가燒溫度가 PZT의 格子常數 및 電氣的性質에 미치는 영향

鄭守泰 釜山工業大學校 1986 論文集 Vol.28 No.2

The effects of calcining temperature ranging from 700℃∼1100℃ on the lattice constant and electrical properties of Pb(??)O₃have been studied. As the samples sintered at 1200℃, the lattice constant, a decreased with calcining temperature up to 900℃ anc increased beyound that temperature, whereas the lattice constant, c was almost unaffected by the calcin-ing temperature. Thus the tetragonality(??) increased upto 900℃ and decreased above that temperature. The planar coupling factor and ?? Pr of sample increased proportionally with the value of ??.

PZT세라믹스에 있어서 강유전성 분역배열의 전계의존성

정수태 釜山工業大學校 1990 論文集 Vol.32 No.-

Electric field dependences of ferroelectric domain orientation are investigated on the morphotropic phase boundary of PZT ceramics. The 90。domain decreased the dielectric constant and the orientation of it linearly increased with the electric field, while the 180。domain increased the dielectric constant and the orientation of it rapidly increased upto coercive field. The behaviour of dielectric constant under applied voltage is affected by both 90 and 180。domain, that under removed voltage is only affected by 180。domain. The electric field dependences of the crystal orientation factor and the piezoelectric constant(k??, d??, g??) are dominated by the 180。domain.

厚膜化 ZnO가스 檢知素子의 製造및 그 特性

鄭守泰,柳志久 釜山工業大學校 1981 論文集 Vol.22 No.2

ZnO 와 Cr₂O₃의 混合母材에 Pt, 씨리카졸을 첨가한 가스 檢知素子를 厚膜技術에 의하여 製造하였다. Pt 0.5wt% , 씨리카졸 10wt% 정도 첨가할때 感度가 向上되었으며 최저 燒結條件은 空氣中 800℃에 1시간, 素子에 유지되는 최적 溫度는 320℃ 부근이었다. 제조된 素子들은 ?? 가스에 높은 感度을 보였다. ZnO and Cr₂O₃ based Gas sensor were manufactured by using of thick-film technology and their characteristics were investigated. Adding about 0.5wt% Pt, 10wt% Silicasol to the mixing of ZnO and Cr₂O₃improved sensitivity. The optimum fired condition was about 1 hr, 800℃ in air and heating temperature of thick-film Gas sensor was about 320℃. Thick-film Gas sensor showed a good sensitivity for ?? Gas.

ZnO 세라믹 바리스터의 電位障壁

鄭守泰 釜山工業大學校 1983 論文集 Vol.24 No.2

The potential barrier of grainboundary is very important in ZnO ceramic varistors and other polycrystalline semiconductors. The general conduction mechanism of ZnO Ceramic varistors is analized by them. In this paper, I used the current transport equation and calculated by the log (G·k·T/q)-1/T curve obtained from J-V data. This method was more useful than 1/C²-V curve and the potential barrier height of grainboundary was 0.76[eV].

ZnO varistor에 대한 ohmic 영역의 전도현상

鄭守泰 釜山工業大學校 1984 論文集 Vol.26 No.-

The conduction mechanism of ohmic region on ZnO varistor was explained by the thermionic emission which was due to rising of forward voltage. In the ohmic region, the current density was proportional to (applied voltage)?? and the forward potential barrier was gradually decreased with rising applied voltage. The value of calculated capacitance agreed with measuring data.

엔진회전계의 전달함수 산정을 위한 개루우프(Open loop) 시험

鄭泰相,鄭鳳守,金明奎 진주산업대학교 농업기술연구소 1993 農業技術硏究所報 Vol.6 No.-

농용엔진이 부하변동에도 일정한 회전수를 유지할 수 있는 제어기법을 개발코자, 개루우프 시험에 의해 회전계의 동특성을 이용하여, 통계적으로 산출하여 엔진회전계 방정식을 정리하였으며, 그 결과는 아래와 같다. 1. 엔진회전계의 전달함수와 이산시계열 방정식을 이론과 실험결과를 이용하여 정립하였다. 2. 실제 엔진회전수와 전달함수를 이용한 추정회전수가 일치하였다. This research was carried out to find out a revolution equation of the engine system using regression analysis. The dynamic characteristics of revolution part of an engine were measured by open loop test. Thus, a transfer function and a discrete-time equation relating the engine speed as ouput of the control system to the torque equivalant to throttle opening angle as imput of the control system were derived from the results of the open loop test. 1. The transfer function and the discrete time equation of the revolution system of the engine were derived from the control theory and experimental results. The calculated and measured engine speed were in good agreement.

Pb(Ni₁/₃ Nb₂/₃)O₃ 세라믹스에 있어서 페롭스카이트상의 생성과 유전특성

정수태,류지구,김강언 釜慶大學校 1997 釜慶大學校 論文集 Vol.2 No.2

The reaction sequences of the 3PbO-NiO-Nb?O? [PNN1] and 3PbO-NiNb₂O? [PNN2] system and their dielectric properties were investigated. The pyrochlore phase of PNN1 formed in the order of Pb₃Nb₂O?, Pb?Nb₄O₁?? and Pb₃Nb₄O₁₃ according to increasing of a reaction temperature, and that of PNN2 formed only a Pb₃Nb₄O₁₃. The perovskite phase of Pb(Ni₁/₃Nb₂/₃)O₃[PNN] formed at 920℃ through the diffusion of NiO into the pyrochlore phase of Pb₃Nb₄O₁₃ on both PNN1 and PNN2, but PNN1 showed about 40% of the pyrochlore phase and PNN2 showed about 10% of it.When the samples sintered for 1 hour at 920℃ after calined for 1 hour at 850℃, the PNN1 sample showed yet about 18% of pyrochlore phase, While the PNN2 sample showed 100% of perovskite phase. The PNN2 sample(pyrochlore phase free) had a 1.5 times of maximum dielectric constant and a 0.1 times of dissipation loss(room temperature) compared to the PNN1 sample(pyrochlore phase not free)

0.5(PZ-PT)-0.5PNN계 세라믹스에 대한 소결특성과 압전상수의 온도특성

정수태,이우일 釜山工業大學校 1991 論文集 Vol.33 No.-

The sinteristics and the temperature dependency of piezoelectric constants of the 0.5(PZ-PT)-0.5 PNN system are investigated as a function of PT. The pyrochlore phase which is detrimental to both the sinteristics and the piezoelectricites, is formed at above 600℃ with the exothermic reaction and is nearly disappeared at about 870℃ with the endothermic reaction. A expansion of the calcined samples due to the formation of the pyrochlore phase materials, but the sintered samples are shrunk about 14% for the forming sample and those are shown a stable perovskite phase. The samples of the morphotropic system(PT=0.65-0.68) have a higher piezoelectric constant, however the temperature dpendency of their piezoelectric constant are bad. The degree of temperature dependency of the piezoelectric constant is shown in the order of morphotropic, rhombohedral and tetragonal phase. From a temperature dependency of piezoelectric constant point of view, PT=0.7 system is suitable for the piezo-actuator materials.

급성 심근경색 : Gd-DTPA 조영증강 자기공명영상 Gd-DTPA Enhanced Magnetic Resonance Imaging

정경일,김제현,이창호,이영주,김한수,소동문,이영돈,박경주,왕희정,탁승제,이철주,김선용,김옥화,임태환,문창현,최병일,서정호 아주대학교 의과학연구소 1996 아주의학 Vol.1 No.1

This study was undertaken to determine the value of gadolinium dimeglumine (Gd-DTPA) enhanced MRI in the diagnosis of acute myocardial infarction. Seven cats were subjected to 2 hours of left anterior descending coronary arteryocclusion (group 1) and 8 cats to 1 hour of occlusion (group 2). Reperfusion was followed by taking Tl-weighted MR images at 5, 15, 30, 45, 60 minutes after Gd-DTPA (0.2 mmol/kg) injection. Myocardial enhancement patterns were categorized into three zones (central ischemic, peripheral ischemic, and normal) or two zones (ischemic and normal) and the presence of injured myocardium in each zone was confirmed by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Signal intensity (SI) of each zone was evaluated relative to back muscle in regard to its chronological changes and difference among the zones. Group 1 displayed three zones of enhancement in 6 cats whereas 1 cat in group 1 and all in group 2 showed two zones of enhancement. Intermediate SI central zone was compatible but smaller than TTC nonstained area, and determined to be a persistently occlusive injury. High SI peripheral zone in group 1 and high SI ischemic zone in group 2 were stained and determined as reperfused injury although reversibility was not definite. The peak SI, occurring 15 minutes after Gd-DTPA injection, of 2.47±0.48 at peripheral zone was greater than that of 1.66±0.36 at central zone in group 1 and of 1.81±0.41 at ischemic zone in group 2 (p < 0.05). SI of injured myocardium increased more rapidly and decreased more gradually than that of normal myocardium. That the features of SI change with time in injured myocardium was compatible with the results of other studies using different contrast agents. Gd-DTPA enhanced MRI differentiated persistently occlusive injury as central intermediate SI, and reperfused injury as homogenous high SI, with the maximal contrast between the two at 15 minutes after contrast injection, thus indicating the value of Gd-DTPA enhanced MRI in the diagnosis of acute myocardial infarction.

하악두 골절의 미진한 처치로 인해 condylar prostheses까지 사용한 증례

정훈,이태영,성춘수 大韓顎顔面成形再建外科學會 1994 Maxillofacial Plastic Reconstructive Surgery Vol.16 No.1

It is a generally known fact that the patient can experience mouth opening limitation, mandibular deviation and malocclusion as a result of injury of tissues around the articular disc and complications even after successful open reduction surgery for fractured mandibular condyle. We have experienced a rare case of reconstruction using metallic condylar prostheses for a patient with complications resulted by unsuccessful management of fractured mandibular condyle. The case strongly suggested to us that careful selection of treatment methods should be taken for patient with fractured mandibular condyle. Accordingly, we are presenting a case in conjunction with reviews of fractured mandibular condyle.