• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.10-16
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• 2013

Characteristics of biological hydrogen production rate and organic acid under anaerobic fermentation process were investigated with sugar wastewater. Hydrogen production rate was higher with alkaline pre-treatment than acidic pre-treatment, resulting in 70% increment. An adequate supply of the nutrients (N or P) into raw sugar wastewater could increase hydrogen production rate. Carbohydrate degradation of the anaerobic fermentation process was not directly related with hydrogen production. Sugar wastewater with the addition of the nutrients shows 3 times higher B/A ratio than the raw sugar wastewater. B/A ratio of the wastewater with alkaline pre-treatment and nutrients addition was most higher than other samples, showing 4.02 of B/A ratio. Higher B/A ratio shows higher hydrogen production rate at each sample.

• Journal of electromagnetic engineering and science
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• v.7 no.2
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• pp.83-90
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• 2007

In this paper, the formulation of the protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the microwave relay system network, and computed results for co-channel and adjacent channel protection ratios are illustrated over an actual system with 6.2 GHz. It is shown that the protection ratio to assure a quality of service can be expressed in terms of the composite fade margin, noise-to-interference ratio, net filter discrimination, and system parameters. In addition, the net filter discrimination, depending upon the transmitter spectrum mask and the overall receiver filter characteristic, has been examined to investigate the effect of the adjacent channel protection ratio caused by the adjacent channel interference. Regarding simulated results for 6.2 GHz, 60 km, 64-QAM, and N/I=6 dB at the bit error rate of $10^{-6}$, composite fade margin and co-channel protection ratio yield 25.14 and 50.3 dB, respectively. Also, the net filter discrimination of 26.5 dB and the adjacent channel protection ratio of 23.8 dB are obtained at the first adjacent channel of 30 MHz. The proposed method provides some merits in view of a comprehensive and practical application with more detailed and various system parameters needed to access the criteria for making the proper frequency coordination.

• Journal of the Korean Ceramic Society
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• v.31 no.5
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• pp.552-560
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• 1994

A composite of TiB2-Al2O3 system was successfully prepared from a mixture of TiO2, B2O3, and Al by self-propagating high temperature synthesis (SHS) with a novel characteristic, utilizing the internal oxidation heat of aluminium metal of the mixture, instead of by a conventional technique, externally heating a mixture of Ti, B and Al2O3. From a mixture with B/Ti molar ratio of =2.0, pure two phases of TiB2 and $\alpha$-Al2O3 with good crystallinity and small, uniform sizes were formed. However, when the B/Ti molar ratio of the mixture goes to a value less than 2.0, in addition to the above main minerals, a small smounts of metastable phases such as TiB and Ti3B4 were formed. It was found that about 60%, the optimum green density of compacts gave their highest reaction rate and temperature during SHS process. TiB2-Al2O3 system composite with B/Ti molar ratio of =2.0 could be pressurelessly sintered even at 190$0^{\circ}C$ under Ar gas flows without any addition of sintering aids, showing their good properties such as 91.2% in relative density, 2750 kgf/$\textrm{mm}^2$ in Vickers hardness and 2620 kgf/$\textrm{cm}^2$ in flexural strength.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.287-291
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• 1993

Catalytic iminohydroacylation has been achieved by the reaction of aldimine 1 and 1,5-hexadiene (2a) with Wilkinson's complex as catalyst. Compounds 7a, 8a and 9a were obtained as final product after hydrolysis of the resulting iminohydroacylation products 4a, 5a and 6a. Depending on the reactant ratio (2/1), the ratio of products were changed dramatically : As the 2/1 ratio was increased, 7a is the major product after hydrolysis while 8a is the major with an 1/1 ratio of 2/1. The mechanism of the formation of 5a is determined by the reaction of 1 and 2b under the identical reaction conditions. Considering that 5a may not be formed from the hydroiminoacylation of 14a since 5b cannot be formed from that of conjugate diene 14b generated from isomerization of 2b, 5a must be formed from the reaction of 4a and 10 by addition-elimination mechanism.

• Korean Journal of Remote Sensing
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• v.2 no.2
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• pp.79-94
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• 1986

TM data, which have better resolution in spatial and spectral than MSS data, were used for this study, and several Image Processing Techniques (IPT) were examined for finding the best IPT to fit to lineament extraction and mineralized zone mapping. The Ryeongnam area was selected as test area, because the area is one of major mineralized zones in Korea and its hydrothermal alteration zone is wider and deeper than other areas. The spatial filtering method is most optimum one for limeament extraction: that is, the directional spatial filtering is most efficient to detect N-S, E-W direction lineaments on the image, and the high boost filtering can be applied for mapping all direction lineaments. The ratio method was selected for detecting altered zone. It is possible to make several tens combinations in ratio with 7 bands of TM data, but considering spectral characteristics of each band of TM to the geological meterials and vegetation, the band 4/band 3(A), band 5/band 7(B), and B/A ratio methods were chosen among them. The 5/7 ratio image did not show clearly the altered area due to noise from vegetation cover, so the 4/3 ratio imae was used for trying to decrease the effect of vegetation. As a result the B/A ratio image showed quite nicely the altered zone of the test area. In conclusion, the spatial filtering is the best image processing techniques for lineament mapping, and the B/A ratio image in TM data is useful for the mineralized zone mapping.

• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1533-1538
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• 2008

Porphyrins generally bind DNA in two different ways with respect to the mixing ratio; monomeric binding at a low mixing ratio and outside stacking at a high mixing ratio. In the present study, CTDNA binding property of a planar structured porphyrin, 5,10,15,20-tetrakis(N-methyl-4-pyridin-4-yl-phenyl)porphyrin (referred to as B-TMPyP) was investigated using absorption, CD, LD, and $LD^r$ spectroscopies. B-TMPyP produced a bisignate CD band, even at the lowest mixing ratio, indicating that B-TMPyP may not have a monomeric binding mode. From the observations of the spectral changes to the absorption, CD, and LD spectra in mixing ratio dependent titrations, B-TMPyP seems to have a quite different stacking type compared to that for the binding of $H_2$TMPyP. Moreover, B-TMPyP produced a CD band of opposite shape in the Soret band region. A qualitative explanation for the observed optical differences is also given.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.720-727
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• 2017

This study determined the optimum mix proportions for volcanic-ash-based geopolymer by analyzing the flow, setting time, and compressive strength. $Na2SiO_3$ and NaOH were used as alkali activators, and NaOH concentrations of 2, 4, 6, and 8M were used for different experimental cases. The A/B ratios examined were 0.25, 0.3, 0.35, 0.4, and 0.45, and the ratios of volcanic ash to blast furnace slag binder were 7:3, 6:4, and 5:5. In the experiment, the flow and setting time tended to decrease and the compressive strength increased as the molarity of NaOH in the geopolymer increased. The optimum molarity of NaOH was determined to be 4M. As the A/B ratio increased, the setting time decreased and the compressive strength increased. The most advantageous A/B ratio for the setting time and strength was 0.35. Increasing the ratio of volcanic ash resulted in a longer setting time and lower compressive strength. The optimum binder ratio was chosen as 6:4 based on the setting time and compressive strength. Thus, 4M of NaOH, an A/B ratio of 0.35, and binder ratio of 6:4 are considered as the proper parameters for the volcanic-ash-based geopolymer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6188-6204
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• 2017

Over the years, more password-based authentication key agreement schemes using chaotic maps were susceptible to attack by off-line password guess attack. This work approaches this problem by a new method--new theorem of chaotic maps: $T_{a+b}(X)+T_{a-b}(X)=2T_a(X)T_b(X)$,(a>b). In fact, this method can be used to design two-party, three-party, even in N-party intelligently. For the sake of brevity and readability, only a two-party instance: a novel Two-party Password-Authenticated Key Agreement Protocol is proposed for resisting password guess attack in this work. Compared with the related literatures recently, our proposed scheme can be not only own high efficiency and unique functionality, but is also robust to various attacks and achieves perfect forward secrecy. For capturing improved ratio of security and efficiency intuitively, the paper firstly proposes a new parameter called security/efficiency ratio(S/E Ratio). The higher the value of the S/E Ratio, the better it is. Finally, we give the security proof and the efficiency analysis of our proposed scheme.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.16-24
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• 2018

In this study, an experiment was conducted to analyze mortar based rheology for 3D printing method application. The tendency of rheological properties due to the change of W/B, binder type, replacement ratio, and super plasticizer which have a great influence on the flow characteristics of concrete was experimentally analyzed. Experiments were carried out by dividing into paste and mortar. In the paste experiment, rheology was analyzed by setting W/B, binder type, replacement ratio, and super plasticizer dosage as main variables. In the mortar experiment, the rheological properties of W/B and sand ratio were analyzed. As a result, as the W/B was increased, the viscosity decreased and the FA ratio to replace FA increased and the viscosity increased. In order to increase the fluidity, substitution of only 5% of SF reduces the shear stress and the viscosity is reduced by about 83%. Mortar rheological evaluation shows that there is a critical section where a large change occurs in the W/B 30 to 40% section. Also, in the same W/B, it is analyzed that there is a critical section where the shear stress increases more than twice in the sand ratio of 50~60%.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.5
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• pp.93-101
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• 2010

The demand for elastic pavement, providing comfort for pedestrians is expected to increase continuously but the lack of a standard for materials mixing ratio, that is, the optimal mixing ratio between ERDM chip and polyurethane binder, is still in a trial and error stage. This study aimed at recommending an optimal mixing ratio for elastic landscape pavement through a coherence and resilience test depending on ratio. The test result is outlined as follows. In a tensile strength test, samples B and C indicated a close positive relationship between the binder mixing ratio and tensile strength, indicating that the higher the mixing ratio the higher the tensile strength. In a hardness test, none of samples A, B or C indicated a statistical interrelationship between the binder mixing ratio and hardness. That is, the hardness of the elastic pavement material remained unchanged, irrespective of the binder mixing ratio. In a resilience lest, Samples A and B indicated a close negative interrelation between mixing ratio and resilience, indicating that the higher the mixing ratio, the lower the resilience. Upon analyzing the optimal mixing ratio based on test results, an increase in tensile strength began to slow at a 20% mixing ratio, while resilience began to reduce rapidly at 22%, Thus the optimal range for a mixing ration appeared to be 20~22%. The outcome of this study could to provide guidance for improving the elasticity and stability of elastic pavement.