• Economic and Environmental Geology
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• v.31 no.5
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• pp.447-458
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• 1998

The spinel Ihelzolite of ultramafic xenoliths are found in the alkali basalt from eastern part of the Cheju island, Korea. The xenolith is are mainly composed of olivine, orthopyroxene, clinopyroxene and spinel. Based on the chemical compositions of the constituent minerals, the ultramafic xenolith belong to upper mantle peridotite. Each minerals have a protogranular texture. Olivine with kink band texture partly shows undulatory extinction. Some clinopyroxenes have spongy textured rims. Brown spinels occur in the interstices between olivine and pyroxene grains. Olivine is mostly forsterite $(Fo_{89-90})$. Orthopyroxene is enstatite $(Wo_{1.3}En_{88.4}Fs_{10.3})$ with 3.87~5.25 wt% $Al_{2}O_{3}$. Clinopyroxene is diopside $(Wo_{48.0}En_{46.2}Fs_{5.8})$ with 6.75~5.03 wt% $Al_{2}O_{3}$. Spinel has the Mg value of 75.9 and its Cr-number is 10.2. According to the PoT estimations for the mantle xenoliths, equilibrium temperatures of the xenoliths range from 1023 to $1038^{\circ}C$ and pressure is 18 kbar. Spinellhelzolite from this area, which is characterized by lower Cr-number (10.2) and homogeneous chemical compositions, supports that these ultramafic xenoliths are derived from the upper mantle.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.269-277
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• 1999

In this paper, a novel dead time minimization algorithm is proposed for improving the output waveform of an inverter. The adverse effects of the dead time are mainly described by the voltage drop and the distortion factor of waveforms. The principle of the proposed algorithm is organized with forbidding unnecessary firings fo the inverter switches which are not conducted even though the gate signal is impressed. The proposed methods are explained with the conduction mode of output currents. The H/W and S/W implementation method of the proposed algorithm are also presented. The validity of the proposed algorithm is verified by comparing the simulation and experimental results with conventional methods. It can be concluded from the results that the proposed algorithm has the advantage which is able to reduce the harmonics in the output voltages and which the output voltage can nearly be equal to the reference value. Another advantage of the proposed method is the reduction of total numbers of switching so that the switching losses of inverter drives can be minimized.

• Journal of Plant Biology
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• v.38 no.4
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• pp.329-336
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• 1995

Raphanus sativus L. var. hortensis f. raphanistroides (wild radish: Brassicaceae), a herbaceous perennial, occurs only on beaches in East Asia. Genetic diversity and population structure of seven Korean populations were investigated using starch gel electrophoresis. Although the Korean populatins are small, isolated with patchy distribution, the population maintain a moderate level of genetic diversity; the mean percentage fo polymorphic loci was 51.4%, mean number of alleles per locus was 1.84, and mean expected heterozygosity was 0.116. A combination of animal-outcrossing breeding system, wide geographical distribution, restricted ecological distribution, and a propensity for high fecundity may in part be explanatory factors contributing the moderate level of genetic diversity within populations. An overall excess of homozygotes relative to Hardy-Weinberg expetations (mean FISa=0.116) indicates that consanguineous mating occur within wild radish populations, leading to a family structure within a circumscribed area. Although population of wild radish experience a limited gene flow, only 5% of the total genetic variation found in Korean wild radish populations examined is due to differences among populations (mean GST=0.052). This value is considerably lower than the mean values of species with similar life history and ecological characteristics. However, significant differences were found in allele frequencies between populations for all polymorphic loci (P<0.01). It is supposed that directional selection toward genetic uniformity (similar gene frequencies) in a relatively homogenous habitat is thought to be operated among Korean wild radish populations.

• The Korean Journal of Ecology
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• v.12 no.4
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• pp.285-295
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• 1989

This report is results of an investigation on the secondary succession and species diversity of the burned area. Fifty hectares of pine forest was burned by the crown fire of the spring (April 6) 1986. The results obtained from spring 1989 were summarized as follows: In the burned area , site and unburned area (U), the vascular plant fo 69 kinds, 49 kinds and 24 kinds were lsted respectively. The life form spectrum of burned area was H---e type, which is common type in most burned area and that unburned area, H---e type. The species diversity (H)and evenness index (e) of burned area (, site) were H=2.51, 1.65 and e=0.59, 0.44 and those of unburned area (U) were H=1.28 and e=0.40. The similarity index was the value of 0.594 in - and 0.236 in -U site. The similarity between and site was greater than between site and U site, and that between and U-site, The dominance index (c) of , and U-site was 0.16, 0.39 and 0.42 respectively. The succession degree (DS) of , and U-site was 244.0, 227.6 and 854.4 respectively. Soil pH, available phosphorous, and exchangeable potassium in the burned area were higher than those in the unburned area, and total nitrogen, organic carbon, and C/N ratio in the burned area were higher than those in the unburned area, and organic matter in the burned area was higher than that in the unburned area.

• Transactions on Electrical and Electronic Materials
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• v.1 no.2
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• pp.28-31
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• 2000

BaTiO$_3$cerameic thin films doped with Mn were manufactured by rf/dc magnetron sputter technique. We have investigated crystal structure, surface morphology and PRCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat-treatment temperature. Second heat treatment of the specimen were performed in the temperature range of 400 to 1350$\^{C}$ X-ray diffraction patterns of BaTiO$_3$ thin films show that the specimen heat treated below 600$\^{C}$ is an amorphous phase and the one heat treated above 1100$\^{C}$ forms a poly-crystallization . In this specimen heat-treated at 1300$\^{C}$, a lattice constant ratio(c/a) was 1.188. Scanning electron microscope(SEM) image of BaTiO$_3$ thin films of the specimen heat treated in between 900 and 1100$\^{C}$ shows a grain growth. At 1100$\^{C}$, the specimen stops grain-growing and becomes a poly-crystallization . A resistivity-temperature characteristics of the specimen depends on the doping concentrations of Mn. A resistivity ratio between the value at room temperature and the one above Curie temperature was 10$^4$ for pure BaTiO$_3$ thin films and 10$\^$5/ fo BaTiO$_3$ : additive 0.127mol% MnO

• Journal of the Korean Home Economics Association
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• v.31 no.1
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• pp.13-24
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• 1993

The reformed family law was enforced from Jan.1,1991 and the claim to division of matrimonial property in case of divorce, a newly enacted right in the law, is expected to increase the economic position of married women. By this system, married woman can claim her share in the matrimonial property in case of divorce if she verifies her contribution to it. But actually, household work of housewives has not been evaluated properly as compared with their husbands' work in deciding of property division rate, because there is no economic base about the value of household work. So, this study verified wives' role of contribution to matrimonial property and compared their work hours with their husbands. As the result, following suggestions can be presented. 1. The contribution rates of husband and wife to the matrimonial property have to be acknowledged equally and, in case of employed wife, her rate has to be evaluated higher than her husband. 2. Because the property division is not a solatium but a transfer of wife's share, responsibility which marriage has dissolved should not be taken more to women than men. 3. Decision of division rate has to be made regardless the amount fo property unless there are special reasons. 4. The donation tax and inheritance tax should not be imposed on matrimonoal property which was returned to wife from her husband.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.897-902
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• 1998

This study was conducted to develop the standard recipe of Dopyun according to the various content of mung bean starch and sugar. The effects of mung bean starch(10%, 15%, 20%) and sugar(20%, 30%) were evaluated on textural and sensory properties of Dopyun through the mechanical properties using texture analizer and sensory evaluation. Color was tested by color and color difference meter. For sensory evaluation, higher content of sugar and lower content of mung been starch(sugar 30%, mungbean starch 10%) showed advantages in acceptance fo taste and overall quality. Mechanical properties of hardness, cohesiveness and chewiness of Dopyun were increased significantly in Dopyun with higher content of mung bean starch and sugar. The values of Hunter color system indicated that "L" and "b" values tended to decrease and "a" value increase, as the mung bean starch and sugar proportion increased. In the analysis of correlation between sensory evaluation and acceptance test, it was found that they were highly related. In view of the above results, it came to the conclusion that Dopyun with the addition of 30% sugar and 10% mung bean starch could give the best result among the groups studied.sult among the groups studied.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.2
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• pp.198-203
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• 2000

A highly viscous biopolymer from Bacillus coagulans CE-74 was purified and its rheological properties were studied The rheological properties of biopolymers produced by Bacillus coagulans CE-74 were studied at the temperature ranges with 20~8$0^{\circ}C$, at the concentration of 0.5~4.0%, at the pH ranges from 3 to 1 and at the shear rate fo 7.34~73.38 sec-1. The apparent viscosity of biopolymer was decreased with increasing shear rate, and thereby biopolymer showed pseudoplastic characteristics. Biopolymer solution showed a characteristic of non-Newtonian fluid properties. At the concentration of 1%, the consistency index and the flow behavior index were shown at 2.64 poise. sec11 and 0.8571, respectively. All dispersions were pseudoplastic fluids described accurately by Herschel-Bulkley model. The change of the biopolymer viscosity on pH showed the highest value at the pH 7.0 and it showed lower at acidic conditon that at alkaline condition comparatively.

• Environmental Analysis Health and Toxicology
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• v.4 no.3_4
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• pp.7-14
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• 1989

Amygdalin has been used for a long time as an anticancer agent. But because of its toxicity, it is difficult to administer continuously for treatment of cancer. This paper was attempted to reduce the side effect and toxicity of amygdalin. That is, effects of cysteine and streptomycin on the toxicity of amygdalin were investigated in rats orally administered amygdalin. 1. The group administered only amygdalin 400 mg/kg was effected on the lung and body weight, hematocrit, hemoglobin, clotting time, SGOT and albumin value. That is, lung and body weight, hematocrit hemoglobin and albumin value were significantly decreased. SGOT and clotting time were significantly increased compared with those of normal group. 2. Weight of lung was significantly increased in the C group (administred amygdalin 400 mg/kg and cysteine 300 mg/kg), D group (amygdalin 400 mg/kg and streptomycin 10 mg/kg), E group (amygdalin 400 mg/kg, streptomycin 10 mg/kg and cysteine 200 mg/kg)and F group (amygdalin 400 mg/kg, streptomycin 10 mg/kg and cysteine 300 mg/kg). 3. Values of hematocrit and hemoglobin were significantly increased, and clotting time was significantly decreased, in the I group and F group compared with those of A group. 4. SGOT was significantly decreased in the C group, E group and F group compared with that of A group. 5. The blood cyanide concentration was significantly decreased in the E group and F group compared with that fo A group. 6. In short, coadministration of cysteine and streptomycin are considered to reduce the toxicity of amygdalin in rats orally administered.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.1-17
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• 2004

It is improtant that performing prophylaxis procedure on an infected implant surface in order to treat peri-implantitis should not change the surface roughness and composition, so that the surface can be recovered to almost same condition as initial implant surface. This thesis, therefore, studied an effect of various oral hygiene instrument on implant surface. A surface roughness measurement instrument and an infection electron microscope were used to observe a change on surface. The purpose of this study was to obtain a clinical guidelines during implant care and peri-implantitis treatment. The result were as follows 1. Ra values (surface roughness value) at experimental group 1, group 2, and group 5 were increased significantly as compared with comparison group(p<0.05). 2. When compared experimental group 1 with each experimental groups at which prohylaxis procedure was performed, mean values of Ra at experimental group 2, group 3, group 6, and group 7 were decreased significantly(p<0.05). 3. Mean value of Ra was lowest at experimental group 2, and highest at experimental group 2, and highest at experimental group 5. 4. Analysis of SEM showed that was significant surface change at experimental group 2, group 3, group 4, group 5, and group 6 as compared with comparison group(X1000). 5. Analysis fo EDX showed that a quantity of Ti on surface for experimental group 6 was very similar to that for comparison group. In conclusion, air-powder abrasive and citric acid, plastic instrument are safe methods to use for performing prophylaxis procedure on implant care or for cleaning and sterilization process on treatment of peri-implantitis, based on the result that those method did not affect implant surface roughness and Ti composition.