Dry etching of polydimethylsiloxane using microwave plasma

Hwang, Sung Jin,Oh, Dong Joon,Jung, Phill Gu,Lee, Sang Min,Go, Jeung Sang,Kim, Joon-Ho,Hwang, Kyu-Youn,Ko, Jong Soo IOP 2009 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.19 No.9

<P>This paper presents a new polydimethylsiloxane (PDMS) dry-etching method that uses microwave plasma. The applicability of the method for fabricating microstructures and removing residual PDMS is also verified. The etch rate of PDMS was dominantly influenced by the gas flux ratio of CF<SUB>4</SUB>/O<SUB>2</SUB> and the microwave power. While the PDMS etch rate increased as the flux ratio of CF<SUB>4</SUB> was increased, the etch rate decreased as the flux ratio of O<SUB>2</SUB> was increased. The maximum etch rate of 4.31 µm min<SUP>−1</SUP> was achieved when mixing oxygen (O<SUB>2</SUB>) and tetrafluoromethane (CF<SUB>4</SUB>) at a 1:2 ratio at 800 W power. The PDMS etch rate almost linearly increased with the microwave power. The ratio of the vertical etch rate to the lateral etch rate was in a range of 1.14–1.64 and varied with the gas fluxes. In consideration of potential applications of the proposed PDMS etching method, array-type PDMS microwells and network-type microprotrusion structures were fabricated. The contact angle was dramatically increased from 104° (non-etched PDMS surface) to 148° (etched PDMS surface) and the surface was thereby modified to be superhydrophobic. In addition, a thin PDMS skin that blocked holes and PDMS residues affixed in nickel microstructures was successively removed.</P>

원산지별 감초추출물의 항산화활성 증가를 위한 효율적인 추출조건 탐색

하지훈 ( Ji Hoon Ha ),이혜미 ( Hye Mi Lee ),권순식 ( Soon Sik Kwon ),김해수 ( Hae Soo Kim ),김문진 ( Moon Jin Kim ),전소하 ( So Ha Jeon ),정유민 ( Yoo Min Jeong ),황준필 ( Jun Pil Hwang ),박종호 ( Jong-ho Park ),최영기 ( Yung-key 대한화장품학회 2013 대한화장품학회지 Vol.39 No.4

본 연구에서는 한국 및 중국산 감초(Glycyrrhiza uralensis), 그리고 우즈베키스탄산 감초(Glycyrrhiza glabra)를 대상으로 추출용매, 추출온도, 추출시간 등 추출조건별 추출물을 제조하고 이들 추출물들의 추출 수율과 항산화 활성을 비교하여 최적의 추출조건을 선정하였다. 항산화 활성 중 자유 라디칼(1,1-phenyl-2-pic-rylhydrazyl, DPPH) 소거활성은 85% 에탄올로 60 ℃에서 6 h 동안 추출한 조건에서 한국 감초로부터 얻은 추출물이 가장 높은 활성(46.05%)을 나타내었다. 루미놀 발광법을 이용한 추출물들의 총 항산화능 측정 실험과 피부 광노화에 중요한 ¹O₂으로 유도된 세포막 손상에 대한 추출물들의 세포 보호 효과를 측정한 실험 모두에서도 위의 조건에서 가장 높은 항산화 활성을 나타내었다. 특히, 한국 감초는 τ₅₀이 116.4 min으로 비교 물질인(+)-α-tocopherol (28.5 min)보다 약 4 배나 높은 세포 보호 효과를 나타내었으며, 추출 수율은 18.75%로 우즈베키스탄 및 중국 감초보다 각각 1.2 배 및 2.5 배의 추출 수율을 나타내었다. 따라서, 본 연구 결과는 항산화 소재로 화장품에 응용하기 위하여 감초로부터 추출물을 얻기 위한 최적의 조건은 85% 에탄올로 60 ℃에서 6시간 동안 추출하는 것임을 보여주었다. In this work, licorice extracts were prepared using various extraction conditions such as extraction solvent, temperature, and time from Glycyrrhiza uralensis (G. uralensis) produced in Korea and China and Glycyrrhiza glabra (G. glabra) in Uzbekistan. The optimum extraction condition was selected from the extraction yields and antioxidative activities of extracts. Korea licorice extracts showed the highest free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scav-enging activity (46.05%) under the extraction condition of 85% ethanol at 60 ℃ for 6 hours. The prominent ROS (reactive oxygen species) scavenging activity using luminol-dependent chemiluminescence assay and the cellular protective effect against ¹O₂ induced cellular membrane damage were also shown from the extracts obtained from the same condition. Especially, Korea G. uralensis extracts exhibited the higher prominent protective effect (τ₅₀ = 116.4 min) than (+)-α-tocopherol (τ₅₀ = 28.5 min) and the extraction yield of Korea licorice extract was 18.75%, which is 1.2 times and 2.5 times higher than that of Uzbekistan and China, respectively. These results indicate that the extraction condition of 85% ethanol at 60 ℃ for 6 hours is optimal to prepare licorice extracts, which can be applicable as antioxidative cosmetic materials.

Improving the subcritical water extraction of flavonoids narirutin and hesperidin from Citrus unshiu peel by pulsed electric fields

Hui-Ju Kim,Mi-Ri Kwon,Hye-Ji Kang,Na-Yeon Kim,Hee-Jeong Hwang,Min-Jung Ko,Myong-Soo Chung 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11

Citrus fruit is important source of flavonoids, mainly flavanones which are narirutin and hesperidin. Those citrus flavonoids have been found to have health-related properties including antioxidant, anticancer, and anti-inflammatory. The main purpose of this study was to verify that the extraction of narirutin and hesperidin from Citrus peel can be more effective by combining pulsed electric field (PEF) pre-treatment and subcritical water extraction (SWE). Citrus unshiu peels were treated with PEF under conditions of electric field strength (3 kV/cm) and times (1 and 2 min). Subsequent SWE was conducted by using a Dionex Accelerated Solvent Extractor (ASE, Model 350) at extraction temperature 170°C for 10 min. The total flavonoids content was measured by using the aluminum chloride colorimetric method and the antioxidant capacity was analyzed by the Ferric reducing antioxidant power (FRAP) assay using spectrophotometer. The concentrations of narirutin and hesperidin were increased as PEF pre-treatment time increased. The highest concentrations of narirutin and hesperidin were 13.41 mg narirutin/g dry citrus peel and 141.16 mg hesperidin/g dry citrus peel at PEF pre-treatment condition of 3 kV/cm and 2 min. The total flavonoids contents of the extracts increased 105.2% and 123.1% for citrus peel PEF treated at 1 and 2 min, respectively. In addition, compared to the untreated sample, PEF pre-treatments of 1 and 2 min increased the antioxidant capacity of the extracts 109.2% and 160.8%, respectively. Therefore, the results demonstrate the potential of PEF pre-treatment to improve the SWE of flavonoids from citrus unshiu peel.

고온에서 회전하는 터빈엔진 디스크의 응력해석

황수철,국정한,조재웅,하영민 한국공작기계학회 1995 한국생산제조학회지 Vol.4 No.4

This study includes thermal plasticity analyses for a turbine rotor with the simple geometry and the boundary conditions. When centrifugal or thermal stress are applied at the high temperarture material of engine blade, stress distributions in material σ_rr, σ_θθ, τ_rθ. Mises stress) are analyzed by computer simulation(ABAQUS) as followings; 1. The maximum stress at the radial direction (σ_rr) is applied at the upper middle part of spline hole. 2. The maximum stress at the tangential direction (σ_θθ) is applied at the upper right boundary of spline hole. 3. The maximum shear stress (τrθ) in (-) direction is applied at the upper middle part of spline hole. 4. The maximum Mises stress is applied at the upper right boundary of spline hole. This stress is due to the critical stress by which rotor can be fractured according to elapsed time.

소형 기기용 효율적인 바이트 코드 검증기술에 관한 연구

황철준,조증보,정민수 慶南大學校 附設 工業技術硏究所 2003 硏究論文集 Vol.21 No.2

USIM(Universal Subscriber Identity Module) 기술은 데이터의 관리와 보호를 하나의 소형 칩 내에 집약시킨 기술로 최근에 이 기술에 대한 관심도가 증가하고 있다. 자바카드 가상기계는 자바 언어로 작성된 프로그램이 USIM 칩 내부에서 실행 가능하도록 해준다. 하지만 자바카드 가상 기계는 자원 제약적인 디바이스의 특성으로 인하여 검증기술을 제공하지 않는다. 본 논문에서는 정적 체크 기반의 효율적인 바이트코드 검증기를 제안한다. 연구 결과 본 논문에서 제안하는 검증기는 일반적인 것에 비해 90% 이상의 사이즈가 감소되었다. As Universal Subscriber Identity Module (USIM) technology can handle, manager and protect data within a small sized chip, peopled are more interested in USIM technology lately. Java Card Virtual Machine (JCVM) enables programs written by Java programming language to be run in smart cards with USIM chips. However JCVM does not have a verifier as limits of hardware. In this paper, we propose a ByteCode verifier with novel algorithm based on Static Check policy. We experiment that the size of our verifier is reduced by 90% over generals.

국내 테니스 경기의 관전 저해요인 분석을 통한 마케팅적 접근 방법에 관한 연구

황민수,신갑호 명지대학교 대학원 1999 대학원논문집 Vol.3 No.-

The purpose of this study was to verify obstacle factors that affect participation in a tennis game in Korea. For the purpose of the study, a self-administered questionnaire was developed. The needs for latent consumer as dependent variables were specifically investigated by communication, skills of tennis game, life cycle, participate in sports, levels of the service, affects of climate, a viewing of other sport games. Independent variables of this study were sex, marriage, kids, age, education level, job, numbers of activity participation for a week, and number of viewing of tennis game for last year. The subject of the study were 247 amateur tennis players(M:175, F:72) and registered in 4 tennis clubs. To compare the difference of dichotomous items such as sex, marriage, and kids, a t-test was employed. One-way ANOVA and Scheffe post hoc test were also used to verify obstacle factors of participation in a tennis game.

디메틸 실록산과 2-히드록시에틸메타크릴레이트계 블락공중합체의 합성 : 초임계 이산화탄소용 양손잡이형 계면활성제 Ambidextrous Surfactant for Supercritical Carbon Dioxide

황하수,이민영,임권택 釜慶大學校 2001 釜慶大學校 論文集 Vol.6 No.-

Block copolymers containing dimethy siloxane and 2-hydroxyethyl methacrylate sequences were synthesized by group transfer polymerization (GTP) of 2- trimethylsilyloxy ethyl methacrylate(TMS-EMA) using silyl ketene acetal terminated poly(dimethylsiloxane) (PDMS) as macroinitiator, followed by hydrolysis of TMS-EMA to HEMA. The block copolymers were obtained with controlled molecular weight and narrow molecular weight distribution. Trimethylsilyl groups in the P(TMS-EMA) block could be selectively hydrolyzed without interfering with Si-O bond in PDMS block. The block copolymers formed micelles in methanol, the effective diameters (Rh) of which were in the range of 78 ~110 nm with narrow distribution by dynamic light scattering (DLS). The latex particles, PMMA was synthesized by dispersion polymerization in supercritical carbon dioxide with these block copolymers as stabilizer.

砂質土에서 鋼말뚝의 마찰지지력에 관한 연구

황신일,민덕기,조상덕,김수일 연세대학교 산업기술연구소 1981 논문집 Vol.13 No.2

The friction resistance of a pile is the major contribution to the bearing capacity of friction piles. In this paper, an empirical equation for the friction capacity of steelpipe piles in sand is proposed through the laboratory pullout test. Pullout tests are carried out for the piles with length to diameter ratios of 4 to 10. The density levels of sand selected in the test are very loose, loose, medium and dense. The experimental analysis shows that the friction capacity is linearly increased with the internal friction angle of sand, and it also shows that the friction capacity is linearly increased with the length to diameter ratio of piles. Also, an important parameter to determine the friction capacity of a pile, the lateral coefficient of earth pressure, shows good correlations when compared with other pile equations.

아세트아미노펜 서방형 정제의 용출유사성에 대한 고찰

김민수,이시범,이태완,전재일,황성주 충남대학교 약학대학 의약품개발연구소 2004 藥學論文集 Vol.19 No.-

We have studied the dissolution kinetics of three extended release commercial tablets of acetaminoPhen in simulated gastric juice, and the dissolution profiles were compared. The applied methods for the comparison of in vitro dissolution profiles are model independent methods including difference factor (f₁) and similarity factor (f₂), and statistical methods based on the analysis of variance and in t-test. The comparison of the dissolution profile, using difference factor (f₁), and similarity factor (f₂), indicates that the three tablets are equivalent in their dissolution. But, statistical methods based on the analysis of variance and in t-test indicate that the three tablets are not equivalent in their dissolution. The results show that statistical methods are better indicator of discrimination than the f-factors.

TiN/TiSi₂-bilayer 형성과 전기적 특성

서경수,황찬용,이광만,최치규,강민성 濟州大學校 基礎科學硏究所 1997 基礎科學硏究 Vol.10 No.2

TiN/TiSi₂-bilayers were formed by reactive sputter deposition in mixed gas of Ar+N₂ on the TiSi₂/Si(100) substrate, which TiSi₂ film was grown by means of the Ti sputtering, and the coevaporation of Ti and Si(Ti : Si = 1 : 2) on the Si(100)-2 ×1 substrate followed by in-situ annealing in ultrahigh vacuum. Stoichiometric Ti??N?? films with (111) texture determined XRD, RBS and XPS were grown at substrate temperature over 600℃, while films prepared at substrate temperature below 600℃ showed N-rich TiN, and the high quality TiSi₂ film was obtaind from the Ti/Si(100) and (Ti+2Si)/Si(100) samples annealed at 700℃. It is capping effect that the TiSi₂ film in the TiN/TiSi₂/Si(100) structure does not occure the agglomeration phenomena. The sheet resistance of the TiN/TiSi₂-bilayer prepared at 700℃ showed 0.39Ω/㎝².