• 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.

• Korean Journal of Plant Resources
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• v.20 no.5
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• pp.389-397
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• 2007

Using the active-increment of Tos17 copies in the genome of Oryza sativa L., there were many studies about induction and selection of new mutants. This study mainly focuses on the induction for retrotransposon(Tos17) activity in the callus of Ilpumbyeo(Oryza sativa L.) according to varied culture period and condition. The objectives of this study are obtaining various mutants($M_1$) through plant regeneration, identification of the mutation relation with Tos17, and subsequent phenotyping of the mutants($M_2,\;M_3$). A total of 371 $M_1$ mutants was obtained. The degree of Tos17 activity obtained regeneration plants with each different culture period was evaluated by Southern blot analysis. The result showed that control Ilpumbyeo rice has 5 numbers of copies and the band numbers obtained 7, 8, 9.5, 12, 6, 13.5, 17.5 from culture period of 1, 2, 3, 5, 6, 7, 8 month, respectively. In this study, the result showed that most effectual culture period for activity of Tos17 in Ilpumbyeo rice is 5 month. Hereafter, collections and analysis of various recombination plants will act on an important factor in multiplication and preservation of $M_2$ and $M_3$ generation. And an urgent and important subject is a development of screening method for selection of diverse mutants.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.435-441
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• 2007

Ground-based optical sensing over the crop canopy provides information on the mass of plant body which reflects the light, as well as crop nitrogen content which is closely related to the greenness of plant leaves. This method has the merits of being non-destructive real-time based, and thus can be conveniently used for decision making on application of nitrogen fertilizers for crops standing in fields. In the present study relationships among leaf nitrogen content of rice canopy, crop growth status, and Normalized Difference Vegetation Index (NDVI) values were investigated. We measured Green normalized difference vegetation index($gNDVI=({\rho}0.80{\mu}m-{\rho}0.55{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.55{\mu}m)$) and NDVI($({\rho}0.80{\mu}m-{\rho}0.68{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.68{\mu}m)$) were measured by using two different active sensors (Greenseeker, NTech Inc. USA). The study was conducted in the years 2005-06 during the rice growing season at the experimental plots of National Institute of Agricultural Science and Technology located at Suwon, Korea. The experiments carried out with randomized complete block design with the application of four levels of nitrogen fertilizers (0, 70, 100, 130kg N/ha) and same amount of phosphorous and potassium content of the fertilizers. gNDVI and rNDVI increased as growth advanced and reached to maximum values at around early August, G(NDVI) were a decrease in values of observed with the crop maturation. gNDVI values and leaf nitrogen content were highly correlated at early July in 2005 and 2006. On the basis of this finding we attempted to estimate the leaf N contents using gNDVI data obtained in 2005 and 2006. The determination coefficients of the linear model by gNDVI in the years 2005 and 2006 were 0.88 and 0.94, respectively. The measured and estimated leaf N contents using gNDVI values showed good agreement ($R^2=0.86^{***}$). Results from this study show that gNDVI values represent a significant positive correlation with leaf N contents and can be used to estimate leaf N before the panicle formation stage. gNDVI appeared to be a very effective parameter to estimate leaf N content the rice canopy.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.192-211
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• 2021

In Seongju, Gyengsangbuk-do, the Placenta Chamber (胎室, Taesil) of 18 sons and a son of the crown prince of King Sejong(世宗大王) is located in one place. Taesil refers to the place where the umbilical cord and placenta, which are separated when the baby is born, are placed in a jar made of pottery and stone box and then buried on the ground. The placenta chamber in Seongju has the Buncheong ware (粉靑沙器) cover buried on the ground to protect the baby's placenta. These covers are all hemispherical, with a diameter of more the 20cm. The decorations were made using black and white inlaid techniques only on the outside. The Buncheong ware cover with this shape and pattern has been confirmed only in the placenta chamber in Seongju. This study targets 6 of the Buncheong ware cover whose owners were identified, when and where they were prepared, what the stylistic features and meanings are, and where it was produced. The results of the study are as follows. First, ss a result of reviewing the production background and procurement system of this bowl, it was inferred that it was sourced from Jangheunggo (長興庫) at the central government office, between 1436 and 1439, when the event to bury the placenta of royal members in the ground was the most active. Second, it analyzed the unique features of this cover, such as the shape, pattern, and baked traces. The shape and pattern were compared to the ritual objects contained in the Sejong Silok Oryeui (『世宗實錄』 「五禮」, Five Rites of King Sejong Chronicle) and the lid of the royal placenta jar made in the 15th and 16th centuries. Third, this study suggests that the baking method was based on the shape and location of the traces remaining outside the cover. Finally, the following data were used to estimate the production site: the relationship with the 'Jagiso (磁器所, ceramic workshop) registered in the Sejong Silok Jiriji (『世宗實錄』 「地理志」, Geographical Appendix of King Sejong Chronicle); various records of contribution and dedication about the Buncheong ware made here; and the Buncheong ware and related tools excavated from the kiln site in the area. The place where the Buncheong ware cover was produced is estimated to be the most likely production site for the kiln site in Chunghyo-dong Kiln Site, located in Jeolla-do province by synthesizing the data above.

• Journal of vocational education research
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• v.37 no.5
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• pp.25-53
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• 2018

The purpose of this study is to find out the improvement plan through the satisfaction survey of the trainees involved in vocational training fraud preventive education. In order to do this, we conducted a satisfaction survey(4,263 persons) of 5,939 people who participated in the prevention education conducted by group education or e-learning in 2017. Finally we collected 4,237 effective responses data. Descriptive statistics and the regression analysis were conducted. The finding of the study were as follows. First, the education service quality(4.42), satisfaction level(4.44), understanding level(4.44) and help level(4.45) were significantly higher than those of participants in the preventive education 4 and above. Second, e-learning participants' perceived level of education service quality, satisfaction, comprehension, and help was higher in all variables than collective education's. Third, all of the sub-factors of preventive education service quality influenced satisfaction, understanding, and help in collective education and e-learning, respectively. In the collective education, the contents of education had the greatest influence, and in e-learning, the data composition had the greatest influence. Fourth, desirable education contents were cases of fraud training(70.7%), disposition regulations(47.9%), NCS course operation instructions(32.8%) and training management best practices(32.4%). Additional requirements also included the establishment of an in-depth course, the provision of anti-fraud education content for trainees, and screen switching and system stability that can be focused on e-learning. Therefore, this study suggests that first, it is necessary to activate e-learning for prevention education more, reflecting satisfaction of e-learning is higher than that of collective education. Second, it is necessary to diversify the content of preventive education and to provide it more abundantly, because it has the biggest influence in common with the satisfaction, understanding and help level of the preventive education. Third, education content next, the factors that have a relatively big influence on satisfaction are shown as delivery method and education place in the collective education. Therefore, it is necessary to prepare education place considering the assignment of instructor and convenience. Fourth, constructing data next, the factor that have a relatively great influence on understanding and help are found to be operator support, and more active operator support activities are required in e-learning. Fifth, it is required to delivery prevention activity for trainees participating in vocational training. Sixth, it is necessary to analyze the educational need to construct the contents of preventive education more systematically.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.175-184
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• 2019

The epidermal growth factor (EGF) has a intrinsic function of inducing growth and proliferation of cells through interacting with cell membrane receptors in human epidermis and dermis layer. These functions of EGF are used as a main ingredient for wound healing medicines and anti-aging cosmetics. As a cosmetic ingredient, the EGF has a problem in exhibiting its natural efficacy due to the lack of the ability to penetrate through the stratum corneum, which is known as the skin barrier. In this study, a recombinant human epidermal growth factor ($MTD_{151}-EGF$) fused with the macromolecule transduction domain $(MTD)_{151}$ with the skin penetration ability was developed to improve the skin penetration efficiency of the EGF. Expression of $MTD_{151}-EGF$ was performed in E. coli transformed with a vector encoding the $MTD_{151}-EGF$ gene and then purified. The purified $MTD_{151}-EGF$ was evaluated using cell proliferation assay, cytotoxicity test and skin penetration test by franz diffusion cell assay and artificial skin. Cell proliferation activity of $MTD_{151}-EGF$ purified to high purity of 99% or above was equivalent to the EGF or better, and cytotoxicity was not observed. In addition, the $MTD_{151}-EGF$ showed an excellent penetration efficiency compared to the EGF in the skin penetration test with EGF and $MTD_{151}-EGF$ labeled by FITC in an artificial skin penetration model. Based on the quantitative analysis of the penetrating substance using franz diffusion cell assay, the amount of penetration was about 16 times more than that of EGF. These results can be regarded as an effective alternative to improve the existing physical transdermal penetration method related to the use of various active ingredients for cosmetics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.131-138
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• 2019

Carbonylated proteins (CPs) are synthesized by the chemical reaction of basic amino acid residues in proteins with aldehyde compounds yielded by lipid peroxidation. CPs are excited by a range of light from UVA to blue light, and resulted in the generation of superoxide anion radicals ($^{\cdot}O_2{^-}$) by photosensitizing reaction. Then, they CPs induce new protein carbonylation in stratum corneum through ROS generation. Furthermore, the superoxide anion radicals produce CPs in the stratum corneum (SC) through lipid peroxidation and finally affects skin conditions including color and moisture functions. The purpose of this study was to investigate the relationship between the production of stratum corneum carbonylated protein (SCCP) and the skin elasticity. 46 healthy female Koream at the ages of 30 ~ 50 years old were participated in this study for 8 weeks. The skin test was experiment conducted into two groups; placebo group (N = 23) used cream that did not contain active ingredients, and the other group (N = 23) used cream containing the elasticity improving ingredients. Test areas were the crow 's feet and the cheek. Various non-invasive methods were carried out to measure biophysical parameters on human skin indicating that dermis density and skin wrinkle were measured by using DUB scanner and Primos premium, respectively. Skin elasticity were measured using dermal torque meter (DTM310) and balistometer (BLS780). SCCP was assessed in a simple and non-invasive method using skin surface biopsy on the cheek of the subject. The amount of SCCP was determined using image analysis. All measurements were taken at 0, 4 and 8 8week. Results revealed that the amount of CP in SC was reduced when the skin wrinkle and skin elasticity related parameters were improved. This indicates that the correlation between the elasticity improvement and the amount of CP can be used as a anti-aging indicator and applicable to the skin clinical test for the measurement of skin aging in the future.

• 한국노년학
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• v.37 no.2
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• pp.281-291
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• 2017

The present study aimed to investigate the rate of unmet healthcare needs for elderly over the age of 65 years, as well as analyze the relevance between employment status and unmet healthcare needs due to financial reasons. With regard to the study method, a logistic regression analysis was performed to investigate the correlation between employment status and unmet healthcare needs due to financial reasons, targeting 5,528 subjects over the age of 65 years. The results showed that the rate of unmet healthcare needs was 18.9%, in which the rate of unmet healthcare needs due to financial reason was 8.1%. The rate of unmet health needs was higher for temporary workers(ORs=1.75) than for retirement workers. However, the rate of unmet healthcare needs caused by financial reasons was higher among day workers(ORs=1.92). In conclusion, in order to prevent unmet healthcare needs for senior Korean patients, it is necessary to not only improve the income security system for the elderly, but also improve the occupational form and level of income of these economically active citizens, considering the increase in average life expectancy. Moreover, it is also necessary to reinforce health insurance coverage systems for settling medical expenses.

• Journal of the Korean Electrochemical Society
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• v.22 no.1
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• pp.36-42
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• 2019

A macroporous Sn thick film as a high capacity negative electrode for a lithium ion secondary battery was prepared by using a chemical etching method using nitric acid for a Sn film having a thickness of $52{\mu}m$. The porous Sn thick film greatly reduced the over-voltage for the alloying reaction with lithium by the increased reaction area. At the same time. The porous structure of active Sn film plays a part in the buffer and reduces the damage by the volume change during cycles. Since the porous Sn thick film electrode does not require the use of the binder and the conductive carbon black, it has substantially larger energy density. As the concentration of nitric acid in etching solution increased, the degree of the etching increased. The etching of the Sn film effectively proceeded with nitric acid of 3 M concentration or more. The porous Sn film could not be recovered because the most of Sn was eluted within 60 seconds by the rapid etching rate in the 5 M nitric acid. In the case of etching with 4 M nitric acid for 60 seconds, the appropriate porous Sn film was formed with 48.9% of weight loss and 40.3% of thickness change during chemical acid etching process. As the degree of etching of Sn film increased, the electrochemical activity and the reversible capacity for the lithium storage of the Sn film electrode were increased. The highest reversible specific capacity of 650 mAh/g was achieved at the etching condition with 4 M nitric acid. The porous Sn film electrode showed better cycle performance than the conventional electrode using a Sn powder.

• The Korean Journal of Archival Studies
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• no.41
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• pp.175-212
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• 2014

In 2001 a large amount of labor record have been donated from Jeontaeil Labor Archive-Institute to SungKongHoe University(SKHU). Institute of Labor History in SKHU was established in the wake of the installation of the labor archive. Development of oral archive raised the awareness of the various relationships between the use and production of labor record. Interviewees of oral testimony expressed dissatisfaction and the role of the researchers was not sufficiently exhibited. Examining the main cases of Korea union movement history, we can find contradictions between the use and production of labor record clearly. Interval of interpretation and memory was too big between the parties of 'democratic' union movement in the 1970s. While among the parties who took part in Guro Alliance Strike of 1985, there is a group that remains in the "winner" in history on the one hand, but "loser" on the other without any reasonable criterion. Active intervention of the record users(researchers) is very limited. Among citizens or workers how will be resolved such "struggle of memory" in due process can not be seen. This is one of the reasons why labor archive is not rooted in the region. In this paper, I present a methodological alternatives for the production and use of records through the construction of participatory labor archive. Further, the reconstituted contents of the "documenting locality" strategy by complementing the theoretical part of the method of participation. The study of local and locality requires a "scale" dimension that will make up the identity recognition space, a memory and identity, a social relationship rather than the dimension of the physical space. Alternative "documenting locality" strategy will be able to contribute to solve the problems that occur between the production and use of the recording in labor archive.