• Structural Engineering and Mechanics
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• 제28권3호
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• pp.295-316
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• 2008

In the present paper a mechanical model to predict the compressive response of high strength short concrete columns with square cross-section confined by transverse steel is presented. The model allows one to estimate the equivalent confinement pressures exercised by transverse steel during the loading process taking into account of the interaction of the stirrups with the inner core both in the plane of the stirrups and in the space between two successive stirrups. The lateral pressure distributions at hoop levels are obtained by using a simple model of elastic beam on elastic medium simulating the interaction between stirrups and concrete core, including yielding of steel stirrups and damage of concrete core by means of the variation in the elastic modulus and in the Poisson's coefficient. Complete stress-strain curves in compression of confined concrete core are obtained considering the variation of the axial forces in the leg of the stirrup during the loading process. The model was compared with some others presented in the literature and it was validated on the basis of the existing experimental data. Finally, it was shown that the model allows one to include the main parameters governing the confinement problems of high strength concrete members such as: - the strength of plain concrete and its brittleness; - the diameter, the pitch and the yielding stress of the stirrups; - the diameter and the yielding stress of longitudinal bars; - the side of the member, etc.

• Advances in concrete construction
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• 제10권2호
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• pp.151-159
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• 2020

An experimental study on the stress-strain relation of PVC-CFRP confined reinforced concrete columns subjected to eccentric compression was carried out. Two parameters, such as the CFRP strips spacing and eccentricity of axial load, were considered. The experimental results showed that all specimens failed by compressive yield of longitudinal steel bar and rupture of CFRP strips. The bearing capacity of specimen decreases as the eccentricity or the CFRP strips spacing increases. The stress-strain relation of specimens undergoes two stages: parabolic and linear stages. In the parabolic stage, the slope of stress-strain curve decreases gradually as the eccentricity of axial loading increases while the CFRP strips spacing has little effect on the slope of stress-strain curve. For the linear stage, the slope of stress-strain curve decreases as the eccentricity of axial load or the CFRP strips spacing increases. A model for predicting the stress-strain relation of columns under eccentric compression is proposed and it agrees well with various test data.

• 한국학교수학회논문집
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• 제18권1호
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• pp.149-167
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• 2015

본 연구의 목적은 수학의 학업성취도에 미치는 영향요인에 대하여 기존의 연구들을 분석하고, 특히 학교수준에서 실시하고 있는 수학과 수준별 이동수업이 실질적으로 학생들의 수학 학업성취도에 영향을 미치는지를 실증적으로 분석하고자 한다. 선택편의를 최소화하기 위해 한국교육종단연구2005의 6차년도 데이터를 바탕으로 경향점수매칭법(propensity score matching)을 사용하여 수학 교과 수준별 이동수업이 수학성취도의 지표인 수능 수리영역 표준점수에 미치는 영향을 살펴보았다. 그 결과 수준별 이동수업과 수학성취도 사이의 양의 관계가 있음을 확인하였으며, 수준별 이동수업의 효과적 운영을 위해 정책적인 노력이 요구된다.

• Perspectives in Nursing Science
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• 제9권1호
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• pp.9-15
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• 2012

Purpose: This study was conducted to determine the impacts of maternal depression on the temperament, health problems, and development of 4-month-old infants. Methods: For this longitudinal comparative study, data collected at one month postpartum and at the 4th month of follow-up were evaluated from sixty five pairs. The Edinburgh Postnatal Depression Scale (EPDS) was used to assess the symptoms of depression. Results: Eighteen point 5 percent and15.4% of mothers were diagnosed with postpartum depression at one month post-partum and at the 4th month of follow-up, respectively. The temperament of the infants between the two groups was not different. However, the infants of the depressed mothers had more health problems after 4 months. Depressed mothers had a lower score for the acceptance of Home Observation for Measurement of the Environment (HOME), and the development score of their infants was lower than that of the non-depressed mothers. Conclusion: Maternal depression affects the health and development of infants. Women should be screened for potential risk factors and for symptoms of depression during postpartum periods so that appropriate interventions including emotional support can be initiated in a timely manner.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.244-258
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• 2015

The horizontal stability of a Single-Point Moored (SPM) Floating Liquefied Natural Gas (FLNG) facility is investigated. Both numerical and experimental studies have been conducted for this SPM FLNG. The numerical simulations feature well the experimental data. The effects of the turret locations are studied based on the validated numerical model. Statistic results of the vessel's motions with different turret locations are conducted and compared. The results show that the longitudinal location of the turret has a significant influence on the horizontal stability, which has a strong relationship with the yaw and roll motions. The calculated top tensions on the hawsers also develop a regular change as changing the turret's location. The investigation will provide a brief of principles with more details for the design of the ongoing project.

• PNF and Movement
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• 제6권3호
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• pp.1-9
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• 2008

Purpose : The purpose of this study was to analyze the reaction of recovery for the fatigue by sports massage treatment after Taekwondo training and then to verify the effectiveness. Subject : The subjects of this study were all the 20 high school Taekwondo players divided into two groups (rest recovery group and sports massage group) selected by systematic random assignment sampling. Method : The variables were the level of hemoglobin, lactic acid and glucose, and measured at rest, immediately-after exercise and 30-minute recovery. The data from this study were analyzed by using one-way ANOVA, independent sample t-test. Results : The results are as follows ; 1. The measurement of the hemoglobin, there was not the significant differences between experiment group and control group. 2. The lactate showed lower in the experiment group than in the control group in 30-minute recovery (p<.001). 3. The glucose showed lower in the experiment group than in the control group in 30-minute recovery (p<.01). So I think the sports massage treatment is more effective in the relief of fatigue than static rest method during the recovery after sports. However the massage treatment influence on the activation of metabolism according to the intensity and the duration of sports, and vary the effect of treatment according to the method and execution time. Therefore the longitudinal investigation of the variation by the long time massage through the more detailed program must be requisite for us.

• 대한간호학회지
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• 제43권1호
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• pp.114-122
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• 2013

Purpose: The purpose of this study was to examine burnout and job satisfaction among nurses based on Job Demand-Resource Model. Methods: A survey using a structured questionnaire was conducted with 464 hospital nurses. Analysis of data was done with both SPSS Win 17.0 for descriptive statistics and AMOS 18.0 for the structural equation model. Results: The hypothetical model yielded the following Chi-square=34.13 (p=<.001), df=6, GFI=.98, AGFI=.92, CFI=.94, RMSR=.02, NFI=.93, IFI=.94 and showed good fit indices. Workload had a direct effect on emotional exhaustion (${\beta}$=0.39), whereas supervisor support had direct effects on emotional exhaustion (${\beta}$=-0.24), depersonalization (${\beta}$=-0.11), and low personal accomplishment (${\beta}$=-0.22). Emotional exhaustion (${\beta}$=-0.42), depersonalization (${\beta}$=-0.11) and low personal accomplishment (${\beta}$=-0.36) had significant direct effects on job satisfaction. Conclusion: The results suggest that nurses' workload should be decreased and supervisor's support should be increased in order to retain nurses. Further study with a longitudinal design is necessary.

• 아동학회지
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• 제36권4호
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• pp.163-176
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• 2015

The purpose of this study is to examine the longitudinal causal relationships between maternal parenting stress and parenting attitudes. Relevant data from mothers with infants aged from 2 to 4 years of age was gathered from the Panel Study of Korean Children were analyzed by means of Latent Growth Modeling. The findings are as follows, First, levels of parenting stress increased whereas the extent of positive parenting attitudes decreased as children grow older. Second, the initial value of parenting stress was observed to have a negative effect on the initial value of positive parenting attitudes. Third, those mothers who generally have faster speeds of increasing parenting stress tend to have faster speeds of decreases in positive parenting attitudes. What this study clearly revealed is that the positive parenting attitudes of mothers with infants tend to improve when the mothers try to efficiently deal with their parenting stress by either acquiring appropriate parenting knowledge or receiving support from their families and communities.

• 천문학회지
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• 제32권1호
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• pp.65-73
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• 1999

In this study we present a new improved nonlinear calibration method for vector magnetograms made by the Solar Flare Telescope of BOAO. To identify Fe I 6302.5 line, we have scanned monochromatic images of the line integrated over filter passband, changing the location of the central transmission wavelength of a Lyot filter. Then we obtained a filter-convolved line profile, which is in good agreement with spectral atlas data provided by the Sacramento Peak Solar Observatory. The line profile has been used to derive calibration coefficients of longitudinal and transverse fields, employing the conventional line slope method under the weak field approximation. Our improved nonlinear calibration method has also been used to calculate theoretical Stokes polarization signals with various angles of inclination of magnetic fields. For its numerical test, we have compared input magnetic fields with the calibrated ones, which have been derived from the new improved non-linear method and the conventional method respectively. The numerical test shows that the calibrated fields obtained from the improved method are consistent with the input fields, but not with those from the conventional method. Finally, we applied our new improved method to a dipole model which characterizes a typical field configuration of a single, round sunspot. It is noted that the conventional method remarkably underestimates the transverse field component near the inner penumbra.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.896-904
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• 2017

희박 예혼합 연소기는 NOx 배출 규제를 만족시키지만, 연소불안정 현상을 야기하는 단점을 갖고 있다. 이때 연소불안정 현상은 연소기 내부에서 열발생 섭동과 음향 압력 섭동 사이의 피드백 관계로부터 도출된다. 특히 항공용 엔진에 대한 배출 가스 규제가 강화되면서, 환형 연소기에서의 연소불안정 연구에 대한 관심이 크게 증가하고 있다. 본 연구에서는 환형연소기에서의 길이방향 및 환형 방향의 모드까지 계산할 수 있는 열음향 네트워크 모델을 개발 및 사용하였고, 이때 연소 모델은 화염전달함수를 적용하였다. 이와 같은 네트워크 모델을 사용하여 벤치마킹한 환형연소기의 실험데이터와 비교 분석하여 연소불안정 해석을 진행하였다.