• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.445-448
• /
• 2006

Mix design of C80A which is applied to the vertical members of The Burj Dubai Tower, the tallest building of the world, was performed so as to meet the requirements of rheological property, mechanical properties & construction sequences based on material analysis in Dubai, UAE. Experimental investigations were carried out to evaluate & optimize the quantities of total binders, the proportions of Micro Silica, Dune Sand & PFA, changes of S/a and the comparison of chemical admixture, etc. Approximately $65,000m^3$ of C80A concrete has been poured to the vertical members since 16-Apr-2006. In the actual application, it was showed that C80A has proper early strength achievement, excellent mechanical properties and satisfactory flowability & workability. The results of extensive site testing can be summarized that the average compressive strength at 28days is 98.8MPa, the average elastic modulus at 28days is 47.8GPa, the flow of concrete after pumping at the height of 250m (L72) was over 500mm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11A
• /
• pp.1880-1888
• /
• 2001

In wireless communication systems, transmission errors degrade the reconstructed image quality severely. Among various techniques which reduce the degradation, the error concealment technique yields good performance without overheads and the modification of the encoder. In this paper, we have proposed the technique for recovering the corrupted motion vector using the edge direction of blocks which surround the corrupted block, when the video information is compressed by H.263 standard. We uses the property that each object in video sequences shows the same motion. For the estimation of edge directions, the first AC coefficients of blocks are used. Extensive simulation results show that the proposed technique yields good performance with a reduced computational complexity.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.319-319
• /
• 2010

Dye-sensitized solar cells (DSSCs) based on plastic substrates have attracted much attention mainly due to extensive applications such as ubiquitous powers, as well as the practical reasons such as light weight, flexibility and roll-to-roll process. However, conventional high temperature fabrication technology for glass based DSSCs, cannot be applied to flexible devices because polymer substrates cannot withstand the heat more than $150^{\circ}C$. Therefore, low temperature fabrication process, without using a polymer binder or thermal sintering, was required to fabricate necked $TiO_2$. In this presentation, we proposed polymer-inorganic composite photoelectrode, which can be fabricated at low temperature. The concept of composite electrode takes an advantage of utilizing elastic properties of polymers, such as good impact strength. As an elastic material, poly(methyl methacrylate) (PMMA) is selected because of its optical transparency and good adhesive properties. In this work, a polymer-inorganic composite electrode was constructed on FTO/glass substrate under low temperature sintering condition, from the mixture of PMMA and $TiO_2$ colloidal solution. The effect of PMMA composition on the photovoltaic property was investigated. Then, the enhanced mechanical stability of this composite electrode on ITO/PEN substrate was also demonstrated from bending test.

• Fire Science and Engineering
• /
• v.23 no.6
• /
• pp.24-31
• /
• 2009

The Environment of disaster has more complicated, diversified and unpredicted sides, which causes extensive damage to humankind. Above all, presently the climatic change causes worldwide disaster of nature like cataclysm, intense heat, drought, earthquake and hard winter. After 9.11, most of countries continuously try to protect their own compatriots' life and property which forms the social safety net as well. This research investigates the current system used by the firerenation which is the national disaster response agency.ict also suggests the unation whiih is the nasystem unationdisaster mthe nasys accundihg to tionld el of disaster like the constructe naof DB, disaster cycld repunt, analysis of danger, facilities ih is ation system, disaster media system, location search system, disaster damage collection system.

• Journal of Korean Medical classics
• /
• v.32 no.3
• /
• pp.73-83
• /
• 2019

Objectives : The purpose of this paper is to investigate the mechanism of 'Joy impairs the Heart'. Methods : "Huangdineijing" was searched in relation to 'Joy' and 'Heart', then Joy was divided into physiological and pathological joy. After examination of the similarities and differences between the two, the mechanism of 'Joy impairs the Heart' was drawn out. Results : 1. Excessive Joy not only relaxes Qi(氣), but also disperses Shen(神). 2. Impairment of Heart damages heart locally and Impairment of Yang not only damages Qi or Shen focally, but also damages Yang of the whole body and the degree of damage is thought to be more extensive than "Joy impairs the Heart". 3. "Too much joy and pleasure can cause the Shen(神) to scatter and not remain stored." not only relaxes Qi, but also disperses Shen(神), and the degree of damage is less than "Sudden joy damages Yang". Conclusions : Excessive or Sudden Joy impairs the Heart by disturbing Heart's property of maintaining Taiyang by scattering Shen(神) or not maintaining high Yang density. Forced expression of Joy impairs the Heart by relaxing and stagnating Qi.

• Advances in concrete construction
• /
• v.11 no.3
• /
• pp.193-206
• /
• 2021

Extensive research has been conducted on the basic mechanical property and structural applications of engineered cementitious composites (ECC). Despite the high tensile ductility and high toughness of ECC, transverse steel reinforcement is still necessary to confine ECC for high performance. However, limited research has examined performance of ECC confined with practical amount of transverse reinforcement. This paper presents the results of axial compression tests on 14 square ECC columns and 4 conventional concrete columns (used as control specimens) with transverse reinforcement. The test variables were spacing, configuration (square ties or square and diamond shape ties), and yield strength of stirrups. The test showed that ECC columns confined with steel stirrup had good compressive ductility, and the stirrup spacing had the greatest effect on the compressive performance. The self-confinement effect of ECC results in a more uniform but slower expansion of the whole column compared with CC ones. The test results are then compared against the predictions from a number of existing models for conventional confined concrete. It is indicated that these models fail to predict the axial strains at peak axial stress and the trend of the stress-strain curve of steel stirrups-confined ECC with sufficient accuracy. Several new equations are then proposed for the compressive properties of steel-confined ECC based on test results and potential approaches for future studies are proposed.

• Journal of applied mathematics & informatics
• /
• v.41 no.5
• /
• pp.1037-1046
• /
• 2023

The reason behind to investigate axiom systems with fewer axioms into investigate what types of results still hold, and what results become more general. Seminearrings obtained by the generalisation of nearrings and semirings. Clearly, seminearrings are common abstraction of semirings and nearrings. The aim of this work is to carry out an extensive study on algebraic structure of seminearrings and the major objective is to further enhance the theory of seminearrings in order to study the special structures of seminearrings, this work addresses some special structures of seminearrings such as right duo seminearrings. The right ideal of a seminearring need not be a left ideal. We focused on those seminear-rings which demonstrate this property. A seminearring S is right duo if every right ideal is two sided. Here we have concentrated on the seminearring which are right duo and regular. Main aim of this paper is to deal with properties of regularity in right duo seminearring. We have given some results on right duo seminearring. Followed by that, we have derived some theorems on the relation between the properties of seminearring such as regularity, semi simplicity and intra-regularity in right duo seminearring. We also illustrate this concept with suitable examples.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.40 no.6
• /
• pp.180-189
• /
• 2012

This study was carried out to suggest an experiment based for selecting Sedum, which can adapt well with heat tolerance in extensive green roof system. The heat tolerance of Sedum subject to laboratory high temperature treatment and heat processing time were evaluated using electrolyte leakage, chlorophyll content and regrowth test, and the relation between soil water content and heat tolerance were researched. Logistic model of nonlinear regression analysis was used to evaluate the lethal temperatures that were predicted with the range of $45.0{\sim}48.1^{\circ}C$(soil water content 5%), $47.5{\sim}49.3^{\circ}C$(10%), $48.6{\sim}52.8^{\circ}C$(15%) in 6-hours high-temperature treatment. The higher the soil water content, the stronger the heat resistance property of Sedum. there is. The higher the treatment temperature, the lower the chlorophyll content, and the less the soil water content, the faster the chlorophyll decomposition. The order of hot-temperature resistance was S. reflexum>S. takevimense>S. middendorffianum>S. album>S. sieboldii>S. spurium when soil water content was 5%. The order of hot-temperature resistance was S. album>S. reflexum>S. spurium>S. takevimense>S. middendorffianum>S. sieboldii when soil water content was 15%. The more of soil water content, S. album, S. reflexum, S. spurium had stronger tolerant of hot temperature. These results were consistent with those from the regrowth test and the heat tolerance tested by electrolyte leakage evaluation.

• Journal of the Korean Chemical Society
• /
• v.12 no.2
• /
• pp.65-80
• /
• 1968

The physico-chemical properties of nine selected thallium borosilicate glasses and other 21 supplementary compositions were investigated. Their composition-property curves are found to be in many respects analogous to those of other borosilicate glasses containing lithia, soda, and lead oxide. It is indicated that certain minima found in the composition-property curves of thallium borosilicate glasses might be caused by a change in boron coordination as has been observed to occur in the $Na_2O-B_2O_3-SiO_2$ glasses. Typical effects of thallium ions on the borosilicate glass are summarized as follows: 1) Addition of thallium ions increased density, refractive index, water solubility, linear coefficient of thermal expansion, and dielectric constant. 2) Increased concentration of thallium decreased the softening point of the glasses, caused fluorescence under ultraviolet radiation and smeared out the absorption edges up to $15{\mu}$ in the infrared region. An extensive liquid immiscibility was found by replication electron microscope technique in the $Tl_2O-B_2O_3-SiO_2$ system. The immiscibility covers a composition range roughly from 55 wt. % Tl2O to the binary system $B_2O_3-SiO_2.$ By acid treatment, it was found that the immiscible glass consists of separate silica-rich and boron-rich phases.

• Journal of Acupuncture Research
• /
• v.24 no.5
• /
• pp.105-111
• /
• 2007

Objectives : The electroacupuncture(EA) was often used in Oriental medicine clinic and basic researches. However, there have been neither any national standard of acupuncture needles in Korea nor many studies about the property of acupuncture needles for applying electrical stimulations. Therefore we investigated the electrical corrosion property of acupuncture needles used for EA stimulation in clinic. Methods : We observed the occurrence of electrical corrosion like changes in the surface of acupuncture needles after EA stimulation with various parameters(electrical stimulation intensity, treatment duration, diameter of needle) under a light microscope. We performed EA stimulation on Baekhoe($GV_{20}$) or Joksamli($ST_{36}$) of rats with intensity of 0.025, 0.05, 0.075, 0.1, 0.25 or 0.5mA at a 10Hz frequency. Results : The electrical corrosion-like changes were found on the surface of needles when the EA stimulation was given over 0.05mA of intensity. When electrical stimulation was treated for 10min, the electrical corrosion-like changes were low, but the electrical corrosion-like changes gradually increased by the treatment duration(20, 30min). We also found that acupuncture needles of 0.2mm diameter were produced more extensive electrical corrosion-like changes than acupuncture needles of 0.3 or 0.4mm diameter by electrical stimulation. Conclusions: These results suggested that EA stimulation could produce electrical corrosion-like changes of acupuncture needles through intensity of current, duration of electric stimulation and/or diameter of needle.