• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.57-66
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• 2023

Asset valuation of social infrastructure is essential for rational decision-making for efficient management of assets. In addition, it can be an indicator for correctly recognizing assets. In general, Korea applies depreciated replacement cost based on the straight-line method to evaluate asset value, yet this is unsuitable for evaluating actual value because it is depreciated at a constant rate over the useful life period. In order to evaluate the asset value considering the performance of the bridge, the performance index of the bridge is estimated using the Weibull distribution. Using the estimated performance indicators and defect index, a new asset value evaluation method is proposed and compared and analyzed with the existing method. The proposed valuation method can take into account the performance of the bridge, so it is judged to be more objective and reasonable than existing method.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.2
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• pp.79-88
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• 2014

In Republic of Korea, there are considerable vulnerability in electrical stimulating swallowing-assist equipments even though they are professional medical equipments and have high penetration rate with heavy frequency of use. Therefore, in this article, we developed Device Management and Safety Diagnosis Manual for Electrical Stimulating Swallowing-Assist Equipments system. For achieving this, we collected and analysed international standard data from international organizations like International Electrotechnical Commission(IEC). After literature reviews, we build maintenance worksheet and equipment procedure manual for electrical stimulating swallowing-assist equipments according to evidences we collected. These manual and protocol would be used as standard process and contribute to sustain accuracy, effectiveness of the devices, also decrease failure rate and assist to save medical documents.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.41-47
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• 2023

Today, due to the increase in global population growth, the international community is discussing solving the food problem. The aquaculture industry is emerging as an alternative to solving the food problem. For the innovative growth of the aquaculture industry, smart fish farms that combine the fourth industrial technology are recently being distributed, and full-cycle digitalization is being promoted. Water quality sensors, which are important in the aquaculture industry, are electrochemical portable sensors that check water quality individually and intermittently, making it impossible to analyze and manage water quality in real time. Recently, optically-based monitoring sensors have been developed and applied, but the reliability of monitoring data cannot be guaranteed because the state information of the water quality sensor is unknown. Therefore, this paper proposes an algorithm representing self-diagnosis status such as Failure, Out of Specification, Maintenance Required, and Check Function based on monitoring data collected by water quality sensors to ensure data reliability.

• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.581-584
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• 2008

무선 센서 네트워크는 최근 대두되고 있는 유비쿼터스 컴퓨팅의 연구에 힘입어, 광범위하게 설치되어 있는 유무선 네트워크 인프라에 상황인지를 위한 다양한 센서 디바이스를 결합하여 감지된 환경 데이터를 응용서비스와 연동하는 기술이다. 기본적으로 홈/빌딩 시큐리티, 사회기반 안전시설, 기계의 고장 진단, 의료 분야 등의 실세계의 다양한 분야에 응용될 수 있다. 본 논문에서 다루고자하는 실종 아동에 대한 문제는 어제 오늘의 이야기가 아니다. 미아 발생률은 꾸준히 증가하고 있으며 장기 미아의 발생 역시 증가하고 있다. 따라서 미아 방지를 위해 새로운 서비스들이 소개되었으나 이용자의 경제적 비용 부담 증가와 같은 문제점을 안고 있다. 본 논문에서 제안하는 미아 찾기 시스템은 무선 센서 네트워크 기술 응용 중의 하나로서 미아가 발생 시에 아동이 장기 미아가 되지 않도록 효율적이면서도 빠르게 미아를 찾을 수 있도록 하기 위해서 개발되었다. RFID 리더기가 장착된 고정형 센서 노드와 이동형 센서노드가 RFID 태그를 지닌 아동의 정보를 얻어서 중앙 제어 서버로 데이터를 넘기면 태그 정보와 전송한 센서 노드의 위치, 전송 시간을 바탕으로 아동의 위치를 파악할 수가 있다. 미아 찾기 시스템은 이용자가 태그만을 지니면 되기 때문에 경제적 부담은 줄어 들 수 있다. 또한 상기 시스템으로 미아 찾기만이 아니라 주변 환경 감시등의 여러 응용에도 적용 시킬 수가 있다.

• Radiation Oncology Journal
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• v.23 no.3
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• pp.186-193
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• 2005

Purpose: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2l00C over a ten year period were retrospectively analyzed. Materials and Methods: The failures were classified according to the involved functional subunits, with each class rated Into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. Results: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for $20\%$ of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and $83\%$ of the expected values, respectively. The operating efficiency was maintained at $95\%$ or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. Conclusion: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. Wore rigorous equipment maintenance Is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the qualify of patient treatment.

• Journal of the Korea Convergence Society
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• v.9 no.3
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• pp.39-44
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• 2018

In this paper, we propose a monitoring method of smartphone to integrate IoT technology to monitor the state of the vehicle for fault diagnosis of E-Mobility power converter. In China, EV regulations are being implemented to promote technological development and market changes in electric vehicles. To meet this trend, E-Mobility should study suitable monitoring technology. The OBD-II method used in existing automobiles is a wired / wireless communication method. In order to apply it to E-Mobility, additional interface and communication link are required. In this paper, we propose a technology to monitor the status information of power converter for E-Mobility by combining existing technology with IoT. This technology simplifies the existing network protocol and hardware interface, and confirms that the E-Mobility power converter and smartphone can be interworked for easy user monitoring. And we have done research to make high value product design from the aspect of function.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.27-32
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• 1997

Continual monitoring of abnormal operating conditions i a key issue in maintaining high product quality and safe operation, since the undetected process abnormality may lead to the undesirable operations, finally producing low quality products, or breakdown of equipment. The statistical projection method recently highlighted has the advantage of easily building reference model with the historical measurement data in the statistically in-control state and not requiring any detailed mathematical model or knowledge-base of process. As the complexity of process increases, however, we have more measurement variables and recycle streams. This situation may not only result in the frequent occurrence of process Perturbation, but make it difficult to pinpoint trouble-making causes or at most assignable source unit due to the confusing candidates. Consequently, an ad hoc skill to monitor and diagnose in plat-wide scale is needed. In this paper, we propose a hierarchical plant-wide monitoring methodology based on hierarchical decomposition and principal component analysis for handling the complexity and interactions among process units. This have the effect of preventing special events in a specific sub-block from propagating to other sub-blocks or at least delaying the transfer of undesired state, and so make it possible to quickly detect and diagnose the process malfunctions. To prove the performance of the proposed methodology, we simulate the Tennessee Eastman benchmark process which is operated continuously with 41 measurement variables of five major units. Simulation results have shown that the proposed methodology offers a fast and reliable monitoring and diagnosis for a large scale chemical plant.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.2
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• pp.121-130
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• 2009

In this paper, the attitude and orbit control subsystem technology of new GEO communication and observation satellite using Sun sensors are introduced and analyzed. COMS is new GEO communication and Earth observation satellite based on EUROSTAR 3000 space bus technology. The attitude and orbit control subsystem of COMS adopts a configuration using three BASS and three LIASS Sun sensors to acquire the attitude error information in the specific reference frames. These Sun sensors are used to acquire Sun direction and to control the spacecraft to keep the relative attitude with respect to a reference Sun direction in both transfer and operational orbits. In this paper, the mathematical models of BASS and LIASS are described as well as their operational implementation in the flight software.

• Current Photovoltaic Research
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• v.10 no.3
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• pp.77-83
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• 2022

Renewable energy is receiving attention again as a way to realize carbon neutrality to overcome the climate change crisis. Among renewable energy sources, the installation of Photovoltaic is continuously increasing, and as of 2020, the global cumulative installation amount is about 590 GW and the domestic cumulative installation amount is about 17 GW. Accordingly, O&M technology that can analyze the power generation and fault diagnose about PV plants the is required. In this paper, a study was conducted to diagnose fault using I-V curves of PV strings and deep learning. In order to collect the fault I-V curves for learning in the deep learning, faults were simulated. It is partial shade and voltage mismatch, and I-V curves were measured on a sunny day. A two-step data pre-processing technique was applied to minimize variations depending on PV string capacity, irradiance, and PV module temperature, and this was used for learning and validation of deep learning. From the results of the study, it was confirmed that the PV fault diagnosis using I-V curves and deep learning is possible.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.613-622
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• 2015

The convergence of IT technology and marine facilities monitoring system is needed for effective monitoring systems to marine facilities. Especially the spread of smart device such as smart phone, smart pad, smart TV provide an environment that can check the status of the marine facility for marin facilities manager. However, smart phones and smart pads are used in a variety of OS used. Thus the monitoring system of the various service environments is difficult. In addition, There is inconvenience that must individually developed monitoring system for each device. In order to solve this problem NMMS (N-Screen Marine-facility Monitoring System) is proposed. NMMS is consist of Real-time monitoring system, Fault diagnosis system, Data storage system. To improve variety of smart devices accessibility, we use HTML 5. Through NMMS, marine facilities manager can use smart device such as PC, Notebook, smart phone, smart pad for marine facilities monitoring.