• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.63-75
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• 2017

In offshore environment, an accurate estimation of a wave-structure interaction has been an important issue for safe and cost effective design of fixed and floating offshore structures exposed to a harsh environment. In this study, a wave-structure interaction around a circular column was investigated with regular waves. To simulate 3D two-phase flow, open source computational fluid dynamics libraries, called OpenFOAM, were used. Wave generation and absorption in the wave tank were activated by the relaxation method, which implemented in a source term. To validate the numerical methods, generated Stokes 2nd-order wave profiles were compared with the analytic solution with deep water condition. From the validation test, grid longitudinal and vertical sizes for wave length and amplitude were selected. The simulated wave run-up and wave loads on the circular column were studied and compared with existing experimental data.

• Journal of Families and Better Life
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• v.34 no.4
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• pp.1-19
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• 2016

The present study aimed at investigating the relations between the amount of child care experienced in the first three years of life and socioemotional development of children at age 4 indicated by problem behaviors and peer competence. Using the longitudinal data of the Panel Study of Korean Children(PSKC), the information of 1,699 children were analyzed. The results indicated that any child care experience, hours in child care, full-time child care and early entry to child care were significantly related to children's externalizing behavior problem and play disruption at age 4. Some significant relations were detected between child care experience and better peer competence as well. Interestingly, the patterns of relations were different for boys and girls. Being in child care, a greater amount of child care and early entry to child care tended to be related to externalizing problem behaviors of boys and whereas they were more related to peer competence of girls indicated by play interaction, play disruption and play disconnection. Child care hours at age 3 were relative stronger predictors of children's development compared to those at age 1 or at age 2. The findings imply that the amount of child care during the first 3 years of life does not have strong harmful effects on preschoolers' socioemotional development and that there are differences in the effects of child care on boys and girls.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.411-417
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• 2015

Several optical monitoring strategies by a ground-based telescope to protect a Geostationary Earth Orbit (GEO) satellite from collisions with close approaching objects were investigated. Geostationary Transfer Orbit (GTO) objects, Inclined GeoSynchronous Orbit (IGSO) objects, and drifted GEO objects forced by natural perturbations are hazardous to operational GEO satellites regarding issues related to close approaches. The status of these objects was analyzed on the basis of their orbital characteristics in Two-Line Element (TLE) data from the Joint Space Operation Center (JSpOC). We confirmed the conjunction probability with all catalogued objects for the domestic operational GEO satellite, Communication, Ocean and Meteorological Satellite (COMS) using the Conjunction Analysis Tools by Analytical Graphics, Inc (AGI). The longitudinal drift rates of GeoSynchronous Orbit (GSO) objects were calculated, with an analytic method and they were confirmed using the Systems Tool Kit by AGI. The required monitoring area was determined from the expected drift duration and inclination of the simulated target. The optical monitoring strategy for the target area was analyzed through the orbit determination accuracy. For this purpose, the close approach of Russian satellite Raduga 1-7 to Korean COMS in 2011 was selected.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.4
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• pp.573-583
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• 2015

Objectives: This study was carried out to evaluate the effect of noise exposure and aging on changes in hearing threshold level and the relationship between age and noise. Materials: The author selected 274 male shipyard and assembly line workers as the noise exposed group and 582 males not exposed to noise as the general population group. Data were collected from five years of consecutive annual audiometric tests performed from 2008 to 2012. Results: In the general population and noise exposed groups, there was a reverse phenomenon that hearing threshold level for 2009 was lower than that of 2008, which seemed to be due to the learning effect, but from 2010 hearing threshold level increased. In the noise exposed group, the mean hearing threshold level in the left ear was significantly higher than that for right ear. In the general population group, the older was the age, the higher was the hearing threshold level, especially at 4000 Hz. In the general population and noise exposed groups, frequency, age group and noise exposure independently affected hearing threshold level, and there was no relationship between age and noise exposure. Over all frequencies, the change of hearing threshold level was larger in the noise exposed group than in the general population group. In the noise exposed group below thirty years old, the change at 4000 Hz was remarkable. Conclusions: Age and noise exposure seem to affect hearing threshold level independently and contribute to an additive effect on hearing threshold level.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.281-287
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• 2005

Nonlinear behaviors such as steep-fronted wave motions and a finite amplitude limit cycle often accompanying combustion instabilities have been numerically investigated using a characteristic-based approximate Riemann solver and the well-known ${\eta}-{\tau}$ model. A resonant pipe initially subjected to a harmonic pressure disturbance described the natural steepening process that leads to a shocked N-wave. For a linearly unstable regime, pressure oscillations reach a limit cycle which is independent of the characteristics of the initial disturbances and depends only on combustion parameters and operating conditions. For the 1.5 MW gas generator under development in KARI, the numerical results show good agreement with experimental data from hot-firing tests.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.373-382
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• 2003

The successful use of osseointegrated implants to replace missing teeth has been demonstrated for both the completely and the partially edentulous patients. Many studies have confirmed an excellent long-term prognosis. The successful outcome of any implant procedure is surely dependent on the interrelationship of the various components that includes the following: biocompatibility of the implant material, macroscopic and microscopic nature of the implant surface, the status of the implant bed in both a health(noninfected) and a morphologic(bone quality) context, the surgical technique, the undisturbed healing phase, the subsequent prosthetic design, and long-term loading phase. Periodontally compromised patients have poor status of the implant bed and periodontal pathogen. No longitudinal data are available whether these factors affect the prognosis of implants. In this study, 102 machined $Br{{\aa}}nemark$ implants are inserted to analyze the success rate of 1-4 years and marginal bone loss in 49 chronic periodontitis patients. The following conclusions could be drawn from this study. 1. The cumulative success rate of implants at the 4-year of loading was 95.10%. 2. 5 failed implants have been removed. One implant have been removed due to infection, two implants were removed due to failure of osseointegration. and other two implants were removed due to mechanical failure caused by over-loading. 3. Mean marginal bone loss from the time of loading was 0.94mm at first year, 1.12mm at second year, 1.25mm at third year. These results suggest that implant therapy is good treatment modality in chronic periodontitis patients, and periodontal treatment including oral hygiene program is completed prior to insertion of implants.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.461-472
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• 2010

This paper investigates the behavior of precast concrete (PC) shear walls with a new vertical connections for a fast remodeling construction. The C-type vertical connections for the PC wall systems are proposed for transfer of bending moment between top and bottom walls in the vertical direction while a shear key in the center of wall is prepared to transfer shear forces by bearing action. The proposed vertical connections allows easy fabrication thanks to slots at the edges of wall in opposite directions. The plane PC wall systems subject to lateral load are compared with ordinary wall systems by investigating the effects of connection on the stiffness, strength, ductility, and failure modes of whole systems. The load-displacement relationship and influence of premature failure of connections are examined. The experimental test showed that the longitudinal reinforcing steel bars placed at the edges of walls yielded first and the ultimate deformation were terminated due to premature failure of connections. The diagonal reinforcements for efficient shear transfer in the walls were not effective. The strength and deformation obtained through the section analysis were generally in agreement with the experimental data, and indicated that. Gap opening contributed to the deformation behavior more than any other factors.

• The Research Journal of the Costume Culture
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• v.1 no.2
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• pp.131-144
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• 1993

Even though it has been to research on the variance of clothing pressure and on its effect of human body, it has not been available to evaluate the clothing pressure as an objective standard ta for the determination of an extra quantity of bodice' basic pattern. In this paper the basic pattern(the close adherence original shape) is determined by a drawing of plane figure after detaching an unweaving clothing from the inside of the gypsum, and the extra quantity is figured by a extension quantity when is formatted with 0.5, 1.0, 1.5 cm extra quantity longitudinal-cross section figures. With our experimental method, review the variance of clothing pressure according to difference of the extra quantity which was figured with subjects wearing experimental clothing including the extra quantity. The difference of the extra quantity was able to calculate with data form the subjects when anatomical position and five movements, then compare with subjects wearing non-extra quantity experimental clothing. The results of experiment as the follows : 1. There is only few body portions with the significant variance according to the increasing of he extra quantity at he body portion and the sleeve portion. 2. The clothing pressure of the sleeve portion was higher than the clothing pressure of the body portion. The difference of clothing pressure according to the variance of the extra quantity at the sleeve portion is more significant than the body portion. 3. Consider several important pressure points which wil be the No. 1 at the front of body portion. No. 17, 18 at the back of body portion and No. 21 at the sleeve portion. 4. It is important to have plane figure of gypsum when format an basis pattern.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.7-20
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• 1989

A serial cephalometric study was undertaken to define the growth of the soft tissue facial profile in Korean children. The sample was composed of 25 males and 15 females for whom yearly cephalometric records were taken from the ages of 6 to 13 years. From the tracings, points on skeletal and soft tissue profiles were located and recorded on magnetic tape utilizing a Calcomp Talos RP660 X-Y digitizer. Linear and angular measurements of soft tissues were made directly from tape in a Cyber 174-16 computer after cephalometric enlargement had been corrected. A statistical evaluation was made of the data and the average profile diagrams in male and female were described by a Calcomp 960 pen plotter. On the basis of the findings of this study, the following trends were established. 1. The most prominent growth in soft tissue facial profile thickness was the nose and the least was the forehead. 2. The general growth direction of the soft facial tissue to the cranium described the downward and forward. 3. The degree of soft tissue facial convexity was decidely more than that exhibited earlier in life even though the soft tissue chin had protruded to the cranium. 4. The measurements indicated a general tendency for males to have larger nose and more convex and long soft tissue facial profile than did females. 5. Males showed significantly more growth than females in base of the upper lip and height of the upper anterior facial profile. 6. There was a difference between males and females in the rates of soft tissue facial profile growth. 7. Korean children showed less convex in the soft tissue profile convexity than did American children.

• Research in Community and Public Health Nursing
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• v.22 no.3
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• pp.302-314
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• 2011

Purpose: This study aimed to validate instruments to classify the frailty of Korean elderly people in community. Methods: For this study, 632 elders were selected from community-based elderly houses and home visiting registries, and data on frailty were collected using three instruments during November, 2008. The Korean Frail Scale (KFS) was composed of 10 domains with the maximum score of 20. The Edmonton Frail Scale (EFS) had 10 domains with the maximum score of 17. The 25_Japan Frail Scale (25_JFS) was composed of 6 domains with the maximum score of 25. Internal consistency was measured with Cronbach's ${\alpha}$. Sensitivity, specificity and area under the curve (AUC) of ROC were measured to see validity with long.term care insurance grade as a gold standard. Results: The Cronbach's ${\alpha}$ was .72 for KFS, .55 for EFS, and .80 for 25_JFS. Sensitivity, specificity, and AUC were 70.0%, 83.2%, and .83, respectively, at cutting point 10.5 for the KFS, 50.0%, 80.9%, and .66, respectively, at 8.5 for EFS, and 80.0%, 85.9%, and .86, respectively, at 12.5 for 25_JFS. Conclusion: KFS and three JFS showed favorable internal consistency and predictive validity. Further longitudinal studies are recommended to confirm predictive validity.