• Journal of KIISE
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• v.44 no.8
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• pp.767-773
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• 2017

In a distributed system environment, such as a cloud database, the tail latency needs to be kept short to ensure uniform quality of service. In this paper, through experiments on a Cassandra database, we show that long tail latency is caused by a lack of memory space because the database cannot receive any request until free space is reclaimed by writing the buffered data to the storage device. We observed that, since the performance of the storage device determines the amount of time required for writing the buffered data, the performance degradation of Solid State Drive (SSD) due to garbage collection results in a longer tail latency. We propose a garbage collection synchronization technique, called SyncGC, that simultaneously performs garbage collection in the java virtual machine and in the garbage collection in SSD concurrently, thus hiding garbage collection overheads in the SSD. Our evaluations on real SSDs show that SyncGC reduces the tail latency of $99.9^{th}$ and, $99.9^{th}-percentile$ by 31% and 36%, respectively.

• Journal of Korea Multimedia Society
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• v.5 no.6
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• pp.674-682
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• 2002

Nowadays economic and commercial businesses have been increased because of the Internet. As a result of this, electronic commerce is becoming one of the most Interesting topic of discussion. Electronic commerce is equal to a real market, only the place of business is the imaginary space supported by the Internet. There are a few conditions to consider, making electronic commerce work safely. The electronic commerce should be connected by a substantial system and an on-line Protocol. There are some conditions needed for information security, authentication, and payment by electronic currency etc. Although there are many kinds of existing systems, which create services successfully, further research for security is required. Therefore, this paper suggests an authenticated Agent management, which offers more convenience and security than before. Also, this paper shows many authenticated methods for a management system. An Agent that is one of interesting things to study can handle information problems and works related to electronic commerce.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.525-533
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• 2020

In recent years, the VR-interactive action contents industry, which utilizes five senses of human bodies, has continued to grow through areas such as games, tourism, movies, performances and exhibitions, but it has reached to breaking point by unrealistic visual elements. Therefore, the purpose of this study is to analyze the effect of each evaluation factor based on visual immersion of interactive type of VR action contents to overcome the limitations. For this study, firstly, prior research is reviewed. Secondly, the evaluation factors of visual immersion of interactive type of VR action contents and hypothesis are to be derived. Research finding is that there is no difference to recognize proximity, three-dimensionality, visibility and immersion by gender. Also, in order to influence visual immersion, it is important that 3D modeling of characters and objects must be sophisticated to be fit in with their surroundings and lighting. This makes user to be confused where they are actually in.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.3083-3093
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• 2010

The number of Free-Form construction projects are increased by development of 3D parametric modeling technology. The reason of Free-Form Architecture's appearance is advance of digital technology. BIM simulation decision making support is inefficient because it is used in virtual reality. In this study, we developed "AR naviX" which is the digital contents of construction management based on AR for effective decision making support to Free-Form construction project. It reflects construction site by using site picture and video, or Laser scanning data. User feel high reality and is absorbed in augmented reality. So they can reduce the time of decision.

• Journal of Game and Entertainment
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• v.2 no.1
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• pp.78-86
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• 2006

In this paper, we design a ubiquitous home automation system for Korean domestic 33-Pyung Apartment based on USN environment. The core of this home automation system is to give Home the 'Intelligence' so that the house can analyze and memorize the occurrences and react spontaneously on the user requirements by means of the World Model, USN, and LBS etc. Ultimately, the resident of this intelligent home might access all of these ubiquitous environments without any feelings about the equipments and peripherals. The methods of user identification, image recognition, and the ultrasonic sensors locations have been applied to Korean domestic 35-Pyung Apartment, but they will be easily generalized to be an extended model because of the flexibility of the World Model. which are confirmed by the imaginary scenario presented at the end of the main left.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.5
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• pp.257-264
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• 2002

In this paper, we give a detailed description of KDSM(KAIST Distributed Shared Memory) system. KDSM is implemented as a user-level library running on Linux 2.2.13, and TCP/IP is used for communication. KDSM uses page-based invalidation protocol, multiple-writer protocol, and supports HLRC(Home-based Lazy Release Consistency) memory consistency model. To evaluate performance of KDSM, we executed 4 scientific applications and compared the result to JLAJLA. The results showed that performance of KDSM almost equal to JIAJIA for 2 applications and performance of KDSM is better than JIAJIA for 2 applications.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.15-23
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• 2001

It is difficult to figure out the specific contents of the buildings in the internet spatial area, since those data on the internet present only the location of buildings and the outlines of lands on which buildings are located, An experimental study for the view management of building information at internet urban spatial area was conducted on the Web-GIS based map using hyper map. With the building information on the 2-D map, modified from the previous numerical map and the regional building information and additional information, a new form of building through 3-D icons was shown on the internet spatial area. This study shows the Web-based building management system, which is designed to manage attribute data about hyper-linked buildings of 2.5-D icons and to reproduce visual building information by putting a variety of information into hyper-linked icons on the hyper map. This system not only complements the lack of consistency between real buildings and those on the map, but also provides users with more familiar urban space, so that everybody can utilize the building information as long as he has access to the internet.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.446-454
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• 2001

A long-distance education method using the computational environment has been developed and implemented for quite some time. However, there has been some difficulty in the simulation of face-to-face instruction due to limitations in performance of the computers and the networks. Continued development of multimedia technologies has now made it possible to simulate face-to-face instruction, recording the teachers' instructions in the form of a screen dump. In this paper, we propose a system that allows the teacher to make loaming materials available on the Web using Window Media Technology(WMT). This technology also allows remote site users to view the contents at their convenience. A media encoder acquires the lessons and stores them as moving pictures. The lessons are displayed on the screen as the teacher explains them. The learning materials are stored in a Windows media file format, the file is stored on a lecture server and provided to the user using a streaming method in real time. The users can view the contents on the Web without requiring a special player. The proposed system consists of a lecture writer module, a lecture server module and a lecture client module.

• Journal of Korea Multimedia Society
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• v.13 no.7
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• pp.960-972
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• 2010

In this paper, we present a software for placing instruments on stage based on the acoustic properties of the concert hall. In order to simulate the changes in sound depending on the positions of the instruments, we incorporated the idea of location-based reverberation effect which can be realized through the convolution of instrument sounds with the impulse responses from the respective instrument positions. And we developed a software with a real-time convolution engine which enables the user to conveniently simulate the resulting sound of various instrument placements. The software was tested with the impulse response data measured at two concert halls of the National Center for Korean Traditional Performing Arts and Korean traditional instrument sounds. Results of these experiments show that simulated reverberation effects properly represent the spatial placement of instruments on stage.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.271-284
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• 2020

Good reviews that Half-Life: Alyx received created a turning point for the vitalization of the VR market with an uncertain future due to the absence of a revenue model together with the increased sales of VR equipment. Based on previous studies, this study categorized the characteristics of VR games according to graphs, first-person system, interface, controller, interaction technology, sound and stories. The analysis results show that the seven elements corresponded with "interactions" and "virtual images," which represent the completion level of games as part of VR components, and were connected to one another, which led to the proposal of an upper-rank concept "presence" to put them together. "Immersiveness," which represents users' emotions as part of VR components, was analyzed with the immersion theory to assign tasks of proper difficulty level for users' abilities. In the research process, the Delphi technique and FGI were administered to a panel of 15 experts to ensure objectivity. Finally, "presence" and "immersiveness" are characteristics in proportion to each other and can be valid concepts in future analysis of VR games as well as Half-Life: Alyx, which led to the proposal a new concept framework called 'presence effects' by combining the two words.