• Journal of Applied Reliability
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• v.11 no.2
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• pp.177-186
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• 2011

Traditionally, one uses a method of straight-line recognition to evaluate quality of product or service. One can satisfy with the product or service if their physical requirement of are met some criterions and can not satisfy them if their physical requirement are not met. Kano, et al(1984) introduce two dimensional Quality model to evaluate quality of product or service. They classify Quality Characteristic of product and service to three categories; satisfying quality, attractive quality, expected quality. In this paper, 17 evaluation features in 6 categories of smart-card are obtained from Focus-interview and Brainstorming and classified into 3 categories of quality model by Kano's two dimensional method. This classification is expected to provide a guideline for evaluation of smart-card.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.93-102
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• 1994

This paper, presents SECRET(SEC REliability Tool), which predicts reliability problems related to the hot-carrier and electromigration effects on the submicron MOSFETs and interconnections. To simulate DC and AC lifetime for hot-carrier damaged devices, we have developed an accurate substrate current model with the geometric sensitivity, which has been verified over the wide ranges of transistor geometries. A guideline can be provided to design hot-carrier resistant circuits by the analysis of HOREL(HOT-carrier RFsistant Logic) effect, and circuit degradation with respect to physical parameter degradation such as the threshold voltage and the mobility can also be expected. In SECRET, DC and AC MTTF values of metal lines are calculated based on lossy transmission line analysis, and parasitic resistances, inductances and capacitances of metal lines are accurately considered when they operate in the condition of high speed. Also, circuit-level reliability simulation can be applied to the determination of metal line width and-that of optimal capacitor size in substrate bias generation circuit. Experimental results obtained from the several real circuits show that SECERT is very useful to estimate and analyze reliability problems.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.88-97
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• 1993

Electrostatic Discharge(ESD) is one of the major reliability, issues for today's VLSI production. Since the gate oxide with a thickness of 100~300$\AA$ is vulnerable to several thousand volt of ESD surge, it is necessary to control the ESD events and design an efficient protection circuit. In this paper, physical mechanism of the catastrophic ESD damage is investigated by transient analysis based upon Human Body Model(HBM). Using two-dimensional electrothermal simulator, we study the failure mechanism of the output protection devices by ESD and discuss the design issues for the optimun protection network.

• The Journal of Korean Physical Therapy
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• v.26 no.2
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• pp.82-89
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• 2014

Purpose: This study was conducted in order to develop an instrument for the Korean Osteoarthritis Impact Measurement scale (KAIMS) in hip and knee osteoarthritis patients. Methods: A sample of 426 subjects was recruited in Ulsan metropolitan city (six hospitals and clinics) and Andong city (five hospitals and clinics) from June 2010 to May 2011. Item internal consistency and item discriminant validity were analyzed on the item-level, and floor (%) and ceiling (%) effect were analyzed on the scale-level. Exploratory factor analysis was performed for construction of items in the KAIMS instrument; confirmative factor analysis was also performed to test the fit of the model. Results: In 426 respondents, age was 64.3 years. The reliability for r coefficient 0.90 (mobility) and 0.89 (pain and stiffness) (Cronbach's alpha 0.95, 0.95 respectively) was high in the test-retest, and there was no significant difference in paired t-test (p>0.05). Item internal consistency (${\alpha}=0.92$, ${\alpha}=0.87$ respectively) was also high. It was constructed of two factors (mobility, pain and stiffness dimension) and nine items in explanatory factor analysis; results of confirmatory factor analysis also indicated that the dimensional structure model was fitted well in the test of model fit (${\chi}^2=83.83$, df=26, p=0.000; RMR=0.05; GFI=0.96; AGFI=0.83). Conclusion: In conclusion, the results of this study showed that the KAIMS that was developed was a reliable and valid instrument for measurement of osteoarthritis (OA) patients. We recommend further research for additional development of the instrument on OA in Korea.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.90-91
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• 2020

Utilization of upgraded fine fly ash in cement-based materials has been proved by many researchers as an effective method to improve compressive strength of cement based materials at early ages. The addition of fine fly ash has introduced dilution effect, enhanced pozzolanic reaction effect, nucleation effect and physical filling effect into cement-fly ash system. In this study, an integrated reaction model is adpoted to quantify the contributions from cement hydration and pozzolanic reaction to compressive strength. A modified model related to the physical filling effect is utilized to calculate the compressive strength increment considering the gradual dissolution of fly ash particles. Via combination of these two parts, a numerical model has been proposed to predict the compressive strength development of fine fly ash mortar considering fly ash fineness. The reliability of the model is validated through good agreement with the experimental results from previous articles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.408-417
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• 2017

The objective of this study is to examine the structural relations between physical self-efficacy, depression, and ego-integrity among the elderly (60 years and older) currently participating in leisure sports. In addition, since the variables affecting ego integrity are presented in a multidimensional manner, it is very important to examine the cause and effect of the variables from an integrated perspective. To achieve this objective, 427 senior citizens attending the leisure sports program of a seniors center were assigned as the research subjects. For the structural equation modeling performed in the study, confirmatory factor analysis and reliability analysis were conducted for each variable, and direct, indirect, and total effects were estimated. The model fit is based on TLI, CFI, and RMSEA, and both the fit of the measurement model and the fit of the research model satisfy the criterion. The results of the analysis are as follows. First, in the results of verifying the validity and reliability of the questionnaire, all the variables of physical self-efficacy, depression, and ego-integrity were suitable. Second, the perceived physical ability had positive effects on depression, current life satisfaction, wise life, and attitude toward life, whereas the physical self-expression confidence had positive effects on current life satisfaction and attitude toward life, but negative effects on acceptance of the past life. Lastly, depression had negative effects on current life satisfaction. The results showed that the elderly identified the integrated relationship of physical self - efficacy, depression, and self-integration.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.225-232
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• 2022

In this paper, the physical neutral surface concept is applied to study the wave propagation of functionally graded (FG) circular plate, the wave equation is derived by Hamiltonian variational principle and the first-order shear deformation plate model. Then, we convert the equations to dimensionless equations. The exact solution of wave propagation problem is obtained by Laplace integral transformation, the first order Hankel integral transformation and the zero order Hankel integral transformation. The results obtained by the current model are very close to those obtained in the existing literature, which indicates the correctness and reliability of this study. Moreover, the effects of the functionally graded index parameters and pore volume fraction on the wave propagation are also discussed in detail.

• Wind and Structures
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• v.14 no.4
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• pp.321-335
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• 2011

The vulnerability of roofing components of contemporary houses built in cyclonic regions of Australia is assessed for increasing wind speeds. The wind loads and the component strengths are treated as random variables with their probability distributions derived from available data, testing, structural analysis and experience. Design details including types of structural components of houses are obtained from surveying houses and analyzing engineering drawings. Wind load statistics on different areas of the roof are obtained by wind tunnel model studies and compared with Australian/New Zealand Standard, AS/NZS 1170.2. Reliability methods are used for calculating the vulnerability of roofing components independently over the roof. Cladding and batten fixings near the windward gable edge are found to experience larger negative pressures than prescribed in AS/NZS 1170.2, and are most vulnerable to failure.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.6
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• pp.347-357
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• 2013

Cyber-Physical system(CPS) is characterized by collaborating computational elements controlling physical entities. In CPS, human desire to acquire useful information and control devices anytime and anywhere automatically has increased the necessity of a high reliable system. However, the physical world where CPS is deployed has management complexity and maintenance cost of 'CPS', so that it is impossible to make reliable systems. Thus, this paper presents an 'Autonomic Control System towards High-reliable Cyber-Physical Systems' that comprise 8-steps including 'fault analysis', 'fault event analysis', 'fault modeling', 'fault state interpretation', 'fault strategy decision', 'fault detection', 'diagnosis&reasoning' and 'maneuver execution'. Through these activities, we fascinate to design and implement 'Autonomic control system' than before. As a proof of the approach, we used a ISR(Intelligent Service Robot) for case study. The experimental results show that it achieves to detect a fault event for autonomic control of 'CPS'.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1771-1779
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• 2018

Modern trams with a super capacitor have gained a lot of attention in recent years due to its reliability, convenience, energy conservation and environmental friendliness. Because of its special charging characteristic, the traditional charging structure and control strategy cannot satisfy its charging requirements. This paper presents a new charging topology for fast charging modern trams with a super capacitor and it designs a controller using continuous control set model predictive control (CCS-MPC). There are three contributions in this paper. First, a new charging structure is designed and its mathematics model is derived. The cascade structure is adopted instead of the parallel structure to simplify the control process and to keep the rated power of the controllable part low. Second, a MPC control strategy is proposed to satisfy the charging characteristic. The optimal control signal can be obtained by solving the designed optimization problem. The optimal control signal is related to the discrete control action. In addition, mapping between the continuous control signal and the discrete control action is designed. Third, a semi-physical experimental platform is built to verify the proposed topology and control method. The simulation model and experiment platform are built to verify the correctness of the new structure and its control method. The results obtained show that the new topology can work effectively.