8개 압저항 브릿지구조를 이용한 저 타축 감도 실리콘 가속도센서

徐熙敦,李榮泰,崔世崑 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1

A low off-axis sensitivity piezoresistive accelerometer has been presented. The off-axis sensitivity was reduced by arrangement of eight piezoresistors on two the beams. The structure and stress distribution of the accelerometer was optimized using FEM(finite element modeling) simulation. The dependence of sensitivity and resonance frequency were also simulated as a function of the beam length for a constant overall size(2000μm). Accurate thickness control of the beams was realized by the etch-stop techonology using SDB(silicon direct bonding) wafer SiO_(2) layer and RIE(reative ion etching) method. This method is relatively simple and very useful for fabrication of accelerometer.

지능화 진단 시스템개발을 위한 광바이오 텔레미트리 칩 제작

서희돈,박차훈,배용욱,최세곤 嶺南大學校 工業技術硏究所 1997 工業技術硏究所論文集 Vol.25 No.1

In this paper, we fabricated optical telemetry IC chip using CMOS process. The telemetering IC with the size of 4 ×4㎟ has the following functions: receiving of command signals, initialization of internal state of all functional blocks, decoding of subject-selection signal, time multiplexing of 4-channel modulated physiological signals, transmission of telemetry signal to extemal system, and auto power down control. The designed synchronous oscillator with low supply voltage dependence operates at a supply voltage from 4.6V-6.0V. And the nonlinearity error of PIM modulator was less than 1.2%FS. In order to demonstrate the principle operations of the implemented CMOSIC chip, the experiments of biotelemetry was performed by telemeter unit and external unit. Main features of this system are to select one of the 4 subjects, to enable measurement of biological signals using the same optical signal, and transmit them back to the extemal unit.

일괄공정 압저항혈 압력센서의 특성

서희돈,이동원,손미정,최세곤 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.1

This paper describes structural characteristics of three kinds of piezoresistive pressure sensors, which include wheatstone-bridge type, center-boss type and single-element type, fabricated on one-chip by batch process. In order to optimize device dimensions with respect to the desired characteristics, analytical formula and finited-element modeling(FEM) are used in design process. In experiments the pressure sensitivity of wheatstone-bridge type is about 2.2㎷/V·㎪. The fabricated center-boss pressure sensor has improved in the characteristics as linearity at low pressure, and sensitivity is about 2.415㎷/V·㎪. In single-element type with a four-terminal gauge using shear stress, the maximum sensitivity about 0.4㎷/V·㎪ appeared at the center of the diaphragm with the 3:1 of the length : width ratio. this type is very appropriate method to minimize the temperature dependance of the offset voltage and sensitivity, because the fabricated sensors reduce the offset of themal stress and mismatch of piezoresistros as compared with the wheatstone-bridge type.

Botrytis cinerea에서 분비된 Laccase의 정제 및 특성

고경희,김나진,한세영,서기림 가톨릭대학교 자연과학연구소 2003 자연과학논문집 Vol.24 No.-

Laccase는 페놀성 화합물과 아민 화합물등 많은 종류의 물질을 산화하는 특성 때문에 펄프 공업에서 펄프의 탈색에 이용되며 또한 염색 공업에서 폐염료의 분해에 이용된다. 본 연구에서는 Botrytis cinerea에서 분비하는 laccase를 분리 정제하여 몇 가지 효소의 특성을 조사하였다. 이 곰팡이의 배지로 Czapek-dox와 소량의 요소를 사용하여 비교적 높은 효소 활성을 얻을 수 있었다. 분비된 laccase는 이온교환 수지로 부분 정제하였으며 한 peak에서만 활성을 검출할 수 있었다. 효소의 특성으로 효소 활성이 가장 높은 pH는 2.6이었으며 최적 온도는 50℃이었다. 효소반응의 활성화 에너지는 일반적 산화반응의 값에 비하여 월등히 낮았다. 속도론적 상수 K_(m)값은 0.619mM이었다. 이 효소는 azide에 민감하여 낮은 농도에서 억제되었으며 cyanide에 의해서도 억제되었으나 azide보다 억제 효과가 낮았다. This study was performed to determine some physicochemical properties of laccase produced by Botrytis cinerea. This fungus was grown in liquid culture media of Czapek-dox broth plus urea. This media enhanced the production of laccase. Laccase was purified by precipitation and DEAE - Sepharose chromatography. Laccase activity could be detected at one peak, which meant the fungus excreted one kind of enzyme. Enzyme activity for oxidation of ABTS was highest at pH 2.6 and decreased with increasing pH. The optimum temperature of the enzyme reaction was 50℃ which was similar to those of laccases from other fungi and the average activation energy for laccase oxidation of 2,2'-azino-bis -(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was much lower than ordinary oxidation reaction without enzyme. The kinetic constant K_(m) was 0.619 mM using ABTS as substrate. Laccase was inhibited by azide and cyanide. NaN₃ was more inhibitory than NaCN.

근관치료용 전기모터의 회전 안정성 평가

박세희,서현우,홍찬의 大韓齒科保存學會 2010 Restorative Dentistry & Endodontics Vol.35 No.4

수종의 근관치료용 전기모터들의 반복사용과 시간에 따른 회전속도의 변화를 비교하여 근관치료용 전기모터의 회전 안정성을 평가하고자 하였다. 시간에 따라 변화하는 실제회전속도 및 전압과 전류를 측정하고, Student t-test를 통한 실제회전속도와, 반복측정분석을 통한 상관관계를 비교분석 하였다. 동일 종류의 전기모터들 사이의 모든 측정 결과들은 차이를 보이지 않았다. 모든 전기모터에서 반복사용과 시간의 흐름에 따른 회전속도의 변화는 차이를 보이지 않았다. 이상의 결과로, 본 실험에 사용된 모든 전기모터는 일정한 회전속도를 유지해야 하는 회전 안정성의 조건에 충족됨을 알 수 있으며, 반복사용과 시간에 따른 신뢰성 있는 회전속도와 안정적인 전압 및 전류의 유지가 가능하리라 생각된다. The purpose of this study was to evaluate a rotational stability of endodontic electronic motors by comparing the changes of rotational speed, depending on the number of usages and with/without static load. Twelve new endodontic electronic motors were used in this study. Non contact type digital tachometer was used for measuring the rotational speed of handpiece. True RMS Multimeter was used for measuring the voltages and the electric currents. All measurements were recorded every 10 seconds during 10 minutes and repeated 9 times. Five repetition was done per each electronic motor. To statistical analysis, student t-test, repeated measures and Scheffe's post-hoc tests were performed. In the same motor group, there was no significant difference in all measurements. In all groups, there was no significant difference in the amount of rotational speed changes depending on the number of usages and with/without static load. In the limitation of this study, the results showed that all kinds of endodontic electronic motors in this study had an established rotational stability. Therefore they could be safely used in root canal treatment with areliable maintenance of rotational speed, regardless of the number of usages and with/without load.

볼바 시스템을 이용한 기상측정오차 보정

이세희,서태일,조명우 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.2

The objective of this research is to develop a measurement error compensation method for On-Machine Measurement(OMM) process based on a closed-loop configuration. Geometric error of vertical machining center arc measured using ball-bar system, and probing errors are measured using master ball. The errors are represented using homogeneous trans-formation matrices and the closed-loop configuration method is applied to calculate 3-dimensional errors. To verify the effectiveness of the method proposed in this research, compensated results are compared to the data using CMM process, and the results are analyzed. The results show the proposed method can be applied in OMM process to make the measured data more reliable.

Carbachol에 의한 닭 췌조직내 nitric oxide synthase 활성 및 methylated arginine 함량변화

유세근,남석우,박승희,남태균,서동완,한정환,홍성렬,이향우 성균관대학교 약학연구소 1994 成均藥硏論文集 Vol.6 No.1

The role of nitric oxide (NO) in the regulation of exocrine secretion was investigated in chicken pancreatic tissues. Nitric oxide synthase (NOS) in the pancreatic tissues were Ca^2+-dependent form. Treatment of tissue with L-arginine (10 mM) or carbachol (10^-5 M) showed the increase of pancreatic exocrine secretion, but that of D-arginine (10 mM) did not. ^3H-citrulline formation, cyclic GMP level and methyl arginine contents in the homogenates of pancreatic tissues treated with carbachol were not affected. Although the action mechanism of NO in the pancreatic tissues remains unknown, NO apparently participates significantly in the overall control of pancreatic secretory function.

高精度의 DUAL-SLOPE 積分型 A/D 變換器 設計

박차훈,서희돈,최세곤 嶺南大學校 工業技術硏究所 1990 연구보고 Vol.18 No.1

In this paper, an effective method, which eliminates the error of the preamplifier, the integrator and the comparator, is proposed. An improved dual-slope integrating A/D converter, composed of the two-stage operational amplifier which is controlled by the control logic circuit switches and the variable ring counter, is for high accuracy. The results of computer simulation show that the conversion error is eliminated completely and the accuracy improved up to the level of the amplification of operational amplifier. These results satisfy the requirment of performance for the high accuracy dual-slope integrating A/D converter.

고감도 에어백용 실리콘 가속도센서의 설계

손미정,김경기,서희돈,최세곤 嶺南大學校 工業技術硏究所 1997 工業技術硏究所論文集 Vol.25 No.1

This paper presents the high sensitivity silicon piezoresitive accelerometer for possible use in an automotive airbag system. Two basic types of silicon piezoresitive accelerometers(bridge-type and cantilever-type)have some problems in the sensitivity and resonance frequency. The bridge-type has high resonance frequency and low sensitivity, but the cantilever-type has everse property. in order to improve the properties of the silicon piezoresistive accelerometer, we propose a new type of silicon accelerometer that have three beams. The proposed structure is that two beams are located at the each comer of the right side, and the other is at center of the left side. The optimized overallsize of the new type accelerometer is more smaller than two basic types of accelerometer. In the simulated reselts using analytical formelae and finite-element modeling(FEM), It's maximum stress is 26MPa and resonance frequency is 3250Hz for 50 G acceleration, respectively. The proposed structure is expected to be applied to much wider use automotive airbag application than the other structures.

소목(Caesalpinia sappan) 추출물의 Streptococcus mutans에 대한 성장, 산생성, 부착 및 비수용성 글루칸 합성 억제에 미치는 영향

유용욱,유현희,김윤정,유미선,서세정,이황,이흥수 대한구강보건학회 2003 大韓口腔保健學會誌 Vol.27 No.2

Streptococcus mutans is known as the causative bacterial playing the most important role in forming plaque and it is being noticed as major causative bacteria of dental caries. Therefore, development of more effective, substantial and safe preventive agent against dental caries and periodontal disease is honestly required. The present study was designed to investigate the effect of chloroform extract(CE), n-butanol extract(BE),methanol extract(ME) and water extract(WE) of Caesalpinia on the growth, acid production, adhesion, and insoluble glucan synthesis of Streptococcus mutans. The CE, BE, ME and WE decreased the growth and acid production of S.mutans than that of control, especially, the ME was more effective than other extracts. The effect of CE, BE, ME and WE on the adherences to saliva-coated hydroxyapatite bead(S-HA) were evaluated. At the concentration of 2,000 ㎍/㎖, the CE showed 32% rate of bacterial adherence to S-HA, whereas, other extracts of the same concentration producedgreater than 50% rate. The CE and BE were significantly decreased the reduction rates of water insoluble glucan formation from sucrose by crude glucosyltransferase of S.mutans. Thus, the application of C. sappan can be considered a useful and a practical method for the prevention of dental caries.