• Korean Journal of Environmental Agriculture
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• v.31 no.4
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• pp.318-327
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• 2012

BACKGROUND: For Non-Point Source(NPS) loads reduction, pollutant loads need to be quantified for major farming methods. The objective of this study was to evaluate impacts of farming methods on NPS pollutant loads from a paddy rice field during the growing season. METHODS AND RESULTS: The height of drainage outlet, amount of fertilizer, irrigation water quality were considered as farming factors for scenarios development. The control was derived from conventional farming methods and four different scenarios were developed based combination of farming factors. A field scale model, CREAMS-PADDY(Chemicals, Runoff, and Erosion from Agricultural Management Systems for PADDY), was used to calculate pollutant nutrient loads. The data collected from an experimental plot located downstream of the Idong reservoir were used for model calibration and validation. The simulation results agreed well with observed values during the calibration and validation periods. The calibrated model was used to evaluate farming scenarios in terms of NPS loads. Pollutant loads for T-N, T-P were reduced by 5~62%, 8~37% with increasing the height of drainage outlet from 100 mm of 100 mm, respectively. When amount of fertilizer was changed from standard to conventional, T-N, T-P pollutant loads were reduced by 0~22%, 0~24%. Irrigation water quality below water criteria IV of reservoir increased T-N of 9~65%, T-P of 9~47% in comparison with conventional. CONCLUSION(S): The results indicated that applying increased the height of drainage after midsummer drainage, standard fertilization level during non-rainy seasons, irrigation water quality below water criteria IV of reservoir were effective farming methods to reduce NPS pollutant loads from paddy in Korea.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.5
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• pp.125-141
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• 2021

The rapidly changing social structure of the digital environment is having a significant impact on economic activities. That is also an important issue for Individuals who want to sustain economic activities and countries that support policies. Non-face-to-face industries have been revitalized due to the problem of human capital utilization attributed to aging population, the real economic recession caused by Corona 19, contraction of face-to-face economic activities, reduction of employment, and job instability. Accordingly, digital media contents based economic activities have become commonplace, and the government's main policy issue is to use human capital effectively for media contents based economic activities. Adaptation to the digital environment has become a necessity, not a choice, for those who wish to continue to be in employment. Therefore, this study analyzed the effects of digital and individual abilities on intention to sustain the economic activity and verified the modulation effect of the role model. In order to achieve the purpose of this research, an online survey was conducted on men and women aged 20 to 80 nationwide, and 382 of the 385 collected questionaires were analyzed. The SPSS 23.0 program was used to analyze this study, and the questionaire questions were measured using the Likert 5-point scale. As a result of the analysis, first, the ability to utilize media contents in digital capacity has a positive impact on the intention to sustain economic activity, and that the higher the ability to utilize the latest digital media contents such as SNS, the more likely the intention to sustain economic activity. Secondly, it was found that the financial strength of individuals' abilities was affected by the negative impact, and that the experiences were affected by positive(+) impact on the intention to sustain economic activity. Thirdly, the social environment has no significant effect on the intention to sustain economic activity. Fourth, it was found that family support amongst social support has a positive impact on the intention to sustain economic activity, and that various emotional support for families has increased intention to sustain economic activity. Fifth, the role model was found to have a positive(+) impact on economic sustainability, while the ability to utilize media content and family support played a modulating role on economic sustainability. Therefore, as a result of this research, the government's policy support for employment and entrepreneurship is required in accordance with digital media content based digital education and human structure in order to sustain economic activities.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.59-67
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• 2016

In this paper, we perform a numerical analysis to evaluate the potential of fault reactivation during gas production from hydrate bearing sediments and the moment magnitude of induced seismicity. For the numerical analysis, sequential coupling of TOUGH+Hydrate and FLAC3D was used and the change in effective stress and consequent geomechanical deformation including fault reactivation was simulated by assuming that Mohr-Coulomb shear resistance criterion is valid. From the test production simulation of 30 days, we showed that pore pressure reduction as well as effective stress change hardly induces the fault reactivation in the vicinity of a production well. We also investigated the influence of stress state conditions to a fault reactivation, and showed that normal fault stress regime, where vertical stress is relatively greater than horizontal, may have the largest potential for the reactivation. We tested one simulation that earthquake can be induced during gas production and calculated the moment magnitude of the seismicity. Our calculation presented that all the magnitudes from the calculation were negative values, which indicates that induced earthquakes can be grouped into micro-seismic and as small as hardly perceived by human beings. However, it should be noted that the current simulation was carried out using the highly simplified geometric model and assumptions such that the further simulations for a scheduled test production and commercial scale production considering complex geometric conditions may produce different results.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.213-223
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• 2017

Recently, the air quality of South Korea has deteriorated and public interest has been increasing. Various observation means are used for the monitoring of the atmospheric environment, but it relies on the experience and judgment of the observer in the absence of spatial information on the emission facilities. The purpose of this study was to determine the availability of using drones for monitoring air pollutant emission facilities. A texture transformation method was applied to the drone ortho image to detect the small gas emission facility and the slope data calculated by the digital surface model (DSM) was used to reduce the false alarm ratio. As a result, it shows the possibility of using drones in the detection of small gas emission facilities by showing about 80% of positive detection ratio and 40% of false alarm ratio. In the future, various researches are required to the improve positive detection ratio and the reduction of the false alarm ratio. Based on these results, it is necessary to construct a database including 3D spatial information of air pollutant emission facilities.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.79-91
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• 2016

Geosynthetic-reinforced and Pile-supported (GRPS) embankment method is widely used to construct structures on soft ground due to restraining residual settlement and their rapid construction. However, effect of cyclic loading has not been established although some countries suggest design methods through many studies. In this paper, cyclic loading tests were conducted to analyze dynamic load transfer characteristics of pile-supported embankment reinforced with geosynthetics. A series of 3 case full scale model tests which were non-reinforced, one-layer-reinforced, two-layer reinforced with geosynthetics were performed on piled embankments. In these series of tests, the height of embankment and pile spacing were selected according to EBGEO (2010) standard in Germany. As a result of the vertical load parts on the pile and on the geosynthetic reinforcement measured separately, cyclic loads transferred by only arching effect decreased with strength geosynthetic-reinforced case. However, final loads on the pile showed no differences among the cases. These results conflict with previous studies that reinforcement with geosynthetics increases transfer load concentrated on piles. In addition, it is observed that the load transferred to pile decreases at the beginning of cycle number due to reduction of arching effected by cyclic loading. Based on these results, transferred mechanism for cyclic load on GRPS system has been presented.

• Journal of Periodontal and Implant Science
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• v.44 no.5
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• pp.242-250
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• 2014

Purpose: This study aimed to evaluate the effects of fibronectin and oxysterol immobilized on machined-surface dental implants for the enhancement of cell attachment and osteogenic differentiation, on peri-implant bone healing in the early healing phase using an experimental model in dogs. Methods: Five types of dental implants were installed at a healed alveolar ridge in five dogs: a machined-surface implant (MI), apatite-coated MI (AMI), fibronectin-loaded AMI (FAMI), oxysterol-loaded AMI (OAMI), and sand-blasted, large-grit, acid-etched surface implant (SLAI). A randomly selected unilateral ridge was observed for 2 weeks, and the contralateral ridge for a 4-week period. Histologic and histometric analyses were performed for the bone-to-implant contact proportion (BIC) and bone density around the dental implant surface. Results: Different bone healing patterns were observed according to the type of implant surface 2 weeks after installation; newly formed bone continuously lined the entire surfaces in specimens of the FAMI and SLAI groups, whereas bony trabecula from adjacent bone tissue appeared with minimal new bone lining onto the surface in the MI, AMI, and OAMI groups. Histometric results revealed a significant reduction in the BIC in MI, AMI, and OAMI compared to SLAI, but FAMI demonstrated a comparable BIC with SLAI. Although both the BIC and bone density increased from a 2- to 4-week healing period, bone density showed no significant difference among any of the experimental and control groups. Conclusions: A fibronectin-coated implant surface designed for cell adhesion could increase contact osteogenesis in the early bone healing phase, but an oxysterol-coated implant surface designed for osteoinductivity could not modify early bone healing around implants in normal bone physiology.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.215-225
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• 2011

In general, the precast columns can obtain its homogeneous quality as they are produced in a factory with a hollow concrete block type by using high strength concrete, so that they can generate the reduction of dead load. Such a method of precast hollow concrete columns is already implemented in USA and Japan and used for connecting between blocks which use PC tendons. However, it is inevitable to have uneconomical construction with excessive cost in early stage when PC tendons are used. This study aims to develop an economical precast column with high quality and constructability which consists of only splice sleeve and general reinforcing bar without using PC tendons in order to reduce the construction period and cost. To achieve this goal, this study tested the performance of total 5 minimized models in the experiment with the variables such as hollowness, diameter of main reinforcement bar and cross-sectional size for the cross section of precast column by using grouting type splice sleeve which is a new type joint rebar. And it also verified the performance of column in the experiment for a large-sized model in order to overview its applicability by excluding large scale effect.

• Korean Journal of Social Welfare
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• v.37
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• pp.381-405
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• 1999

The primary purpose of this study is to design and perform juvenile group program and. to evaluate the effectiveness of that program The group was consisted of 10 fourth-grade elementary school boys who have had such factors that might force themselves to be delinquent, for example, broken family, having delinquent siblings or friends, family violence, and etc. The group had been held once a week and continued for 5 months. The effectiveness of that program is evaluated quantitatively and qualitatively through goal-attainment model. The ultimate goal of this program is reduction of delinquency stimulating factors which are operationalized with overall self-esteem - family related self-esteem, friend related self-esteem, and school related self-esteem. Quantitative evaluation is performed by pre- and post-test with Hare Self-Esteem Scale. Case records, family records, group activities records, and reports from schools are analyzed for the qualitative evaluation. According to paired samples t-test scores, average overall self-esteem scores of experimental group members were escalated from 67.57 to 74.86, and this difference between pre-test and post-test was statistically significant. Difference of experimental group was bigger and more striking than that of control group. These results suggest that designed and performed group program in this study would be effective in preventing juvenile from being delinquent.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.209-220
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• 2015

In this study, the effects of changed environment on spatial extension of flood discharge data which is generating discharge data at ungauged watersheds. Especially, effects of dams on spatial extensions of flood discharge data and on natural flow generation were studied. This is somehow an intial trial of flood discharge data generation for heterogeneous watersheds because of dam installation. Data extensions have been performed based on the flood discharge data from YeoJoo water gauge station located on the Nam-Han River. For the evaluation of flood discharge data spatial extension under dam effects and producing natural flow, 41 flood events associated with YeoJoo water gauge station were selected from 1986 to 2010. When flood discharge data were extended based on YeoJoo water gauge station, 77% of selected flood events were over the satisfaction ranges (NSE>0.5) of Nash-Sutcliffe Efficiency for model validation. Extended flood discharge data at Yangpyung has 0.84 NSE obtained from spatial data extension based on YeoJoo water gauge station. Generated natural flow at YeoJoo was influenced strongly by Chungju Dam which has larger effects on streamflow at YeoJoo than Hoangsung Dam. Observed peak discharges after the 1986 of Chungju Dam installation were smaller than those of the obtained natural flow. Through these results, spatial extension of flood discharge data with installed dams works efficiently for ungauged watersheds and natural flow can be generated using extended flood discharge data.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.471-480
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• 2006

The field scale experiment was performed to examine the performance of the constructed wetland for nonpoint source (NPS) pollution loading reduction. Four sets (each set of 0.88 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland systems. Water depth was maintained at 0.3-0.5 m and hydraulic retention time was managed to about 2-5 days; emergent plants were allowed to grow in the wetland. The wetland effluent concentrations of $BOD_5$, TSS, and T-N were higher in winter than in the growing season excepting the T-P, and effluent $BOD_5$ concentration was higher than influents in winter. Mass retention of T-N and T-P was stable throughout the year, whereas mass retention of $BOD_5$ and TSS was decreased in winter. $BOD_5$, TSS, T-N, and T-P performance of the experi-mental system was compared with the existing database (North American Treatment Wetland Database), and was within the range of general system performance. From the first-order analysis, T-P was virtually not temperature dependent, and $BOD_5$ and TSS were more temperature dependent than T-N. Overall, the wetland system was found to be an adequate alternative for treating polluted stream water with stable removal efficiency and recommended as a NPS control measures.