• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.137-144
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• 1992

This paper reports a case study of dynamic consolidation. The objective of the study is to evaluate the effectiveness of ground improvement at the site for Hyundai Petrochemical Compound constructed at Daesan-Myeon, Seosan-Gun in the western shores of Korea. The site ground was prepared by filling on the existing soft marine deposit which consists of a loose granular soil layer and a medium stiff clay layer. For the stabilization of site ground, the compaction was executed in three different procedures with same pounder weigh, drop height and imprint spacing. The post investigation showed that the object was successfully achieved indicating a significant increase of bearing capacity of the treated ground. In this study the effectiveness of dynamic consolidation is evluated for various factors the applied energy, temping sequences, the radial distance from the imprint location and the depth of bed rock.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.44-51
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• 2013

This paper proposes and analyzes recycling of optical phonons emitted by nonradiative decay, which is a major thermal management concern for high-power light emitting diodes (LED), by introducing an integrated, heterogeneous barrier cooling layer. The cooling is proportional to the number of phonons absorbed per electron overcoming the potential barrier, while the multi-phonon absorption rate is inversely proportional to this number. We address the theoretical treatment of photon-electron-phonon interaction/transport kinetics for optimal number of phonons (i.e., barrier height). We consider a GaN/InGaN LED with a metal/AlGaAs/GaAs/metal potential barrier and discuss the energy conversion rates. We find that significant amount of heat can be recycled by the barrier transition cooling layer.

• Wind and Structures
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• v.15 no.1
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• pp.65-86
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• 2012

Over the last decade substantial improvements have been made in our ability to observe the tropical cyclone boundary layer. Low-level wind speed maxima have been frequently observed in Global Positioning System dropwindsonde (GPS sonde) profiles. Data from GPS sondes and coastal Doppler radars were employed to evaluate the characteristics of tropical cyclone vertical wind profiles in open ocean conditions and at landfall. Changes to the mean vertical wind profile were observed azimuthally and with decreasing radial distance toward the cyclone center. Wind profiles within the hurricane boundary layer exhibited a logarithmic increase with height up to the depth of the wind maximum.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.599-608
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• 2000

One dimensional numerical modeling was carried out for the melting behavior of dry snow and the unsaturated flow when heat was supplied from the bottom surface. Discrepancy between the previous experimental data and the present numerical results is substantially reduced by considering the density change of water permeation layer due to the infiltration of meltwater. In the parametric study for effective thermal conductivity, it was found that the effect of this parameter to the behavior of snow melting is minor. Sensitivity analysis showed that the melting time is most sensitive to changes in supplied heat flux, snow temperature, and bulk density, whereas snow bulk density and residual saturation have a significant effect on the height of water permeation layer in snow.

• 보존과학연구
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• s.19
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• pp.179-191
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• 1998

The Dumu of casted iron objects which is the big vessel for the prevention of fire to wood building is conserved in Kyongpok Palace(Dumu sizes：diameter 97cm, height 42cm, thickness 2cm, weight 250kg). The treated objects which some parts were lost, were not corroded, but cracted and broken by an external power, and strongly attached an cement layer on inside surface. First of all cement layer was mechanically removed by pneumatic needle scaler, welded to electric method for broken and cracked pieces, and then the lost sections were restored to use a epoxy resin and glass fiber. In order to prevent a damage during the handling, the restoration section of the inside surface was treated different colour in comparison with original part.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.24-31
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• 2004

Masking effect of the nanoscratched silicon (100) surface was studied and applied to a maskless nanofabrication technique. First, the surface of the silicon (100) was machined by ductile-regime nanomachining process using the scratch option of the Nanoindenter${ \circledR}$ XP. To clarify the possibility of the nanoscratched silicon surfaces for the application to wet etching mask, the etching characteristic with a KOH solution was evaluated at room temperature. After the etching process, the convex nanostructures were made due to the masking effect of the mechanically affected layer. Moreover, the height and the width of convex structures were controlled with varying normal loads during nanoscratch.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.477-483
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• 1997

Experiments have been performed to investigate the formation of smoke layer in case of several furniture fires such as trashcan, chair, carpet, sofa, mattress, and wardrobe in a residential room. As a result of the present investigation, the uniformly distributed fire of carpet showed that the ignition and the initial growth period were relatively short while the fully developed period was considerably long. The concentrated fires such as mattress and wardrobe showed that the ignition and the initial growth period were relatively long. The descending time of the interface heights was within 1-3 minutes to reach around 1m. However, the interface height was lowered to 0.25-0.75m above the floor at the time of the maximum temperature.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.8
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• pp.149-156
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• 2019

In this study, dynamic responses of high - rise buildings were analyzed through the change of horizontal stiffness and yield strength among characteristics of seismic isolation system by applying middle - layer seismic isolation system to high - rise buildings of 120m height. As a result in order to prevent the displacement of the isolation layer and to control the maximum torsion angle, it is possible to appropriately control by increasing or decreasing the horizontal stiffness and the yield strength. However, depending on the maximum torsional angle and the hysteretic behavior of the seismic isolation system, excessive yield strength and horizontal stiffness increase may induce the elastic behavior of the structure and amplify the response. Therefore, it is considered that it is necessary to select the property value of the appropriate isolation device.

• Architectural research
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• v.26 no.2
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• pp.31-39
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• 2024

The numerical study focuses on the analysis of the structural behavior of concrete beams containing outdated concrete and offers an innovative method of strengthening them using carbon-fiber-reinforced polymer sheets (CFRP). The focus is on modeling and analyzing the performance of aged concrete beams strengthened by CFRP in the flexural direction. This study presents an ultimate load model for CFRP-strengthened RC beams featuring outdated concrete layers. Validation through four-point bending tests and finite element modeling demonstrated the efficacy of the model. Findings indicate that CFRP sheets significantly enhance beam strength, particularly in structures with outdated concrete layers, resulting in increased ultimate load capacity. Moreover, an inverse relationship between ultimate load and concrete layer height was observed, with the CFS-21-15-30 sample exhibiting the most substantial reduction. Validation of the model was achieved using finite element analysis con-ducted in Abaqus software.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.85-90
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• 2012

In this paper, we compared and analyzed 3D silicon-oxide-nitride-oxide-silicon (SONOS) multi layer flash memory devices fabricated on nitride or oxide layer, respectively. The device fabricated on nitride layer has inferior electrical properties than that fabricated on oxide layer. However, the device on nitride layer has faster program / erase speed (P/E speed) than that on the oxide layer, although having inferior electrical performance. Afterwards, to find out the reason why the device on nitride has faster P/E speed, 1/f noise analysis of both devices is investigated. From gate bias dependance, both devices follow the mobility fluctuation model which results from the lattice scattering and defects in the channel layer. In addition, the device on nitride with better memory characteristics has higher normalized drain current noise power spectral density ($S_{ID}/I^2_D$>), which means that it has more traps and defects in the channel layer. The apparent hooge's noise parameter (${\alpha}_{app}$) to represent the grain boundary trap density and the height of grain boundary potential barrier is considered. The device on nitride has higher ${\alpha}_{app}$ values, which can be explained due to more grain boundary traps. Therefore, the reason why the devices on nitride and oxide have a different P/E speed can be explained due to the trapping/de-trapping of free carriers into more grain boundary trap sites in channel layer.