• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.600-603
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• 2009

We compared relative importance of thermal conductivity and initial ground temperature in designing borehole heat exchanger network and also we test accuracy of ground temperature estimation in thermal response test using a proven 3-D T-H modeler. The effect of error in estimating ground temperature on calculated total length of borehole heat exchanger was more than 3 times larger than the case of thermal conductivity in maximum 20% error range. Considering 10% of error in estimating thermal conductivity is generally acceptable, we have to define the initial ground temperature within 5% confidence level. Utilizing the mean annual ground surface temperature and the geothermal gradient map compiled so far can be a economic way of estimating ground temperature with some caution. When performing thermal response test for estimating ground temperature as well as measuring thermal conductivity, minimum 100 minutes of ambient circulation is required, which should be even more in case of very cold and hot seasons.

• Journal of Ocean Engineering and Technology
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• v.37 no.5
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• pp.198-204
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• 2023

In response to the complexity and time demands of conventional methods for estimating the hydrodynamic coefficients, this study aims to revolutionize ship maneuvering analysis by utilizing automatic identification system (AIS) data and the Support Vector Regression (SVR) algorithm. The AIS data were collected and processed to remove outliers and impute missing values. The rate of turn (ROT), speed over ground (SOG), course over ground (COG) and heading (HDG) in AIS data were used to calculate the rudder angle and ship velocity components, which were then used as training data for a regression model. The accuracy and efficiency of the algorithm were validated by comparing SVR-based estimated hydrodynamic coefficients and the original hydrodynamic coefficients of the Mariner class vessel. The validated SVR algorithm was then applied to estimate the hydrodynamic coefficients for real ships using AIS data. The turning circle test wassimulated from calculated hydrodynamic coefficients and compared with the AIS data. The research results demonstrate the effectiveness of the SVR model in accurately estimating the hydrodynamic coefficients from the AIS data. In conclusion, this study proposes the viability of employing SVR model and AIS data for accurately estimating the hydrodynamic coefficients. It offers a practical approach to ship maneuvering prediction and control in the maritime industry.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1090-1097
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• 2000

Predicting building energy use can be useful to evaluate its energy performance. This study proposed empirical approach for predicting building energy use with regression analysis. For the empirical analysis, simple regression models were developed based on the historical energy consumption data as a function of daily outside temperature, the predicting equations were derived for different operational modes and day types, then the equations were applied for predicting energy use in a building. BY selecting a real building as a case study, the feasibilities of the empirical approach for predicting building energy use were examined. The results showed that empirical approach with regression analysis was fairly reliable by demonstrating prediction accuracy of $pm10%$ compared with the actual energy consumption data. It was also verified that the prediction by regression models could be simple and fairly accurate. Thus, it is anticipated that the empirical approach will be useful and reliable tool for many purposes: retrofit savings analysis by estimating energy usage in an existing building or the diagnosis of the building operational problems with real time analysis.

• New & Renewable Energy
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• v.20 no.1
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• pp.52-60
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• 2024

This study conducted an economic analysis of renewable heat energy by estimating the levelized cost of heat production (LCOH) of ST and GSHP and comparing it with the cost of alternative fuels. The LCOH of ST ranged from 396.8 KRW/kWh to 578.7 KRW/kWh (small-scale), 270.3 KRW/kWh to 393.3 KRW/kWh (large-scale), and 156.3 KRW/kWh to 220.7 KRW/kWh for GSHP. The economic feasibility of ST and GSHP was analyzed by comparing the calculated LCOH and the fuel costs such as gas and kerosene prices. Moreover, scenario analyses were conducted for installation subsidies under the current system to examine the changes in the economics of renewable thermal energy.

• Journal of the Korean Wood Science and Technology
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• v.20 no.4
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• pp.21-30
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• 1992

An activation energy equation for moisture diffusion in wood was developed with an assumption that activation energy is directly proportional to wood specific gravity. Theoretical activation energies obtained from the activation energy equation were revealed to be always lower than actual activation energies, which implies that activation energy isn't affected only by wood specific gravity. The other affecting factors are possibly anatomical structures of wood which determine a ratio of vapor diffusion to bound water diffusion in wood. For the convenience of estimating actual activation energy by using the activation energy equation, thirteen kinds of species were categorized into three groups according to their anatomical structures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.9
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• pp.868-877
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• 2001

This study is to present the typical energy consumption criteria and $CO_2$ exhaust rate in multi-family housing complex by analyzing the energy consumption characteristics. The contents and methodology of this study are as follows; -Examining the documents of maintenance accounts, investigate the cost and its items expended by the annual maintenance in multi-family housing complex. -Survey each consumption of energy sources, maintenance area, location of multi-family housing complex, heating type, and so forth. -After classifying with heating type of multi-family housing complex investigated, Scrutinize the energy consumption by each source. -Analyze the characteristics of energy consumption and $CO_2$ exhaust through multiple regression analyses of maintenance property. -Suggest the typical energy consumption criteria (Mcal/$m^2$.year, Mcal/house.year) and $CO_2$ exhaust rate (kg-c/$m^2$.year, Kg-c/house.year) in multi-family housing complex. the results will come into basic data for estimating energy consumption in multi-family housing complex according to maintenance characteristics.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.275-285
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• 2003

Pinching is an important property of reinforced concrete member which characterizes its cyclic behavior. In the present study, numerical studies were performed to investigate the characteristics and mechanisms of pinching behavior and the energy dissipation capacity of flexure-dominated reinforced concrete members. By analyzing existing experimental studies and numerical results, it was found that energy dissipation capacity of a member is directly related to energy dissipated by re-bars rather than concrete that is a brittle material, and that it is not related to magnitude of axial compressive force applied to the member. Therefore, for a member with specific arrangement and amount of re-bars, the energy dissipation capacity remains uniform regardless of the flexural strength that is changed by the magnitude of axial force applied. Due to the uniformness of energy dissipation capacity pinching appears in axial compression member. The flexural pinching that is not related to shear force becomes conspicuous as the flexural strength increases relatively to the uniform energy dissipation capacity. Based on the findings, a practical method for estimating energy dissipation capacity and damping modification factor was developed and verified with existing experiments.

• Journal of the Korean Solar Energy Society
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• v.25 no.1
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• pp.79-86
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• 2005

The external conditions for estimating dynamic wind loads of wind turbines, such as the turbulence, the extreme wind, the mean velocity gradients and the flow angles, are simulated over GangWon Wind Energy Test Field placed in one of the most complex terrain in Korea. Reference meteorological data has been gathered at a height of 30m from 2003 to 2004 with a ultrasonic anemometer. The absolute value of the spectral energy are simulated and the verification of this prediction has been carried out with comparing to the experimental data. The most desirable place for constructing new wind turbine are resulted as Point 2 and Point 3 due to the lower value of Turbulence Intensity and the higher value of wind resource relatively.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.18-27
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• 2013

This paper presents a method for assessing the wind energy potential at complex terrain using probability distribution. And the proper probability models of the parameters estimating the wind energy are presented. Finally a mixture-Weibull determined by numerical methods procedure are proposed to assess the probability distribution of the energy potential at a site. The developed method is applied to the Kwanjungchun Bridge and compared with wind records which the neighboring weather station.

• Nutritional Sciences
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• v.2 no.2
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• pp.113-118
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• 1999

Critical evaluation of energy intake data from dietary studies is difficult but important. To investigate the underreporting of total energy intake, we analyzed the one-day dietary intake data collected by 24-hour recall method from 550 elderly Koreans aged 60 years or older. Underreporting was addressed by computing the ratio of energy intake (EI) to estimated basal metabolic rate (BMRest). EI : BMRest ratio was found to be 1.38 for, men and 1.33 for women, with about 14% of men and women classified as underreporters. Underreporting of energy intake was highest in men and women who were overweight, had lower family income, or no school education. For men, the most significant variables to predict the ratio of energy intake to estimated basal metabolic. rate (EI : BMRest) were weight status, members of household, alcohol consumption and age, while income and education level were most significant for women.