• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.29 no.9
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• pp.56-62
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• 2000

1997년 12월 일본 교토에서 개최된 COP3를 계기로 1999년 3월 에너지보존법이 대폭적으로 개정 및 강화되어졌다. 지구온난화의 주된 원인이 되는 이산화탄소는 에너지와 밀접한 관계를 가지고 있으므로, 에너지보존·자원보존의 추진은 지구온난화 대책의 추진과 동등한 의미를 가지고 있다고 하여도 과언이 아니다. 여기서는 건축설비계획의 관점에서 에너지보존법 개정의 요점과 그 대응책에 관해서 개요를 소개하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.4
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• pp.131-136
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• 2016

Horizontal geothermal heat exchanger is affected by various factors such as pipe length, soil temperature, and outdoor environment. Simulation program is convenient for responding to various factors. The objective of this study was to determine the feasibility of using EnergyPlus to predict exit air temperature through horizontal geothermal heat exchanger in domestic. The correlation coefficient between EnergyPlus results and experimental results was 0.825. The correlation coefficient between EnergyPlus results and mathematical results was 0.722, indicating "The two values can based on Lousi on values can be Our results indicate that it is possible to use EnergyPlus to predict exit air temperature through horizontal geothermal heat exchanger.

• New & Renewable Energy
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• v.9 no.1
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• pp.60-68
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• 2013

In recent years, green house effect related natural disasters occur throughout the world. Carbon dioxide, mainly comes from the fossil fuel burning, is suspected to be the cause of green house effect. To reduce the emission of carbon dioxide, we need to find alternative energy resources such as photovoltaic energy. In this paper, the basic characteristics of wind force coefficient on a PV panel installed on the floating type PV energy generation system are investigated though the two-dimensional wind tunnel tests. Test variables included the angle of PV panel, direction of wind, number of rows of PV panel and attached or not attached frame. Based on the results obtained through the wind tunnel tests, it was found that the wind force coefficient can be used as a preliminary data in the design of the structure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.159-166
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• 2018

The Korean fenestration energy consumption efficiency rating system only considers thermal performance of the heat transfer coefficient (U-value) and airtightness excluding optical characteristics of the solar heat gain coefficient (SHGC). This study analyzed annual heating and cooling energy requirements on the middle floor of apartment by optical and thermal performance of windows to evaluate the suitability of the rating system. One hundred and twenty-eight windows were analyzed using THERM and WINDOW 7.4, and energy simulation for a reference model of an apartment house facing south was performed using TRNSYS 17. The results showed that window performance was the main factor in the heating and cooling load. The heating load of the reference model was 539 kWh to 2,022 kW, and the cooling load was 376 kWh to 1,443 kWh. The coefficient of determination ($R^2$) of the heating and cooling loads driven from the SHGC were 0.7437 and 0.9869, which are more compatible than those from the U-value, 0.0558 and 0.4781. Therefore, it is not reasonable to evaluate the energy performance of windows using only the U-value, and the Korean fenestration energy consumption efficiency rating system requires a new evaluation standard, including SHGC.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.38-43
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• 2010

Enhancement of exterior's insulation performance like wall or window etc. is general way for building's energy efficient and thermal performance. But exterior's opening plan is important for minimizing the energy consumption and heat loss. In this paper, energy saving rate will be analyzed and compared considering the window area's rate and window's SC(Shading Coefficient) in a apartment with Building Energy Efficiency Rating System's evaluation tool. In the process of evaluation, energy saving rate is measured at each stage of the window area's rate from 20% to 60% every 10% term and the shading coefficient value from 1.0 to 0.6. As a result of this research, energy saving evaluation could not be measured exactly with existing evaluation tool. Accord this research, Building Energy Rating System's evaluation range is needed to be broaden for exact evaluation of energy saving rate.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.303-309
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• 2004

In this paper, an interfacial crack length has been detected by using the ultrasonic attenuation coefficient on the adhesively bonded double-cantilever beam (DCB) joints. The correlations between energy release rates which were investigated by experimental measurement, the boundary element method (BEM) and Ripling's equation are compared with each other. The experimental results show that the interfacial crack length for the ultrasonic attenuation coefficient and energy release rate increases proportionally. From the experimental results, we propose a method to detect the interfacial crack length by using the ultrasonic attenuation coefficient and discuss it.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1109-1114
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• 2003

The initial crack often occurs on the bonded interface and it is the general cause of the interface fracture. It is very significant to establish the measurement method of interfacial crack by applying the ultrasonic technology into the interface of bonded dissimilar materials. In this paper, the interfacial crack length was measured by ultrasonic attenuation coefficient in the Al/Epoxy bonded dissimilar materials of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental and Ripling's equation measurement of compliance. The experimental results represent that the relation between interfacial crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. From the experimental results, a measurement method of the interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.161-166
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• 2011

This paper proposes an algorithm for determining critical generator lists using accelerating power and synchronizing power coefficient (SPC), and critical generator group (CGG) from CGG candidates, which is a combination of critical generators. The accurate determination of CGG provides a more accurate energy margin while providing system operator with information of possible unstable generator group. Classical transient energy function (TEF) method selects the critical generators with big corrected kinetic energy of each generator at the moment of fault removal. However, the generator with small acceleration after fault, that is, the generator with small corrected kinetic energy, is also likely to belong to CGG if the generator has small synchronizing power. The proposed algorithm has been verified to be effective compared with the classical TEF method. We utilized the power system of Korean Electric Power Corporation(KEPCO) as a test system.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.856-862
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• 2015

Tidal current energy is an important alternative energy resource among the various ocean energy resources available. The tidal currents in the South-Western sea of Korea can be utilized for the development of tidal current power generation. Tidal power generation can be beneficial for many fishing nurseries and nearby islands in the southwest region of Korea. Moreover, tidal power generation is necessary for promoting energy self-sufficient islands. As tidal currents are always available, power generation is predictable; thus, tidal power is a reliable renewable energy resource. The selection of an appropriate hydrofoil is important for designing a tidal current turbine. This study concentrates on the selection and numerical analysis of four different hydrofoils (MNU26, NACA63421, DU91_W2_250, and DU93_W_210LM). Blade element momentum theory is used for configuring the design of a 50 W class turbine rotor blade. The optimized blade geometry is used for computational fluid dynamics (CFD) analysis with hexahedral numerical grids. Among the four blades, NACA63421 blade showed the maximum power coefficient of 0.45 at a tip speed ratio of 6. CFD analysis is used to investigate the power coefficient, pressure coefficient, and streamline distribution of a 50 W class horizontal axis tidal current turbine for different hydrofoils.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.321-328
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• 2006

In the present study extensisve numerical experiments are conducted using the CFD code, FLUENT, to investigate the energy dissipation due to perforated walls for various wall-thickness and flow conditions. A new empirical formula for energy loss coefficient considering the effect of the thickness of perforated wall is obtained based on the results of computational experiments. It is found that the energy loss coefficient decreases as the wall-thickness increases and the maximum coefficient reduction reaches upto 40% of the value calculated using the conventional formulas for the sharp-crested orifice. To check the validity of the new formula the reflection coefficient of waves due to perforated wall is evaluated and compared with the results of existing theories and hydraulic experiments. The result shows that the new formula is superior to the conventional ones.