• Korean Journal of Weed Science
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• v.15 no.1
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• pp.85-98
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• 1995

Six malformin B's produced by Aspergillus niger van Tiegh. were separated by HPLC. Their structures determined by the methods of amino acid analyses, mass spectrometry, and two-dimensional NMR were revealed as cyclic pentapeptides structurally related to malformin $A_1$. Both the NMR and MS/MS data suggest that the respective structures of separated malformin B's were as follows; cyclo-D-Cys-D-Cys-L-Val-D-Leu-L-allo-Ile for $B_{1a}$, cyclo-D-Cys-D-Cys-L-Val-D-Leu-L-Leu for $B_{1b}$, cyclo-D-Cys-D-Cys-L-Val-D-Val-L-Leu for $B_2$, cyclo-D-Cys-D-Cys-L-Val-D-Ile-L-Leu for $B_3$, cyclo-D-Cys-D-Cys-L-Val-D-Ile-L-Ile for $B_4$, and cyclo-D-Cys-D-Cys-L-Val-D-Val-L-Ile for $B_5$. Among the malformin B's, the structure of $B_{1b}$ was the same as that of malformin $A_3$ or C. All the malformin B's showed physiological activities in the two assay systems using corn(Zea mays L.) roots and mung bean(Phaseolus aureus Roxb.) hypercotyl segments. The malformin B's with molecular weight 529 were more effective for inducing corn root curvature than those with molecular weight 515. The difference in molecular weight of malformin B's, i.e., the retention time on HPLC, results in the polarity change of the whole malformin molecule which affects the revealation of the malformin activities. In addition, the disulfide form of the malformin B's gives the rigidity of the molecule, whereas the combination of the fourth and the fifth amino acid residues provides the optimal three-dimensional configuration to the malformin receptor of plants. Presumably, these two factors are appeared to be essential for the greatest physiological activity of malformin B's. malformin $B_{1a}$ caused the corn root curvature by 90% at a concentration of $0.25{\mu}M$. However, such differential activities with molecular weight of 529 or 515 of malformin B's were not found in the mung bean hypercotyl segment test. Maximum stimulation of mung bean hypercotyl growth was observed at $0.1{\mu}M$ concentration of malformin B's. The growth of the segments treated with $B_5$ was 154% greater than that of the control.

• Korean Journal of Veterinary Service
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• v.33 no.1
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• pp.29-35
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• 2010

This study was performed to test the hypothesis that Brucella abortus strain RB51 (SRB51) might protect Korean indigenous mongrel dog against challenge with either virulent B. abortus biotype 1 or B. canis. A total of 12 Korean mongrel dogs were divided into four groups (Group A, B, C and D). Dogs belonging to Group A and C were inoculated subcutaneously with $1{\times}10^9$ CFU of SRB51 in 1ml of sterile phosphate buffered saline (PBS). Dogs of Group B and D were inoculated subcutaneously with 1ml of sterile PBS as control. At 12 weeks post vaccination, dogs of Group A and B were challenged by oral inoculation of virulent strain of B. canis ($5.0{\times}10^9$ CFU) and dogs of Group C and D were challenged by oral inoculation of virulent strain of B. abortus biotype 1 ($4.4{\times}10^{10}$ CFU). The serum antibodies titers in all dogs were monitored at regular interval for eight weeks after challenge (AC) by standard tube agglutination test, plate agglutination test, rose bengal test, 2-mercaptoethanol rapid slide agglutination test and 2-mercaptoethanol tube agglutination test. No antibody titers in Group A and C was detected. Also, the challenge strains were not found from blood of all dogs of Group A and C from 1 week AC till the end of the experiment by culture and modified AMOS-PCR, whereas B. canis and B. abortus challenge strains were detected from blood of Group B and D, respectively. In addition, neither of two challenge bacteria was recovered from liver, spleen, kidneys, lymph nodes and reproductive tracts of Group A and C dogs after postmortem. However, B. canis and B. abortus challenge strains were isolated from these tissues of Group B and D, respectively. These data suggest that SRB51 could be a promising vaccine candidate for immunizing dogs to control canine brucellosis caused by B. canis or B. abortus.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.76-82
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• 2001

Because the biological tissue with inhomogeneous acoustic properties does not keep a particular shape, the measurement of propagation characteristics of ultrasonic fields by the conventional scanning method with a miniature hydrophone is difficult. In this study, a two-dimensional may hydrophone was fabricated using the PVDF (Polyvinylidene fluoride) piezo-electric film and a ultrasonic field measurement system with it was established. For the acoustic field produced by a circular plan transducer with center frequency of 2.25㎒ and 13㎜ in diameter, it was possible to make a fairly accurate field measurement using the hydrophone system. The attenuation coefficients at 2.25 ㎒ for biological tissues were 0.7∼1.3 dB/cm(average; 1.0 dB/cm) in bovine liver, 1.0∼1.8 dB/cm (average; 1.6 dB/cm) in pig liver, 0.9∼2,9 dB/cm(average: 2.1 dB/cm) in bovine muscles, 1.7∼3.3 dB/cm (average; 2.5 dB/cm) in pig muscles.

• Korean Journal of Mathematics
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• v.30 no.3
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• pp.467-474
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• 2022

In this article, we consider the integral operator 𝓒^b,c, which is defined as follows: $${\mathcal{C}}^{b,c}(f)(z)={\displaystyle\smashmargin{2}{\int\nolimits_{0}}^z}{\frac{f(w)*F(1,1;c;w)}{w(1-w)^{b+1-c}}}dw,$$ where * denotes the Hadamard/ convolution product of power series, F(a, b; c; z) is the classical hypergeometric function with b, c > 0, b + 1 > c and f(0) = 0. We investigate the boundedness of the 𝓒^b,c operators on Bloch spaces.

• YAKHAK HOEJI
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• v.44 no.4
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• pp.325-333
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• 2000

The 1,3-dipolar cycloaddition reaction of the quinoxaline 4-oxides 2 with 2-chloroacrylonitrile gave the 2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxalines 3, which were converted into the 2,3,4,6-tetrahydro-1H-1,2-diazepino[3,4-b]quinoxalines 5-7. The reaction of compounds 3 with selenium dioxide in acetic acid/water resulted in ring transformation to give the 1,4-dihydro-4-oxopyridazino[3,4-b]quinoxalines 8.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.111-120
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• 2022

Improving flour quality is one of the major targets of wheat breeding programs. This study determined the optimum high-molecular-weight glutenin subunits (HMW-GS) to improve flour quality, and analyzed the correlation between agronomic and quality traits in Korea. A total of 180 wheat varieties, including 55 Korean and 125 foreign cultivars, carrying various Glu-1 alleles, were evaluated for their quality and agronomic traits. Results indicated that Glu-A1b, Glu-B1b, and Glu-D1f were the most prevailing alleles for each Glu-1 locus for Korean wheat cultivars. Korean wheat cultivars recorded shorter days to heading (DTH) and longer days to maturity (DTM) compared to foreign cultivars. In addition, an interaction effect was found between Glu-A1 and Glu-B1 alleles on several quality parameters. The combination of Glu-A1c and Glu-B1i showed a higher protein content, dry gluten content, and higher sodium dodecyl sulfate (SDS) sedimentation value than other Glu-A1×Glu-B1 combinations. Cultivars carrying Glu-A1a or Glu-A1b, Glu-B1i or Glu-B1al, and Glu-D1d for each Glu-1 locus exhibited a longer mixing time and stronger mixing tolerance. The DTM positively correlated with the protein content, gluten index and SDS sedimentation value. However, a negative correlation was observed between DTH and quality traits. Owing to the above results, this study suggests that an increase in the frequency of Glu-B1i or Glu-B1al, Glu-D1d coupled with a short DTH and long DTM could significantly improve wheat quality properties.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.15-15
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• 2011

As you know, boron compounds, borax ($Na_2B_4O_5(OH)_4{\cdot}8H_2O$) etc. were known thousands of years ago. As for natural boron, it has two naturally occurring and stable isotopes, boron 11 ($^{11}B$) and boron 10 ($^{10}B$). The neutron absorption $^{10}B$ is included about 19~20% with 80~81% $^{11}B$. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. The mass difference results in a wide range of ${\beta}$ values between the $^{11}B$ and $^{10}B$. The $^{10}B$ isotope, stable with 5 neutrons is excellent at capturing thermal neutrons. For example, it is possible to decrease a thermal neutron required for the nuclear reaction of uranium 235 ($^{235}U$). If $^{10}B$ absorbs a neutron ($^1n$), it will change to $^7Li+^1{\alpha}$ (${\alpha}$ ray, like $^4He$) with prompt ${\gamma}$ ray from $^{11}B$ $^{11}B$ (equation 1). $$^{10}B+^1n\;{\rightarrow}\;^{11}B\;{\rightarrow}\; prompt \;{\gamma}\;ray (478 keV), \;^7Li+4{\alpha}\;(4He)\;\;\;\;{\cdots}\; (1)$$ If about 1% boron is added to stainless steel, it is known that a neutron shielding effect will be 3 times the boron free steel. Enriched boron or $^{10}B$ is used in both radiation shielding and in boron neutron capture therapy. Then, $^{10}B$ is used for reactivity control and in emergency shutdown systems in nuclear reactors. Furthermore, boron carbide, $B_4C$, is used as the charge of a nuclear fission reaction control rod material and neutron cover material for nuclear reactors. The $B_4C$ powder of natural B composition is used as a charge of a control material of a boiling water reactor (BWR) which occupies commercial power reactors in nuclear power generation. The $B_4C$ sintered body which adjusted $^{10}B$ concentration is used as a charge of a control material of the fast breeder reactor (FBR) currently developed aiming at establishment of a nuclear fuel cycle. In this study for new boron compound, silicon boride ceramics for capturing thermal neutrons, preparation and characterization of both silicon tetraboride ($SiB_4$) and silicon hexaboride ($SiB_6$) and ceramics produced by sintering were investigated in order to determine the suitability of this material for nuclear power generation. The relative density increased with increasing sintering temperature. With a sintering temperature of 1,923 K, a sintered body having a relative density of more than 99% was obtained. The Vickers hardness increased with increasing sintering temperature. The best result was a Vickers hardness of 28 GPa for the $SiB_6$ sintered at 1,923K for 1 h. The high temperature Vickers hardness of the $SiB_6$ sintered body changed from 28 to 12 GPa in the temperature range of room temperature to 1,273 K. The thermal conductivity of the SiB6 sintered body changed from 9.1 to 2.4 W/mK in the range of room temperature to 1,273 K.

• Membrane Journal
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• v.2 no.1
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• pp.59-66
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• 1992

The experimental studies were carried out on ultrafiltration of PEG #6000 and dextran 70T macromole¬cules. using an asymmetric cellulose acetate membrane in a cross flow plane type cell. Effects of pressure difference. feed concentration were studied on permeate flux and observed rejection for both the macromole¬cules. and the concentration polarization layer resistance $R_{b1}$ on permeate flux was analysed. The concentration polarization layer resistance $R_{b1}$ was correlated with the average macromolecule concen¬tration $C_{b1}$ in polarization layer. The resulting dimensionless correlation was expressed as : $\frac{R_{b1}}{{R_m}}=\alpha[\frac{\rho_{b1}}{C_{b1}}]^\beta$

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.41-47
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• 2016

The times of multiplication for encryption and decryption of cryptosystem is primarily determined by implementation efficiency of the modular exponentiation of $a^b$(mod m). The most frequently used among standard modular exponentiation methods is a standard binary method, of which n-ary($2{\leq}n{\leq}6$) is most popular. The n-ary($1{\leq}n{\leq}6$) is a square-and-multiply method which partitions $b=b_kb_{k-1}{\cdots}b_1b_{0(2)}$ into n fixed bits from right to left and squares n times and multiplies bit values. This paper proposes a variable-length partition algorithm that partitions $b_{k-1}{\cdots}b_1b_{0(2)}$ from left to right. The proposed algorithm has proved to reduce the multiplication frequency of the fixed-length partition n-ary method.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.82-87
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• 2006

Twenty one strains strongly producing protease were isolated from Korean traditional Cheonggukjang. Eight strains selected by sensory evaluation on Cheonggukjang prepared with isolated strains were identified with based on biochemical properties a and 16S rDNA sequencing. Identified strains were Bacillus subtilis MB4, and Bacillus amyloliquefaciens A1, A2, B1, MC1, SB2, SC1, and SD1. Protease activities, important strain selection factor, were higher in Cheongjukjang prepared with B. subtilis MB4 (179.6 Unit) and B. amyloliquefaciens SB2 (201.9 Unit) than commercial traditional Cheonggukjang (97.9 Unit). Sensory evaluation revealed Cheonggukjang prepared with B. subtilis MB4 had flavor very similar to commercial traditional Cheonggukjang. Cheonggukjang prepared with B. suhtilis MB4 (0.0006 Pa s) and commercial traditional Cheonggukjang (0.0002 Pa s) revealed lower viscosities than those of Cheonggukjang prepared with B. amyloliquefaciens SB2, MC1, B1, A1, SD1, A2, and SC1 (0.006 to 0.008 Pa s at 1001/s. Results show Cheonggukjang could be prepared using single strain of B. subtilis MB4, maintaining high protease activity and very similar sensory and viscosity qualities with those of commercial traditional Cheonggukjang.