• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.144-151
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• 2017

In this paper, the antenna for parking management using wireless communication in outdoor parking environment was proposed. The proposed antenna was miniaturized by using parasitic element to reduce the size of the radiating element of the basic ${\lambda}/2$ microstrip antenna. The dimensions of the proposed antenna are $35mm{\times}35mm{\times}20.1mm$ that is 98.7% smaller than $309.1mm(0.46{\lambda}){\times}296.1mm(0.441{\lambda}){\times}20.1mm(0.029{\lambda})$ of the basic ${\lambda}/2$ microstrip antenna. The electrical characteristics of the antenna are 1.1 dBi at the center frequency of 447 MHz, an omni-directional radiation pattern on the E-plane, and $87.5^{\circ}$ of HPBW on the H-plane. The miniaturized ${\lambda}/4$ folded microstrip antenna using parasitic element has proved to be easy to mount on the wireless repeater, the sensor node installed on the ground, and the strop bar in the outdoor parking environment.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.164-170
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• 2012

The dependance of degradation on the blue-peak wavelength is investigated with the blue light-emitting diode (LED) of InGaN/GaN with respect to the optical and the electrical characteristics of the devices. The LED devices emitting the blue-peak wavelength ranging from 437 nm to 452 nm is prepared to be stressed for a long aging time with three different currents of 60 mA, 75 mA and 90 mA, respectively. The degradation of optical intensity is observed with and without phosphor in the devices. The device without phosphor has been degraded significantly as the wavelength of blue-peak is decreased while the optical intensity of LED device with phosphor become less sensitive than that of device without phosphor. The electrical property does not depend on the emission peak wavelength. However, the series-resistance of LED device is slowly increased as the aging time is increased. The deformation of device is observed severely the short wavelength of blue-peak even with the same current since the short wavelength is absorbed substantially at the materials of device during the aging time. Consequently, in order to enhance the lifetime of LED devices, it is important to understand the optical degradation property of the materials against the specific wavelengths emitted from the blue chip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.349-349
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• 2008

유비쿼터스 시대를 맞이하여 현재의 전자제품은 고주파 환경에서의 소형화된 마이크로파 소자를 요구하고 있다. 현재 구현되고 있는 마이크로파 소자의 형태는 여러 가지 전송선로 중에 하나로서 금속의 그라운드면 위에 유전체 막을 형성하고 그 위에 금속선을 정밀하게 패터닝하여 각 종 소자를 연결하는 microstrip line의 형태가 많이 사용된다. 이러한 microstrip line 형태의 소자를 설계할 시에 소자 자체의 구조나 유전체 막이 그 소자의 성능을 크게 좌우한다. 여기서 유전체 막은 신호선과 그라운드면 간의 전자파를 집중시켜주어 방사손실을 줄여주는 역할을 한다. 유전체 막의 두께는 소자의 전체적인 크기를 결정하는 요인이 된다. 이는 유전체 막의 두께가 감소할 경우 50 $\Omega$ 임피던스 매칭을 위해 막 위에 형성되는 소자들의 선폭도 동시에 줄여야 하므로 소자의 소형화도 가능 하여진다. 하지만 유전체 막의 두께가 감소할 경우 전자파가 유전체 막에 집중되지 못하여 방사손실이 커지게 되고 소자의 성능이 저하된다. 이런 점을 고려할 때 소자의 소형화를 만족시키면서 동시에 소자의 성능을 유지할 수 있는 유전체 막의 최적화 두께에 대한 연구가 필요하다. 볼 연구에서는 유전체 막의 최적화 두께를 제시하기 위해 대표적 마이크로파 소자인 Edge-Coupled Filter에 대하여 3-D Electromagnetic Simulator로 설계하고 유전체 막의 두께와 Filter 성능 간의 관계를 연구하였다. Filter의 성능은 유지하도록 하면서 유전체 막의 두께를 감소시켜 나간 결과, 약 30 ~ 40 ${\mu}m$ 의 최적화 두께를 얻을 수 있었다. 한편 30 ~ 40 ${\mu}m$ 두께의 후막 공정을 고려할 때 기존의 성막공정으로는 성막시간, 공정의 난이도, 공정온도 등의 면에서 난점이 존재하며 이러한 점들을 극복할 수 있는 Aerosol Deposition Method의 적용 가능성에 대해서 연구하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.253-259
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• 2003

This paper presents the basic characteristics of a 5 element dipole array antenna which has a four parastic element and one driving element at the center of the circular array. The coupled integral equations for the unknown current distributions on dipole elements are derived and solved by applying Galerkin's method of moments. The numerical results show that the highest power gain of 7.8 dBi is obtained at radius of d = 0.3lλ when two short circuited parastic element neighbors. In order to verify the theoretical analysis, the radiation pattern is compared with Preston's results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.273-279
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• 2009

In this paper, an antenna which has dipole-like radiation pattern and low profile is proposed. The antenna is composed of four elements slot array based on L-shaped 0.43 $\lambda_g$ slot element. It presents a omni-directional radiation patter in the azimuth plane and has a null toward broad-side direction. In the design, a small mono-pole antenna which acts as a large capacitance element, combined with the partially removed ground plane by four L-shaped slots. As a result, these structure act as a LC resonator for radiation. The measured result shows, the impedance bandwidth(VSWR$\leq$2) of the proposed antenna is 60 MHz(2.35$\sim$2.41 GHz). The measured maximum radiation gain and efficiency of proposed antenna is 0.02 dBi, 56.7 % at center frequency 2.38 GHz, respectively. The proposed antenna can be applied to wireless tan access point system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.5
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• pp.38-43
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• 2015

In this paper, we present novel dual-band microstrip antennas using inverted-L-shaped parasitic elements vertically at radiation apertures for GPS L1(1.575 GHz) and L2(1.227 GHz) bands. For making dual band which has large interval, the inverted-L-shaped parasitic element was loaded at the radiation aperture of a half-wavelength patch antenna(GPS L1) in opposite direction of the feeding point for receiving the low frequency(GPS L2). The low frequency occurs by perturbation and coupling between the patch and parasitic. Next, due to use circular polarizations at the GPS applications, two inverted-L-shaped parasitic elements were loaded at radiation apertures of each polarizations and the feeding point was moved at diagonal part of the patch. The dimensions of the designed circularly polarized antenna were $88.5{\times}79{\times}10.4mm^3$ ($0.36{\lambda}L{\times}0.32{\lambda}L{\times}0.04{\lambda}L$, ${\lambda}L$ is the free-space wavelength at 1.227 GHz). Measured -10 dB bandwidths were 116.3 MHz(7.4%) and 64.3 MHz(5.2%) at GPS L1 and L2 bands, respectively. All of these cover the respective required system bandwidths. The measured 3 dB axial ratio bandwidths were 11.7 MHz(0.74%) and 14 MHz(1.14%), respectively. Within each of the designed bands, broadside radiation patterns were observed.

• Journal of IKEEE
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• v.24 no.3
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• pp.917-920
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• 2020

In this paper, we studied the derivation method of isoflux radiation for a planar array antenna. The presented array antenna was designed for considering of 1U-sized CubeSAT with Ku-band communications. For the presented array antenna, 8×8 radiating elements were arranged, and the distance between radiating elements was set of half-wavelength. The excited current weighting for each radiating elements was calculated by the signal processing technique used in the design of the low-pass filter. As a result of analysis of the method proposed in this paper, it was confirmed that a seamless isoflux pattern can be derived.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.233-240
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• 2019

In this paper, due to the development of 5G communication technology, an antenna capable of covering both LTE and 5G bands is currently needed. In addition, we designed and manufactured a single feed antenna for the integrated public network (LTE) and 5G frequency dual band cover to satisfy the frequency bandwidth of more than 10% in each band. The antenna designed by adopting the dipole of the basic dipole antenna in a planar structure is a form in which the radiating element is vertically extended at all of the 700 MHz antennas and folded into a 'ㄷ' shape. In addition, the radiating element of the 700MHz band serves as a reflector of the 3.5GHz band radiating element. As a result, the 700 MHz band -10 dB bandwidth 104 MHz(14.8%) and 3.5 GHz band -10 dB bandwidth 660 MHz(18.8%) were obtained and the radiation pattern characteristic resulted in gains of 8.46 dBi, beam width E-plane 55°, H-plane 81° and 3.5 GHz bands 6.14 dBi, beamwidth E-plane 79°, H-Plane 49°.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.245-254
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• 2022

In this paper, a design optimization method for anti-jamming GPS antenna is presented. For this purpose, jamming performance analysis criteria and methods are presented. And based on the proposed analysis method, the antenna design elements that can realize the best performance were optimized. The anti-jamming GPS antenna for applying the presented method has a structure in which 7 radiating elements are arranged. Here, six radiating elements were circular arranged, and one element was arranged in the center of the circular arrangement. The optimized antenna design parameter(radius of the circular array) is 0.48 λ. As a result of the simulation, it was confirmed that when the steering angle(theta, phi) of the main lobe was (0°, 0°), the pattern null steering range(based on theta) was 57° to 90°.

• Proceedings of the Acoustical Society of Korea Conference
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• 1997.06a
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• pp.53-56
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• 1997

Tonpilz 압전변환기에 관하여 유한요소법을 사용하여 공기중의 동특성 해석과 수중의 방사임피던스를 해석하였다. 공기중에서 트랜스듀서의 구조를 변화시키면서 입력 어드미턴스 특성과 진동모드를 해석하여 압전변환기를 모델링하였다. 음향 윈도우를 압전변환기 전면에 부착한 후 유한요소법(FEM)에 의하여 매질의 영향을 고려한 입력어드미턴스 특성을 해석하였으며, 또한 방사임피던스 계산 루틴을 추가하여 무한 배플의 경계조건하에서 방사 임피던스를 해석하였다. 공기중과 수중에서의 해석을 통하여 Tonpilz 압전변환기 단일 소자의 구조 변경 및 기계 부재의 추가등에 따라 변동하는 변환기의 특성 및 방사 임피던스를 해석하므로서 평면 배열형 음향 트랜스듀서의 설계에 필요한 파라메터를 구할 수있다.