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사공건,김흥근,신광호 東亞大學校 2004 東亞論叢 Vol.41 No.-
This paper is focused on the improvement of reflection angle of an optical scanner by changing a shape of a torsion bar attached with an optical scanner reflector(mirror). In order to improve the light efficiency of the optical scanner by virtue of the magnetic effect, which tiny magnets are attached under both ends of the optical scanner reflector. and hence the optical scanner reflector was operated in relatively lower driving voltage. By changing the torsion bar's shape I type into S type, we've got the lower resonant frequency(32.5Hz) of an optical scanner than that of conventional one(50Hz). According to these results. The reflection angle of an optical scanner with magnets was much larger in the range of about 14.8° compared to one without a magnet. By making use of a magnetic actuator instead of a conventional electrostatic actuator, the optical scanner was less influenced from outdoor dust or moisture.
사공건,박연준 東亞大學校 2003 東亞論叢 Vol.40 No.-
In order to get the infrared ray radiator with high efficiency emission, the starting raw material Fez03 powder is heat-treated under the oxygen pressure log[PO_(2)]= -13 -15 at 800℃ for 2 hours. It has shown that the radiation rate was larger than 0.85 at the relatively high temperature(400℃), and almost kept constant the radiation rate with increasing the temperature from 50 to 400℃.
사공건,전홍배,허 진,김철한 東亞大學校 2001 東亞論叢 Vol.38 No.-
In this study, a measuring system of the initial permeability of soft-ferrite powder is developed by using a linear variable differential transformer's coil, and investigated about a demagnetizing factor. Magnetic powder is extensively used for a magnetic fluid and microwave absorber's materials etc.. In these applications, it is significantly important for us to measure an initial permeability of magnetic ceramic powder. Unfortunately, there are not any measuring equipment and method directly up to the present.
압전 세라믹(PZT)의 미세 구조에 미치는 첨가물의 효과
사공건,이수호 東亞大學校 大學院 1993 大學院論文集 Vol.18 No.-
In this paper, we have studied about the microstructure of the piezoceramics PZT that were added with some kinds of addiives, such as Niobium(Nb), Iron(Fe) or Manganese(Mn). The grain size of PZT ceramics was decreased with increasing the amounts of additive of Nb or Fe, while increased with increasing Mn. The curie temperature was changed slightly for the PZT ceramics containing FE?, which is not dependent on the amounts, but Nb? or Mn? ion added PZT was lowered. The resistivity was increased with increasing the amounts of Nb? additive, while decreased for Mn? additive.
Zn의 조성비에 따른 Pb(ZN Nb)O₃세라믹의 전기적 특성
사공건,이수호 東亞大學校 大學院 1994 大學院論文集 Vol.19 No.-
In this paper, Pb(Zn Nb₁)O₃ceramics were fabricated by the mixed oxide method. The sintering temperature and time were at 1,100(※) for 1(hr). According to the contents of ZnO₂, the depression of pyrochlore phase and its effects were investigated. As a results of the XRD and SEM experiments, the pyrochlore and second phase were increased with increasing the ZnO₂contents. Increasing the ZnO₂, the density was decreased.
세라믹/고분자 1-3형 복합압전체 초음파 트랜스듀서를 사용한 근접거리변동 측정용 레벨Limit스위치에 관한 연구
사공건,김흥근,박경일 東亞大學校 2003 東亞論叢 Vol.40 No.-
In this study, an ultrasonic transducer is fabricated with 1-3 type composite resonators. Pulse-echo responses of an ultrasonic transducer are investigated in underwater dependent on the variable designated water-level. LED Output signals of a level limit with changing a water level are obtained by the 1-3 type self-made ceramics/polymer composite transducer and electric measuring unit. LED is turned on at above the up-limit level with increasing a water level, and LED is turned on at less level than the down-limit level with decreasing a water level. There was good agreement between the virtual water level and output LED signal by using the self-made water-detecting system.
水中聽音器 응용을 위한 PZT/PMMA O-3 Composites의 誘電 및 壓電特性
鍵司空,趙玄哲 동아대학교 공과대학 부설 한국자원개발연구소 1990 硏究報告 Vol.14 No.1
In this paper, the composites with 0-3 connectivity were fabricated with PZT powder and PMMA for hydrophone applications. A modified cube model was derived by combining a series ad parallel for estimating the dielectric constant K_(33) values and piezoelectric constant(d_(33), d_(h)·g_(h)) changing the volume percentage of PZT. The difference of the dielectric and piezoelectric constant between the calculated and measured values became smaller at higher volume percentage of PZT. There was good agreement between the calculated and observed results for the 70 volume percentage of PZT and 30 volume percentage of PMMA at n=0.133.
면취기 시스템에 있어서 부하의 관성모멘트에 따른 가변 PID 일정 장력제어의 기초연구
사공건,허 진,전홍배,김철한 東亞大學校 2001 東亞論叢 Vol.38 No.-
In the winding system, the constant tension control is too important. In this study, we've investigated about a variable PID system as a function of a radius of winding roll. As a result, it was possible to measure a winding roll radius in the real time by making a mathematical model for measuring a winding roll radius. Finally, we've compared PID parameters as a function of winding roll radius after getting PID parameters in terms of the Ziegler & Nichols(ZN) method.
PZT-고분자 1-3-0형 복합압전체의 압전 및 음향특성
양윤석,사공건 東亞大學校 1999 東亞論叢 Vol.36 No.-
In this study, the piezoelectric ceramics PZT powder was synthesized by the Wet-Dry combination method. And a flexible 1-3-0 type composite was fabricated with piezoceramic PZT and Eccogel polymer matrix mixed the 3rd phase. Dielectric constant of 1-3-0 type composites was lower than that of single phase PZT ceramics. Thickness mode coupling factor kt(0.65) which was comparable with single phase PZT ceramics and mechanical quality factor Qm were about 6. These composites are considered as a good candidates for broad-band type transducer applications. The acoustic impedance of 1-3-0 type composites was lower than that of single phase PZT ceramics. Therefore, these composites would be better used for hydrophone applications.
신광호,사공 건 東亞大學校 大學院 1995 大學院論文集 Vol.20 No.-
In this paper, the optimum oxidation conditions in preparing the Cu-Zn ferrite wore investigated. The Cu-Zn ferrite powders which were synthesized by the coprecipitation method using FeCl( ) 6H( )O, CuCl( ) 2H( )O, ZnCl( ) and NaOH. These powders dependent on various heat treatments and oxidation conditions were prepared. The properties of Cu-Zn ferrite powders were examined by SEM, XRD, and VSM. The shape of powders obtained at 70(℃) were more spherical and fine-grained particles than that of powders prepared at 25, 50 and 60(℃), respectively. The saturation magnetization of the powders was not influenced by adding H( )O( ), but was influenced significantly by air oxidation. We have found that the saturation magnetization of Cu-Zn powders was dependent on the reaction time of air oxidation and was saturated in 6 hours.