• Journal of Dental Rehabilitation and Applied Science
• /
• v.16 no.1
• /
• pp.51-60
• /
• 2000

The purpose of this study was to compare the microleakage at the interface of cast post and tooth according to the type of cement. Forty anterior teeth with single root were used. The teeth were cut 2 mm coronal from the cementoeamel junction and chamfer finish line was made on 1 mm coronal from the cementoeamel junction. After the routine endodontic treatment, post space was prepared using #5.5 Parapost drill to a depth of 7 mm. After the pick up impression, core building was made to 3 mm of clinical crown with burnout wax, then post and core was cast with nonprecious metal. The teeth were divided into four groups of ten each. In Group I, post and core were cemented with Fleck's(Zinc phosphate cement) In Group II, post and core were cemented with Fuji I(Glass ionomer cement) In Group III, post and core were cemented with Superbond C & B(Composite resin cement) In Group IV, post and core were cemented with Panavia 21(Composite resin cement) All cemented teeth were stored in normal saline at $37^{\circ}C$ for 7 days and thermocycled from $5^{\circ}C$ to $55^{\circ}C$ for 500 cycles with a dwell time of 30 seconds. After thermocycling, teeth were immersed in 1% Basic fuchsin dye for 48 hours. All 40 teeth were then embedded in the epoxy resin and cut buccolingually with a cutting instrument. The degree of penetration of dye at interface was graded on a scale of 0 to 4 using a stereomicroscope at 25 to 40 times magnification. Through the findings of this study, the following conclusion were obtained. 1. All the groups showed the microleakage at the interface of cast post core and tooth. 2. Group I showed the highest microleakage score among the groups with a significant difference(p<0.05). 3. Group II showed higher microleakage score than Group III and Group IV with a significant difference(p<0.05). 4. Group IV showed the lowest microleakage score but there were no significant difference with Group III(p>0.05).

• 보존과학연구
• /
• s.33
• /
• pp.45-55
• /
• 2012

A beeswax-treated paper has no air permeability but has the water repellency compared with a general Hanji. Because of these properties, the differences of the aging factors and mechanisms between the outer partition of beeswax-treated paper that is affected by the surrounding conservation environment and the inner partition of it that is not affected are bigger than general books. In this research, we analyzed and compared the aging characteristics through the accelerated aging of the beeswax-treated paper by some air and humidity conditions. The results of the physical and optical analysis after the artificial aging, it was shown that the oxygen accelerates the aging of the beeswax-treated paper and the condition with the humidity 50% RH is more stable than the condition with the humidity 0% RH. The results of the CG/MS analysis that was conducted to figure out the decomposition charateristics of the beeswax according to the air quality and the humidity, a low molecular weight compound that the number of carbon is C9-C20 including a fatty acid such as a palmitic acid was increased as the aging was progressed. However, under the same environment, a compound that the number of carbon is C21-C36 including a hydrocarbon and a aliphatic alcohol and a high molecular weight compound that the number of carbon is more than C34 including a wax ester were decreased. A rate of change according to the air quality and the humidity was similar to the beeswax-treated papers.

• Korean Journal of Agricultural Science
• /
• v.36 no.1
• /
• pp.1-10
• /
• 2009

The characteristics of fruit ripening and cell wall modifications of two oriental pear fruits were compared during storage. The loss of fresh weight was lower in 'Pingguoli' than 'Niitaka', probably due to the difference in wax accumulation and skin structure. 'Pingguoli' produced much higher amount of ethylene and showed climacteric ripening pattern, but this response was not found in 'Niitaka'. A significant difference in soluble pectin contents was found, thus, the amount of water soluble pectins were much higher in 'Niitaka' at harvest but this difference was not significant at later stage of storage. A severe loss of water soluble pectins in 'Niitaka' was confirmed whereas a similar tendency was not found in CDTA soluble ones. Even the amount of $Na_2CO_3$ soluble pectins was relatively low, 'Pingguoli' contained approximately 2 times higher than 'Niitaka' and both cultivars showed an increasing tendency in $Na_2CO_3$ soluble polymers at later stage of storage. No significant difference in alkali soluble polysaccharides (hemicelluloses fraction) was found between both cultivars. There was a significant change in gel filtration profiles regardless of cultivars, especially in water soluble pectins resulting from severe depolymerization probably due to degradation of higher molecular weight pectins and loss of their side chains. In gel filtration profiles of $Na_2CO_3$ soluble pectins, neutral sugars were evenly distributed regardless of molecular size of pectic polymers but the decrease of high molecular weight fraction was found. In comparison of alkali soluble polymers, a similar trend was found, that is, there was no difference in gel filtration profiles but 'Niitaka' seemed to have longer side chains in alkali soluble polysaccharides in both 4% and 24% of KOH soluble fractions.

• The Journal of Korean Medicine
• /
• v.19 no.2
• /
• pp.125-136
• /
• 1998

This study is on the etiological factors of the obesity, symptoms of a disease caused by the etiological factors and the method of medical treatment resulted from symptoms of a disease, it is based on Dong-Yi Bo Gam. The conclusion of this study is as follows. 1. The final metabolic of fat is depend on the defensive energy. The shape of fatty layer is changed by the point where the defensive energy is replenish or not. So 'Goin(暠人)' 'Bein(肥人)' and 'Yuckin(肉人)' is made a discriminated and there is defferent between 'Besudaeso(肥瘦大小)' and 'Herlqidaso(血氣多少)'. 2. Etiological factors of obesity is ; essential substance from cereals overcome the primodial energy, spleen and stomach are strong at once, spleen and stomach are weak at once, spleen is disturbed by evil energy, retention of phlegm and fluid, muscle is weak, blood is excess but energy (qi)is weak, hua-sid(華食) eating the sweat food very often, a rich fatty diet. 3. To investigate each syndrome as etiological factons, essential substance from cereals overcome primodial energy is divided into two case: one is the food increase itself because of the weakness of stomach energy (qi), the other is not to digest the food because liver overact spleen by seven emotion. The obesity because of strengthen of the spleen and stomach at once do not feel hungry very well and spleen and stomach do not damaged easily by overacting. The obesity because of weakness of spleen and stomach at once, and disturbace in spleen cause by evil energy, gain the weight even if they eat food a little. Also it is hard to move four limbs. Weakness of muscle is weakness of spleen and stomach. Weakness of muscle is caused by weakness of spleen and stomach. That is the case of faining the weight because of eating food with an empty stomach. The obsity caused by retention of fluid has intestine rumbling and gain the weight suddenly. 4. The method of medical treatment fallowing to the etiological factors: The food is inclined to increase itself caused by weakness of stomach energy, In case of the obseity caused by this phenomenon. We can use Decoction for Reinforcing Middle wanner and Replenishing Qi(補中益氣湯), five tastes il-going-san(左味異功散) and so on. The method of medical treatment on obsity caused by strengthen of spleen and stomach is not referred yet. But we must investigate about using peptic powder(平胃散), ji-chul-huan(枳朮丸) for strengthen of stomach qi (胃氣). If the obesity appear caused by weakness of spleen and stomach and disturbance in spleen as to evil energy, and in the same time stomach qi is weak, we can use li-gong san(異功散). If not only obesity but also indigestion, we can use Decoction for naurishing the stomach and promotion eating(養胃進食湯). If not only obesity but also weakness of spleen and stomach, we can use Decoction for Reinforcing Middle warmer and replenishing Qi(補中益氣湯). The energy being weak, we can use Decoction for six noble drugs(六君子湯). If the obesity appear because of retention of fluid, we can use sin-chul-huan(神朮丸). On the obesit, caused by excess of blood and weakness of qi(血管氣虛), there is not method of mectical treatment yet, but the method of medical treatment that we count of first important maybe to invigorate the spleen and the lung qi and to disperse and recitify the depressed liver energy(疏肝利氣). The method of medical treament about the obesity caused by a rich fatty diet is not mentioned yet, but it is important to improve the lifestyle of food and we think that invigorate the spleen, and the lung-qi(補疏肝氣) and disperse and recitify the depressed liver-energy (??肝利機) amy count of first important. 5.There is useful medicine for weight down for example Herb tea(茶), red bean, wax gourd, etc. 6.The etiological factors of the obesity that revive frequently is weakness of qi(氣虛), from 形成氣衰, deficiency of yang, hasty of qi, damp and so on. The symptoms and sign of a disease that revive frequently to the obesity is appoplexia(中風), leucorrhea, reddish and whitish turbid, feeling of fullness in the upper abdomen, diabetes and so on.

• The Korean Journal of Pesticide Science
• /
• v.3 no.2
• /
• pp.60-68
• /
• 1999

Effects of temperature and dose-size on infectivity and reproduction of Korean entomopathogenic nematode, Steinernema longicaudum Gongju strain were examined. The greater wax mea Galleria mellonella larvae were exposed to 5, 10, 20, 40, 80, and 160 infective juveniles/larva in $60{\times}15$ mm petri dishes and kept in $13^{\circ}C$, $18^{\circ}C$, $24^{\circ}C$, and $30^{\circ}C$ incubators. Each petri dish contained one larva weighed from 180 to 200 mg. Infectivity was observed everyday for 14 days and reproduction for 30 days. The infectivity of S. longicaudum was more influenced by temperature than by dose-size. Mortalities by S. longicaudum were lower at $13^{\circ}C$ at all concentrations but higher at $24^{\circ}C$ and $30^{\circ}C$ even at lower concentrations, 5 or 10 infective juveniles/larva. Lethal time was also shorter with increasing temperature and dosages. All host larvae died at $24^{\circ}C$ and $30^{\circ}C$ in 2 days at the rate of 160 infective juveniles per host while 83.3% of tested larvae died at $24^{\circ}C$ in 10 days and 90% at $30^{\circ}C$ in 6 days at the rate of 5 infective juveniles. Reproduction was also better with increasing temperature and dosages. The highest number of progenies was obtained at $30^{\circ}C$ in 6 days at the rate of 80 infective juveniles. However, progenies were not produced from cadavers at $13^{\circ}C$. Reproductive period was the shortest at $30^{\circ}C$ of all temperatures by 6 to 9 days. The results indicated that optimum temperatures for infectivity was $24^{\circ}C$ and $30^{\circ}C$ for reproduction.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.3
• /
• pp.484-495
• /
• 2020

This study is a mixed surfactant (MimicLipid-MSM1000) that forms the same structure as that of the stratum corneum, sucrose distearate, polyglyceryl-2 dioleate, fermented squalane, ergosterol, 10-hydroxystearic acid, mixture consisting of was synthesized. When using 2~5 wt% of this mixed surfactant, it was possible to make an artificial skin mimetic that forms a multi-layer lamellar structure of 5~30 layers. An emulsion was prepared using this mixed surfactant, and a multi-layered lamellar phase was formed and analyzed mechanically. The appearance of this surfactant was a light brown hard wax, the hydrophilic lipophilic balance (HLB) was 12.53, the critical parameter value was 0.987, and the acid value was 0.13. Stability according to pH change was also stable in acidic (3.8), neutral (7.2) and alkaline (10.8). The particle size of the liquid crystal was found to be the most stable maltese cross lamellar crystalline droplet at 5~25mm. The size of the emulsified particles according to the change in the speed of the homo agitator is 2500 rpm (17.9mm±2.6mm), 3500rpm (12.5mm±2.1mm), 4500rpm (6.2mm±1.8mm) particles were formed. Liquid crystal forming particles were observed through a polarization microscope, and the formation structure of the liquid crystal was precisely analyzed with a scanning electron microscope (cryo-SEM). As an application field, it is expected that it will be widely applicable to the development of various prescriptions, such as various skin care cosmetics, makeup care cosmetics, and scalp protection cosmetics, by using a skin-mimicking surfactant.

• Restorative Dentistry and Endodontics
• /
• v.31 no.6
• /
• pp.452-459
• /
• 2006

Competition will usually develop between the opposing walls as the restorative resin shrinks during polymerization. Magnitude of this phenomenon may be depended upon cavity configuration and volume. The purpose of this sturdy was to evaluate the effect of cavity configuration and volume on microleakage of composite resin restoration that has margins on the enamel site only. The labial enamel of forty bovine teeth was ground using a model trimmer to expose a flat enamel surface. Four groups with cylindrical cavities were defined, according to volume and configuration factor(Depth x Diameter / C-factor) - Group I : 1.5 mm ${\times}$ 2.0 mm / 4.0, Group II : 1.5 mm ${\times}$ 6.0 mm / 2.0, Group III : 2.Omm ${\times}$ 1.72 mm / 5.62, Group IV : 2.0 mm ${\times}$ 5.23 mm / 2.54. After treating with fifth-generation one-bottle adhesive - BC Plus$^{TM}$ (Vericom, AnYang, Korea), cavities were bulk flted with microhybrid composite resin - Denfill$^{TM}$ (Vericom). Teeth were stored in distilled water for one day at room temperature and were finished and polished with Sof-Lex system. Specimens were thermocycled 500 times between 5$^{\circ}$C and 55$^{\circ}$C for 30 second at each temperature. Teeth were isolated with two layers of nail varnish except the restoration surface and 1 mm surrounding margins. Electrical conductivity (${\mu}$A) was recorded in distilled water by electrochemical method. Microleakage scores were compared and analyzed using two-way ANOVA at 95% level. The results were as follows: 1. Small cavity volume showed lower microleakage score than large one, however, there was no statistically significant difference. 2. There was no relationship between cavity configuration and microleakage. Factors of cavity configuration and volume did not affect on microleakage of resin restorations with enamel margins only.

• Korean journal of applied entomology
• /
• v.51 no.1
• /
• pp.9-18
• /
• 2012

The size of infective $Steinernema$ $arenarium$ juveniles is variable and ranges from 724 to 1408 ${\mu}m$. Effects of harvest time and infective juvenile size on pathogenicity, development, and reproduction were examined in the last instar of the great wax moth, $Galleria$ $mellonella$. Harvest time of infective juveniles (IJs) of $S.$ $arenarium$ affected pathogenicity. IJs harvested at the 10th day from trapping were more pathogenic than those harvested the 3rd day from trapping. Mortality of $G$. mellonella also depending on harvest time, $i.e$, 100% died within 48h when IJs were harvested at the 10th day, without relation to size. However, mortality was 40% in the small size group (SSG) compared with 18% in the large size group (LSG) within 48h when IJs were harvested at the 3rd day. Establishment of $S.$ $arenarium$ within the host was different depending on IJ size. The number of established IJs was 1.8 in the SSG, 3.3 in the LSG, and 3.2 in the mixed size group (MSG) when IJs were harvested at the 3rd day, and 5.3 in the SSG, 7.4 in the LSG, and 7.6 in the MSG when IJs were harvested at the 10th day. The length of the female adult was 7,070.5 ${\mu}m$ in the SSG and 7,893.9 ${\mu}m$ in the LSG and that of the male was 1,460.5 ${\mu}m$ in the SSG and 1,688.2 ${\mu}m$ in the LSG when IJs were harvested at the 3rd day. The length of the female adult was 7,573.6 ${\mu}m$ in the SSG and 8,305.4 ${\mu}m$ in the LSG and that of the male adult was 1,733.4 ${\mu}m$ in the SSG and 1,794.4 ${\mu}m$ in the LSG when IJs were harvested at the 10th day. Harvest time and size of IJs did not influence numbers of progeny or size of IJS.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.29 no.4
• /
• pp.317-326
• /
• 2013

This study was to compare the cumulative survival rate of implant-supported fixed prostheses and to analyze association between risk factors and cumulative survival rate of implant-supported fixed prostheses. In order to assess the clinical status of implant-supported fixed prostheses, individuals who treated in the Department of Prosthodontics, Pusan National University Dental Hospital, between 2000 to 2007 were examined. The results of this study were as follows: 1. Length of service of implant-supported fixed prostheses was $6.6{\pm}32.0$ years (mean), 11.7 years (median). 2. Age and sex of patient was found to have no statistically significant influence on longevity of implant-supported fixed prostheses (P>.05). 3. Reason of tooth extraction wax found to have statistically significant influence on implant-supported fixed prostheses (P<.05). The longevity of fixed prostheses was low in tooth extraction case due to periodontal disease (median:9.0 years). 4. Location of implant-supported fixed prostheses was found to have statistically significant influence on longevity of fixed prostheses (P<.05). The longevity of fixed prostheses was low in molar region (median:8.8 years). 5. Number of units in implant-supported fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses (P>.05). 6. Condition of opposing dentition was found to have no statistically significant influence on longevity of implant-supported fixed prostheses (P>.05). 7. Food impaction (40.5%), porcelain fracture (25.8%), screw loosening (23.6%) were frequent complications.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.04a
• /
• 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.