• 한국전자파학회논문지
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• 제15권9호
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• pp.906-913
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• 2004

레이다 데이터로부터 ISAR(Inverse Synthetic Aperture Radar) 영상을 생성 할 때 가장 보편적으로 사용되는 것이 FFT 알고리즘이다. FFT 알고리즘을 넓은 방위각 데이터에 적용할 때는 MTRC(Moving Through Resolution Cell) 현상으로 영상의 번짐이 발생하는데 이를 보정하기 위하여 polar formatting 기법을 적용한다. 그러나 polar formatting도 적용할 수 있는 각도의 한계가 존재하며 만약 지나치게 넓을 경우 polar formatting을 적용하여도 원하는 영상을 얻을 수 없게 된다. 이 논문에서는 ISAR 영상 생성시 내삽법을 사용하는 polar formatting기법과 polar formatting의 단점인 내삽법을 사용하지 않는 CDT(Coherent Doppler Tomography) 기법을 비교하여 각각의 장단점을 분석하였다.

• 전자공학회논문지D
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• 제34D권4호
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• pp.113-120
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• 1997

In this paper, we have obtained information about the orientational distribution (polar and azimuthal) of the surface molecules on backward rubbed polyimide. Using the second-harmonic genration tecnique, the nonlinear susceptibility tensor components were induced. And, the orientational distribution function was estimated without a prior assumptions, using the maximum entropy method. The polar angle of surface molecules befor rubbing is isotropic. The polar angle of surface molecules after rubbing is anisotropic along the rubbing direction. The polar angle of surface molecules after several rubbing is determined by the last rubbing direction.

• Korean Membrane Journal
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• 제9권1호
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• pp.1-11
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• 2007

To prepare chemically stable asymmetric microporous membranes with a hydrophilic surface, which would be expected to have better antifouling properties, poly(vinylidene fluoride) (PVDF) blend membranes were prepared by the phase inversion process. PVDF mixture solutions in N-methylpyrrolidone (NMP) blended with several polar potential ionic polymers such as polyacrylonitrile (PAN), poly(methylmethacrylate) (PMMA) and poly(N-isopropylacrylamide) (NIPAM) were used for the formation of the PVDF blend membranes. They were then characterized with several analytical methods such as FESEM, FTIR, contact angle measurement, pore size distribution and permeability measurement. Regardless of different polar polymers blended, they all showed a finger-like structure with more hydrophilic surface than the pristine PVDF membrane. For all the PVDF blend membrane, due to the polar potential ionic polymers used, the flux of those was improved. Especially the PVDF blend membrane with NIPAM showed the highest flux among the membranes prepared. Also antifouling property of the PVDF membrane was improved by the use of the polar polymers.

• 통합자연과학논문집
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• 제5권1호
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• pp.38-41
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• 2012

In this paper we show that for any triangle and any point on the circumcircle the envelope of the Wallace-Simson lines with signed angle ${\alpha}$ is a parabola. The proof is obtained naturally using polar coordinates. We also present the reparametrization of the envelope which is a linear normal curve.

• 한국통신학회논문지
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• 제17권3호
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• pp.288-296
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• 1992

본 논문에서는 개선된 2D QPS(Quadrature polar separable) 필터의 설계와 조직 프로세싱에 대한 응용이 논의된다. 필터의 커넬쌍은 이산 PSS에 근거한 라디얼 가중 함수와 방향각을 위한 지수 감쇄 함수의 적으로 구성되며 주파수 평면상에서 퀴드래처 극분리형이 된다. 필터는 방향각 함수를 이산 PSS에 근사화시키므로 에너지 손실면에서 최적화된다. 필터의 주파수 특성은 대역폭, 방향각, 감쇄 정수, 그리고 주파수 변이 정수와 같은 설계 명제 조건에 의존하므로 제어가 용이하다. 조직 프로세싱에 대한 필터의 응용으로 조직 영상의 생성, 방향각의 평가, 그리고 합성 조직 영상의 세그멘테이션이 고찰된다. 결과는 넓은 대역폭을 갖는 필터가 강한 방향성 조직의 생성 및 식별에 사용될 수 있다는 것과 세그멘테이션 결과도 효과적임을 보였다.

• 한국컴퓨터정보학회논문지
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• 제26권11호
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• pp.85-92
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• 2021

이 논문에서는 회전각도에 무관하게 회전 얼굴과 회전각도를 효과적으로 검출하는 방법이 제안되었다. 회전된 얼굴 검출은 회전에 따른 얼굴 외형의 큰 변화로 인해 어려운 분야이다. 제안한 극좌표계 변환 방법은 회전 각도와 무관하게 얼굴 구성요소들의 위치 정보가 유지되기 때문에 회전으로 인한 얼굴의 외형 변화가 없게 된다. 이에 따라 회전이 없는 정면 얼굴 검출에 사용되지만 회전에 민감한 특성을 갖는 HOG와 같은 특징들이 회전얼굴을 검출하는 과정에서 효과적으로 사용될 수 있다. 극좌표계 변환된 영상에서 얻은 HOG 특징을 SVM을 이용하여 학습하고 회전 얼굴을 검출하였다. 학습 데이터는 회전이 없는 정면 얼굴 영상만을 사용하였다. 3600개 회전 얼굴 영상에 대한 실험 결과 97.94 %의 회전각도 검출률을 얻었다. 또한, 다수의 회전 얼굴이 포함된 배경이 있는 영상들에서 회전 얼굴들의 위치와 회전 각도를 정확하게 검출하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권10호
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• pp.553-558
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• 2000

This paper deals with change of contact angle, surface potential decay, surface resistivity and XPS of water-treated epoxy insulator. From the experimental results on the contact angle was reduced from $74^{\circ}$to $24^{\circ}$ due to the formation of polar hydroxyl groups on surface which was associated with intermolecular reaction between epoxy chains of three-dimensional network structure and water molecules. From the experimental results in the surface potential decay of water treated-samples, it was found that the accumulation of charge is decreased and the surface potential decay time is shortened by the interaction of polar hydroxyl groups induced on the treated surface as the increment of treatment time. The positive charging on the treated surface compared with negative charging is relatively lowered by the induction of polar hydroxyl groups. The surface resistivity was changed from $10^{15}[{\Omega}/cm^2$] to $10^{12}[{\Omega}/cm^2$] caused by water treatment. From XPS, it was found that the changes affected by the surface degradation of epoxy were caused by the generation of carboxyl groups through the chain decomposition and recombination with oxygen molecules in the air.

• 한국전기전자재료학회논문지
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• 제12권1호
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• pp.69-74
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• 1999

We have investigated that the high pretilt angle of the NLC, 4-n-pentyl-4-cyanobiphenyl (5CB), was observed on rubbed polythiophene (PTP) surfaces with alkyl chains with more than 10 carbon atoms; it is attributed to the surface-excluded volume effect by the alkyl chain lengths between the LCs and the PTP surfaces. Next, we investigated that the odd-even effect of the polar anchoring strength in 5CB on rubbed PTP surfaces with alkyl chain lengths has been successfully evaluated. The anchoring strength of 5CB for rubbed PTP surfaces with odd-number is weak compared with even-number up to the 6 carbon atoms in the alkyl chain; however, odd-number is strong compared with even-number above 7 carbon atoms. The weak anchoring strength of 5CB is approximately $1\times10^{-3} (J/m^2$) on rubbed PTP surface with 7 carbon atoms; it is relatively strong anchoring strength. Consequently, we conclude that the odd-even effects of the polar anchoring strength in NLCs are strongly related to the characteristics of the polymer and observed clearly for short alkyl chain lengths.

• 한국정밀공학회지
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• 제2권2호
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• pp.69-75
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• 1985

The object of this study is to discuss the effect of cutting fluid on the mechanism of chip formation in orthogonal cutting. Rehbinder effect has been known as a phenomenon, the reduction of mechanical strength, when the metal is exposed in a polar organic environment or the surface of metal is coated with some polar organic substances. About the cause of Rehbinder effect there have been many different ideas by Rehbinder, Merchant, Shaw, Sakakida and etc. In this report, the effects of surface active medium (magic ink) upon the mechanism of chip formation on the orthogonal cutting of copper and the mechanical properties of the work material are experimentally discussed with constant rake angle. Under the condition of polar organic environment the experimental results are as follows; 1) The chip thickness becomes thinner and slip line pitch on the free surface of chip becomes smaller than that of dried cutting area. 2) The order of alternation of cutting ratio was changed. 3) The friction angle on the tool face is not affected by the depth of cut. 4) The cutting force and shear strain on the shear plane decrease remarkably, therefore the work material must be embrittled under polar organic environment.

• 한국응용과학기술학회지
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• 제22권3호
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• pp.228-233
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• 2005

Langmuir-Blodgett(LB) technique can speak the best candidate of the future molecular electronic devices. But, precursor as molecular ultrathin film devices require the bulk property that are influenced by the molecular orientation. So, this device is one of current interest in molecular electronic device development of new materials. In this study, quantitative evaluation of molecular orientation in LB films of polyamic acid alkylamine salt was performed analysis experiment comparing the absorption or transmission intensity of the FT-IR spectrometer and reflection or absorption spectra with UV-visible absorption spectra. It could find that the polar angle(${\theta}$) of the dipole moment appears in about $68^{\circ}$ and the tilting angle of the alkyl chain is about $11.5^{\circ}$.