• 가족자원경영과 정책
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• 제26권1호
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• pp.27-42
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• 2022

본 연구에서는 학업중단 청소년 자녀의 학교복귀 선택에 영향을 미치는 자원에 관해 살펴보고자 2013년부터 2017년까지의 총 5차년도 2,553명의 학업중단 청소년 패널 자료를 활용하였다. 2012년 7월 이후 정규 중·고등학교 학업중단 경험이 있는 청소년을 대상으로 학교복귀에 영향을 미치는 자원을 검증하기 위해 학업중단 청소년의 가족자원을 비롯하여 개인의 심리·정서자원 및 사회관계자원에 초점을 두고 분석하였다. 자료 분석 방법은 t-test와 교차분석, 위계적 로지스틱 회귀분석을 사용하였다. 본 연구의 주요 결과는 다음과 같다. 첫째, 청소년 자녀의 학교복귀 선택에 영향을 주는 자원 중 인구사회학적 변인은 이사횟수였다. 둘째, 청소년 자녀들의 학교복귀에 영향을 미치는 심리·정서자원은 우울, 충동성과 함께 학업을 중단한 현재에 대한 긍정적 인식의 정도가 낮고 우리 사회가 학력에 대한 차별이 심하다고 지각하는 점이 학교복귀 선택에 작용하였다. 셋째, 가족자원으로는 가족형태와 부모애착의 하위요인 중 경제적 지지 측면이 유의미한 것으로 나타났다. 넷째, 도움을 주는 사회관계자원으로서 멘토 여부가 사회자원으로 유의미한 영향을 미치는 것으로 나타났다. 본 연구를 토대로 학업중단 청소년 자녀들의 학교복귀 선택에 영향을 미치는 긍정적 가족자원을 밝혀 학업중단 청소년 자녀를 둔 부모들에게 지지적인 가족자원의 방향성을 제시하였다는 점에서 의의가 있다.

• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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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.

• 한국보건간호학회지
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• 제29권3호
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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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• 제34권4호
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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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• 제24권3호
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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.

• 한국항공우주학회지
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• 제44권1호
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• pp.23-32
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• 2016

초고속으로 비행하는 물체의 항력을 줄이기 위해 노즈콘으로부터 제트를 분사하는 다양한 연구가 진행되고 있다. 본 연구에서는 항력감소의 기초자료와 핵심 변수를 파악하기 위해서 미국의 항력감소용 분사 제트 연구 동향을 조사하고 요약하였다. 연구에 활용한 노즈콘 모델의 형상은 반구 실린더, 잘린 콘, 재돌입 캡슐이었으며, 각 모델의 시험조건에 대해 정리하였다. 항력감소의 핵심 변수는 분사제트의 마하수, 질량유량, 압력비율이다. 항력감소효과는 주어진 조건에 따라 다양한 결과를 보였지만, 최대 40~50% 정도까지 항력이 감소하였다.

• 항공우주시스템공학회지
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• 제13권1호
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• pp.18-28
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• 2019

초고속 비행체는 발사 및 재진입 시 공력 가열에 의해 높은 열 하중을 받는다. 초고속 비행체의 외피 구조물인 열방어 시스템 패널은 기계적으로 구속되어 있기 때문에 고온 가열 시 열 좌굴이 발생할 수도 있다. 이는 초고속 비행체의 유동장에 변화를 주어 공력특성을 불안정하게 한다. 따라서 열방어 시스템 패널은 초고속 비행에 의한 공력가열 시 비행안정성을 유지하기 위해 열 좌굴을 방지하도록 설계되어야 한다. 본 논문에서는 운용 시 안팎에 큰 온도차가 존재하는 열방어 시스템 패널에 대해 유한차분법을 사용하여 열전달 특성을 분석하였으며, 리츠 법을 사용하여 열 좌굴 특성에 대한 근사적 모델을 제안하였다. 또한 정의된 근사적 모델의 정확도를 검증하기 위해 유한요소 해석결과와 비교하였다. 마지막으로, 수립된 근사 기법을 바탕으로 열방어 시스템 패널의 좌굴 발생 온도에 대한 매개변수 분석을 수행하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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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.

• 중소기업연구
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• 제42권3호
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• pp.43-75
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• 2020

본 연구는 중소기업학회에서 편찬한 '중소기업연구'에 게재된 논문을 분석하여 사업실패의 연구동향을 알아보는데 있다. 이를 위하여, 첫째, 문헌고찰을 통해, 해외의 연구동향과 주요 연구 주제를 탐색하고, 본 연구를 위한 분석의 틀을 작성하였다. 둘째, 1979년부터 2019년에 이르기까지, 중소기업연구에 편찬된 총 1,060편의 논문 중, 실패와 관련된 16편을 선정하고 분석하였다. 세 번째, 중소기업연구 이외의 한국의 실패 연구동향을 알아보기 위해, 키워드 분석으로 24편을 추가로 선정하여 분석하였다. 본 논문에서는 실패 연구의 동향을 총 5가지 큰 주제로 구분하여 분석하였다. (1) 실패예측, (2) 실패 전·후 감정, (3) 감정 이외 실패 비용, (4) 실패 원인, (5) 재창업 결정 및 성공요인이다. 기존연구가 가지는 함의를 살펴봄으로써, 향후 실패분야의 연구방향을 제시하고 있다.