• Journal of Korean Society of Water and Wastewater
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• v.12 no.2
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• pp.76-82
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• 1998

It is necessary to calculate the accurate velocity from the hydraulic model for the reliable prediction of water quality changes in water supply system. To verify the hydraulic analysis of the water supply system, fluoride was used as a tracer to calculate the travel time from the injection point to the sampling points. Results from this field experiment indicate that fluoride can be a good conservative tracer while it showed a little longitudinal dispersion along the pipe lines. And the velocity from the model was verified by these travel times and calibrated by changing the ratio of the unaccountable water. When the ratio of the unaccountable water. When the ratio of the unaccountable water was 20%, the error between the estimation of hydraulic model and the real travel time was minimum.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.88-95
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• 2003

A firm's business composition and the sales volume of each business segment are subject to change depending, to a considerable extent, on the firm's business strategy. These changes were weighted and represented as a single index, referred to by scholars in strategic management and industrial organization research fields as 'firm entropy' then its impact on firms' profitability was assessed over twelve years. The performance differences between contractor and non-contractor firms, as well as focused and diversified firms, were compared through a Longitudinal Data Analysis Technique within a Hierarchical Linear Modeling framework. Hypothesis was formulated based on firm diversification theories and previous research findings. The hypothesis was tested according to the modeling outcomes, and implications are presented. The research findings indicate that the level of firms' long-term profitability supports the argument that the construction industry is highly competitive and mature.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.5
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• pp.628-636
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• 1994

One vertical (medianus) and six horizontal (chest, bust, below bust, waist, abdomen and hip) sections of nine healthy pregnant women were examined every month by siliding gauge method during the period from 3rd to loth monthes of pregnancy. In the body changes along the passing months of pregnancy, which were observed by a follow·up measurement, there was little change on the posterior line when viewed using a vertical cross section. On the contrary, there was a great deal of increase on the anterior median line. Particularly, the degree of protrusion was great in the waist and ubilicus area due to pregnancy. At early pregnancy the distance from front to back is much shorter than side to side, however, as pregnancy progressed the front to back distance, on a horizontal cross section, is almost equal to the side to side distance.

• The Journal of the Korean dental association
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• v.19 no.2 s.141
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• pp.167-174
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• 1981

The purpose of this study was observing the annual growth increment in cephalogram. The cephalograms of 29 boys & 23 girls were analized by method of Downs & Steiner, range from 7 to 8 years in Korean children. the results were as follows; 1. The craniofacial complex of Korean children grew downward and fordward. 2. The pronounced linear and angular growth changes were in the upper central incisors and lower central incisors. 3. The SN Plane to Mandibular plane angle was reduced. 4. The SNA and SNB was almost constant in male.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.37-42
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• 2010

This paper deals with the sealing mechanism of the gasket component and the effects of design parameters for the exhaust manifold. The finite element model includes hot-end exhaust system and a simplified gasket model supplied by ABAQUS software. The mechanical behaviors of bead and body of a gasket are measured after several times of cyclic loads by gasket supplier. From the finite element analysis due to the cyclic thermal loads, the flange of exhaust manifold shows thermal expansion and contraction in longitudinal direction as well as convex and concave deformations with respect to the engine cylinder head. And, the contact pressures of the gasket beads suddenly changes by normal deformation of inlet flanges. Therefore, the magnitudes of contact pressures could be used to determine the sealing characteristics of the exhaust gas in the exhaust system. The distributions of contact pressures in gasket bead lines shows a good agreement with the engine test results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.4
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• pp.363-369
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• 2009

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.403-408
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• 2010

The acoustic properties of anti-inflammatory egonol were investigated by using micro-Brillouin scattering spectroscopy, by use of a 6-pass tandem Fabry-Perot interferometer and an optical microscope specially modified for spectroscopic purposes. The measured Brillouin spectrum was composed of a central peak centered at zero and a Brillouin doublet arising from the longitudinal acoustic waves, i.e. propagating density fluctuations. For the first time, the glass transition of egonol was identified to be about $5^{\circ}C$ at which the Brillouin peak position and the half width showed abrupt changes. The substantial damping of acoustic phonons of egonol near the glass transition temperature indicated that the contribution of internal relaxation processes such as small-amplitude librations of side chains to the damping of acoustic phonons may be substantial depending on the internal structure of molecules.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.130-135
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• 1997

A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by longitudinal distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product changes with the aspect ratio of product and increases with the decreases in die length and in eccentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

• Journal of Families and Better Life
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• v.25 no.1 s.85
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• pp.59-75
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• 2007

This review synthesizes research during the past 15 years on the family relations of older persons. After discussing two background issues-sociodemographic changes of later life families and the status of the elderly-the following topics are addressed; relationships between aged parents and adult children, couple relationships, grandparents' relationship with their grandchildren and sibling relationships. Family relationships are vital support systems providing emotional and instrumental support in the lives of older persons. Mutual assistance and affection among family members were found to be common characteristics. Although research on family gerontology has increased in quantify, there are feater needs to develop qualitative, longitudinal and theory grounded studies to capture the rich complexity of family life. Other challenges and suggestions for future research on older persons' family relationship are presented.

• Asia pacific journal of information systems
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• v.14 no.4
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• pp.123-145
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• 2004

This paper empirically and longitudinally examines relationships among corporate strategy, competitive advantage of information technology (CAIT), and organizational performance. This research replicates the research done in 1997 and compares the results to observe any noticeable changes. Research results confirm that information technology provides several traits of strategic advantages such as efficiency, threat, functionality, preemptiveness, and synergy and significantly contributes to corporate performance both in 1997 and 2004. The findings reinforce the accepted belief that alignment between corporate strategy and CAIT is critical for firms to attain sustainable competitive advantage, subsequently enhances corporate performance and competitive position against rivals, potential entrants, substitutes, suppliers, and buyers. Research results of 2004 show stronger relationships among corporate strategy, competitive advantage of information technology, and organizational performance than research results of 1997.