• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.55-66
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• 2001

In this paper, we analyze the security of OFB encryption mode which is one of the basic modes of operation for the block cipher and the security of 3GPP f8 encryption mode used to provide the data confidentiality over a radio access link of W-CDMA IMT-2000. We provide the lower bound and the upper bound on security of both modes in random function model and random permutation model, respectively, by means of the left-or-right security notion, and prove the security of both modes using a pseudorandom function and a pseudorandom permutation, respectively.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.21-22
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• 2009

유비쿼터스 사회(Ubiquitous Society)로의 진입에 발맞추어 USN(Ubiquitous Sensor Network) 기반의 인간 중심적 편의 시스템에 관한 연구가 활발하게 진행되고 있다. 그 중 대형 시장을 갖는 차량 편의시설에 관한 연구는 지능형 차량 시스템(Intelligent Car System)을 중심으로 활발히 이루어지고 있다. 지능형 차량 시스템의 주요 연구는 자동 항법 장치, 사고 예방 장치, 자가 진단 시스템 등 탑승자의 편의성과 안전성을 중심으로 진행되었다. 그러나 탑승자의 사고 발생 시 응급 상황 처리를 위한 지원 시스템은 미미하다. 탑승자 부상으로 사고 신고를 하지 못할 경우, 사고지점 확인, 탑승자의 위급(현재) 상황, 부상 정보와 같은 정보를 얻을 수 없어 응급 상황 대처에 신속하지 못할 수 있다. 따라서 본 논문은 다양한 센서를 이용하여 차량의 정보를 수집하고, 사고 판단 시 차량 위치 정보, 탑승자 상황 정보를 응급 기관에 전달할 수 있는 차량용 스마트 안전장치를 설계 및 구현하였다. 테스트를 위해 Intel PXA255 MCU와 AM-3AXIS(3축 가속 센서), MDSM-1000A(지자기 센서), RX-M800S CDMA, GPS520, Alpha cam, Flex Sensor로 시스템을 제작하였으며 모의 도로 모형에서 테스트 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.7-10
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• 2011

본 논문에서는 스마트폰을 이용하여 차량을 원격시동 제어 및 관리하는 원격시동 관리 시스템을 제안한다. 이 시스템은 고가의 차량을 관리 및 제어하는 시스템인 만큼 작동의 신뢰성을 중요시 한다. 그래서 기존의 소형 리모콘 방식의 차량 원격시동 제어관리 시스템을 활용하여 시스템 작동의 신뢰도를 높였으며, 기존의 소형 리모콘 제어 환경에서 스마트폰으로 옮겨옴으로써, 기존의 입력 및 제어의 불편함을 해결하였다. 그리고 기존 존재하는 블루투스와 CDMA를 사용하는 차량 원격시동 제어 관리 시스템의 거리 및 속도, 비용 등의 문제점도 개선하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.75-85
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• 2009

This work proposes a 13b 100MS/s 0.13um CMOS ADC for 3G communication systems such as two-carrier W-CDMA applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs a four-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. Area-efficient high-speed high-resolution gate-bootstrapping circuits are implemented at the sampling switches of the input SHA to maintain signal linearity over the Nyquist rate even at a 1.0V supply operation. The cascode compensation technique on a low-impedance path implemented in the two-stage amplifiers of the SHA and MDAC simultaneously achieves the required operation speed and phase margin with more reduced power consumption than the Miller compensation technique. Low-glitch dynamic latches in sub-ranging flash ADCs reduce kickback-noise referred to the differential input stage of the comparator by isolating the input stage from output nodes to improve system accuracy. The proposed low-noise current and voltage references based on triple negative T.C. circuits are employed on chip with optional off-chip reference voltages. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates the measured DNL and INL within 0.70LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 64.5dB and a maximum SFDR of 78.0dB at 100MS/s, respectively. The ABC with an active die area of $1.22mm^2$ consumes 42.0mW at 100MS/s and a 1.2V supply, corresponding to a FOM of 0.31pJ/conv-step.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.839-846
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• 2007

In this paper, the first attempt to design a novel structure of dual-band feedforward linear power amplifier(FFW LPA) was presented. Up to now, primary technical difficulty has been the extension of the conventional signal canceller to the dual-band operation. Therefore, we propose the design technique of the dual-band equal group delayed carrier canceller, the dual-band equal group delayed intermodulation distortion(IMD) canceller and the dual-band FFW LPA. The operation frequency bands of the implemented dual-band FFW LPA are digital cellular($f_0=880$ MHz) and IMT-2000($f_0=2.14$ GHz) band, which are separated about 1.26 GHz. With the high power amplifier of 120 W PEP for commercial base-station application, IMD cancellation loop shows 20.45 dB and 25.04 dB loop suppression at each band of operation for 100 MHz. From the adjacent channel leakage ratio(ACLR) measurement with CDMA IS-95A 4FA and WCDMA 4FA signal, we obtained 16.52 dB improvement at the average output power of 41.5 dBm for digital cellular band, and 18.59 dB improvement at the average output power of 40 dBm for IMT-2000 band simultaneously.

• The Journal of the Korea Contents Association
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• v.7 no.4
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• pp.1-9
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• 2007

Cellular operators develop high speed mobile internet and multi-function cellular phones to activate new business model based on mobile internet services. Domestic cellular operators evolve their mobile networks from cdma2000-1x and EvDo to HSDPA to activate high speed mobile internet services. They also develop mobile internet platforms such as WIPI, BREW, and J2ME on multi-function cellular phones having multimedia solutions such as camera, MP3, MPEG, 3D game engine, DMB, PAN such as bluetooth, IrDA, W-LAN, and location information using GPS. But, content providers have problems of redevelopment of the same mobile internet application on different mobile internet platforms provided by cellular operators. In this paper, we develop conversion solutions for interoperability of mobile internet applications on WIPI and BREW using an one-pass compiler. We confirm the performance the proposed conversion solutions for the API conversion rate, the converted file size, and the full conversion time using the popular mobile games which are the killer applications on WiPI and BREW.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1015-1022
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• 2007

In this paper, we proposed a wideband design of planar inverted-F antenna(PIFA) using two-layer, patches and modified ground structure. The antenna consists of two layer patches with common feed and modified ground plane to control resonance frequency and antenna input impedance. The measured bandwidth is 1,492 MHz(BW: 67.7 %, 1,457${\sim}2,949$ MHz) for VSWR<2, and 1,170 MHz(BW: 21 %, 4,970${\sim}$6,140 MHz) for VSWR<2.5. It covers service bands of DCS1800, DCS1900, UMTS(WCDMA), WiBro, WLAN(IEEE 802.11b), satellite DMB. WLAN(IEEE 802.11a) in Korea and radiation patterns shows constant figure with frequency change.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.271-273
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• 2003

최근에 전력선통신(PLC: power line communication)에 관한 연구 및 개발이 활성화되고 있는 가운데, 정부에서는 전력선통신을 위한 전송채널의 주파수허용범위를 기존의 협대역인 450kHz에서 광대역인 30MHz로 확대할 계획이다. 현재, PLC 시스템에서는 대용량정보를 고속으로 전송하기 위한 고속 PLC기술의 개발이 활발히 진행되어지고 있으며, 이러한 통신시스템 기술의 구현을 위해서는 새롭게 확대될 30MHz대역에서의 전력선채널의 분석이 무엇보다도 중요한 해결 과제라고 할 수가 있을 것이다. 전력선은 각종 전기기기와 가전제품 및 사무기기로부터 발생되는 잡음들이 직접 유입되며, 또한 부하가 전력선에 연결되는 시간과 공간에 따라 전송 특성이 수시로 가변하는 특성을 가진다. 이와 같은 열악한 전력선통신채널 환경을 극복하고 통신의 에러극복능력을 향상시키기 위해서는 기존의 협대역 채널모델을 그대로 적용하기에는 부적합한 면이 많으므로, 새롭게 허용될 광대역 주파수를 갖는 전력선 채널에 대한 모델링기법이 요구된다. 따라서, 새롭게 인가될 광대역 채널을 위한 효율적인 전력선통신시스템을 개발하기 위해서는 전력선채널의 리모델링에 근거한 다양하고 실험적인 고찰이 수반되어야 하리라고 판단된다. 그러므로, 본 논문에서는 Mixture 잡음 모델링기법을 이용하여, 부하변동 및 가변적인 잡음 특성을 가진 전력선채널모델을 새롭게 분석하였다. 또한, 새롭게 분석한 전력선채널모델에 관한 수식을 직교 코드에 의한 다중접속 통신 기술인 CDMA 방식에 적용하여 비트 에러율을 유도해 봄으로써 그 유효성을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3B
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• pp.226-236
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• 2002

In this paper, we present the channel assignment and management methods for an efficient use of traffic channel resource for supporting 12.2 Kbps, 64 Kbps, and 384 Kbps traffic with the different quality of service (QoS) in the radio network controller (RNC) in asynchronous IMT-2000 system. We first describe two types of traffic channel block assignments for utilizing the traffic channel efficiently; the partially dedicated and partially shared channel (PDPSC) assignment and the completely shared channel (CSC) assignment. The former is that some traffic channel block is completely assigned to each traffic type and the other blocks are shared with some traffic type. The latter is that all traffic channel blocks are completely shared with all traffic types. Further, for efficiently assigning, releasing, and managing the channel resource, we present the traffic channel management method which consists of the block and task management step. Through numerical examples, we evaluate the blocking probability and the mean number of required search for fading the available channel when applying our proposed channel block assignment and resource management methods.

• Journal of Korean Society of Rural Planning
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• v.21 no.3
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• pp.171-179
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• 2015

The objectives of this research have been focussed on 1) developing prediction techniques for the flash flood and landslide based on rainfall prediction data in agricultural area and 2) developing an integrated forecasting system for the abrupt disasters using USN based real-time disaster sensing techniques. This study contains following steps to achieve the objective; 1) selecting rainfall prediction data, 2) constructing prediction techniques for flash flood and landslide, 3) developing USN and communication network protocol for detecting the abrupt disaster suitable for rural area, & 4) developing mobile application and SMS based early warning service system for local resident and tourist. Local prediction model (LDAPS, UM1.5km) supported by Korean meteorological administration was used for the rainfall prediction by considering spatial and temporal resolution. NRCS TR-20 and infinite slope stability analysis model were used to predict flash flood and landslide. There are limitations in terms of communication distance and cost using Zigbee and CDMA which have been used for existing disaster sensors. Rural suitable sensor-network module for water level and tilting gauge and gateway based on proprietary RF network were developed by consideration of low-cost, low-power, and long-distance for communication suitable for rural condition. SMS & mobile application forecasting & alarming system for local resident and tourist was set up for minimizing damage on the critical regions for abrupt disaster. The developed H/W & S/W for integrated abrupt disaster forecasting & alarming system was verified by field application.