• 대한치과보철학회지
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• 제32권4호
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• pp.593-607
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• 1994

The purpose of this study is to evaluate the effect of the bone morphogenetic protein, bone matrix gelatin and collagen matrix on the amount and shape of generating new bone adjacent to the implant. Implants were inserted in the mandible of adult dogs at 2 months after teeth extraction. Artificial bony defects, 3mm in width and 4mm in depth were made at the mesial and distal side of implant. Experimental groups were divided into three groups ; Group 1 : Defects filled with collagen matrix and bone morphogenetic protein, Group 2 : Defects filled with bone matrix gelatin. Control group : Defects filled with only collagen matrix. After implantation, the animals were sacrificed at 1,3,5 and 10 weeks for light microscopic examination. For the fluorescent microscopic examination. each tertracycline Hcl and calcein were injected at 1, 3, 5, 8 and 10 weeks after implantation. The results obtained were as follows : 1. The molecular weight of bovine BMP was about 18,100 by hydroxyapatite chromatography. 2. Osseointegration was observed in experimental groups 1 & 2, and BMG and BMP had an excellent bone forming capability as a filling materials to the repair of the bone defects. 3. The degree of healing of bone defect area, the experimental group 1 showed more prominent bone formation than control group, and the control group showed fibrous connective tissue between the implant and the bone. 4. In the fluorescent microscopic findings, bone remodelling was observed regenerative lamellar bone at defect area in experimental group 1, and partial remodelling in experimental group 2, In the control group, fibrous connective tissue was observed between the implant and bone surface and sign of remodelling was not apperaed. Above results suggest that BMP has rapid osteoinductive property and can be used clinically as a bone substitute on bone defects around implants.

• 한국정보통신학회논문지
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• 제26권6호
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• pp.834-841
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• 2022

최근 스마트팩토리와 인공지능 기술의 수요 증가로 인해 다양한 분야에서 인공지능 기술을 적용하는 연구가 진행되고 있다. 결함 검사 분야에서도 인공지능 알고리즘을 도입하기 위한 노력을 기울이고 있다. 특히, 금속 외관의 결함을 검출하는 연구는 다른 소재(목재, 플라스틱, 섬유 등)의 결함을 검출하는 연구에 비해 많은 연구가 이루어지고 있다. 본 논문에서는 머신러닝 기법(서포터 벡터 머신(SVM: Support Vector Machine), 소프트맥스 회귀(Softmax Regression), 결정 트리(Decesion Tree))과 차원 축소 알고리즘(주성분 분석(PCA: Principal Component Analysis), 오토인코더(AutoEncoder))의 9가지 조합과 2가지 합성곱신경망(CNN: Convolutional Neural Network) 기법(자체 알고리즘, ResNet)의 금속 외관의 결함 분류 성능 및 속도를 비교하고 분석하는 연구를 수행하고자 한다. 두 종류의 학습 데이터셋((i) 공용 데이터셋(Public Dataset), (ii) 실측 데이터셋(Actual Dataset))에 대한 실험을 통해 각 데이터셋에 대한 성능 및 속도를 비교 분석하고, 가장 효율적인 알고리즘을 찾아낸다.

• 한국환경과학회지
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• 제16권10호
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• pp.1169-1177
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• 2007

The main objective of this research was to evaluate the effects of process variables which were forming ability, flow displacement, effective stress, effective strain, fluid vector and products defects on manufactured artificial lightweight aggregate made of both incinerated sewage sludge ash and clay by means of the numerical analysis of a rigid-plastic finite element method. CATIA (3D CAD program) was used for an extrusion metal mold design that was widely used in designing aircraft, automobile and metallic molds. A metal forming analysis program (ATES Co.) had a function of a rigid-plastic finite element method was used to analyze the program. The result of extrusion forming analysis indicated clearly that a shape retention of the manufactured artificial light-weight aggregate could be maintained by increasing the extrusion ratio (increasing compressive strength inside of extrusion die) and decreasing the die angle. The stress concentration of metal mold was increased by increasing an extrusion ratio, and it was higher in a junction of punch and materials, friction parts between a bottom of the punch and inside of a container, a place of die angle and a place of die of metal mold. Therefore, a heat treatment as well as a rounding treatment for stress distribution in the higher stress concentration regions were necessary to extend a lifetime of the metallic mold. A deformity of the products could have made from several factors which were a surface crack, a lack of the shape retention and a crack of inside of the products. Specially, the surface crack in the products was the most notably affected by the extrusion ratio.

• 한국표면공학회지
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• 제36권6호
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• pp.466-474
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• 2003

To develop a method of detecting dross in coating layer on hot-dip galvanizing steel, chemical etching behavior of the artificial coating layers with top and bottom dross were investigated. After chemical etching with the mixture of picric acid and sodium thiosulfate, each of the top and bottom dross take its distinct color, and alloy layer in coating is also observed. Defects in the coating layers of HGI(hot rolled galvanized iron), CGI(continuous galvanized steel sheet) and GA(galvannealed steel) were analysed, and methods of dross detection which can be applied to inspection process in manufacture were suggested.

• Journal of Periodontal and Implant Science
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• 제26권1호
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• pp.1-26
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• 1996

This study was performed to estimate the effects of cultured bone cell inoculated on porous type hydroxyaptite for the regeneration of the artificial alveolar bone defect. In this experiment 3 beagle dogs were used, and each of them were divided into right and left mandible. Every surgical intervention were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). To reduce the gingival bleeding during surgery, operative site was injected with Lidocaine hydrochloride(l:80,000 Epinephrine) as local anesthesia. After surgery experimental animal were feeded with soft dietl Mighty dog, Frisies Co., U.S.A.) for 1 weeks to avoid irritaion to soft tissue by food. 2 months before surgery both side of mandibular 1st premolar were extracted and bone chips from mandibular body were obtained from all animals. Bone cells were cultured from bone chips obtained from mandible with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. Porous type hydroxyapatite were immerse into the high concentrated cell suspension solution, and put 4 hours for attachin the cells on the surface of hydroxyapatite. Graft material were inserted on the artificial bone defect after 3 days of culture. Before insertion of cellinoculated graft material, scanning electronic microscopic observation were performed to confirm the attachment and spreading of cell on the hydroxyapatite surface. 3 artificial bone defects were made with bone trephine drill on the both side of mandible of the experimental animal. First defect was designed without insertion of graft material as negative control, second was filled with porous replamineform hydroxyapatite inoculated with cultured bone marrow cells as expermiental site, and third was filled with graft materials only as positive control. The size of every artificial bone defect was 3mm in diameter and 3mm in depth. After the every surgical intervention of animals, oral hygiene program were performed with 1.0% chlorhexidine digluconate. All of the animals were sacrificed at 2, 4, 6 weeks after surgery. For obtaining histological section, tissus were fixed in 10% Buffered formalin and decalcified with Planko - Rycho Solution for 72hr. Tissue embeding was performed in paraffin and cut parallel to the surface of mandibular body. Section in 8um thickness of tissue was done and stained with Hematoxylin - Eosin. All the specimens were observed under the light microscopy. The following results were obtained : 1. In the case of control site which has no graft material, less inflammatory cell infiltration and rapid new bone forming tendency were revealed compared with experimental groups. But bone surface were observed depression pattern on defect area because of soft tissue invasion into the artificial bone defect during the experimental period. 2. In the porous hydroxyapatite only group, inflammatory cell infiltration was prominet and dense connective tissue were encapsulated around grafted materials. osteoblastic activity in the early stage after surgery was low to compared with grafted with bone cells. 3. In the case of porous hydroxyapatite inoculated with bone cell, less inflammatory cell infiltration and rapid new bone formation activity was revealed than hydroxyapatite only group. Active new bone formation were observed in the early stage of control group. 4. The origin of new bone forming was revealed not from the center of defected area but from the surface of preexisting bony wall on every specimen. 5. In this experiment, osteoclastic cell was not found around grafted materials, and fibrovascular invasion into regions with no noticeable foreign body reaction. Conclusively, the cultured bone cell inoculated onto the porous hydroxyapatite may have an important role of regeneration of artificial bone defects of alveolar bone.

• 한국세라믹학회지
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• 제41권5호
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• pp.406-409
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• 2004

교류 구동 분산형 EL(ACPEL)에 사용되는 ZnS:Cu 청색 형광체를 고상 반응법으로 제조하였다. 1차 소성 후 인위적 결함을 형광체 표면에 도입함으로서 2차 소성 중에 의해 일어나는 ZnS의 상전이 및 EL 발광 휘도에 미치는 영향을 연구하였다. 즉 1차 소성된 형광체를 ball-mill 공정에서 인위적으로 표면에 defect를 형성시켜 ZnS의 저온상인 cubic으로의 전이가 용이하게 하여 EL구동하에서 발광 휘도를 증가시켰다. Ball-mill의 공정 변수로는 milling 시간과 rpm 등을 고려하여 각 조건에 따른 효과를 고찰하였으며, 발광 spectrum을 측정한 결과, 최적 조건에서 인위적인 결함을 형성하지 않은 형광체 보다 발광 휘도가 약 30% 이상 증가하였다. 또한 각기 다른 ball-mill 조건으로 합성된 형광체의 결정상을 분석하고 비교하였으며 상전이 특성에 따른 발광 휘도 변화를 고찰하였다.

• 한국정밀공학회지
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• 제32권7호
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• pp.619-625
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• 2015

There is a large interest to find reliable and automatic methods for crack detection and quantification in the railway bogie frame. The non-destructive inspection of railway bogie frame has been performed by ultrasonic and magnetic particle testing in general inspection. The magnetic particle method has been utilized in the defect inspection of the bogie frame but the grinding process is required before inspection and the dust is developed resulting from the processing. The objective of this paper is to apply the inspection method of bogie frame using infra-red thermography. The infra-red thermography system using the excitation of eddy current was performed for the defect evaluation of weld specimen inserted artificial defects. The result shows that the infra-red thermography method can detect the surface and inner defects in weld specimen for bogie frame.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 추계학술발표 개요집
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• pp.139-141
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• 1996

Among various welding parameters, the welding current which is inversely proportional to the tip-to-workpiece distance in GMAW is an essential parameter to monitor the GMAW process of horizontal fillet joints. For the case of weld defect such as overlap in horizontal fillet welding, therefore, the signal processing for process monitoring or automatic seam tracking should be modified by considering the weld pool surface geometry including the corresponding weld defect. In other words, the adequate signal processing algorithm is indispensible to improve the performance of the arc sensor. However, arc sensor algorithm already developed usually focus on weld seam tracing but do not considering the weld qualities. In this paper, various experiments were carried out to investigate the tendencies of the weld defects when weaving motion is added, and the experimental method based on 2$^n$ factorial design was proposed for deriving the mathematical model between the leg length and the various welding conditions. Moreover, a signal processing method based on the artificial neural network(Adaptive Resonance Theory) was proposed far discriminating the current signal of sound weld beads from that of weld beads with overlap. Finally, the algorithm for weld seam tracking combined with the mathematical modeling and the signal processing method was carried out to track the weld line in conjunction with the improvement of the weld qualities. The reliability of the proposed algorithms were evaluated through various experiments, which showed that the proposed algorithms could be effectively used for arc welding automation.

• 치위생과학회지
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• 제13권4호
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• pp.461-470
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• 2013

정상법랑질과 인공우식법랑질에서 불소바니쉬 도포 후의 항우식 효과를 알아보기 위하여 건전한 소의 전치를 사용하였고, 네 군으로 분류하여 실험하였다. 법랑질 표면의 재광화 및 탈회 후 결정구조의 변화를 FE-SEM으로 관찰하였고, Ca과 P의 정량적 분석은 EDS를 사용하여 측정하였다. 그 결과 불소바니쉬 도포한 경우, 재석회화로 인하여 불규칙하고 매우 거친 표면과 다공성의 구조물이 평활하고 균일한 양상으로 나타났으며, Ca 및 P의 함량이 증가되어 정상법랑질과 인공우식법랑질의 항우식 효과를 크게 증진시키는 것으로 확인되었다.

• Structural Monitoring and Maintenance
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• 제3권3호
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• pp.297-314
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• 2016

As the study of internal corrosion of pipeline need a large number of experiments as well as long time, so there is a need for new computational technique to expand the spectrum of the results and to save time. The present work represents a new non-destructive evaluation (NDE) technique for detecting the internal corrosion inside pipeline by evaluating the dielectric properties of steel pipe at room temperature by using electrical capacitance sensor (ECS), then predict the effect of pipeline environment temperature (${\theta}$) on the corrosion rates by designing an efficient artificial neural network (ANN) architecture. ECS consists of number of electrodes mounted on the outer surface of pipeline, the sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of two dimensional capacitance sensors are illustrated. The variation in the dielectric signatures was employed to design electrical capacitance sensor (ECS) with high sensitivity to detect such defects. The rules of 24-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. A feed-forward neural network (FFNN) structure are applied, trained and tested to predict the finite element (FE) results of corrosion rates under room temperature, and then used the trained FFNN to predict corrosion rates at different temperature using MATLAB neural network toolbox. The FE results are in excellent agreement with an FFNN results, thus validating the accuracy and reliability of the proposed technique and leads to better understanding of the corrosion mechanism under different pipeline environmental temperature.