• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2797-2802
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• 2007

It has been confirmed that implementation of the no-slip boundary conditions for the lattice-Boltzmann method play an important role in the overall accuracy of the numerical solutions as well as the stability of the solution procedure. We in this paper propose a new algorithm, i.e. the method of the dynamic boundary condition for no-slip boundary condition. The distribution functions on the wall along each of the links across the physical boundary are assumed to be composed of equilibrium and nonequilibrium parts which inherit the idea of Guo's extrapolation method. In the proposed algorithm, we apply a dynamic equation to reflect the computational slip velocity error occurred on the actual wall boundary to the correction; the calculated slip velocity error dynamically corrects the fictitious velocity on the wall nodes which are subsequently employed to the computation of equilibrium distribution functions on the wall nodes. Along with the dynamic selfcorrecting process, the calculation efficiently approaches the steady state. Numerical results show that the dynamic boundary method is featured with high accuracy and simplicity.

• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.27-33
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• 2013

Nowadays, the utilization of renewable energy sources like wind energy is considered one of the most effective means of generating massive amounts of electricity. This is evident in the rapid increase of wind farms all over the world which comprise a huge number of wind turbines. However, the drawback of utilizing wind turbines is that it requires maintenance, which could be a costly operation. To keep the wind turbines in pristine condition so as to reduce downtime, the implementation of CMS (Condition Monitoring System) and FDS (Fault Detection System) is mandatory. The efficiency and accuracy of these systems are crucial in deciding when to carry out a maintenance process. In this paper, a fault detection system based on intelligent clustering method is proposed. Using SCADA data, the clustering model was trained and evaluated for its accuracy through rigorous simulations. Results show that the proposed approach is able to accurately detect the deteriorating condition of a wind turbine as it nears a downtime period.

• 한국전자통신학회논문지
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• 제6권6호
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• pp.987-991
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• 2011

본 논문에서는 인체의 운동 변화를 홈 네트워크 방식으로 측정하고 확인할 수 있는 헬스 케어 시스템을 구현하였다. 제안되는 시스템은 트레드밀 운동 또는 사이클 운동 자세에서, 그 운동의 변화에 따라 신호 전달 장치를 통하여 실시간으로 전달되는 생체 신호를 데이터 획득 장치를 통하여 얻고, 그 데이터를 분석 장치에서 논리적으로 분석하여 자세에 대한 평가를 할 수 있도록 구성하였다. 측정파라미터의 항목을 혈압(Blood Pressure), 온도(Temperature), 낙상(Fall Index), 무게분포도(WDI), 체질량지수(BMI) 등으로 함으로서 측정값을 통하여 신체적 변화정도를 확인하고, 신체의 상태를 평가할 수 있도록 감시 체제를 구성하였다.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2185-2191
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• 2012

기존의 인버터에 대한 모니터링은 로컬컴퓨터나 웹 모니터링 등을 이용하여 모니터링을 하고 있다. 그러나 본 논문에서는 블루투스 통신을 이용하여 사용자가 편리한 위치에서 컴퓨터를 사용하지 않고도 태양광 인버터를 원격 모니터링 가능한 시스템을 구현하였다. 제안한 시스템은 인버터 프로토콜을 이용하여 인버터의 원하는 정보를 무선 통신으로 모니터링 할 수 있게 설계 하였다. 또한 태양광 인버터의 고장시 블루투스 고장이력과 시각을 기록할 수 있도록 하였다. 마지막으로 본 논문에서 제안한 시스템이 실험을 통해 좋은 성능을 보여주었고 또한 상용화의 가능성을 제시해 주었다.

• 한국정밀공학회지
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• 제34권1호
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• pp.19-22
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• 2017

This paper describes the efficient equipment maintenance that can offer the exact time for repair and change of component in root industry. A conventional method offered the fixed time for repair and change of component because the method is based on early guarantee specification of the component. However the operating condition of manufacturing field is often under worse condition than early guarantee condition for high productivity. So, most components can't use until early guarantee time due to the operation of various different condition. Therefore we suggest the useful method for efficient equipment-maintenance by manufacturing-field analysis and feedback database. For this, the classification of root industry and related equipment is performed and then the detail classification of the process and component for equipment maintenance. And the monitoring module is also designed to gather data for feedback process and the environment is basically implemented for aging and reliability test.

• International Journal of Contents
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• 제16권3호
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• pp.1-17
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• 2020

Human motion recognition is essential for user-centric services such as surveillance-based security, elderly condition monitoring, exercise tracking, daily calories expend analysis, etc. It is typically based on the movement data analysis such as the acceleration and angular velocity of a target user. The existing motion recognition studies are only intended to measure the basic information (e.g., user's stride, number of steps, speed) or to recognize single motion (e.g., sitting, running, walking). Thus, a new mechanism is required to identify the transition of single motions for assessing a user's consecutive motion more accurately as well as recognizing the user's body and surrounding situations arising from the motion. Thus, in this paper, we collect the human movement data through Android smartphones in real time for five targeting single motions and propose a mechanism to recognize a consecutive motion including transitions among various motions and an occurred situation, with the state transition model to check if a vulnerable (life-threatening) condition, especially for the elderly, has occurred or not. Through implementation and experiments, we demonstrate that the proposed mechanism recognizes a consecutive motion and a user's situation accurately and quickly. As a result of the recognition experiment about mix sequence likened to daily motion, the proposed adoptive weighting method showed 4% (Holding time=15 sec), 88% (30 sec), 6.5% (60 sec) improvements compared to static method.

• 한국환경복원기술학회지
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• 제8권6호
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• pp.45-58
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• 2005

The objective of this study is to the integrated evaluation of the present condition and satisfaction of visitors of rooftop greening area using quantitative and qualitative method. The thirteen green roofs were selected to investigate environmental variables as like building structure, soil, water, atmosphere and climate environment and questionnaire survey for investigate the satisfaction of visitors was conducted. The results of this study are as follows : remove of the hazardous inflow of species, install rain water recycling facility, install outdoor unit of air condition where not to affect plants in green roof, install safety facilities in the case of making resting place, plant variable vegetation and so on. The result of questionnaire survey are that visitors want to make more comfortable resting space. The more bigger the resting space and privacy, the more satisfaction of visitor became high. In conclusion, green roofs implementation should be considered reduction of temperature and delay of runoff, insulation effect and ecological restoration as well as rooftop greening is focused on the development of resting space nowadays.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.737-752
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• 2014

As condition-based maintenance (CBM) has risen as a new trend, there has been an active movement to apply information technology for effective implementation of CBM in power plants. This motivation is widespread in operations and maintenance, including monitoring, diagnosis, prognosis, and decision-making on asset management. Thermal efficiency analysis in nuclear power plants (NPPs) is a longstanding concern being updated with new methodologies in an advanced IT environment. It is also a prominent way to differentiate competitiveness in terms of operations and maintenance costs. Although thermal performance tests implemented using industrial codes and standards can provide officially trustworthy results, they are essentially resource-consuming and maybe even a hind-sighted technique rather than a foresighted one, considering their periodicity. Therefore, if more accurate performance monitoring can be achieved using advanced data analysis techniques, we can expect more optimized operations and maintenance. This paper proposes a framework and describes associated methodologies for in-situ thermal performance analysis, which differs from conventional performance monitoring. The methodologies are effective for monitoring, diagnosis, and prognosis in pursuit of CBM. Our enabling techniques cover the intelligent removal of random and systematic errors, deviation detection between a best condition and a currently measured condition, degradation diagnosis using a structured knowledge base, and prognosis for decision-making about maintenance tasks. We also discuss how our new methods can be incorporated with existing performance tests. We provide guidance and directions for developers and end-users interested in in-situ thermal performance management, particularly in NPPs with large steam turbines.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1534-1539
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• 2009

During the last ten years, there have been many studies related with settlement and reinvigoration of CM. These researches have shown that the application of CM has been not reinvigorated in Korean construction industry yet, because of some problems such as the insufficient application of the public sector, the policy matters and the CM fee estimates. But the present condition data of the Korean CM Market shown in these studies was insufficient for the standpoint of Market itself. Also, some of these studies compared the Korean CM Market with The America CM Market, to study the foreign CM markets. However, because the Korea CM Market only has the CM for Fee Market but the American CM Market has the CM for Fee and the CM at Risk, the Korea CM Market must be not only compared with the America CM Market but also compared with the America CM for Fee Market. Therefore, the purpose of this study is to determine the present condition of the Korea CM Market through the compare and contrast of the Korean CM Market, American CM Market and American CM for Fee Market, by the Market Growth rate and Market Share. This study further aims to verify whether Korean CM market was implemented.

• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.295-299
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• 2007

This paper presents the ASF(Additional Secondary Factor) modeling of DGPS beacon signal. In addition to DGPS's original purpose, the feasibility to utilize DGPS system for timing and navigation has been studied. For timing and navigation, the positioning system must know the accurate time delay of signal traveling from the transmitter to receiver. Then the delay can be used to compute the user position. The DGPS beacon signal transmits the data using medium frequency, which travels through the surface and cause the additional delay rather than the speed of light according to conductivities and elevations of the irregular terrain. We introduce the modeling of additional delay(ASF) and present the results of implementation. The similar approach is Locan-C. Loran-C has been widely used as the maritime location system and was enhanced to E-Loran(Enhanced Loran). E-Loran system uses the ASF estimation method and is able to provide the more precise location service. However there was rarely research on this area in Korea. Hence, we introduce the ASF and its estimation model. With the comparison of the same condition and data from the original Monteath model and ASF estimation data of Loran system respectively, we guarantee that the implementation is absolutely perfect. For further works, we're going to apply the ASF estimation model to Korean DGPS beacon system with the Korean terrain data.