• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2005년도 추계종합학술대회
• /
• pp.623-626
• /
• 2005

In this paper, we proposed a new type SIR bandpass filter using DAML. This filter is consisted of 2 layers with MEMS resonator layer and CPW feed line. DAML ring resonator is elevated with $10\;{\mu}m$ height from GaAs substrate. Using MEMS processing, we are able to realize SIR bandpass filter easily. Furthermore it is useful to integrate on conventional MMICs because it has CPW interfaces and ring resonator is isolated from substrate by air-gap. We optimized and measured the results that $S_{21}$ attenuation at rejected band is over 15 dB, insertion loss is inside the limit of 3 dB, and relative bandwidth is about 10 % at 60 GHz

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2005년도 추계종합학술대회
• /
• pp.261-264
• /
• 2005

This paper presents the design of a down-conversion mixer with built-in active balun integrated in a $0.25\;{\mu}m$ pHEMT process. The active balun consists of series-connected common-gate FET and common-source FET. The designed balun achieved broadband characteristics by optimizing gate-width and bias condition for the reduction in parasitic effect. From DC to more than 6GHz, the active balun shows the phase error of less than 3 degree and the gain error of less than 0.4 dB. A single-balanced down-conversion mixer with built-in broadband active balun has been designed with optimum width, load resistor and bias for conversion gain and without any matching component for broadband operating. The designed mixer whose size of including on-chip bias circuit is $1\;mm{\times}1\;mm$ shows the conversion gain of better than 7 dB from 2 GHz to 6 GHz and $P_{1dB}$ of -10 dBm at 5.8 GHz

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.281.2-281.2
• /
• 2016

Two-dimensional van der Waals (2D vdWs) materials have been extensively studied for future electronics and materials sciences due to their unique properties. Among them, black phosphorous (BP) has shown infinite potential for various device applications because of its high mobility and direct narrow band gap (~0.3 eV). In this work, we demonstrate a few-nm thick BP-based nonvolatile memory devices with an well-known poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] ferroelectric polymer gate insulator. Our BP ferroelectric memory devices show the highest linear mobility value of $1159cm^2/Vs$ with a $10^3$ on/off current ratio in our knowledge. Moreover, we successfully fabricate the ferroelectric complementary metal-oxide-semiconductor (CMOS) memory inverter circuits, combined with an n-type $MoS_2$ nanosheet transistor. Our memory CMOS inverter circuits show clear memory properties with a high output voltage memory efficiency of 95%. We thus conclude that the results of our ferroelectric memory devices exhibit promising perspectives for the future of 2D nanoelectronics and material science. More and advanced details will be discussed in the meeting.

• The Bulletin of The Korean Astronomical Society
• /
• 제40권2호
• /
• pp.52.1-52.1
• /
• 2015

FIMS/SPEAR is a dual-channel far-ultraviolet imaging spectrograph on board the Korean microsatellite STSAT-1, which was launched on 2003 September 27. The primary mission goal of FIMS was to conduct a survey of diffuse far UV emissions in our Galaxy. For this purpose, FIMS completed a survey of about 84% of the sky during its operation of a year and a half. The present study aims to analyze this survey data made in the far UV wavelengths to understand the global evolution of our Galaxy. The far UV wavelength band is known to contain important cooling lines of hot gas: hence, the study will show how the hot gas in our Galaxy, produced by stellar winds and supernova explosion, evolves globally to cool down and become mixed with ambient cooler medium. One of the main findings from previous analyses of the FIMS data is that molecular hydrogen exists ubiquitously in our Galaxy. This discovery leads to another important scientific question: how is molecular hydrogen distributed in our Galaxy and how does it affect globally the evolution of our Galaxy as a cold component? Hence, the present study will cover both the hot and cold components of the ISM, which will also provide the opportunity to investigate the interactions between the two.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• 제5권1호
• /
• pp.26-32
• /
• 2012

This paper presents a metamaterial absorber unit sell structure with four-element electric-LC resonators (ELC). In order to enhance the operating bandwidth of the proposed absorber unit cell two pairs of ELC resonators with a different size are used. The proposed unit cell shows negative permittivity and permeability when the electric field is parallel to the capacitive gap and the magnetic field is normal to the plane of ELC resonator. The simulated results show peak absorbance over 90% at two frequencies of 8.53 and 9.08 GHz, respectively.

• Journal of Korean Society for Atmospheric Environment
• /
• 제5권2호
• /
• pp.12-20
• /
• 1989

Distribution of benzo(a)pyrene (BaP) in Seoul surface soils was investigated with a simple micro-analytical method consisting of ultrasonic extraction, one-dimensional dual band thin-layer chromatographic separation (TLC) and spectrofluorometric determination. The TLC was done in the following condition: thin-layer plate; Kieselguhr G/Acetylated cellulose, Developer; 1st; ether, 2nd; methanol-ether-water (4:4:1, V/V). The results thus obtained were as follows; 1. All the samples collected from various areas were contained detectable amount of benzo(a)pyrene. The range and average of benzo(a)pyrene contents in Seoul areas are 0.20 $\sim$5.90ppm and 1.01 ppm, respectively. 2. Benzo(a)pyrene contents in soils obtained from commercial areas were much higher than those in industrial and residential areas. The contents range in commercial, industrial, and residential areas are 0.31 $\sim$ 5.90 ppm, 0.36 $\sim$ 1.22 ppm and 0.20 $\sim$ 0.67 ppm, respectively. 3. Benzo(a)pyrene contents in soils from major roads were far higher than those from side or park roads. The ranges of benzo(a)pyrene contents in major, park and side road are 0.40 $\sim$ 5.9 ppm, 0.20 $\sim$ 0.70 ppm, 0.31 $\sim$ 1.30 ppm, respectively. These findings suggest strongly that surface soils in Seoul city are polluted by benzo(a)pyrene probably emitted automobiles.

• Journal of Electrical Engineering and Technology
• /
• 제9권6호
• /
• pp.2019-2024
• /
• 2014

This paper presents a method to optimize the design of a planar-type antenna and reduce the number of design parameters for rapid computation. The electromagnetic characteristics of the structure are analyzed, and Taguchi method is used to identify critical design parameters. Adaptive particle swarm optimization, which has a faster convergence rate than particle swarm optimization, is used to achieve the design goal effectively. A compact dual-band USB dongle antenna is tested to verify the advantage of the proposed method. In this case, we can use only five selected geometrical parameters instead of eighteen to accelerate the optimization of the antenna design. The 10 dB bandwidth for return loss ranges from 2.3 GHz to 2.7 GHz and from 5.1 GHz to 5.9 GHz, covering all the WiBro, Bluetooth, WiMAX, and 802.11 b/g/n WLAN bands in both simulation and measurement. The optimization process enables the antenna design to achieve the required performance with fewer design parameters.

• Wind and Structures
• /
• 제5권6호
• /
• pp.527-542
• /
• 2002

Wind-excited vibrations of slender structures can induce fatigue damage and cause structural failure without exceeding ultimate limit state. Unfortunately, the growing importance of this problem is coupled with an evident lack of simple calculation criteria. This paper proposes a mathematical method for evaluating the crosswind fatigue of slender vertical structures, which represents the dual formulation of a parallel method that the authors recently developed with regard to alongwind vibrations. It takes into account the probability distribution of the mean wind velocity at the structural site. The aerodynamic crosswind actions on the stationary structure are caused by the vortex shedding and by the lateral turbulence, both schematised by spectral models. The structural response in the small displacement regime is expressed in closed form by considering only the contribution of the first vibration mode. The stress cycle counting is based on a probabilistic method for narrow-band processes and leads to analytical formulae of the stress cycles histogram, of the accumulated damage and of the fatigue life. The extension of this procedure to take into account aeroelastic vibrations due to lock-in is carried out by means of ESDU method. The examples point out the great importance of vortex shedding and especially of lock-in concerning fatigue.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 한국정보통신학회 2015년도 춘계학술대회
• /
• pp.824-825
• /
• 2015

본 논문은 차량 레이더용 24-GHz/77-GHz 이중 대역 CMOS 저 잡음 증폭기를 제안한다. 이러한 회로는 1.8볼트 전원에서 동작하며, 저 전압 전원 공급에서도 높은 전압 이득과 낮은 잡음지수를 가지도록 설계하였다. 제안한 회로는 TSMC $0.13-{\mu}m$ 혼성신호/고주파 CMOS 공정($f_T/f_{MAX}=120/140GHz$)으로 설계되어 있다. 전체 칩 면적을 줄이기 위해 가능한한 많은 부분에 실제 수동형 인덕터 대신 전송선을 이용하였다. 제안한 회로는 최근 발표된 연구결과에 비해 높은 전압 이득, 낮은 잡음지수 및 작은 칩 크기 특성을 보였다.

• Korean journal of applied entomology
• /
• 제35권1호
• /
• pp.85-90
• /
• 1996

Bacillus thuringiensis NT0423 produces quite a typical bipyramidal crystals of a common major band of ca. 130 kDa, and has dual specificity against Lepidoptera and Diptera. To enforce the Diptera-toxicity of B. thuringiensis NT0423, cryND gene was transformed 30 B. thuringiensis NT0423. The transfonnant B. thuringiensis PT1227 was obtained from introduction of pCGl0 into B. thuringiensis NT0423 by electroporation. The result showed that cryND and resident crystal protein genes in transformant were stably expressed with its own shape. Furthermore, the toxicity of B. thuringiensis PT1227 against Diptera was highly enforced, suggesting that the enforced toxicity of B. thuringiensis PT1227 was due to synergistic effect of both introduced and resident crystal proteins in transformant.