• Journal of Information Technology Applications and Management
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• 제25권2호
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• pp.1-21
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• 2018

This study aims to investigate the usage patterns of users in Social Network Services (SNS) where is an upsurge. Specifically, the paper considers the reason why young people more and more prefer online (or mobile) SNS activities rather than offline face-to-face social relationship. Furthermore, the drivers which affect SNS usages are considered from users' personal characteristics and social influences. User's personal characteristics include their personalities (extraversion and introversion), narcissism, and life satisfaction. Social influences involve subjective norm, visibility, and image. Affected by personal and social factors in SNS, users intend to show positive self-presentation, which refers to a behavior to selectively expose his/her goodness to others. As one of the most influential drivers affecting SNS usage, the positive self-representation has an effect on the level of SNS usage. Thus, this paper suggests the hypothesized research model focusing on positive self-representation in the relationship among personal characteristics, social influence, and user's behavior in SNS. Empirical data analysis with 100 questionnaires suggests that all hypotheses were adopted except for the effect of visibility among social influence factors on positive self-representation.

• Journal of information and communication convergence engineering
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• 제11권2호
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• pp.95-102
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• 2013

This paper presents a stochastic driver behavior modeling framework which takes into account both individual and general driving characteristics as one aggregate model. Patterns of individual driving styles are modeled using a Dirichlet process mixture model, as a non-parametric Bayesian approach which automatically selects the optimal number of model components to fit sparse observations of each particular driver's behavior. In addition, general or background driving patterns are also captured with a Gaussian mixture model using a reasonably large amount of development data from several drivers. By combining both probability distributions, the aggregate driver-dependent model can better emphasize driving characteristics of each particular driver, while also backing off to exploit general driving behavior in cases of unseen/unmatched parameter spaces from individual training observations. The proposed driver behavior model was employed to anticipate pedal operation behavior during car-following maneuvers involving several drivers on the road. The experimental results showed advantages of the combined model over the model adaptation approach.

• Journal of Power Electronics
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• 제13권6호
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• pp.964-974
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• 2013

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

• 전기학회논문지
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• 제65권8호
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• pp.1392-1399
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• 2016

Blackout effect occurs when a driver misadapts to the changed lighting conditions upon entering a tunnel. This could lead to a decrease in visibility especially in the daylight, depending on the difference in the degree of brightness between inside and outside the tunnel. To alleviate such a problem, we decrease windshield transparency before the driver arrives at the tunnel entrance. Controlled amount of light inside the car can allow the drivers to adjust to the dark prior to entering. The windshield transparency coefficient is to be determined by the arrival time at the tunnel and difference in the level of brightness between inside and outside the tunnel. Navigation, road sign detection, and tunnel entrance detection provide the arrival time. We also designed an opto-electronic conversion function to estimate the level of brightness. The black-hole phenomenon alleviation method is verified by field experiments using an automobile camera and a navigation. The result shows that the adjusted windshield transparency is able to provide an environment with a comfortable level of brightness with which the drivers can enter tunnels without the visibility problem.

• 한국산업정보학회논문지
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• 제5권3호
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• pp.18-29
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• 2000

결과적으로 컴포넌트 기반의 개발 방법은 새로운 개념의 비용 예측 모델이 요구되고 있으며 외국의 경우 이에 대한 연구가 활발히 진행되고 있다. 그러나 외국의 비용산정 모형을 그대로 적용하기에는 국내 소프트웨어 사용환경에 적절치 못할 것으로 판단되며 또한 축적된 개발 관리 자료의 부족으로 인하여 사용이 매우 제한적인 실정이다. 본 연구는 컴포넌트 환경의 비쥬얼 개발 툴을 기반으로 하는 소프트웨어 개발을 전제로 개발비용의 핵심인 노력도(Person Month)를 산정하는 모델을 제안하고자 한다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권3호
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• pp.226-231
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• 2012

Autoparking assistant systems are a new and very promising area in automotive systems engineering. Since the traffic in modern cities becomes more intense, it is getting harder for a driver. Those systems are necessary for an inexperienced one to find a proper parking slot, or to park in a narrow parking slot without damaging his car or the vehicles around. The implementation of autoparking assistant systems may reduce drivers' stress and make parking generally more comfortable. In addition, such system can be extremely useful for senior or disabled people or for drivers with reduced mobility. The implementation of autoparking assistant systems may increase the safety of the parking, and therefore the development of such systems is a highly-demanded task. We introduce an intelligent autoparking system that automatically generates trajectory for parking using a fuzzy logic. This paper consists of three parts. In first part we introduce trajectory generation method for parallel parking without collisions. Fuzzy-logic based trajectory generation algorithm is described in second part. Experimental results presented in the third part of the paper prove effectiveness of the proposed method.

• 한국지능시스템학회논문지
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• 제20권4호
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• pp.469-475
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• 2010

본 논문에서는 두 바퀴로 구동되는 역진자기반의 1인승 차량의 안정적인 균형을 위해 제어기를 설계하였다. 탑승자의 몸무게에 따라 전체 질량이 달라지므로 그에 따른 PID 제어기의 이득값을 실험적으로 구하였다. 이 때 탑승자의 몸무게에 따라 무게 중심이 달라지게 되는데, 이는 밸런싱 각도에 영향을 미치게 된다. 따라서, 안정적인 균형을 이루기 위해서는 몸무게에 따른 목표 밸런싱 각도를 수정하여 제어해야 한다. 다양한 탑승자의 몸무게를 측정하기 위해 차량에 체중계를 달고 측정된 체중 데이터를 컴퓨터로 전송하여 제어기에 적용하였다. 다양한 실험으로 얻은 정보를 사용하여 제어기의 게인 스케줄링을 통하여 보다 안정적인 균형을 유지할 수 있었다.

• 대한안전경영과학회지
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• 제17권3호
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• pp.65-79
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• 2015

This study intended to investigate exploratorily the precedent factors affecting two types of perceived balances between work and life(family/leisure) and the antecedent ones affected by them, focusing on the metro train drivers. To attain this purpose, literature survey on the precedent factors, work-life balance, and antecedent factors was performed, and the study model was designed based on this survey, and then this model was analyzed empirically using Multiple-Regression. The results on the precedent factors showed that Job Demand, Self-Efficacy, and Age have significant effects on the negative transfer of work. On the other hand, it was shown that Affiliative Culture, Self-Efficacy, and Internal Locus of Control have significant effects on the family centered balance. And the results on the antecedent factors showed that family centered balance has significant effects on Job Satisfaction, Psychological Depression and Fatigue, Safety Behavior, and accident, and the negative transfer of work has significant effects on Physical and Psychological Depression and Fatigue, Emergency Stress, and Safety Behavior.

• 대한안전경영과학회지
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• 제17권3호
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• pp.53-63
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• 2015

This study highlights empirically the relationship among major constructs such as accident, fear and anxiety emotion, self-efficacy, and negative spillover of work, focused on the railway drivers. The differentiated factor of this study is in that the experience of accident was posed as exogenous variable. The main statistical tool was Regression. Hypothesis tests based on 201 samples verified that the experience of accidents showed a significant effect on negative spillover of work mediated by fear and anxiety, with moderating effect of self-efficacy between fear and anxiety and negative spillover of work. However, the moderating effect was shown as increasing the degree of negative spillover of work, since the drivers recognized their fear and anxiety accrued by accident experience as uncontrollable. This findings suggest the need for mitigating driver's negative emotion - fear and anxiety - through an introduction of practice such as exemption of settlement obligation in accident site and lowering of the penalty for accident responsibility.

• 대한안전경영과학회지
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• 제14권4호
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• pp.93-105
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• 2012

The purpose of this study was to investigate drivers' postures in different car pedal systems and skilled levels under fatigue. Twenty four subjects participated in this experiment. For three-dimensional analyses, six cameras (Proreflex MCU-240, Qualisys) were used to acquire raw data. The parameters were calculated and analyzed with Visual-3D. In conclusion, ROAs of two leg-pedal system were less than one leg pedal system by pattern analysis. Through statistical tests, skilled levels have effects on ROAs(X, Y, Z) of ankle joint at breaking a pedal and ROAs(Y, Z) of ankle joint at accelerating a pedal. Also, car pedal systems have effects on ROAs(Y, Z) of ankle joint, and ROA(Z) of knee joint at accelerating a pedal. In addition, skilled levels and car pedal systems (cross effects) have an effect on ROA(Z) of ankle joint. These findings suggested that we should improve a present single pedal system.