• Ocean Systems Engineering
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• v.1 no.1
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• pp.31-57
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• 2011

Impact pressure due to sloshing is of great concern for the ship owners, designers and builders of the LNG carriers regarding the safety of LNG containment system and hull structure. Sloshing of LNG in partially filled tank has been an active area of research with numerous experimental and numerical investigations over the past decade. In order to accurately predict the sloshing impact load, a new numerical method was developed for accurate resolution of violent sloshing flow inside a three-dimensional LNG tank including wave breaking, jet formation, gas entrapping and liquid-gas interaction. The sloshing flow inside a membrane-type LNG tank is simulated numerically using the Finite-Analytic Navier-Stokes (FANS) method. The governing equations for two-phase air and water flows are formulated in curvilinear coordinate system and discretized using the finite-analytic method on a non-staggered grid. Simulations were performed for LNG tank in transverse and longitudinal motions including horizontal, vertical, and rotational motions. The predicted impact pressures were compared with the corresponding experimental data. The validation results clearly illustrate the capability of the present two-phase FANS method for accurate prediction of impact pressure in sloshing LNG tank including violent free surface motion, three-dimensional instability and air trapping effects.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.66-72
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• 1992

A computational method of the Michell integral for water of finite depth is developed and the method makes use of the expansion of the hull form by the Legendre polynomial in both the longitudinal and the vertical directions. The wave resistance coefficient is given as a quadruple summation of the product of the shape factor and the hydrodynamic factor. The shape factor depends only upon the geometry of the hull form, and the hydrodynamic factor upon the depth-based Froude number and the ratios of the water depth and the draft to the ship length. Example calculations are done for the Wigley parabolic hull and the Series 60 $C_B$ 0.6, and the comparison of our results with the existing experimental data is shown.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.55-63
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• 1997

A numerical investigation has been made for flows in an axisymmetric circular cylinder with an impulsively rotating cone located at the bottom of the container. The axisymmetric container is completely filled with a viscous fluid. Major parameter for the present research is only the vertex angle of the cone, otherwise Reynolds number and aspect ratio of the vessel are fixed. Main interest concerns on the vortex breakdown of meridional circulation by impulsive rotation of the cone with respect to the longitudinal axis of the cylinder. Numerical method has been used to integrate momentum and continuity equations on a generalized body-fitted grid system. The pattern of vortex breakdown is quite different from that in a right circular cylinder with flat endwall disks. The flow visualization photograph of the preceeding work by Escudier is compared with the present numerical results and the two results are in good agreements. Also flow data are plotted to gain a deep understanding for the present phenomena of the vortex breakdown. The conclusions of this work are clearly explained by the classical theory of the vortex flows in a finite geometry.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.996-1001
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• 2008

To stop the train safely within the limited traveling distance and reduce its speed to the desired speed, it is necessary to guarantee the correct braking force. Presently, most trains have electric propulsion system and have adopted combined electrical and mechanical(friction) braking system. The friction coefficient between brake disc and pad is an important parameter in determining the mechanical braking force. In general, friction coefficient data of braking material have been taken through the dynamo-test in a laboratory. This study have suggested two methodologies that can measure friction coefficient of braking material on the train's actual operating condition. The first is the direct method; measure the brake force and the clamping force applied on the mechanical brake by using strain gauges installed at the brake disk, and then calculate it. The second method is the indirect method; obtain the friction coefficient by using the train load and the equivalent brake force which is deducted the longitudinal force, such as resistance to motion, gradient resistance and curved resistance, from the inertia force applied to the train.

• Journal of the Korea Society of Computer and Information
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• v.21 no.8
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• pp.117-126
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• 2016

The purpose of this study was to explain the influence of depression on the life satisfaction of the elderly with hypertension. Also, we were focusing whether there is a mediating effect of subjective health status between depression and life satisfaction of the elderly with hypertension. 2,198 persons with hypertension over 65 years of age were selected from the data of KLoSA(Korean Longitudinal Study of Ageing), administered by The Korea Employment Information Service in 2014. Life satisfaction was measured by 10-Likert. The depression measured by CES-D10. The mediating variable is subjective health status measured by 5-Likert. As the method of analysis, the multiple regressions were used with SPSS 19.0. The result of the study shows that depression has a negative influence on life satisfaction and a negative influence on subjective health status. It was also verified that the subjective health status variable has a mediating effect between depression and life satisfaction. These results present the importance of psychological approach for the health promotion experts intervening with the elderly with hypertension.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.3
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• pp.335-342
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• 2009

Motion characteristics of a planing craft are sensitively changed according to its weight and longitudinal center of gravity. In this paper, planing craft model tests were performed in calm water for various test conditions and Froude numbers. Sinkage and trim were measured to analyze the relations between the attitudes of a planing craft and the weight and center of gravity of it. Theoretical formula for the prediction of the attitudes of a prismatic planing hull was modified so that it can be applied to the prediction of the attitudes of a non-prismatic planing hull, and the calculation results by the modified formula were in good agreements with the experimental data.

• Korean Journal of Human Ecology
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• v.21 no.6
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• pp.1059-1082
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• 2012

The purpose of this study was to analyze the trends, research methodology and findings of various researches on family resilience published in Korea over the past 13 years. A total of 93 publications related to family resilience between 1999 and June of 2012 were analyzed; 72 journal articles and 21 doctoral dissertations which had not been published in academic journals. The results are as follows; (1) There has been steady increase in the number of related researches since 1999, with a significant increase since the mid-2000s as various nontraditional families emerged and the perception of family problems began to change. (2) With regards to the methodology, the majority of the studies were empirical, using quantitative methods in both data collection and analysis. Most measurement scales employed were based on inventories developed by foreign researchers. (3) The research subjects encompass a wide range of individuals and groups from both vulnerable families and families from the general population. Additionally, some researches focused on special interest areas including program development & evaluation and scale development. Although research on family resilience has increased in quantity, there needs to be more qualitative, longitudinal and theory grounded studies on different families and individual types to better understand family resilience in depth. In addition, specific measurement scales reflecting the unique Korean family culture should be developed. Other challenges and suggestions for future research on family resilience are discussed.

• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.729-744
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• 2012

The purpose of this study was to investigate the effects of youth voluntary on sense of citizenship, positive self-perception, and peer relations, which procedures was conducted by being comparison between middle school students and high school ones. This study also use the data given by 2st of the Seoul Education Longitudinal Study(SELS), which subjects were 7,593 youths(3,566 in middles school students and 4,027 in high school ones). The most significant variable for youth's peer relations was sense of citizenship both middle school and high school student, which indicates not only that it is encouraged by sense of citizenship but also that developing and leading the sense of citizenship for youth should be given by the school welfare policy. Positive self-perception in middle school youth influenced the second effect on their peer relations, but high school student's peer relation was impacted by the voluntary service into a secondary effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.243-250
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• 2005

In elevated irrigation aquaducts, one can observe a common damage pattern. That is, cracks, and crushing of concrete are usually repeated at a certain interval even if no faults are found in the design and construction of the structures. To investigate the causes of this damage, longitudinal deformations of several aquaducts have been measured. The analysis of the measured data suggests that the damages are mainly caused by cumulative repetition of extension and contraction due to temperature changes.

• Korean Journal of Child Studies
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• v.27 no.1
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• pp.153-166
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• 2006

Stability of the Korean Bayley Scale of Infant Development-II was tested in 305 infants by two measurements of varying intervals over a span of 5-36 months. Stability of K-BSID-II performance was r=.62(p<.01), r=.08(p<.18), r=.69(p<.01), r=.18(p<.01) for mental scale raw scores, mental scale index scores (MDI), psycho-motor scale raw scores and psycho-motor scale index scores(PDI), respectively. Stability was higher for the shorter test-retest interval group. Correlations between raw scores among infants with retest intervals of more than 2 years were stable on both mental and psycho-motor scales. MDI showed higher stability among high-risk infants than normal infants while PDI showed higher stability among normal infants. Testers and researchers should use both raw scores and index scores for better interpretations.