• Journal of electromagnetic engineering and science
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• 제11권2호
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• pp.83-90
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• 2011

In this paper, we present the design method for a low-pass type inverter, which can effectively suppress the spurious response associated with band-pass filters. The inverter has a length of ${\lambda}/4$ and employs not only a stepped-impedance configuration but also asymmetrical and bending structures in order to improve frequency selectivity and compactness. The inverter is applied as an impedance/admittance inverter to the ultra-wideband (UWB) band-pass filter. The UWB band-pass filter configuration is based on a stub band-pass filter consisting of quarter-wavelength impedance inverters and shunt short-circuited stubs ${\lambda}/4$ in length. The asymmetrical stepped-impedance low-pass type inverter improves not only the spurious responses, but also the return loss characteristics associated with a UWB band-pass filter, while a compact size is maintained. The UWB band-pass filter using the proposed inverters is fabricated and tested. The measured results show excellent attenuation characteristics at out-band frequencies, which exceed 18 dB up to 39 GHz. The insertion loss within the pass-band (from 3.1 to 10.6 GHz) is below 1.7 dB, the return loss is below 10 dB, and the group delay is below 1 ns.

• Journal of electromagnetic engineering and science
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• 제10권4호
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• pp.212-218
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• 2010

The radar backscatter from various earth surfaces is sensitive to the frequency of the incident wave. This study examined the radar sensitivities for surface parameters such as soil moisture content and surface roughness of both bare and vegetated surfaces at X-band. Because L-band frequencies are often used for sensing the surface parameters, the sensitivities of X-band are also compared with those of the L-band. The sensitivities of the X-band radar backscatter were examined with respect to soil moisture content and surface roughness of rough bare soil surfaces. These sensitivities were also examined using the same parameters for vegetated surfaces for various vegetation densities and incidence angles. Use of the X-band radar for soil moisture detection was as effective as L-band radar for bare soil surfaces. For vegetated surfaces, the soil moisture could be detected using an X-band radar at lower incidence angles, where the upper limit of the incidence angles was dependent on vegetation density.

• Geomechanics and Engineering
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• 제5권6호
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• pp.499-517
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• 2013

In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.

• 복식문화연구
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• 제26권4호
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• pp.632-648
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• 2018

This study aims to contribute to the development of sports wearables. It was conducted by a convergence team of professionals in the fashion industry, kinesiology and sports studies, and computer science and engineering. The purpose of the current study was to design and develop a fabric-type fitness band for a sensor to measure acceleration during jump rope exercises. Computer science and engineering professionals developed the Arduino board and sensor, kinesiology and sports studies provided the necessary exercise protocol, and the fashion industry professionals developed the band. First, a fitness band preference survey was completed by men and women between the ages of 20 and 50. Typical uses of the band included tracking exercise amount as measured by the number of steps taken and calories burned. Strap watch closure, a single color and achromatic color, and soft and smooth touch materials were preferred as band design. Second, two fabric-type fitness bands were designed and developed. Design 1 had a 3-dimensional pocket for the sensor, bright blue color, and stretch binding around the edges and for a loop. Design 2 had a flat pocket for the sensor, achromatic color, mesh binding around the edges and two metal loops. Both designs had Velcro as a closure. Third, wear testing of both bands with the sensor were conducted of 15 women in their 20s. They wore the bands during jump rope exercises. Both bands generally satisfied the participants. The Design 2 band was slightly more satisfying than the Design 1 band.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.217-220
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• 2004

This paper presents design simulation, implementation, and measurement of a miniaturized GPS/K-PCS dual-band LTCC chip antenna for mobile communication handsets. The dimension of LTCC chip antenna is $9mm{\times}15mm{\times}1.2mm$. The lower meander type antenna is to be tuned to the lower frequency (GPS) band and the upper meander antenna with via hole connection is to contribute the higher frequency (K-PCS) band. In order to lowering the resonant frequency for GPS band, two printed modified meander antenna with gap stub is used to integrate with PCS band operation. The measured resonant frequency at GPS band shifts to lower frequency about 100MHz. The measured impedance bandwidth(VSWR $\leq$ 2) are 55MHz and 120MHz at the resonant frequency. respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.267-270
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• 2004

A silver indium sulfide($AgInS_2$) epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_2$ epilayer has found to be a chalcopyrite structure and evaluated to be high qualify crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks. are ascribed to the band-to-band transition. The valence band splitting of $AgInS_2$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\ddot{A}cr$, and the spin orbit splitting, $\ddot{A}so$, have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_g(T)$, was determined.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.513-514
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• 2008

A scalable satellite broadcasting system is designed to guarantee quality of multimedia service cooperatively utilizing both Ku Band and Ka band. In the system, video streams are separated into a base layer and an enhancement layer, and are transmitted over the two channels, Ku Band and Ka band, respectively. A basic quality of service using the base layer stream can be provided even when the enhancement layer stream over Ka band channel is unavailable by rain attenuation. A rain fall model is simulated using Barlett-Lewis Pulse model and is used in the operation test of the implemented sacalable satellite broadcasting system.

• Journal of Yeungnam Medical Science
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• 제2권1호
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• pp.59-63
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• 1985

저자들은 tension band wiring을 이용하여 주두골골절을 치료하여 그 결과를 분석하여 tension band wiring이 주두골골절의 치료에 매우 효과적이란 결론을 얻었기에 보고하는 바이다.

• 대한안전경영과학회지
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• 제11권4호
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• pp.161-168
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• 2009

Ubiquitous application is in need of high-level technology to meet various requests for ubiquitous service. In order to adopt ubiquitous technology in not only pilot projects but also regional services, many projects like u-City are implemented in and outside the country. RFID has been known as one of the important technology to provide with core benefits of Ubiquitous services. Because each band of RFID technology has merits and demerits concurrently, single-band RFID system has limitations for various RFID services. Thus, we developed dual-band RFID system enable to provide with 13.56MHz and 2.45GHz RFID service at the same time to compensate the shortage of single-band RFID system. Also we have considered the way that the firmware would control signals without collision, studied battery life and range for tag, and made hardware for dual-band RFID service.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1053-1058
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• 2021

본 논문은 능동소자에 인가되는 게이트 바이어스 전압을 가변하여 X-, K- 및 Ka-대역 신호를 선택적으로 변환할 수 있는 다중대역 혼합기를 제안하였다. 제안한 다중대역 혼합기는 LO 전력 +6 dBm으로 구동하였고 X-대역의 경우, 게이트 바이어스 전압 -0.8 V에서 변환손실 -10 dB 특성, K-대역에서 게이트 바이어스 전압 -0.3 V에서 변환손실 -9 dB 특성, Ka-대역에서는 게이트 바이어스 전압 -0.2 V에서 변환손실 -7.0 dB 특성을 나타내었다. 모든 대역에서 1-dB 압축점 (P1dB)은 +0.5 dBm 특성을 나타내었다.