• 대한기계학회논문집
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• 제19권5호
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• pp.1333-1339
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• 1995

Recently developed technique of measuring minor species concentration by using the modulation dip in broadband CARS has been applied to the flame structure study of methane/air premixed flames in a counterflow. This method used the modulation dip from the cold band CO Q-branch resonant signal superimposed on the nonresonant background. The measured CO concentration profile in a symmetric and unsymmetric methane/air premixed flames together with the velocity and temperature by using LDV and CARS have been compared with the numerical results adopting detailed chemistry modeling. The results show that there is a satisfactory agreement between the experimental data and numerical results for velocities, temperatures and CO concentrations. And the modulation dip technique of measuring minor species, such as CO is a viable tool for a quantitative measurement in a flame.

• Journal of Advanced Marine Engineering and Technology
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• 제14권1호
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• pp.62-71
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• 1990

Two-dimensional turbulent wake flow past a rectangular cylinder is investigated experimentally by using the linearized constant temperature hot-wire anemometer. Some of turbulent characteristics are obtained at the range of X=6B-500B downstream from the cylinder and the Reynolds number range is 500-2800. For the statistical treatment, autocorrelation coefficient, probability density function and power spectral density function are obtained by using the signal analyzer. It is clear that coherent structure of strong periodic eddies exists to the position of 20B downstream from the cylinder, and its feature is similar to round type as nearer to the cylinder while it is stretched longitudinally along with flow direction as the distance from the cylinder is increased to downstream.

• 대한전자공학회논문지
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• 제26권8호
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• pp.1203-1210
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• 1989

A cross-sectional transmission electorn microscopy study of the MBE grown GaAs/Al0.3 Ga0.7As layers was carried out at high-resolution so that the atomic arrangement of the well, barrier and the interface could be understood on an atomic level. Results show that the images reveal directly the atomic structure of the GaAs, Al0.3Ga0.3 Ga0.7 As interface is sharply defined but is not smooth on the atomic scale. The roughness arises from the presence of hills with heights of several{002} GaAs interplanar spacings. The atomic arrangement at the interface is almost completely coherent without any structural disorder. Alloy clustering at the interface was not observed.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.126-127
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• 2000

Resonance fluorescence is the manifestation of the interaction between the physical system under consideration and the vacuum-field fluctuation. The fluorescence spectrum provides such physical informations as the energy-level structure of the system, instabilities and relative populations of the energy levels, etc.. One of the typical fluorescence spectra is the Mollow triplet appearing when two-level atoms are driven by a strong coherent field in free space$^{(1)}$ . In the weak field limit, the singlet instead of the triplet is obtained with a reduced linewidth due to the squeezing of one quadrature phase of the induced atomic dipole$^{(2)}$ . On the other hand, when the atoms are put inside a cavity rather than in free space, a doublet spectrum due to the vacuum Rabi-splitting is achieved, showing clearly the coupling of atoms and the cavity in the single-quantum limit$^{(3)}$ . (omitted)

• 대한전자공학회논문지SD
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• 제42권9호
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• pp.19-28
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• 2005

특정한 각으로 입사하는 가간섭인 평행광선들에 의한 간섭무뉘는 1차원 정보로서 표현되는 회절격자와 흡사한 홀로그램을 구성하며, 이러한 홀로그램을 1차원 홀로그램이라 제안한다. 1차원 홀로그램을 이용하여 표시장치의 구성이 가능하며, 간단한 광 컴퓨팅구조로서 빠르게 간섭무늬를 계산할 수 있다. 이러한 표시장치를 구성하는 방법을 제시한다.

• 전자공학회논문지A
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• 제31A권9호
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• pp.26-33
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• 1994

In this paper, the performance of the trellis coded CPFSK with the coherent detection over mobile communication channels is calculated. The characteristics of channels, including phase jitter effects and fading effects, are examined and modeled. The phase jitter channel is modeled to have a nonzero mean and a gaussian distribution. The fading channel has a Rayleigh distribution in the multipath. For the optimal decoding method(MLSE), the Viterbi algorithm is used for the trellis structure of trellis coded CPFSK. The results indicate that the trellis coded CPFSK with a small moulation indes gets more sensitive, as the index gets smaller, to the phase noise under the phase jitter channel. Using the interleaving method. It gives considerable improvements in the error rate under the fading channel.

• Journal of Advanced Marine Engineering and Technology
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• 제24권6호
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• pp.120-127
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• 2000

This study is concerned with evaluating the effects of acoustic excitation on the development of two stream mixing layer generated by split plate. The ratios of two velocities U1 and U2 either side of the splitter plate were such that $U_1/U_2$=1.0 (uniform flow) or $U_1/U_2$<1.0(shear flow). The mixing layers were disturbed acoustically through the edge of split plate. Quantitative data were obtained with hot-wire anemometry. Flow visualization with smoke-wire was also employed for qualitative study. the results show that the large scale structures of mixing layers are strongly affected by excitation frequency and amplitude in both uniform and shear flows. The maximum streamwise and vertical turbulent intensities of the excited flow fields are apt to be decreased as compared with those of without excitation. The flow characteristics of uniform flow are more influenced by acoustic excitation than those of shear flow.

• Elastomers and Composites
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• 제30권2호
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• pp.112-121
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• 1995

The physical properties of rubber compounds containing silica and siliane coupling agent in order to replace the carbon black and prepare for environmental regulation showed improved dynamic properties(rebound, heat build-up, $60^{\circ}C\;tan\;{\delta}$), but the abrasion resistance did not improve compared with the compounds containing carbon black. Also, curing retardation because of coherent structure of silica improved by the addition of DEG, but the mixing step change of activators did not so much improve the static and dynamic properties of the compounds containing high synthetic rubber, the status of mixing and dispersion showed that the compounds containing carbon black was much better than the compounds containing silica by TEM investigation.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.304-305
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• 2013

We report a positive exchange bias (HE) in thinmultilayered filmscontaining nano-oxide layer. The positive HE, obtained for our system results from an antiferromagnetic coupling between the ferromagnetic (FM) CoFe and the antiferromagnetic (AFM) CoO layers, which spontaneously form on top of the nano-oxide layer (NOL). The shift in the hysteresis loop along the direction of thecooling field and the change in the sign of exchange bias are evidence of antiferromagnetic interfacial exchange coupling between the CoO and CoFe layers. Our calculation indicates that uncompensated oxygen moments in the NOL results in antiferromagnetic interfacial exchange coupling between the CoO and CoFe layers. One of the interesting features observed with our system is that it displays the positive HE even above the bulk Neel temperature (TN) of CoO. Although the positive HEsystem has a different AFM/FM interfacial spin structure compare to that of the negative HE one, the results of the angular dependence measurements show that the magnetization reversal mechanism can be considered within the framework of the coherent rotation model.

• 전자공학회논문지A
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• 제29A권9호
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• pp.65-75
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• 1992

In this paper, we introduce an integrated layout design system, SOLGER. Our system incorporates useful design tools : a powerful layout editor, a coherent access mechanism for large volumes of design data, an incremental design rule checker for hierarchical design environment, node extractor and electrical rule checker, a technology capture which is used for defining technology-specific information, and a procedural design environment for user customization. Also, we present a modified corner-stitching data structure which allows 45$^{\circ}$-angled bilateral edges. Users are provided with a multi-window design environment and a menu-driven interface. SOLGER is being used for VLSI designs practically.