• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.100-108
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• 2008

In this paper, the dual-ground, high-gain and broad-band internal antenna has been designed and fabricated for 4th-generation mobile communication applications. The optimized antenna was fabricated using photolithography method. The antenna consist of the patches, antenna and system ground, and a probe. The patch and ground plane were separated by air. In order to prevent the demage due to radiator swaying, the foams(${\varepsilon}_r{\fallingdotseq}1.03$) were used to fix the patches and ground. The conductor for the radiators was 0.05 [mm] thick. The measured input return loss showed less than -10 [dB] at the broadband from 3499 to 4743 [MHz]. It's measured bandwidth was 1244 [MHz]. The radiation patterns measured at 3400, 3600, 3800, 4000 and 4200 [MHz] showed Omni-directional characteristics. The gain in the E-plane and H-plane was 4.7 ~ 6.1 and 2.1 ~ 4.3 [dBi], respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.139-143
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• 2001

In manufacturing process of semiconductor package, thermal stress owing to high temperature in moulding and bubbles generated in chip bonding process become main causes to producing void. Therefore, on this study we evaluated quantitatively void size by ultrasonic spectroscopy method which analyze the frequency of this received pulse using pulses with broad band frequency, and after destructive test we verified effectiveness of sizing void by ultrasonic spectroscopy as we find error degree between the real size of void and the sizing void by ultrasonic spectroscopy.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.182-190
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• 1993

In manufacturing process of semiconductor package, the thermal stress owing to high temperature in moulding and the bubbles generated in chip bonding process become main causes to produce void. On this study we evaluated quantitatively void size by use of ultrasonic spectroscopy method which analyze the reflective pulses with broad band frequency in frequency domain, and after destructive testing we verified effectiv- eness of sizing void by use of ultasonic spectroscopy.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.55-55
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• 2003

Recently, with the rapid development of the waveguide division multiplexing (WDM) systems for large capacity and flexibility of information network, the broad band 1.5$\mu\textrm{m}$ erbium-doped waveguide amplifier (EDWA) become important. The main factors affecting the performance of sol-gel-based waveguides are non-radiative relaxation channels due to rare-earth concentration quenching and to vibration of the OH groups Therefore, the sol-gel process has to be carefully controlled in order to minimize the residual OH content.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.82-89
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• 1999

In this article, the performances of acoustic enclosure with double resilient mount system which was designed by ADD to reduce the radiated noise by main noise source of ships, was tested and evaluated. From test results, it was verified that the acoustic performances of acoustic enclosure satisfied the requirements; vibration isolation level at 1st stage mount system of 15 ㏈ and airborne noise reduction level of 20 ㏈ in broad band.

• Proceedings of the Optical Society of Korea Conference
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• 1991.07a
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• pp.83-83
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• 1991

1970年代 初에 開發된 光纖維는 化合物 半導體, Laser lc Photo-detector의 硏究開發과 더불어 光通信의 可能性을 確信케 했다. 國際的의 關心과 치열한 硏究開發 競爭으로 光通信技術은 1980年代 이미 實用化 段階에 到達케 되었음은 周知의 事實이다. 光通信 分野의 技術開發은 指定되어 電子部品이나 電子素子를 包含하지 않고 오직 光部品 또는 光素子만으로 構成된 全光通信 System이 廣帶域 ISDN(Broad Band ISDN)으로 곧 國際化 될 것이며, 21 世紀에는 光帶域 通信網이 Video, Audio, Data의 統合 Service 通信網으로 浮上 情報化 社會의 Ingra-structure가 될 것이다. 本發表에서는 이러한 光通信網을 構築하는데 必要한 部品 및 素子의 製造技術을 深度있게 說明코저 한다.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.161-164
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• 1998

광대역 주파수 상에서 외부로부터 입사하는 전자파를 산란시키지 않고 유전체 내부에서 흡수시키기 위해 유전체를 다층으로 배열하여 전파 흡수체를 최적 설계하고자 한다. 수직 및 여러 각도로 전파가 입사하는 경우 각 유전층의 두께, 유전 상수, 손실 탄젠트 등의 설계변수를 유전자 앨거리즘을 이용하여 최적화한다. 다극함수에서의 부분 초기화 유전자 앨거리즘의 성능 향상을 위해 부분 초기화율, 부분 초기화 시점, 스케일 인자의 변화에 따른 성능을 비교, 개선하여 흡수체 설계에 적용하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.585-587
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• 2008

Depending on host environments, $Eu^{2+}$ emission can be spectrally tuned by manipulating the energy levels between allowed $4f{\leftrightarrow}5d$ transition. Spectral variations of $Eu^{2+}$ emission from narrow green emission to broad yellow emission band were achieved by varying the host lattices such as Sr- or Ba-silicate, borate, and borosilicate.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.667-671
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• 1989

The CO laser is one of powerful light source for laser magnetic resonance spectroscopy in the mid-infrared region of the spectrum because of its wideband operational characteristics. In this work, a liquid nitrogen cooled cw CO laser is developed to allow broad-band operation from 5 to 8 ${\mu}m$. The design details will be presented.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.183-186
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• 2000

본 논문에서는 잡음에 적합한 능동 정합 회로를 구성하여 기존의 보상 정합 회로와 궤환 회로를 적용함으로써 L. S 밴드(1-4GHz) 내에서 균일한 이득 특성과 작은 반사 손실을 갖는 광대역 저잡음 증폭기를 설계하였다. 설계된 중폭기는 대역 내에서 14.25-14.96dB의 소신호 이득과 1.41, 1.28 이하의 입, 출력 정재파비를 갖는다.