• 한국공작기계학회논문집
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• 제13권5호
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• pp.67-74
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• 2004

Laser heat treatment is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power $CO_2$ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching action to occur and the formation of matrensitic structure. In this investigation, the microstructrual features occurring in Nd:YAG laser hardening SM45C and $STD_11$ steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimisation of the processing parameters for maximum hardened depth of SM45C and $STD_11$ steel specimens of 10mm thickness by using CW:YAG laser.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.498-502
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• 2011

The divergent synthesis of novel phosphorus-containing dendrimer with 4,4'-sulphonyldiphenol at the core has been accomplished involving simple condensation reactions using $P(O)Cl_3$, $P(S)Cl_3$, 3-amino-phenol, 3-hydroxy-benzaldehyde, and 2-butyn 1, 4-diol. The final compound was a Schiff's base macromolecule possessing 4 imine bonds, 8 acetylenic bonds and 8 OH groups at the periphery. The structures of intermediate compounds were confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), LC-Mass and C, H, N analysis. The structure of the final dendrimer (5) was confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), MALDI-TOF-MS, and C, H, N analysis. The surface morphological characteristics of the final dendrimer were understood by Scanning Electronic Microscopic study (SEM). The thermal stability of the final dendrimer was studied by TGA/DTA analysis.

• 대한미생물학회지
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• 제16권1호
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• pp.71-82
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• 1981

An electron microscopic study was carried out on the morphogenesis of herpes simplex type 2 virus in BHK-21 cells BHK-21 cells was found susceptible to infection and replication of herpes simplex type 2 virus cytopathic effects of the herpes type appeared at approximately 1 day postinoculation. Foci consisting of rounded refractile cells and syncytia were observed. Projection of the nuclear membrane in the infected cells was also seen, Several infected cells showed a track-shaped structure which apparently consisted of multiple layered membranes of the nucleus.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1898-1904
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• 2003

Laser heat treatment is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power $CO_{2}$ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching to occur and the formation of matrensitic structure. In this investigation, the microstructrual features occurring in Nd:YAG laser hardening SM45C and $STD_{11}$ steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimisation of the processing parameters for maximum hardened depth of SM45C and $STD_{11}$ steel specimens of 10mm thickness by using CW Nd:YAG laser.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.341-344
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• 2001

제일원리 슈도퍼텐셜 계산을 통해 강유전성 격자 불안정성의 미시적 기원과 페로브스카이트 PbTiO$_3$의 전자구조를 연구했다. 의사 얀-텔러 효과를 이용해서 격자 불안정성을 논의한다. 얀-텔러 효과의 원인은 O 원자의 p 궤도함수와 Ti 원자의 d 궤도함수의 혼성결합이다. 얀-텔러 효과는 브릴루앙 영역의 중심에서 가장 중요해진다는 것을 알 수 있었다.

• Carbon letters
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• 제5권2호
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• pp.75-80
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• 2004

The studies on activated carbon prepared from walnut shell and groundnut shell were undertaken to ascertain the effect of initial state of precursor and activation process on the development of porosity in the resulting activated carbon. Walnut shell based carbon shows the presence of cellular pores while Groundnut shell based carbon shows fibrillar pore structure. The adsorption parameters, characterization of product and scanning electron microscopic studies carried out showed the presence of mainly Micro, Meso and Macro porosity in carbon prepared from Walnut shell while mainly micro porosity was observed in Groundnut shell based activated carbon. An interrelationship between the adsorption efficiency and porosity in terms of quality control parameters, for before and after activation, was validated through the scanning electron microscopic data.

• Journal of Magnetics
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• 제7권1호
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• pp.9-13
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• 2002

The dependences of microscopic magnetic domain on film thickness in unidirectional and isotropic exchange-coupled NiO/NiFe bilayers were investigated by magnetic force microscopy to better understand for exchange biasing. As NiO thickness increases, microscopic domain structure of unidirectional biased film changed to smaller and more complicated domains. However, for isotropic-coupled film a new cross type domain appeared with out-of plane magnetization orientation. The density of the cross domain is proportional to exchange biasing fields and the fact that the domain was originated by the strongest exchange coupling region was confirmed from the dynamic domain configuration during a magnetization cycle.

• 한국광물학회지
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• 제4권1호
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• pp.51-55
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• 1991

산청 할로이사이트의 전자 회절분석 및 레플리카와 박편을 이용한 형태 연구결과 관산 할로이사이트는 반경이 서로 다른 몇 개의 관들이 중첩되어 있으며 내부의 작은 관은 원형이나 외부의 큰 관은 다각형으로서 두 관 사이에 삼각형의 공극이 형성되어 있음이 관찰되었다. 할로이사이트의 단면은 대체로 직경이 500${\AA}$보다 작으면 원형을 이루고 그보다 크면 다각형을 이룬다. 다각형의 단면을 갖는 할로이사이트의 전자 회절상은 이들이 이층 단사 구조를 갖고 있음을 지시한다.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.328-339
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• 2010

A new gasification model for coal char was developed considering the effects of pore structure and solid reaction product (ash) and compared with conventional models. Among various parameters reflecting microscopic pore structure, initial pore surface per unit volume of char was found to have the largest effect on carbon conversions. Reaction studies showed that the proposed model can predict carbon conversion more accurately over a broader range of reaction degree compared to the conventional models. Therefore the model proposed in this study would be useful for the design of pilot or commercial scale gasifiers.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1992년도 제3회 학술발표회 논문개요집
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• pp.17-17
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• 1992

In this talk, our recent progress in experiment study on microscopic surface phonons has been reviewed. After the brief introduction concerning the concept of surface phonons, exprimental apparatus of HREELS and the principle of the measurment for surface phonon dispersions, I show the experimental data of some solide surfaces. The following points are discussed ; (1) lattice dynamical analysis of the phonon dispersions of some transi tion metal carbide (100) surfaces indicates the large changes in the force constant near the surface, which is consistent wi th a rippled structure of a topmost layer. (2) the phonon dispersions of a graphite overlayer show the modified phonon structure, which indicates that the thickness of the overlayer is one atomic layer, and in addition, the electronic structure is also modified. (3) The phonon structure of $LaB_6$ (100) surface is discussed. Lastly I telJ about new technology of extreme high vaccum less than $10^{-10}$ Pa.EX> Pa.