• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.425-427
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• 2004

Many of the problems by using the microscope are related to the fact that the eyes of the surgeon must be continually fixed to the microscope eyepieces. In this paper, we describe a development of the stereoscopic monitoring system of the stereo microscope for reduced eyestrain or operator fatigue about the long time observations of the microscope. The system consists of the stereoscopic camera part, the stereoscopic image processor device and the polarized light stereoscopic monitor. The left and right images obtained form the two CCD cameras are the same as the eyepiece images. By use of the image processor, the polarized light stereoscopic monitor displayed a real-time stereo microscope images.

• 국제초고층학회논문집
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• 제1권1호
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• pp.37-51
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• 2012

New generation of tall and complex buildings systems are now introduced that are reflective of the latest development in materials, design, sustainability, construction, and IT technologies. While the complexity in design is being overcome by the availability and advances in structural analysis tools and readily advanced software, the design of these buildings are still reliant on minimum code requirements that yet to be validated in full scale. The involvement of the author in the design and construction planning of Burj Khalifa since its inception until its completion prompted the author to conceptually develop an extensive survey and real-time structural health monitoring program to validate all the fundamental assumptions mad for the design and construction planning of the tower. The Burj Khalifa Project is the tallest structure ever built by man; the tower is 828 meters tall and comprises of 162 floors above grade and 3 basement levels. Early integration of aerodynamic shaping and wind engineering played a major role in the architectural massing and design of this multi-use tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria established at the onset of the project design. Understanding the structural and foundation system behaviors of the tower are the key fundamental drivers for the development and execution of a state-of-the-art survey and structural health monitoring (SHM) programs. Therefore, the focus of this paper is to discuss the execution of the survey and real-time structural health monitoring programs to confirm the structural behavioral response of the tower during construction stage and during its service life; the monitoring programs included 1) monitoring the tower's foundation system, 2) monitoring the foundation settlement, 3) measuring the strains of the tower vertical elements, 4) measuring the wall and column vertical shortening due to elastic, shrinkage and creep effects, 5) measuring the lateral displacement of the tower under its own gravity loads (including asymmetrical effects) resulting from immediate elastic and long term creep effects, 6) measuring the building lateral movements and dynamic characteristic in real time during construction, 7) measuring the building displacements, accelerations, dynamic characteristics, and structural behavior in real time under building permanent conditions, 8) and monitoring the Pinnacle dynamic behavior and fatigue characteristics. This extensive SHM program has resulted in extensive insight into the structural response of the tower, allowed control the construction process, allowed for the evaluation of the structural response in effective and immediate manner and it allowed for immediate correlation between the measured and the predicted behavior. The survey and SHM programs developed for Burj Khalifa will with no doubt pioneer the use of new survey techniques and the execution of new SHM program concepts as part of the fundamental design of building structures. Moreover, this survey and SHM programs will be benchmarked as a model for the development of future generation of SHM programs for all critical and essential facilities, however, but with much improved devices and technologies, which are now being considered by the author for another tall and complex building development, that is presently under construction.

• Structural Engineering and Mechanics
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• 제74권2호
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• pp.157-173
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• 2020

In the finite element modelling of long-span cable-stayed bridges, there are a lot of uncertainties brought about by the complex structural configuration, material behaviour, boundary conditions, structural connections, etc. In order to reduce the discrepancies between the theoretical finite element model and the actual static and dynamic behaviour, updating is indispensable after establishment of the finite element model to provide a reliable baseline version for further analysis. Traditional sensitivity-based updating methods cannot support updating based on static and dynamic measurement data at the same time. The finite element model is required in every optimization iteration which limits the efficiency greatly. A convenient but accurate Kriging surrogate model for updating of the finite element model of cable-stayed bridge is proposed. First, a simple cable-stayed bridge is used to verify the method and the updating results of Kriging model are compared with those using the response surface model. Results show that Kriging model has higher accuracy than the response surface model. Then the method is utilized to update the model of a long-span cable-stayed bridge in Hong Kong. The natural frequencies are extracted using various methods from the ambient data collected by the Wind and Structural Health Monitoring System installed on the bridge. The maximum deflection records at two specific locations in the load test form the updating objective function. Finally, the fatigue lives of the structure at two cross sections are calculated with the finite element models before and after updating considering the mean stress effect. Results are compared with those calculated from the strain gauge data for verification.

• The Journal of Korean Physical Therapy
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• 제18권1호
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• pp.1-10
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• 2006

Purpose: This study was to investigate how induced microcurrent shoes affect relief of feet pain, which often occurs to persons who are more than fifty years old and how they prevent fatigue of feet generated during everyday life. The subjects of this study were comprised af five males and five females, who agreed with this research and ate more than fifty years old. And they all have plantar faciitis and pain in their feet. Methods: Subjects ware the induced microcurrent shoes far more than 4 hours everyday during the test. When they wore those shoes, they also wore the specially produced shacks made of silver-mixed thread and they were asked to avoid serious exercise. Prior to starting test and after the test, assessments were carried out two times. In the examination before the test, general shoes were used and in examination after the test, induced microcurrent shoes used. Muscle fatigue was measured by electromyography(MP150, Biopac, USA). When the walking rate of subjects on a treadmill was increased from 2.Km/h to 3Km/h for 10 minutes, muscle activities of a lower leg were measured during the whale walking process by MP150 remote monitoring system(TEL 100C). And pain was measured by VAS. Results: The results are as follows. 1. Comparisons of VAS before and after experimentation showed that degree of pain was significantly decreased(p < .05). 2. Degree of fatigue of Tibialis anterior was significantly decreased after 6 weeks of treatment(p < .05). 3. Degree of fatigue of Soleus was slightly decreased after 6 weeks of treatment, but did not show significant difference (p > .05). Conclusion: The above results suggest that induced microcurrent shoes is helpful decreasing fatigue of feet and relief of feet pain.

• 항공우주시스템공학회지
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• 제8권4호
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• pp.7-17
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• 2014

Objective of this paper is to introduce a new technology known as prognostics and health management (PHM) which enables a real-time life prediction for safety critical systems under extreme loading conditions. In the PHM, Bayesian framework is employed to account for uncertainties and probabilities arising in the overall process including condition monitoring, fault severity estimation and failure predictions. Three applications - aircraft fuselage crack, gearbox spall and battery capacity degradation are taken to illustrate the approach, in which the life is predicted and validated by end-of-life results. The PHM technology may allow new maintenance strategy that achieves higher degree of safety while reducing the cost in effective manner.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1011-1016
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• 2015

Gas piping systems in power plants and factories are always influenced by the mechanical vibrations of rotational machines such as pumps, blowers, and compressors. Unusual vibrations in a gas piping system influence possible leakages of liquids or gases, which can lead to large explosive accidents. Real-time measurements of unusual vibrations in piping systems in situ prohibit them from being possible leakages owing to the repeated fatigue of vibrations. In this paper, a non-contact 3-dimensional measurement system that can detect the vibrations of a solid body and monitor its vibrational modes is introduced. To detect the displacements of a body, a stereoscopic camera system is used, through which the major vibration types of solid bodies (such as X-axis-major, Y-axis-major, and Z-axis-major vibrations) can be monitored. In order to judge the vibration types, an artificial neural network is used. The measurement system consists of a host computer, stereoscopic camera system (two-camera system, high-speed high-resolution camera), and a measurement target. Through practical application on a flat plate, the measured data from the non-contact measurement system showed good agreement with those from the original vibration mode produced by an accelerator.

• 한국강구조학회 논문집
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• 제23권2호
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• pp.159-167
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• 2011

최근 강구조물의 건설이 지속적으로 증가되고 있고, 이에 따른 모니터링 시스템의 중요성이 더욱 부각되고 있는 실정이다. 강구조물의 노화로 인한 피로균열 및 부식은 강구조물의 수명저하에 가장 큰 요인이 된다. 구조물이 큰 교량의 경우에는 사람의 접근이 어렵고, 균열 측정 방법 또한 시간이 오래 걸리며, 많은 비용이 소비된다. 따라서, 초기에 균열을 발견하고 보수, 보강 작업을 수행함으로써 비용을 절감할 수 있는 모니터링 시스템의 개발이 절실히 요구된다. 본 연구에서는 강부재의 전위차법(EPDM : Electric Potential Drop Method)에 의한 모니터링 기법에 의해 쉽게 관찰되지 않는 피로균열의 발생 및 진전 상황을 추적하고 또한 잔여수명을 예측하였다.

• 한국정보통신학회논문지
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• 제14권10호
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• pp.2317-2323
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• 2010

근경직으로 인한 질병을 판단하기 위한 새로운 비침습적 초음파 근경직도 측정 시스템을 검증하기 위해 근경직 발생시 근전도의 변화를 분석하였다. 근경직 유발을 위해 하지 대퇴직근에서 등척성 운동을 실시하였다. 실험 프로토콜에 따라 실험을 반복 실시하였다. 이때 바이오시스템3를 이용하여 무릎관절토크의 크기 및 토크를 실시간으로 측정하였다. 또한 대퇴직근에서 근전도 측정 시스템으로 근전도를 측정하였다. 피검자는 실험 프로토콜에 따라 최초 무릎관절 토크의 최대수의적 등척성수축(MVC : maximal voluntary contraction)을 측정하고,. MVC의 50%에서 -5%로 떨어질때까지 등척성 운동을 지속하였다. 근경직 유발시 근전도 신호를 신호처리 과정을 거쳐 중앙주파수변동과 실효값 변화로 나타내었으며, 이러한 결과가 근경직도 측정 시스템의 결과와 유의함을 보였다.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.809-824
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• 2017

The accurate evaluation of wind characteristics and wind-induced structural responses during a typhoon is of significant importance for bridge design and safety assessment. This paper presents an expectation maximization (EM) algorithm-based angular-linear approach for probabilistic modeling of field-measured wind characteristics. The proposed method has been applied to model the wind speed and direction data during typhoons recorded by the structural health monitoring (SHM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. In the summer of 2015, three typhoons, i.e., Typhoon Chan-hom, Typhoon Soudelor and Typhoon Goni, made landfall in the east of China and then struck the Jiubao Bridge. By analyzing the wind monitoring data such as the wind speed and direction measured by three anemometers during typhoons, the wind characteristics during typhoons are derived, including the average wind speed and direction, turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD). An EM algorithm-based angular-linear modeling approach is proposed for modeling the joint distribution of the wind speed and direction. For the marginal distribution of the wind speed, the finite mixture of two-parameter Weibull distribution is employed, and the finite mixture of von Mises distribution is used to represent the wind direction. The parameters of each distribution model are estimated by use of the EM algorithm, and the optimal model is determined by the values of $R^2$ statistic and the Akaike's information criterion (AIC). The results indicate that the stochastic properties of the wind field around the bridge site during typhoons are effectively characterized by the proposed EM algorithm-based angular-linear modeling approach. The formulated joint distribution of the wind speed and direction can serve as a solid foundation for the purpose of accurately evaluating the typhoon-induced fatigue damage of long-span bridges.

• 한국콘텐츠학회논문지
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• 제11권6호
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• pp.26-32
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• 2011

최근 U-health 분야에서는 EEG(Electroencephalograph) 뇌파를 전송하여 환자뿐만 아니라 일반 노약자를 대상으로 졸음운전이나 뇌졸중, 또는 심장마비와 같은 위기상황에 대처하기 위해 실시간으로 뇌파를 모니터링하는 시스템을 연구하고 있다. 이러한 시스템은 병원이나 요양원등 다양한 지역에 적용할 수 있다. 본 논문에서는 자동차 통신망에 적용하여 운전자의 뇌파를 실시간으로 모니터링하고 미연에 사고를 방지할 수 있는 통신망 시스템의 성능을 평가하고자 한다. 이를 위해 VANET환경에서 EEG뇌파 전송을 효율적으로 할 수 있도록 옵넷 시뮬레이터에서 제공하는 모바일 애드혹 노드를 사용하였다. 운전자의 뇌파를 노변기지국으로 전송하는 애드혹한 자동차 통신망을 설계하고 시뮬레이션을 통하여 도심 지역에 적합한 환경을 도출하였다.