• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.237-254
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• 2019

This paper presents an improved time series based damage detection approach with experimental verifications for detection, localization, and quantification of damage in shear-type structures under varying mass effects using output-only vibration data. The proposed method can be very effective for automated monitoring of buildings to develop proactive maintenance strategies. In this method, Auto-Regressive Moving Average models with eXogenous inputs (ARMAX) are built to represent the dynamic relationship of different sensor clusters. The damage features are extracted based on the relative difference of the ARMAX model coefficients to identify the existence, location and severity of damage of stiffness and mass separately. The results from a laboratory-scale shear type structure show that different damage scenarios are revealed successfully using the approach. At the end of this paper, the methodology limitations are also discussed, especially when simultaneous occurrence of mass and stiffness damage at multiple locations.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2008년도 추계학술발표대회
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• pp.1008-1011
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• 2008

본 논문에서는 PDA에서 지속적인 상대 거리 측정 모니터링 시스템을 제안하고자 한다. 제안하는 시스템은 GPS나 다른 값비싼 디바이스를 제외하고 PDA의 기본 사양인 802.11, 무선 랜, 마이크, 스피커를 이용한다. 802.11 무선 랜을 이용하여 거리 변화의 감지 및 변화에 따른 거리를 측정한다. 거리 변화 감지는 RSSI값을 이용하고 TCP 패킷과 UDP패킷을 이용하여 RTT를 계산하고 거리 측정을 하고 기존에 있던 시스템을 통합한다. 이러한 시스템 개발은 PDA와 같은 모바일 디바이스에서 공유를 통한 멀티미디어 서비스 및 재난 상황 같은 곳에서 위치 정보 파악을 위해서 이용 가능할 것이라 예상 된다.

• 한국해양공학회지
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• 제23권2호
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• pp.58-68
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• 2009

The increased use of unmanned underwater vehicles (UUV) has led to the development of alternative navigational methods that do not employ acoustic beacons and dead reckoning sensors. This paper describes a simultaneous localization and mapping (SLAM) scheme that uses range sonars mounted on a small UUV. A SLAM scheme is an alternative navigation method for measuring the environment through which the vehicle is passing and providing the relative position of the UUV. A technique for a SLAM algorithm that uses several ranging sonars is presented. This technique utilizes an unscented Kalman filter to estimate the locations of the UUV and surrounding objects. In order to work efficiently, the nearest neighbor standard filter is introduced as the data association algorithm in the SLAM for associating the stored targets returned by the sonar at each time step. The proposed SLAM algorithm was tested by experiments under various three degrees of freedom motion conditions. The results of these experiments showed that the proposed SLAM algorithm was capable of estimating the position of the UUV and the surrounding objects and demonstrated that the algorithm will perform well in various environments.

• 전자공학회논문지
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• 제54권3호
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• pp.108-118
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• 2017

본 논문은 수중 로봇 항법에 사용하기 위한 영상 소나 기반 SLAM (simultaneous localization and mapping) 방법을 제안하고, 성능 평가를 위해 실제 로봇에 탑재하여 실험한 내용을 소개한다. 일반적인 수중 항법은 관성 센서에서 출력되는 정보를 바탕으로 로봇의 위치 및 자세(x,y,z,${\phi}$,${\theta}$,${\psi}$)를 추정한다. 하지만, 장시간 주행할 경우 위치 오차의 누적으로 인하여 정확도가 감소하게 된다. 이에 본 논문에서는 영상 소나로부터 얻을 수 있는 외부 정보를 바탕으로 관성 항법의 위치 추정 성능을 높이고 지도 작성을 수행할 수 있는 SLAM 방법을 제안하고자 한다. 영상 소나를 위한 인공 표식물과 확률 기반 물체 인식 구조를 통해 인공 표식물의 인식 성능을 높이고, 이를 통해 얻게 된 인공 표식물의 위치 정보를 활용하여 관성 항법의 누적 오차를 줄이고자 한다. 항법 알고리즘으로는 확장형 칼만 필터(Extended Kalman Filter, EKF)를 적용하여 로봇의 위치 및 자세를 추정하고 지도를 작성한다. 제안한 방법은 선박해양플랜트연구소에서 보유 중인 수중 로봇 'yShark'에 탑재하여 대형 수조에서 실시간 검증을 수행하였다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2005년도 제30회 춘계학술대회
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• pp.68-70
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• 2005

To precisely localize target in prostate cancer, image-guided radiotherapy was performed using the $ExacTrac^{\circledR}$ x-ray system (Brainlab, Germany) with implanted markers. For three prostate cancer patients, three gold markers were implanted into prostate. Orthogonal portal images were acquired every treatment and CT scans were repeated 3～5 times during the course of treatment. After correcting setup errors calculated by the system, the position of the implanted markers and the distance between them were detected in daily portal images and in CT images, and analyzed retrospectively. Deviation of the relative position of the implanted markers and the distance between them were less than 1 mm in lateral, longitudinal, and vertical direction for three patients, both in portal images and CT images. This study reveals that image-guided radiotherapy using the $ExacTrac^{\circledR}$ system is useful to verify positioning errors and localize prostate target with implanted markers, reducing the planning target volume (PTV) margin as well as irradiation to rectum and bladder.

• 한국정밀공학회지
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• 제27권10호
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• pp.52-60
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• 2010

It is generally important to get a precise position information for autonomous unmanned vehicle(AUV) to run safely. For getting the position of AUV, the GPS has been using to navigation in a vehicle. Though it is useful to finding a position, it is difficult to precisely control a trajectory of the AUV due to large measuring error which may reach over 10 meters. Therefore to apply AUV it needs to compensate for the error. This paper proposes a method to more precisely localize AUV using three low-cost differential global positioning systems (DGPS). The distance errors between each DGPS are minimized as using the least square method (LSM) and the Kalman filter to eliminate a Gaussian white noise. The selected DGPS is cheaper and easier to set up than the RTK-GPS. It is also more precise than the general GPS. The proposed method can compensate the relatively position error according to stationary and moving distance of the AUV. For evaluating the algorithm by simulation, the DGPS signal with the Gaussian white noise to any points is generated by the AR model and compared with the measurement signal. It is confirmed that the proposed method can effectively compensate the position error as comparing with the measurement signal. The compensated position signal can be used to localize and control the AUV in the road.

• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.357-366
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• 1996

The present experiments aimed to investigate the metabolism of calcium during oocyte maturation in rat. The concentration of free calcium and calmodulin in oocytes was measured respectively by using of fluo-3/AM and FITC with microscope fluorescence spectrometer. The ultrastructural localization of calcium precipitates in oocytes was observed with the transmission electron microscope. Cumulus-free immature oocytes(GV-oocyte) were cultured in vitro through 15 hours. The free calcium concentration in GV oocyte was $55.9{\pm}3.5nM$. In calcium-containing medium, the free calcium concentration was increased in germinal vesicle breakdown(GVBD) oocyte($64.2{\pm}7.3nM$). In normal medium after calcium chelator treatment ($10{\mu}M$ BAPTA/AM), the free calcium contents were slightly lower than those in control group. In calcium-free medium, the free calcium content was drastically increased in GVBD($72.7{\pm}3.4nM$) and metaphase I - anaphase I ($88.0{\pm}3.4nM$) oocyte. In maturation rate of oocytes, GVBD rate was high in control group($82.9{\pm}6.55%$) and calcium chelator treatment group($91.2{\pm}4.4%$), but in calcium-free medium group, it was low and then the oocyte was degenerated without polar body formation. Relative content of calmodulin in oocyte was significantly(P<0.001) increased in metaphase I - anaphase I than in GV and GVBD oocyte. The calcium precipitates were observed in mitochondria and cytoplasm of GV oocyte but that were not observed in mitochondria of GVBD and metaphase I - anaphase I oocyte. And then the calcium precipitates reappeared in mitochondria of metaphase II oocyte. The above results indicate that changes in free calcium and calmodulin concentration of oocyte occur according to the maturational stages and the extracellular calcium is required during oocyte maturation. Also change of calcium localization in oocyte occurs according to the maturational stages.

• 한국의상디자인학회지
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• 제23권2호
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• pp.165-176
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• 2021

To solve environmental problems, research and efforts are required to reduce leather waste that is generated in large quantities during the leather manufacturing process. Leatherboard is a plate-like material that is made by crushing leather waste, such as trimming or shaving scraps and mixing fibers, pulp, rubber, and adhesives. The aim of this study is to provide basic data on the localization of leatherboard manufacturing technology for outsoles, which are increasingly in demand due to their excellent performance and price competitiveness. Interviews with experts and related organizations were conducted to investigate the related global technology trends. Also, the performance of three products that can be used as reference materials were evaluated and compared. As part of the research and efforts to reduce the amount of leather waste generated, high-performance materials using leather waste were developed and commercialized by major western companies. In Korea, various efforts have been made since 2000, and some companies have produced leatherboard for interior uses. However, the amount of waste recycled relative to that generated is not large due to the limited demand. Natural leather soles perform better than leatherboard soles in all evaluation aspects. In the case of leatherboard, performance varied by manufacturer. German products showed flexibility resistance and dimensional stability, thereby meeting performance requirements. However, abrasion resistance and cleavage resistance were slightly below the required performance standards, and research and development is needed to improve performance in those areas. Currently, it is impossible to evaluate the performance of domestic products due to underdevelopment. However, if the development of process technology continues based on the performance evaluation results of the best leatherboard in the shoe industry, materials for outsoles will be able to be produced domestically with prices competitiveness while realizing natural leather materials performance to some extent.

• Journal of Advanced Marine Engineering and Technology
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• 제37권2호
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• pp.220-226
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• 2013

최근 공장자동화 및 물류시스템의 발전은 대형선박이나 물류창고 등과 같은 넓은 작업현장을 소수의 작업자가 관리할 수 있게 되었다. 기존의 무선 실내 위치인식 시스템에서 이러한 작업자들의 정확한 위치를 추정하기 위해서 일반적으로 셋 또는 그 이상의 고정노드가 하나의 노드로 이루어진 이동노드의 위치를 인식하는 방식이 주로 사용되고 있다. 하지만 이러한 방법은 작업자(이동노드)에 비하여 넓은 작업현장에 많은 고정노드가 필요하므로 노드 배치 측면에서는 비효율적이다. 따라서 소수의 작업자를 요구하는 이러한 작업환경에서 효율적으로 노드를 배치하기 위하여 본 논문에서는 세 개의 노드로 구성된 이동노드가 고정노드 두 개의 상대좌표를 효율적으로 인식함으로써 고정노드의 개수를 저감하는 새로운 추정 알고리즘과 이동노드와 고정노드 사이의 거리오차를 최소화하기 위하여 Rounding estimation(RE) 기법을 제안한다. 실험 결과 제안한 RE기법은 자유공간에서 기존의 삼변측량법의 오차율 대비 90.9% 개선된 위치인식 결과를 나타냈다. 또한 실내 자유공간에서 고정노드 수를 최대 50%까지 감소시킬 수 있음에도 불구하고 제안한 추정 알고리즘은 평균 오차 0.15m의 정밀한 위치인식이 가능하였다.

• Spatial Information Research
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• 제21권2호
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• pp.35-43
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• 2013

본 연구는 U-City 서비스 지원기관이 'U-City 서비스 및 산업 활성화를 지원하는 기관'으로서의 역할을 수행하기 위하여 어떠한 기능에 우선순위를 두어야 하는지 분석하는 것을 목적으로 한다. 이를 위하여 관 산 학 연 전문가를 대상으로 AHP 방법을 활용하여 U-City 서비스 지원기관의 기능 영역과 기능 요소의 상대적 중요도와 우선순위를 분석하고, 민감도 분석을 실시하였다. 연구 결과, 기능 영역별 상대적 중요도는 1) U-City 서비스 관련 정보의 유통, 2) U-City 관련 제품 및 서비스의 품질인증, 3) U-City 기술의 연구개발, 4) U-City의 표준화, 5) U-City 전문인력 양성 순으로 나타났다. 기능 요소별 상대적 중요도는 1) U-City 정보 유통 추진체계 마련, 2) U-City 정보 유통을 위한 유통망 설치 운영, 3) U-City 정보 유통 및 가격 정책 수립 지원, 4) U-City 정보 유통 목록 제공, 5) U-City 제품 및 서비스의 품질인증 기준 마련 및 적용, 6) U-City 인증항목, 인증대상, 인증절차 등 제도연구, 7) U-City 정보 유통현황의 조사 분석 및 제공, 8) U-City에 구축된 인프라와 서비스 수준 평가, 9) U-City 관련 핵심원천기술의 개발 및 국산화, 10) U-City 수집 정보 및 서비스의 분류체계, 전달체계 등의 표준화 순으로 나타났다. 이러한 연구결과는 U-City 서비스 지원기관의 기능 설계에 직접적으로 반영할 수 있고, 직무 조정과 인력 배치, 재원 배분 등에 활용될 수 있을 것이다.