• Structural Engineering and Mechanics
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• 제36권3호
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• pp.363-380
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• 2010

Materials which exhibit different elastic moduli in tension and compression are known as bimodular materials. The bimodular materials model, which is founded on the criterion of positive-negative signs of principal stress, is important for the structural analysis and design. However, due to the inherent complexity of the constitutive relation, it is difficult to obtain an analytical solution of a bimodular bending components except in particular simple problems. Based on the existent simplified model, this paper solves analytically bending thin plates with different moduli in tension and compression. By using the continuity conditions of stress components in unknown neutral layer, we determine the location of the neutral layer, and derive the governing differential equation for deflection, the flexural rigidity, and the internal forces in the thin plate. We also use a circular thin plate with bimodulus to illustrate the application of this solution derived in this paper. The results show that the introduction of different moduli has influences on the flexural stiffness of the bending thin plate.

• Smart Structures and Systems
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• 제25권5호
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• pp.593-604
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• 2020

Temperature may have more significant influences on structural responses than operational loads or structural damage. Therefore, a comprehensive understanding of temperature distributions has great significance for proper design and maintenance of bridges. In this study, the temperature distribution of the steel box girder is systematically investigated based on the structural health monitoring system (SHMS) of the Sutong Cable-stayed Bridge. Specifically, the characteristics of the temperature and temperature difference between different measurement points are studied based on field temperature measurements. Accordingly, the probability density distributions of the temperature and temperature difference are calculated statistically, which are further described by the general formulas. The results indicate that: (1) the temperature and temperature difference exhibit distinct seasonal characteristics and strong periodicity, and the temperature and temperature difference among different measurement points are strongly correlated, respectively; (2) the probability density of the temperature difference distribution presents strong non-Gaussian characteristics; (3) the probability density function of temperature can be described by the weighted sum of four Normal distributions. Meanwhile, the temperature difference can be described by the weighted sum of Weibull distribution and Normal distribution.

• ETRI Journal
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• 제36권1호
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• pp.116-123
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• 2014

In this paper, a novel unequal broadband out-of-phase power divider (PD) is presented. Double-sided parallel-strip lines (DSPSLs) are employed to achieve an out-of-phase response. Also, an asymmetric dual-band matching structure with two external isolation resistors is utilized to obtain arbitrary unequal power division, in which the resistors are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of the DSPSLs, is used to short the isolation components. Additionally, this property can efficiently improve the broadband matching and isolation bandwidths. To investigate the proposed divider in detail, a set of design equations are derived based on the circuit theory and transmission line theory. The theoretical analysis shows that broadband responses can be obtained as proper frequency ratios are adopted. To verify the proposed concept, a sample divider with a power division of 2:1 is demonstrated. The measured results exhibit a broad bandwidth from 1.19 GHz to 2.19 GHz (59.2%) with a return loss better than 10 dB and port isolation of 18 dB.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.43-52
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• 2012

To compute a permeability coefficient along a rough fracture that takes into account the fracture geometry, this study performed detailed measurements of fracture roughness using a confocal laser scanning microscope, a quantitative analysis of roughness using a spectral analysis, and a homogenization analysis to calculate the permeability coefficient on the microand macro-scale. The homogenization analysis is a type of perturbation theory that characterizes the behavior of microscopically inhomogeneous material with a periodic boundary condition in the microstructure. Therefore, it is possible to analyze accurate permeability characteristics that are represented by the local effect of the facture geometry. The Cpermeability coefficients that are calculated using the homogenization analysis for each rough fracture model exhibit an irregular distribution and do not follow the relationship of the cubic law. This distribution suggests that the permeability characteristics strongly depend on the geometric conditions of the fractures, such as the roughness and the aperture variation. The homogenization analysis may allow us to produce more accurate results than are possible with the preexisting equations for calculating permeability.

• 보건의료산업학회지
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• 제8권4호
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• pp.1-12
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• 2014

This study is designed to develop a hospital communication program and to verify its effectiveness in graduate nurses self-esteem, communication conflicts, turnover intention and early resignation rate. The study method is a randomized control group with a pre-post test design. In order to help new graduate nurses adapt to the hospital, eight week hospital communication program is developed. The study participants are 104 nurses(47 experiment, 57 control) who have been working for less than six months. The data on self-esteem, communication conflict, and turnover intention was collected one week before the program and four weeks after the program. Then, the early resignation rate of the participating nurses was surveyed one year after the start of employment. The nurses who participated in the hospital communication program exhibit higher self-esteem, fewer communication conflicts, and lower early resignation rates than those who did not. However, effect in the turnover intention is not observed. Overall, the hospital communication program will help new graduate nurses adapt to hospitals.

• 한국도로학회논문집
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• 제16권6호
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• pp.19-25
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• 2014

PURPOSES : This study was performed to evaluate the possibility of Indirect Tensile Strength (ITS) as a testing method that can predict cracking on pavement. METHODS : Three asphalt binders and one kind of aggregate were used in this study, and all asphalt mixtures were produced using Gyratory Compactor followed asphalt mix design. The ITS test was performed for the mixture which are artificially short-term aged using the oven. The ITS properties were analyzed by air void, compaction temperature, asphalt content, and asphalt binder. RESULTS : The results of this study indicated that (1) the compaction temperature did not show relationship with the ITS test; (2) there was no specific trend between the asphalt content and the ITS test; (3) the ITS could reveal the property of kinds of asphalt binders; (4) the asphalt mixture that were produced at optimum temperature suggested by manufacturer did not exhibit optimum result for all asphalt binder. CONCLUSIONS : The possibility of ITS was confirmed from this study for replacement of the Marshall Stability method. However, it needs to perform in further studies of aggregate and compaction property to suggest a new ITS standard value.

• 한국전기전자재료학회논문지
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• 제26권5호
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• pp.360-366
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• 2013

For conventional electrical actuators, the materials are mainly made up of metals, which mean they are prone to corrosion and electrical sparking. Replacing these systems with polymer metal composite based materials can be solved both problems. Considering their excellent electromechanical property, low device fabrication cost, light weight, and good electrical conductivity, the actuator based on ionic polymer metal composite (IPMC) was fabricated using Nafion film, NaOH 0.1 molar solution, and Au electrode. IPMCs exhibit good electrostatic property which means they can in principle be used in making actuators based on electromechanical motions. The resistance measurements of Nafion film after soaking in NaOH and deionized water were demonstrated and compared each other. The result of sample soaked in NaOH showed better electrical conductivity than in deionized water. The fabricated IPMC actuator exhibits a large deformation of bending displacement of approximately 9 mm with applied low AC voltage 6.89 V at 2.84 Hz. The result of computer simulation was also very similar and shown as a bending displacement of 8.6085 mm.

• Asian-Australasian Journal of Animal Sciences
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• 제17권7호
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• pp.954-959
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• 2004

In a herd of 24 spring-born steers, plasma leptin and performance of selected purebred (n=5) and backcrossed Hereford (n=5) were compared in a year-round summer grazing and winter feedlot fattening. Bimonthly blood collection and body weight measurement were accomplished. The plasma samples were analyzed for leptin, insulin, total cholesterol, triglyceride, NEFA and glucose. The experimental design utilized one-way ANOVA with breed as the treatment. The purebred obtained higher plasma NEFA (p<0.001) compared to backcross, regardless of seasonal feeding systems (SFS). The backcross showed gradual increase and nonresponsiveness of plasma leptin to SFS. During summer grazing, attenuation of plasma leptin and sudden elevation when shifted to winter feedlot fattening were observed in purebred. Plasma leptin obtained linear relationship with body weight of purebred (r=0.53;p<0.001) and backcrossed Hereford (r=0.49; p<0.01). The purebred and backcrossed Hereford, when shifted to summer grazing, resulted to sustained and restricted daily gain, respectively. Therefore, cattle breeds of higher growth potential exhibit significant elevation of plasma leptin after 400 kg BW, when animal starts to deposit significant body fat.

• 산경연구논집
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• 제9권7호
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• pp.33-42
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• 2018

Purpose - This paper aims to verify whether the Fisher effect and the international Fisher effect are significant between China and South Korea in the long and short run, respectively. Research design, data, and methodology - The annual and monthly data, respectively, are employed to conduct an empirical estimation under the fully modified ordinary least squares(FMOLS). The nominal interest rate is treated as an independent variable. The inflation rate is treated as a dependent variable. Results - The results exhibit whenever in the long or short run, the Fisher effect exists in China and South Korea. However, the Fisher effect in South Korea is more significant than that of in China. Meanwhile, an empirical analysis is also preformed to investigate the long-run and the short-run international Fisher effect between China and South Korea. The deviation from the equilibrium relationship is that the commodity market and the Financial market have started to integrate in China. But China's integrated level proved to be relatively lower. Conclusions - To exploit that the Fisher effect and the international Fisher effect hold between China and South Korea can help both countries deal with the sufferings from integration of the commodity market and the financial market.

• 대한기계학회논문집
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• 제17권6호
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• pp.1423-1430
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• 1993

본 연구에서는 레이저를 사용한 부재의 충돌속도 계측 실험을 통하여 기존 연구자들의 연구 결과를 비교하고, 이 결과를 바탕으로 보다 간단하고 유용한 실험식 을 제안하고자 한다.