• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.38-47
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• 1996

Sectional analysis program for plane strain or axisymmetric geometry of aluminum alloy sheet metals was developed. For modeling the anomalous behavior of aluminum alloy, Barlat's strain rate potential and Hill's 1990 non-quadratic yield theory arranged under the plane stress assumption were employed. 2-D rigid-viscoplastic FEM formulation based on the bending-augmented membrane theory was derived, solving simultaneously force equilibrium as well as non-penetration condition. Isotropic hardening law was also assumed for yielding behavior. To verify the validity and availability of the developed program, 2-D stretch/draw forming process for plane strain geometry and cylindrical cup deep drawing process for axisymmetric geometry were simulated.

• 한국임상수의학회지
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• 제12권1호
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• pp.853-860
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• 1995

Two cases of guttural pouch mycosis in race horses were observed for clinical and pathological aspects of the disease to investigate etiology and pathogenesis of dysphagia and epistaxis of the horse. In case 1 showing prolonged dysphagic sign a diphtheritic membrane was confined to the guttural pouch involved with neuritis of the glossopharyngeal nerve due to fungal penetration. The other horse showing fatal recurrent epistaxis had lesion of mycetoma invading the internal carotid artery to provoke erosion of the artery. An Aspergillosis sp. was isolated from the guttural pouches of the two horses and identified as A nidulans.

• 대한화장품학회지
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• 제31권1호
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• pp.43-49
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• 2005

최근, 민감성 피부가 증가함에 따라 화장품의 안전성이 매우 중요시되고 있으며, 특히 방부제는 화장품 사용에 따른 부작용을 일으킬 수 있는 주요 자극원의 하나로 알려져 있다. 하지만, 방부제의 세포 독성 피부 투과, 유/수 분배, 항균력 비교 및 이를 통한 피부 자극과의 상관성 분석에 관한 연구는 전무한 실정이다. 본 연구의 목적은 상기의 여러 factor를 고려하여 화장품에서 빈번히 사용되고 있는 방부제의 하나인 phenoxyethanol을 이용한 저자극 방부시스템 개발에 관한 것이다. MTT assay를 통하여 human norm기 fibroblast cell에 대한 독성을 평가해 본 결과, 세포 독성은 propylparaben>butylparaben>ethylparaben>methylparaben>triciosan>phenoxyethanol 순으로 확인되어 phenoxyethanol이 다른 방부제에 비해 낮은 세포 독성을 나타낸 반면, 피부 일차자극을 알아보기 위하여 수행한 인체 첩포시험에서는 triclosan, methylparaben에 비해 높은 피부 자극을 나타내었다. 5 ${\~}$ 8 주령의 웅성 무모생쥐의 피부를 적출하여 in vitro Franz diffusion cell system을 이용한 방부제의 피부 투과도를 측정하여 본 결과, 피부 투과도는 phenoxyethanol > methylparaben > ethylparaben > propylparaben > butylparaben > triclosan 순으로 확인되어 세포 독성이 낮은 phenoxyethanol의 높은 피부 자극이 높은 피부 투과도와 연관성이 큰 것을 확인하였다. 따라서, 본 연구에서는 비교적 독성이 낮은 phenoxyethanol의 피부 투과도를 감소시킬 수 있는 방법을 찾고자 하였으며, 연구 결과, 제형내 polarity가 낮은 oil을 사용할 경우 phenoxyethanol의 피부 투과가 현격히 감소하며, 피부 자극도 감소함을 알 수 있었다. Oil polarity에 따른 Phenoxyethanol의 유/수 분배 측정 결과, Polarity가 낮은 oil에서는 $70\%$ 이상의 Phenoxyethanol이 수상에 존재한 반면, polarity가 높은 oil에서는 약 $70 {\~} 90\%$의 phenoxyethanol이 유상에 존재하였다. 또한, 미생물에 대한 항균력도 phenoxyethanol이 수상에 많이 존재할수록 증가하는 경향을 나타내었다. 따라서, 제형 내 oil tomposition을 변화시킴으로써 phenoxyethanol의 사용량을 줄일 수 있을 뿐만 아니라, 피부 투과를 감소시켜 보다 피부 자극이 적은 저자극 방부시스템 개발이 가능하리라 보여 진다.

• 한국수소및신에너지학회논문집
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• 제24권3호
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• pp.216-222
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• 2013

Durability characteristics of Gas Diffusion Layer(GDL) is one of the important issues for accomplishing commercialization of Proton Exchange Membrane Fuel Cell(PEMFC). It is strongly related to the performances of PEMFC because one of the main functions of GDL is to work as a path of fuel, air and water. When the GDL does not work on their proposed functions due to the degradation of durability, mass transfer in PEMFC is disturbed and it might cause the flooding phenomenon. Thus, investigating the durability of GDL is important and understanding the GDL degradation process is needed. In this study, electrochemical degradation with carbon corrosion is introduced. The carbon corrosion experiment is carried out with GDLs which have different MPL penetration thicknesses. After the experiment, the amount of degradation of GDL is measured with various properties of GDL such as weight, thickness and performance of the PEMFC. The degraded GDL shows loss of their properties.

• Biomolecules & Therapeutics
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• 제19권3호
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• pp.357-363
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• 2011

In relieving local pains, ropivacaine has been widely used. In case of their application such as ointments and creams, it is difficult to expect their effects for a significant period of time, because they are easily removed by wetting, movement and contacting. Therefore, the new formulations that have suitable bioadhesion were needed to enhance local anesthetic effects. The effect of drug concentration and temperature on drug release was studied from the prepared 1.5% Carboxymethyl cellulose (CMC) (150MC) gels using synthetic cellulose membrane at $37{\pm}0.5^{\circ}C$. As the drug concentration and temperature increased, the drug release increased. A linear relationship was observed between the logarithm of the permeability coefficient and the reciprocal temperature. The activation energy of drug permeation was 3.16 kcal/mol for a 1.5% loading dose. To increase the skin permeation of ropivacaine from CMC gel, enhancers such as saturated and unsaturated fatty acids, pyrrolidones, propylene glycol derivatives, glycerides, and non-ionic surfactants were incorporated into the ropivacaine-CMC gels. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the highest enhancing effects. For the efficacy study, the anesthetic action of the formulated ropivacaine gel containing an enhancer and vasoconstrictor was evaluated with the tail-flick analgesimeter. According to the rat tail-flick test, 1.5% drug gels containing polyoxyethylene 2-oleyl ether and tetrahydrozoline showed the best prolonged local analgesic effects. In conclusion, the enhanced local anesthetic gels containing penetration enhancer and vasoconstrictor could be developed using the bioadhesive polymer.

• 말소리와 음성과학
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• 제10권4호
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• pp.147-154
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• 2018

Wet voice quality (WVQ) is a characteristic that appears after swallowing. Although the concept is accepted by many clinicians worldwide, it is nevertheless ambiguous. In this study, we investigated WVQ in patients with swallowing disorders using acoustic analysis. A total of 106 patients diagnosed with penetration-aspiration by the videofluoroscopic swallowing study (VFSS) were recruited. A voice recording of vowel /a/ was conducted before and after the VFSS, and an acoustic analysis was then performed using PRAAT. Voice after VFSS was used for a perceptual judgment and divided into two groups: the Wet group (48 patients) and the Non-wet group (58 patients). At the post-VFSS stage, the two groups displayed significant differences in many acoustic parameters including F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP. The parameter affecting judging wetness resulted into Jitter and NHR by the logistic regression test. At the pre-VFSS stage, the two groups differed significantly in many acoustic parameters including Intensity, Jitter, RAP, Shimmer, NHR, FUF, DVB, and CPP. Both pre-and post-VFSS, the mean values of all significant parameters, except Intensity, HNR, and CPP, were higher in the Wet group. According to pre-and post-VFSS, the two groups displayed interactions in many parameters (Intensity, F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP). In particular, Intensity increased in both groups after the VFSS, although the increase in the Non-wet group was greater. Based on these results, it was conjectured that the WVQ after swallowing resulted from the secretion effect of the mucous membrane due to the dry laryngeal characteristic of elderly patients, rather than aspiration resulting in food on the vocal cords.

• 농약과학회지
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• 제6권1호
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• pp.16-24
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• 2002

농약의 식물 엽면 침투성에 관하여 보고한 국내외 논문을 조사하여 최근에 빈번하게 사용되고 있는 침투율 측정법과, 계면활성제에 의해서 유도되는 농약의 엽면 침투기작에 관한 연구 동향을 고찰하였다. 농약의 식물 엽면 침투성 연구에는 생물검정법, 식물 잎이나 cuticular membrane을 이용하는 방사능 추적 기술이 주로 이용되고 있다. 가장 최근에는 수용성 색소 Congo Red를 추적물질로 이용하는 새로운 침투율 측정법이 제안되었다. 농약의 엽면 침투에 있어서 최대의 장벽은 epicuticular wax와 cuticular wax를 포함하는 잎 표면의 왁스층이며, 일부 연구자들은 이를 limiting skin이라 부르기도 한다. 농약의 몰부피(molar volume), 수용해도 및 분배계수 등의 이화학적 성질은 식물 엽면 침투성에 영향을 미치지만 제한적인 상관관계를 나타낼 뿐이며, 일반화할 수 있는 어떠한 상관관계도 아직 발견되지 않았다. Polyoxyethylene을 친수기로 가지는 지방족 알콜 계면활성제들은 많은 농약에 대하여 좋은 침투성 증진제로 알려져 있다. 침투성 증진제로 사용되는 계면활성제가 농약의 엽면 침투성을 증진하는 데에는 계면활성, 가용화 능력, 흡습성 및 미셀생성임계농도 등 계면활성제 고유의 성질이 크게 관여하는 것 같지는 않다. 최근의 연구에서 침투성 증진 효과가 큰 계면활성제는 식물의 왁스층에 쉽게 흡수되어 가역적으로 왁스층의 유동성을 증가시키는 가소제 역할(plasticizing effect)을 한다는 것이 밝혀졌다. 계면활성제가 왁스층에 먼저 침투하면 wax층의 유동성이 증가하고, 이로 인하여 wax층 내에서 농약의 이동성과 분배계수가 달라짐으로써 농약의 엽면 침투 속도가 변화한다는 것이다. 그러나 계면활성제의 친유기 부분인 지방족 알콜의 탄소수와 친수기의 ethylene oxide 부가중합도가 농약의 침투성 증진에서 어떠한 역할을 하는지는 상세히 밝혀져 있지 않다. 다만 계면활성제 자체의 엽면 침투 속도가 농약의 침투속도와 깊은 관련이 있을 것으로 추정되고 있다.

• Parasites, Hosts and Diseases
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• 제28권4호
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• pp.197-206
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• 1990

MDCK세포간에 형성된 tight junction이 Toxoplasma gondii이 숙주세포 침투에 미치는 영향에 대하여 고찰 하기 위해 여러 조건의 세포배양을 시행하였다. MDCK세포를 25-well배양기 내의 18-mm cover glass에 $1{\times}10^5,{\;}3{\times}10^5{\;}및{\;}5{\times}10^5$ 개로 분주한 후 배양 1, 2, 3 및 4일에 다수의 Toxoplasma를 첨가하여 1시간 동안 배양한 다음 Giemsa 용액으로 염색한 후 관찰하였을 때, 각 실험군에서 침투한 원충의 숫자는 숙주세포가 포화밀도를 이루면서 급격히 감소하였다. 배양액 내의 calcium 농도를 일반적인 1.8mM에서 $5{\;}{\mu}M$로 낮추어 포화밀도의 MDCK 세포간에 tight junction 형성을 억제하였을 때, 원충의 침투가 약 2배 증가하였으며(p<0.05) 포화밀도 이전의 배양에서는 원충의 침투가 감소하였다. Trypsin-EDTA를 처리하여 포화밀도의 배양에서 tight junction을 소화 시킨 경우, 원충의 침투가 약 2.5배 증가하였으며 (p<0.05) 포화밀도 이전의 배양에서는 급격히 감소하였다. 이상의 결과들로 볼 때, 포화밀도의 MDCK세포간에 형성된 tight junction이 Toxoplasma의 침투를 억제하는 것을 알 수 있었다. 이는 Toxoplasma가 숙주세포로 침투할 때 숙주세포의 막구조에 대한 특이성이 있음을 시사 하며, 상피세포에서는 tight junction 위의 막(apical membrane) 보다 옆 및 아래의 막(basolateral membrane)상의 구조를 이용하는 것으로 추정되었다.

• BMB Reports
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• 제33권3호
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• pp.221-227
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• 2000

The distribution of barbiturates in the model membranes of total lipids (SPMVTL) and total phospholipids (SPMVPL) extracted from synaptosomal plasma membrane vesicles was determined by employing a fluorescent probe technique. The two fluorescent probes 2-(9-anthroyl)stearic acid and 12-(9-anthroyl)stearic acid were utilized as probes for the surface and the hydrocarbon interior of the outer monolayer of the SPMVTL and SPMVPL, respectively. The Stern-Volmer equation of fluorescent quenching was modified to calculate the relative distribution. The analysis of preferential quenching of these probes by barbiturates indicates that pentobarbital, hexobarbital, amobarbital and phenobarbital are predominantly distributed on the surface area, while thiopental sodium has an accessibility to the hydrocarbon interior of the outer monolayer of the SPMVTL and SPMVPL. From these results, it is strongly suggested that the more effective penetration into the hydrocarbon interior of the outer monolayer of the membrane lipid bilayer could result in a higher general anesthetic activity.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.15-22
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• 1997

The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.