• Journal of KIISE:Information Networking
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• v.33 no.3
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• pp.231-246
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• 2006

A server load balancer is used to accept and distribute client requests to one of servers in a wireless internet proxy server cluster. LVS(Linux Virtual Server), a software based server load balancer, can support several load balancing algorithms where client requests are distributed to servers in a round robin way, in a hashing-based way or in a way to assign first to the server with the least number of its concurrent connections to LVS. An improved load balancing algorithm to consider server performance was proposed where they check upper and lower limits of concurrent connection numbers to be allowed within each maximum server performance in advance and apply the static limits to load balancing. However, they do not apply run-time server load information dynamically to load balancing. In this paper, we propose a dynamic load balancing scheme where the load balancer keeps each server CPU load information at run time and assigns a new client request first to the server with the lowest load. Using a cluster consisting of 16 PCs, we performed experiments with static content(image and HTML). Compared to the existing schemes, experimental results show performance improvement in the cases of client requests requiring CPU-intensive processing and a cluster consisting of servers with difference performance.

• Journal of Korea Game Society
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• v.4 no.4
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• pp.11-18
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• 2004

The on-line games in the past were played by only two persons exchanging data based on one-to-one connections, whereas recent ones (e.g. MMORPG: Massively Multi-player Online Role-playings Game) enable tens of thousands of people to be connected simultaneously. Specifically, Korea has established an excellent network infrastructure that can't be found anywhere in the world. Almost every household has a high-speed Internet access. What made this possible was, in part, high density of population that has accelerated the formation of good Internet infrastructure. However, this rapid increase in the use of on-line games may lead to surging traffics exceeding the limited Internet communication capacity so that the connection to the games is unstable or the server fails. expanding the servers though this measure is very costly could solve this problem. To deal with this problem, the present study proposes the load distribution technology that connects in the form of local clustering the game servers divided by their contents used in each on-line game reduces the loads of specific servers using the load balancer, and enhances performance of sewer for their efficient operation. In this paper, a cluster system is proposed where each Game server in the system has different contents service and loads are distributed efficiently using the game server resource information such as CPU utilization. Game sewers having different contents are mutually connected and managed with a network file system to maintain information consistency required to support resource information updates, deletions, and additions. Simulation studies show that our method performs better than other traditional methods. In terms of response time, our method shows shorter latency than RR (Round Robin) and LC (Least Connection) by about 12%, 10% respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.41-49
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• 2010

This paper proposes a new high speed SHA-1 architecture using multiple unfolding and pre-computation techniques. We unfolds iterative hash operations to 2 continuos hash stage and reschedules computation timing. Then, the part of critical path is computed at the previous hash operation round and the rest is performed in the present round. These techniques reduce 3 additions to 2 additions on the critical path. It makes the maximum clock frequency of 118 MHz which provides throughput rate of 5.9 Gbps. The proposed architecture shows 26% higher throughput with a 32% smaller hardware size compared to other counterparts. This paper also introduces a analytical model of multiple SHA-1 architecture at the system level that maps a large input data on SHA-1 block in parallel. The model gives us the required number of SHA-1 blocks for a large multimedia data processing that it helps to make decision hardware configuration. The hs fospeed SHA-1 is useful to generate a condensed message and may strengthen the security of mobile communication and internet service.

• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.409-418
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• 2004

Multicast services are provided on the Internet in fast increasing . Therefore it is important to keep security for multicast communication. Member leaving is deeply associated with scalability problem for group key management. If one member of the group is removed, new group key has to be generated and distributed to all remaining members of group. Minimizing the number of messages and operation cost for generation of the composite keys are important evaluating criteria of multicast key management scheme since generation and distribution of new keys for rekeying require expensive operation. Batch removal can reduce these important parameters rather than removing members sequentially In fashion one after another. In this paper, Hamming distance is calculated between eve교 members to be removed. The members with Hamming distance less than threshold are selected for rekeying procedure. With running the round assignment algorithm In the case of removing several members simultaneously, our model has advantages of reducing the number of message and operation cost for generation of the composite keys and eliminating possibility of collusion attack for rekeying.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.2 s.302
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• pp.1-10
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• 2005

The current implementation of TCP for the Internet is not efficient when used for Mobile Ad hoc Networks (MANENTs). This is because TCP assumes that all packet losses are caused by congestion, whereas transmission errors are a main reason for packet losses in wireless networks. To remedy this situation and increase performance, we propose an end-to-end method of using propagation delays and the differences between propagation delays to distinguish the causes for packet losses. The proposed method has two characteristics: Firstly, it is energy-efficient because this solution is only initiated when a packet loss is detected. Secondly, our approach considers only the one way propagation delay and is more accurate in determining causes for packet losses than existing methods which consider round trip time. Petri net models of the proposed TCP and of the standard TCP have been built and simulations have been performed on them. Our simulation results show that the proposed approach increases throughput and reduces propagation delay compared with standard TCP.

• Journal of Acupuncture Research
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• v.24 no.3
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• pp.187-196
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• 2007

Objectives : This study was designed to evaluate the effect of Moxa Pellet therapy on chronic low back pain. Methods: Subjects were voluntarily recruited by newspapers and internet. The Moxa Pellet therapy was performed for 4 weeks. Patients were randomized to three groups: Moxa Pellets, Control-l and Control-2 group. Moxa Pellets group administered with Moxa Pellets, Control-l group administered with moxa pellet-shaped moxa pellet without available components and Control-2 group administered with round bonded fabric that could not give pressing stimulation. Acupuncture points used in this study were $GV_3$, $BL_{23}$, $BL_{24}$, $BL_{25}$ and $BL_{22}$. The patient's symptoms were assessed before and after 4 weeks treatments by VAS, SF-MPQ and SF- 36. Results : The results are follows; 1. VAS score showed significant difference in Moxa Pellet group and Control-l group after treatment. 2. SF-MPQ score showed significant difference only in Moxa Pellet group. 3. Moxa Pellet group showed significant difference in PF, RE, MR, and BP of SF- 36 score after treatment; Control-l group showed no significant difference; Control-2 group showed significant difference in BP. There were no significant difference among the groups. Conclusions : This study suggests that Moxa Pellet therapy can be applicable to improve symptoms in the patients with chronic low back pain. Further studies on the Moxa Pellet therapy and other treatment in the patients with chronic low back pain is recommended.

• Journal of the Korean Society of Costume
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• v.56 no.7 s.106
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• pp.42-53
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• 2006

The purpose of this research is to study doll's symbolism representing our social culture and the characteristics of clothing design. The ball joint doll was selected, that are pretty much resembled to human body in terms of facial expression, body proportion, joint movement, etc. Results of research are summarized as follows: the ball joint doll is indicated a doll whose joints are free to move with a round shaped joint, which originated by Yochilya simon, who adopted German Hans Bellmer's method.'rho ball joint doll, first, there appeared state of human isolation due to the material civilization and industrial revolution, and trend of adhering to one's own world made human possess dolls. Second, according to the doll play became a representing play culture among Kidult culture, dolls, that are resembled with human being, were recognized as personalized objects. Third, along of expanding digital culture that makes easy to exchange information via Internet, so, ball joint doll market is growing fast, for which various levels of mania are being formed. Take a look at the doll fashion in modern society. In accordance to form of Look, it is largely categorized Young Casual look, Office look, Ethnic look and Military look. When take a look at design specialty, young casual look was presented as a comfortable silhouette and also made of elastic materials and expressed vivid bright tones. Office look image was expressed as a suit of jacket with skirt, and cotton wool polyester materials and acro-matic colors. Ethnic look was represented by Japanese traditional dress and Chinese traditional clothing. The Military look was generally emphasized army uniforms of straight silhouette and shoulder straps.

• Journal of the Korean Society of Costume
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• v.66 no.8
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• pp.98-108
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• 2016

Knitwear has been used as an active and functional clothing item due to its flexible and soft nature. Diverse design expressions have made knitwear into an essential fashion item for people today, who are constantly seeking for ways to display their individualism. The purpose of this study is to analyze the actual wearing conditions, and the preferred designs of knitwear for female college students in order to provide a baseline data, which can be used to develop knitwear designs for the subjects of the study. Survey by questionnaire of 135 female college students in 3 universities in Seoul were analysed. The results of the study are as follows: First, the most owned knitwear were sweaters and cardigans. Knitwear was viewed as soft and warm, as well as versatile. It was not restricted to certain sizes, and was comfortable to wear for different activities. Seound, the most preferred items were sweaters and cardigans. The most preferred styles were round neckline sweaters and open V-neckline cardigans. Third, the most preferred designs were plain designs with achromatic colors and wool-blended fabrics. The most preferred images were simple images. The most preferred fit was loose enough for little bit of room inside. Fourth, appropriateness and design of the knitwear were assessed during the purchasing stage. the most preferred method of purchase was purchasing via online stores after researching the knitwear through various channels, such as store visits and the Internet. The preferred price of knitwear was below 100,000 KRW. Fifth, the most common complaints were as follows: changes in the shape and quality of the knitwear after a wash, appearance of nap, and loose threads. In short, it is necessary for female college students to develop high quality knitwear with designs that can display individuality, while being simple.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.631-636
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• 2007

Promotion websites of companies have several advantages: They can publicize the brand image in various ways by using the character of web environment; they enable consumers to learn the information of products in the round with interests; they can stretch out their marketing targets to the whole world. In order to make an effective delivery of their information in such promotion websites, interaction with their consumers is an important factor, for which understanding Interactive Storytelling is essential. The purpose of this thesis is to study Interactive Storytelling which enables us to have effective interaction with consumers in making promotion websites of companies. For this, this thesis analyzes examples of Interact Storytelling focused on it have story promotion websites on the basis of the five steps for internet marketing promotions: attraction of visitors, attraction of interests and participations, acquisition of the information of customers, grasp of the needs of customers, and an offer of values classified by customers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1194-1201
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• 2003

Measurements of network traffic have shown that self-similarity is a ubiquitous phenomenon spanning across diverse network environments. We have advance the framework of multiple time scale congestion control and show its effectiveness at enhancing performance for fast TCP prototype control. In this paper, we extend the fast TCP prototype control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of fast TCP prototype is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. We explicate out methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under self-similar traffic conditions. We discuss issues arising in comparative performance evaluation under heavy-tailed workload. workload.