• Journal of the Korean Solar Energy Society
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• v.40 no.2
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• pp.25-36
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• 2020

The Korean government has a plan to mandate zero-energy buildings in 2020 for public and 2025 for private buildings. In order to design a zero-energy building, insulation and airtightness, which are the most basic elements of passive house technology, are required, and the government has been accomplished this through step-by-step strengthening of related standards. In passive house with high thermal insulation and airtightness performance, the heat introduced into the building through solar radiation can be stored for a long time to keep the inside warm during winter. On the other hand, during summer, heat introduced into the building cannot be easily released to outside, so it is necessary to actively block solar radiation and high temperature outdoor air to prevent an increase of indoor temperature. Therefore, this study aims to derive an appropriate operation condition of passive house to maintain the indoor temperature at an suitable level according to the ventilation methods and solar shading conditions. As a result, under the conditions that the outdoor temperature was 28℃ or less, the ventilation using a heat recovery ventilation system at daytime and natural ventilation at nighttime were selected for the most appropriate operation method. In addition, in the case of solar shading, it was found that blocking solar radiation at daytime using the blind and open the blind at nighttime to ensure natural ventilation were selected for the most appropriate solar shading condition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.4
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• pp.175-184
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• 2017

With the improvement of living standards, the ventilation for the mitigation of indoor or outdoor air-pollution problems has recently attracted a lot of attention. Consequently, the ventilation for the supply of outdoor fresh air into a room is treated as an important building-design factor. The ventilation is generally divided into the forced and natural types; here, the former can control the ventilation rate by using mechanical devices, but it has the disadvantages of the equipment costs, maintenance costs, and noise generation, while the latter is applied to most workshops due to the absence of noise and the low installation and maintenance costs. In this experimental study, the ventilation performance of a typical rotating-type natural ventilator, which is called a "wind turbine," was investigated with the outdoor-wind velocity and the indoor/outdoor-temperature difference. From the experiment results, it was confirmed that the temperature difference of $10^{\circ}C$ corresponds to the ventilation driving force with an outdoor-wind velocity of 1.0 m/s. Additionally, the intake-opening area of a building also exerts a great effect on the ventilation rates.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.111-117
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• 2019

An experimental study on the welding part of a heat transfer plate that constitutes the lightweight and high efficiency recuperator is presented in this paper. In particular, to find out the service life of the welded part, fatigue characteristics were determined through experiments. Experiments were carried out on two materials (STS347, AL20-25 + nb), which are selected as the material of the recuperator; further, the specimens were manufactured through the methods used for actual fabrication and the standards recommended by ASTM. To evaluate the mechanical properties of the specimens at room and high temperature, MTS-810 was used in a high-temperature furnace. The tensile test was carried out at room and high temperatures for each specimen. The fatigue test was carried out by setting the load ratio corresponding to 50%, 40%, 30%, 20%, and 10% of the tensile strength at the stress ratio of 0.1. Finally, the fatigue life characteristics obtained by the experiment were compared with the stresses owing to the load generated in the operating conditions of the recuperator, and the lifetime of the welds was evaluated to prepare for the operation time required by the UAV.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.289-295
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• 2005

Instrumentation and Control (I&C) of the Neutral Beam Test Stand (NB- TS) Facility at the Korea Atomic Energy Research Institute (KAERI) for the Korea Superconducting Tokamak Advanced Research (KSTAR) project has been underway since the start of the project to answer the diverse requests arising from the various facets of the development and construction phases of the project. Optical signal transmission constitutes a significant portion of I&C works and has been performed for the entirety of the project. During the NB- TS construction and related experiments, significant achievements to a more accurate as well as more refined optical signal transmissions have been made. Examples of those I&C works that utilized the optical signal transmission are the Langmuir probe signal transmission, gradient grid current signal transmission, gas flow control and signal transmission, ion source temperature measurement, beam line component temperature monitoring, and coolant flow signal transmission, etc. These optical signal transition provisions are now performing part of the indispensable functions for the proper operation of the NB- TS facility. Attained experience and expertise are expected to be well applied to the upcoming main neutral beam injection (NBI) system construction for the KSTAR project.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.11
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• pp.998-1004
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• 2005

Recently natural ventilation rate is decreased due to the airtightness of apartment building. Therefore the use of heat recovery ventilator (HRV) has been greatly increased as an alternative method to supply fresh air and save energy in the building. In this research the experiment standard of HRV is compared between KS and JIS and the sensitivity analyses are experimented by both standards. Under cooling experiment condition indoor and outdoor wet-bulb temperature difference of JIS is 2 to 3 times higher than that of KS. It shows that the efficiency measurement of HRV by KS is expected to have greater sensitivity than by JIS and thus accurate measurement of web-bulb temperature is required. The experimental results provide that the efficiency of thermal exchange is resemblance to each others between KS and JIS. Under cooling experiment condition the efficiency of humidity exchange by KS presents higher than by JIS, however, under heating experiment condition the efficiency by KS shows lower than by JIS, reversely.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.525-531
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• 2004

In this paper, the concept of infrared thermography(IRT), the principle of measurement of IRT and how to set up the IR camera for the nondestructive testing are described in detail. Also, its utilization and non-destructive testing(NDT) diagnosis are reviewed. By performing the periodic non-touched WDT through the estimation of thermal patterns related with the temperature for the surface targeted, IRT can be applied to the early prevention of the device failure. For the diagnosis utilization, thermal imaging patterns obtained from IRT for heated blocks with internal defects were estimated through the lion-destructive method and discussed the way of IRT estimation from the analysis of characteristics between material defects and thermal imaging patterns.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.574-583
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• 2004

In this study, the operation strategy of the radiant floor cooling is evaluated in terms of indoor environmental conditions and energy consumption through simulations using the TRNSYS comparing the existing cooling operation. The operation strategy during continuously operated for cooling is proposed that a representative room had additional equipments and other rooms were operated with only a radiant floor cooling system and that system and control method for cooling are varied with period while intermittently operated for cooling. Specifically, when there are no people in the room, rooms were operated by only radiant floor cooling system using cooling storage and when people are occupied, rooms were operated by dehumidification and supplementary cooling device with radiant floor cooling system. The results of this study show that proposed operation strategy can stably maintain the set room air temperature and can reduce the energy consumption compared to the existing cooling method during continuously operated for cooling. While intermittently operated for cooling, the difference of set room air temperature by proposed operation strategy does not happen, satisfying comfort standards and the radiant floor cooling can expect to supply stable electric power because of decreasing demand for peak electric power of energy consumption.

• Fire Science and Engineering
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• v.30 no.2
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• pp.49-55
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• 2016

It is necessary to obtain a fire resistance certification in order to use Fire Protection Coating in Korea. According to the fire test standards, columns have four heating sides and beams have three. In comparison with columns which are heated four sides equally, beams have three exposed sides and one unexposed up side. So the question arises as to there were the differences between the temperature of up side and others of beams in fire test. The purpose of this study is to consider the positions of thermocouples for beams through a comparative analysis of the temperature data obtained from fire certification tests.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.591-598
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• 2005

A three-way catalyst system of a natural gas vehicle (NGV) has characteristics of higher fuel consumption and higher thermal load than a lean-bum catalyst system. To meet stringent emission standards in the future, NGV with the lean-bum engine may need a catalyst system to reduce the amounts of HC, CO and NOx emission, although natural gas system has low emission characteristics. We conducted experiments to evaluate the conversion efficiency of the NOx reduction catalyst for the lean-burn natural gas engine. The NOx reduction catalysts were prepared with the ${\gamma}-Al_{2}O_3$ washcoat including Ba based on Pt, Pd and Rh precious metal. In the experiments, effective parameters were space velocity, spike duration of the rich condition, and the temperature of flowing model gas. From the results of the experiments, we found that the temperature for maximum NOx reduction was around $450^{\circ}C$, and the space velocity for optimum NOx reduction was around $30,000\;h^{-1}$ And we developed an evaluation model of the NOx reduction catalyst to evaluate the conversion performance of each other catalysts.

• Science of Emotion and Sensibility
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• v.16 no.3
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• pp.305-310
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• 2013

This user-centered research aims to empirically evaluate color temperature (K) and illuminance (lx) of residential bathroom lightings to determine the most optimal lighting conditions for productive task performance as well as for satisfying users' emotional needs. Using 3 LED lighting fixtures, 4 types of lighting contexts were investigated; main lighting, task lighting, shower lighting, and bath lighting. Two lightings were installed parallel to the vertical edges of the main bathroom mirror to be used as main and task lighting, while another fixture was installed above the bathtub to be used for shower and bathing. For each lighting context, subjects (N＝54) were instructed to perform a few tasks during which time the users were exposed to different lighting conditions with color temperature ranging from 2700 K ~ 6500 K and illuminance ranging from 100 lx ~ 700 lx. Upon completing the given tasks, subjects were asked to evaluate the lighting conditions and their applicability for performing the given tasks. Based on the user evaluations, the most optimal lighting conditions for the different lighting scenarios are as follow: 1) 3500 K ~ 4300 K and 150 lx for main lighting, 2) 3500 K ~ 4300 K and 500 lx ~ 700 lx for task lighting, and 3) 2700 K ~ 3500 K and 100 lx ~ 150 lx for shower/bath lighting. These results can be used to adjust the lighting standards suggested by KS, as well as be utilized by both engineers and designers in designing new types of user-centered bathroom lightings.