• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1109-1114
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• 2003

In this paper, the electric characteristic of the SGPS with slot in the ground plane is similar to the parallel resonant circuit. When the slot length in SGPS is equal to the half wavelength of specific frequency, the characteristic of SGPS represent the large attenuation at the specific frequency. We found out the relation between attenuation and resistor on the slot in SGPS and we designed the variable attenuator for MMIC using the variable resistor. This attenuator can be applied to AGC circuit in transceiver if the PIN diode is used replace for resistor.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.183-186
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• 2000

In this paper we propose a new architecture of a programmable digital automatic gain controller(AGC) for analog interface in mixed mode systems. Compared with conventional analog AGCs which have difficulties in integration due to large capacitors, the proposed AGC is easily integrated. So the production cost can be reduced. In addition, The proposed AGC has a better performance in temperature, and power supply variations, and substrate noise than analog counterparts do. To prevent erroneous operations of the AGC due to noise, a mal-function preventer is newly proposed. In addition, to achieve an optimized AGC time constant, we propose a logic block which controls an up-down counting clock. This is directly related to the changing speed of the AGC gain. Implemented with a 0.25 $\mu\textrm{m}$ 1-poly, 5-metal CMOS parameters, the AGC operates from a single 2.5V power supply with the dynamic range of 36.ldB and occupies active area of 500$\mu\textrm{m}$${\times}$600$\mu\textrm{m}$

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.567-572
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• 2004

This paper shudies an automatic gain control(AGC) algorithm used in wireless communication cellular systems. The AGC design includes the selection of the appropriate analog-to-digital converter(ADC) and keeping the input power to the ADC constant to minimize the quantization noise generated from the analog-to-digital conversion process. In this paper the process to determine the required precision or the An is illustrated and the method to set the design parameters of the AGC is proposed. And the validity of the proposed algorithm is verified by computer simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.96-102
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• 2004

In this paper, optical noise is reduced by a differential detector, which is composed of a beam splitter and two photodiodes whose spectral responses are different each other. In this configuration, the automatic gain control circuit is not required for noise cancellation because the noise intensities at the two photodiodes are kept equal by a beam splitter. The signal to noise ratio in a differential detector with a beam splitter was improved to be 14 ㏈ higher than in a single photodiode with optical filtering.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.129-133
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• 2020

In this paper, a temperature compensation circuit is presented in order to mitigate gain variability due to temperature in the W-band low-noise amplifier (LNA). The proposed cascode temperature compensation bias circuit automatically controls gate bias voltages of the common-source LNA in order to suppress variations of small-signal gain. The designed circuit was realized in a 100-nm GaAs pHEMT process. The simulated voltage gain of W-band LNA including the proposed bias circuit is >20 dB with gain variability less than ±0.8 dB in the range of temperatures between -35 to 71℃. We expect that the proposed circuit contributes to millimeter-wave receivers for stable performances in radar applications.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.39-44
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• 1999

High-resolution images are drawn from existing seismic data which were originally obtained by Korea Ocean Research & Development Institute (KORDI) during 1994-1997 for deep seismic studies on the East Sea of Korea. These images are analyzed for mapping Quaternary faults and near-bottom gas pockets. First 12 channels are selected from shot gathers for reprocessing. The processing sequence adopted for high-resolution seismic images comprises data copy, trace editing, true amplitude recovery, common-midpoint sorting, initial muting, prestack deconvolution, bandpass filtering, stacking, highpass filtering, poststack deconvolution, f-x migration, and automatic gain control (AGC). Among these processing steps, predictive deconvolution, highpass filtering, and short window AGC are the most significant in enhancement of resolution. More than 200 Quaternanry faults are interpreted on the migrated sections in the shallow depths beneath the seafloor. Although numerous faults are found mostly at the western continental slope and boundaries of the Ulleung Basin, significant amount of the faults are also indicated within the basin. Many of these faults are believed to be formed with reactivation of basement, from geotectonic activities including volcanism, and often originated in Tertiary, indicating that the tectonic regime of the East Sea might be unstable. Existence of shallow gas pockets casts real hazardous warnings to deep-sea drillings and/or to underwater constructions such as inter-island cables and gas pipelines. On the other hand, discovery of these gas pockets heightens the interests in developing natural resources in the East Sea. Reprocessed seismic sections, however, show no typical seismic characteristics for gas hydrates such as bottom-simulating reflectors in the western continental slope and ocean floor.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.213-219
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• 2004

In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in $V_P$ and $I_{DSS}$ will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets $V_{gs}$ for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in $P_{1dB}$.

• Proceedings of the Korean Professional Engineer Association Conference
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• 1996.12a
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• pp.76-102
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• 1996

북한은 전력부족난과 전기품질의 저하로 인하여 주요 생산기업에 지장을 주고 있으며, 노후 발전소의 성능저하도 함께 진행되고 있는 것으로 추정된다. 이에 대한 적절한 대책이 없는 한 그 상황은 더욱 악화될 전망이다. 한반도 에너지 개발기구(KEDO)가 추진하고 있는 경수로 원자력 발전기가 6～7년 후에 준공된다고 해도 이처럼 불안정한 전력계통에 병입되어 원활한 운전이 가능할런지 기대하기 곤란하다. 이러한 실정에서 \circled1 전력부족으로 주파수가 저하될 때 우선 순위가 낮은 부하를 제한하는 자동 부하제한 방식을 포함한 자동 주파수 제어 계통개선 \circled2 기존발전소 성능과 이용을 향상을 위한 재가동(Repowering) 등의 리 엔지니어링 \circled3 가스터빈 복합화력과 열병합발전(Co-generation) 등과 같이 건설기간이 짧고 비용이 적게 들며 송전 설비 건설도 불필요한 분산형 전원의 건설 \circled4 수력발전소와 조력발전소의 건설 \circled5 양수발전 등 전력에너지 저장설비의 개발 \circled6 송전전압격상과 배전방식개선 및 종합전력정보시스템 구축 \circled7 남ㆍ북한 전력계통 내지는 동북아시아 전력계통을 연계하는 평화망사업(Peace Network Project)등의 추진이 경수로 사업에 선행되어야 한다. 특히 러시아, 중국, 한국, 일본의 발전 에너지원 분포와 년간 부하곡선을 고려할 때 동북아시아 전력계통의 연계는 관련국 상호간에 에너지 환경과 경제적 측면에서 상당한 이득과 안정성을 강화해 줄 것이며, 기술발전과 평화공존에 크게 기여 할 것이다. 이를 위하여 관련국의 전력계통연계 전문가들이 참여하는 남\ulcorner북한전력 계통연계연합회(Co-Pia ; Co-rea Power Systems Interconnection Association)와 동북아지역전력 계통연합회(Near Pia=North-Eastern Asia Region Power Systems Interconnection Association)의 구성을 제안하는 바이다. 주요용어(Key Words): 자동주파수 제어(AFC), 리엔지니어링(Re-Engineering), 분산형 전원(Dispersed Generation System), 전력저장(Power Storage), 부하조절기(Load Conditioner), 수요관리(DSM) 연계(Interconnection), 인터시스템(Intersystem), 통합자원계획(IRP), 안전성 강화(Security Enhancement), 전력시장개방(Electricity Free Maket), 통일비용(Unification Expense, Unification Cost), 남ㆍ북한전력계통연계연합회(Co-Pia), 동북아지역전력 계통연계연합회(Nea,-Pia).

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.399-402
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• 2005

For efficient and accurate diagnosis of ultrasound images, the time gain compensation (TGC) and dynamic range (DR) control of the ultrasound echo signal are important. TGC is for compensating the attenuation of the ultrasound echo signal along the depth, and DR is used to control the image contrast. In this paper, we propose an algorithm for finding the optimized values of TGC and DR automatically. For TGC, the degree of compensation is determined along the depth based on the effective attenuation estimation of ultrasound signal. For DR optimization, we introduce a novel cost function on the basis of the characteristics of ultrasound image, which provides the minimum value at the optimal DR. Experiments have been performed by applying the proposed algorithm to a real US imaging system. The results show that the algorithm automatically can determine the values of TGC and DR in realtime so that the subjective quality of the corresponding US image may be good enough for diagnosis.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.342-349
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• 1998

A multipurpose TLD readout system for radiation dosimetry and thermoluminescence study is constructed and its characteristics are investigated. The thermoluminescent lights are measured by a PM tube and the current-to-frequency converter. TLDs are heated by platinum heater and the heating rate is linearly varied. Measurement of the glow curve and control of the whole system have been done by a personal computer equipped with an interface board. The automatic gain control can be done by the control software. The lower detection limit of the system is about $10\;{\mu}Gy$ and dose response is linear.