• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.411-412
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• 2009

• 한국재료학회:학술대회논문집
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• 한국재료학회 2004년도 춘계학술발표대회 및 제6회 신소재 심포지엄
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• pp.90-90
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• 2004

• 한국산학기술학회논문지
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• 제3권2호
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• pp.136-140
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• 2002

정밀하고 복잡한 형상의 금속 부품을 제작하는데 사용되는 정밀주조법은 왁스형을 만드는 과정을 수작업으로 진행하므로 많은 시간과 비용이 소요되었다. 왁스형 제작공정을 개선하기 위해 쾌속조형기를 이용하는 방법을 제안하였다. SLS 형 쾌속조형기를 이용하여 캐스트폼형을 제작하고 여기에 용융된 왁스를 함침시켜 왁스형을 완성한다. 이 방법을 이용하여 스텐레스 스틸 소재의 금속 주분을 제작하였는데, 시간과 비용이 크게 절감되었으며 정밀도도 향상되었다.

• Computers and Concrete
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• 제23권1호
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• pp.11-23
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• 2019

Nowadays, the characterization of Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) tensile behavior still remains a challenge for researchers. For this purpose, a simplified closed-form non-linear hinge model based on the Third Point Bending Test (ThirdPBT) was developed by the authors. This model has been used as the basis of a simplified inverse analysis methodology to derive the tensile material properties from load-deflection response obtained from ThirdPBT experimental tests. In this paper, a non-linear finite element model (FEM) is presented with the objective of validate the closed-form non-linear hinge model. The state determination of the closed-form model is straightforward, which facilitates further inverse analysis methodologies to derive the tensile properties of UHPFRC. The accuracy of the closed-form non-linear hinge model is validated by a robust non-linear FEM analysis and a set of 15 Third-Point Bending tests with variable depths and a constant slenderness ratio of 4.5. The numerical validation shows excellent results in terms of load-deflection response, bending curvatures and average longitudinal strains when resorting to the discrete crack approach.

• Structural Engineering and Mechanics
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• 제84권5호
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• pp.605-618
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• 2022

Glass fiber reinforced polymer (GFRP) elastic gridshells consist of long continuous GFRP tubes that form elastic deformations. In this paper, a method for the form-finding of gridshell structures is presented based on the interpretable machine learning (ML) approaches. A comparative study is conducted on several ML algorithms, including support vector regression (SVR), K-nearest neighbors (KNN), decision tree (DT), random forest (RF), AdaBoost, XGBoost, category boosting (CatBoost), and light gradient boosting machine (LightGBM). A numerical example is presented using a standard double-hump gridshell considering two characteristics of deformation as objective functions. The combination of the grid search approach and k-fold cross-validation (CV) is implemented for fine-tuning the parameters of ML models. The results of the comparative study indicate that the LightGBM model presents the highest prediction accuracy. Finally, interpretable ML approaches, including Shapely additive explanations (SHAP), partial dependence plot (PDP), and accumulated local effects (ALE), are applied to explain the predictions of the ML model since it is essential to understand the effect of various values of input parameters on objective functions. As a result of interpretability approaches, an optimum gridshell structure is obtained and new opportunities are verified for form-finding investigation of GFRP elastic gridshells during lifting construction.

• 대한토목학회논문집
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• 제11권4호
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• pp.151-162
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• 1991

본 연구에서는 자료형태 및 전처리수준이 다른 위성영상자료를 이용하여 전처리수준에 따른 외부표정요소의 최적다항식형태와 위치결정정확도를 파악하고, 지상기준점의 획득방법 및 획득방법에 따른 3차원 위치결정정확도를 분석함으로서 SPOT 위성영상을 이용한 3차원 위치결정이론 및 프로그램을 개발하고 위치결정의 정확도를 향상시키는데 목적이 있다. 본 연구수행 결과 각 전처리수준에 대한 외부표정요소의 최적다항식형태(수준 1B; 15변수, 수준 1AP, 1A; 12변수)를 결정할 수 있었으며, 전처리수준에 따른 위치결정 정확도분석에서는 수준 1AP 위성사진의 정확도가 가장 좋았으나, 수치영상인 수준 1A도 유사한 정확도를 나타냄을 알 수 있었다. 또한, 지상기준점의 획득방법이 다른 수준 1A 수치영상의 3차원 위치결정 정확도를 분석한 결과, 지상기준점의 정확도가 양호한 경우 부가매개변수의 도입만으로 정확도 향상률이 큰 반면 지상기준점의 정확도가 저하되는 경우 부가매개변수의 도입만으로 정확도가 크게 향상되지 않아 조정체계에 과대오차소거이론이 포함된 동시조정이론을 적용함이 바람직함을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제14권3호
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• pp.345-364
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• 2002

The scaling laws for vibration response of anti-symmetrically laminated plates are derived by applying the similitude transformation to the governing differential equations directly. With this approach, a closed-form solution of the governing equations is not required. This is a significant advantage over the method employed by other researchers where similitude transformation is applied to the closed-form solution. The scaling laws are tested by comparing the similitude fundamental frequencies to the theoretical fundamental frequencies determined from the available closed-form solutions. In case of complete similitude, similitude solutions from the scaling laws exactly agree with the theoretical solutions. Sometimes, it may not be feasible to select the model which obeys the similarity requirement completely, therefore partial similitude is theoretically investigated and approximate scaling laws are recommended. The distorted models in stacking sequences and laminated material properties demonstrate reasonable accuracy. On the contrary, a model with distortion in fiber angle is not recommended. The derived scaling laws are very useful to determine the vibration response of complex prototypes by performing the experiment on a model with required similarities.

• 간호행정학회지
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• 제13권4호
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• pp.462-472
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• 2007

Purpose: Purpose of the this study is to define the hemodialysis noncompliance Indicators and discriminant standards levels for low Flux Hemodialysis patients and development of Hemodialysis noncompliance measurement - brief form. Method: Data was collected from 269 hemodialysis patients. To establish the hemodialysis noncompliance Indicators and to discriminate standards, 13 hemodialysis nurses and 2 nephrology doctors are participated in professional group. To verify the indicators and discriminant standards, data was ananlyzed by the canonical discriminant analysis method using by SAS 8.3 program. Result: 4 Indicators- interdialysis weight gain(IWG); average of recent 4weeks, serum phophate level, skipping of hemodialysis and hemodialysis time shortening without permission- of hemodialysis noncompliance are established and discriminant standards are developed. Discriminant ability of these 4 noncompliance indicators is 99.7%(p=.000). Hemodialysis noncompliance measurement - brief form has 96.3% discriminant accuracy. Conclusion: Hemodialysis noncompliant patients have high risks. It means that special intervention to noncompliance is needed. Also continuous and objective assessment and standards of noncompliance are needed.

• East Asian mathematical journal
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• 제33권5호
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• pp.495-509
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• 2017

With the accuracy of the nonlinearity guaranteed, plenty of time and large memory space are needed when we solve the finite element numerical solution of nonlinear partial differential equations. In this paper, we use the Group Element Method (GEM) to deal with the non-linearity of the BBM-Burgers Equation with Conservation form and perform a numerical analysis for two particular initial-boundary value (the Dirichlet boundary conditions and Neumann-Dirichlet boundary conditions) problems with the Finite Element Method (FEM). Some numerical experiments are performed to analyze the error between the exact solution and the FEM solution in MATLAB.

• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.557-564
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• 2001

The objective of he study is to record the real conditions along with the soccer ball that is, each player's ball keeping time, the number football keeping, accuracy of passing to other player, direction, etc., on a real-time basis, measure them in numbers and get necessary analyzed output as much as one needs. The study consists of the following stages: (1) Record the data by drawing through Visual Interface on a real-time basis; (2) Graphic windows to display the recorded data item by item in graphic; (3) Form windows to display the individual or team scores anytime when needed; (4) Windows to display the analyzed data in visualized form. The effect of the study is threefold: (1) It inputs all the game-related data on a real-time basis, which was impossible before and shows analyzed contents during the game enabling each tea manager o use; (2) In cse of TV broadcasting or newspaper articles, it explains objectively the situations of he game to the TV viewers or readers; (3) After the game, it provides importance information on each team's playing ability and individual player's technical improvement through data analysis.