薄板狀水晶振動子의 두께振動

南孝悳 영남이공대학 1977 論文集 Vol.6 No.-

A mathematical theory is presented giving the relations between the clastic constants and the frequencies of piezoelectric vibration for an infinite plate of homogeneous but aeolotropic materail. The results of this calculation is then applied to determine the three mutually orthogonal vibration modes of quartz crystal, one of the above throe modes is generally piezoelectrically excitable.

부분수산법에 의한 PZT 세라믹스의 저온소성과 전기적 제특성

남효덕,이희영 한국전기전자재료학회 1993 電氣電子材料學會誌 Vol.6 No.2

두가지 부분수산법, 즉 부분수산법(1)과 수정된 부분수산법에 의해 합성한 미분말을 사용하여 PZT 세라믹스를 저온소성하고 그 전기적 제특성을 조사하였다. 두가지 부분수산법에 의해 합성한 분말의 소결거동을 조사해본 결과 고상반응법보다 훨씬 낮은 소결온도인 950.deg.C에서도 단일상의 페로브스카이트상이 얻어지고 치밀화가 이루어졌을 뿐만 아니라 비유전율, 전기기계 결합계수, 압전정수 등 유전 및 압전특성이 고상반응법에 비해 손색이 없었다. 특히 두가지의 부분수산법에 의해 얻어진 PZT 세라믹스는 물리적 전기적 제특성이 서로 비슷하게 나타났으며 이 결과로부터 부분수산법(1)에서 수반되는 ZTO 분말을 따로 합성하는 공정이 불필요한 수정된 부분수산법이 편리함을 알았다.

옥소화합물 CTR의 제작 및 그 전기적 특성

남효덕 嶺南大學校 工業技術硏究所 1981 연구보고 Vol.9 No.2

(Ag ₁-??Cu??)₂Cdl₄(0 ≤x≤1) critical temperatue resistances (CTR) were fabricated by sintering the mixture of Cul, AgI and CdI₂ at 260℃ for one hour. The electerical characteristics of the CTR were also investigated. The x-dependent critical temperature for the CTR was between 30 and 60℃ and Φ value of the fabricated CTR was about 3.4 for x=0.5 sample.

입자배향(Pb, Ba, La) $Nb_2O_6$ 압전세라믹스의 제작 및 그 전기적.광학적 특성

남효덕,조상희,영전방유 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.3

KCI을 사용한 용융염합성법에 의해 침상형$(Pb_{1-x}Ba_x)_{1-y}La_{2y/3}Nb_2O_6$ (PBLN)분말을 합성하고 합성분말의 형상에 미치는 Ba 및 La 치환의 영향을 조사하였다. 또 이 침상형 분말을 사용하여 doctor-blade법 및 hot-press 법에 의해 입자배향 세라믹스를 제작하고 유전적, 압전적, 광학적 성질을 조사하였다. 얻어진 PBLN 분말의 형상 및 입자배향 PBLN 세라믹스의 전기적 특성은 분말합성시의 열처리조건과 Ba 및 La 치환량에 따라 현저히 달랐다. 특히 PBLN 세라믹스의 유전율 및 전기기계결합계수는 입자배향 세라믹스 제작시의 가압방향에 따라 뚜렷한 이방성을 나타내었다. Ba or La-Substituted lead niobate $(Pb_{1-x}Ba_x)_{1-y}La_{2y/3}Nb_2O_6$(PBLN), powders having needle shape are prepared by flux method using KCl and the effect of Ba or La substitution on morphology of obtained powders is examined. From these needle shape powders, grain-oriented ceramics are made by doctor-blade method and two-stage hot-pressing technique. The dielectric, piezoelectric and optical properties of the ceramics are also investigaated. Heating condition and the amount of substituted Ba or La have remarkable effects have large anisotropy in both permittivity and coupling factor depending on the pressing direction.

유한요소법과 경계요소법을 이용한 음향트랜스듀서의 음향방사 특성 해석

남효덕,서희돈,고영준,장호경 嶺南大學校 工業技術硏究所 2001 工業技術硏究所論文集 Vol.29 No.2

The acoustic characteristics of the acoustic transducer was simulated by using the finite element method(FEM) and boundary element method(BEM). After meshing the inside closed boundary of the acoustic transducer, pressure gradients, isobaric lines, directivity characteristics and acoustic impedances were calculated by using the FEM and characteristics of 3-D free field sound pressure, directivity characteristics and radiation efficiency were simulated by using the BEM. It was shown that the usefulness of the design and the fabrication for the acoustic transducer from the results.

UHF 대역의 휴대전화 착신기능 제한 시스템의 설계 및 제작

남효덕,김종석,김병철 嶺南大學校 工業技術硏究所 2001 工業技術硏究所論文集 Vol.29 No.2

As demands grow for restricting use of cellular phones by attendants in the public places such as conference rooms, churches, and playhouses etc., a call blocking system against UHF band cellular signals is developed for other attendants who do not want to be disturbed by the phone rings. The idea of preventing a cellular phone from ringing was developed from the fact that the system radiates interferent signals having 0.1 to 0.05 watts of CW wave, makes it possible to increase the error rates of output signal of PSK modem, and hence makes the cellular phone Impossible to receive the right call signal. The system designed in this study was set up and tested in the several public places and found itself very effective.

용융염합성법에 의한 $Sr_2(Ta_{1-x}Nb_x)_2O_7$ 세라믹스의 저온소성과 유전특성

남효덕 한국전기전자재료학회 1995 電氣電子材料學會誌 Vol.8 No.2

Solid solutions Sr$_{2}$(Ta$_{1-x}$ Nb$_{x}$)$_{2}$O$_{7}$, (x=0.0-1.0), composed of strontium tantalate(Tc=-107.deg. C) and strontium-niobate(Tc=1342.deg. C) were prepared by the conventional mixed oxide method and the flux method(molten salt synthesis method). Phase relation, sintering temperature, grain-orientation and dielectric properties for sintered ceramic samples were investigated with different compositions. Both Curie temperature and dielectric constant at Curie temperature were increased, and sintering behavior and the degree of grain-orientation were improved with the increase of Nb content. The single phase Sr$_{2}$(Ta/sib 1-x/Nb$_{x}$)$_{2}$O$_{7}$ powder was synthesized by using the flux method at lower temperatures, and sintering temperature was also reduced by using the flux method-derived powder than using the mixed oxide-derived powder. Sintering characteristics and dielectric properties of the specimens prepared by the flux method were better than those derived through the conventional mixed oxide method.thod.hod.

전도성 충전물을 이용한 도전성 판재의 제조기술 개발

남효덕,이현석,박봉국 嶺南大學校 工業技術硏究所 2003 工業技術硏究所論文集 Vol.31 No.1

As an effort of developing efficient materials for shielding EM waves, a fibrous sheet for shielding EMI is developed by adding conductive filler to fibrous sheet during hardening process. From the aspect that the conductivity is inversely proportional to the square value of the length of added material, the conductive filler is fabricated by electroless plating with nickel and copper to the polymer textile power which has very high anisotropy. The conducting sheet was also fabricated by applying proper amount of highly efficient conductive filler to the fibrous sheet. The results obtained by measuring the shielding characteristics of 1㎒∼1㎓ frequency range showed the EMI suppressing effectiveness of 10∼20 ㏈.

Nd8Fe86-xNbxB6 (x = 0, 1, 2, 3) 초미세립복합상 영구자석의 자기적 특성 연구

남효덕,김성준,박경석,김응찬 한국물리학회 2009 새물리 Vol.58 No.2

A precisely refined Mössbauer study revealed that the intergranular phase that forms between the α-Fe and the Nd2Fe14B phases in NdFeNbB alloys plays a significant role in the magnetic properties. By the addition of Nb into the Nd8Fe86B6 composition, the coercivity was found to be increased by 25% due to a refinement of the average grain size of both the soft and the hard magnetic phases, which decreased from 50 nm for virgin Nd8Fe86B6 to 25 nm for Nd8Fe86B6 alloys. Nb addition was confirmed to stabilize the Nd8Fe86B lattice by preventing thermal vibration of the sites in the Nd8Fe86B lattice at which Fe atoms were replaced by Nb atoms. The enhanced coercivity originated the exchange hardening of the soft and amorphous phases surrounding the hard magnetic Nd8Fe86B crystals. NdFeNbB 합금에서 α-Fe와 Nd2Fe14B상 사이에 형성된 입간결정립이 초미세립 복합상의 자기특성에 큰 영향을 미치고 있음을 정밀한 뫼스바우어 분광학 분석을 통해 조사하였다. Nd2Fe14B+α-Fe 재료에서 얻은 최대자기특성은 Br = 9.791 kG, iHc = 5.565 kOe, 그리고 (BH)max = 14.61 MGOe였고, 이 경우, 각 존재상의 부피분율은 α-Fe; 24.2%, Nd2Fe14B; 53.1%, 입자간; 22.7 %였음을 확인하였다. Nd8Fe86B6 조성에 첨가한 Nb는 평균 입자 크기를 50 nm에서 25 nm로 정제함으로써 보자력을 25% 정도 증가시켰다. 첨가원소 Nb의 역할은 Nd2Fe14B 격자의 열적진동을 억제함으로써 Nd2Fe14B 격자를 안정화시킴은 물론 연자성상 α-Fe의 교환경화를 일으킴으로 인해 보자력을 증가시켰다.

水晶의 彈性 및 壓電氣係數

南孝悳 영남이공대학 1976 論文集 Vol.5 No.-

The transformation theory of elastic and piezoelectric constants of quartz cystal is presented by the symmetrical properties of 2-fold to x axis and 3-fold to z axis. The results of this calculation will be applied to analysis of various vibrational modes and their mutual interference.