전로용 MgO-C질 내화벽돌의 손상요인

김의훈,오영우,이철수,김종성,김종희 한국세라믹학회 1986 한국세라믹학회지 Vol.23 No.1

It was the first time the MgO-C brick was developed for the lining materials in the hot spots in electric are furnace in 1972. MgO-C brick is high registant to thermal and structural spalling. Futhermore for the reason that carbon is hard to react with slag and MgO is high fireproof MgO-C brick shows a high corrosion registance to slag attack compared with conventional basic refractories. Owing to their excellent properties the use of MgO-C refractories are being developed widely in the field of shaped refractories and even in that of monolithic refractories. In this paper the oxidation of carbon the infiltration of slag into the brick texture and effects of additions were investigated. The results obtained were as follows : 1) The use of fused MgO-clinker and high purity carbon as raw materials increased the corosion registance and hot modulus of rupture of MgO-C brick. 2) As the oxidation reaction of the carbon proceeded the slag infiltrated into the brick texture. And then the slag components reacted with the MgO grains and formed low melting point compounds particulary CaO.MgO.$SiO_2$ and 3CaO.MgO.$2SiO_2$ that resulted in the wear of the brick. 3) It is recongnized the Al, Si, $B_3C$ effects on the oxidation registant properties of MgO-C brick by contribu-ting to the decrease of permeability according to the formation of $Al_4C_3$, SiC, $B_2O_3$ and the decrease of open pores relating to the formation of MgO.Al2O3, $SiO_2$, 3MgO.$B_2O_3$ at the decarbonized layer.

광음효과에 관한 이론적 연구

이창효,김의훈 漢陽大學校 基礎科學硏究所 1988 基礎科學論文集 Vol.7 No.-

본 논문은 음향임피던스의 개념을 사용하여 매우 낮은 광단속진동수에 대해서도 적용될 수 있도록 Rosencwaig-Gersho이론을 수정한 것이다. 이 결과는 실험치와 잘 일치하였으며, 특히 매우 낮은 광단속진동수에서의 광음향신호 세기가 유한한 값을 가져야 한다는 사실을 잘 설명해 주고 있다. 또한 음향임피던스가 무한한 값으로 주어질 때 본 이론은 Rosencwaig-Gersho 이론과 완전히 일치하였다. In this work, we modified the Rosencwaig-Gersho theory using the concepts of acoustic impedance in order to apply the theory to the range of low chopping frequencies. Our theory is verified by experimental results, explainning well the fact that the intensity of photoacoustic signal at the low limit frequency must be finite. When the acoustic impedance is infinite, this theory coincides with the Rosencwaig-Gersho theory.

薄膜의 두께가 光音響信號에 미치는 영향

李昌孝,金義薰 漢陽大學校 基礎科學硏究所 1984 基礎科學論文集 Vol.3 No.-

시료의 두께가 광음향신호에 미치는 영향을 이론 및 실험적으로 고찰하였고, 특히 단속광을 투명한 배경물질을 통하여 시료에 직접 조사시켜 불필요한 잡음을 제거함으로써 종전의 방법을 개량하였다. 이 경우에 대해 이론적으로 구한 신호세기는 Rosencwaig-Gersho의 이론과 유사하였다. 금속 박막에 대한 광음향신호 세기는 박막의 두께가 증가함에 따라 지수적으로 증가하여 극한값에 도달하는데 이 극한값은 모든 금속박막에 대해서 동일함을 할 수 있었다. 이 사실들은 실험결과와 잘 일치하였다. 광흡수계수의 값에 따라 신호세기가 명확히 달라지는 두께는 100Å~1000Å 사이의 범위로, 이 사실은 금속 박막의 광흡수계수 측정에 이용할 수 있을 것이다. The purpose of this paper is to study experimentally and theoretically the influence of the thickness of the thin film on photoacoustic signals. The chopped light beam is used to illuminate the surface of a sample in the cell through transparent backing material in order to eliminate background noise. The theoretically calculated signals agree well with the Rosencwaig-Gersho theory which pradicts the amplitude and phase of signal wave at the inside of the cell. It is found that the signal intensity of the metal film increases exponentially as the thickness of the film increases, reaching the limiting value and also that the limiting value turns out to be the same regardless of kinds of metal films used, which agree well with the experimental results. It is also found that in the rage of 100Å~1000Å in thickness the signal intensity of films shows a marked optical absorption coefficent dependence. This result can be utilized for the measurement of the optical absorption coefficients of metal films.

비정질 실리콘 박막의 안정성 연구

김의훈 漢陽大學校 自然科學硏究所 1996 自然科學論文集 Vol.15 No.-

PECVD를 이용하여 불소가 첨가된 비정질 실리콘 박막과 이온 샤우어 도핑을 이용하여 완전 보상된 비정질 실리콘 박막을 제작하여 전기적 특성을 조사하엿다. a-Si : H : F 박막에서 SiF₄유량이 증가하면 SiH₂모드의 크기가 증가하고, 전기전도도와 광감도는 감소한다. 이온 도핑 방법에 의해 제작된 완전 보상형 비정질 실리콘 박막의 보상 조건은 P이온 도즈량이 5.9×??㎠일 때, B이온 도즈량이 4.9×??㎠이다. 완전 보상형 비정질 실리콘의 상온에서의 전기전도도는 ∼1.6×??/cm이고, 잔여광전기전도도(Persistent Photoconductivity ; PPC)는 빛 조사시간에 따라 증가하였다. We have studied the electrical properties of a-Si : H : F films by PECVD and compensated a-Si : H films by ion shower technique. With increasing SiF₄ flow rate, SiH₂mode intensity increased and conductivity and photosensitivity decreased. Fully compensated a-Si : H films prepared by incorporations of both 5.9×??cm₂ PH₂/H₂ plasma ions and 4.9×??㎠ ??/H₂ plasma ions. At room temperature, dark conductivity of fully compensated a-Si : H film is ∼1.6×1??/cm and persistent photoconductivity increased with light exposure time.

고온 초전도체 CYBa₂Cu₃O의 초전도성에 관한 연구

김재욱,김채옥,김의훈 漢陽大學校 基礎科學硏究所 1993 基礎科學論文集 Vol.12 No.-

고온 초전도체 ??의 X-선 회절 측정은 실온에서 수행되었으며, 수송 임계전류밀도와 저항측정은 각각 77K와 80∼160K범위의 온도에서 조사되었다. 또한 자화율과 자기임계전류밀도의 값은 30K의 온도에서 자기 이력곡선으로 부터 구하였다. X-선 회절 무늬의 분석으로 부터 초전도체의 결정구조는 직방정계임을 알 수 있었으며, 고온 초전도 전이온도 Tc는 92.5K값을 가졌다. 수송임계전류의 밀도의 값은 190A/㎠이었다. 완전 반자성과 낮은 임계장은 30K의 온도에서 각각 35.1%와 375 Oe이었다. 임계전류 밀도의 값은 10²∼10³A/㎠범위에 있었다. X-ray diffraction measurement for high Tc superconductor ?? was carried out at room temperature. The transport critical current density and resistivity were determined at 77K as well as in the range of 80∼160K. Also the magnetic susceptibility and the magnetic critical current density were measured from the magnetic hysterisis loops obtained at 30K. The X-ray diffraction analysis indicated that the phase of the sample is orthorhombic. The transiton temperature Tc was 92.5K. The transport critical current density was 190A/㎠. The perfect diamagnetism and the lower critical field were 35.1% and 375 Oe at 30K, respectively. The values of the magnetic critical current densities were in the range of 10²∼10³A/㎠.

현대(1910-1961) 에큐메니칼 교회론에 나타난 '일치'에 대한 종말론적 이해

김의훈 대학복음화학회 2004 대학과 복음 Vol.0 No.10

Solid Carbon Dioxide 에 의한 音響效果

李昌孝,金義薰 漢陽大學校 1979 論文集 Vol.13 No.-

The acoustic effect was produced by contacting an edge of metal rod with dry ice. Influences of various factors such as thermal conductivity, specific heat and density of the metal on the acoustic effect were investigated. The acoustic effect was mainly attributed to the production of sound by the impact due to sublimation pressure of dry ice. The impact frequency of the rod increased as time elapsed but it showed a comparatively slow increase in the beginning. There also occurred an abrupt increase of the frequency as time goes on. After a certain time elapsed, the frequency reached a stational constant value thereafter. The time required for arriving at the stational impact frequency distinctively increased as mass and thermal conductivity of rod decreased and it also increased when specific heat become large.

MYCALEX의 유전 特性에 관한 硏究

金彩玉,金義薰 漢陽大學校 基礎科學硏究所 1984 基礎科學論文集 Vol.3 No.-

본 연구에서는 Mycalex의 전기적 특성중 주로 誘電率, 誘電正接의 주파수와 온도 의존성에 대한 특성조사와 아울러 絶綠耐力 比低抗등을 조사하였다. 측정 주파수 영역은 5×10~1.5×10⁴K㎐이다. 연구결과 Mycalex시료에 대해서 다음과 같은 내용의 특성을 얻었다. ① 유전율의 주파수 특성을 5×10³K㎐에서 굴절점을 가지고 있다. ② 유전율의 값은 型造溫度가 상승할수록 커지며 tanδ의 값은 작아진다. ③ 유전손율은 굴절점 이상의 고주파칙에서는 거의 일정하며 그 값은 0.1~0.5의 범위내에 있다. ④ 體積抵抗率은 형조 온도가 상승함에 따라 指數曲線的으로 增加되고, 表面抵抗率은 거의 일정한 값이다. ⑤ 절연내력의 범위는 2.4×10⁴~3.5×10⁴V/mm이다. ⑥ Mycalex의 형조 온도는 670℃~690℃가 적당하다. This paper puts great emphasis upon investigating the electric specific properties of the Mycalex such as permitivity, dielectric loss, the dependence of dielectric loss tangent on frequency and temperature, the breaking point of insulation, and specific resistance etc. The range of frequency measurement was from 5×10K㎐ to 1.5×10⁴K㎐. The results obtained by this study are as follows: 1. The frequency dependence of permitivity shows a bending point at 5×10³K㎐. 2. The rate of dielectric loss shows almost a constant at high frequency range above the bending point and the point is in the range of 0.1to 0.5. 3. The value of permitivity increases with the manufacturing temperature and decreases with the value of dielectric loss tangent. 4. The rate of volume resistance increases logarithmically with the manufacture temperature. The rate of surface resistance show almost a constant value. 5. The range of breaking point of insulation was from 2.4×10⁴ to 3.5×10⁴V/mm. 6. The profitable manufacturing temperature range of mycalex was known to be 670℃ to 690℃.

InGaAsP/InP 양자우물 구조의 물성연구

김채옥,오차환,문승준,김의훈 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-

Liquid phase epitaxy(LPE)법에 의해 InGaAsP quantum well(QW)구조를 성장하여 특성을 photoluminescence(PL)와 double crystal rocking curve(DCRC)를 이용하여 조사하였다. PL 측정결과, 상온 PL의 경우 well특성의 피크 에너지는 0.97eV이 FWHM은 80.41meV이며, 저온PL결과 well특성의 피크 에너지는 1.025eV이고 FWHM은 33meV이었다. 여기광의 세기를 증가시킴에 따라 PL 세기가 비교적 선형적으로 급준한 증가를 보이고 있어 well발광 특성임을 관찰할 수 있었다. DCRC결과, 격자부정합도가 0.32이고 한 쌍의 주기는 600Å이며 전형적인 Quantum Well특성의 위성피크를 관찰할 수 있다. In this work, We have grown the InGaAsP/InP quantum well by liquid phase epitaxy(LPE) and its some physical properties have been studied by photoluminescence(PL) and double crystal x-ray rocking curve(DCRC). In low temperature PL, the characteristic emission peak of well is observed at 1.025eV with a full-with-half-maximum of 33meV. As we increase the excitation intensities the emission intensities are drastically increased. From the DCRC analysis, we know that lattice mismatch between epitaxial layer and substrate is very low with a value of 0.32.

코로나 放電寫眞의 응용

金義薰 漢陽大學校 基礎科學硏究所 1981 基礎科學論文集 Vol.1 No.-

The effects of variations in image quality and its field dependence on the corona discharge photograph have been explored experimentally. The radiation of light from the surface due to the corona discharge is greatly affected by the condition of the conducting surfaces located in the field between plane parallel electrodes. Therefore, the spark-breakdown voltage is affected by the presence of unevenness on the surfaces of the coin located in the field between the plane parallel electrodes. This paper shows that the image quality of the corona discharge image of the surface of coin in a plane to plane gap in air at atmospheric pressure generally depends on the multiplicational results of the discharge voltage and time.