• 한국인터넷방송통신학회논문지
• /
• 제19권4호
• /
• pp.105-111
• /
• 2019

본 논문에서는 근접전계 시험을 수행하여 Ka 대역 밀리미터파 탐색기용 도파관 광벽 슬롯 배열 안테나의 성능 검증을 수행하였다. 슬롯 배열 안테나의 측정은 원전계, 근접전계 시험을 모두 수행하고 비교하여 밀리미터파 대역의 근접전계 시험의 유효성을 확인하였다. 검증을 수행한 슬롯 배열 안테나의 빔폭 및 부엽 준위를 포함한 빔 패턴 특성이 동일함을 확인하였다. 방위각, 고각 빔패턴의 부엽준위 차이는 1dB 이내로 검증되었다. 추가로 back-projection 기법을 활용하여 근접전계 데이터를 가공한 후 안테나 개구면의 분포를 새롭게 추출하여 배열 안테나 성능 분석을 수행하는 방법에 대하여 소개하였다.

• 한국전자파학회논문지
• /
• 제26권4호
• /
• pp.414-423
• /
• 2015

본 논문에서는 항공기 레이더에 적용 가능한 능동배열 안테나의 배열오차 분석 및 보정에 대한 시험 결과를 기술하였다. 복사소자, TR 모듈, 급전기 등으로 구성되는 배열소자 간의 크기 및 위상오차는 안테나 부엽 준위에 영향을 미치며, 이는 안테나 개구면 weighting에 따른 이상적인 부엽레벨, 배열소자 개수, 안테나 효율 등에 의해 그 민감도가 달라진다. 시스템에서 요구되는 부엽준위를 만족시키기 위해서는 배열소자의 오차 보정이 반드시 이루어져야 한다. 그 방법은 오차요소에 따라 다르게 적용되어야 하며, 안테나 형태, 목표 부엽 준위에 따라 고려되는 수준의 차이가 달리 적용되어야 한다. 본 논문에서는 배열오차 요소와 그 영향에 대해 분석하였으며, 오차 보정 방안을 제시하였다. 또한, 근접 전계 시험을 통해 그 결과를 확인하였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
• /
• pp.447-450
• /
• 2002

In this paper, we present design methods for a series-fed microstrip patch array operating at X-band frequency. The array consists of 18 rectangular patches connected to 3 quarter-wave impedance transformers. The power divider is designed for the uniform element excitation. The element excitation is then made to be tapered by increasing the input impedance of elements located at array edges. The designed antenna is fabricated and tested. Results of test show a fair agreement with the prediction.

• 한국소음진동공학회논문집
• /
• 제19권7호
• /
• pp.693-698
• /
• 2009

Various acoustic tests were carried out to investigate the acoustic performance of diesel engine exhaust silencers. In order to consider flow effects, the test facility was set up composed of fan, duct and silencer. Using the test facility, insertion loss tests were carried out to improve the acoustic performance in the low-frequency ranges. Through a series of tests, it was found out that the array resonators having multi-perforated holes inside the exhaust silencer, might be very effective in the low frequency range. Consequently, the hybrid-type silencer which is the combination of reflective silencer with array resonators and conventional absorptive silencer, was proposed and its high performance in the low-frequency range was also verified.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.30-35
• /
• 2007

Various acoustic tests were carried out to investigate the acoustic performance of diesel engine exhaust silencers. In order to consider flow effects, test equipment composed of fan, duct and silencer was set up. Using the test equipment, insertion loss tests were carried out to improve the performance in the low-frequency ranges. Through a series of tests, the fact that array resonators may be effective in the low-frequency noise has been verified. Consequently, the hybrid-type silencer which is the combination of reflective silencer with array resonators and conventional absorptive silencer were proposed and its high acoustic performance in the low-frequency range has also been verified.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.862-865
• /
• 2000

The object of this paper is to evaluate the surface roughness using the experimental equation of surface roughness, which is developed in turning by an orthogonal array method. $L_9{3^4}$ orthogonal array method, one of fractional factorial design has been used to study effects of main cutting parameters such as cutting speed, feed rate and depth of cut, on the surface roughness. And the analysis of variance (ANOVA)-test has been used to check the significance of cutting parameters. Using the result of ANOVA-test, the experimental equation of surface roughness, which consists of only significant cutting parameter - feed rate, has been developed. The coefficient of determination of this equation is 0.962.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권9호
• /
• pp.488-493
• /
• 2004

In this paper, we present the fabrication of copper electrode array and test of electrochemical discharge machining(ECDM) for glass machining. An array of 72 Cu electrodes is used to machine Borofloat33 glass. The height and diameter of a Cu electrode are 400 $\mu\textrm{m}$ and 100 $\mu\textrm{m}$ respectively. It is fabricated by ICP-RIE, Au-Au thermo-compression bonding, and copper electroplating. Borofloat33 glass is machined by the fabricated copper electrode array in 60 seconds at 55 V. The surface roughness of the machined glass is measured and the machined glass is anodically bonded with silicon.

• Tribology and Lubricants
• /
• 제24권6호
• /
• pp.368-373
• /
• 2008

This paper will investigate the friction characteristics of a 100m Hexagonal Array, Micro-scale Dimple Pattern, on bearing steel. These characteristics are researched by utilizing a pin-on-disk wear test machine, under various test conditions. The reduction of friction is a necessary requirement for the improved efficiency of this machine. As the speed increases, there is a decrease in the effect of the dimple of friction characteristic, with substantially little change to density. Conversely, as the load increases, the dimple pattern grows larger, resulting in a difference in the texture of these two components. At a dimple density of 10% the friction characteristic is easily demonstrated, with a consistent change in both speed and load.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.92-96
• /
• 2007

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet windtunnel.

• 한국소음진동공학회논문집
• /
• 제18권6호
• /
• pp.612-618
• /
• 2008

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet wind tunnel.