• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.4-21
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• 2019

In this paper, 23 Silla gold earrings from the sixth and seventhand centuries, excavated from the Yeongnam region, were analyzed. Based on the silver content of the gold plate, they were classified into three types. The classifications included type I(20-50wt%), type II(10-20wt%) and type III (less than 10wt%). In the analysis process, the composition and morphological differences were identified on the surface of the gold plate. In the case of type I and II earrings, it was observed that the fine holes were concentrated in a relatively higher part of the gold content. The causes of the difference in the surface composition of the gold plate were divided into four categories: 1) surface treatment, 2) thermal diffusivity in the manufacturing process, 3) differences in composition of alluvial gold, and 4) the refining method of gold. It is possible that depletion gilding was attempted to increase the gold content while intentionally removing the other metals from the surface of the gold alloy in the portion where the gold deposit is relatively concentrated on the surface of the gold plating. The highest copper content was detected in the earring with the highest gold content of the analyzed earrings, and it was assumed that thermal diffusion had occurred between the gold plate and the metal rod during the manufacturing process rather than intentional addition. Copper was detected only in the thin ring earring type, and copper was not detected in the thick ring earring type or pendant type. It also proves that this earring has a high degree of tightness at higher temperatures, as there was an invisible edge finish on other earrings and horizontal wrinkles on the gold plate surface. In terms of the material of the gold plate, we examined whether the silver content of the gold plate was natural gold or added by alloy through analyzing the alluvial gold collected in the region. As a result of the analysis, it was found that on average about 13wt% of silver is included. This suggests that type II is natural gold, type III is refined gold, and type I seems to have been alloyed with natural gold. Here, we investigated the refining method introduced in the ancient literature, both at home and abroad, about the possibility of alloying silver after the refining process of type III earrings and then making pure gold. It was found that from ancient refining methods, silver which had been present in the natural gold was removed by reacting and combining with silver chloride or silver sulfide, and long-term efforts and techniques were required to obtain pure gold through this method. Therefore, it was concluded that the possibility of adding a small amount of silver in order to increase strength after making pure gold through a refining process is low.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.348-353
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• 1997

Hydrogenated amorphous carbon(a-C:H) films were deposited on p-type Si(100) by DC saddle-field plasma enhanced CVD to investigate the effect of substrate bias on optical properties and structural changes. They were deposited using pure methane gas at a wide range of substrate bias at room temperature and 90 mtorr. The substrate bias voltage ($V_s$) was employed from $V_s=0 V$ to $V_s=400 V$. The information of optical properties was investigated by photoluminescence and transmitance. Chemical bondings of a-C:H have been explored from FT-IR and Raman spectroscopy. The thickness and relative hydrogen content of the films were measured by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection (ERD) technigue. The growth rate of a-C:H film was decreased with the increase of $V_s$, but the hydrogen content of the film was increased with the increase of $V_s$. The a-C:H films deposited at the lowest $V_s$ contain the smallest amount of hydrogen with most of C-H bonds in the of $CH_2$ configuration, whereas the films produced at higher $V_s$ reveal dominant the $CH_3$ bonding structure. The emission of white photoluminescence from the films were observed even with naked eyes at room temperature and the PL intensity of the film has the maximum value at $V_s$=200 V. With $V_s$ lower than 200 V, the PL intensity of the film increased with V, but for V, higher than 200 V, the PL intensity decreased with the increase of $V_s$. The peak energy of the PL spectra slightly shifted to the higher energy with the increase of $V_s$. The optical bandgap of the film, determined by optical transmittance, was increased from 1.5 eV at $V_s$=0V to 2.3 eV at $V_s$=400 V. But there were no obvious relations between the PL peak and the optical gap which were measured by Tauc process.

• Applied Microscopy
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• v.30 no.1
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• pp.45-59
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• 2000

Cis-platin is a widely used anticancer drug against certain solid tumors such as malignant ovarian tumor, malignant carcinoma of head and neck, bladder cancer and cervical cancer of uterus, and its major mechanism of action is inhibition of DNA synthesis of the tumor cell. To investigate the inhibitory effects of cis-platin on the ciliogensis of the ciliated cells in the mucosa of oviduct, the author pursued the alterations of $\alpha-tubulin$, which is the main constituent of the microtubles in cilia, after cis-platin treatment. To eliminate the possible variations due to ovarian cycle, female Spargue-Dawley rats ($150\sim200gm$ in B.W.) were pretreated with estradiol benzoate (20 mg/kg, once a day, for 4 consecutive days). Animals were administrated with cis-platin (6 mg/kg, i.p.) and sacrificed at 1day, 3days, 5days and 7days after treatment, respectively. Immunohistochemistry for $\alpha-tubulin$ using mouse anti-rat $\alpha-tubulin$ monoclonal antibody as primary antibody was done. Immunogold electronmicroscopy for intracellular distributions of $\alpha-tubulin$ was also performed with same primary antibody and Goat anti- mouse IgM which is preconjugated with gold particles of 15 nm as secondary antibody. The results obtained were as follows; 1. Strong immunoreactivity of $\alpha-tubulin$ was observed in ciliated cells of oviducts at 1, 3 and 5 days after estradiol pretreatment. 2. Weak immunoreactivity of $\alpha-tubulin$ was observed in ciliated cells of oviducts at 1 and 3 days after cis-platin treatment but it was recovered to strong immunoreactivity in 5 days 3. In immunogold electronmicroscopy, density of gold particles for $\alpha-tubulin$ reactions was decreased in apical cytoplasm, but few changes were observed in basal body or cilia at 1 and 3 days after cis-platin treatment. From these above results, it is indicated that synthesis of $\alpha-tubulin$ in ciliated cells of rat oviduct is inhibited by cis-platin treatment.

• Applied Microscopy
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• v.35 no.3
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• pp.121-128
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• 2005

It has been known that ras signaling transduction leads to cell proliferation and migration including various adaptor molecules. Dynamin protein has been implicated in the formation of nascent vesicles in both the endocytic and secretory pathways. Dynamin was classified into three isoforms: dynamin I is only expressed in neuronal tissue, dynamin II is expressed ubiquitously in all tissue but that of dynamin III is confined to testis. We have reported in previous study that Grb2, binding to ras, was associated with dynamin II in NIH3T3 cells. Therefore we have tried to identify the relative expression of dynamin II according to overexpressed ras protein in ras oncogene transfected cells (NIH3T3 (ras)). For the detection of differential expression of dynamin II, we have used immunofluorescent staining and western blot methods in NIH3T3 and NIH3T3 (ras) cells. Next we have described the morphological differences between NIH3T3 and NIH3T3 (ras) cells using SEM and TEM. From these experiments dynamin II was highly expressed in NIH3T3 (ras) cells. NIH3T3 cells was transformed to more spindle shape with many cell process by transfection of ras oncogene. Moreover dynamin II was more concentrated in endocytotic membrane of the NIH3T3 (ras) cells compared to that of NIH3T3 cells. The present results suggested that dynamin II may involve the intermediate messenger in Ras signaling transduction pathway.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.558-567
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• 1989

The synthesis of methanol from carbon dioxide and hydrogen was studied for various compositions of Cu/ZnO catalyst system. Effect of the composition ratio of CuO and ZnO on the catalytic activity in the above reaction and the relationship between the activity and the characteristics of the catalysts were explained from the result of surface area measurements, SEM, XRD, and XPS. The major products of the reaction were methanol and carbon monoxide. The selectivity to methanol increased with increase of the copper oxide content in the catalyst up to CuO: ZnO = 30:70 weight ratio, and decreased rapidly when the content is above 70%. SEM and BET measurements, indicate that this point corresponds to the increasing point of the catalyst crystallite size and the decreasing point of the surface area. As to the Cu/Cu + Zn atomic ratio, the surface concentration of copper measured by XPS decreased remarkably when the copper oxide content in catalyst was higher than 50%. All the unreduced catalysts had almost same binding energy of Cu(2P3) level, but the binding energy for $Cu(2P^3)$ level of reduced catalysts was lowered than that of calcined catalysts. The surface copper species which was in the maximum amount when the CuO:ZnO composition in the catalyst was 30:70, existed as zero valent copper. This result agreed with the experimental result that the highest rate of methanol formation was observed when the CuO content in the catalyst was 30%. It was postulated that these reduced catalysts performed with a relatively strong basicity because the formation rate of acetone was higher than that of propylene in isopropanol decomposition as measured in a pulse type reactor.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.127-136
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• 2015

To evaluate the effects of limestone powder and silica fume on the properties of high-strength high-volume ground granulated blast-furnace slag (GGBFS) blended cement concrete, this study investigated the rheology, strength development, hydration and pozzolanic reaction characteristics, porosity and pore size distribution of high-strength mortars with the water-to-binder ratio of 20, 50 to 80% GGBFS, up to 20% limestone powder, and up to 10% silica fume. According to test results, compared with the Portland cement mixture, the high-volume GGBFS mixture had much higher flow due to the low surface friction of GGBFS particles and higher strength in the early age due to the accelerated cement hydration by increase of free water; however, because of too low water-to-binder ratio and cement content, and lack of calcium hydroxide content, the pozzolanic reactio cannot be activated and the long-term strength development was limited. Limestone powder did not affect the flowability, and also accelerate the early cement hydration. However, because its effect on the acceleration of cement hydration is not greater than that of GGBFS, and it does not have hydraulic reactivity unlikely to GGBFS, compressive strength was reduced proportional to the replacement ratio of limestone powder. Also, silica fume and very fine GGBFS lowered flow and strength by absorbing more free water required for cement hydration. Capillary porosities of GGBFS blended mortars were smaller than that of OPC mortar, but the effect of limestone powder on porosity was not noticeable, and silica fume increased porosity due to low degree of hydration. Nevertheless, it is confirmed that the addition of GGBFS and silica fume increases fine pores.

• Journal of Life Science
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• v.16 no.4
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• pp.612-617
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• 2006

Phosphoinositide-specific phospholipase $C-{\gamma}\;1\; (PLC-{\gamma}\;1)$ has pivotal roles in cellular signaling by producing second messengers, inositol 1,4,5-trisphosphate $(IP_3)$ and diacylglycerol (DG). Tubulin is a main component of microtubules and mitotic spindle fibers, which are composed of ${\alpha}-$ and ${\beta}-tubulin$ heterodimers in all eukaryotic cells. In humans, six ${\beta}-tubulin$ isotypes have been identified which display a distinct pattern of tissue expression. Previously we found that $PLC-{\gamma}\;1$ and one of four ${\beta}-tubulin$ isotypes including ${\beta}1$, ${\beta}2$, ${\beta}3$ and ${\beta}6$, colocalized in COS-7 cells and cotranslocated to the plasma membrane to activate $PLC-{\gamma}\;1$ upon agonist stimulation. In the present study, we demonstrate that the remaining two, tubulin ${\beta}4$ and ${\beta}5$, also showed a potential to activate $PLC-{\gamma}\;1$. The phosphatidylinositol 4,5-bisphosphate $(PIP_2)$ hydrolyzing activity of $PLC-{\gamma}\;1$ was substantially increased in the presence of purified ${\beta}4$ and ${\beta}5$ tubulin in vitro, whereas the activity was not promoted by bovine serum albumin, suggesting that tubulin ${\beta}4$ and ${\beta}5$ also activate $PLC-{\gamma}\;1$. Taken together, our results suggest that all the ${\beta}-tubulin$ isotype activates $PLC-{\gamma}\;1$ activity to regulate cellular signaling.

• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.5-7
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• 1974

1. This study indicates that above the fiber saturation point the drying rate can be increased with increasing the velocity of the air circutation, i.e., the drying rate of sample boards is proportional to the air velocity, but below the fiber saturation point, the effect of the velocity of air circulation is very low as shown in Figs. 1 and 2. 2. Under the controlled temperature and humidity in the kiln, the more the sample boards have moisture, the higher drying rate of it can be obtained. In other words, this means that even though in the case of drying various moisture content of wood, at the final drying stage, approximately the same percentage of moisture content of wood can be secured by employing the higher velocity of air circulation. 3. This study shows that the rate of drying in kiln changes distinctly at the fiber saturation point, i, e., above the fiber saturation point, the drying curve shows concave aginst the X axsis, but below the fiber saturation point, in the range from 30 percent of moisture content to 20 percent of moisture content, the curve shows convex as shown in Fig. 3. As the drying progresses, however, the drying curve shows concave again below 20 percent of moisture content. This means that inflection point of drying curve may be located clearly at the fiber saturation point, i.e., 30 percent of moisture content. As mentioned above, the 30 percent of moisture content of wood at which the inflectional point appears can be recognized as a critical point, i. e., the fiber saturation point at which all free water was removed from wood. The existence of inflectional point indicates that the evaporation of hygroscopic water in a cell wall is more difficult than the evaporation of free water in a cell cavity and the minor space of cell wall. The convex curve in the range of moisture content from 30 percent to 20 percent means that the evaporation of capillary condensed water has a tendency of the same rates of drying approximately, but as approaching to the 20 percent of moisture, the transfusion of moisture from wood becomes difficult because of having less moisture in cell wall. Below 20 percent of moisture content, the drying curve shows concave again, which means that it is difficult to remove the moisture located nearer to the surface of cellulose molecules and the surface bound water. These relations were revealed in Fig. 4. In comparison AC curve which does not have the two inflection points with BD curve which has two inflection points, i.e., Band D, they are mentioned already, by existence of the inflection points, the curve BD shows that the change of drying rate in the interval from 20 percent of moisture content to 30 percent of moisture content is not greater than in the case of the curve AC in the same interval. At the inflection point of 30 percent of moisture content, it can be noticed that the changing of the drying rate is very conspicuous. This phenomenon also can be recognized, as it is noticed by the Fig. 3, the drying rate from green to 30 percent of moisture content is very great. But the inclination of the curve is very slow from 30 percent of moisture content to 20 percent of moisture content, i.e., the inclination of the curve becomes almost horizontal lines. Acknowledgments Gratitude is expressed to Fred E. Dickinson, Professor of 'Wood Technology, School of Natural Resources, University of Michigan, USA for his suggestion to carry out this study.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.648-652
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• 2010

Catalytic activities of the partial oxidation of methane (POM) to hydrogen were investigated over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK in a fixed bed flow reactor (FBFR) under atmosphere, and the catalysts were characterized by BET, XPS, XRD. The BET surface areas, pore volume and pore width of Horvath-Kawaze, micro pore area and volume of t-plot of Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were $284m^2/g$, $0.233cm^3/g$, 3.9 nm, $30m^2/g$, $0.015cm^3/g$ and $396m^2/g$, $0.324cm^3/g$, 3.7nm, $119m^2/g$, $0.055cm^3/g$, repectively. The nitrogen adsorption isotherms were type IV with hysteresis. XPS showed that Si 2p and O 1s core electronlevels of Ti-SPK and Zr-SPK substituted Ti and Zr shifted to slightly lower binding energies than SPK. The oxidation states of Pd on the surface of catalysts were $Pd^0$ and $Pd^{+2}$. XRD patterns showed that crystal structures of fresh catalyst changed amorphous into crystal phase after reaction. The conversion and selectivity of POM to hydrogen over Pd(5)/Ti-SPK and Pd(5)/Zr-SPK were 77, 84% and 78, 72%, respectively, at 973 K, $CH_4/O_2$ = 2, GHSV = $8.4{\times}10^4mL/g_{cat}{\cdot}h$ and were kept constant even after 3 days in stream. These results confirm superior activity, thermal stability, and physicochemical properties of catalyst in POM to hydrogen.

• Applied Microscopy
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• v.30 no.4
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• pp.347-355
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• 2000

Zinc is one of the most abundant oligoelements in the living cell. It appears tightly bound to some metalloproteins and nucleic acids, loosely bound to some metallothioneins or even as free ion. Small amounts of zinc ions (in the nanomolar range) regulate a plentitude of enzymatic proteins, receptors and transcription factors, thus rolls need accurate homeostasis of zinc ions. Zinc is an essential catalytic or structural element of many proteins, and a signaling messenger that is released by neural activity at many central excitatory synapses. Growing evidences suggest that zinc may also be a key mediator and modulator of the neuronal death associated with transient global ischemia and sustained seizures, as well as perhaps other neurological disease stoles. Some neurons have developed mechanisms to accumulate zinc in specific membrane compartment ('vesicular zinc') which can be evidenced using histochemical techniques. Substances giving a bright colour or emitting fluorescence when in contact with divalent metal ions are currently used to detect them inside cells; their use leads to the so called 'direct' methods. The fixation and precipitation of metal ions as insoluble salt precipitates, their maintenance along the histological process and, finally, their demonstration after autometallographic development are essential steps for other methods, the so called 'indirect methods'. This study is a short report on the autometallograhical approaches for zinc detection in the central nervous system (CNS) by means of a modified selenium method.