• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.295-310
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• 2002

Software architecture representing a common high-level abstraction of a system can be used as a basis for creating mutual understanding among all stakeholders of the system. In determining a software architecture's fitness with respect to its desired qualities as well as in improving a software architecture, software architecture evaluation is importantly performed. However moat of architecture evaluation methods are not still sufficient in that they do not explicitly consider artifacts discussed during architecture evaluation and their processes are net systematic. As a result, we are hard to follow them. To address these problems, this paper presents the method to evaluate systematically a software architecture with respect to its desired qualities. In this approach, the functional and non-functional requirements are separately handled, and software architecture is represented in the 4+1 view model using UML. Through this initial consideration, the important artifacts such as goals, scope, and target of evaluation are clearly determined. Also, the method provides the well defined process to produce the important evaluation artifacts such as sub-designs, design decisions, rationale, qualities from inputs. In addition, it enables us to determine satisfaction of a architecture with respect its desired qualities or improve a architecture through the structured evaluation results.

• The KIPS Transactions:PartA
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• v.19A no.1
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• pp.35-44
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• 2012

Traditional technologies that are used to improve the performance of hard disk drives show many negative cases if they are applied to solid state drives (SSD). Access time and block sequence in hard disk drives that consist of mechanical components are very important performance factors. Meanwhile, SSD provides superior random read performance that is not affected by block address sequence due to the characteristics of flash memory. Practically, it is recommended to disable prefetching if a SSD is installed in a personal computer. However, this paper presents a combinational method of a prefetching scheme and a memory management that consider the internal structure of SSD and the characteristics of NAND flash memory. It is important that SSD must concurrently operate multiple flash memory chips. The I/O unit size of NAND flash memory tends to increase and it exceeded the block size of operating systems. Hence, the proposed prefetching scheme performs in an operating unit of SSD. To complement a weak point of the prefetching scheme, the proposed memory management scheme adaptively evicts uselessly prefetched data to maximize the sum of cache hit rate and prefetch hit rate. We implemented the proposed schemes as a Linux kernel module and evaluated them using a commercial SSD. The schemes improved the I/O performance up to 26% in a given experiment.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.383-390
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• 2006

Product-line engineering is a dreaming goal in software engineering research. Unfortunately, the current underlying technologies do not seem to be still not much matured enough to make it viable in the industry. Based on our experiences in working on mobile telephony systems over 3 years, now we are in the course of developing an approach to product-line engineering for mobile telephony system software. In this paper, the experiences are shared together with our research motivation and idea. Consequently, we propose an approach to building and maintaining telephony application logics from the perspective of scenes. As a Domain-Specific Language(DSL), Menu Navigation Viewpoint(MNV) DSL is designed to deal with the problem domain of telephony applications. The functional requirements on how a set of telephony application logics are configured can be so various depending on manufacturer, product concept, service carrier, and so on. However, there is a commonality that all of the currently used telephony application logics can be generally described from the point of user's view, with a set of functional features that can be combinatorially synthesized from typical telephony services(i.e. voice/video telephony, CBS/SMS/MMS, address book, data connection, camera/multimedia, web browsing, etc.), and their possible connectivity. MNV DSL description acts as a backbone software architecture based on which the other types of telephony application logics are placed and aligned to work together globally.

• Journal of Korea Technology Innovation Society
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• v.14 no.2
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• pp.343-372
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• 2011

Since the introduction of motion picture in the early 20th century, Korean motion picture industry has gradually evolved as one of the world leaders. However, due to the rapid technological change as exemplified by the emergence of the new digital and 3D cinema technologies, there is a need to re-consider the existing technology policy and strategy designed for the adoption and effective use of new technologies. In this paper, the authors address this issue by emphasizing the technological development side rather than the use/adoption side. In order to provide policy makers with critical information on the current status of the sector, we analyzed the sectoral innovation system of the Korean motion picture industry. In order to conduct this analysis, we re-visited previous literature and interviewed experts in the motion picture sector. Then, the authors attempted to identify the characteristics and problems of the current Korean motion picture industry. Based on the insights gained from this research, we draw policy implications for technological innovation in this sector. However, the implications from this paper are not limited to the motion picture industry. As the motion picture industry is a new case for innovation studies, our paper may provide new research opportunities to the academia.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.11
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• pp.626-634
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• 2004

In a client-server model, network server systems suffer from both heavy communication and computational loads. While communication channels become increasingly speedy, the existing protocol stack architectures still include mainly three performance bottlenecks of protocol stack processing, system call, and network interrupt overheads. To address these obstacles, in this paper we present a host-independent network system where a network interface card (NIC) is utilized in an efficient manner. First, by offloading network-related portion to the NIC, the host can fully utilize its processing power for other useful purposes. Second, it eliminates the system call overhead, such as context-switching and memory copy operations, since the host communicates with the NIC through its user-level libraries. Third, it a] so reduces the network interrupt operation count as the host handles the interrupt in a segment instead of a packet. The experimental results show that the proposed network system reduces the host CPU overhead for communication system by 68-71%. It also shows that the proposed system improves the communication speed by 11-83% under heavy computational and communication load conditions.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.369-374
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• 2016

The growing demand of virtual computing and storage resources in the cloud computing environment has led to deduplication of storage system for effective reduction and utilization of storage space. In particular, large reduction in the storage space is made possible by preventing data with identical content as the virtual desktop images from being stored on the virtual desktop infrastructure. However, in order to provide reliable support of virtual desktop services, the storage system must address a variety of workloads by virtual desktop, such as performance overhead due to deduplication, periodic data I/O storms and frequent random I/O operations. In this paper, we designed and implemented a clustered file system to support virtual desktop and storage services in cloud computing environment. The proposed clustered file system provides low storage consumption by means of inline deduplication on virtual desktop images. In addition, it reduces performance overhead by deduplication process in the data server and not the virtual host on which virtual desktops are running.

• Journal of the Korean Society of School Health
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• v.13 no.1
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• pp.97-108
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• 2000

This study researches an obesity index and the realities of physical activity of elementary school children and provide basic data to instruct correct physical activity for low weight and obese children. The subject was 813 Elementary School Children of grade 4-6 in Kyungju and data were collected with a Physical Activity Questionnaire from YHS, USA. The collected data were analyzed with real number, percentage, average and standard deviation techniques. The range was by SPSS WIN. Both of them were in the normal range, between -38.3 and 77.7, between low weight and obesity. The results are as follows : 1. An Obesity index according to grade and sex: the average obesity index of 423 boys was $7.56{\pm}15.7$, for girls it was $2.56{\pm}14.3$. Both of them were in the normal range, between -38.3 and 77.7. There were low weight($-38.85{\pm}0.9$) students as well as obese, including extremely low weight children ($-38.85{\pm}0.9$) and extremely obese children. 2. On the whole, in the Frequency of the 25 item physical activities breakdown, children reported to watch TV 1. ($2.7{\pm}0.6$), or do homework($2.1{\pm}0.9$), more than three-fourths of the week, male children, however, played more football($2.0{\pm}0.9$). As male obese children do less MET5, MET8(highly active activity) than male normal children, it was also discovered that low weight children do more severe activity in MET8(high activity). In female cases, it was revealed that neither do highly intense activity. 3. In physical activity, male children received higher points than female children with $92.94{\pm}37.95$ to $74.46{\pm}29.50$. On the whole, male and female obese children had lower score than normal children. 4. As for attitude toward physical activity, male children($31.96{\pm}4.37$) had a positive attitude than female children ($29.57{\pm}3.89$), but obese male children had a negative attitude regarding activity viewed as normal. Therefore, in preventing obesity in elementary school children the treating of under-weight children should be included in the obesity program so as to prevent mal-nutrition or deficiency. It is needed to instruct obese children to carry out intensive work-outs at least 3 times a week through systematic programs. It is also needed that parents and teachers educate elementary school children from an early age with information on the frequency and intensity of work-outs to prevent obesity. It is also desirable that children be educated to carry out physical activities that address their specific needs. As a result of this study, obesity management must be started from elementary school and children should be instructed to act in high-intensity actirities when they spend leisure time.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.4_1
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• pp.311-318
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• 2014

The data of buildings and structures take over large portions of the mapping database with large numbers. Furthermore, those shapes and attributes of building data continuously change over time. Due to those factors, the efficient methodology of updating database for following the most recent data become necessarily. This study has purposed on extracting needed data, which has been changed, by using overlaying analysis of new and old dataset, during updating processes. Following to procedures, we firstly searched for matching pairs of objects from each dataset, and defined the classification algorithm for building updating cases by comparing; those of shape updating cases are divided into 8 cases, while those of attribute updating cases are divided into 4 cases. Also, two updated dataset are set to be automatically saved. For the study, we selected few guidelines; the layer of digital topographic map 1:5000 for the targeted updating data, the building layer of Korea Address Information System map for the reference data, as well as build-up areas in Gwanak-gu, Seoul for the test area. The result of study updated 82.1% in shape and 34.5% in attribute building objects among all.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.626-636
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• 2009

In Mobile IP-enabled wireless LAN (WLAN), packet flows are corrupted due to the handoff of a mobile node (MN) at the link and network layers, which results in burst packet losses and can cause temporary buffer underflow in a streaming client at the MN. This transient behavior hurts time-sensitive streaming media applications severely. Among many suggestions to address this handoff problem, few studies are concerned with empirical issues regarding the practical validation of handoff options on the time-sensitive streaming media applications. In this paper, targeting seamless streaming over Mobile IP-enabled WLAN, we introduce a seamless media streaming framework that estimates accurate pre-buffering level to compensate the handoff latency. In addition, we propose a link-layer (L2) assisted seamless media streaming system as a preliminary version of this framework. The proposed system is designed to reduce the handoff latency and to overcome the playback disruption from an implementation viewpoint. A packet buffering and forwarding mechanism with L2 trigger is implemented to reduce the handoff latency and to eliminate burst packet losses generated during the handoff. A pre-buffering adjustment is also performed to compensate the handoff latency. The experimental results show that the proposed approach eliminates packet losses during the handoff and thus verify the feasibility of seamless media streaming over Mobile IP-enabled WLAN.

• Journal of Distribution Science
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• v.13 no.1
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• pp.57-70
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• 2015

Purpose - Open source software has high utilization in most of the server market. The utilization of open source software is a global trend. Particularly, Internet infrastructure and platform software open source software development has increased rapidly. Since 2003, the Korean government has published open source software promotion policies and a supply promotion policy. The dynamism of the open source software market, the lack of relevant expertise, and the market transformation due to reasons such as changes in the relevant technology occur slowly in relation to adoption. Therefore, this study proposes an assessment model of services provided in an open source software service company. In this study, the service level of open source software companies is classified into an enterprise-level assessment area, the service level assessment area, and service area. The assessment model is developed from an on-site driven evaluation index and proposed evaluation framework; the evaluation procedures and evaluation methods are used to achieve the research objective, involving an impartial evaluation model implemented after pilot testing and validation. Research Design, data, and methodology - This study adopted an iteration development model to accommodate various requirements, and presented and validated the assessment model to address the situation of the open source software service company. Phase 1 - Theoretical background and literature review Phase 2 - Research on an evaluation index based on the open source software service company Phase 3 - Index improvement through expert validation Phase 4 - Finalizing an evaluation model reflecting additional requirements Based on the open source software adoption case study and latest technology trends, we developed an open source software service concept definition and classification of public service activities for open source software service companies. We also presented open source software service company service level measures by developing a service level factor analysis assessment. The Behavior-Structure-Evolution Evaluation Model (BSEM) proposed in this study consisted of a rating methodology for calculating the level that can be granted through the assessment and evaluation of an enterprise-level data model. An open source software service company's service comprises the service area and service domain, while the technology acceptance model comprises the service area, technical domain, technical sub-domain, and open source software name. Finally, the evaluation index comprises the evaluation group, category, and items. Results - Utilization of an open source software service level evaluation model For the development of an open source software service level evaluation model, common service providers need to standardize the quality of the service, so that surveys and expert workshops performed in open source software service companies can establish the evaluation criteria according to their qualitative differences. Conclusion - Based on this evaluation model's systematic evaluation process and monitoring, an open source software service adoption company can acquire reliable information for open source software adoption. Inducing the growth of open source software service companies will facilitate the development of the open source software industry.