• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.90-95
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• 2000

Cycle life test was carried out to evaluate the failure modes of the gel type nth batteries at $C_5$ currents and $100\%$ DOD. When the batteries were charged at constant voltage of 2.40 V and 2.50 Vi respectively, cycle lift was over 1,000 cycles. The batteries lost 426.4 g and 391.2 g of electrolyte far each case after the weight measurement. The battery charged at 2.50 V was shown to have a better cyclic performance than charged at 2.40 V, and the amounts of electrolyte loss was proportional to charge factor. After cycle test, the micro-structure of positive active material was completely changed and the corrosion layer of positive grid was about $50{\mu}m$. Failure mode of the positive plate of the gel type battery was a shedding of the positive active material, and the cause of discharge capacity decrease was found to be a electrolyte loss.

• Food Science and Preservation
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• v.12 no.3
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• pp.292-298
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• 2005

Kochujang(Korean red pepper paste) of 600 g was fermented in the different types of vessels (glass, polypropylene(PP), polyethylene terephthalate(PET), stainless steel and Korean porcelain called onggi) with 627 mL of volume during 4 months. The quality changes were monitored for physical, chemical and microbiological attributes. Onggi which had high porosity in the micro-structure provided kochujang with higher microbial counts of aerobic bacteria, lactic acid bacteria and yeasts than those of the other containers. Compared to kochujang fermented in the other containers, kochujang in Onggi showed higher protease activity, amino type nitrogen, and free amino acid content. The kochujang in Onggi also attained higher acidity, lower pH and higher reducing sugar concentration than those in the other containers. All changes were completed 2 or 3 months. Onggi showed water loss and salt increase of the kochujang comparable to those in the other vessels, which was from gradual clogging of the micropores during storage. All physical, chemical and microbiological changes made the kochujang in Onggi attain the sensory quality significantly better than those fermented in the other vessels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.84-89
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• 2009

The turbid/translucent, near colorless(milky) metamorphic sapphire samples from Sri Lanka have been characterized after the heat treatment in $N_2$ at $1650^{\circ}C$. As-received sapphire specimens became bluish-colored and exhibited more clarity after the heat treatment. It was found that the color change at inclusions zoning region is attributed by the dissolution. As received samples contain the micro/nano inclusions such as rutile($TiO_2$), ilmenite($FeTiO_3$), spinel($MgAl_{2}O_{4}$)/ulvospinel($Fe_{2}TiO_{4}$) and apatite($Ca_5(PO_4)_3$), which were dissolved by the heat treatment and form the blue color through $Fe^{2+}/Ti^{4+}$ charge transferring. The microstructures become different because as the dissolution of apatite($Ca_5(PO_4)_3(OH,F,Cl)$) in alumino silicates($Al_{2}SiO_{5}$) occurred, resulting in morphological change with the appearance of(Ca, Mg, Al) silicate on the surface. Both as-received and heat treated samples showed the rhombohedral crystal structure of $Al_{2}O_{3}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.94-98
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• 2014

$LiCoO_2$ thin film has received diverse attention as cathodes material of thin-film micro-batteries. In this study, $LiCoO_2$ thin films were synthesized on Au substrates by sol-gel spin coating method and an annealing process. Their structures were studied using X-ray diffraction and Raman Spectroscopy. The particle morphologies of these thin films were observed by Scaning electron microscope. From the results of X-ray diffractometry and Raman Spectroscopy analyses, it was found that as-grown films had the structure of spinel (LT-$LiCoO_2$) and layered-Rock-salt (HT-$LiCoO_2$) at $550^{\circ}C$ and $750^{\circ}C$ respectively. The annealed films at $650^{\circ}C$ were presumed to be the mixed state of these two types. Throlugh the scanning electron microscope, It was estimated that the particle size in as-grown films at $750^{\circ}C$, were larger crystilline particle than in those at the other lower temperature and well distributed in the film.

• Korean Journal of Social Welfare
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• v.55
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• pp.181-204
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• 2003

The purpose of this study was to offer a comprehensive analysis of the changing trends of the Korean income packaging, poverty rate, and level of income inequality from 1996 to 2002. In order to do that, this study used the micro-data of "Income and Expenditure Survey of Urban Households" by the National Statistical Office(NSO). Major results were as follows: (1) A ratio of public transfer in family income packaging increased at the DJ administration. (2) Poverty rate and Gini coefficient, which were 7.8% and 0.29 in 1996, rose to $8.8{\sim}10.4%$ and $0.30{\sim}0.34$ respectively during the year of 1998-2002. (3) However, poverty reduction effect and income inequality reduction effect of public income transfer increased preferably at the DJ administration. Those effects increased more since the enactment of National Basic Livelihood Security in 2000. Therefore, government should provide more national welfare programs to reduce the poverty rate and to improve better structure of income distribution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.381-387
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• 2017

Dehydrogenation from the hydrolysis of a sodium borohydride ($NaBH_4$) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.％) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a $NaBH_4$ solution over both a single microchannel with a hydraulic diameter of $300{\mu}m$ and a staggered array of micro pin fins in the microchannel with hydraulic diameter of $50{\mu}m$. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.％. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

• Archives of design research
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• v.17 no.2
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• pp.373-382
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• 2004

The value of Korean ginseng has been known in the world since the 4th century B. C. Red ginseng is hot-steamed, and then dried for the purpose of long-term storing. Through the steaming and drying process, its moisture rate is reduced to 14% and its color becomes citrine or light yellowish brown. Its hardened structure enables long-term storage without any deformation. Especially, Korean red ginseng contains substances that promote micro-physiological activities which are not found in American or Sanchi ginseng. Ginseng is produced in diverse forms for the customer's convenience. In this study, these are classified as sliced, dried, and honeyed ginseng, granulated tea, extract, powder, capsules, tablets, drinks and candy. Package design is one of the most effective method in the marketing fields. However, in this research, we found that red ginseng packages are not variously and properly developed in materials and designs. The research pointed out the problems and discuss ways and means of the package design.

• The Journal of Engineering Geology
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• v.7 no.2
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• pp.91-99
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• 1997

In general, there are various approaches available in literature to model discontinuous rock masses and engineers are often confused which one to use for designing structures in rock masses. Modelling rock masses can be classified mainly into two approaches. One is discrete modelling of intact rock and discontinuities and the other is the equivalent continuum modelling. In this study five models are selected ;(1) Crack tensor model, (2) Equivalent volume defect model, (3) Damage model, (4) Micro - structure model (Parallel model and Series model), and (5) Homogenization model. Most of these models are mainly concerned with how to define additional strain due to discontinuities over the representative elementary volume (REV) and how to relate the stress field of discontinuities to that acting on the REV. The characteristics of these models are clarified by comparing with results of some laboratory tests.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.61-67
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• 2018

Grouting is reinforcement or cutoff method which uses the hardening agent which is typically represented by portland cement and injected into the ground or the structure. When mixing the cement in powder form with water, the particles tend to cohere each other. Once they cohered, the particle size tends to become larger while injection efficiency becomes lower. This study, in a bid to reduce the cohesion of cement, the screen was set inside the grout mixer so that the cement particles are separated while vibrating them. To validate the effect of vibration screen, comparison test was conducted by using ordinary portland cement, slag cement and micro cement. Viscosity test, bleeding test and grain-size analysis indicated that the characteristics varied significantly after passing through the vibration filter. It is expected that the vibration filter installed inside the grout mixer will reduce the cement cohesion when mixing with water.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.761-769
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• 2007

We made 712 thermal property measurements on igneous, metamorphic and sedimentary rock samples from Gyeonggi-do, Gangwon-do and Chungchung-do, Korea. The average thermal conductivities of igneous, metamorphic and sedimentary rocks are 3.58W/m-K, 4.16W/m-K and 4.53W/m-K, respectively. Thermal conductivity of granite and gneiss are 2.13-5.87W/m-K and 2.26-6.67W/m-K, with average values of 3.57W/m-K and 3.945W/m-K, respectively. The average of thermal diffusivities are $1.43mm^2/sec\;and\;1.55mm^2/sec$, respectively; the average of specific heat values are 0.914J/gK, 0.912J/gK for granite and gneiss samples, respectively. The thermal conductivity of a rock type generally have a wide range because it depends on various factors such as dominant mineral phase, micro-structure, anisotropy, and so on.