펄스 레이더의 최대탐지거리 산출 모델연구

채광표,Chae, Kwang-Pyo 한국국방경영분석학회 1980 한국국방경영분석학회지 Vol.6 No.2

Computer model for calculating the maximum detection range of the pulse radar used for surface surveillance is developed, and the detailed procedures of each theoretical step are discussed. The quantity of radar antenna's receiving energy, transmitting energy and noise level are compared in this model. All the calculation steps are programmed in BASIC language. Finally, I have found the output of this model well matched with the some experimental results.

Cr과 Ti으로 치환환 Co 페라이트의 비교 연구

채광표,이영배 建國大學校 自然科學硏究所 2001 建國自然科學硏究誌 Vol.12 No.-

The CoCr_xFe_(2-x)O_4 and Co_(1-x)Fe_(2-2x)Ti_xO_4 ferrites have been fabricated by a sol-gel method. The crystallographic and magnetic properties of the Cr and the Ti substituted cobalt ferrites were investigated by means of x-ray diffraction. Mo¨ssbauer spectroscopy and vibrating sample magnetometry. The structure of all the sample is cubic spinel type and the formation of nano crystallized particles if confirmed. The Mo¨ssbauer spectra consist of two sextets due to Fe^(3+) ions at A and B sites for 0.0≤x≤0.6, while, a paramagnetic doulbet appears for 0.8≤x≤1.0 in CoCr_xFe_(2-x)O_4 and the magnetic hyperfine field decreases with increasing the Cr content. The relaxation spectra are shown at 0.8≤x≤1.0 in CoCr_xFe_(2-x)O_4. The IS and QS values are nearly constant, whereas H_H decrease with increasing Ti substitution in Co_(1-x)Fe_(2-x)Ti_xO_4. The coercivity decreases drastically, while, the saturation magnetization decreases linearly with increasing x in CoCr_xFe_(2-x)O_4. Whereas the saturation magnetization and the coercivity decrease with increasing x in Co_(1-x)Fe_(2-x)Ti_xO_4. Whereas the saturation magnetization and the coercivity decrease with increasing x in Co_(1-x)Fe_(2-x)Ti_xO_4.

Mo¨ssbauer 분광법에 의한 치환형 YIG, (Y, Gd)-(Fe, Al)-O계의 연구

채광표,이영배 건국대학교 1997 學術誌 Vol.41 No.2

치환된 Yttrium iron garnet Y2.6Gd0.4Fe5-xAlxO12계를 제조하여 X-선 회절법과 Mo‥ssbauer 분광법을 이용하여 결정구조와 초미세 상호작용과 연구하였고 초전도 양자 간섭장치(SQIID)를 이용하여 측정한 자기이력 곡선으로부터 거시적인 자기적 성질의 변화를 연구하였다. X-선회절 결과 각시료는 모든 조성비열 역에서 cubic garnet구조를 가지며 격자상수 값은 치환된 刃 이온의 증가에 따라 약간의 감소를 보였다. 또한 Neel 온도는 조성비 증가에 따라 증가하는 경향을 나타냈다. 외부자기 장에 대한 자화곡선으로부터 얻어진 포화자화값(Ms)은 조성비에 따라 감소경향을 보였다. The substituted yttrium iron garnet system Y2.6Gd0.4Fe5-xAlxO12(x=0.2, 0.4, 0.6) have been investigated by means of X-ray diffractometry, Mo‥ssbauer spectroscopy and SQUID. The specimens have been found to be the cubic garnet structure in the entire range compositions. The lattice constants slightly decreased and the Neel temperature increased with Increasing Al ions contents. From the Magnetization curve measured by means of SQUID, the saturation magnetization Ms decreased with x.

Co-Ti 치환 페라이트 분말의 열처리 효과 연구

채광표,김원기 建國大學校 自然科學硏究所 2000 建國自然科學硏究誌 Vol.11 No.-

Co-Ti substituted ferrite powders, Co_(1+x)Fe_(2-2x)Ti_xO_4, have been prepared by the sol-gel method. The annealing effects at 600℃ and 800℃ of the samples have been investigated by means of x-ray diffraction. Mo¨ssbauer spetroscopy and vibration sample magnetometry. The x-ray diffractions of all samples with various compositions clearly indicate the presence of spinel structure. The crystallize temperature increased with annealing temperature. The Mo¨ssbauer spectra could be fitted as the superposition of two sextets due to Fe^(3+) at A-site and B-site. IS and OS values were nearly constant with substituted Co=Ti contents, whereas H_(h∫) of B-site decreased with increasing Co=Ti substitution in Co_(i+x)Fe_(2-2x)Ti_xO_4. The area rationof A-site increased with increasing annealing temperature. The saturation magnetization increased whereas the coercivity decreased with increasing annealing temperature. The magnetic behaviour of powders showed that the saturation magnetization and the coercivity decreased with increasing x in Co_(1+x)Fe_(2-2x)Ti_xO_4.

Popularization of Science and Technology : what informal and nonformal education can do?

채광표 한국과학교육학회 1989 한국과학교육학회지 Vol.9 No.2

이 글은 1989년 9월 4일부터 9일까지 홍콩대학에서 있었던 국제회의 결과 보고서이다. 유네스코가 후원한 이 회의에는 20여개국에서 28명이 참석하였으며, 모든 참석자가 country paper를 발표하고 주제에 관련된 토의를 거쳐 최종 보고서를 작성하였다. 학교교육 밖에서 과학기술의 대중화를 위한 방안을 모색해보는 새로운 내용이라서 그 전문을 소개한다.

자연과 보조 교과서 ' 실험 관찰 ' 의 활용 실태와 개선 방안 연구

채광표 한국과학교육학회 1990 한국과학교육학회지 Vol.10 No.1

To achieve the aim of science education, it is known that warious teaching and learning materials should have to be used. As a sub-textbook for primary science education, 'Sil Hum-Kwan Chal (Experiment and Observation), teaching and learing material are developed and using now in school. This material have following characteristics; (a) Soruce-book contains reading materials for additional information, various pictures to enirich the science concepts, and supplementary and enrichment activities. (b) Work-book consists of the detailed procedures of activities of experiments presented in the textbook, student can record the experimental procedures and results. (c) Operational manuals provide operation techniques for experimental equipments which are used in science class. In this study the using status are surveyed for the 3rd grade of primary school, and based on this survey the improvement plan are discussed in view of design, quantity and utility, of sub-textbook.

Sol-gel법에 의한 Mn - Zn Ferrite 박막의 자기적 특성

채광표,이재광,이원민,김정훈,김중석,정소민,이영배,최승한 한국자기학회 2004 한국자기학회 학술연구발표회 논문개요집 Vol.14 No.1

Effective Charge Number and Critical Current Density in Eutetic SnPb and Pb Free Flip Chip Solder Bumps

채광표,Chae, Kwang Pyo The Korean Welding and Joining Society 2005 대한용접·접합학회지 Vol.23 No.5

The effective charge number and the critical current density of electromigration in eutetic SnPb and Pb Free $(SnAg_{3.8}Cu_{0.7)$ flip chip solder bumps are studied. The effective charge number of electromigration in eutectic SnPb solder is obtained as 34 and the critical current density is $j=0.169{\times}({\delta}_{\sigma}/{\delta}_x})\;A/cm^2,\;where\;({\delta}_{\sigma}/{\delta}_x})$ is the electromigration-induced compressive stress gradient along the length of the line. While the effect of electromigration in Pb free solder is much smaller than that in eutectic SnPb, the product of diffusivity and effective charge number $DZ^{\ast}$ has been assumed as $6.62{\times}10^{-11}$. The critical length for electromigration are also discussed.

치환된 YIG, Y Gd Fe In O(x=0.2, 0.4, 0.6)계에 관한 Mossbauer 분광학적 연구

이성호,김한석,이영배,채광표 建國大學校基礎科學硏究所 1995 理學論集 Vol.20 No.-

치환된 yttrium iron garnet Y₃-xGdxFe4.8In0.2 O₁₂계를 제조하여 X-선 회절법과 Mossabuer분광법을 이용, 결정구조와 초미세 상호작용을 연구하였다. X-선 회절 실험결과 결정구조는 모든 조성비 영역에서 cubic garnet 구조를 가지며 격자상수는 조성비 x가 증가함에 따라 약간씩 증가하였다. Mossabuer spectrum은 octahedral(a) sites과 두개의 tetrahedral sites(d, d´)의 Fe3+ 이온에 의한 세 개의 Zeeman pattern이 나타났다. 일차적으로 각 이론들의 site 선호도를 고려하여 이온 분포식을 결정하고, 이를 다시 이론적 격자상수 및 실험치와 비교 확인하였다. The Y₃-xGdxFe4.8In0.2 O₁₂(x=0.2, 0.4, 0.6) systems have been investigated by means of X-ray diffractometry and Mossbauer spectroscopy. The specimens have been found to be the garnet structure in the entire composition range, and the lattice constants slightly increased with increasing x. The Mossbauer spectrum consists of three Zeeman sextets at room temperature, one due to the Fe3+ on octahedral(a) sites and the others due to the Fe?? on the tetrahedral sites(d, d´), respectively. We firstly have set up the cation distribution considering the site perference on the ions, which has again been compared with the theoretically as well as experimentally confirmed lattice parameters.

Orthoferrite LaFeO₃에서의 Mn 치환 효과

채광표(Kwang Pyo Chae),이성환(Sung Hwan Lee),이성호(Sung Ho Lee),이영배(Young Bae Lee) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.2

Crystallographic and magnetic properties of the Mn-doped orthoferrite LaFe_(1-x)Mn_xO₃ (0.0≤x≤0.4) system have been investigated by means of x-ray diffractometry, Mossbauer spectroscopy, vibrating sample magnetometer and superconducting quantum interference device. The structure of the system was found to be orthorhombic distorted perovskite structure. At room temperature, the Mossbauer spectra for x=0.0 consists of one Zeeman sextets from Fe³+ ions at octahedral sites. The Mossbauer spectra of two Zeeman sextets (x≤0.1) change one Zeeman sextets and a paramagnetic doublet (x=0.4). The saturation magnetization increases but the coercivity decreases with increasing x in LaFe_(1-x)Mn_xO₃.