• Journal of the Korean Society of Costume
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• v.59 no.6
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• pp.29-40
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• 2009

On April 28th of 2006, a set of Buddha's reliquary was excavated from the pagoda in n Nacsan Temple. According to the record, the relics were put in the pagoda in the 18th year of King SookJong in the Chosun Dynasty (1692). The present paper examines ten pieces of wrapping clothes covering reliquary found in the pagoda. They are especially precious data in the history of textiles because they were blocked off from outside and was preserved in good condition with vivid colors still remaining after more than 300 years. Of the ten pieces of wrapping cloth, five were double-layered and the other five were single-layered. They include 15 pieces of silk fabric but, excluding repeated use of the same silk fabric, the total of 11 pieces of silk fabric were examined. All 11 kinds of silk fabric were patterned, 9 of which were Satin and the other 2 were Twill. Of the 9 Satin pieces, 8 pieces were 5-end satin which had the ground of 5-end warp satin with the figure of 5-end weft satin. The remaining 1 Satin piece were more splendid with prominent figures by using warp and weft of different colors. The 2 Twill pieces used twill weave-the ground was 3-end warp twill and the figures were 5-end weft twill. Both of the Twill pieces were weaved with character patterns, partly using wrapped gold thread as supplementary weft. The patterns of 11 pieces of silk fabric include flower, dragon/phoenix, cloud, and geometric patterns. Five were flower patterns, three were dragon/phoenix patterns, two were geometric pattern, and one was cloud pattern. In addition, various treasure patterns, character patterns were utilized as supplementary patterns. The flower and phoenix patterns reflect characteristics of the textiles of the 17th century whereas check pattern and cloud pattern were very unique.

• Geotechnical Engineering
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• v.11 no.2
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• pp.139-156
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• 1995

A set of field investigations was performed to estimate accurately the predominant periods of seismic 8round motions and the attenuation characteristics of the seismic ground vibration. Predominant periods of ground motions were estimated from the measurement of the continuous microseismic vibratins of certain periods, inherent in the ground and in the buildings, utilizing the high sensitivity digital velocity seismometer consisting of 3-component geophones and a digital seismograph. Estimated predominant periods of microseismic vibraion of the ground(measured on'the ground surface) and the building (measured on the second floor) were in the range of 0.18~0.235 sec. and 0.26~0.31 sec. respectively. The subsurface structure of the site ground was surveyed by the seismic refraction method utilizing the digital seismicwave probing system. The ground structure was found to be a two-layered system : an upper top soil layer of 7m in thickness with the P-wave velocity of 662m1sec and a lower layer of silty-clayey soils with the P -wave velocity of 2210m1 sec. The attenuation characteristics of the seismic ground vibrations were determined by the amplitude decay measurement method us;ng the Seisgun, which produces strong artificial seismic energy. Measured spatial attenuation coefficients of the ground vibration in vertical(Z) longitudinal(X), transverse(Y) direction were 0.1137, 0.0025, and 0.0290 respectively. Estimated Spartial QP's (inverse of the specific dissipation constant w.r.t. shear waved of X, Y, and Z directions were in the range of 5.913~7.575, 32.371~41.452, 2.794~3.579 re spectively. This indicates that aseimic design of the structures on the site should take stronger consideration regarding the earthquake resistance characteristics of the structures against longitudinal ground motion.

• Earthquakes and Structures
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• v.14 no.4
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• pp.313-322
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• 2018

The present study is dedicated to investigate the SH body-as well as Love-waves propagation effects in porous media with uncertain porosity and permeability. A unified formulation of the governing equations for one-dimensional (1-D) wave propagation in anisotropic porous layered media is presented deterministically. The uncertainties around the above two cited parameters are taken into account by random fields with the help of Monte Carlo Simulations (MCS). Random samples of the porosity and the permeability are generated according to the normal and lognormal distribution functions, respectively, with a mean value and a coefficient of variation for each one of the two parameters. After performing several thousands of samples, the mathematical expectation (mean) of the solution of the wave propagation equations in terms of amplification functions for SH waves and in terms of dispersion equation for Love-waves are obtained. The limits of the Love wave velocity in a porous soil layer overlaying a homogeneous half-space are obtained where it is found that random variations of porosity change the zeros of the wave equation. Also, the increase of uncertainties in the porosity (high coefficient of variation) decreases the mean amplification function amplitudes and shifts the fundamental frequencies. However, no effects are observed on both Love wave dispersion and amplification function for random variations of permeability. Lastly, the present approach is applied to a case study in the Adapazari town basin so that to estimate ground motion accelerations lacked in the fast-growing during the main shock of the damaging 1999 Kocaeli earthquake.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.156-162
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• 2004

In recent years, mobile ad-hoc networks have received a great deal of attention in both academia and industry to provide anytime-anywhere networking services. As wireless networks are rapidly deployed, the security of wireless environment will be mandatory. In this paper, we describe a group key management architecture and key agreement protocols for secure communication in mobile ad-hoc wireless networks (MANETs) overseen by unmanned aerial vehicles (UAVs). We use implicitly certified public keys method, which alleviates the certificate overhead and improves computational efficiency. The architecture uses a two-layered key management approach where the group of nodes is divided into: 1) Cell groups consisting of ground nodes and 2) control groups consisting of cell group managers. The chief benefit of this approach is that the effects of a membership change are restricted to the single cell group.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.481-489
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• 2006

Two dimensional diffusion model test was conducted to investigate the sedimentation properties and consolidation process of reclaimed ground using dredging coarse soil which is composed of passing amount 20 percentage and 45 percentage of #200 sieve size respectively. The passing amount of #200 sieve size affected on sedimentation properties. The coarse soil which is passing amount of 20 percent showed that the sedimentation structure was layered type and passing amount of 45 percentage was wall-partition type according diffusion distance. Furthermore, the water content of surface and section, and distribution of fine soil were changed according to diffusion distance. and the change amount of pore water pressure and strength property when soil is diffused, segregated and accumulated can be applied efficiently in design of dredging and reclamation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.82-92
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• 2012

This study proposed a new non-destructive evaluation method for concrete bridge deck deterioration using ground penetrating radar (GPR). To calculate dielectric constant of the concrete bridge deck, an extended common mid-point (XCMP) method was developed for a two-layered structure using an air-coupled GPR antenna setup. The deterioration conditions of the concrete bridge deck such as deterioration depth was evaluated based on the dielectric constant and surface-to-average dielectric constant ratio of the concrete bridge deck. A GPR field test was conducted on an old concrete bridge with asphalt concrete surfacing to validate the new evaluation method. The test results showed that the newly proposed method estimated pavement thickness and deterioration depth of the concrete deck in a reasonable level.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.55-61
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• 2023

This paper describes the comparative results of measured and predicted values for the horizontal displacement of earth retaining wall based on two field cases, In order to examine the application of lateral earth pressure to the earth retaining wall considering the typical ground characteristics (clinker layer) in Jeju. The prediction of the lateral earth pressure causing the horizontal displacement of the retaining wall was performed by elasto-plastic analysis using Rankine earth pressure, Terzaghi & Peck modified lateral earth pressure, and Tschebotarioff lateral earth pressure. As a result, it was confirmed that the maximum horizontal displacement predicted at site A was about 5 times larger than the measured value, and the ground with maximum horizontal displacement occurred by the prediction was found to be the clinker layer. In the case of site B, the predicted value was 4 to 7 times larger than the measured value. In addition, the ground with maximum horizontal displacement and the tendency of horizontal displacement were very different depending on the prediction method. This means that research on lateral earth pressure that can consider regional characteristics needs to be continued, because it is due to the multi-layered ground characteristics of the Jeju area in which bedrock layers and clinker layers are alternately distributed,

• Journal of the Korean Solar Energy Society
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• v.24 no.4
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• pp.19-25
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• 2004

A numerical study is performed to investigate the effect of sun tracking on the thermal performance of the evacuated compound parabolic concentrator (CPC) collectors. The evacuated CPC collectors consist of a two-layered glass tube, a copper tube and a reflector. The collector has a copper tube as an absorber and a reflector inside a glass tube. The water is used as a working fluid. The length and the diameter of the glass tube are 1,700mm and 70mm, respectively. The length and the diameter of the copper tube are 1,700mm and 25.4mm, respectively. Ray tracing analysis is carried out in order to compare absorbed heat fluxes on the absorber surface of the stationary and tracking collectors. The collected energy is calculated and compared with that on a fixed surface tilted at $35^{\circ}$ on the ground and facing south. The results indicate that the collected solar energy of the sun tracking system is significantly larger than that of a stationary collector. The sun tracking evacuated CPC collectors show a better performance with an increase in the thermal efficiency of up to 14% compared with an identical stationary collector.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.3-44
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• 1999

This paper discusses the lateral behavior of single and group piles in homogeneous and non-homogeneous(two layered) soil. In the single pile, the model tests were conducted to investigate the effects on ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer, boundary rendition of pile head and tip, embedded pile length, pile construction condition, ground condition with saturate and moisture state in Nak-Dong river sand. Also, in the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, boundary condition of pile head and tip, eccentric load and ground condition. The maximum bending moment and deflection induced in active piles were found to be highly dependent on the relative density, pile construction condition, boundary condition of pile head and tip. Based on the results obtained, it was found that the decrease of lateral bearing capacity in saturated sand was in the range of 31% - 53% as compared with the case of dry sand. Also, in the group pile, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8%, and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. In this study, the program is developed by using the modified Chang method which used p - y method and the exact solution of governing equation of pile and it can be used to calculate the deflection, bending moment and soil reaction with FDM in non-homogeneous soil. In comparing the modified Chang method with field test results, the predict results shows better agreement with measured results in field tests.

• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.53-62
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• 2014

In Korea, in general, separation distance between existing parallel tunnels was set at two to five times as distant as the diameter of the tunnels according to ground conditions. Recently, however, actual applicability of closely spaced parallel tunnels whose distance between tunnel centers was shorter than the diameter has increased due to environmental damages resulting from massive cutting, restriction in purchase of required land, and maintenance of linear continuity. In particular, when the pillar width of tunnel decreases, the safety of pillars affects behaviors of the tunnel and therefore the need for diverse relevant studies has emerged. However, research so far has been largely confined to analysis of behavior characteristics of pillars, or parameters affecting design, and actually applicable and quantitative data have not been presented. Accordingly, in order to present a stability evaluation method which may maximally reflect construction conditions of spots, this study reflected topographical and stratigraphic characteristics of the portal part with the highest closeness between the tunnels, simulated multi-layer conditions with rock mass and complete weathering, and assessed the degree of effect the stability of pillars had on the entire tunnels through numerical analysis according to changes in pillar width by ground strength. This study also presented composite analysis result on ground surface settlement rates, interference volume rates, and average strength to stress and a formula, which may be applicable to actual work, to evaluate safety rates of closely spaced parallel tunnel pillars and minimum pillar width by ground strength based on failure criteria by Hoek-Brown (1980).