• Journal of the Korean Society of Child Welfare
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• no.32
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• pp.7-32
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• 2010

The purpose of this research is to identify the longitudinal reciprocal relationship between family social capital and self-esteem of adolescents. Five waves of panel data from the Korea Youth Panel Survey were employed for this research. Korean Adolescents Policy Research Institute collected the first wave data in 2004 from elementary school children in 4th grade. Autoregressive cross-lagged modeling was performed to analysis the longitudinal reciprocal relationship between family social capital and self-esteem. The major findings were as follows. First, stability coefficient of family social capital and self-esteem showed that both variables were significantly stable over time. Secondly family social capital(t) had statistically significant effect on self-esteem(t+1), whereas self-esteem did not predict family social capital at a statistically significant level. These findings suggest that family social capital and self-esteem is stable overtime, and that obtaining family social capital and establishing positive self-esteem is important during this period in childhood. In addition, the results show that family social capital affects self-esteem, which highlights the importance of family social capital accumulation on the development of adolescent self-esteem.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.18-27
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• 2005

Airfoils with improved longitudinal static stability were designed for a WIG craft through aerodynamic design optimization. The response surface method is coupled with NURBS-based shape functions and Navier-Stokes flow analysis. The procedure runs in the network-distributed design framework of commercial-code based automated design capability to enhance computational efficiency and robustness.Lift maximization design maintaining similar static margin to a DHMTU airfoil successfully produced a new airfoil shape characterized by pronounced front-loading and the well-known reflexed aft-camber line. Another airfoil design of lower variation in pitching moment during take-off showed weakened front-loaded characteristics and hence decreased lift slightly. Investigations using the present design methodology on an existing optimization result based on potential flow analysis and NACA-type geometry generation demonstrated significance of carrying various geometry generations and more realistic flow analysis with optimization.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.92-97
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• 2008

Salt wedge into the river from the sea or fresh water flume (fresh wedge) in the ocean from the sea has density current characteristics. However, when temperature and salinity simultaneously determine the density of wedges, one of salinity and temperature can distributed in the reversed profiles against gravity, even though the density profile is stable. In this case, the double diffusive process is critical in determining mixing rate. The present work studies relative contribution of shear driven mechanical mixing component and double diffusive layering process, when warm salty denser water is introduced into the cold fresh lighter water column. Laboratory experiment releases warm salty denser water into cold fresh lighter water controlling discharge amount to achieve the steady state of density current. When longitudinal density rate becomes 15, the released amount ratio of salt and heat changes sharply and in the releasing point, vigorous mixing occurs with increase of discharged amount due to double diffusion. Double diffusion distabilizes gravitational stability and enhances the mixing rate up to $6{\times}10$ times at the lower density ratio comparing to the higher density ratio.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.194-200
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• 2010

Recently, a longitudinal tunnel construction has increased because of subway construction extension, geomorphological effect and the development of construction Technologies etc. When the fire occurs in a tunnel and an underground structure, the many damage of human life and the economic losses are caused. In Korea, fire resistance character study of a tunnel and an underground structure is proceeding. However, when a concrete is exposed to high temperature, study of load carrying capacity reduction and stability evaluation for spalling of a concrete is not enough. Therefore in this study, fire resistance character of a concrete evaluated according to time heating temperature curve(RABT and RWS) and a result compared on virtual fire accident in order to apply fire scenario. Also this study performed thermo-mechanical coupled analysis of a FEM-based numerical technique and estimated fire-induced damage of a tunnel and an underground structure.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.269-275
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• 1997

Wind tunnel test results and their interpretations, which were performed to study the aerodynamic stability of tower of self-anchored suspension bridge, are presented in this paper. Tower and full models were tested under smooth and turbulent flow conditions. In the case of the tower with inclined two columns, the vibration due to wakes were occurred at wide velocity zone because the wakes with various frequencies were generated by inclined upstream column. It has to be emphasized that the vibration characteristics of the tower in the self-anchored suspension bridge may be very sensitive to the longitudinal boundary conditions of the girder at the supports. Because of the two natural frequency of the tower, out-of-plane bending and torsional, were not well separated, coupled motions were observed in a wide range of wind velocity. The effectiveness of corner cut, countermeasure to reduce the tower vibrations, was also studied. It has been found that 1:10, comer cut size to column width, may be the most effective ratio for reducing the vibrations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.330-334
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• 1983

The author carried out an experiment to find out the response of gray rock cod, Sebastes inermis (Cuvier et Valenciennes) to the color light. The experimental tank ($360L{\times}50W{\times}55H\;cm$) was set up in a dark room. Six longitudinal sections with 60 cm intervals are marked in the tank to observe the location of the fish. Water depth in the tank was kept 50 cm level. Light bulbs of 20W at the both ends of the tank projected the light horizontally into the tank. Two different colored filters were selected from four colors of red, blue, yellow, and white, and they were placed in front of the light bulbs to make different colors of light. Light intensity were controlled by use of auxiliary filters intercepted between the bulb and the filter. The fishes were acclimatized in the dark for 50 minutes before they were employed in the experiment. Upon turning on the light, the number of fish in each section was counted 40 times in 30 second intervals, and the mean of the number of fish in each section was given as the gathering rate of the fish. The colors favourited by the fish was found in the order of white, blue, yellow and red. The gathering rate of fish on illumination period was small and comparatively fluctuated with stability. The difference of the gathering rates on two different colors of light was much greater, regardless of illumination period, in day time than in night time.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.7-12
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• 2007

Previously study on structural design of the main wing of the twenty-seat class WIG (Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the Y-mode (lateral mode), the Z-mode (vertical mode) and the $M_{xyz}$-mode (twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the X-mode (longitudinal mode) with the oscillating propeller thrust which occurs in operation.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.419-425
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• 2020

In this paper, when a refractive index grating and a gain grating are simultaneously present in a DFB (Distributed Feedback) laser for a 1.55 um wavelength with two mirror surfaces without an anti-reflective coating, an analysis program was developed to determine the beam distribution of the oscillation mode in the longitudinal direction. As the phases of the index and gain gratings on the mirror faces are varied, the lasing gain and the beam profiles |R(z)| and |S(z)| of the lasing mode with the emitted power ratio P_l/P_r are analyzed and examined in case of δL<0. In order to reduce the threshold current of a oscillation mode and enhance the frequency stability, κL should be greater than 8, regardless of the grating phase values at the mirror surface.

• Geomechanics and Engineering
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• v.22 no.4
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• pp.291-303
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• 2020

The deformation of the rock surrounding a tunnel manifests due to the stress redistribution within the surrounding rock. By observing the deformation of the surrounding rock, we can not only determine the stability of the surrounding rock and supporting structure but also predict the future state of the surrounding rock. In this paper, we used grey system theory to analyse the factors that affect the deformation of the rock surrounding a tunnel. The results show that the 5 main influencing factors are longitudinal wave velocity, tunnel burial depth, groundwater development, surrounding rock support type and construction management level. Furthermore, we used seismic prospecting data, preliminary survey data and excavated section monitoring data to establish a neural network learning model to predict the total amount of deformation of the surrounding rock during tunnel collapse. Subsequently, the probability of a change in deformation in each predicted section was obtained by using a Bayesian method for detecting change points. Finally, through an analysis of the distribution of the change probability and a comparison with the actual situation, we deduced the survey mark at which collapse would most likely occur. Surface collapse suddenly occurred when the tunnel was excavated to this predicted distance. This work further proved that the Bayesian method can accurately detect change points for risk evaluation, enhancing the accuracy of tunnel collapse forecasting. This research provides a reference and a guide for future research on the probability analysis of tunnel collapse.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.6
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• pp.671-678
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• 2004

Statement of problem. Reducing treatment time in implant dentistry is a matter of main concern. There are so many factors affecting the success rate of immediate or early loaded implant for the initial bone response. The especially microscopic properties of implant surfaces playa major role in the osseous healing of dental implant. Purpose. The aims of this study were to perform a histologic and histomorphometric comparison of the healing characteristics anodically roughened surface, HA coated surface and RBM surface implant, and to compare of ISQ values measured by $Osstell^{TM}$ for resonance frequency analysis in dogs mandible during 2 weeks. Material and method. Bone blocks from 2 dogs were caught after covered healing for 0 day(2 h); Group I, 1 week; Group II and 2 weeks; Group III. One longitudinal section was obtained for each implant and stained with hematoxylin and eosin. Histomorphometric analysis was done with Kappa Imagebase system to calculate bone-to-implant contact and bone volumes inside the threads. ISQ values were measured in every time of surgery schedule. Conclusion. The experiment revealed that: 1. The percentages of bone-to-implant contact on the fixture in each group were not significantly different(P > 0.05). 2. The percentages of bone area inside the threads on the fixture in each group were not significantly different(P > 0.05). 3. The ISQ level showed clinical stability of each fixture during 2 weeks(all ISQ level ${\geq}71$ ).