• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.415-416
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• 2010

• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.130.2-130
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• 1999

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.4
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• pp.220-230
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• 2006

Fracture behavior of a monolithic PZT and a plate-type piezoelectric composite actuator (PCA) has been investigated under a bending load at three points by an acoustic emission (AE) monitoring. AE signal from a monolithic PZT at the maximum bending load shows the characteristics of high amplitude and long duration with a low frequency band of $100{\sim}230kHz$ which is confirmed by fast Fourier transform (FFT). For a PCA, it is concluded that AE signals with high amplitude over 80dB and low dominant frequency band of $170{\sim}223kHz$ emitted in the stage I are due to the brittle fracture in the PZT layer and the delamination between the PZT layer and the adjacent fiber composite layer. Based on the above analysis of AE behavior and damage observations with an optical microscopy and a scanning electron microscopy, AE characteristics related to fracture behavior of asymmetrically laminated PCA have been elucidated.

• Journal of Veterinary Clinics
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• v.19 no.2
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• pp.228-235
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• 2002

Mastitis is the most costly disease results in lost milk production, decreased milk quality, milk discard, early culling of cows, drug costs and labor costs in dairy cow. Until now, a antibiotic administration at the end of lactation, dry cow therapy has been known the most effective and widely used mastitis control method. However, dry cow therapy do not control a new infection in the late dry and prepartum period because dry cow products have only persistent activity in the early dry period. Therefore, this study was conducted to evaluate clinical effect of sustained released biodegradable cephalexin microsphere using PLGA in bovine mastitis control during dry period. PLGA has been approved as controlled drug release system because of non-toxic, non-tissue reactive and bioerodible characteristics. This study revealed that cephalexin microsphere had a spherical shape with characteristic porous structure on the surface. Also, in vitro drug release studies are clearly observed that the release rate of cephalexin from PLGA microsphere decrease during the first 21 days after initial burst and then increase again between 3 and 4 weeks showing pulsatile releasing pattern. On the other hand, as tried in field the new infection rate, cure rate and mean SCC after parturition in cephalexin microsphere infused group were significantly differenced as compared to the control group. Accordingly, a sustained release of cephalexin from a biodegradable microsphere could make dry cow therapy more efficiently by preventing a new infection and decreasing the number of existing infection of mammary gland during dry period.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.187-196
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• 2004

The health effects resulting from severe accidents of typical 1,000MWe KSNP(Korea Standard Nuclear Plant) PWR and typical 600MWe CANDU(CANada Deuterium Uranium) plants were estimated and compared. The population distribution of the site extending to 80km for both site were considered. The releaese fraction for various source term categories(STC) and core inventories were used in the estimation of the health effects risks by using the MACCS2(MELCOR Accident Consequence Code System2) code. Individuals are assumed to evacuate beyond 16km from the site. The health effects considered in this comparative study are early and cancer fatality risk, and the results are presented as CCDF(Complementary Cumulative Distribution Function) curves considering the occurrence probability of each STC's. According to the results, the early and cancer fatality risks of PHWR plants we lower than those of PWR plants. This is attributed the fact that the amount of radioactive mateials that released to the atmosphere resulting from the postulated severe accidents of PHWR plants are smaller than that of PWR plants. And, the dominating initiating event of STC that shows maximum early and cancer fatality risk is SGTR(Steam Generator Tube Rupture) for both plants. Therefore, the appropriated actions must be taken to reduce the occurrence probability and the amounts of radioactive materials released to the environment in order to protect the public for both PWR and PHWR plants.

• Polymer(Korea)
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• v.31 no.4
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• pp.329-334
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• 2007

Osmotic pellet system, which is one of the oral drug delivery systems, has been developed to improve manufacturing process, reduce product cost and other problems of osmotic tablet systems. Osmotic pellet is consisted of water swellable seed layer, drug layer, and membrane layer. Among them, the membrane layer plays an important role in a control of the drug release. In this work, we examined the effect of ratio for Eudragit RL and RS on the drug release behavior. Osmotic pellet with nifedipine as a model drug was easily obtained in a good yield by fluidized bed coater. Osmotic pellet showed round morphology with a range of size $1300{\sim}1500\;{\mu}m$. In the experiment of nifedipine release, the release amount increased with the increase of the ratio of Eudragit. This is due to the fact that Eudragit RL contains more hydrophilic quaternary ammonium group than Eudragit RS. Additionally, the release amount was retarded with increasing the membrane thickness. There are no differences in the release amount measured at the different pH 1.2, 6.5, 6.8, and 7.2. In conclusion, it was found that the drug release from osmotic pellets depended on the composition ratio and coating thickness of membrane layer.

• Analytical Science and Technology
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• v.12 no.4
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• pp.284-289
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• 1999

Dissolved inorganic carbonates in ground water were quantitatively recovered by using gas evolution method. Gas evolution method was found to be less time-consuming, less susceptible to the contamination fromatmospheric $CO_2$ and little affected by the sulfate ions in comparison to the direct precipitation method. Extraction efficiency of nearly 99% could be achieved by gas evolution method in two hours using recirculated gas at a sweeping rate of 4 liter per minute. Samples for carbon isotope fractionation study were collected in three fractions with collection times. The evolution time for the first fraction was one hours, and then second and third fractions were collected at intervals of 30 minutes, respectively. A small portion of each fraction was analyzed to evaluate ${\delta}^{13}C$ values, which were measured to be -7.9‰, -3.0‰ and +0,4‰ for the each fraction. The result clearly indicated that gas evolution method generates isotopically lighter carbon at the beginning of the purging process and heavier isotopes at the end. However, this isotope fractionation effect could be neglected by the almost complete recovery of carbonates.

• Fire Science and Engineering
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• v.24 no.2
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• pp.82-88
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• 2010

In this study, we have performed several tests for composite plastic materials to be applied on interior materials of a vehicle to identify their combustion characteristics using cone calorimeter, smoke density chamber and toxicity index chamber. We have prepared a total of 12 samples for 4 major parts of a vehicle wherein each major part has 3 different materials. The results of cone calorimeter test showed ignition time of PVC sheet and PVC leather were 2s. The 8 samples showed under less than 10s of ignition time. The sample comprising Nylon and PE had the biggest maximum heat release rate of 635 $kW/m^2$. The sample comprising Rubber showed the smallest maximum heat release rate but with the biggest total heat release. The results of smoke density chamber test showed the sample that is made up with Rubber had the biggest specific optical smoke density. The sample comprising PVC leather and PUR showed the biggest VOF4 which enables the initial smoke production. The results of toxicity index test showed that all samples contained carbon dioxide content exceeding its lethal concentration. The sample comprising PVC showed high content of hydrogen chloride and hydrogen bromide. The PVC sheet showed the biggest toxicity index calculated by using lethal concentration and test results. Toxicity index of all sample wes over 1.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.321-328
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• 2019

The detection performances of the NaI(Tl), $LaBr_3$(Ce) and $CeBr_3$ scintillation detectors, which can be used to rapidly evaluate the major artificial radionuclides deposited on the soil surface in a nuclear accident or radiological emergency, were compared. Detection performance was assessed by calculating the minimum detectable activity (MDA). The detection efficiency of each detector for artificial radionuclides was semi-empirically determined using mathematical modelling and point-like sources having certified radioactivity. The background gamma-ray energy spectrum for MDA evaluation was obtained from relatively wide and flat grassland, and the MDA values of each detector for the major artificial radionuclides that could be released in nuclear accidents were calculated. As a result, the relative MDA values of each detector regarding surface deposition distribution at normal environmental radiation level were evaluated as high in the order of the NaI(Tl), $LaBr_3$(Ce), and $CeBr_3$ detectors. These results were compared based on each detector's intrinsic and measurement environment background, detection efficiency, and energy resolution for the gamma-ray energy region of the radionuclide of interest.

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.194-196
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• 2002

지하수의 오염을 막기 위하여 음식물의 매립은 법적 제재를 받게 되었고, 따라서 음식물을 퇴비나 사료로 사용할 수 있는 시스템을 갖추는 것이 바람직하다. 이러한 필요성에 힘입어 음식물 쓰레기 처리용 원적외선 가열기를 법랑 및 전열선을 사용하여 설계(특허출원 출원번호 : 10-2002-0017492)하였고, 가열의 효과를 돕기 위한 원적외선 발열 교반기도 설계하였다. (실용신안 출원 출원번호 : 20-2002-0009572). 또한 간이 원적외선 발열기를 통한 색상차에 의한 원적외선 방사효율의 차이를 알아보았다.