• International Journal of Fuzzy Logic and Intelligent Systems
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• v.2 no.2
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• pp.95-99
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• 2002

The Loose Part Monitoring System(LPMS) has been designed to detect. locate and evaluate detached or loosened parts and foreign objects in the reactor coolant system. In this paper, at first, we presents an application of the back propagation neural network. At the preprocessing step, the moving window average filter is adopted to reject the reject the low frequency background noise components. And then, extracting the acoustic signature such as Starting point of impact signal. Rising time. Half period. and Global time, they are used as the inputs to neural network . Secondly, we applied the neural network algorithm to LPMS in order to estimate the mass of loose parts. We trained the impact test data of YGN3 using the backpropagation method. The input parameter for training is Rising clime. Half Period amplitude. The result shored that the neural network would be applied to LPMS. Also, applying the neural network to thin practical false alarm data during startup and impact test signal at nuclear power plant, the false alarms are reduced effectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.158-164
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• 2015

The main mission of OTM(On-The-Move) satellite communication system is to provide satellite communication service while moving on a vehicle. So it should have a capability to maintain a reliable communication channel when it travels at high speeds or in a severe fluctuation region. This paper presents a small-sized multi-mode monopulse structure applicable to OTM satellite communication system which has only single mode-coupler with a pair of slot using a feature of circular polarized received signal. And tracking error signal is defined using fundamental and high-order modes.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.238-243
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• 2012

The purpose of this study is to search the temperature-rise time conditions for adequate reforming temperature region of hydrogen generation system. And we measured theexhaust gas at the exit of that system in order to know the combustion state of hydrogen generation system's combustor. We found the optimum condition of heat supply and temperature-rise time at well burned state. And the results were nearly same when the reactants were entered to each reactors. We will further consider the effects of temperature change near the exothermic reactors and find out hydrogen yield through reforming experiment.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.207-215
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• 1993

In order to statistically predict $O_3$ levels in Seoul, the study used the TMS (telemeted air monitoring system) data from the Department of Environment, which have monitored at 20 sites in 1989 and 1990. Each data in each site was characterized by 6 major criteria pollutants ($SO_2, TSP, CO, NO_2, THC, and O_3$) and 2 meteorological parameters, such as wind speed and wind direction. To select proper variables and to determine each pollutant's behavior, univariate statistical analyses were extensively studied in the beginning, and then various applied statistical techniques like cluster analysis, regression analysis, and expert system have been intensively examined. For the initial study of high level $O_3$ prediction, the raw data set in each site was separated into 2 group based on 60 ppb $O_3$ level. A hierarchical cluster analysis was applied to classify the group based on 60 ppb $O_3$ into small calsses. Each class in each site has its own pattern. Next, multiple regression for each class was repeatedly applied to determine an $O_3$ prediction submodel and to determine outliers in each class based on a certain level of standardized redisual. Thus, a prediction submodel for each homogeneous class could be obtained. The study was extended to model $O_3$ prediction for both on-time basis and 1-hr after basis. Finally, an expect system was used to build a unified classification rule based on examples of the homogenous classes for all of sites. Thus, a concept of high level $O_3$ prediction model was developed for one of $O_3$ alert systems.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.111-116
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• 2008

The objective of this paper was to show the possibility of demand-controlled ventilation (DCV) using the current Korean ventilation standard for multi-purposed facilites. Two attractive DCV approaches; $CO_2$-DCV and RFID-DCV were applied to DCV simulations for a theoretical public assembly space served by a dedicated outdoor air system (DOAS) with enthalpy recovery device. A numerical model for predicting realtime occupant number, ventilation rate, and $CO_2$ concentration under given conditions was developed using a commercial equation solver program. It was found that the current ventilation standard causes unstable ventilation system control in DCV applications, especially under $CO_2$-DCV. It is because the ventilation rate (per person) used in Korea is the sum of the outdoor air required to remove or dilute air contaminants generated by both occupant and building itself, and not a pure function of occupant numbers. Finally, it makes DCV control unstable when ventilation flow is regulated only by the number of occupants. In order for solving this problem, current Korean ventilation standard was modified as a form of ASHRAE Standard 62.1-2007 showing good applicability to various DCV approaches. It was found that this modification enhances applicability of the current ventilation standard to DCV significantly.

• Journal of Environmental Science International
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• v.7 no.5
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• pp.573-580
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• 1998

This study examined the carbon dioxide ($CO_2$) pollution inside vehicles under low ventilation condition and evaluated the Air Quality System (AQS) for in-vehicle air quality using two techniques. The low ventilation condition is not recommended in order to keep oxygen-rich condition inside vehicles. Under the low ventilation condition, the in-vehicle $CO_2$ concentrations exceeded 1,000 ppm, the air qualify guidelines in the United States, Western Europe, and Japan, indicating more oxygen deficiency inside vehicles. On the contrary, with the AQS-on condition, the in-vehicle $CO_2$ concentrations were less than 1,000 ppm fer most of the driving time, indicating that the AQS could solve the problem of $CO_2$ accumulation inside vehicles under the low ventilation condition. The AQS test conducted by comparing carbon monoxide (CO) and volatile organic compound (VOC) concentrations inside two vehicles indicated that the AQS effectively decreased the in-vehicle concentrations by 21 to 36%, as compared to medium ventilation condition with the windows closed, the vent opened, and air conditioning on. In addition, The AQS test conducted by comparing the interior and exterior concentrations indicated that the AQS effectively decreased the in-vehicle concentrations by 18 to 31%, as compared to medium ventilation condition.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.765-777
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• 2011

According to the total pollution load management system, exact prediction and analysis of water quality and discharge has been required in order to allocate the amount of pollution load to each local government. In this study, QUAL2E model was used for comparison with other water quality models and improve the inadequate to forecast future water quality. And Various calibration and verification methods were applied to deal with existing uncertainties of parameter during modeling water quality. For user convenience, A GUI(Graphical User Interface) system named "QL2-XP" model is developed by object-oriented language for the user convenience and practical usage. Suggested GUI system consist of hydraulic analysis, water quality analysis, optimized model calibration processes, and postprocessing the simulation results. Therefore this model will be effectively utilized to manage practical and efficient water quality.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.212-217
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• 2014

Recently, the use of renewable energy has been increased due to growing concern on the energy-saving at buildings and the reduction of $CO_2$ emission. In the field of architecture, to reduce the energy consumption of heating, cooling and hot water supply, heat pump systems with renewable energy has been developed and used in various applications. However, there have been many of researches on the large-scale commercial heat pump systems, but the research and the field application of a compact heat pump system is rare. Therefore, in order to develop the compact heat pump for the small-scale residential building, this study conducted the performance test and feasibility study for a hybrid heat pump using the heat source of air, solar and ground. In the results of experiments through a trial product, the average COP of cooling mode with ground heat source was 4.75, and it of heating mode was 4.03. Furthermore, the average COP of cooling mode with air heat source was 2.60, and it of heating mode was 2.92. Finally, payback period of the system was calculated as 9.2 years.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.153-156
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• 2009

The water cooling system for VFD (Variable Frequency Drive) of a fossil fuel power plant was reported to be shut down due to a water leak at the metal connection of the heat-sink to the hoses. In order to identify the cause of the failure, the system was visually inspected, and corrosion products were analyzed with SEM equipped with EDX. The failure was observed repeatedly at the nipples of certain location, suggesting galvanic corrosion. In a U-shaped heat sink with two nipples, for inlet and outlet, only one nipple was corrosively damaged at the tip, while the other was not. Most of the corrosion products were observed at the sound nipple and in the filter, identified as $Cu(OH)_2$. Some other corrosion products, composed of mostly $Cu_2O$, were found at the corrosively attacked nipple. A fair amount of Cl was also detected on the surface of the damaged nipple. It was concluded that galvanic corrosion was occurred due to a current leakage over the whole system, and the damage was accelerated by the accumulated chlorine ions in the cooling water.

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.100-106
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• 2011

Music recordings have been digitalized such that huge size of music database is available to the public. Thus, the automatic classification system of music genres is required to effectively manage the growing music database. Mel-Frequency Cepstral Coefficient (MFCC) is a popular feature vector for genre classification. In this paper, the combined super-vector with Decorrelated Filter Bank (DFB) and Octave-based Spectral Contrast (OSC) using texture windows is processed by Support Vector Machine (SVM) for genre classification. Even with the lower order of the feature vector, the proposed super-vector produces 4.2 % improved classification accuracy compared with the conventional Marsyas system.