• Korean Journal of Child Studies
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• v.38 no.2
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• pp.81-91
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• 2017

Objective: The purpose of this study was to identify the longitudinal relationship between child maltreatment and adolescent suicidal ideation. Several studies suggest that child maltreatment is associated with adolescent suicidal ideation. However, these studies have not focused on the duration of child maltreatment. Methods: Participants were 420 adolescents (52.6% male; 47.4% female) involved in the Korea Welfare Panel Study. Data were collected via youth self-report in 2006, 2009, and 2012. A self-report assessment of children and youths' experiences of physical, emotional, or neglect had been surveyed longitudinally. Questionnaires on adolescent suicidal ideation were answered in 2012. A growth mixture model and multiple regression were conducted using Mplus 5.21. Results: The study results showed that 93.5% of the children had experienced no maltreatment; 6.5% had experienced increasing maltreatment longitudinally. The trajectory of increasing maltreatment was positively associated with adolescent suicidal ideation. Conclusion: These results show that children suffering from chronic maltreatment are subject to a high risk of suicide and therefore require continuous supervision and management.

• Korean Journal of Social Welfare Studies
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• v.49 no.3
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• pp.209-245
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• 2018

In this study, various performance types, the combinations of the performance types for growth were investigated to suggest viable policy recommendations for the sustainable growth of social enterprises. The data of the economic and social performance of social enterprises from 2011 to 2016 were obtained and the changes were investigated. Among total of 235 social enterprises that participated in Cho et al, 2011, the research subjects were 164 social enterprises, which were still being operated in March, 2018. The performance of 6 years, since 2011, was surveyed, and total of 104(recovery factor: 69.8%) of social enterprises were analyzed using the growth mixture model, cross tabulation. First of the results, the latent trajectory classes of sales, which are of economic performance, were investigated through the analysis of growth mixture model. The optimal model including three latent classes was adopted. The three latent classes were named as 'mature sales type', 'growing sales type', and 'average sales type'. Second, the latent trajectory classes of employment rate, which are of social performance, were investigated. The optimal model including three latent classes was adopted. The three latent classes were named as 'average employment type', 'declining employment type', and 'increasing employment type'. Third, cluster in $3{\times}3$ tabulation, which is a distribution of the latent trajectory classes of social performance based on the latent trajectory classes of economic performance of social enterprises, was looked into.

• 한국노년학
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• v.39 no.1
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• pp.37-60
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• 2019

This study was attempt to derive the aging trajectories of Korean elderly people and identify its characteristics. In particular, this study used the successful aging model of Rowe and Kahn as an analytical framework. Using the Korean Longitudinal Study of Ageing(KLoSA), this study applied group-based multi-trajectory analysis to identify multiple aging trajectories in sample of Korean elder aged 65~74(n=2,682). This study also used several demographic characteristics as baseline predictors to identify the characteristics of each aging trajectory. Five dimensions were analyzed in the multi-trajectory model: chronic disease, physical functional limitation, cognitive functioning, depressive symptom and social engagement. As a result of the analysis, five aging trajectories were identified: successful aging(17.8%), usual aging (33.9%), health declining aging(18.2%), pathological aging(7.9%), and aging with mild cognitive impairment(22.1%). In general, the odds of experiencing successful aging were high in men, low-aged, highly educated, high-income, and spousal elderly. On the other hand, for the elderly, who are under-educated, low-income, and high-aged, there was a high probability of experiencing a relatively difficult aging process. In particular, the odds of experiencing a mild cognitive impairment aging was high in older, lower-income women without a spouse.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.5
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• pp.277-286
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• 2017

This paper introduces mathematical modelling and control algorithm of expendable mine disposal vehicle. This vehicle has two longitudinal thrusters, one vertical thruster and internal mass moving system which can control pitch rate. Also, the vehicle has an optical camera and forward looking sonar for underwater mine detection and classification. The vehicle is controlled via an optical cable connected with operating console on the mother ship. We describe the vehicle's 6DOF dynamic model and controller which can track the desired trajectory for the way-point tracking. These simulation results shows guidance and maneuvering performance which has other sensor data or not.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.69-70
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• 2013

By using differential force between left and right wheel, lateral motion can be controlled known as Direct Yaw-moment Control (DYC). In previous researches, DYC control is proposed to increase the stability of the vehicle, but maneuverability has not been discussed sufficiently. The car handling condition which is called the index parameter of maneuverability is dependent on the vehicle velocity and steering angle. To achieve the desired vehicle's cornering path, the car handling condition must be considered sufficiently. In this paper, the novel DYC method is proposed which gives the car handling condition regardless of the longitudinal speed. The proposed controller is based on the PI controller to feedback the curvature parameter. The controlled system shows the advantages of DYC regarding to the reference trajectory by the dual motor system. With respect to the uncontrolled model, the effectiveness of the proposed method is validated by numerical examples.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.209-220
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• 1996

In this paper, dynamic performance of 4WD/4WS Electric-driven vehicles is investigated. A coupled dynamic model is introduced for longitudinal, lateral and yawing motion of 4WD/4WS vehicles. Based on the coupled model, dynamic performance is analyzed for steady-state steering, acceleration steering and brake steering, respectively. These non steady-state cornering analysis is important for non-paved road maneuvering, trajectory projection for armored vehicle and future AVCS(Advanced Vehicle Control System) technology. Simulation results are obtained based on a simulink module for the introduced model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.49-52
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• 2008

In this study, multilayer structured ultrasonic linear motor was simulated using Atila for investigating its optimum driving conditions. The ultrasonic linear motors mainly consist of an ultrasonic vibrator to generate elliptical displacement. The ultrasonic linear motor simulated in this paper was the use of the 1st longitudinal(Ll) and 4th bending vibrations (B4). Whit the increase of the number of piezoelectric actuator layers, displacement of node was increased. Maximum total displacement of node was about $3,91{\mu}m$ at the 13 layered ultrasonic motor under 5 V.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.152-167
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• 2001

Recently safety systems for the commercial vehicle have been rapidly developed. However, we still have many problems in the vehicle stability and the braking performance. Especially, a commercial vehicle may meet a dangerous braking condition when the vehicle is lightly loaded or empty and when the road is wet or slippery. Under these conditions, the truck can spin out or the tractor can jackknife or the trailer can swing out. To design the air brake system for the commercial vehicle, since the air brake system has many design variables, there must have been intensive researches on a method how to prevent dynamic instability and how to maximize the vehicle deceleration. In this study, mathematical models about the tractor-semitrailer and the air brake system including an ABS controller have been constructed for computer simulation. Also, simple examples are applied to show the usefulness of the program. Designers can use this simulation program for understanding the braking characteristics such as trajectory, braking distance, longitudinal deceleration, lateral deceleration, and yaw rate on various road conditions.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.73-78
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• 2015

According to the characteristic of carrier-based aircraft, the method of solving safe set during arresting landing is discussed in this paper based on optimal control and invariant set theory. The safe sets of carrier aircraft are evaluated in different states on the characteristic of longitudinal augmented system by using the level set method. Then, the influence on the boundary of safe set under various factors is analyzed. At last, the maneuverability envelope protection is established based on the corresponding theory, and the validity of the system is verified through simulation. The results demonstrate preliminarily that: compared with mass and thrust, the elevator is the greatest influence factor for the boundary of safe set; the dynamic trajectory of carrier-based aircraft can be located at the interior of safe set effectively with the maneuverability envelope protection.

• Korean Journal of Child Studies
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• v.27 no.3
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• pp.169-187
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• 2006

A hierarchical linear model(HLM) provides advantages over existing traditional statistical methods (e.g., ordinary least squares regression, repeated measures analysis of variance, etc.) for analyzing multilevel/longitudinal data or diary methods. HLM can gauge a more precise estimation of lower-level effects within higher-level units, as well as describe each individual's growth trajectory across time with improved estimation. This article 1) provides scholars who study children and families with an overview of HLM (i.e., statistical assumptions, advantages/disadvantages, etc.), 2) provides an empirical study to illustrate the application of HLM, and 3) discusses the application of HLM to the study of children and families. In addition, this article provided useful information on available articles and websites to enhance the reader's understanding of HLM.