• Journal of KIISE:Databases
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• v.31 no.3
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• pp.331-339
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• 2004

XML has got to be a new standard for data representation and exchanging by its many good points, and the core part of many new researches and emerging technologies. However, the self-describing characteristic, which is one of XML's good points, caused the spreading of XML documents with different structures, and so the need of the research for the effective XML-document search has been proposed. This paper is for the analysis of the problem in BitCube, which is a bitmap indexing that shows high performance grounded on its fast retrieval. In addition, to resolve the problem of BitCube, we did design and implement xPlaneb(XML Plane Web) which it a new 3-dimensional bitmap indexing made of linked lists. We propose an effective information retrieval technique by replacing BitCube operations with new ones and reconstructing 3-dimensional array index of BitCube with effective nodes. Performance evaluation shows that the proposed technique is better than BitCube, as the amount of document increases, in terms of memory consumptions and operation speed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.3 s.333
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• pp.35-42
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• 2005

This paper proposes a new reseeding methodology using a variable-rank multiple-polynomial linear feedback shift register (MP-LFSR). In the proposed reseeding scheme, a test cube with large number of specified bits is encoded with a high-rank polynomial, while a test cube with a small number of specified bits is encoded with a low-rank polynomial. Therefore, according to the number of specified bits in each test cube, the size of the encoded data can be optimally reduced. A variable-rank MP-LFSR can be implemented with a slight modification of a conventional MP-LFSR and Multiple Polynomial can be represented by adding just 1 bit to encoding data. The experimental results on the largest ISCAS'89 benchmark circuits show that the proposed methodology can provide much better encoding efficiency than the previous methods with adequate hardware overhead.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1257-1265
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• 2006

As XML is increasingly used, the need of researches which are related with XML in various fields is also augmented. Many XML document management systems have been actively developed especially for the storage, processing and retrieval of XML documents. The BitCube is a three dimensional bitmap index system that could be manipulated efficiently and improves the performance of document retrieval. However, the site of index is increase rapidly, when a new bit is added to the axis. This problem is caused by its three dimensional memory structure with document, path and word. We suggest a path combining strategy of XML documents in this paper to solve the problem of BitCube that mentioned above. To reduce the size of index, our approach combines sibling nodes that has same ancestor paths, and transforms word axis into value axis. The method reduces the size of index, when the system com poses the three dimensional bitmap index. It also improves the speed of retrieving, and takes efficiency in storage space.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.171-178
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• 2008

Since the XML standard was introduced by the W3C in 1998, documents that have been written in XML have been gradually increasing. Accordingly, several systems have been developed in order to efficiently manage and retrieve massive XML documents. BitCube-a bitmap indexing system-is a representative system for this field of research. Based on the bitmap indexing technique, the path bitmap indexing system(LH06), which performs the clustering of similar paths, improved the problem that the existing BitCube system could not solve, namely, determining similar paths. The path bitmap indexing system has the advantage of a higher retrieval speed in not only exactly matched path searching but also similar path searching. However, the similarity calculation algorithm of this system has a few particular problems. Consequently, it sometimes cannot calculate the similarity even though some of two paths have extremely similar relationships; further, it results in an increment in the number of meaningless clusters. In this paper, we have proposed a novel method that clustering, the similarity between the paths in order to solve these problems. The proposed system yields a stable result for clustering, and it obtains a high score in clustering precision during a performance evaluation against LH06.

• Journal of Astronomy and Space Sciences
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• v.37 no.4
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• pp.219-228
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• 2020

A CubeSat platform has become a popular choice due to inexpensive commercial off-the-shelf (COTS) components and low launch cost. However, it requires more power-efficient and higher-data rate downlink capability for space applications related to remote sensing. In addition, the platform is limited by the size, weight and power (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF) spectrum. The requirements and limitations have put optical communications on promising alternatives to RF communications for a CubeSat platform, owing to the power efficiency and high data rate as well as the license free spectrum. In this study, we analyzed the performance of optical downlink communications compatible with CubeSat platforms in terms of data rate, bit error rate (BER) and outage probability. Mathematical models of BER and outage probability were derived based on not only the log-normal model of atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the fixed slot width, the optimal guard time and modulation orders were chosen to achieve the target data rate. And the two performance metrics, BER and outage data rate, were analyzed and discussed with respect to beam divergence angle, scintillation index and zenith angle.

• International Journal of Computer Science & Network Security
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• v.23 no.6
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• pp.84-90
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• 2023

In this article the problem of computing floating-point reciprocal cube root functions is considered. Our new algorithms for this task decrease the number of arithmetic operations used for computing $1/{\sqrt[3]{x}}$. A new approach for selection of magic constants is presented in order to minimize the computation time for reciprocal cube roots of arguments with movable decimal point. The underlying theory enables partitioning of the base argument range x∈[1,8) into 3 segments, what in turn increases accuracy of initial function approximation and decreases the number of iterations to one. Three best algorithms were implemented and carefully tested on 32-bit microcontroller with ARM core. Their custom C implementations were favourable compared with the algorithm based on cbrtf(x) function taken from C ＜math.h＞ library on three different hardware platforms. As a result, the new fast approximation algorithm for the function $1/{\sqrt[3]{x}}$ was determined that outperforms all other algorithms in terms of computation time and cycle count.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.499-503
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• 2016

We study algorithms that can efficiently find cube roots by modifying Cipolla-Lehmer algorithm. In this paper, we present two type algorithms for finding cube roots in finite field, which improves Cipolla-Lehmer algorithm. If the number of multiplications of two type algorithms has a little bit of a difference, then it is more efficient algorithm which have less storage variables.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.6161-6176
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• 2018

Pseudorandom numbers are useful in cryptographic operations for using as nonce, initial vector, secret key, etc. Security of the cryptosystem relies on the secret key parameters, so a good pseudorandom number is needed. In this paper, we have proposed a new approach for generation of pseudorandom number. This method uses the three dimensional combinational puzzle Rubik Cube for generation of random numbers. The number of possible combinations of the cube approximates to 43 quintillion. The large possible combination of the cube increases the complexity of brute force attack on the generator. The generator uses cryptographic hash function. Chaotic map is being employed for increasing random behavior. The pseudorandom sequence generated can be used for cryptographic applications. The generated sequences are tested for randomness using NIST Statistical Test Suite and other testing methods. The result of the tests and analysis proves that the generated sequences are random.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.1519-1522
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• 2003

기존의 웹 문서나 컨텐츠들의 표현적 한계를 극복하기 위한 방안으로 메타 데이터에 관한 다양한 연구가 수행되어졌고 그 결과의 산물중에 가장 대표적인 것으로 XML을 들 수 있다. XML은 문서의 내용뿐 아니라 구조까지도 기술할 수 있는 장점을 통해 향후 정보 교환에 핵심적인 역할을 할 것으로 기대되어지고 있으며 이에 따라 XML 문서를 효율적으로 저장하고 검색하기 위한 다양한 연구가 진행되고 있다. BitCube는 Bit-wise 연산이 가능한 3차원 비트맵 인덱싱을 사용하여 XML 문서들의 구조적 유사성에 따라 클러스터링하고 사용자의 질의에 대한 처리를 수행하는 인덱싱 기법으로 그것의 빠른 성능을 입증하였다. 그러나 BitCube의 클러스터링은 XML 문서의 경로에 중점을 둔 것이므로 클러스터와 경로가 담고 있는 실제 단어들간에는 연관성이 없으므로 3차원 비트맵 인덱스는 하나의 평면을 제외한 모든 평면이 굉장히 높은 공간 사용량을 갖는 회소행렬이 된다. 본 논문에서는 늘어나는 방대한 문서의 양으로 인한 시스템의 성능 저하를 막고 안정적인 성능을 유지할 수 있도록 기존 연산의 성능을 저하시키지 않으면서 공간을 최소화 할 수 있는 연결 리스트틀 설계하고 3차원 비트맵 인덱스를 연결 리스트로 재구성하는 방법을 제시한다.

• The Journal of Society for e-Business Studies
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• v.18 no.2
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• pp.153-173
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• 2013

The ontology has been gaining increasing interests by recent arise of the semantic web and related technologies. The focus is mostly on inference query processing that requires high-level techniques for storage and searching ontologies efficiently, and it has been actively studied in the area of semantic-based searching. W3C's recommendation is to use RDFS and OWL for representing ontologies. However memory-based editors, inference engines, and triple storages all store ontology as a simple set of triplets. Naturally the performance is limited, especially when a large-scale ontology needs to be processed. A variety of researches on proposing algorithms for efficient inference query processing has been conducted, and many of them are based on using proven relational database technology. However, none of them had been successful in obtaining the complete set of inference results which reflects the five characteristics of the ontology properties. In this paper, we propose a new index structure called hyper cube index to efficiently process inference queries. Our approach is based on an intuition that an index can speed up the query processing when extensive inferencing is required.