• 한국재료학회지
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• 제5권6호
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• pp.639-643
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• 1995

수소화된 비정질 게르마늄 (a-Ge : H)에 대해 전기전도율이 297-423K 사이에서 연구되었다. 측정된 전기전도율의 Arrhenius 구성에 의해 pre-exponential 인수 $\sigma$$_{0}$ 및 활성화에너지 $E_{c}$- $E_{F}$가 결정되었다. 튀어오름(kink) 온도의 존재로 인해 전기전도율의 arrhenius 구성이 두 exponential 함수에 의해 표현되었고, 이에 의해 결정된 페르미준위의 통계이동계수 ${\gamma}$$_{F}$는 약 8.65$\times$$10^{-3}$eV/K이었으며, $\sigma$$_{0}$는 약 2$\Omega$$^{-1}$$cm^{-1}$ /이었다. 전기전도율 데이터로부터 결함밀도가 수치해석적 방법에 의해 계산되었고, 결함밀도는 측정된 온도영역하에서 약 2배 정도 변화하였다 변화하였다화하였다

• Journal of Periodontal and Implant Science
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• 제31권2호
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• pp.421-436
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• 2001

Transforming growth $factor-{\beta}(TGF-{\beta})$is a polypeptide biologic mediator considered to play a role in promoting bone formation in bony defect area. The purpose of this study was to examine the effect of $TGF-{\beta}$ to the periodontal regeneration of class III furcation defect in dogs. Classs III furcation defects were surgically created on the third and the fourth premolars bilaterally in the mandibles of eight mongrel dogs. Experimental periodontitis were induced by placing small cotton pellets into the created defects for 3 weeks. Experimental sites were divided into 4 groups according to the treatment modalities: Group I-Surgical debridement only; Group II-allogenic demineralized freeze dried bone grafting; Group III-allogenic demineralized freeze dried bone soaked in $TGF-{\beta}(4ng/10{\mu}l)$grafting; Group IV-allogenic demineralized freeze dried bone soaked in $TGF-{\beta}(20ng/10{\mu}l)$ grafting. The animals were sacrificed in the 8th week after periodontal surgery and the decalcified and undecalcified specimens were for histological and histometric examination. Although no significant differences was seen in the length of epitheial growth and connective attachment, group III showed the least apical migration among treatment groups. The amount of bone repair was significantly greater in group III, IV compared to group I and group II. New attachment formation was significantly greater in group III and group IV compared to group I and group II. These results suggest the allogenic demineralized freeze dried bone with $TGF-{\beta}$ in class III furcation defect has the potentiality of promoting alveolar bone formation and periodontal regeneration.

• 대한조선학회지
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• 제21권1호
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• pp.35-42
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• 1984

In the present study, rotating bending fatigue tests have been carried out in three kinds of carbon steel specimens; an annealed low carbon steel, an annealed high carbon steel and quenched-tempered high carbon steel; with a small artificial surface defect that might exist in real structures. Fatigue crack lengths have been observed by a method of replication in order to investigate the growth characteristic of fatigue crack in the viewpoints of strength of materials and fracture mechanics. The main results obtained are as follows: 1) The effect of a small surface defect upon the reduction of fatigue limit is considerably large, and the rate of fatigue limit reduction grows in the following order; annealed low carbon steel(mild steel), annealed high carbon steel, quenched-tempered high carbon steel. 2) When the growth rate of surface crack length(2a) was investigated in the viewpoints of fracture mechanics based upon $ ${\Delta}K_{\varepsilon}$, the dependence of stress level and of surface defect size disappear, and there exists a linear relationships between d(2a)/dN and ${\Delta}K_{{\varepsilon}t},\;\Delta_{{\varepsilon}t}\sqrt{{\pi}a}$, on log. plot, i.e, $d(2a)/dN={C{\cdot}{\Delta}K_{\varepsilon}}^3_t$, where ${\Delta}_{{\varepsilon}t}\sqrt{{\pi}a}$ a is the cyclic total strain intensity factor range.

• 대한기계학회논문집A
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• 제33권8호
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• pp.807-812
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• 2009

Most structure engineers give the casting components over-estimated factor of safety without any reasonable foundation due to the worries about the unavoidable defects such as shrinkages and porosity in castings; the engineers have little knowledge on the relation between the defect and structural behavior. And the workers in casting field also do not know how to control the defects by manufacturing; they do not know to where the defects move or until how size they reduce the defects. In this study, shrinkage defect was scanned by industrial computerized tomography instrument (CT), and subsequently was modeled to a spheroid primitive for structural analysis. Using these simplified models of shrinkage, we observed the effects of the defect on the results of the structural analysis. A commercial structural analysis code was used to do the analysis works. Considering the conclusions, it is possible to manage the shrinkages effectively in casting process and to design the products with more reliable

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.627-628
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• 2015

Construction defect which can causes economic damage such as schedule delay, cost overrun is a considerably important factor in construction industry. In general, a construction defect features a difficulty to find out causes precisely because it occurs when several interrelated causes combine. Yet, studies have tried to understand the interrelationships between factors are limited. In addition, despite of a tremendous amount of construction data, it's not still enough to analyze them, but tends to depend on experience or know-how of practitioners. Thus, it is necessary to identify underlying causes in influential factors by utilizing related data. This paper analyses Interrelationships between causal factors using Association Rule Mining to discover root causes of construction defects. Confidence and Lift that can be used for presenting the interrelationships of the causes were extracted from 1241 cases in 30 projects in Korea. It is expected that this paper allows the construction managers to discover key factors and make right decisions to reduce occurrence of construction defects. Furthermore, analysis of interrelationships can improve understanding of structural patterns of construction defects.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제11권6호
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• pp.229-236
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• 2022

사물인터넷을 기반으로 실시간으로 소화기 주변의 상태와 화재 발생 여부, 소화기의 상태를 확인할 수 있는 웹 시스템과 화재 알림을 받을 수 있는 애플리케이션을 구현한다. 해당 시스템의 목표를 명확하게 정하고 구조를 상세히 정의함으로써 개발 도중 일어나는 오류를 최소화한다. 또한, 스마트소화기에 대한 요구분석과 설계, 구현 단계에서 제품 결함을 찾아내고 그 원인을 분석하여 결함을 줄이는 방법을 제안한다. 제안하는 연구를 통해 IoT 기반의 스마트 소화기에 대해 결함관리 신뢰성을 확보할 수 있다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제20권2호
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• pp.173-183
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• 1998

$TGF-{\beta}$ is one of growth factors that may be involved in the formation of bone and cartilage. Multiple studies demonstrate that $TGF-{\beta}$ is involved in regulating cell proliferation, differentiation and matrix synthesis, events observed in frature healing. The apperance of $TGF-{\beta}$ in the fracture during healing was evaluated by immunohistologic localization of $TGF-{\beta}$ using antibody. Twenty Sprauge-Dawley strain white male rats, each weiging about 150grams were used and divided two groups. The one group, the $2{\times}2mm$ bony defect was formed in the right femur. The other group, $4{\times}2mm$ bony defect was formed in right femur. Both group were sacrificed at 3day, 1, 2, 3, 4 week and femur were harvested, paraffin sections were stained with H & E, MT stain, immunihistochemical staining with $TGF-{\beta}$ antibody and observed under light microscope. The result were as follows: 1. New bone formation and cartilagenous tissue was seen at 3day. And in the $2{\times}2mm$ bony defect group, $TGF-{\beta}$ stained the cell surounding new bone. 2. The osteoclast and trabecular was seen at 1week. $TGF-{\beta}$ stained the osteoblast and in the $2{\times}2mm$ bony defect group was stained more than $4{\times}2mm$ bony defect group. 3. The lamella bone and trabecule was seen from 3, 4week, and $TGF-{\beta}$ stained almost negative. From the above finding, we could concluded that $TGF-{\beta}$ stained the osteoblast at early stage and 1week, the peak stain was seen from 1week, and then decreased, almost negative stain was seen at 3, 4week.

• Archives of Plastic Surgery
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• 제33권2호
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• pp.213-218
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• 2006

As the large defect of peripheral nerve occurs, the autologous nerve graft is the most ideal method but it has many limitations due to donor site morbidities. Various materials have been developed for the nerve defect as the conduits, but none of these materials is satisfactory. Among them, $Gore-Tex^{(R)}$ tube seems to be one of the most ideal nerve conduit materials at peripheral nerve defect. Many researches have focused on finding the neurotrophic factors. It is recently demonstrated that Valproic acid(VPA) has an effect of axonal regeneration as a neurotrophic factor without enzymatic degradation and toxicity problems. The purpose of this study is to evaluate the effect of VPA on the nerve regeneration at the peripheral nerve defect. A 10 mm gap of rat sciatic nerve was made and $Gore-Tex^{(R)}$ tube filled with biceps femoris muscle was placed at the nerve defect site. We let the rat take VPA as drinking water in experimental group and did not give VPA to the control group. We estimated the results as electrophysiologic and histological aspects for 16 weeks after the surgery. The nerve conduction velocity, total myelinated axon count, myelin sheath thickness and mean nerve fiber diameter significantly increased in VPA-treated experimental group when compared to the control (p < 0.05). From the above results, we conclude that VPA promotes the nerve regeneration at the peripheral nerve defect site. It is suggested that $Gore-Tex^{(R)}$ tube filled with skeletal muscle and VPA administration may be a good substitute for autologous nerve graft.

• 한국압력기기공학회 논문집
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• 제16권2호
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• pp.1-9
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• 2020

Large-scale industrial facility structures continue to deteriorate due to the effects of operating and environmental conditions. The problems of these industrial facilities are potentially causing economic losses, environmental pollution, casualties, and national losses. Accordingly, in order to prevent disaster accidents of large structures in advance, the necessity of diagnosing structures using non-destructive inspection techniques is being highlighted. The defect occurrence, location and defect type of the structure are important parameters for predicting the remaining life of the structure, so continuous defect observation is very important. Recently, many researchers have been actively researching real-time monitoring technology to solve these problems. Structure Health Monitoring Inspection is a technology that can identify and respond to the occurrence of defects in real time, but there is a limit to check the degree of defects and the direction of growth of defects. In order to compensate for the shortcomings of these technologies, the importance of defect imaging techniques is emerging, and in order to find defects in large structures, a method of inspecting a wide range using guided ultrasonic is effective. The work presented here introduces a calculation for the shape factor for evaluation of the damaged area, as well as a variable β parameter technique to correct a damaged shape. Also, we perform research in modeling simulation and an experiment for comparison with a suggested inspection method and verify its validity. The curved structure image obtained by the advanced RAPID algorithm showed a good match between the defect area and the shape.

• Journal of Periodontal and Implant Science
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• 제37권3호
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• pp.465-478
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• 2007

Various periodontal barrier membranes used in many clinical and experimental fields, and many recent studies of membranes have reported good results. To improve clinical results, selection of barrier membranes is an important factor. So, we need not only to evaluate various barrier mem-branes, but also to understand the property of barrier membranes appropriate to defect characteristics. For this purpose, this study reviewed available literature, evaluated comparable experimental models, and compared various barrier membranes. From above mentioned methods, the following conclusions are deduced. 1. In i-wall periodontal defect models, new bone formation showed a consistent result, almost 30% of the defect size. New cementum formations measured mostly 40% of the defect size, but showed more variations than new bone formations. This seems to be resulted form difference in experimental methods, so standardization in experimental methods is needed for future studies. 2. Application PLGA barrier membrane to periodontal defect demonstrated improved healing in new bone and new cementum. 3. There was a minimal periodontal regeneration with calcium sulfate barrier membrane only. But, there was better healing pattern in combination of calcium sulfate membrane with bone graft material, such as DFDBA, 4. There was no significant difference between the experimental group that used chitosan mem-brane only and the control group. But, in combination with bone graft material for space maintanence, periodontal regeneration was improved. Overall, Space maintenance is a critical factor for Guided tissue regeneration using barrier membranes. Also, a barrier membrane itself that has difficulty in maintaining space, achieved better result when used with graft material.