• Spatial Information Research
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• v.13 no.4 s.35
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• pp.355-364
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• 2005

Vector data sets (e.g. maps) are currently major sources of displaying, querying, and identifying locations of spatial features in a variety of applications. Especially in mobile environment, the needs for using spatial data is increasing, and the relative large size of vector maps need to be smaller. Recently, there have been several studies about vector map compression. There was clustering-based compression method with novel encoding/decoding scheme. However, precedent studies did not consider that spatial data have to be updated periodically. This paper explores the problem of existing clustering-based compression method. We propose an adaptive approximation method that is capable of handling data updates as well as reducing error levels. Experimental evaluation showed that when an updated event occurred the proposed adaptive approximation method showed enhanced positional accuracy compared with simple cluster based compression method.

• Korean Journal of Radiology
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• v.20 no.6
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• pp.863-879
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• 2019

Hepatocellular carcinoma (HCC) can be noninvasively diagnosed on the basis of its characteristic imaging findings of arterial phase enhancement and portal/delayed "washout" on computed tomography (CT) and magnetic resonance imaging (MRI) in cirrhotic patients. However, different specific diagnostic criteria have been proposed by several countries and major academic societies. In 2018, major guideline updates were proposed by the Association for the Study of Liver Diseases, European Association for the Study of the Liver (EASL), Korean Liver Cancer Association and National Cancer Center (KLCA-NCC) of Korea. In addition to dynamic CT and MRI using extracellular contrast media, these new guidelines now include magnetic resonance imaging (MRI) using hepatobiliary contrast media as the first-line diagnostic test, while the KLCA-NCC and EASL guidelines also include contrast-enhanced ultrasound (CEUS) as the second-line diagnostic test. Therefore, hepatobiliary MR contrast media and CEUS will be increasingly used for the noninvasive diagnosis and staging of HCC. In this review, we discuss the emerging role of hepatobiliary phase MRI and CEUS for the diagnosis of HCC and also review the changes in the HCC diagnostic criteria in major guidelines, including the KLCA-NCC practice guidelines version 2018. In addition, we aimed to pay particular attention to some remaining issues in the noninvasive diagnosis of HCC.

• Journal of Korea Multimedia Society
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• v.11 no.9
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• pp.1258-1266
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• 2008

Most game players obtain more satisfactions by interacting with human players that have fluxed behavior patterns, than with NPC(Non-Player Character)s that have fixed behavior patterns. Since it is impossible that game players always interact with human players, adaptive NPCs that can variously behave are required. In this paper, we present a method to create adaptive NPCs using a dynamic FSM(Finite State Machine). This method configures a dynamic FSM by using behavior information at behavior database, and repeatedly updates the dynamic FSM so that the dynamic FSM's total efficiency approaches to a given target efficiency. NPC adapts to game players through this process. For an experiment, we have implemented a 2D game with this strategy, and experimented with various target efficiencies. We show that a dynamic FSM's total efficiency approaches to target efficiency by updating a dynamic FSM several times over. It means that the adaptive NPC to be generated, adapts to game players.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.1-11
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• 2013

Dynamic Software Update(DSU) is a technique, which updates a new version of the software to a running process without stopping. Many DSU systems that update C application programs are introduced. However, these DSU systems differ in implementation method or in main features. In this paper, we propose a new DSU system that can solve some disadvantages of existing DSU systems. DSU system presented in this paper splits existing program to code, global data and local data and then updates each part of the program considering the characteristics of the respective parts. The proposed system in this paper is implemented and tested on Linux. Also, we compared our DSU system with other DSU systems and we could find some strength of our DSU system. First, the code memory usage of our DSU system can be efficient since our system does not need to maintain code of an old version. Second, the global data memory waste is small because our system does not need to allocate the global data again which is not modified in the new version. Finally, we restore local data of old version in stack area of the new version using stack reconstruction technique. This paper is meaningful since we proposed a new DSU method and we implemented a full DSU system using the method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.5
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• pp.1744-1765
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• 2014

A client stores data in the cloud and uses remote data checking (RDC) schemes to check the integrity of the data. The client can detect the corruption of the data using RDC schemes. Recently, robust RDC schemes have integrated forward error-correcting codes (FECs) to ensure the integrity of data while enabling dynamic update operations. Thus, minor data corruption can be recovered by FECs, whereas major data corruption can be detected by spot-checking techniques. However, this requires high communication overhead for dynamic update, because a small update may require the client to download an entire file. The Variable Length Constraint Group (VLCG) scheme overcomes this disadvantage by downloading the RS-encoded parity data for update instead of the entire file. Despite this, it needs to download all the parity data for any minor update. In this paper, we propose an improved RDC scheme in which the communication overhead can be reduced by downloading only a part of the parity data for update while simultaneously ensuring the integrity of the data. Efficiency and security analysis show that the proposed scheme enhances efficiency without any security degradation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1401-1409
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• 2009

All the forces in the real world act dynamically on structures. Design and analysis should be performed based on the dynamic loads for the safety of structures. Dynamic (transient or vibrational) responses have many peaks in the time domain. Topology optimization, which gives an excellent conceptual design, mainly has been performed with static loads. In topology optimization, the number of design variables is quite large and considering the peaks is fairly costly. Topology optimization in the frequency domain has been performed to consider the dynamic effects; however, it is not sufficient to fully include the dynamic characteristics. In this research, linear dynamic response topology optimization is performed in the time domain. First, the necessity of topology optimization to directly consider the dynamic loads is verified by identifying the relationship between the natural frequency of a structure and the excitation frequency. When the natural frequency of a structure is low, the dynamic characteristics (inertia effect) should be considered. The equivalent static loads (ESLs) method is proposed for linear dynamic response topology optimization. ESLs are made to generate the same response field as that from dynamic loads at each time step of dynamic response analysis. The method was originally developed for size and shape optimizations. The original method is expanded to topology optimization under dynamic loads. At each time step of dynamic analysis, ESLs are calculated and ESLs are used as the external loads in static response topology optimization. The results of topology optimization are used to update the design variables (density of finite elements) and the updated design variables are used in dynamic analysis in a cyclic manner until the convergence criteria are satisfied. The updating rules and convergence criteria in the ESLs method are newly proposed for linear dynamic response topology optimization. The proposed updating rules are the artificial material method and the element elimination method. The artificial material method updates the material property for dynamic analysis at the next cycle using the results of topology optimization. The element elimination method is proposed to remove the element which has low density when static topology optimization is finished. These proposed methods are applied to some examples. The results are discussed in comparison with conventional linear static response topology optimization.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.269-273
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• 2010

Massively Multiplayer Online Game (MMOG) is one of diverse applications where more than hundreds of users enjoy experiencing virtual worlds. Voronoi-based Overlay Network (VON) is proposed to reduce a bandwidth consumption in P2P MMOGs and Vorocast also is made using message forwarding in VON. We propose a dynamic area of interest (AOI) management method that solves problems such as less consistency and high latency due to sending position updates to more neighbor nodes from the message originator in forwarding scheme. Our scheme provides the higher consistency and reduces latency by combining direct connection scheme and Vorocast scheme compared to existing schemes. The proposed model is evaluated through simulations.

• The Journal of the Korea Contents Association
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• v.14 no.1
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• pp.14-23
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• 2014

There have been many researches for XML as the international standard to store and exchange data on the internet. Among these research fields, we focus on the techniques labeling the nodes of the XML tree that is required for querying the structural information. A labeling scheme assigns the unique label to the nodes and supports the queries for the structural information such as Ancestor-Descendant and Parent-Child relationships. In this paper, we propose a labeling scheme using vector representation where the assigned labels are not altered although XML documents are changed dynamically. Our labeling scheme reduces the storage requirement for the labels of the XML tree and provides the efficient query by using the fixed-length labels with a short size. Result of performance evaluation shows that our labeling scheme is superior to the previous approaches.

• Journal of Internet Computing and Services
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• v.2 no.5
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• pp.21-29
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• 2001

In this paper, we present the development of a system(WebPierrot) that helps end-users to generate home pages with the construction of their corresponding web databases without the web programming technique. It consists of a page editor. a database wizard and a database manager. The page editor creates and modifies multimedia home pages. The database wizard generates databases operated with home pages automatically, and the database manager maintains the database related to the home pages. The page editor has been made based on the DHTML(Dynamic Hypertext Markup Language) and lets users generate multimedia home pages interactively. The database manager creates, updates and manages web databases. The system has the advantage which end-users can create multimedia home pages containing databases without requiring web database programming.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.426-432
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• 2000

The hydraulic loading system real-time simulator using a PC and I/O interface board is developed to simulate the dynamic characteristics of hydraulic loading system in real time. The simulator receives the digital on-off control signals generated by the operator through the D/I channels, updates the state and output variables of the hydraulic loading system responding to the input signals and draw the moving pictuters of the lift cylinder, lift arm and loading box on the PC monitor in real time. Also, the operator can observe the displacement and pressure of cylinder, the rotatinal angle, reaction force, and safety factors of lift arm representing the operation of hydraulic loading system through the PC monitor in real time. The real-time simulator can be a very useful tool to design industrial dynamic systems and feel the goodness of the system operation since the operator can observe the moving pictures of the operating system in real time as he operates the real time simulator.