• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.517-525
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• 2010

The IPTV Service provides various interactive services beyond the level of being able to substitute cable TV. The IPTV system is to be decentralized gradually in which one server conducts all tasks. Primarily, deliberation of media needs to be changed into a system in which relayer and peer from the central server is utilized. Secondarily, the way of controling IPTV network need to be decentralized. Unlike the current client-server system, P2P(Peer To Peer), the main technology of decentralized IPTV is able to provide a service by cooperation of each node. Dealing with live streaming IPTV system which is based on the P2P protocol, this paper design the pure P2P IPTV structure and does verify the performance of P2P IPTV structure by realizing real system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.451-457
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• 2006

A peer-to-peer(P2P) network is inherently vulnerable to malicious attacks from participating peers because of its open, flat, and autonomous nature. This paper addresses the problem of effectively defending from active attacks of malicious peers at bootstrapping phase and at online phase, respectively. We propose a secure membership handling protocol to protect the assignment of ID related things to a newly joining peer with the aid of a trusted entity in the network. The trusted entities are only consulted when new peers are joining and are otherwise uninvolved in the actions of the P2P networks. For the attacks in online phase, we present a novel message structure applied to each message transmitted on the P2P overlay. It facilitates the detection of message alteration, replay attack and a message with wrong information. Taken together, the proposed techniques deter malicious peers from cheating and encourage good peers to obey the protocol of the network. The techniques assume a basic P2P overlay network model, which is generic enough to encompass a large class of well-known P2P networks, either unstructured or not.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.897-900
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• 2008

Various sequences of pH change were applied in a batch bioreactor to investigate pH shock effects on geldanamycin production by Streptomyces hygroscopicus subsp. duamyceticus JCM4427. In the control culture where the pH was not controlled, the maximum geldanamycin concentration was 414 mg/l. With the pHS1 mode of pH shock, that is, an abrupt pH change from pH 6.5 to pH 5.0 and then being maintained at around pH 5.0 afterward, 768 mg/l of geldanamycin was produced. With pHS2, in which the pH was changed sequentially from pH 6.7 to pH 5.0 and then back to pH 6.0, 429 mg/l of geldanamycin was produced. With pHS3 having a sequential pH change from pH 6.0 to pH 4.0 and then back to pH 6.5 followed by the third pH shock to pH 5.5, no geldanamycin production was observed. Considering that the productivity with pHS1 was about two-fold of that of the control culture with no pH control, we concluded that a more sophisticated manipulation of pH would further promote geldanamycin production.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.25-33
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• 2013

P2P(Peer-to-Peer) architecture can reduce the network bandwidth and resource on the server since peers exchange data chunks with each other, while server-client architecture causes a lot of traffic on the server. Peers receive a data more reliably when the number of participating peer increases. Currently, P2P traffic has accounted for about 65% of the world's Internet traffic and diverse P2P streaming services have launched combining to video streaming technology. However, the requirements and data chunk delivery algorithms for mobile P2P streaming service should be investigated, since the existing P2P technologies have been developed and designed for the wired network. In particular, the bandwidth fluctuation caused by user mobility, wireless packet collisions, and packet losses brings about different problems on the mobile P2P streaming service compared to existing P2P streaming service. In this paper, we analyzed the problem of mobile P2P streaming services in the 802.11n wireless LAN environment through experiments.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1129-1134
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• 2001

In the point of the Eco-concrete(Environmentally Friendly Concrete), it is very important to reduce the pH of high porous concrete by the pH to be able to grow plants, because the pH of concrete is l1~13. But the method of measuring the pH of high porous concrete is not well-defined, yet. Therefore, first, this paper report the method of measuring the pH of high porous concrete. Secondly this paper reports the pH reduction of high porous concrete to grow plants.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.2
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• pp.37-45
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• 2015

The technology development of MANET and dissemination of P2P services has been made very widely. In particular, the development of many application services for the integration of P2P services in MANET has been made actively. P2P networks are commonly used because of the advantages of efficient use of network bandwidth and rapid information exchange. In P2P network, the infrastructure managing each node in the middle does not exist and each node is a structure playing a role as the sender and receiver. Such a structure is very similar to the structure of the MANET. However, it is difficult to provide reliable P2P service due to the high mobility of mobile nodes. In this paper, we propose location-based routing technique in order to provide efficient file sharing and management between nodes. GMN managing the group is elected after network is configured to the area of a certain size. Each node is assigned an identifier of 12 bit dynamically to provide routing which uses location information to the identifier. ZGT is managed in the GMN in order to provide management of group nodes and distributed cache information. The distributed cache technique is applied to provide a rapid retrieval of the sharing files in the each node. The excellent performance of the proposed technique was confirmed through experiments.

• Journal of Microbiology
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• v.44 no.5
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• pp.530-536
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• 2006

Bacteriophage P4, a satellite phage of coliphage P2, is a very useful experimental tool for the study of viral capsid assembly and cos-cleavage. For an in vitro cos-cleavage reaction study of the P2-P4 system, new shortened and selectable markers containing P4 derivative plasm ids were designed as a substrate molecules. They were constructed by swapping the non-essential segment of P4 DNA for either the kanamycin resistance (kmr) gene or the ampicillin resistance (apr) gene. The size of the genomes of the resulting markers were 82% (P4 ash8 delRI:: kmr) and 79% (P4 ash8 delRI:: apr) of the wild type P4 genome. To determine the lower limit of genome size that could be packaged into the small P4-size bead, these shortened P4 plasmids were converted to phage particles with infection of the helper phage P2. The conversion of plasmid P4 derivatives to bacteriophage particles was verified by the heat stability test and the burst size determination experiment. CsCl buoyant equilibrium density gradient experiments confirmed not only the genome size of the viable phage form of shortened P4 derivatives, but also their packaging into the small P4-size head. P4 ash8 delRI:: apr turned out to be the smallest P4 genome that can be packaged into P4-sized head.

• Journal of dental hygiene science
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• v.12 no.4
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• pp.335-341
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• 2012

This study conducted a survey targeting at dental hygienists working in medical institutions located in Daegu, Pusan, Ulsan Metropolitan City and Gyeongnam and Gyeongbuk Province from July 18th to August 26th 2011, in order to study factors which affect radiation safety management behaviors and improve levels of those behaviors. The results of this study are as follows. 1. There were significant differences in radiation safety management knowledge of dental hygienists, according to service institutions (p<.001), the current state of defense facilities (p<.006) and the necessity for safety management education (p<.012). 2. There were significant differences in radiation safety management attitudes, according to age (p<.014), service institutions (p<.003), work experience (p<.009), educational level (p<.002), the current state of defense facilities (p<.015), the necessity for safety management education (p<.005) and the intention to take part in the education (p<.036). 3. There were significant differences in radiation safety management behaviors, depending on experience in safety management education (p<.068), measurement of exposed dose (p<.010), the state of defense facilities (p<.001). 4. There were statistically positive correlations between radiation safety management knowledge and attitude, and between radiation safety management attitude and behavior (p<.05). 5. The regular measurement of exposed dose (p<.046) and the present state of defense facilities (p<.001) were found to be factors to affect radiation safety management behaviors. In conclusion, it is considered that building perfect defense facilities of radiology rooms and measuring the exposed does of dental hygienists on a regular basis to alert them to the danger of radiation is considerably important to improve radiation safety management behaviors.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.3
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• pp.178-184
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• 1992

Five varieties of silage corn were cultivated to compare the growth characteristics and productivity. Corn varieties were Pioneer 3144(P 3144), 3160(P 3160), 3282(P 3282), 3352(P 3352) and Suweon 19 (S 19). The corns were seeded on May 2 and harvested on August 15, and measured the plant height, leaf length, leaf width, stem diameter, and yields of fresh and dry matter. The results obtained were as follows: 1. Plant height of P 3352 and P 3144 grown about 280cm throughout the experimental period was the tallest(P<.Ol), and those of P 3160, P 3282 and Suweon 19 ranged from 246.3 to 256.0 cm. 2. Leaf length is the longest in P 3352 and the shortest in P 3282(97.63cm vs 84.17cm), and there was significant(P<.Ol) difference between corn varieties. 3. Stem diameter was the longest in P 3144 and the shortest(P<.Ol) in P 3352(3.28cm vs 2.66cm). 4. P 3144, P 3282 and P 3352 had the greatest(P<.Ol) fresh matter yields per 10a in leaf, stem, and ear and whole plant, respectively. 5. Dry matter yield of P 3282 was the greatest(P<.Ol) in stem(1,080.6 kg/lOa) and leaf(304.5 kg/lOa), and that of P 3352 was the greatest in ear(864.1 kg/lOa) and whole plant yield(2,021 kg/lOa). 6. Ratios of respective part of corn to total dry matter were ranged from 12.7 to 17.8 76 for leaf, 44.5 to 66.9% for stem and husks, and 16.9 to 42.8 % for ear, and the highest in P 3160, P 3160 and P 3352, respectively. Consequently, P 3352, P 3144 and P 3282 shown high productivity in dry matter yield could be recommended as a reliable corn varieties for silage.

• The KIPS Transactions:PartC
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• v.18C no.1
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• pp.51-60
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• 2011

In this paper, we propose a P4P based P2P system for live multimedia streaming services. In order to satisfy the strict requirement of delay in live multimedia streaming, in the proposed scheme, the P4P server of network provider provides the network status information related to delay and congestion links to P2P system in addition to the information to optimize the network resource utilization. The P2P system server, then, makes the peering suggestion based on the information from the network server. Also, we propose a playback synchronization mechanism that enable each peer to start the playback within the limited variation from the playback positions of source peer. Through the simulation results, it is shown that the proposed scheme not only deals with the original objective of the P4P framework, i.e., effective network utilization, but also the live multimedia streaming requirements. It enhances the playback continuity, and reduces the playback start-up latency and the control overhead. In addition, the proposed scheme reduces the variation in playback positions of the peers.