• 한국군사과학기술학회지
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• 제20권2호
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• pp.238-245
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• 2017

This paper deals with the scale effects of warhead on concrete penetration. We investigated the scale effects using finite element analysis and Young's penetration equation. As the scale of penetration test decreases, the strain rate effects of target increases, and then strength of concrete target increases. This means the residual velocity and penetration depth of warhead decreases as the test model size decreases. Young's penetration equations are transformed with various penetrator mass and scale cases as a function of scale ratio. Penetration distance and residual velocity are not simply changed by the geometric scaling law.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8645-8652
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• 2016

Background: Consumption of tobacco in the form of a water pipe has recently increased, especially among young people. This study aimed to develop a scale which would be used in order to detect perceptions about the effects of water pipe smoking on health and to test its validity and reliability. Our scale named "a scale of perception about the effects of water pipe smoking on health" was developed in order to detect factors effecting the perception of adolescents about the effects of water pipe smoking on health. Materials and Methods: The sample consisted of 150 voluntary students in scale development and 750 voluntary students in the study group. Data were collected via a questionnaire prepared by researchers themselves and 5-pont Likert scale for "a scale of perception about the effects of water pipe smoking on health" which was prepared through the literature. Data evaluation was carried out on a computer with SPSS. Results: The findings of the study showed that "a scale of perception about the effects of water pipe smoking on health" was valid and reliable. Total score average of the adolescents participated in the study was $58.5{\pm}1.25$. The mean score of the ones who did not smoke water pipe ($60.1{\pm}11.7$) was higher than the mean score of the ones who smoked water pipe ($51.6{\pm}13.8$), the difference being statistically significant. Conclusions: It is established that "a scale of perception about the effects of water pipe smoking on health" was a reliable and valid measurement tool. It is also found out that individuals who smoked a water pipe had a lower level of perception of water pipe smoking effects on health than their counterparts who did not smoke a water pipe.

• 대한조선학회논문집
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• 제55권2호
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• pp.178-186
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• 2018

The scale effects on the permanent deformations and fractures of structures subjected to impact loadings have been aware by structural engineers for a long time. Experimental investigations have been performed with various structures to demonstrate the effects, but very few are directly related with marine structural elements. Furthermore, the causes of the scale effects have not clearly been answered yet. In this study, to quantify the scale effects on the permanent deflections, lateral collision tests were performed on steel unstiffened plates and the numerical analyses of the tested models were also conducted using a commercial package, Abaqus. After the substantiation of the numerical tool using the test results, a parametric study was carried out considering and neglecting the strain-rate hardening. Based upon the parametric study results, it may be concluded that the main cause of the scale effects on the permanent deflections of steel unstiffened plates subjected to lateral collision loads is the strain-rate effects.

• 자원ㆍ환경경제연구
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• 제9권5호
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• pp.973-997
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• 2000

The carbon tax is one of several measures to reduce the green-house gases emitted from burning the fossil fuels, which has been much discussed internationally. The analyses of the effects of a carbon tax on individual countries have been carried out by applying the computable general equilibrium(CGE) models, especially models with the assumption of non-existence of scale economies. However, the introduction of scale economies to CGE models changes the simulation results drastically. In this paper, two CGE models are used to compute and compare the economic and $CO_2$ reduction effects of a carbon tax, one of with is the model with scale economies and the other is without scale economies. One of main results is that the analysis using the CGE model without scale economies may underestimate the effects of a carbon tax on GDP and reducing the emission of $CO_2$.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.407-420
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• 2019

In the present work, an attempt is made to explore the effects of shear in-plane preload on the wave propagation response of small-scale plates containing nanofibers. The small-scale system is assumed to be embedded in an elastic matrix. The nonlocal elasticity is utilized in order to develop a size-dependent model of plates. The proposed plate model is able to describe both nanofiber effects and the influences of being at small-scales on the wave propagation response. The size-dependent differential equations are derived for motions along all directions. The size-dependent coupled equations are solved analytically to obtain the phase and group velocities of the small-scale plate under a shear in-plane preload. The effects of this shear preload in conjunction with nanofiber and size effects as well as the influences of the elastic matrix on the wave propagation response are analyzed in detail.

• 한국지반공학회지:지반
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• 제13권6호
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• pp.147-164
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• 1997

본 논문은 절리 암반물성의 크기효과가 암반의 불균질성 및 불연속성에 기인한다고 가정하였다. 이를 위해 대표체적요소의 개념이 적용되는 일반적인 등가물성이론을 탈피하여 불규칙적인 절리기하와 임의의 절리수 및 임의의 절리 방향성을 고려할 수 있는 등가물성이론에 대해서 연구하였다. 이론적인 연구를 바탕으로 이 이론을 실제 문제에 적용한 결과 암반요소의 크기에 따라 달라지는 물성 변화를 관찰하고, 크기효과에 관한 여러 가지 연구를 수행하였다. 특히, 수치해석적인 방법으로 크기효과를 증명하는 과정의 타당성을 입증하고 크기효과의 구체적인 원인을 알아보기 위해서 4개의 모델에 대해서 전산실험을 수행하였다. 이 실험으로부터 증명된 내용을 토대로 실제 3차원 구조물을 대상으로 크기효과 실험을 수행하였다. 이 실험 과정 중 절리의 여러 역학적인 성질들이 암반강도 및 탄성계수의 크기효과에 미치는 영향을 관찰해 보았다. 또 크기효과가 특정 절리구조에서 발생되는 것이 아니고 절리를 포함하는 모든 경우에서 발생됨을 증명하기 위해 절리 구조가 다른 두 모델을 대상으로 크기효과 실험을 수행하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2210-2213
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• 2008

In the present study, effects of degree of confinement on heat transfer characteristics of a micro-scale slot jet impinging on a heated flat plate are experimentally investigated. The effects of Reynolds numbers (Re = $1000{\sim}5000$), lateral distances (x/B = $1{\sim}10$), nozzle-to-plate spacings (Z/B = $1{\sim}20$), and degree of confinement ($B_c$/B = 3, 48) on the Nusselt number are considered. The results show that the effects of the degree of confinement on the cooling performance of the micro-scale impinging slot jet are significant at lower nozzle-to-plate spacings and higher Reynolds numbers. In addition, it is shown that the cooling performance of the micro-scale unconfined slot impinging jet is 200% higher than that of the micro-scale confined slot impinging jet.

• Structural Engineering and Mechanics
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• 제76권1호
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• pp.17-26
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• 2020

The objective of this paper is to study the deformation in transversely isotropic thermoelastic solid using new modified couple stress theory subjected to ramp-type thermal source and without energy dissipation. This theory contains three material length scale parameters which can determine the size effects. The couple stress constitutive relationships are introduced for transversely isotropic thermoelastic solid, in which the curvature (rotation gradient) tensor is asymmetric and the couple stress moment tensor is symmetric. Laplace and Fourier transform technique is applied to obtain the solutions of the governing equations. The displacement components, stress components, temperature change and couple stress are obtained in the transformed domain. A numerical inversion technique has been used to obtain the solutions in the physical domain. The effects of length scale parameters are depicted graphically on the resulted quantities. Numerical results show that the proposed model can capture the scale effects of microstructures.

• 사상체질의학회지
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• 제30권2호
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• pp.42-54
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• 2018

Objectives This study was aimed to compare effects of Yukgunja-tang (YGJT) extract granule on functional dyspepsia (FD) by sasang constitution. Methods A placebo-controlled, double-blind, randomized, two-center trial was performed. We obtained 3D face images of FD patients participating in this study using face-only scanner and classified them into two types as narrow face and wide face by 3D facial shape diagnosis system (3-FSDS). 96 subjects (48 subjects per type) were enrolled and were randomly allocated into treatment or control groups in a 2:1 ratio. YGJT extract granule or placebo were administered to each group during the 8 week treatment period. One of sasang constitutional specialist diagnosed their constitutions by referring to questionnaires and 3D face images. The primary outcome was total dyspepsia symptom scale (TDS scale), the secondary outcomes were single dyspepsia symptom scale (SDS scale), visual analog scale (VAS) and so on. This trial was registered with clinical research information service identifier: KCT0001920, 15 May, 2016. Results In the Taeeumin treatment group, the TDS scale was significantly decreased after 8 weeks compared to the control group (t=2.331, p=0.025) and the SDS scale also significantly decreased. (t=2.042, p=0.048). The specific effects of the YGJT extract granule without the placebo effect on the Taeeumin with functional dyspepsia were 30.61% in TDS scale and 28.33% in SDS scale. Conclusions The effects of Yukgunja-tang extract granule on functional dyspepsia was different according to Sasang constitution. So the constitution should be considered in randomized controlled trials using herbal extract granules.

• Wind and Structures
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• 제38권4호
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• pp.261-275
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• 2024

Before performing an experimental study on the downburst-generated wave, it is necessary to examine the scale effects and corresponding corrections or compensations. Analysis of similarity is conducted to conclude the non-dimensional force ratios that account for the dynamic similarity in the interaction of downburst with wave between the prototype and the scale model, along with the corresponding scale factors. The fractional volume of fluid (VOF) method in association with the impinging jet model is employed to explore the characteristics of the downburst-generated wave numerically, and the validity of the proposed scaling method is verified. The study shows that the location of the maximum radial wind velocity in a downburst-wave field is a little higher than that identified in a downburst over the land, which might be attributed to the presence of the wave which changes the roughness of the underlying surface of the downburst. The impinging airflow would generate a concavity in the free surface of the water around the stagnation point of the downburst, with a diameter of about two times the jet diameter (D_jet). The maximum wave height appears at the location of 1.5D_jet from the stagnation point. Reynolds number has an insignificant influence on the scale effects, in accordance with the numerical investigation of the 30 scale models with the Reynolds number varying from 3.85 × 10⁴ to 7.30 × 10⁹. The ratio of the inertial force of air to the gravitational force of water, which is denoted by G, is found to be the most significant factor that would affect the interaction of downburst with wave. For the correction or compensation of the scale effects, fitting curves for the measures of the downburst-wave field (e.g., wind profile, significant wave height), along with the corresponding equations, are presented as a function of the parameter G.