• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8B
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• pp.739-746
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• 2004

An ATM/AAL2 is standardized to transmit delay sensitive application services, which has small size packet, efficiently. An AAL2 transmission scheme is used to deliver voice and data traffic on the lob interface between base station (Node-B) and Radio Network Controller (RNC) in UMTS network. To predict AAL2 performance, a detailed end-to-end UMTS network performance simulator was developed. We performed detailed simulation(cell packing density and bandwidth gain) for voice and data services in UTRAN. The results indicate that the maximum bandwidth gain in Node-B is about 17% and the bandwidth gain of AAL2 multiplexing in $I_{ub}$ for data services is less than that for voice service. Futhermore, the more offered load increase the more the bandwidth gain decreases in a concentrator.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.4
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• pp.48-53
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• 2001

A three-stage low noise amplifier(LNA) for the Base-station of the IMT-2000 is designed and implemented. In the first stage, a GaAs HJt-FET which has good noise characteristics is made use of. Monolithic microwave integrated circuits(MMICS) are used in the second and the third stage to achieve both the high gain and high output power. Although the balanced amplifier is used to reduce the input VSWR, it is done only in the first stage because we have to minimize the noise figure attributed to the phase difference of the balanced amplifier. It is shown that the implemented LNA has the gai over 39.74dB, the gain flatness less than ±0.4dB, the noise figure below 0.97dB, input and output VSWRs less than 1.2, and OIP₃(output third order intercept point) of 38.17dBm in the operating frequency range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6B
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• pp.736-745
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• 2001

차세대 이동통신 시스템은 고속의 멀티미디어 데이터의 신뢰성 있는 전송을 요구하고 다양한 전파환경에서 신뢰성 있는 음성, 데이터, 영상서비스 등의 다양한 서비스를 제공한다. 하지만 광대역 무선 접속을 지원하는 다중 접속 기술은 DS-CDMA(Direct Sequence Code Division Multiple Access) 시스템에서 시스템 성능을 저하시키는 심벌간 간섭(ISI) 혹은 다중접속간섭(MAI) 신호를 발생시킨다. 이러한 간섭 신호를 개선하기 위해 적응 블라인드 등화 방식을 사용하는데 적응 블라인드 등화 방식 중에서도 가장 많이 이용하는 Constant Modulus Algorithm(CMA)을 적절한 초기화 없이 사용하면 ill-convergence 현상이 나타난다. 본 논문에서는 채널의 효율을 높이기 위한 등화 방식으로 기존의 NCMA 알고리듬을 이용한 새로운 블라인드 등화 방식(Modified NCMA)을 제안하고, 이를 비동기 DS-CDMA 시스템의 다중 사용자 환경에서 컴퓨터 모의 실험 및 성능분석을 하였다. 제안한 등화 방식의 자승오차(SE : Squared Error)의 개선은 spreading gain 31과 127에 대해 cell 내의 사용자가 10명일 때 약 17dB 정도이고, 사용자가 15, 25명으로 증가시킴에 따라 자승오차의 개선은 각각 20dB, 15dB 정도로 전체 평균 자승오차는 약 17.3dB 정도로 개선됨을 확인할 수 있었다.

• Fisheries and Aquatic Sciences
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• v.22 no.8
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• pp.17.1-17.9
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• 2019

Bacillus is a diverse genus consisting of more than 200 species with extensive genetic diversity. Their beneficial effects in industrial shrimp farming have been well documented. However, little is known about the biodiversity of the Bacillus spp. in this aquaculture system. Taxonomic analysis by 16S rRNA sequencing does not always allow species-level identification of Bacillus spp. In this study, 26 Bacillus isolates from two industrial Litopenaeus vannamei shrimp ponds in Bac Lieu Province, Vietnam, were analyzed for their genetic diversity by multi-locus sequence typing (MLST). A total of 22 sequence types were identified and segregated into four distinct clusters, corresponding to B. subtilis, B. velezensis, B. siamensis, and B. licheniformis. Bacillus subtilis and B. velezensis accounted for more than 73% of the Bacillus isolates. Notably, the MLST scheme exhibited high discriminatory power and might be further simplified to be a convenient method to identify species of the genus Bacillus.

• Journal of Nutrition and Health
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• v.35 no.1
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• pp.37-44
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• 2002

The purpose of this study was to provide a reference range for plasma homocysteine and to explore the relation between plasma homocysteine and nutritional indexes in a Korean college women. Thirty women were selected from college students in Seoul area With mean age of 22.4y. Dietary intakes of Vitamins B$_{6}$, B$_{12}$, folate were estimated from a 3 day food diary method and plasma homocysteine concentration was mearsured as well as the levels of blood vitamins. The results obtained are as follows. Mean daily intake of energy, vitamin B$_{6}$, B$_{12}$, and folate were 1731.9kcal, 0.9mg, 2.2mg and 139.8$\mu\textrm{g}$ respectively. Mean plasma homocysteine concentration was 12.4$\mu$mol/l with a range between 6.7 and 17.8$\mu$mol/l and the mean concentrations of plasma vitamin B$_{6}$(PLP), serum vitamin $_{12}$, Serum folate and RBC folate were 77.5nmol/l, 267.4pmol/l, 17.1 nmol/l and 736.5nmol/l arid 736.5nmol/l respectively. we found a negative correlation between plasma homocysteine concentration and dietary vitamins, and blood levels of vitamin although it was not significant.

• Journal of Welding and Joining
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• v.22 no.5
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• pp.53-57
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• 2004

Friction stir weldability of AZ31B-H24, AZ61A-F and AZ91C-F Mg alloys were studied using microstructural observation and mechanical tests. The microstructure of stir zone(SZ) was coarse in AZ31B-H24 alloy whereas it was very fine both in AZ61A-F and AZ91C-F alloys. The hardness of SZ was remarkably increased by very fine recrystallized grains both in AZ61A-F and AZ91C-F alloys. On the other hand, the hardness of SZ was decreased in AZ31B-H24 due to the coarse microstructure. In SZ, AZ91C-F alloy showed very high hardness values because of dispersion hardening of $Mg_{17}$Al$_{12}$($\beta$ phase) and Al solid solution hardening. Because of more $Mg_{ 17}Al_{12}($\beta$ phase)$ intermetallic compounds, Mg alloy with high Al content showed poor mechanical properties.s.

• Kyungpook Mathematical Journal
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• v.54 no.4
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• pp.677-684
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• 2014

In the theory of hypergeometric functions of one or several variables, a remarkable amount of mathematicians's concern has been given to develop their transformation formulas and summation identities. Here we aim at generalizing the following transformation formula for the Exton's triple hypergeometric series $X_{12}$ and $X_{17}$: $$(1+2z)^{-b}X_{17}\;\left(a,b,c_3;\;c_1,c_2,2c_3;\;x,{\frac{y}{1+2z}},{\frac{4z}{1+2z}}\right)\\{\hfill{53}}=X_{12}\;\left(a,b;\;c_1,c_2,c_3+{\frac{1}{2}};\;x,y,z^2\right).$$ The results are derived with the help of two general hypergeometric identities for the terminating $_2F_1(2)$ series which were very recently obtained by Kim et al. Four interesting results closely related to the Exton's transformation formula are also chosen, among ten, to be derived as special illustrative cases of our main findings. The results easily obtained in this paper are simple and (potentially) useful.

• Journal of fish pathology
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• v.22 no.3
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• pp.391-400
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• 2009

Genetic identification of 17 fish-derived Aeromonas strains was attempted using 5 housekeeping genes. 16S rRNA, gyrB, rpoD, dnaJ and recA genes from the 17 strains were amplified, and total of 85 amplicons were sequenced. DNA sequences of the strains and type strains of the 17 Aeromonas homology groups were used for genetic identification and phylogenetic analyses. None of the strains was identified as a single species using the 16S rRNA gene, showing the same identities (average = 99.7%) with several Aeromonas species. According to gyrB, rpoD, dnaJ, and recA, 9 strains and RFAS-1 used in this study were identified as A. hydrophila and A. salmonicida, respectively. However, the other strains were closely related to 2 or more Aeromonas species (i.e., A. salmonicida, A. veronii, A. jandaei, A. media and A. troda) depending on the genetic marker used. In this study, gyrB, rpoD, dnaJ and recA gene sequences proved to be advantageous over 16S rRNA for the identification of field Aeromonas isolates obtained from fish. However, there are discrepancies between analyses of different phylogenetic markers, indicating there are still difficulties in genetic identification of the genus Aeromonas using the housekeeping genes used in this study. Advantages and disadvantages of each housekeeping gene should be taken into account when the gene is used for identification of Aeromonas species.

• Journal of fish pathology
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• v.35 no.2
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• pp.241-246
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• 2022

White spot syndrome virus (WSSV) is a prevalent and virulent pathogen affecting cultured whiteleg shrimp (Litopenaeus vannamei) in Korea. In this study, seven monoclonal antibodies (mAbs) (10A12, 16C3, 17G4, 21G5, 22C4, 23B6 and 24G6) were produced by using purified WSSV. The reactivity of these mAbs was analysed by Western blot (WB), indirect immunofluorescence (IIF), and lateral flow immunochromatographic assay (LFIA). WB analysis demonstrated that three mAbs (17G4, 22C4, and 23B6) reacted specifically to VP28 with an approximate molecular weight of 24 kDa, mAb 16C3 reacted with approximately 17 kDa. IIF analysis demonstrated specific fluorescence signals on gill tissues of WSSV-infected shrimp, with five mAbs (10A12, 16C3, 22C4, 23B6, and 24G6), pleopods from WSSV-infected shrimp were used for LFIA, where, two mAbs (21G5 and 22C4) exhibited positive reaction. In conclusion, it can be inferred that the mAbs usage and specificity depends on the nature of assay used for diagnosis.

• International Journal of Oral Biology
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• v.35 no.1
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• pp.13-19
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• 2010

The DNA probes Pn17 and Pn34 were evaluated for their ability to specifically detect clinical strains of P. intermedia and P. nigrescens from a Korean population by dot blot hybridization. These probes were sequenced by extension termination and their specificity was determined by Southern blot analysis. The results revealed that the Pn17 sequence (2,517 bp) partially encodes an RNA polymerase beta subunit (rpoB) and that Pn34 (1,918 bp) partially encodes both rpoB (1-169 nts) and the RNA polymerase beta subunit (rpoB'; 695-1918 nts). These probes hybridized with both HindIII- and PstI-digested genomic DNAs from the strains of P. intermedia and P. nigrescens used in this study. Interestingly, each of the hybrid bands generated from the HindIII-digested genomic DNAs of the two bacterial species could be used to distinguish between them via restriction fragment length polymorphism. These results thus indicate that Pn17 and Pn34 can simultaneously detect P. intermedia and P. nigrescens.