• 전기전자학회논문지
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• 제12권2호
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• pp.95-101
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• 2008

본 논문에서는 2.45 GHz RFID eSeal(electrical seal)의 표준 ISO/IEC 18185-5와 24730-2의 물리적 계층을 지원하는 기저대역 모뎀의 동기 탐색 구조 설계에 대해 연구하였다. DSSS 모뎀 설계 시, 수신기에서 가장 중요한 기능인 코드 획득 및 추적 구조를 설계하였고 고려되어야 할 각 파라미터들에 대해서 살펴보았다. 제안된 모뎀의 데이터 전송률은 59.7 Kbps이며, PN 칩 전송률은 30.521875 Mcps로써 프로세싱 이득(Processing Gain)이 27 dB이다. 그러므로 상기 표준의 변조 특성은 현재 비슷한 모뎀 구조로 사용되고 있는 IEEE 802.11b 규격(프로세싱 이득이 10dB)에 비해 잡음에 대한 내성이 17dB 우수하다. 그러므로 상기 표준에 적합 한 모뎀의 동기 탐색 구조를 제시 하였다.

• Spatial Information Research
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• 제19권3호
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• pp.53-62
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• 2011

최근 실내 공간 내에서의 위치 정보를 이용한 공간정보 서비스가 실외공간에서 제공되는 서 비스만큼 공간정보시스템의 중요한 응용분야로 자리 잡고 있다. 실외 공간과 달리, 실내 공간의 위치 정보는 좌표기반이 아닌, 방 번호와 같은 기호를 기반으로 표현된다. 따라서 실내공간에서 이동객체의 위치를 추적하기 위해서는 이동객체의 현재 위치를 이용하여 좌표정보를 예측하는 것이 아니라, 기호적 추론이 필요하다. 이에 본 논문에서는 RFID센서를 이용하여 이동객체의 위치를 항상 명시적으로 결정할 수 있는 추적가능 실내 기호공간을 위한 프레임웍을 제안한다. 우선, 실내기호공간과 실내기호공간에서의 위치추적에 대한 개념을 소개하고, 추적 가능한 실내 기호공간을 위한 접근성 그래프를 정의한다. 둘째로, RFID 리더기의 배치방법, 추적 가능한 실내기호공간을 위한 접근성 그래프 생성방법과 이를 이용한 위치 추적방법을 제시한다. 마지막으로, 제시한 방법의 유효성을 보이기 위하여 실험결과를 보인다.

• 정보보호학회논문지
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• 제29권1호
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• pp.105-115
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• 2019

최근 지능화된 안드로이드 악성코드는 정적 분석만으로는 악성행위에 대한 탐지가 어려워지고 있다. SO파일, 동적로딩을 이용한 코드 호출 및 문자열 난독화를 적용한 악성코드의 경우 분석을 위해 다양한 툴을 이용하여도 원본 코드에 대한 정보 추출이 어렵다. 이 문제를 해결하기 위해서 다양한 동적 분석기법이 있지만, 동적 분석은 루팅 환경이나 에뮬레이터 환경을 요구한다. 그러나 동적 분석의 경우 악성코드들이 루팅 및 에뮬레이터 탐지를 실시하여 분석 환경을 탐지 하고 있다. 본 논문은 이를 해결하고자 다양한 루팅 탐지 기법을 조사하여 실단말에서 루팅탐지 우회 환경을 구축하였다. 또한, Xposed를 이용하여 안드로이드 악성코드 분석을 위한 SDK 코드 후킹 모듈을 설계하였고, 코드 흐름을 위한 인텐트 추적, 동적 로딩 파일에 대한 정보, 다양한 API 정보 추출을 구현하였다. 이를 통해 악성코드의 난독화 된 정보 및 다양한 악성 행위 정보를 분석하고자 한다.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.85-92
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• 2024

This study develops a Global Positioning System (GPS) Code Multipath Grid Map (CMGM) of each individual domestic reference station from the extracted code multipath of measurement data. Multipath corresponds to signal reflection/refraction caused by obstacles around the receiver antenna, and it is a major source of error that cannot be eliminated by differencing. From the receiver-independent exchange format (RINEX) data for two days, the associated code multipath of a satellite tracking arc is extracted. These code multipath data go through bias correction and interpolation to yield the CMGM with respect to the azimuth and elevation angles. The effect of the CMGM on multipath mitigation is then quantitatively analyzed to improve the Root Mean Square (RMS) of averaged pseudo multipath. Furthermore, the single point positioning (SPP) accuracy is analyzed in terms of the RMS of the horizontal and vertical errors. During two weeks in February 2023, the RMSs of the averaged pseudo multipath for five reference stations decreased by about 40% on average after CMGM application. Also, the SPP accuracies increased by about 7% for horizontal errors and about 10% for vertical errors on average after CMGM application. The overall quantitative analysis indicates that the proposed approach will reduce the convergence time of Differential Global Navigation Satellite System (DGNSS), Real-Time Kinematic (RTK), and Precise Point Positioning (PPP)-RTK correction information in real-time to use measurement data whose code multipath is corrected and mitigated by the CMGM.

• Journal of Ecology and Environment
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• 제34권4호
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• pp.365-370
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• 2011

The water deer (Hydropotes inermis) is one of the most primitive extant deer of the family Cervidae. Unlike Chinese water deer, Korean water deer have rarely been studied, even though they have relatively well remained in Korea. In particular, the home range of the Korean water deer has not yet been studied. Here we estimated the home range of the Korean water deer using two different methods (GPS and radio tracking) and analyzed the home range according to sex, time, and season. The mean home range size of four individuals was 2.77 $km^2$ and 0.34 $km^2$ under the 95% minimum convex polygon (MCP) and the 50% kernel (K) method, respectively. There seemed to be a difference in home range size between males (3.30 $km^2$) and females (2.25 $km^2$) under the 95% MCP method. We also found a difference in home range size between day (1.90 $km^2$) and night (2.43 $km^2$) by 95% MCP method. In addition, a home range size difference was observed between summer (4.65 $km^2$) and spring (0.48 $km^2$) or fall (0.85 $km^2$) using the 95% MCP method. Water deer seemed to have a larger home range in night than in day, and males also have a larger home range. We presumed that the GPS tracking method of the code division multiple access system could be a very useful tool for understanding the ecology of the water deer using the radio tracking method. Using these tracking methods and through future research, we can better understand the habitat use pattern of these water deer.

• Nuclear Engineering and Technology
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• 제44권4호
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• pp.369-378
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• 2012

A load-following operation in APR+ nuclear plants is necessary to reduce the need to adjust the boric acid concentration and to efficiently control the control rods for flexible operation. In particular, a disproportion in the axial flux distribution, which is normally caused by a load-following operation in a reactor core, causes xenon oscillation because the absorption cross-section of xenon is extremely large and its effects in a reactor are delayed by the iodine precursor. A model predictive control (MPC) method was used to design an automatic load-following controller for the integrated thermal power level and axial shape index (ASI) control for APR+ nuclear plants. Some tracking controllers employ the current tracking command only. On the other hand, the MPC can achieve better tracking performance because it considers future commands in addition to the current tracking command. The basic concept of the MPC is to solve an optimization problem for generating finite future control inputs at the current time and to implement as the current control input only the first control input among the solutions of the finite time steps. At the next time step, the procedure to solve the optimization problem is then repeated. The support vector regression (SVR) model that is used widely for function approximation problems is used to predict the future outputs based on previous inputs and outputs. In addition, a genetic algorithm is employed to minimize the objective function of a MPC control algorithm with multiple constraints. The power level and ASI are controlled by regulating the control banks and part-strength control banks together with an automatic adjustment of the boric acid concentration. The 3-dimensional MASTER code, which models APR+ nuclear plants, is interfaced to the proposed controller to confirm the performance of the controlling reactor power level and ASI. Numerical simulations showed that the proposed controller exhibits very fast tracking responses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
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• pp.65-66
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• 2008

A vector DLL represents signal tracking scheme utilizing navigation results, and it has been known that it has better performance than a conventional scalar DLL. This paper discusses the structure and conceptual benefits of the vector DLL, and describes implementation of the vector DLL in a software GPS receive. Also, the benefits of the vector DLL are confirmed by an experiment. Through the experiment, the code tracking accuracy between the vector DLL and a scalar DLL implementation is compared in static environments, and the navigation accuracy is analyzed using GPS signals received from a commercial GPS simulator.

• Journal of information and communication convergence engineering
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• 제6권2호
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• pp.213-217
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• 2008

This paper proposes a novel method for the recognition of passports based on the CDM(Conditional Dilation Morphology) masking and the ART2-based RBF neural networks. For the extraction of individual codes for recognizing, this paper targets code sequence blocks including individual codes by applying Sobel masking, horizontal smearing and a contour tracking algorithm on the passport image. Individual codes are recovered and extracted from the binarized areas by applying CDM masking and vertical smearing. This paper also proposes an ART2-based hybrid network that adapts the ART2 network for the middle layer. This network is applied to the recognition of individual codes. The experiment results showed that the proposed method has superior in performance in the recognition of passport.

• 한국통신학회논문지
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• 제19권8호
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• pp.1421-1432
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• 1994

본 논문에서는 비코히어런트 방식의 시간분할 조만 동기추적루프에 속하는 타우진동루프의 최적 설계를 위한 대역통과필터의 대역폭에 대하여 고찰하였다. NRZ 데이터의 경우 이상적 대역통과 필터를 채용한 비코히어런트 TDL의 제곱손실 및 최소의 동기추적지터를 구하였다. 또한 이를 이용하여 최적의 3dB 대역통과필터 대역폭을 주어진 데이터율과 데이터 신호대잡음비에 대해 계산하였다. 결과로서 이상적 대역통과 필터의 경우 최적의 대역폭은 주어진 신호대잡음비에 따라 데이터율의 약 1-2배의 범위 내에 존재함을 알 수 있었다.

• ETRI Journal
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• 제31권2호
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• pp.193-200
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• 2009

In this paper, we study the performance of subspace-based multiuser detection techniques for multicarrier code-division multiple access (MC-CDMA) systems. We propose an improvement in the PASTd algorithm by cascading it with the classical Gram-Schmidt procedure to orthonormalize the eigenvectors after their sequential extraction. The tracking of signal subspace using this algorithm, which we call OPASTd, has a faster convergence as the eigenvectors are orthonormalized at each discrete time sample. This improved PASTd algorithm is then used to implement the subspace blind adaptive multiuser detection for MC-CDMA. We also show that, for multiuser detection, the complexity of the proposed scheme is lower than that of many other orthogonalization schemes found in the literature. Extensive simulation results are presented and discussed to demonstrate the performance of the proposed scheme.