• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.963-971
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• 2022

Water pipeline network in local and metropolitan area is buried underground, by which it is hard to know the degree of pipe aging and leakage. In this study, assuming various sensor combinations installed in the water pipeline network, the optimal algorithm was derived by predicting the water flow rate and pressure through artificial intelligence algorithms such as linear regression and neuro fuzzy analysis to examine the possibility of detecting pipe leakage according to the data combination. In the case of leakage detection through water supply pressure prediction, Neuro fuzzy algorithm was superior to linear regression analysis. In case of leakage detection through water supply flow prediction, flow rate prediction using neuro fuzzy algorithm should be considered first. If flow meter for prediction don't exists, linear regression algorithm should be considered instead for pressure estimation.

• Journal of the Korean Data and Information Science Society
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• v.24 no.3
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• pp.533-541
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• 2013

In this study, a simple principal component analysis using Lasso is proposed. This method consists of two steps. The first step is to compute principal components by the principal component analysis. The second step is to regress each principal component on the original data matrix by Lasso regression method. Each of new principal components is computed as the linear combination of original data matrix using the scaled estimated Lasso regression coefficient as the coefficients of the combination. This method leads to easily interpretable principal components with more 0 coefficients by the properties of Lasso regression models. This is because the estimator of the regression of each principal component on the original data matrix is the corresponding eigenvector. This method is applied to real and simulated data sets with the help of an R package for Lasso regression and its usefulness is demonstrated.

• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.255-273
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• 2005

Based on the random vibration theory, a response spectrum method is developed for seismic response analysis of linear, multi-degree-of-freedom structures under multi-support excitations is developed. Various response quantities, including the mean and variance of the peak response, the response mean frequency, are obtained from proposed combination rules in terms of the mean response spectrum. This method makes it possible to apply the response spectrum to the seismic reliability analysis of structures subjected to multi-support excitations. Considering that the tedious numerical integration is required to compute the spectral parameters and correlation coefficients in above combination rules, this paper further offers simplified procedures for their computation, which enhance dramatically the computational efficiency of the suggested method. The proposed procedure is demonstrated for tow numerical examples: (1) two-span continuous beam; (2) two-tower cabled-stayed bridge by using Monte Carlo simulation (MC). For this purpose, this paper also presents an approach to simulation of ground motions, which can take into account both mean and variation properties of response spectrum. Computed results based on the response spectrum method are in good agreement with Monte Carlo simulation results. And compared with the MSRS method, a well-developed multi-support response spectrum method, the proposed method has an incomparable computational efficiency.

• Journal of the Korean Data and Information Science Society
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• v.20 no.4
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• pp.757-764
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• 2009

In discriminant analysis, we consider a special pattern which contains a block of missing observations. We assume that the two populations are equally likely and the costs of misclassification are equal. In this situation, we consider the bootstrap confidence intervals of the error rate in the circular models when the covariance matrices are equal and not equal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.567-570
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• 2000

Optimization of structure of a high-precision stamping press structure is performed by combination of Taguchi Method and finite element analysis. Too much difference in the stiffness between hydrostatic bearing linear guide and press structure is observed. Efforts are made to level up the stiffness of press structure to the level of hydrostatic bearing's. Some important design parameters are identified and discussed.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.459-475
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• 2009

This paper presents analytical methodologies for remaining life prediction of plain concrete structural components considering tension softening and size effects. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. Size effect has been accounted for by modifying the Paris law, leading to a size adjusted Paris law, which gives crack length increment per cycle as a power function of the amplitude of a size adjusted stress intensity factor (SIF). Details of tension softening effects and size effect in the computation of SIF and remaining life prediction have been presented. Numerical studies have been conducted on three point bending concrete beams under constant amplitude loading. The predicted remaining life values with the combination of tension softening & size effects are in close agreement with the corresponding experimental values available in the literature for all the tension softening models.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.8 s.145
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• pp.1158-1167
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• 2005

The purpose of this study is to examine the effect of structural properties of plain knit fabrics on the subjective textures and sensibilities of consumers. We investigated the relationship of subjective textures and sensibilities according to fiber contents of wool/rayon and stitch loop length. We made 20 plain knit fabrics, as specimens, with a combination of 5 kinds of fiber contents and 4 kinds of stitch loop length. A factor analysis showed that subjective textures are classified into 3 categories with $R^2=70.32\%$: 'surface-rough', 'drapable', 'bulky' and 'elastic' and subjective sensibilities into 3 categories with $R^2=68.12\%$: 'stable/neat', 'feminine/elegant' and 'natural/comfortable'. The fiber contents of wool/rayon had a positive and linear relation with 'surface-rough', but had a relatively non-linear one with 'bulky' and 'elastic' categories of textures, and 'feminine/elegant' of sensibilities. The stitch loop length had a linear influence on 'drapable' and 'stable/neat', but had a non-linear influence on other subjective textures and sensibilities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.274-275
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• 2006

A linear ultrasonic motor was designed by a combination of the longitudinal and bending mode. Linear ultrasonic motors are based on an elliptical motion on the surface of elastic body, such as bar or plates. The corresponding eigen-mode of one resonance frequency can be excited twice at the same time with a phase shift of 90 degrees in space and time. That is excite symmetric and anti-symmetric modes. Then it determines the thrust and speed of the motor. Linear ultrasonic motors are investigated experimentally in according to be fabricated a general classification to motor structure and material characteristic. There was the first to simulate as use of finite element analysis ANSYS 9.0. The AL-T2W8-ARM14-LEG18-ANGLE80 motor has a maxim efficiency 17 [%] under the speed 0.14 [m/s], thrust 345 [gf] and preload 280 [gf], operating frequency is 57.6 [kHz].

• Herbal Formula Science
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• v.32 no.3
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• pp.277-296
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• 2024

Objective : Dyspepsia is one of the most common ailments among Koreans, leading to a continuously expanding market for liquid digestive solutions. These products are popular due to their convenience and low risk of side effects. However, there is a lack of research on the basic prescription composition of these ingredients and their precise indications according to Korean Medicine. Methods : Drugs were selected from the Korea Pharmaceutical Information Service website (http://www.health.kr), focusing on oral and liquid products classified under the Ministry of Food and Drug Safety's category of stomach and digestive aids (category 233). Frequency analysis was conducted to determine the occurrence and combinations of herbal ingredients within each product. Additionally, the four properties and five flavors of each product were calculated using their herbal ingredient composition ratios, and Pearson correlation coefficients were employed to verify the linear relationships between the composition ratios of the ingredients. Results : A comparative analysis of 33 liquid digestive medicines revealed that Zingiberis Rhizoma was the most frequently used herb. The most common dual-herb combination was Zingiberis Rhizoma and Citri Unshius Pericarpium, and the most prevalent tri-herb combination was Zingiberis Rhizoma, Citri Unshius Pericarpium, and Cinnamomi Cortex. Pearson correlation coefficient analysis showed a strong positive correlation between the composition ratios of Zingiberis Rhizoma and Cinnamomi Cortex. The analysis of four properties and five flavors indicated that products with warm and bitter flavors were the most common. Conclusions : The most frequently used herbal combination in liquid digestive solutions was Zingiberis Rhizoma, Citri Unshius Pericarpium, and Cinnamomi Cortex. This composition is suitable for treating dyspepsia caused by cold-dampness in the digestive system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.133-141
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• 2010

MG(Microgrid) is a small power supply system located on-site that can supply both the electricity and the hot-water simultaneously. Engineering S/W is requested to construct Microgrids economically. We developed Engineering S/W that can combine DERs (Distributed Energy Resources) most economically using the linear programming and estimate of the economic. Developed S/W was programed using GAMS(General Algebraic Modeling System) and it is composed of the optimal DER combination module and forecasting module of renewable energy's output. We embody it based on MS Excel considering the user's convenience and we show its validity through a case study. We think that developed S/W will be very useful for planning MGs and energy supply.