• Journal of Korean Neurosurgical Society
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• v.29 no.4
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• pp.461-470
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• 2000

Objective : Many investigators have demonstrated the protective effects of hypothermia following traumatic brain injury(TBI) in both animals and humans. It has long been recognized that mild to moderate hypothermia improves neurologic outcomes as well as reduces histologic and biochemical sequelae after TBI. In this study, two immunohistochemical staining using terminal deoxynucleotidyl-transferase-mediated biotin dUTP nick end labeling(TUNEL), staining of apoptosis, and ${\beta}$-amyloid precursor protein(${\beta}$-APP), a marker of axonal injury, were done and the authors evaluated the protective effects of hypothermia on axonal and neuronal injury after TBI in rats. Material and Method : The animals were prepared for the delivery of impact-acceleration brain injury as described by Marmarou and colleagues. TBI is achieved by allowing of a weight drop of 450gm, 1 m height to fall onto a metallic disc fixed on the intact skull of the rats. Fourty Sprague-Dawley rats weighing 400 to 450g were subjected to experimental TBI induced by an impact-acceleration device. Twenty rats were subjected to hypothermia after injury, with their rectal temperatures maintained at $32^{\circ}C$ for 1 hour. After this 1-hour period of hypothermia, rewarming to normothermic levels was accomplished over 30-minute period. Following 12 hours, 24 hours, 1 week and 2 weeks later the animals were killed and semiserial sagittal sections of the brain were reacted for visualization of the apoptosis and ${\beta}$-APP. Results : The density of ${\beta}$-APP marked damaged axons within the corticospinal tract at the pontomedullary junction and apoptotic cells at the contused cerebral cortex were calculated for each animal. In comparison with the untreated controls, a significant reduction in ${\beta}$-APP marked damaged axonal density and apoptotic cells were found in all hypothermic animals(p<0.05). Conclusion : This study shows that the posttraumatic hypothermia result in substantial protection in TBI, at least in terms of the injured axons and neurons.

• Korean Journal of Metals and Materials
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• v.56 no.11
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• pp.787-795
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• 2018

The effects of tempering condition on the microstructure and mechanical properties of 30MnB5 hot stamping steel were investigated in this study. Before the tempering, hot-stamped 30MnB5 steel was composed of only ${\alpha}^{\prime}$-martensite microstructure without precipitates. After the tempering at $180^{\circ}C$ for 120 min, nano-sized ${\varepsilon}$-carbides were precipitated in the ${\alpha}^{\prime}$-martensite laths. After tempering at $250^{\circ}C$ for 60 min, cementite was precipitated along the ${\alpha}^{\prime}$-martensite lath boundaries. The cementite was also observed in the specimens tempered at $350^{\circ}C$ for 30 min and $450^{\circ}C$ for 6 min, respectively. The globular ${\alpha}$-ferrite appeared at $350^{\circ}C-30min$ tempering, and the volume fraction of ${\alpha}$-ferrite increased when the tempering temperature was increased. The yield strength increased after tempering, and it reached a peak with the tempering condition of $180^{\circ}C-120min$, due to the nano-sized precipitates in the ${\alpha}^{\prime}$-martensite lath. After the tempering, the steel's ultimate tensile strength (UTS) was decreased due to the reduction in dislocation density and C segregation to lath boundaries. The highest elongation was observed at the $180^{\circ}C-120min$ tempering condition, due to the reduction of residual stress, and the lack of precipitates along the lath boundaries. The $180^{\circ}C-120min$ tempering condition was considered to have outstanding crash performance, according to toughness and anti-intrusion calculation results. In drop tower crash tests, the 30MnB5 door impact beam tempered at $180^{\circ}C$ for 120 min showed better crash performance compared to a 22MnB5 door impact beam.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.245-262
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• 2019

The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

• Composites Research
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• v.21 no.5
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• pp.23-30
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• 2008

Stab threats using sharp edged or pointed Instruments could be easily encountered by police officers or soldiers. In this study, the shear thickening fluids (STF) was impregnated into Kevlar fabrics to improve the stab protection and the resistance of STF impregnated Kevlar fabrics was experimentally investigated. The puncture and cut resistance were tested using a drop test machine withspike and knife indenters fabricated based on the National Institute of Justice (NIJ) standard. The STF was filled with spherical $SiO_2$ particles having an average diameter of 100nm, 300nm, and 500nm. The effect of particle size on puncture and cut resistance of STF impregnated Kevlar fabrics was also investigated. The measured impact load histories showed that STF impregnation into fabric leads to withstand higher peak loads than that of neat fabrics under spike test. The test results showed that Kevlar impregnated with STF exhibit remarkable improvements in puncture resistance while it is slightly influential on the cut resistance. Specifically, particle size is the one of the dominant factors controlling fabric resistance to puncture under spike impact test.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.345-352
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• 2023

Recently, the risk of snow disasters has been increasing South Korea. The damages of heavy snow were categorized into direct and indirect. Direct damage is usually the collapse of buildings as houses, greenhouse or barns. Indirect damage is various, for example, traffic congestion, traffic acident, drop damage, and so on. In South Korea, direct damage is severe in rural area, mosty collapse of greenhouse or barns. However, indirect damage such as traffic accident is mostly occurred in urban area. Therefore, the regional characteristics should be considered when vulnerability is evaluated. Therefore, in this study, the PSR and DPSIR method were applied by regional scale in South Korea. The PSR evaluation method is divided into pressure, state, and reaction index. however, the DPSIR evaluation method is divided into Driving force, Pressure, State, Impact, and Response index. the DPSIR evaluation method is divided into Driving force, Pressure, State, Impact, and Response index. Data corresponding to each indicator were collected, and the weight was calculated using the entropy method to calculate the snowfall vulnerability index by regional scale in South Korea. Calculated heavy snow damage vulnerabilities from the two methods were compared. The calculated vulnerabilities were validated using the recent snow damage in South Korea from 2018 to 2022. Snow vulnerability index calculated using the DPSIR method showed more reliable results. The results of this study could be utilized as an information to prepare the mitigation of heavy snow damage and to establish an efficient snow removal response system.

• Journal of the Korean earth science society
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• v.42 no.5
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• pp.479-495
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• 2021

This study investigates the synoptic (patterns of southern highs, northern lows, and lows rapidly developed by tropopause folding), thermodynamic, and kinematic characteristics of a strong wind that occurred in the Yeongdong region of South Korea on March 18-20, 2020. To do so, we analyzed data from an automatic weather station (AWS), weather charts, the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis, rawinsonde, and windprofiler radars. The daily maximum instantaneous wind speed, exceeding 20 m s^-1, was observed at five weather stations during the analysis period. The strongest instantaneous wind speed (27.7 m s^-1) appeared in the Daegwallyeong area. According to the analysis of weather charts, along with the arrangement of the north-south low-pressure line, the isobars were moved to the Yeongdong area. It showed a sine wave shape, and a strong wind developed owing to the strong pressure gradient. On March 19, in the northern part of the Korean Peninsula, with a drop in atmospheric pressure of 19 hPa or more within one day, a continuous strong wind was developed by the synoptic structure of the developing polar low. In the adiabatic chart observed in Bukgangneung, the altitude of the inversion layer was located at an altitude of approximately 1-3 km above the mountaintop, along with the maximum wind speed. We confirmed that this is consistent with the results of the vertical wind field analysis of the rawinsonde and windprofiler data. In particular, based on the thermodynamic and kinematic vertical analyses, we suggest that strong winds due to the vertical gradient of potential temperature in the lower layer and the development of potential vorticity due to tropopause folding play a significant role in the occurrence of strong winds in the Yeongdong region.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.3
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• pp.502-516
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• 2014

This study has decomposed the Gini coefficient using Korean Labor & Income Panel Study data and empirically analyzed the impact of demographic characteristics and source-specific income of householder on the household income gap using panel analysis. The scope of areas were divided into 'nationwide,' 'metropolitan areas,' and 'non-metropolitan areas,' and the period before and after the global financial crisis was examined. The analysis findings are as follows. First, when the entire period was examined by income source using Gini decomposition with division of areas into 'nationwide,' 'metropolitan areas,' and 'non-metropolitan areas', the following results were revealed. The absolute and relative contribution level of property income to the gross income was the largest in the category of 'nationwide' and 'metropolitan areas,' while the contribution level of earned income was the largest in the category of 'non-metropolitan areas'. In addition, property income worsened the household income gap the most in the category of 'nationwide' and 'metropolitan areas.' Second, property income worsened the household income gap less after the financial crisis than before the crisis. It is probably because the price of real estate skyrocketed before the global financial crisis, worsening the household income gap, whereas the price drop after the crisis temporarily alleviated the gap. Third, a correlation analysis revealed that households with older householders whose education is high school graduation or below had relatively low gross income, and households with higher source-specific income, especially earned income, had relatively high gross income. Fourth, when the household income determinants were compared through panel analysis with division of areas into 'nationwide,' 'metropolitan areas,' and 'non-metropolitan areas,' the following results were obtained. While the impact of earned income, financial income, and other incomes was greater in non-metropolitan areas than in metropolitan areas, the impact of property income was greater in metropolitan areas than in non-metropolitan areas. To reduce the income gap, the government should impose higher taxes on the high-income class and provide tax benefits to the low-income class, with efforts to create a wide variety of jobs. In addition, since income inequality gets worse as the proportion of incomes generated through asset holdings becomes higher, the government should focus on stabilizing property prices while paying attention to the regional differentiation when carrying out related policies.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.50-56
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• 2010

Oil contamination soil has been one of the most environmental social issues for decades in the inside and outside of country. The law of soil environmental preservation was carried out in the 1990s and the government controlled not only soil environment management and the remediation of contaminated soil but also promoted the development of remedial technology and cleanup business of contaminated soil by national policy. In addition to agriculture areas, the main oil contaminated sites are a gas station, oil reservoir, petro-chemical complex, site of railway carriage base and military camp. The contamination-frequency of agriculture area and effect sites are low but it has significantly important area on account of producing food for human beings. Therefore, we should be concerned about oil contamination damage of agriculture area. The oil contamination damage of agriculture area influenced drop of birth and breeding since the oil directly adheres to seeds and farm products even diffusion of contaminated soil to cultivation area. The studies of the crops and the food vegetation has not enough detailed data caused by the incident of oil contamination. This study investigated the effect of oil in germination and growth of selected plant seeds. In this study, we try to verify whether the oil contamination by accidents on farmland influenced the damage of farm produce and the mutual relation both oil contaminated soil or the vegetation of crops. The impact of oil on plant development was followed by phytotoxicity assessments. The plants exhibited visual symptoms of stress, growth reduction and perturbations in developmental parameters. The increase of the degree of pollution induced more marked effects in plants, likely because of the physical effects of oil. The relationships between the phytotoxicity contents of plants and growth reduction suggest a chemical toxicity of fuel oil. In addition, while cleaned up the contaminated soil under the standard of contaminated soil we examined it was suitable for region standard and it may have practical possibility for fill material of construction of afforestation and molding soil of landfill.

• Journal of the Korean Society of School Health
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• v.12 no.1
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• pp.97-107
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• 1999

The purpose of the study was to ascertain the trends of future circumstances in primary education along with population change. These trends, which are subject to change in population and structure, have a great impact on the size and characteristics of primary school-aged children. Accordingly, it is imperative for the government to plan for future conditions involving primary education. The major findings of the study were as follows: 1. In the long-term primary school children aged 6-11, which accounted for 17.7% of the total population in 1970, will decline to 8.6% by the year 2000, 6.9% in 2020 and 6.4% in 2030. This drastic reduction in fertility rate is a direct result of pressure by the government to control population. 2. In 1996, the total number of classes in primary schools rose to 106,594. In the future, these numbers will actually decline. By 2003 the total number of classes will peak at 142,605, but until then drop off to 112,288 by 2030-a decrease of over 6,000. 3. The actual number of primary schools in 1997 totaled 5,721. This figure will reach its highest peak, 5,942, in 2003, but it is expected decrease later after declining by 1,263, it will bottom out at 4,679 in 2003. 4. The number of teachers at primary schools increased from 101,095 in 1970, 119, 064 in 1980, 136,800 in 1990 to 138,369 in 1995. Accordingly this means that the ratio of students to teaching staff changed for the better. By the year 2005, if teachers of specialty subjects (music, art, English, physical education) are assigned to every primary school with over 18 classrooms and the number of students per class is 30, it should improve educational surroundings. This is because it is expected that the population of primary school children will continue to grow until 2003 and then decrease. Thus, there is a need to maintain the number of primary school teachers between the years 2003 and 2030 so that the ratio of students to teachers will be reduced to 1/20.25. In considering factors related to migration which influence conditions of education, it is evident that changes have already begun. In the suburbs of Seoul, population shifts are causing overcrowding in classrooms. The government believes it would be inefficient to invest in education because fluctuating migration figures make it impossible. Accordingly, we have to be concerned about stabilizing the population throughout the entire country.

• Science of Emotion and Sensibility
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• v.21 no.3
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• pp.151-164
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• 2018

The appropriate interpretation of social cues is a crucial ability for everyday life. While processing socially relevant information, beyond the low-level physical features of the stimuli to emotional information is known to influence human cognition in various stages, from early perception to later high-level cognition, such as working memory (WM). However, it remains unclear how the influence of each type of emotional information on cognitive processes changes in response to what has occurred in the processing stage. Past studies have largely adopted face stimuli to address this type of research question, but we used a unique class of socially relevant motion stimuli, called biological motion (BM), which depicts various human actions and emotions with moving dots to exhibit the effects of anger, happiness, and neutral emotion on task performance in perceptual and working memory. In this study, participants determined whether two BM stimuli, sequentially presented with a delay between them (WM task) or one immediately after the other (perceptual task), were identical. The perceptual task showed that discrimination accuracies for emotional stimuli (i.e., angry and happy) were lower than those for neutral stimuli, implying that emotional information has a negative impact on early perceptual processes. Alternatively, the results of the WM task showed that the accuracy drop as the interstimulus interval increased was actually lower in emotional BM conditions than in the neutral condition, which suggests that emotional information benefited maintenance. Moreover, anger and happiness had distinct impacts on the performance of perception and WM. Our findings have significance as we provide evidence for the interaction of type of emotion and information-processing stage.