• Journal of Life Science
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• v.19 no.9
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• pp.1245-1250
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• 2009

Beimu (Fritillaria thunbergii Miquel), a bulbous plant of Liliaceae found in Korea, Japan and China, has been used as an antitussive and expectorant agent, and is also useful in alleviating stonsillitis and bronchiolitis. Most researches have been focused on micro-propagation and plant regeneration, component analysis, and dormancy relieving of beimu. Reports regarding the biological activity of beimu, such as anti-Helicobacter pyroli or platelet aggregation inhibition activity, are few and not widely available. In this study, methanol extract and its organic solvent fractions were prepared from Fritillaria thunbergii Miquel and their antimicrobial, antithrombin, and antioxidant activities were evaluated, respectively. The methanol extract contained lots of water-soluble materials (58.98%) and hexane-soluble oils (14.85%). The ethylacetate and butanol fraction at $500{\mu}g$/disc concentration showed strong antibacterial activity against tested bacteria, except Escherichia coli. Antifungal activity was not observed in methanol extract and its fractions. The hexane, ethylacetate and butanol fractions showed strong antithrombin activity at 4.8 mg/ml concentration. Especially, the ethylacetate fraction showed 95.4 sec of thrombin time at a concentration of 1.2 mg/ml, which is comparable to aspirin, a widely used antithrombosis agent. For antioxidation activity, the ethylacetate and butanol fraction showed good 1,1-diphenyl-2-picryl hydrazyl scavenging activity ($IC_{50}$ of $344{\sim}368{\mu}g$/ml). In superoxide dismutase-like activity and reducing power, the fractions showed $20{\sim}25%$ of vitamin C, and $51{\sim}54%$ of butyl hydroxytoluene, respectively.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.55-69
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• 2013

The phytosocialogical study on the coastal sand dune vegetation of the East Coast was carried out. 180 phytosociological relev$\acute{e}$s of 62 sites in the East Coast were used in this study. In addition, already published syntaxa and the phytosociological hierarchy in Korea and Japan were used and comparative analyses of syntaxonomy, synecology, syngeography, and syndynamics were performed in the study. In this study, the flora was investigated 30 families, 66 genera, 77 taxa and 3 vegetation types were identified : the coastal drift-line annual communities (Calystegio soldanellae-Salsoletum komarovii), the dune glasslands communities (Elymo-Caricetum kobomugi, Carex kobomugi typical community, Elymus mollis community, Calystegia soldanella community, Zoysia macrostachya community, Cynodon dactylon community, Carex pumila community), and the dune shrubs communities (Linario-Viticetum rotundifoliae, Vitex rotundifolia community, Rosa rugosa community). The aspect of transition in the coastal sand dune vegetation of the East Coast were identified as follows : (1) reduced constancy degree and cover degree of Glehnia littoralis in each community; (2) lack of Ischaemum anthephoroides in Linario-Viticetum rotundifoliae (3) simplified species composition in Vitex rotundifolia community. Unstable habitat condition by external interference seemed to has caused the reduction of 2 taxa, Glehnia littoralis and Ischaemum anthephoroides, that usually grow in the second dune. In addition, we found changes in the distribution of the dune shrub communities influenced by rising temperature of the East Coast as results of the global warming. The results on the distribution of the dune shrub communities in this study demonstrated that the limit of the Rosa rugosa community made $0^{\circ}$ 44'N to the North and the vegetative limit of the Vitex rotundifolia community made $0^{\circ}$ 28'N to the North, respectively compared with the previously phytosociological studies. This study investigated the coastal sand dune vegetation, syntaxonomy, habitat condition and human disturbunce of the East Coast, and this will provide important information as basic data for the coastal ecosystem.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.213-232
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• 2009

This document was prepared to review and summarize the analytical methods for airborne and bulk asbestos. Basic principles, shortcomings and advantages for asbestos analytical instruments using phase contrast microscopy(PCM), polarized light microscopy(PLM), X-ray diffractometer (XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM) were reviewed. Both PCM and PLM are principal instrument for airborne and bulk asbestos analysis, respectively. If needed, analytical electron microscopy is employed to confirm asbestos identification. PCM is used originally for workplace airborne asbestos fiber and its application has been expanded to measure airborne fiber. Shortcoming of PCM is that it cannot differentiate true asbestos from non asbestos fiber form and its low resolution limit ($0.2{\sim}0.25{\mu}m$). The measurement of airborne asbestos fiber can be performed by EPA's Asbestos Hazard Emergency Response Act (AHERA) method, World Health Organization (WHO) method, International Standard Organization (ISO) 10312 method, Japan's Environmental Asbestos Monitoring method, and Standard method of Indoor Air Quality of Korea. The measurement of airborne asbestos fiber in workplace can be performed by National Institute for Occupational Safety and Health (NIOSH) 7400 method, NIOSH 7402 method, Occupational Safety and Health Administration (OSHA) ID-160 method, UK's Health and Safety Executive(HSE) Methods for the determination of hazardous substances (MDHS) 39/4 method and Korea Occupational Safety and Health Agency (KOSHA) CODE-A-1-2004 method of Korea. To analyze the bulk asbestos, stereo microscope (SM) and PLM is required by EPA -600/R-93/116 method. Most bulk asbestos can be identified by SM and PLM but one limitation of PLM is that it can not see very thin fiber (i.e., < $0.25{\mu}m$). Bulk asbestos analytical methods, including EPA-600/M4-82-020, EPA-600/R-93/116, OSHA ID-191, Laboratory approval program of New York were reviewed. Also, analytical methods for asbestos in soil, dust, water were briefly discussed. Analytical electron microscope, a transmission electron microscope equipped with selected area electron diffraction (SAED) and energy dispersive X-ray analyser(EDXA), has been known to be better to identify asbestiform than scanning electron microscope(SEM). Though there is no standard SEM procedures, SEM is known to be more suitable to analyze long, thin fiber and more cost-effective. Field emission scanning electron microscope (FE-SEM) imaging protocol was developed to identify asbestos fiber. Although many asbestos analytical methods are available, there is no method that can be applied to all type of samples. In order to detect asbestos with confidence, all advantages and disadvantages of each instrument and method for given sample should be considered.

• KDI Journal of Economic Policy
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• v.13 no.4
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• pp.59-90
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• 1991

The purpose of this paper is to determine whether the rate schedule of the Korean income tax system embodies the theoretically desirable distribution of the tax burden by income classes. The paper follows the approach of Young (1990) who has estimated the utility function and calculated the magnitude of sacrifice, i.e., the tax burden. The main point of the study is to estimate the utility function. The estimation results may differ if different data sets are used. Therefore, this paper employs the effective as well as the nominal tax rate schedule. The findings derived in this paper are 1) that the effective rate schedule is more appropriate in estimating the utility function; 2) that the middle class has born the relatively heavier burden over time; 3) that the current income tax credit scheme curtails the tax burden on the middle class while intensifying the tax burden of the lower and upper income classes; 4) that reducing the amount of deduction moves the distribution of tax burdens by income classes closer to the theoretically desirable model; 5) that the rate schedule of the Korean income tax system, particularly in 1991, did not conform to the desired model as did the tax systems of developed countries such as the United States, Italy, Japan, and Germany.

• Journal of Environmental Science International
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• v.18 no.10
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• pp.1089-1101
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• 2009

In this paper, changes in the intensity (e.g., central pressure and maximum sustained wind speed) of Tropical Cyclone (TC) in summer in the regions located at $30^{\circ}N$ in East Asia from 1988 to 1991 were found. The intensity of TC from 1991 to 2007 was much higher than that of TC from 1965 to 1988. The reason for this was that the frequency of TCs passing China from 1991 to 2007 was much lower than that of TCs from 1965-1988 because a northeasterly wind caused by high-pressure circulation in East Asia got severer along the East Asian coast. Instead, TCs moved from the eastern region of the Tropical West Pacific to Korea and Japan mainly after passing the East China Sea due to the low-pressure circulation strengthened in the subtropical waters of East Asia. In addition, low Vertical Wind Shear (VWS) was created along the mid-latitude regions of East Asia and the main path of TCs from 1991 to 2007. Most of the regions in the Northwestern Pacific showed higher Sea Surface Temperature (SST) from 1991 to 2007, and had a good environment where TCs were able to maintain a higher intensity on the mid-latitude. In particular, a low sensible heat flux occurred due to high snow depth in East Asia in the spring of 1991 to 2007. Accordingly, the lower layer of East Asia showed high-pressure circulation, and the sea surrounding East Asia showed low-pressure circulation. Thus, the typical west-high, east-low pattern of winter atmospheric pressure was shown. The possibility of snowfall in East Asia in spring to be used as a factor for predicting the summer intensity of TC in the mid-latitude regions of East Asia was insinuated. The characteristics of TC in a low-latitude region were the same in Korea. The latest intensity of TCs got higher, and the landing location of TCs gradually changed from the west coast to the south coast.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.159-167
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• 2013

The aim of this study was to evaluate changes in demineralization resistance and bonding strength of light cured glass ionomer after the addition of nano hydroxyapatite in various ratios. Fuji II LC GIC (GC Co., Japan) was used as the control group and also as a base material for experimental group. HA was mixed into the RMGIC at various ratio to create a HA-LC GIC mixture, preparing six experimental groups, i.e. 5%, 10%, 15%, 20%, 25%, 30% HA-LC GIC. According to the results, the bonding strength increased due to the addition of HA, showing the maximum value at the 15% nano HA group (p < 0.05). Under CLSM observation after 4 days of demineralization, the HA groups were more resistant to demineralization compared to the control group. No significant difference was observed between HA groups. In analysis through SEM, the HA groups showed attachment of granular materials and decreased demineralized tooth surfaces under influence of HA particles.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.3-13
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• 2008

The year 2007 marked two important anniversaries for space. The Soviet Union launched Sputnik 50 years ago on October 4. 1957. The 40th anniversary of the United Nations treaty on outer space was also marked in 2007. 2008 and 2007 were full of dramatic events of space activity as well : Success of Japan's first large lunar explorer 'KAGUYA'(SELENE) and China's 'Chang'e 1', launch of ISS laboratory module, 'Colombus' and 'Kibo', test of China's ASAT, and success of Korea's first astronaut program and so on. International government space budgets reached $78.3 billion in 2007, a strong growth rate of 36% over 2006, and the recently released Global Exploration Strategy, The Framework for Coordination is a set of guidelines for international cooperation among 14 of the world's space agencies. Worldwide space industry revenue grew by 20% over 2005, $106.1 billion in 2006 and $173.9 billion expected in 2007. This paper discusses the issues related to the Earth observation R&D trend and market in detail. Korea's 2008 government space spending is \316.4 billion, 2007 space industry revenue was $106 million. Several research projects are now underway and STSAT 2 will be launched by KSLV-1 at the Naro Space Center within this year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.4
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• pp.195-203
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• 1974

The individual production rate of Plecoglossus altivelis was studied from the 18th of June to the 25th of September (99 days) 1973, when the fish grow best at Gangjeong Stream, Jeju Do, as one of the ways to find out the reasons why the size of P. altivelis of Jeju Island is smaller than that of other places. The results obtained are as follows : 1) The indivudual production rate of the fish in the Gangjeong Stream during the summer 1973, was estimated as shown in Table 6. 2) The individual production rate of the fish and standing crop of algae on stones in the Gang-jeon Stream were no more than $7.2\%$ and $6.2\%$ respectively, when compared with those of the Ukawa River (which is located in Japan), thus the individual production rate of the fish at Gang-jeong Stream being very poor. 3) Population density was 5.2 individuals average per square meter during the research period. This is beyond the estimated density limit, i. e., 4.8 individuals per square meter, for the standing crop of algae on stones. 4) The period that the individual production rate of the fish was the most brisk during the summer in this stream was from August to September in 1973. 5) The poor individual production rate is primarily regarded due to insufficient gross ingestion. The reasons seemed to be insufficeient productivity of algae on the bottom stones, over-population density of the fish, and the lowered activity of ingestion due to low water temperature in daytime as compared with other places. Thus, the production rate of Plecoglossus altivelis in the Gangjeong Stream during the summer was greatly influenced by these factors.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.466-477
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• 2005

Statement of problem : Problem of matching the appearance of porcelain restorations with the patient's natural dentition has always been a concern to dental clinicians. Recently, demands for esthetics, even in restorations requiring strength, has brought a revolution to dentistry and increased use of zirconia. Among the various factors, shade and translucency or the core can significantly affect the overall esthetics of the restoration and should be considered when selecting an all-ceramic system. Purpose : The purpose of this study was to spectrophotometrically evaluate the influence of different zirconia systems and core thickness on the final shade of all-ceramic restorations using the CIEL$^*a^*b^*$ system. Material and Methods: Core specimens (n : 20 per group) of In-Ceram Alumina, In-Ceram Zirconia, Digident CAD/CAM Zirconia, Cercon Zirconia were fabricated 20mm in diameter. 10 specimens of each group were fabricated at core thickness of 0.5mm and 0.7mm. These core specimens were veneered with shade Al & A3 porcelain of the recommended manufacturer. CIEL$^*a^*b^*$ coordinates were recorded for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). Color differences were calculated using the equation ${\Delta}E^*=[({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2]^{\frac{1}{2}}$. Results : 1. Specimens of core thickness 0.5mm and 0.7mm did not exhibit clinically perceived color difference. 2. Regarding shade reproducibility, In-Ceram Alumina and In-Ceram Zirconia showed significant difference within each group. 3. Cercon Zirconia group showed the highest $L^*$ value and Digident Zirconia group showed lowest $a^*$ & $b^*$ value. 4. Generally the shade difference between materials was higher in the A3 shade group than in the Al shade group. Conclusion: Within the limitations of this study, there was no color difference after increase in core thickness and every all-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• Korean Journal of Poultry Science
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• v.31 no.2
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• pp.119-128
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• 2004

Highly Pathogenic Avian Influenza (HPAI) is a very acute systemic disease in poultry, particularly in chickens and turkeys caused by HPAI viruses. An outbreak of HPAI caused by subtype H5N1, was first reported in a broiler breeder farm on December 10, 2003 in Korea, although there had been twenty one outbreaks of the disease reported in the world before. Since mid-December 2003, eight Asian countries have confirmed outbreaks of HPAI due to the same subtype. The outbreak has also resulted in at least twenty three fatal human cases in Vietnam and Thailand as of May 17, 2004 according to the WHO. Regarding the first outbreak of recent Asian HPAI, it has been suspected that some Asian countries with the exception of Korea and Japan veiled the fact of HPAI outbreaks since the last half of 2003, even though it was first reported in Korea. There have been total nineteen outbreaks of HPAI among chicken and duck farms in 10 provinces in Korea since Dec. 2003 and approximately 5,280,000 birds were slaughtered from 392 farms for eradication of the disease and preemptive culling. The origin of the H5Nl HPAI virus introduced into the country are unknown and still under epidemiological investigation. Current status of outbreaks and characteristics of HPAI will be reviewed and discussed on the basis of genetic, virological, clinicopathological, and ecological aspect, as well as future measures for surveillance and prevention of the disease in Korea.