• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.725-736
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• 2014

It is very important to detect and identify small anomalies and component failures for the safe operation of complex and large-scale artifacts such as nuclear power plants. Each diagnostic technique has its own advantages and limitations. These facts inspire us not only to enhance the capability of diagnostic techniques but also to integrate the results of diagnostic subsystems in order to obtain more accurate diagnostic results. The article describes the outline of four diagnostic techniques developed for the condition monitoring of the fast breeder reactor "Monju". The techniques are (1) estimation technique of important state variables based on a physical model of the component, (2) a state identification technique by non-linear discrimination function applying SVM (Support Vector Machine), (3) a diagnostic technique applying WT (Wavelet Transformation) to detect changes in the characteristics of measurement signals, and (4) a state identification technique effectively using past cases. In addition, a hybrid diagnostic system in which a final diagnostic result is given by integrating the results from subsystems is introduced, where two sets of values called confidence values and trust values are used. A technique to determine the trust value is investigated under the condition that the confidence value is determined by each subsystem.

• Journal of the military operations research society of Korea
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• v.33 no.1
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• pp.1-18
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• 2007

In the early stage of weapon system acquisition process, acquisition policy is necessarily established to acquire weapon system in a faster, better, cheaper way. Several alternatives, such as "buy", "domestic research and development", and "technical corporative production", can be considered for the best acquisition policy making. However, the comparison factors for those alternatives have different metrics and values. Therefore, the aim of this paper is to suggest KAAM(Knowledge-based Alternatives Analysis Model) as a scientific method to compare the alternatives having such different metrics and values and giving a weighted and normalized single measurement for the easy comparison. KAAM is a hybrid model incorporating Satty technique, Delphi/Shang method, Consensus method, and SAW method. KAAM is implemented on Microsoft Excel environment and provided tabular form user interface. Finally, an illustrative example is shown using KAAM.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1042-1047
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• 2008

As an ultra-precision measurement system the heterodyne laser interferometer plays an important role in semiconductor industry. However the errors of environment and nonlinearity which are caused by air refraction and frequency-mixing separately reduce the accuracy of displacement measurement. In this paper we propose a DFNN(data fusion and neural network) method for error compensation. As a hybrid method of data fusion and neural network, DFNN method reduces the environmental and nonlinear error simultaneously. The effectiveness of the proposed error compensation method is proved through experimental results.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.195-197
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• 2010

체온은 가장 기본적인 진단 정보로써 여러 가지 생리 변화를 반영하는 지표이므로 거의 모든 질환에 대해 반드시 측정하도록 되어있다. 그러므로 체온을 정확하고 빠르게 측정하는 것은 매우 중요하다. 본 논문은 복합형 체온측정 시스템의 개발에 목적이 있다. 즉, 하나의 복합 시스템으로 고막과 이마에서의 체온을 측정하려고 한다. 개발 결과, 이 시스템은 IR 센서를 사용한 비접촉식 방식이며 빠른 응답시간과 $0.2^{\circ}C$의 정밀도를 가지고 있다. 또한 체온 측정을 위한 주변온도 보상을 고려하여 온도 측정의 정확도를 높였다.

• Wind and Structures
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• v.18 no.4
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• pp.375-389
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• 2014

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4491-4503
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• 2023

This study aimed to verify and validate the transient simulation capability of the hybrid code system RAST-F for fast reactor analysis. For this purpose, control rod (CR) drop experiments involving eight separate CRs and six CR groups in the China Experimental Fast Reactor (CEFR) start-up tests were utilized to simulate the CR drop transient. The RAST-F numerical solution, including the neutron population, time-dependent reactivity, and CR worth, was compared against the measurement values obtained from two out-of-core detectors. Moreover, the time-dependent reactivity and CR worth from RAST-F were verified against the results obtained by the Monte Carlo code Serpent using continuous energy nuclear data. A code-to-code comparison between Serpent and RAST-F showed good agreement in terms of time-dependent reactivity and CR worth. The discrepancy was less than 160 pcm for reactivity and less than 110 pcm for CR worth. RAST-F solution was almost identical to the measurement data in terms of neutron population and reactivity. All the calculated CR worth results agreed with experimental results within two standard deviations of experimental uncertainty for all CRs and CR groups. This work demonstrates that the RAST-F code system can be a potential tool for analyzing time-dependent phenomena in fast reactors.

• Journal of the Korean Institute of Educational Facilities
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• v.18 no.3
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• pp.35-41
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• 2011

Performance of a small-capacity solar absorption cooling system was investigated experimentally. Ten sets of evacuative-tube solar-heat collectors and a 5 kW single-stage absorption cooler were combined to produce a hybrid cooling system. The performance of the cooling system was measured using a tim-coil unit installed in a small plastic storage. It was found from the test on a sunny day of May that when the temperature of the hot water supplied from the solar collectors to the generator of the absorption cooler reached $60^{\circ}C$, the absorption cooler started cooling and the cold water temperature measured from the fan-coil unit reached $18^{\circ}C$. The COP, which is defined as the ratio of the cooling power to the total electrical power input was higher than 1.0.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.334-334
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• 2022

Improvement of old-fashioned rain gauge systems for automatic, timely, continuous, and accurate precipitation observation is highly essential for weather/climate prediction and natural hazards early warning, since the occurrence frequency and intensity of heavy and extreme precipitation events (especially floods) are recently getting more increase and severe worldwide due to climate change. Although rain gauge accuracy of 0.1 mm is recommended by the World Meteorological Organization (WMO), the traditional rain gauges in both weighting and tipping bucket types are often unable to meet that demand due to several existing technical limitations together with higher production and maintenance costs. Therefore, we aim to introduce a newly developed and cost-effective hybrid rain gauge system at 0.1 mm accuracy that combines advantages of weighting and tipping bucket types for continuous, automatic, and accurate precipitation observation, where the errors from long-term load cells and external environmental sources (e.g., winds) can be removed via an automatic drainage system and artificial intelligence-based data quality control procedure. Our rain gauge system consists of an instrument unit for measuring precipitation, a communication unit for transmitting and receiving measured precipitation signals, and a database unit for storing, processing, and analyzing precipitation data. This newly developed rain gauge was designed according to the weather instrument criteria, where precipitation amounts filled into the tipping bucket are measured considering the receiver's diameter, the maximum measurement of precipitation, drainage time, and the conductivity marking. Moreover, it is also designed to transmit the measured precipitation data stored in the PCB through RS232, RS485, and TCP/IP, together with connecting to the data logger to enable data collection and analysis based on user needs. Preliminary results from a comparison with an existing 1.0-mm tipping bucket rain gauge indicated that our developed rain gauge has an excellent performance in continuous precipitation observation with higher measurement accuracy, more correct precipitation days observed (120 days), and a lower error of roughly 27 mm occurred during the measurement period.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.121-130
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• 2009

In this paper, Gaussian probability distribution model based multi-sensor data fusion algorithm is proposed for a vehicular location awareness system. Conventional vehicular location awareness systems are operated by GPS (Global Positioning System). However, the conventional system is not working in the indoor of building or urban area where the receiver is difficult to receive the signal from satellites. A method which is combined GPS and UWB (Ultra Wide-Band) has developed to improve this problem. However, vehicular is difficult to receive seamless location information since the measurement systems by both GPS and UWB convert the vehicle's movement information separately at each sensor. In this paper, normalized probability distribution model based Hybrid UWB/GPS is proposed by utilizing GPS location data and UWB sensor data. Therefore the proposed system provides information with seamless and location flexible properties. The proposed system tested by Ubisense and Asen GPS in the $12m{\times}8m$ outdoor environments. As a result, the proposed system has improved performance for accurateness and connection ability between devices to support various CNS (Car Navigation System).

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.867-886
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• 1996

The purpose of this study was to evaluate the shearbond strength and resin-dentin interface of three different dentinal bonding systems in primary and permanent teeth. Thirty extracted human primary molars and premolars, which were non-carious and free of obvious defect, were selected for this study. All specimens were divided into six groups with two groups allocated for each of the three dentinal bonding system(All-bond 2, Scotchbond Multi-Purpose, Gluma bonding system). After completion of bonding composite to dentin using each tested dentin bonding system, bond strength measurement and histological observation were performed. The results are as follows: 1. All-bond 2 and Scotchbond Multi-Purpose, A good quality hybrid layer was identified, the morphology of which could be equated with the zone of H-E and Brown-Brenn staining. In Gluma bonding system, hybrid layer was very thin, and separated from the solid polymer. 2. All-bond 2 had the highest mean shearbond strength, followed by Scotchbond Multi-Purpose and Gluma bonding system in both primary and permanent teeth. There was no statistically significant difference between All-bond 2 and Scotchbond Multi-Purpose. Statistically significant difference could be found between Gluma bonding system and the other two groups(p<0.05). 3. The fracture patterns observed were mainly the mixture of adhesive failure and dentin dettachment pattern in All-bond 2 and Scotchbond Multi-Purpose while adhesive failure prevailed in Gluma bonding system.