• Parasites, Hosts and Diseases
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• 제27권3호
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• pp.161-170
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• 1989

Toxeplasma의 추출액을 3H-casein을 기질로 반응시켰을 때, pH 6.0과 PH 8.5에서 casein을 분해하였으며, pH 6.0에서는 cysteinyl protease의 억제제 인 iodoacetamide(rAh)에 의해 억제되 었고, 활성제 인 dithiothreitol (DTT)에 의해 환성이 증가하였다. 또 pH 8.5에서는 serine protease의 억제제인 phenylmethylsulfonil fluoride (PMSF)에 의해 활성이 억제되었으며, ATP를 첨가할 때 그 활성이 증가하여 ATP 의존성 효소임을 알 수 있었다. 위의 단백질 분해 효소를 부분 정제하기 위해 여러 chromatography를 실시하였는데, 먼저 DE52 (2.Sfx40 cm)에 통과시켰을 때, 0.05M-0.IM NaCl에 의해 유출되는 분획이 pH 6.0에서 황성을 나타내었으며, 0.25V- 0.3M에서 유출되는 분획이 pH 8.5에서 황성을 나타내었다. 이 분회들을 각각 Sephadex G-200 ($2.50{\phi}{\times}40cm$) 에 통과시켜 pH 6.0에서 활성을 나타내는 분획은 exclusion limit내에서, pH 8.5의 분획은 exclusion limit 외에서 분획을 얻었다. 이들을 각각 hydroxylapatite ($2.50{\phi}{\times}10cm$과 $2.5{\phi}{\times}20cm$)를 통과시켜 각각을 0.05M Phosphate로 유출되는 분회에서 높은 환성을 얻었다. 부분 정제된 분획들의 특성을 검토하기 위하여 억제제를 농도별로 처리하였을 때, pH 0.0에서의 분해 효소는 10-3M IAA에 의해 활성이 반감되어 cysteinyl acid protease임을 알 수 있었다. pH 8.5에서의 분해 효소는 10-5M PMSF에 의해 활성이 반감되었고, ATP에 의해 활성이 증가(ATP의 농도가 2.0mM 이상에서는 억제)하여 ATP-dependent neutral serine protease임을 알 수 있었다.

• 한국세라믹학회지
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• 제49권3호
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• pp.216-220
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• 2012

Mullite formation in a porcelain body was promoted extensively by replacing kaolinite with pyrophyllite. Effects of mullite formation and vitrification by substitution of kaolinite with pyrophyllite on the mechanical and thermal properties were investigated. Addition of 45-55% pyrophyllite (pyrophyllite (45-55%)-feldspar (30%)-Gairome clay (20%)) could vitrify the sintered samples (water absorption : 0.05%, bulk density : 2.66g/cc) and improve the flexural strength (122MPa) when fired at $1280^{\circ}C$. Mullite formation was found to be decreased with increasing content of pyrophyllite. On the contrary, beyond 50% of pyrophyllite quartz and cristobalite phases was found to be increased. Thermal expansion coefficient of the samples decreased with increase of mullite phase. In triaxial system of pyrophyllite-feldspar-clay, the mullite formation of the samples with 50% pyrophyllite reaches about 78.7% and thermal expansion coefficient was found to be $5.4{\times}10^{-6}/K$.

• 한국의류학회지
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• 제25권4호
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• pp.707-718
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• 2001

The purpose of this study is to evaluate a newly developed protective suit with the fragments of grenade. The protection efficiency should be strengthened upon the degree of wound. The fragment weight of the used grenade was measured and the kinetic energy of the maximum speed of the fragments in the field test was 137.7J and this could be the protective efficiency test by the multitude fragments in less than 0.031g of the M16A1. The panel inserted to the new demining suit has protection rate of 100% within the distance of 1m and sample II has protection rate of 100% only beyond the distance of 5m. The test showed that the protection rate on the protective suit of the existing garment was comparatively high, however, the protection rate of the sleeve part was very low. The new demining suit through the research demand some complementary measures to lower the temperatures in ear, average skin temperatures, and the temperatures-humidity inside the clothing for summer climate condition, It showed that 30 minutes of rest on the clothing was difficult to go back to the original condition. But in winter climate condition, there was no problem in the temperature, humidity, and comfort to go back to the original condition during the rest and was better in warmth.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.447-456
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• 2005

Laser driven accelerators promise to provide an alternative to conventional accelerator technology. They rely on the excitation of large amplitude density waves in a plasma by the photon pressure of an intense laser. The density oscillations in which electrons and ions are separated, result in extremely large longitudinal electric fields that can be several orders of magnitude larger than those that are used in today's radio-frequency accelerators. Whereas this principle had been demonstrated experimentally for nearly two decades, it was not until 2004 that the production of high quality electron beams around 100 MeV was demonstrated. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, are the keys to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short and long term prospects for intense radiation sources and high energy accelerators based on laser-drivenplasma accelerators.

• 한국가축번식학회지
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• 제20권1호
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• pp.63-69
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• 1996

Bovine immature oocytes cultured for various times in TC-199 medium were inseminated with frozne-thawed spermatozoa in TC-199 medium supplemented with caffeine(5mM) and heparin(10$\mu\textrm{g}$/ml). Sperm penetraton was possible in oocytes at any stage of maturation, but penetration rates were lower in oocytes inseminated 0~16h (60~76%) than 20h (98%) after culture. Formation of male and female pronuclei were first observed in oocytes inseminated 8h after cultrue. Formation of male and female pronuclei were first observed in oocytes inseminated 8h after culture. The proportions of polyspermy were high(50~76%) in oocytes inseminated at any stage of maturation. Sperm penetration into oocytes at the GV stage started at 8h after insemination and the penetration rates gradually increased as time after insemination proceeds. The proportion(35%) of oocytes matured beyond metaphase-II 20h after sperm-oocytes incubation was low. When oocytes were incubated without spermatozoa in TC-199 medium, maturation rates were significantly higher (P<0.001) in those without(45 and 84% for 16 and 20 h) than with (0 and 36% for 16 and 20 h) caffeine and heparin. These results indicate that TC-199 medium with caffeine and heparin is not suitable for maturation and fertilization of immature oocytes and may inhibit male pronuclear formation in the cytoplasm.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.253-256
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• 1997

KESF-1 foot conceptually provides storage of potential energy and is converted to kinetic energy throughout the weight - bearing phase of the gait cycle. This stored energy is progressively released as the foot continues through the toe-off phase to rebound and propel the body forward. A weight deflects the keel through a predetermined range, then the keel "springs back" as weight is removed. Foot designs criteria were selected to guide development beyond the proof-of concept composite material keels; 1) store and return energy (1-3/4 " metatarsal deflection at 435 pounds vertical load), 2) natural feel and stability; 3) useful life of 3-years: 4) lightweight; 5) reduced production costs. The purpose of this study is developed the comfortable stable foot that fitted with Korean lifestyle and road condition. The results produced the realistic cosmetic foot cover with polyurethane form and the keel composed with composite materials of both glass fiber and carbon fiber.

• 한국전산유체공학회지
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• 제19권1호
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• pp.34-40
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• 2014

Conjugate heat transfer of an automotive oil cooler with offset-strip fins was numerically investigated to predict the performance of the oil cooler for various flow-rates. The simulations were conducted by directly modeling offset-strip fins with unstructured meshes. The incompressible Navier-Stokes equations coupled with energy equation were used for the present simulations. Heat transfer characteristics of the oil cooler was compared well with experimental results and the errors were approximately within 5 percents. It was found that the performance of the oil cooler increased as the flow-rate increased up to the flow-rate of 12 L/min, but the performance seemed to be saturated beyond a critical flow-rate, which was estimated as 15 L/min. Furthermore, it was confirmed that compared to the performance without fins, that of the oil cooler with offset-strip fins was increased by about 75 percents.

• Preventive Nutrition and Food Science
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• 제2권1호
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• pp.42-48
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• 1997

the exocrine pancreatic secretion is an important factor in the maintenance of zinc homeostasis. The daily pancreatic secretion of zinc into the gastrointestinal tract may be two or more times the daily dietary zinc intake. The objective of this study was to examine the distribution of proteins and zinc in pancreatic/biliary fluid following intraperitoneal {TEX}${65}^Zn${/TEX} injection into dietary prepared Sprague-Dawly rats. Distribution of zinc-binding protein in Sephadex G-75 subfractions showed a peak corresponding to the high molecular weight protein standard(<66kDa) in the pancreatic/biliary fluid. Zinc also was associated with the 29~35kDa mole-cular weight proteins. These are similar in size with zinc-containing enzymes, carboxypeptidase A and car-boxypeptidase B. A more remarkable small molecular weight fraction eluted beyond the 6.5kDa standard pro-tein peak. These results show the presence of small molecular weight compound in pancreatic/biliary fluid associated with zinc . These small molecular weight compounds may serve as zinc-binding ligands for the secretion of enogenous zinc into the duodenum. These findings suggest that these lignads may dissociate zinc in the duodenum thus making it vulnerable to complexation with phytate in the upper gastrointestinal tract rendering the zinc unavailable for reabsorption.

• 한국가시화정보학회지
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• 제11권1호
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• pp.48-52
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• 2013

This paper presents experimental observation of asymmetric electrohydrodynamic flow generated around a pair of symmetric coplanar electrodes. Electrodes are attached on the bottom of the cavity containing a dielectric liquid, i.e., a mixture of dodecane and 0.5% wt Span80. In the first experiment, an AC voltage of 1500 V is applied with the frequency varying in the range 10~500 hz and the left electrode being grounded. The flow patterns show that the center line of vortices is unexpectedly tilted to the left side. If the right side electrode is grounded, the center line is tilted to the right side. The magnitude of the fluid velocity shows an irregular variation with the frequency in the range 10 Hz~100 Hz, beyond which it simply decays. In the second experiment, we applied fixed AC with 1000 V and 60 Hz superposed by DC voltage varying in the range -1000 V ~ +1000 V. The center line of the flow pattern is tilted to the right side with positive DC voltage and to the left side with negative DC. We have managed to show that the flow pattern can be symmetric with a suitable combination of DC and AC, e.g., DC 850 V plus AC 1000 V with the frequency 10 Hz.

• Progress in Superconductivity
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• 제3권1호
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• pp.5-12
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• 2001

Our experimental research focuses on manipulating pinning deflects to alter the phase diagram of vortex matter, creating new vortex phases. Vortex matter offers a unique opportunity for creating and studying these novel phase transitions through precise control of thermal, pinning and elastic energies. The vortex melting transition in untwinned YB $a_2$C $u_3$ $O_{7-}$ $\delta$/ crystals is investigated in the presence of disorder induced by particle irradiation. We focus on the low disorder regime, where a glassy state and a lattice state can be realized in the same phase diagram. We follow the evolution of the first order vortex melting transition line into a continuous transition line as disorder is increased by irradiation. The transformation is marked by an upward shift in the lower critical point on the melting line. With columnar deflects induced by heavy ion irradiation, we find a second order Bose glass transition line separating the vortex liquid from a Bose glass below the lower critical point. Furthermore, we find an upper threshold of columnar defect concentration beyond which the lower critical point and the first order melting line disappear together. With point deflect clusters induced by proton irradiation, we find evidence for a continuous thermodynamic transition below the lower critical point..