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서영우,목하균 한국방송공학회 2001 한국방송공학회 학술대회 Vol.1 No.1

병리, 기생충학 : 수도권 일대 집단 번식농장 사육견에서의 개심장사상충 감염실태

서영우,신성식,김종택 대한수의학회 2001 大韓獸醫學會誌 Vol.41 No.1

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경경정맥 간내문맥 정맥단락술에 사용한 비피막형 스텐트와 Expanded Polytetrafluoroethylene 피막형 스텐트의 개통률과 임상결과의 비교

서영우,원영철,황재철,강병성,권운정,신상훈,남미정,양지연,최성훈 대한영상의학회 2013 대한영상의학회지 Vol.69 No.2

Purpose: The purpose of this study is to compare shunt patency and clinical outcomes between bare stents and expanded polytetrafluoroethylene (ePTFE) covered stents in patients who had undergone transjugular intrahepatic portosystemic shunt (TIPS) creation. Materials and Methods: 43 consecutive patients with active gastroesophageal variceal bleeding who had undergone de novo TIPS creation were included in this study. For TIPS creation, bare stents were placed in twenty patients (Group 1) from January 2001 to December 2003, while ePTFE-covered stents were placed in twenty-three patients (Group 2) from January 2004 to December 2007. The primary and secondary patency rates of TIPS along with the clinical outcome were assessed, and a comparison was made between the two groups. Results: The technical success rate was 100%. Cumulative primary shunt patency rate in Group 1 was 78.5%, 55.8%, and 45.8% at 6, 12, and 24 months, respectively, and in Group 2, 91.1%, 86.0%, and 79.9%, respectively (p = 0.009). Cumulative secondary shunt patency rate in Group 1 was 86.3%, 70.7%, and 64.3%, respectively, and in Group 2, 91.1%, 91.1%, and 85.0%, respectively (p = 0.022). Conclusion: The use of ePTFE-covered stents particularly designed to spare the juxtacaval segment of the hepatic vein resulted in an improved patency of shunts compared to using bare stents. 목적: 위식도 정맥류 출혈 치료를 위한 transjugular intrahepatic portosystemic shunt (TIPS) 시술시, 간정맥-하대정맥 이행부 보존을 위해 사용된 expanded polytetrafluoroethylene (ePTFE) 피막형 스텐트와 비피막형 스텐트의 개통률을 비교하여 ePTFE 피막형 스텐트의 유용성을 알아보고자 한다. 대상과 방법: 위식도 정맥류 출혈을 치료하기 위해 de novo TIPS를 시행한 43명의 환자가 대상이며, 2001년 1월부터 2003년 12월까지 20명의 환자는 비피막형 스텐트를 사용하였고(Group 1), 2004년 1월부터 2007년 12월까지 23명의 환자는 스텐트 양측 끝에 2 cm의 비피막부가 있는 ePTFE 피막형 스텐트를 사용하였다(Group 2). 두 군 간의 일차 개통률, 이차 개통률 및 임상결과를 비교하였다. 결과: 평균 추적관찰 기간은 985일이었으며, 모든 환자에서 기술적 성공을 하였다. 30일 내 재출혈은 Group 1에서 3명, Group 2에서 2명이 있었으나 통계적 차이는 없었다. 일차 개통률은 Group 1에서 78.5%, 55.8%, 45.8%(6개월, 12개월, 24개월)였고, Group 2에서 91.1%, 86.0%, 79.9%로 통계적으로 유의한 차이가 있었으며(p = 0.009), 이차 개통률은 Group 1에서 83.6%, 70.7%, 64.3%였고, Group 2에서 91.1%, 91.1%, 85.0%로 통계적으로 유의한 차이가 있었다(p = 0.022). 결론: 간정맥-하대정맥 이행부를 보존하기 위하여 제작된 ePTFE 피막형 스텐트는 비피막형 스텐트와 비교하여 우수한 개통률을 보여주며, 위식도 정맥류 출혈의 치료를 위한 TIPS 시술에 효과적이며 유용하다.

Effect of Ambient Light Exposure on Ocular Fatigue during Sleep

서영우,나건후,안소은,오재령 대한의학회 2018 Journal of Korean medical science Vol.33 No.38

Background: To investigate the influence of nocturnal ambient light on visual function and ocular fatigue. Methods: Sixty healthy subjects (30 men and 30 women) aged 19 through 29 years with no history of ocular disease were recruited. All subjects spent 3 consecutive nights in the sleep laboratory. During the first and second nights, the subjects were not exposed to light during sleep, but during the third night, they were exposed to ambient light, measuring 5 or 10 lux at the eye level, which was randomly allocated with 30 subjects each. The visual function and ocular fatigue were assessed at 7 a.m. on the 3rd and 4th mornings, using best-corrected visual acuity, refractive error, conjunctival hyperemia, tear break-up time, maximal blinking interval, ocular surface temperature, and subjective symptoms reported on a questionnaire. Results: Three men and three women subjects failed to complete the study (4 in the 5 lux; 2 from the 10 lux). For the entire 54 subjects, tear break-up time and maximal blinking interval decreased (P = 0.015; 0.010, respectively), and nasal and temporal conjunctival hyperemia increased significantly after sleep under any ambient light (P < 0.001; 0.021, respectively). Eye tiredness and soreness also increased (P = 0.004; 0.024, respectively). After sleep under 5 lux light, only nasal conjunctival hyperemia increased significantly (P = 0.008). After sleep under 10 lux light, nasal and temporal conjunctival hyperemia, eye tiredness, soreness, difficulty in focusing, and ocular discomfort increased significantly (P < 0.05). Conclusion: Nocturnal ambient light exposure increases ocular fatigue. Avoiding ambient light during sleep could be recommended to prevent ocular fatigue.

강화 학습을 이용한 인터넷 문서 여과

서영우,장병탁 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.1B

본 논문에서는 일반 사용자가 웹 문서공간에서 자신의 정보 요구에 적합한 정보를 찾을 때 맞게되는 부적절한 문서의 홍수에서 보다 적합한 문서를 여과시키는 방법을 제시한다. 제시된 방법은 적합성 최적-우선 탐색 방법으로 문서들을 검색하여 강화학습을 통해 학습된 사용자의 기호를 기준으로 문서들을 여과한다. 검색된 HTML문서는 사용자의 정보용구와의 적합성을 평가하는 하나 이상의 필드로 표현된다. 검색기간동안 학습에 이전트는 적합성검사에 사용되는 필드의 참여 비율을 조절하여 웹 문서 검색 에이전트의 검색정책을 수정한다. 제시된 결과에 대한 사용자의 적합성 평가는 사용자의 프로파일을 학습하고 웹 문서 검색 에이전트의 검색 정책에 대한 보상 또는 질책으로 사용된다. 실험은 기존의 웹 검색 엔진들과 제시된 방법을 동일한 topic에 대하여 각각의 검색결과에 대한 사용자의 만족도를 측정하였고 검색이 계속되는 동안 HTML문서에 대한 사용자의 기호를 학습하는 과정을 관찰하였다. 실험을 통해서 제시된 방법이 실제 환경에서 보다 나은 성능을 보였다.

지상파 UHD 방송 부가서비스 동향 및 전망

서영우,전성호 한국방송·미디어공학회 2020 한국방송공학회 학술발표대회 논문집 Vol.2020 No.7

초음파 유화술시 발생하는 유리기에 대한 아스코르빈산의 각막 내피 보호 효과

서영우,오청훈,김효명,Young-Woo Suh,Chung-Hoon Oh,Hyo-Myung Kim 대한안과학회 2005 대한안과학회지 Vol.46 No.3

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Purpose: To evaluate corneal endothelial protection effect of ascorbic acid (AA) at the most appropriate concentration, and determine the synergistic effect of glutathione in irrigation solution during phacoemulsification. Methods: Phacoemulsification was performed in the anterior chamber of 30 rabbit eyes for 5 minutes without damage to other ocular structures. Thirty rabbit eyes were divided into 6 groups, of 5 eyes each, according to the following irrigation solutions in phacoemulsification.: BSS? in group 1, BSS? with 1 mM AA in group 2, BSS Plus? in group 3, BSS Plus? with 0.1 mM AA in group 4, BSS Plus? with 1 mM AA in group 5 and BSS Plus? with 10 mM AA in group 6. Corneal endothelial loss was measured with specular microscopic photographies taken before and 1 week after surgery. Results: Postoperatively endothelial counts were reduced by 592.0±100.0, 275.9±51.9, 658.2±107.1, 466.3±88.6, 259.3±61.6 and 451.6±63.7 (mean cells/mm2±SD) in groups 1-6, respectively. Endothelial cells in group 2 were less reduced than in group 1 (P=0.009), but there was no difference between groups 2 and 5. Though the reduction of endothelial cells in groups 4, 5, and 6 were less than in group 3 (P<0.05), group 5 showed more significant endothelial protection effect than groups 4 and 6 (P=0.009, 0.009). Conclusions: AA in irrigation solution showed endothelial protection effect against free radicals during phacoemulsification, and 1 mM was the most effective concentration. Combination of glutathione with AA did not show any synergistic endothelial protection effect.

간헐기를 거친 항상성 외사시의 임상특징

서영우,차덕선,조윤애,김승현.Young-Woo Suh. MD. PhD. Deoksun Cha. MD. Yoonae A. Cho. MD. PhD. Seung-Hyun Kim. MD. PhD 대한안과학회 2011 대한안과학회지 Vol.52 No.4

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Purpose: To investigate clinical characteristics of constant exotropia patients with a previous history of intermittent exotropia. Methods: Constant exotropia patients (CXT) with a previous history of intermittency, and intermittent exotropia patients (X [T]) who had undergone surgery for exotropia were included in the present study. Patching therapy of the fixating eye was performed for all patients. Surgical results, the effect of patching, lateral incomitancy, and suppression were retrospectively reviewed and compared between the 2 groups. Results: The number of CXT was 51 and X (T) was 84. The angles of deviation at the initial visit and at surgery were significantly larger in CXT. After 3 months of patching therapy, there was no difference between the 2 groups in the reduction of distant angle of deviation. However, the reduction of near angle of deviation was 0.29 ± 5.44 in CXT and 4.42 ± 6.26 Δ in X (T), which was significantly different (p = 0.04). Lateral incomitancy was observed in 7.8% of CXT and 34.5% of X (T) (p < 0.001). The angles of deviation at the final visit and surgical success rate were not different between the groups. Preoperative suppression at distant was found in 100% of CXT and 88.7% of X (T), and postoperative suppression was in 17.6% and 18.3%, respectively. Conclusions: The surgical success rate and postoperative suppression were not different between constant exotropia and intermittent exotropia. However, the frequency of lateral incomitancy and the response to the patching therapy was lower in constant exotropia. J Korean Ophthalmol Soc 2011;52(4):462-465

컴퓨터 작업으로 인한 눈 피로의 객관적 평가 방법

서영우,김균형,강수연,김성우,오재령,김효명,송종석,Young-Woo Suh,Kyun-Hyung Kim,Su-Yeon Kang,Seoung Woo Kim,Jae Ryung Oh,Hyo-Myung Kim,Jong-Suk Song 대한안과학회 2010 대한안과학회지 Vol.51 No.10

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Purpose: To develop methods for the objective measurement of ocular fatigue. Methods: Fifteen patients were enrolled in the present study. Subjects performed visual tasks on a computer for one hour. A survey of ocular fatigue was conducted with a questionnaire. Tear break-up time, blinking rate, ocular protection index, conjunctival injection, maximal blinking interval, temperature of the ocular surface, and visual evoked potential were evaluated before and immediately after the task. Surface electromyography of the orbicularis oculi muscle was performed before and during the task. Results: The survey showed increases in subjective ocular fatigue in all subjects. Tear break-up time, ocular protection index and maximal blinking interval decreased, while temperature of the ocular surface increased after the task. Conjunctival injection showed a tendency to increase. Electromyography, and visual evoked potential did not change significantly. Conclusions: In the present study, tear break-up time, ocular protection index, maximal blinking interval, and temperature of the ocular surface changed as ocular fatigue increased. Therefore, these measures can be objectively used for the evaluation of ocular fatigue. J Korean Ophthalmol Soc 2010;51(10):1327-1332

Improving the Corrosion Resistance of AISI 316L Steel for Semiconductor Piping by Controlled Delta-Ferrite Content

서영우,김찬양,서보경,정원섭 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.1

This study evaluated changes in delta-ferrite content depending on the preheating of AISI 316L stainless steel. We also determined the reasons for the variation in delta-ferrite content, which affects corrosion resistance. Changes in delta-ferrite content after preheating was confirmed using a Feritscope, and the microstructure was analyzed using optical microscopy (OM). We found that the delta-ferrite microstructure size decreased when preheating time was increased at 1295 oC, and that the delta-ferrite content could be controlled through preheating. Potentiodynamic polarization test were carried out in NaCl (0.5 M) + H2SO4 (0.5 M) solution, and it was found that higher delta-ferrite content resulted in less corrosion potential and passive potential. To determine the cause, an analysis was conducted using energy-dispersive spectroscopy (EDS), which confirmed that higher delta-ferrite content led to weaker corrosion resistance, due to Cr degradation at the delta-ferrite and austenite boundaries. The degradation of Cr on the boundaries between austenite and delta-ferrite can be explained by the difference in the diffusion coefficient of Cr in the ferrite and austenite. A scanning electron microscopy (SEM) analysis of material used for actual semiconductor piping confirmed that corrosion begins at the delta-ferrite and austenite boundaries. These results confirm the need to control delta-ferrite content in AISI 316L stainless steel used for semiconductor piping.