
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• pp.134-141
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• 2018

Purpose: Postoperative pancreatic fistula is a serious and fatal complication of gastrectomy for gastric cancer. Blunt trauma to the parenchyma of the pancreas can result from an assistant's forceps compressing and retracting the pancreas, which in turn may result in pancreatic juice leakage. However, no published studies have focused on blunt trauma to the pancreas during laparoscopic surgery. Our aim was to investigate the relationship between compression of the pancreas and pancreatic juice leakage in a swine model. Materials and Methods: Three female pigs were used in this study. The pancreas was gently compressed dorsally for 15 minutes laparoscopically with gauze grasped with forceps. Pancreatic juice leakage was visualized by fluorescence imaging after topical administration of chymotrypsin-activatable fluorophore in real time. Amylase concentrations in ascites collected at specified times was measured. In addition, pancreatic tissue was fixed with formalin, and the histology of the compressed sites was evaluated. Results: Fluorescence imaging enabled visualization of pancreatic juice leaking into ascites around the pancreas. Median concentrations of pancreatic amylase in ascites increased from 46 U/L preoperatively to 12,509 U/L 4 hours after compression. Histological examination of tissues obtained 4 hours after compression revealed necrotic pancreatic acinar cells extending from the surface to deep within the pancreas and infiltration of inflammatory cells. Conclusions: Pancreatic compression by the assistant's forceps can contribute to pancreatic juice leakage. These findings will help to improve the procedure for lymph node dissection around the pancreas during laparoscopic gastrectomy.

• 대한조선학회논문집
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• 제50권5호
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• pp.324-333
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• 2013

Recently, rudder erosion due to cavitation has been frequently reported on a semi-spade rudder of a high-speed large ship. This problem raises economic and safety issues when operating ships. The semi-spade rudders have a gap between the horn/pintle and the movable wing part. Due to this gap, a discontinuous surface, cavitation phenomenon arises and results in unresolved problems such as rudder erosion. In this study, we made a rudder model for 2-D experiments using the NACA0020 and also manufactured gap flow blocking devices to insert to the gap of the model. In order to study the gap flow characteristics at various rudder deflection angles($5^{\circ}$, $10^{\circ}$, $35^{\circ}$) and the effect of the gap flow blocking devices, we carried out the velocity measurements using PIV(Particle Image Velocimetry) techniques and cavitation observation using high speed camera in Seoul National University cavitation tunnel. To observe the gap cavitation on a semi-spade rudder, we slowly lowered the inside pressure of the cavitation tunnel until cavitation occurred near the gap and then captured it using high-speed camera with the frame rate of 4300 fps(frame per second). During this procedure, cavitation numbers and the generated location were recorded, and these experimental data were compared with CFD results calculated by commercial code, Fluent. When we use gap flow blocking device to block the gap, it showed a different flow character compared with previous observation without the device. With the device blocking the gap, the flow velocity increases on the suction side, while it decreases on the pressure side. Therefore, we can conclude that the gap flow blocking device results in a high lift-force effect. And we can also observe that the cavitation inception is delayed.

• Archives of Plastic Surgery
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• 제34권4호
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• pp.432-435
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• 2007

Purpose: The jejunal free flap has the shorter ischemic time than other flap and requires a laparotomy to harvest it. As the evaluation of the perfusion the buried flap is very important, the perfusion of the buried jejunal free flap requires monitoring for its salvage. We tried to improve the monitoring flap method in the jejunal free flap and examined its usefulness. Methods: From March 2002 to March 2006, the monitoring flap method was applied to 4 cases in 8 jejunal free flaps for the pharyngeal and cervical esophageal reconstructions. The distal part of the jejunal flap was exposed without suture fixation through cervical wound for monitoring its perfusion. The status of perfusion was judged by the color change of jejunal mucosa and mesentery. If necessary, pin prick test was performed. Doppler sonography was applied to mesenteric pedicle of the monitoring flap in case of suspicious abnormal circulation. Results: The monitoring flap shows no change in 3 cases, but the congestion happened in one case at the 12 hours after the operation. This congestion was caused by the twisting or kinking of the mesenteric pedicle of the monitoring flap. So, we fixed up the monitoring flap close to adjacent cervical skin for prevention of rotation. Finally, the main part of transferred jejunal flap was intact. Conclusion: The success of a jejunal free flap depends on close postoperative monitoring and early detection of vascular compromise. So, various monitoring methods have been tried, for instance, direct visualization using a fiberoptic pharyngoscope, through a Silastic window placed in the neck flap, or external surface monitoring with an Doppler sonography, use of a buried monitoring probe. But, all of the above have their own shortcomings of simplicity, non-invasiveness, reliability and etc. In our experience, monitoring flap can be a accurate and reliable method.

• 한국임상수의학회지
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• 제24권3호
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• pp.315-319
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• 2007

1년령, 암컷, 15 kg의 잡종견에서 위내시경을 이용한 경위장관 담낭절제술을 최소한의 복강경 도움아래에서 성공적으로 수행하였다. 내시경용 바늘 절개도를 이용하여 배쪽 유문부에서 위절개를 실시하였다. 위절개부를 통하여 내시경을 복강내로 진입한 다음 뒤쪽으로 돌려서 담낭쪽 시야를 확보하였다. 술야의 확보를 위해 복강경용 겸자를 이용하여 담낭의 바닥부위를 부드럽게 들어올렸다. 담낭관과 동맥을 내시경용 endoclip을 이용하여 3중 결찰하였다. 담낭관과 동맥을 절단한 후 내시경용 소작겸자와 바늘 절개도를 이용하여 담낭을 간으로부터 분리하였다. 분리된 담낭은 내시경을 이용해 입을 통하여 제거하고, 위절개부위는 내시경용 endoclip을 이용하여 봉합하였다. 술후 3일째 방사선검사 및 혈청화학검사를 통해 위봉합부위의 천공이 없음과 담즙의 누출이 없음을 확인하였다. 술후 16일째 위내시경과 복강경 검사를 실시하였다. 위내시경검사 결과 봉합부위가 완전히 유합 되었음을 확인하였고 복강경 검사를 통해 담낭절제부위와 위절개부의 장막에 대망막이 유착되어있음을 확인하였다. 본 연구는 개에서 자연개구부 내시경수술(NOTES)을 이용한 담낭절제술의 최초 보고로써 새로운 방법에 의한 담낭절제술에 대한 가능성을 제시한다.

• 한국가스학회지
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• 제2권1호
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• pp.28-39
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• 1998

본 연구에서는 $20\%$ 천장개구부가 있는 정사각형 밀폐공간내의 순수자연대류와 자연대류 -복사가 고려된 복합열전달을 순차해석과 실험을 통하여 비교 분석하였다. 수치해석은 순수자연대류에 대하여 SIMPLE 알고리즘을 사용하였고, 복사열전달에 대해서는 S-N 구분 종좌표법을 이용하였으며 난류유동의 경계조건은 벽함수를 적용하였다. 실험은 수치해석의 결과와 비교하기 위하여 동일한 조건에 대하여 수행되었다. 그 결과 순수자연대류와 복합열전달의 유동장, 온도장의 형상은 유사한 유선함수를 보이고 있으며, 유동가시화를 통한 실험결과와 잘 일치하고 있음을 보여준다. 수치해석과 실험의 온도분포를 비교한 결과 평균 $8.5\%$의 오차를 보였다.

• Journal of Gastric Cancer
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• 제21권2호
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• pp.191-202
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• 2021

Purpose: A near-infrared (NIR) fluorescence imaging is a promising tool for cancer-specific image guided surgery. Human epidermal receptor 2 (HER2) is one of the candidate markers for gastric cancer. In this study, we aimed to synthesize HER2-specific NIR fluorescence probes and evaluate their applicability in cancer-specific image-guided surgeries using an animal model. Materials and Methods: An NIR dye emitting light at 800 nm (IRDye800CW; Li-COR) was conjugated to trastuzumab and an HER2-specific affibody using a click mechanism. HER2 affinity was assessed using surface plasmon resonance. Gastric cancer cell lines (NCI-N87 and SNU-601) were subcutaneously implanted into female BALB/c nu (6-8 weeks old) mice. After intravenous injection of the probes, biodistribution and fluorescence signal intensity were measured using Lumina II (Perkin Elmer) and a laparoscopic NIR camera (InTheSmart). Results: Trastuzumab-IRDye800CW exhibited high affinity for HER2 (K_D=2.093(3) pM). Fluorescence signals in the liver and spleen were the highest at 24 hours post injection, while the signal in HER2-positive tumor cells increased until 72 hours, as assessed using the Lumina II system. The signal corresponding to the tumor was visually identified and clearly differentiated from the liver after 72 hours using a laparoscopic NIR camera. Affibody-IRDye800CW also exhibited high affinity for HER2 (K_D=4.71 nM); however, the signal was not identified in the tumor, probably owing to rapid renal clearance. Conclusions: Trastuzumab-IRDye800CW may be used as a potential NIR probe that can be injected 2-3 days before surgery to obtain high HER2-specific signal and contrast. Affibody-based NIR probes may require modifications to enhance mobilization to the tumor site.

• Wind and Structures
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• 제35권1호
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• pp.1-20
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• 2022

This research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0≤G/D≤1.5 at Reynolds number of 5 × 10³. Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (𝜃) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the -ring exhibits remarkable flow control at 𝜃=50° and 𝜃=55° before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50° exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.