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RISS 인기검색어
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- 저자 : 오혁준(Hyukjun Oh) (검색결과 22 건)
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협대역 통신시스템을 위한 전처리기-등화기 구조의 FIR 여파기 설계
오혁준(Hyukjun Oh),안희준(Heejune Ahn) 한국통신학회 2005 한국통신학회논문지 Vol.30 No.6C
본 연구는 협대역 통신시스템을 위한 전처리기-등화기 구조의 여파기에서, 곱셈기를 사용하지 않는 최소 복잡도의 디지털 FIR 여파기를 설계하는 방법을 제안한다. 제안하는 여파기는 순환 다항식(cyclotomic polynomial, CP) 여파기와 2차 내삽 다항식(interpolated second order polynomial, ISOP) 등화기로 구성되며, 이 두 여파기가 동시에 혼합 정수 선형 계획법(mixed integer linear programming (MILP))으로 최적 설계되어 최소의 복잡도를 갖는 특성을 갖게 된다. 제안된 방식으로 설계된 여파기들은, 설계 규격을 만족하면서도 기존의 여파기에 비하여 복잡도면에서 월등히 간단함을 확인하였다.
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유신우,오혁준,Yoo, Sinwoo,Oh, Hyukjun 한국정보통신학회 2022 한국정보통신학회논문지 Vol.26 No.5
This paper shows a small and low-powered wireless communication system based on the ATSC broadcasting system using the ISM frequency band that can be used as a PBS(Personal Broadcasting System). It is designed to demonstrate a channel-adaptive CR(Cognitive Radio) system to provide a better service quality in the unlicensed band where co-channel interference exists. And it achieved very reliable communications by a closed-loop active phased array antenna. This ATSC-based personal broadcasting platform can be modified easily with given flexibility by using GNU Radio as an open-source signal processing platform based on USRP and implementing additional functions in FPGA. In addition, the chosen communication frequency resource can be managed and controlled by the return channel that transmits the channel status and communication parameters between transmission and reception in real-time.
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C# 프로그래밍 무기체계 소프트웨어에 대한 신뢰성 시험 기준 연구
신봉득,오혁준,Shin, Bongdeug,Oh, Hyukjun 디지털산업정보학회 2016 디지털산업정보학회논문지 Vol.12 No.4
Defense Acquisition Program Administration's weapon system software development and management guideline specifies the criteria of software reliability tests including static and dynamic tests mainly on C/C++ languages. Recently, Defense Acquisition Program Administration expanded the scope of software reliability test for the various languages including C#, java etc. but specific criteria for them are not established. This study suggests the reliability test procedures and standards on C# programming software in weapon system. For the static test, considering the nature of the C# which depends on .NET framework, this paper introduces applying coding rules recommended by Microsoft Corp. Visual Studio 2012. Block coverage provided by Visual Studio is applied on dynamic tests and the achievement objectives for block coverage according to the software levels(A, B, C) are suggested. Also, the software reliability test procedures and standards proposed by this paper are properly verified through the case study. The result of this study can be used for establishing the specific criteria of the software reliability test for C# programming software in weapon system.
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도플러 주파수 관찰을 위한 무선 신호의 주파수 영역 해상도 향상
홍예린,오혁준,Hong, Yerin,Oh, Hyukjun 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.12
There are many research to find not only user data but also physical information about objects or human in radio signals. And we can obtain physical information from the wireless signals such as RSSI (Received Signal Strength Indicator), Doppler frequency and other values. For example, the Doppler frequency is generated by the object moving physically in wireless signals used for communication. By analyzing the Doppler frequency, the moving speed and direction of the object can be predicted. In this paper, we study the previous research which is to detect the moving objects or human using wireless signals, 802.11a signals. We introduce and verify the method to improve the frequency domain resolution of commercial 802.11a receivers to observe the doppler frequency and obtain the information of the moving objects or human.
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MFCC와 CNN을 이용한 저고도 초소형 무인기 탐지 및 분류에 대한 연구
신경식,유신우,오혁준,Shin, Kyeongsik,Yoo, Sinwoo,Oh, Hyukjun 한국정보통신학회 2020 한국정보통신학회논문지 Vol.24 No.3
This paper is related to detection and classification for micro-sized aircraft that flies at low-altitude. The deep-learning based method using sounds coming from the micro-sized aircraft is proposed to detect and identify them efficiently. We use MFCC as sound features and CNN as a detector and classifier. We've proved that each micro-drones have their own distinguishable MFCC feature and confirmed that we can apply CNN as a detector and classifier even though drone sound has time-related sequence. Typically many papers deal with RNN for time-related features, but we prove that if the number of frame in the MFCC features are enough to contain the time-related information, we can classify those features with CNN. With this approach, we've achieved high detection and classification ratio with low-computation power at the same time using the data set which consists of four different drone sounds. So, this paper presents the simple and effecive method of detection and classification method for micro-sized aircraft.
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무선랜 시스템을 위한 적응형 빔포밍 시스템의 설계 및 구현
오주현,곽경훈,오영석,조성민,오혁준,Oh, Joohyeon,Gwag, Gyounghun,Oh, Youngseok,Cho, Sungmin,Oh, Hyukjun 한국정보통신학회 2014 한국정보통신학회논문지 Vol.18 No.9
This paper presents the implementation and design of the advanced WI-FI systems with beam-forming antenna that radiate their power to the direction of user equipment to improve the overall throughput, contrast to the general WI-FI systems equipped with omni-antenna. The system consists of patch array antenna, DSP, FPGA, and Qualcomm's commercial chip. The beam-forming system on the FPGA utilizes the packet information from Qualcomm's commercial chip to control the phase shifters and attenuators of the patch array antenna. The PCI express interface has been used to maximize the communication speed between DSP and FPGA. The directions of arrival of users are managed using the database, and each user is distinguished by the MAC address given from the packet information. When the system wants to transmit a packet to one user, it forms beams to the direction of arrival of the corresponding user stored in the database to maximize the throughput. Directions of arrival of users are estimated using the received preamble in the packet to make its SINR as high as possible. The proposed beam-forming system was implemented using an FPGA and Qualcommm's commercial chip together. The implemented system showed considerable throughput improvement over the existing general AP system with omni-directional antenna in the multi-user communication environment.
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하영석,최증원,김동현,오혁준,Ha, Youngseok,Choi, Jeungwon,Kim, Donghyun,Oh, Hyukjun 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.12
A closed loop wireless transmission method adaptive to mobile unit speed is proposed in this paper. A mobile communication node measures the mobile speed based on the transmitted pilot signals through Doppler frequency estimation, and it changes the transmission period of pilot signals as per estimated mobile speed adaptively. The pilot signals with the different transmission periods are transmitted using the different PN sequences with the previous ones without any explicit information about the new period. The corresponding receiver node can detect and extract the transmitted pilot signals through blind search of the transmitted PN sequences of the pilot signals, and it can demodulate and decode the transmitted information using the channel estimation results based on the detected pilot signals. The performance of the proposed method had been analyzed through the simulation under the fading channel environments and compared with the previous methods. The simulation results showed performance improvement of the proposed method over the existing ones.
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