• 한국자동차공학회논문집
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• 제5권6호
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• pp.192-201
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• 1997

The feedback control scheme of the pressure control system of the rear wheel steering gear which has relatively large volume and sprung load was built up in order to improve th response characteristic of the system. The control algorithm chosen was a feedback compensator joined by a feedfoward compensator and the model matching method was used in the process of control system design. The structures and properties of the reference models were inspected and the parameters of the controller were decided. The improvement of the response characteristic of the pressure control valve by means of the feedback control is affirmed. Particularly, when the order of the system model is higher than the 2nd order, the effectiveness of the feedback control on the improvement of the response characteristic of the valve is distinct. And the convenience of the model matching method is the process of control system design is confirmed as well.

• Communications for Statistical Applications and Methods
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• 제29권1호
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• pp.27-40
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• 2022

In this paper, the focus on the removal noise in the binary image based on the variational Bayesian method with the Ising model. The observation and the latent variable are the degraded image and the original image, respectively. The posterior distribution is built using the Markov random field and the Ising model. Estimating the posterior distribution is the same as reconstructing a degraded image. MCMC and variational Bayesian inference are two methods for estimating the posterior distribution. However, for the sake of computing efficiency, we adapt the variational technique. When the image is restored, the iterative method is used to solve the recursive problem. Since there are three model parameters in this paper, restoration is implemented using the VECM algorithm to find appropriate parameters in the current state. Finally, the restoration results are shown which have maximum peak signal-to-noise ratio (PSNR) and evidence lower bound (ELBO).

• 산업공학
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• 제21권3호
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• pp.283-293
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• 2008

It is important to choose and develop right business model in the process of implementing the ubiquitous service concept. In particular, it is also required to build a method which can assist in establishing a business model in a competitive perspective to differentiate business strategy. However, we could not find the existing studies which tried to develop business model including methods on how to differentiate business strategy in a competitive environment. In this study, we propose an ontology for repository of ubiquitous business model and address on how to apply the proposed business model repository to real ubiquitous industry. We also built a repository of unlicensed wireless device industry to check the applicability of proposed ubiquitous business model ontology and to show the various examples. We expect that building the business model repository contributes to reduce the redundancy and inefficiency for industry as well as to increase likelihood of business success for an individual company.

• Earthquakes and Structures
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• 제11권6호
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• pp.1101-1121
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• 2016

Base isolation, one of the popular seismic protection approaches proven to be effective in practical applications, has been widely applied worldwide during the past few decades. As the techniques mature, it has been recognised that, the biggest issue faced in base isolation technique is the challenge of great base displacement demand, which leads to the potential of overturning of the structure, instability and permanent damage of the isolators. Meanwhile, drain, ventilation and regular maintenance at the base isolation level are quite difficult and rather time- and fund- consuming, especially in the highly populated areas. To address these challenges, a number of efforts have been dedicated to propose new isolation systems, including segmental building, additional storey isolation (ASI) and mid-storey isolation system, etc. However, such techniques have their own flaws, among which whipping effect is the most obvious one. Moreover, due to their inherent passive nature, all these techniques, including traditional base isolation system, show incapability to cope with the unpredictable and diverse nature of earthquakes. The solution for the aforementioned challenge is to develop an innovative vibration isolation system to realise variable structural stiffness to maximise the adaptability and controllability of the system. Recently, advances on the development of an adaptive magneto-rheological elastomer (MRE) vibration isolator has enlightened the development of adaptive base isolation systems due to its ability to alter stiffness by changing applied electrical current. In this study, an innovative semi-active storey isolation system inserting such novel MRE isolators between each floor is proposed. The stiffness of each level in the proposed isolation system can thus be changed according to characteristics of the MRE isolators. Non-dominated sorting genetic algorithm type II (NSGA-II) with dynamic crowding distance (DCD) is utilised for the optimisation of the parameters at isolation level in the system. Extensive comparative simulation studies have been conducted using 5-storey benchmark model to evaluate the performance of the proposed isolation system under different earthquake excitations. Simulation results compare the seismic responses of bare building, building with passive controlled MRE base isolation system, building with passive-controlled MRE storey isolation system and building with optimised storey isolation system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.251-252
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• 2011

This paper describes the development of hardware simulator for the operation analysis of DC microgrid, which has a wind power, solar power and fuel cell as a distributed generation, and a supercapacitor and battery as an energy storage. A detailed simulation model for the DC microgrid was developed for operation analysis. Based on simulation results a hardware simulator was built in the lab for the purpose of operation analysis. The developed hardware simulator can be utilized to evaluate with practical manner the performance of actual microgrid in the field.

• Asia pacific journal of information systems
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• 제17권2호
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• pp.29-47
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• 2007

Owing to the rapid growth of using the Internet, not only click-and-mortar companies but also brick-and-mortar ones have been expanding their distribution channels into online, Moreover, since online channels are more attractive than offline ones in control and maintenance, switching customers into online ones is emerged as one of very important managerial issues in a view of reduction of cost as well as expansion of services. However, the switched customers should be faced by uncertainties which could not have been experienced in offline. Specifically, in online channels, buyers and sellers are separated temporally and spacially and there are always so many kinds of threat for security as well as not enough systems and conventions for them yet. Therefore, trust has been considered as one of the most critical mechanisms for resolution of such uncertainties in online transactions. However, it is not easy to build and maintain the relationships in online since most of them are virtual and indirect generally. Therefore, in order to switch offline customers into online ones, it is very important to make strategies based on identification of the relationship between online transaction and offline trust which has been built in offline business. Generally offline trust, which has been built independent of online, could not include trust for online-dependent activities such as payment security during or after transactions, while most of online trust include it. Therefore, a customer with high offline trust does not always perceive high security and assure safe transactions. Accordingly, while online trust, where technical capabilities for online security is one of main bases, includes control trust implicitly or explicitly, offline trust does not. However. in spite of such clear discrimination and independence between offline trust and perceived security, there can be the significant dependency between these two beliefs. The customers with high offline trust believe that the company would do some activities for online security for customers' safe transactions since it has been believed of doing well for customers' trust. Theoretically, users' perception of security is interpreted as a kind of control trus, which is trust for company's technical control capacities in order to resolve technical uncertainties in online. Therefore, the relationship between two beliefs can be considered as transference from offline trust to another type trust. that is, control trust. The objective of this study is to analyze the effect of offline trust on online transaction uses mediated by perceived security. For this purpose, we suggest a research model based on technology acceptance model (TAM). Reuse intention is adopted as a dependent variable and TAM is modified by adding perceived risk (PR) as well as two beliefs of using Internet banking, perceived usefulness (PU) and perceived ease of use (PEOU). Moreover, perceive security (PS) is adopted as an external variable for PR and PU, while offline trust (OT) is an antecedent of PS. For an empirical test, sampling from 108 visitors to the banks in Daegu, Korea, we analyze our model by partial least square (PLS) approach. In result, our model is shown to explain 51.4% of the variance in reuse intention and all hypothesis are supported statistically. A theoretical implication of this study is to identify a role of PS between offline trust and reuse intention of using online transaction services. According to our result, PS can be considered as a mediation variable for bridging between two different concepts: trust that explains social aspects of customers and companies, and TAM that explains customers' reuse intention.

• Asia pacific journal of information systems
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• 제13권2호
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• pp.119-143
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• 2003

Trust has been identified as a key component in many e-Commerce studies. The purpose of this study is to find out which factors play a major role in building trust and how the built-up trust affect consumer's purchase intention in Internet used-car transactions. Based on the information asymmetry, TAM(Technology Acceptance Model), and the trust theory, our research model includes factors such as a buyer's propensity-to-trust, institutional characteristics(inspection and warranty policy), word-of-mouth referral, perceived size, and perceived benefits as independent variables. The model also includes trust as a mediate variable, intention to purchase as a dependent variable and perceived quality risk as a moderate variable. The research model is tested by analyzing 787 sample data gathered from Internet used-car transaction sites. The result shows that the trust has significant effects on the online purchase intention, and institutional characteristics has been identified as the most significant factor for the trust of Internet used-car sites. The independent factors influencing trust vary depending on the level of perceived quality risk. For users who perceive the quality risk low, the perceived benefits explain a little portion of the purchase intention. However, those who perceive quality risk high would purchase used-cars only when they have trust on the Internet sites, indicating that trust play an important role as a mediate variable. This study suggests that enhancing the trust in Internet used-car sites is important to increase online transactions.

• ETRI Journal
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• 제25권2호
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• pp.140-143
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• 2003

In this paper, we present a probabilistic approach to determining whether extracted facial features from a video sequence are appropriate for creating a 3D face model. In our approach, the distance between two feature points selected from the MPEG-4 facial object is defined as a random variable for each node of a probability network. To avoid generating an unnatural or non-realistic 3D face model, automatically extracted 2D facial features from a video sequence are fed into the proposed probabilistic network before a corresponding 3D face model is built. Simulation results show that the proposed probabilistic network can be used as a quality control agent to verify the correctness of extracted facial features.

• 경영과정보연구
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• 제9권
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• pp.117-137
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• 2002

As attention to the Internet from both companies and individuals is rapidly on the increase, hundreds of new websites are opening in a single day. Along with such a high attention to the Internet, to set up an effective website needs efficient evaluation and reliable evaluation criterions for the website. The existing homepage contests and evaluation models are limited to certain websites in a special field or to the systemic side and to the contents, which in fact weakened the development of detailed evaluation sections and items possibly measured. This study is designed to integrate and seek out methods and success factors that should be considered when a website is built up, discovering evaluation criterions and making evaluation models objectively possible to be measured. The study focused on investigation into a new measurement standard and model by considering the previous studies, in order to suggest the followings: Centering the 7 top evaluation sections by type of each website such as (1) Service, (2) Mechanism, (3) Structure & Navigation, (4) Usability, (5) Contents (6) Community, (7) Communication, the study suggests an objective and reasonable website evaluation model on a basis of common factors considered in an integral and optimum view.

• 교육시설
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• 제8권2호
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• pp.5-12
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• 2001

As the exiting school facilities become old and unfit for new curriculum, the systematical remodelling process based on its educational and physical functions is required. due to the inadequate maintenance and repairing practices, unnecessary costs are expended. Therefore, this study aims to establish a remodelling decision-making model for improving the educational environment of the existing school facilities. According to the budget system, it proposes the concept of remodelling that includes the activities of extension, reconstruction, repair and improvement. This study classifies the performance evaluation for school facilities as that of safety, durability and educational function, and articulates the assessment standards, methods and elements. In the end, it suggests a rational model for remodelling decision-making that can provide efficient and comprehensive remodelling process, economic and sustainable school development.