• Composites Research
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• v.32 no.5
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• pp.258-264
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• 2019

In this paper, a progressive failure analysis method was developed using the Hashin failure criterion and crack band model. Using the failure criterion, the failure initiation was evaluated. If the failure initiation is occurred, the damage variables at each failure modes (fiber tension & compression, matrix tension & compression) was calculated according to linear softening degradation behavior and the variables are used to derive the damaged stiffness matrix. The damaged stiffness matrix is reflected to damaged material and the progressive failure analysis is continued until the damage variables to be 1 that complete failure of material. A series of processes were performed using FE commercial code ABAQUS with user defined material subroutine (UMAT). To evaluate the proposed progressive failure model, the experimental results of open hole composite laminate tests was compared with numerical result. Using digital image correlation system, the strain behavior also was compared. The proposed numerical results were coincided well with the experimental results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.311-326
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• 2024

The rapid development of neural network technology promotes the neural network model driven by big data to overcome the texture effect of complex objects. Due to the limitations in complex scenes, it is necessary to establish custom template matching and apply it to the research of many fields of computational vision technology. The dependence on high-quality small label sample database data is not very strong, and the machine learning system of deep feature connection to complete the task of texture effect inference and speculation is relatively poor. The style transfer algorithm based on neural network collects and preserves the data of patterns, extracts and modernizes their features. Through the algorithm model, it is easier to present the texture color of patterns and display them digitally. In this paper, according to the texture effect reasoning of custom template matching, the 3D visualization of the target is transformed into a 3D model. The high similarity between the scene to be inferred and the user-defined template is calculated by the user-defined template of the multi-dimensional external feature label. The convolutional neural network is adopted to optimize the external area of the object to improve the sampling quality and computational performance of the sample pyramid structure. The results indicate that the proposed algorithm can accurately capture the significant target, achieve more ablation noise, and improve the visualization results. The proposed deep convolutional neural network optimization algorithm has good rapidity, data accuracy and robustness. The proposed algorithm can adapt to the calculation of more task scenes, display the redundant vision-related information of image conversion, enhance the powerful computing power, and further improve the computational efficiency and accuracy of convolutional networks, which has a high research significance for the study of image information conversion.

• 한국노년학
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• v.31 no.4
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• pp.999-1014
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• 2011

The purpose of this study is to examine the effects of long-term care insurance(macro-system) on family relationship(micro-system)s' change based on ecosystems theory. Data come from the second(2007) and the fourth(2009) Korean Welfare Panel Study(KWPS). Experimental group is the beneficiary using long-term care insurance and the member of household in their households, and control group is the non-beneficiary not using long-term care insurance and the member of household in their households. The main findings of difference-in-difference model analysis are as follows. First, the ecosystems theory is a theory examining the correlation between long-term care insurance and family relationship. Second, the effects of long-term care insurance is not income effect but independent effect. This result shows that the meaning of family has faded away and family relationship has been weaken and that long-term care insurance has not complete characteristics as a social insurance. Thus, system reforms of long-term care insurance is highly needed for system comprehensiveness, coverage, adequacy, and service accessibility and is changed into family-friendly social policy.

• Journal of Power Electronics
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• v.11 no.2
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• pp.194-201
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• 2011

The air flow supplied to a fuel cell system is one of the most significant factors in determining fuel efficiency. The conventional method of controlling the air flow is to fix the oxygen supply at an estimated constant rate for optimal efficiency. However, the actual optimal point can deviated from the pre-set value due to temperature, load conditions and so on. In this paper, the maximum efficiency point tracking (MEPT) algorithm is proposed for finding the optimal air supply rate in real time to maximize the net-power generation of fuel cell systems. The fixed step MEPT algorithm has slow dynamics, thus it affects the overall efficiency. As a result, the variable step MEPT algorithm is proposed to compensate for this problem instead of a fixed one. The complete small signal model of a PEM Fuel cell system is developed to perform a stability analysis and to present a design guideline. For a design example, a 1kW PEM fuel cell system with a DSP 56F807 (Motorola Inc) was built and tested using the proposed MEPT algorithm. This control algorithm is very effective for a soft current change load like a grid connected system or a hybrid electric vehicle system with a secondary energy source.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.9
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• pp.315-324
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• 1983

Dynamic stability problems have been experienced with a generator connected to an infinite bus through a long transmission line. Nuclear turbine-generator units #1 and #2 at the Winsconsin Electric Power Point Baech Station were found to be dynamically unstable when one unit is isolated on one of the lines to Milwaukee or when two units are isolaed on the lines to milwaukee. Power System Stabilizers(PSS) were applied to the excitation system to provide stable operation under these conditions. Suitable settings for the PSS were predetetermined analytically by computer method and root licus analysis of an equivalent single machine-infinite bus configuration. This procedure allows graphical approach to the design of power stabilizers and serves as assynthesis procedure when the design constraints are relaxed so the the speed stabilizer is required ro provide animprovement in system damping. A simplified model of the complete exciter generator system is shown to be adequate for this type of analysis.

• Journal of Korean society of Dental Hygiene
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• v.21 no.5
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• pp.491-498
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• 2021

Objectives: This study aimed to review the definition, qualification conditions, accreditation field, and system of Japanese recognized dental hygienists. It is expected that it will be used as basic data for the system introduction of the Korean advanced dental hygienists. Methods: From May to November 2020, a literature review was conducted on Japanese dental hygienists and Japanese certified dental hygienists. Results: The lifelong education system training courses to become Japanese certified dental hygienists consisted of basic training, special training, and specific training. Each training session lasted for 15 h, and the number of training hours required to complete the course was 30 h. The training items for the field of recognition A were prevention of lifestyle disease, home care, oral function management, rehabilitation for dysphagia, prevention of diabetes, and oral management by medical and dental partnership. The training items for the field of recognition B were dentistry for the disabled, dentistry for the aged, community oral health, and oral health care. Conclusions: The Japanese recognized that dental hygienist system is valuable as a demonstration model in introducing the Korean advanced dental hygienist system.

• International Journal of Control, Automation, and Systems
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• v.6 no.5
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• pp.677-688
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• 2008

In this paper, the general problem of impedance control for a robotic manipulator with a moving flexible base is addressed. Impedance control imposes a relation between force and displacement at the contact point with the environment. The concept of impedance control of flexible base mobile manipulator is rather new and is being considered for first time using singular perturbation and new sliding mode control methods by authors. Initially slow and fast dynamics of robot are decoupled using singular perturbation method. Slow dynamics represents the dynamics of the manipulator with rigid base. Fast dynamics is the equivalent effect of the flexibility in the base. Then, using sliding mode control method, an impedance control law is derived for the slow dynamics. The asymptotic stability of the overall system is guaranteed using a combined control law comprising the impedance control law and a feedback control law for the fast dynamics. As first time, base flexibility was analyzed accurately in this paper for flexible base moving manipulator (FBMM). General dynamic decoupling, whole system stability guarantee and new composed robust control method were proposed. This proposed Sliding Mode Impedance Control Method (SMIC) was simulated for two FBMM models. First model is a simple FBMM composed of a 2 DOFs planar manipulator and a single DOF moving base with flexibility in between. Second FBMM model is a complete advanced 10 DOF FBMM composed of a 4 DOF manipulator and a 6 DOF moving base with flexibility. This controller provides desired position/force control accurately with satisfactory damped vibrations especially at the point of contact. This is the first time that SMIC was addressed for FBMM.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.689-696
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• 2007

Kinetic analysis was important to develope the biological nutrient removal process effectively. In this research, anoxic-anaerobic-aerobic system was operated to investigate kinetic behavior on the nutrient removal reaction. Nitrification and denitrification were important microbiological reactions of nitrogen. The kinetics of organic removal and nitrification reaction have been investigated based on a Monod-type expression involving two growth limiting substrates : TKN for nitrification and COD for organic removal reaction. The kinetic constans and yield coefficients were evaluated for both these reactions. Experiments were conducted to determine the biological kinetic coefficients and the removal efficiencies of COD and TKN at five different MLSS concentrations of 5000, 4200, 3300, 2600, and 1900 mg/L for synthetic wastewater. Mathematical equations were presented to permit complete evaluation of the this system. Kinetic behaviors for the organic removal and nitrification reaction were examined by the determined kinetic coefficient and the assumed operation condition and the predicted model formulae using kinetic approach. The conclusions derived from this experimental research were as follows : 1. Biological kinetic coefficients were Y=0.563, $k_d=0.054(day^{-1})$, $K_S=49.16(mg/L)$, $k=2.045(day^{-1})$ for the removal of COD and $Y_N=0.024$, $k_{dN}=0.0063(day^{-1})$, $K_{SN}=3.21(mg/L)$, $k_N=31.4(day^{-1})$ for the removal of TKN respectively. 2. The predicted kinetic model formulae could determine the predicted concentration of the activated sludge and nitrifier, investigate the distribution rate of input carbon and nitrogen in relation to the solid retention time (SRT).

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.527-538
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• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• Journal of Distribution Science
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• v.14 no.1
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• pp.85-91
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• 2016

Purpose - Recently, the importance of rapid change in business models is more and more increasing as the change of information technology environment. Therefore, a variety of business models have emerged. On the other hand, there is no company that can generate revenue. Many enterprises are still maintained while they are changing only their appearance of the business model. Business model is important in e-commerce. However, a lot of researches are targeted only in Web sites. Thus, e-commerce companies do not have the infrastructure for measuring and business models. The purpose of paper is to evaluate factors which are related with the structuring of the e-commerce success. And it proposed a financial items and non-financial items. From the perspectives of administrators and managers, the paper researches the possibility for E-Commerce Evaluation Model as a valuable criteria in measuring business model. Research design, data and methodology - The methods are taken by the classification for the type of business-to-business transactions, transactions subject, and the degree of integration and innovation capabilities. Financial and Non-financial value is used to build E-Commerce Evaluation Model. Evaluation items in Administration's perspective are composed with enhance the effectiveness of the mission, improving efficiency of the administration, and control of costs. Evaluation items in the customer's perspective were measured by customer participation and cooperation with customer Satisfaction. In the case of researching the information system's perspective, three criteria are used such as adequacy of the development process, improvement of the quality of service, and maintenance of standardized information technology. In researching for the ICT competence's perspective, evaluation items were composed of enhanced user capabilities, utilizing new technologies, and empowerment of information workers. Results - In this paper, E-Commerce Evaluation Model with financial and non-financial perspectives shows the possibility to be criteria in the case of measuring business model. Moreover, it gives the positive expectation to be successful criteria. But the research may have ambiguity in its essential concept because it cannot avoid the limitation in selecting evaluation tools from merely the model. It is impossible to exclude the possibility in omitting specific properties which may take place in actual case study. Therefore, In hereafter research, it is necessary to include actual case study research in selecting evaluation tools in order to improve the limit point. Actual measurement items which are derived from actual case study should be subdivided, and it would be more effective to complete the research. Conclusions - In rapid change in business models, there are various kinds of business models. But it is general situation that companies which adopted business models have not brought in revenue. For this reason, E-Commerce Evaluation Model is needed as an important factor for the structuring of the e-commerce success. Although it has the limitation in selecting evaluation tools from model, E-Commerce Evaluation Model proposes the implication for measuring business models as a valuable criteria.