• Journal of Family Resource Management and Policy Review
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• v.26 no.1
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• pp.27-42
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• 2022

This study was conducted to examine the resources that influence the choice of drop-out students' reentry to school. A total of five years of panel analysis of 2,553 drop-out teenagers from 2013 to 2017 were utilized. In order to verify the resources that affect the choice of school reentry of teenagers with experiences of suspension of studies to formal middle and high school after July 2012, this study analyzed drop-out teenagers' family resources as well as their psychological, mental, and social-relationship resources. A crossover analysis, t-test, and hierarchical logistic regression analysis were conducted. The major outcomes of this study are as follows: First, the socio-demographic variables among the resources that affected the choice of reentry for school of teenager children were the type of family and number of moves to a new house. Second, the psychological and sentimental variable that affected the choice of school reentry was a decreasing level of positive recognition of the situation of suspension of studies combined with depression, impulsiveness, and perceiving society as one that discriminates based on the level of education. Third, significant family resource variables were the type of family form and parents providing economic support, which is a subfactor of parental attachment. Fourth, the presence of a mentor as a helpful social-relationship resource had a significant effect on relational resources. This study is significant in the sense that the positive family resources that affect the choice of school reentry of drop-out teenage students were determined, and the positive directivity of supportive family resources is presented for parents with teenage children experiencing a suspension of studies.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.3
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• pp.247-255
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• 2013

The flight control of re-entry vehicles poses a challenge to conventional gain-scheduled flight controllers due to the widely spread aerodynamic coefficients. In addition, a wide range of uncertainties in disturbances must be accommodated by the control system. This paper presents the design of a roll channel controller for a non-axisymmetric reentry vehicle model using the trajectory linearization control (TLC) method. The dynamic equations of a moving mass system and roll control model are established using the Lagrange method. Nonlinear tracking and decoupling control by trajectory linearization can be viewed as the ideal gain-scheduling controller designed at every point along the flight trajectory. It provides robust stability and performance at all stages of the flight without adjusting controller gains. It is this "plug-and-play" feature that is highly preferred for developing, testing and routine operating of the re-entry vehicles. Although the controller is designed only for nominal aerodynamic coefficients, excellent performance is verified by simulation for wind disturbances and variations from -30% to +30% of the aerodynamic coefficients.

• Journal of Korean Public Health Nursing
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• v.29 no.3
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• pp.515-527
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• 2015

Purpose: This study was to the experiences hospital school programs health impaired children as perceived by mothers. Methods: The participants were 9 mothers of children with health impairment who had in hospital school program. ata were collected through in-depth interview using semi-structured questionnaire. The interviews were analyzed by content analysis. Results: domains and 13 categories were extracted from the analysis. The 5 domains related to the experience hospital school program were emotion, therapeutic course, interpersonal relationship, school reentry, and needs for hospital school management. Conclusion: The results of this study indicate that participation hospital school programs not only educational support but it is also helpful for physical, psychosocial adjustment of health impaired children and could be used develop effective hospital school programs to improve the adaption of children with health impairment.

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.289-302
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• 2017

The key risk analysis technologies for the re-entry of space objects into Earth's atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on reentry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d'Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth's atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.24 no.3
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• pp.141-150
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• 2013

Objectives : The objective of this report is to identify the utilization of hospital school service during hospitalization among patients in their childhood and adolescence with psychiatric disorders. Methods : We retrospectively reviewed the medical record of child and adolescent psychiatric who were hospitalized during March 2009 through October 2012. We compared the one-year successful schooling and outpatient follow up rate between users and nonusers of the inpatient hospital school service. The hospital schooling experiences of the users were investigated upon follow-up visits to the outpatient clinic. Results : Sixty-three students received hospital school service during hospitalization among total 122 child and adolescent inpatients. Hospital school participants showed a significantly higher school reentry rate (61.9%) than non-participants (40.7%). However, there was no difference on follow up rate between the two groups. More than 60% of the 22 interviewed participants expressed an above-average level of satisfaction about hospital school service. Conclusion : Many patients with mental illness experience difficulty in receiving school education during treatment. That induces deterioration in disease, academic failure, poor social skills, low self-esteem, economic difficulties, and future job opportunities. The results of this study emphasize the importance of hospital school service and offer useful guidance for hospital school operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.23-32
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• 2016

Various studies have been conducted for drag reduction of a high-speed vehicle by injecting counterflow jet from its nose cone. In this study, in order to obtain baseline data and key parameters for drag reduction method, the counterflow jet study of the USA is reviewed and summarized. The nose cone shapes of each study are hemisphere cylinder, truncated cone, and reentry capsule, and their test conditions are summarized accordingly. Key parameters for drag reduction are jet mach number, mass flow rate, and pressure ratio. Even though drag reduction effects show various results according to given test conditions, it is found that the drag reduction effect reaches up to 40~50%.

• Journal of Aerospace System Engineering
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• v.13 no.1
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• pp.18-28
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• 2019

High speed vehicles are subjected to high thermal loadings due to aerodynamic heating during ascent and reentry. Since a thermal protection system panel is mechanically constrained, it may cause thermal buckling under excessive thermal loadings. The thermal buckling could disturb the field of flow and make aerodynamic characteristics unstable. It is thus necessary to design the thermal protection system panel to prevent thermal buckling. This study defines the analytical model of temperature distribution using the finite difference method for the thermal protection system panel with large temperature differences inside and outside. This paper proposes the approximate model of the thermal buckling characteristics for the thermal protection system panel through the use of the Ritz method. The validity of the present method was verified by comparing the results of the finite element analysis. Furthermore, this research performs the parametric analysis of the thermal buckling characteristics for the thermal protection system panel by using the approximate model.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.330-339
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• 2008

Ground-based interceptors(GBI) comprise a major element of the strategic defense against hostile targets like Intercontinental Ballistic Missiles(ICBM) and reentry vehicles(RV) dispersed from them. An optimum design of the subsystems is required to increase the performance and reliability of these GBI. Propulsion subsystem design and optimization is the motivation for this effort. This paper describes an effort in which an entire GBI missile system, including a multi-stage solid rocket booster, is considered simultaneously in a Genetic Algorithm(GA) performance optimization process. Single goal, constrained optimization is performed. For specified payload and miss distance, time of flight, the most important component in the optimization process is the booster, for its takeoff weight, time of flight, or a combination of the two. The GBI is assumed to be a multistage missile that uses target location data provided by two ground based RF radar sensors and two low earth orbit(LEO) IR sensors. 3Dimensional model is developed for a multistage target with a boost phase acceleration profile that depends on total mass, propellant mass and the specific impulse in the gravity field. The monostatic radar cross section (RCS) data of a three stage ICBM is used. For preliminary design, GBI is assumed to have a fixed initial position from the target launch point and zero launch delay. GBI carries the Kill Vehicle(KV) to an optimal position in space to allow it to complete the intercept. The objective is to design and optimize the propulsion system for the GBI that will fulfill mission requirements and objectives. The KV weight and volume requirements are specified in the problem definition before the optimization is computed. We have considered only continuous design variables, while considering discrete variables as input. Though the number of stages should also be one of the design variables, however, in this paper it is fixed as three. The elite solution from GA is passed on to(Sequential Quadratic Programming) SQP as near optimal guess. The SQP then performs local convergence to identify the minimum mass of the GBI. The performance of the three staged GBI is validated using a ballistic missile intercept scenario modeled in Matlab/SIMULINK.

• Korean small business review
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• v.42 no.3
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• pp.43-75
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• 2020

The main purpose of this study is to analyze research trend of 'business failure' from academic papers published in Asia Pacific Journal of Small Business. In this review, first, we reviewed research trend of failure, published in academic journals at abroad, explored the major topics, and set forth the framework of classification. Second, we selected and analyzed 16 Korean articles in a refined search from total 1,060 articles published in Asia Pacific Journal of Small Business from 1979 to 2019. Third, in order to understand overall research trend in Korea, additional publication search was done by online database system using keywords, and 24 other articles were selected. As a result, five research themes were identified and analyzed: (1) bankruptcy prediction, (2) emotion before and after failure, (3) costs of failure, (4) causes of failure, and (5) reentry determinants. We believe that this purposed review will offer future research issues regarding business failure.