• 한국멀티미디어학회논문지
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• 제11권7호
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• pp.1025-1034
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• 2008

본 논문은 모바일 디바이스에 GML을 효율적으로 공급하고 가시화하기 위한 맵 분할 및 캐싱 기법을 제안하고, 이를 적용한 GridGML을 구현한다. GridGML은 GML의 가장 큰 단점인 가중성을 극복하기 위해 GML 속성들 중 맵 가시화 핵심 부분만을 추출 및 클래스 객체로 경량화 한다. GridGML은 모바일 디바이스에 실시간으로 맵을 공급하고 가시화하기 위해 모바일 디바이스 가시영역을 기준으로 분할 관리하며, 분할 영역은 전송상의 이점을 위해 바이트화 하여 전송한다. 그리고 모바일 디바이스에서는 수신된 분할영역을 조합한 후 모바일 디바이스에서 표현하는 영역에 따라 4개의 가시영역으로 재분할 및 가시화를 한다. 또한, 자원의 효율적 운영을 위해 이전에 전송받은 맵의 중복성을 고려한 캐싱 알고리즘을 적용하여 관리한다. 맵의 객체 밀집 지역에 대해서는 전송시간의 지연을 방지하기 위해 적응적 맵 분할 메커니즘을 제안하여 전송시간을 일정함을 유지한다.

• 한국정보통신학회논문지
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• 제24권1호
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• pp.91-99
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• 2020

영상 감지 시스템의 기반 기술인 그림자 제거기술의 경우 실시간 영상처리는 계산의 복잡도가 높아 처리속도가 저하되고, 명도 차이만으로 그림자를 제거하기 때문에 조명이나 빛에 민감하다는 문제점이 있다. 따라서 본 논문에서는 기존 시스템의 문제점을 해결하기 위해 가중치 적용 부분을 제거하여 계산의 복잡도를 낮추어 실시간성을 향상시켰다. 또한 수직 히스토그램을 이용해 그림자 인식률을 향상시킬 수 있는 그림자 제거 알고리즘 기반의 영상 감지 시스템을 설계 및 평가하였다. 평가 결과 기존 영상 감지 시스템에 비해 평균 속도가 약 5.6ms, 검출률이 약 5.5%p 향상된 것을 확인하였다.

• Structural Monitoring and Maintenance
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• 제9권1호
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• pp.29-42
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• 2022

In mountainous areas of China, concrete poles with connectors are widely employed in power transmission due to its convenience of manufacture and transportation. The bearing capacity of the poles must have degenerated over time, and most of the steel connectors have been corroded. Carbon fiber reinforced polymer (CFRP) offers a durable, light-weight alternative in strengthening those poles that have served for many years. In this paper, the bearing capacity and failure mechanism of CFRP sheet strengthened existing reinforced concrete poles with corrosion steel connectors were investigated. Four poles were selected to conduct flexural capacity test. Two poles were strengthened by single-layer longitudinal CFRP sheet, one pole was strengthened by double-layer longitudinal CFRP sheets and the last specimen was not strengthened. Results indicate that the failure is mainly bond failure between concrete and the external CFRP sheet, and the specimens fail in a brittle pattern. The cross-sectional strains of specimens approximately follow the plane section assumption in the early stage of loading, but the strain in the tensile zone no longer conforms to this assumption when the load approaches the failure load. Also, bearing capacity and stiffness of the strengthened specimens are much larger than those without CFRP sheet. The bearing capacity, initial stiffness and elastic-plastic stiffness of specimen strengthened by double-layer CFRP are larger than those strengthened by single-layer CFRP. Weighting the cost-effective effect, it is more economical and reasonable to strengthen with single-layer CFRP sheet. The results can provide a reference to the same type of poles for strengthening design.

• 소성∙가공
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• 제33권2호
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• pp.103-111
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• 2024

With the increasing global interest in carbon neutrality, the automotive industry is also transitioning to the production of eco-friendly cars, specifically electric vehicles. In order to achieve comparable driving distances to internal combustion engine vehicles, the application of high-capacity battery packs has led to an increase in vehicle weight. To achieve light-weighting and durability requirements of automotive components simultaneously, there is a demand for research on the application of Ultra-High Strength Steel (UHSS). However, when manufacturing chassis components using UHSS, there are challenges related to fracture defects due to lower elongation compared to regular steel sheets, as well as spring-back issues caused by high tensile strength. In this study, a simulated specimen that is not affected by the property changes of four materials was designed to improve formability of the rear cross member, which is the most challenging automotive chassis component. The influence and correlation of material-specific variables were analyzed through finite element analysis (FEA) for each material with tensile strength of 440, 590, 780, and 980 MPa grades, resulting in the development of a predictive equation. To validate the equation, the simulated specimens of 980 MPa grade were produced from the test molds. Then the reliability of the FEA and predictive equation was verified with measured specimen data using a 3D scanner. The results of this study can be proposed to improve the formability of UHSS chassis components in future researches.

• Applied Microscopy
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• 제38권3호
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• pp.259-264
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• 2008

소취 및 소독제로서 사용되어온 안정화 이산화염소($S-ClO_2$)의 조직에 대한 부패억제 효과를 확인하고자 본 연구를 수행하였다. 실험을 위해 8주령 SD계 흰쥐 콩팥(kidney)을 사용하였고, 안정화 이산화염소를 처리하지 않은 대조군과, 안정화 이산화염소의 분말과 수용액을 처리한 실험군으로 구분하여 광학 및 전자현미경으로 관찰하였다. 광학현미경 관찰 결과, 부패양상은 시간경과에 따라 토리, 보우만주머니 및 세뇨관을 구성하는 세포의 핵과 세포사이 경계가 불분명해지며, 세뇨관의 경우 신장되었다가 결국에 수축되었다. 대조군의 1일군부터 괴사(necrosis)가 시작되어 3일군 이후는 전체적인 조직 괴사로 형태를 구별하기 어려웠다. 실험군에서 3일군의 경우, 조직의 전반적 형태와 괴사정도가 대조군의 1일군과 유사하였다. 전자현미경 관찰 결과, 시간경과에 따라 세포소기관 및 미토콘드리아의 부분적 붕괴로 시작되어 결과적으로 모든 세포내소기관이 붕괴되었다. 대조군의 1일군에서 세포소기관의 부분적 붕괴가 관찰되었으며, 실험군의 3일군에서 세포소기관 및 미토콘드리아의 부분적 붕괴 현상이 관찰되었다. 대조군의 3일군 이후에서는 세포소기관을 구별할 수 없었다. 이상의 연구 결과에서 $37^{\circ}C$, 습도 $80{\pm}5%$에서 안정화 이산화염소($S-ClO_2$)가 부패와 변성을 억제하는 부패억제제로서 효과가 있고, 억제 정도는 실험군의 3일군이 대조군의 1일군에 해당하는 것으로 보아 최소 2일 정도의 부패억제 효과가 있는 것으로 확인되었다.

• Journal of Korean Neurosurgical Society
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• 제46권5호
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• pp.479-483
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• 2009

Objective : A mouse model of spinal cord injury (SCI) could further increase our basic understanding of the mechanisms involved in injury and repair of the nervous system. The purpose of this study was to investigate whether methods used to produce and evaluate photochemical graded ischemic SCI in rats, could be successfully adapted to mice, in a reliable and reproducible manner. Methods : Thirty female imprinting control region mice (weighting 25-30 g, 8 weeks of age) were used in this study. Following intraperitoneal injection of Rose bengal, the translucent dorsal surface of the T8-T9 vertebral laminae of the mice were illuminated with a fiber optic bundle of a cold light source. The mice were divided into three groups; Group 1 (20 mg/kg Rose bengal, 5 minutes illumination), Group 2 (20 mg/kg Rose bengal, 10 minutes illumination), and Group 3 (40 mg/kg Rose bengal, 10 minutes illumination). The locomotor function, according to the Basso-Beattie-Bresnahan scale, was assessed at three days after the injury and then once per week for four weeks. The animals were sacrificed at 28 days after the injury, and the histopathology of the lesions was assessed. Results : The mice in group 1 had no hindlimb movement until seven days after the injury. Most mice had later recovery with movement in more than two joints at 28 days after injury. There was limited recovery of one joint, with only slight movement, for the mice in groups 2 and 3. The histopathology showed that the mice in group 1 had a cystic cavity involving the dorsal and partial involvement of the dorsolateral funiculi. A larger cavity, involving the dorsal, dorsolateral funiculi and the gray matter of the dorsal and ventral horns was found in group 2. In group 3, most of the spinal cord was destroyed and only a thin rim of tissue remained. Conclusion : The results of this study show that the photochemical graded ischemic SCI model. described in rats, can be successfully adapted to mice, in a reliable and reproducible manner. The functional deficits are correlated an increase in the irradiation time and, therefore, to the severity of the injury. The photothrombotic model of SCI, in mice with 20 mg/kg Rose bengal for 5 minutes illumination, provides an effective model that could be used in future research. This photochemical model can be used for investigating secondary responses associated with traumatic SCI.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.184-189
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• 2018

최근에 안전기준과 환경규제 강화의 증대로 인해, 차체의 경량화에 대한 연구가 지속적으로 증가하고 있다. 고강도강의 응용은 가장 보편화 된 차체 경량화의 효과적인 방법 중에 하나이다. TWB(Tailor Welded Blank)는 다양한 두께와 용접을 사용하여 부분적인 강도와 경량화를 만족시키는 주요한 공법으로 활용되고 있다. 그러나 추가적인 용접공정으로 인해 판재간의 용접성이 중요하고 용접부에 대한 품질관리가 중요하다. 이점을 개선하기 위해, TRB(Tailor Rollded Blank)공법이 제안되었다. TRB는 롤러 압력을 조절하여 판재의 두께를 다르게 하고, 용접을 사용하는 TWB 공법보다 추가적인 용접공정이 없기 때문에 생산 비용적인 측면에서 훨씬 더 효율적이다. 본 연구에서는 Blank의 압연 영향을 조사하기 위해 스탬핑용 고강도강 TRB 판재의 성형성을 분석하였다. 성형성을 분석하기 위해, TRB 판재에서 0.8 mm, 1 mm의 두께를 갖는 부분을 채취하여 시험하였다. 시편에 새겨진 그리드마킹의 변형도를 분석하여 변형률을 조사하였고, 0.8 mm와 1.0 mm의 두께를 갖는 TRB 시편으로 Erichsen 시험을 한 후에 FE분석을 활용하여 성형성과 고유진동수를 비교하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권6호
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• pp.557-564
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• 2000

The bone graft materials can be grossly divided into autogenous bone, allogenic bone, xenogenic bone, and alloplastic material. Much care was given to other bone graft materials away from autogenous bone due to its additional operation for harvesting, delayed resorption and limitation of quantity. Demineralized freeze-dried bone(DFDB) and hydroxyapatite are the representatives of bone graft materials. As resorbable hydroxyapatite is developed in these days, the disadvantage of nonresorbability can be overcome. So we planned to study on the strength and the bone formation at the rats calvarial defects of DFDB graft and those of the composite graft with DFDB and resorbable hydroxyapatite. We used the 16 male rats weighting range from 250 to 300 gram bred under the same environment during same period. After we made the 6mm diameter calvarial defect, we filled the DFDB in 8 rats and DFDB and resorbable hydroxyapatite in another 8 rats. We sacrificed them at the postoperative 1 month and 2 months with the periostium observed. As soon as the specimens were delivered, we measured the compressive forces to break the normal calvarial area and the newly formed bone in calvarial defect area using Instron(Model Autograph $S-2000^{(R)}$, Shimadzu, Japan). The rest of the specimens were stained with H&E(Hematoxylin & Eosin) and evaluated with the light microscope. So we got the following results. 1. In every rats, there was no significant difference between the measured forces of normal bone area and those of the bone graft area. 2. In 1 month, the measured forces at DFDB graft group were higher than those of the DFDB and resorbable hydroxyapatite composite graft group(P<0.05). 3. In 2 months, there was no significant differences between the measured forces of DFDB graft group and those of the DFDB and resorbable hydroxyapatite composite graft group. 4. In lightmicroscopic examination, most of the grafted DFDB were transformed into bone in 1 month and a large numbers of hydroxyapatite crystal were observed in DFDB and resorbable hydroxyapatite composite graft group in 1 month. 5. Both group showed no inflammatory reaction in 1 month. And hydroxyapatite crystals had a tight junction without soft tissue invagination when consolidated with newly formed bone. 6. In both groups, newly formed bone showed the partial bone remodeling and the lamellar bone structures and some of reversal lines were observed in 2 months. From the above results, it is suggested that DFDB and resorbable hydroxyapatite composite graft group had a better resistance to compressive force in early stage than DFDB graft group, but there would be no significant difference between two groups after some period. And it is suggested that the early stage of bone formation procedure of DFDB and resorbable hydroxyapatite composite graft group was slight slower than that of DFDB graft group, but there would be no significant difference between two groups after some period.

• 대한소아치과학회지
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• 제27권2호
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• pp.333-343
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• 2000

본 연구의 목적은 성견 치아에서 ferric sulfate로 치수절단술을 시행하고 상부 이장재의 영향을 최소화한 후에 잔존 치수 조직 반응을 formocresol을 사용한 군과 조직병리학적으로 비교 평가하는 것이다. 생후 $6\sim7$개월, 체중 $10\sim12Kg$ 정도의 성견 5마리의 전치 40개에 5급 와동을 형성하여 치수절단술을 시행하였다. 치수를 formocresol과 ferric sulfate를 이용하여 복조를 시행하고 IRM으로 밀봉하였다. 실험동물은 3일, 1주, 2주, 4주, 그리고 8주 후에 관류 고정하여 희생되었으며, 표본을 광학현미경으로 관찰하여 다음과 같은 결론을 얻었다. 1. Ferric sulfate군과 formocresol군 모두에서 치수절단술 후에 염증 반응을 보였지만 ferric sulfate군에서 현저히 감소된 염증 양상과 빠른 치수조직 회복소견을 보였다. 2. Ferric sulfate군에서 치수절단술 후 치수 측벽의 상아모세포의 배열 양상은 초기에는 치관부 1/3에 불규칙한 배열양상을 나타내었지만 2주 후부터는 대체로 회복된 양상을 보였다 그러나 formocresol군에서는 불규칙한 배열양상이 실험기간 동안 지속되었다. 3. 치근을 따라 넓고 길게 형성된 수복상아질층이 formocresol군 8주의 1개 치아에서 나타났으며 상아질교의 형성은 ferric sulfate군 8주의 2개 치아에서 관찰할 수 있었다.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.170-179
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• 2000

The rh-BMP-4 is a subgroup of TGF-${\beta}$ superfamily. The application of rh-BMP in alveolar bony defect was reported to new alveolar bone and new cementum formation. For minimized complications following tooth replantation, a operator must replant a tooth fast at the pertinent position. This study was to evaluate the effect of rh-BMP-4 on periodontal regeneration and root resorption following tooth replantation in rats. The 50 Sprague-Dawley rats weighting about 130gm were used in this study. The animals were divided into three groups. Group 1 ; immediate replantation after extraction : Group 2 ; replantation stored teeth extraction of first molar, the removal of periodontal ligament with collagenase, and etching with citric acid : Group 3 ; replantation stored teeth with treated rh-BMP-4 in mesial root. Experimental animals were sacrificed 3, 7, 14 days after replantation by heart infusion. The maxillae were removed, fixed, demineralized, dehydrated, infiltrated and embedded with JB-4 mixture. For light microscopic observation, 5 micron sections were cut and stained with toluidine blue. The results of this study were as follows : 1. After experimental 3 days, all groups were observed dead space between periodontum and root. 2. After experimental 7 days, group 1 and group 3 were observed filling periodontal fibers between alveolar bone and root but group 2 were not. 3. After experimental 7 days, group 3 were observed appearance of attached cementoblast like cell on root surface. Group 1 were observed regular arrangement of fibroblasts and collagen fibers at ${\times}400$ observation. 4. After experimental 14 days, all group were observed filling periodontal fibers between alveolar bone and root. Group 1 were observed normal arrangement of periodontal fibers. Group 3 were observed less abnormal arrangement of periodontal fibers. Group 2 were not observed functional normal arrangement of periodontal fibers. 5. After experimental 14 days, group 2 and 3 were observed several root resorption and irregular root surface but group 1 were not. These results suggest that the rh-BMP-4 can stimulate cementogenesis and enhance to attach collagen fibers.