• 대한수의학회지
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• 제43권3호
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• pp.507-516
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• 2003

This study was performed to clarify the induction possibility of anaphylactoid reactions by the administration with the heartworm extracts, and, if any, to elucidate different virulences in terms of the protein concentrdtions and sexes of Dirofilaria immitis. Twenty three clinically healthy D. immitis-free adult dogs were used in the present study. The experimental animals were divided into 5 groups. Group A (5 heads) was administered with an female heartworm extract containing 0.1 g/dl protein concentration. Group B (4 heads) was administered with an male heartworm extract containing 0.1g/dl protein concentration. Group C (5 heads) was administered with an female heartworm extract containing 0.2 g/dl protein concentration. Group D (4 heads) was administered with an male heartworm extract containing 0.2 g/dl protein concentration. Group E (5 heads) was administered with an female heartworm extract containing 0.4 g/dl protein concentration. The changes of clinical symptoms and vital signs (body temperature, heart rate and respiration rate) were examined before and 5 minutes, 15 minutes, 30 minutes, 1 hour, 2 hours and 24 hours after injection with the extracts, respectively. In addition, the changes of hematological values (RBC, PCV and total leukocytes counts), serum chemical values (ALP and CK) were determined. It was considered that heartworm extract could induce anaphylactoid reaction and adult female heartworm extract was more affective than those of adult male heartworm extract in the changes of clinical symptoms, vital signs, hematological values and serum chemical values.

• 폴리머
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• 제31권1호
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• pp.8-13
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• 2007

나일론 6/poly(acrylonitrile-co-butadiene-co--styrene) (ABS) 블렌드의 단점을 해결하기 위해 ABS의 고무상인 폴리부타디엔 대신 폴리(부틸 아크릴레이트)를 고무상으로 포함하고 있는 poly(acrylonitrile-co-styrene-co-acrylic rubber) (ASA)를 사용하여 새로운 나일론/ASA 블렌드를 실험하였다. 고충격성을 갖는 블렌드 제조를 위하여 상용화제로 무수 말레산을 25 wt% 포함한 poly(styrene-co-maleic anhydride) (SMA)와 이를 3 wt% 이하 포함한 poly(styrene-co-acrylonitrile-co-maleic anhydride) (SANMA)를 사용하여 블렌드를 제조하였다. 나일론/ASA 블렌드에서 상용화제의 함량에 따른 물성 변화는 나일론/ABS 블렌드와 유사한 경향을 나타내었다. 블렌드 내의 고무 함량이 20 wt% 이상일 때 안정된 물성의 고충격 블렌드가 제조되었다. 블렌드를 사출 성형 온도에서 사출 성형기 내에 체류시킨 후 제조한 시편의 충격 강도를 시험한 결과 SMA를 상용화제로 사용한 경우 충격 강도의 감소가 관찰된 반면 SANMA를 상용화제로 사용한 블렌드에서는 충격 강도의 변화가 거의 없었다.

• 한국조명전기설비학회지:조명전기설비
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• 제1권2호
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• pp.74-81
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• 1987

고분자 절연재료에 전하주입시 발생하는 캐리어 트랩현상은 재료의 절연성을 저하시키는데 중요한 영향을 미치는 것으로 알려져 있다. 따라서 본 연구에서는 절연재료의 전기적 특성을 개선한다는 측면에서 캐리어의 거동을 파악하기 위해 내열성이 폴리프로필렌보다 우수한 이축 연신된 폴리프로필렌 필름(두께 $50\mu\textrm{m}$)을 선정하여 전계변화에 따른 열자격전류 스펙트라를 분석 검토하였다. 온도범위 303~413[K]와 전계범위 2~80[㎹/m]에서 열자격 전류의 변화를 살펴본 결과 전계 12[㎹/m]이하에서는 전하주입의 효과가 관찰되지 않았으나 전계가 점점 높아지면 트랩된 공간전하와 전극으로부터 주입된 공간전하가 형성되어 Hetero 및 Homo성 열자격전류 스펙트라가 나타나며 이는 결국 절연파괴를 야기시키는 것으로 예측되어진다. 또한 이축 연신된 시료가 미연신 재료보다 우수한 절연특성을 가지고 있음을 확인 할 수 있었다.

• 대한기계학회논문집B
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• 제23권9호
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• pp.1151-1162
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• 1999

The effects of radial heat and $H_2O$ diffusion on the evolution of silica particles in coflow diffusion flames have been studied experimentally. The evolution of silica aggregate particles in coflow diffusion flames has been measured experimentally using light scattering and thermophoretic sampling techniques. The measurements of scattering cross section from $90^{\circ}$ light scattering have been utilized to calculate the aggregate number density and volume fraction using with combination of measuring the particle size and morphology through the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh-Debye-Gans and Mie theory for fractal aggregates and spherical particles, respectively. Flame temperatures and volumetric differential scattering cross sections have been measured for different flame conditions such as inert gas species, $H_2$ flow rates, and burner injection configurations to examine the relation between the formation of particles and radial $H_2O$ diffusion. The comparisons of oxidation and flame hydrolysis have also been made for various $H_2$ flow rates using $N_2$ or $O_2$ as a carrier gas. Results indicate that the role of oxidation becomes dominant as both carrier gas($O_2$) and $H_2$ flow rates increases since the radial heat diffusion precedes $H_2O$ diffusion in coflow flames used in this study. The effect of carrier gas flow rates on the evolution of silica particles have also been studied. When using $N_2$ as a carrier gas, the particle volume fraction has a maximum at a certain carrier gas flow rate and as the flow rate is further increased, the hydrolysis reaction Is delayed and the spherical particles finally evolves into fractal aggregates due to decreased flame temperature and residence time.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.201.2-201.2
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• 2011

A water-source heat pump system has been developed for cooling and heating of a green house on the waterfront in Jinju. In order to supply a heat source/sink of water in alluvium aquifer to the heat pump system, the riverbank filtration facility (two pumping wells and one recharge well) for water intake and injection has been constructed. To pump and recharge water sufficiently, the geometric design such as depth and diameter for the wells have been completed, and details of the well such as slot size and length of the screen and filter pack size have been designed based on the practical and theoretical design method including D30 technique. For the investigation of the hydrogeological characteristics, step-drawdown test, long-term pumping test, and recovery test have been carried out for two developed pumping wells. Step-drawdown test has been performed on 4 step flowrates of 150, 300, 450, $600m^3$/day for 1 hour, and long-term pumping test on flowrate of $500m^3$/day for 24 hours, and recovery test for 6 hours. Since the underground water filtrated by riverbank is flowing smoothly into the well, the water level goes down slightly for the long-term test. Consequently, the stable pumping flowrate for two pumping well has been predicted at least over $1,647m^3$/day which is larger than the flowrate of $1,000m^3$/day for a 60 RT heat pump system.

• 한국대기환경학회지
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• 제32권5호
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• pp.526-535
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• 2016

Recently, fine dust in atmosphere have been considerably issued as a harmful element for human. Nitrogen oxide ($NO_x$) exhausted from diesel engines and power plants has been disclosed as a main source of secondary production of fine dust. In order to prevent exhausting these nitrogenous compounds into atmosphere, a treatment system with selective catalytic reduction (SCR) catalyst with ammonia as a reductant has been used in various industries. Urea solution has been widely studied to supply ammonia into a SCR catalytic reactor, safely. However, the conversion of urea solution to ammonia has several challenges, especially on a slow conversion velocity. In the present study, a fast urea conversion system including a plasma burner was suggested and designed to evaluate the performances of urea conversion and initial operation time. A designed lab-scale facility has a plasma burner, urea nozzle, mixer, and SCR catalyst which is for hydrolysis of isocyane. Flow rate of methane that is a fuel of the plasma burner was varied to control temperatures in the urea conversion facility. From experimental results, it is found that urea can be converted into ammonia using high temperature condition of above $400^{\circ}C$. In the designed test facility, it is found that ammonia can be produced within 1 min from urea injection and the result shows prospect commercialization of proposed technology in the SCR facilities.

• 한국자동차공학회논문집
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• 제20권4호
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• pp.125-132
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• 2012

Urea-SCR system, which converts nitrogen oxides to nitrogen and water in the presence of a reducing agent, usually AdBlue urea solution, is known as one of the powerful NOx reduction systems for mobile as well as stationary applications. For its consistent and reliable operation in mobile applications, such various problems as transient injection, ammonia slip, and freezing in cold weather have to be resolved. In this work, therefore, numerical study on three-dimensional unsteady heating problems were analyzed to understand the melting and heat transfer characteristics such as urea liquid volume fraction, temperature profiles and generated natural convection behavior in urea solution by using the commercial software Fluent 6.3. After validating by comparing numerical and experimental data with pure gallium melting phenomena, numerical experiment for urea melting is conducted with three different coolant heating models named CH1, 2, and 3, respectively. Finally, it can be found that the CH3 model, in which more coolant is concentrated on the lower part of the urea tank, has relatively better melting capability than others in terms of urea quantity of $1{\ell}$ for start-up schedule.

• The Korean Journal of Pain
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• 제14권2호
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• pp.199-206
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• 2001

Background: The lumbar sympathetic ganglia are variable in both position and numbers. The aim of this study was to detect the appropriate lumbar vertebral level where the lumbar sympathetic ganglia primarily aggregate. Methods: Forty patients comprising of hyperhidrosis (26 cases), complex regional pain syndrome (10 cases), peripheral artery occlusion disease (3 cases) and postherpetic neuralgia (1 case) underwent lumbar sympathetic block. We randomly selected one of two (L2 or L3) levels and the L4 level. The position of the needle tip and distribution of dye was verified by injection of a mixture of radio-opaque dye (1.5 ml) and 4% lidocaine (1.5 ml) and subsequently confirmed by L-spine anteroposterior and a lateral view X-ray. We considered the response positive when the skin temperature increased more than $1^{\circ}C$ in 5 min. Results: In general, the positive response ratio was greater when the needle tip located at the L2 or L4 level vice L3 and when the drug was distributed on the lower half of the L4 body and in the L4/5 intervertebral disc space. In a right side block, the positive response ratio was greater when the drug was distributed on the lower half of the L4 body and in the L4/5 intervertebral disc space, although in a left side block there was no significant difference seen between the levels. The complications of the neurolytic block were alcohol neuritis (7.5%) and hypoesthesia (5%) on the L1 or L2 dermatome. Conclusions: The best effect with least chance of complication may be induced by spreading the drug on the lower half of the L4 body and/or into the L4/5 intervertebral disc space by placing the needle tip on the L4 body.

• Journal of Pharmaceutical Investigation
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• 제23권3호
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• pp.139-144
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• 1993

Microencapsulation of acyclovir, an effective antiviral agent which acts as a specific inhibitor of herpes DNA polymerase, by carbopol-gelatin complex coacervation has been carried out to develop an oral controlled release preparation, which could improve the absorption characteristics in GI tract. After dissolving carbopol and gelatin separately in distilled water at $40^{\circ}C$, gelatin solution was mixed with carbopol solution while stirring at the same temperature. The pH of the mixture was lowered gradually by dropwise addition of 10% HCI with continuous stirring, and then, at pH 3.5, positively charged gelatin molecules were attracted to negatively charged carbopol. These coacervation processes were observed by optical microscopy during preparation. Plasma concentrations of acyclovir in rats after an oral administration of microcapsule suspension were assayed by HPLC, and pharmacokinetic parameters were calculated based on the model-independent analyses. Two standard formulations, oral solution and intravenous bolus injection, were used as references to compare the bioavailability. It has been revealed that $C_{max}$, $T_{max}$, and MRT of microcapsule suspension were greater than those of oral solution, which results in about two-fold increases in bioavailability. Therefore, in conclusion, the carbopol-gelatin microcapsule of acyclovir might be evaluated as an effective oral controlled release preparation which could increase the bioavailability of acyclovir.

• The Korean Journal of Physiology and Pharmacology
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• 제3권4호
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• pp.383-391
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• 1999

This study was carried out to determine whether the effects of an ${\alpha}_2-adrenoceptor$ agonist, clonidine, on mean arterial pressure (MAP) and heart rate (HR) are influenced by mild hypothermia. Experiments were performed in respiration-controlled and spontaneously breathing pentobarbital-anesthetized rats. Rectal temperature was maintained at $37.5{\pm}0.3^{circ}C$ for normothermic groups or at $35.2{\pm}0.3^{circ}C$ for mild hypothermic groups. Intravenous injection of clonidine (1 and 2 ${\mu}g/kg)$ produced depressor and bradycardic responses in spontaneously breathing rats under both normothermic and mild hypothermic condition: a decrease in MAP was not altered but bradycardic response was significantly augmented in the mild hypothermic group as compared with the normothermic group. Under the respiration-controlled condition, the hypotensive effect of clonidine $(2\;{\mu}g/kg)$ was reduced, whereas the bradycardic effect was increased in mild hypothermic rats as compared with normothermic rats. Both hypotensive and bradycardic effects of clondine $(2\;{\mu}g/kg)$ were blocked by pretreatment with an ${\alpha}_2-adrenoceptor$ antagonist, yohimbine (0.5 mg/kg), in both thermal conditions. Yohimbine (0.5 mg/kg, i.v.) alone produced signifcantly an increase in heart rate in the mild hypothermic group than in the normothermic group. Pretreatment with a muscarinic receptor antagonist, atropine methylnitrate (1 mg/kg, i.v.), attenuated the bradycardic effect of clonidine in the mild hypothermic group but not in the normothermic group. These results suggest that clonidine- induced bradycardia is amplified by mild hypothermia probably through an increased parasympathetic activity.