• 사회복지연구
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• 제37호
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• pp.295-318
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• 2008

본 연구의 목적은 일반긴장이론에 근거한 청소년 지위비행 설명 모형을 검증하는 데 있다. 설문은 2007년 10월 22일부터 2007년 11월 9일까지 서울 및 경기 지역의 중고등학교 남녀청소년을 대상으로 이루어졌다. 본 연구에서는 최종 수거된 1167사례 중 응답내용이 부실한 27사례를 제외하고 총 1140사례를 이용하여 분석하였다. 우울을 매개로한 자녀학대경험과 청소년 지위비행 모형을 구조방정식을 이용하여 분석한 결과 적합도지수가 각각 .986(TLI), .994(CFI), 그리고 .032(RMSEA)으로 나타나 높은 적합도지수를 보여주었다. Aroian test를 통해 우울의 매개효과를 검증한 결과 유의미한 매개효과를 지니고 있음이 검증되었다(p<.001). 그러나 본 연구에서 주요 조건변수로 제시한 청소년의 자기통제력은 우울이 지위비행으로 이르는 경로에 유의미한 영향을 주지 않는 것으로 나타나 조건효과가 검증되지 않았다.

• 보건의료산업학회지
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• 제11권2호
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• pp.117-127
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• 2017

Objectives : This study aimed to identify factors of adolescents' cell-phone dependency using Agnew's General Strain Theory (GST) and the perspective of adolescents' micro-systems. A second aim was to verify the moderating effect of self-esteem. Methods : In total, 2,046 students who participated in a study on KCTPS mid. 1 panel 3 Wave by the National Youth Policy Institute were examined in this research. Data were analyzed through descriptive statistics, factor analysis, reliability tests, and hierarchical linear regression using SPSS Ver. 22.0. Results : The strain factors had a positive effect on adolescents' depression, and depression had a positive effect on cell-phone dependency. In addition, self-esteem had a negative moderating effect between depression and cell-phone dependency. Conclusions : Factors of cell-phone dependency were identified. The findings of the study indicate that an intervention is required to lower strain and depression and to enhance self-esteem among adolescents.

• Advances in nano research
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• 제10권3호
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• pp.271-280
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• 2021

The present work deals with an investigation on longitudinal wave propagation in nanobeams made of graphene sheets, for the first time. The nanobeam is modelled via a higher-order shear deformation theory accounts for both higher-order and thickness stretching terms. The general nonlocal strain gradient theory including nonlocality and strain gradient characteristics of size-dependency in order is used to examine the small-scale effects. This model has three-small scale coefficients in which two of them are for nonlocality and one of them applied for gradient effects. Hamilton supposition is applied to obtain the governing motion equation which is solved using a harmonic solution procedure. It is indicated that the longitudinal wave characteristics of the nanobeams are significantly influenced by the nonlocal parameters and strain gradient parameter. It is shown that higher nonlocal parameter is more efficient than lower nonlocal parameter to change longitudinal phase velocities, while the strain gradient parameter is the determining factor for their efficiency on the results.

• 오토저널
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• 제11권2호
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• pp.55-65
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• 1989

In this paper, the bellows problem under axial load were investigated. A modified energy theory, which has the improved strain energy and stress description taken from governing equation of general shells of revolution, were proposed. From the analysis, the results obtained from the modified theory were more accurate and in stable state with varing geometric parameter of bellows than those of other theory.

• 시큐리티연구
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• 제44호
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• pp.225-250
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• 2015

우리 사회에서 청소년비행을 가장 잘 설명한다고 평가받는 몇 가지 비행이론을 사용하여 한국청소년비행의 원인을 규명하려는 시도가 다방면으로 이루어져 왔다. 이런 노력의 일환으로 이 연구는 사회유대이론, 사회학습이론, 일반긴장이론, 자기통제이론을 사용하여 청소년비행의 원인을 통합적으로 밝히는 것이 그 주된 목적이었다. 특히 위의 4가지 이론 중에서 어떤 이론이 청소년비행을 가장 잘 설명하는지를 살펴보았으며, 4가지 이론에서 추출된 많은 독립변수들 중에서 어떤 요인이 14가지 청소년비행의 원인을 통계적으로 가장 유의미하게 잘 설명하는지를 파악하는 데 주력하였다. 연구결과, 사회학습이론의 설명력이 가장 높았으며, 그 다음으로 사회유대변인들 > 일반긴장이론 > 자기통제이론 순으로 나타났다. 특히 사회학습이론에서 추출된 친구와의 차별적 접촉과 정의변인은 다른 이론의 변인에 비해 가장 많은 청소년비행 변량을 설명함에 따라 사회학습이론이 가장 효율적으로 청소년비행을 잘 설명하는 것으로 드러났다. 본 연구는 청소년비행을 잘 설명하는 것으로 알려져 있는 4가지 비행이론에서 추출된 독립변인들을 바탕으로 청소년비행의 원인을 가장 잘 설명하는 변인들이 무엇인지를 파악했다는 점에서 중요한 의미를 지닌다.

• 한국학교보건학회지
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• 제29권2호
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• pp.63-70
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• 2016

Purpose: The purpose of this study was to find the factors influencing adolescents' adult media engagement. The study is based on Agnew's General Strain Theory (GST) and a micro-systemic perspective. Methods: The study examined 479 middle school freshmen who participated in the fourth wave of the Korean Children & Youth Panel Survey (KCYPS) conducted by National Youth Policy Institute. Data were analyzed through descriptive statistics, factor analysis, and reliability analysis using SPSS 22.0 Ver. Also, hypothesis testing was performed via covariance-based structure equation modeling (CB-SEM) using Amos 21.0 Ver. Results: Strain factors had positive effects on adolescent depression, and depression had a positive effect on adult media engagement. Also, cell-phone dependency had a positive mediation effect between depression and adult media engagement. Conclusion: The study's result identified the factors affecting adult media engagement. Therefore, we suggest intervention programs considering adolescents' strains, depression and cell-phone dependency to improve their health.

• Steel and Composite Structures
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• 제24권6호
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• pp.689-695
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• 2017

The constitutive relation is an important factor in analysis of confined concrete in composite structures. In order to propose a constitutive model for nonlinear analysis of confined concrete, lateral restraint mechanism of confined concrete is firstly analyze to study the generalities. As the foundation of the constitutive model, peak stress and peak strain is the first step in research. According to the generalities and the Twin Shear Unified Strength Theory, a novel unified equation for peak stress and peak strain are established. It is well coincident with experimental results. Based on the general constitutive relations and the unified equation for peak stress and peak strain, we propose a unified and convenient constitutive model for confined concrete with fewer material parameters. Two examples involved with steel tube confined concrete and hoop-confined concrete are considered. The proposed constitutive model coincides well with the experimental results. This constitutive model can also be extended for nonlinear analysis to other types of confined concrete.

• 한국안전학회지
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• 제5권2호
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• pp.58-65
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• 1990

The purpose of this study is to consider the effects of strain rate on the stress-strain behavior of sheet metal at instability. The results and conclusions obtained as follows ： 1. As the strain rate increases, the fracture pressure increases and the polar height at fracture decreases. 2. The effect of strain rate on forming limit diagram produces a general lowering of the diagram with increasing strain rate but changes according to materials and strain paths. 3. The forming limit diagram predicted by swift instability theory is comparatively inconsistent with the experimental result at high strain rates, because there is inevitable gap between them.

• Structural Engineering and Mechanics
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• 제18권5호
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• pp.565-589
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• 2004

The present paper concerns the macroscopic overall description of rheologic properties for steel wire and synthetic fibre cables under variable loading actions according to non-linear creep and/or relaxation theory. The general constitutive equations of non-linear creep and/or relaxation of tension elements - cables under one-step and the variable stress or strain inputs using the product and two types of additive approximations of the kernel functions are presented in the paper. The derived non-linear constitutive equations describe a non-linear rheologic behaviour of the cables for a variable stress or strain history using the kernel functions determined only by one-step - constant creep or relaxation tests. The developed constitutive equations enable to simulate and to predict in a general way non-linear rheologic behaviour of the cables under an arbitrary loading or straining history. The derived constitutive equations can be used for the various tension structural elements with the non-linear rheologic properties under uniaxial variable stressing or straining.

• Structural Engineering and Mechanics
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• 제61권2호
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• pp.275-282
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• 2017

The Fleck-Hutchinson theory on strain gradient plasticity (SGP), proposed in Adv. Appl Mech 33 (1997) 295, has recently been reformulated by adopting the strategy of decomposing the second order strain presented by Lam et al. in J Mech Pays Solids 51 (2003) 1477. The newly built SGP satisfies the non negativity of plastic dissipation, which is still an outstanding issue in other SGP theories. Furthermore, it explicitly shows how elastic strain gradients and corresponding elastic characteristic length scales come into play in general elastic-plastic loading histories. In this study, the relation between elastic length scales and plastic length scales is investigated by taking wire torsion as an example. It is concluded that the size effects arising when two sets of length scales are of the same order are essentially elastic instead of plastic.