• Transactions on Control, Automation and Systems Engineering
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• 제2권2호
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• pp.92-97
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• 2000

The Lyapunov stability theorem is used to derive a control law that can be used to control the spacing between vehicles in a platoon. A third order system is adopted to model the vehicle and power-train dynamics. In addition, the concept of

• 아동학회지
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• 제22권4호
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• pp.17-32
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• 2001

The purpose of this study was to explore the developmental patterns of self-concept of pre-adolescents and adolescents by using the longitudinal data originated by the Korean Institute for Research in the Behavioral Sciences (KIRBS). Specifically, using Structural Equation Modeling (SEM), the effects of parents and peer groups on the stability and change of self-concept were examined across a 9-year-period. The subjects were 62 children(29 boys and 33 girls) from the KIRBS longitudinal data. The results showed that, peer relationships revealed consistent effects on children's self-concept from pre-adolescence to mid-adolescence. In particular, this influence was most evident at 7 years of age and at 16 years of age. However, parental influence was almost non-existent for 7-year-olds, equivalent to peer relationships for 10-year-olds, and decreased for 16-year-olds. On the whole, parental and peer influence on self-concept gradually decrease in adolescence. Nevertheless, parental and peer influence continue to maintain a certain level of influence from childhood to adolescence. This study provides an understanding of developmental change and stability in the self-concept of Korean adolescents.

• 대한조선학회논문집
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• 제36권3호
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• pp.60-70
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• 1999

해면효과를 받는 WIG선의 종방향 안정성 특성은 고도에 따른 힘과 모멘트의 변화량 때문에 일반 항공기와는 매우 다르게 나타나며, WIG선의 안전한 설계 및 성능에 큰 영향을 준다. 해면 효과를 고려한 WIG선의 종방향 운동방정식으로부터 정안정성 및 동안정성 조건을 유도하고 이를 분석하였다. 20인승 WIG선의 실험데이터로부터 정적 및 동적 안정성 해석을 수행하였으며, 몇가지 설계인자의 변화에 따른 동적 운동특성도 조사하였다. 마지막으로 순항조건에서 비행성능(flying quality)을 군용 항공규정에 의해 분석하였다.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.14-19
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• 2012

On-line and real-time information of the longitudinal velocity is the essential factor for the Advanced Vehicle Control Systems such as ABS(Anti-lock Brake System), TCS(Traction Control System), ESC (Electronic Stability Control) etc. However, the longitudinal velocity cannot be easily measured or calculated during braking maneuvering. A new algorithm is presented for the estimation of the longitudinal velocity with the measurements of the vehicle longitudinal/lateral acceleration, steering angle and yaw rate. The algorithm is designed utilizing the Extended Kalman Filter based on the 3 degree of freedom vehicle model. In order to compensate for the biased sensor signal on the inclined road, the inclined angle is also estimated. The performance of the proposed estimation algorithm is evaluated in field tests.

• 아동복지연구
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• 제16권2호
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• pp.109-135
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• 2018

The purpose of this study was to analyze the longitudinal causal relationship between caregiver relations and peer relations of children in out-of-home care. We analyzed the three years(2011-2013) of longitudinal data from the Panel Study on Korean Children in Out-of-Home Care. The autoregressive cross-lagged model (ARCL) was used to measure the longitudinal causal relationship between caregiver relations and peer relations. As a result, first, caregiver relations and peer relations showed stability over time. In other words, the results of the measurement at three time points showed that the caregiver relations and peer relations at the previous time had a significant effect on the caregiver relations and peer relations at the later time point. Second, the previous caregiver relations had a significant effect on the subsequent peer relations over time. Third, the previous peer relations had a significant effect on the subsequent caregiver relations over time. This study confirmed the interrelationships of caregiver relations and peer relations of children in care by examining the longitudinal data using the longitudinal analysis method.

• Structural Engineering and Mechanics
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• 제8권2호
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• pp.193-205
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• 1999

A formulation for the dynamic stability analysis of cylindrical shells resting on elastic foundations is presented. In this previously not studied problem, a normal-mode expansion of the partial differential equations of motion, which includes the effects of the foundation as well as a harmonic axial loading, yields a system of Mathieu-Hill equations the stability of which is analyzed using Bolotin's method. The present study examines the effects of the elastic foundation on the instability regions of the cylindrical shell for the transverse, longitudinal and circumferential modes.

• 한국정보통신학회논문지
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• 제10권2호
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• pp.392-397
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• 2006

본 논문에서는 ESP와 4WS차량의 동적성능에 관한 연구와 차량이 불안정 영역으로의 주행 시 안정영역으로의 거동으로 할 수 있게 하는 차량의 주행안정성 향상에 관한 연구를 수행하였다. 고속으로 주행하는 차량이 조향과 동시에 가${\cdot}$감속을 하는 경우 관련된 변수로는 종방향 및 횡방향의 속도변화, 요우잉 등을 들 수 있으며, 이 변수들은 타이어 특성, 차량의 중량, 제동력, 조향각등에 따른 동역학적 관계식들로 표현 할 수 있다. 본 연구는 위와 같은 제동${\cdot}$조향장치들을 제어하여, 차량의 주행 중 위급상황 시 탁월한 성능을 발휘 할 수 있는 시스템에 관하여 고찰하고, 주행시 안정성향상을 위한 제어시스템 알고리즘개발을 통하여 운전상황을 안전하게 하기 위함이다.

• 아동학회지
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• 제37권1호
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• pp.73-82
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• 2016

Objective: This two-wave study examined stability in kindergarteners' friendship patterns over 5 months. Methods: Participants were 501 five-year-old children (262 girls and 239 boys) attending kindergartens in Seoul, Incheon, and Kyounggi provinces in Korea. Each child nominated three individuals as his/her friends in July, and again in December of 2013. Depending on the presence/absence of friendships and the mutuality of identifying friends, the children's friendship patterns were categorized into five groups: stable, fluid, loss, gain, and friendless. The data were analyzed by descriptive statistics, and chi-square tests. Results: Results revealed stability, as well as changes in friendship patterns, among kindergarteners over the 5-month period. The stable friendships, those that maintained the same friend(s) in both waves, was 43.7%, the fluid friendships, those that changed friends over the 5 month period was 18%, the gain friendships, those who had newly developed friends in wave 2 was 17%, and the loss friendships, those who had friends at wave 1 but lost friends at wave 2, was 9.8%. The friendless, those that had no friends in both waves, was 11.5%. Conclusion: Results showed that kindergarteners were capable of maintaining and making new friends over a 5-month period.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1078-1083
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• 2008

In this paper, assessed are the stability of vehicle and track according to vertical support stiffness difference on the transition between conventional and zero-longitudinal resistance (ZLR) rail fastener on bridge. For this, the spring constants of rail fastener have been determined according to different load ranges - KTX load (with or without impact factor) and test load of EN standards - from results of laboratory test on rail pad, the stability analysis of vehicle and track has been performed according to numbers or installation length of ZLR fasteners using vertical vehicle-track coupled model to consider train-track interaction. The analysis results reveal that only the wheel load variation slightly exceed the limit value when 2 ZLR fasteners are used with spring constant determined within the EN test load range, but, in all other cases, all evaluation items are satisfied. Thus, it can be said that the stability of vehicle and track will not be degraded by ZLR fastener.

• Archives of Reconstructive Microsurgery
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• 제7권2호
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• pp.88-94
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• 1998

Free vascularized fibular transplantation is one of the most useful living bone reconstructive procedure in microsurgical field. Concerning about donor site morbidity, the donor has minor problems of ankle stability and muscle power weakness and transient peroneal nerve symptoms. That problems can be minimized with longitudinal splitted osteotomy on the donor fibula if the bone defect in recipient site is not so large. Half splitted fibula with peroneal arterial pedicle which contains nutrient artery and periosteal vessels, grafted bone can survive with those vascular supplies. Authors underwent five cases of half splitted free vascularized fibular transplantation from 1985. There were no evidence of devascularization in all cases, we can minimized donor morbidity with leaving half fibula intact on donor site. The problem of that technique is technically demanding in longitudinal splitting of bone without damage to peroneal nutrient vessels and periosteal soft tissues which attached to the bone. Authors can propose longitudinal half fibular transplantation is one of modification in free vascularized bone transplantation that minimize donor defect.