• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.4 s.40
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• pp.367-372
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• 1991

In this study, we discussed about the factors effected upon the initial maximum value of heat flux ($q_{max}$). Thermal conductivity, thermal transmittance and surface air cavity of wool fabrics were examind and their correlation to the $q_{max}$ was studied. The factors were examined which had an effect upon the $q_{max}$ of an objective measure of warm/cool feeling. It was simulated by Thermo-Labo apparatures. We selected twenty sorts of pure wool woven fabrics for men's fall -winter cloth (all Wool). The conclusions are as follows; 1. There was not a certain correlation between the $q_{max}$ and the thermal conductivity of wool fabric. 2. When the fabrics touched on the copper plates, the thickness of wool fabric had a negative correlation to the $q_{max}$. The thermal transmittance had a positive correlation. Both of them had a good correlation to the $q_{max}$. 3. As a major factor, the thickness of fabric effected on the $q_{max}$.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.209-221
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• 1988

The ore deposit of the Ohtani mine is one of repesentatives of plutonic tungsten-tin veins related genetically to acidic magmatism of Late Cretaceous in the Inner zone of Southwest Japan. Based on macrostructures of vein filling on the order of ore body, three major mineralization stages, called stage I, stage II, and stage ill from earliest to latest, are distinguished by major tectonic breaks. The alteration zories are characterized by specific mineral associations in pseudomorphs after biotite. The alteration zones can be divided into two parts, i. e. a chlorite zone and a muscovite zone, each repesenting mineralogical and chemical changes produced by the hydrothermal alteration. The chloritic alteration took place at the beginning of mineralization, and muscovite alteration in additions to chloritic alteration took place at stage II and ill. The alteration zones are considered to be formed by either of two alteration mechanism. 1) The zones are formed by reaction of the rock with successive flows of solution of different composition and different stage. 2) The zones are formed contemporaneously as the solution move outward. Reaction between the solution and the wall-rock results in a continuous change in solution chemistry. The migration of the successive replacement of the fresh zone$\rightarrow$the chlorite zone$\rightarrow$the muscovite zone may have transgressed slowly veinward, leaving metasomatic borders between the different zones.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.192-195
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• 2000

Degenerate primevs corresponding to the consensus sequences of the copper-binding regions in the N- and Cterminal domains of fungal laccases were used to isolate laccase gene-specific sequences froin a white rot rungus Ganodern~a lucidrm w-hich has been known to strengthen the imnnne system. A 1.6 Kbp fragment was amplified by PCR and its base sequence was detenuiued. Locating seven iutrous within the base sequence, we could deduce its amino acid sequence. The nucleotide sequence witl~out introlls was 47Y0 identical to that of lee1 gene of Pametes wllosa; lhe identity in amino acid sequences of the two was 7994 The deduced amino acid seqoence was also sunilar to those of Coriolus versicolo~ kc3 (79%); Co~,iolz~s hirsutus phenolouiduse (78%), Trainetes vel.srcoloi. lccl (77%), Trametes ~!i/Iosa Ice2 (77%) and Trametes vemicolor kc4 (66%).

• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.103-114
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• 2021

Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm - 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load - deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.424-435
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• 1991

To develop the photoelastic experiment method for the orthotropic material under pure torsional moment is the main objective of this research. In the development of photoelastic experiment for orthotropic material under pure torsional moment, the important problems and their solutions are the same as following. In the model material for photoelastic experiment, it was found that C.F.E.C.(Copper Fiber Epoxy Composite) can be used as the model material of photoelastic experiment for orthotropic material. In the stress freezing cycle, it was assured that stress freezing cycle for epoxy can be used as the stress freezing cycle of the photoelastic experiment for orthotropic material. In the slicing method, it was found that the negative oblique slicing method can be effectively used as slicing method in 3-dimensional photoelastic experiment. In the measuring method of stress fringe values and physical properties in the high temperature, it was found that stress fringe values can be directly measured by experiment and physical properties can be directly or indirectly by equation between stress fringe values and physical properties developed by author. In the stress analysis method of orthotropic material under pure torsional moment by photoelastic experiment, it will be studied in the second paper.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.62-84
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• 1991

The purpose of this study was to evaluate the cytotoxicity of four root canal sealers(Tubliseal, AH26, Apatite Root Canal Sealer I, Apatite Root Canal Sealer II) in Vitro. The root canal sealers were mixed and filled in molds which were $14{\times}1.25mm$ in diameter, in height to use for cell counting and agar overlary method, and $7{\times}1.25mm$ for millipore filter method and set for 7 days to use for experiment. Silicone and copper plate were used for negative and positive control respectively. Using the culture of L929 fibroblast, total cell number and vital cell number were counted and the ratio of vital cell number to total cell number was calculated on 2 nd, 4 th, 6 th experimental day, and the change of cell membrane permeability was tested by agar overlay method, and the succinate dehydrogenase activity was tested by millipore filter method. The obtained results were as follows. 1. In ail experimental groups, the mitotic activity of fibroblast was reduced when compared with that of negative control group, so ail experimental groups showed cytotoxicity. Apatite Root Canal Sealer I group exhibited mild cytotoxicity, and Tubliseal, AH26, Apatite Root Cenal Sealer II groups exhibited severe cytotoxicity. 2. In the test of the change of cell membrane permeability by agar overlay method, all experimental groups showed cytotoxicity. AH26 group exhibited mild cytotoxicity, and Apatite Root Canal Sealer I group exhibited moderate cytotoxicity, and Tubliseal and Apatite Root Canal Sealer II group exhibited severe cytotoxicity. 3. In the test of SDH activity by millipore filter method, there was no cytotoxicity in Apatite Root Canal Sealer I and Apatite Root Canal Sealer II group, but Tubliseal and AH26 group showed mild cytotoxicity.

• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.560-568
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• 2007

The aim of this study is to investigate the terminology of chemically unclear ‘heavy metals' which were expressed in the Korean secondary science textbook in terms of the definition, the type and the meaning. Initial results showed that six of ‘Chemistry I' textbooks among these texts defined a heavy metal with the density and described it as a metal which is hazardous and continuously accumulated in the human body. Specifically, cadmium, lead and mercury were presented as examples of the hazardous metal in all of the eight textbooks but non-metals such as arsenic and absolutely essential metals including chrome, manganese, iron, cobalt, nickel and copper were also given in the texts. Most of the texts described the hazardousness and toxicity of the metal too simple to understand the mechanism of its intoxication despite considering all of the factors including its oxidation state, residual amount and reactivity with biomolecules of the human body. Such an ambiguous definition and explanation may excluded in the textbook because the chemically undefined chemical vocabulary leads students to cause an alternative conception of the heavy metal, which means that the metal could be identical with toxins.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.10-14
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• 2008

Differently from BSCCO tapes which are fabricated by powder-in-tube method, the coated conductors are made by the evaporation of YBCO on metal substrate. Due to this structural merit, although the coated conductors are generally used for large current transportation, they are expected to be favorable to the purpose of the fault current limitation as well. In this study, using YBCO coated conductor having copper stabilizer formed by plating technique(produced by Superpower Co.), we investigated the over-current characteristics of the coated conductor. The coated conductors had 85 A $I_c$ and 90 K $T_c$. The resistance of the conductor was 0.93 $m{\Omega}/cm$ at 300 K and 0.17 $m{\Omega}/cm$ at the temperature right above $T_c$. To the coated conductors, we applied the voltages of the range from 150 $V_{rms}$ to 230 $V_{rms}$ and measured the V-I curves using four probe method. From the results, we could analyze the electric behavior of the coated conductor in flux flow state. As the current exceed $I_c$, the currents were distributed into the superconductor and metal stabilizer. The amounts of the currents shared through both current paths were calculated under the assumption that the ,Joule heating was perfectly eliminated by $LN_2$ surrounding the conductor. Finally, the condition for the stable current flowing state which does not affect the conductor was established from the analysis on the over-current characteristics.

• Analytical Science and Technology
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• v.19 no.4
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• pp.309-315
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• 2006

Two piperazine-templated metal sulfate complexes, $(C_4N_2H_{12})[Ni(H_2O)_6](SO_4)_2$, I and ($C_4N_2H_{12}$) $[Co(H_2O)_6](SO_4)_2$, II, have been synthesized by hydro/solvothermal reactions and their crystal structures analyzed by single crystal X-ray diffraction methods. Complex I crystallizes in the monoclinic system, $P2_1/n$ space group, a=12.920(3), b=10.616(2), $c=13.303(2){\AA}$, ${\beta}=114.09(1)^{\circ}$, Z=4, $R_1=0.030$ for 3683 reflections; II: monoclinic $P2_1/n$, a=12.906(3), b=10.711(2), $c=13.303(2){\AA}$, ${\beta}=114.10(2)^{\circ}$, Z=4, $R_1=0.032$ for 4010 reflections. The crystal structures of the piperazine-templated metal(II) sulfates demonstrate zero-dimensional compound constituted by diprotonated piperazine cations, metal(II) cations and sulfate anions. The structures of complex I and II are substantially isostructural to that of the previously reported our piperazine-templated copper(II) sulfate complex $(C_4N_2H_{12})[Cu(H_2O)_6](SO_4)_2$. The central metal(II) atoms are coordinated by six water molecules in the octahedral geometry. The crystal structures are stabilized by three-dimensional networks of the $O_{water}-H{\cdots}O_{sulfate}$ and $N_{pip}-H{\cdots}O_{sulfate}$ hydrogen bonds between the water molecules and sulfate anions and protonated piperazine cations. Based on the results of thermal analysis, the thermal decomposition reactions of the complex I was analyzed to have three distinctive stages whereas the complex II proceed through several stages.

• Composites Research
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• v.36 no.5
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• pp.377-382
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• 2023

To enhance the performance of graphene-based devices, it is of great importance to better understand the interfacial interaction of graphene with its underlying substrates. In this study, the adhesion energy of monolayer graphene placed on dielectric substrates was characterized using mode I fracture tests. Large-area monolayer graphene was synthesized on copper foil using chemical vapor deposition (CVD) with methane and hydrogen. The synthesized graphene was placed on target dielectric substrates using polymer-assisted wet transfer technique. The monolayer graphene placed on a substrate was mechanically delaminated from the dielectric substrate by mode I fracture tests using double cantilever beam configuration. The obtained force-displacement curves were analyzed to estimate the adhesion energies, showing 1.13 ± 0.12 J/m² for silicon dioxide and 2.90 ± 0.08 J/m² for silicon nitride. This work provides the quantitative measurement of the interfacial interactions of CVD-grown graphene with dielectric substrates.