• Korean Journal of Agricultural Science
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• v.51 no.3
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• pp.375-389
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• 2024

Soil erosion, a critical environmental issue primarily driven by water and wind, has severe consequences, including the loss of fertile agricultural land, degradation of water quality, and sediment accumulation in riverbeds. This study utilized the SSEM (surface soil erosion model), a physically-based distributed model, to simulate the rainfall-runoff-sediment dynamics associated with short-term rainfall events in the Naerin River basin. A spatial analysis of erosion and deposition was conducted, taking into account topographical factors such as local slope and overland flow length. The study area was segmented into six sub-catchments using Strahler's stream order method to examine the correlation between geographic factors and erosion or deposition. The findings revealed that erosion was predominant within flow path distances of 0 - 1 km (adjacent to the river) and 3 - 4 km (in the upper catchment areas). Notably, deposition did not occur in areas beyond 2.5 km from the river. Furthermore, it was observed that average erosion depth increased on steeper slopes (exceeding 0.3 - 0.4 degrees), whereas deposition was absent in these steep slope classes.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.1-13
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• 2016

Groundwater flow paths and groundwater ages at a radioactive waste repository located in a coastal area of South Korea were evaluated using the hydrochemical and hydrogeological characteristics of groundwater, surface water, rain water, and seawater, as well as by numerical modeling. The average groundwater travel time in the top layer of the model, evaluated by numerical modeling and groundwater age (34 years), approximately corresponds to the groundwater age obtained by chlorofluorocarbon (CFC)-12 analysis (26-34 years). The data suggest that the groundwater in wells in the study area originated up-gradient at distances of 140-230 m. Results of CFC analyses, along with seasonal variations in the δ¹⁸O and δD values of groundwater and the relationships between ²²²Rn concentrations and δ¹⁸O values and between ²²²Rn concentrations and δD values, indicate that groundwater recharge occurs in the summer rainy season and discharge occurs in the winter dry season. Additionally, a linear relationship between dissolved SiO₂ concentrations and groundwater ages indicates that natural mineralization is affected by the dilution of groundwater recharge in the rainy summer season.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.179-184
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• 2007

The boiling heat transfer was experimentally investigated for the FC-77 sprays impacting a square heated test surface in a downward direction. Full cone spray nozzles were employed for the spray cooling experiment, and experiments were made under the test conditions of $Q=3.32{\times}10^{-6}{\sim}2.30{\times}10^{-5}\;m^3/s$, ${\Delta}T_{sub}=20{\sim}70^{\circ}C$. Also, heat transfer measurements were made using the copper block of $10{\times}10\;mm^2$ test area heated by nine cartridge heater. From the experimental results, correlation between the Nusselt number and Reynolds number based on droplet-flow-rate was developed. The correlation shows good predictions with ${\pm}30%$ error for FC-77.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.12
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• pp.938-944
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• 2008

The boiling heat transfer was experimentally investigated for the PF-5052 sprays impacting a square heated test surface in a downward direction. Full cone spray nozzles were employed for the spray cooling experiment, and experiments were made under the test conditions of Q=$3.32{\time}10^{-6}{\sim}\;12.98{\time}10^{-6}m^3/s$, ${\Delta}T_{sub}=5{\sim}25^{\circ}C$. Also, heat transfer measurements were made using the copper block of $10{\time}10mm^2$ test area heated by nine cartridge heater. From the experimental results, correlation between the Nusselt number and Reynolds number based on droplet-flow-rate was developed. The correlation shows good predictions with ${\pm}30$ % error for PF-5052.

• Journal of the Ergonomics Society of Korea
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• v.29 no.6
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• pp.853-860
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• 2010

This study investigated differences in blood oxygen saturation($SpO_2$) and heart rate(HR) according to flow rate, gender, and phase in males and females in their 60s when the supply of 93% highly concentrated oxygen administration was changed (1L/min, 3L/min, and 5L/min). It recruited totally 20 elderly subjects including 10 males($68.0{\pm}2.6$ years) and 10 females ($65.5{\pm}3.1$ years). The experiment consisted of three phages of Rest 1(5 min), Hyperoxia(10 min), and Rest 2(10 min), and $SpO_2$[%] and HR[bpm] were measured during all phages. $SpO_2$ was higher in Hyperoxia phase supplied with highly concentrated oxygen than in Rest phases. Higher flow rate was associated with more increase in $SpO_2$. HR was reduced in Hyperoxia phase compared to Rest phases. More supply of highly concentrated oxygen was associated with more decrease of HR. However, there were no differences in both $SpO_2$ and HR according to gender.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.169-175
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• 2018

This study deals with a process for the recovery of hydrogen isotopes from methane ($CQ_4$) and water ($Q_2O$) containing tritium in the nuclear fusion exhaust gas (Q is Hydrogen, Deuterium, Tritium). Steam Methane Reforming and Water Gas Shift reactions are used to convert $CQ_4$ and $Q_2O$ to $Q_2$ and the produced $Q_2$ is recovered by the subsequent Pd membrane. In this study, one circulation loop consisting of catalytic reactor, Pd membrane, and circulation pump was applied to recover H components from $CH_4$ and $H_2O$, one of $CQ_4$ and $Q_2O$. The conversion of $CH_4$ and $H_2O$ was measured by varying the catalytic reaction temperature and the circulating flow rate. $CH_4$ conversion was 99% or more at the catalytic reaction temperature of $650^{\circ}C$ and the circulating flow rate of 2.0 L/min. $H_2O$ conversion was 96% or more at the catalytic reaction temperature of $375^{\circ}C$ and the circulating flow rate of 1.8 L/min. In addition, the amount of $CQ_4$ generated by Korean Demonstration Fusion Power Plant (K-DEMO) in the future was predicted. Then, the treatment process for the $CQ_4$ was proposed and HAZOP (hazard and operability) analysis was conducted to identify the risk factors and operation problems of the process.

• The Korean Journal of Nuclear Medicine
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• v.22 no.2
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• pp.163-170
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• 1988

8 patients of delayed CO sequelae were evaluated using Brain CT and $^{99m}Tc-HMPAO$ SPECT. The results were as follows; 1) CT findings of delayed CO sequleae were bilateral low density lesion in globus pallidus (l pt.), diffuse low density in white matter with bilateral low density in white matter (l pt.), diffuse low density in white matter with bilateral low density in globus pallidus (l pt.), diffuse low density in white matter with cortical atrophy (l pt.), bilateral low density in globus pallidus and diffuse low density in white matter with cortical atrophy (l pt.) and normal in 3 pts. 2) $^{99m}Tc-HMPAO$ Brain SPECT findings of delayed CO sequelae were decreased regional cerebral blood flow (rCBF) in frontal (1 among 8 pts.), frontal and basal ganglia (3 among 8 pts.), and diffuse patch decreased rCBF pattern (4 among 8 pts.) 3) $^{99m}Tc-HMPAO$ Brain SPECT study was well correlated with neurologic symptoms and signs in delayed CO sequelae. Our results may suggest that reduced cerebral blood flow contributes to the development of delayed CO sequelae.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.688-698
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• 2015

This paper presents a modeling and a controller design for a hybrid wind turbine generator, especially with an operating mode of battery energy-storage system and a dumpload that contribute to the frequency control of the system while diesel-synchronous unit is not in operation. The proposed control scheme is based on a robust tracking controller, which takes an account of system uncertainties due to the wind flow and load variations. In order to provide robustness for system uncertainties, the range of operation is partitioned into three operating conditions as sub-models in the controller design. In the simulation study, the proposed robust tracking controller (RTC) is compared with the conventional proportional-integral (PI) controller. Simulation results show that the effectiveness of the RTC against disturbances caused by wind speed and load variation. Thus, better quality of the hybrid wind power system is achieved.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.3
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• pp.143-154
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• 2013

Purpose: This study was to find efficacy of integrin alpha2 (${\alpha}_2$) and epidermal growth factor receptor (EGFR) as tumor marker of oral squamous cell carcinoma (SCC) and clarify the selective cell death effect of anti-integrin ${\alpha}_2$ and anti-EGFR on SCC cells, additionally testify conjugated gold nanoparticles (GNP) with air plasma for selective cell death of oral SCC. Methods: Expression of integrin ${\alpha}_2$, EGFR on human SCC cells (SCC25) were examined by western blot. SCC25 cells were treated with anti-integrin ${\alpha}_2$, anti-EGFR and analysed by Hemacolor staining, immunoflorescence staining, FACS flow cytometry. Conjugated GNP with integrin ${\alpha}_2$, EGFR antibody were treated by air plasma on SCC cells. Results: Integrin ${\alpha}_2$ and EGFR were over-expressed on SCC25 cells than normal lung WI-38 cells. The cell viability rate of SCC25 cells treated with anti-integrin ${\alpha}_2$, anti-EGFR was lower than WI-38 cells. The concentration changes of nucleus, releasing cytochrome c and apoptosis inducing factor (AIF) from mitochondria to cytosol were observed. The changes of proteins related with apoptosis were observed. Increase of bax, bcl-xL, activation of caspase-3, -7, -9, and fragmentation of PARP, DFF45 and decrease of lamin A/C in SCC25 cells were observed. In FACS, increase of sub-$G_1$ and S phase was observed. Cell cycle related proteins, Such as cyclin D1, cyclin dependent kinase (CDK) 4, cyclin A, cyclin E, CDK 2, p27 were decreased. After SCC25 cells treated with conjugatged GNP-Integrin ${\alpha}_2$, GNP-EGFR, additionally air plasma, the cell death rate was significantly increased. Conclusion: Integrin ${\alpha}_2$, EGFR were over-expressed in oral SCC cells. Anti-integrin ${\alpha}_2$, anti-EGFR in SCC25 cells induced apoptosis selectively. When GNP-anti integrin ${\alpha}_2$, GNP-anti EGFR were treated with air plasma on SCC25 cells, cancer cells were died more selectively. GNP-anti integrin ${\alpha}_2$, GNP-anti EGFR with air plasma could be treatment choice of oral SCC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.737-744
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• 2016

The printed circuit heat exchanger (PCHE) is regarded as a promising candidate for advanced heat exchangers for the next-generation supercritical $CO_2$ power generation owing to its high compactness and rigid structure. In this study, an innovative type of PCHE, in which the channel sizes for the heat source fluid and heat sink fluid are different, is considered for analysis. The thermal performance of the PCHE, with supercritical $CO_2$ as the working fluid, is numerically analyzed. The results have shown that the thermal performance of the PCHE decreases monotonically when the channel size of either the heat source channel or the heat sink channel, because of the decreased flow velocity. On the other hand, the thermal performance of the PCHE is found to be almost independent of the spacing between the channels. In addition, it was found that the channel cross sectional shape has little effect on the thermal performance when the hydraulic diameter of the channel remains constant.