• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.65-73
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• 1999

Dioxins refer to a family of chemicals comprising 75 polychlorinated dibenzo-p-dioxin (PCDD) and 135 polychlorinated dibenzo-p-furan (PCDF) congeners, which may cause skin disorder, human immune system disruption, birth defects, severe hormonal imbalance, and cancer. The effects of exposure of dioxin-like compounds such as PCBs are mediated by binding to the aryl hydrocarbon receptor (AHR), which is a ligand-activated transcription factor. To grasp physicochemical factors affecting human toxicity of dioxins, six geometrical and topological indices, eleven thermodynamic variables, and quantum mechanical descriptors including ESP (electrostatic potential) were analyzed using QSAR and semi-empirical AM1 method. Planar dioxins with high lipophilicity and large surface tension show the probability that negative electrostatic potential in the lateral oxygen may make hydrogen bonding with DNA bases to be a carcinogen.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.444-450
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• 1998

In the present investigation, it is attempted to derive a yield function and associated flow rules of loose metal powders to predict plastic deformation and density change during compaction. The loose metal powders yield by shear stress as well as hydrostatic stress and the yield strength is much smaller in tension than compression. Therefore, a yield function for the powders is expressed as a shifted ellipse toward the negative direction in the hydrostatic stress axis in the space defined by the two stresses. Each of parameters A, B and .delta. used in the yield function is expressed as a function of relative density and it is determined by uniaxial strain and hydrostatic compressions using Cu powder. Flow rules obtained by imposing the normality rule to the yield function are applied to the analyses of unidirectional, bidirectional and hydrostatic compressions, resulting in an excellent agreement with experiments. The yield function is further examined by checking volume changes in plane stain, uniaxial strain and shear deformations.

• Journal of Korean society of Dental Hygiene
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• v.13 no.4
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• pp.645-650
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• 2013

Objectives : The aim of this study is to investigate dental clinic fear and anxiety in high school students. Methods : The subjects were 311 high school students aged 19 years. They completed self-reported questionnaire including general characteristics, dental clinic experiences, dentist or dental hygienist confidence, and dental fear. Data were analyzed using SPSS 18.0. Results : Poor oral health status showed negative attitude towards dental clinic visit. Girl students tended to have more fear than boy students. Muscle tension was the most common experience and was closely related to anesthetic needles and drills. Dental anxiety was caused by lack of confidence to dentists and dental hygienists. Students were more afraid of dentists than dental hygienists. Higher score of dental anxiety seemed to be associated with infrequent visit to dental clinic. Conclusions : Frequent regular dental checkup may reduce dental fear and anxiety. Dental clinic staff should try to minimize dental anxiety in performing treatment.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.191-196
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• 2001

The structural performance of a shear wall subjected to lateral loads is influenced by many factors, such as sectional shape, aspect ratio, vertical and horizontal reinforcement, lateral confinement and axial compression, etc. This experimental research is focusing to investigate the structural performance of T-shaped walls with different confining reinforcement. Experimental results show that all specimens finally failed by the crushing of the concrete in the compression zone. Although the location and content of the lateral confinement is different, the results are very similar during the negative loading direction where the flange is compressed. However, when flange is subjected to tension, the location and content of the lateral confinement results in a large difference in the structural performance of T-shaped walls. Therefore, selection of location and content of the lateral confinement would be important aspect in the design of the nonsymmetric structural walls.

• Journal of Trauma and Injury
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• v.28 no.4
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• pp.276-279
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• 2015

Subcutaneous emphysema is a benign condition following trauma (pneumothorax and oropharyngeal), cervical or thoracic procedures, and mediastinal infection. However, severe subcutaneous emphysema may be related to serious complications such as respiratory failure, airway compromise, and tension- related phenomena. Many alternative therapies have been tried to treat patients with this condition. We report our experience with vacuum-assisted closure therapy for treating patients with severe subcutaneous emphysema.

• Korean Journal of Child Studies
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• v.28 no.4
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• pp.187-196
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• 2007

This study evaluated attachment representation of school aged children, its relation to classification of family drawings, and their association with children's perceptions about families. The attachment representation of 43 children 6-9 years of age was evaluated by the Manchester Attachment Story Task (Green, Stanley, & Goldwyn, 2003) children's family drawings were classified by Fury's Family Drawing Scales (1996). Results showed that 12 children (28%) were avoidant, 23 (54%) secure, 4 (9%) resistant, and 4 (9%) were disorganized. Classification of childhood attachment representation showed a high concordance rate (86%) with family drawings. Securely Attached children showed positive perceptions such as family pride/happiness and vitality/creativity while Insecure children showed negative perceptions like emotional distance, tension and bizarreness.

• Journal of the Korean Chemical Society
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• v.25 no.3
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• pp.199-205
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• 1981

7-Alkyl-1-carboxyphenazine derivatives, bearing butyl or octyl group, were synthesize by the reaction of anthranilic acid with 3-nitroalkylbenzene, prepared from aniline and alcohols as starting materials through alkylation of 3-nitro-4-aminoalkylbenzene. And the products were also identified by elementary analysis, IR and NMR spectra. Surface tension of these derivatives in aqueous solution was determined. And also Antibiotic activity of these derivatives was tested, using Gram positive and negative bacillus and fungi. It showed that the antibiotic activity of these alkyl-substituted 1-carboxyphenazine derivatives was stronger than that of the 1-carboxyphenazine.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.171-181
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• 2004

This study was conducted to explore the tensile strength models in granular soil at the full range of unsaturated state. Direct tension experiments were carried out with a newly developed direct tension technique. The measured experimental data were compared with theoretical models developed by Rumpf and Schubert for monosized ideal particulate solids at the unsaturated state. To do this, the soil-water characteristic curve obtained from a suction-saturation experiment was used to define the unsaturation state and the negative pore water pressure with different water content levels, which are important factors in theoretical tensile strength models. The nonlinear behavior of the tensile strength for unsaturated granular soil at the pendular state is appropriately simulated with Rumpf's model. For the funicular and capillary states, the predicted trend by Schubert's model is properly matched with the experimental data: tensile strength steadily increases and reaches a maximum value and then decreases until it reaches zero. This comparison supports the concept that the tensile strength of unsaturated real granular soil can be approximately simulated with theoretical models.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.992-1006
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• 2008

The tunnel type spillways is under construction to increasing water reservoir capacity in Dae-am dam. Cutting-slope adjacent to outlet of spillways had been originally designed to be 63 degrees and about 65m in height. Examination is carried out in preceding construction that it is caused to some problems possibility which of machine for slope cutting couldn't approach to the site, blasting for cutting slope might have negative influence on highway and roads nearby, and fine view along the Tae-hwa river would be eliminated. In order to establish stability of tunnel and more friendly natural environment that we are carry out detailed geological surface survey and analysis of slope stability. So, we are design and construct for tunnel excavation with possible method that it is keep up natural slope. The result of survey and analysis that natural slope was divided 3 zone(A, B, C zone). In A and B zone, in first removed floating rock, high tensile tension net is install that it prevent of release and falling of rock, in order to security during under working. In addition to, pre-stressed rock anchor is install purpose of security during tunnel excavation because of fault zone near vertical developed above excavation level. Zone C is relatively good condition of ground, design is only carry out random rock bolt. All zone are designed and constructed drainage hole for groundwater and surface water is easily drain. Desinged slpoe is harmony with near natural environment. Successfully, construction is completed.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.177-177
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• 2023

The impacts of dams on transboundary flow are complex and challenging to project and manage, given the potential moderating influence of a broad range of anthropogenic and natural factors. This study presents a global meta-analysis of 168 studies that examines the effect magnitude of dams on downstream seasonal, annual flow, and hydrological extremes risk on 39 hotspot transboundary river basins. The study also evaluates the impact of 13 factors, such as climate, basin characteristics, dams' design and types, level of transboundary cooperation, and socioeconomic indicators, on the heterogeneity of outcomes. The findings reveal that moderators significantly influence the impact of dams on downstream flow, leading to considerable heterogeneity in outcomes. Transboundary cooperation emerges as the key factor that determines the severity of dams' effect on both dry and wet season's flows at a significance level of 0.01 to 0.05, respectively. Specifically, the presence of water-supply and irrigation dams has a significant (0.01) moderating effect on dry-season flow across basins with high transboundary cooperation. In contrast, for wet-season flow, the basin's vulnerability to climate extremes is associated with a large negative effect size. The various moderators have varying degrees of influence on the heterogeneity of outcomes, with the aridity index, population density, GDP, and risk level of hydro-political tension being the most significant factors for dry-season flow, and the risk level of hydro-political tension and basin vulnerability to climate extremes being the most significant for wet-season flow. The results suggest that transboundary cooperation is crucial for managing the impacts of dams on downstream flow, and that various other factors, such as climate, basin characteristics, and socioeconomic indicators, have significant moderating effects on the outcomes. Thus, context-specific approaches are necessary when predicting and managing the impacts of dams on transboundary flow.