• The Journal of the Acoustical Society of Korea
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• v.17 no.1E
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• pp.54-65
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• 1998

This study attempts to test the classifying performance of a neural network and thereby examine its applicability to the signals distorted in a shallow water environment. Linear frequency modulated(LFM) signals are simulated by using an acoustic model and also measured through sea experiment. The network is constructed to have three layers and trained on both data sets. To get normalized power spectra as feature vectors, the study considers the three transforms : shot-time Fourier transform (STFT), wavelet transform (WT) and pseudo Wigner-Ville distribution (PWVD). After trained on the simulated signals over water depth, the network gives over 95% performance with the signal to noise ratio (SNR) being up to-10 dB. Among the transforms, the PWVD presents the best performance particularly in a highly noisy condition. The network performs worse with the summer sound speed profile than with the winter profile. It is also expected to present much different performance by the variation of bottom property. When the network is trained on the measured signals, it gives a little better results than that trained on the simulated data. In conclusion, the simulated signals are successfully applied to training a network, and the trained network performs well in classifying the signals distorted by a surrounding environment and corrupted by noise.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.1
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• pp.8-14
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• 1999

This paper presents the methods of short-term load forecasting Kohonen neural networks and back-propagation neural networks. First, historical load data is divided into 5 patterns for the each seasonal data using Kohonen neural networks and using these results, load forecasting neural network is used for next day hourly load forecasting. Next day hourly load of weekdays and weekend except holidays are forecasted. For load forecasting in summer, max-temperature and min-temperature data as well as historical hourly load date are used as inputs of load forecasting neural networks for a better forecasting accuracy. To show the possibility of the proposed method, it was tested with hourly load data of Korea Electric Power Corporation(1994-95).

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.969-977
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• 2021

We cluster the electricity consumption of households in A-apartment in Seoul, Korea using Hierarchical K-means clustering algorithm. The data is recorded from the advanced metering infrastructure (AMI), and we focus on the electricity consumption during evening weekdays in summer. Compare to the conventional clustering algorithms, Hierarchical K-means clustering algorithm is recently applied to the electricity usage data, and it can identify usage patterns while reducing dimension. We apply Hierarchical K-means algorithm to the AMI data, and compare the results based on the various clustering validity indexes. The results show that the electricity usage patterns are well-identified, and it is expected to be utilized as a major basis for future applications in various fields.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.14-19
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• 2019

In this study, the Relux illumination program was used to simulate the optimal lighting design for a glass greenhouse with Si and DSSC solar-cells and LEDs. The results of the daylight simulation show that the optimum conditions were a structure angle of 90o and higher transmittance. The results of the illumination simulation produced a power consumption effect of 5.6 kwh in the summer (42[%] energy savings compared to full LED control) and 7.8 kwh in the winter (58[%] energy savings compared to full LED control). The results suggest that ginseng should be grown in an energy-saving glass greenhouse.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.118-118
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• 2020

This study investigates the change of flow characteristics over 10 Asian river basins in the past 30 years (1976-2005). The variation is estimated from The Soil and Water Assessment Tool (SWAT) model outputs based on reanalysis data which was bias-corrected for Asian monsoon reagion. The model was firstly calibrated and validated using observed data for daily streamflow. Four statistical criteria were applied to evaluate the model performance, including Coefficient of determination (R2), Nash - Sutcliffe model efficiency coeffi cient (NSE), Root mean square error-observations standard deviation ratio (RSR), and Percentage Bias (PBIAS). Then parameters of the model were applied for the historical period 1976-2005. The estimates show a temporal non-considerable increasing rate of daily streamflow in most of the basins over the past 30 years. The difference of monthly discharge becomes more significant during the months in the wet season (June to September) in all basins. The seasonal runoff shows significant difference in Summer and Autumn, when the rainfall intensity is higher. The line showing averaged runoff/rainfall ratio in all basins is sharp, presenting high variation of seasonal runoff/rainfall ratio from season to season.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.3
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• pp.3-12
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• 2000

The field surveys and the measurements of seawater temperatures were conducted every month from 1997 to 1999, and the distributions of seawater temperature were simulated and reproduced by a three dimensional hydrodynamic numerical model over the southern waters of Cheju island. In order to estimate the marine environmental capacity for the reception of the heat loads of cooling water discharged from Hwasoon Thermal Power Plant(HTPP) in the study area, the simulations for predicting the situation of unfavorable environment in which marine organisms might not be satisfied with change in seawater temperature were peformed using a three dimensional hydrodynamic numerical model by controlling quantitatively the heat loads of cooling water from HTPP Currently, HTPP discharges cooling water of 35.9℃ into the sea as much as 112,800m³/day in summer. As the results of simulations, the more the heat loads from the power plant increase, the more increase the seawater temperatures around the water areas adjacent to the power plant. In case the heat loads of cooling water from HTPP become about 5 times as high as the present loads, seawater temperatures at near-shore waters adjacent to HTPP appear to be increased to the extent of 0.5℃ above the existing seawater temperature in summer. The marine environmental capacity for the reception of thermal discharge from HTPP is estimated to be about 530×10/sup 6/kcal/day which is equivalent to the increase of a factor of 2 in the temperature of cooling water without any change in the discharge rate of cooling water or which is equivalent to the increase of a factor of 4.6 in the discharge rate of cooling water without any change in the temperature of cooling water. Comparing the case of the increase in the discharge rate of cooling water with the case of the increase in the temperature of cooling water on the basis of the same heat loads of 530×10/sup 6/kal/day, the former case is expected to increase seawater temperature a little higher and to extend the area affected by heat loads a little broader.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.4
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• pp.52-68
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• 2014

In this study, we investigated the seasonal variation of SST(Sea Surface Temperature) and thermal effluents estimated by using Landsat-7 ETM+ around the Kori Nuclear Power Plant for 10 years(2000~2010). Also, we analyzed the direction and range of thermal effluents dispersion by the tidal current and tide. The results are as follows, First, we figured out the algorithm to estimate SST through the linear regression analysis of Landsat DN(Digital Number) and NOAA SST. And then, the SST was verified by compared with the in situ measurement and NOAA SST. The determination coefficient is 0.97 and root mean square error is $1.05{\sim}1.24^{\circ}C$. Second, the SST distribution of Landsat-7 estimated by linear regression equation showed $12{\sim}13^{\circ}C$ in winter, $13{\sim}19^{\circ}C$ in spring, and $24{\sim}29^{\circ}C$ and $16{\sim}24^{\circ}C$ in summer and fall. The difference of between SST and thermal effluents temperature is $6{\sim}8^{\circ}C$ except for the summer season. The difference of SST is up to $2^{\circ}C$ in August. There is hardly any dispersion of thermal effluents in August. When it comes to the spread range of thermal effluents, the rise range of more than $1^{\circ}C$ in the sea surface temperature showed up to 7.56km from east to west and 8.43km from north to south. The maximum spread area was $11.65km^2$. It is expected that the findings of this study will be used as the foundational data for marine environment monitoring on the area around the nuclear power plant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4602-4609
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• 2013

In summer and winter, the difference between the temperature during the day and that during the night is high, which leads to various problems during concrete placement, such as cracks and defects in the concrete as well as low durability and strength. Although nuclear power plant concrete is widely used for placement in all seasons, particular attention must be paid to its quality during the summer. Therefore, we evaluated the effects of a cooling method for mixing water, which is a commonly used hot weather precooling method, and the use of a retarder, on the characteristics of Nuclear Power Plant concrete. In the cooling method for mixing water, cold water at 5 was used, with 50% of the water content consisting of ice flakes. The effects of using a retarder were evaluated by reviewing the characteristics of the cement at the unset stage and after hardening. To evaluate the characteristics of the unset cement, we measured the slump, air volumes, setting times, and pressure strengths after hardening. Furthermore, we measured the heat of hydration at different temperatures; the loss of heat was minimized using insulation. Both the slump time and the complete ageing time of the air volume were found to be 120 min at $20^{\circ}C$ and 40 min at $40^{\circ}C$. In the case when the cooling method for mixing water was used and in the case when a retarder was used, the initial and final sets by penetration resistance were delayed, and the delay decreased with increasing air temperature. For the heat of hydration, the cooling method for mixing water not only lowered the maximum temperature but also delayed its attainment. However, the use of a retarder had no effect on the maximum temperature. Moreover, in the early ages (e.g., 3 and 7 days), the pressure strength of the concrete was lower than that of plain cement. However, the strength of 28-day concrete met the standard construction specifications.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.68-80
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• 1984

Garolim Bay is not only important fishing ground but also expected area for the tidal power plant. The construction and operation of tidal power plant will make change the ecosystem of this bay. Therefore, the actual fisheries stocks should be precisely understood for the effect estimation and overall utilization of the bay after the construction of the tidal power plant. During the study period from January through December in 1981, forty-six adult fishes species, 3 species of fish egg and 25 fishes larvae species have occurred in the bay. Considering the result on monthly distribution of eggs and larvae, the inner area of the bay seems to be important as nursing ground of larvae spawned at the outside bay in winter, e. g., Ammodytes personatus, and Enedrias sp. This inner bay is also major spawning ground for many species spawning in spring and summer, e. g., Gobiidae, Konosirus punctatus, Engraulis japonica, etc. Taking into consideration the annual mean production for three years($1978{\sim}1980$), there are two major fishing seasons. The one is in May-June for Enedrias larvae stock, and the another in October-November for big eyed herring stock. For the mariculture stocks, short necked clam, oyster and laver are important species. After construction of the tidal power plant, the migratory species, i. e., larvae of Enedrias and Ammodytes personatus, Mugil cephalus, Konosirus punctatus, etc. will be directly damaged by the interuption of migration route. On the otter hand, the change of physico-chemical factors of seawater will also affect the ecosystem of the bay. Consequently, for the overall utilization of the bay after construction, the actual ecosystem including the fisheries stocks, must bs precisely revealed, and the mechanical designs, e. g., sluice position and its demension, should be also considered with these biological characters of the bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.391-407
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• 1987

To understand the effects of the cooling water system of the power plant on the succession of sessile zoobenthos, a series of experiments were carried out at the cooling water system of Samchonpo Power Plant from Hay 1985 to May 1986. The lowest species diversity of the zoobenthos was observed at the discharge canal. This is probably caused by both increased velocity and temperature of circulating water. It is also noticeable that species composition of the zoobenthos, to a certain degree, was affected due to the impingement of meroplankton during the entrainment process. While the number of species attached on the experimental substrata installed in the thermally altered area is smaller than that in the intake canal, the biomass is increased as the increased temperature eliminates some species and in turn stimulates reproduction and growth of the others. It is interesting that relatively high similarity exists between the summer communities in the intake canal and the spring communities in the thermally altered area, and the same relationship is also found between the fall communities in the intake canal and the winter communities in the thermally altered area. Ecological index curves of the zoobenthos of the intake canal follows the fluctuation pattern of the thermally altered area in one or two months of elapsed time, probably due to temperature increase by the inflow of heated water discharged from the power plant.