• 한국인터넷방송통신학회논문지
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• 제22권5호
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• pp.87-92
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• 2022

본 논문에서는 탐색기용 AESA 레이더에 적용할 수 있는 배열소자 설계에 관한 연구를 수행하였다. AESA 레이더에 적용하기 위한 안테나는 전자 빔조향 특성을 확보하기 위해 배열 안테나에 적용할 최적의 복사소자를 선정하고, 설계 시 빔조향 특성을 고려하여야 한다. 특히 광각 빔조향 특성을 충족하기 위해 광각 임피던스 매칭(WAIM:Wide Angle Impedance Matching) 기법을 활용하여 광각 조향 시 발생할 수 있는 음영 지역(Scan Blindness region)을 최소화하여야 한다. 이처럼 시스템 운용의 안정성 확보가 AESA 레이더의 중요한 설계 고려 사항이 되고 있다. 본 논문에서는 AESA 레이더 안테나 장치에 적용되는 복사소자 특성을 개선하기 위해 복사소자 끝단에 WAIM을 적용하고, 시스템의 안정적 운용 척도인 능동 반사 계수 성능 변화를 검토하였다. 최종 성능 결과는 시뮬레이션 데이터를 수학적으로 합성하여 제시한 방안의 유효성을 검증하였다.

• 한국레이저가공학회지
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• 제17권3호
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• pp.19-23
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• 2014

To directly engrave circuit-line patterns as wide as $6{\mu}m$ in a buildup film to be used as an IC substrate, we applied a projection ablation technique in which an 8 inch dielectric ($ZrO_2/SiO_2$) mask, a DPSS 355nm laser instead of an excimer laser, a ${\pi}$-shaper and a galvo scanner are used. With the ${\pi}$-shaper and a square aperture, the Gaussian beam from the laser is shaped into a square flap-top beam. The galvo scanner before the $f-{\theta}$ lens moves the flat-top beam ($115{\mu}m{\times}105{\mu}m$) across the 8 inch dielectric mask whose patterned area is $120mm{\times}120mm$. Based on the results of the previous research by the authors, the projection ratio was set at 3:1. Experiments showed that the average width and depth of the engraved patterns are $5.41{\mu}m$ and $7.30{\mu}m$, respectively.

• Earthquakes and Structures
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• 제25권4호
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• pp.283-296
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• 2023

This paper presents experimental and numerical studies of seismic performance on reinforced concrete (RC) wide beam (WB) joints. Two RC-WB joint specimens and one conventional RC joint specimen were fabricated using the reinforcing details of longitudinal reinforcing bars in a beam as a variable, and quasi-static cyclic loading tests were performed. The results were used to compare and analyze the load-drift ratio relationship, failure mode, and seismic performance of the specimens quantitatively. In addition, a finite element (FE) analysis of the RC-WB joint was conducted, and the rationality of the FE model was validated by comparing it with the test results. Based on the FE model, a parametric study was conducted, where the ratio of longitudinal reinforcing bars placed on the outer and inner parts of the joint (𝜌_ex/𝜌_in) was a key variable. The results showed that, in the RC-WB joint, an increase of 𝜌_ex/𝜌_in leads to more severe damage to concrete, which reduces the seismic performance of the RC-WB joints.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.187-190
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• 1999

We have developed fabrication processes that form a wide-head T-gate with a 0.2 ${\mu}{\textrm}{m}$ gate length using the combination of thickness of each PMMA layer, line doses and development times for applications in millimeter- and micro-waves monolithic integrated circuits. The three-layer resist structure (PMMA/P(MMA-MAA)/PMMA = 1800 $\AA$/5800 A/1900$\AA$), 4nC/cm and over development were used for fabrication of a wide-head T-gate by the conventional double E-beam exposure technology. The experimented results show that the cross sectional area of T-gate fabricated by the proposed method is easily enlarged without additional processes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1267-1270
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• 1998

This paper analyzes the characteristics of wide-band one-shot beam formed by using all sensors of array at once, as variation of weighting width. Gaussian function is applied to each sensor as a role of weighting. As the results of the simulation for nested linear array having 17 sensors for each octave, as the width goes wider the directivity index(DI) becomes lower but more even and the variation of beamwidth becomes smaller. It is confirmed, therefore, that weighting width is carefully decided in consideration of DI level, DI stability and the beamwidth.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.639-642
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• 1998

This paper proposes a new wide-band beamforming which has guassian weighting. For the prupose of measurement this beam is formed by using all sensors toghether, not octave-by-octave. Weighting is applied to each sensor before time-delay compensation as a frequency-dependent function. As the resutls of the simulation of the proosed algorithm for nested linear array having 17 sensors for each octave, it is confirmed that beam can be formed with all sensors together and uniform directivity index can be achieved by proposed algorithm.

• Computers and Concrete
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• 제23권6호
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• pp.377-398
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• 2019

Behavior of RC beam-column joint is very complex as the composite material behaves differently in elastic and inelastic range. The approaches generally used for predicting joint shear strength are either based on theoretical, strut-and-tie or empirical methods. These approaches are incapable of predicting the accurate response of the joint for entire range of loading. In the present study a new generalized RC beam-column joint shear strength model based on hybrid approach i.e. combined strut-and-tie and empirical approach has been proposed. The contribution of governing parameters affecting the joint shear strength under compression has been derived from compressive strut approach whereas; the governing parameters active under tension has been extracted from empirical approach. The proposed model is applicable for various conditions such as, joints reinforced either with or without shear reinforcement, joints with wide beam or wide column, joints with transverse beams and slab, joints reinforced with X-bars, different anchorage of beam bar, and column subjected to various axial loading conditions. The joint shear strength prediction of the proposed model has been compared with 435 experimental results and with eleven popular models from literature. In comparison to other eleven models the prediction of the proposed model is found closest to the experimental results. Moreover, from statistical analysis of the results, the proposed model has the least coefficient of variation. The proposed model is simple in application and can be effectively used by designers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.405-410
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• 2001

To investigate factors influencing the effective width of. SRC column-steel beam joint resisting the moment as strut, six specimens are designed and tested. Parameters in the test are column width, beam height and horizontal tie within beam depth. From the test, using either wide column width or ties, strength and stiffness of joint were developed. The lower beam height the specimens showed the lower moment.

• 한국전자파학회논문지
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• 제30권6호
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• pp.467-478
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• 2019

본 논문에서는 전자전용 재밍 송신기에 사용하기 위해서 개발된 광대역 평면형 능동위상배열 안테나 시스템의 설계 및 제작 그리고 측정 결과를 소개한다. 설계된 시스템은 $45^{\circ}$ slant 광대역 복사소자를 $8{\times}8$ 삼각 배열 구조로 배치하고, 광대역 GaN 반도체 고출력 증폭기와 GaAs 다기능집적회로(MFC)를 적용한 64개의 송신 채널을 구성하여 개발하였다. GaAs다기능집적회로는 광대역에서 빔 편이 현상을 피하기 위한 실시간 지연소자, 디지털 감쇠기 그리고 GaAs 구동증폭기를 포함하고 있어서 송신 빔 조향을 할 수 있으며, 시스템의 전자적 빔 조향 범위는 방위각/고각 방향으로 각각 ${\pm}45^{\circ}/{\pm}25^{\circ}$ 범위에서 가능하다. 개발된 시스템의 송신 빔 패턴 성능을 확인하기 위해 근접 전계 시험 시설을 이용하였다. 전자전용 송신 시스템 빔 패턴 측정 결과, 시스템의 유효방사출력은 목표성능(P) 대비 최대 9.8 dB 이상을 만족하였고, 방위각/고각 방향으로 각각 ${\pm}45^{\circ}/{\pm}25^{\circ}$ 빔 조향 결과 요구성능에 만족함을 확인하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2008년도 공동학술대회
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• pp.93-96
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• 2008

멀티빔 음향측심기를 이용하여 후포퇴(Hupo Bank) 주변의 정밀해저지형 분석하였다. 멀티빔 음향측심기는 광범위한 광대역 빔을 발사하여 조사선의 항적에 따른 지형기복을 관측할 수 있는 시스템으로 조사 측선과 측선 사이의 미측심구간에 대한 자료의 밀도를 높여 정밀해저지형을 구현할 수 있다. 이러한 조사를 통해 연구해역에서는 길이 84km, 폭 1-15km 그리고 수심 5.3-160m를 보이는 후포퇴를 중심으로 서측에는 모오트(moat)가 동측에는 scarp와 해저협곡(submarine canyon)이 분포한다. 또한 후포퇴의 정상부에는 최소 5.3m의 수심을 보이는 왕돌초(Wangdol reef)가 존재한다. 본 연구해역에 분포하는 모오트는 깊이가 30m 그리고 폭이 30-40m로 움폭파인 수로 형태를 보인다. scarp는 수심차가 약 60m로 절단면의 특성을 보이며 해저협곡은 3.5km에서 최대 13.5km의 폭을 보인다.