• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.209-216
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• 1999

KITSAT-3, the third satellite of KITSAT series which has been developed for the last four and half years with purely Korean design and implementation technology, was launched successfully at last. All subsystems were tested and validated during the initial operation of the satellite. During the initaial operation phase, the Earth imaging camera on board KITSAT-3 acquisited several tens of scenes all over the world and transmitted the image data to ground station. The quality of images and the reliability of data transmission-reception system were tested qualititively and quantititively, respectively. In this paper, we summarize the camera, data handling, on-board memory, and image data transmission system of KITSAT-3 as well as the image receiving and archiving system in ground station. The error rate of image data transmission and reception was tested during the initial operation phase. The average data transmission error rate satisfied the initial requirement of less than 1%. The error rate will be reduced through the continuous work of test and stabilization of the ground system hardware.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4C
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• pp.330-335
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• 2008

This paper proposes a packet detection algorithm for IEEE802.11n system. IEEE802.11n is a multiple input multiple output (MIMO) system and we have to consider several combining techniques which are used in multiple receive antenna system. In this paper, we propose a hybrid packet detection algorithm which combines double sliding window algorithm or delay and correlation algorithm, that is used in single input single output (SISO) system, and multiple receive antenna combining algorithms, and simulated their performances in Iin system environments and shows the results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.71-78
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• 2005

In this paper, we propose a transceiver for noncoherent OOK(On-Off Keying) Ultra Wide Band system based on magnitude detection. The proposed transceiver are designed using 0.18 micron CMOS technology and verified by simulation using SPICE and measurement. The proposed transceiver consist of parallelizer, Analog-to-Digital converter, clock generator, PLL and impulse generator. The time resolution of 1ns is obtained with 125MHz system clocks and 8x parallelization is carried out. The synchronized eight outputs with 2-bit resolution are delivered to the baseband. Impulse generator produces 1ns width pulse using digital CMOS gates. The simulation results and measurement show the feasibility of the proposed transceiver for UWB communication system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.955-964
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• 2010

In this paper, a compensation method of the amplitude and phase errors from the T/R(Transmit/Receive) modules in an active SAR(Synthetic Aperture Radar) system is introduced. The errors are defined and classified, and characterized by analyzing the measurement data acquired from the pilot test. To compensate these errors, a control methodology of T/R modules output is proposed. Before the compensation is applied, 16 T/R modules integrated on the active SAR antenna show the amplitude in 28.2~29.0 dBm and the phase in $101.7^{\circ}{\sim}165.2^{\circ}$. After the compensation, the amplitude and phase are distributed in 27.4~28.0 dBm and $116.1^{\circ}{\sim}120.0^{\circ}$ respectively. The antenna beam patterns generated by the array theory with the distributions are compared, and the proposed method is verified as good to apply for the active SAR system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1380-1387
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• 2012

The transmit/receive(T/R) module is a key component in the active phased array system. The brick-type T/R module has been widely used and the miniaturization has been an important factor to get the flexibility of the system configuration. For the miniaturization, multi-function chips(MFC) having a common leg configuration are suitable to reduce the number of required MMICs and a high isolation between transmit and receive paths is necessary for the high gain T/R modules. In this work, we propose a bias timing scheme for the compact T/R module and show the optimum timing based on measurements, in order to improve the feed-back path loop problem and the consequent isolation problem of the common leg configuration. We have implemented high power(7 W/channel) and high T/R gain(35 dB transmit and 30 dB receive gains) within the half size($140{\times}80{\times}16mm^3$) of the conventional T/R modules.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.401-407
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• 2021

The continuous active sonar technology is effective for detecting and tracking targets because of short target revisiting rate. Generalized Sinusoidal Frequency Modulation (GSFM) pulses suitable for continuous active sonar systems are known to be capable of obtaining high time-bandwidth product while maintaining the orthogonality between pulses. However, it is unknown how to calculate an appropriate length of time to correlate received GSFM pulses in the presence of a target with acceleration. In this paper, we propose a method to calculate the appropriate time length based on the correlation when matching the received signal in the continuous active sonar system using GSFM pulse. The proposed method calculates the correlation according to the acceleration of the target and calculates the signal processing length according to the correlation. It is shown that stable detection performance can be obtained when the signal processing length calculated by the proposed method through the level of the sidelobe is applied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.17-22
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• 2009

A switch or circulator is used for distinguishing between the paths of transmitter and receiver in TDD systems. If the isolation between Tx and Rx paths is low in TDD systems, the output signal of the ransmitter acts as an interferer to the receiver even if the transceiver operates on the receiver mode. In this paper we propose a method to get high isolation characteristics between transmitting and receiving paths in TDD systems. We implement the module with a proposed improving method to verify the effect of the isolation improvement and the experimental results are presented. The isolation improvement of above 44.8 dB over the frequency bandwidth of 30 MHz is obtained from the implemented isolation improvement module.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.1-7
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• 2006

Lattice decoding concept has been proposed for the implementation of the Maximum-Likelihood detection which is the optimal receiver from the viewpoint of the BER (Bit Error Rate) performance for MIMO (Multiple Input Multiple Output) systems. Sphere decoding algorithm and K-best decoding algorithm are based on the lattice decoding concept. A K-best decoding algorithm shows a good BER performance with relatively low complexity. However, with small K value, the error propagation effect severely degrades the performance. In this paper, we propose an adaptive K-best decoding algorithm which has lower average complexity and better BER performance than conventional K-best decoding algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.105-109
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• 2008

클러스터 파일시스템은 근거리 또는 원거리에 있는 클러스터 시스템 간에 연구데이터 공유 뿐 아니라, 실시간 계산을 위한 데이터 저장 공간으로 사용되는 네트워크 기반의 파일시스템이다. 고도의 과학계산을 처리할 때 계산노드들은 네트워크를 통해 연결된 클러스터 파일시스템으로부터 대용량의 데이터를 송수신하는 과정에서 CPU의 부하가 생기게 되고 이러한 문제는 계산노드로 하여금 과학계산의 속도를 저하시키는 요인이 된다. 본 논문에서는 패킷 송수신으로 인한 CPU 부하를 줄이고 이를 통하여 계산 성능을 향상시킬 목적으로 계산노드에서 수신하는 패킷들에 대해 인터럽트를 통합할 때 CPU 사용률에 미치는 영향을 분석하였다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.56-58
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• 2015

본 논문은 자기유도 무선전력 전송하에 송수신부간 양방향 자기장 무선통신 시스템을 제안한다. 송수신부의 무선전력전송 중 양방향 무선통신은 수신부가 장착된 전자기기의 무선충전시 수신부의 안정적인 전력공급 측면에서 필수적이다. 제안하는 양방향 자기장 무선통신 시스템은 송수신부간 복잡한 IC 회로 또는 추가적인 무선통신회로 없이 단순 공진 필터 및 통신용 변압기만을 이용하여 외부환경에 강인하면서도 경제적인 무선통신이 가능하다. 본 논문에서는 제안하는 자기장 무선통신 시스템의 전력선 및 통신선 등가회로를 각각 분석하였고 실험 및 시뮬레이션을 통해 그 타당성을 검증하였다.