• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.99-105
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• 2010

The concentration and size analysis of in-situ suspended particulate material were measured using an optical instrument, LISST-100, in the bottom layer at the three inlets of the Seomjin River Estuary, mouth of Gwangyang bay, and Gwangyang bay-side of the Namhae Bridge. In the Seomjin river estuary and mouth of Gwangyang bay-side of the Namhae Bridge, the in-situ mean grain size of the suspended material changed from a uni-modal distribution with a dominant peak at a coarse fraction to a bi-modal distribution with a secondary peak at the finer particles. Seomjin River. The interactions between suspended particulate concentration and beam attenuation coefficient of suspended particulate matters depended on the supply of finer and coarser particles in the mouth of Gwangyang Bay and Seomjin River. So, interactions reflected difference of the concentration, mean size and sorting of suspended particulate matters. The difference of interaction showed dynamic behaviors to the resuspension and deflocculation processes increased river discharge. This showed that it may be possible to use the interactions between the suspended particle concentration and beam attenuation coefficient to monitor the temporal and spatial distributions of in-situ particles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1341-1344
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• 2003

Studies on impact damage of composite laminate shells were fewer compared with those on impact behaviors to analyze time-load, displacement-load and impact energy - energy absorption. Up to date the studies were not enough to demonstrate suitability of their results because they were dependent on theories and numerical analyses. In particular, it is a well-known fact that there was a correlation between initial peak load and damage resistance of composite material flat plates imposed with low-speed impact, but studies on composite material shells with curvature were also very few. Actually structures such as wings or moving bodies of airplanes, motor cases and pressure containers of rockets are circular. And as low-speed impact load is imposed for optimal design of take-off and landing, and containers of airplanes, it is very important to analyze evaluation of behaviors and damaged areas. Therefore, in this paper to evaluate the impact characteristics of the CFRP laminate shell according to size of curvature quantitatively, it was to identify energy absorption and impact damage instruments according to change of impact speed.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.945-952
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• 2012

The sorption of selenium ions onto iron and iron compounds as a disposal container material and its corrosion products, and onto bentonite as a buffer material, was studied to understand the behaviors of selenium in a waste repository. Selenite was sorbed onto commercial magnetite very well in solutions at around pH 9, but silicate hindered their sorption onto both magnetite and ferrite. Unlike commercial magnetite and ferrite, flesh synthesized magnetite, green rust and iron greatly decreased selenium concentration even in a silicate solution. These results might be due to the formation of precipitates, or the sorption of selenide or selenite onto an iron surface at below Eh= -0.2 V. Red-colored Se(cr) was observed on the surface of a reaction bottle containing iron powder added into a selenite solution. Silicate influences on the sorption onto magnetite and iron for selenide are the same as those for selenite. Even though bentonite adsorbed a slight amount of selenite, the sorption cannot be ignored in the waste repository since a very large quantity of bentonite is used.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.318-325
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• 2000

Dynamic behaviors of saturated-fatty acids $C_{16}$, $C_{18}$, $C_{20}$ and 8A5H with azobenzene were measured by displacement current method when the molecules are stimulated by pressure light and heat. When a barrier was compressed I-A, $\pi$-A isotherms of $C_{16}$, $C_{18}$, and $C_{20}$ were similar to each other but the displacement current of $C_{20}$ which has a long alkyl chain was relatively low. 8A5H showed the form of double liquid films and had a reversible reaction when a barrier was compressed and then expanded. When the molecules of 8A5H were stimulated by 365[nm] light the positive currents which were generated by the structural changes from trans to cis were measured. But the negative currents of the structural changes from cis to trans by 450[nm] light were too weak to detect. When the temperature of the water subphase was increased the surface pressures of the monolayers were increased early because of the thermal activations of the molecules and the double liquid films of 8A5H were disappeared above 40[$^{\circ}C$]EX>].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.25-28
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• 2001

The objectives of this paper are to demonstrate the electrical degradation phenomena with Si atom's behaviors in the grainboundary of semiconducting ZnO ceramics. The ZnO ceramic devices used in this investigation were fabricated by standard ceramic techniques. Especially, $SiO_2$ were added to analyze the degradation characteristics with Si and sintered in oxygen ambient at $1300^{\circ}C$. The conditions of DC degradation test were $115{\pm}2^{\circ}C$ for 13h. Using XRD and SEM, the phase and microstructure of samples were analyzed respectively. E-J analysis was used to determine $\alpha$. Frequency analysis was accomplished to understand $R_g$ and $R_b$ at the equivalent circuit. Electrical stability improved as the amount of $SiO_2$ addition increased. This results were explain by the quantitative analysis and the line scanning method of EPMA.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.55-60
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• 2010

Rockfill zones in CFRD consist typically of large granular materials, usually the maximum particle size up to several meters, which makes laboratory testing to determine the mechanical properties of rockfill difficult. Commonly, the design strength of the rockfills is obtained by scaling down the original rockfill materials and performing laboratory strength tests for the reduced size materials. The objective of the present study is to investigate the effect of particle size on the shear behavior and the strength for granular materials. A series of large-scale triaxial tests was conducted on large granular materials with the maximum particle size varying from 20 to 50mm. The test results showed that overall shear behaviors were similar between the samples with different particle sizes while there were slight differences in the magnitudes of the peak shear stress between the samples. In addition, a simulation of the granular material with the max. particle size of 20mm was performed using DEM code, $PFC^{2D}$, and compared with the test results. The deviatoric stress versus strain behaviors of experimental and numerical tests were found to be matched well up to the peak stress state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.282-286
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• 2003

We investigated the effects of calcination temperature and sintering additives on the sintering behaviors and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$. Highly densified samples were obtained at the sintering temperatures below $1000^{\circ}C$ with additions of 0.45 wt.% $Bi_2O_3$ and 0.55 wt.% $V_2O_5$. From the examination of the existing phases and microstructures before and after sintering of $(Zn_{0.8}Mg_{0.2})TiO_3$ system calcined at the various temperatures ranging from $800^{\circ}C$ to $1000^{\circ}C$, it was found that high $Q{\times}f_o$ values were obtained when unreacted or second phases in calcined body were reduced. When calcined at $1000^{\circ}C$ and sintered at $900^{\circ}C$, it consists of hexagonal as a main phase with uniform microstructure and exhibits $Q{\times}f_o$ value of 42,000 GHz and dielectric constant of 22.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.635-636
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• 2006

In this study, the diffusion behaviors of C and Co in liquid phase sintering of WC-Co system were investigated whether these two components diffused in the same direction in case of having opposite gradient each other with not being $\eta$ phase. The green compacts with controlled compositions in not being of $\eta$ phase and gradient composition which one is WC-5Co-1.2%C, the other is WC-XCo-0.2%C (where X = 5, 10, 15, 20, 25) were sintered at $1350^{\circ}C$ and $1400^{\circ}C$ and then the diffusion behaviors of C and Co were investigated by analyses of compositional change, also determined for microstructure and microhardness. Also, same testing was carried out on the specimens with dual layers sintered in upright and reverse positions to evaluate the effect of gravity on the diffusion in liquid Co. From the results of this study, we can find the fact that the direction of diffusion for C and Co in WC-Co system during liquid phase sintering was different and the effect of gravity for the liquid was insignificant. Also other physical properties were changed on the diffusion of elements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.227-230
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• 2004

As the organic acids were added in the slurry, zeta potential of alumina was changed to negative value and IEP value was shifted from alkaline to acidic pH. In citric acid based slurry, Cu surface continuously dissolved and etching depth linearly increased. On the contrary, passivation layer was grown on Cu surface in oxalic acid based slurry. As the platen rotation speed increased, Preston coefficient decreased in both slurries. With oxalic acid based slurry, at low velocity, removal rate is high value because of high friction force compared to citric acid based slurry. As platen velocity increased, removal of Cu in citric acid based slurry became higher value than oxalic acid based slurry. Typical lubrication behaviors were observed in both slurries. As Sommerfeld number increased, COF values gradually decreased and then re-increased. It indicated that lubrication was changed to direct contact or semi-direct contact mode to hydro-lubrication mode.

• Journal of the Korea Fashion and Costume Design Association
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• v.20 no.1
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• pp.93-107
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• 2018

A questionnaire survey was conducted on male and female college students living in Busan in May 2015 to study customer types and purchasing behaviors based on the benefit sought from undergarments. This study used a total of 460 data reports collected from 203 male and 257 female college students. The results of this study were as follows. First, the undergarment benefits sought were divided into material and function, harmony of outerwear and underwear and design. Consumers were categorized into function seekers, brand and design seekers, and undergarment indifferent customers. In addition, while male college students were likely to be function seekers, female college students were mostly brand and design seekers. Second, both male and female respondents showcased significant differences in the undergarment benefits sought depending on their customer type. Based on the customer type, male college students showed a greater difference in the undergarment benefits they sought when compared to their female counterparts, and marked differences were found in male respondents' undergarment material and function factors and female respondents' harmony factor of outerwear and underwear. Based on their sex, a significant difference in the harmony factor of outerwear and undergarments was observed. Third, after examining the purchasing behavior influenced by the customer type, this study found that both male and female students had undergarment purchasing behavior differences depending on their customer type, while function seekers and design seekers were likely to exhibit similar behaviors in purchasing undergarments regardless of their sex, except for their preferred image and purchasing method of undergarments. However, among the indifferent group of customers, there were significant differences depending on their sex.