• Journal of the Chungcheong Mathematical Society
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• v.22 no.1
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• pp.1-5
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• 2009

Let {$X_n,\;n{\geq}1}$ be a sequence of independent identically distributed(i.i.d.) sequence of positive random variables with common absolutely continuous distribution function(cdf) F(x) and probability density function(pdf) f(x) and $E(X^2)<{\infty}$. The random variables $\frac{X_i{\cdot}X_j}{(\Sigma^n_{k=1}X_k)^{2}}$ and $\Sigma^n_{k=1}X_k$ are independent for $1{\leq}i if and only if {$X_n,\;n{\geq}1}$ have gamma distribution.

• Journal of the Chungcheong Mathematical Society
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• v.34 no.4
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• pp.327-334
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• 2021

In this paper, we find all the prime numbers p that satisfy the following statement. If a positive integer k is a divisor of p - 1, then there is a sequence consisting of all k-th power residues modulo p, satisfying the recurrence equation of the Fibonacci sequence modulo p.

• Bulletin of the Korean Mathematical Society
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• v.59 no.5
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• pp.1269-1277
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• 2022

In this paper we consider a sequence of polynomials defined by some recurrence relation. They include, for instance, Poupard polynomials and Kreweras polynomials whose coefficients have some combinatorial interpretation and have been investigated before. Extending a recent result of Chapoton and Han we show that each polynomial of this sequence is a self-reciprocal polynomial with positive coefficients whose all roots are unimodular. Moreover, we prove that their arguments are uniformly distributed in the interval [0, 2𝜋).

• Bulletin of the Korean Mathematical Society
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• v.59 no.3
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• pp.697-707
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• 2022

It is well known that the continued fraction expansion of ${\sqrt{d}}$ has the form $[{\alpha}_0,\;{\bar{{\alpha}_1,\;{\ldots},\;{\alpha}_{l-1},\;2_{{\alpha}_0}}]$ and ${\alpha}_1,\;{\ldots},\;{\alpha}_{l-1}$ is a palindromic sequence of positive integers. For a given positive integer l and a palindromic sequence of positive integers ${\alpha}_1,\;{\ldots},\;{\alpha}_{l-1},$ we define the set $S(l;{\alpha}_1,\;{\ldots},\;{\alpha}_{l-1})\;:=\;\{d{\in}{\mathbb{Z}}{\mid}d>0,\;{\sqrt{d}}=[{\alpha}_0,\;{\bar{{\alpha}_1,\;{\ldots},\;{\alpha}_{l-1},\;2_{{\alpha}_0}}],\;where\;{\alpha}_0={\lfloor}{\sqrt{d}}{\rfloor}\}.$ In this paper, we completely determine when $S(l;{\alpha}_1,\;{\ldots},\;{\alpha}_{l-1})$ is not empty in the case that l is 4, 5, 6, or 7. We also give similar results for $(1+{\sqrt{d}})/2.$ For the case that l is 4, 5, or 6, we explicitly describe the fundamental units of the real quadratic field ${\mathbb{Q}}({\sqrt{d}}).$ Finally, we apply our results to the Mordell conjecture for the fundamental units of ${\mathbb{Q}}({\sqrt{d}}).$

• Journal of Power Electronics
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• v.16 no.4
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• pp.1513-1525
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• 2016

Rapid and accurate phase synchronization is critical for the reliable control of grid-tied inverters. However, the commonly used software phase-locked loop methods do not always satisfy the need for high-speed and accurate phase synchronization under severe grid imbalance conditions. To address this problem, this study develops a novel open-loop phase locking scheme based on a synchronous reference frame. The proposed scheme is characterized by remarkable response speed, high accuracy, and easy implementation. It comprises three functional cascaded blocks: fast orthogonal signal generation block, fast fundamental-frequency positive sequence component construction block, and fast phase calculation block. The developed virtual orthogonal signal generation method in the first block, which is characterized by noise immunity and high accuracy, can effectively avoid approximation errors and noise amplification in a wide range of sampling frequencies. In the second block, which is the foundation for achieving fast phase synchronization within 3 ms, the fundamental-frequency positive sequence components of unsymmetrical grid voltages can be achieved with the developed orthogonal signal construction strategy and the symmetrical component method. The real-time grid phase can be consequently obtained in the third block, which is free from self-tuning closed-loop control and thus improves the dynamic performance of the proposed scheme. The proposed scheme is adaptive to severe unsymmetrical grid voltages with sudden changes in magnitude, phase, and/or frequency. Moreover, this scheme is able to eliminate phase errors induced by harmonics and random noise. The validity and utility of the proposed scheme are verified by the experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2341-2348
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• 2009

An intrusion detection technique based on host consider system call sequence or system call arguments. These two ways are suitable when system call sequence or order and length of system call arguments are out of order. However, there are two disadvantages which a false positive rate and a false negative rate are high. In this paper we propose the T-N2SCD detection model based on Time Window in order to reduce false positive rate and false negative rate. Data for using this experiment is provided from DARPA. As experimental results, the proposed model showed that the false positive rate and the false negative rate are lowest at an interval of 1000ms than at different intervals.

• Animal cells and systems
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• v.7 no.2
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• pp.133-137
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• 2003

Secreted proteins and membrane proteins play key roles in the formation, differentiation, and maintenance of multicellular organisms. In this study, we undertook to characterize these protein types in the central nervous system of the marine snail Aplysia kurodai using a yeast-based signal sequence trap method. One hundred and three cDNA clones were obtained by screening 300,000 clones from the signal sequence trap cDNA library. Of these, twelve were identical to previously identified Aplysia genes, 19 were related to known proteins in other organisms, and 54 clones were novel. These 54 new genes had high signal peptide scores or were found likely to contain a transmembrane domain sequence. Only 18 of the 103 clones proved to be false positive. The study demonstrates that the signal sequence trap method is an effective tool for Isolating Aplysia genes encoding secreted and membrane proteins.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.151-156
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• 2002

This study was performed to obtain the thermostable $\beta$-glycosidase producing bacteria from hot spring of volcanic area at Atagawa in Japan. KNOUC 202 was selected because it showed thermostable $\beta$-glycosidase activity in sodium phosphate buffer(pH 6.8) at $70^{\circ}C$ for 4h, and it was identified. The strain was aerobic, asporogenic bacilli, immobile, gram negative, catalase positive, oxidase positive, and pigment-producing. Optimum growth was at $70~72^{\circ}C$, pH 7.0~7.2, and it could grow in the presence of 3% NaCl. The main fatty acids in cell were iso-15:0 and iso-l7:0. 16S rRNA sequence of KNOUC 202 showed 99.9% similarity with that of Thermus thermophilus ATCC 27634(HB8). Based on morphological, physiological, biochemical characteristics, cellular fatty acids profile and 16S rRNA sequence analysis, KNOUC 202 was identified as Thermus thermophilus.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.103-105
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• 2008

In grid-interconnection system, a fast, robust and precise phase angle detector is most important to grid synchronization and the active power control. The phase angle can be easily estimated by synchronous dq PLL system. On the other hand under unbalanced voltage condition, synchronous dq PLL system has problem that harmonics occur to phase angle or magnitude of grid voltage because of the effect of the negative sequence components. So, To eliminate the negative sequence components, the PLL method using APF (All Pass Filter) in a stationery reference frame to extract positive sequence components under unbalanced voltage condition is researched. In this paper, we propose a new PLL method with decoupling network using APF in a synchronous reference frame to extract the positive sequence components of the grid voltage under unbalanced grid. The cut-off frequency of APF in a synchronous reference frame can be set to twice of the fundamental frequency comparing with that of APF in a stationery reference frame which is the fundamental frequency. The proposed PLL strategy can detect the phase angle quickly and accurately under unbalanced gird voltages. Simulation and experimental results are presented to verify the proposed strategy under different kind of voltage dips.

• Korean Institute of Interior Design Journal
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• v.21 no.5
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• pp.181-188
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• 2012

Body movements of humans have emotions and these movements have meanings of 'Living Spirits' and 'Emotions'. Also emotions of humans indicate all body movements which are made within the environment. This study aims at providing new potentials to emotional design research methods not only by understanding the characteristics of visual perception according to body movements and but by investigating correlations between sequence which arise by the visual perception and emotions through experiments. As for the scope and method of this study, the emotional space designs were analyzed through the emotional theory study, SD method was used to evaluate emotions and the movements in the modern village and traditional village with similar elements were compared and analyzed for the empirical study. As a result, first it was confirmed waling hours in the traditional village took more than the modern village and it is thought movements of humans are affected by the visual environments. Second, it was confirmed values of the emotional evaluation were higher in the traditional village than the modern village. Third, according to a result of the correlation analysis between space sequence and emotions, it was closed with negative emotions such as 'Closed', and 'Complicated' from positive emotional words such as 'Natural'. 'Open', 'Curious', etc. as spaces are experienced more through movements in the modern village. On the contrary, the emotional intensity of the positive words such as 'In Harmony', 'Beautiful' and 'Warn' through movements in the traditional village increased as spaces were experienced more. As a result of this study, it was confirmed the time, space and emotions have correlations each other.