• 한국해양공학회지
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• 제32권5호
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• pp.333-340
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• 2018

This paper addresses the concept of the representative mean position, which was devised to improve the numerical efficiency of a time domain fatigue analysis of a mooring chain. To investigate the influence of an artificial offset of the floater on the fatigue of the mooring chain, a parametric study was performed on the moored FPSO under various combinations of offsets and environmental conditions. Tension time histories were calculated using the de-coupled analysis method, and fatigue damages were calculated to determine the influence of the offset. The parametric study was extended to a more realistic case to determine the actual effect of the representative mean position, where a comparison was made between the two different analysis results, one using the representative mean position and the other one using the actual mean position. It was confirmed that the application of the representative mean position guaranteed the conservatism of the fatigue damage with the enhanced numerical efficiency in the time domain fatigue analysis.

• 아동학회지
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• 제35권2호
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• pp.1-23
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• 2014

The purpose of this research was to investigate the most critical variables in the school adjustment of youth. In addition, this research assessed the impact of variables according to the categorization of individual, family, and school domains. To acquire the effect sizes, published studies between 1990 and 2012 were reviewed systematically and synthesized by meta-analysis. The major findings were as follows. First, this study identified a total of 34 variables which can have an influence on the school adjustment of youth and confirmed that 24 of those variables are significant. The most crucial variable that can influence school adjustment is that of a teacher's support. The next most important variables are self-resilience, relationships with friends, and self-efficiency. Focusing on the categorized elements, self-resilience is the most critical variable in the individual domain, the parent-child relation is the most crucial variable in the family domain, and a teacher's support is the most powerful variable in the school domain. Based on these results, this study suggested a number of the indispensable components in interventions to improve the youth's adjustment in school.

• 한국진공학회지
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• 제12권S1호
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• pp.36-39
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• 2003

Field-domain dynamics and current self-oscillations are theoretically studied in quantum-well (QW) negative-effective-mass (NEM) $p^{+}pp^{+}$ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the p-base. We have accurately considered the scattering contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon. It's indicated that, both the applied bias and the doping concentration largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM $p^{+}pp^{+}$ diode with a submicrometer p-base. The complicated field-domain dynamics is presented with the applied bias as the controlling parameter.

• 대한전자공학회논문지TC
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• 제44권11호
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• pp.42-47
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• 2007

본 논문은 초광대역 임펄스를 이용한 지반탐사 레이더에 있어서 지면 및 지면과 안테나 사이의 간격에 따른 임펄스 전파에 미치는 영향을 기술한다. 영향 연구를 위해 평판형 초광대역 다이폴 안테나를 개발하였다. 우선, 수치해석 방법을 이용하여 지면의 유전율 변화 및 안테나와 지면 사이의 간격에 대한 영향을 시뮬레이션하였다. 결과를 비교하기 위하여 실제 모래 및 수분이 포함된 토양으로 구성된 시험장을 제작하여, 개발된 다이폴 안테나를 사용하여 주파수 영역에서의 지면의 변화 및 안테나와 지면의 간격 차이에 의한 주파수 영역에서의 투과 특성을 조사하였다. 역 퓨리에 변환을 이용하여 주파수 영역에서 시뮬레이션 및 측정된 투과 특성을 시간 영역에서의 임펄스 응답 특성을 구하였다. 시뮬레이션과 측정 결과로부터 지면의 유전율이 높을수록 안테나와 지면과의 간격 변화가 클수록 최대 투과값이 생기는 주파수가 높아졌고, 투과 계수도 증가하였다. 시간영역에서는 유전율이 높을수록 지표면의 직접 반사에 의해 수신되는 신호가 크게 증가하였고, 수신 신호의 모양은 완전히 변형되었다. 또한, 지면과 안테나 사이의 간격 변화로 시간영역 반사 신호의 첨두치의 시간 위치가 변경됨을 알 수 있었다.

• Nano
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• 제13권12호
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• pp.1850149.1-1850149.10
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• 2018

Ferroelectric particles have been applied in the photocatalytic field because the spontaneous polarization results in the internal electric field, which can accelerate the separation and migration of photogenerated carriers. In this study, the $BaTiO_3$ (BT) fibers are synthesized by electrospinning. The BT fibers calcined above $800^{\circ}C$ exhibit a strong ferroelectric property, which is verified by a typical butterfly-shaped displacement-voltage loop. It is found that the BT fibers with the single-domain structure exhibit better photocatalytic performance than that with the multi-domain configuration. When the single-domain transforms into multi-domain, the integrated internal electric field correspondingly breaks up, inducing that the internal electric field might cancel each other out and diminish the separation of photogenerated carriers. Also, the Au nanoparticles can improve the photocatalytic activity further on account of the surface plasmon resonance. Therefore, it is suggested that Au nanoparticles decorated on ferroelectric BT nanomaterials are promising photocatalysts.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.507-512
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• 2007

A new type of extended element-free Galerkin method (XFEM) is proposed on this paper. The blending region which was inevitable in the extended finite element method and the extended meshfree method is removed in this method. For this end, two different techniques are developed. The first one is the modification of the domain of influence so that the crack tip is always placed on the edge of a domain of influence. The second method is the use of the Lagrange multiplier. The crack is virtually extended beyond the actual crack tip. The virtual extension was forced close by the Lagrange multiplier. The first method can be applied to two dimensional problems only Lagrange multiplier method can be used in both two and three dimensions.

• 한국정밀공학회지
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• 제9권1호
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• pp.126-136
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• 1992

In this paper, a simple structured feedback compensation scheme for a electro-hydraulic servo system to keep the response characteristics unchanged regardless of the load variation is proposed. In electro-hydraulic servo system, servovalve is most important control element. But the relation between input corrent and output flowrate of the servovalve has properties as follows; firstly, in spite of constant input current, output flowrate decreases as load pressure increases, secondly, according to frequency response of typical servovalve, the characteristics of gain and phase shift is something like 2'nd order system. Load pressure feedback compensation method has been applied to eliminate the first influence, the second influence has been improved by phase lead compensation method. As a result of above compensation methods, regardless of variation load condition, spring and inertia load, the compensation scheme has been verified to be effective within the range of frequency less than 25Hz by static response and dynamic response in time domain and frequency domain through experiments.

• Structural Engineering and Mechanics
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• 제31권6호
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• pp.717-735
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• 2009

The present problem is concerned with the study of deformation of micropolar thermoelastic medium with voids under the influence of various sources acting on the plane surface. The analytic expressions of displacement components, force stress, couple stress, change in volume fraction field and temperature distribution are obtained in the transformed domain for Lord-Shulman (L-S) theory of thermoelasticity after applying the integral transforms. A numerical inversion technique has been applied to obtain the solution in the physical domain. The numerical results are presented graphically. Some useful particular cases have also been deduced.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.357-364
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• 2006

The meshfree method is extended by the local partition of unity method to model the cohesive cracks in two dimensional continuum The shape function of a particle whose domain of influence is completely cut by a crack is enriched by the step enrichment function. If the domain of influence contains a crack tip inside, it is enriched by the branch enrichment function without the stress singularity. It is found that this method is more accurate and converges faster than the meshless methods for LEFM cracks based on the visibility concept Several staic and dynamic examples are solved to verify the method.

• 가정과삶의질연구
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• 제9권2호
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• pp.191-207
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• 1991

The purpose of this study is to investigate the degree of socialization of household work and to analyze the influence of demographic and psycho-social variable on socialization of household work. For the purpose of this study, questionnaires were administrated to 314 housewives in Pusan. For the statistical analysis were as follows; 1)The degree of socialization in the domain of food showed significant difference by number of family, number of children, housewife's age, housewife's education, husband's education, income and sex-role attitude. The degree of socialization in the domain of housing showed significant difference by family pattern, housewife's education, husband's education, state of housewife employment. husband's occupation , income and sex-role attitude. The degree of socialization in the domain of clothing showed significant difference by housewife's age, housewife's education, husband's education , state of housewife employment. husband's occupation, income and sex-role attitude. The degree of socialization in the domain of family management showed significant difference by number of children, housewife's age. state of housewife employment, income, period of marriage life and sex-role attitude. The degree of socialization in the domain of home management showed significant difference by housewife's education, husband's occupation, sex-role attitude and share of household work. 2) The socialization in the domain of food was influenced husband's education, income, housewife's education and sex-role attitude. The socialization in the domain of housing was influenced husband's education, income, housewife's occupation and sex-role attitude. The socialization in the domain of clothing was influenced husband's education, income. housewife's occupation and sex-role attitude. The socialization in the domain of family management was influenced husband's education, shave of household work. and sex-role attitude. The socialization in the domain of home management was influenced husband's education, shave of household work, and sex-role attitude.