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장병욱,한경덕,장경수,신동렬 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.1
Advances in computer and communications technology have been successfully applied by power utilities in the development of information systems. Many of these systems are dedicated to meeting the specific needs of particular utility functions. Furthermore these systems have evolved based on proprietary communication protocols and thus been operated on various vendor-specific platform. These characteristics make communications between systems difficult, complex, and costly. In order to promote and facilitate interoperability between computer systems supplied to the electric utility industry, EPRI(Electric Power Research Institute) initiated the new standard protocol called ICCP(Inter-Center Control Communications Protocol) which specified the use of MMS(Manufacturing Message Specification) for use of in utility field devices or communication between control centers. This paper addresses the characteristics, modeling and implementation of objects associated with ICCP and MMS.
라미부딘 내성 만성 B형 간염 환자에서의 아데포비어의 치료 효과
이지숙,장리라,이상욱,한병훈,윤병철 고신대학교의과대학 2008 고신대학교 의과대학 학술지 Vol.23 No.2
Backgrounds/Aims : Adefovir dipivoxil(ADV) has been shown to be effective against lamivudine resistant strain of hepatitis B virus. But continuation of lamivudine therapy or switching to Adefovir dipivoxil in patients with viral breakthrough after long term lamivudine therapy are controversial. To find efficacy of adefovir dipivoxil, we retrospectively assessed clinical course after lamivudine resistance in patients who changed adefovir dipivoxil and continued lamivudine therapy. Methods : 58 patients with lamivudine resistant HBV mutants after at least 6 months of lamivudine treatment were included in this study. 24 of the 58 patients were treated with ADV and rest of them were continued the lamivudine therapy after lamivudine resistance. The continuous lamivudine treatment group (n=34) was divided into two groups according to ALT count (ALT≧40, n=19 vs ALT<40, n=16) The clinical course and the biochemical and virological response of the switching adefovir group were compared with those of continuing lamivudine group. HBV genotypes and YMDD mutation site was anaylzed by TRUGENE HBV Genotyping. Results : At twelve months, the levels of median serum HBV DNA and ALT was decreased and albumin was improved significantly(P<0.01) in adefovir switching group compared with lamivudine sustained group, especially ALT was elevated more than 40. There is no significant differences between adefovir switching group and lamivudine sustained group (ALT<40, n=15). This study showed that adefovir dipivoxil reduces HBV replication and improves not only biochemical markers of disease activity, but also liver function. HBV genotypes of 58 patients were all C and rtM204I/V mutant was the most common. Conclusion : This study provides an evidence that adefovir dipivoxil can be effective in the treatment of lamivudine-resistant HBV mutants, especially ALT elevated.
Impact source localization for composite structures under external dynamic loading condition
Jang, Byeong-Wook,Lee, Yeon-Gwan,Kim, Chun-Gon,Park, Chan-Yik The Korean Society for Composite Materials 2015 Advanced composite materials Vol.24 No.4
This paper suggests a real-time impact localization algorithm for a stiffened composite structure using acoustic emission signals acquired by multiplexed fiber Bragg grating (FBG) sensors. The suggested algorithm requires a database composed of premeasured impact signals at all training points to be used as reference signals. Once the FBG signals were measured from an arbitrary impact event, the root mean-squared (RMS) values were calculated between the obtained signals and all reference signals. Then, the training point that has the minimum RMS values was determined as the resultant impact location. In order to validate the applicability of this algorithm in the external environment, impact localization was performed under a dynamic loading condition. The dynamic loading condition was simulated by exciting the test article using a shaker. The results of validation tests show that the proposed algorithm could successively estimate the impact locations under a dynamic loading condition.
Jang, Byeong-Wook,Kim, Chun-Gon Elsevier 2018 Composite structures Vol.189 No.-
<P><B>Abstract</B></P> <P>Low-velocity impact is the one of the most critical events to reduce the reliability of composite structures, because it can generate hidden damages such as delamination inside the structures. In order to address this problem, impact monitoring systems have been suggested using various types of built-in sensors. Generally, such impact monitoring systems are consisted of impact localization and damage assessment. In this paper, a methodology of impact-induced delamination assessment was studied using fiber Bragg grating (FBG) sensors. Because of its multiplexing capability, FBG sensors are advantageous of monitoring large areas of target structures. However, it is hard to be applied in impact monitoring systems due to its low sensitivity and narrow bandwidth. In this study, a quantification method of delamination was examined with maintaining the merits of FBG sensors. For the acquisition of impact-generated acoustic emission (AE) signals, the commercial FBG system was adopted with a sampling frequency of 100 kHz. Then, the acquired AE signals during the low-velocity impact fracture tests were analyzed with the wavelet transform (WT) method for measuring the delamination areas due to different energies. Finally, it can be concluded that the quantities of WT detailed portions are linearly correlated with the delamination areas.</P>
멀티콥터 초기 사이징을 위한 기체 구조 중량 예측 기법
장병욱(Byeong-Wook Jang),황인성(In-Seong Hwang),김민우(Minwoo Kim),이보성(Bosung Lee),정용운(Yongwun Jung),강왕구(Wanggu Kang) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.9
20kg 미만의 중소형 멀티콥터의 초기 사이징 과정에서 적용 가능한 기체 구조 중량 예측에 관한 연구를 소개한다. 임무장비를 제외하고 멀티콥터는 기체 구조, 모터, 프로펠러, 배터리 등으로 구성되는데, 모터, 프로펠러, 배터리 등의 중량은 설계변수에 따른 추세선을 통해 추정이 가능하다. 하지만 기체 구조 중량은 멀티콥터의 형상과 설계 개념이 다양하고, 대부분의 상용 제품들이 기체 구조 중량 데이터를 제공하지 않기 때문에 추세선을 통해 예측할 수 없다. 본 논문에서는 기본적인 멀티콥터 형상을 정의하고 멀티콥터 사이징 초기단계에서 결정되는 프로펠러 개수와 직경을 통해 멀티콥터 기체 구조 중량을 추정하는 방법을 제안하였다. 제안한 방법은 구조 중량이 제시된 멀티콥터 제품들을 통해 검증하여 그 유용성을 확인하였다. A structural weight estimation methodology for the multicopter design process is presented. In general, a multicopter is composed of an airframe, motors, propellers, battery and so on. Among these, the weight of motors, propellers and battery can be obtained from the weight trends with respect to design parameters. However, the structural weight is hard to be estimated due to the various configurations and design concepts of multicopters. Moreover, the airframe weights of most commercial multicopter products are not provided. Thus, an accurate airframe weight model is required for the reliable mutlcopter design process. Firstly, the standard configuration of multicopters is defined. Then, we proposed the structural weight estimation method using the number and diameter of propellers determined from the initial step of sizing process. Finally, we validated our suggested method using the commerical products.
광섬유 브래그 격자 센서를 이용한 복합재 구조물의 충격 모니터링 기법 연구
장병욱 ( Byeong Wook Jang ),박상오 ( Sang Oh Park ),이연관 ( Yeon Gwan Lee ),김천곤 ( Chun Gon Kim ),박찬익 ( Chan Yik Park ),이봉완 ( Bong Wan Lee ) 한국복합재료학회 2011 Composites research Vol.24 No.1
복합재 구조물에서 발생하는 저속 충격에 의한 손상은 대부분 복합재의 내부나 충격을 받은 면의 반대 면에서 발생하기 때문에 검출이 쉽지 않아 시간이 지날수록 구조물이 위험에 처할 확률이 높아진다. 하지만 기존의 비파괴검사 방법은 일정한 주기에 따라 수행되기 때문에 즉각적으로 충격 손상을 감지할 수 없다는 단점이 있다. 따라서 최근에는 이러한 단점을 극복하고자 비파괴검사 장비를 구조물 내에 탑재하여 실시간으로 구조물의 건전성을 확인하는 개념인 구조 건전성 모니터링에 관한 연구가 활발히 진행되고 있다. 그 중의 하나인 충격 모니터링 시스템은 운용 중에 발생한 충격 이벤트를 감지하고 그 위치 및 손상 정도에 대한 정보를 제공해 주어야 한다. 이를 위한 첫 번째 단계로 본 연구에서는 복합재 평판 및 복잡한 복합재 시편 구조물에 FBG센서를 부착하여 충격 위치 검출 시험을 수행하였고, 이와 같은 복합재 시편에 대해 충격 파손 시험을 수행하여 손상 발생 유무를 예측하는 시험을 수행하였다. 저속 충격에 의해 발생하는 음향 파는 ㈜파이버프로에서 개발한 고속 FBG interrogator를 사용하여 4개의 다중화된 FBG 센서로부터 동시에 취득하였고, 신경회로망을 이용한 학습을 거쳐 충격 발생 위치를 검출하였다. 또한 충격 파손 시험으로부터 취득한 음향 파의 웨이블릿 변환을 통해 충격 손상의 발생 유무 예측 가능성을 확인하였다. Low-velocity impact can cause various damages which are mostly hidden inside the laminates or occur in the opposite side. Thus, these damages cannot be easily detected by visual inspection or conventional NDT systems. And if they occurred between the scheduled NDT periods, the possibilities of extensive damages or structural failure can be higher. Due to these reasons, the built-in NDT systems such as real-time impact monitoring system are required in the near future. In this paper, we studied the impact monitoring system consist of impact location detection and damage assessment techniques for composite flat and stiffened panel. In order to acquire the impact-induced acoustic signals, four multiplexed FBG sensors and high-speed FBG interrogator were used. And for development of the impact and damage occurrence detections, the neural networks and wavelet transforms were adopted. Finally, these algorithms were embodied using MATLAB and LabVIEW software for the user-friendly interface.