• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 춘계학술발표회
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• pp.169-174
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• 2007

부표시스템 침수체의 주요형상인 원형실린더에 제어봉을 부착하여 2차원 단면의 유동특성에 대해서 수치해석을 수행하였다. 유속을 0.1m/s에서 0.5m/s로 변화시키면서 부표시스템 주위의 유동현상을 파악하고 부표시스템의 효과적인 유통제어를 위해 실린더 (D=50mm)에 제어봉의 직경을 0.1D 에서 O.5D 까지 부착하여 조류에 의한 영향을 조사하였다. 유동장내의 속도분포는 PIV계측기법 중 2 프레림 입자추적법을 사용하여 수치해석의 정도를 높이고자 0.3m/s에서 비교 평가하였다. 실린더 주위의 압력분포는 0.2D 의 제어봉을 부착하였을 경우, 유속의 변화에 관계없이 가장 양호한 경향을 보이는 것을 알 수 있었다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.23-26
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• 2002

The phase-averaged velocity fields of 3 dimensional turbulent wake behind a marine propeller measured by 2D PIV and stereoscopic PIV(SPIV) were compared directly. In-plane velocity fields obtained from the consecutive particle images captured by one camera in 2D PIV have perspective errors due to out-of-plane motion. However, the perspective errors can be removed by measuring three component velocity fields using SPIV method with two cameras. It is also necessary to measure three components velocity fields for the investigation of complicated near-wake behind the propeller for the suitable propeller design. 400 instantaneous velocity fields were measured for each of four different blade phases of $0^{\circ},\;18^{\circ},\;36^{\circ}C\;and\;54^{\circ}$. They were ensemble averaged to investigate the spatial evolution of the propeller wake in the downstream region. The phase-averaged velocity fields show the viscous wake developed along the blade surfaces and tip vortices were formed periodically. The perspective errors caused by the out-of-plane motion was estimated by the comparison of 2D PIV and SPIV results. The difference in the axial mean velocity fields measured by both techniques are nearly proportional to the mean out-of-plane velocity component which has large values in the regions of the tip and trailing vortices. The axial turbulence intensity measured by 2D PIV was overestimated since the out-of-plane velocity fluctuations influence the in-plane velocity vectors and increase the in-plane turbulence intensities.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제9권1호
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• pp.103-107
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• 2006

Belsey Mark IV 위바닥주름술은 이전의 역류 방지 수술이 실패하여 재수술을 해야 하는 경우 혹은 식도 열공 탈장이 오래 되어 유착이 있는 경우에 적응증이 된다. 본 증례는 식도 열공 탈장과 GERD로 진단되어 Nissen 위바닥 주름술을 시행하였으나 실패하였고 재수술을 시도하였지만 수술 부위의 유착이 심하여 수술적 접근이 불가능하였다. 저자들은 흉강을 통하여 Belsey Mark IV 위바닥주름술을 실시하였고, 수술 후 증상과 영양상태의 호전을 보인 1예를 문헌 고찰과 함께 보고하는 바이다.

• Journal of Korean Neurosurgical Society
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• 제47권3호
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• pp.185-190
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• 2010

Objective : The aneurysm remnants rate was evaluated via three-dimensional digital subtraction angiography (3D-DSA) in the postoperative evaluation of clipped aneurysms. Methods : Data on surgically clipped aneurysms of anterior circulation obtained via postoperative 3D-DSA from February 2007 to March 2009 were gathered. The results of the postoperative 3D-DSA and of two-dimensional digital subtraction angiography (2D-DSA) for the detection of aneurysm remnants were compared, and an investigation was performed as to why 2D-DSA had missed some aneurysm remnants that were detected in the 3D-DSA. Various surgical factors that revealed aneurysm remnants in the 3D-DSA were also evaluated. Results : A total of 39 neck remnants of 202 clipped aneurysms (19.3%) were confirmed in 3D-DSA, and these were classified according to Sindou's classification of aneurysm remnants. Patients with only a neck remnant found in the 3D-DSA represented 17.3% (35/202 aneurysms) of the whole series, and those with a residuum of neck plus sac found in the 3D-DSA represented 1.9% (4/202 aneurysms). The causes of aneurysm remnants were no full visualization (14/39, 35.9%), parent and perforator artery protection (10/39, 25.6%), clip design problems (8/39, 20.5%), and broadnecked aneurysm (7/39, 17.9%). Conclusion : Patients with ${\leq}2$mm aneurysm remnants showed an increased risk of undetectable aneurysm remnants in the 2D-DSA. The most frequent location of the missed aneurysm in 2D-DSA was the anterior communicating artery. 3D-DSA showed more aneurysm remnants than what is indicated in the existing literature, the 2D-DSA.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.61-67
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• 2011

The confocal laser scanning microscopy and two-photon microscopy was implemented based on a single laser source and an objective lens. We imaged and compared the morphology of identical sites of ex vivo human skin using both microscopes. The back-scattering emission from the sample provided the contrast for the confocal microscopy. The intrinsic autofluorescence and the second harmonic generation were used as the luminescence source for the two-photon microscopy. The wavelength of the Ti:Sapphire laser was tuned at 710 nm, which corresponds to the excitation peak of NADH and FAD in skin tissue. The various cell layers in the epidermis and the papillary dermis were clearly distinguished by both imaging modalities. The two-photon microscopy more clearly visualized the intercellular region and the nucleus of the cell compared to the confocal microscopy. The fibrous structures in the dermis were more clearly resolved by the confocal microscopy. Numerous cells in papillary dermal layer, as deep as $100\;{\mu}m$, were observed in both CLSM and two-photon microscopy. While most previous studies focused on fibrous structure imaging (collagen and elastin fiber) in the dermis, we demonstrated that the combined imaging with the CLSM and two-photon microscopy can be applied for the non-invasive study of the population, distribution and metabolism of papillary dermal cells in skin.

• Journal of Gastric Cancer
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• 제19권1호
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• pp.62-71
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• 2019

Purpose: The laparoscopic transhiatal approach (LA) for adenocarcinoma of the esophagogastric junction (AEJ) is advantageous since it allows better visualization of the surgical field than the open approach (OA). We compared the surgical outcomes of the 2 approaches. Materials and Methods: We analyzed 108 patients with AEJ who underwent transhiatal distal esophagectomy and gastrectomy with curative intent between 2003 and 2015. Surgical outcomes were reviewed using electronic medical records. Results: The LA and OA were performed in 37 and 71 patients, respectively. Compared to the OA, the LA was associated with significantly shorter duration of postoperative hospital stay (9 vs. 11 days, P=0.001), shorter proximal resection margins (3 vs. 7 mm, P=0.004), and extended operative times (240 vs. 191 min, P=0.001). No significant difference was observed between the LA and OA for intraoperative blood loss (100 vs. 100 mL, P=0.392) or surgical morbidity rate ($grade{\geq}II$) for complications (8.1% vs. 23.9%, P=0.080). Two cases of anastomotic leakage occurred in the OA group. The number of harvested lymph nodes was not significantly different between the LA and OA groups (54 vs. 51, P=0.889). The 5-year overall and 3-year relapse-free survival rates were 81.8% and 50.7% (P=0.024) and 77.3% and 46.4% (P=0.009) for the LA and OA groups, respectively. Multivariable analyses revealed no independent factors associated with overall survival. Conclusions: The LA is feasible and safe with short- and long-term oncologic outcomes similar to those of the OA.

• Asian Pacific Journal of Cancer Prevention
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• 제17권2호
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• pp.719-722
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• 2016

Background: Cholangiocarcinoma (CCA) is a serious health problem in Thailand, particularly in northeastern and northern regions, but epidemiological studies are scarce and the spatial distribution of CCA remains to be determined. A database for the population at risk is required for monitoring, surveillance and organization of home health care. This study aim was to geo-visually display the distribution of CCA in northeast Thailand, using a geographic information system and Google Earth. Materials and Methods: A cross-sectional survey was carried out in 9 sub-districts and 133 villages in Chum Phuang district, Nakhon Ratchasima province during June and October 2015. Data on demography, and the population at risk for CCA were combined with the points of villages, sub-district boundaries, district boundaries, and points of hospitals in districts, then fed into a geographical information system. After the conversion, all of the data were imported into Google Earth for geo-visualization. Results: A total of 11,960 from 83,096 population were included in this study. Females and male were 52.5%, and 47.8%, the age group 41-50 years old 33.3%. Individual risk for CCA was identifed and classified by using the Korat CCA verbal screening test as low (92.8%), followed by high risk (6.74%), and no (0.49%), respectively. Gender ($X^2$-test=1143.63, p-value= 0.001), age group ($X^2$-test==211.36, p-value=0.0001), and sub-district ($X^2$-test=1471.858, p-value=0.0001) were significantly associated with CCA risk. Spatial distribution of the population at risk for CCA in Chum Phuang district was viewed with Google Earth. Geo-visual display followed Layer 1: District, Layer 2: Sub-district, Layer 3: Number of low risk in village, Layer 4: Number of high risk in village, and Layer 5: Hospital in Chum Phuang District and their related catchment areas. Conclusions: We present the first risk geo-visual display of CCA in this rural community, which is important for spatial targeting of control efforts. Risk appears to be strongly associated with gender, age group, and sub-district. Therefor, spatial distribution is suitable for the use in the further monitoring, surveillance, and home health care for CCA.

• 한국의학물리학회지:의학물리
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• 제9권4호
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• pp.207-215
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• 1998

방사선의 측정방법으로 현재까지 여러 방법들이 쓰여져 왔다. 여기에는 필름을 이용하는 방법, TLD를 이용하는 방법, 전리함(ion chamber)을 이용하는 방법 등이 대체로 가장 많이 쓰여지는 방법이다. 그러나 본 연구에서는 새로운 방사선측정 방법이 시도되었다. 고분자 젤과 핵자기공명영상 (MRI)을 이용한 방법이 그 것이다. 본 연구의 목적은 방사선 측정을 위한 고분자 젤을 합성하고 합성된 젤을 사용하여 젤의 방사선 흡수선량과의 관계를 MRI 영상으로부터 구해서, 이 결과를 근접치료에 쓰이는 seed 선원의 선량분포를 측정하여 가시화 시키는데 있다. 이를 위해 지름 12 cm 원통형 팬텀에 젤을 합성하고, 이 젤을 뇌정위 방사선수술에 쓰이는 30 mm 콜리메이터를 이용하여 여러 단계의 선량을 젤에 조사하였다. 이렇게 조사된 젤은 MRI 을 촬영하였고 이렇게 촬영된 MRI 영상으로부터 젤팬텀의 각 위치의 횡이완시간 (T$_2$ time)을 영상분석 소프트웨어를 이용하여 계산하였다. 그 결과 젤의 홉수선량과 횡이완시간과는 17 Gy 근처까지는 거의 반비례 ($R^2$=0.993)하는 것을 알 수 있었으며, 이 보다 높은 흡수선량에 대해서는 또 다른 관계가 있음을 알 수 있었다. 또 이것을 이용하여 HDR afterloading system 의 Ir-192 seed 선원에 의한 선량분포와 2 mCi Ir-192 seed 선원에 의한 선량분포를 측정하였다. 그리고 이 것을 각각 치료계획컴퓨터에 의한 선량분포곡선과 비교하였다. 본 연구의 결과로는 고분자 젤을 이용한 방사선의 측정방법을 시도하여 홉수선량과 젤의 특성과의 관계를 밝혔으며, 실제로 그접치료에 쓰이는 seed 선원에 의한 선량분포 곡선을 얻는데 적용하였다.

• 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.

• 한국과학교육학회지
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• 제34권6호
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• pp.601-611
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• 2014

본 연구는 과학적 사실, 현상, 첨단 과학 소식, 과학적 이슈 등을 독자들에게 알기 쉽게 제공하기 위한 표현수단으로 인포그래픽을 활용하고 있는 과학동아를 대상으로 인포그래픽의 시계열적 특성을 분석하여 과학 교육에 인포그래픽의 활용 가능성을 짐작하는데 그 목적이 있다. 과학동아의 인포그래픽을 분석하기 위해 스토리텔링 유형, 시지각 특성, 프레임워크의 수준을 차원으로 하는 3차원 구성틀을 개발하였다. 이 구성틀에 의해 분석한 결과 과학동아는 1986년부터 2014년까지 이미지를 강조한 과학 기사를 발행하였으며 특히 2008년 이후부터는 인포그래픽이 포함된 기사가 유의미하게 증가하는 것으로 나타나 2008년을 인포그래픽 특성 변화의 중요 기준이 되는 $T_c$(Critical time Point)로 설정하였다. 2008년 이후의 과학 기사의 인포그래픽은 위치, 시간, 수치, 관계, 기능, 과정 기반형의 6가지 스토리텔링 유형이 2008년 이전 보다 다양하게 분포하였고, 게슈탈트 시지각 이론의 시지각 특성(근접성, 유사성, 연속성, 폐쇄성)도 2008년 이후에 더욱 많이 적용한 것을 알 수 있었다. 마지막으로 프레임워크의 수준은 위치, 시간, 수치, 과정 기반 인포그래픽은 전체 범위 수준이 주를 이루며 시간의 흐름에 변화가 없는 반면, 기능과 관계 기반 인포그래픽에서는 프레임워크의 수준이 2008년을 기준으로 변화가 나타났다. 인포그래픽 관점에서 과학동아를 분석한 결과를 통해 인포그래픽의 특성이 어떻게 변화되어 왔는지 분석하여 과학교육에서 인포그래픽을 적용할 때 기초적인 기준을 제공할 수 있을 것으로 사료된다.