• Journal of Welding and Joining
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• 제15권5호
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• pp.124-133
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• 1997

Corrosion behavior of welded SWS400 steel used for bridges was studied in a range of the acid-rain environment using immersion, potentiodynamic polartization, polarization resistance, and galvanic corrosion tests. The SWS400 steel exhibited active corrosion behavior in the range of acid-rain environment, i.e. no passivation. As the results of immersion corrosion test, Tafel extrapolation method, and polarization resistance measurement, the average corrosion rats of the steels were 0.31-0.72 mm/year in the pH of 4-5, and 0.17 mm/yera in the pH 6, respectively. The steel showed a resistance to corrosion in the pH 6. The observed active behavior of SWS400 steel in chloride-containing environment indicated that the chloride ions exerts a detrimental influence on the formation of passive films. Galvanic corrosion was observed between the weld and the base metals because the weld is anodic to the base metal.

• 한국표면공학회지
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• 제47권6호
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• pp.335-340
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• 2014

This study selected an outdoor RCD'S and verified behavior of change in the housing with time. Weathering tests were carried out as outdoor exposure test (90 degrees, 37 degrees) and laboratory test (xenon lamp), and the results were evaluated based on color difference, gloss, contact angle, and optical microscope. This study can provide basic data for standardization of development and performance evaluation on RCD'S housing products.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.335-344
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• 2013

TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA) is a CubeSat with 3.14 kg in weight and 3-U ($10{\times}10{\times}30$ cm) in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultra-high vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.569-582
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• 2018

Effects of crack separation, bridge area, on the tensile behaviour of concrete are studied experimentally and numerically through the Brazilian tensile test. The physical data obtained from the Brazilian tests are used to calibrate the two-dimensional particle flow code based on discrete element method (DEM). Then some specially designed Brazilian disc specimens containing two parallel cracks are used to perform the physical tests in the laboratory and numerically simulated to make the suitable numerical models to be tested. The experimental and numerical results of the Brazilian disc specimens are compared to conclude the validity and applicability of these models used in this research. Validation of the simulated models can be easily checked with the results of Brazilian tests performed on non-persistent cracked physical models. The Brazilian discs used in this work have a diameter of 54 mm and contain two parallel centred cracks ($90^{\circ}$ to the horizontal) loaded indirectly under the compressive line loading. The lengths of cracks are considered as; 10 mm, 20 mm, 30 mm and 40 mm, respectively. The visually observed failure process gained through numerical Brazilian tests are found to be very similar to those obtained through the experimental tests. The fracture patterns demonstrated by DEM simulations are mostly affected by the crack separation but the tensile strength of bridge area is related to the fracture pattern and failure mechanism of the testing samples. It has also been shown that when the crack lengths are less than 30 mm, the tensile cracks may initiate from the cracks tips and propagate parallel to loading direction till coalesce with the other cracks tips while when the cracks lengths are more than 30 mm, these tensile cracks may propagate through the intact concrete itself rather than that of the bridge area.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2008년도 추계학술대회 논문집
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• pp.406-407
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• 2008

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2008년도 추계학술대회 논문집
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• pp.453-454
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• 2008

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.61-61
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• 2017

• 간호행정학회지
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• 제21권2호
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• pp.212-222
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• 2015

Purpose: This study was conducted to identify correlations in hospital nurses' work environment, emotional labor and happiness index to provide basic resources for nurses' happiness at work. Methods: Resources were gathered from 291 nurses who agreed to participate. Random sampling of nurses in nine hospitals in G-do was done between July 15 and August 14, 2014. Data were analyzed using ${\chi}^2$ tests, independent t-test, One-way ANOVA, Pearson correlation coefficients and multiple hierarchical regression with SPSS/WIN 18.0. Results: Mean scores (scale of 5) were nurses' work environment, 2.81, emotional labor, 3.24, and happiness index, 2.94. There were significant differences on the happiness index for: age, marriage, children, clinical experience, position, payment, and future work plans and a negative correlation between work environment and emotional labor, emotional labor and happiness index but a positive correlation between happiness index and work environment. Happiness index was influenced by work environment, emotional labor, future work plans. Explanatory power of these variables was 26%. Conclusion: Based on the findings of this study, so it is necessary to improve the work environment and reduce the frequency of emotional labor in order to increase the happiness index of hospital nurses.

• 한국물환경학회지
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• 제21권2호
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• pp.132-140
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• 2005

The pilot test of a new alternative for small wastewater treatment system has been conducted for two years. It consists of a hybrid bioreactor and the expert system including the process control logic, PLC system, and HMI for the process automation. In order to monitor and remote control its status, the real-time data was transferred from the on-site control center to the central station via a wireless local area network. More efficient and stable performances were observed at automatic operating mode compared with the manual. On an average, COD, SS, T-N and T-P concentrations in the effluent from the hybrid bioreactor were less than 14, 7, 12 and 0.9 mg/L, respectively. According to the result from pilot tests, the quality of treated wastewater with sand filtration was enough to be utilized again.

• 한국산업융합학회 논문집
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• 제25권5호
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• pp.843-851
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• 2022

This paper was conducted to study the conditions for the manufacture and operation of artificial snow removal and ice-making test facilities so that the test equipment can be tested in a low-temperature environment using the polar environment performance test facility. The polar environment performance test Facility is designed to artificially simulate extreme environments up to -65 ℃, and is a mid-to-large low-temperature environment test facility that can perform performance tests on offshore plant equipment, ships, leisure, and offshore structures. To verify the safety of deck work of ships operating in polar environments, artificial snow removal and artificial ice making devices were manufactured, and we conducted research on various operating environments using these facilities. For the efficient operation of artificial snow and ice making facilities, it is important to continuously supply dry air, and it has been found that installing an additional heater at the tip of the nozzle is effective in preventing freezing.