• Bulletin of the Korean Chemical Society
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• 제10권4호
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• pp.372-374
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• 1989

The new viscosity theory is applied to the abnormal behavior of the viscosity near the critical point. This theory suggests that the viscosity is equal to the product of the absolute pressure(kinetic pressure + internal pressure) and the collision time. We can find this abnormal behavior to be due to the large collision time near the critical point. The agreements between theoriticals and experimentals of the critical enhancement are satisfactory.

• Advances in materials Research
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• 제12권1호
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• pp.15-29
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• 2023

In this paper, fracture analysis of a continuously inhomogeneous arch structure with two longitudinal cracks is developed in terms of the time-dependent strain energy release rate. The arch under consideration exhibits non-linear creep behavior. The cross-section of the arch is a rectangle. The material is continuously inhomogeneous along the thickness of the cross-section. The arch is loaded by two bending moments applied at its end sections. The mechanical behavior of the material is described by using a non-linear stress-strain-time relationship. The two longitudinal cracks are located symmetrically with respect to the mid-span of the arch. Due to the symmetry, only half of the arch is considered. Time-dependent solutions to strain energy release rate are obtained by analyzing the balance of the energy. For verification, time-dependent solutions to the strain energy release rate are derived also by considering the time-dependent complementary strain energy. The evolution of the strain energy release rate with the time is analyzed. The effects of material inhomogeneity, locations of the two cracks along the thickness of the arch and the magnitude of the external loading on the time-dependent strain energy release rate are evaluated.

• 한국학교ㆍ지역보건교육학회지
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• 제14권2호
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• pp.1-14
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• 2013

Objectives: The purpose of this study was to identify the relationship of internet use time and health risk behaviors among adolescents and provide data to set up a strategy for preventing internet addiction. Methods: The data of the 2011 Youth Health Risk Behavior web-based Survey Collected by Korean Center for Disease Control was analyzed using t-test, ANOVA, Chi-square test for this study. Results: There were significant differences between boys and girls in internet use time. Boy's internet use time was different according to city size(F=13.20, p<.001), grade(F=35.85, p<.001), school record(F=298.95, p<.001), economic state(F=326.75, p<.001), living with parents(t=11.60, p<.001), father's education level(F=147.92, p<.001), and mother's education level(F=110.93, p<.001). Girls' internet use time was also different according to school grade(t=-8.68, p<.001), grade(F=61.03, p<.001), school record(F=233.32, p<.001), economic state(F=185.78, p<.001), living with parents(t=10.81, p<.001), father's education level(F=86.54, p<.001), and mother's education level(F=92.64, p<.001). Regarding the health risk behaviors, present smoking, present alcohol drink, drug use skipping breakfast, eating fast food, drinking soda, sexual behavior, suicidal attempt, engagement time in physical education classes, severe exercise, and sleeping satisfaction made differences in the internet use time. Conclusions: The results suggest that health risk behaviors are influenced by internet use time of adolescents. Thus, these results may be contribute to development of programs to prevent internet addiction.

• 콘크리트학회논문집
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• 제18권4호
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• pp.479-487
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• 2006

본 연구는 고성능 콘크리트를 사용한 프리텐션 콘크리트 부재에 대한 시간의존거동해석에 관한 연구이다. 일반 콘크리트의 크리프, 건조수축 및 강재의 릴렉세이션 현상에 대한 기존의 AASHTO 방법을 수정하여, 고성능 콘크리트 부재에 대한 단계-함수법 및 시간-단계법에 의한 시간의존 해석기법을 소개하였다. 제시된 모델은 고성능 콘크리트 프리텐션 부재의 프리스트레스 손실 및 처짐에 대한 초기 및 시간의존거동 예측 값을 제공해 준다. 제안된 모델을 이용하여, 고성능 콘크리트를 사용한 프리텐션 부재의 시간의존거동에 관한 실험 결과와 비교하였다. 기존의 AASHTO 규정에 의한 시간의존 거동 예측치에 비해, 소개된 모델에 의한 고성능 콘크리트 부재의 초기 및 시간의존거동 예측결과가 실제 거동에 보다 정확한 결과를 제공해 주었다.

• 한국체육학회지인문사회과학편
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• 제58권1호
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• pp.217-228
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• 2019

이 연구는 여가시간 신체활동 의도와 운동행동 간의 관계에서의 틈(gap)을 극복하고 이 관계를 잇는 매개 변인들의 역할을 검증하고, 기존의 계획행동이론의 확장을 도모하는데 목적을 두었다. 이에 여가시간 신체활동에 대한 의도와 운동행동 간의 관계에서 실천계획-1)극복계획과 2)실행계획-의 매개효과를 검증하였다. 연구의 목적을 달성하기 위하여 편의표집법을 활용하여 강원도 내 위치한 세 곳의 대학에서 교양체육에 참여하고 있는 대학생 253명(남학생=118; 여학생=105)을 대상으로 설문조사를 하였다. 수집된 자료는 SPSS와 Amos프로그램을 활용하여 분석되었으며, 기술통계, 신뢰도, 상관분석, 그리고 구조 관계를 검증하기 위해 구조방정식 모형을 적용하여 의도, 극복계획 및 실행계획, 그리고 여가시간 신체활동 및 운동 간의 관계를 검증하였다. 특히, 의도와 행동 간의 관계에서 극복계획과 실행계획의 매개효과를 검증하기 매개 분석을 실시하였다. 그 결과, 신체활동 의도는 실행계획과 운동행동에 직접적으로 영향을 미쳤으며, 실행계획은 의도에 비해 실제 운동행동을 더욱더 잘 예측하는 것으로 나타났다. 따라서 매개변인인 극복계획과 실행계획은 신체활동에 대한 참여 의도가 실제 운동행동에 미치는 영향에서 부분적으로 모두 매개역할을 하는 것으로 나타났다. 이 연구를 통해 나타난 결과를 종합해 보면, 극복계획과 실행계획의 개념화와 모형검증은 의도-행동의 틈을 극복하고 실제 현장에서 실용적으로 활용될 수 있다는 사실을 알 수 있었다.

• 한국보건간호학회지
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• 제19권2호
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• pp.305-315
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• 2005

Purpose: The purpose of this study was to investigate the relationships among depression, sleep patterns and health promoting behavior in female college students. Methods: The subjects of this study consisted of 350 college students. The data was collected through self-administered questionnaires from November to December of 2004. The data was analyzed via the SPSS computer program by using descriptive statistics, t-tests, ANOVA and Pearson's correlation coefficients. Results: There are significant differences and impacts on depression according to the amount of coffee consumed, the time spent on computer and the amount of smoke inhaled. Sleep patterns differ depending on one's college major, the time spent on computer, and the amount of smoke inhaled. Health promotion behavior was shown to be significantly different according to the living style, college major and how much TV was watched The mean scores for depression, sleep patterns, health promoting behavior were 1.45 (on a 3 points scale), 2.71 (on a 4 points scale), and 3.03 (on a 5 point scale), respectively. There was a significant positive correlation between sleep patterns and health promoting behavior, and there was negative correlation between depression and health promoting behavior, and between depression and sleep patterns in college students. Conclusion: The findings of this study give useful information to create further studies on intervention programs related to health promoting behavior for college female students.

• 제어로봇시스템학회논문지
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• 제9권10호
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• pp.789-797
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• 2003

An implementation scheme and some improvements are proposed to adopt public-licensed operating system, Linux and de-facto world-wide network standard, TCP/IP into the field of behavior-based autonomous mobile robots. To demonstrate the needs of scheme and the improvement, an analysis is performed on a server/client communication problem with real time Linux previously proposed, and another analysis is also performed on interactions among TCP/IP communications and the performance of Linux system using them. Implementation of behavior-based control architecture on real time Linux is proposed firstly. Revised task-scheduling schemes are proposed that can enhance the performance of server/client communication among local tasks on a Linux platform. A new method of TCP/IP packet flow handling is proposed that prioritizes TCP/IP software interrupts with aperiodic server mechanism as well. To evaluate the implementation scheme and the proposed improvements, performance enhancements are shown through some simulations.

• 웰빙융합연구
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• 제2권2호
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• pp.13-19
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• 2019

This study is about pressure-accepting behavior of consumers attached to brands. Previous studies of the situation focused on time pressure and scarcity pressure, focusing on scarcity. The results of the study are as follows. First, consumers attached to brands were found to be relatively blunt in time pressures. This indicates that brands of consumers are attached to do not buy on impulse because of time pressure. Second, consumers attached to brands were found to be relatively under social pressure. This indicates that consumers who are attached to the brand do not buy with social pressures such as quasi-family groups. Third, consumers attached to brands were found to be relatively sensitive to scarcity pressures. Thus, a quantity-limited marketing strategy is generally more effective for consumers with high marketing effectiveness but high brand attachment. Fourth, unlike the one presented, consumers attached to the brand were found to be relatively insensitive to place pressure.

• Journal of Biosystems Engineering
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• 제14권1호
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• pp.8-15
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• 1989

Agricultural materials do not react in a purely elastic manner, and their responses when subjected to stress and strain are appeared from a combination of elastic and viscous behavior. Various researchers have studied the mechanical and rheological properties of the many agricultural materials, but those properties are available mostly foreign varieties of agricultural products. Rheological properties of rice seedlings become important to formulate the principles governing their mechanical behavior. The objectives of this study were to experimentally determine the stress relaxation properties of rice seedlings such as three Japonica-type and one Indica ${\times}$ Japonica hybrid in the transplanting age. The results of this study are summarized as follows; 1. The stress relaxation behavior could be described by the generalized Maxwell model. 2. The phenomenon of stress relaxation happened abruptly just after loading and this phenomenon weakened with the loading time lapsed. 3. With increase of the initial stress, the stress relaxation intensity and residual stress increased, while the relaxation time was constant with increased, while the relaxation time was constant with increase of the level of initial stress. 4. With increase of loading rate, the stress relaxation intensity increased, while the relaxation time and residual stress decreased.

• Fibers and Polymers
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• 제2권2호
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• pp.81-85
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• 2001

The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.