• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1189-1196
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• 2003

Owing to the developed If industry, many people are more and more interested in Workflow which is an automated business processing system. In this paper, we present basic structures and various parallel processing structures of a workflow using EMFG (Extended Mark Flow Graph) that makes conceptional design available. And then, We design a workflow with EMFG. We propose the commitability verification method to check whether a workflow can complete or not and the logical bug verification method to find whether invalid components exist or not by using simulation result of it. The proposed EMFG modeling and analysis method for a workflow make it possible to become a visual and formal design. Also, it makes intuitional and mathematical analysis possible.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.19-21
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• 2002

우리는 저전력 소모를 위한 상위 수준(high-level)에서의 효과적인 바인딩(binding) 알고리즘을 제안한다. 이전 연구들에 의해서 저전력 소모를 위한 몇몇의 바인딩 알고리즘들은 멀티-코모도티 플로우(multi-commodity flow) 문제로 모델링 될 수 있음이 밝혀졌다. 그러나 멀티-코모도티 플로우 문제는 NP-hard이기 때문에 진은 크기의 설계에만 적용될 수 있다. 이러한 제약을 극복하기 위해 우리는 네트워크 상의 플로우를 잘 이용해서 효과적으로 빠른 시간 안에 최적에 가까운 결과를 낼 수 있는 방법을 제안하여 크기가 큰 설계에도 적용할 수 있도록 한다. 이를 위해 우리는 첫번째 단계에서는 네트워크에서 최소 비용의 최대 플로우 (maximum f1ow -minimum cost)를 구하는 방법을 부분적으로 이용해서 유효한 결과를 구하고 두 번째 단계에서는 이를 반복적으로 개선시켜나가는 2 단계의 알고리즘을 제안한다. 벤치마크를 이용한 실험 결과는 제안된 알고리즘이 실제적인 설계에 적용되었을때, 충분히 빠른 시간 안에 최적에 가까운 결과를 생성함을 보여준다.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.145-148
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• 2002

기업 등 조직의 경계를 초월한 분산 환경에서의 정보교환은 인터넷이 확산되면서 더욱 증가하고 있다. 특히 전자결재나 기업 간 상거래, 공동작업을 위한 정보나 메시지 교환이 폭발적으로 증가하고 있는 것이 현실이다. 본 논문은 다양한 정보들이 분산된 노드와 사용자간 의미 있는 메시지로 교환될 수 있도록 지원하는 메시지 엔진을 설계하는 연구이다. 특히 자바 메시징 서비스의 모델을 기본으로 하여 메시징 요구사항을 충족함과 아울러 다양한 인터페이스의 제공에 초점을 두기보다는 핵심적인 메시징 서비스 모델에 치중하여 다양한 응용에 통합되어 활용될 수 있도록 설계하였다.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.76-82
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• 2010

Reversible watermarking hides some information in a digital image in such a way that an authorized party could decode the hidden information and also restore the image to its original state. In this paper, a high capacity reversible watermarking method using histogram shifting is proposed. In order to increase embedding capacity, the proposed method divides the image into $2{\times}2$ blocks and uses a paring(horizontal, vertical, diagonal) inside each block, then finds a maximum embedding bin which has the most frequent difference values among the parings. Also, the proposed method removes the overflow and underflow by using location map which including the maximum embedding bin and increases the embedding capacity by embedding iteratively. The experimental results show that the proposed method provides a high embedding capacity and good visual quality compared with the conventional reversible watermarking methods.

• KIISE Transactions on Computing Practices
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• v.21 no.9
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• pp.587-595
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• 2015

Several fields of science have traditionally demanded large-scale workflow support, which requires thousands of central processing unit (CPU) cores. In order to support such large-scale scientific workflows, large-capacity cluster systems such as supercomputers are widely used. However, as users require a diversity of software packages and configurations, a system administrator has some trouble in making a service environment in real time. In this paper, we present a container-based cluster management platform and introduce an implementation case to minimize performance reduction and dynamically provide a distributed computing environment desired by users. This paper offers the following contributions. First, a container-based virtualization technology is assimilated with a resource and job management system to expand applicability to support large-scale scientific workflows. Second, an implementation case in which docker and HTCondor are interlocked is introduced. Lastly, docker and native performance comparison results using two widely known benchmark tools and Monte-Carlo simulation implemented using various programming languages are presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.583-586
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• 2002

Molding properties of etched surface pattern are presented. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1295-1301
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• 2013

The cause of flow mark defect is known as non-uniform temperature of mold surface when the flow front meets the cold cavity. The exact definition and classification of Flow mark is not clear because the mechanism of flow mark is not figured out till now. Any injection molding analysis software can not predict the flow mark phenomena. To solve weldline and flow mark defects, the gate thickness is reduced to increase the melt front velocity and the melt front velocity of the flow mark area is increased from 82.3mm/s to 104.7mm/s. In addition, the bulk temperature of the flow mark area is increased from $178.3^{\circ}C$to $215.2^{\circ}C$ by adding a cold slug well. The flow mark phenomena can be greatly reduced by increasing the flow front velocity and elevating the bulk temperature.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.25-32
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• 2003

Molding properties of etched surface pattern are presented. Injection molding has given attention on improving dimensional accuracy and productivity. However, the molding of etched surface pattern on plastic parts is not researched relatively for its additional values, which can meet design function and customer's attraction. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• Journal of KIISE:Software and Applications
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• v.37 no.6
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• pp.417-429
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• 2010

Reversible watermarking inserts watermark into digital media in such a way that visual transparency is preserved and then enables to restore the original media from the marked one without any loss of media quality. This watermarking can be applied to quality-sensitive imaging such as medical imaging, military imaging, remote-sensing imaging, and precious artwork, where the original media should be preserved during image processing and analysis. In this paper, a reversible image watermarking technique that embeds message bits by modifying the differential histogram of adjacent pixels is presented. In order to satisfy both high embedding capacity and visual quality, the proposed technique exploits the fact that adjacent pixels in the image have highly spatial correlation. Also, we prevent overflow/underflow problem and salt-and-pepper artifacts by employing a predicted error compensation scheme. Through experiments using various test images, we prove that the presented technique provides perfect reversibility and high embedding capacity, while maintaining the induced-distortion low.

• The KIPS Transactions:PartB
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• v.17B no.4
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• pp.275-286
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• 2010

Reversible watermarking which can preserve the original quality of the digital contents and protect the copyright has been studied actively. Especially, in medical, military, and art fields, the need for reversible watermarking is increasing. This paper proposes a high-capacity reversible watermarking through predicted error expansion and error estimation compensation. Watermark is embedded by expanding the difference histogram between the original value and the predicted value. Differently from previous methods calculating the difference between adjacent pixels, the presented method calculates the difference between the original value and the predicted value, and that increases the number of the histogram value, where the watermark is embedded. As a result, the high capacity is achieved. The inserted watermark is extracted by restoring the histogram between the original value and the predicted value. To prove the performance, the presented algorithm is compared with other previous methods on various test images. The result supports that the presented algorithm has a perfect reversibility, a high image quality, and a high capacity.