• 지역사회간호학회지
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• 제15권3호
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• pp.471-482
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• 2004

Purpose: This study intended to identify personality factors and related problematic behaviors of adolescents who drink alcohol in order to provide basic data for developing nursing programs. Methods: The data were collected from October to December 2002 from 1.080 high school students in Seoul. The Revised Cloninger's Tri-dimensional Personality Questionnaire (TPQ) was used to measure their personalities. The alcohol expectancy was measured using the tool revised by Cho (1999) and stress levels were measure using a stress tool revised Cho (1998). The data were analyzed with SPSS Windows using Chi square test. independent t-test. and logistic regression analysis. Results: 1. The percentage of fathers who drank was 79.8%. mothers. 54.3%. and friends. 54.3%. The alcohol expectancy averaged 6.36 while the stress levels were 132.79. 2. It was found that there are significant differences (p<.001) in problematic drinking behaviors according to the following variables: second year high school students among all grade variables, more monthly pocket money for the amount of money variables, the group of students who smoked in the case of the variable related to smoking, spending more time using the Internet for the Internet use variable, and having friends who drink 65.6% for the friend variable. The alcohol expectancy scale of those students who showed problematic drinking behaviors was higher than that of those who did not. There are four family-related stress subscales, and there was a significant difference among them (p<.05). Among the personal characteristics, the group who displayed problematic drinking behaviors seeks new experiences and reward dependence more than the group who did not exhibit those behaviors, and there were significant differences between the two groups (p<.001). 3. When the socio-demographic and drinking-related factors were controlled, the tendency of seeking new experiences increased the risk of problematic behaviors 1.07 times (p<.05). Compared to the non smoking group, the smoking group was found to have a 5.06 time (p<.001) greater risk of displaying problematic drinking behaviors. In comparison with the non drinking group, the drinking group was also found to have a 5.31 time (p<.001) greater risk of exhibiting problematic drinking behaviors. The group with high alcohol expectancy scores was significantly different from the group with the no alcohol expectancy, showing a 1.26 time (p<.00l) greater risk of problematic drinking behaviors. Conclusions: Based on these results, the problematic drinking behaviors were connected with alcohol expectancies, friends and personality types. Therefore, we should develop an alcoholic prevention program for adolescence considering the above results.

• 보건교육건강증진학회지
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• 제22권4호
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• pp.73-90
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• 2005

Objectives: Smokers who had failed to quit smoking were frequently reported that life stress mostly interrupted their abstention. Stress vulnerability model for smoking cessation has been considered, and most of contemporary smoking cessation programs help smokers develop coping strategies for stressful situations. This study aims to investigate the appropriate coping styles for stress of abstention from smoking. The result of investigating the relationship between abstention following smoking cessation program and coping styles would suggest useful information for those who want to stop smoking and health practitioners who help them. Methods: Participants were 69 smokers (62 males, 7 females) participated in a hospitalized smoking cessation program, whose mean age was 44.89 (SD=9.61). Participants took medical test and completed questionnaires and psychological tests including: Fagerstrom Test for Nicotine Dependence and Multidimensional Coping Scale. To identify participants' abstention, researchers followed them for 2 years. To identify whether abstained or not and encourage them to abstain, researchers called them on the telephone once a week for 3 months. After 3 months, they were contacted every other week till 6 months passed since they left smoking cessation program. And they were contacted once a month for other 18months. Researchers also contacted their family to identify their abstention. Data Mining Decision Tree was performed with 37 variables (13 variables for the coping styles and 24 smoking-related variables) by Answer Tree 3.0v Results: Forty four (63.8%) out of sixty nine for 2 weeks, 34 (49.3%) for 6 months, 25 (36.2%) abstained for 1 year, and 22 (31.9%) abstained for 2 years. Participants of this study abstained average of 286.77 days from smoking. Included variables of a Decision Tree model for this study were positive interpretation, emotional expression, self-criticism, restraint and emotional social support seeking. Decision Tree model showed that those (n=9) who did not interpret positively (<=7.5) and criticized themselves (>6.5) abstained 23 days only, while those (n=9) who interpreted positively (>7.5), expressed their emotion freely (>6.5), and sought social support actively (>11.5) abstained 730 days, till last day of the investigation. Conclusion: The results of this study showed that certain coping styles such as positive interpretation, emotional expression, self-criticism, restraint and emotional social support seeking were important factors for long-term abstention from smoking. These findings reiterate the role of stress for abstention from smoking and suggest a model of coping styles for successful abstention from smoking. Despite of limitation of this study, it might help smokers who want to stop smoking and health practitioners who help them.

• 터널과지하공간
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• 제20권5호
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• pp.344-351
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• 2010

닫힌 균열을 따라 발생하는 전단거동을 Mode II 크랙의 시작과 진행으로 묘사할 수 있다. 파괴역학 이론에서는 순수 Mode II 재하에서 일반적으로 고유물성으로 인식되는 에너지 방출율(GII, Engergy Release Rate)이 한계점($G_{IIC}$)에 도달했을 때 전단거동이 시작된다고 예측한다. 지난 몇 년간 퍼듀대학의 암반공학그룹은 한계 에너지 방출률($G_{IIC}$)의 구속응력(normal stress)과 닫힌 균열의 거칠기에 대한 관계를 실험적으로 접근해왔다. 먼저 많은 실험들이 아크릴 재료를 대상으로 실행되었는데, 이는 광탄성(Photoelastic) 방법을 이용한 균열 끝(fracture tip)의 응력 집중 영역을 시각화하는 것을 가능케 해 주었다. 그 다음 실험 연구는 비교적 낮은 압축강도를 지닌 균질한 석고에 시행되었고, 최근에는 더 높은 압축강도를 지닌 재료를 대상으로 실험연구를 수행하였다. 그 예로 시멘트로 만든 시료 불록에 직접 전단 실험을 하였는데, 이전의 실험들과 마찬가지로 불연속면의 최대마찰각(Peak Friction Angle)이 잔류 마찰각(Residual Friction angle)과 비슷할 때만이 $G_{IIC}$가 재료의 고유물성으로 간주 될 수 있다는 점을 확인할 수 있었다. 그렇지 않은 경우에 한계 에너지 방출율($G_{IIC}$)은 구속응력과 함께 증가한다.

• Food Science and Biotechnology
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• 제17권1호
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• pp.90-94
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• 2008

Dynamic rheological properties of honey samples with 3 different moisture contents (17.2, 19.0, and 21.0%) were evaluated at various low temperatures (-15, -10, -5, and $0^{\circ}C$) using a controlled stress rheometer. The honey samples displayed a liquid-like behavior, with loss modulus (G") predominating over storage modulus (G') (G">>G'), showing the high dependence on frequency ($\omega$). The magnitudes of G' and G" decreased with an increase in temperature and water content while a predominant increase of G' was noticed at $-15^{\circ}C$. The time-temperature superposition (TTS) principle was applied to bring G" values for honeys at various temperatures together into a master curve. The G" over the temperature range of -15 to $0^{\circ}C$ obeyed the Arrhenius relationship with a high determination coefficient ($R^2=0.98-0.99$). Activation energy value (Ea=112.4 kJ/mol) of honey with a moisture content of 17.2% was higher than those (Ea=98.8-101.1 kJ/mol) of other honey samples with higher moisture contents.

• Steel and Composite Structures
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• 재36권6호
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• pp.643-656
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• 2020

This article presents a comprehensive static analysis of simply supported cross-ply carbon nanotubes reinforced composite (CNTRC) laminated nanobeams under various loading profiles. The nonlocal strain gradient constitutive relation is exploited to present the size-dependence of nano-scale. New higher shear deformation beam theory with hyperbolic function is proposed to satisfy the zero-shear effect at boundaries and parabolic variation through the thickness. Carbon nanotubes (CNTs), as the reinforced elements, are distributed through the beam thickness with different distribution functions, which are, uniform distribution (UD-CNTRC), V- distribution (FG-V CNTRC), O- distribution (FG-O CNTRC) and X- distribution (FG-X CNTRC). The equilibrium equations are derived, and Fourier series function are used to solve the obtained differential equation and get the response of nanobeam under uniform, linear or sinusoidal mechanical loadings. Numerical results are obtained to present influences of CNTs reinforcement patterns, composite laminate structure, nonlocal parameter, length scale parameter, geometric parameters on center deflection ad stresses of CNTRC laminated nanobeams. The proposed model is effective in analysis and design of composite structure ranging from macro-scale to nano-scale.

• Coupled systems mechanics
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• 제7권5호
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• pp.525-554
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• 2018

The paper deals with the study of the dynamics of the oscillating moving ring load acting in the interior of the hollow circular cylinder surrounded by an elastic medium. The axisymmetric loading case is considered and the study is made by employing the exact equations and relations of linear elastodynamics. The focus is on the influence of the oscillation of the moving load and the problem parameters such as the cylinder's thickness/radius ratio on the critical velocities. At the same time, the dependence between the interface stresses and load moving velocity under various frequencies of this load, as well as the frequency response of the mentioned stresses under various load velocity are investigated. In particular, it is established that oscillation of the moving load can cause the values of the critical velocity to decrease significantly and at the same time the oscillation of the moving load can lead to parametric resonance. It is also established that the critical velocity decreases with decreasing of the cylinder's thickness/radiusratio.

• 한국항공우주학회지
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• 제33권10호
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• pp.35-41
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• 2005

재료주축과 경사진 중앙균열을 내포하는 직방성 복합재료 내 균열문제를 해석하였다. 이 균열체에는 외부경계에서 2축방향으로 작용하는 하중을 받고 있다. 복합재료 내 초기균열의 진전각을 예측하기 위하여 수직응력비 이론을 적용하였으며, 균열진전각에 미치는 2축하중과 섬유재료주축의 영향을 분석하였다. 본 해석을 통하여 균열진전각은 수평하중에 많은 영향을 받고 있으며, 또한 균열경사각과 섬유배향각에도 큰 영향을 받음을 확인하였다.

• 대한조선학회지
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• 제21권1호
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• pp.35-42
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• 1984

In the present study, rotating bending fatigue tests have been carried out in three kinds of carbon steel specimens; an annealed low carbon steel, an annealed high carbon steel and quenched-tempered high carbon steel; with a small artificial surface defect that might exist in real structures. Fatigue crack lengths have been observed by a method of replication in order to investigate the growth characteristic of fatigue crack in the viewpoints of strength of materials and fracture mechanics. The main results obtained are as follows: 1) The effect of a small surface defect upon the reduction of fatigue limit is considerably large, and the rate of fatigue limit reduction grows in the following order; annealed low carbon steel(mild steel), annealed high carbon steel, quenched-tempered high carbon steel. 2) When the growth rate of surface crack length(2a) was investigated in the viewpoints of fracture mechanics based upon $ ${\Delta}K_{\varepsilon}$, the dependence of stress level and of surface defect size disappear, and there exists a linear relationships between d(2a)/dN and ${\Delta}K_{{\varepsilon}t},\;\Delta_{{\varepsilon}t}\sqrt{{\pi}a}$, on log. plot, i.e, $d(2a)/dN={C{\cdot}{\Delta}K_{\varepsilon}}^3_t$, where ${\Delta}_{{\varepsilon}t}\sqrt{{\pi}a}$ a is the cyclic total strain intensity factor range.

• 한국건축시공학회지
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• 제2권2호
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• pp.145-150
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• 2002

The hydration of cement paste occurs when the cement is miked with water. During the hydration, hydration heat causes the thermal stress depending on the site of concrete and the cement content. Especially in the high-strength concrete, we must give care to the concrete due to its large cement content. In this study conduction calorimeter and concrete insulation hydration heat meter were used to investigation the hydration heat characteristics of cement and concrete. To reduce hydration heat of high-strength concrete, several types of replacement of fly-ash and blast-furnace slag powder were used in this experiment. As a result of this study, it was found that hydration heat of high-strength concrete was reduced by replacement of fly-ash and blast-furnace slag powder. In case of high-strength concrete using blast-furnace slag powder, the max-heat arrival time was delayed but an effect of heat reduction was lower than a case of high-strength concrete using fly-ash, because it was considered that the heat-dependence property of blast-furnace slag powder was higher than that of fly-ash.

• 한국전산유체공학회지
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• 제21권2호
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• pp.62-69
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• 2016

It has been highly demanded to improve the accuracy of CFD(Computational Fluid Dynamics) methods for the assessment of the hydrodynamic performance of marine propellers in cavitating and non-cavitating flows. This paper presents a validation study on the numerical simulation of the tip vortex flow of a non-cavitating marine propeller SVA VP1304. The calculations are carried out by using the Reynolds averaged Navier-Stokes(RANS) approach, where the Reynolds Stress Model(RSM) is used for turbulence closure. The present paper contains a grid dependence test for the propeller open water simulations and a special emphasis is placed on conducting a local grid adaptation on the blade tip and in the tip vortex to reasonably reproduce the velocity and the pressure in the tip vortex flow field. The numerical results are compared with the experimental validation data, which are published in the second International Symposium on Marine Propulsors 2011(SMP'11). The present numerical results show a reasonable agreement with the experiments.