• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.4
• /
• pp.506-514
• /
• 1998

The design and fabrication of X-band(11.7~12 GHz) 2-stage monolithic microwave integrated circuit(MMIC) low noise amplifier (LNA) for active antenna are presented using $0.15{\mu}m\times140{\mu}m$ AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (P-HEMT). In each stage of the LNA, a series feedback by using a source inductor is used for both input matching and good stability. The measurement results are achieved as an input return loss under -17 dB, an output return loss under -15dB, a noise figure of 1.3dB, and a gain of 17 dB at X-band. This results almost concur with a design results except noise figure(NF). The chip size of the MMIC LNA is $1.43\times1.27$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.9
• /
• pp.1019-1024
• /
• 2012

In this paper, a UWB antenna using a SIR(Step Impedance Resonator) that eliminate signal interference at 5 GHz WLAN as the first rejection band and adjust the second rejection band is proposed. Unlike the unit impedance resonator, the second harmonic of SIR is decided according to step impedance. Therefore, To adjust the second rejection band, SIR is applied to UWB antenna. Also, the equivalent circuit of the antenna at first rejection band is presented and the equivalent modeling values of the SIR and the coupling value is obtained. The proposed antenna is satisfied to cover full UWB band with return losses less than -10 dB and has band rejection characteristic in 5 GHz WLAN band. The radiation patterns show +y directivity characteristics in H-plane and the group delay variations are within 1.0 ns.

• Korean Journal of Crystallography
• /
• v.8 no.1
• /
• pp.20-25
• /
• 1997

Two experimental methods have been developed for high resolution measurement of x-ray scattering. The methods used were (1) an x-ray double crystal diffraction (DCD) spectrometer set-up and (2) an x-ray triple crystal diffraction (TCD) spectrometer set-up. With the DCD arrangement of Si(511)-sample(hkl), rocking curves have been plotted for Si (333), Si(004) and GaAs(004). Also, with the TCD arrangement of Si(111)-Si(111)-Si(511)-sample(hkl) including monolithic monocro-collimator and $K_{\alpha1}$ selector, rocking curves have been plotted for Si(333), Si(004) and GaAs(004). The results of FWHM by DCD and TCD set-up have been compared each other and discussed. The reflection topographs (004) and (115) in an $In_{0.037}Ga_{0.0963}As/GaAs$ sample have been obtained by DCD set-up.

• 한국지구물리탐사학회:학술대회논문집
• /
• 1999.08a
• /
• pp.202-216
• /
• 1999

The deep foundation is frequently used for the infrastructures. Since the quality control of the cast-in-place concrete foundations such as CIP piles and slurry walls is not so easy as that of the ready made PC(prestressed concrete) piles, it is necessary to get the information on the integrity of the concrete of the foundation. The depth estimation of foundations whose depths are unknown is also very important in repair and reinforcement works or in safety inspection and assessment to the big structures. The cross-hole sonic logging(CSL) system and the single channel reflection seismic measurement system were developed to test the integrity of pile. The former is well applied to CIP structures, while the later to all kinds of piles with less accurate result compared to that of CSL. To estimate the depth of the deep foundations, parallel seismics, borehole RADAR, and borehole magnetics can be used.

• Korean Journal of Remote Sensing
• /
• v.19 no.6
• /
• pp.411-419
• /
• 2003

An area corresponding to the spatial resolution of optical remote sensor imagery often includes more than one pure surface material. In such case, a pixel value represents a mixture of spectral reflectance of several materials within it. This study attempts to apply the spectral mixture analysis on forest and to evaluate the information content of endmember fractions resulted from the spectral unmixing. Landsat-7 ETM+ image obtained over the study area in the Kwangneung Experimental Forest was initially geo-referenced and radiometrically corrected to reduce the atmospheric and topographic attenuations. Linear mixture model was applied to separate each pixel by the fraction of six endmember: deciduous, coniferous, soil, built-up, shadow, and rice/grass. The fractional values of six endmember could be used to separate forest cover in more detailed spatial scale. In addition, the soil fraction can be further used to extract the information related to the canopy closure. We also found that the shadow effect is more distinctive at coniferous stands.

• Annual Conference on Human and Language Technology
• /
• 2010.10a
• /
• pp.114-117
• /
• 2010

특정 대상 또는 외부 자극에 대해 반사적이고 직관적으로 발생하는 느낌으로 정의되는 감성은 자신의 경험을 바탕으로 개개인이 서로 다른 반응을 보이는 특징을 가진다. 이러한 감성은 맞춤형, 적응형 및 개인화된 서비스를 요구하는 현대사회에서 반드시 필요하고 연구되어야 하는 대상이다. 하지만, 감성은 외부 자극에 따라 빠르게 변하고 객관성을 유지하기 어려울 뿐 아니라 복합적으로 나타나기 때문에 측정하거나 표현하기가 매우 어렵다. 시각정보는 감성을 이해하고 전달하는 데 큰 비중을 차지하며, 대상에 대한 종합적인 정보를 전달하여 빠르게 인지하고 이해하는데 많은 도움을 준다. 그 중 색채정보는 대상의 객관적인 특정, 심리적 속성 및 사회적 배경을 반영할 수 있어 복합적인 감성을 효과적으로 표현하고 전달한다. 많은 연구를 통해 감성과 색채정보 간의 관계를 생성하고 정의하였지만, 단일 시각정보로 감성을 표현하는 것은 한계가 있다. 본 논문에서는 종합적인 시각정보를 고려한 감성연구를 제안하기 위해 대용량의 감성어휘와 이미지를 수집하였다. 감성어휘는 The Center for the Study of Emotion and Attention(CSEA)에서 생성한 균형 감성어휘 중 273개를 사용하였고 감성이미지는 객관성과 공통성을 유지하기 위해 사용자의 참여가 활발하고 이미지에 부착된 태그가 비교적 정확한 Flickr를 사용하여 수집하였다. 감성어휘 당 약 500개의 이미지를 수집하고자 시도하였고, 총 130,944개의 감성이미지 후보를 수집하였다. 한 번 수집된 이미지는 중복을 피하였고, JPEG형식으로 저장되어 있다. 또한, 각 이미지에는 사용자 태그가 평균적으로 약 25개가 포함되어 있고, 총 2,l47,645개의 태그를 수집하였다.

• Korean Journal of Optics and Photonics
• /
• v.16 no.5
• /
• pp.476-478
• /
• 2005

We have fabricated a Fabry-Perot etalon around $1.3\;{\mu}m$ wavelength utilizing $Al_{2}O_3$ and a-Si thin films. A full width at half maximum of ${\sim}12.1nm$ and a finesse value of 53 were found from the measured resonant transmission spectra. Single thin film of $Al_{2}O_3$ was analyzed by spectroscopic ellipsometry. A refractive index of a-Si thin film was measured as 3.120 in the real part and 0.002 in the imaginary part, respectively. The thin-film pairs of $Al_{2}O_3$ and a-Si are applicable to output mirrors of vertical-cavity surface-emitting lasers at $1.3{\mu}m$ waveband.

• Korean Journal of Optics and Photonics
• /
• v.21 no.3
• /
• pp.91-96
• /
• 2010

The size of a reconstructed image depends on the reconstruction distance and wavelength. The double fourier transform method is proposed to eliminate the dependence on the reconstruction distance and wavelength. We can get a fixed reconstructed image size by using the double fourier transform method. Two wavelength digital holography is proposed to measure the step height, which is larger than a single wavelength. The two image size of different wavelength holograms should be the same in order to apply two wavelength digital holography. We use two wavelength digital holography and double fourier transforms to measure the step height. The measured data were reasonable and we found that the double fourier transform is useful in two wavelength digital holography.

• Journal of Advanced Navigation Technology
• /
• v.23 no.4
• /
• pp.309-315
• /
• 2019

This paper proposes an implementation of unequal power divider with 1:3 and 1:4 splitting ratio in multi-section structure using CPW and offset coupled transmission line. The power divider consists of a multi-section transmission line and a circuit with parallel capacitors and resistors. A multi-section transmission line was implemented by decomposing a ${\lambda}/4$ single transmission line terminated by an arbitrary impedance and converging it with a multi-section transmission line shorter than $90^{\circ}$ electrical length, and RC parallel circuits were connected between transmission lines to obtain reflection coefficient of output port and isolation characteristics between the output port. In this way, it was confirmed that the transmission lines at the unequal power divider designed at 2 GHz were shorter than ${\lambda}/4$ and implemented at least 27% less than the conventional ones, and that the broadband characteristics could be obtained.

• Journal of Advanced Navigation Technology
• /
• v.23 no.5
• /
• pp.415-423
• /
• 2019

In this paper, a design method for a high-sensitivity microstrip patch sensor antenna (MPSA) loaded with a bent-slot was studied for the permittivity measurement. The bent-slot similar to a single-ring complementary split ring resonator was added along a radiating edge of the patch in order to enhance the sensitivity to the permittivity. The sensitivity of the proposed MPSA was compared with that of a conventional rectangular MPSA and a thin rectangular-slotted MPSA. Three MPSAs were designed and fabricated on a 0.76-mm-thick RF-35 substrate so that the input reflection coefficient would resonate at 2.5 GHz in the absence of the superstrate under test. When five different Taconic substrates with a relative permittivity ranging from 2.17 to 10.2 were used as the superstrate under test, experiment results show that the sensitivity of the proposed MPSA, which is measured by the shift in the resonant frequency of the input reflection coefficient, is 4.1 to 6.1 times higher than that of the conventional MPSA.