• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.351-358
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• 2001

In this study, for the investigation of effects of several parameters, such as fluid mesh boundary size, cylinder or block shape, dimensions of depth, breadth and length at free suface, and fluid mesh element size to the depth direction on a reliable shock response of finite element model under underwater explosion with consideration of the bulk cavitation analysis of a simplified surface ship was carried out using the LS-DYNA3D/USA code. The shock responses were not much affected by the fluid mesh parameters. The computational time was greatly dependent on the number of DAA boundary segments. It is desirable to reduce the DAA boundary segments in the fluid mesh model, and it is not necessary to cover the fluid mesh boundary to or beyond the bulk cavitation zone just for the concerns about an initial shock wave response. It is also the better way to prefer cylinder type of the fluid mesh model to the block one.

• Steel and Composite Structures
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• 제47권4호
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• pp.539-550
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• 2023

Owing to the obstruction of section steel on the moisture diffusion in concrete, the existing shrinkage prediction models overestimate the time-dependent deformation of steel reinforced concrete (SRC) columns, particularly for the SRC columns with enclosed section steels. To solve this issue, this study deals with analytical and experimental studies on the drying shrinkage for this type of column. First, an effective method for predicting the drying shrinkage of concrete based on finite element model is introduced and two crucial parameters for simulation of humidity field are determined. Then, the drying shrinkage of SRC columns with enclosed section steels is investigated and two modified parameters, which depend on the ambient relative humidity and the ratio of section steel size to column size, are introduced to the B3 model. Finally, an experiment on the shrinkage deformation of SRC columns with enclosed section steels is conducted. Comparing the predicted results with the experimental ones, it demonstrates that the modified B3 model is quite reasonable.

• International Journal of Advanced Culture Technology
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• 제9권1호
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• pp.1-6
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• 2021

This study aims to test the relationship between the change in population size and population composition and crime changes. The analytical model includes variables representing changes in population size and population composition, three dependent variables for crime changes, and three control variables. Changes in popuvpdllation size and population composition are measured by indicators such as population size, gender, age groups, and immigrants and foreign workers, and crime changes by felonious, burglary, and violent crime volumes. The sample includes 154 cities and counties in South Korea, and the sample period is from 2010 to 2017. As a result of the analysis, I examine that the decrease in the number of young and men are likely to lead to a decline in felonious and violent crimes, but a high rate of the elderly and the increasing racial heterogeneity are likely to accelerate the fear and worries about crimes.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.250-251
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• 2006

It is known that powder characteristics including particle size and distribution, particle shape, and chemical composition are important parameters which influence direct laser sintering of metal powders. In this paper, we introduce a first order kinetics model for densification of steel powders during laser sintering. A densification coefficient (K) is defined which express the potential of different powders to be laser-sintered to a high density dependent on their particle characteristics.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.161-169
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• 2020

The condition of mining companies that exploit natural resources in their business processes underline this research to emphasize on social and environmental issues. After twelve years of government regulation on CSR practices, this study investigates the factors that influence mining companies in disclosing information about corporate social responsibility based on legitimacy, stakeholders, and agency theory. Thus, independent variables are foreign ownership, company size, leverage, and the board of commissioners. The dependent variable is the corporate social reporting disclosure that is measured using GRI indexing. For sampling, we have used thirty-four Indonesian mining companies listed in IDX during the 2014-2018. out of which only fifty-two companies meet the sample criteria. All data should pass the classical assumption test to get the best estimator. Multiple linear regression is used to test the hypothesis, and the results show that the model is good, and can explain 60% of the dependent variable. Based on F-test, all four variables affect CSR practices simultaneously. The findings of this study suggest that foreign ownership and firm size influences CSR disclosure in a positive direction. However, this study did not support the hypothesis that leverage negatively affects CSR disclosure and board size measures positively affect CSR disclosure.

• Advances in nano research
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• 제4권2호
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• pp.65-84
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• 2016

This paper investigates the buckling behavior of shear deformable piezoelectric (FGP) nanoscale beams made of functionally graded (FG) materials embedded in Winkler-Pasternak elastic medium and subjected to an electro-magnetic field. Magneto-electro-elastic (MEE) properties of piezoelectric nanobeam are supposed to be graded continuously in the thickness direction based on power-law model. To consider the small size effects, Eringen's nonlocal elasticity theory is adopted. Employing Hamilton's principle, the nonlocal governing equations of the embedded piezoelectric nanobeams are obtained. A Navier-type analytical solution is applied to anticipate the accurate buckling response of the FGP nanobeams subjected to electro-magnetic fields. To demonstrate the influences of various parameters such as, magnetic potential, external electric voltage, power-law index, nonlocal parameter, elastic foundation and slenderness ratio on the critical buckling loads of the size-dependent MEE-FG nanobeams, several numerical results are provided. Due to the shortage of same results in the literature, it is expected that the results of the present study will be instrumental for design of size-dependent MEE-FG nanobeams.

• Advances in materials Research
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• 제7권1호
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• pp.1-16
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• 2018

Thermal bifurcation buckling behavior of fully clamped Euler-Bernoulli nanobeam built of a through thickness functionally graded material is explored for the first time in the present paper. The variation of material properties of the FG nanobeam are graded along the thickness by a power-law form. Temperature dependency of the material constituents is also taken into consideration. Eringen's nonlocal elasticity model is employed to define the small-scale effects and long-range connections between the particles. The stability equations of the thermally induced FG nanobeam are derived via the principal of the minimum total potential energy and solved analytically for clamped boundary conditions, which lead for more accurate results. Moreover, the obtained buckling loads of FG nanobeam are validated with those existing works. Parametric studies are performed to examine the influences of various parameters such as power-law exponent, small scale effects and beam thickness on the critical thermal buckling load of the temperature-dependent FG nanobeams.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.488-494
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• 2001

Many literatures, so far, have concentrated on approaches employing dependent coordinates set resulting in computational burden of constraint forces, which is needless in many cases. Some researchers developed methods to remove or calculate it efficiently. But systematic generation of the motion equation using independent coordinates set by Kane's equation is possible for any closed loop system. Independent velocity transformation method builds the smallest size of motion equation, but needs practically more complicated code implementation. In this study, dependent velocity matrix is systematically transformed into independent one using dependent-independent transformation matrix of each body group, and then motion equation free of constraint force is constructed. This method is compared with the other approach by counting the number of multiplications for car model with 15 d.o.f..

• The Journal of Asian Finance, Economics and Business
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• 제9권4호
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• pp.213-228
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• 2022

This paper investigates the association between key corporate governance characteristics and the performance of general insurance businesses listed on the Saudi stock exchange (TADAWUL). The methodology for the study is based on a pooled data collection for 11 Saudi general insurance companies from 2011 to 20. The linear regression model and the logarithm regression model are suggested to assess the relationship between performance and corporate governance characteristics. The dependent variable is firm performance measured using ROA, ROE, and Tobin's Q. The independent variables are corporate governance variables consisting of a complete set of board and audit committee characteristics. Insurer-specific control variables are introduced. The empirical results reveal that the characteristics of corporate governance influence the performance of insurance companies. In particular, the board size, board's tenure, the proportion of independent directors in the board, audit committee size, audit committee meeting frequency, and proportion of health insurance premiums have a positive impact. However, audit committee independence, size of the company, and proportion of reinsurance premiums have a negative impact on the performance of the Saudi general insurance companies. Finally, the empirical results indicated also that there is an unclear relationship between the performance and board meeting frequency, compensations of the Board, and the average age of the Board.

• Nuclear Engineering and Technology
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• 제17권2호
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• pp.116-128
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• 1985

본 논문에는 이산화 우라늄 소결체의 노내고밀화현상을 온도와 미세구조의 함수로 정화하게 예측할 수 있는 기계론적 이론 모형이 개발.기술되어있다. 이 모형은 $UO_2$ 소결체의 결정 입계내에서 공극(vacancy)이 생성 이동되고, 결정입계에서 공극이 소멸되는 현상을 고려하고 있으며, 이 과정에서 일어나는 고밀화의 크기가 핵분열율, 조사시간, $UO_2$ 소결체밀도, 기공 크기의 분포, 결정입크기 및 온도의 함수로 기술되어 있다. 본 모형의 기공 수축에 대한 결과식은 Assmann과 Stehle가 유도한 4개의 온도 영역에 대한 결과식과는 상이한 것으로서, 소결체의 모든 온도 영역에 직접 적용된다. 본 모형에 의한 노내고밀화 크기의 예측치는 실험자료와 아주 잘 일치하며, KEFDA 전산코드에 사용된 경험적 실험 연산식에 비하여 고밀화의 경향과 절대치를 보다 정확히 예측한다.