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>

국내외 수용가 맞춤형 수력발전시스템 현대화개발 및 실증

오민환(Min-Hwan Oh),신기석(Ki-Seok Shin),임재황(Jae-Hwang Lim),윤여창(Yeo-Chang Yun),김현아(Hyun-Ah Kim),강석원(Seok-Won Kang),백종명(Jong-Myung Paik),이준용(Jun-Yong Lee) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.10

개체동결 굴(Crassostrea gigas)을 이용한 레토르트파우치 굴국의 제조 및 품질특성

황영숙 ( Young-sook Hwang ),조준현 ( Jun-hyun Cho ),황석민 ( Seok-min Hwang ),김상현 ( Sang-hyun Kim ),김병균 ( Byeong-gyun Kim ),오광수 ( Kwang-soo Oh ) 한국수산과학회(구 한국수산학회) 2016 한국수산과학회지 Vol.49 No.6

To develop a value-added product from individually quick-frozen oysters Crassostrea gigas (IQFO), we prepared a retort pouched oyster soup (RPOS) from IQFOs and characterized its processing conditions and quality metrics. We found that the most appropriate manufacturing process for the RPOS consisted of half-thawing and washing raw IQF oysters, blanching, adding them to the retort pouch along with other ingredients (base soup stock, IQF oyster extract, radish, bean sprouts, garlic, and red pepper), sealing, retort sterilization (120°, F0-value 10 min.), cooling, and packaging inspection. The moisture, crude protein, pH and salinity of the RPOS were 91.0%, 2.8%, 6.20 and 0.9%, respectively. The total amino acid content of the RPOS was 2,163.8 mg/100 g, and the main amino acids were glutamic acid, aspartic acid, leucine, proline, lysine and arginine. The primary inorganic ions were Na, K, S and Zn. In taste compounds, total free amino acid content was 313.4 mg/100 g, and the main free amino acids were glutamic acid, taurine, proline, hydroxyproline, aspartic acid, glycine, alanine, valine, lysine and arginine. This RPOS has good storage stability and organoleptic qualities compared with commercial retort pouched shellfish soup, and is suitable for commercialization as a value-added instant seafood soup.

알루미나이드 확산코팅된 스테인레스 합금의 내산화 및 내삭마 특성

황철홍,이효민,오정석,황동현,황유석,이종원,최정묵,박준식,Hwang, Cheol Hong,Lee, Hyo Min,Oh, Jeong Seok,Hwang, Dong Hyeon,Hwang, Yu Seok,Lee, Jong Won,Choi, Jeong Mook,Park, Joon Sik 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.5

Stainless steel, a type of steel used for high-temperature parts, may cause damage when exposed to high temperatures, requiring additional coatings. In particular, the Cr₂O₃ product layer is unstable at 1000℃ and higher temperatures; therefore, it is necessary to improve the oxidation resistance. In this study, an aluminide (Fe₂Al₅ and FeAl₃) coating layer was formed on the surface of STS 630 specimens through Al diffusion coatings from 500℃ to 700℃ for up to 25 h. Because the coating layers of Fe₂Al₅ and FeAl₃ could not withstand temperatures above 1200℃, an Al₂O₃ coating layer is deposited on the surface through static oxidation treatment at 500℃ for 10 h. To confirm the ablation resistance of the resulting coating layer, dynamic flame exposure tests were conducted at 1350℃ for 5-15 min. Excellent oxidation resistance is observed in the coated base material beneath the aluminide layer. The conditions of the flame tests and coating are discussed in terms of microstructural variations.

ESO기법을 이용한 신뢰성 기반 형상 최적설계

오영규,박재용,황승민,임민규,박재용,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

This paper presents a reliability-based shape optimization (RBSO) using the evolutionary structural optimization (ESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. The deterministic optimization (DO) is obtained without considering uncertainties related to uncertainty parameters. However, the RBSO can consider the uncertainty variables because it has the probabilistic constraints. In order to determine whether the probabilistic constraint is satisfied or not, simulation techniques and approximation methods are developed. In this paper, the reliability-based shape design optimization method is proposed by utilizing the reliability index approach (RIA), performance measure approach (PMA), single-loop single-vector (SLSV), adaptive-loop (AOL) are adopted to evaluate the probabilistic constraint. In order to apply the ESO method to the RBSO, a sensitivity number is defined as the change in the displacement. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model more reliable than deterministic shape optimization.

신이식에서 이식신의 생존분석

오선미,김종학,황평주,구영선,강민규,나기량,김종섭,김성숙,이강욱,신영태,설종구,배진선,손기섭 충남대학교 의과대학 지역사회의학연구소 1997 충남의대잡지 Vol.24 No.2

To investigate the prognostic factors for the survival of transplanted kidney in patients with end-stage renal failure, 59 cases of renal transplantation from September 1986 to Feburary 1997 in Chungnam National University Hospital were analyzed retrospectively. The results were as follows: 1)The mean age of recipients was 33.8 years and that of doners was 38.9 years. The male to female ratio of recipients was 2.5:1, and that of donors was 1.03:1 2) Living related donore(LRD) were 79.6% and living non-related donors were 20.3%. The HLA-identical donors(ID) in LRD were 18.7% and HLA-haploidentical donors(HID) were 61.0%. In living non-related donors(LNRD), mean matched HLA-AB antigens were 1.56 and mean matched HLA-DR antigens were 0.56. 3) The average 5-year patient survival fate was 94%, and average 5-year graft survival rate was 70%. The 5-year graft survival fate of HLA-ID was 100%, and those HLA-HID and LNR were 70% and 36% respectively. 4) Total 33 episodes of acute rejection were found in 45.8% of transplanted patients. The number of acute rejection episode did not show significant difference between LRD and LNRD(P > 0.05). There was no significant difference in MLC between two groups(p > 0.05). 5) In comparison between the 18 patients who lost their graft function in 5 years and 17 patients who are maintaining graft function for more than 5 years, MLC was significantly lower in patients with functioning graft than of patients with non-functioning graft (p < 0.05). The number of rejection episode was also lower in patients with functioning graft than that of the patients with non-functioning graft(p < 0.05). However, there were no significant difference in recepient and donor age and history of pre-transplantation donor specific transfusion between two groups. With the results above, we can speculate that adequate donor selection according to good matched HLA typing and low MLC is very important for graft survival in renal transplantation. Prevention and treatment of acute rejection in renal transplantation is also na important factor for graft survival.

적응 루프법을 이용한 진화적 구조 위상 최적설계

황승민,박재용,임민규,오영규,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). Topology optimization is formulated as volume minimization problem with probabilistic displacement constraint. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., RIA, PMA, SLSV and ADL(adaptive-loop), are used. Reliability-based topology optimization design process is conducted to obtain optimal topology satisfying displacement and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.

신뢰성 지수에 의한 위상최적화

임민규,박재용,황승민,오영규,박재용,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

The objective of this work is to integrate reliability analysis into topology optimization problems. The reliability index determines design domain and uncertainty value. The elemental sensitivity numbers are calculated from finite element analysis and then converted to the nodal sensitivity numbers in the design domain. A mesh-independency filter using nodal variables is introduced to determine the addition of elements and eliminate unnecessary structural details below a certain length scale in the design. To further enhance the convergence of the optimization process, the accuracy of elemental sensitivity numbers is improved by its historical information. Application of the RBTO model gives a different topology relative to DTO. It is found that the RBTO model yields more reliable optimal topologies than those produced by DTO.

두개안면 섬유성 이형성증의 임상적 고찰

백롱민,오갑성,윤성호,백세민,황민호 大韓成形外科學會 1994 Archives of Plastic Surgery Vol.21 No.3

Fibrous dysplasia is a benign pathologic condition of bone and causes facial deformities as well as functional problems. We have managed 32 craniofacial fibrous dysplasia form March 1989 to December 1993. The most common age distribution of surgery was second decade(34%) and third decade(53%). In our patients, the desease process usually begins in childhood and progresses throughout puberty and adolescence. Treatment was aimed at preventing and correcting functional problems and achieving normal facial aesthetics. The reconstruction with other combined surgery, i.e., mandibular and maxillary osteotomies, reduction malar plasty, malar augmentation and orbit, nasal reconstruction with bone graft. Postoperative results were satisfactory in most cases. In some patients, repeated contouring(16%) surgery might produce less morbidity than a single massive resection. In evaluating the extent of the lesion, computerized tomography prooved to be a good diagnostic tool. Aethetically and functionally satisfactory surgical results were achieved by bone shaving in combination with reconstructive surgery.

치근 천공 치료 재료의 생체친화성의 비교

강민경,배인호,고정태,황윤찬,황인남,오원만 대한치과보존학회 2009 Restorative Dentistry & Endodontics Vol.34 No.3

This study was carried out in order to determine in vitro biocompatibility of white mineral trioxide aggregate (MTA), and to compare it with that of the commonly used materials, i. e. calcium hydroxide liner(Dycal), glass ionomer cement (GIC), and Portland cement which has a similar composition of MTA. To assess the biocompatibility of each material, cytotoxicity was examined using MG-63 cells. The degree of cytotoxicity was evaluated by scanning electron microscopy (SEM) and a colorimetric method, based on reduction of the tetrazolium salt 2,3 bis {2methoxy 4nitro 5〔(sulfenylamino) carbonyl〕2H tetrazolium hydroxide} (XTT) assay. The results of SEM revealed the cells in contact with GIC, MTA, and Portland cement at 1 and 3 days were apparently healthy. In contrast, cells in the presence of Dycal appeared rounded and detached. In XTT assay, the cellular activities of the cells incubated with all the test materials except Dycal were similar, which corresponded with the SEM observation. The present study supports the view that MTA is a very biocompatible root perforation repair material. It also suggests that cellular response of Portland cement and GIC are very similar to that of MTA. 이번 연구는 치근 천공의 치료 재료인 white mineral trioxide aggregate (MTA)를 흔히 사용되는 calcium hydroxideliner(Dycal^(R), glass ionomer cement (GIC), 그리고 MTA와 유사한 성분을 가진 Portland cement와 세포독성 실험으로 생체 친화성을 평가하는 것이다. 세포독성의 정도는 MG-63 세포를 이용해 주사전자 현미경적 관찰과 수용성 tetrazolium salt를 이용한 흡광도를 측정 (XTT assay)하여 평가하였다. SEM 관찰에서, 1일과 3일째 모두에서 GIC와 MTA, Portland cement표면에서는 잘 부착된 세포를 보여주었다. 반면에, Dycal 표면의 세포들은 둥글고 부착되지 않은 양상을 보여주었다. XTT assay에서는 Dycal을 제외한 모든 재료에서 유사하게 높은 세포 활성도를 보여주었으며, 이는 SEM 관찰 소견과 일치하였다. 이번 연구는 MTA가 생체친화적인 재료라는 견해를 뒷받침한다. 또한 Portland cement와 GIC에서도 MTA와 유사한 세포반응을 보여주었다.