• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.678-685
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• 2013

In this paper, we propose a design of dual-band patch antennas for Global Positioning System(GPS) applications, and the designed antenna is used as an individual element of GPS arrays. A low distortion and a high isolation of the array are achieved by adjusting rotating angles of each array element. The antenna consists of two radiating patches that operate in the GPS $L_1$ and $L_2$ bands, and the two ports feeding network with a hybrid chip coupler is adopted to achieve a broad circular polarization(CP) bandwidth. The rotating angles of each antenna element are varied with four directions(${\phi}=0^{\circ}$, ${\phi}=90^{\circ}$, ${\phi}=180^{\circ}$, ${\phi}=270^{\circ}$) in order to minimize the pattern distortion and maximize the isolation among array elements. The measurement shows bore-sight gains of 0.3 dBic($L_1$) and -1.0 dBic($L_2$) for the center element. Bore-sight gains of 1.6 dBic($L_1$) and 1.0 dBic($L_2$) are observed for the edge element. This results demonstrate that the proposed antenna is suitable for GPS array applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.230-233
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• 2002

본 논문에서는 안테나의 이득을 극대화하기 위해서 Bluetooth PCB Layout 위에 Bluetooth용 내장형 마이크로 칩 안테나를 직접 설계하여 Bluetooth의 주요 사양인 2.4~2.4835GHz에서 동작할 수 있도록 Bluetooth용 내장형 마이크로 칩 안테나를 설계하였다. Bluetooth PCB Layout 크기는 실제 크기와 같은 54mm$\times$19mm$\times$2.4mm로 설계하고 마이크로 칩 안테나 크기는 11mm$\times$4mm$\times$l.6mm로 설계하여 상용화 된 프로그램인 HFSS에 의해 3.616dBi의 이득을 얻었다. 설계 제작된 Bluetooth용 내장형 마이크로 칩 안테나는 2.45GHz의 중심주파수에서 넓은 대역폭 10.71%을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1158-1165
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• 2004

This paper describes the design of a two stage 1V power supply SiGe Low Noise Amplifier operating at 5.25㎓ for 802.lla wireless LAN application. The achieved performance includes a gain of 17㏈, noise figure of 2.7㏈, reflection coefficient of 15㏈, IIP3 of -5㏈m, and 1-㏈ compression point of -14㏈m. The total power consumption of the circuit was 7㎽ including 0.5㎽ for the bias circuit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.891-895
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• 2010

A dual-band (UHF: 470-862 MHz, L: 1452-1492 MHz) digital video broadcasting-handheld (DVB-H) antenna is presented. The proposed antenna is composed of a planar inverted F-shape antenna (PIFA) with an input impedance matching circuit. The matching circuit improves antenna performance in the broad UHF bands (470-862 MHz: 63%). The proposed antenna has omni-directional patterns and sufficient gain (Ave. peak gain is about 1.70 dBi over 470-862 MHz) for the PMP applications. The antenna is contact with a PMP case (${\varepsilon}_r=3.2$) which is used as a substrate for the size reduction and compact design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1191-1202
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• 1994

We numerically investigate a stable propagation regime of soliton pulse trains in fibers with periodically copensated loss by lumped optical amplifiers. When amplification solition pulses is 1.2~1.5 and the minimum soliton separation normalized by the soliton width becomes about 6. In cases of L=50[km], the allowable range of A is 1.5~1.7 under =6. The maximum allowable variation of the loss compensation in each lumped amplifier becomes +-2% of the fiber loss when L=50[km], A=1.6, and =6. Generally, the allowable rages of the soliton amplitude A and amplifier gain are inversely proportional to the amplification period L.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.11
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• pp.34-41
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• 2003

In this paper, 60GHz band transmitter and receiver for wireless LAN are designed and implemented using the broband amplifier and mixer fabricated by standard 0.1${\mu}{\textrm}{m}$ MIMIC process of MINT. Output power and gain of the RF transmitter are 0 ㏈m and 1.7㏈, respectively. Noise figure and gain of the receiver are 4.2㏈ and l5.7dB, respectively. Considering the sensitivity and LOS test, this system can communicate with BER of below than 10$^{-6}$ at a distance more than 35m. DSSS, which is strong for concealment and disturbance, is adopted.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.10-17
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• 1989

A new design method of lossy matching network for the microwave broadband ampilfier is presented by using seattering parameters instead od modeling of transistor. A lossy matching network is represented as the combination of 2 lossless networks between which lossy serial or parallel immittance is inserted without using specific topology, and so many useful matching cireuits can be realized. Also it is shown that linear transforming relation exists between gain and reflection coefficient of the amplifier, and the transforming equation is derived using scattering parameters. With this equation some constant gain circles can be drawn on reflection coefficient plane to get adequate reflection coefficient and gain. And since the relations between amplifier gain/reflection coefficient and the immittance of passive element are bilinear transformations. constant gain or reflection coefficients circles. Illustrative examples are presented to show the usefulness of proposed method.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.806-809
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• 2008

온칩(on-chip) 캐쉬는 외부 메모리로의 접근을 감소시키는 중요한 역할을 한다. 본 연구에서는 내장형 시스템에 맞추어 설계된 2-레벨 캐쉬 메모리 구조를 제안하고자 한다. 레벨1(L1) 캐쉬의 구성으로 작은 크기, 직접사상(direct-mapped) 그리고 바로쓰기(write-through)를 채용한다. 대조적으로 레벨2(L2) 캐쉬는 일반적인 캐쉬 크기와 집합연관(Set-associativity) 그리고 나중쓰기(write-back) 정책을 채용한다. 결과적으로 L1캐쉬는 한 사이클 이내에 접근될 수 있고 L2캐쉬는 전체 캐쉬의 미스율(global miss rate)을 낮추는데 효과적이다. 두 캐쉬 계층간 바로쓰기(write-thorough) 정책에서 오는 빈번한 L2 캐쉬 접근으로 인한 에너지 소비를 줄이기 위해 본 연구에서는 One-way 접근 기법을 제안하였다. 본 연구에서 제안한 2-레벨 캐쉬 메모리 구조는 평균적으로 26%의 성능향상과 43%의 에너지 소비 그리고 77%의 에너지-지연 곱에서 이득을 보여주었다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.9
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• pp.511-519
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• 2003

In this paper, we considered the design of gain scheduled controllers for linear systems with saturating actuators. Our basic idea is to design a control that uses higher control gain when the states are smaller, and lower gain when it is higher. By doing this, we can avoid the saturation and we can improve the performance. First, we derive a control and a reachable set expressed as LMI form, which minimizes not only the L$_2$ gain from the disturbance to the measured output but also the control is never saturated within this reachable set. Next, the reachable set is divided as nested subsets, and at each nested subset, the control gain is designed to minimize the L$_2$ gain and it is never saturated. Finally, the control gain is scheduled according to the status of states, i.e., the subset in which the states are located. A numerical example is presented to show that our gain scheduled control significantly improves the performance.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.335-338
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• 2003

In this paper, we considered the design of gain scheduled controllers for linear systems with input constraints. The gain scheduled control is a method that uses larger control gain when the states are smaller, and smaller gain when it is larger. By doing this, we can use a full actuator capacity. Also we allow the over-saturation in control to improve the performance. First, we derive a control and a reachable set expressed as LMI form, while minimizing the $L_2$ gain from the disturbance to the measured output. Next, the reachable set is divided as nested subsets, and the control gains are obtained by minimizing the $L_2$ gain at each nested subset. Finally, the control gains are scheduled according to the status of states, i.e., the nested-subset in which the states are located. Performance of the proposed technique is illustrated through simulations of a six-story building subject to earthquake ground motion.