• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1129-1132
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• 2008

기존의 하천은 제방의 직선화와 더불어 홍수량을 신속히 바다로 유출시키는데 하천정비를 목표로 삼고 추진해왔다. 그러나 하천주변의 인구 집중화와 더불어 도시화는 홍수피해에 대한 잠재력을 발전시킴과 동시에 불투수층의 증가로 인해 하천 위주의 홍수방어에 그 한계를 나타내고 있다. 따라서 최근 유역종합치수계획에서는 홍수량을 유역내에 분담시키고자 노력하고 있으며 이러한 노력중의 하나로 천변저류지와 습지를 이용한 홍수제어 방안이 꾸준히 제시되고 있다. 따라서 본 연구에서는 낙동강 본류내에 위치하고 있는 습지와 치수목적으로 계획중인 천변저류지를 고려하여 유역 수문모델링 SWAT모형을 이용하여 유역내에서 발생하는 홍수량 저감효과를 분석하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.190-201
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• 1996

설계자는 설계를 진행시켜 가면서 많은 의사 결정을 내려야 한다. 그 결정은 크게 선택 결정과 타협 결정으로 나뉘어질 수 있다. 선택 결정은 여러 평가 기준을 고려해 여러 대안들 중 하나를 선택하는 결정이며 타협 결정은 제한 조건과 목표들을 가장 잘 만족하는 설계 대안의 주요 치수를 결정하는 것이다. 이때 두 결정의 결과는 설계자의 의사에 크게 의존하게 된다. 따라서 설계자의 의사를 체계적이고 정확하게 반영시켜줄 필요가 있다. AHP 기법은 불분명한 선택 문제에 있어서 문제를 계층적으로 분석하여 평가함으로써 설계자의 의사를 체계적으로 반영시켜줄 수 있다. 또한 정성적인 성질들을 정량적인 판단 기준에 따라 평가함으로써 설계자의 의사를 보다 일관적으로 반영할 수 있다. 보통 공학 문제의 경우 하나의 설계 대안을 선택하고 또한 그 대안의 주요 치수를 동시에 결정해야 하는 결합된 문제이다. 이때 선택에 필요한 각 대안의 속성이 타협 문제 변수들의 함수로 표현되기 때문에 최적 과정 중에 계속 변화하게 된다. 또한 여러 속성을 고려할 경우 자릿수와 단위가 모두 다르기 때문에 속성들의 평가가 표준적으로 이루어져야 한다. 이 부분에 학습된 인공 신경망을 도입함으로써 변화하는 속성치를 자동적으로 평가할 수 있으며 설계자의 의사와 경험적인 지식도 반영할 수 있게 되었다.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.152-163
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• 2010

This study investigated the changes in gene expression when mineral trioxide aggregate (MTA) was applied in vitro to human dental pulp cells (HDPCs). MTA in a teflon tube (diameter 10 mm, height 2 mm) was applied to HDPCs. Empty tube-applied HDPCs were used as negative control. For microarray analysis, total RNA was extracted at 6, 24, and 72 hrs after MTA application. The results were confirmed selectively by performing reverse transcriptase polymerase chain reaction for genes that showed changes of more than two-fold or less than half. Of the 24,546 genes, 109 genes were up-regulated greater than twofold (e.g., FOSB, THBS1, BHLHB2, EDN1, IL11, FN1, COL10A1, and TUFT1) and 69 genes were down-regulated below 50% (e.g., SMAD6 and DCN). These results suggest that MTA, rather than being a bio-inert material, may have potential to affect the proliferation and differentiation of pulp cells in various ways.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.410-418
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• 2000

An in vitro study was performed to evaluate the effect of four variables on the temperature rise produced by polishing of restorations. The four variables were : restorative material, base, thickness of remaining dentin, continuous polishing or intermittent polishing. Class V cavities were cut on extracted molar and restored with composite resin, resin-modified glass ionomer cement, compomer, amalgam on the various bases (glass ionomer cement, zinc oxide eugenol cement, zinc phosphate cement) Dentin thickness under the restoration was 0.5mm, 1.5mm. Polishing was done with an aluminum oxide-coated disc. Polishing time was continuous or intermittent for up to 1 minute. Intra-pulpal temperature increased almost linearly in all cases. Amalgam produced highest temperature rises at the pulp, while the composite resin, resin-modified glass ionomer cement and compomer were not different for each other. The rate and extent of temperature rising of amalgam restoration was reduced by presence of a cement base. Zinc oxide eugenol cement bases showed the highest temperature rise, while glass ionomer cement, zinc phosphate cement were not different to the untreated tooth Thickness of remaining dentin was only significant for the amalgam restoration. Continuous polishing produced higher temperature rise than intermittent polishing.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.12-13
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• 1994

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.524-531
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• 1996

The objective of this study was to determine the important factors affecting the early natural regeneration of Pinus densiflora S. et Z. Seed germination, survival and height growth of the pine seedlings were examined at four experimental plots of P. densiflora forests including forest roadside. Plots I and III were thinned in 1992, plot II was treated with hexazinone in 1993 after seed tree method was applied in 1982 and 1989. Seedlings emerged after thinning and the rate of their emergence depended on forest floor conditions. Seedling survival was related with light conditions, herbaceous vegetation, and degrees of rainfall. More seedlings emerged in forest hauling roads than within the forest because soil scarification due to logging provided better conditions for seed germination and seedling growth. Seed supply was enough, but germination rate was very low in the forest compared with that in the greenhouse because micro-environments such as organic layer and herbaceous plant acted as limiting factors. Weed control was needed for 4 to 5 years until seedlings grew upto about 50cm in height which was similar to that of herbaceous plants. But 10-40% coverage of herbaceous vegetation was needed to protect small seedlings from heavy rain. Forest works such as thinning and logging, over 40% of light were important factors to help the pine regeneration. However, over 70% coverage of herbaceous vegetation, and heavy rain inhibited rather survival and growth of pine seedlings.

• Archives of design research
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• v.12 no.3
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• pp.73-80
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• 1999

Many domestic users complain about severe pain to the waist, neck, and shoulder as well as work performance because the domestic chair design was developed with western anthropometry dimension and design criteria. Ergonomic design standards are needed for office chair design to reduce stress and poor physical posture for various user body types. In this study, we have suggested design dimensions recommended from previous studies and Korean anthropometry data. We also have reviewed users' preference dimension through measured subjects and analyzed differences between users' preference dimension and the previous design criteria to verify physical appropriateness. We evaluated general office chairs and adjustable chairs which can adjust to fit each person. we also analyzed how each design dimension was reached and affected the human body by evaluation of physical discomfort and comfort. We have found seat height is very important in a workstation. If the seat height is high, it effects the thigh. If width, height, and angle of the backrest are wrong, fatigue to the shoulder, neck, and waist, etc.. As a result of this experiment, we suggested that the height of a seat for Koreans be 425mm for the fixed type and 365-484mm for the adjustable type. Also other design recommendations were suggested in the thesis. In conclusion, our research will be very important in the database because it provides adjustable ranges to fit user's body types in the various design fields.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.250-256
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• 2018

Dental avulsion, defined as the complete displacement of a tooth from the alveolar bone with consequent loss of the blood and nerve supply, was reported as one of the most severe dental injuries. Avulsion can cause tissue ischemia, which leads to pulp necrosis. Apexification is a conventional treatment method that induces an apical calcified barrier in immature roots with pulp necrosis. However, root development characterized by an increase in the root thickness and length cannot be achieved by apexification. The purpose of this case report was to describe the radiographic and clinical outcomes of regenerative endodontic treatment for the avulsed and necrosed permanent tooth with an immature root after replantation in a 5-year-old girl; the treatment was performed using a mixture of ciprofloxacin, metronidazole and cefaclor, CollaTape and Biodentine.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.110-115
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• 2003

Dens evaginatus is an anomalous tooth development arising during morphodifferentiation. It is most often reported in premolar, and familial occurrence has been reported. The primary dental complication of dens evaginatus is fracture or wear of the tubercle which leads to pulp exposure, pulpal necrosis and periapical infection. Pathosis of the pulp can occur before complete root formation with cessation of root development. A rational and conservative approach to the management of dens evaginatus in vital teeth includes early diagnosis and treatment to prevent fracture or attrition of the tubercle. This treatment would include careful sequential grinding, pulp capping, preventive resin restoration. When presented with a case of dens evaginatus in a nonvital tooth with incomplete root development, the treatment of choice has been extraction, apexification. We report two cases of dens evaginatus that appear in two sisters. In the elder, a periapical lesion on radiographs is shown, and it is treated by calcium hydroxide apexification. The other sister is early recognized of dens evaginatus, it is treated using glass ionomer cement reinforcing with sequential grinding.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.216-222
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• 2013

Paradigm shift in management of infected immature permanent teeth has occurred. The new concept of the treatment includes minimal or no intracanal instrumentation, disinfection with triple antibiotic paste and sealing with mineral trioxide aggregate. This regenerative endodontic treatment promotes differentiation of periradicular stem cells that induce regeneration of vital tissue and continuation of root formation. Thorough disinfection and three-dimensional scaffold are important in this new concept of the treatment. Platelet-rich fibrin has been reported as 'new scaffold' instead of blood clot, which had been used in the past. Triple antibiotics can be used to disinfect the tooth but may lead to complications including discoloration. Three cases of infected immature permanent tooth caused by dens evaginatus fracture are presented. After removal of necrotic pulp and thorough intracanal irrigation, only platelet-rich fibrin was applied to the root canal in the first case. In the other cases, topical antibiotics was used for disinfection and platelet-rich fibrin for scaffold. In all the cases, the opening was sealed with mineral trioxide aggregate. All the cases showed proper healing of inrabony lesion and some lengthening of root. According to these cases, regenerating vital tissue of the infected immature permanent tooth can be achieved with disinfection and application of platelet-rich fibrin.