• 한국전자파학회논문지
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• 제18권6호
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• pp.656-663
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• 2007

본 논문은 접지된 2중의 유전체 평면 사이에 변화하는 저항율을 갖는 저항 띠 격자 구조로 임의의 각도로 입사되는 E-분극 전자파 산란 문제를 모멘트 법으로 해석하였다. E-분극 산란에서는 저항 띠의 모서리 양끝에서 유도되는 전류 밀도가 매우 높을 것으로 예측되므로, 이 특성과 일치하는 기저 함수를 직교 다항식 일종인 2종 Chebyshev 다항식의 급수로 전개하여 수치 해석하였다. 산란 전자계는 주기적인 구조에 대응시킬 수 있는 Floquet 모드 함수의 급수로 전개하였고, 미지의 계수를 구하기 위하여 경계 조건을 적용하였다 또한, Fourier-Galerkin 모멘트 법을 적용함으로써 접지된 2중의 유전체 사이에 다양한 저항율을 갖는 저항 띠에 대해 기하광학적인 정규화 된 반사 전력에 관한 스트립 폭과 주기, 입사각의 영향 등을 수치 해석하였다.

• 한국산업정보학회논문지
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• 제4권1호
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• pp.102-109
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• 1999

본 논문에서는 접지평면위에 2개의 유전체 층을 가지는 완전도체 격자구조에서의 전자파 산란문제를 간단한 방수치해석 방법으로 잘 알려진 PMM방법을 적용하여 입사각에 따라 수치해석하였다. 산란전자계는 Floquet 모드 함수의 급수로 전개하였다. 경계조건은 미지의 계수를 구하기 위하여 적용하였고, 도체의 경계조건은 접선성분의 전계와 스트립 위의 전류와의 관계를 위해 적용하였다. 입사각이 수직일 때 비유전율이 증가함에 따라 기하광학적 반사전력의 변하는 최소점은 스트립 폭이 높은 값으로 이동한다는 것은 주목되며, 이때 수직입사시 대부분의 전력은 다른 각도의 방향으로 산란된다.

• Current Optics and Photonics
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• 제6권3호
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• pp.337-343
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• 2022

Microfluidic chips are new devices that can manipulate liquids at the micrometer level, and terahertz (THz) time-domain spectroscopy has good applicability in biochemical detection. The combination of these two technologies can shorten the distance between sample and THz wave, reduce THz wave absorption by water, and more effectively analyze the kinetics of biochemical reactions in aqueous solutions. This study investigates the effects of different external magnetic field intensities on the THz transmission characteristics of deionized water, CuSO₄, CuCl₂, (CH₃COO)₂Cu, Na₂SO₄, NaCl, and CH₃COONa; the THz spectral intensity of the sample solutions decrease with increasing intensity of the applied magnetic field. Analysis shows that the magnetic field leads to a change in the dipole moment of water molecules in water and electrolyte solutions, which enhances not only the hydrogen-bond networking ability of water but also the hydration around ions in electrolyte solutions, increasing the number of hydrogen bonds. Increasing the intensity of this magnetic field further promotes the hydrogen-bond association between water molecules, weakening the THz transmission intensity of the solution.

• 한국전자파학회지:전자파기술
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• 제5권2호
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• pp.20-28
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• 1994

컬러게이트 혼 안테나의 이론적 복사패턴을 벡터적분법과 준 광학모드 이론으로써 각각 구하였다. 혼 개구면에 존재하는 하이브리드 모드의 전자계를 등가 전류원으로 대체하고 포텐셜 이론을 적용하는 벡터 적분법으로 안테나의 복사 전계식을 계산 하였다. 또한, 준 광학모드인 Gaussian-Laguerre 모드를 확장하여 복사 관력식을 유도하였다. 85-115GHz에서 동작하는 컬러게이트 혼 안테나에 대한 복사패턴을 벡터적분법 및 준 광학방법으로 계산하고 비교한 결과 중심 주파수인 100GHz에서는 거의 일치하였으나 85 및 115GHz에서는 다소의 오차가 발생하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.340-343
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• 2008

The Soya Warm Current (SWC) is a coastal boundary current, which flows along the coast of Hokkaido in the Sea of Okhotsk. Seasonal and subinertial variations in the SWC are investigated using data obtained by high-frequency (HF) ocean radars, coastal tide gauges, and a bottom-mounted acoustic Doppler current profiler (ADCP). The HF radars clearly capture the seasonal variations in the surface current fields of the SWC. The velocity of the SWC reaches its maximum, approximately 1 m/s, in the summer, and becomes weaker in the winter. The velocity core is located 20 to 30 km from the coast, and its width is approximately 50 km. The almost same seasonal cycle was repeated in the period from August 2003 to March 2007. In addition to the annual variation, the SWC exhibits subinertial variations with a period from 10-15 days. The surface transport by the SWC shows a significant correlation with the sea level difference between the Sea of Japan and Sea of Okhotsk for both of the seasonal and subinertial variations, indicating that the SWC is driven by the sea level difference between the two seas. Generation mechanism of the subinertial variation is discussed using wind data from the European Centre for Medium-range Weather Forecasts (ECMWF) analyses. The subinertial variations in the SWC are significantly correlated with the meridional wind component over the region. The subinertial variations in the sea level difference and surface current delay from the meridional wind variations for one or two days. Continental shelf waves triggered by the meridional wind on the east coast of Sakhalin and west coast of Hokkaido are considered to be a possible generation mechanism for the subinertial variations in the SWC.

• 천문학논총
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• 제32권1호
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• pp.251-255
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• 2017

Submillimetre and millimetre-wave surveys with Herschel and the South Pole Telescope have revolutionised the discovery of strong gravitational lenses. Their follow-ups have been greatly facilitated by the multi-wavelength supplementary data in the survey fields. The forthcoming Euclid optical/near-infrared space telescope will also detect strong gravitational lenses in large numbers, and orbital constraints are likely to require placing its deep survey at the North Ecliptic Pole (the natural deep field for a wide class of ground-based and space-based observatories including AKARI, JWST and SPICA). In this paper I review the current status of the multi-wavelength survey coverage in the NEP, and discuss the prospects for the detection of strong gravitational lenses in forthcoming or proposed facilities such as Euclid, FIRSPEX and SPICA.

• 한국해양공학회지
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• 제21권6호
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• pp.120-124
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• 2007

The purpose of this study was to investigate the stability of the arched and fan types of artificial reefs, which provide habitats for shellfish and seaweed. According to the Froude similitude, parameters affecting the stability of the artificial reefs were analytically, experimentally studied. First, the design parameters of the artificial reefs in wave and current fields were presented. Then, using dimensionless parameters, such as the surf similarity parameter and water particle speed, the stability of the arched and fan types of artificial reefs was investigated. From the hydraulic experiments, it is shown that the stability heavily depends on the way the artificial reefs are installed. Therefore, the installation of the artificial reefs on the surf zone should be carefully executed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.127-130
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• 2002

Supersonic jet flow has been applied to many various industrial applications of manufacturing fields. Such a supersonic jet is generally classified by three flow patterns, depending on the flow state at nozzle exit, that is, under-, correctly- and over-expanded flows. Of these three flows, the correctly-expanded supersonic jet is most frequently used since it provides a maximum performance of a flow device. However detailed information on what conditions are the Jet correctly expanded at the exit of nozzle is not well known. In the current study, computations are applied to the axisymmetric, compressible, Navier-Stokes equations. The design Mach number used are 2.0,1.2 and 2.6. The computational results obtained are compared with the previous experimental ones. A theoretical analysis is conducted to predict the major features of the correctly-expanded jet. The results show that the jet core length is increased as Mach number is increased.

• 세라미스트
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• 제21권2호
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• pp.59-74
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• 2018

Imaging in the Short Wave Infrared (SWIR) provides several advantages over the visible and near-infrared regions: enhanced image resolution in in foggy or dusty environments, deep tissue penetration, surveillance capabilities with eye-safe lasers, assessment of food quality and safety. Commercially available SWIR imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits(ROIC) by indium bump bonding Infrared image sensors made of solution-processed quantum dots have recently emerged as candidates for next-generation SWIR imagers. They combine ease of processing, tunable optoelectronic properties, facile integration with Si-based ROIC and good performance. Here, we review recent research and development trends of various application fields of SWIR image sensors and nano-materials capable of absorption and emission of SWIR band. With SWIR sensible nano-materials, new type of SWIR image sensor can replace current high price SWIR imagers.

• 전기전자학회논문지
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• 제7권1호
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• pp.32-42
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• 2003

본 논문에서는 이방성 매질의 덮개층과 기판을 갖는 사각 마이크로스트립 패치 안테나의 방사패턴을 full-wave approach와 모멘트 계산법을 이용하여 연구하였다. 이방성 매질내의 구성관계식을 통하여 제안된 구조에서의 파수영역 다이애딕 그린 함수를 유도하였으며 이 결과로부터 전계 적분 방정식을 수식화하였다. 갤러킨 모멘트법을 사용하여 전계 적분 방정식을 이산화 하여 전류밀도의 계수를 구한 후에 구좌표계의 원거리 전계는 고정 위상법(stationary phase method)을 이용하여 얻을 수 있다. 전사모의 실험 결과의 타당성을 검증하기 위해서 기존의 결과와 비교하여 일치된 결과를 얻었으며 이방성 덮개층의 두께 변화 그리고 기판과 덮개층의 이방성 비에 따른 방사패턴이 제시되고 분석되었다.