• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1539-1542
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• 2003

최근 소프트웨어 개발에서의 핵심어인 객체지향(object oriented)은 1970년대 초부터 중요하게 인식 되기 시작했다. 현재는 객체지향에 대한 많은 관련 연구를 통하여 그 활용범위가 증대되고 있다. 본 연구에서는 객체지향 연구의 한 부분인 디자인 패턴 중에서 많이 이용되는 Iterator(Cursor) Pattern을 활용하여 닷넷(.NET) 기반에서의 특정 비즈니스를 위한 데이터 접속 객체를 연구하였다.

• The KIPS Transactions:PartD
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• v.8D no.6
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• pp.637-644
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• 2001

EJB, providing specification for development and deployment of component based application, permits distributed development as central element of J2EE environment that manages automatically transaction management, persistence, concurrency control that are the most complicated work in enterprise environment. In this paper, we wish to resolve DAO's transaction logic complexity and performance reduction of system in the EJB based legacy system. Therefore, this paper describes the design and implementation of IDAO that applies Iterator pattern. IDAO gets effect that reduces complexity of transaction logic, system overload by database connection, and reduction of performance through container managed transaction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.970-976
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• 2001

In this paper, OUIG IDL CFE, provided by Sunsoft, is used to take a IDL definitions as inputs and parse those. OmniORB3 is introduced to support functionality of the ORB. Suns CFE produce AST after parsing inputs. Actually, the node of AST Is instances of classes which are derived from CFE classes. As the compiler back end visit the node of the AST using iterator class, UTL_ScopeActiveIterator, it dumps codes of output. During processing, two files are generated. Routines of generating code are invoked by BE_produce.cc and codes are produced while visiting root of AST, idl_global->root(). The dump* functions which dump codes is called according to the type of node. In this paper, Mapping C++ of IDL definition is experimented and results In the same as that of omniidl which is provided by omniORB3. The code of results behavior correctly on omniORB3. In the future, we are interested in optimizing the performance of marshalling code via IDL compiler.

• The KIPS Transactions:PartD
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• v.16D no.6
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• pp.835-844
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• 2009

Today, most of all the query processors in the world generally use the 'Pipelining' method to acquire fast response time (first record latency) and less memory usage. Each of the operator nodes in the Query Execution Plan (QEP) provides Open(), Next(), and Close() functions for their interface to facilitate the iterator mechanism. However, the embedded database systems for the mobile devices, based on the FLASH memory, usually require a function like Previous(), which returns the previous records from current position. It is because that, in the embedded environment, the mobile devices cannot fully provide it main memory to store all the query results. So, whenever needed the previously read records the user (program) should re-fetch the previous records using the Previous() function: the BACKWARD data fetch. In this paper, I introduce the 'Direction Switching Problem' caused by the Previous() function and suggest 'Block-wise Skipping' method to fully utilize the benefits of the block-based data transfer mechanism, which is widely accepted by most of the today's relational database management systems.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.19-34
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• 2005

The difficulties in implementing of image processing algorithms are a major reason for the lack of research into algorithm comparison. This fact makes an image processing research with difficult. We conclude that it is important to represent algorithms in form of reusable code. Since current image processing systems do not fulfill all requirements we must pose on reusable implementations, we propose to solve the reuse problem by applying generic programming. We define two dimensional iterators, which mediate between image processing algorithms and their underlying data structures, so that the same algorithm implementation can be applied to any number of different image formats. The elegance and efficiency of this approach is illustrated by a number of useful examples and demonstrated by porting in existing image processing algorithm IDE(Integrated Development Environment).

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.5
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• pp.543-552
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• 1999

The iterator technique which is used for implementing physical operators of the query executor is known for its efficiency and extensibility. The most widely used technique for processing an operator on spatial objects is to process by dividing it into the filter step and the refinement step. Recently, there was a research for an optimizer which can generate more efficient query execution plans than those of traditional methods by separating a spatial operator into filter and refinement steps in the level of the object algebra. But, traditional query executors were not designed considering such query execution plans. So they have no function of transmitting the result of the filter operation between operators. We propose two methods, the probe technique and the tag technique, which transmit the result of the filter operator when using the iterator in the query execution plan in which operators are separated by filter/refinement steps and other operators can be allowed between the steps. Whereas the probe technique extends the state record within an operator, the tag technique stores the result of a filter step in an intermediate result in the form of the tag. Based on the comparison of these methods, we design and implement a query executor using the tag technique that is superior in extensibility. The implemented query executor can execute operations defined in the Spatial Object Algebra(SOA) to process an extended OQL for spatial queries.

• Journal of Korea Spatial Information System Society
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• v.4 no.1 s.7
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• pp.39-46
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• 2002

In distributed spatial database systems, users nay issue a query that joins two relations stored at different sites. The sheer volume and complexity of spatial data bring out expensive CPU and I/O costs during the spatial join processing. This paper shows a new spatial join method which joins two spatial relation in a parallel way. Firstly, the initial join operation is divided into two distinct ones by partitioning one of two participating relations based on the region. This two join operations are assigned to each sites and executed simultaneously. Finally, each intermediate result sets from the two join operations are merged to an ultimate result set. This method reduces the number of spatial objects participating in the spatial operations. It also reduces the scope and the number of scanning spatial indices. And it does not materialize the temporary results by implementing the join algebra operators using the iterator. The performance test shows that this join method can lead to efficient use in terms of buffer and disk by narrowing down the joining region and decreasing the number of spatial objects.