• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.959-961
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• 2003

Cirrus clouds observation was conducted using a lidar system in order to measure their height, thickness and optical depth at Kwangju (35$^{\circ}$10'N, 126$^{\circ}$53'), Korea in winter, December 2002, and spring March and April 2003. Cirrus clouds at high altitude can be distinguished from atmospheric aerosols location by high depolarization ratio and high altitude. Cirrus clouds were observed at 5${\sim}$12km altitudes with a high depolarization ratio from 0.2 to 0.5. Optical depth of cirrus clouds had varied from 0.28 to 1.81. Radiative effect of observed cirrus cloud on climate system was estimated to be negative net flux from ?0.24 to ?31.04 W/m$^{2}$.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1187-1194
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• 2006

This study analyzed characteristics of soft ground consolidation according to depths of vertical drain. As the result, when the depth ratio of vertical drains (L/D) were 0.5, 0.7, and 1.0, consolidation characteristics were similar up to 70% in consolidation degree under one-dimensional drain condition. However, above this degree, consolidation speed became slower as L/D became smaller. Two-dimensional drain condition also showed a similar tendency, but when L/D was 1.0, the consolidation speed was relatively higher.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.152-159
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• 1999

This study is to investigate the effects of warm deep drawing with aluminum sheets of A1050-H16 and A5020-H32 for improving deep drawability. Experiments for producing circular cups and square cups were carried out for various working conditions, such as forming temperature and blank shapes. The limit drawing ratio(LDR) of 2.63 in warm deep drawing of circular cups in case of A5020-H32 sheet, whereas LDR of 2.25 in case of A1050-H16, could be obtained and the former was 1.4 times higher than the value at room temperature. The maximum relative drawing depth for square cups of A5020-H32 material was also about 1.92 times deeper than the depth drawn at room temperature. The effects of blank shape and forming temperature on drawability as well as thickness distribution of drawn cups were examined and discussed.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2544-2547
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• 2008

A micro channel heat sink has been studied and optimized for mixed pressure driven and electroosmotic flows through three-dimensional numerical analysis. The effects of ionic concentration represented by zeta potential and Debye thickness are studied with the various steps of externally applied electric potential. Optimization of the micro channel heat sink has been performed considering two design variables related to the micro channel width, depth and fin width. The surrogate-based optimization is performed using a search algorithm taking overall thermal resistance as objective function. The thermal resistance is found to be more sensitive to channel width-to-depth ratio than fin width-to-depth of channel ratio.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.799-802
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• 2000

There are many methods that extract the depth information based on the blurring ratio for object point in DFD(Depth from Defocus). However, it is often difficult to measure the depth of the object in two-dimensional images that was affected by various elements such as edges, textures, and etc. To solve the problem, new DFD method employing the texture classification with a neural network is proposed. This method extracts the feature of texture from an evaluation window in an image and classifies the texture class. Finally, It allocates the correspondent value for the blurring ratio. The experimental result shows that the method gives more accurate than the previous methods.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.73-81
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• 2003

In this paper, salt damage resistance of high durable concrete was tested. High durable concrete was made by using low water cement ratio, chemical admixture called super-durable admixture and mineral admixtures such as fly-ash, ground granulated blast-furnace slag, silica fume. Two kinds of salt damage resistance test were carried out. One method is chloride ion penetration test(ASTM C1202), and the other one is depth of chloride penetration test in saline solution. Test results were as followers: 1) The depth of chloride ion penetration increased exponentially as water cement ratio was increased and time passed. 2) Super-durable admixture had little effect on the improvement of salt damage resistance of concrete. 3) Silica fume and ground granulated blast-furnace slag were effective on salt damage resistance because of pozzolanic reaction, but fly-ash had a little effect.

• Structural Engineering and Mechanics
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• v.28 no.6
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• pp.635-658
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• 2008

An application is presented of a modified Vlasov model to the free vibration analysis of plates resting on elastic foundations. The effects of the subsoil depth, the ratio of the plate dimensions, the ratio of the subsoil depth to the plate dimension in the longer direction, and the value of the vertical deformation parameter within the subsoil on the frequency parameters of plates on an elastic foundation are investigated. This analysis has been caried out by the aid of a computer program. The first ten frequency parameters are presented in tabular and the graphical forms to evaluate the effects of the parameters considered in this study. Then mode shapes corresponding to the first six of the frequency parameters are given in graphs. It is concluded that the effect of the subsoil depth on the frequency parameters of the plates on an elastic foundation is generally larger than those of the other parameters considered in this study.

• Nanomaterials
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• v.12 no.24
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• pp.4457-4467
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• 2022

SiO₂ etching characteristics were investigated in detail. Patterned SiO₂ was etched using radio-frequency capacitively coupled plasma with pulse modulation in a mixture of argon and fluorocarbon gases. Through plasma diagnostic techniques, plasma parameters (radical and electron density, self-bias voltage) were also measured. In this work, we identified an etching process window, where the etching depth is a function of the radical flux. Then, pulse-off time was varied in the two extreme cases: the lowest and the highest radical fluxes. It was observed that increasing pulse-off time resulted in an enhanced etching depth and the reduced etching depth respectively. This opposing trend was attributed to increasing neutral to ion flux ratio by extending pulse-off time within different etching regimes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.37-42
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• 2018

With advancements in digital image production technology, the branch of stereoscopic image technology has also been undergoing active development. Accordingly, research and development on cutting-edge display products for mounting stereoscopic images are currently being pursued. There are various problems that can occur when viewing 3D images. Because viewers feel visual fatigue while perceiving the depth of the images provided via an artificial method, a negative human factor such as visual fatigue has become one of the most prominent concerns, especially as it is a factor that affects the ongoing maintenance of 3D images. Therefore, by identifying the factors affecting the depth of the graphic images provided in 2D images, and subsequently using this information to develop an image processing method, we conducted depth-related experiments and analysed them under the assumption that stereoscopic images could be reproduced without visual fatigue. Thus, we analysed the most significant factors related to depth and verified the interactions by performing depth-related factors-based ANOVA variance analysis by differentially applying the texture, colour temperature, and contrast ratio to graphic images. We determined the significance of the factors related to depth and proposed a method to improve depth based on an analysis of the results of the experiments conducted in this study.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.4
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• pp.475-482
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• 2011

This study, a basic study to improve aerodynamic characteristic of a wind blade, explored through CFD how much the lift to drag ratio improves according to the shape of groove formed on the surface of airfoil NACA0015. This study found out that the ratio improves by 8.7% when the ratio between boundary layer(${\delta}$) and the depth of groove(h), the ratio between the depth of groove(h) and the width of groove(d) and the ratio between the length(p) from one groove to the other and the width of groove are 1.1, 0.1 and 1.2 respectively. The number of grooves is two. It was also confirmed that the improvement of the lift to drag ratio is maintained after certain angle of attack.