• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.263-268
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• 2001

This paper analyzes error probability performance adopted the Ray Tracing method efficiently analyzing millimeter wave or optic wave in Inter Vehicle Communication(IVC). Analysis environment analyzed bit error characteristic in 60㎓ band with very powerful to multipath wave, to be large to oxygen absorption and to be good to frequency reuse efficiency. We analyzed bit error characteristic of DS/CDMA system by multi access user in Two-Ray rician channel adopted reflect wave of grand, reflect wave of concrete wall and reflect wave of driving vehicle at side road. Improvement performance is adopted MRC diversity.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.9-13
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• 1997

본 논문에서는 two-ray 시간선택성 레일레이 페이딩 채널상에서 DPSK 신호를 차동검출 (differential detection)할 때 심볼에러율을 분석한다. 현재까지 수행된 많은 연구는 주파수 선택성 페이딩 채널 및 단일 경로 시간선택성 페이딩 채널을 대상으로 하였고, 다경로 시간선택성 페이딩 채널을 대상으로 한 예는 극히 드물다. 또한 다경로 시간선택성 페이딩 채널을 가장 간단히 모델링 할 수 있는 two-ray 페이딩 채널에 대한 연구도 지금까지 수행된 예가 극히 적다. 본 논문에서는 심볼열의 형태에 따라 수신신호들간의 관계를 세가지 그룹으로 나눈 후 각각의 경우에 대하여 위상 옵셋값을 계산하는 방식을 취하였다. 이와 같이 계산된 위상옵셋과 신호대 잡음비를 인자로 하여 차동검출된 신호가 가지는 위상의 확률밀도 함수를 계산하고 이 함수를 이용하여 심볼에러율을 계산하였다. 결과로부터 two-ray 페이딩 채널의 특성을 결정짓는 지연시간과 지연신호의 전력이 증가함에 따라 위상 옵셋값 및 에러율이 모두 증가하는 것을 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.157-160
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• 2001

본 논문은 근거리에서의 차량간 통신에 밀리미터나 광전파를 분석하는데 효과적인 Ray Tracing방법을 도입하여 오율특성을 분석하였다. 분석환경으로는 간섭신호에 강한 장점을 지니며 산소흡수에 의한 감쇠가 크며 주파수 재사용효율이 좋은 60GHz 대역에서의 비트오율을 분석하였다. 전파모델로 지면반사파, 콘크리트벽에 의한 반사와 옆 도로를 달리는 차량에 의한 반사를 고려한 Two-Ray 라이시안 채널에서의 다중접속자에 의한 DS/CDMA 시스템의 비트오율특성을 분석하여 검토하였다.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2375-2380
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• 2013

Two metal-organic frameworks based on the connectivity co-effect between rigid benzenedicarboxylic acid and bridging ligand have been synthesized $[Zn_2(3-NO_2-bdc)_2(4,4'-bpy)_2H_2O]_n$ (1), $[Co(3-NO_2-bdc)(4,4'-bpy)H_2O]_n$ (2) (where $3-NO_2-bdcH_2$ = 3-nitro-1,2-benzenedicarboxylic acid, 4,4'-bpy = 4,4'-bipyridine). The two novel complexes were characterized by IR spectrum, elemental analysis, fluorescent properties, thermogravimetric analysis, single-crystal X-ray diffraction and powder X-ray diffraction (PXRD). X-ray structure analysis reveals that 1 and 2 are two-dimensional (2D) network structures. Complex 1 and complex 2 belong to triclinic crystal with P-1 space group. The luminescence measurements reveal that two complexes exhibit good fluorescent emissions in the solid state at room temperature. Also, thermal decomposition process and powder X-ray diffraction of complexes were investigated.

• Journal of Magnetics
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• v.13 no.3
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• pp.85-87
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• 2008

I report a simple method to correct the saturation effect in absorption spectra measured in total electron yield (TEY) mode. It does not require additional measurements of the X-ray penetration depth. In order to check the reliability of the method, X-ray magnetic circular dichroism (XMCD) spectra for polycrystalline Fe were measured at two different incident angles, and then processed with the method. The two resultant XMCD spectra were identical, and their sum rule analysis produced the ratios of orbital magnetic moment to spin magnetic moment, which were very close to the well-known value.

• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.36-41
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• 2011

Nowadays, the solar expose right is very important with people's life. Therefore, in calculating the sunshine hours, the point analysis and area analysis methods are used in previous studies. Previous two methods have merits and faults. Therefore, ray-tracing method is used as a alternative. Ray-tracing method is adopted by the software of Autodesk Ecotect which is a widely used program by the architectural company and academic university. In this study first, ray-tracing methodology is studied with how to calculate the overshadowing area and, secondly, the sensitivity of the two major factors, overshadowing accuracy and sky subdivision, is analyzed. With these results, appropriate application of the ray-tracing method is presented.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.219-221
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• 1996

The x-ray pulsar GX 1+4 was observed by us in four balloon- borne experiments carried out from Hyderabad, India during 1991-1995 period with a hard x-ray telescope. The x-ray telescope consists of two collimated large area xenon-filled proportional counters with an effective area of $2400 cm^2$, a field of view of $5^{\circ}{\times}5^{\circ}$ and sensitive in the energy band of 20 - 100 keV. The pulsar was detected in bright state in two of the four experiments and x-ray pulsations with 120 second period were detected clearly. Pulsation period, rate of change of period with time, pulse fraction, pulse profile and energy spectra of the source were determined from these studies. During March 1995 observation, the x-ray pulse of GX 1+4 was found to be double-peaked compared to a single-peak pulse profile detected in December 1993. Details of these results are presented and their interpretation discussed in terms of the current accretion models of x-ray binaries.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.465-471
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• 2021

Dual-energy X-ray imaging (DEI) techniques can provide X-ray images that a certain material is suppressed or emphasized by combining two X-ray images obtained from two different x-ray spectrum. In this paper, a single-shot DEI, which uses stacked two detectors (i.e., multilayer detector), is proposed to reduce the patient dose and increase throughput in angiography. The polymethyl methacrylate (PMMA) and aluminum (Al) were selected as two basis materials for material decomposition, and material-specific images are reconstructed as a vector combination of these two materials. We investigate the contrast and noise performance of material-decomposed images using iodine phantoms with various concentrations and diameters. The single-shot DEI shows comparable performances to the conventional dual-shot DEI. In particular, the single-shot DEI shows edge enhancement in material-decomposed images due to the different spatial-resolution characteristics of upper and lower detectors. This study could be useful for designing the multilayer detector including scintillators and energy-separation filter for angiography purposes.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.51-54
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• 1996

In this paper, an interchannel interference (ICI) and symbol error probability for orthogonal frequency division multiplexing (OFDM) on the two-ray fading environment are obtained analytically. From the analysis results, it is found that the ICI is a Gaussian random variable and its variance depends on the subchannel location, normalized time delay, and the number of subchannels. In addition, the OFDM signal without guard interveal is found to yield an irreducible error even at high signal to noise ratio due to the ICI.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.119-124
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• 1999

A method to find the line of sight ray in space which corresponds to a point in an image plane is presented. The line of sight ray is defined by two points which are the intersections between the two calibration planes and the sight ray. The intersection point is found by the oblique coordinate mapping between the image plane and the calibration plane in the space. The proposed oblique coordinate mapping method has advantages over the transformation matrix method in the required memory space and computation time.