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이경원,이석준,이종혁,Kyung-won Lee,M,D,Seok-joon Lee,M,D,Jong-hyuck Lee,M,D 대한안과학회 2005 대한안과학회지 Vol.46 No.1
Purpose: Scleral buckles are frequently performed as an additional procedure in perforated ocular injury surgery, but little is known about their independent effect after ocular trauma. The authors made a posterior penetrating ocular injury model in rabbits to evaluate the isolated role of primary scleral buckle placement. Methods: Twenty eyes underwent surgery. The penetrating injury consisted of two 5 mm circumferential incisions placed five clock hours apart and 7 mm behind the limbus. A segmental scleral buckle was placed over a randomly chosen penetrating injury site after wound closure. The degree of the fibrous proliferation, traction, and the presence of retinal detachment were evaluated on follow-up examination. After enucleation and fixation, tissue sectioning was performed including injury sites. The greatest dimension of the fibrous proliferation at both wound sites was measured. Results: Two eyes were excluded from the study due to unsuccessful buckling. Four eyes developed a retinal detachment. The remaining 14 eyes showed varying degrees of proliferation and traction on the retina. The greatest dimension of the fibrous proliferation at the buckle site (1.69±0.29 mm) was significantly different from that at the non-buckle site (2.07±0.37 mm, P<0.05). Conclusion: Primary scleral buckle placement at the time of surgical repair reduces vitreous traction and decreases the degree of fibrous proliferation.
특이값 제거 기법을 적용한 수중 이동체의 음향 거리 추정
이경원,오단비,김기만,김태형,이희창,Kyung-won Lee,Dan-bi Ou,Ki-man Kim,Tae Hyeong Kim,Heechang Lee 한국음향학회 2024 韓國音響學會誌 Vol.43 No.4
수중 이동체의 방사소음을 측정하는 경우 이동체와 수신기 사이의 거리 정보가 중요한 요소이지만 수중에서는 Global Positioning System(GPS)를 사용할 수 없기 때문에 대체 수단이 필요하다. 대체 수단으로써 별도의 음향신호를 이용하여 도달 시간, 도달 시간 차 및 도달 주파수 차 등을 추정하여 거리를 측정한다. 하지만 채널 환경에 의해 오류가 발생하며, 이러한 특이값들은 연속적으로 거리를 측정함에 있어서 장애 요인이 된다. 본 논문에서는 거리 정보를 측정하는 과정에서 발생한 특이값들을 제거하기 위하여 사후 처리로써 V-곡선 형태의 함수로 곡선 적합하여 오류를 감소시키는 방법을 제안한다. 제안한 방법의 성능검증을 위해 모의, 호수 및 해상실험을 수행하였다. 호수실험 결과에서는 Root Mean Square Error(RMSE) 관점에서 약 85 % 정도로 거리 추정 오차가 감소하였다. When measuring the radiated noise of an underwater vehicle, the range information between the vehicle and the receiver is an important factor, but since Global Positioning System (GPS) is not available in underwater, an alternative method is needed. As an alternative, the range is measured by estimating the arrival time, arrival time difference, and arrival frequency difference using a separate acoustic signal. However, errors occur due to the channel environment, and these outliers become obstacles in continuously measuring range. In this paper, we propose a method to reduce errors by curve fitting with a function in the form of a V-curve as a post-processing to remove outliers that occurred in the process of measuring range information. Simulation, lake and sea trials were conducted to verify the performance of the proposed method. In the results of the lake trial, the range estimation error was reduced by about 85 % from the Root Mean Square Error (RMSE) point of view.
이경원,박찬흔,박용래,현기훈,윤지섭,Kyung-Won Lee,Chan-Heun Park,Yong-Lai Park,Ki-Hun Hyun,Ji-Sup Yoon 대한갑상선-내분비외과학회 2013 The Koreran journal of Endocrine Surgery Vol.13 No.4
Purpose: Gasless transaxillary approach to endoscopic thyroidectomy is a widely performed procedure for benign or malignant thyroid neoplasms. However, it requires wide dissection for approaching the target area. The intravenous patient-controlled analgesia (IV PCA) is an effective method for postoperative pain control and patients can use it according to their requirement. However, patients suffer from nausea, vomiting, sleep disturbance, etc. due to opioids. Pain pump ON-Q<sup>Ⓡ</sup> PainBuster<sup>Ⓡ</sup> (pain buster) has been used widely in various surgeries for control of postoperative localizing and wide area pain without side effects of opioid analgesia because it consists of Ropivacaine. Methods: From Aug. 2008 to Jan. 2013, Gasless transaxillary endoscopic thyroidectomy was performed in 90 patients in a single institution, who were divided into three groups, including the IV PCA, pain buster, and null groups. We compared postoperative outcomes, pain severity between groups. We recorded scores immediately, 6, 12, 24, and 48 hours after surgery following visual analog pain score (VAS), and investigated hospital stay and occurrence of events of nausea, vomiting, and complications. Results: In the IV PCA group, it was discontinued due to nausea in 36.7% of patients. No significant difference in pain severity following VAS score was observed among the three groups. However, smaller numbers of analgesia injections were required in the Pain buster group than in the other groups, and fewer patients suffered from constipation, compared with the PCA group. Conclusion: Pain buster showed even effects compared to IV PCA, with few side effects and less discomfort of patients, compared with the other groups. Therefore, pain buster was thought to be the proper method for pain control after dissection of the anterior chest wall, cervical area in order to secure an operative view for transaxillary endoscopic thyroi-dectomy.
수정된 설계 방정식을 이용한 허니컴 구조의 차폐 효과 예측
이경원,정영철,홍익표,육종관,Lee Kyung-Won,Cheong Yeong-Chul,Hong Ic-Pyo,Yook Jong-Gwan 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.9
In this paper, the modified design equation of shielding effectiveness was presented to predict more accurately the shielding effectiveness of honeycomb structure with hexagonal waveguide. The design equation of shielding effectiveness in honeycomb was represented from adding shielding effectiveness of single lattice to shielding effectiveness of infinite array of single lattice. This paper proposed the generalized design equation of shielding effectiveness by analyzing basis lattice of hexagonal waveguide which composes honeycomb structure and infinite array structure of basis lattice. To provide the validity of the modified design equation of shielding effectiveness in this paper, comparison with other available date using 3D EM commercial software is made.
범주형 환경변수를 고려한 부대성과평가 방법에 관한 연구 - DEA와 CCCA의 결합을 중심으로 -
이경원,박명섭,임재풍,Lee, Kyung-Won,Park, Myung-Seop,Im, Jae-Poong 한국국방경영분석학회 2006 한국국방경영분석학회지 Vol.32 No.1
There are many occasions that the performance of a corps is influenced not only by its own efforts but by the commander of the next higher unit in a vertical organizational structure. When the direction of the commander in the next higher organization is different from that of the actual evaluation agency, the unit under evaluation may get rated lower than what it should deserve. This study suggests an alternative method to evaluate the performance of military units in the situation that there exist critical environmental factors which affect the performance. This method employes DEA, a non parametric method, and Constrained Canonical Correlation Analysis(CCCA), a parametric method which is used to estimate a efficient frontier with multiple dependent variables and constraints. This article also exploits a set of categorical environmental variables in the CCCA to improve the fairness of performance evaluation. It is shown that the introduction of the categorical variables helps evaluating the true performance of individual units such as battalions subordinated to different next higher commanders.
탄소섬유강화플라스틱CFRP의 인장하중하에서의 파괴거동에 따른 음향방출신호 특성에 관한 연구
이경원 ( Kyung Won Lee ),이상윤 ( Sang Yun Lee ),남준영 ( Jun Young Nam ),이종오 ( Jong Oh Lee ),이상율 ( Sang Yul Lee ),이보영 ( Bo Young Lee ) 한국항공운항학회 2010 한국항공운항학회지 Vol.18 No.4
Recently, aerospace structures have lightweight trend in order to reduce the cost of fuel and system, Carbon Fiber Reinforced Plastic (CFRP) can give the ability to reduce weight at 20~50% as the substitution of metal alloy, and there are advantages such as high Non-rigid, specific strength and anti-corrosion, but it is difficult to prove its destruction properties due to heterogeneous structure and anisotropy. In this study we designed specimen, inducing distinguishing destructions of material (for example, matrix crack, fiber breakage, and delamination) by using the Carbon Fiber Reinforced Plastic (CFRP) which is used in a real aircraft, to apply acoustic emission technique to aerospace structures. And we gained data via tensile testing and acoustic emission technique, from which each fault signal was classified respectively by using AE parameters and waveform.
Carbon Fiber Reinforced Plastic(CFRP)복합재의 파괴 거동에 따른 Acoustic Emission(AE)신호 특성에 관한 연구
이경원 ( Kyung Won Lee ),김종현 ( Jong Hyun Kim ),김재성 ( Jae Seong Kim ),이보영 ( Bo Young Lee ) 한국항공운항학회 2009 한국항공운항학회지 Vol.17 No.4
Recently, the wide range of the composite materials is used for the making airplanes, trains and automobiles body for the lightweight. Despite having complex structures, composite materials usually have well defined mechanical characteristics. However, composite materials are difficult to understand the fracture mechanism clearly by simple mechanical test. Nondestructive evaluation (NDE) combined with mechanical testing can play a more important role and especially Acoustic Emission Testing (AET) would become known to be a useful tool to assess damage and fracture behavior of composites. In this study The experiment was performed to acquire the acoustic emission signal during tensile test using unidirectional CFRP specimen and the data was analyzed the acoustic emission parameters with the waveform.