• Journal of KIISE:Computer Systems and Theory
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• v.28 no.9
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• pp.442-460
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• 2001

In video-on-demand(VOD) systems it is important to minimize initial latency and memory requirements. The minimization of initial latency enables the system to provide services with short response time, and the minimization of memory requirements enables the system to service more concurrent user requests with the same amount of memory. In VOD systems, since initial latency and memory requirement increase according to the increment of buffer size allocated to user requests, the buffer size allocated to user requests must be minimized. The existing static buffer allocation scheme, however, determines the buffer size based on the assumption that thy system is in fully loaded state. Thus, when the system is in partially loaded state, the scheme allocates user requests unnecessarily large buffers. This paper proposes a dynamics buffer allocation scheme that allocates user requests the minimum buffer size in fully loaded state as well as a partially loaded state. This scheme dynamically determines the buffer size based on the number of user requests in service and the number of user requests arriving while servicing current requests. In addition, through analyses and simulations, this paper validates that the dynamics buffer allocation outperforms the statics buffer allocation in initial latency and the number of concurrent user requests that can be supported. Our simulation results show that, in proportion to the static buffer allocation scheme, the dynamic buffer allocation scheme reduces the average initial latency by 29%~65%, and in a systems having several disks. increases the average number of concurrent user requests by 48%~68%. Our results show that the dynamic buffer allocation scheme significantly improves the performance and reduce the capacity requirements of VOD systems.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.581-591
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• 2005

Collaborative filtering systems have problems involving sparsity and the provision of recommendations by making correlations between only two users' preferences. These systems recommend items based only on the preferences without taking in to account the contents of the items. As a result, the accuracy of recommendations depends on the data from user-rated items. When users rate items, it can be expected that not all users ran do so earnestly. This brings down the accuracy of recommendations. This paper proposes a collaborative recommendation method for extracting typical group preferences using user-item matrix optimization and user profiles in collaborative tittering systems. The method excludes unproven users by using entropy based on data from user-rated items and groups users into clusters after generating user profiles, and then extracts typical group preferences. The proposed method generates collaborative user profiles by using association word mining to reflect contents as well as preferences of items and groups users into clusters based on the profiles by using the vector space model and the K-means algorithm. To compensate for the shortcoming of providing recommendations using correlations between only two user preferences, the proposed method extracts typical preferences of groups using the entropy theory The typical preferences are extracted by combining user entropies with item preferences. The recommender system using typical group preferences solves the problem caused by recommendations based on preferences rated incorrectly by users and reduces time for retrieving the most similar users in groups.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.232-243
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• 2002

There are many methods for improving TLB (translation lookaside buffer) performance, such as increasing the number of entry in TLB, supporting large page or multiple page sizes. The best way is to support multiple page sizes, but any operating system doesn't support multiple page sizes in user mode. So, we propose the new structure of TLB supporting two pages to obtain the effect of multiple page sizes with high performance and at low cost without operating system support. we propose a new TLB structure supporting two page sizes dynamically and selectively for high performance and low cost design without any operating system support. For high performance, a promotion-TLB is designed by supporting two page sizes. Also in order to attain low power consumption, a banked-TLB is constructed by dividing one fully associative TLB space into two sub-fully associative TLBs. These two banked-TLB structures are integrated into a banked-promotion TLB as a low power and high performance TLB structure for embedded processors. According to the results of comparison and analysis, a similar performance can be achieved by using fewer TLB entries and also power consumption can be reduced by around 50% comparing with the fully associative TLB.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.813-826
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• 1999

실시간 멀티미디어 응용의 등장으로 멀티캐스트와 QoS(Quality of Service) 지원이 필수적인 망 서비스로 부각되고 있다. 이에, ATM 기반의 인터넷에서 IP 멀티캐스트의 효율적인 처리를 위하여 MARS(Multicast Address Resolution Server)가 제안되었고, 기존의 최선 서비스 기반의 인터넷에서 QoS(Quality of Service)를 지원하기 위하여 RSVP(Resource Reservation Protocol)가 제안되었다. 본 논문에서는 ATM 망에서 QoS가 지원되는 IP 멀티캐스트 서비스를 제공하기 위하여 MARS 구조에서 RSVP를 지원하는 두 가지 방안을 제안하고, 시뮬레이션을 통하여 그 성능을 분석하였다. 제안하는 두 가지 방법은 각각 'RSVP 전 홉 노드 방식'과 'MARS 서버 방식'이라 명명하였다. RSVP 전 홉 노드 방식은 송신원으로부터 ATM 망으로 진입하는 노드와 수신원을 향하여 ATM 망을 진출하는 노드 간에 각각 일대일 양방향 VC를 설정하여 멀티캐스트 그룹에 속하는 수신원들이 보내는 자원 예약 메시지를 ATM 망에서 전송하는 방안이다. MARS 서버 방식은 ATM 망을 진출하는 노드와 MARS 서버간에 MARS 제어 메시지 교환을 위해 존재하는 ATM VC를 사용하여 RSVP의 자원 예약 메시지를 전송하고, MARS 서버가 RSVP 자원 예약 메시지를 처리하도록 그 기능을 확장함으로써 ATM 망에서 필요로 하는 제어 VC 수를 절약할 수 있는 방안이다. 시뮬레이션을 통하여, MARS 서버 방식은 ATM 제어 VC의 수를 절약할 수 있을 뿐 아니라 경우에 따라 RSVP 자원 예약 메시지 전달 지연을 줄일 수도 있음을 볼 수 있었다. 그러나, MARS 클러스터 내에 동시에 존재하는 RSVP 흐름이 많을 때에는 MARS 서버 방식의 경우 MARS 서버에서의 병목 현상으로 인해 성능이 저하될 수 있다.Abstract Emerging real time multimedia applications require multicast service with a QoS(Quality of Service) support. An overlay service architecture MARS(Multicast Address Resolution Server) is proposed to support IP multicast over an ATM network, and a resource reservation protocol RSVP is proposed to provide QoS support in the Internet which is originally based upon best effort service only. In this paper, we propose two schemes to support IP multicast service with QoS support over ATM networks: 'RSVP Previous Hop Node(RPHN) scheme' and 'MARS server based scheme'. In RPHN scheme, the RSVP reservation messages are transported via one-to-one ATM control VC from the egress nodes to the ingress nodes of the the multicast flow set up between each pair of nodes. The RSVP message processing occurs at the ingress nodes of the multicast flow. Whereas, in the MARS server based scheme, the RSVP reservation messages are transported via the MARS control VCs between the egress nodes and the MARS server. The RSVP message processing burden is imposed at MARS server in this scheme. For MARS server based scheme, no additional ATM VC is required for RSVP reservation message transmission, while the processing burden at the MARS server is high. Simulation results show that the MARS server based scheme, may accomplish RSVP reservation message delivery with smaller delay as well as saving of the number of ATM VCs. When the number of simultaneous RSVP flows in the MARS cluster is large, however, MARS based scheme may suffer performance degradation since MARS server becomes a performance bottleneck.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.371-378
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• 2004

This paper presents the implementation and performance of the HVIA-GE card, which is a hardware implementation of the Virtual Interface Architecture (VIA) based on Gigabit Ethernet. The HVIA-GE card is a 32-bit/33MHz PCI adapter containing an FPGA for the VIA protocol engine and a Gigabit Ethernet chip set to construct a high performance physical network. HVIA-GE performs virtual-to-physical address translation, Doorbell, and send/receive completion operations in hardware without kernel intervention. In particular, the Address Translation Table (ATT) is stored on the local memory of the HVIA-GE card, and the VIA protocol engine efficiently controls the address translation process by directly accessing the ATT. As a result, the communication overhead during send/receive transactions is greatly reduced. Our experimental results show the maximum bandwidth of 93.7MB/s and the minimum latency of 11.9${\mu}\textrm{s}$. In terms of minimum latency HVIA-GE performs 4.8 times and 9.9 times faster than M-VIA and TCP/IP, respectively, over Gigabit Ethernet. In addition, the maximum bandwidth of HVIA-GE is 50.4% and 65% higher than M-VIA and TCP/IP respectively.

• The Journal of the Korea Contents Association
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• v.9 no.9
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• pp.60-67
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• 2009

This paper describes a development of system that enables the user to simulate the rockfall and landslide from slopes using physical engine. Until now, it will not be able to accomplish the virtual experiment of three-dimensional interpretation about slope informations, stability evaluation, the rockfall and landslide simulation, etc., because of absence of three-dimensional simulation systems which relates with slopes. With like that reason, this paper developed a simulator which is identical or similar the rockfall and the landslide where the possibility which will occur or occurred from actuality is high very actual condition from virtual experiment. For a simulator development, this paper uses the physical engine which is mainly used from computer game and animation development etc., And it will be show the process where the rockfall and landslide occurs with simulator. This simulator which sees the process where the rockfall and the landslide occur from three-dimension computer graphics theory and the physical engine, is a system which is the possibility of showing actual feeling. Therefore, the result of this paper is applied in vehicle travelling guidance system and intelligence traffic systematic etc., because of creates visual service and three-dimensional application of the slope information database which is developed in existing, and will be able to forecast the upgrade of user benefit planning and a service.

• Journal of Distribution Research
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• v.7 no.1
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• pp.61-86
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• 2002

The number of people who perform their banking business on Internet has been increasing drastically during the recent period and the trend still continues. Banks and other types of financial institutions are now competing intensely with each other in attracting customers to this new innovative banking service. The marketers in charge of formulating and implementing the strategies for this new banking business need to understand the behavioral factors as well as the technical factors in order to succeed in attracting more customers to this new service. products. A deep understanding as to why and how the customers are adopting the new service developed on information technology is a prerequisite for a successful marketing effort. The purpose of this dissertation is to find out what factors are playing important roles in the customers'decision related to the adoption of the Internet banking services. The focus of the research is threefold. First. by testing the hypotheses proposed by the Technology Adoption Model, a well-known theory in the IT-related behavioral science, an analysis was made as to which factors are more important in affecting the attitudes and adoption of the Internet banking on the part of customers. Secondly, an analysis was made as to whether the three criteria of the Technographics- -the attitude toward new technology, level of income, and the motivational factor- -are useful as the criteria for segmenting the Korean users of the online banking. Thirdly, an analysis was made as to whether each customer group segmented by the criteria of the Technographics reveal a differential decision process and thus requires a differential approach strategywise.

• The Journal of Industrial Distribution & Business
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• v.10 no.10
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• pp.35-44
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• 2019

Purpose - This study focuses on the continuance intention of O2O fresh agricultural products e-commerce. By literature review, this paper looks through the classical theories which are often applied to study use behavior and continuance intention on the electronic commerce area. Ultimately based on the expectancy theory, Technology acceptance model, success model as well as trust model, a model of the continuance intention of fresh products O2O electronic commerce application is established. Research design, data, and methodology - Among users Chinese consumers have been chosen who have use experience as the research objects. From October 2, 2018 to November 2, 2018, 685 questionnaires in total were collected by the online release and collection. Expect for the negative questionnaires, the remaining 650 pieces of data are statistically analyzed. The collected data were firstly be analyzed by SPSS Ver. 25 on its frequency, reliability and exploratory factors. Then AMOS Ver. 25 is applied to the Confirmatory Factor Analysis, Discriminant Validity and hypothesis testing of the Structural Equation Modeling. Finally, the following research conclusions could be obtained from the hypothesis testing. Results - Firstly, in the extended IS model, quality factor for hypothesis testing, service quality, information quality and delivery quality have obviously present positive influences on satisfaction respectively. Secondly, in the hypothesis testing part of ECM-ISC model and UTAUT model, all hypotheses have presented accepted results. Especially from expectation confirmation to usefulness perception, the influence factor achieves 12.603, In the hypothesis of continuance intention, the influence factor of social influence on continuance intention is 7.748 and also it is the most remarkable one. Conclusions - The results show that the service quality of O2O fresh agricultural products e-commerce has the greatest impact on satisfaction, while the perceived usefulness of consumers has the most significant impact on O2O fresh agricultural products for sustainable use intention. This thesis makes up for the blank of O2O fresh food e-commerce for sustainable use intentions, and provides a theoretical basis for consumers' sustainable use behavior, and practical enlightenment for the sustainable development of O2O fresh agricultural products e-commerce.

• The Journal of Art Theory & Practice
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• no.3
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• pp.51-66
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• 2005

With the advent of the time when the competitiveness of a nation or a city can be evaluated by the extent of cultural reception, the art exhibitions, like other genres of art, are actively held in various ways by different institutions. The spaces of exhibition offered not only by public museums and galleries but also by private galleries, alternative spaces and open-air exhibition spots are being increased. Likewise, the number of exhibitions organized on a large scale by Biennales and local governments is on the increase. In accordance with actual tendency, the Ministry of Culture and Tourism has planned to increase the number of museums and galleries up to 500 by the year of 2011. Under these circumstances, the actual situation shows that the central and local governments are adopting beneficial measures to support the private galleries such as permission of construction on green belt areas and tax deduction. That is, our society has come to realize that the necessity and importance of public as well as private galleries to play their roles as cultural and educational institution. Now, the number of galleries is growing. Exhibitions are held everywhere. Therefore, spectators have more chance to visit them than before. With these conditions and the growing number of amateurs, social interest in curator organizing exhibitions is getting popular. Because of the rise of curatorial popularity on the social level, the influence of curators which is exercised within the gallery seems to become gradually enlarged. In reality, it is true that the curatorial influence cannot be ignored more than ever for appear in various fields their new features made from their professional cometence. The function of gallery is more strengthened and its position is more heightened than those in 80s. For these reasons, the curators whose playground is the gallery, they may be regarded as invisible power to the artists. Futhermore, their influence as such seems to be more likely because our world of art does not still have any reliable system of art criticism. Nevertheless, considering the actual situation in which national and public galleries as cultural institution would rather exist on the local sentiments or political dynamics than on autonomy, there must be some restrictions for the galleries and the curators to obtain the power. In this context, the actual moment is looked upon as transitional period to make the curatorship settled down. Before discussing the power relevant to curatorship, we are going to examine first the role and function of curator and then the new curatorial role and function at the age of information. Finally, we will see in sequence the development and problems of curatorship, the power and dilemmas of curator.

• The Journal of Art Theory & Practice
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• no.3
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• pp.67-84
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• 2005

Since the evaluation of its intellectual activities and abilities is done by curator's capabilities, planning exhibition is very important as the final result achieved by their own knowledge, information, and research. ARPA(Advanced Research Project on Arts) is suggested as the system which enables curators responding simultaneously to the society in the times, based on its special characteristics. If this system settles well, which means that the curators at NMCA(National Museum of Contemporary Art, Korea) play their roles as the professionals in each of their fields, the goal of consolidating the status of museum as the representative national museum, and building up competent department of curators, will be achieved at the same time. To clarify above, the curators set up the various assignments of research about the types of arts such as painting, Korean painting, sculpture, installation, new-media, design, craft, photogarphy, architecture, etc. And they establish the art objects classified by the regions, such as the Northern American, Southern American, European, Asian, and other Third World countries. They elaborate art objects more on the history, the work, the artist, and the issue of contemporary art. Furthermore, when the curators devote deeper study to those research subjects, they can have the opportunities to design an exhibition upon the research. Today, the museum of art is 'The Place for Communication and Encounter', it is regarded important to share the aesthetical, creative values with current artists, and to understand mutually with the spectators. It is needed to improve the curator's work, in order to meet the demands of the times and even to advance. Because the form of 'exhibition' is the tool that reveals the identity NMCA aiming at, the motivation, the development, and the realization should be leaded by the curators, who are the mainstream of the museum. ARPA is a system for identifying the exhibition like mentioned above. The main purpose of this system is to produce synergy effect, having the researching, collecting work in liaison with planning exhibition. ARPA will be able to improve the quality of exhibition through the way of developing the exhibition, passing through the stable process in the long run. So far, I have referred to a new paradigm of the exhibition design at NMCA via ARPA. Yet, there still remain missions in reality, such as analyzing the previous exhibition and reshuffling personnel and system, which should be done. When these matters settled, these plans would be suggested practically. At this point, it is the most significant that NMCA is attempting to let others aware of the importance of exhibition planning based on research. when the ARPA and exhibition planning is conjoined together successfully, the competent exhibition will be achieved, which can offer a meaningful exhibition to the art world, strengthen infra structure thru exchanging with public museum in the region, and eventually, establish a network with museum in foreign countries.