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초탄성 형상기억합금을 활용한 자동복원 가새 프레임 구조물의 내진성능 평가 - 비선형 동적해석
반우현,허종완,주영훈 대한토목학회 2020 대한토목학회논문집 Vol.40 No.4
Korea was recognized as a relatively safe area for earthquake. However, due to considerable damage to facilities caused by the earthquake in Gyeongju and Pohang, interest in the maintenance and repair of structures is increasing. So interest in vibration damping technology applicable to existing structures is also increasing. However, vibration damping technology has a problem in that its usability is reduced due to damage of the damping device when a strong earthquake occurs. Recently, in order to solve such a problem, study is being conducted to apply a superelastic shape memory alloys (SSMA) capable of recentering bracing. Therefore, in this study, nonlinear dynamic analysis is performed to evaluate the seismic performance of the buckling-restrained braced frame (BRBF) applied SSMA to bracing. 우리나라는 비교적 지진에 대해 안전한 지역으로 인식되고 있었다. 그러나 최근 경주와 포항에서 발생한 지진으로 인한 시설물에 상당한 피해가 발생함에 따라 이미 건축된 구조물의 유지, 보수에 관한 관심이 높아지고 있다. 따라서 기존 구조물에 적용 가능한 제진기술에 대한 관심 또한 높아지고 있다. 그러나 제진기술은 강한 지반 운동으로 인한 장치의 손상으로 인하여 성능 저하의 문제점이 있다. 최근 이러한 문제를 해결하기 위해, 가새 부재에 응력을 제거함으로써 자동복원이 가능한 초탄성 형상기억합금을 적용하는 연구가 이뤄지고 있다. 따라서 본 연구에서는 초탄성 형상기억합금을 적용한 비좌굴 가새 부재를 활용하여 자동복원 프레임 구조물을 구성하고 비선형 동적 해석을 통하여 초탄성 형상기억합금의 재료적 우수성과 구조물의 내진성능을 평가 및 검증하였다.
굽힘하중을 받고 있는 3가지 선반조립구 이음구조의변형 저항에 관한 수치해석
반우현,최복록 한국기계기술학회 2022 한국기계기술학회지 Vol.24 No.1
The design of the corner joints in furniture structures is very important to firmly support the loaded structure and to sufficiently maintain the durability and stability. Therefore, the strength of the corner joints and the rigidity of the connected panels play a very important role in the structural performance of the assembled furniture. The structural properties can be measured or calculated experimentally or numerically, and compared by representing the applyed forces or bending moments as a function of deformed value. This paper shows the numerical models to determine the strength and stiffness of the 3-types of corner joints for simple designed furniture. Based on the finite element results, the maximum stresses are concentrated on the corner joints designed with MDF panels. And the deformation resistances and maximum applied loads are calculated for furniture corner joints under tensile and compressive moment.
초탄성 형상기억합금을 활용한 자동복원 가새 프레임 구조물의 내진성능 평가: 비선형 정적해석
반우현,허종완 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.2
우리나라는 지진에 대해 비교적 안전한 지역으로 인식되고 있었으나, 최근 경주지진과 포항지진이 발생하면서 시설물에 상당한 피해가 발생되면서 지진피해 저감장치를 적용한 내진설계 및 보강에 대한 연구와 개발이 수행되고 있다. 이미 건축된 구조물의 유지⋅보수에 대한 관심이 높아짐에 따라, 구조물의 감쇠, 강성 등을 국부적으로 변화시켜 지진 하중에 의한 에너지를 흡수하고 소산시키는 내진설계 방식인 제진기술이 활용되고 있다. 그러나 강한 지진이 발생할 때 제진 장치의 손상으로 인하여 사용성이 매우 떨어지게 되는 문제점이 발생되고 있다. 최근에는 이러한 문제를 해결하기 위해, 구조물의 가새 부재에 별도의 열처리를 하지 않고 응력 제거만으로 원형복원이 가능한 초탄성 형상기억합금을 적용하는 연구가 진행되고 있다. 따라서 본 연구에서는 비좌굴 가새 부재에 초탄성 형상기억합금을 사용하여 자동복원이 가능한 프레임 구조물을 구성하여 비선형 정적해석을 수행하여 구조물의 내진성능을 평가하고, 초탄성 형상기억합금의 재료적 특성의 우수성을 검증하고자 한다. Korea had been recognized as a relatively safe country from earthquakes. However, this perception has changed as recent earthquakes in Gyeongju and Pohang caused significant damage to facilities. Therefore, research and development on seismic design and reinforcement using seismic damage reduction devices are being conducted. As the interest in the maintenance and repair of built structures increase, vibration-damping technology is being used. Vibration-damping technology is a seismic design method that absorbs and dissipates energy because of seismic loads by locally changing the damping and rigidity of structures. However, when a strong earthquake occurs, the usability is poor due to damage to the vibration-damping devices. Recently, to solve this problem, research has been conducted by applying the super-elastic shape memory alloys (SSMA) capable of re-centering by removing stress without additional heat treatment on the bracing of the structures. Therefore, this study performs nonlinear static analysis to evaluate the seismic performance of the buckling-restrained braced frame by applying SSMA to bracing.
반우호,김경훈,김형우,신아영,김주상,안중현,하직환 대한결핵 및 호흡기학회 2018 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.126 No.-
Purpose: Medical thoracoscopic talc pleurodesis is one of the most useful techniques for management of malignant pleural effusion (MPE). This study aimed to analyze the clinical feasibility and utility of medical thoracoscopic talc pleurodesis with patients with MPE. Methods: From May 2015 to May 2018, a retrospective study was conducted in Incheon St. Mary’s hospital, The Catholic University of Korea. Patients with MPE who underwent medical thoracoscopic talc pleurodesis were enrolled in the study. Clinical characteristics and outcomes were investigated. Results: Talc pleurodesis were performed in 30 patients. Non-small cell lung cancer (83%) was the most common cause of MPE. The mean procedure duration was 55 minutes. The median doses of fentanyl and midazolam were 100 μg and 2.5 mg. Twenty patients (66%) complained chest pain during pleurodesis, additional analgesics were administered in 18 cases (60%). Procedure-related complications were observed in 18 cases (60%). Subcutaneous emphysema (36.7%) and pneumothorax (23.3%) were frequently occurred. However, procedure-related complications were relatively mild and self-limiting. The median follow up duration was 180 days. Recurrence of effusion after pleurodesis was observed in 4 patients (13.3%). Conclusion: Medical thoracoscopic talc pleurodesis is a relatively safe and effective method for the control of MPE.
반우호,김형우,신아영,김주상,안중현,하직환 대한결핵 및 호흡기학회 2017 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.124 No.-
Purpose: Medical thoracoscopy (MT) has emerged as a minimally invasive technique for exploration of pleural space with conscious sedation and local anesthesia. Pleural nodules on computed tomography (CT) strongly suggest malignant pleural effusion (MPE). However, the association between the presence of pleural nodules on CT and MT findings in patients with suspicious MPE has not been studied well. Methods: A retrospective study was conducted in Incheon St. Mary’s hospital, The Catholic University of Korea. Patients who underwent MT suspecting MPE were classified into two groups according to pleural nodularity on CT scan. Clinical parameters including pleural fluid analysis and imaging findings on CT and MT were reviewed and diagnostic yield were analyzed between two groups. Results: Among 47 patients, pleural nodules on CT scan were detected in 26 patients. Other CT findings about pleura and parenchymal lesions were not significantly different between two groups. Pleural nodule or mass on MT were more frequently observed in the pleural nodule on CT positive group and the diagnostic accuracy was higher compared to the pleural nodule on CT negative group. Although, detection rate of pleural nodules on MT and diagnostic accuracy were estimated more than 50% in the CT negative group. Conclusion: MT is a useful method in suspected MPE, especially in patients with pleural nodule on CT scan. However, even in cases without pleural nodularity on conventional imaging, it could be an efficient method for improving proper diagnosis in suspected MPE.