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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.
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.
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.
김인재(Kim In Jae),김시철(Kim Si Chul),양신추(Yang Sin Choo),한상철(Han Sang Chul) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-
Lateral resistance on ballasted track acts on lateral force under train running conditions and axial force resulting from rail temperature changes in order to enhance track stability on lateral direction. Lateral ballast resistance can be varied by the shape and material quality of sleepers as well as the size and shape of gravel. It can significantly decline by loosening ballast or exposure of sleeper during construction and maintenance. Although there are many approaches to estimate the lateral ballast resistance, defining an accurate distribution of the resistance on each side of sleeper enables to design sleepers with higher lateral ballast resistance and determine maximum permissible exposure of sleeper and allowable temperature change. In this paper, we have analysed existing formulas, assessed friction coefficient on each of sleeper, compared the formulas with measured value from HSL track, and determined tolerance of those formulas. In particular, we have applied a formula that can infer the lateral resistance during design and maintenance stages to the Gyeongbu HSL track.