• 한국항해항만학회지
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• 제28권4호
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• pp.293-297
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• 2004

In this papers, an S-band oscillator of the low phase noise property using a miniaturized micro-strip hairpin shaped ring resonator is presented The substrate has a dielectric constant $\epsilon_\gamma$＝3.5, a thickness h＝0.508 mm, and loss tangent $tan\delta$＝0.002. A designed and fabricated oscillator shows low phase noise performance of 99. 71 dBc/Hz at 100 KHz offset frequency and of output power 19.584 dBm at center frequency 2.450 GHz. This circuit was fabricated with hybrid technique, but can be fully compatible with the MMIC due to its entirely planar structure.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권2호
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• pp.140-145
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• 2006

The behaviour of alginate immobilized and soluble watermelon (Citrullus vulgaris) urease in water miscible organic solvents like, acetonitrile, dimethylformamide (DMF), ethanol, methanol, and propanol is described. The organic solvents exhibited a concentration dependent inhibitory effect on both the immobilized and the soluble urease in the presence of urea. Pretreatment of soluble enzyme preparations with organic solvents in the absence of substrate for 10 min at $30^{\circ}C$ led to rapid loss in the activity, while similar pretreatment of immobilized urease with 50% (v/v) of ethanol, propanol, and acetonitrile was ineffective. Time-dependent inactivation of immobilized urease, both in the presence and in the absence of urea, revealed stability for longer duration of time even at very high concentration of organic solvents. The soluble enzyme, on the other hand, was rapidly inactivated even at fairly lower concentrations. The results suggest that the immobilization of watermelon urease in calcium alginate make it suitable for its application in organic media. The observations are discussed.

• 한국전기전자재료학회논문지
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• 제14권3호
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• pp.228-233
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• 2001

This paper presents the optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro elelctro mechanical system) applications usign SOI (Si-on-insulator) and trench structures. The micro-heater is based on a thermal measurement principle and contains for thermal isolation regions a 10㎛ thick Si membrane with oxide-filled trenches in the SOI membrane rim. The micro-heater was fabricated with Pt-RTD (resistance thermometer device) on the same substrate by suing MgO as medium layer. The thermal characteristics of the micro-heater wit the SOI membrane is 280$\^{C}$ at input power 0.9W; for the SOI membrane with 10 trenches, it is 580$\^{C}$ due to reduction of the external thermal loss. Therefore, the micro-heater with trenches in SOI membrane rim provides a powerful and versatile alternative technology for improving the performance of micro-thermal sensors and actuators.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.845-847
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• 1999

(Ba, Sr)$TiO_3$[BST] thin films were fabricated on Pt/$TiO_2/SiO_2$/Si substrate by RF sputtering. The structural and dielectric properties of the BST thin films were investigated with the deposition time. Increasing the deposition time from 20 min. to 60 min., second phases were decreased, and EST (111), (100), (200) peaks were increased. The relative dielectric constant and dielectric loss of the EST thin films with the thickness of 3000$\AA$ were 300 and 0.018, respectively at 1[kHz]. The relative dielectric constants was decreased and dielectric losses was increased as increasing the frequency.

• 한국산업정보학회논문지
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• 제19권2호
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• pp.45-49
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• 2014

In this work, a phase shifter radio-frequency integrated chip (RFIC) using a simple all-pass network is presented. As a tuning element of the phase shifter RFIC, tunable capacitors with a multi-layer dielectric of a para-/ferro-/para-electrics using a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film were utilized. In order to evaluate and analyze the fabricated phase shifter RFIC, the same elements such as an inductor and capacitor integrated into it are also fabricated and tested. The designed phase shifter RFIC was fabricated on a quartz substrate in the size of $1.16{\times}1.21mm^2$. As the test results, the maximum phase difference of $350^{\circ}$ is obtained at 15 V and its tuning frequency bandwidth is 90 MHz from 2.72 to 2.81GHz.

• 한국통신학회논문지
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• 제25권10B호
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• pp.1701-1706
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• 2000

본 연구에서 GaAs pHEMT와 도파관-마이크로스트립 변환구조를 이용하여 38 GHz 대역 하이브리드 전력증폭기 모듈이 개발되었다. 10 mil duroid 기판이 전력증폭가와 도파관-마이크로스트립 변환구조 제작에 사용되었다. 제작된 도파관-마이크로스트립 변환구조는 32 - 40 GHz 대역까지 약 I dB 삽입손실(back to back)의 측정 결과를 보였다. 전력증폭기 모듈의 측정 결과, 36.8 - 38.5 GHz에서 대략 출력 전력 29 dBm(P1.5 dB), 전력 이득은 7.2 dB, PAE 는 11.2 % 였다.

• Journal of electromagnetic engineering and science
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• 제15권2호
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• pp.111-114
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• 2015

In this paper, we have proposed dual-band Phi-shaped slot gap filler antenna for satellite internet service applications. Some properties of the antenna such as return loss, radiation pattern, and gain have been simulated and measured. The proposed antenna has a Phi-shaped slot on the circular patch and is fabricated on the TLX-9 substrate. The radius of the circular patch is 25 mm, and it has a coaxial feeding structure. The dual-band Phi-shaped slot gap filler antenna has high-gain, small-size, simple-structure, and good radiation patterns at each band. The operating frequency band can be tuned by adjusting the length AL and FL of the Phi-shaped slot.

• ETRI Journal
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• 제39권6호
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• pp.813-819
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• 2017

A slotted rectangular nameplate antenna design with a patch bearing the name of the first author is presented. A $6.8mm{\times}26mm{\times}1.6mm$ substrate of FR-4 epoxy material having a relative permittivity of 4.4 and a dielectric loss tangent of 0.02 is used. Additionally, the feeding technique used is a coaxial mechanism. The standard antenna design parameters, including the reflection coefficient, bandwidth, radiation pattern, gain, directivity, and voltage standing wave radio (VSWR) for the proposed prototype are analyzed using a high-frequency structure simulator (HFSS) v-15, and are compared to the measured results. The designed structure may be considered for different satellite- and radio-determination applications at the respective resonant frequencies.

• 한국전자통신학회논문지
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• 제7권6호
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• pp.1275-1279
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• 2012

본 논문에서는, 무선통신을 위한 이중대역 마이크로스트립 안테나를 설계하였다. IEEE 802.11a의 대역인 Hyper LAN(5.725~5.825GHz)에서도 사용 할 수 있도록 설계하였다. 제안된 안테나의 기판은 FR-4이고 크기는 $22mm{\times}23mm$, 두께는 1.6mm로 구성하였으며, 시뮬레이션은 CST Microwave Studio 2010을 사용하였다. 설계된 안테나의 시뮬레이션 결과 5GHz와 5.8GHz의 대역에서 공진을 나타내고 -10dB 이하에서 양호한 반사손실을 보였다.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.81-84
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• 2010

In dye-sensitized solar cells (DSSCs), the back transfer of photo-generated electrons from FTO glass to triiodide ions in an electrolyte is an important loss mechanism, which leads to low cell efficiency. Recently, this back electron transfer was greatly suppressed by the introduction of a compact $TiO_2$ blocking layer, which was prepared by the treatment of $TiCl_4$ solution. In the present work, more detailed $TiCl_4$ treated surface conditions on FTO substrate were investigated and DSSC performances were correlated with the surface morphology as well as dark current behavior.