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Sensor Network for Pipeline Leakage Detection in Nuclear Power Plant
Wonjune Lee(이원준),Sunghyun Cho(조성현) 대한전자공학회 2017 전자공학회논문지 Vol.54 No.12
원자력 발전소 매설 배관은 시설 노후화로 인한 누수를 피하기 어렵다. 매설 배관의 누수는 경제적 손실 및 인명 피해로 이어질 수 있기 때문에 실시간 누수 탐지 시스템은 매우 중요하다. 기존 전통적인 누수 탐지 시스템은 대부분 누수 탐지 도구등을 활용하여 작업자가 일일이 확인하는 방법이었다. 이에 본 논문에서는 매설 배관 누수를 실시간으로 자동 탐지할 수 있는 센서 네트워크 시스템을 제안한다. 배관의 누수를 탐지하는 기존의 대표적 방법은 두 가지가 있다. 첫 째는 청음봉을 이용한 물리적 방법이고 다른 하나는 배관 양단의 센서로부터 진동 신호를 수신하여 상호상관함수를 계산하여 누수를 탐지하는 방법이다. 그러나 두 가지 방법 모두 실시간에 탐지에 취약하고 전문지식이 있는 전문가가 필요하다는 단점이 있다. 이를 해결하기 위해서 다양한 연구가 진행되었으나 대부분 복잡한 필터링 알고리즘이 필요하여 실시간 시스템에 사용하기에 부적합한 단계이다. 본 논문에서는 앞서 살펴본 문제점들을 해결하기 위해 향상된 누수탐지 방법을 기반으로 한 지능형 센서 네트워크 구조를 제안한다. 제안하는 방법의 성능 분석을 위해 실제 구축한 필드 테스트 및 시뮬레이션을 진행하였다. 시뮬레이션 및 필드 테스트에서는 다양한 형태의 네트워크 토폴로지에 대해 누수 탐지 데이터 전송 지연 및 패킷 전송 성공률 등을 측정하였다. 시뮬레이션 결과 네트워크 그리드 크기가 5 이하일 경우에는 선형 네트워크 구조가 더 유리하였고 네트워크 그리드 크기가 5보다 큰 경우에는 애드-혹 네트워크 구조가 전송 지연 감소에 더 유리함을 보였다. It is important to apply real-time remote sensing system for premature pipeline leakage detection of nuclear power plant because of economic damage and human injury due to leakage. There are two typical methods to detect pipeline leakage. One is the physical method using acoustic rod and the other is cross-correlation method by receiving vibration signals from sensors at both ends. In the former method, it needs a specialist with expertise in listening and is hard to process in real-time. The latter method is greatly vulnerable to noise signals. There are a lot of efforts to solve the limitation. However, most of the methods proposed so far are not suitable for practical systems because those require additional filtering algorithms. The filtering algorithms are difficult to process in real time and thus not suitable for nuclear power plants. In order to solve the above problems, we propose an intelligent sensor network system based on the leakage detection with improved cross-correlation function. For the performance evaluation, we implement the testbed and simulation. The field test and simulation results show that the ad-hoc structure is superior than the linear structure when the grid size is less than 5, whereas the linear structure is more advantageous when the grid size is greater than 5.
Movement-Aware Vertical Handoff of WLAN and Mobile WiMAX for Seamless Ubiquitous Access
Wonjun Lee,Eunkyo Kim,Joongheon Kim,Inkyu Lee,Choonhwa Lee IEEE 2007 IEEE transactions on consumer electronics Vol.53 No.4
<P>This paper addresses a movement-aware vertical (MAV) handover algorithm between WLAN and Mobile WiMAX for seamless ubiquitous access. An MAV handover algorithm is proposed in this paper to exploit movement pattern for avoiding unnecessary handovers in the integrated WLAN and Mobile WiMAX networks. If a mobile station (MS)'s velocity is high and its movement pattern is irregular, unnecessary handovers likely occur more frequently. Therefore, the MS velocity and moving pattern are important factors for the handover decision procedure. To avoid unnecessary handovers, the MAV handover algorithm adjusts the dwell time adaptively and predicts the residual time in the cell of target base station (BS). Consequently, the adaptive dwell timer of MAV handover algorithm allows an MS a better connection as long as possible. Our simulation results show that the reduction of unnecessary handovers by leads to significant throughput improvements.</P>
Cross-Domain Service Composition in OSGi Environments
LEE, Choonhwa,LEE, Seungjae,KIM, Eunsam,LEE, Wonjun The Institute of Electronics, Information and Comm 2009 IEICE transactions on information and systems Vol.92 No.6
<P>This letter presents a new approach to provide inter-domain service compositions for OSGi environments. Our proposal of remote wire objects extends OSGi's wiring capability across the framework boundaries, so that even remote services can join in the composition. Hence, a better composition is made possible with a richer set of candidate services from foreign domains.</P>
Lee, Wonjun,Lee, S.,Choi, K.-Y.,Lee, K.-J.,Kim, B.-J.,Suh, B. J.,Shin, S.,Park, T. American Physical Society 2017 Physical Review B Vol.96 No.22
<P>We report mu SR experiments on the ternary compounds Sm1-xLaxNiC2 (x = 0.85, 0.92, and 0.96), crossing from a ferromagnetic to a superconducting phase. Zero-field mu SR measurements of the ferromagnetic sample (x = 0.85) unveil a glassylike character of the ferromagnetically ordered state. At the putative quantum critical compound (x = 0.92), fluctuations of the Sm moments slow down below 2 K and remain dynamic down to 30 mK, showing persisting spin dynamics. Moreover, we find a time-field scaling (t/H-gamma) of the mu SR asymmetry function, evidencing quantum critical fluctuations. As to the superconducting material (x = 0.96), the muon spin-relaxation rate displays a gimel-like peak at T = 250 mK, indicating the coexistence of weak magnetism and filamentary superconductivity. Our results demonstrate that Sm1-xLaxNiC2 constitutes a model system for studying a ferromagnetic quantum critical point tuned by chemical pressure.</P>
Aliveness detection based on multispectral analysis for touchless fingerprint recognition
Wonjune Lee,Jungin Lee,Heeseung Choi,Jaihie Kim 대한전자공학회 2010 ICEIC:International Conference on Electronics, Inf Vol.1 No.1
Recently, several researches in touchless fingerprint recognition system has been carried out. However, the touchless system is still vulnerable to spoof attacks by artificial fingerprints. In this paper, we introduce an aliveness detection method with multispectral analysis in touchless fingerprint recognition system. Our fingerprint acquisition device includes green, yellow and red illuminations for capturing the fingerprint images. Multispectral properties, especially reflectance of finger are extracted from the acquired fingerprint images under the each of illuminations. These features which can discriminate between live and fake fingerprint images are used and Support Vector Machine (SVM) is applied to classify live and spoof fingerprint image. In our data set, proposed method achieved 0% EER (Equal Error Rate). The results show that our approach can provide an efficient and effective aliveness detection method in the touchless fingerprint image recognition system.
이원준(Wonjune Lee) 역사비평사 2016 역사비평 Vol.- No.117
As the Chinese Communists gained the upper hand in the civil war(1946-49) against the Nationalists, the party began to consider the matter of establishing a new state, and this consideration brought about a series of policy changes since early 1948. The formation of the CCP’s urban takeover policy was also the result of this changed situation. As a result, the takeover policy of the CCP was based on the ‘New Democracy Theory’, which formed the foundation of the their revolutionary stance at the time. From the example of the Beijing’s People’s Congress of All Circles, the CCP’s urban takeover policy fully reflected the aims of ‘the New Democratic Revolution’.
이원준 ( Lee Wonjun ),김민수 ( Kim Minsu ),웨이장 ( Wei Zhang ),이득행 ( Lee Deuckhang ) 한국구조물진단유지관리공학회 2021 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.25 No.1
건축물 내진설계기준(KDS 41 17 00)이 개정됨에 따라 지하구조물에 대한 내진설계는 필수적으로 수행되어야 한다. 현행실무에서 주로 사용하고 있는 지하연속벽의 경우 1차 벽체(Primary Wall)와 2차 벽체(Secondary Wall)가 합성될 수 없으며, 이에 따라서 현행 설계기준에 따라서 내진설계되기 어렵다. 이 연구에서는 PC(Precast concrete)공법에 적합한 다양한 수직접합상세를 개발하였으며, 이에 대한 실대형 실험을 수행하였다. 또한, 기존의 비합성 연속벽체와 제안된 PC공법의 내진성능을 비교 및 평가하였다.