골 이식술에 의해 치료된 골연하 결손부의 방사선학적 변화 양상의 관찰

류상호,박진우,서조영,이재목,Ryu, Sang-Ho,Park, Jin-Woo,Suh, Jo-Young,Lee, Jae-Mok 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.3

Purpose: A number of techniques and materials have been used for periodontal regeneration and bone graft procedures with guided tissue regeneration(GTR) have been suggested as alternatives to osseous surgery in the management of local infra-bony defects. However, the long-term stability and treatment outcome following bone graft procedure of infra-bony defects is poorly documented. The purpose of this study was to assess radiographic change in infra-bony defects over 2 years after bone graft procedures with various graft materials. Material and Methods: Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients showed clinical and radiographic evidence of infra-bony defect(s). 44 sites of 34 patients aged 31 to 69 (mean age 48.3) were treated by bone graft procedure with a bone graft material. Baseline and 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, defect depth, defect angle, bone graft materials) using the paired t-test were examined. Result: We observed $1.15{\pm}1.95\;mm$ of bone fill, $0.40{\pm}1.19\;mm$ of crestal resorption, $1.55{\pm}1.77\;mm$ of defect resolution, and $40{\pm}44%$ of percentage of defect resolution. Deeper initial defect depth, narrower initial defect angle showed significantly greater bone fill, defect resolution, and % of defect resolution. But no significant difference was observed in graft sites and graft materials. Conclusion: If good oral hygiene maintenance and periodic recall check of patients is assured, bone graft procedure using various graft materials is one of the appropriate treatment modality for regenerative therapy of infra-bony defects.

하자담보책임에 있어 하자추정을 통한 입증책임의 전환 - 독일민법 제477조와 우리법에의 시사점 -

김동환 전북대학교 부설법학연구소 2022 法學硏究 Vol.69 No.-

According to the general principle of burden of proof, a buyer must prove that there was a defect at the time of passing of the risk in order to exercise the right die to defects which stipulated in Article 437 of the German Civil Code. If the defect is discovered after the time of transfer of the risk, the buyer must also prove the caused defect which existed before the time. However, the principle of proof gives rise to difficulties for the buyer to prove. Taking this into account, the German Civil Code reduces the burden of proof of consumers to protect them by stipulating as “If, within six months after the date of the passing of the risk, a material defect manifests itself, it is presumed that the thing was already defective when risk passed, unless this presumption is incompatible with the nature of the thing or of the defect” through the Article 477. Under this provision, a consumer only needs to prove the defect which existed at the time of asserting the liability for warranty against defect of seller and that such defect was revealed within six months from the time of the passing of the risk. On the other hand, in order to avoid liability for defects, seller must prove that there was any defect on the material when the risk is passed. According to the Korean Civil Code, however, a buyer shall prove that there was a defect in the material before the date of passing of the risk in order to claim the liability for warranty against defect which mentioned through the Article 580. Thus, it is necessary to the Korean Civil Code to impose a regulation such as the Article 477 of the German Civil Code for substantial protection of the right of consumer. 독일민법상 매수인이 제437조에 규정된 하자로 인한 권리를 행사하기 위해서는 입증책임의 일반원칙에 따라 위험이전시에 하자가 존재하였음을 입증해야 한다. 매수인은 하자가 위험이전시 이후에 발견된 경우, 이러한 하자의 원인이 되었던 위험이전시에 존재하였던 하자도 입증해야 한다. 하지만 오늘날 매매의 목적물은 기술적으로 복잡한 물건이 상당수여서 매수인이 그러한 물건의 하자를 입증한다는 것은 쉬운 일이 아니다. 독일의 입법자는 이러한 점을 고려하여 소비재매매의 경우 제477조에 하자추정을 통해 소비자의 입증책임을 완화하는 규정을 두고 있다. 이에 따르면 물건의 하자가 위험이전시로부터 1년(살아 있는 동물매매의 경우에는 6개월) 내에 드러난 경우, 위험이전 당시에 이미 하자가 존재하였던 것으로 추정된다. 이로써 입증책임은 전환되어 소비자는 사업자의 하자담보책임을 주장하는 시점의 하자의 존재와 이러한 하자가 위험이전시로부터 1년 내에 드러났음만을 입증하면 되고, 반대로 매도인은 위험이전시에 하자가 없었다는 점을 입증하여야 한다. 우리법에서는 권리를 주장하는 사람은 자기에게 유리한 권리근거규정의 요건사실, 즉 권리발생사실에 대한 입증책임을 지게 된다(통설 및 판례). 따라서 매수인인 소비자가 민법 제580조 이하에 규정된 하자담보책임을 주장하기 위해서는 위험이전시에(사견) 물건에 하자가 있었음을 입증해야 한다. 결국 우리법에서도 하자의 입증책임과 관련하여 소비자를 보호할 법정책적인 필요성이 존재하고, 이에 독일민법 제477조에 관한 논의가 우리에게 주는 시사점은 적지 않다고 할 수 있다.

Hole Defects on Two-Dimensional Materials Formed by Electron Beam Irradiation: Toward Nanopore Devices

Park, Hyo Ju,Ryu, Gyeong Hee,Lee, Zonghoon Korean Society of Microscopy 2015 Applied microscopy Vol.20 No.1

Two-dimensional (2D) materials containing hole defects are a promising substitute for conventional nanopore membranes like silicon nitride. Hole defects on 2D materials, as atomically thin nanopores, have been used in nanopore devices, such as DNA sensor, gas sensor and purifier at lab-scale. For practical applications of 2D materials to nanopore devices, researches on characteristics of hole defects on graphene, hexagonal boron nitride and molybdenum disulfide have been conducted precisely using transmission electron microscope. Here, we summarized formation, features, structural preference and stability of hole defects on 2D materials with atomic-resolution transmission electron microscope images and theoretical calculations, emphasizing the future challenges in controlling the edge structures and stabilization of hole defects. Exploring the properties at the local structure of hole defects through in situ experiments is also the important issue for the fabrication of realistic 2D nanopore devices.

다양한 치주 골내낭과 이개부 병변의 처치를 위한 $BBP^{(R)}$ 이식재의 임상적 효과

김명진,이주연,김성조,최점일,Kim, Myung-Jin,Lee, Ju-Youn,Kim, Sung-Jo,Choi, Jeom-Il 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.1

Purpose: Periodontal intrabony defects have great deal of importance since they contribute to the development of periodontal disease. Current treatment regimens for intrabony defects involve grafting of numerous bony materials, GTR using biocompatible barriers, and biomodification of root surface that will encourage the attachment of connective tissue. Xenograft using deproteinized bovine bone particles seems to be very convenient to adjust because it doesn't require any donor sites or imply the danger of cross infections. These particles are similar to human cancellous bone in structure and turned out to be effective in bone regeneration in vivo. We here represent the effectiveness of grafting deproteinized bovine bone particles in intrabony defect and furcation involvements that have various numbers of bony walls. Materials and methods: Open flap debridement was done to remove all root accretions and granulation tissue from the defects within persisting intrabony lesions demonstrating attachment loss of over 6mm even 3 months after nonsurgical periodontal therapy have been completed. Deproteinized bovine bone particles($BBP^{(R)}$, Oscotec, Seoul) was grafted in intrabony defects to encourage bone regeneration. Patients were instructed of mouthrinses with chlorohexidine-digluconate twice a day and to take antibiotics 2-3 times a day for 2 weeks. They were check-up regularly for oral hygiene performance and further development of disease. Probing depth, level of attachment and mobility were measured at baseline and 6 months after the surgery. The radiographic evidence of bone regenerations were also monitored at least for 6 months. Conclusion: In most cases, radio-opacities increased after 6 months. 2- and 3-wall defects showed greater improvements in pocket depth reduction when compared to 1-wall defects. Class I & II furcation involvements in mandibular molars demonstrated the similar results with acceptable pocket depth both horizontally and vertically comparable to other intrabony defects. Exact amount of bone gain could not be measured as the re-entry procedure has not been available. With in the limited data based on our clinical parameter to measure pocket depth reduction following $BBP^{(R)}$ grafts, it was comparable to the results observed following other regeneration techniques such as GTR.

QFN 반도체 패키지의 외형 결함 검사를 위한 효과적인 결함 분류 시스템 개발

김효준,이정섭,주효남,김준식,Kim, Hyo-Jun,Lee, Jung-Seob,Joo, Hyo-Nam,Kim, Joon-Seek 한국융합신호처리학회 2009 융합신호처리학회 논문지 (JISPS) Vol.10 No.2

There are many different types of surface defects on semiconductor Integrated Chips (IC's) caused by various factors during manufacturing process, such as cracks, foreign materials, chip-outs, chips, and voids. These defects must be detected and classified by an inspection system for productivity improvement and effective process control. Among defects, in particular, foreign materials and chips are the most difficult ones to classify accurately. A vision system composed of a carefully designed optical system and a processing algorithm is proposed to detect and classify the defects on QFN(Quad Flat No-leads) packages. The processing algorithm uses features derived from the defect's position and brightness value in the Maximum Likelihood classifier and the optical system is designed to effectively extract the features used in the classifier. In experiments we confirm that this method gives more effective result in classifying foreign materials and chips. 반도체 외관결함에는 발생 요인이 각각 다른 crack, foreign material, chip-out, chip, void 등이 있으며, 검사 시스템에서는 결함 유무 및 결함 분류를 수행하여 효과적인 공정관리가 가능하여야 한다. 본 논문에서는 QFN 패키지 결함의 분류를 위한 알고리즘 및 광학시스템을 제안한다. 제안한 방법에서 분류가 어려운 결함 중 하나인 foreign material 과 chip의 효과적인 분류를 위해 제안한 결함의 위치, 밝기의 특징정보(feature)를 사용한 ML(Maximum Likelihood ratio) 분류방법 및 특징정보 획득에 효과적인 광학계를 제안하였다. 실험 결과에서 분류가 어려운 foreign material과 chip에 대한 신뢰성 높은 분류성능을 보였다.

가토에서 조직 재생 이식재로서 무세포성 진피 기질의 효용

최종학(Jong-Hak Choi),류재영(Jae-Young Ryu),유선열(Sun-Youl Ryu) 대한구강악안면외과학회 2009 대한구강악안면외과학회지 Vol.34 No.2

Purpose: The present study was aimed to examine the effect of acellular dermal matrix (AlloDerm) grafted to the experimental tissue defect on tissue regeneration. Materials and Methods: Male albino rabbits were used. Soft tissue defects were prepared in the external abdominal oblique muscle. The animals were then divided into 3 groups by the graft material used: no graft, autogenous dermis graft, and AlloDerm graft. The healing sites were histologically examined at weeks 4 and 8 after the graft. In another series, critical sized defects with 8-㎜ diameter were prepared in the right and left iliac bones. The animals were then divided into 5 groups: no graft, grafted with autogenous iliac bone, AlloDerm􀋓 graft, AlloDerm graft impregnated with rhBMP-2, and AlloDerm graft with rhTGF-1. The healing sites of bone defect were investigated with radiologic densitometry and histological evaluation at weeks 4 and 8 after the graft. Results: In the soft tissue defect, normal healing was seen in the group of no graft. Inflammatory cells and foreign body reactions were observed in the group of autogenous dermis graft, and the migration of fibroblasts and the formation of vessels into the collagen fibers were observed in the group of AlloDerm graft. In the bone defect, the site of bone defect was healed by fibrous tissues in the group of no graft. The marked radiopacity and good regeneration were seen in the group of autogenous bone graft. There remained the traces of AlloDerm with no satisfactory results in the group of AlloDerm graft. In the groups of the AlloDerm graft with rhBMP-2 or rhTGF-1, there were numerous osteoblasts in the boundary of the adjacent bone which was closely approximated to the AlloDerm with regeneration features. However, the fibrous capsule also remained as in the group of AlloDerm graft, which separated the AlloDerm and the adjacent bone. Conclusions: These results suggest that AlloDerm can be useful to substitute the autogenous dermis in the soft tissue defect. However, it may not be useful as a bone graft material or a carrier, since the bone defect was not completely healed by the bony tissue, regardless of the presence of osteogenic factors like rhBMP-2 or rhTGF-1.

Impact of grain boundary defect on performance of perovskite solar cell

Iftiquar, S.M.,Yi, Junsin Elsevier 2018 Materials science in semiconductor processing Vol.79 No.-

<P>Methyl ammonium lead halide (MAPbI(3)) perovskite is a crystalline material. It shows interesting properties that are suitable for absorber layer of solar cell. An optimized solar cell requires 200-400 nm thick absorber layer. However, the thin absorber layer inevitably contains grain of crystallites and hence grain boundary (GB) defects. The GB defects affect device performance. Therefore, we theoretically investigated the effects of GB defects on performance of solar cells. In this simulation studies, we kept total mid-gap defect density (N-d) as constant at 4x10(17) cm(-3) but varied the GB defect density (GB(dd)) from 3x10(12) cm(-3) to 3x10(22) cm(-3), because of which, the observed short circuit current density (J(sc)) of the cells remain nearly unchanged, but the open circuit voltage (V-oc) and power conversion efficiency (PCE) decreased steadily, while the fill factor (FF) shows a different trend of variation in a region (Region-X, say) where the GB(dd) and the N-d were nearly equal. A further investigation reveals that in the Region-X, a transition happens from defect mediated recombination to GB mediated recombination, where the reverse saturation current density (J(0)) and diode ideality factor (n) of the solar cells, reduce sharply from 3.46x10(-13) A cm(-2) to 2.65x10(-19) A cm(-2) and 1.9 to 1.1, respectively for a cell with 200 nm thick absorber layer. For 400 nm thick absorber layer, reduction of these parameters was 1.96x10(-13) A cm(-2) to 1.20x10(-17) A cm(-2) and 1.8 to 1.2 respectively.</P>

Ability of non-destructive assay techniques to identify sophisticated material partial defects

Lloyd, Cody,Goddard, Braden Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6

This study explores the ability of non-destructive assay techniques to detect a partial material defect in which 100 g of plutonium are diverted from the center of a 1000 g can of PuO₂ powder. Four safeguards measurements techniques: neutron multiplicity counting, calorimetry, gravimetry, and gamma ray spectroscopy are used in an attempt to detect the defect. Several materials are added to the partial defect PuO₂ can to replicate signatures of the diverted material. ²⁵²Cf is used to compensate for the doubles neutron counts, ²⁴¹Am is used to compensate for the decay heat, and aluminum is used to compensate for the weight. Although, the doubles and triples difference before and after diversion are statistically indistinguishable with the AWCC in fast and thermal mode, the difference in the singles counts are statistically detectable in both modes. The relatively short half-life of ²⁵²Cf leads to a decrease (three sigma uncertainty) in the doubles neutron counts after 161 days. Combining this with the precise quantity of ²⁴¹Am needed (10.7 g) to mimic the heat signature and the extreme precision in ²⁵²Cf mass needed to defeat neutron multiplicity measurements gives reassurance in the International Atomic Energy Agency's ability to detect partial material defects.

항공 우주 해상 : 주성분 분석과 이차 판별 분석 기법을 이용한 항공기 복합재료에서의 자동 결함 검출 및 분류

김영범 ( Young Bum Kim ),신덕하 ( Duk Ha Shin ),황승준 ( Seung Jun Hwang ),백중환 ( Joong Hwan Baek ) 한국항행학회 2014 韓國航行學會論文誌 Vol.18 No.4

본 논문에서는 항공기 복합재료 내부의 결함을 자동으로 검출하고 분류하는 초음파 검사 방식을 제안한다. 결함 검출을 위해서 초음파의 국부 최대값을 이용해 피크(peak) 값을 추출해낸다. 피크의 거리정보를 이용해 히스토그램화 하며 시편의 표면과 바닥의 백월에코(back-wall echo)를 결정한다. 이를 통해 C-scan 영상을 생성한다. 검출된 피크의 평균과 분산을 이용해 임계값을 정하고 그 값으로 결함여부를 판단한다. 결함의 종류를 구분하기 위해서는 주성분 분석(PCA; principal component analysis)와 이차 판별 분석(QDA; quadratic discriminant analysis)를 수행하였다. PCA를 통한 512개의 차원은 주성분으로 변환 시 30개의 주성분에 99% 이상의 분산이 포함되었다. 주성분 개수를 한정시킴으로써 차원 축소를 통해 계산량을 크게 줄였고 오분류를 최소화하였다. 이차 판별 분석을 적용해 결정경계(decision boundary)의 방정식을 얻었고 이를 통해 결함을 분류할 수 있음을 실험을 통해 보였다. In this paper, we propose a ultra sound inspection technique for automatic defect detection and classification in aircraft composite materials. Using local maximum values of ultra sound wave, we choose peak values for defect detection. Distance data among peak values are used to construct histogram and to determine surface and back-wall echo from the floor of composite materials. C-scan image is then composed through this method. A threshold value is determined by average and variance of the peak values, and defects are detected by the values. PCA(principal component analysis) and QDA(quadratic discriminant analysis) are carried out to classify the types of defects. In PCA, 512 dimensional data are converted into 30 PCs(Principal Components), which is 99% of total variances. Computational cost and misclassification rate are reduced by limiting the number of PCs. A decision boundary equation is obtained by QDA, and defects are classified by the equation. Experimental result shows that our proposed method is able to detect and classify the defects automatically.

Investigation on native defects of α-MgAgSb and its effects on thermoelectric properties using first principles calculations

Zhuoyi Pang,Xiwen Zhang,Chao Wang 한국물리학회 2017 Current Applied Physics Vol.17 No.10

a-MgAgSb is a promising thermoelectric materials having good performance at medium temperature. Native defects in a-MgAgSb are frequently reported experimentally and are tightly involved in the thermoelectric properties of a-MgAgSb. In this paper, all possible native defects in a-MgAgSb are calculated as well as detailed results are given and discussed. The concentrations of several dominant native defects, for example, VAg and AgSb, could reach up to 104 cm3 at 540 K. Furthermore, the electronic structure and transport properties of a-MgAgSb with dominant native defects are investigated. Results show that the introduction of AgMg and VAg contributes to a much lower inertial mass and slight decrease in Seebeck coefficient. The lattice thermal conductivity is greatly reduced with the introduction of native defects. For a-MgAgSb with VAg, the peak ZT could reach up to 1.84 at 420 K. Our calculation demonstrates that defect engineering is an effective strategy to enhance thermoelectric performance of the materials.