• Journal of Korea Society of Industrial Information Systems
• /
• v.5 no.4
• /
• pp.55-59
• /
• 2000

In start up process control, it may be necessary to use appropriate scheme in monitoring processes with individual observations. In these situation individual observations are periodically drawn from the process. In this paper, using modifying statistics with individual measurement, we suggest a simple technique which operating control chart for monitoring the process. And compare individual observation control procedures that are X, an exponentially weighted moving(EWM), adjusted EWM and adjusted MCEWM charts. And estimate the ARL to detection of shifts in the process mean and standard deviation using simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.2
• /
• pp.199-207
• /
• 2001

In this paper, the technique of prediction and analysis on the characteristics of propagation in indoor environment is presented. This technique needs no reception sphere commonly used in 3D-ray tracing scheme, and thereby it lends us easy code realization. The validity of developed code is verified by comparing with the values of image methods and measurement. The developed technique applied to the structure of rectangular corridor with the iron door and we calculated the path loss for the variation of the iron door angle. The path loss decreased about 15 dB at the distance of30 m from the iron door and the delay spread increased approximately by four times. Based on the computation, we confirmed that indoor propagation in PCS is heavily affected by the iron door in corridor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.553-564
• /
• 2000

In this thesis, mobile communication channel with multi-path fading which is major factor of performance degradation of DS-CDMA system has been considered. An MRC diversity and error correcting coding technique have been used to improve performance of MFSK-MDPSK/DS-CDMA system. The MFSK-MDPSK/DS-CDMA system performance has been obtained quantitatively by the numerical analysis. the modulations under consideration are noncoherent M-ary frequency shift keying(MFSK) and an MFSK based joint frequency phase modulation utilizing MFSK/DS-CDMA and MDPSK-DS-CDMA systems the MFSK-MDPSK/DS-CDMA system obtain a better performance . Also, the error performance of MFSK-MDPSK/DS-CDMA system in Nakagami fading environments is improved by increasing the number of diversity branch and coding gain.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2B
• /
• pp.99-106
• /
• 2009

The tracking information of objects or persons plays the important role for being advanced of the technology in the logistics management or processing. In this paper, we propose the TDOA-based localization method for port logistics environment for obtaining accurate location of a tag which is attached to some objects or persons. The proposed method consists of these modules for precision : An adaptive selection module of base reader, 2.5D locating method and position-restriction method using a map. This paper includes the performance evaluation of those methods. We could see the improved performance in the simulation. And we also implemented the system and achieved the accuracy of DRMS and CEP within 4 meters.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.1
• /
• pp.14-21
• /
• 2011

A 10b 500MS/s $0.13{\mu}m$ CMOS ADC is proposed for 4G wireless communication systems such as a LTE-Advanced and SDR The ADC employs a calibration-free single-channel folding architecture for low power consumption and high speed conversion rate. In order to overcome the disadvantage of high folding rate, at the fine 7b ADC, a cascaded folding-interpolating technique is proposed. Further, a folding amplifier with the folded cascode output stage is also discussed in the block of folding bus, to improve the bandwidth limitation and voltage gain by parasitic capacitances. The chip has been fabricated with $0.13{\mu}m$ 1P6M CMOS technology, the effective chip area is $1.5mm^2$. The measured results of INL and DNL are within 2.95LSB and l.24LSB at 10b resolution, respectively. The SNDR is 54.8dB and SFDR is 63.4dBc when the input frequency is 9.27MHz at sampling frequency of 500MHz. The ADC consumes 150mW($300{\mu}W/MS/s$) including peripheral circuits at 500MS/s and 1.2V(1.5V) power supply.

• Convergence Security Journal
• /
• v.19 no.5
• /
• pp.107-118
• /
• 2019

Based on the Internet of Things technology, one of the core technologies of the fourth industrial revolution, our Ministry of Defense is also pushing to establish M-IoT in defense area to improve management efficiency, innovate military culture and strengthen military power. However, devices connected to the Military Internet of Things can be easily exposed to various of cyber threats as most of them are developed and with a focus on improving sensing and communication skills that collect and transmit data. And it is not easy to uniquely identify the numerous heterogeneous devices, and to establish a secure communication channel between devices or between devices and management servers. In this paper, based on PUF technology, we propose a novel key management scheme that can uniquely identify the various devices, and generate the secret keys needed for the establishment of a secure communication channel using non-replicable information generated by the PUF. We also analyze the efficiency of our proposed scheme through comparison with existing key management scheme and verify the logic and security using BAN Logic.

• Journal of Aerospace System Engineering
• /
• v.10 no.4
• /
• pp.17-25
• /
• 2016

In this study, an optical system for a lens-shifting method that compensates for microvibration of a high-agility small satellite has been designed. The lens-shifting method is an image-stabilization technique that can be applied to compensate for the optical path disturbed by microvibration. The target optical system is designed by using Code-V, a commercial optical-design code. The specifications for real satellite cameras have established the requirements for optical design. The Ray aberration curve, spot diagram, and MTF curve were carried out to verify if the designed optical system meets the requirements or not. The designed Schmidt-Cassegrain optical system with field flattener and a vibration-reduction lens has been verified to meet the optical requirements, 33% of MTF at Nyquist frequency, GSD of 2.87 m, and vibration coefficient of 0.95~1.0.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.3
• /
• pp.101-113
• /
• 2015

The purpose of this study is increasing ventilation network usability for urban green space planning by enhancing its practicality and detail. A ventilation network feature extraction technique using roughness length($z_0$) was proposed. Continuously surfaced DZoMs generated from $z_0$(cadastral unit) using three interpolations(IDW, Spline, and Kriging) were compared to choose the most suitable interpolation method. Ventilation network features were extracted using the most suitable interpolation technique and studied with land cover and land surface temperature by spatial overlay comparison. Results show Kriging is most suitable for DZoM and feature extraction in comparison with IDW and Spline. Kriging based features are well fit to the land surface temperature(Landsat-7 ETM+) on summer and winter nights. Noteworthy is that the produced ventilation network appears to mitigate urban heat loads at night. The practical use of proposed ventilation network features are highly expected for urban green space planning, though strict validation and enhancement should follow. (1) $z_0$ enhancement, (2) additional ventilation network interpretation and editing, (3) linking disconnected ventilation network features, and (4) associated dataset enhancement with data integrity should technically preceded to enhance the applicability of a ventilation network for green space planning. The study domain will be expanded to the Seoul metropolitan area to apply the proposed ventilation network to green space planning practice.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.6A
• /
• pp.929-938
• /
• 2001

CDMA 2000 1X EV.(HDR, 1XTREME, LAS-CDMA)에서는 고속데이터 전송을 위한 변조방식으로 M-ary QAM을 제안하고 있다. 그러나, M-ary QAM을 사용한 DS-CDMA 시스템은 고속 데이터 전송이 가능한 반면에 M-ary 수가 증가할수록 잡음(AWGN)과 타 사용자에 의한 다중접속간섭(MAI)의 영향이 커져 비트에러율(BER)이 증가하고 채널용량이 급격히 줄어드는 문제점이 있다. 따라서, DS-CDMA/M-ary QAM 시스템에서 많은 사용자에게 고속의 데이터 서비스를 제공하기 위해서는 잡음을 줄이거나 MAI를 경감시킬 수 있는 성능 개선 기법이 요구된다. 본 논문에서는 성능 개선 기법으로서 다단병렬간섭제거기(MPIC : Multistage Parallel Interference Canceller)와 부분 다단병렬간섭제거기(partial MPIC)를 채용한 비동기 DS-CDMA/M-ary QAM 시스템의 성능 개선을 이론적으로 분석하고 이를 검증하기 위한 컴퓨터 시뮬레이션을 수행하였다. 결과에서, MPIC와 partial MPIC를 채용함으로써 4 QAM, 16 QAM 및 64 QAM을 사용한 DS-CDMA 시스템의 BER과 채널용량이 크게 개선됨을 확인하였다. MPIC를 채용한 경우는 AWGN 채널의 BER에 근접하였다. 또한, MPIC는 partial MPIC보다 BER 성능이 우수하였으며 더 많은 채널용량 개선을 달성하였다. 그러나, MPIC는 partial MPIC 보다 계산량이 훨씬 많고 복잡한 구조를 갖기 때문에 실제 시스템 구현에 있어서 성능과 복잡도 사이에 타협(tradeoff)이 필요하다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.05a
• /
• pp.559-562
• /
• 2002

본 논문에서는 최근 제한적으로 사용이 승인된 UWB(초광대역： Ultra-Wideband) 통신을 AWGN 하에서 다중 접속을 고려하지 않은 단일 사용사일 경우로 가정시, M진 값이 변화함에 따른 에러율과 성능 개선 기법으로 BCH를 채용시의 에러율을 비교 분석하였다. 기존에 연구되어 오던 변조로 PAM(Pulse Amplitude Modulation)과 PPM(Pulse Position Modulation)방식을 비교하였으며 에러율 $10^{-6}$을 기준으로 M=2, 4일 경우 PAM이 PPM보다 약 E$_{b}$/N$_{o}$ =3~4［dB］, M=8 이상의 경우 PPM이 약 E$_{b}$/N$_{o}$ =9［dB］, M=16일 경우 약 E$_{b}$/N$_{o}$ =15［dB］정도 성능이 우수하였다. AWGN 채널 하에서 에러 정정 부호인 BCH(15,7)를 도입하였을 경우 에러율 $10^{-6}$을 기준으로 PAM방식은 약 E$_{b}$/N$_{o}$ 가 약 1［dB］, PPM 방식은 M=2, 4일 경우 약 E$_{b}$/N$_{o}$ =1~1.5［dB］정도 개선되었다.