Silwet L-77이 포함된 Polydimethylsiloxane(PDMS) 마이크로 채널의 유동 길이 모델링

이봄이(Bom-yee Lee),이봉기(Bong-Kee Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

In the present study, simple models to predict a capillary-driven flow length in a surfactant-added poly(dimethylsiloxane) (PDMS) rectangular microchannel were proposed. Due to a hydrophobic nature of PDMS, it is difficult to transport water in a conventional PDMS microchannel by means of a capillary force only. In this regard, microchannels with a hydrophilic surface were fabricated using the surfactant-added PDMS. By measuring the contact angle change on the surfactant-added PDMS surface, the behavior was investigated to establish a simple model. In order to predict the filling length induced by the capillary force, the Washburn equation was modified in the present study. From the investigation, it was found that the initial rate-of-change of the contact angle affected the filling length. The simple models for three representative cases were developed, which can be a useful tool in designing microfluidic manufacturing techniques including MIMIC.

분지형 폴리카보네이트의 분자량 조절 및 유변학적 특성 연구

이봄이 ( Bom Yi Lee ),프러산터 ( Prashanta Dahal ),김희승 ( Hee Seung Kim ),유승윤 ( Seung Yoon Yoo ),김연철 ( Youn Cheol Kim ) 한국공업화학회 2012 공업화학 Vol.23 No.4

말단캡핑제(end capping agent) 4종류와 함량별로 분지형 폴리카보네이트를 용융중합법으로 제조하였다. 합성된 분지 형 폴리카보네이트의 화학구조는 FT-IR과 1 H-NMR 스펙트럼을 이용하여 확인하였으며, 말단캡핑제의 반응여부는 FT-IR 스펙트럼의 수산기(3500 cm -1) 존재여부로 확인하였다. 평균 분자량 및 분자량 분포도, 유리전이 온도 및 분해온 도는 GPC, DSC와 TGA를 이용하여 측정하였다. 말단캡핑제의 화학구조에 따라 평균 분자량이 증가 또는 감소를 나타내었으며, 말단캡핑제로 4-tert-butylphenol (TBP)이 사용되었을 때 최적의 분자량 조절 결과를 나타내었다. 말단캡핑제 의 함량이 증가할수록 평균분자량은 감소하였고, 4-tert-butylphenol이 0.05 mol%가 첨가될 때 폴리카보네이트의 대형 사출물 가공에 적합한 20000 정도의 수평균분자량을 나타내었다. 분지형 폴리카보네이트의 용융점도는 분자량이 감 소할수록 감소하였으며, shear thinning effect에는 큰 영향을 주지 않음을 확인하였다. Branched polycarbonates (B-PCs) were synthesized using melt polymerization method with four different end capping agents and vaying concentrations. The chemical structure of the synthesized PC was determined by FT-IR and 1 H-NMR spectroscopy, and the reaction of the end capping agent was confirmed by the existence of hydroxy group in FT-IR spectrum. The average molecular weight and distribution, glass transition and degradation temperatures were determined by GPC, DSC and TGA. The average molecular weight changed with the chemical structure of end capping agent, and 4-tert-butylphenol was estimated as the optimum end capping agent. The average molecular weights of B-PCs decreased with the increase of the concentration of the agent, the number average molecular weight represented 20000 when 0.05 mol% of 4-tert-butylphenol was added to B-PCs. The melt viscosities of the B-PCs decreased with the decrease of the molecular weight of B-PCs, and adding of the agent was not effected to shear thinning tendency.

나일론66/실리케이트 복합체의 충격특성 개선 연구

이봄이(Lee, Bom Yi),김연철(Kim, Youn-Cheol) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.7

나일론66/실리케이트 복합체를 자동차 부품 소재로 적용하기 위해서 충격특성 개선에 대한 연구가 요구된다. 이축압 출기(twin screw extruder)를 이용하여 나일론66/실리케이트 복합체를 실란계열의 γ-APS로 처리한 실리케이트 사용과 MAH가 그라프트된 옥텐계 α 올레핀을 첨가한 경우로 하여 제조하였다. 실란처리된 실리케이트의 화학구조는 적외선 분광 기(FT-IR)을 이용하여 측정하였고, 나일론66/실리케이트 복합체의 열적특성, 실리케이트 삽입여부 및 아이조드 충격강도를 DSC, TGA, XRD, 그리고 Izod 시험기를 이용하여 분석하였다. 실란계열로 처리된 실리케이트의 화학반응여부는 표면 수산 기 피이크의 감소로부터 확인하였다. 복합체의 분해온도에는 큰 차이를 보이지 않았지만 결정화온도와 결정화도는 약간 증 가하였다. 이는 사용한 첨가제들이 나일론 66에 불균일 핵제로의 역할을 했기 때문으로 추측된다. 나일론66/실리케이트 복합 체의 아이조드 충격특성 측정결과 실란으로 처리된 실리케이트를 사용한 경우 약 24% 정도의 충격강도 개선효과를 보여주었다. A study of the improvement in the impact strength is required to apply Nylon 66/silicate composites as an automobile material. Nylon 66/silicate composites were prepared using a twin screw extruder in case of a silicate treatment by γ-APS (S-silicate) and the addition of an octene α olefin grafted by maleic anhydride (PE-g-MAH). The chemical structure of the silane treated silicate was measured by Fourier transform infra-red (FT-IR) spectroscopy. The chemical reaction was confirmed by the decrease in the FT-IR intensity of the OH stretching vibration. The thermal properties, intercalation structure, and Izod impact strength were measured by DSC, TGA, XRD, and Izod impact tester. There was no significant effect on the degradation temperature of the Nylon66/silicate composite, but the crystallization temperature and crystallinity increased slightly in the case of the Nylon66/silicate composites. This suggests that the additives act as heterogeneous nuclei on the Nylon 66 matrix. The Izod impact test indicated that S-silicate enhanced the impact performance by up to 24%.

말단캡핑제를 이용한 폴리카보네이트의 분자량 특성 조절

이봄이(Lee, Bom Yi),김연철(Kim, Youn-Cheol) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.3

말단캡핑제(end capping agent) 6종류에 대해 폴리카보네이트를 용융중합법으로 제조하였다. 합성된 폴리카보 네이트의 화학구조는 FT-IR 스펙트럼을 이용하여 확인하였다. 평균분자량 및 분자량분포도, 유리전이 온도 및 열분해 온도는 GPC, DSC와 TGA를 이용하여 측정하였다. 말단캡핑제의 화학구조에 따라 평균분자량이 증가 또는 감소를 나 타내었으며, 말단캡핑제로 4-tert-butylphenol (TBP)이 사용되었을 때 최적의 분자량 조절 결과를 나타내었다. 말단캡핑 제의 함량이 증가할수록 평균분자량은 감소하였고, 4-tert-butylphenol이 0.05 - 0.1 mol%가 첨가될 때 폴리카보네이트 의 대형 사출물 가공에 적합한 20,000 - 30,000 정도의 수평균분자량을 나타내었다. 폴리카보네이트의 용융점도와 유 리전이온도는 분자량이 감소할수록 감소하였다. 말단캡핑제의 투입방법 변경은 PC의 분자량분포도에 영향을 주었고, power law index의 감소를 보여주었다. Polycarbonates (PCs) with six different end capping agents were synthesized from melt polymerization. Chemical structure of the synthesized PC was determined by FT-IR spectroscopy. The average molecular weight and distribution, glass transition and thermal degradation temperatures were determined by GPC, DSC and TGA. Average molecular weight changed with the chemical structure of end capping agent, and 4-tert-butylphenol was estimated as the optimum end capping agent. The average molecular weights of PCs decreased with the concentration of the agent, the number average molecular weight was observed as 20,000 - 30,000 when 0.05– 0.15 mol% of 4-tert-butylphenol added in PCs. The melt viscosities and glass transition temperature of the PCs decreased with molecular weight. The change for adding method of the agent affected on both the molecular weight distribution and decrease in power law index.

Silwet L-77 이 포함된 Polydimethylsiloxane(PDMS) 마이크로 채널의 유동 길이 모델링

이봄이(Bom-yee Lee),이봉기(Bong-Kee Lee) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.8

본 연구에서는 계면활성제를 첨가한 사각 PDMS(polydimethylsiloxane) 마이크로 채널에서의 모세관 흐름에 의한 충전 길이를 예측하기 위한 모델들을 제안하였다. 일반적으로 PDMS 의 소수성 특성 때문에 모세관 힘만을 이용한 PDMS 마이크로 채널에서의 물의 이동에는 어려움이 따르게 된다. 따라서 본 연구에서는 계면활성제를 첨가하여 친수성을 가지는 PDMS 표면을 제작하고, 이 표면에서의 물의 접촉 각 변화 측정 및 단순 모델을 수립하였다. 또한 친수성 PDMS 마이크로 채널에서의 모세관 힘에 따른 충전 길이를 예측하기 위해서 Washburn 방정식을 바탕으로 한 단순 모델을 수립하였다. 그 결과 유체의 충전 길이는 접촉각의 초기변화속도의 영향을 받는 것을 확인할 수 있었다. 이를 바탕으로 대표적인 세 가지 경우에 대한 모델을 제안하였으며, 이들은 MIMIC(MIcroMolding In Capillaries)과 같은 마이크로 유체 기반의 생산공정의 설계와 개발에 유용하게 적용될 수 있을 것이다. In the present study, simple models were proposed to predict the capillary-driven flow length in a surfactantadded poly(dimethylsiloxane) (PDMS) rectangular microchannel. Owing to the hydrophobic nature of PDMS, it is difficult to transport water in a conventional PDMS microchannel by means of the capillary force alone. To overcome this problem, microchannels with a hydrophilic surface were fabricated using surfactant-added PDMS. By measuring the contact angle change on the surfactant-added PDMS surface, the behavior was investigated to establish a simple model. In order to predict the filling length induced by the capillary force, the Washburn equation was modified in the present study. From the investigation, it was found that the initial rate-of-change of the contact angle affected the filling length. Simple models were developed for three representative cases, and these can be useful tools in designing microfluidic manufacturing techniques including MIcroMolding In Capillaries (MIMIC).

신문(神門) 침 자극이 급성 코카인 투여로 인한 보행성 활동량과 뇌내 c-Fos 발현에 미치는 효과

이봄비 ( Bom Bi Lee ),심인섭 ( In Sup Shim ),양재하 ( CheHa Yang ),이학인 ( Hak In Lee ),함대현 ( Dae Hyun Hahm ),이혜정 ( Hae Jeong Lee ) 대한경락경혈학회 2002 Korean Journal of Acupuncture Vol.19 No.1

Substantial evidence suggests that behavioral and reinforcing effects of cocaine can be mediated by the mesolimbic dopaminergic system. Injections of cocaine can produce one of the immediate-early gene, c-fos expression in the brain and behavioral activation. Acupuncture as a therapeutic intervention is widely used for the treatment of many mental disorders such as drugs of abuse. In order to investigate whether acupuncture has an influence on cocaine-induced reinforcing and behavioral effects, we examined the effect of acupuncture on cocaine-induced locomotor activity and c-Fos expression in the nucleus accumbens and the striatum using Fos-like-immunoreactivity(FLI). Male SD rats received acupuncture for 1 min after injection of cocaine hydrochloride(1 mg/kg, i.v.). The employed acupuncture point, Shenmen(HT7), has been clinically used to treat mental and psychosomatic disorders. Injections of cocaine produced a marked increase in locomotor activity and FLI in the nucleus accumbens and the striatum. Acupuncture at HT7, but not at control points(PC6, TE4 or tail), significantly attenuated cocaine-induced increase in locomotor activity and Fos-like immunoreactivity. These results demonstrated that reduction in locomotor activity by acupuncture may be reflected by reduction of postsynaptic neuronal activity in the nucleus accumbens and the striatum. Our results suggest that acupuncture may have a therapeutic effect on cocaine addiction.

약침이 반복적인 코카인 투여로 인한 행동적 민감화 현상에 미치는 효과

이봄비,양재하,함대현,이혜정,심인섭,Lee, B.B,Yang, C.H.,Hahm, D.H.,Lee, H.J.,Shim, I.S. 대한약침학회 2004 Journal of pharmacopuncture Vol.7 No.1

Substantial evidence suggests that behavioral and reinforcing effects of cocaine can be mediated by the mesolimbic dopaminergic system. It has been shown that repeated injections of cocaine produce increase in locomotor activity, expression of the immediate-early gene, c-fos in the nucleus accumbens (NAc), which was one of the main dopaminergic terminal areas. Herbal-acupuncture as a therapeutic intervention has been widely used for the treatment of many functional disorders such as drug abuse. Coptidis Rhizoma (CR) and its main component, berberine (BER) were selected as herbal medicine of herbal-acupuncture. Both medicines have been known to have the therapeutic effect on the central nervous system. In order to investigate the effects of CR and BER herbalacupuncture at shenmen (HT7) point (CR/H and BER/H) on the cocaine-induced behavioral sensitization, the influence of CR/H and BER/H on repeated cocaine-induced locomotor activity, the change of c-Fos expression in the brain by immunohistochemistry were examined. Male SD rats were given CR/H (0.4mg/kg) and BER/H (0.1mg/kg) 30 min before daily injections of cocaine hydrochloride (15mg/kg. i.p.) 10 days. After 3 days withdrawal, rats received a challenge injection of cocaine (15mg/kg, i.p.). Systemic challenge with cocaine produced much larger increased locomotor activity, accumbal Fos-like immunoreactivity in the NAc. Pretreatment with CR/H and BER/H significantly inhibited cocaine-induced locomotor activity, the change of c-Fos expression in the rats. Our data demonstrated that the inhibitory effects of cocaine-induced behavioral sensitization by CR/H and BER/H were closely associated with the reduction of presynaptic dopamine release in the NAc. These results suggest that CR/H and BER/H can be effectively applied to cocaine addiction.

나일론66/유리섬유 복합체의 압출횟수에 따른 특성 연구

이봄이(Lee, Bom Yi),김연철(Kim, Youn-Cheol) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.6

나일론66/유리섬유 복합체의 경우 300 ℃ 이상의 고온에서 사출가공 될 때 물성 저하가 일어날 수 있어, 재이용시 열이력에 대한 체계적인 연구가 필요하다. 305/290/273/268/265/260 ℃ 온도조건의 이축압출기(twin screw extruder)를 이용 하여 나일론66/유리섬유 복합체의 압출시료를 압출횟수에 따라 제조하였다. 압출횟수에 따른 화학구조, 열적특성, 용융지수, 결정구조, 아이조드 충격강도 및 유변학적 특성을 FT-IR, 용융지수 측정기, DSC, TGA, XRD, Izod 시험기, 그리고 유변물성 측정기를 이용하여 분석하였다. 적외선분광 스펙트럼을 이용하여 확인한 결과 압출횟수에 따른 압출시편에서의 화학구조 변화는 확인되지 않았다. 압출횟수에 따라 분자량이 감소하는 것을 용융지수와 복소점도를 이용하여 확인하였다. 나일론66/ 유리섬유 복합체의 용융온도는 큰 변화가 없으나, 압출횟수 증가에 따라 분해온도가 20 ℃ 정도까지 감소하는 것을 DSC와 TGA를 이용하여 확인하였다. 압출시편의 아이조드 충격강도는 압출횟수가 증가함에 따라 감소하였다. 또한 나일론66/유리 섬유 복합체 압출시편의 G'-G" 곡선의 기울기나 형태가 변하지 않는 것으로부터 압출시편에 가교와 같은 구조변화가 크게 나타나지 않음을 알 수 있었다. Because the physical properties can be decreased when a Nylon 66/glass fiber composite is injected into a mold over 300 ℃, a systematic study of the thermal history in the case of re-use is needed. Nylon 66/glass fiber extrudates as a function of the extrusion number were prepared using a twin screw extruder at 305/290/273/268/265/260 ℃. The chemical structure, thermal properties, melt index, crystal structure, Izod impact strength, and rheological properties were measured by Fourier transform infra-red (FT-IR), melt indexer, DSC, TGA, XRD, Izod impact tester, and dynamic rheometer. The FT-IR spectra indicated that the number of extrusions did not affect the chemical structure. The decrease in molecular weight with increasing extrusion number was confirmed by the melt index and the complex viscosity of extrudates. Based on the DSC and TGA results, the thermal history had no effect on the melting temperature, regardless of the number of extrusions, but the degradation temperature decreased up to 20 ℃ with increasing extrusion number. The Izod impact strengths of the extrudates were found to decrease with increasing extrusion number. No structural change after extrusion was also confirmed because there was no change in the slope and shape of the G'-G" plot.

중풍 한방처방전의 효능비교 연구; 황련해독탕, 거풍지보단, 가미사물탕이 국소 전뇌허혈에 의한 학습과 기억에 미치는 효과

이봄비 ( Bom Bi Lee ),정진용 ( Jin Yong Chung ),김선녀 ( Sun Yeou Kim ),김호철 ( Ho Cheol Kim ),권용준 ( Youn Jun Kwon ),함대현 ( Dae Hyun Hahm ),이혜정 ( Hae Jeong Lee ),심인섭 ( In Sup Shim ) 대한경락경혈학회 2002 Korean Journal of Acupuncture Vol.19 No.2

Kupunggibodan(KU), Gamisamul-tang(GA) and Whangryunhaedok-tang(WH) are clinically the most popular prescriptions as an herbal medicine in the treatment of ischemia. In order to compare and evaluate their protective effects on the ischema-induced cognitive deficits by middle cerebral artery occlusion (MCAO), we examined its ability to improve ischemia-induced cell loss and impairements of learning and memory in the Morris water maze and eight-arm radial arm maze. Focal cerebral ischemia produced a marked cell loss, decrease in acetylcholinesterase(AchE) reactivity in the hippocampus, and learning and memory deficits in two behavioral tasks. Pretreatment with WH (100 mg/kg, p.o.) produced a substantial increase in acquisition in the Morris water maze. Pretreatment with KU increased the perfomance of the resention test in the Morris water maze. WH, KU and GA caused a significant improvement in choice accuracy in radial arm maze test. WH was superior to KU and GA in perfomance of the radial arm maze test. Consistent with behavioral data, staining with cresyl violet showed that pretreatments with WH, but not KU and GA significantly recovered the ischemia-induced cell loss in the hippcampal CA1 area. In addition, pretreatments with WH and KU recovered the ischemia-induced reduction of AchE reactivity in the hippocampal CA1 area. These results demonstrated that KU, GA and WH have protective effects against ischimea-induced learning and memory impairments and that the efficacy was the order of WH>KU>GA in tratment of ischemia induced memory deficits. The present studies provide an evidence of KU, GA and WH as putative treatment of vascular dementia. Supported by a fund from the Ministry of Health and Welfare(HMP-00-OO-04-0004), and the Brain Korea 21 Project from Korean Ministry of Education, Korea.

친수성 PDMS 몰드를 이용한 마이크로 패턴 전사

이봄이(B.-y. Lee),이봉기(B.-K. Lee) 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.5월