외부압력으로 부착된 강판으로 보강된 구속콘크리트의 압축반복거동 모델

최은수,송세근,Choi. Eunsoo,Song. Segeun 한국방재학회 2013 한국방재학회논문집 Vol.13 No.1

본 연구에서는 그라우팅 없이 외부압력을 이용해서 부착된 강판으로 보강된 콘크리트의 압축반복거동에 대한 응력-변형률 모델을 개발하여 제공하고자 한다. 두께 1.0 mm와 1.5 mm 두 종류의 스테인레스 스틸로 <TEX>$150mm{\times}300mm$</TEX> (<TEX>${\Phi}xH$</TEX>)의 시편을 보강하였다. 압축강도가 1.0 mm 및 1.5 mm 두께에 대해서 각각 강도 증가율이 32.1% 및 45.6% 으로 나타났으며 Sakai and Kawashima 모델을 이용하여 구속 효과를 확인하기 위해 보강된 콘크리트 기둥의 반복하중 거동을 분석하였다. 본 연구 실험의 반복하중 거동을 Sakai and Kawashima 모델과 비교 분석해 본 결과, 제하 이력곡선과 재재하 이력곡선이 값의 재해석을 통해 매우 일치함을 확인할 수 있었다. This study provides a model for cyclic compressive behavior of concrete confined by steel wrapping jackets without grouting. This study uses concrete specimens of <TEX>$150mm{\times}300mm$</TEX> (<TEX>${\Phi}xH$</TEX>) with steel jackets of the thickness of 1.0 mm and 1.5 mm. The peak strength of concrete increases by 32.1% and 45.6% with applying the steel jacket of 1.0 mm and 1.5 mm, respectively. This study adopts the Sakai and Kawashima model for cyclic compressive behavior of confined concrete, and it is found that the experimental results correspond well to the adopted model.

특발성 황반원공에 있어 인도사이아닌그린과 트리암시놀론을 이용한 내경계막 제거술의 임상결과비교

최은수,최영락,윤희성,Eun Su Choi,Yeong Rak Choi,Hee Seong Yoon 대한안과학회 2006 대한안과학회지 Vol.47 No.10

Purpose: To compare the outcomes of indocyanine green (ICG) and triamcinolone (TA) assisted internal limiting membrane (ILM) peeling during idiopathic macular hole surgery. Methods: Fifty-four eyes of 54 patients with idiopathic macular hole underwent pars plana vitrectomy including peeling of the posterior cortical hyaloid and peeling of the internal limiting membrane. For enhanced visualization of ILM, ICG was used in 25 eyes and TA in the remaining 29 eyes. Postoperative visual acuity was measured and OCT was performed. Results: Anatomical closure was achieved in 25 eyes (100%) in ICG group and 28 eyes (97%) in TA group, Best corrected visual acuity improvement by ?2 lines was in 15 eyes (60%) in ICG group and 18 eyes (62%) in TA group. Postoperative visual improvement rates by ?20/50 were 10 eyes (40%) in ICG group and 9 eyes (31%) in TA group. Conclusions: Peeling of the internal limiting membrane using triamcinolone and indocyanine green was safe and effective for anatomic and functional success in idiopathic macular hole surgery. Further studies of the toxicity of TA, ICG and the result of internal limiting membrane peeling is needed.

쯔쯔가무시병에서 발생한 전포도막염 1예

최은수,문상정,김호숭,이경헌,Eun Su Choi,Sang Jeong Moon,Ho Soong Kim,Kyung Hun Lee 대한안과학회 2010 대한안과학회지 Vol.51 No.10

Purpose: To report a single case of tsutsugamushi disease with anterior uveitis and eschars on the upper eyelid. Case summary: A 56-year-old female patient complained of ocular pain and gradually decreasing visual acuity in her right eye. On physical examination, lymphadenopathy was palpable on the right side of the neck, and eschars were observed on the forehead and upper eyelid. On slit lamp examination, conjunctival injection, episcleral vessel dilations and severe intraocular inflammatory reaction were observed. Fundus examination showed no abnormal findings. A blood test was submitted for analysis, and tsutsugamushi disease was diagnosed. The patient’s ocular manifestations responded well to treatment with steroids. After three weeks, the patient showed improvement on ocular examination, and no problems were observed at the six-month follow-up. Conclusions: Although ocular manifestation of tsutusgamushi disease with conjunctivitis and limbitis has previously been reported, ocular manifestation of tsutusgamushi disease with anterior uveitis has not been reported. Anterior uveitis may respond satisfactorily to steroid treatment, along with improvement in systemic conditions. J Korean Ophthalmol Soc 2010;51(10):1414-1418

펨토초 레이저와 미세각막절삭기를 이용한 근시교정수술에서 임상성적 비교

최은수,정희진,이경헌,Yun Su Choi,M,D,Hee Jin Jung,M,D,Kyung Hun Lee,M,D 대한안과학회 2007 대한안과학회지 Vol.48 No.8

Purpose: To compare results between in femtosecond laser and microkeratome LASIK correction of myopia Methods: We retrospectively analyzed the result of 94 eyes of 47 patients in the femtosecond group (F) and 103 eyes of 52 patients in the microkeratome group (M). All patients had undergone LASIK using either a femtosecond laser or a microkeratome for making of flap. Patients were divided into groups I (6D≤) and II (≥6D) according to preoperative myopia. Each patient was followed up for over 6 months with measurements of uncorrected visual acuity and manifest refraction at 1 week and 1, 3, and 6 months after operation. Complications during and after the operation were reviewed retrospectively in two groups 6month after the operation. Results: In groups F-I, F-II, M-I, and M-II, postoperative 6-month uncorrected visual acuity was 0.98±0.08, 0.96±0.09, 0.97±0.03, 0.98±0.09. At the 6-month follow-up, there were no significant differences between the two groups in uncorrected visual acuity and mean spherical equivalent. Corneal opacity was found in 3 eyes in group M and complication related with flap was found 1 eye in group F and 4 eyes in group M. Conclusions: During a 6-month follow up, LASIK using either a femtosecond laser or a microkeratome has an similar effect in uncorrected visual acuity and mean spherical equivalent. Thus LASIK for using femtosecond laser can be used as an alternative procedure to correct myopia.

결막하 스파르가눔증 1예

최은수,한상엽,박동원,노주헌,Eun-Su Choi,Sang-Youp Han,Dong-Won Park,Ju-Hun Rho 대한안과학회 2005 대한안과학회지 Vol.46 No.12

Purpose: The subconjunctival sparganosis is rare tissue helminthiasis which developed frequently in abdominal, urethral, ureteral and vertebral cases. Authors report a case of sparganosis in the subconjunctival mass. Methods: A 51-year-old man with reddish non painful mass in his left eye on the subconjunctiva that was unresponsive to medications for 6months was evaluated and treated surgically. On surgical exploration, a white thread-like plerocercoid 0.2×4.7 cm in size was extracted from the subconjunctival mass and actively motile in the bottle filled with saline. It was confirmed as a typical sparganum under histologic examination. Three months after surgery, the lesion disappeared completely. Results: Although rare, parasitic disease should be suspected in a palpable subconjuntival mass unresponsive to the medical treatment.

소아에서 위장관내 이물질의 임상적 고찰

최은수,이호균,최수진나,정상영,Choi, Eunsoo,Lee, Hyo Gyun,Choi, Soo Jin Na,Chung, Sang Young 대한소아외과학회 2014 소아외과 Vol.20 No.1

Foreign body ingestion is a common problem among paediatric populations. Most of the ingested foreign bodies spontaneously pass through the gastrointestinal tract, but approximately less then 10% of them remain without being discharged, and trigger complications. Therefore, proper evaluation and treatment according to the situation is required. In this study, clinical progress and complications were analyzed according to the clinical features and treatment in children who ingested foreign bodies. Among pediatric patients under 18 who were admitted to Chonnam National University Hospital after ingesting foreign bodies between January 2008 to June 2012, only the patients who had their foreign body in the gastrointestinal tract were included in this study. Based on medical records, age, type of foreign body, time spent till admission, and whether the endoscopy was done or not, complication were researched retrospectively. According to symptoms and plain abdomen X-ray findings, treatment was chosen and conducted among endoscopy, observation and emergency operation. Among 273 patients, 9 (3.3%) of them had surgical removal. Seven (2.6%) of them had an emergency operation on the day of admission, and the rest 2 (0.7%) had operation during observation. Removal through initial endoscopic approach was tried in 157 (57.5%) patients. Eleven (70.8%) of them had their foreign body removed at the initial trial, and 5 (4.9%) of them at the second trial. Among 109, who were on observation status, 9 (8.3%) of them needed endoscopic removal, and 2 (1.8%) of them suffered from surgical removal. It is thought to be better to approach slowly considering the type, size and symptoms in foreign body ingestion of pediatric patients, rather than immediate and invasive removal.

철도교용 고무패드 설치에 따른 판형교의 동적 거동 분석

최은수,김현민,오지택,김성일,Choi, Eun Soo,Kim, Hyun Min,Oh, Ji Taek,Kim, Sun Gil 한국강구조학회 2005 韓國鋼構造學會 論文集 Vol.17 No.3

본 연구에서는 '철도교용 고무패드의 강성추정기법'에서 결정된 각 고무패드의 강성과 가정된 감쇠비를 이용하여 두 판형교에서의 동적 거동을 분석하였다. 또한 패드에 의한 판형교의 동적 거동 변화가 철도교량의 거동의 한계를 규정하고 있는 규준에 적합한지도 판단하였다. 고무패드를 교좌로 판형교에 설치하면 판형교의 동적 처짐은 증가하였다. 그러나 처짐이 증가하더라도 규정에 있는 한계를 넘지는 않아 차량의 안정적 주행에 영향을 주지는 않는다. 천연고무나 크로로프렌 고무패드는 변형이 크게 발생하여 교좌로서 활용이 부적합하나, 폴리우레탄 고무패드는 변형이 작게 나타나 사용성이 우수한 것으로 판단되었다. 그러나 고속 주행을 위해서는 패드의 면적을 증가 시켜서 패드변형을 제한해야 하는 것으로 나타났다. 고무패드의 강성증가 및 감쇠비 증가가 교량의 동적 거동에 미치는 영향에 대해서 분석을 실시하였다. 고무패드의 감쇠비 증가는 교량의 동적 거동에 거의 영향을 주지 않았다. 패드의 강성 증가는 상대적으로 자중이 크고 강성이 작은 교량에서는 응답 개선 효과가 적지만, 자중이 작고 강성이 큰 즉 경간이 짧은 교량에서 상대적으로 응답 개선 효과가 크게 나타났다. In this study, the dynamic characteristics of the two open-steel-plate-girder bridges was analyzed using the pads' stiffness estimated in the previous accompanying paper.Also, it was determined that the variation in the dynamic behavior of the two bridges due to the pads corresponds to the codes describing the restriction for the steel bridges' behavior.The pads installed at the bridges increase the displacement at mid-span.However, the increase does not exceed code restrictions and does not have an adverse effect on the riding quality of the running trains. The natural and Chloroprene rubber pads are not suitable for bridge bearings since they are more deformed than the code regulated ones.

외부구속자켓의 구속비와 강도비에 따른 콘크리트 부착거동의 특성

최은수,정춘성,Choi, Eunsoo,Jung, Chunsung 대한토목학회 2014 대한토목학회논문집 Vol.34 No.1

이 연구에서는 형상기억합금과 강재로 구속된 콘크리트의 부착응력을 외부자켓의 구속비 및 강도비를 이용하여 분석하였다. 이를 위해서 직경 1.0 mm 형상기억합금 와이어와 두께 1.0 mm와 1.5 mm 강판을 사용하여, 구속비 및 강도비의 차이를 유발하여 각 변수의 차이에 따른 부착강도 및 부착거동을 분석하였다. 외부자켓 구속에 의해서 콘크리트의 부착강도는 증가하였으며, 파괴형태도 쪼갬파괴에서 뽑힘파괴로 전환되어 구속효과가 있음을 알 수 있었다. 콘크리트 부착강도는 구속비와 강도비가 증가함에 따라 증가하는 현상을 보이지만, 특정 시점부터는 부착강도가 거의 증가하지 않고 일정한 값을 나타내는 결과를 보였다. 그러나 강도비의 증가에 따라 발생하는 원주방향 최대 변형율은 거의 선형적으로 감소하는 결과를 보였다. This study analyzes the characteristics of bond behavior of concrete, which is confined by external jackets such as shape memory alloy (SMA) and steel, according to confinement and stiffness ratios of the external jackets. For this purpose, SMA wires with 1.0 mm diameter and steel plates with 1.0 and 1.5 thickness are used to induce difference on confinement and stiffness ratios and, then, bond strength and behavior are analyzed considering the two factors. When external jakcets are used for the concrete cylinders, bond strengths of specimens increase and their bond failures are transferred from splitting failure to pull-out failure and, thus, the external jackets show confining effect. Bond strenght of concrete increase with increasing confinement and stiffness ratios of the external jackets. However, maximal circumferential strains decrease linearly with increasing the two values.

Effect of Simplified Methods in Seismic Analysis of Bridges

최은수,Choi, Eunsoo Korean Society of Steel Construction 2002 韓國鋼構造學會 論文集 Vol.14 No.6

본 연구에서는 스틸베어링을 가진 교량의 단순해석의 효과를 상부구조의 충돌의 유무에 따라 점검하였다. 교량의 지진해석에서는 비선형 시간이력해석이 일반적으로 사용되지만, AASHTO 등을 포함해서 많은 시방서는 단순해석법을 제시하고 있다. 그러나 AASHTO에서는 충돌에 대한 언급이 없고, 이로 인하여 단순해석의 결과가 비선형 시간이력해석과 차이가 있을 수 있음을 알 수 있다. 그래서 본 연구에서 다경간 단순지지 교량과 다경간 연속 고량, 두 형태의 교량에 대하여 비선형 모델을 개발하고, 이들을 단순해석에 적합하게 선형 모델로 수정하였다. 그리하여 비선형 시간이력해석과 단순 선형해석들의 결과를 비교 검토하였다. 이를 통해서, 단순 선형해석에 있어서 충돌 또는 접촉을 고려하는 것이 비선형 시간이력해석 결과와 가장 근접함을 알 수 있었다. The effect of several simplified methods of seismic analysis is estimated. The pounding/contacting of superstructures were considered in the multispan simply supported bridge and the multispan continuous bridge. Although nonlinear time history analysis is generally used for seismic analysis of bridges, many codes including AASHTO propose several simplified analysis methods. AASHTO, however, does not mention pounding. Therefore, the simplified methods may produce results that are different from those of nonlinear time history analysis. This study developed nonlinear analytical models of the two types of bridges mentioned. The models were then modified to the simplified linear models for simplified analysis. The results of the simplified methods were compared with those of nonlinear time history analysis. It was found that including of the pounding/contacting element in the simplified methods generated responses similar to those of the nonlinear time history analysis.

Seismic base isolation for highway steel bridges using shape memory alloys

최은수,전준창,Choi, Eun Soo,Jeon, Jun Chang Korean Society of Steel Construction 2004 韓國鋼構造學會 論文集 Vol.16 No.1

Conventional lead-rubber bearings may be unstable in case of strong ground motions. To address this problem, this paper proposed a new concept of isolation device wherein shape memory alloy wires were incorporated in an elastomeric bearing. A three-span continuous steel bridge was used for seismic analyses to compare the performance of lead-rubber and proposed bearings. The proposed bearings showed almost the same performance as the lead-rubber bearings. In particular, the proposed bearings limited relative displacement effectively with strong ground motions and recovered its original undeformed shape. 기존교량의 내진성능개선 및 신설교량의 지진보호에 납-고무 베어링은 좋은 효과를 보여주고 있다. 그러나 납-고무 베어링은 사용상에 있어 문제점이 있으며, 이를 개선하기 위하여 형상기억합금(shape memory alloy)을 이용한 면진장치를 본 연구에서 제시하였다. 3경간 연속 고속도로 강교량의 지진해석을 통하여 납-고무베어링과 고무베어링 및 형상기억합금 와이어와의 조합 면진장치의 지진거동을 비교하였다. 해석결과 형상기억합금 와이어+고무베어링 시스템이 납-고무베어링과 거의 유사한 거동을 보여주었으며, 특히 제시된 면진장치는 상대변위의 제어 및 잔류변형에 있어 기존의 납-고무 베어링에 비해 성능이 우수했다.