• Journal of Korea Water Resources Association
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• v.50 no.9
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• pp.597-607
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• 2017

In this study, the applicability of the surface image velocimeter using the far-infrared camera was examined in order to solve the application problem of the measurement in night time, which has been pointed out in previous studies as the limit of the surface image velocimeter. For this purpose, the accuracy evaluation of measurement of the far-infrared camera was conducted for two conditions. Accuracy was evaluated by calculating the relative error of the results of the measurements of surface image velocimeter using the normal video camera during the daytime that was already verified. As a result, the relative error of the surface velocimeter using the far infrared camera was 4.3% at maximum, the average error was about 1%, and the error of the fog condition was maximum 5.2% with an average of 2%. In conclusion, it is possible to measure with high accuracy when using far-infrared camera in a invisible environments where the water flow can not be visualized with a general camera.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.147-156
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• 2010

This study was conducted from April, 2002 to March 2006, using three urban streams(Gap Stream, Yudeung Stream and Daejeon Stream) in Daejeon Metropolitan City. 12,027 individual birds summed by the peak count in 126 species, 34 families, and 13 orders were observed from three stream sites. Dominant species were of Anas poecilorhyncha, Anas crecca, Columba livia, Passer montanus, and Egretta garzetta(in that order). The groups of birds were classified into six types. The most frequent group were the arbor birds(54 species), while the smallest group was the diving ducks(7 species). As for the number of individuals, the shrub bird group had 721 individuals while the dabbling ducks observed had 4,974 individuals. Regarding the distribution of birds appeareing in each stream, 14,885 individual numbers in 114 species were observed at Gap Stream, 6,642 individuals in 90 species at Yudeung Stream and 4,202 individuals in 69 species at Daejeon Stream. Various indices of the birds were analyzed with respects to the similarities between streams. Gap Stream had similar characteristics to Yudeung Stream, and the latter was similar to Daejeon Stream. However, Gap Stream and Daejeon Stream showed different characteristics. The dominance index of each section was calculated using ten dominant bird species top-down. Subsequently, the birds and their preferred environment were analyzed. The results showed that shrub birds and arbor birds preferred the upper stream of every stream, while herons and dabbling ducks inhabited the midstream. Dabbling ducks and some diving ducks appeared downstream.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.3
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• pp.139-146
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• 2017

In order to understand the efficacy of submerged breakwater constructed for the beach protection, laboratory experiments were carried out by observing the characteristics of flow around a single shore-parallel submerged breakwater. The velocity field near the shoreline was measured by utilizing the LSPIV (Large-Scale Particle Image Velocimetry) technique, and mean surface and wave height distributions were observed around the submerged breakwater, according to various combinations of incident waves and submerged breakwaters. In this experiment, it was found that the mean flow pattern behind the submerged breakwater was determined by the balance among the gradients of mean water surface and excess wave-momentum flux (i.e., radiation stress tensors) which interact with the wave-induced current developed by the gradients on the rear and the side of the submerged breakwater. The divergent and convergent flow patterns behind the submerged breakwater (i.e., accretion and erosion response) of the numerical study of Ranasinghe et al.(2010) were observed in the measured velocity distributions, and their empirical formula mostly agreed with the experimental results. However, for some cases in this experiment, it was difficult to say that the flow pattern was one of them and was agreed with the empirical formula.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.315-327
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• 2017

This study was carried out to examine the converging factors related to academic burnout in students from health-related majors who are involved in studying for the Test of English for International Communication (TOEIC). Research subjects included 291 randomly selected students from the J-region, who were enrolled in TOEIC classes. Data collection took place from April 3, 2017 to April 14, 2017, using anonymous self-administered questionnaires. The results of a multiple regression analysis in female students showed higher academic burnout pertaining to studying for the TOEIC when sleeping hours, self-worth, self-efficacy, school adaptation resilience, and study immersion were low, and job-seeking stress and test anxiety were high. The explanatory power of this model was 65%. Based on these results, to reduce academic burnout pertaining to studying for the TOEIC in health majors, it is first necessary to increase sleeping hours, self-worth, self-efficacy, school adaptation resilience, and study immersion, and to make efforts to manage self-competence, job-seeking stress, and test anxiety. The results of this study may be used to decrease the academic burnout caused by studying for the TOEIC in health major students and to increase their aptitude for studying English, to cultivate globalized capabilities. Future studies need to conduct an effect analysis on the control and mediation effect that these factors have on academic burnout.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.605-610
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• 2013

Gamma-aminobutyric acid (GABA) is a non-protein amino acid widely present in organisms, which has shown several important physiological functions such as neurotransmission, hypotension induction, as well as diuretic and tranquilizer effects. They have also been extensively used in food industry. GABA contents in the grain and brown rice are about 1~4 mg/100 g and 4~8 mg/100 g, respectively but it is difficult to expect physiological activity from such low amounts of natural food intake. We investigate the effects of GABA-coated rice on the secretion of melatonin and serotonin which both have been used as sleep inductive compounds. As a result, the secretion of melatonin and serotonin from mice were found to be $3.578{\pm}0.158pg/mL$, $5.918{\pm}0.169ng/mL$ respectively. The melatonin and serotonin in mice increased significantly up to the 8.7 and 22.8 times respectively, when compared to that of the rice, but there was no cumulative effects. Due to the continuous intake of GABA-coated rice, which was developed as a functional food nutrient, inductive effects of melatonin and serotonin from general rice could be achieved and also the similar effect as taking up directly 25 mg/mL of GABA could be obtained.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.4
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• pp.208-218
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• 1992

Analytic solutions for the gradient of surface elevation and vertical profiles of velocity driven by the wind stress in the one-dimensional rectangular basin were obtained under the assumption of steady-state. The approach treats the bottom frictional stress $\tau$$_{b}$ as known and includes vertically varying eddy viscosity $textsc{k}$$_{M}$, which is constant, linear and quadratic of water depth. When the $\tau$$_{b}$ is param-terized with surface stress, depth averaged velocity and bottom velocity, the result shows the relation of the no-slip bottom velocity condition and the bottom frictional stress $\tau$$_{b}$. The results of a mode splitted, (x-$\sigma$) coordinate, numerical model were compared with the derived analytic solutions. The comparison was made for the case such that $textsc{k}$$_{M}$ is the constant, linear and quadratic function of water depth. In the case of constant $textsc{k}$$_{M}$, the gradient of surface elevation and vertical profiles of velocity are discussed for a uniform depth, a mild slope and a relatively steep slope. When $textsc{k}$$_{M}$ is a linear and quadratic function of water depth, the vertical structures of velocities are discussed for various $\tau$$_{b}$. The result of the comparison shows that the vertical structure of velocities depends not only on the value of $textsc{k}$$_{M}$ but also on the profile of $textsc{k}$$_{M}$ and bottom stress $\tau$$_{b}$. Model results were in a good agreement with the analytic solutions considered in this study.his study.y.his study.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.743-752
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• 2014

Delay time for groundwater recharge means the travel time from the bottom of soil layer to groundwater through vadose zone after infiltration from rainfall. As it is difficult to measure delay time, we suggested an empirical formula which is derived by using linear regression between altitude and delay time. For the regression analysis, 4 major gauging watersheds were chosen (Hancheon, Kangjeongcheon, Oedocheon, Cheonmicheon) with 18 measured groundwater level stations. To verify this empirical formula, derived equation from linear reservoir theory was applied to compute delay time and to compare estimated amounts of groundwater recharge using both methods. The result showed good agreement. Furthermore, if derived empirical formula would be linked with SWAT model, the spatial time delay effect in the watershed could be reflected properly.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.357-364
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• 2019

The purpose of this study was to investigate the relationship between Internet addiction and oral health behavior among university students. The results, internet addiction was found in gender and smoking, oral health behaviors were classified according grade and smoking, differences in internet addiction were found in gender and smoking, there were statistically significant differences. And in common, high was first grades, non-health related major, smokers and drinkers, male students living at home. Oral health behaviors were found to be "lying on one side when sleeping" the highest, indicating that frequent use of the Internet occurred before sleep and thus negative oral health behaviors. In addition, there was a statistically significant correlation between college students 'oral health behavior and Internet addiction. Also, university students' internet addiction was found to be an oral health behavior. As a result of the above research, it is necessary to educate and guide appropriate internet use considering the influence on university students academic performance, and to develop oral health education program to recognize the problem of internet use regulation and the oral health behavior of university students themselves.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.370-370
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• 2023

수자원이란 인간의 생활이나 경제활동 및 자연환경 유지 등을 하는데 이용할 수 있는 자원으로서의 물을 말하며 효율적인 수자원의 활용을 위해서는 수문조사가 필수적이라고 할 수 있다. 수문조사는 강수량, 수위, 유량, 유사량, 증발산량, 토양수분량을 측정, 조사, 분석하는 것이라고 할 수 있으며 이 중 유량은 강우-유출 관계 규명, 이수, 치수 등을 위해 높은 정확도의 관측자료가 필요하다. 그러나 하천유량은 장기간 연속적으로 관측하는 것이 어려우므로 특성 횟수의 유량조사를 통해 수위-유량관계곡선식(Rating curve)을 개발하여 수위로부터 연속적인 유량을 산정하여 활용하고 있어 이를 개선하기 위해 전자파표면유속계를 활용한 자동유량측정장치를 개발하였으며 측정자료 분석 및 알고리즘 고도화를 통해 신뢰도 높은 유량을 산정하고자 하였다. 운동하는 물체에 의하여 산란된 전자파의 주파수가 변하게 되는 현상을 도플러 효과라고 하며 이때의 주파수의 변화량을 도플러 주파수라고 한다. 전자파표면유속계는 하천 수면으로 전자파를 발사한 후 물 표면에서 반사되는 전자파의 도플러 효과를 이용하여 표면유속을 측정하는 것으로 전자파표면유속계를 교량 상류 방향으로 고정시켜 설치하였으며 측정된 자료는 유량관측 시스템에서 저장, 관리되고 물리적, 통계적 방법이 적용된 알고리즘을 통해 유량을 산정한다. 산정된 유량의 정확도 확보를 위해 바람 영향, 최적 환산계수 재산정, 통계분석 등을 통해 시스템의 유량산정 알고리즘 개선 방안을 도출하였으며 개선된 알고리즘이 적용된 유량은 NSE(Nash Sutcliffe Efficiency), PBIAS(Percent Bias), RSR(RMSE-observations standard edviation ratio)을 통해 평가하였다. 바람 영향은 유량 관측 고도화 매뉴얼(일본 토목연구소)의 경험식과 현장에서 관측된 풍향·풍속을 활용하여 분석하였으나 개선효과가 미미한 것으로 나타났으며 자동으로 관측된 유량자료에 포함된 무작위적인 변화량을 감소시키기 위해 경향성 분석을 병행하여 이동평균 방법을 적용하였다. 또한 ADCP 등을 활용한 유량측정성과와 수위-유량관계곡선식과의 비교·분석을 통해 수위별 최적 환산계수를 산정하여 유량산정 알고리즘에 적용한 결과 NSE는 0.980, PBIAS는 1.580, RSR은 0.142로 모두 Very Good(높은 상관성)으로 분석되어 유량자료의 정확도를 확보하였다.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.743-751
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• 1997

A thorough literatural review of researches on the experimental prediction of scour depths caused by jets was carried out to find out a measure of scour prediction. A new experimental equation for predicting scour depths due to a vortical or an inclined jet was developed from five hundreds of experimental data which were carefully reviewed and adopted from the previous researches. The developed equation shows 0.941 statistical correlation coefficient. It was found that the parameters governing the scour depth were the size of bed material, flow rate through unit width of spillway, and head drop across structure. The predicted scour depth could be expressed as the deepest scouring depth below tail water surface with correlation coefficient ${\gamma}$ = 0.941.