• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.263-271
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• 2016

This study investigated the hydraulic impact scope and dissolved oxygen (DO) concentration distribution by the micro-bubble aeration in the Juksan Lake located in Asan city in Chungcheongnam-do province. A tracing experiment for hydraulic impact scope was used which constituted a 20% rhodamine solution. A 160 m-guideline was installed in the horizontal direction of the micro-bubble jet flow and the rhodamine concentration, water temperature, and DO concentration were measured at depths of 1 m, 2 m, and 3 m at intervals of 10 m. In the Juksan Lake, the effective range of jet flow discharged by the micro-bubble generator was about 40 m, and after then the jet plume moved up to 80 m to 120 m through the advection and diffusion processes of ambient water. DO concentration in the lake was maintained at 7.4-12.6 mg/L during tracking experiment. The DO of the lake sediments improved from 0.2 mg/L to 8.0 mg/L after applying micro-bubble aeration. In conclusion, the micro-bubble aeration can be an effective technology for the management and improvement of water quality in an agricultural reservoir.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.173-181
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• 1992

Tantalum pentoxide($Ta_{2}O_{5}$) thin films on p-type (100) silicon wafer were fabricated by RF reactive sputtering. Physical properties and structure of the specimens were examined by XRD and AES. From the C-V analysis, the dielectric constant of $Ta_{2}O_{5}$ films was in the range of 10-12 in the reactive gas atmosphere in which 10% of oxygen gas is mixed. The ratio of Ta : 0 was 1 : 2 and 1 : 2.49 by AES and RBS examination, respectively. The heat-treatment at $700^{\circ}C$ in $O_{2}$ ambient led to induce crystallization. When the heat-treatment temperature was $1000^{\circ}C$, the dielectric constant was 20.5 in $O_{2}$ ambient and 23 in $N_{2}$ ambient, respectively. The crystal structure of $Ta_{2}O_{5}$ film was pseudo hexagonal of ${\delta}-Ta_{2}O_{5}$. The flat band voltage shift(${\Delta}V_{FB}$) of the specimens and the leakage current density were decreased for higher oxygen mixing ratio. The maximum breakdown field was 2.4MV/cm at the oxygen mixing ratio of 10%. The $Ta_{2}O_{5}$ films will be applicable to hydrogen ion sensitive film and gate oxide material for memory device.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.5
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• pp.32-40
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• 2006

This study's objects are to suggest effective forest community-level management measures by identifying the vulnerable forest vegetation communities types to climate change through a comparative analysis with present forest communities identified and delineated in the Actual Vegetation Map. The methods of this study are to classify the climatic life zones based on the correlative climate-vegetation relationship for each forest vegetation community, the Holdridge Bio-Climate Model was employed. This study confirms relationship between forest vegetation and environmental factors using Pearson's correlation coefficient analysis. Then, the future distribution of forest vegetation are predicted derived factors and present distribution of vegetation by utilizing the multinomial logit model. The vulnerability of forest to climate change was evaluated by identifying the forest community shifts slower than the average velocity of forest moving (VFM) for woody plants, which is assumed to be 0.25 kilometers per year. The major findings in this study are as follows : First, the result of correlative analysis shows that summer precipitation, mean temperature of the coldest month, elevation, soil organic matter contents, and soil acidity (pH) are highly influencing factors to the distribution of forest vegetation. Secondly, the result of the vulnerability assessment employing the assumed velocity of forest moving for woody plants (0.25kmjyear) shows that 54.82% of the forest turned out to be vulnerable to climate change. The sub-alpine vegetations in regions around Mount Jiri and Mount Seorak are predicted to shift the dominance toward Quercus mongolica and Pinus densiflora communities. In the identified vulnerable areas centering the southern and eastern coastal regions, about 8.27% of the Pinus densiflora communities is likely to shift to sub-tropical forest communities, and 3.38% of the Quercus mongolica communities is likely to shift toward Quercus acutissima communities. In the vulnerable areas scattered throughout the country, about 8.84% of the Quercus mongolica communities is likely to shift toward Pinus densiflora communities due to the effects of climate change. The study findings concluded that challenges associated with predicting the future climate using RCM and the assessment of the future vulnerabilities of forest vegetations to climate change are significant.

• Science of Emotion and Sensibility
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• v.18 no.2
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• pp.45-54
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• 2015

This study carried out an experiment to identify subject's work effectiveness and energy saving effect using LED light. Towards this end, this study configured nine various lighting environments in order to control PWM (Pulse Width Modulation) and illuminance (lux), which are the characteristics of LED light. The PWM ratio of LED light was set as R:G:B=1:1:1, R:G:B=4:1:5, and R:G:B=8:7:7, respectively, and illuminance (lux) was set as 400 lx, 700 lx, and 1000 lx, respectively. In addition, the indoor environment was set temperature $20-24^{\circ}C$, humidity 50%-60%, and the amount of clothing 1. This study analyzed work effectiveness and energy consumption in nine lighting environments, each. Error correction was performed for work effectiveness analysis, and cumulative power consumption was measured in each lighting environment for energy consumption analysis. According to experiment results through the lighting environments suggested in this study, accuracy and spent time effectiveness were good in 700lux and higher than 400lux. For spent time, the best effectiveness was revealed in the suggested PWM ratio, R:G:B=8:7:7. The lowest power consumption on each illuminance (lux) was revealed in the order of R:G:B=8:7:7, RGB=1:1:1, and R:G:B=4:1:5. Therefore, pulse-width modulation effect is proposed in this paper was found to affect the efficiency and energy saving.

• Science of Emotion and Sensibility
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• v.17 no.2
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• pp.55-62
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• 2014

In this study, a questionnaire was developed to assess error search and correction tasks, and an analysis was performed on the accuracy of the tasks and the time required for their completion in order to identify the effects of LED light source illumination on visual performance according to changes in a predicted mean vote(PMV) thermal environment. In addition, a subjective evaluation was performed by conducting a survey on the level of visual fatigue experienced during the tasks. In the experiment, four types of PMV thermal environments were established according to PMV values in the temperature range of $(17{\pm}1-29{\pm}1)^{\circ}C$ and the humidity range of $(50{\pm}5-60{\pm}5)%$, and the LED light source illumination was divided into three types: 400lx, 700lx, and 1000lx. The experimental results confirmed that the accuracy of the error search(LED p value=0.058, PMV*LED p value=0.083) and correction tasks and the time required(LED p value=0.004, PMV p value=0.000) for their completion were affected by changes in both the PMV thermal environment and the LED light source illumination, whereas a significant difference in visual fatigue was observed only in the PMV thermal environment(p value=0.003).

• Korean Journal of Remote Sensing
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• v.33 no.5_3
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• pp.879-888
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• 2017

This study is a preliminary research conducted in Buhansan mountain National Park to develop a management system to predict and control oak wilt disease by indicating spatial factors which affect diffusion of the disease. After analysing altitude factor during the estimation of spatial analysis of damaged area, it is indicated that damaged trees are mainly distributed at altitude of 200-500 m and number decreased drastically over the altitude of 500 m. The result showed that 92% of total damaged trees are on slope between 20~40 degrees and the number decreased drastically on slope steeper than 40 degrees. It is indicated that damaged area is mainly distributed on southern aspect. It is estimated by using CART that slope factor affected the diffusion of disease mostly but aspect factor did not. Surface temperature and altitude showed similar effect.By simulating possible diffusion scenario, it is estimated that the disease could spread to DO-BONG Mt., northeast of Bukhansan mountain.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.773-781
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• 2008

As buildings are becoming taller and longer-spanned, the requirements of high-strength and reliable steels are becoming increasingly stringent. Structural steels, however, acquire significantly different mechanical properties when their strength becomes higher. In this study, the mechanical properties, welding characteristics, and conformities of the 600MPa-grade high-strength steel were tested. The 600MPa-grade steel plates exhibited stable criterion strengthvalues and showed low carbon equivalents (${\mathcal{Ceq}}$) and composition (${\mathcal{Pcm}}$) as well as excellent welding hardness. In the tensile strength test, all the specimens were found to have strengths of over 600MPa. In the Sharphy impact test, the impact-absorbed energy of the V-notch specimens was shown to be 47J at the KS limit. Moreover, the maximum hardness of the specimens in the weld-heat-affected zone at a normal temperature was the same as that before welding. Their weld metal properties, however, were found not to be as good as those of high-strength steel. As such, the details of high-strength steel must be determined.

• Journal of Veterinary Clinics
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• v.11 no.2
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• pp.545-552
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• 1994

This experiment was carried out to investigate the renditions to maintain good post-thaw motility and viability of canine spermatozoa when the semen was frozen using methanol. The semen from two male dogs which had been proven to be fertile in the previous one year was treated with different compositions of semen diluent and was frozen at different freezing temperatures, When canine semen was frozen at-2$0^{\circ}C$, -6$0^{\circ}C$, or -8$0^{\circ}C$, the spermatozoa frozen and stored at -2$0^{\circ}C$ showed very low post-thaw motility and viability from day 2 to 7 and showed no viability since day 15 after freezing. The spermatozoa frozen and stored at -6$0^{\circ}C$ or -8$0^{\circ}C$ showed higher post-thaw motility and viability on day 2, 1, 15 and 30 after freezing than that frozen and stored at-2$0^{\circ}C$(p<0.01), with no difference between two groups. Among different composition groups of the semen diluents of control(tris + egg yolk + glycerol), egg yolk-free, 히ycerol-free, and tris-free, Prior to freezing, the egg yolk-free diluent showed significantly love. motility and viability than the other diluents(p<0.05). On each thawing day (from day 2 to 15 after freezing), control group showed considerably higher motility and viability than the other groups(p<0.01). The canine spermatozoa frozen and stored at -6$0^{\circ}C$ and -8$0^{\circ}C$ showed gradual decrease of motility from day 2 to 30 after freezing and the spermatozoa of these two groups thawed on day 30 showed considerably love. motility than those thawed on day 2 after freezing, respectively(p<0.01). These results indicate that the freezing temperature of either -6$0^{\circ}C$ or -8$0^{\circ}C$ can be applicable to the freezing method using methanol and also all of the components of the semen diluent including cryoprotectant, buffer and cold-shock buffer are very important to maintain motility and viability of canine spermatozoa in the freezing and thawing procedure.

• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.211-218
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• 2011

The aims of this study were to investigate the anesthetic effects of medetomidine-midazolam-ketamine (MMK) combination and to compare antagonistic effects of atipamezole and yohimbine in dogs anesthetized with MMK. Eighteen adult male healthy beagles were used in this study. All dogs were anesthetized with intramuscular (IM) administration of medetomidine (0.04 mg/kg), midazolam (0.2 mg/kg) and ketamine (5 mg/kg) in one syringe. Intravenous (IV) administration of atipamezole (0.24 mg/kg, MMKA), yohimbine (0.2 mg/kg, MMKY) or saline solution (0.1 ml/kg, MMK) was administered 20 minutes after MMK combination anesthesia. Induction and recovery times, scores of sedation and analgesia, heart rate, blood pressure, rectal temperature, respiratory rate and blood gases were determined and recorded for each dog. Mean anesthesia times, sternal recumbency times, standing times and walking times in the MMKA and MMKY groups were significantly shorter than those in the MMK group. But there were not significantly different between MMKA and MMKY groups. In all groups, MMK administration produced a satisfactory sedation and analgesia for all dogs. However, after administration of atipamezole or yohimbine the scores for posture and response to noxious stimuli were significantly lower in the MMKA or MMKY group than those in the MMK group. MMK produced good sedation and anesthesia effects, and atipamezole or yohimbine can be used as a safe and effective agent for antagonizing the MMK anesthesia in dogs.

• Korean Journal of Organic Agriculture
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• v.28 no.2
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• pp.209-221
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• 2020

Highbush blueberries (Vaccinium corymbosum), 'Duke', 'Bluecrop', and 'Elliott', were applied with ground cover mulch systems to evaluate bush growth and fruit characteristics. Soil temperature variation was lower in the woodchip mulching plot. Therefore, CEC, soil pH, phosphate, mineral ions were not significantly different among mulching materials. The number of main stem was higher in woodchip > sawdust > rice husk > plastic film mulching plot, respectively. Total shoot number was also higher in organic mulching plots than in plastic film plot. However, total shoot number was not significantly different among the organic mulching plots. Fruit weight was the highest in the woodchip mulching plot of all blueberry cultivars, however, soluble sugar content, organic acidity, fruit firmness were not significantly different in mulching materials. Yield was higher in organic mulching plots than in plastic film plot in all blueberry cultivars. Especially, yield per shrub of woodchip plots was the highest about 3.6 kg in 'Duke', 2.7 kg in 'Bluecrop', and 2.6 kg in 'Elliott'. Furthermore, correlation of main stem number and yield was highly significant (r² = 0.8413). Therefore, woodchip mulching is expected to be an eco-friendly method to increase the number of stems and the yield of blueberries.