• Journal of KIISE:Databases
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• v.27 no.4
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• pp.671-681
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• 2000

클라이언트-서버(Client-Server) 데이터베이스 환경에서 병목현상의 해결책으로 클라이언트캐시(Client cache)를 사용할 수 있다. 여러 클라이언트들이 같은 데이터베이스의 일부를 캐시한 복사본을 사용할 때, 다른 클라이언트들과 서버간에 일관성 유지를 보장해주어야 한다. 캐시의 일관성을 유지하기 위한 여러 가지 알고리즘들이 제안되어왔다. 그 중에서 O2PL(Optimistic Two Phase Locking) 기법은 동시성을 증가시킬 수 있는 주요 장점이 있다. 그러나 O2PL 알고리즘은 트랜잭션이 완료(commit) 연산을 요구하는 시점에서 접근한 캐시데이터의 일관성을 위한 작업이 시작되므로 최종적인 완료까지는 지연이 발생하게된다. 이때 다른 클라이언트에서 잠금 충돌(lock conflict)에 의해 전역 교착상태(global deadlock)가 발생한다면 블락(block)되어 지연되는 시간은 더욱 증가하게된다. 본 논문에서는 향상된 O2PL 기법으로 PN(Preemption by Notification)-O2PL 기법을 제안한다. 이 접근에서는 O2PL의 특성으로 얻을 수 있는 연산정보를 관련된 다른 트랜잭션에게 통지(notification)로 사용하고 제시한 조건에 해당할 경우 상대 자원을 바로 사용할 수 있게 한다. 이 조건은 대부분의 전역 교착 상태에 해당하는 두 트랜잭션간의 교착상태를 조기에 신속히 감지할 수 있게 하여 트랜잭션 완료의 지연을 감소시키게 한다. PN-O2PL 알고리즘이 기존의 O2PL기법보다 빠른 응답시간을 얻을 수 있음을 모의 실험을 통하여 보인다.

• Journal of KIISE:Software and Applications
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• v.31 no.1
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• pp.89-99
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• 2004

This paper proposes a morphological analysis method that enables morphological analysis by checking conditions between two adjacent morphemes. These conditions are fed from a dictionary. This method eliminates a code conversion module and the application of transformational rules for candidate generation. The method claims that very high speed morphological analysis is attainable through simple bit operations for adjacency condition check. MACH, an implementation of the proposed method, is a supersonic Korean morphological analyzer which is able to analyze a document of 1 GB in 5 minutes on a PC with 1.13 GHz Pentium III CPU. The analysis accuracy of MACH is 99.2 %.

• Journal of the Korea Computer Industry Society
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• v.2 no.10
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• pp.1349-1354
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• 2001

In the Traveling Salesman Problem(TSP), a set of N cities is given and the problem is to find the shortest route connecting them all, with no city visited twice and return to the city at which it started. Since TSP is a well-known combinatorial optimization problem and belongs to the class of NP-complete problems, various techniques are required for finding optimum or near optimum solution to the TSP. Especially DNA computing, which uses real bio-molecules to perform computations supported by molecular biology, has been studied by many researchers to solve NP-complete problem using massive parallelism of DNA computing. Though very promising, DNA computing technology of today is inefficiency because the effective computing models and operations reflected the characteristics of bio-molecules have not been developed yet. In this paper, I design new Polymerase Chain Reaction(PCR) operations of DNA computing to solve TSP.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.691-698
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• 2009

Chen et al. proposed a RFID authentication protocol for anti-counterfeiting and privacy protection. A feasible security mechanism for anti-counterfeiting and privacy protection was proposed using XOR and random number shifting operations to enhance RFID tag's security providing a low cost. However, their authentication protocol has some drawbacks and security problems because they did not consider the surrounding environments. We conduct analysis on the protocol and identify problematic areas for improvement of the research. We also provide enhanced authentication and update scheme based on the comment for efficient supply chain management. The proposed protocol was analyzed and compared with typical XOR based RFID authentication protocols and it was confirmed that our protocol has high safety and low communication cost.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.44-51
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• 2013

Raster operations are widely used to display full-color graphics images (or pixmaps) and single-color images (or bitmaps). These features are strongly needed for image processing applications and font output. However, current mobile graphics platforms, including OpenGL ES hardware implementations, do not directly support these features. To fully support those raster operations on the mobile graphics platforms, we interpreted the graphics images as a set of 3D points, and processed those 3D points through the typical 3D geometry pipelines, in a full-software implementation. Our implementation shows sufficient execution speeds, and passed the official conformance tests to show its correctness.

• Journal of KIISE:Databases
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• v.35 no.2
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• pp.143-154
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• 2008

RFID events are large volume of stream data which come out continuously. Many studies have been done to detect a business event in RFID stream. However, the existing methods have many problems which increase unnecessary operations when business events do not satisfy minimum conditions. In this paper, to remove unnecessary operations, we define the minimum condition of business events and propose an efficient method that detects business events only when the minimum condition is satisfied. To check the minimum condition of business events, we register business queries in a query index. We detect business events using the query index and bitmap. It is shown through various experiment that the proposed method outperforms the existing methods.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.582-587
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• 2008

Structural join is one of the most typical techniques for evaluating XML path queries. Recent researches for structural joins focus on techniques of skipping unnecessary elements using the horizontal distribution information of elements that is indexed on a structure like B+ tree. However, those techniques make the structural join complicated and cannot guarantee efficient join processing due to the overhead of an index structure. In this paper, we propose a new structural join technique that exploits the level information of XML elements. Our technique can skip unnecessary elements using level information, which is vertical distribution information of elements. Through the experimental results, we show that our technique can evaluate structural joins efficiently.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.2
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• pp.93-98
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• 2003

This paper presents two new algorithms and their architectures for $AB^2 $ multiplication over $GF(2^m)$.First, a new architecture with a new algorithm is designed based on LFSR (Linear Feedback Shift Register) architecture. Furthermore, modified $AB^2 $ multiplier is derived from the multiplier. The multipliers and the structure use AOP (All One Polynomial) as a modulus, which hat the properties of ail coefficients with 1. Simulation results thews that proposed architecture has lower hardware complexity than previous architectures. They could be. Therefore it is useful for implementing the exponential ion architecture, which is the tore operation In public-key cryptosystems.

• Journal of KIISE:Software and Applications
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• v.26 no.3
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• pp.353-364
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• 1999

공간 데이터베이스는 일반 관계형 데이터베이스나 객체지향 데이터베이스에 비해 다음과 같은 특징을 가진다. 첫째, 공간 데이터베이스에서의 질의는 공간 질의와 비공간 질의가 섞여서 들어 온다. 둘째, 공간 질의는 비공간 질의에 비해 데이터의 복잡성과 방대함으로 인해 주로 2 단계(여과 단계 및 정제 단계)로 나누어 처리되었다. 셋째, 공간 객체들은 대부분 공간 색인을 가지고 있다. 본 논문에서는 이러한 공간 데이터베이스의 특성을 잘 반영하는 질의 최적화 기법을 제안한다. 첫 번째 방법으로 질의 수행 단계 이전의 최적화 단계에서부터 여과 및 정제를 분리하여 생각하는 것이다. 두 번째 방법으로는 복잡한 질의에 대해서 각각의 공간 연산을 여과/정제 단계로 분리한후 여러 정제 단계 연산들을 합쳐 한꺼번에 처리 할수 있고 여러 여과 단계 연산들도 마찬가지로 합쳐질 수 있다. 본 논문에서는 또한 여과/정제를 질의 최적화 단계에서 분리한 여과/정제 조기 분리 (ESFAR) 최적화 기법에 대한 규칙 기반 질의 최적화 기법을 제안한다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.21-31
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• 1999

In this paper we study on an interface connection between spatial operators and temporal operators to support the unified operations for spationtemporal data. The integration development of the spatiotemporal operations will be defined as a common use of spatiotemporal relationship operators by spatiotemporal referencing macros. additionally we propose an integration algorithm of a history operator and temporal relationship operators. Then the proposed system will be implemented on the commercial GIS software and evaluated by examples of spatiotemporal query expressions. Here, our integration of spatial and temporal operators will provide spatiotemporal query expressions with a useful framework.