• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.103-110
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• 2022

Ultrafine Particle number and size distributions were simultaneously measured at rural area around the power plant in Dangjin, South Korea. New Particle formation and growth events were frequently observed during January, 2021 and classified based on their strength and persistence as well as the variation in geometric mean diameter(GMD) on January 12, 21 and 17. In this study, we investigated mechanisms of new particle growth based on measurements using a high resolution time of flight aerosol mass spectrometer(HR-ToF-AMS) and a scanning mobility particle sizer(SMPS). On Event days(Jan 12 and 21), the total average growth rate was found to be 8.46 nm/h~24.76 nm/hr. These growth rate are comparable to those reported for other urban and rural sites in South Korea using different method. Comparing to the Non-Event day(Jan 17), New Particle Growth mostly occurred when solar radiation is peaked and relative humidity is low in daytime, moreover enhanced under the condition of higher precusors, NO₂ (39.9 vs 6.2ppb), VOCs(129.5 vs 84.6ppb), NH₃(11 vs 4.7ppb). The HR-ToF-AMS PM_1.0 composition shows Organic and Ammoniated nitrate were dominant species effected by emission source in domestic. On the other hand, The Fraction of Ammoniated sulfate was calculated to be approximately 16% and 31% when air quality is inflow from China. Longer term studies are needed to help resolve the relative contributions of each precusor species on new particle growth characteristics.

• Journal of Powder Materials
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• v.30 no.1
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• pp.22-28
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• 2023

The global demand for raw lithium materials is rapidly increasing, accompanied by the demand for lithiumion batteries for next-generation mobility. The batch-type method, which selectively separates and concentrates lithium from seawater rich in reserves, could be an alternative to mining, which is limited owing to low extraction rates. Therefore, research on selectively separating and concentrating lithium using an electrodialysis technique, which is reported to have a recovery rate 100 times faster than the conventional methods, is actively being conducted. In this study, a lithium ion selective membrane is prepared using lithium lanthanum titanate, an oxide-based solid electrolyte material, to extract lithium from seawater, and a large-area membrane manufacturing process is conducted to extract a large amount of lithium per unit time. Through the developed manufacturing process, a large-area membrane with a diameter of approximately 20 mm and relative density of 96% or more is manufactured. The lithium extraction behavior from seawater is predicted by measuring the ionic conductivity of the membrane through electrochemical analysis.

• Journal of Korean Physical Therapy Science
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• v.29 no.4
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• pp.86-95
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• 2022

Background: The purpose of this study is to investigate the effect of ultra-thin microcurrent patch application on pain, tenderness, trunk flexion, and trunk extension in patients with back pain. Design: pretest-posttest design: single blind. Methods: Thirty men and women diagnosed with chronic back pain were classified into 15 microcurrent application groups and 15 placebo groups. Changes in pain were observed on a visual analog scale, tenderness was observed with a digital tenderness meter, and changes in trunk flexion and trunk extension angles were evaluated with a posture analyzer. The paired t-test was used to see the changes within each group before and one week after the experiment, and the independent t-test was used to see the change in the difference between the groups, and the significance level was 0.05. Results: In both the experimental group and the control group, there was a significant difference in pain within and between groups(p<0.05). In the experimental group, there were significant differences in the intra- and inter-group changes in the erector spinae muscle tenderness and low back pain disorder index(p<0.05). In the experimental group, there was a significant difference in the change in trunk flexion and extension within the group(p<0.05). Conclusion: In this study, it was confirmed that the application of ultra-thin microcurrent was effective for pain, tenderness, and movement of back extension in patients with low back pain. It is expected that it will be used as a basic data for microcurrent therapy and as a treatment method for improving the function of patients with back pain in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.63-77
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• 2023

This study applies reinforcement learning to effectively operate expressway hard shoulder running (HSR). An HSR algorithm was developed, and its effectiveness was evaluated using the VISSIM microscopic simulation program. The simulation evaluated two aspects: mobility and safety. The DQN-based HSR algorithm found speed improvement of up to 26 km/h. Compared to the current method, the difference in the number of conflicts was not significant. Considering the results, a DQN-based HSR operation has a clear effect, and it is necessary to consider adjusting the current operational criteria.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.97-113
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• 2023

Swift and appropriate responses in emergency situations like objects falling on the road can bring convenience to road users and effectively reduces secondary traffic accidents. In Korea, current intelligent transportation system (ITS)-based detection systems for emergency road situations mainly rely on loop detectors and CCTV cameras, which only capture road data within detection range of the equipment. Therefore, a new detection method is needed to identify emergency situations in spatially shaded areas that existing ITS detection systems cannot reach. In this study, we propose a ResNet-based algorithm that detects and classifies emergency situations from vehicle camera footage. We collected front-view driving videos recorded on Korean highways, labeling each video by defining the type of emergency, and training the proposed algorithm with the data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.4
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• pp.84-94
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• 2023

The wave height and period regression curve is widely used to estimate the design wave period. In this study, the parameters of the curves are estimated, compared, and evaluated using the linear, robust linear, and nonlinear regression methods, respectively. The data used in the design wave height estimation are the annual maxima (AM) wave height and period data sets divided by typhoon and non-typhoon conditions, provided by the Ministry of Oceans and Fisheries (2019). The estimation parameters show significant differences in the local coastal waters and the estimation methods. The estimation parameters based on the Suh et al. (2008, 2010) method show the apparent bias, under-estimation in the intercept (scale) parameter, and over-estimation in the slope (exponent) parameter, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.83-83
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• 2003

The stochiometric mix of evaporating materials for the CuInSe$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CuInSe$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 62$0^{\circ}C$ and 41$0^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of CuInSe$_2$ single crystal thin films measured from Hall effect by van der Pauw method are 9.62$\times$10$^{16}$ cm$^{-3}$ , 296 $\textrm{cm}^2$/V.s at 293 K, respectively From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the CuInSe$_2$ single crystal thin film, we have found that the values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 6.1 meV and 175.2 meV at 10 K, respectively. From the photoluminescence measurement on CuInSe$_2$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$,X) having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral donor bound excition were 7 meV and 5.9 meV, respectivity. By Haynes rule, an activation energy of impurity was 59 meV.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.761-768
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• 2022

In the hope of realizing carbon neutrality, Korea has established the goal of expanding the supply of hydrogen electric vehicles through a roadmap to revitalize the hydrogen economy. A prerequisite for successful supply expansion is securing the safety of hydrogen electric vehicles. Certain parts, such as the hydrogen transport pipe and tank, in hydrogen electric vehicles are exposed to high-pressure hydrogen gas over long periods of time, so the hydrogen enters the grain boundary of material, resulting in a degradation of the parts referred to as hydrogen embrittlement. In addition, since the safety of parts utilizing hydrogen varies depending on the type of material used and its environmental characteristics, the necessity for the enactment of a hydrogen embrittlement regulation has emerged and is still being discussed as a Global Technical Regulation (GTR). In this paper, we analyze a hydrogen compatibility material evaluation method discussed in GTR and present a direction for the development of Korean-type hydrogen compatibility material evaluation methods.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.70-75
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• 1997

An improved technique based upon an electron beam evaporation system has been developed to prepare cubic thin films In crystalline semiconductors. Zinc blonde CdSe epilayers were grown on GaAs(100) substrate by an e-beam evaporation method. The lattice parameter obtained from (400) reflection is $6.077\AA$, which is in excellent agreement with the value reported in the literature for zinc blonde CdSe. The orientation of the as-grown CdSe epilayer is determined by electron channeling patterns. The crystallinity of epitaxial CdSe layers were investigated on the double crystal X-ray rocking curve. The carrier concentration and mobility of epilayers deduced by Hall effect measurement are about $10^{18}{\textrm}{cm}^{-3}$, $10^2\textrm{cm}^2/V{\cdot}sec$ at room temperature, respectively. The photocurrent spectrum peak of the epilayer at 30 K exhibits a sharp change at 1.746 eV due to the free exciton of cubic CdSe.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.59-70
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• 2010

A long-term field demonstration experiment on selected stabilization methods to reduce the heavy metal mobility in farmland soil contaminated by heavy metals was conducted. The field demonstration experiment was established on the contaminated farmland with wooden plates (thickness = 1 cm), of which the dimension were width = 200 cm, Length = 200 cm, height = 80 cm, filled with treated soil, which was mixed with lime stone and steel refining slag except on control plot. Soil samples in the plots were collected and analyzed during the experiment period (6 months) after the installation of the plots. The field demonstration experiment results showed that the application lime stone at the ratio of 5% was effective for immobilizing heavy metal components in contaminated farmland soil.