• Journal of Navigation and Port Research
• /
• v.45 no.6
• /
• pp.360-365
• /
• 2021

LTE-maritime, which was built as part of the Korean e-Navigation project, has been providing a service that meets the goal of establishing a network up to 100km from the coast since J anuary 31, 2021. To provide appropriate communication services for LTE-maritime from the perspective of real users, additional performance analysis of LTE-maritime is required considering service implementation, and efficient use of spectrum resources. This paper presents the requirement of transmission speed according to the e-Navigation service scenario, and available transmission speed based on LTE modulation coding scheme (MCS) according to sea-specific ship distribution scenario and frequency resource allocation, and is cross-analyzed with results of the sea test.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.6
• /
• pp.99-105
• /
• 2018

This paper proposes multiple access method for smart doorlock system using VLC(Visible Light Communication) with color grid modulation method. The proposed method is to connect multiple visible light signals using color grid modulation method in order to recognize and authenticate multiple users accessing doorlock. In order to enable visible light multiple access with existing infrastructure, the symbol energy interval of signal should be maximized. Thus, performance of system in VLC channel is measured by modulating symbols based on the proposed method. We confirm the actual channel test results of the modulated signal to implement doorlock system that recognizes the number of multiple access users.

• Information and Communications Magazine
• /
• v.28 no.6
• /
• pp.31-38
• /
• 2011

본고에서는 홀로그래피 기술을 알아본다. 홀로그래피 기술은 파동 광학에 기초하여 빛의 크기뿐만이 아니라 위상까지 촬영하고 재생할 수 있는 기술이다. 특히 최근 촬상 소자와 광변조소자의 발달로 홀로그래피의 디지털 방식으로의 촬영, 처리, 재생이 가능해 지면서 이를 응용한 다양한 홀로그래피 기술들이 개발되고 있다. 본 고에서는 이 중에서 3차원 촬영 및 3차원 디스플레이에 응용되고 있는 홀로그래피 기술을 중심으로 알아본다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.8
• /
• pp.104-108
• /
• 2006

There are range and azimuth direction resolution of synthetic aperture radar on the aircraft or satellite. Wide bandwidth chirp pulse generation technology is prerequisite for SAR image with fine resolution. There are two kinds of digital chirp pulse generation technology as arbitrary waveform generator(AWG) and direct digital synthesizer(DDS). In this paper, we design and implement a digital chirp pulse generator to generate 300MHz wide bandwidth linear FM chirp pulse for the fine resolution image with direct digital synthesizer. Implemented chirp pulse generator can be useful for the SAR sensors to make 50cm range resolution image.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2018.01a
• /
• pp.151-152
• /
• 2018

본 논문에서는 스마트 디바이스를 통하여 유통되는 디지털 콘텐츠의 합리적 유통과 보안을 위하여 블록체인기술을 적용한 거래방식을 소개하고 블록체인기술 활성화를 위한 스마트 디바이스에서의 개인정보보안 알고리즘을 연구하였다. 특히 권한상승공격을 대비한 알고리즘을 수정하여 연구함으로 스마트 디바이스 상에서의 해킹 및 위변조, 복제에 안정적인 활용이 가능하다. 구현된 알고리즘을 통하여 스마트 디바이스상에서 위변조.해킹의 위협에 대한 주기적인 점검 및 바인더노드를 통한 사전 체크가 가능하다.

• Investigative Magnetic Resonance Imaging
• /
• v.7 no.1
• /
• pp.12-21
• /
• 2003

Purpose : In order to overcome limitations in the existing conventional spectrometer, a new spectrometer with advanced functionalities is designed and implemented. Materials and Methods : We designed a spectrometer using the TMS320C6701 DSP capable of 1 giga floating point operations per second (GFLOPS). The spectrometer can generate continuously varying complicate gradient waveforms by real-time calculation, and select image plane interactively. The designed spectrometer is composed of two parts: one is DSP-based digital control part, and the other is analog part generating gradient and RF waveforms, and performing demodulation of the received RF signal. Each recover board can measure 4 channel FID signals simultaneously for parallel imaging, and provides fast reconstruction using the high speed DSP. Results : The developed spectrometer was installed on a 1.5 Tesla whole body MRI system, and performance was tested by various methods. The accurate phase control required in digital modulation and demodulation was tested, and multi-channel acquisition was examined with phase-array coil imaging. Superior image quality is obtained by the developed spectrometer compared to existing commercial spectrometer especially in the fast spin echo images. Conclusion : Interactive control of the selection planes and real-time generation of gradient waveforms are important functions required for advanced imaging such as spiral scan cardiac imaging. Multi-channel acquisition is also highly demanding for parallel imaging. In this paper a spectrometer having such functionalities is designed and developed using the TMS320C6701 DSP having 1 GFLOPS computational power. Accurate phase control was achieved by the digital modulation and demodulation techniques. Superior image qualities are obtained by the developed spectrometer for various imaging techniques including FSE, GE, and angiography compared to those obtained by the existing commercial spectrometer.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2006.06a
• /
• pp.551-554
• /
• 2006

보안 침해사고시 수집된 디지털 증거를 법적 증거로써 제출하기 위해 신뢰성이 확보되어야한다. 이를 위한 디지털 증거 무결성 보증 기법들중 MDC를 사용한 디지털 증거 무결성 보증 기법은 MDC값을 공격자가 위조 변조 할 수 있다는 단점이 있다. 또 PKI를 이용한 공증 방식은 기존의 증거 수집 시스템을 수정해야 하는 단점과 새로 시스템을 도입하기 위한 비용이 많이 드는 단점이 있다. 따라서 본 논문에서 제안하는 디지털 증거 보호 기법은 Diffie-Hellman(DH) 키 교환 알고리즘을 이용하여 생성된 비밀키와 디지털 증거 수집 대상 시스템(Collecotion System-CS)의 하드웨어 정보($HW_{CS}$)로 디지털 증거(D), 디지털 증거에 대한 해쉬값(H(D))과 타임스탬프(Time)를 암호화해서 디지털 증거에 대한 기밀성, 인증 및 무결성을 보증하는 기법을 제안하였다.

• KIPS Transactions on Computer and Communication Systems
• /
• v.6 no.1
• /
• pp.9-16
• /
• 2017

In modern society, everyone can easily access the Internet and freely express their opinions or ideas on Web bulletin boards or SNS. At the same time, they are often used as a place of slandering and the spreading of false information about celebrities such as entertainers and politicians. Typically people use the screen capture method to submit web posts as evidence in lawsuits. But it is difficult to get these accepted as evidence in court because screen captured images are easily forged and tempered. Therefore, as described above, using "Proxy Browser", we propose a screen capture authentication system for web posts that protects forging and tempering to use as digital evidence in court.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.5
• /
• pp.565-570
• /
• 2015

Spread spectrum communications have increased interest due to their immunity to channel fading and low probability of intercept. One of the limitations of the traditional digital spread spectrum systems is the need for spreading code synchronization. Chaotic communication is the analogue alternative of digital spread spectrum systems beside some extra features like simple transceiver structures. In this paper, This paper was used instead of the digital modulation and demodulation carriers for use in the chaotic signal in a digital communication system among the chaotic modulation schemes, the Differential Chaos Shift Keying(DCSK) is the most efficient one because its demodulator detects the data without the need to chaotic signal phase recovery. Also Implementation of Differential Chaos Shift Keying Communication System Using Matlab/Simulink and the receiver con decode the binary information sent by the transmitter, performance curves of DCSK are given in terms of bit-error probability versus signal to noise ratio with spreading factor as a parameter and we compare it to BPSK modulation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.515-515
• /
• 2013

RF는 사이클로트론에서 빔을 원하는 에너지로 가속하기위해 쓰인다. MC50 사이클로트론에는 두 개의 DEE가 있고 각각 독립된 LLRF모듈과 증폭기를 통해 제어된다. 주요 제어변수는 DEE1,2의 Voltage와 양단간의 Phase인데 이는 RF Generator에서 특정 주파수로 발생된 RF 시그널의 Amplitude와 Phase를 RF Modulator에서 변조하므로 제어되어진다. 지금 현재의 Modulator는 오래되어 DEE Voltage의 컨트롤이 잘 이루어지지 않고 있고 가끔 연결부위에서 문제를 보여 새 Modulator를 제작하게 되었다. 기존의 LLRF는 아날로그 방식인데 아날로그 방식은 외부제어가 어렵고 확장이 쉽지 않아 디지털 제어방식으로 설계하였다. 새 LLRF는 저속처리부와 고속처리부로 두 부분으로 구성하였다. Final amplifier와 cavity의 상태를 체크하는 저속처리부는 PLC로 RF 시그널의 Amplitude와 Phase를 제어하는 고속처리부는 FPGA로 제어할 계획이다.