• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.202-207
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• 1997

Design and fabrication issues for an L-band GaAs Monolithic Microwave Integrated Circuit(MMIC) Voltage Controlled Oscillator(VCO) as a component of Personal Communications Systems(PCS) Radio Frequency(RF) transceiver are discussed. An ion-implanted GaAs MESFET tailored toward low current and low noise with 0.5mm gate length and 300mm gate width has been used as an active device, while an FET with the drain shorted to the source has been used as the voltage variable capacitor. The principal design was based on a self-biased FET with capacitive feedback. A tuning range of 140MHz and 58MHz has been obtained by 3V change for a 600mm and a 300mm devices, respectively. The oscillator output power was 6.5dBm wth 14mA DC current supply at 3.6V. The phase noise without any buffer or PLL was 93dB/1Hz at 100KHz offset. Harmonic balance analysis was used for the non-linear simulation after a linear simulation. All layout induced parasitics were incorporated into the simulation with EEFET2 non-linear FET model. The fabricated circuits were measured using a coplanar-type probe for bare chips and test jigs with ceramic packages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.386-391
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• 2006

In this paper, a design of V-type Linearly Tapered Slot Antenna(V-LTSA) with uniplanar microstrip-to-coplanar stripline(CPS) transitions is presented. The effect of reducing and increasing with taper width G, teper length L and opening angle are also considered at 5.8 GHz. In the result of a simulation by using CST-MWS, the return loss characteristic came very wide band about 4.3GHz, or 1.8 Octave. Proposed V-LTSA design schemes are expected to be a good antenna for microwave and millimeter-wave communcations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.25-29
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• 2002

There is an increasing interest in high-speed signal processing in modern telecommunication and SC circuit, HDTV, ISDN. There are many methods of high-speed signal processing. This paper describes a design approach for the realization of high-frequency Op-amp in CMOS technology. A limiting factor in Op-amp based analog integrated circuits is the limited useful frequency range. this thesis will develop a CMOS op-amp architecture with improved gainband width product with this technique an op-amp will achieve up to 170MHz (CL=2pF) unity-gain frequency with a 1.2-micron design rule. This CMOS op-amp is particularly suitable for achieving wide and stable closed-loop band widths, such as required in high-frequency SC filters, high-speed analog circuits.

• Bulletin of the Korean Mathematical Society
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• v.59 no.2
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• pp.285-301
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• 2022

In this paper, we mainly study the random sampling and reconstruction of signals living in the subspace V^p(𝚽, 𝚲) of L^p(ℝ^d), which is generated by a family of molecules 𝚽 located on a relatively separated subset 𝚲 ⊂ ℝ^d. The space V^p(𝚽, 𝚲) is used to model signals with finite rate of innovation, such as stream of pulses in GPS applications, cellular radio and ultra wide-band communication. The sampling set is independently and randomly drawn from a general probability distribution over ℝ^d. Under some proper conditions for the generators 𝚽 = {𝜙_λ : λ ∈ 𝚲} and the probability density function 𝜌, we first approximate V^p(𝚽, 𝚲) by a finite dimensional subspace V^p_N (𝚽, 𝚲) on any bounded domains. Then, we prove that the random sampling stability holds with high probability for all signals in V^p(𝚽, 𝚲) whose energy concentrate on a cube when the sampling size is large enough. Finally, a reconstruction algorithm based on random samples is given for signals in V^p_N (𝚽, 𝚲).

• Journal of the Korean Graphic Arts Communication Society
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• v.21 no.2
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• pp.43-53
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• 2003

As information-communication network has been developed rapidly, internet users' circumstances also have been changed for the better, in result, more information can be applied than before. At this moment, there are many differences between real color and reappeared color on the CRT. When we observe a material object, our eyes perceive the multiplied form of light sources and nature spectral reflection. However, when the photographed signal is reappeared, illumination at that time of photographing and spectral reflection of a material object are converted into signal, and this converted RGB signal is observed on the CRT under another illumination. At this time, RGB signal is the reflected result of illumination at that time of photographing Therefore, this signal is influenced by the illumination at present, so it can be perceived another color. To accord the colro reflections of another color source, the study has been reported by S.C.Ahn$^{[1]}$, which study is about the color reapperarance system using neuron network. Furthermore, color reappearing method become independent of its circumstances has been reported by Y.Miyake$^{[2]}$. This method can make the same illuminations even if the observe circumstances are changed. To assume the light sources of observe circumstances, the study about color reappearing system using CCD sensor also have been studied by S.C.Ahn$^{[3]}$. In these studies, a population is fixed, first, on ab coordinates of CIE L${\ast}$a${\ast}$b${\ast}$. Then, color reappearing can be possible using every population and existing digital camera. However, the color is changed curvedly, not straightly, according to value's changes on the ab coordinates of CIE L${\ast}$a${\ast}$b. To solve these problems in this study, first of all, Labeling techniques are introduced. Next, basis color-it is based on Munsell color system-is divided into 10 color fields. And then, 4 special color- skin color, grass color, sky color, and gray-are added to the basis color. Finally, 14 color fields are fixed. After analyzing of the principle elements of new-defined-color fields' population, utility value and propriety value are going to be examined in 3-Band system from now on.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.7
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• pp.646-652
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• 2013

EU's Galileo project is a market-based GNSS (Global Navigation Satellite System) that is under development. It is expected that Galileo will provide the positioning services based on new technologies in 2020s. Because Galileo E1 signal for OS (Open Service) shares the same center frequency with GPS L1 C/A signal, CBOC (Composite Binary Offset Carrier) modulation scheme is used in the E1 signal to guarantee interoperability between two systems. With E1 signal consisting of a data channel and a pilot channel at the same frequency band, there exist several options in designing signal acquisition for Assisted-Galileo receivers. Furthermore, compared to SNR worksheet of Assisted-GPS, some factors should be examined in Assisted-Galileo due to different correlation profile and code length of E1 signal. This paper presents SNR worksheets of Galileo E1 signals in E1-B and E1-C channel. Three implementation losses that are quite different from GPS are mainly analyzed in establishing SNR worksheets. In the worksheet, hybrid long integration of 1.5s is considered to acquire weak signal less than -150dBm. Simulation results show that the final SNR of E1-B signal with -150dBm is 19.4dB and that of E1-C signal is 25.2dB. Comparison of relative computation shows that E1-B channel is more profitable to acquire the strongest signal in weak signal environment. With information from the first satellite signal acquisition, fast acquisition of the weak signal around -155dBm can be performed with E1-C signal in the subsequent satellites.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.51-55
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• 2007

As for satellite programs, the multipurpose satellite 1(KOMPSAT-1) was successfully launched on Dec. 21, 1999 and operated for three years. It is still properly operated even though its life cycle was ended. The development of KOMPSAT-2 (Korea Multipurpose Satellite-2) is near completion and the development of KOMPSAT-3, KOMPSAT-5 and COMS (Communication, Ocean, Meterological Satellite) are proceeding swiftly. In KORDI(Korea Ocean Research and Development Institute), the KOSC (Korea Ocean Satellite Center) construction project is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI(Geostationary Ocean Color Imager) instrument which is loaded on COMS(Communication, Ocean and Meteorological Satellite); it will be launched in 2000. Ansan(the headquarter of KORDD has been selected for the location of KOSC between 5 proposed sites, because it has the best condition to receive radio wave. The data acquisition system is classified antenna and RF. Antenna is designed to be ${\emptyset}$ 9m cassegrain antenna which has 19.35 $G/T(dB/^{\circ}K)$ at 1.67GHz, RF module, is divided into LNA(Low noise amplifier) and down converter, those are designed to send only horizontal polarization to modem The existing building is re-designed and classified for the KOSC operation concept; computing room, board of electricity, data processing room, operation room Hardware and network facilities have been designed to adapt for efficiency of each functions. The distribution system which is one of the most important systems will be constructed mainly on the internet, and it is also being considered constructing outer data distribution system as a web hosting service for to offering received data to user under an hour.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.49-56
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• 2006

This paper describes the design and the verification of IEEE 802.15.4 LR-WPAN 2.4GHz Physical layer for Ubiquitous Sensor Network(USN). We designed the Carrier Frequency Offset(CFO) compensation satisfied the frequency tolerance of IEEE 802.15.4 LR-WPAN and the adaptive matched filter that re-setting of the threshold for the symbol synchronization of the various USN environment. The multiplications is reduced 1/16 by this method each other at i, q phases and has 0.5dB performance improvement in detection probability. Proposed baseband system is designed with verilog HDL and implemented using FPGA prototype board.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1083-1092
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• 2016

In this paper, the performance of the optical code-division multiple access (OCDMA) technology on a plastic optical fiber (POF) access network, which had received much attention due to its low weight, large core diameter, flexibility, easy installation, and especially its high bandwidth, is analyzed. Recently, POF was a very attractive candidate for transmission media in an access network based on OCDMA technology. But the conventional OCDMA system only allows finite units to transmit and access simultaneously according to the number of channels which are restricted by BER, and so, in this paper, to resolve this problem a novel multi-priority reservation protocol is also proposed. By using this reservation scheme and a distributed arbitration algorithm, channel collision and destination conflict could be avoided. And this protocol can efficiently support the transmission of multimedia messages that require the different time-delay. The network throughput and average delay using various system parameters have been investigated by numerical analysis and simulation experiments. These results shows that the multi-priority reservation protocol in this POF access network based on OCDMA technology is valid and efficient.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.114-121
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• 2003

In this paper, low voltage and two stage CMOS Class E RF power amplifier for ISM(Industrial/Scientific/Medical) Open Band is presented. The power amplifier operates at 2.4GHz frequency, and is designed and simulated with a 0.35um CMOS technology and HSPICE simulator. The power amplifier is simple structure of two stage Class E power amplifier. The design procedure determing matching network was presented. The power amplifier is composed of input stage matching network, preamplifier, interstage matching network, power amplifier, and output stage matching network. The matching networks of input stage and interstage were constituted by pi($\pi$) type and L type respectively. At 2.4GHz operating frequency, and with a 2.5V supply voltage, the power amplifier delivers 23dBm output power to a 50${\Omega}$ load with 39% power added efficiency(PAE).