• 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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.163-170
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• 2009

Several species of the genus Pseudo-nitzschia produce the neurotoxin domoic acid (DA) known to be responsible for amnesic shellfish poisoning. In spite of the potentially toxic effects on marine ecosystem, even the representative Pseudo-nitzschia species occurring in Korean coastal waters have not been clearly reported. Plankton samples from several outer coastal sites of Tongyeong were collected fortnightly from May to November 2008 and the presence of diatoms of the genus Pseudo-nitzschia was examined using light and scanning electron microscopy. Thirteen species were observed, including P. americana, P. brasiliana, P. caciantha, P. calliantha, P. cuspidata, P. delicatissima, P. micropora, P. multiseries, P. multistriata, P. pseudodelicatissima, P. pungens, P. subfraudulenta, and P. subpacifica. The number of Pseudo-nitzschia species observed were only four in May, which was minimum during this survey, and then gradually increased attaining maximum, twelve, in September. After September it began to decrease again and got to five in November. Of these, P. americana, P. brasiliana, P. caciantha, P. calliantha, P. micropora, and P, pseudodelicatissima are new records for the Korean coastal waters and P. calliantha, P. cuspidata, P. delicatissima, P multiseries, P. multistriata, and P. pungens have been reported as DA producers around the world, but the potential toxicity of these species was not ascertained in Tongyeong area.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.689-695
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• 2003

The purpose of this study is to evaluate and to predict of eutrophication in lakes by using Vollenweider-OECD model and total phosphorus concentration and inflow rate which were measured in 1993∼2001. The results of study were as follows. The annual total phosphorus loading from the watershed was calculated to be 55∼195tP/yr at lake Soyang, 221∼466tP/yr at lake Taechong, 123∼278tP/yr at lake Andong, 57∼109tP/yr at lake Seomjin. These are discharged, far the most parts, from population and fishfarm facility. TP loading on the surface area at lake Soyang was 3.01gP/㎡/yr, 2.82gP/㎡/yr, 2.84gP/㎡/yr, 3.03gP/㎡/yr, 2.34gP/㎡/yr, 1.78gP/㎡/yr, 0.91gP/㎡/yr, 0.89gP/㎡/yr, 0.86gP/㎡/yr, lake Taechong was 6.71gP/㎡/yr, 7.25gP/㎡/yr, 7.24gP/㎡/yr, 6.53gP/㎡/yr, 6.50gP/㎡/yr, 7.06gP/㎡/yr, 7.04gP/㎡/yr, 4.05gP/㎡/yr, 3.44gP/㎡/yr and TP loading on the surface area of lake Andong, lake Soemjin were 5.39gP/㎡/yr, 4.47gP/㎡/yr, 4.56gP/㎡/yr, 4.45gP/㎡/yr, 3.33gP/㎡/yr, 2.38gP/㎡/yr, 2.53gP/㎡/yr, 2.46gP/㎡/yr, 2.54gP/㎡/yr, 4.09gP/㎡/yr, 4.10gP/㎡/yr, 3.98gP/㎡/yr, 3.73gP/㎡/yr, 2.80gP/㎡/yr, 3.46gP/㎡/yr, 3.22gP/㎡/yr, 2.19gP/㎡/yr, 2.13gP/㎡/yr respectively. The tropic states of four lakes can be assessed as eutrophy because phosphorus leading exceeds the critical phosphorus loading by Vollenweider-OECD model.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.15-20
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• 1990

A laboratory experiment was conducted to investigate the relationship between the composition of phosphorus forms and soil chemical properties. The soil samples were collected from the farms of the 149 locations where vegetables were intensively cultivated with heavy application of phosphorus. The composition percentages of Ca-P and Saloid-P to the total phosphorus were increased as increasing soil pH while those of Fe-P and Al-P were decreased, The composition percentage of Fe-P were increased up to pH 5.0-6.0 and decreased as increasing pH above 6.0. respectively. The pH dependency of Al-P and Fe-P composition percentage was more remarkable for the soils with high available phosphorus (>500ppm) than with low available phosphorus (<500ppm). Composition percentages were in order of Fe-P>Al-P>Ca-P>Saloid-P for the soils with available phosphorus below 500ppm, while those were in order of Al-P>Fe-P>Ca-P>Saloid-P for the soils with high available phosphorus above 1,000ppm. Composition percentages of Al-P and Fe-P were increased as increasing active Al content, and Fe-P was increased as increasing of active Fe and P sorbed but saloid-P, Al-P and Ca-P were decreased.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.1-6
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• 2015

The term "P2 sir-associated helper inefficiency" has been used to define the inefficient helper capability of P2 sir mutants for their satellite bacteriophage P4. The aim of this study was to investigate the factors overcoming P2 sir-associated helper inefficiency. At first, we verified whether the P2 cos region containing P4 sid71 cosP2 could overcome P2 sir-associated helper inefficiency with P2 sir3. The result was that P4 sid71 cosP2 could not overcome P2 sir-associated helper inefficiency with P2 sir3. Instead of cos region of P2, the size of the DNA packaged into a $P2_{sir}$-sized head seems to be important for overcoming P2 sir-associated helper inefficiency. In the present work, three kinds of P4 derivatives with packaged DNA sizes between those of P4 ost1 and P4 ost2, were constructed through DNA manipulation. In one P4 derivative, P4 sid71 delRI::apr, the size of the packaged DNA was identified with a CsCl buoyant equilibrium density gradient experiment. According to the burst sizes of the P4 derivatives, they could overcome P2 sir3-associated helper inefficiency. The size of the P4 derivative DNA suitable for packaging into a $P2_{sir3}$-sized head was 28-29 kb.

• The Plant Pathology Journal
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• v.15 no.4
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• pp.228-235
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• 1999

Genetic diversity of ninety-five Korean isolates of Phytophthora was investigated on the basis of PCR-RFLP of ribosomal DNA. The isolates were previously identified as following fifteen species by mycological and cultural characteristics; P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamoni, P. citricola, P. citrophthora, P. cryptogea, P. drechsleri, P. erythroseptica, P. infestans, P. megasperma, P. nicotianae, P. palmivora and P. sojae. The regions of small subunit (SSU) and internal transcribed spacer (ITS) of rDNA were amplified with primer pair, NS1 and ITS4, by polymerase chain reaction (PCR) and digested with nine restriction enzymes. P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamomi, P. citricola, P. citrphthora, P. infestans, P. nicotianae and P. palmivora showed specific band patterns for each species. However, P. sojae and P. erythroseptica presented identical band patterns and P. cryptogea, P. drechsleri and P. megasperma were divided into six groups, which were not compatible with delineation of the species. A group originated from cucurbits showed distinct band patterns from other groups, but the other five groups were closely related within 96.0% similarity, forming one complex group. Consequently, Korean isolates of Phytophthora were divided into thirteen genetic groups and each group was readily differentiated by comparing digestion patterns of AvaII, HaeIII, MboI, HhaI and MspI. Therefore, PCR-RFLP of rDNA using the five enzymes can be used to differentiate or identify the Phytophthora species reported in Korea so far.

• The Journal of Society for e-Business Studies
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• v.23 no.3
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• pp.207-224
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• 2018

In this article, an empirical study was conducted by using public dataset from Lending Club Corporation, the largest online peer-to-peer (P2P) lending in the world. We explore significant predictor variables related to P2P lending default that housing situation, length of employment, average current balance, debt-to-income ratio, loan amount, loan purpose, interest rate, public records, number of finance trades, total credit/credit limit, number of delinquent accounts, number of mortgage accounts, and number of bank card accounts are significant factors to loan funded successful on Lending Club platform. We developed online P2P lending default prediction models using discriminant analysis, logistic regression, neural networks, and decision trees (i.e., CART and C5.0) in order to predict P2P loan default. To verify the feasibility and effectiveness of P2P lending default prediction models, borrower loan data and credit data used in this study. Empirical results indicated that neural networks outperforms other classifiers such as discriminant analysis, logistic regression, CART, and C5.0. Neural networks always outperforms other classifiers in P2P loan default prediction.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.545-552
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• 2007

P3P(Platform for Privacy Preference) that is used in the World Wide Web is a standard to define and negotiate policies about definition, transmission, collection, and maintenance of personal information. Current P3P standard provides methods that define client personal information protection policy and P3P policy associated with web server. It also provides a method that compares these two policies. The current P3P standard, however, does not handle detail functions for safe transmission of the personal information and data. Also, it does not handle problems that can be induced by the detail functions. In this paper, in order to solve these problems, we propose a Secure P3P(S-P3P) protocol, which is a security protocol for the current P3P standard, offers mutual authentication between the web server and the client, and guarantees integrity and confidentiality of the messages and data. Furthermore, a S-P3P protocol provides non-repudiation on transmission and reception of personal information that is transmitted from the client to the web server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.659-669
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• 2010

The P2P IPTV will create a new paradigm for the Internet services. However, it cannot guarantee the reliability of their server and QoS because of using common Internet users(peers) for SIP server or relay server, though the infrastructural cost is low. This paper proposes the ISP-based P2P IPTV architecture which can solute the limitations of conventional P2P-based IPTV. In this model, ISP can build P2P overlay network with ISP servers and directly manage each server needed for session connection. So, the servers have higher performance and better reliability than previous one. Besides, robustness is improved because each sever is set by P2P overlay network. To evaluate the characteristics of the ISP-based P2P IPTV architecture, we simulate it for some parameters which are end-to-end streaming delay time, connection delay time and traffic amount. We compared the proposed architecture with the conventional P2P architecture about video service and confirmed that the performance of ISP-based P2P IPTV is better than conventional P2P based IPTV.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.651-659
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• 2013

A graph is $s$-regular if its automorphism group acts regularly on the set of its $s$-arcs. In this paper, the cubic $s$-regular graphs of order 12p, 36p, 44p, 52p, 66p, 68p and 76p are classified for each $s{\geq}1$ and each prime $p$. The number of cubic $s$-regular graphs of order 12p, 36p, 44p, 52p, 66p, 68p and 76p is 4, 3, 7, 8, 1, 4 and 1, respectively. As a partial result, we determine all cubic $s$-regular graphs of order 70p except for $p$ = 31, 41.