• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1059-1070
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• 2016

The Prototype Gen IV sodium cooled fast reactor (PGSFR) has been developed for the last 4 years, fulfilling the technology demonstration of the burning capability of transuranic elements included in light water reactor spent nuclear fuel. The PGSFR design has been focused on the robustness of safety systems by enhancing inherent safety characteristics of metal fuel and strengthening passive safety features using natural circulation and thermal expansion. The preliminary safety information document as a major outcome of the first design phase of PGSFR development was issued at the end of 2015. The project entered the second design phase at the beginning of 2016. This paper summarizes the overall structures, systems, and components of nuclear steam supply system and safety characteristics of the PGSFR. The research and development activities to demonstrate the safety performance are also briefly introduced in the paper.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.19-26
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• 2005

Concentric evacuated tube solar energy collector has been interested recently since government has driven to install alternative energy systems in new large building. In this paper, testing of the evacuated tube collector is conducted in outdoor during daytime by transient method. The collector thermal efficiencies are plotted in term of $(T_{in}-T_a)/Ic$, where $T_{in}$ is inlet working fluid temperature, $T_a$ is atmospheric temperature and $I_c$ is solar irradiation on the collector surface. The evacuated tube collector efficiency is ranged from 50% to 63% in real outdoor condition. In addition, the total overall heat loss coefficient is found to have an inverse variation to $(T_{in}-T_a)/I_c$ so that the coefficient becomes very high when $(T_{in}-T_a)/I_c$ is small.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.3
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• pp.165-170
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• 2010

Experiments have been performed to investigate the key parameters determining the performance of thermoelectric power generation. The experimental results obtained show that the power output significantly increases with the temperature difference between cold and hot sides of thermoelectric generator. However, the effect of the hot side temperature under the identical temperature difference on the overall performance of a thermoelectric generator is meager. The conversion efficiency defined as the ratio of the power generated to the heat absorbed at the hot side increases with the temperature difference. The behavior of the thermoelectric generator is shown to be consistent with the theoretical analysis. The optimum current giving the maximum conversion efficiency and the maximum conversion efficiency are linearly increased with the temperature difference.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1096-1101
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• 2005

In this study, the experiment of thermal performance about closed-type hybrid cooling tower was conducted. A closed type cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from top part of heat exchanger to bottom side in the inner side of tube, and spray water flows gravitational direction in the outer side of it. Air contacts of tube outer side are counterflow. The heat transfer pipe used in this experiment is a bare type tube having an outside diameter of 15.88mm. In this experiment, heat performances of the cooling tower are calculated such as overall heat transfer coefficient of between the process fluid and air, cooing capacity and pressure drop.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.545-552
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• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.

• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.37-43
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• 2015

A Beta-type Stirling engine is developed and tested on the operation stability and cycle performance. The flow rate for cooling water ranges from 300 to 1500 ml/min, while the temperature of heat source changes from 300 to $500^{\circ}C$. The internal pressure, working temperatures, and operation speed are measured and the engine performance is estimated from them. In the experiment, the rise in the temperature of heat source reduces internal pressure but increases operation speed, and overall, enhances the power output. The faster coolant flow rate contributes to the high temperature limit for stable operation, the cycle efficiency due to the alleviated thermal expansion of power piston, and the heat input to the engine, respectively. The experimental Stirling engine showed the maximum power output of 12.1 W and the cycle efficiency of 3.0 % when the cooling flow is 900 ml/min and the heat source temperature is $500^{\circ}C$.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.98-109
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• 2021

Fundamental parameters describing overall operational characteristics of active cooling systems of a hypersonic flight vehicle are mainly classified into endothermic hydrocarbon fuels, regenerative cooling channels, and materials and system structures. Of primary importance is the improvement of endothermic performance of hydrocarbon aviation fuels in a series of studies developing efficient regenerative cooling systems. In a previous study, therefore, an extensive technical analysis has been carried out on thermal decomposition characteristics of liquid hydrocarbon fuels. As a subsequent study, catalytic cracking and steam reforming technologies have been reviewed to find a way for the improvement of endothermic reaction performance of hydrocarbon aviation fuels.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.665-671
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• 2017

The alkali-Metal Thermal-to-electric Converter (AMTEC) is one of the promising static energy conversion technologies for the direct conversion of thermal energy to electrical energy. The advantages over a conventional energy converter are its high theoretical conversion efficiency of 40% and power density of 500 W/kg. The working principle of an AMTEC battery is the electrochemical reaction of the sodium through an ion conducting electrolyte. Sodium ion pass through the hot side of the beta"-alumina solid electrolyte (BASE) primarily as a result of the pressure difference. This pressure difference across the BASE has a significant effect on the overall performance of the AMTEC system. In order to build the high pressure difference across the BASE, hermeticity is required for each joined components for high temperature range of $900^{\circ}C$. The AMTEC battery was manufactured by utilizing robust joining technology of BASE/insulator/metal flange interfaces of the system for both structural and electrical stability. The electrical potential difference between the anode and cathode sides, where the electrons emitted from sodium ionization and recombined into sodium, was characterized as the open-circuit voltage. The efforts of technological improvement were concentrated on a high-power output and conversion efficiency. This paper discusses about the joining and performance of the AMTEC systems.

• KIEAE Journal
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• v.15 no.5
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• pp.113-118
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• 2015

Purpose: In Korea, buildings make up 20.5% (2012) of the gross national energy consumption, so they are a major target for greenhouse gas reduction. In particular, energy consumption in multihousing represents approximately 32.6% of the entire building sector. With improving energy performance being the focus, efforts are continuously being made to reinforce standards and systems in greenhouse gas reduction. This study investigated the current status of multihousing in Korea in terms of energy performance as described in the performance evaluation reports submitted (to an institution that specializes in reviewing the performance evaluation of green homes) based on the construction criteria and performance codes for green homes and examined if the evaluation criteria using related methodologies were appropriate. The results will provide helpful information for reviewing the future directions of operations and amendments to the systems. Method: The overall characteristics of the system were examined using the evaluation methodologies (and current state of revisions) of the performance codes for green homes and comparing them with similar systems. Also, the current state of application and energy performance (conducted according to the evaluation methodologies) were compared by the evaluation institution for multihousing neighborhoods that were assessed for five years from 2010 to 2014. Result: It has been confirmed that the performance codes for green homes are different from other similar systems in evaluating performances of multihousing in that they allow both quantitative and qualitative methods of evaluation, and they consider both energy and sustainability simultaneously in the evaluation. Furthermore, regarding the adoption rate of the forms for the two evaluation methods (Form 1 - quantitative and Form 2 - qualitative), the rate preferring Form 2 increased gradually in time to reach 55.3% in 2014. In analyzing the rate of overall energy reduction (submitted in Form 1) and the coefficient of thermal transmission for each part (submitted in Form 2), it was observed that the deviation between the performance submitted and the criteria decreased in line with the level of reinforcement.

• Korean Journal of Environment and Ecology
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• v.29 no.6
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• pp.936-946
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• 2015

This study is aimed to analyze the reduction performance of building energy consumption according to planting base types of panel-type green walls which can be applied to existing buildings. The performance was compared to the general performance of green walls that have demonstrated effects of improving the thermal environment and reducing building energy consumption in urban areas. The number of planting base types was 4 in total, and simulations were conducted to analyze the thermal conductivity, thermal transmittance, and overall building energy consumption rate of each planting base type. The highest thermal conductivity by the planting base type was Case C (0.053W/mK), followed by Case B (0.1W/mK) and Case D (0.17W/mK). According to the results of energy simulation, the most significant reduction of cooling peak load per unit area was Case C (1.19%), followed by Case B (1.14%) and Case D (1.01%) when compared to Case A to which green wall was not applied; and the most significant reduction of heating peak load per unit area was estimated to be Case C (2.38%), followed by Case B (1.82%) and case D (1.50%) when compared to Case A. The amount of yearly cooling and heating energy use per unit area showed 3.04~3.22% of reduction rate. The amount of the 1st energy use showed 5,844 kWh/yr of decrease on average for other types when compared to Case A. The amount of yearly $CO_2$ emission showed 996kg of decrease on average when compared to Case A to which the green wall was not applied. According to the results of energy performance evaluation by planting location, the most efficient energy performance was eastward followed by westward, southward and northward. According to the results of energy performance evaluation by planting location by green wall ratio, it was found that as the ratio of green wall increased, the energy performance displayed better results, showing approx. double reduction rate in energy consumption at 100% of green wall ratio than the reduction rate at 20% to 80% of green wall ratio.