• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.766-771
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• 2001

The package used to transport radioactive materials, which is called by cask, must be safe under normal and hypothetical accident conditions. These requirements for the cask design must be verified through test or finite element analysis. Since the cost for FE analysis is less than one for test. the verification by FE analysis is mainly used. But due to the complexity of mechanical behaviors. the results depends on how users apply the codes and it can cause severe errors during analysis. In this paper, finite element analysis is carried out for the 9 meters free drop and the puncture condition of the hypothetical accident conditions using LS-DYNA3D and ABAQUS/Explicit. We have investigated the analyzing technique for the free drop impact test of the cask and found several vulnerable cases to errors. The analyzed results were compared with each other. We have suggested a reliable and relatively simple analysis technique for the drop test of spent nuclear fuel casks.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.295-302
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• 2003

A quantitative approach for the retrofit prioritization of bridges is developed based on the damage risk of seismic vulnerable components. In the developed approach, seismic damage risk is estimated in the probabilistic perspectives with an analytical bridge model, which can consider various phenomena found in the seismic behaviors of girder-type bridges and damage models of various vulnerable components. Based on the total cost due to failure of structural components, weighting factors are proposed. Finally, the ranking index and retrofit priority of bridges are estimated from the overall damage risk and weighting factors of bridges. As a result, the retrofit priority of four PSC girder bridges is evaluated by using the proposed approach. The vulnerable components in need of seismic retrofit are selected accordingly. From simulated results, the validity of the proposed approach is verified by comparison with the existing approach. In addition, the proposed approach is found to be appropriate in evaluating the priority of existing bridges.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.471-476
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• 2008

There has been a growing interest for the use of natural fibers in composite applications due to their low cost, environmental friendliness, and good mechanical properties. It was demonstrated to determine the characteristic of tensile behaviors under the variation of test temperature on sisal fiber reinforced polymer composites by RTM process. Especially, the permanganate-treated-fibers improved tensile strength by increasing the coherence with matrix. Material deformation is restricted to increment of cohesion for surface treatment of fiber and then elongation decreas.

• Journal of Power Electronics
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• v.19 no.1
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• pp.296-306
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• 2019

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondary windings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used to effectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In this paper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter with synchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with a transformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, good heat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulation tool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCB transformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.529-543
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• 2021

Inevitable source-uncertainties in geometry configuration, boundary condition, and material properties may deviate the structural dynamics from its expected responses. This paper aims to examine the influence of these uncertainties on the vibration of functionally graded beams. Finite element procedures are presented for Timoshenko beams and utilized to generate reliable datasets. A prerequisite to the uncertainty quantification of the beam vibration using Monte Carlo simulation is generating large datasets, that require executing the numerical procedure many times leading to high computational cost. Utilizing artificial neural networks to model beam vibration can be a good approach. Initially, the optimal network for each beam configuration can be determined based on numerical performance and probabilistic criteria. Instead of executing thousands of times of the finite element procedure in stochastic analysis, these optimal networks serve as good alternatives to which the convergence of the Monte Carlo simulation, and the sensitivity and probabilistic vibration characteristics of each beam exposed to randomness are investigated. The simple procedure presented here is efficient to quantify the uncertainty of different stochastic behaviors of composite structures.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.50-60
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• 2007

The endeavor of this paper focuses on designing a monitoring system to provide a cost-effective solution on quality assurance for construction projects. The construction site monitoring system integrates a long-range wireless network, network cameras, and a web-based collaborative platform. The users of the system could obtain the most updated status of construction sites, such as behaviors of workers, project progress, and site events anywhere with Internet connectivity. It was carefully configured in order to maintain the reliability under the reactive conditions of the construction sites. This paper reports the architecture of the monitoring system and reviews the related technologies. The system has been implemented and tested on a construction site and promising results were obtained.

• Journal of Nutrition and Health
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• v.52 no.3
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• pp.297-309
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• 2019

Purpose: This study examined the relationship among the use of food-related content (FRC), dietary behaviors, and dietary self-efficacy to demonstrate the need for nutrition education to help adolescents build healthy eating habits and provide evidence for developing nutrition education programs for adolescents. Methods: Three hundred and eighty-one high school students in Seoul and Gyeonggi areas participated in the study. The subjects were divided into three groups (low, medium, and high) according to the level of use of the FRC, and their general characteristics, dietary behaviors, and dietary self-efficacy were analyzed. Correlation analysis was performed between FRC usage, dietary behaviors, and dietary self-efficacy, and the mediating effects of dietary self-efficacy on the relationship between the level of the use of FRC and dietary behaviors were estimated. Results: A higher level of FRC usage was associated with an increased daily cost of eating out and snacking, but no difference was observed in the BMI range. The subjects in a group with a high level of FRC usage ate convenience store or instant foods instead of homemade meals (p = 0.033), had a late-night meal or snack (p = 0.024), and turned to emotional eating under stress (p < 0.001) more than those in the low level group. In addition, the high level group checked the nutrition facts label more carefully when purchasing processed foods (p = 0.016) and exercised at least 30 minutes daily, not considering physical education classes (p = 0.057). The higher level of FRC use, the lower the dietary self-efficacy, whereby the subscales 'environmental stimulus control efficacy' and 'affective factor control efficacy' showed complete mediating effects. Conclusion: Given that FRC has been increased recently, adolescents are in need of support to help them control and enhance their dietary self-efficacy as well as develop healthy dietary behaviors through proper nutrition education programs.

• 한국벤처창업학회:학술대회논문집
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• 2007.04a
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• pp.405-433
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• 2007

This study is conducted to examine how purchase behaviors of consumers have affected by the promotion of coupons in internet shopping mall. This study was conducted with the purpose of identifying the differences in purchase behavior based on consumer' s perception and experience of internet shopping mall coupons, and based on consumers' perception of cost and value of coupons, using a theoretic framework presented in previously conducted studies. The results of this study can be summarized as follows. First, based on the perception of coupons, there were significant differences in intent to use and intent to re-use at the time when coupons are offered, and at the time when coupons are offered, no significant differences were found between the level of interest and the importance of coupon at the time of visiting the shopping mall; however, significant differences were found in the overall purchase behavior based on perception of coupons. Second, when overall differences m purchase behavior based on experience in coupon use was observed, having experience in using coupons showed a higher average than did having no experience in using coupons, showing a significant difference. It was found that compared to those without experience in using coupons, those with experience with coupons had higher intent to use at the time when coupon is offered, intent to re-use at the time when coupon is offered, and higher level of purchase behavior in the importance of coupons at the time of visiting the shopping mall. Third, when relationship between purchase behaviors, cost of coupon, and perception of convenience was observed, a clear static relationship was found. This suggests that as the cost and perception of convenience of coupon increases, purchase behavior also increases. Such result suggests that there is a difference in purchase behavior based on experience in coupon use. When relationship of purchase behavior by variables of cost of coupon and perception of convenience is observed, it has a positive relationship with the perception that the use of coupon includes saving money, financial help, enjoyment of use, habitual use, has a short effective date, and has a negative relationship with the perception that it saves little money and is a waste of time. Therefore, it can be seen that purchase behavior has the highest relationship with enjoyment of coupon use and habitual coupon use. Such results suggest that purchase behavior will be significantly influenced based on cost of coupon and perception of convenience.

• Journal of Distribution Research
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• v.15 no.1
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• pp.25-47
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• 2010

CS is one of the major concerns of managers in the world because it is well known to be a key medium construct for firms' superior outcome. One of the major agents for CS management is retailers. Firms try to manage not only employees but also retailers to promote CS behaviors. And so diverse incentives are used to promote their CS behaviors under diverse channel setting such as multi-channel. However in spite of the rising needs there has been scarce studies on the optimal incentive structure for a manufacturer to offer competing retailers at the multi-channel. In this paper, we try to find better way for a manufacturer to promote the competing retailers' CS behaviors. We investigated how to promote the retailers' CS behavior via game-theoretic modeling. Especially, we focus on the possible incentive, CS bonus type reward introduced in the studies of Hauser, Simester, and Wernerfelt(1994) and Chu and Desai(1995). We build up a multi stage complete information game and derive a subgame perfect equilibrium using backward induction. Stages of the game are as following. (Stage 1) Manufacturer sets wholesale price(w) and CS bonus($\eta$). (Stage 2) Both retailers in competition set CS effort level($e_i$) and retail price($p_i$) simultaneously. (Stage 3) Consumers make purchasing decisions based on the manufacturer's initial reputation and retailers' CS efforts.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1516-1519
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• 1997

With disseminationof Distributed Control Systems(DCS), the huge amounts of process operation data could have been available and led to figure out process behaviors better on the statistical basis. Until now, the statistical modeling technology has been susally applied to process monitoring and fault diagnosis. however, it has been also thought that these process information, extracted from statistical analysis, might serve a great opportunity for process operation improvements and process improvements. This paper proposed a general methodolgy for process operation improvements including data analysis, backing up the result of analysis based on the methodology, and the mapping physical physical phenomena to the Principal Components(PC) which is the most distinguished feature in the methodology form traditional statistical analyses. The application of the proposed methodology to the Balst Furnace(BF) process has been presented for details. The BF process is one of the complicated processes, due to the highly nonlinear and correlated behaviors, and so the analysis for the process based on the mathematical modeling has been very difficult. So the statisitical analysis has come forward as a alternative way for the useful analysis. Using the proposed methodology, we could interpret the complicated process, the BF, better than any other mathematical methods and find the direction for process operation improvement. The direction of process operationimprovement, in the BF case, is to increase the fludization and the permeability, while decreasing the effect of tapping operation. These guide directions, with those physical meanings, could save fuel cost and process operator's pressure for proper actions, the better set point changes, in addition to the assistance with the better knowledge of the process. Open to set point change, the BF has a variety of steady state modes. In usual almost chemical processes are under the same situation with the BF in the point of multimode steady states. The proposed methodology focused on the application to the multimode steady state process such as the BF, consequently can be applied to any chemical processes set point changing whether operator intervened or not.