• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
• /
• pp.1-2
• /
• 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.

• Food Science and Preservation
• /
• 제19권6호
• /
• pp.799-806
• /
• 2012

This experiment was conducted to establish the optimum conditions for high $CO_2$ gas treatment in combination with a proper gas-permeable packaging film to maintain the quality of fig fruit (Ficus carica L). Among the fig fruits with different high $CO_2$ treatments, the quality change was most effectively controlled during storage in the 70%-$CO_2$-treated fig fruit. Harvested fig fruit was packaged using microperforated oriented polypropylene (MP) film to maintain the optimum gas concentrations in the headspace of packaging for the modified-atmosphere system. MP film had an oxygen transmission rate of about $10,295cm^3/m^2$/day/atm at $25^{\circ}C$. The weight loss, firmness, soluble-solid content (SSC), acidity (pH), skin color (Hunter L, a, b), and decay ratio of the fig fruits were monitored during storage at 5 and $25^{\circ}C$. The results of this study showed that the OPP film, OPP film + 70% $CO_2$, and MP film+70% $CO_2$ were highly effective in reducing the loss rate, firmness and decay occurrence rate of fig fruits that were packaged with them during storage. In the case of using treatments with packages of OPP film and OPP film+70% $CO_2$, however, adverse effects like package bursting or physiological injury of the fig may occur due to the gas pressure or long exposure to $CO_2$. Therefore, the results indicated that MP film containing 70% $CO_2$ can be used as an effective treatment to extend the freshness of fig fruits for storage at a proper low temperature.

• Journal of Korean Society of Forest Science
• /
• 제110권4호
• /
• pp.630-647
• /
• 2021

We determined the current problem of the restoration deposit-estimation system, stipulated by the Mountainous Districts Management Act, using the Delphi technique. Consequently, we proposed a standard model for forest land restoration to derive a reasonable deposit-estimation system. With the result of the Delphi survey, the inappropriateness of land-use type and slope gradient classifications was shown; the insufficiency of standard works was a significant problem in the current system. A way to solve these problems was devised, to reorganize the current land-use type into the subject of the site. The specific subjects included the following: (i) to permit or report forest land-use change and temporary use of forest land, (ii) to report temporary use of forest land, (iii) to permit stone collection or sale for mineral mining, and (iv) to allow sediment collection. The current slope gradient subdivision into (a) θ<10°, (b) 10°≦θ<15°, (c) 15°≦θ<20°, (d) 20°≦θ<25°, (e) 25°≦θ<30°, and (f) θ≧30° and the reorganization of 17 standard works into 22 standard works were deemed as solutions, along with seven additional works. We developed 24 standard models for the forest land restoration project based on the aforementioned results. The deposits estimated by these models ranged from 34,185,000 (Korean) won to 607,403,000 won. If additional works, premiums, discounts, and supervision fees are added to the models, the deposit increases to an estimated 668,143,000 won subject to permission for stone collection or sale and mineral mining. Experts agree on the distribution of the restoration deposits estimated by these models at a high level in the Delphi survey. Our findings are expected to contribute to securing the appropriateness of the restoration cost deposited for the smooth performance of the vicariously executed restoration project.

• Journal of Food Hygiene and Safety
• /
• 제34권4호
• /
• pp.354-360
• /
• 2019

In order to extend the shelf life of Wasabi paste, the effects of citric acid were confirmed at $35^{\circ}C$ for 28 days. Citric acid-treated groups contained citric acid in amounts of 0.05, 0.10, 0.17, 0.30, and 0.40%, respectively. Quality characteristics of Wasabi pastes were determined in pH, titratable acidity, soluble solid content, color values, microbial analysis (aerobic bacteria, yeast), gas production, and content of allyl isothiocyanate. The pH and titratable acidities of Wasabi pastes added with citric acid were indicated as 4.03-5.19 and 4.23-4.82%, respectively. Soluble solid content was significantly different according to concentrations of citric acid. L values showed the highest at $50.05{\pm}0.46$. a and b values were increased during the storage period. Total aerobic bacteria and yeast counts of Wasabi pastes were decreased in a dose-dependent manner. Gas production from Wasabi pastes showed at 19.55-19.80 mL/tube after 28 days of storage. The addition of citric acid (0.3% or more) to the Wasabi paste resulted in increased storage stability.

• The Korean Journal of Air & Space Law and Policy
• /
• 제33권2호
• /
• pp.267-290
• /
• 2018

This paper reviews and criticizes the EU Case of C-452/13, Germanwings GmbH v. Ronny Henning. Under this case, Ronny Henning later sued Lufthansa's budget carrier Germanwings after it refused to pay him 250 euros compensation for a delay he said totalled more than three hours. Germanwings, however, maintained his flight had arrived only two hours and 58 minutes behind schedule. In those circumstances, the following question to the European Court of Justice (ECJ) for a preliminary ruling: What time is relevant for the term time of arrival used in Articles 2, 5 and 7 of Regulation [No 261/2004]: (a) the time that the aircraft lands on the runway (touchdown); (b) the time that the aircraft reaches its parking position and the parking brakes are engaged or the chocks have been applied (in-block time); (c) the time that the aircraft door is opened; (d) a time defined by the parties in the context of party autonomy? ECJ says that the situation of passengers on a flight does not change substantially when their aircraft touches down on the runway at the destination airport, when that aircraft reaches its parking position and the parking brakes are engaged or when the chocks are applied, as the passengers continue to be subject, in the enclosed space in which they are sitting, to various constraints. Therefore, it is only when the passengers are permitted to leave the aircraft and the order is given to that effect to open the doors of the aircraft that the passengers may in principle resume their normal activities without being subject to those constraints. ECJ rules that it is apparent that Articles 2, 5 and 7 of Regulation No 261/2004 must be interpreted as meaning that the concept of 'arrival time', which is used to determine the length of the delay to which passengers on a flight have been subject, corresponds to the time at which at least one of the doors of the aircraft is opened, the assumption being that, at that moment, the passengers are permitted to leave the aircraft.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• 제14권3호
• /
• pp.59-71
• /
• 2019

The domestic unemployment rate is now seriously increasing due to the impact of the international trend of incurring high costs using only a small number of manpower in a situation where the business has been being reduced in size. The nation is taking start-up promotion policies as a way to overcome the problem, but with the advent of excessive entrepreneurs and their concentration on specific areas, their survival is in an unclear situation. Thus, this study was intended to provide a useful direction for successful start-ups by identifying the impact of entrepreneurial motivation and entrepreneurship, internal characteristics of entrepreneurs, and of competency characteristics, external characteristics of them, on sustainability through business performance. Thus, the purpose of this study was to provide a useful direction for successful start-ups by identifying the impact of entrepreneurial motivation and entrepreneurship, internal characteristics of entrepreneurs, competency, and external characteristics, on sustainability through business performance. The result of verifying the hypothesis has showed that entrepreneurial motivation, entrepreneurship, and competency characteristics had a positive effect on business performance, and on the other hand, the business performance had a positive effect on sustainability. In addition, in terms of the impact of entrepreneurial motivation, entrepreneurship, and competency characteristics on sustainability, all of them had mediating effects on business performance. It is obvious that studies on the factors affecting business performance and corporate sustainability up to now have been carried out by only collecting the independent variables of this study individually or two of them. so it is judged that if the study, which has verified the practical direction in general through the verification of entrepreneurs's internal and external characteristics from various angles, is performed more comprehensively along with the addition of background characteristics of entrepreneurs, such as characteristics of start-up preparation, etc., in the future, more in-depth results will be able to be obtained.

• (The)Study of the Eastern Classic
• /
• 제67호
• /
• pp.345-378
• /
• 2017

In the scriptures of "$Ch{\bar{u}}n-qi{\bar{u}}$(春秋)", the expression method of '$Ch{\bar{u}}n-w{\acute{a}}ng-zh{\bar{e}}ng-yu{\grave{e}}$(春王正月 : It's spring. It's the first month regulated by the king.)' was used as Jì-yuè-fǎ(紀月法 : the rules to determine the first month(正月)), the month of winter solstice was regarded as the first month of a year, and three years since then were named as $Ch{\bar{u}}n$(春 : spring). With regard to this "$Ch{\bar{u}}n-qi{\bar{u}}$"Wáng-lì("春秋"王曆 : the calendar regulated by the king of $Zh{\bar{o}}u$(周) dynasty in "$Ch{\bar{u}}n-qi{\bar{u}}$"), depending on whether Confucius(孔子) changed and recorded the names of the months and the season or not, there were three different arguments; the theory that 'Confucius changed the names of both the months and the season'(孔子改月 改時說), the view that 'Confucius changed the name of the season, not the names of the months'(孔子不改月 改時說), and then the theory that 'Confucius changed neither the names of the months nor the name of the season'(孔子不改月 不改時) since Song(宋) dynasty. The first view was taken by $Hh{\acute{u}}-{\bar{a}}n-gu{\acute{o}}$(胡安國) and $C{\grave{a}}i-ch{\acute{e}}n$(蔡沈), and the second theory was mentioned by Chéng-yí(程?) and Zhū-zǐ(朱子). The advocates of the third view had become remarkable since Ming(明) dynasty, and one of representatives was Wàng-yáng-míng(王陽明). All of them based their arguments on ancient scriptures and Confucian legal books, and there were cases of taking the same records as the support for different opinions. Confucius' so-called 'Chūn-qiū-bǐ-fǎ(春秋筆法 : the method to describe historical facts by making clear discrimination between right and wrong)' and '$Sh{\grave{u}}-{\acute{e}}r-b{\grave{u}}-zu{\grave{o}}$(述而不作 : the attitude to succeed virtuous men's achievements and only explain and describe them not creating and adding new contents)' could come from thoughts of $Z{\bar{u}}n-w{\acute{a}}ng$(尊王 : to respect the king with the virtues of benevolence, righteousness, propriety, wisdom and sincerity). Therefore, even though Confucius is assumed to have been the writer of "$Ch{\bar{u}}n-qi{\bar{u}}$(春秋)", whether he actually changed and recorded the names of the months and the season in the calendar used in "$Ch{\bar{u}}n-qi{\bar{u}}$" is doubtful. These theories on Confucius's intervention in the calendar of "$Ch{\bar{u}}n-qi{\bar{u}}$" hadn't been discussed as conflicting in reality until Tang(唐) dynasty.

• Development and Reproduction
• /
• 제12권3호
• /
• pp.289-296
• /
• 2008

BPES (Blepharophimosis/Ptosis/Epicanthus inversus Syndrome) is an autosomal dominant disorder caused by mutations in FOXL2. Affected individuals have premature ovarian failure (POF) in addition to small palpebral fissures, drooping eyelids, and broad nasal bridge. FOXL2 is a member of the forkhead family transcription factors. In FOXL2-deficient ovaries, granulosa cell differentiation dose not progress, leading to arrest of folliculogenesis and oocytes atresia. Using yeast two-hybrid screening of rat ovarian cDNA library with FOXL2 as bait, we found that small ubiquitin-related modifier (SUMO)-conjugating E2 enzyme UBE2I protein interacted with FOXL2 protein. UBE2I also known as UBC9 is an essential protein for processing SUMO modification. Sumoylation is a form of post-translational modification involved in diverse signaling pathways including the regulation of transcriptional activities of many transcriptional factors. In the present study, we confirmed the protein-protein interaction between FOXL2 and UBE2I in human cells, 293T, by in vivo immunoprecipitation. In addition, we generated truncated FOXL2 mutants and identified the region of FOXL2 required for its association with UBE2I using yeast-two hybrid system. Therefore, the identification of UBE2I as an interacting protein of FOXL2 further suggests a presence of novel regulatory mechanism of FOXL2 by sumoylation.

• Korean Journal of Animal Reproduction
• /
• 제23권4호
• /
• pp.337-345
• /
• 1999

The present study was conducted to investigate the effects of various co-culture systems and supplemented protein sources on the in vitro development of bovine IVF embryos. Bovine cumulus oocyte complexes (COCs) were matured and fertilized in vitro. Presumptive zygotes with cumulus cells were transferred to TCM-199 or CRlaa containing 10% FBS or 3mg/$m\ell$ BSA, and cultured for 36~40 hr. After primary culture, cleaved embryos were co-cultured with cumulus cells(CC), bovine oviduct epithelial cells(BOEC) or Buffalo rat liver cells (BRLC) in TCM-199 or CRlaa supplemented with FBS or BSA respectively, for further 6 days. Cleavage rate increased with BSA(P＜0.01) in the both TCM-199(79%) or CRlaa(74%) When embryos were co-cultured with CC or BOEC in TCM-199, blastocyst development was enhanced with BSA(40% and 43%) compared to FBS (22% and 29%) , whereas in CRlaa no difference observed between BSA(40% and 39%) and FBS (40% and 42%). When embryos were co-cultured with BRLC monolayer, FBS enhanced the blastocyst development (P＜0.05) compared to BSA in both TCM-199(41% vs 31%) and CRlaa (44% vs 37%). The result of the present study showed that the cleavage rate of bovine IVF embryos increased with BSA, The result also showed that BSA can enhance the development of IVF embryos in co-culture with CC or BOEC in TCM-199, suggesting the in vitro development is affected by the medium and supplemented protein sources in co-culture with somatic cells.

• 한국노년학
• /
• 제30권3호
• /
• pp.831-842
• /
• 2010

BACKGROUND: Sarcopenic obesity(SO), a condition of the reduction in muscle mass paired with an increased fat mass has been paid attention because of its association with disability in later life. A few evidence, however, has reported the association with these factors. PURPOSE: To explore the association among SO, physical function and fitness in older women. METHOD: 257 older women(age of 74) were recruited from Y city and 7 physical functions and 4 fitness tests were measured. Participants were classified into one of four groups based on their body fat and muscle mass: Normal group (GR-A), high fat(GR-B), sarcopenia(GR-C), and sarcopenic obese(GR-D). GLMand LSD-test were conducted with SPSS 12.0. RESULTS: Chair stand, arm-curl, back-scratch, 2-min steps of GR-A was higher than GR-C and GR-D(p<.05). One-leg stand of GR-A was higher than GR-D(p<.01) and of GR-C was higher than GR-D(p<.01).8ft-TUG of GR-D was lower than GR-A(p<.01). Grip strength, knee extension of GR-A was higher than that of GR-C and GR-D(p<.01) and knee flexion of GR-A was also higher than that of GR-C and GR-D(p<.01). CONCLUSION: Based on our findings, we conclude that SO is significantly associated with lower physical function and fitness in older Korean women, which alarm the risk of frailty induced by SO.