• 아동학회지
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• 제24권1호
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• pp.99-108
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• 2003

가족소득은 어머니의 교육수준과 밀접하게 관련되어 있다는 이전의 많은 연구들에 근거하여, 세대간 교육수준 순환의 가정하에 두 문제점들이 제기되었다 : (a) 어머니의 교육수준이 학령기 아동의 학업성적을 예측할 수 있는가? (b) 만약 예측되어진다면, 교육수준의 역순환은 부모의 경제적 수준상태에 의하여 이러한 영향을 상쇄시킬 수 있는가? 아동발달에 대한 보다 나은 이해를 추구하고자 종단적 데이타를 사용하였다. 즉, 아동이 2살일 때 부모의 경제적 수준상태가 측정되어졌으며, 아동들이 초등학교 1학년이 되었을 때 다시 담임선생에 의한 아동의 학업성적이 측정되어졌다. 이러한 데이타는 Structure equation modelling analyses 통계분석법을 이용하여, 본 연구는 어머니의 교육수준이 아동의 초등학교 1학년 때의 학업성적을 예측한다는 것을 검증하였으며, 이러한 관계는 부모의 경제적 수준상태에 의하여 상쇄될 수 있다는 것이 밝혀졌다. 그러므로, 이 연구는 어머니의 저교육수준에 따른 아동의 열등한 학업성적 순환고리는 부모의 경제적 수준의 영향에 의해 깨어질 수 있다는 가능성을 밝혀주었으며, 아동기 발달의 한 경로를 분명히 제시하였다.

• 대한전자공학회논문지
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• 제21권5호
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• pp.90-99
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• 1984

양면에서 텅스텐 램프를 조사하는 실리콘 재결정시의 SOI(silicon-on-insulator) 다층구조에 대한 1차원적 온도 및 열원(열원)의 분포를 SOR(successive over-relaxation)방법을 이용하여 정상상태의 열방정식의 해로부터 구하였다. 열원의 분포는 광원의 스펙트럼, SOI sample 내부 계면에서의 다중반사, 광흡수 계수의 온도, 주파수 의존성 등을 고려하여 구하였으며, 열 방정식의 경계조건이 되는 wafer의 전면과 후면의 온도는 혹체복사 조건으로부터 구하였다. 내부계면에서는 전도열속(conduction heat flux)과 복사열속(radiation heat flux)에 의한 연속조건을 만족하도록 하였다. 본 문제에서의 온도분포와 열원의 분포는 상호간에 큰 영향을 주게 되므로, 두가지 변수가 일치되는 값을 보일 때까지 iteration을 계속하였다. Pyrometer을 이용하여 측정한 wafer 전면의 온도는 약1200°K이었고 이때의 simulation 결과는 1120°K 정도로 나타났다.

• 지구물리
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• 제2권2호
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• pp.123-134
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• 1999

상부맨틀이나 하부지각의 고전도층(HCL)에서 나타나는 고이방성은 MT 탐사에 큰 영향을 미칠 수 있다. 본 연구에서는 고이방성 매질이 MT 반응에 미치는 영향을 고찰하기 위한 모델연구를 수행하였다. 각각의 균질한 암체의 전기적 성질은 대칭적인 전기전도도 텐서로 주어지며 모델링을 위한 기본방정식은 전기장과 자기장 성분이 결합되어진 주파수 영역 분산 방정식으로 주어진다. 이방성 매질에서는 전기장의 왜곡에 의해 항상 4성분의 임피던스가 존재하며, 2차원 구조에서는 대각선 성분, 특히 YY성분의 임피던스가 증가한다. 어떤 경우에는 서로 이방성 주향이 다른 매질의 상호작용에 의해 TM 모드의 위상이 90° 이상으로 증가하고 겉보기비저항이 낮아지는 현상이 발생한다. GB 분리법은 광역적인 반응을 추출하는데 이용될 수 있으나, 심부의 이방성의 영향을 크게 받는다. 이상의 모델연구의 결과를 BC87자료에 적용하여 현장자료에서의 이방성 효과를 고찰하였다.

• Computers and Concrete
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• 제21권6호
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• pp.717-726
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• 2018

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use of nano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that $SiO_2$ nanoparticles can improve the mechanical behavior of concrete. Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton's principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load. The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method. The effects of different parameters such as $SiO_2$ nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluid pressure and earthquake intensity are discussed on the seismic response of the structure. From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of $SiO_2$ nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.

• Computers and Concrete
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• 제24권2호
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• pp.125-135
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• 2019

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use of nano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that SiO2 nanoparticles can improve the mechanical behavior of concrete. Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton's principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load. The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method. The effects of different parameters such as SiO2 nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluid pressure and earthquake intensity are discussed on the seismic response of the structure. From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of SiO2 nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.

• 한국구조물진단유지관리공학회 논문집
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• 제14권2호
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• pp.89-96
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• 2010

이산화탄소에 의해 열화된 콘크리트 구조물의 보수 후 잔존수명을 평가할 때 보수재의 효과를 고려하기 위해 본 연구에서는 탄산화에 의해 열화를 받은 콘크리트 부재의 보수 후 재열화과정을 Fick's 확산(diffusion) 제1법칙을 이용하여 모델링함으로써 단면복구재에 의해 보수된 콘크리트 부재의 독특한 상황을 고려한 합리적인 예측식을 제시하였다. 연구결과는 보수재의 이산화탄소 확산 프로파일과 기존 구체콘크리트의 탄산화된 부분의 이산화탄소 확산 프로파일을 효과적으로 모델링할 수 있음을 보여줬다. 제시된 평가모델식에 대한 검증예제를 통해 보수재의 이산화탄소 확산지연효과를 확인할 수 있었으며 보수된 콘크리트 구조물의 보수 후 잔존수명을 객관적이고 수치계산적인 방법으로 평가할 수 있었다.

• Advances in nano research
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• 제14권1호
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• pp.1-15
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• 2023

Driven by the scaling down of transistor node technology, graphene became of interest to many researchers following the success of its fabrication as graphene nanoribbons (GNRs). However, during the fabrication of GNRs, it is not uncommon to have defects within the GNR structures. Scaling down node technology also changes the modelling approach from the classical Boltzmann transport equation to the quantum transport theory because the quantum confinement effects become significant at sub-10 nanometer dimensions. The aim of this study is to examine the effect of Stone-Wales defects on the electronic properties of GNRs using a tight-binding model, based on Non-Equilibrium Green's Function (NEGF) via numeric computation methods using MATLAB. Armchair and zigzag edge defects are also implemented in the GNR structures to mimic the practical fabrication process. Electronic properties of pristine and defected GNRs of various lengths and widths were computed, including their band structure and density of states (DOS). The results show that Stone-Wales defects cause fluctuation in the band structure and increase the bandgap values for both armchair GNRs (AGNRs) and zigzag GNRs (ZGNRs) at every simulated width. In addition, Stone-Wales defects reduce the numerical computation DOS for both AGNRs and ZGNRs. However, when the lengths of the structures increase with fixed widths, the effect of the Stone-Wales defects become less significant.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권4호
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• pp.209-215
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• 2001

In this paper a method for analysis and modelling of coplanar transmission interconnect lines that are placed on top of silicon-silicon oxide substrates is presented. The potential function is expressed by series expansions in terms of solutions of the Laplace equation for each homogeneous region of layered structure. The expansion coefficients of different series are related to each other and to potentials applied to the conductors via boundary conditions. In the plane of conductors, boundary conditions are satisfied at $N_d$ discrete points with $N_d$ being equal to the number of terms in the series expansions. The resulting system of inhomogeneous linear equations is solved by matrix inversion. No iterations are required. A discussion of the calculated line admittance parameters as functions of width of conductors, thickness of the layers, and frequency is given. The interconnect capacitance and conductance per unit length results are given and compared with those obtained using full wave solutions, and good agreement have been obtained in all the cases treated

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.351-363
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• 2020

The objective of this paper is to explore how board gender diversity affects corporate sustainability performance. Therefore, this paper examines the direct association between board gender diversity with corporate sustainability performance and the mediation effect of enterprise risk management (ERM) on this association. The study employed a cross-sectional survey method. Data were collected from annual reports, websites, and through the questionnaires that were distributed to Chief Financial Officers (CFOs) of all the listed companies of Dhaka Stock Exchange, Bangladesh. The partial least square technique of Structural Equation Modelling (SEM) approach was employed for data analysis. The result did not find support for the direct association between board gender diversity and sustainability performance in Bangladesh context. This implies that contextual factors, such as, male-dominant board, appointment of female directors based on family ties, lack of education and expertise etc. may discount gender diversity direct influence on sustainability performance. However, the study finds strong support for the mediating role of ERM use within the corporate structure. Further analysis of indirect effect suggests that ERM use mediates the relationship of board gender diversity and sustainability performance in full. This implies that in the Bangladesh context effective use of ERM is highly recommended.

• The Journal of Asian Finance, Economics and Business
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• 제7권2호
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• pp.309-316
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• 2020

This study aims to measure the relationship between corporate social responsibility (CSR) and affective commitment (ACO), normative commitment (NCO), and organizational performance in food processing enterprises (FPEs) in the Mekong River Delta, Vietnam. To test the initial model proposed in this paper, a total of 422 owners, directors and managers of FPEs were interviewed from some provinces in the Mekong River Delta. The method of exploratory factor analysis (EFA) is initially employed, then confirmatory factor analysis (CFA) and structure equation modelling (SEM) are used. The results of SEM showed that higher affective commitment was correlated with normative commitment. The results showed that four aspects of CSR toward employees, customers, environment and legal are significant factors. As a result, ACO and NCO act as mediators between CSR and organizational performance. This finding provides strong evidence of the important role of CSR to support positive impacts on ACO, NCO, and orgazational performance (OP). In addition, the success of the organizational performance is also found by contributions of CSR and NCO to its changes. Although ACO does not directly affect performance, it has a positive effect on the NCO. Therefore, it is necessary to enhance the implementation of CSR to promote implementation of organizational commitments.