• 한국태양에너지학회 논문집
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• 제21권1호
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• pp.83-91
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• 2001

The heat transfer experiment in a pilot scale latent heat storage tank as a solar energy storage system for the hot water supply was carried out. The latent heat storage tank was consisted of three parts; Outer shell for hot water from solar collector, PCM storage vessel in the middle of the tank and immersed coil in the PCM vessel for hot water recovery. The heat storage tank has the dimension of 115 cm in height and 32 cm outside diameter. Paraffin wax (m.p = 55.4C) and sodium acetate trihydrate (m.p = 58 C) were employed as the PCM this study. Experimental variables were inlet temperature and flow rate of the hot water for heat storage stage and cold water for heat recovery stage. Temperature profiles, heat transfer coefficient and the efficiency of heat storage $(Q/Q_{max})$ and heat recovery $(Q/Q_{max})$ were determined for the paraffin wax and inorganic salt respectively.

• 설비공학논문집
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• 제20권2호
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• pp.128-136
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• 2008

It is necessary to estimate the cooling load of the next day for effective control of ice thermal storage system. In this paper, new methodology is proposed to estimate the cooling load using design parameters of building and predicted weather data. Only six input parameters such as sensible heat coefficient and constant, latent heat coefficient and constant, maximum and minimum temperature are necessary to obtain hourly distribution of cooling load for the next day. Two benchmarking buildings(hospital and research institute) are selected to validate the performance of the proposed method, and the estimated cooling loads in hourly and daily bases are calculated and compared with the measured data for E hospital. The estimated results show fairly good agreement with the measured data for both buildings.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.447-452
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• 2007

Greenhouses should be heated during nights and cold days in order to fit growth conditions in greenhouses. Ground source heat pump(GSHP) or geothermal heat pump system(GHPs) is recognized to be outstanding heating and cooling system. Horizontal GSHP system is typically less expensive than vertical GSHP system but requires wide ground area to bury ground heat exchanger(GHE). In this study, a horizontal GSHP system with thermal storage tank was installed in greenhouse and investigated as performance characteristics. In the daytime, heating load of greenhouse is very small or needless because solar radiation increases inner air temperature. The results of study showed that the heating coefficient of performance of the heat pump ($COP_h$) was 2.9 and the overall heating coefficient of performance of the system($COP_{sys}$) was 2.4. Heating energy cost was saved 76% using the horizontal GSHP system with thermal storage tank.

• 방사성폐기물학회지
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• 제21권3호
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• pp.359-370
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• 2023

The thermal integrity of spent nuclear fuels has to be maintained during their long-term dry storage. The detailed temperature distributions of spent fuel assemblies are essential for evaluating the integrity of their dry storage systems. In this study, a subchannel analysis model was developed for a canister of a single fuel assembly using the COBRA-SFS code. The thermal parameters affecting the peak cladding temperature (PCT) of the spent fuel assembly were identified, and sensitivity analyses were performed based on these parameters. The subchannel analysis results indicated the presence of a recirculation flow, based on natural convection, between the fuel assembly and downcomer region. The sensitivity analysis of the thermal parameters indicated that the PCT was affected by the emissivity of the fuel cladding and basket, convective heat transfer coefficient, and thermal conductivity of the fluid. However, the effects of the wall friction factor of the canister, form loss coefficient of the grid spacers, and thermal conductivities of the solid materials, on the PCT were predominantly ignored.

• 세라미스트
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• 제10권3호
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• pp.86-90
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• 2007

Novel photochromic oxide glasses are presented in this section. These glasses are based on phosphate formers containing both tungsten and antimony atoms. Exposure to visible continuous or pulsed laser beam results in an intense photochromic effect witch is shown to occur in the volume of the glass and results in a broad absorption band in the visible and near infrared. This effect was not identified to be related with a structural change and is assumed to be entirely electronic. A change in the absorption coefficient is observed in function of tungsten content, exposure time and increases with beam power. These glasses have been investigated regarding the possibility of holographic data storage using visible lasers sources. Changes in both refractive index and the absorption coefficient were measured using a holographic setup. The modulation of the optical constants is reversible by heat treatment.

• 한국환경과학회지
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• 제15권4호
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• pp.365-372
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• 2006

In this study investigated that topographical parametersestimate and calculated travel time, storage coefficient and lag time by watershed dividing 11, 8, 6 and 2. The results showed the more divide watershed, the more increase peak discharges. The results showed that Kraven-Clark-Kraven case is good simulated by compared observed data with calculated data. The sub-basin number are adequate $6{\sim}11$ for wichun and travel times compare observed data with calculated data at the younggok, to take about $18{\sim}20hr$ by simulated results but observed data shorter $8{\sim}10hr$. From this study results showed that it could be make narrow parameter estimate for observed hydrograph simulation, if more observed velocity and hydrograph. Also, as results of this study that is help to estimate parameters (arrival time, storage coefficient and lag time for Clark model.

• 한국환경과학회지
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• 제16권12호
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• pp.1319-1324
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• 2007

A tank model in conjunction with Kalman filter is developed for prediction of sediment yield from an upland watershed in Northwestern Mississippi. The state vector of the system model represents the parameters of the tank model. The initial values of the state vector were estimated by trial and error. The sediment yield of each tank is computed by multiplying the total sediment yield by the sediment yield coefficient. The sediment concentration of the first tank is computed from its storage and the sediment concentration distribution(SCD); the sediment concentration of the next lower tank is obtained by its storage and the sediment infiltration of the upper tank; and so on. The sediment yield computed by the tank model using Kalman filter was in good agreement with the observed sediment yield and was more accurate than the sediment yield computed by the tank model.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.497-500
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• 2003

If ground water levels of a confined fractured rock aquifer fluctuate with sea tides, individual values of hydrogeologic parameters can be determined. Tidal efficiency and time lag are first calculated from the water level data recorded at an observation device situated inland from the sea. The tidal efficiency factor of the aquifer at the seacoast is then determined from the observation in monitoring wells and used to calculate storage coefficient. Tidal efficiency factor and the tidal time lag are utilized to calculate storage coefficient and the results are compared. This method is tested in the southeastern coastal area of Busan, Korea. This is a simple and inexpensive way to test confined aquifer but the analysis should be performed according to the coastal environment.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.84-92
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• 2005

This work presents the feasibility of shunt damping far vibration suppression of the rotating HDD disk-spindle system using piezoelectric bimorph. A target vibration mode which significantly restricts the recording density increment of the drive is determined through modal analysis and a piezoelectric bimorph is designed to suppress unwanted vibration. After deriving the two-dimensional generalized electromechanical coupling coefficient of the shunted drive, the shunt damping of the system is predicted by simulating the displacement transmissibility using the coefficient. In addition, optimal design process using sensitivity analysis is undertaken in order to improve the shunt damping of the system. The effectiveness of the proposed methodology is verified through experimental implementation by observing the vibration characteristics of the rotating disk-spindle system in frequency domain.

• 한국환경과학회지
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• 제23권4호
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• pp.533-541
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• 2014

The streams in Jeju Island have very distinctive hydrological and geological properties and there are a lot of limits in applying the general flood estimation method. This study presented parameters dominant in the Hancheon stream of Jeju Island by analyzing the sensitivity of parameters of HEC-HMS model regarding rainfall events in the target basin, and extracted the optimal parameter(Time of Concentration of Clark Unit Hydrograph: Kraven II method, Storage Coefficient: Sabol method) by analyzing and comparing it with the flood runoff data observed in the site and Jeju Island's observation data.