• 한국산림과학회지
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• 제108권3호
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• pp.311-321
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• 2019

이 연구는 땅밀림위험등급을 구축하기 위하여 수행되었다. 땅밀림지의 평균산지경사는 $23.8^{\circ}$($11.8^{\circ}{\sim}37.0^{\circ}$), 땅밀림지 내에서 미세지형지의 평균사면경사는 $23.5^{\circ}$ ($10.7^{\circ}{\sim}41.5^{\circ}$)로 미소한 차이가 있는 것으로 분석되었다. 땅밀림지 및 땅밀림 재발생지에서 땅밀림지 내 등고선 간격과 땅밀림지 내 미세지형지의 등고선 간격은 5% 수준에서 유의한 결과를 나타내었다. 산사태위험등급에 포함되지 않는 땅밀림지는 전체 땅밀림지 중 1등급이 14개소(약 38.0%), 2등급이 6개소(약 16.0%), 3등급과 4등급이 각각 5개소(약 14.0%), 5등급이 16개소(약 43.0%), 산사태위험지등급 외 지역이 9개소(약 24.0%)이었다. 땅밀림지 중 산사태위험 1~5등급으로 지정되지 않은 면적 비율이 50.0% 이상인 지역은 8개소(약 22.0%), 20.0%~50.0% 이상인 지역은 18개소(약 49.0%), 20.0% 이상인 지역은 26개소(약 70.0%)이었다.

• 대한치과보철학회지
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• 제42권3호
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).

• 대한치과보철학회지
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• 제41권6호
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• pp.699-713
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• 2003

Statement of problem. Titanium is the most important material for biomedical and dental implants because of their high corrosion resistance and good biocompatibility. These beneficial properties are due to a protective passive oxide film that spontaneously forms on the surface. Purpose. The purpose of this study was to evaluate the responses of osteoblast-like cells on different surface treatments on Ti discs. Material and Methods. Group 1 represented the machined surface with no treatment. Group 2 surfaces were sandblasted with $50{\mu}m\;Al_2O_3$ under $5kgf/cm^2$ of pressure. Groups 3 and 4 were sandblasted under the same conditions. The samples were treated on a titanium oxide surface with reactive sputter depositioning and thermal oxidation at $600^{\circ}C$ (Group 3) and $800^{\circ}C$ (Group 4) for one hour in an oxygen environment. The chemical composition and microtopography were analyzed by XRD, XPS, SEM and optical interferometer. The stability of $TiO_2$ layer was studied by petentiodynamic curve. To evaluate cell response, osteoblast extracted from femoral bone marrow of young adult rat were cultured for cell attachment, proliferation and morphology on each titanium discs. Results and Conclusion. The results were as follows : 1. Surface roughness values were, from the lowest to the highest, machined group, $800^{\circ}C$ thermal oxidation group, $600^{\circ}C$ thermal oxidation group and blasted group. The Ra value of blasted group was significantly higher than that of $800^{\circ}C$ thermal oxidation group (P=0.003), which was not different from that of $600^{\circ}C$ thermal oxidation group (P<0.05). 2. The degree of cell attachment was highest in the $600^{\circ}C$ thermal oxidation group after four and eight hours (P<0.05), but after 24 hours, there was no difference among the groups (P>0.05). 3. The level of cell proliferation showed no difference among the groups after one day, three days, and seven days (P>0.05). 4. The morphology and arrangement of the cells varied with surface roughness of the discs.

• 대한치과보철학회지
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• 제41권3호
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• pp.300-318
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• 2003

Statement of problem: The success of implants depends on intimate and direct contact of implant material on bone tissue and on functional relationship with soft tissue contact. Creation and maintenance of osseointegration depend on the understanding of the tissue's healing, repairing, and remodeling capacity and these capacities rely on cellular behavior. Altering the surface properties can modify cellular responses such as cell adhesion, cell motility, bone deposition, Therefore, various implant surface treatment methods are being developed for the improved bone cell responses. Purpose: The purpose of this study was to evaluate the responses of osteoblast-like cells to surface-modified titanium. Materials and Methods: The experiment was composed of four groups. Group 1 represented the electropolished surface. Group 2 surfaces were machined surface. Group 3 and Group 4 were anodized surfaces. Group 3 had low roughness and Group 4 had high roughness. Physicochemical properties and microstructures of the discs were examined and the responses of osteoblast-like cells to the discs were investigated. The microtopography was observed by SEM. The roughness was measured by three-dimension roughness measuring system. The microstructure was analyzed by XRD, AES. To evaluate cell responses to modified titanium surfaces, osteoblasts isolated from calvaria of neonatal rat were cultured. Cell count, morphology, total protein measurement and alkaline phosphatase activities of the cultures were examined. Results and Conclusion: The results were as follows 1. The four groups showed specific microtopography respectively. Anodized group showed grain structure with micropores. 2. Surface roughness values were, from the lowest to the highest, electropolished group, machined group, low roughness anodized group, and high roughness anodized group. 3. Highly roughened anodized group was found to have increased surface oxide thickness and surface crystallinity. 4. The morphology of cells, flattened or spherical, were different from each other. In the electropolished group and machined group, the cells were almost flattened. In two anodized groups, some cells were spherical and other cells were flattened. And the 14 day culture cells of all of the groups were nearly flattened due to confluency. 5. The number of attached cells was highest in low roughness anodized group. And the machined group had significantly lower cell count than any other groups(P<.05). 6. Total protein contents showed no difference among groups. 7. The level of alkaline phosphatase activities was higher in the anodized groups than electropolished and machined groups(P<.05).

• Journal of Ecology and Environment
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• 제30권4호
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• pp.347-356
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• 2007

The structure and dynamics of Korean red pine stands established in the riparian zone were studied in the Tsang stream in Mt. Seorak National Park, in east-central Korea. Pine stands were classified into four successional stages, the initial, establishing, competitive, and stabilizing stages, based on the age distribution of a dominant tree, Pinus densiflora, the vegetation stratification, and the microtopography of the riverine environment. The stages usually corresponded to disturbance frequencies, depending on the horizontal and vertical distances from the watercourse. Stands of the initial and establishing stages lacked tree or subtree layers, or both. As stands progressed through the developmental stages, soil particle size became finer and moisture retention capacity was improved. The stand ordination reflected the developmental stage, and the species ordination differentiated species specializing in relatively dry and wet habitats. The results of the analysis of vegetation dynamics provided ecological information which will be useful for understanding the developmental processes of vegetation established in riparian zones. Species diversity indices usually increased across developmental stages, following the typical pattern for successional processes. We discuss the importance and necessity of riparian vegetation in Korea, where most riparian forests have disappeared due to excessive human land use.

• 한국정밀공학회지
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• 제17권1호
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• pp.129-137
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• 2000

In this paper, a new method of noncontact measurement has been developed for a 3 dimensional topography in semiconductor wafer, implementing a new optical probe based on the precision defocus measurement. The developed technique consists of the new optical probe, precision stages, and the measurement/control system. The basic principle of the technique is to use the reflected slit beam from the specimen surface, and to measure the deviation of the specimen surface. The defocusing distance can be measured by the reflected slit beam, where the defocused image is measured by the proposed optical probe, giving very high resolution. The distance measuring formula has been proposed for the developed probe, using the laws of geometric optics. The precision calibration technique has been applied, giving about 10 nanometer resolution and 72 nanometer of four sigma uncertainty. In order to quantitize the micro pattern in the specimen surface, some efficient analysis algorithms have been developed to analyse the 3D topography pattern and some parameters of the surface. The developed system has been successfully applied to measure the wafer surface, demonstrating the line scanning feature and excellent 3 dimensional measurement capability.

• The Korean Journal of Ecology
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• 제24권1호
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• pp.27-34
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• 2001

30년 전 석호를 간척한 후 농경을 포기하여 자연 천이가 진행되고 있는 강원도 양양군 동해안의 군개 습지에서 물 및 토양환경과 관련하여 습지 식생을 조사하였다. 이 습지에서는 해수의 유입이 차단되어 거의 담수화되었으며, 수심과 토양 유기물 함량의 공간적 변이가 다른 환경요인에 비하여 상대적으로 컸다. 다변량 분석인 detrended canonical correspondence analysis를 실시한 결과 습지의, 식물군집 구조는 주로 수심 혹은 지형의 높이와 토양 유기물함량에 의하여 결정되었다. 군개 습지에서는 다양한 정수식물 식생이 발달하였다 갈대, 산조풀, 삿갓사초, 부처꽃과 같은 종은 전체 습지에 넓게 분포하였고, 애기부들과 큰고랭이와 같은 수생식물은 수심이 깊고 낮은 지형에, 미국가막사리, 며느리배꼽과 같은 황무지 식물은 토양 유기물함량이 많은 육상에 가까운 곳에, 통보리사초, 백령풀, 곰솔, 눈양지꽃과 같은 사구식생은 높은 지형에서 발달하였다. 교란된 군개 습지를 보존, 복원하기 위해서는 자연 석호의 식생 분석으로부터 복원 원형을 도출하고 자연 습지 수위로 복원하고 바다와 수문을 연결하는 것이 중요하다고 판단되었다.

• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.498-504
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• 2014

PURPOSE. Dental implant has gained clinical success over last decade with the major drawback related to osseointegration as properties of metal (Titanium) are different from human bone. Currently implant procedures include endosseous type of dental implants with nanoscale surface characteristics. The objective of this review article is to summarize the role of nanotopography on titanium dental implant surfaces in order to improve osseointegration and various techniques that can generate nanoscale topographic features to titanium implants. MATERIALS AND METHODS. A systematic electronic search of English language peer reviewed dental literature was performed for articles published between December 1987 to January 2012. Search was conducted in Medline, PubMed and Google scholar supplemented by hand searching of selected journals. 101 articles were assigned to full text analysis. Articles were selected according to inclusion and exclusion criterion. All articles were screened according to inclusion standard. 39 articles were included in the analysis. RESULTS. Out of 39 studies, seven studies demonstrated that bone implant contact increases with increase in surface roughness. Five studies showed comparative evaluation of techniques producing microtopography and nanotopography. Eight studies concluded that osteoblasts preferably adhere to nano structure as compared to smooth surface. Six studies illustrated that nanotopography modify implant surface and their properties. Thirteen studies described techniques to produce nano roughness. CONCLUSION. Modification of dental osseous implants at nanoscale level produced by various techniques can alter biological responses that may improve osseointegration and dental implant procedures.

• 보존과학회지
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• 제26권4호
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• pp.385-395
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• 2010

이 연구는 현풍석빙고의 미기후 특성을 분석하여 손상에 영향을 미친 기후인자를 해석하고 보존환경을 평가한 것이다. 석빙고의 내부 구성부재에는 균열, 이격, 탈락, 박락, 백화, 갈색 변색, 흑색 변색 및 생물에 의한 변색이 발생하였으며, 이 중 생물에 의한 변색이 가장 높은 훼손율(24%)을 보였다. 석빙고 내부의 환경은 외부의 기상 변화에 따라 변동하나 변동폭과 일교차가 작고 일정한 온습도를 유지하는 것으로 나타났다. 이는 석빙고 전면의 산사면과 폐쇄된 입구환경이 외기를 차단하여 온습도의 변화를 최소화하였기 때문이다. 석빙고의 단열환경은 수분의 응축과 동결 현상을 방지하여 물리적 손상도를 저감하고 장빙기능을 극대화한 것으로 판단된다. 그러나 99% 이상의 높은 상대습도는 미생물의 생장을 활성화시켜 생물학적인 손상도를 높인 것으로 해석된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.199-199
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• 2022

선행 연구들을 통해 미세지형이 유역에서의 유사 유출량에 영향을 끼침을 알 수 있다. 그러나 여전히 유사-유출에 대한 미세지형의 영향이 불분명하여 유역 내 토양 침식 과정에서 미세지형적 거칠기를 고려할 때 혼란이 야기될 수 있다. 따라서, 유사유출량과 토양침식량에 대한 보다 정확한 예측 및 산정을 위해 미세지형이 토양 침식에 미치는 영향을 명확하게 하는 것이 필요하다. 본 연구에서는 Hairsine-Rose 침식 모형과 동역학파(Dynamic wave) 모형을 사용하여 강우-유출에 따른 미세지형의 유사-유출 과정을 수치적으로 모의하였다. 모의 결과에 따르면, 미세지형은 동일 강우 및 유출 조건에서도 유역 내 유사 유출량을 변화시켰다. 또한, 본 연구의 모의조건 하에서 지반이 비교적 미세토사로 구성된 경우 미세지형이 거칠수록 침식률이 증가하는 반면 지반의 토사가 대부분 굵은 입경을 가질 때는 매끄러운 지형보다 거친 미세지형에서 토양 침식률이 감소함을 확인하였다. 따라서, 지형의 미세지형 변동 정도와 토양침식률 사이에 비례 또는 반비례 관계가 형성됨을 보이고, 이러한 관계를 형성하는 과정에 입경 분포가 미치는 영향을 제시하였다. 마지막으로, 본 연구 결과를 통해 장갑화(armoring) 과정이 입경 분포뿐만 아니라 미세지형의 거칠기에 따라 유역별로 다르게 나타나는 것을 확인하였다. 따라서 유사-유출에 대한 미세지형의 영향을 적절하게 고려하기 위해 부상(Pick-up), 이류 및 퇴적 등 입경 별 퇴적물 이동이 다중 물리적으로 고려되어야 한다는 점을 강조한다. 본 연구를 통해 지표면의 미세지형적 거칠기 및 토양 입경에 대한 정확한 정보가 필요함을 알 수 있으며, 이를 충분히 고려한다면 강우 유출에 의한 토양 침식 메커니즘에 대한 이해도와 토양침식량에 대한 정량적 예측의 정확도가 향상될 것으로 예상된다.