스펙트럼 분석기를 이용한 PZT 압전체 박막의 nm 변위 측정

박봉찬,석해진,김태헌,조신욱,김일원,김헌오 한국물리학회 2019 새물리 Vol.69 No.11

Pb(Zr,Ti)O3 (PZT) piezoelectric materials are widely used in sensors, ultrasonic motors, and actuators for controlling the displacement below micrometer (m). We deposited a PZT film with a thickness of 700 nm on a Pt/TiO2/SiO2/Si substrate via the sol-gel technique. The displacement (in the nm range) of the PZT film according to the alternating voltage was accurately measured by using a Laser Doppler Vibrometer (LDV). The as-deposited PZT film on a silicon substrate was measured differently depending on the degree of clamping of the ac voltage applied to the substrate. For accurate measurement without error due to the fixing effect of this substrate, it was measured by attaching it to a rigid adhesive fixed plate. We analyzed the output signal strength of the LDV in the frequency range of interest by using with a spectrum analyzer to increase the measurement accuracy at low voltage, resulting in a piezoelectric coefficient of 45 pm/V. Pb(Zr,Ti)O3 (PZT) 압전체는 센서, 초음파 모터, ㎛ 이하의 변위를 제어하기 위한 액츄에이터 등에광범위하게 사용되고 있다. 졸-겔 방법으로 Pt/TiO2/SiO2/Si 기판 위에 700 nm 두께의 PZT 박막을 증착한 후 레이저 도플러 진동계 (Laser Doppler Vibrometer, LDV)를 이용하여 교류 전압에 따른 nm 범위의미세 변위를 정밀하게 측정하였다. 실리콘 기판 위에 증착한 PZT 박막은 인가 전압에 의해 휘어지는특성에 의해 기판의 고정 정도에 따라 변위 값이 다르게 측정된다. 이런 기판의 고정 효과에 의한 오차 없이정확한 측정을 위해 접착제로 기판을 단단한 고정 판에 부착하여 측정하였고 저 전압에서 측정 정밀도를 높이기 위해 스펙트럼 분석기로 레이저 도플러 진동계의 출력 신호를 주파수 영역에서 분석하여 PZT 박막의 nm 변위를 정밀하게 측정하여 45 pm/V의 압전 계수를 얻었다.

Czochralski법에 의한 $MgO:LiNbO_3$단결정 성장과 밀도 측정

김일원,박봉찬,김갑진,Kim, Il-Won,Park, Bong-Chan,Kim, Gap-Jin 한국결정학회 1993 韓國結晶學會誌 Vol.4 No.2

Lithium niobate(LiNbO3) 단결정은 유전성, 압전성, 초전성, 비선형 광학 및 선형 전기광학 물질로서 다양한 응용 성을 가지고 있으므로 전기와 광학장치로 널리 사용되어지고 있다. 그러나 LiNbo3 단결정이 레이저를 이용한 광학장치로 응용될 때 레이저광의 세기에 따라 상굴절(ne)과 이상굴절(no)이 불규칙하게 변하는 장손상이 발생하여 비선 형 광학소자로의 이용에 한계가 있음이 밝혀졌다. 1980년 Zhong등이 LiNbO3에 MgO를 4.5mol% 첨가한 MgO:LiNbO3단결정을 성장시켜 물성을 조사한 결과 광손 상이 현저하게 감소된다고 발표한 후 이 분야의 연구가 활발히 진행되고 있다. 본 연구에서는 순수한 LiNbO3 단결정의 최적 성장조건인 congrugnt한 LiNbOs(Li/Nb=0.486)에 MgO를 0, 2.5, 5.0, 7.5, 10.0 mol% 첨가시킨 MgO:LiNb03 단결정을 Czochalski법으로 성공적으로 성장시켰다. 결정성장은 성장온도 1250℃ 근방에서 회전속도 15rpm 인상속도 2.85 ∼3.25 mm/hr로 하였으며 냉각율은 30℃/hr이다. 성장시킨 단결정의 X-ray 회절실험과 편광현미경의 conoscope상 관찰로 양질의 MgO:LiNbO3 단결정이 성장되었음을 확인하였다. c축에 수직되게 절단한 c-pltae 시료 중 MgO가 첨가된 MgO:LiNb03 시료에서 나이테 형태의 둥근 원무늬가 나타나고 있다. 이 현상은 결정성장시 공기 중의 산소분압에 의해 MgO:LiNbO3 의 용융상태에서 MgO가 균일하게 분포되지 못하기 때문에 나타난 것으로 해석 된다. MgO 첨가량에 따른 MgO:LiNbo3 단결정의 결정 결함 구조를 조사하기 위하여 밀도측정을 하였다. MgO:LiNbO3 단결정의 밀도는 MgO론 2.5mol% 첨가한 시료에서 감소 하다가 5.0mol% 첨가한 시료에서 다시 증가하였으며 5.0mol%이상에서는 다시 감소하였다. 이 실험결과로 MgO 첨가량에 따른 결정 결함구조를 점 결함 모형 (point defect medel)으로 해석하였다. Single crystals of LiNbO3 have found extensive application in electro-optic and nonlinear optic devices. However, laser-induced refartive index inhomogeneities, which have been labeled opical damage impose limits on device optical damage in LiNbO3 is imporved if more than 4.5 rml% MgO is added to the melt The laser damage thrueshold increased as much as 100 times better then that of undoped crystals. The MgO doped cystal has thus been urterlsiv81y studied since then. In the study, Mgo:LiNbOs(MLA) single crystals dopsd with 0, 2.5, 5.0, 7.5, 10.0 mol% MgO have been grown by the czocrualski technique. The metls were prepared in the platinum crluible and 15∼20mm diameter crystals were grown with a length of 20∼30mm in a resitance heater. The growth rate was 2.5mm/hr, the rotation speed 15rpn. Before sawing MLN single crystals were annealed for 24 hours under atmosphere at a temperature of 1080℃. After sawing, we have found an annual ring cross section of MNA crystals only in the direction of perpendicilar to the c-axis. Nonuniform dispusion of MgO was pointed out that the cuties of the state of oxide were strongly affected by oxygen partial pressure in.

Transverse piezoelectric properties of Mn-doped Bi0.5Na0.5TiO3 thin films

Bich Thuy Nguyen,원성식,박봉찬,조용진,안창원,김일원,김태훈 한국물리학회 2020 Current Applied Physics Vol.20 No.12

Lead-free (Bi0.5Na0.5)(Ti1-xMnx)O3 (BNTMn-x; x = 0, 0.0025, 0.0050, 0.0100) thin films were fabricated using a chemical solution deposition method on Pt/TiO2/SiO2/Si substrate. The effect of Mn substitution on crystal structures, surface morphologies, and ferroelectric and transverse piezoelectric properties of BNTMn-x thin films was investigated. The 0.5 mol% Mn-doped (Bi0.5Na0.5)(Ti0.995Mn0.005)O3 thin film exhibited a well-saturated ferroelectric P-E hysteresis loop at room temperature. A remnant polarization (Pr) of 16 μC/cm2 was obtained for the BNTMn-0.0050 film at an applied electric field of 400 kV/cm. In addition, a 1.12-μm-thick BNTMn- 0.0050 film was applied as a cantilever. The Pt/BNTMn-0.0050/Pt/TiO2/SiO2/Si unimorph cantilever exhibited a high transverse piezoelectric coefficient (e*31) of 2.43 C/m2.

하악골 양측 하악지 시상분할 골절단술 후 흡수성 고정의 안정성에 관한 연구

최병환,박수원,장수미,손한나,박봉찬,손장호,조영철,성일용,Choi, Byoung-Hwan,Park, Su-Won,Jang, Soo-Mi,Son, Han-Na,Park, Bong-Chan,Son, Jang-Ho,Cho, Yeong-Cheol,Sung, Iel-Yong 대한구강악안면외과학회 2010 대한구강악안면외과학회지 Vol.36 No.4

Introduction: To evaluate the skeletal stability after a bilateral sagittal split osteotomy (BSSO) setback of the mandible fixed with a biodegradable internal fixation device or metal internal fixation device. Materials and Methods: Thirty consecutive patients underwent mandibular setback via BSSO. Fifteen patients were fixed with a biodegradable internal fixation device or metal internal fixation device respectively. Posteroanterior (PA) and lateral cephalograms were taken preoperatively and at two days, 5.5 months and 14.5 months postoperatively. The relevant skeletal points were traced and digitized to evaluate the skeletal changes postoperatively. The relapse rates were analyzed and compared statistically. Results: There was no statistically significant differences in postoperative stability between the two groups.(P<0.05) Conclusion: The biodegradable internal fixation device may make an effective device alternative to a metal internal fixation device for setback BSSO.

Large Piezoelectric Coefficient of high Quality Mn-doped (K0:5Na0:5)NbO3 Thick film by Using a Laser Doppler Vibrometer

Hae Jin Seog,박봉찬,조신욱,김태헌,Ill Won Kim,Aman Ullah 한국물리학회 2020 New Physics: Sae Mulli Vol.70 No.3

The development of lead-free ferroelectric and piezoelectric materials is required from the viewpoint of environmental preservation. Among various lead-free materials, (K0:5Na0:5)NbO3 (KNN) has attracted much attention due to its excellent ferroelectric and piezoelectric properties. In this study, high-quality Mn-doped (K0:5Na0:5)NbO3 (KNMN) films were deposited on Pt/TiO2/SiO2/Si substrates by using the sol-gel method. For various numbers of coating cycles; the KNMN films have thicknesses of around 0.8, 1.0, 1.5 and 2.0 m, respectively. The effective piezoelectric coefficient (d33;eff) of the KNMN films was analyzed using a home-made laser Doppler vibrometer that could measure large millimeter-scale areas. The average d33;eff of a 2-m-thick KNMN film was measured to be around 120 pm/V, which is comparable to those of lead-based materials and higher than those of other lead-free piezoelectric film alternatives.

Pure Ferroelectric Polarization of Lead-free Na0.5K0.5NbO3 Thin Films by Using the Double Wave Method

이해준,안창원,원성식,Achiri Tange,박봉찬,석해진,김일원 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.9

Na0.5K0.5NbO3 (NKN) thin films were grown on Pt(111)/Ti/SiO2/Si substrates by using RFmagnetron sputtering. We investigated the behavior of the ferroelectric polarization. Well-saturated P-V hysteresis loops were observed, but the P-V hysteresis loops were sometimes distorted and consisted of three roughly parallel components, such as ferroelectric, dielectric and conductive components. Correction methods were proposed to identify the undesirable components and the pure ferroelectric polarization components from the observed P-V hysteresis loops. A new polarization hysteresis loop measurement technique, the double wave method (DWM), was applied to NKN thin films to obtain pure ferroelectric polarization and elucidate the behaviors of the polarization components.

다발성 유아기 흑색 신경외배엽성 종양의 치험례

최병환(Byoung-Hwan Choi),박수원(Su-Won Park),장수미(Soo-Mi Jang),박봉찬(Bong-Chan Park),손한나(Han-Na Son),손장호(Jang-Ho Son),성일용(Iel-Yong Sung),김종렬(Jong-Ryoul Kim),조영철(Yeong-Cheol Cho) 대한구강악안면외과학회 2010 대한구강악안면외과학회지 Vol.36 No.5

A melanotic neuroectodermal tumor of infancy (MNTI) is a uncommon osteolytic pigmented neoplasm that primarily affects the jaws of newborn infants. Most patients (> 90%) present with the tumor in the first year of life. Approximately 65% form in the maxilla, 11% in the mandible, 5% in the brain and elsewhere. MNTI is normally benign, but up to 15% may recur and a few have metastasized. Approximately 200 cases of MNTI have been reported but only 2 of them presented as multifocal. A case of MNTI in a 7 month old boy was encountered. The chief complaint was maxillary anterior ridge swelling. The incisional biopsy findings were MNTI. Two months after the first operation, mild swelling of another site was observed. The infant was examined periodically since undergoing two procedures with no recurrence. This case demonstrates the possibility of a multicentric MNTI. We report a multicentric MNTI with a review of the relevant literature

임플란트 식립 부위의 골밀도 평가에 관한 연구

박수원(Su-Won Park),장수미(Soo-Mi Jang),최병환(Byoung-Hwan Choi),손한나(Han-Na Son),박봉찬(Bong-chan Park),김창환(Chang-Hwan Kim),손장호(Jang-Ho Son),성일용(Iel-Yong Sung),이지호(Ji-Ho Lee),조영철(Yeong-Cheol Cho) 대한구강악안면외과학회 2010 대한구강악안면외과학회지 Vol.36 No.5

Introduction: Bone density is one of the important factors for the long term success of endosseous implants. The bone density varies from site to site and from patient to patient. A preoperative evaluation of the bone density is quite useful to oral surgeons for planning dental implantation. More accurate information on the bone density will help surgeons identify suitable implant sites, thereby increase the success rate of dental implantation. This study examined the correlation between the bone density measured preoperatively by computed tomography (CT) and the implant primary stability measured by resonance frequency analysis. Furthermore, the effects of the implant sites, gender, age and generalized systemic disorder patients on the bone density and primary implant stability were examined. Materials and Methods: One hundred and fourteen patients were selected. None of the patients had undergone a tooth extraction or bone graft history in the previous year. Preoperatively, the patients underwent CT scanning to evaluate the Hounsfield unit (HU), and resonance frequency analysis(RFA) was used to evaluate the implant primary stability at the time of implant installation. All implants were 4.0 mm diameter and 11.5 mm length US II. All patients were recorded and the HU and implant stability quotient (ISQ) value were evaluated according to the sites, gender and age. Results: The highest HU values were found in the mandibular anterior site (827.6±151.4), followed by the mandibular molar site (797±135.1), mandibular premolar site (753.8±171.2), maxillary anterior site (726.3±154.4), maxillary premolar site (656.7±173.8) and maxillary molar site (621.5±164.9). The ISQ value was the highest in the mandibular premolar site (81.5±2.4) followed by the mandibular molar site (80.0±5.7), maxillary anterior site (77.4±4.1), mandibular anterior site (76.4±11.9), maxillary premolar site (74.2±14.3) and maxillary molar site (73.7±7.4). The mean HU and ISQ value were similar in females and males. (HU: P=0.331, ISQ: P=0.595) No significant difference was also found in the age group respectively. However, the correlation coefficients between the variables showed a closed correlation between the HU and ISQ value. Conclusion: These results showed close correlation between the bone density (HU) and primary stability value (ISQ) at the time of implant installation(Correlation coefficients=0.497, P<0.01). These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis.