Control of Reversible Self-Bending Behavior in Responsive Janus Microstrips

Oh, Myung Seok,Song, Young Shin,Kim, Cheolgyu,Kim, Jongmin,You, Jae Bem,Kim, Taek-Soo,Lee, Chang-Soo,Im, Sung Gap American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.13

<P>Here, we demonstrate a simple method to systematically control the responsive self-bending behavior of Janus hydrogel microstrips consisting of a polymeric bilayer with a high modulus contrast. The Janus hydrogel microstrips could be easily fabricated by a simple micromolding technique combined with an initiated chemical vapor deposition (iCVD) coating, providing high flexibility in controlling the physical and chemical properties of the microstrips. The fabricated Janus hydrogel microstrip is composed of a soft, pH-responsive polymer hydrogel layer laminated with a highly cross-linked, rigid thin film, generating a geometric anisotropy at a micron scale. The large difference in the elastic moduli between the two layers of the Janus microstrips leads to a self-bending behavior in response to the pH change. More specifically, the impact of the physical and chemical properties of the microstrip on the self-bending phenomena was systematically investigated by changing the thickness and composition of two layers of the microstrip, which renders high controllability in bending of the microstrips. The curvature of the Janus microstrips, formed by self-bending, highly depends on the applied acidity. A reversible, responsive self-bending/ unbending exhibits a perfect resilience pattern with repeated changes in pH for 5 cycles. We envision that the Janus microstrips can be engineered to form complex 3D microstructures applicable to various fields such as soft robotics, scaffolds, and drug delivery. The reliable responsive behaviors obtained from the systematic investigation will provide critical information in bridging the gap between the theoretical mechanical analysis and the chemical properties to achieve micron-scale soft robotics.</P>

적층각 변화에 따른 복합재료 회전익의 구조적 연성에 관한 연구

변창환,유용석,오택열 경희대학교 산학협력기술연구원 1997 산학협력기술연구논문집 Vol.3 No.-

This study is made allowance for using one dimensional modeling method that extracts equivalent stiffness matrix used the reduction of degree of freedom in order to sufficiently express the cross section of rotor blade and the material properties of composite. Modern helicopter rotor blade which are made from anisotropic material is very important a subject on the tailoring based on coupling tearms by changing of ply angle. In basing on this, we have searched for coupling terms by changing of ply angle of composite rotor blade and the dynamic behaviour of rotor blade for each coupling term.

문화의 새로운 개념에 관한 연구

오정석(Oh Jeong-Seok),윤호창(Youn Ho-Chang) 한국콘텐츠학회 2004 한국콘텐츠학회 종합학술대회 논문집 Vol.2 No.2

근대 산업사회에서 현대 지식기반 사회에 이르러 문화에 대한 관심이 증가하고 있다. 중세의 신 중심 사상에서 인간 중심 사상으로의 중심이동은 이제 생명 복제와 같은 과학 기술 발달과 함께 인류가 신의 영역에 점차 가까워지는 단계에 이르게 되었다. 이러한 급진적인 변화의 흐름에서도 인류 문화의 진화는 더디게만 느껴진다. 생명 경시, 종교 전쟁, 환경 파괴, 적자생존의 자본주의 제도 등은 우리가 바라는 인류공영의 발목을 옥죄는 듯하다. 본 논문은 이러한 현대의 문화 개념과 정체성을 되짚어 보고 21세기라는 새로운 시대의 그릇에 담길만한 문화의 개념을 ‘물’의 특성을 가진 ‘SeaCricle’이라는 새로운 용어로 재정의해 보고자 한다. People's Interest about culture is increasing to reach in today's knowledge based society on age of modern industrial society. Conversion of human based idea arrived in step that human through scientific technique development such as life reproduction approaches gradually in God's sacred ground. Evolution of human's culture was proceeded slowly in current of such radical change. Life underestimate, religion war, pollution etc. are seeming to keep away human development. This treatise wishes to redefine concept of suitable culture in new terminology of 'SeaCricle' that have characteristic of water at 21C's New Age.

Which Environmental Factors Caused Lammas Shoot Growth of Korean Red Pine?

Lee, Chang-Seok,Song, Hye-Gyung,Kim, Hye-Soo,Lee, Bit-Na-Ra,Pi, Jeong-Hoon,Cho, Yong-Chan,Seol, Eun-Sil,Oh, Woo-Seok,Park, Sung-Ae,Lee, Seon-Mi The Ecological Society of Korea 2007 Journal of Ecology and Environment Vol.30 No.1

Lammas growth, a rare phenomenon for Korean red pine (Pinus densiflora), occurred in 2006. Lammas shoots showed higher frequency and longer length in Seoul's hotter urban center than in urban boundary or suburban forest sites. Frequency and length showed a close correlation with urbanization density and vegetation cover expressed in NDVI. Air temperature in the late summer of 2006 was more than $1^{\circ}C$ higher than an average year. Of the predominant environmental signals that modulate bud flush, only temperature changed significantly during the year. Differences in temperature between the urban centers, urban boundaries and suburban forests correlated with varying land-use density. The rise in temperature likely spurred lammas growth of the Korean red pine. Symptoms of climate change are being detected throughout the world, and its consequences will be clearer in the future. Considerate interest in the responses of ecological systems to the variable changes is required to prepare for unforeseeable crises. Monitoring of diverse ecological phenomena at Long Term Ecological Research sites could offer harbingers of change.

생약제제인 이공산(異功散)의 Cisplatin 유도 신장독성 보호 및 항산화 효과

Lee, Kyung-Tae,Ahn, Kyoo-Seok,Chang, Sung-Goo,Oh, Soo-Myung,Jung, Jee-Chang 경희대학교 동서의학연구소 1999 INTERNATIONAL SYMPOSIUM ON EAST-WEST MEDICINE Vol.1999 No.1

Kyung-Tae Lee, Kyoo-Seok Ahn¹, Sung-Goo Chang², Soo-Myung Oh²and Jee-Chang Jung²¹College of Pharmacy, ²Oriental Medicine and ³College of Medicine, and East-West Medical Reserch Institute, Kyung Hee University, Seoul, Korea. Preventive and Antioxidative Effects of Crude Drug Preparation(E-kong-san) on Cisplatin Induced Nephrotoxicity. Proceedings of International Symposium on East-West Medicine, Seoul. 201-211, 1999. -Nephroprotective effects of a crude drug-prearation (E-kong-san) were determined from cisplatin on rabbit kidney proximal tubule and human renal cortical cells by MTT assays and sustained glucose consumption on ciplatin-induced human renal cortical tissue. Levels of creatinine and blood ure nitrogen(BUN) in serum after administration of cisplatin(0.75mg/kg,i.p.) to E-kong-san(0.75g/kg/day,p.o.)-pretreated rats were markedly lower compared to those of cisplatin-treated rats. Moreover, the administration of E-kong-san significantly inhibited the loss of body weight of cisplatin injected rts. These findings suggest that E-kong-san on the cisplatin induced nephrotoxicity led us to investigate whether the effect of this water extract was a result of anti-oxidation. E-kong-san showed strong free radical scavenger activities on 1,1-dipheny1-2picrylhydrazil(DPPH) radical and xanthine/xanthine oxidase(XOD) generated superoxide anion radical(O2-). We further studied the effects of E-kong-san on lipid peroxidation in rat liver microsomes induced by enzymatic and nonenzymatic methods. E-kong-san exhibited significant inhibition on both ascorbic acid/Fe2+and ADP/NADPH/Fe3+ induced lipid peroxidation in rat liver microsomes. Based on these results, we suggest that-E-kong-san attenuate the cisplatin induced cytotoxicity and its mechanism can be eplained by antioxidant.

2 ㎓ 선형 위상 천이 특성을 갖는 소형 아날로그 위상천이기

오현석(Hyun-Seok Oh),최재홍(Jae-Hong Choi),정해창(Hae-Chang Jeong),허윤성(Yun-Seong Heo),염경환(Kyung-Whan Yeom) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.1

본 논문에서는 2 ㎓ 선형 위상 천이 특성을 갖는 위상천이기를 설계 및 제작하여 보였다. 소형의 위상 천이기 구현을 위해 집중소자로 구성된 전통과 회로망(all pass network)을 기반으로 위상천이기를 구성하고, 박막 세라믹 공정을 이용하여 제작하였다. 또한, 선형의 위상 천이 특성을 얻기 위해 버랙터(varactor) 다이오드에 직렬 커패시터를 연결하여, 전압에 대한 커패시턴스를 선형화함으로써 비선형성을 개선하였다. 전통과 회로망에 나타나는 인덕터는 스파이럴 인덕터로 구현하고, 이를 다이오드 바이어스 회로에 활용하여 4 ㎜×4 ㎜ 면적을 가지는 소형 위상천이기를 구성할 수 있었다. 또한, 온-웨이퍼(on wafer)로 측정을 위해 입출력은 CPW(Coplanar Waveguide) 형상으로 구현하였으며, 제작된 위상천이기는 버랙터 조정 전압 0~5 V에 대하여, 2 ㎓에서 삽입 손실은 약 4.2~4.7 ㏈, 위상 변화량은 약 79°였으며, 예상한대로 선형 위상 천이 특성을 보였다. In this paper, we present a 2 ㎓ compact analog phase shifter with linear phase-tune characteristic. The compact phase shifter was designed base on a lumped all pass network and implemented using a ceramic substrate fabricated with thin-film technique. For a linear phase-tune characteristic, a capacitance of the varactor diode for a tuning voltage was linearized by connecting series capacitor and subsequently produced an almost linear capacitance change. The inductor and bias circuit in the all pass network was implemented using a spiral inductors for small size, which results in the size reduction to 4 ㎜×4 ㎜. In order to measure the phase shifter using the probe station, two CPW pads are included at the input and output. The fabricated phase shifter showed an insertion loss of about 4.2~4.7 ㏈ at 2 ㎓ band and a total 79° phase change for DC control voltage from 0 to 5 V, and showed linear phase-tune characteristic as expected in the design.

Rat의 포유조절에 따른 난소와 유선의 조직학적 성상

오석두,윤창현 진주산업대학교 농업기술연구소 2000 農業技術硏究所報 Vol.13 No.-

This experiment was conducted to investigate how the lactation regulation such as restricted-lactation, early weaning during the suckling period influences on ovarian functions in primiparous rats, on the bases of change in histological characteristics of ovary and mammary gland. 1. The ovaries of rats in middle lactation stage maintained the functional corpora lutea full of cytoplasm, and those of rats in late lactation stage contained matured ovarian follicles. 2. The milk was found full in the mammary gland tissue of NL rats, but short in the tissue of RL rats, and all the alveolar tissues were degraded in mammary gland of weaned rats. The alveoli structures of mammary gland of NL rats were uniformed on Day 10, but such uniformity was lost greatly on Day 20.

토양으로부터 항세균성 물질을 생산하는 Streptomyces sp. 의 분리

오현정,정완석,김세재,김창진,고영환 제주대학교 생명과학연구소 1999 제주생명과학연구 Vol.2 No.-

제주도의 토양에서 분리된 방선균 307주를 대상으로, paper disc법과 시험관 희석 배양법을 사용하여 항세균성 물질을 생산하는 균주를 선별하였다. 약 3.3%에 상당하는 분리주들이 Escherichia coli 8749, Staphylococcus aureus 6538 그리고 Pseudomonas solanacearum 10692에 대해 항균효과를 나타냈고, 그 중에서 가장 높은 항균활성을 나타내는 BL93 균주를 최종선별하여 동정하였다. BL93 균주의 배양학적, 형태학적, 생리학적, 생화학적 그리고 화학분류학적 특성을 기준으로 볼 때 Streptomyces violaceus와 유사하였기에, Streptomyces sp. BL93으로 명명하였다. 이 균주가 생산하는 항세균성 물질은 butanol보다도 물에 더 잘 녹는 극성화합물로 chloroform이나 ethylacetate에는 거의 용해되지 않았다. 100℃에서 30분간 가열 처리해도 활성의 소실이 거의 없었고, pH 3∼9범위에서 안정하였다. 분리균주 BL93은 aspartocin을 생산하는 Streptomyces violaceus와 유사함으로, BL93이 생산하는 항세균성 물질의 동정 및 aspartocin과의 비교 검토가 선행되어야 할 것이다. Three hundred and seven isolates of Actinomycetes were isolated and purified from soil samples in Cheju Is. to screen antibacterial compounds. About 3.3% of the isolates showed antibacterial activity, and one of them, BL93, showed relatively higher antibacterial activity against Escherichia coli 8749, Staphylococcus aureus 6538 and Pseudomonas solanacearum 10692 by both paper disc method and tube dilution incubation method. The isolate BL93 was similar to Streptomyces violaceus based upon its cultural, morphological, physiological, biochemical and chemotaxanomic characteristics. It was designated as Streptomyces sp. BL93. The antibacterial substance produced by the isolate BL93 had higher affinity for water than butanol and was insoluble in chloroform or ethylacetate. Most of its antibacterial activity was retained even after heating at 100℃ for 30min and was stable at pH ranges 3 to 9. As the isolate BL93 was tentatively identified to be Streptomyces violaceus, the antibacterial substance preferentially need to be identified and compared with aspartocin, an antimicrobial compound produced by Streptomyces violaceus.

카오스를 이용한 통신 비화시스템 연구

오진우,김창석 明知大學校 産業技術硏究所 1999 産業技術硏究所論文集 Vol.18 No.-

In this, we study a new secure communication system using a characteristic of chaos. The proposed system utilize a few system condition equation to occur securing signal and mixed with speech signal. The proposed system composed a flexible attracter occurrence development, obtained a high secure degress using attracter of the various styles. We convince a good quality securing in S/N rate of -40[dB] with secured signal and speech signal.

해조류 에탄올 농도별 추출물의 항돌연변이원성 및 항균성

박제석,오명철,오창경,현재석,김봉오,김수현 濟州大學校工科大學産業技術硏究所 1996 尖端技術硏究所論文集 Vol.7 No.2

톳. 미역 및 다시마의 에탄올 농도별 추출물이 MMS. ICR191 및 sodium azide에 의해 유도되는 돌연변이원성의 억제효과 및 E. coli, B. subtilis 및 S. serevisiae에 대한 항균효과를 검정하였다. 톳의 90% 에탄올 추출물은 MMS와 ICR191에 대한 항돌연변이 원성이 각각 70 및 95% 이상으로 매우 높았으나, sodium azide에 대한 항돌연변이원성은 없었다. 미역의 에탄올 농도별 추출물은 30∼90% 에탄올 추출물에서 50% 이상의 항돌연변이 효과를 보았으나 MMS와 sodium azide에 대한 항돌연변이 효과는 없었다. 다시마의 30∼90% 에탄올 추출물의 ICR191에 대한 항돌연변이 효과는 70% 이상이었으나, MMS와 sodium azide에 대한 효과는 없었다. 에탄올 농도별 톳의 추출물들에 대한 항균성 검색 결과 70과 90% 추출물들이 E. coli와 B. subtilis에 대하여 뚜렷한 항균효과는 미역 추출물 보다 다시마의 추출물이 더욱 요과적이었다. 미역 추출물은 50% 추출물만이 S. cerevisiae에 대한 성장저지효과를 나타낸 반면, 다시마 추출물은 90% 에탄올 추출물에서는 시험된 모든 공시균주에 대하여, 그리고 70% 에탄올 추출물에서는 E. coli와 B. sutilis에 대하여 높은 성장저지효과를 나타내었다. Desmutagenic against MMS-, ICR191- and sodium azide-induced mutations, and antimicrobial effects against Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae by the extracts from Hizikia fusiforme. Laminaria japonica and Undaria pinnatifida with ethanol of a different concentrations were investigated. Desmutagenic effects against MMS and ICR191 of 90% ethanol extracts from Hizikia fusiforme were up 70 and 95%. respectively. no against sodium azide. Desmutagenic effects against ICR191 of 30∼90% ethanol extracts from Undaria pinnatifida and Laminaria japonica were up to 50 and 70%. respectively. but no against sodium azide and MMS. Antimicrobial effect of 70 and 90% ethanol extracts from Hizikia fusiforme had potent antimicrobial activities against E. coli and B. subtilis. Ethanol extracts from Laminaria japonica showed more effective antimicrobial effects than those from Undaria pinnatifida. Only 50% ethanol extract from Undaria pinnatifida showed growth inhibition effect against S. cerevisiae. Seventy percent ethanol extract from Laminaria japonica showed growth inhibition effect against all strains tested. while 90% ethanol extract showed against E. coli and B. subtilis.