• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.211-220
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• 2020

When domestic sewage and rainwater runoff are discharged into a single sewer pipe, it is called a "combined sewer system." The sewage design standards in Korea specify the flow velocity based only on the volume of rainfall; therefore, sedimentation occurs on non-rainy days owing to the reduced flow rate and velocity. This sedimentation reduces the discharge capacity, causes unpleasant odors, and exacerbates the problem of combined sewer overflow concentration. To address this problem, the amount of sewage on non-rainy days, not just the volume of rainfall, should also be considered. There are various theories on sedimentation in sewer movement. This study introduces a self-cleansing velocity based on tractive force theory. By applying a self-cleansing velocity equivalent to the critical shear stress of a sand particle, sedimentation can be reduced on non-rainy days. The amount of sewage changes according to the water use pattern of citizens. The design hourly maximum wastewater flow was considered as a representative value, and the velocity of this flow should be more than the self-cleansing velocity. This design method requires a steeper gradient than existing design criteria. Therefore, the existing sewer pipelines need to be improved and repaired accordingly. In this study, five types of improvement and repair methods that can maximize the use of existing pipelines and minimize the depth of excavation are proposed. The key technologies utilized are trenchless sewer rehabilitation and complex cross-section pipes. Trenchless sewer rehabilitation is a popular sewage repair method. However, it is complex because the cross-section pipes do not have a universal design and require continuous research and development. In an old metropolis with a combined sewer system, it is difficult to carry out excavation work; hence, the methods presented in this study may be useful in the future.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.555-570
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• 2007

The effects of climatic changes owing to urbanization on annual water balance have been studied. In this study, 56 meteorological stations including Seoul metropolis in South Korea have been selected, and the area of study site is $314\;km^2$. The meteorological station is centrally located in the study area with a 10 km radius. Land use status of study area was examined to estimate the urbanization extent, so that annual actual evapotranspiration could be estimated. Annual runoff was estimated by annual water balance approach using the estimated annual actual evapotranspiration and measured annual precipitation. Annual actual evapotranspiration was estimated by applying experimental equation suggested by Zhang et al, (2001) which was evaluated from 250 watersheds all over the world. Study results show that reference evapotranspiration is tending upwards due to urbanization; therefore, it seems that climatic change due to urbanization may increase the amount of annual actual evapotranspiration. However, the increase of residential area due to urbanization in study area may decrease the amount of annual actual evapotranspiration. The study results indicate that urbanization effect on annual trend of precipitation was not significant. In urban area, annual runoff is directly affected by annual precipitation, and compared with annual precipitation, annual variation of actual evapotranspiration was not significant even though it was estimated by using annual precipitation. It seems that the effect of urbanization on annual actual evapotranspiration does not influence on annual runoff significantly, and that urbanization effect on annual runoff Is not significant.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.571-583
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• 2007

The effects of climatic changes owing to urbanization, geographical and topographical conditions on Penman-Monteith reference evapotranspiration, and energy and aerodynamic terms of Penman-Monteith reference evapotranspiration have been studied. In this study, 56 climatological stations including the Seoul metropolis in South Korea have been selected, and the area of study site was set at $314\;km^2$. The climatological station is centrally located In the study area with a 10 km radius. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicated that the variation of reference evapotranspiration rate is closely related to urbanization in most climatological stations. The level of change in reference evapotranspiration was higher in areas with higher urbanization rates. The change in reference evapotranspiration appears to be caused by temperature rises following heat island phenomena due to urbanization, and by the decrease in humidity, wind speed and sunshine duration due to the Increase in residential areas in urban districts. Especially, the humidity decrease causes a significant decrease in evapotranspiration rate. The study results showed that climatic change due to urbanization and proximity to the coast had the greatest effect on reference evapotranspiration.

• Journal of the Society of Disaster Information
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• v.7 no.4
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• pp.273-285
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• 2011

This research present actual conditions on realization about safety of observable individual and country, terror countermeasure from danger of terrorism which special guards have. To achieve these purposes, 400 special guards were sampled using the convenience sampling method and collected data through questionnaire from self-administration method. the collected data are in statistics of p<.05 levels. As the result, we drew following conclusions. Special guards thought that terror might occur most in 'aircraft, rapid-transit railway, subway, and bus'. It was no difference in society demography(p>.05). In type of terror, 'bomb terror' seemed to happen most, and they recognized that biochemistry terror and factor terror, and hostage terror may happen in society demography. Purpose of terror was thought that 'political purpose' may be the biggest, and 'ideological purpose' and 'social purpose' joined the remainder. According to society demography, woman's realization about terror was higher than man in two low variables. According to age, image of terror was high in 40 more than 20. According to educational background, university graduate were higher than a high-school diploma in two low variables. According to place of work, metropolis was higher than small and medium-sized city.

• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.137-147
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• 2003

The objective of this experiment was to investigate the possibility on agricultural use of muncipal sewage sludge with respect to heavy metal contents in Korea. Metal contents (mg/kg) in 88 sludge samples were ranged from 0 to 54.3 for As, 1,7 to 197.3 for Cd, 7.3 to 2,854 for Cr, 87.4 to 5,730 for Cu, 129.3 to 10,289 for Mn 20.1 to 2,057 for Ni, 7.6 to 197.5 for Pb, and 523.5 to 6,349 for Zn. Heavy metal contents of sludges were compared with the regulation on raw material for compost. All sludges produced from sewage treatment plane in metropolis (over a million in population) and large cities ($500,00{\sim}1,000,000$) were not compatible with the regulation. In addition, 95% of sludge from small and mid-size cities ($100,00{\sim}500,000$) and 93% from rural area (below 100,000) were not suitable. On the basis of Cd, Cu, Ni and Zn contents, 41, 53, 47, and 89% of sludge samples were not compatible with the regulation on raw material for compost respectively.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.511-516
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• 2007

Active method MASW(Multi channel Analysis of Surface Waves), which is one of the surface wave exploration methods, has the difficulties to supply enough shear wave velocity log, caused by short spread length and lack of low frequency energy. To make up this defect, the passive method MASW survey is taked and analysised in Daeku subway construction site, Jungpyung-dong Gyeongsan city. The passive method MASW using the microtremor, improve the quality of the overtone record by applying the azimuth correction caused offline sources. And combing with active overtone record which is acquired by same geometry has the benefits of improve shallow depth resolution and extend possible investigation depth. To take the optimized acquisition parameters, the 2m, 4m, and 6m geophone spacing is tested. And 2m spacing overtone image could make the reliable shear wave velocity log.

• Journal of the Economic Geographical Society of Korea
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• v.20 no.4
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• pp.453-485
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• 2017

One of the oldest chestnuts in economic geography is this: Cultural and creative industries strongly gather in large cities and this geographic concentration of economic activities leads to regional development. Of course, depending on the circumstances, such a proposition still holds good. But, under the current paradigm shift to knowledge-based economy, it may be open to question. This study aims to investigate financing and knowledge accumulation in the film industry through an alternative framework for explaining their spatial distributions, "formation mechanism of economic space." From the fact that their production organizations are formed on a project basis, project-based financing structure in the investment stage and knowledge accumulation process in the production stage form both axes of it. Film industry as the most mature industry among the cultural and creative industries does not always concentrate in a certain place (industrial agglomeration) or show metropolis-oriented preference. This allows us to reconsider our long brooding theory.

• The Korean Journal of Applied Statistics
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• v.33 no.1
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• pp.47-59
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• 2020

In this paper, we present the longitudinal Markov binary regression model with t-link function when its transition order is known or unknown. It is assumed that logit or probit models are considered in binary regression models. Here, t-link function can be used for more flexibility instead of the probit model since the t distribution approaches to normal distribution as the degree of freedom goes to infinity. A Markov regression model is considered because of the longitudinal data of each individual data set. We propose Bayesian method to determine the transition order of Markov regression model. In particular, we use the deviance information criterion (DIC) (Spiegelhalter et al., 2002) of possible models in order to determine the transition order of the Markov binary regression model if the transition order is known; however, we compute and compare their posterior probabilities if unknown. In order to overcome the complicated Bayesian computation, our proposed model is reconstructed by the ideas of Albert and Chib (1993), Kuo and Mallick (1998), and Erkanli et al. (2001). Our proposed method is applied to the simulated data and real data examined by Sommer et al. (1984). Markov chain Monte Carlo methods to determine the optimal model are used assuming that the transition order of the Markov regression model are known or unknown. Gelman and Rubin's method (1992) is also employed to check the convergence of the Metropolis Hastings algorithm.

• Journal of the Korean association of regional geographers
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• v.14 no.4
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• pp.279-289
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• 2008

The purpose of this paper is to search for geomorphological landscape resources of Goryeong-gun, to provide fundamental data for their management through mapping their distribution, and to present their conservation and application plan. The results are as follow: Firstly, geomorphological landscape resources in mountain area are Misungsan and Jusan mountain of Goryeong-up, Sangbiri valley of Deoggok-myeon, and isolated hill of Gaejin-myeon. Secondly, geomorphological landscape resources in riparian area are natural wetlands such as Jinchonneup of Bu-ri Gaejin-myeon, Hochonneup and Dalseongseupji of Hochon-ri Dasan-myeon, Bongsanneup of Bongsan-ri Ugok- myeon; artificial wetlands following the construction of weir such as riparian wetland of Oe-ri Goryeong-up and Banun-ri Gaejin-myeon; meander core and abandoned channel of Banun-ri Gaejin -myeon, river cliffs such as Naegok-ri Goryeong-up and Weolo-ri Ugok-myeon; sand bars and braided channel of Yajeong-ri Ugok-myeon. Thirdly, Jinchonneup swamp area of Bu-ri Gaejin-myeon have characteristics of typical floodplain landform, and its conservation conditions is relatively satisfactory, and its accessibility to metropolis is great, so it is a good place to construct eco-park. And construction of inquiry learning place at Banun-ri Gaejin-myeon will increase the opportunity to observe environmental changes following incised meander cutoff and ecological affirmative functions of a weir.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.249-261
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• 2012

Purpose: This study was carried out in order to examine the relationship of job satisfaction and quality of life on the dental technicians and to analyze its influence. Methods: A self-reported questionnaire survey was carried out by having convenience sampling as 220 dental technicians who work in Seoul Metropolis, Gyeonggi-do Province, Daejeon and Chungnam Province from March 12, 2012 to April 13. A research tool was used questionnaire that was proved reliability and validity. It was prepared with totally 50 questions such as 12 items for subjects' general characteristics, 18 items for job satisfaction measurement, and 20 items for life quality measurement. An analysis of the collected data was computationally processed by using SPSS Win 17.0 program. An analytical technique was made by using statistical techniques such as frequency & percentage, T-test or One-way ANOVA analysis. The following are the analytical results of the collected materials. Results: As a result of analyzing research subjects' job satisfaction level, there was significant difference(P<0.05) in items of religion, hobby life, working environment, and rest time out of daily work. The whole mean in job satisfaction was indicated to be relatively high with 3.13. However, job satisfaction with social recognition, salary, and safety was indicated lowly. As a result of analyzing research subjects' life quality level, there was significant difference(P<0.05) in items of religion, hobby life, working environment, and rest time out of daily work. The whole mean in quality of life was indicated to be relatively high with 3.10. However, the satisfaction was indicated lowly in the whole life quality and the life environment sphere. As a result of analyzing correlation between job satisfaction and life quality, all variables were indicated to be positive correlation in high significance level, thereby having been indicated that the higher job satisfaction leads to the higher life quality. Conclusion: As a result of research, the dental technicians' job satisfaction was indicated to have high correlation with quality of life. An effort is judged to be necessary for establishing fair compensation system, improving welfare policy and enhancing social recognition and position in order to promote dental technicians' quality of life.