자연하천의 드론영상 활용 홍수관리 데이터 취득과 수리특성 분석

김시철(Si-Chul Kim),이종석(Jong-Seok Lee) 한국방재학회 2024 한국방재학회논문집 Vol.24 No.4

자연재해 예방은 기상이변에 따른 가뭄과 집중호우 발생에 의한 하천 이치수의 순기능 유지관리는 물론, 신속하고 정확한 예측을 통해 피해를 최소화하는 것이 필요하다. 본 연구는 이를 위한 관련 데이터를 신속⋅정확하게 수집⋅분석하는데 드론 라이다(D-LiDAR)의 지형데이터와 드론 초분광 이미지(Drone Hyperspectral Image, D-HSI) 데이터의 활용으로 수리특성을 분석하였다. HEC-RAS 모형은 본 연구의 D-LiDAR 지형 데이터와 하천기본계획의 조도계수 사용 결과와 정규식생지수 (Normalized Difference Vegetation Index, NDVI)의 추가에 의한 매개변수 적용 결과를 비교 분석하였다. 그 결과 100년 빈도 계획홍수량의 경우 평균유속은 NDVI에 의한 구역별 저항계수 적용에서 평균 2.23 m/s 감소, 홍수위는 평균 0.30 m 상승, 통수 단면적은 평균 20.17 m2 증가하였다. 이는 자연하천의 흐름특성 변화에 식생인자의 영향이 큼을 확인하였다. 본 연구에 의한 자료구축⋅분석방법은 홍수 시 신속한 하천 흐름특성의 측정⋅분석과 가뭄⋅홍수예방의 예측기법⋅경보관련 시스템 개발에 유용한 정보를 제공할 수 있을 것이다. Natural disaster prevention requires the maintenance of the proper function of river flow during droughts and heavy rains caused by abnormal weather as well as the minimization of damage via rapid and accurate predictions. This study analyzed hydraulic characteristics by utilizing D-LiDAR (Drone LiDAR) topographic data and D-HSI (Drone Hyperspectral Image) data to quickly and accurately collect and analyze related data. The HEC-RAS model was used to compare and analyze the results obtained via the D-LiDAR topographic data of this study, the roughness coefficient of the river master plan, and the results of applying parameters by adding NDVI. As a result, in the case of a 100-year frequency flood discharge, the average velocity decreased by an average of 2.23 m/s when applying the resistance coefficient by area, based on NDVI. Moreover, the flood level increased by an average of 0.30 m, and the cross-sectional area of the flow capacity increased by an average of 20.17 m2. These results confirms that vegetation has a significant influence on the flow characteristics of natural streams. Hence, the data construction and analysis method used in this study can provide useful information regarding the rapid measurement and analysis of river flow characteristics during floods as well as and the development of prediction techniques and warning-related systems for drought and flood prevention.

측정 방법에 따른 CAD/CAM으로 제작한 3본 브리지의 내면 적합도 비교

김시철(Si-Chul Kim) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.10

본 연구에서는 치과용 CAD/CAM 시스템을 이용하여 연질의 Co-Cr 블록을 가공하여 적합도를 측정하였고 적합도 측정 방법은 인상재를 이용한 간접법(IM: Indirect Method)과 시편을 절단한 직접법(DM: Direct Method)을 이용하여 두 방법간의 적합도 차이가 있는지 비교분석 하고자 하였다. 2가지 형태의 변연(knife, chamfer)을 3-unit 주모형을 6개씩 12개를 제작하였고 CAD/CAM 시스템을 이용하여 Co-Cr보철물을 제작하였다. 제작된 시편은 내면 적합도를 간접법(DM)과 직접법(IM)으로 측정하였다. 측정부위는 보철물의 변연 부분과 지대치 변연 부분의 틈을 marginal opening(MO), 지대치 변연에서부터 상방 400 μm에서 거리를 internal gap(IG)로 측정하였다. 지대치 축면은 3부분의 측정 평균값을 axial gap(AG), 교합면의 중앙부위 3부분의 측정 평균값을 occlusal gap(OG)로 측정하였다. 측정방법과 변연 형태에 따른 이원배치분산분석을 실시하였으며 각각의 평균값들은 일원배치분산분석과 Dancan’s 사후 검정을 실시하였다. 전체적인 평균 적합도는 126 μm이하의 값을 보였으며, 두 측정방법 (DM, IM)에 따른 적합도의 차이는 없었다. 또한, 연질의 Co-Cr 블록 가공을 통한 치과용 보철물의 적합도는 임상적 허용이 가능하였다. This study examined the internal fit of a soft Co-Cr block fabricated using a dental CAD/CAM system by comparing the measured fit determined by two evaluation methods: indirect method (IM) using an impression material, and direct method (DM) using the cut specimen. Two sets of six 3-unit bridge master models were fabricated with two types of margins (knife, chamfer); the CAD/CAM system was used to produce a Co-Cr prosthesis. The resulting specimen was evaluated for the internal fit using either the indirect method (IM) or the direct method (DM). The measurement sites were defined as marginal opening (MO) the space between the tip of the prosthesis and margin of abutment and internal gap (IG) the distance from the margin of abutment to a point 400 μm above. For the axial plane of the abutment, the mean of triplicate measurements of three areas was defined as the axial gap (AG), and the center three areas of the occlusal surface were defined as the occlusal gap (OG). Two-way ANOVA was performed for comparative analysis according to the fit evaluation method and margin type. One-way ANOVA and Duncans post-hoc tests were performed for the comparative analysis of different mean values. The mean overall fit was ≤126 μm with no significant variation across the measured sites according to the evaluation method. There was no difference in the fit between the two measurement methods (DM, IM). Our results indicate that the fit of a dental prosthesis through soft Co-Cr block processing is clinically acceptable.

현수교 보강형 가설중 내풍 안정성에 대한 연구 : 이순신대교 보강형 가설 중심으로

김시철(Kim Si Chul),김성호(Kim Sung Ho),박주택(Park Joo Taek),정봉교(Jeong Bong Gyo),김재홍(Kim Jae Hong) 대한토목학회 2010 대한토목학회 학술대회 Vol.2010 No.10

OFDM통신 시스템에서 PAPR의 감소를 위한 사전-스크램블링 기법

김시철(Si Chul Kim),현덕수(Deok Soo Hyun),최광돈(Kwang Don Choi),박상규(Sang Kyu Park) 한국통신학회 2003 한국통신학회 학술대회논문집 Vol.2003 No.7

수작업과 CAD-CAM에 의해 제작된 3-unit 브리지 왁스 패턴의 적합도 비교

김시철(Si-Chul Kim),배지영(Ji-Young Bae),이해형(Hae-Hyoung Lee) 대한치과재료학회 2010 대한치과재료학회지 Vol.37 No.4

The purpose of this study was to compare the marginal and internal fit of 3-unit bridge wax patterns fabricated by manual wax-up or CAD-CAM techniques. A three-unit bridge model was prepared with die stone and two types of margin, knife and chamfer were applied to the abutment teeth. The fit of wax patterns was measured from mesiodistally sectioned of bridge model with wax patten by microscopic examination. Gap dimensions of wax patterns prepared in this study were <100 ㎛, which were within clinically acceptable level, except for occlusal gap of CAD-CAM wax pattern. Wax patters with knife margin produced better adaption accuracy than does those with chamfer margin. Axial gap adaption was very good regardless of margin type. Overall, the level of accuracy of wax pattern produced by manual technique was better than that of CAD-CAM technique.

현수교 주케이블 래핑와이어의 장력감소에 관한 연구

김시철(Kim, Si Chul),이민재(Lee, Min Jae),문종훈(Moon, Jong Hoon),윤자걸(Yoon, Jah Geol) 대한토목학회 2012 대한토목학회 학술대회 Vol.2012 No.10

콘크리트궤도용 고속분기기 성능평가

김시철(Si-Chul Kim),김만철(Man-Cheol Kim),황광하(Kwang-Ha Hwang),배상환(Sang-Hwan Bae) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7

In line with current speed-up of railroad, a slab track has been increasingly adopted in a bid to secure the safety of track structure as well as to reduce the maintenance cost, and furthermore, the need for commercialization of domestically-developed swing-nose crossing turnout on slab track has been on the rise. For commercialization of swing-nose crossing turnout on slab which was developed in Korea, a technical and systematic performance evaluation system, considering local environment, shall be established and then the performance evaluation shall be accordingly implemented. This paper was intended to summarize the performance evaluation system, referring to the data available at home and abroad and the results of performance evaluation for domestically-developed swing-nose crossing turnout on slab track carried out to date based on that system. A performance evaluation system comprises the technical requirement appropriateness evaluation(component performance evaluation and design verification), laboratory test and on-site test. For domestically-developed swing-nose crossing turnout on slab track, appropriateness evaluation and laboratory test have been completed and the on-site test of those installed on the 2nd phase of Kyung-Bu HSR is underway now.

치과 CAD/CAM용 크롬-코발트 연질 금속블록으로 제작한 3-unit 브리지의 변연 적합도

김시철(Si-Chul Kim),이해형(Hae-Hyoung Lee) 대한치과재료학회 2016 대한치과재료학회지 Vol.43 No.2

Dental CAD/CAM technology have been introduced to the field of dental laboratory processing for fabrication of metallic prosthesis in order to substitute traditional lost-wax technique. The purpose of this study was to investigate the internal adaptation accuracy of 3-unit fixed partial denture (bridge) made of Co-Cr soft metal block with dental CAD/CAM systems. A three-unit bridge model was prepared with two types of margin (knife and chamfer). The master models were used to fabricate three-unit bridge with soft metal block by CAD/CAM system. Internal fit was measured by a replica technique at the areas of marginal opening (MO), marginal gap (MG) of maximum curvature area, axial gap (AG), and occlusal gap (OG). For MO gap, bridge with chamfer margin recorded a significantly higher adaptation accuracy than bridge with knife margin, however, MG gap with knife was significantly smaller than MG gap with chamfer (P<0.05). The mean gap dimensions of all area measured were under 120 ㎛. Overall results indicate that the CAD/CAM fabricating method for metal restorations can substitute the conventional lost-wax technique in terms of marginal accuracy.

3D 프린팅법으로 제작한 브리지 패턴의 내면 적합도

김시철(Si-Chul Kim),한민수(Min-Soo Han),최범진(Beom-Jin Choi),이청재(Chung-Jae Lee),이해형(Hae-Hyoung Lee) 대한치과재료학회 2014 대한치과재료학회지 Vol.41 No.4

The purpose of this study was to compare the marginal and internal fit of resin bridge patterns fabricated by a 3D printer system. Three type bridge models (2-, 3-, 4-unit bridge) were prepared with die stone and two types of margin, knife or chamfer were applied to the abutment teeth. The gypsum models were used to fabricate resin patterns by a 3D printer. The printed resin patterns were fixed to their master dies using zinc phosphate cement and then invested with dental stone in a box. The resin patterns were cut mesiodistally using a diamond saw and further polished with #1000 SiC paper. Internal fit of the bridge patterns was measured at areas of marginal opening (MO), marginal gap (MG) of maximum curvature area, axial gap (AG), and occlusal gap (OG) from the images of gaps captured by a stereoscope with CCD camera. Overall, mean gap dimensions of the resin patterns prepared in this study were <155 μm, except for OG. The 3D bridge patterns with chamfer margin showed a significantly higher adaptation accuracy at MO, but those with knife margin showed a better accuracy at MG. Internal fit of all patterns at AG were found to be <50 μm.

혼파초지에서 지역별 건물수량과 하고일수 간 관계

오승민,김문주,팽경룬,이배훈,김지융,베페카두,김시철,김경대,김병완,조무환,성경일,Oh, Seung Min,Kim, Moonju,Peng, Jinglun,Lee, Bae Hun,Kim, Ji Yung,Chemere, Befekadu,Kim, Si Chul,Kim, Kyeong Dae,Kim, Byong Wan,Jo, Mu Hwan,Sung, Kyung Il 한국초지조사료학회 2018 한국초지조사료학회지 Vol.38 No.1

본 연구는 혼파초지 수량예측모형에서 기후특성이 뚜렷한 지역의 자료 제거 및 지역별 구분을 통해 건물수량과 하고일수 간 상관관계를 검토하였다. 데이터세트는 총 582점으로 11개 지역으로 분류되며 혼파조합은 총 41가지였다. 변수에서 반응변수는 건물수량 이었으며 설명변수는 하고일수를 포함한 5가지의 기상변수를 이용하였다. 통계방법은 산점도, 기술통계량 및 상관분석을 거쳐 다중회귀분석을 통해 건물수량과 하고일수 간 상관관계를 확인하였다. 산점도 분석 결과 데이터세트를 지역별로 구분하였을 때 9개 지역 중 7개에서 건물수량과 하고일수 간 부(-)의 상관관계가 나타나 지역을 구분할 필요가 있었으며 대표본 근사이론을 적용할 수 있었던 5개 지역(화성, 수원, 대전, 시흥 및 광주)을 선정하였다. 5개 지역의 상관분석 결과 3개 지역(화성, 수원 및 시흥)에서, 다중회귀분석결과 화성에서 건물수량에 대한 하고일수의 효과가 부(-)로 나타났다. 따라서 혼파초지의 건물수량에 대한 하고일수의 상관관계는 지역별로 구분하였을 때 풀사료 생산이론과 일치하여 수량예측모형의 정밀도를 높일 수 있을 것으로 판단하였다. Yield prediction model for mixed pasture was developed with a shortage that the relationship between dry matter yield (DMY) and days of summer depression (DSD) was not properly reflected in the model in the previous research. Therefore, this study was designed to eliminate the data of the regions with distinctly different climatic conditions and then investigate their relationships DMY and DSD using the data in each region separately of regions with distinct climatic characteristics and classify the data based on regions for further analysis based on the previous mixed pasture prediction model. The data set used in the research kept 582 data points from 11 regions and 41 mixed pasture types. The relationship between DMY and DSD in each region were analyzed through scatter plot, correlation analysis and multiple regression analysis in each region separately. In the statistical analysis, DMY was taken as the response variable and 5 climatic variables including DSD were taken as explanatory variables. The results of scatter plot showed that negative correlations between DMY and DSD were observed in 7 out of 9 regions. Therefore, it was confirmed that analyzing the relationship between DMY and DSD based on each region is necessary and 5 regions were selected (Hwaseong, Suwon, Daejeon, Siheung and Gwangju) since the data size in these regions is large enough to perform the further statistical analysis based on large sample approximation theory. Correlation analysis showed that negative correlations were found between DMY and DSD in 3 (Hwaseong, Suwon and Siheung) out of the 5 regions, meanwhile the negative relationship in Hwaseong was confirmed through multiple regression analysis. Therefore, it was concluded that the interpretability of the yield prediction model for mixed pasture could be improved based on constructing the models using the data from each region separately instead of using the pooled data from different regions.