http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
DLC Structure Layer for Piezoelectric MEMS Switch
황현석,이경근,유영식,임윤식,송우창,Hwang, Hyun-Suk,Lee, Kyong-Gun,Yu, Young-Sik,Lim, Yun-Sik,Song, Woo-Chang Korea Society of Satellite Technology 2011 한국위성정보통신학회논문지 Vol.9 No.1
본 논문에서는 d33 모드로 구동하여 우수한 성능을 가지는 RF-MEMS 스위치의 구현을 위한 희생층과 구조층의 조합으로서 DLC와 포토레지스트를 제안하였다. 포토레지스트의 경화현상을 방지하기 위하여 DLC 구조층은 상온에서 RF-PECVD 방법을 이용하여 증착하였다. 그리고 PZT 압전층은 RF 마그네트론 스퍼터링 방법을 이용하여 상온에서 구조층 위에 증착하였으며, 희생층의 제거 후 결정화를 위하여 급속 열처리 (RTA) 장비를 이용하여 후 열처리하였다. PZT의 결정화 과정과 DLC의 기계적 성질의 변화를 다양한 온도조건에 따라 분석한 결과 DLC는 PZT의 결정화 온도까지 영률과 강도면에서 우수한 특성을 나타냄을 확인하였다. 또한 포토레지스트를 사용함으로서 공정을 단순화하고 낮은 비용으로 제작이 가능하였다. In this paper, a new set of structural and sacrificial material that is diamond like carbon (DLC)/photoresist for high performance piezoelectric RF-MEMS switches which are actuated in d33 mode is suggested. To avoid curing problem of photoresist sacrificial layer, DLC structure layer is deposited at room temperature by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method. And lead zirconate titanate (PZT) piezoelectric layer is deposited on structure layer directly at room temperature by rf magnetron sputtering system and crystallized by rapid thermal annealing (RTA) equipment. Particular attention is paid to the annealing of PZT film in order to crystallize into perovskite and the variation of mechanical properties of DLC layer as a function of annealing temperature. The DLC layer shows good performance for structure layer in aspect to Young's modulus and hardness. The fabrication becomes much simpler and cheaper with use of a photoresist.
황현석,여동훈,김종희,송준태,Hwang, Hyun-Suk,Yeo, Dong-Hun,Kim, Jong-Hee,Song, Joon-Tae 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.6
In this work, Ga-doped ZnO (GZO) thin films for gas sensor application were deposited on low temperature co-fired ceramics (LTCC) substrates, by RF magnetron sputtering method. The LTCC substrate is one of promising materials for this application since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.). The LTCC substrates with thickness of $400\;{\mu}m$ were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The structural properties of the fabricated GZO thin film with thickness of 50 nm is analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The film shows good adhesion to the substrate. The GZO gas sensors are tested by gas measurement system and show fast response and recovery characteristics to $NO_x$ gas that is 27.2 and 27.9 sec, recpectively.
LTCC 기판상에 증착한 GZO 가스 센싱 박막의 두께 의존 특성 연구
황현석,Hwang, Hyun Suk 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.3
A novel design of gas sensor using Ga-doped ZnO (GZO) thin films which are deposited on low temperature co-fired ceramic (LTCC) substrates is presented. The LTCC substrates with thickness of 400 ${\mu}m$ are fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The GZO thin films with different thickness are deposited on LTCC substrates, by RF magnetron sputtering method. The microstructure and sensing properties of GZO gas sensing films are analyzed as a function of the film thickness. The films are well crystallized in the hexagonal (wurzite) structure with increasing thickness. The maximum sensitivity of 3.49 is obtained at 100 nm film thickness and the fastest 90% response time of 27.2 sec is obtained at 50 nm film thickness for the operating temperature of $400^{\circ}C$ to the $NO_2$ gas.
甲狀腺 結節에 대한 細針突刺吸引 細胞診과 針生檢의 診斷的 價値
황현석,김보완 慶北大學校 醫科大學 1988 慶北醫大誌 Vol.29 No.1
甲狀腺 結節의 良性과 惡性을 감별하기 위한 細針穿剌吸引細胞診과 針生檢의 진단적 가치를 알아 보고자 甲狀腺炎을 제외한 結節환자에게 실시한 166例의 성적을 검토하였다. 그 결과 吸引細胞診의 세포 채취 성공율은 83%였고 이들가운데 良性群이 72%, 惡性이 의심스러운 群이 2%, 그리고 惡性群이 10%였다. 針生檢을 함께 한 64예에서 조직 채취 성공율은 86%였으며 이들의 病理學的 所見은 濾胞狀腫瘍이 30%, 結節性 增殖이 27%, 乳頭狀癌이 23%였고 濾胞狀腺腫과 濾胞狀癌으로 단정된 例는 각각 1例씩이였다. 진단적 정확도는 乳頭狀癌의 경우 細胞診과 針生檢에서 모두 높아 각각 83%, 92% 였으며, 濾胞狀腺腫의 경우 細胞診과 針生檢 모두 7%로 저조했다. 濾胞狀癌에서는 針生檢에서 20%의 정확도를 보였다. 이러한 결과로 보아 吸引細胞診 및 針生檢은 乳頭狀癌의 진단에는 그 가치가 높이 평가되나 濾胞狀腫瘍의 良性과 惡性의 감별에는 한계가 있는 것으로 생각된다. The diagnostic values of asoiration biopsy cytology (ABC) and needle biopsy for the differential diagnosis of thyroid nodules were studied. In this analysis of the cytological and histological findings from 166 patients with thyroid nodule, thyroiditis confirmed histologically was not included. The obtainability of adequate specimen by ABC was 83% : 72% of cytological findings were benign, 2% suspicious malignancy, and 10% malignancy. The obtainability of adequate tissue plus by needle biopsy was 86% in 64 cases. Out of them, follicular tumor was 30%, nodular hyperplasia 27%, and papillary carcinoma 23%. In comparison between postoperative diagnoses and cytological findings by ABC, the accuracy of ABC was 83% in papillary carcinoma, 7% in follicular adenoma, and 20% in follicular carcinoma. These results suggest that the values of both ABC and needle biopsy are high, with particular reference to papillary carcinoma and that the accuracy of both ABC and needle biopsy in differential diagnosis of follicular tumors may not be valuable.
아르곤 기체에서 진행하는 충격파 연구를 위한 비평형 분자동역학 모의실험 개발 및 응용
황현석,권찬호,김홍래,김성식,박민규,Hwang, Hyon-Seok,Kwon, Chan-Ho,Kim, Hong-Lae,Kim, Seong-Shik,Park, Min-Kyu 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.1
A nonequilibrium molecular dynamics(NEMD) simulation method is developed and applied to study shock waves propagating through argon gas. In this simulation method, shock waves are generated by pushing a piston at a constant speed from one side of a simulation box filled with argon molecules. A linear relationship between piston speeds and shock speeds is observed. Thermodynamic properties including density, temperature, and pressure before and after the shock front are obtained from the simulations and compared with the well-known Rankine-Hugoniot equations based on ideal gases. The comparison shows an excellent agreement, indicating that this NEMD simulation method can be employed to investigate various physical properties of shock waves further.
황현석 한국전기전자재료학회 1997 電氣電子材料學會誌 Vol.10 No.2
In this study, piezoelectric transducers were designed and manufactured using PZT-5A which had relatively high electromechanical coefficient, nondestructive testing system was developed which was able to inspect automatically using stepping motors, PC-Lab, and PC-Scope. The optimum design conditions for NDT were presented and verified comparing PZT-5A probes with comercial probes. It was proved by simulation and experiments that Epoxy is a good material as matching and backing layers. The envelope was reduced 60% with matching layer and 76% with matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error of PZT-5A probe was 2.8%.