• Journal of Advanced Navigation Technology
• /
• v.4 no.1
• /
• pp.67-77
• /
• 2000

This paper proposes a reduction scheme for codebook search time in the adaptive codebook using wavelet transformed coefficients. In a CELP coder, pitch estimation with a combined open loop and closed loop search in adaptive codebook needs a lengthy search. More precisely, the pitch search using autocorrelation function over all possible ranges has been shown inefficient compared to the consuming time. In this paper, we propose a new adaptive codebook search algorithm which ensures the same position for the pitch with maximum wavelet coefficient over various scaling factors in Dyadic wavelet transform. A new adaptive codebook search algorithm reduces 25% conventional search time with almost the same quality of speech.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.573-575
• /
• 2015

Positioning system using satellite GPS is used at positioning, navigation, acquisition time information and other various field and taking an important part precision guided weapon such as missile. But commercial code(C/A code) do not have ECCM. Therefore commercial code is vulnerable to various jamming techniques and noise jamming from near station can attack even the encrypted military code(P code) GPS. In this paper, GPS jamming techniques, North Korean GPS jamming cases and anti-jamming GP S technologies are surveyed and described.

• Journal of the Korea Computer Industry Society
• /
• v.3 no.8
• /
• pp.963-980
• /
• 2002

Software reengineering is making various research for solutions against problem of maintain existing systems. Reengineering has a meaning of development of software on exizting systems through the reverse engineering auf forward engineering. Most of the important concepts used in reengineering is composition that is restructuring of the existing objects. Is there a compiler that can compile a program written in a traditional procedural language (like C or Pascal) and generate a Java bytecode, rather than an executable code that runs oかy on the machine it was compiled (such as an a.out file on a Unix machine)\ulcorner This type of compiler may be very handy for today's computing environment of heterogeneous networks. In this paper we present a software system that does this job at the binary-to-binary level. It takes the compiled binary code of a procedural language and translates it into Java bytecode. To do this, we first translate into an assembler code called Jasmin [7] that is a human-readable representation of Java bytecode. Then the Jasmin assembler converts it into real Java bytecode. The system is not a compiler because it does not start at the source level. We believe this kind of translator is even more useful than a compiler because most of the executable code that is available for sharing does not come with source programs. Of course, it works only if the format of the executable binary code is known. This translation process consists of three major stages: (1) analysis stage that identifies the language constructs in the given binary code, (2) initialization stage where variables and objects are located, classified, and initialized, and (3) mapping stage that maps the given binary code into a Jasmin assembler code that is then converted to Java bytecode.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.6
• /
• pp.20-30
• /
• 2003

In a conventional method based on quadrature 2D Gator wavelets to extract iris features, the iris recognition is performed by a 256-byte iris code, which is computed by applying the Gabor wavelets to a given area of the iris. However, there is a code redundancy because the iris code is generated by basis functions without considering the characteristics of the iris texture. Therefore, the size of the iris code is increased unnecessarily. In this paper, we propose a new feature extraction algorithm based on the ICA (Independent Component Analysis) for a compact iris code. We implemented the ICA to generate optimal basis functions which could represent iris signals efficiently. In practice the coefficients of the ICA expansions are used as feature vectors. Then iris feature vectors are encoded into the iris code for storing and comparing an individual's iris patterns. Additionally, we introduce two methods to enhance the recognition performance of the ICA. The first is to reorganize the ICA bases and the second is to use a different ICA bases set. Experimental results show that our proposed method has a similar EER (Equal Error Rate) as a conventional method based on the Gator wavelets, and the iris code size of our proposed methods is four times smaller than that of the Gabor wavelets.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.6
• /
• pp.275-280
• /
• 2010

Recently, This paper suggests that LED-ID technique applying positioning method for LED light. also, Authors in this paper has launched this investigation earnestly. However, there are various interferences such as MPI(Multi Path Interference) by reflected waves of the surface and interfere factors by their correlation properties of the ID in LED-ID wireless channel. Therefore, in this paper, we propose a novel OOK(On-Off Keying)-CDMA(Code Division Multiple Access) system using unipolar ZCD(Zero Correlation Duration) spreading code and verify the availability of the proposed system via the evaluation performance simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.11
• /
• pp.1044-1050
• /
• 2013

This paper analyzes what is mitigated as spoofing attack using the U-Blox Receiver and GPS RF signal generator developed at ETRI. Generally the spoofing attack made the target receiver to be wrong navigation solution by providing false measurement of code and carrier. So we analyzed the impact of spoofing attack through the signal strength and navigation solution. In oder to test of effect of anti-spoofing signal, we consider the signal with antiphase code to spoofing signal and generated GPS normal signal and spoofing signal and anti-spoofing signal using GPS RF signal generator. This paper analyzed that the GPS receiver was responded to the spoofing attack according to code phase difference between spoofing and anti-spoofing signal. We confirmed that the spoofing signal was disappeared by anti-spoofing signal if code phase is an exact match.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.8
• /
• pp.1464-1474
• /
• 1994

GPS(Global Positioning System)is a satellite-based navigation system that we can survey where we are, anywhere and anytime. In this paper, delay-lock loop of the receiver which detects the navigation data is theoretically analyzed, and designed using the digital logic circuit. Also logic operations for the synchronization are analyzed. The designed system consists of the correlator which correlates the received C/A code and the generated C/A code in the receiver, the C/A code generator which generates C/A code of selected satellite, and the direct digital clock syntheizer which generates the clock of the C/A code generator to control the C/A code phase and clock rate. From the analyses results of the proposed digital delay-lock loop system, the system has the detection propertied over 90% when its input signal power is above-113.98dB. The influence of input signal variation of digital delay loop, which is the input of A/D converter, is investigated and the performance is analyzed with the variation of threshold level via the computer simulation. The logic simulation results show that the designed system detects precisely the GPS navigation data.

• The KIPS Transactions:PartC
• /
• v.13C no.4 s.107
• /
• pp.397-404
• /
• 2006

Successful software attacks require both injecting malicious code into a program's address space and altering the program's flow control to the injected code. Code section can not be changed at program's runtime, so malicious code must be injected into data section. Detoured flow control into data section is a signal of software attack. We propose a new software attack detection method which verify the target address of CALL, JMP, RET instructions, which alter program's flow control, and detect a software attack when the address is not in code section. Proposed method can detect all change of flow control related data, not only program's return address but also function pointer, buffer of longjmp() function and old base pointer, so it can detect the more attacks.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.3
• /
• pp.134-142
• /
• 2002

Quadtree, which is a hierarchical data structure, is a very important data structure to represent binary images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related with quadtrees. The window operation is one of important geometry operations in image processing, which extracts a sub-image indicated by a window in the image. In this paper, we present an algorithm to perform the window operation of binary images represented by quadtrees, using three-dimensional $n{\times}n{\times}n$ processors on RMESH(Reconfigurable MESH). This algorithm has constant-time complexity by using efficient basic operations to route the locational codes of quardtree on the hierarchical structure of $n{\times}n{\times}n$ RMESH.

• The KIPS Transactions:PartA
• /
• v.11A no.3
• /
• pp.173-180
• /
• 2004

Quadtree, which 11 a hierarchical data structure, is a very important data structure to represent images. The linear quadtree representation as a way to store a quadtree is efficient to save space compared with other representations. Therefore, it has been widely studied to develop efficient algorithms to execute operations related to quadtrees. The region expansion is an operation to expand images by a given distance and the scaling If an operation to scale images by a given scale factor. In this paper, we present algorithms to perform the region expansion and scaling of images represented by quadtrees, using three-dimensional n${\times}$n${\times}$n processors on RMESH(Reconfigurable MESH). These algorithms have constant time complexities by using efficient basic operations to route the locational codes of quadtree on the hierarchical structure of n${\times}$n${\times}$n RMESH.