• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.204-211
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• 1993

Boundary element method is applied to simulate nonlinear water waves using Green's identity formula in a numerical wave flume. A system of linear equations is formulated from the governing equation and free surface boundary conditions in order to calculate velocity potential and water surface elevation at each nodal point. The velocity square terms are included in the dynamic free surface boundary condition. The free surface is treated as a moving boundary. the vertical variation of velocity potential being considered in calculating the time derivative of the velocity potential at the free surface. The present method is applied to simulate solitary wave and Stokes 2nd order wave, and shows excellent agreements with their theoretical values.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1712-1716
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• 2008

Performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area has been conducted. From field monitoring results, excessive ground settlement compared to predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation was occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared to field monitoring results after additional surcharge was applied.

• Korean Institute of Interior Design Journal
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• v.18 no.3
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• pp.20-28
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• 2009

Recently, the interest is increased rapidly about the New Hanok as contemporary house. Therefore, the purpose of this paper is to recognize New Hanok as valuable things, which represents traditionality of urban, and to seek how it can be developed as contemporary house. This research analyze the characteristics of New Hanok is built since 2000. The result are as followings. First, many contemporary architects used only the roofing tiles and traditional Hanok elevation design as the design vocabulary of New Hanok. In future, the design vocabulary of New Hanok must be developed variously. Secondly, the construction of New Hanok is possible from the land of minimum $100m^2$ in a city can be found. Thirdly, as a result of having analyzed at the form and the spatial side, it has been analyzed that New Hanok can be divided into 3 types in the form side, which is 'the transfiguration of format', 'the motive borrowing of traditional elements', 'the vertical extension and reconstruction'. In the spatial side, it has been analyzed that New Hanok can be divided into 3 types, which is 'the center of Madang', 'the integration of circulation', 'the transfiguration of design principle'. Lastly, The contemporary architects were analyzed into having a thought that New Hanok must maintain an appearance of Hanok.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.15-20
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• 2005

This is a comparative study where we compare simulation results with model examining the time and direction the fire spreads when it breaks out. Also there is vertical distribution of temperature in carriage where the fire spreads out. This study is about demonstrating how to establish smokeless system in urban vehicle, about its necessity, and about vehicle system restructuring, This study also makes an effort to find more advanced method for efficient fire safety in trains, In existing vehicles, in case of fire, the smoke can't go out when doors are closed and hence it spreads in whole train. Even though the method of using ventilation or exhaust established inside the carriage to throw smoke out is much better than the way of opening end doors in each carriage, this study is trying to do research on second way. Through simulation we see that in second case, even though not as good as the first one, smoke can exit through gates. Even though the first method is better, the second can also be uses to let fire out. We can know that in the first case as the smoke can exit out faster, it provides more safety for people. So this system provides better fire safety condition.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1697-1704
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• 2018

As a key component of lighting location system (LLS) for lightning warning, the atmospheric electric field measuring is required to have high accuracy. The Conventional methods of the existent electric field measurement meter can only detect the vertical component of the atmospheric electric field, which cannot acquire the realistic electric field in the thunderstorm. This paper proposed a three dimensional (3D) electric field system for atmospheric electric field measurement, which is capable of three orthogonal directions in X, Y, Z, measuring. By analyzing the relationship between the electric field and the relative permittivity of ground surface, the permittivity is calculated, and an efficiency 3D measurement model is derived. On this basis, a three-dimensional electric field sensor and a permittivity sensor are adopted to detect the spatial electric field. Moreover, the elevation and azimuth of the detected target are calculated, which reveal the location information of the target. Experimental results show that the proposed 3D electric field meter has satisfactory sensitivity to the three components of electric field. Additionally, several observation results in the fair and thunderstorm weather have been presented.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.79-84
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• 2015

This case report presents surgical endodontic management outcomes of maxillary incisors that were infected via the lateral canals. Two cases are presented in which endodontically-treated maxillary central incisors had sustained lateral canal infections. A surgical endodontic treatment was performed on both teeth. Flap elevation revealed vertical bone destruction along the root surface and infected lateral canals, and microscopy revealed that the lateral canals were the origin of the lesions. After the infected lateral canals were surgically managed, both teeth were asymptomatic and labial fistulas were resolved. There were no clinical or radiographic signs of surgical endodontic management failure at follow-up visits. This case report highlights the clinical significance and surgical endodontic management of infected lateral canal of maxillary incisor. It is important to be aware of root canal anatomy variability in maxillary incisors. Maxillary central incisors infected via the lateral canal can be successfully managed by surgical endodontic treatment.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.235-245
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• 2019

This paper presents a novel methodology for face stability assessment of rock tunnels under water table by combining the kinematical approach of limit analysis and numerical simulation. The tunnels considered in this paper are excavated in fractured rock masses characterized by the Hoek-Brown failure criterion. In terms of natural rock deposition, a more convincing case of depth-dependent mi, GSI, D and ${\sigma}_c$ is taken into account by proposing the horizontally layered discretization technique, which enables us to generate the failure surface of tunnel face point by point. The vertical distance between any two adjacent points is fixed, which is beneficial to deal with stability problems involving depth-dependent rock parameters. The pore water pressure is numerically computed by means of 3D steady-state flow analyses. Accordingly, the pore water pressure for each discretized point on the failure surface is obtained by interpolation. The parametric analysis is performed to show the influence of depth-dependent parameters of $m_i$, GSI, D, ${\sigma}_c$ and the variation of water table elevation on tunnel face stability. Finally, several design charts for an undisturbed tunnel are presented for quick calculations of critical support pressures against face failure.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.297-304
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• 2022

The models used for ionosphere error correction in positioning using Global Navigation Satellite System (GNSS) are representatively Klobuchar model and NeQuick model. Although these models can correct the ionosphere error in real time, the disadvantage is that the accuracy is only 50-60%. In this study, a method for polynomial modeling of Global Ionosphere Map (GIM) which provides Vertical Total Electron Content (VTEC) in grid type was studied. In consideration of Ionosphere Pierce Points (IPP) of satellites with a receivable elevation angle of 15 degrees or higher on the Korean Peninsula, the target area for model generation and provision was selected, and the VTEC at 88 GIM grid points was modeled as a polynomial. The developed VTEC polynomial model shows a data reduction rate of 72.7% compared to GIM regardless of the number of visible satellites, and a data reduction rate of more than 90% compared to the Slant Total Electron Content (STEC) polynomial model when there are more than 10 visible satellites. This VTEC polynomial model has a maximum absolute error of 2.4 Total Electron Content Unit (TECU) and a maximum relative error of 9.9% with the actual GIM. Therefore, it is expected that the amount of data can be drastically reduced by providing the predicted GIM or real-time grid type VTEC model as the parameters of the polynomial model.

• Korean Journal of Optics and Photonics
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• v.32 no.1
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• pp.15-21
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• 2021

In this paper, an aircraft warning light's optical system was designed using an LED light-source module and a collimating Fresnel lens. As for the optical system, a collimator Fresnel lens was designed for each module to satisfy a vertical-elevation center luminous intensity of 20,000 cd and the divergence-angle luminous-intensity standard conditions of the Ministry of Land for Infrastructure and Transport for aircraft warning lights. In addition, the optical system was optimized by adjusting the position and tilt of the LED light-source module and Fresnel lens. By analyzing and comparing the light-distribution characteristics of the optical system, an aircraft-warning-light optical system with optimal performance was obtained.

• Journal of Korean Association for Spatial Structures
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• v.21 no.4
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• pp.23-30
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• 2021

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.