• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.9-17
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• 2006

The SNU MAV has been designed through studies on highly efficient aerodynamic shape and propulsion system. The configuration of the vehicle was determined from conventional empirical equations, iterative wind tunnel tests and flight tests. The propeller shape was optimized with the various thrust tests and RSM(Response Surface Method) to obtain the higher efficient propulsion system. It was certified that the MAV could fly for over 17 minutes with a 210mAh battery. In addition, it showed good flight characteristics in both stability and controllability.

• Korean Journal of Social Welfare
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• v.66 no.2
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• pp.75-99
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• 2014

The purpose of this study is to examine mediation role of parental attachment, school bonding and delinquent peers in effects of child abuse experience on offending school violence among middle school students. The survey was conducted for boys and girls enrolled in 50 middle schools located in Seoul and Kyung-ki province from October 15 to November 25 in 2012 and total 1,563 were used for final analysis. PASW 18.0, AMOS 18.0 and Mplus were used for statistical analysis. Major findings of this study are as follows. Child abuse experience is analyzed as effecting directly to offending in school violence but also having indirect effecting through mediation process with parental attachment, school bonding and delinquent peers from the analysis of structural equation model. Another finding indicates that multiple indirect effects of parental attachment, school bonding, delinquent peers through Mplus nonlinear analysis, pathways including mediator of parental attachment, school bonding and delinquent peers are verified as statistically significance. Below is discussed for practical and policy implications to prevent school violence in middle school based on this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.33-40
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• 2005

The reliability of flight control system(FCS) for Unmanned Air Vehicle(UAV) is underestimated because of the design restrictions such as small size, low cost and light weight. However because the failure of FCS may cause the loss of aircraft, the reliability of FCS must be analysed and validated whether it meet the reliability requirements in design phase.In this paper the failure rate of subsystems was divided with its function based on the design experience of FCS. The redundancy models which satisfy the system reliability requirements were suggested. These results may be utilized in the hardware design of FCS.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.186-192
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• 2013

Fabrication of human powered aircraft and flight test procedure for pilot training are included in this paper. To meet the weight requirement, very light materials such as carbon fiber and PVC foam are used and the final weight was 41.5kg. Ninety two times of flight test were done at Goheung Aviation Test Center from August to September 2012. When KARI were lack of know-how about human powered aircraft, damages on the aircraft were very frequent. After knowing how to fly and to control, one of two pilots was finally successful in flying further to 240m in the Human Powered Aircraft Contest.

• 한국사회정책
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• v.24 no.2
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• pp.127-155
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• 2017

The physical and psychological weaknesses of delinquent adolescents increase the possibility of socialization and the possibility of social exclusion. Therefore, this study aims to clarify the characteristics of the social exclusion through the Q methodology and to suggest policy and practical intervention directions. For this purpose, 36 statements about social exclusion were conducted through 15 prejudicial adolescents with the prior cooperation of the institution and the consent of the subjects. As a result of the analysis, four types were derived. Type 1 can be named as social disconnect type 'Type 2 is total type', type 3 is 'poverty type' and type 4 is 'service type'. Based on this, it can be said that the characteristics of social exclusion of juvenile delinquents are complexity, inclusivity, individuality, universality.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.1 no.1
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• pp.130-147
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• 1990

This study intended to investigate the characteristics of adolescent drug user in Korea. A questionnaire on adolescent drug use was administered to 1st or 2nd grade 898 students (465 males, 433 females) from 9 senior high schools in Seoul area. The extent of current using six representative drugs such as cigarettes, alcohol, chemical substance inducing hallucination(e,g., thinner, bond etc.), psychostimulant, hypnotic and minor tranqulizer was self-reported. Also their psychological distress, self-concept and individual-related variables such as academic grade, deviant behavior, drug-using peers, the perceived availability of drugs, the degree of family discipline, and the perceived parents' attitude for drinking and smoking were surveyed. Subjects were grouped into six(male) or five(female) subgroups (nonuser, simple experiencer, one kind of drug user, two kinds of drugs user, three kinds of drugs user(male only), minor tranqulizer user) to their extent of drug use. Then ANOVA procedure performed for group comparison of their psychological distress, self-concept and individual-related variables. The results showed that the most popular drugs among adolescents in Korea were cigarettes and alcohol. Minor tranqulizer was used by about 2.8% of male and 7.41% of female subjects. In general abusers showed lower academic grade, more deviant experiences, having more drug-using peers, higher degree of psychological distress, and lower postitive self-concept than nonuser group. According to the results of discriminant analysis, hostility and deviant behavior were reliable predictive variables that distinguished abuser group from nonuser group among the associated variables in this study. These results suggest that some common factors affect drug use of Korean high school students : high school students who have many common risk factors could be abusers more easily. These findings supported risk factor theory that the extent of drug use of adolescents might be associated with general maladjustment in everyday life.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.264-275
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• 2022

The purpose of this study is to examine the effects of social withdrawal, depression, aggression, negative parenting attitude as parental factors, friendship as school factors, academic helplessness and smartphone dependence, persistence, etc. on adolescent delinquency experiences as perceived personal factors. was carried out to understand. For this study, first year middle school students in the first year of the Korean Children and Youth Panel Survey (KCPYS 2018) were analyzed. As a result of the study, it was found that depression, aggression, social withdrawal as individual factors of adolescents, negative parenting attitude as parent factors, academic helplessness, negative friendships, smartphone dependence, persistence, etc. as school factors influence delinquent behavior of adolescents. In addition, it was found that smartphone dependence and persistence play a partial mediating role in the process of personal factors, parental factors, and school factors affecting adolescents' delinquency experiences. Based on these results, first, we need to break stereotypes about adolescents and understand the accurate understanding of adolescents' delinquent behaviors and what expectations they have. Second, practical education is required for parents and grandparents for consistent parenting attitudes and effective parenting. Third, a positive self-awareness and correct human relationship formation program should be operated in order to improve the friendship among adolescents. Finally, correct smartphone usage and counseling interventions and prevention programs to alleviate impulsivity are needed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.105-110
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• 2020

This study provides a method and data for predicting the flight initiation wind speed of wind-borne debris. From the force equilibrium acting on debris including aerodynamic and inertia forces, the equation for predicting the flight initiation wind speeds are presented. Wind tunnel tests were carried out to provide necessary aerodynamic data in the equation for the debris with various aspect ratios. The proposed equation for flight initiation wind speeds was validated from free flying tests in the wind tunnel. The flights of debris were mostly initiated by slip when width to thickness was less than 10, otherwise overturning were dominant. The actual flight initiation speeds were lower than that of the computed ones. The surface boundary layer flow and the gap between the debris and surface might affect the prediction error.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.1-9
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• 2009

The ground integration test of Smart UAV has been performed according to the flight test plan. The flight test of full scaled model will be performed followed by 4 DOF ground rig test and a tethered hover test. Smart UAV is the first indigenous tiltrotor aircraft which can fly with fast cruise speed and take off or land vertically. In order to prove the flight control law of Smart UAV, the 40% scaled airplane was developed and have been tested. During flight test of small scaled model, many unique and unexpected problems occurred. After clearing these problems, fully automatic flight test was performed successfully. The experiences about many trouble shooting and resolving the problems would be basic material to avoid the unexpected but similar flight test problems hidden behind of the full scaled Smart UAV. This paper presents the detailed procedures of trouble shootings to solve the unique problems which occurred during the flight test of small scaled tiltrotor UAV.

• Journal of the Korea Computer Graphics Society
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• v.19 no.1
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• pp.21-25
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• 2013

In this paper, we consider a physics-based 2D flight simulation game where users can easily control realistic flight of a vehicle equipped with two thrusters that allow vertical takeoff and vertical landing. The flight vehicle can be manipulated by directly controlling the thrusting force at each thruster using a pair of analog input devices such as joysticks. However, it might require too much practice to make aerobatic flying solely with this kind of control. We propose a set of fly-by-wire methods that provide easy-to-use, intuitive control of a VTVL vehicle. Based on PD controllers, the proposed methods allow users to specify the velocity or position of the vehicle directly. Furthermore, they are easy to understand and simple to implement. We expect that the proposed vehicle model and control mechanism could be used in various 2D games.