• Proceedings of the KSR Conference
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• 2003.10b
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• pp.40-45
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• 2003

Korea selected to introduce high-speed railway system from advanced countries in order to accumulate railway technologies and develop exiting domestic logistics system. After many twists and turns, we adopted to introduce France's high-speed railway called 'TGV'. Despite many difficulties along with trials and errors, it is expected that Korean high-speed railway will be brilliantly launched in April 2004, although it has been commissioned for multi-discipline tests. It is forecast that the opening of high-speed railway will bring us the epoch-making development of logistics system. However, what if there are really some problems in the operation of high-speed railway? We cannot consider and highlight only the positive aspects of our own high-speed railway. In terms of many challenging aspects we would face in the future, there would be some matters we must consider and point out in this opportunity. In this regard, the direction for developing high-speed railway stations requires the harmony between profitability and public benefits, which must involve compatibility with other traffice systems and practical policies to secure competitive edges.

• Proceedings of the KSRS Conference
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• v.2
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• pp.812-815
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• 2006

Proteins are essential agents for controlling, effecting and modulating cellular functions, and proteins with similar sequences have diverged from a common ancestral gene, and have similar structures and functions. Function prediction of unknown proteins remains one of the most challenging problems in bioinformatics. Recently, various computational approaches have been developed for identification of short sequences that are conserved within a family of closely related protein sequence. Protein function is often correlated with highly conserved motifs. Motif is the smallest unit of protein structure and function, and intends to make core part among protein structural and functional components. Therefore, prediction methods using data mining or machine learning have been developed. In this paper, we describe an approach for protein function prediction of motif-based models using data mining. Our work consists of three phrases. We make training and test data set and construct classifier using a training set. Also, through experiments, we evaluate our classifier with other classifiers in point of the accuracy of resulting classification.

• Advances in pediatric surgery
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• v.3 no.2
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• pp.164-167
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• 1997

Conjoined twins are one of the rarest and most challenging congenital anomalies in pediatric surgery. Successful surgical separation is difficult because it the majority of conjoined twins in is technically typical to separate shared vital organs successfully. The timing of separation is variable, but separation is usually delayed until such infants are relatively mature(i.e, 9-12 months of age). Operative survival was 50 % in the neonatal period, but 90 % in those over 4 months of age. The present case was successfully separated early beacase of cardiac problems in one of the twins. These twins were omphalopagus and only the liver was shared through a bridge. The vascular and biliary trees were independent from each other. Successful surgical separation was on 11th day of life, but one died of sepsis 18 days after operation.

• Interdisciplinary Bio Central
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• v.1 no.1
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• pp.4.1-4.7
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• 2009

Introduction: Histone modifications and DNA methylation are the major factors in epigenetic gene regulation. Especially, revealing how histone modifications are related to DNA methylation is one of the challenging problems in this field. In this paper, we address this issue and propose several plausible mechanisms for precise controlling of DNA methylation status at CpG islands. Materials and Methods: To establish the regulatory relationships, we used 38 histone modification types including H2A.Z and CTCF, and DNA methylation status at CpG islands across chromosome 6, 20, and 22 of human CD4+ T cell. We utilized Bayesian network to construct regulatory network. Results and Discussion: We found several meaningful relationships supported by previous studies. In addition, our results show that histone modifications can be clustered into several groups with different regulatory properties. Based on those findings we predicted the status of methylation level at CpG islands with high accuracy, and suggested core-regulatory network to control DNA methylation status.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2284-2296
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• 1994

Force control of robotic mechanisms continues to be a challenging area. Previous implementation have seldom produced satisfactory results, and researchers in the past have experienced significant instability problems associated with their force controllers. In this study, a new stability factor in force control will be pointed out. When a manipulator is constrained to an environment(force-controlled), geometric instability due to the relationship between the manipulator configuration and the force-controlled direction is shown to be a significant factor in overall system stability. This exploratory study points out a rather intuitive, geometrically based stability factor in terms of an effective system stiffness and analyzes the phenomenon both analytically and graphically. Also, a stiffness control algorithm using the kinematic redundancy of a kinematically redundant manipulator is proposed to improve the overall stability in force control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5780-5802
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• 2017

Cloud computing system consists of distributed resources in a dynamic and decentralized environment. Therefore, using cloud computing resources efficiently and getting the maximum profits are still challenging problems to the cloud service providers and cloud service users. It is important to provide the efficient scheduling. To schedule cloud resources, numerous heuristic algorithms such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Ant Colony Optimization (ACO), Cuckoo Search (CS) algorithms have been adopted. The paper proposes a Modified Particle Swarm Optimization (MPSO) algorithm to solve the above mentioned issues. We first formulate an optimization problem and propose a Modified PSO optimization technique. The performance of MPSO was evaluated against PSO, and GA. Our experimental results show that the proposed MPSO minimizes the task execution time, and maximizes the resource utilization rate.

• ETRI Journal
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• v.20 no.4
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• pp.346-360
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• 1998

It is challenging to parallelize problems with irregular computation and communication. In this paper, we propose an asynchronous algorithm for balancing unpredictable workload on distributed-memory machines. By using an initial workload estimate, we first partition the computations such that the workload is distributed evenly across the processors. In addition, we perform task migrations dynamically for adapting to the evolving workload. To demonstrate the usefulness of our load balancing strategy, we conducted experiments on an IBM SP2 and a Cray T3D. Experimental results show that our task migration strategy can balance unpredictable workload with little overhead. Our code using C and MPI is portable onto other distributed-memory machines.

• Clinics in Shoulder and Elbow
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• v.20 no.2
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• pp.105-112
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• 2017

Rotator cuff tears commonly affect the shoulder joints. Despite developments in surgical techniques and instrumentation, the treatment of massive rotator cuff tears remains challenging. The problems associated with rotator cuff repairs, such as inferior mechanical properties and high retear rates are yet to be solved. Recently, patch augmentation has been suggested as an alternative treatment because it can reinforce mechanical properties at the initial stage of healing and reduce gap formation. The purpose of this article was to comprehensively summarize the concepts and the consensus surrounding patch augmentation and evaluate the clinical and anatomical outcomes after patch augmentation for massive rotator cuff tears.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.55-58
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• 1997

In automotive industries, stamping of laser-welded blank gives many merits which brings about dimensional accuracy, strong body assembly and high productivity. However the welding of blanks with different thickness or/and different strength materials introduces many challenging formability problems for process development and tool design. In this paper, the deformation characteristics for deep drawing process of laser-welded blank with different thickness sheets are investigated by experiment and FEM simulation. And also the optimal location of weld line in laser-welded blank with different thickness sheets is calculated to compensate for the movement of weld line on deep drawing process. In addition, the effect of location of weld line is clarified using FEM simulation.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.5
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• pp.331-336
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• 2016

Multi-bit tries have been proposed to improve the search performance of a binary trie by providing flexibility in stride values, which identify the number of bits examined at a time. However, constructing a variable-stride multi-bit trie is challenging since it is not easy to determine a proper stride value that satisfies the required performance at each node. The aim of this paper is to identify several desired characteristics of a trie for IP address lookup problems, and to propose a multi-stride decision trie that has these characteristics. Simulation results using actual routing sets with about 30,000 to 220,000 prefixes show that the proposed multi-stride decision trie has the desired characteristics and achieves IP address lookup using 33% to 47% of the 2-bit trie in the average number of node accesses, while requiring a smaller amount of memory.