• 한국환경복원기술학회지
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• 제13권1호
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• pp.1-13
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• 2010

This study was accomplished to identify and analyze vegetation structure of Mountainous Wetlands in Dan-yang and around area, and surveyed from September to November, 2006. 6 sites of total 16 potential Mountainous Wetlands by GIS based wetland forecasting system (Korea National Arboretum, 2006) were identified as wetlands throughout field survey by the indicators such as hydrology, soil and vegetation. By classification system of Korea National Arboretum (2006), types of wetlands were classified into 3 slope-types and 3 flat-types. To understand vegetation structure of wetlands, height, DBH (diameter at breast height), DI (Dominance Index), sociability and constancy were surveyed and the projection diagram and charts ware drawn. As results, Salix koreensis in woody plant layer and Persicaria thunbergiiin and Juncus effusus var. decipiens in herb layer were surveyed as broadly distributed species. The wetlands of Dan-yang around area were similar to those of Chung-ju around area, but the species of plants and hydrology conditions were different. This study is mainly focused on vegetation condition of Mountainous Wetlands. But, further studies on functional assessment for management and restoration of wetlands were necessary.

• 한국군사과학기술학회지
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• 제9권3호
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• pp.12-19
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• 2006

A gun barrel of infantry fighting vehicle is supported like a type of cantilever. Temperature of a gun barrel is increased by heat transfer due to the combustion of propellant charge during the firing. Thus, the muzzle of a gun barrel is deflected in accordance with its temperature and the accuracy rate is decreased by deflection of the muzzle. In this study, deflection of a gun barrel is estimated by measuring its restoration rate because measuring the deflection rate is difficult due to the vibration of the gun barrel during the firing. In order to obtain the relations between deflection rate and restoration rate of the 40mm gun barrel of Next Infantry Fighting Vehicle(NIFV) under varying temperature, measurement of deflection rate and restoration rate is carried out using 5.56mm Remington rifle barrel. Effect of the estimated deflection rate of a gun barrel of NIFV on the hit probability is also analyzed.

• 한국환경복원기술학회지
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• 제21권3호
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• pp.83-98
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• 2018

This study was conducted on rare plants distributed in Chungnam area from April, 2012 to November, 2017. The rare plant populations that are emerging are: Utricularia pilosa, Jeffersonia dubia, Iris ruthenica, Tipularia japonica, Calanthe discolor, Parasenecio pseudotaimingasa, Ranunculus kazusensis, Berchemia racemosa, Pogonia minor and Glehnia littoralis. According to the criteria of the International Union for Conservation of Nature (IUCN), plant resources in the rare species category were one important type (CR), three hazardous species (EN) and six vulnerable species (VU). As a result of analyzing characteristics of ecological environment and threats, five types of habitat types, two aquatic areas, two types of flatland and coastal sand dune distribution types were analyzed. The decreasing tendency of the rare plant populations in the surveyed area is judged to be artificial disturbance and habitat destruction rather than climate or environmental change. Considering the characteristics of habitat, conservation measures should be prepared for each population.

• Restorative Dentistry and Endodontics
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• 제42권3호
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• pp.240-252
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• 2017

The restoration of endodontic tooth is always a challenge for the clinician, not only due to excessive loss of tooth structure but also invasion of the biological width due to large decayed lesions. In this paper, the 7 most common clinical scenarios in molars with class II lesions ever deeper were examined. This includes both the type of restoration (direct or indirect) and the management of the cavity margin, such as the need for deep margin elevation (DME) or crown lengthening. It is necessary to have the DME when the healthy tooth remnant is in the sulcus or at the epithelium level. For caries that reaches the connective tissue or the bone crest, crown lengthening is required. Endocrowns are a good treatment option in the endodontically treated tooth when the loss of structure is advanced.

• The Journal of Advanced Prosthodontics
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• 제11권2호
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• pp.112-119
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• 2019

PURPOSE. Zirconia materials have been used for implant-retained restorations, but the stress distribution of zirconia is not entirely clear. The aim of this study is to evaluate the stress distribution and risky areas caused by the different design of zirconia restorations on the atrophic bone of the posterior maxilla. MATERIALS AND METHODS. An edentulous D4-type bone model was prepared from radiography of an atrophic posterior maxilla. Monolithic zirconia and zirconia-fused porcelain implant-retained restorations were designed as splinted or non-splinted. 300-N occlusal forces were applied obliquely. Stress analyses were performed using a 3D FEA program. RESULTS. According to stress analysis, the bone between the 1) molar implant and the 2) premolar in the non-splinted monolithic zirconia restoration model was stated as the riskiest area. Similarly, the maximum von Mises stress value was detected on the bone of the non-splinted monolithic zirconia models. CONCLUSION. Splinting of implant-retained restorations can be more critical for monolithic zirconia than zirconia fused to porcelain for the longevity of the bone.

• 대한치과보철학회지
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• 제47권4호
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• pp.365-375
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• 2009

연구목적: 임플란트 보철물의 유지형태 중 나사 및 시멘트 혼합 유지형의 경우 나사 풀림력 등에 영향을 주는 임플란트 구성 성분의 응력에 관한 연구가 부족하였다. 임플란트 상부 보철물의 유지형태, 즉, 시멘트 유지와 나사 유지, 그리고 이 두 가지 유지형태가 서로 연결된 혼합형의 임플란트 보철물의 응력분산의 특징들을 3차원 유한요소분석법을 이용하여 비교하고자 하였다. 연구재료 및 방법: 하악골에서 제1소구치 부위와 제1대구치 부위에 2개의 임플란트 (SS II, Osstem Co. Ltd., Seoul, Korea)를 식립한 가상의 3본 계속가공의치를 모델화하였다. 지대주 종류와 그 위치에 따라, 4가지 모형 군으로 나누어 실험하였다. 모형 1은제1대구치와 제1소구치 각각의 고정체에 모두 동일한 시멘트 유지형 지대주인 Comocta abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 합착시킨 경우이고, 모형 2는 제1대구치와 제1소구치 각각의 고정체에 모두 나사 유지형 지대주인 Octa abutment (Osstem Co. Ltd) 를 장착하여 3본 계속가공의치를 나사로 고정시킨 경우이며, 모형 3은 제1대구치의 고정체에는 시멘트 유지형 지대주인 Comocta abutment를 장착하고, 제1소구치에는 나사 유지형 지대주인 Octa abutment를 장착한 후 3본 계속가공의치를 각각 시멘트 합착 및 나사로 고정시킨 경우이다. 그리고 모형 4는 모형 3에서 각각 제1대구치 및 제1소구치의 지대주를 맞바꾼 후 3본 계속가공의치를 나사 및 시멘트로 고정시킨 경우로 나누었다. 평균저작압인 하중을 대구치 565 N과 소구치 288 N의 힘으로 설정하고 수직방향으로 중심와와 협측 교두정에, 그리고 $30^{\circ}$ 경사 하중을 협측 교두정 부위에 준 다음 골, 고정체, 지대주, 그리고 지대주 나사 등에 나타나는 von-Mises stress 양상을 평가하였다. 결과: 네 가지 모형 중 나사 유지형 지대주인 Octa abutment를 제1대구치와 제1소구치 부위에 사용한 모형 2가 전반적으로 가장 낮은 안정적인 응력 분포를 보였다. 네 가지 모형 모두 피질골 및 고정체에 미치는 응력 크기 및 분포는 거의 유사하며, 치조골에 작용하는 응력은 하중의 종류와 상관없이 주로 피질골에 집중되었다. 지대주, 지대주 나사, 그리고 보철물 나사 등에 미치는 응력 크기나 분포는 모형에 관계없이 나사 유지형인 경우가 시멘트 유지형인 경우에 비해 낮은 안정적인 값을 보였다. 제1대구치와 제1소구치의 상부 구조물의 차이에 의한 교호작용 (reciprocal action)은 상대적으로 약하였다. 모든 부위에서 중앙 수 직하중, 교두정 수직하중, 그리고 교두정 경사하중의 순으로 응력값이 증가하였다. 결론: 본 유한 요소실험의 한계내에서 나사 및 시멘트 혼합 유지형의 임플란트 보철물은 시멘트 유지형만 사용하는 경우와 비교하여 주위에 더 큰 응력을 나타내지는 않았다. 이상적인 passive fit의 가정하에서 나사 유지형의 임플란트 보철물이 본체와 주위에 가장 작은 응력을 나타내었다.

• 한국환경복원기술학회지
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• 제5권6호
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• pp.30-36
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• 2002

A 0.19 hectare natural-type wetland for stream water treatment demonstration was constructed and planted with cattails from April 2001 to May 2001. Part of its bottom surfaces adjacent to levees have a variety of slope of 1 : 4~1 : 15. Two small open water areas were installed, in which emergent plants could not grow. Removal of nutrients from stream waters was a major objective of the wetland. Waters of Sinyang Stream flowing into Kohung Estuarine Lake were pumped and funneled into the wetland. The lake had been formed by a salt marsh reclamation project and was located southern coastal region of Korean Peninsula. Volumes and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged $120.4m^3/day$ and $112.1m^3/day$, respectively. Hydraulic retention time was about 3.1 days. Average total phosphorous concentration of influent and effluent was $0.19mg/{\ell}$ and $0.075mg/{\ell}$, respectively. Total phosphorous loading rate of inflow and outflow averaged $12.05mg\;m^{-2}\;day^{-1}$ and $4.44mg\;m^{-2}\;day^{-1}$, respectively. Average total phosphorous removal rate in the wetland was $7.61mg\;m^{-2}\;day^{-1}$. Seasonal changes of phosphorous retention rates were observed. The wetland acted as effective phosphorous sinks in the initial stage of the constructed wetland.

• 한국환경복원기술학회지
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• 제13권4호
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• pp.52-64
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• 2010

This study was carried out to analyze the occurrence characteristics and the influence of forest environment factors on the debris flow of 3 national parks in korea. The results obtained from this study were summarized as follows; The total number of debris flow occurrence was 125 areas. The average length of the debris flow scar was 144m, average width was 20m. And the average area and sediment were $2,854m^2$ and $3,959m^3$ respectively. The factors influencing the debris flow were highly occurred in Metamorphic rock, mixed forest type. And also, slope gradient was $30{\sim}35^{\circ}$, aspect was NE, altitude was over 1,000m, vertical and cross slope was concave (凹), soil depth was below 15cm, stream order was 0 order. The variables of cross slope (complex), deciduous tree, soil depth (over 46cm), cross slope (concave), mixed forest type and altitude (801~1200m) in correlation analysis were significant at 1 % level. The landslide of high mountain area highly tend to change the debris flow in stream bed of torrent. The debris flow in national parks mainly occurred in high mountain area with long ridge and steep slope.

• 대한전자공학회논문지
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• 제22권1호
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• pp.1-6
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• 1985

Defocussed된 정지화상은 그 PSF(point spread fufction)이 rectangular 혹은 Gaussian등의 2차함수가 되며 이것과 입력화상과의 convolution으로 모델링 할 수 있음이. 알려져 있다. 그런데 이를 TV카메라의 주사선을 이용한 analog 방식으로 개선코자 할 경우에는 매 수평주사선에 관한한 1차원적인 처리가 가능하며 이 defocussed된 화상은 원래의 화상과 일정한 폭을 가진 펄스와의 수평방향으로 convolution된 결과로 해석 할 수 있음을 밝혔다. 또한 TV 카메라의 analog compound high pass filter를 사용한 복구 실험으로써 현저히 개선된 사진을 얻을 수 있있다.

• 한국환경복원기술학회지
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• 제8권4호
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• pp.32-42
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• 2005

To investigate the plants invasion process and dominant species in large-scale cutting slopes, slopes elapsed one year to thirteen years after construction had been selected in five counties. The obtained results are summarized as follows : The species of high appearance frequency were Alnus firma, Arundinella hirta, Miscanthus sinensi var. purpurascens, Erigeron cancdensis, Artemisia princeps var. orientalis, Oenothera odorata, Lactuca raddeana, Lactrca indica var. laciniata, Lespedeza bicolor, Youngia sonchifolia, Populus albaglandulosa, and so on. The biological type of identified vascular plants was $Ch-D_1-R_{5-e}$. In time, plant coverage was increased gradually and average of plant coverage was 1.17% in slopes which elapsed one year, 42.44% after six years, 56.67% after eight years, and 69.17% after ten years. The dominant species in the surveyed slopes were covered with Alnus firma, Artemisia princeps var. orientalis, Erigeron cancdensis, Miscanthus sinensi var. purpurascens, Arundinella hirta, Lactuca raddeana, Oenothera odorata, Boehmeria spicata, Kummerowia striata and Artemisia montana of the 59 species. The conditions of location in large-scale cutting slopes are hard to fix and germinate of seeds, and extend plant roots in the slope soil. Hence, the highly appearance species and dominance species of the area will make plant coverage quick and slope stable.