• Title, Summary, Keyword: selectivity index

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Performance of Convolution Coding Underwater Acoustic Communication System on Frequency Selectivity Index (주파수 선택 지표에 따른 길쌈 부호 수중 음향 통신 시스템의 성능 평가)

  • Seo, Chulwon;Park, Jihyun;Park, Kyu-Chil;Shin, Jungchae;Jung, Jin Woo;Yoon, Jong Rak
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.6
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    • pp.494-501
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    • 2013
  • The convolution code(CC) of code rate 1/2 as a forward error correction (FEC) in Quadrature Phase Shift Keying (QPSK) is applied to decrease bit error rate (BER) by background noise and multipath in shallow water acoustic channel. Ratio of transmitting signal bandwidth to channel coherence bandwidth is defined as frequency selectivity index. BER and bit energy-to-noise ratio gain of transmitted signal according to frequency selectivity index are evaluated. In the results of indoor water tank experiment, BER is well matched theoretical results at frequency selectivity index less than about 1.0. And bit energy-to-noise ratio gain is also matched theoretical value of 5 dB. BER is effectively decreased at frequency selective multipath channel with frequency selectivity index higher than 1.0. But bit energy-to-noise ratio greater than a certain size in terms of CC weaving is effective in reducing bit errors. In the results, the defined frequency selectivity index in this study could be applied to evaluate a performance of CC in multipath channel. Also it could effectively reduced BER in a low speed underwater acoustic communication system without an equalizer.

Estimation of selectivity index and separation efficiency of copper flotation process using ANN model

  • Nuri, Omid Salmani;Allahkarami, Ebrahim;Irannajad, Mehdi;Abdollahzadeh, Aliakbar
    • Geosystem Engineering
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    • v.20 no.1
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    • pp.41-50
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    • 2017
  • Artificial neural network was used to predict the copper ore flotation indices of Separation Efficiency (SE) and Selectivity Index (SI) within different operational conditions. The aim was to predict $SE_{Cu}$ and $SI_{Fe}$ and $SI_{Mo}$ as a function of chemical reagent dosages (collector, frother, modifier), feed rate, solid percentage, and the feed grade of Cu, Fe, and Mo. A three-layered back propagation neural network with the structure of 9-10-10-3 is selected and standard Bayesian regularization was used as a training function in which, it is unnecessary the validation data-set being apart from the training data-set. The advantage of this algorithm is the minimization of weights and linear combinations of squared errors of producing the appropriate network. In the training and testing stages, the quite satisfactory correlation coefficient of 1 for three training outputs and .93, .9, and .88 for testing outputs was achieved. The results show that the proposed approach models can be used to determine the most advantageous industrial conditions for the expected SE and SI in the froth flotation process.

Performance Study of the Index-based Parallel Join

  • Jeong, Byeong-Soo;Edward Omiecinski
    • The Journal of Information Technology and Database
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    • v.2 no.2
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    • pp.87-109
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    • 1995
  • The index file has been used a access database records effectively. The join operation in a relational database system requires a large execution time, especially in the case of handling large size tables. If the indexes are available on the joining attributes for both relations involved in the join and the join selectivity is relatively small, we can improve the execution time of the join operation. In this paper. we investigate the performance trade-offs of parallel index-based join algorithms where different indexing schemes are used. We also present a comparison of our index-based parallel join algorithms with the hash-based parallel join algorithm.

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Antiherpetic Activities of Natural Hesperetin Alone and in Combinations with Acyclovir and Vidarabine (천연 Hesperetin의 항허피스바이러스작용과 Acyclovir 및 Vidarabine과의 병용효과)

  • Lee, Ji-Hyun;Eo, Seong-Kug;Kim, Young-So;Lee, Chong-Kil;Han, Seong-Sun
    • Korean Journal of Pharmacognosy
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    • v.30 no.1
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    • pp.40-47
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    • 1999
  • To search for less toxic antiherpetic agents, the inhibitory effects of natural hesperetin on the plaque formation of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in Vero cells were examined by the plaque reduction assay in vitro. Hesperetin inhibited plaque formations of HSV-1 and HSV-2 in a dose dependent manner. It also exhibited more potent antiherpetic activity on HSV-2 with selectivity index (SI) of 9.8 than on HSV-1 with SI of 8.4. The combined antiherpetic effects of hesperetin with nucleoside antiherpetic agents, acyclovir and vidarabine, were examined on the multiplication of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combinations of hesperetin with acyclovir on HSV-1 and HSV-2 showed synergistic effects with CI values of $0.29{\sim}0.73$ for 50%, 70%, 90% effective levels and those with vidarabine showed partially synergistic or additive effects with CI values of $0.83{\sim}1.33$.

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Antiherpetic Activities of Natural Naringenin Alone and in Combinations with Acyclovir and Vidarabine (천연 나린게닌의 항허피스바이러스작용과 아시클로버 및 비다라빈과의 병용효과)

  • 이지현;김영소;이종길;이혁구;한성순
    • YAKHAK HOEJI
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    • v.43 no.1
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    • pp.77-84
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    • 1999
  • To search for less toxic antiherpetic agents, the inhibitory effects of natural naringenin on the plaque formation of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in Vero cells were examined by the plaque reduction assay in vitro. Naringenin inhibited plaque formations of HSV-l and HSV-2 in a dose dependent manner. It also exhibited more potent antiherpetic activity on HSV-l with selectivity index (SI) of 19.1 than on HSV-2 with SI of 5.7 The combined antiherpetic effects of naringenin with nucleoside antiherpetic agents, acyclovir and vidarabine, were examined on the multiplication of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combinations of naringenin with acyclovir on HSV-l and HSV-2 showed more potent synergism with CI values of 0.28∼0.81 for 50%, 70%, 90% effective levels than those with vidarabine with CI values of 0.86-3.28.

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핵산 유도체들에 대한 in vitro 항바이러스 약효검색

  • 이종교
    • Proceedings of the Korean Society of Applied Pharmacology
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    • pp.112-112
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    • 1993
  • 바이러스 치료제 개발을 위하여 합성된 핵산유도체 11개에 대한 in vitro 항바이러스 약효검색을 수행하였다. 검색대상 바이러스로서 외피보유 DNA 바이러스인 human herpesvirus에 속하는 herpes simplex virus type 1과 type 2에 대해서는 Vero 세포체계에서 3일 후 CPE 저해정도를 MTT 검색법으로 cytomegalovirus에 대해서는 HEL 세포체계에서 7일 후 Giemsa 염색법으로 약효를 측정하였다. 외피비보유 RNA 바이러스인 picornavirus에 속하는 poliovirus type 1과 type 3과 coxsackie B virus type 3에 대한 약효를 HeLa 세포체계에서 2일 후 CPE 저해정도를 MTT 검색법으로 측정하였다. 아울러 selectivity index를 구하기 위하여 Vero와 HeLa 세포에 대한 약물자체의 독성인 cytocidal effect를 MIT 검색법으로 측정하였다. 그 결과 항 herpesvirus 약효는 어떤 물질에서도 발견되지 않았으나 한 물질이 poliovirus type 1과 3에 대하여 selectivity index 10정도 (CC$_{60}$ 38 ug/ml, EC$_{50}$ 1-4 ug/ml)를 나타내었고 자세한 기작은 좀 더 조사할 필요가 있다.

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Analgesic, Anti-inflammatory and Antiviral Effects of Melandrin Derivatives (Melandrin유도체의 진통 소염 및 항바이러스 효과)

  • Lim, Jung-Ki;Lee, Eun-Bang;Woo, Won-Sik;Lee, Kang-Ro;Lee, Yeong-Sun;Ma, Eun-Sook
    • YAKHAK HOEJI
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    • v.38 no.3
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    • pp.345-350
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    • 1994
  • Fourteen melandrin derivatives(I-XIV) were investigated on analgesic, anti-inflammatory and antiviral activities . Compound I [N-(p-hydroxybenzoyl)-5-hydroxyanthranilic acid methvl ester], Xll [N-(2-phenoxypropionyl)-5-hydroxy anthranilic acid propyl ester and XIV [N-(2-phenoxypropionyl)-5-hydroxyanthranilic acid exhibited analgesic activity in tail pressure and Randall-Selitto method. But no anti-inflammatory activity was shown. Compound I exhibited weak antiviral activity on Herpes simplex virus type I F strain by virus-induced cytopathic effect(CPE) assay and it's selectivity index(Sl) was 8.17.

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Wavelength and polarization selectivity of a side-polished fiber contacted with a metal-clad planar waveguide (금속 클래드 평면 도파로와 결합된 측면 연마 광섬유의 파장 및 편광 선택성)

  • 김광택;황중호;이준옥;김철호;황보승
    • Korean Journal of Optics and Photonics
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    • v.13 no.2
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    • pp.134-139
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    • 2002
  • We report an experimental investigation of the wavelength and polarization selectivity of a side-polished fiber in contact with a metal-clad planar waveguide. The influences of the structural parameters of the planar waveguide, including refractive index of the superstrate and metal thickness, on the optical transmission characteristics of the device were measured and explained. The conditions for high wavelength and polarization selectivity wore predicted and demonstrated experimentally.

Modeling the Selectivity of the Cod-end of a Trawl Using Chaotic Fish Behavior and Neural Networks

  • Kim, Yong-Hae;Wardle, Clement S.
    • Fisheries and aquatic sciences
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    • v.11 no.1
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    • pp.61-69
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    • 2008
  • Using empirical data of fish performance and physiological limits as well as physical stimuli and environmental data, a cod-end selectivity model based on a chaotic behavior model using the psycho-hydraulic wheel and neural-network approach was established to predict fish escape or herding responses in trawl and cod-end designs. Fish responses in the cod-end were categorized as escape or herding reactions based on their relative positions and reactions to the net wall. Fish movements were regulated by three factors: escape time, a visual looming effect, and an index of body girth-mesh size. The model was applied to haddock in a North Sea bottom trawl including frequencies of movement components, swimming speed, angular velocity, distance to net wall, and the caught-fish ratio; simulation results were similar to field observations. The ratio of retained fish in the cod-end was limited to 37-95% by optomotor coefficient values of 0.3-1.0 and to 13-67% by looming coefficient values of 0.1-1.0. The selectivity curves generated by this model were sensitive to changes in mesh size, towing speed, mesh type, and mesh shape.

Cell Selectivity of an Antimicrobial Peptide Melittin Diastereomer with D-amino Acid in the Leucine Zipper Sequence

  • Zhu, Wan Long;Nan, Yong Hai;Hahm, Kyung-Soo;Shin, Song-Yub
    • BMB Reports
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    • v.40 no.6
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    • pp.1090-1094
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    • 2007
  • Melittin (ME), a linear 26-residue non-cell-selective antimicrobial peptide, displays strong lytic activity against bacterial and human red blood cells. To design ME analogue with improved cell selectivity, we synthesized a melittin diastereomer (ME-D) with D-amino acid in the leucine zipper sequence (Leu-6, Lue-13 and Ile-20). Compared to ME, ME-D exhibited the same or 2-fold higher antibacterial activity but 8-fold less hemolytic activity. Circular dichroism analysis revealed that ME-D has much less $\alpha$-helical content in $\alpha$-helical content in the presence of zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes compared to negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. The blue shift of the fluorescence emission maximum of ME-D in zwitterionic EYPC/cholesterol (10 : 1, w/w) liposomes was much smaller than in negatively charged EYPE/EYPG (7 : 3, w/w) liposomes. These results suggested that the improvement in therapeutic index/cell selectivity of ME-D is correlated with its less permeability to zwitterionic membranes.