• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.71-76
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• 2014

There is to be virtually impossible to solve the very large digits of prime number p and q from composite number n=pq using integer factorization in typical public-key cryptosystems, RSA. When the public key e and the composite number n are known but the private key d remains unknown in an asymmetric-key RSA, message decryption is carried out by first obtaining ${\phi}(n)=(p-1)(q-1)=n+1-(p+q)$ and then using a reverse function of $d=e^{-1}(mod{\phi}(n))$. Integer factorization from n to p,q is most widely used to produce ${\phi}(n)$, which has been regarded as mathematically hard. Among various integer factorization methods, the most popularly used is the congruence of squares of $a^2{\equiv}b^2(mod\;n)$, a=(p+q)/2,b=(q-p)/2 which is more commonly used then n/p=q trial division. Despite the availability of a number of congruence of scares methods, however, many of the RSA numbers remain unfactorable. This paper thus proposes an algorithm that directly and immediately obtains ${\phi}(n)$. The proposed algorithm computes $2^k{\beta}_j{\equiv}2^i(mod\;n)$, $0{\leq}i{\leq}{\gamma}-1$, $k=1,2,{\ldots}$ or $2^k{\beta}_j=2{\beta}_j$ for $2^j{\equiv}{\beta}_j(mod\;n)$, $2^{{\gamma}-1}$ < n < $2^{\gamma}$, $j={\gamma}-1,{\gamma},{\gamma}+1$ to obtain the solution. It has been found to be capable of finding an arbitrarily located ${\phi}(n)$ in a range of $n-10{\lfloor}{\sqrt{n}}{\rfloor}$ < ${\phi}(n){\leq}n-2{\lfloor}{\sqrt{n}}{\rfloor}$ much more efficiently than conventional algorithms.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.249-253
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• 2009

This paper dealt with the insulation evaluation by a measurement of partial discharge(PD) on traction motors used in a hybrid vehicle. The PD method has been accepted as an effective and a non-destructive. technique to evaluate insulation performance of low-voltage electric and electronic devices. In this paper, the PD measurement system which was manufactured with a coupling network, a low noise amplifier, and an associated electronics is described. The PD measurement system has the frequency bandwidth of $1[MHz]{\sim}30[MHz]$ at -3 [dB] and the stable sensitivity of 19 [mV/pC] for the traction motor. From the experimental results, discharge inception voltage (DIV) and apparent charge (q) were $1,100[V_{rms}]$ and 105 [pC] for the used motor, and $1,400[V_{rms}]$ and 84 [pC] for the new one. By comparing the DIV and q, we could evaluate the insulation condition for the traction motors.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.1
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• pp.45-59
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• 2016

Vegetation and soil conditions of four sites in west coastal forests in South Korea, were examined to analyze the relationship between Pinus thunbergii forests structure and soil conditions. The P. thunbergii forests were divided into four clusters; 1) P. thunbergii - Prunus sargentii var. sargentii, 2) P. thunbergii - Robinia pseudoacacia, 3) P. thunbergii - P. densiflora and 4) P. thunbergii - Quercus serrata. The soil of each site was poor in chemical characteristics but good enough for land plants to grow because of its low salt concentration. According to the results by CCA Ordination, certain excessive soil nutrition has influenced on vegetation and specific species distribution. Forty eight species were found in the whole sites of coastal forests and some species appeared in every site. They are P. thunbergii, R. pseudoacacia, Rhus chinensis, Idesia polycarpa and Morus alba. For the tree species importance value, P. thunbergii was followed by R. pseudoacacia, Q. serrata, P. densiflora, Celtis sinensis, M. alba, I. polycarpa and Q. mongolica in order.

• Korean Journal of Environment and Ecology
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• v.26 no.1
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• pp.74-81
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• 2012

Decay rate and nutrient dynamics during leaf litter decomposition of deciduous Quercus acutissima and evergreen Quercus mysinaefolia were studied for 24 months from December 2008 to December 2010 in Gongju, Chungnam Province, Korea. Percent remaining weight of Q. acutissima and Q. mysinaefolia leaf litter after 24 months elapsed was $46.3{\pm}5.4%$ and $37.8{\pm}2.5%$, respectively. Decomposition of evergreen Q. mysinaefolia leaf litter was significantly faster than that of deciduous Quercus acutissima leaf litter. Decay constant(k) of Q. acutissima and Q. mysinaefolia leaf litter after 24 months elapsed was 0.38 and 0.49, respectively. Initial C/N and C/P ratio of Q. mysinaefolia leaf litter was significantly lower than those of Q. acutissima leaf litter. Initial C/N and C/P ratio of Q. acutissima leaf litter was 46.8 and 270.9, respectively. After 24 months elapsed, C/N and C/P ratio of decomposing Q. acutissima leaf litter decreased to 22.5 and 104.2, respectively. Initial C/N and C/P ratio of Q. mysinaefolia leaf litter was 22.4 and 41.7, respectively. After 24 months elapsed, C/N and C/P ratio of decomposing Q. mysinaefolia leaf litter decreased to 16.7 and 89.7, respectively. Initial concentration of N, P, K, Ca and Mg in leaf litter was 8.31, 0.44, 4.18, 9.38, 1.37 mg/g in Q. acutissima, and 19.88, 2.73, 7.06, 8.24, 2.61 mg/g in Q. mysinaefolia, respectively. Initial concentration of N and P in Q. mysinaefolia leaf litter was significantly higher than those in Q. acutissima. After 24 month elapsed, remaining N, P, K, Ca and Mg were 100.91, 114.75, 32.99, 50.63, 15.51% in Q. acutissima, and 43.22, 11.35, 12.98, 82.22, 44.23% in Q. mysinaefolia, respectively. N and P in decomposing leaf litter was immobilized in Q. acutissima, and mineralized in Q. mysinaefolia.

• Communications of the Korean Mathematical Society
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• v.19 no.4
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• pp.775-778
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• 2004

The authors aim at obtaining an interesting result for a special summation formula for $_{6F_5}$(1), by comparing two generalized Watson's theorems on the sum of a $_{3F_2}$ obtained earlier by Mitra and Lavoie et. al.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.15 no.1
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• pp.111-126
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• 2011

Objectives: To characterize Five Woons in 1993, 1994 and 1995. Methods: A diagnostic questionnaire was given to 1066 High School students who were born in Korea from 1993 to 1995. One of the Five Woons was given to the participant based on his and her birthday. The oneway analysis of variance was applied to compare the means of the Five Woons in each year. Results: 1. Developed a reliable questionnaire consisting of 28 items for the purpose of chracterizing five constitutions. 2. Based on the Duncan method, significant differences were observed among the Five Woons in height, weight and BMI (p<0.1). For height, the score of Wood constitution was lowest. For weight the core of Soil constitution was lowest. 3. Based on the Duncan method, at the significant level (p<0.1), the Five Woons were different in each year (Gapsul year, Eulhae year, Gyeyoo year) for 28 items in the questionnaires: Q1, Q2,Q3, Q7, Q8, Q11, Q12, Q15, Q18, Q19, Q21, Q22, Q24, Q26, Q27 and Q28. Conclusions: Further clinical research is necessary to characterize five constitutions and also develop more delicate analyses and questionnaires. Also the diagnosis and corresponding treatments based on the Five Woons should be further studied in view of the Asian medicine.

• Bulletin of the Korean Mathematical Society
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• v.52 no.3
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• pp.915-923
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• 2015

Self-dual codes have been actively studied because of their connections with other mathematical areas including t-designs, invariant theory, group theory, lattices, and modular forms. We presented the building-up construction for self-dual codes over GF(q) with $q{\equiv}1$ (mod 4), and over other certain rings (see [19], [20]). Since then, the existence of the building-up construction for the open case over GF(q) with $q=p^r{\equiv}3$ (mod 4) with an odd prime p satisfying $p{\equiv}3$ (mod 4) with r odd has not been solved. In this paper, we answer it positively by presenting the building-up construction explicitly. As examples, we present new optimal self-dual [16, 8, 7] codes over GF(7) and new self-dual codes over GF(7) with the best known parameters [24, 12, 9].

• Journal of Practical Agriculture & Fisheries Research
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• v.19 no.1
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• pp.139-151
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• 2017

This study was conducted to confirm the rumen fermentation characteristics of large-scale CoenzymeQ10(CoQ10) producing bacteria R. spharoides in rumen. We conducted in vitro continuous culture test to investigate the characteristics of rumen fermentation with 5% R. spharoides as a direct fed microorganism. A rumen microbial fermentation characteristic has stability at after 12 days for 15 day of experimental period. pH value, NH₃-N, microbial protein synthesis, ADF digestibility and NDF digestibility were not shown significantly differences between control and treatment. However, UDP was significantly higher in treatment than control (p<0.05). CoQ10 concentration was 336.0mg/l with 5% R. spharoides. On the other hands, CoQ10 was not detected without R. spharoides. Our study was shown that R. spharoides can produce CoQ10 in rumen environment without harmful effects on rumen fermentation parameter. CoQ10 in rumen may transfer into cow milk through cow metabolism. This strategy might be helpful for producing functional dairy cow milk.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.164-171
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• 2017

This study analysed 7 distribution features of dominant natural vegetation, such as elevation, slope, aspect, topographic index, annual mean temperature, warmth index and potential evapotranspiration using geographic information system(GIS) in Gayasan national park. The Gayasan national park has total 128 communities in which Pinus densiflora community occupies with 29.42%, Quercus mongolica community 27.66% relatively. These two communities comprise 80.58% out of total area, considering Q. mongolica & P. densiflora dominantly mixed communities. The Q. mongolica communities range around 575~1,065m(80.4%) in elevation, and the P. densiflora communities range around 465~965m(84.1%), respectively. The slopes of those two communities areas showed over $21^{\circ}$(78.0%) and (71.3%) respectively. In terms of slope aspect occurrence, Q. mongolica communities occur mostly on northern slope, and the P. densiflora communities on southern slope. The topographic indices of both communities occur around 5~6 most frequently. The Annual mean temperature distributions of Q. mongolica and P. densiflora range $7{\sim}8^{\circ}C$(83%), $8{\sim}9^{\circ}C$(84%), respectively, And the warmth index range of Q. mongolica is $59{\sim}70^{\circ}C{\cdot}month$ and the P. densiflora community, $58{\sim}88^{\circ}C{\cdot}month$. The potential evapotranspiration ranges mostly from 560 to 590mm/yr, in Q. mongolica communities, and from 580 to 610mm/yr in P. densiflora communities.

• Korean Journal of Materials Research
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• v.19 no.6
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• pp.293-299
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• 2009

The microstructures and mechanical properties of Dual Phase (DP), Transformation-Induced Plasticity (TRIP), and Quenching & Partitioning (Q&P) steels were investigated in order to define the strengthening mechanism of 0.2 C steel. An intercritical annealing between Ac1 and Ac3 was conducted to produce DP and TRIP steel, followed by quenching the DP and TRIP steel being quenched at to room temperature and by the TRIP steel being austemperingaustempered-air cooling cooled the steel toat room temperature, respectively. The Q&P steel was produced from full austenization, followed by quenching to the temperature between $M_s$ and $M_f$, and then enriching the carbon to stabilize the austenite throughout the heat treatment. For the DP and TRIP steels, as the intercritical annealing temperature increased, the tensile strength increased and the elongation decreased. The strength variation was due to the amount of hard phases, i.e., martensite and bainite, respectively in the DP and TRIP steels. It was also found that the elongation also decreased with the amount of soft ferrite in the DP and TRIP steels and with the amount of the that was retained in the austenite phasein the TRIP steel, respectively for the DP and TRIP steels. For the Q&P steel, as the partitioning time increased, the elongation and the tensile strength increased slightly. This was due to the stabilized austenite that was enriched with carbon, even when the amount of retained austenite decreased as the partitioning time increased from 30 seconds to 100 seconds.