• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.163-186
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• 2000

We have previously screened 150 medicinal plants on the inhibition of elastase and found a significant inhibitory effects of the extracts of Areca catechu L. on the aging and inflammation against the skin tissues. To isolate and identify the compounds having biological activity, we was further purified by each of the solvent fractions, silica gel column chromatography, preparative TLC and reversed-Phase HPLC. Peak in HPLC, which coincided with the inhibitory activity against elastase, was identified as Phenolic substance using various colorimetric methods, UV, and IR. $IC_{50}$/ values of phenolic substance purified from Areca catechu were 26.9 $\mu\textrm{g}$/$m\ell$ for porcine pancreatic elastase (PPE) and 60.8 $\mu\textrm{g}$/$m\ell$ for human neutrophil elastase (HNE). This Phenolic substance showed more potent activity than those of reference compounds, oleanolic acid (76.5 $\mu\textrm{g}$/$m\ell$ for PPE, 219.2 $\mu\textrm{g}$/$m\ell$ for HNE) and ursolic acid (31.0 $\mu\textrm{g}$/$m\ell$ for PPE, 118.6 $\mu\textrm{g}$/$m\ell$ for HNE). According to the Lineweaver-Burk Plots, the inhibition against both PPE and HNE by this phenolic substance was competitive with substrate. Phenolic substance from Areca catechu exhibited high free radical scavenging effect ($SC_{50}$/ : 6 $\mu\textrm{g}$/$m\ell$) and inhibited effectively hyaluronidase activity ($IC_{50}$/: 210 $\mu\textrm{g}$/$m\ell$). These results suggest that the Phenolic substance Purified from Areca catechu showed anti-aging effect by protecting connective tissue proteins.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.16 no.1
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• pp.1-32
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• 2003

Objectives: This study was carried out to analyze and understand the trends of research papers published In the Journal of Oriental Medical Surgery？phthalmology & Otolaryngology Society(JOMSOOS). Methods: We studied the 308 research papers that had been published in JOMSOOS from 1988 Vol. 1. No. 1. to 2002 Vol. 15. No. 2. Our study was developed through the four stages in order to analyze the papers; 1) we analyzed all the papers overall to classify them into three categories; original article. review article and case report. 2) we classified the original articles in terms of methodology. 3) we also analyzed the case reports according to the sort of disease each paper dealt with. 4) we had another statistical approach to each paper to figure out the distribution of diagnoses in detail. Results: We have got the following outcomes from our analysis of the papers in terms of the four stages. 1. Overall Analysis. 1) Classification of 308 research papers between 1988 and 2002: 137 original articles(44.48$\%$), 111 review articles(36.04$\%$), 56 case reports(18.18$\%$). 2) Used language: Korean(99.03$\%$). English(0.97$\%$). 3) The Number of Authors: 2 persons(42.86$\%$). 3 persons(29.87$\%$), 1 person(14.61$\%$). 2. Original Article Analysis 1) Classification of 137 original articles in terms of methodology: 90 experimental studies(65.69$\%$)46 descriptive studies(33.58$\%$), 1 analytic study(0.73$\%$). 2) Classification of the original articles according to the use of statistical methods: No statistical methods(36.42$\%$), Descriptive methods only(1.99$\%$), Not defined(23.18$\%$), t-test(24.50$\%$), ANOVA(3.97$\%$), Multiple comparison(2.65$\%$), Non-parametric test(2.65$\%$), Other methods(1.32$\%$). 3) Classification of 46 descriptive articles in terms of diseases: otorhinolaryngology(43.48$\%$), dermatology(23.91$\%$), ophthalmology(13.04$\%$), facial palsy(13.04$\%$). 4) Classification of descriptive articles in terms of the number of patients: the highest was 'more than 26 but less than 50 persons'(19 articles - 41.30$\%$). 5) Classification of descriptive articles in terms of the period for patients observation: the highest was the time 'more than 9 but less than 12 months(34.78$\%$)' Out of the 34.78$\%$, the number of articles with the patients observed for more than 12 months was 13(28.26$\%$). 3. Case Report Analysis 1) Classification of 56 case reports in terms of the sort of disease: dermatology(44.64$\%$), ophthalmology(19.64$\%$), otorhinolaryngology(14.29$\%$), facial palsy(8.93$\%$). 2) Classification in terms of the number of patients: 1 person(50$\%$), 3 persons(16.07$\%$), 2 persons(14.29$\%$). 4. Diagnosis Distribution of Each Disease. 1) Studies regarding ophthalmology : the percentage of 'strabismus' cases was the highest(33.33$\%$). 2) Studies regarding otorhinolaryngology : nasal inflammation(34.48$\%$), tinnitus(20.69$\%$). 3) Studies regarding dermatology: the percentage of 'allergic skin disease' was the highest(33.33$\%$). Conclusions: We analyzed the trends of research papers that have been published in JOMSOOS in detail. We came to understand the trends of the research through this study. However, we acknowledge that we only adopted the quantitative method out of various possible analysis methods. For further studies, we strongly urge to adopt the qualitative methods as well.

• Korea journal of population studies
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• v.11 no.1
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• pp.58-75
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• 1988

1.Objectives of the Study It is a well known fact that a prompt and reliable data on demographic information is essential in a proper planning and evaluation of any program of national or community level. Especially vital statistics are an important demographic component among demographic information. Realizing the importance of vital statistics, the government has made some efforts for years to improve the vital registration system which has a close relationship with the production of vital statistics. However, it is still observed that there are some limitations in utilizing vital registration data due to considerable amount of vital events which are never registered and registered but not in time or inaccurately, even though vital registration system in Korea has sound legal basis. In this connection, the objectives of the study is as follows :(1) To examine some problems of the vital registration system in various aspects, (2) To make improvement programme of continuous Demographic Survey as a supplementary source of vital statistics, and (3) To find out some alternatives for making it possible to produce and utilize the reliable vital statistics by developing analytical methodologies on that. 2. Current Situation of Vital Registration System All the vital events, i.e. births, deaths, marriages and divorces, are to be registered in time under the Civil Registration Law, Statistics Law and Regulation on Vital Statstics as a duty of people. Some recent tendencies in each of recent registration are summarized as below: (1) The completeness of vital registration .Out of all births which are occurred during a year, around 75% of those compared to the estimates are registered in the year of occurrence. .In case of death registration, the percentage of registration in the year of occurrene has been gradually increased from 86.2% in the year of 1980, but it is still below the level of 90% compared to the estimates. .The percentage of registration for marriages and divorces in the year of occurrence out of total registered numbers was revealed to be 69% and 73% respectively in 1985. (2) Continuous Demographic Survey .It is a kind of sample survey for the purpose of producing reliable vital statistics which could not be provided by the vital registration. .It covers about 17, 000 sample households at national level and important information for vital events are collected in every month by 323 expertized enumerators who are regular staff of the government. .Although the result of the survey seems to be more reliable than of vital registration, the reliability of the data is still bellow the acceptable level if compared with relevant information from other sources such as population census or special surveys. 3. Problems of Vital Registration System There are four major obstacles in improving vital registration system in Korea; (1) In general, policy priority is not given on any programme of improving vital registration system. It is, therefore, very difficult to formulate comprehensive programme through having cooperation from related authorities and sufficient financial assistance. (2) In all the laws related and system itself, there is substantial degree of overlap and irrationality. Registration of each vital event is maintained according to several laws and regulation such as Civil Registration Law, Statistics Law, Resident Registration Law and Regulation on Vital Statistics. However they are mutually overlapped and overall supervision can not be done systematically due to lack of co-operation among the authorities concerned. (3) The administration of vital registration system seems to be working inefficiently, because of most of civil servants who are in charge of vital registration are lacking of conception on vital statistics and also there is a certain extent of regidity in handling the works. Therefore, they are doing their jobs in a passive way. (4) A substantial proportion of vital events occurred is not registered within the legal time limit (i.e. within one month after the occurrence in case of birth and death) or not registered forever. Some of social customs and superstitution seem to be the potential causes especially in case of births and deaths. 4. Recommendations for the Improvement of Vital Statistics (1) Reporting systems such as civil registration, vital statistics and resident registration should be integrated under the single law. Also, administrative supervision, personnel and budget with regard to the registration system should be under the control of a single ministry. (2) It is necessary to simplify the procedures and methods of reporting vital events, i.e., reducing number of sheets of the form, making corrections easily, reducing registration items, etc. (3) Continuous Demographic Survey as a supplementary source of vital registration should be improved and special ad-hoc surveys should be conducted wth regular interval. (4) In-depth analysis should be done using various sources of data on vital statistics. 5. Concluding Remarks From this study, we can notice that temporary campaign and motivation programs are not sufficient to improve the quality of vital statistics. Strong intentions and continuous efforts of the government are needed for the improvement of the vital registration system. Furthermore, most of the data collected through the registration are not properly analyzed and utilized, partly due to the lack of appreciation among high-level governmental officials of the need for vital statistics. It is, therefore, requested that long-term improvement programs of vital statistics be implemented with policy priority and continuous efforts be given to this purpose as a long-term goal of development in Korea.

• Korea journal of population studies
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• v.35 no.2
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• pp.209-232
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• 2012

The purposes of this study is to calculate the gender-based Life Expectancy and Disability Free Life Expectancy of 65-year-olds in accordance with the regions of 16 in Korea based on the years 2005 and 2010 by using the Sullivan method. We used the Census in 2005, 2010, the Korea National Statistical Office(10% sample). We also reviewed examining the changes in LE and DFLE and understanding the relevance between the DFLE of 65-year-olds of the year 2010 and related factors. As a result of this study, it was shown that the LE of the group of all 65-year-old in Korea increased from 18.15 years in 2005 to 19.75 years in 2010 and DFLE increased from 11.41 years in 2005 to 11.64 years in 2010. Regionally, the highest LE for total of 65-year-olds was found to be the entire Jeju area and DFLE was the highest in the city of Seoul. And the highest LE and the highest DFLE for 65-year-old male were found to be in the city of Seoul. Regarding the regional LE of 65-year-old female, both in 2005 and 2010 Jeju area was seen to be the highest. The results of a correlation analysis showed that the DFLE of 65-year-olds in 2010 was found to be increasing with high LE and high population density and in regions with low average temperatures, low number of beds and low age standardized death rates of malignant neoplasms and circulatory disease.

• The Journal of the Petrological Society of Korea
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• v.15 no.3 s.45
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• pp.154-166
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• 2006

Though there are more than 600 active and non-active dimension stone quarries in Korea, most quarries are small-scaled and non-active. Main dimension stone belt in Korea is distributed in the Wonju-jecheon-Mungyeong-Geochang-Jinan-Nanwon-Geogumdo area with NNE direction, which occupies about 50% of domestic dimension stone quarries. The other dimension stone belts occur in the Gangyeong-Iksan-Gimje area, the Pocheon-Ujeongbu area and the Boryeong area. The dimension stones in Korea have been produced from at least fifteen rock types: granite, diorite, syenite, gabbro, homblendite, basalt andesite, rhyolite, tuff felsite, sandstone, marble, gneiss, schist and slate. However, seven or eight rock types such as granite, diorite and marble are currently produced. The dimension stones are quarried out 87% from plutonic rocks (mainly granite and diorite), 6% from sedimentary rocks (mainly sandstone), and 3% from metamorphic rocks (mainly marble). Main rock types of the dimension stones are variable with respect to their production locality. In the Jeollanam-do area, most dimension stones are produced from diorite. Marble is mainly produced from the Gangwon-do and Chungcheongbuk-do areas. Black sandstone is exclusively quarried out from the Chungcheongnam-do area. Granite is most abundant dimension stone in Korea. Above 50% of the domestic dimension stones are medium-grained to coarse-grained granitic rocks, but fine-grained granite dimension stones have 10% of distribution. The color of the dimension stone varies with rock types. Most granite dimension stones have dominant colors of whitish gray and gray, which are produced from the Wonju, Gapyeong, Iksan, Namwon and Geochang areas. Pink-colored granites are rarely produced from the Mungyeong area.

• Food Science and Preservation
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• v.15 no.5
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• pp.675-681
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• 2008

This study investigatedthe quality of mashed red pepper after application of various freezing and thawing conditions. Two freezing temperatures ($-70^{\circ}C$, $-10^{\circ}C$), two thawing temperatures ($0^{\circ}C$, $40^{\circ}C$), and two thawing methods (water-thawing, air-thawing), were employed. Changes in levels of capsaicinoids, vitamin C, free sugars, organic acids, and capsanthin were measured. Capsaicinoids, vitamin C,and free sugar contents were lowest in pepper treated at $-10^{\circ}C/40^{\circ}C$ (freezing/thawing), and the loss rates were 38.0, 79.4 and 24.6%, respectively. When thawing methods were compared, chemical contents were higher in air-thawed samples than in water-thawed peppers, but there was a statistically significant difference only in vitamin C content. Free sugar content after $-70^{\circ}C$ freezing were higher than after $-10^{\circ}C$ freezing, irrespective of the thawing method used. Initial citric acid, malic acid, and succinic acid contents were 44.90, 30.76 and 20.65 mg/100 g, and there was no significant difference between peppers treated with different freezing and thawing conditions. It is recommended that the best method for preserving the overall quality of mashed red pepper is freezing at $-70^{\circ}C$ and thawing at $0^{\circ}C$ in air.

• Food Science and Preservation
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• v.19 no.6
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• pp.951-956
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• 2012

In this study, the effects of the use of a starter on radish soaked at $4^{\circ}C$ for 28 days using two kinds of domestic sun-dried salt (white and gray salt) were determined. As a result, the moisture contents of the radish soaked with white and gray salt were 7.93 and 4.50%, respectively. The salinity levels were found to be equal (90%). No significant difference was found between the two groups in terms of the mineral contents of the salts therein ($37812.41{\pm}1922.95$ and $39755.13{\pm}1205.70$ mg/100 g, respectively). However, iron and zinc contents of gray salt were higher than those of white salt while the calcium, potassium, and magnesium contents were lower than those of white salt. After the addition of the starter, the sugar content increased, the pH decreased, and the total acidity rapidly decreased compared with the non-starter group during fermentation. The total microorganism count of the two groups increased during the fermentation period of 28 days. From the initial fermentation for 7 days, the lactic acid bacteria in the non-starter group increased while those in the leuconostoc starter group steadily increased within the whole fermentation period. The Leuconostoc spp. in non-starter group increased, but that in the starter group decreased to pH 4.0 on day 14.

• Food Science and Preservation
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• v.25 no.1
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• pp.44-51
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• 2018

The purpose of this study is to present the results as basic data for establishing proper storage conditions and distribution conditions of actual farms at point of increasing concern about hygiene and palatabiltiy of consumers to food. In this study, three farmhouses of dried persimmons prepared using different storage conditions were selected in Sangju (Korea). The dried persimmons were stored for 90 days. Changes in temperature and humidity were measured with a temperature and humidity recorder under each storage condition, and physicochemical analysis and sensory evaluation were performed. The average temperatures of farmhouse A, B and C were approximately $-22--23^{\circ}C$, $-19--18^{\circ}C$ and $-25^{\circ}C$ respectively. The humidities of A, B and C were 62-63%, 59-60%, and 66-67%, respectively, and the moisture contents of all farmhouses increased during the storage period, with farmhouse B showing the most rapid increase. Free sugars increased, except for those from farmhouse C. Persimmons from farmhouse B showed the greatest changes in chewiness and hardness. The values of $a^*$ and $b^*$ were significantly decreased in persimmons from farmhouse B, and the color difference value of farmhouse B was dramatically increased. Sensory evaluation showed that the color preference tended to decrease compared with the initial value. Only farmhouse B showed decreased overall acceptability. Moreover, farmhouse B had the highest storage temperature and lowest humidity. Therefore, our results showed that storage at a low temperature and high humidity was important for manufacturing high-quality dried persimmons.

• Food Science and Preservation
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• v.25 no.1
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• pp.107-116
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• 2018

The aim of this study is to investigate the antioxidant and intracellular anti-inflammatory efficacy of blueberry leaf extracted with hot water (BLW), 70% ethanol (BLE), and 70% acetone (BLA) in RAW 264.7 macrophages. In order to evaluate the anti-inflammatory effect of blueberry leaf extracts, RAW 264.7 macrophages were stimulated with lipopolysaccharide (LPS) to induce the production of inflammation-related factors, which were measure by Western blotting and real-time PCR methods. i-NOS, COX-2 protein, and mRNA expression showed concentration-dependent decrease. The decreases in the mRNA expression levels of interleukin-$1{\beta}$ (IL-$1{\beta}$), interleukin-6 (IL-6), tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), and prostaglandin $E_2$ ($PGE_2$) were concentration-dependent. Further, the antioxidant effects of blueberry leaf on total polyphenol contents, electron donating ability and $ABTS^+$ radical scavenging activity were evaluated. The total polyphenol contents of BLW, BLE, and BLA were $217.04{\pm}2.98$, $156.72{\pm}3.90$, and $182.88{\pm}3.02mg\;TAE/g$, respectively, while the electron donating abilities at $1,000{\mu}g/mL$ of BLW, BLE, and BLA were 81.7, 79.6, and 79.3%, respectively. The $ABTS^+$ radical scavenging activity was fond to be concentration dependent. The nitric oxide (NO) production inhibition activities at $50{\mu}g/mL$ of BLW, BLE, and BLA were 35.1, 42.4 and 42.7%, respectively. In conclusion, the antioxidant and anti-inflammatory test results indicate that blueberry leaf extracts (BLW, BLE, and BLA) can be used as potential anti-inflammatory agents.