• Honam Mathematical Journal
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• v.40 no.4
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• pp.681-689
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• 2018

In this paper, we defined new subclasses of Spirallike and Robertson functions by using concept of q-derivative operator. We investigate convolution properties and coefficient estimates for both classes q-Spirallike and q-Robertson functions denoted by ${\mathcal{S}}^{\lambda}_q[A,\;B]$ and ${\mathcal{C}}^{\lambda}_q[A,\;B]$, respectively.

• Journal of applied mathematics & informatics
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• v.39 no.5_6
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• pp.643-654
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• 2021

In this paper, we define a modified q-poly-Bernoulli polynomials of the first type and modified q-poly-tangent polynomials of the first type by using q-polylogarithm function. We derive some identities of the modified polynomials with Gaussian binomial coefficients. We also explore several relations that are connected with the q-analogue of Stirling numbers of the second kind.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.311-320
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• 2008

In this paper, a new variable active inductor using a conventional grounded active inductor with feedback variable LC-resonator is proposed. The grounded active inductor is realized by the gyrator-C topology and the variable LC-resonator is realized by the low-Q spiral inductor and varactor. This variable LC-resonator can compensate the degradation of Q-factor due to parasitic capacitance of a transistor, and the frequency range with high Q-factor is adjustable by resonance frequency adjustment of LC-resonator. The fabricated variable active inductor with Magnachip $0.18{\mu}m$ CMOS process shows that high-Q frequency range can be adjusted according to varactor control voltage from 4.66 GHz to 5.45 GHz and Q-factor is higher than 50 in the operating frequency ranges. The measured inductance at 4.9GHz can be controlled from 4.12 nH to 5.97 nH by control voltage.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.13 no.1
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• pp.7-10
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• 1977

In estimates of horizontal radiation, its values are determined by correlations among the length of day, noon altitude of the sun, and cloud amount. During winter from 1971 to 1974 in Korea, its correlations are calculated by empirical method are $$Q_o=0.0124 H_cT_d at clear day and$$ $$ Q_s=0.0124 H_cT_d (1-0.0C4^1.3) at cloudy day.$$ here$ Q_o, Q_s, H_c, T_d, C $ are horizontal radiation at clear day, horizontal radiation at cloudy day, noon altitude of the sun, length of day, and cloud amount. In applications of this equation at 10 stations in Korea, errors are less than 10% when cloud amount are less than 7, and 1O~20% when cloud amount are more than 7. But, according to Laevastu equation in same case, errors are 50% closely.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1787-1794
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• 2008

Coenzyme $Q_{10}$ and six derivatives of coenzyme $Q_n$ were synthesized and tested for their antioxidative effects occurred in proximal tubular epithelial cell (LLC-PK1 cell) and cytotoxicities using in NIH/3T3 cell. As the result, synthetic coenzyme $Q_n$ derivatives showed a potent antioxidative effect compared to coenzyme $Q_{10}$. Among these synthetic compounds, coenzyme $Q_3$-C at ranged 0.04 to 0.4 mmol showed the $107.7{\sim}135.9%$ of cell viability in LLC-PK1 cell. In the test of NIH/3T3, all synthesized coenzyme $Q_n$ derivatives showed the similar effect compared with coenzyme $Q_{10}$. A correlation between isoprene unit number of coenzyme $Q_n$ derivatives and its biological effects, we suggest reduction of isoprene unit number of $Q_n$ derivatives may be related to the increase of antioxidants effects and the reduction of cytotoxicities.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.557-564
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• 2012

This study concerns the existence of positive solution for the following nonlinear system $$\{-div(|x|^{-ap}|{\nabla}u|^{p-2}{\nabla}u)=|x|^{-(a+1)p+c_1}({\alpha}_1f(v)+{\beta}_1h(u)),x{\in}{\Omega},\\-div(|x|^{-bq}|{\nabla}v|q^{-2}{\nabla}v)=|x|^{-(b+1)q+c_2}({\alpha}_2g(u)+{\beta}_2k(v)),x{\in}{\Omega},\\u=v=0,x{\in}{\partial}{\Omega}$$, where ${\Omega}$ is a bounded smooth domain of $\mathbb{R}^N$ with $0{\in}{\Omega}$, 1 < $p,q$ < N, $0{{\leq}}a<\frac{N-p}{p}$, $0{{\leq}}b<\frac{N-q}{q}$ and $c_1$, $c_2$, ${\alpha}_1$, ${\alpha}_2$, ${\beta}_1$, ${\beta}_2$ are positive parameters. Here $f,g,h,k$ : $[0,{\infty}){\rightarrow}[0,{\infty})$ are nondecresing continuous functions and $$\lim_{s{\rightarrow}{\infty}}\frac{f(Ag(s)^{\frac{1}{q-1}})}{s^{p-1}}=0$$ for every A > 0. We discuss the existence of positive solution when $f,g,h$ and $k$ satisfy certain additional conditions. We use the method of sub-super solutions to establish our results.

• The Korean Journal of Ecology
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• v.11 no.3
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• pp.145-152
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• 1988

The potential natural vegetation of Naejangsan national park area, southwestern Korea, was inferred from the actual vegetation. With the phytosociological classification, ordinatins and field surveys, the actual vegetation map of the area was made in scale 1:25, 000, including ten communities of Pinus densiflora, quercus mongolica, Quercus variabilis, Carpinus laxiflora, Daphnipyllum macropodum, Carpinus tschonoskii, Quercus aliena-Carpinus tschonoskii, Cornus controversa-Lindera erythrocarpa, Torreya mucifera-Zelkova serrate and Acer mono-Zelkova serrata community. The analyses of species richness, age structure and various informations on vegetation changes suggest the three pathways of late stage succession from P. densiflora forest to climatic climax. The first of them is through Q. variabilis forest to Q. monogolica forest in the upper parts of the mountain, the second through Q. variabilis and Q. serrata forest to C. laxiflora forest in the middle parts and the third through Q. aliena forest to C. tschonoskii forest in lower parts. Considering the actual vegetation and informations on the vegetation changes including human activities, the potential natural vegetation of the mountain mainly composed of Q. monogolica, C. laxiflora, C. tschonoskii, P. densiflora and Z. serrata forest as climatic climax and/or edaphic climax was inferred. The present situration of nature conservation in the area was estimated by the examination on the actual vegetation and potential natural vegetation map.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.37-43
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• 2008

The performance and hardware complexity of LDPC decoders depend on the design parameters of quantization, the clipping threshold $c_{th}$ and the number of quantization bits q, and also on the maximum number of decoding iterations. In this paper, the BER performances of LDPC codes are evaluated according to the clipping threshold $c_{th}$ and the number of quantization bits q through the simulation studies. By comparing the quantized Min-Sum algorithm with the ideal Min-Sum algorithm, it is shown that the quantized case with $c_{th}=2.5$ and q=6 has the best performance, which approaches the idea case. The decoding complexities are calculated and the word error rates(WER) are estimated by using the pdf which is obtained through the statistical analyses on the iteration numbers. These results can be utilized to tradeoff between the decoding performance and the complexity in LDPC decoder design.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.748-752
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• 1995

Canned and bottled orange juices currently sold in Korean market were stored for 24 weeks at 20, 30, 40 and $50^{\circ}C$ and analyzed after opening at 4 week intervals. Activation energy, $Q_{10}$ values and shelf-life at respective temperatures were calculated from the data on various quality indexes. Proposed indexes were lead, tin, iron and vitamin C contents in canned juices and vitamin C content and browning index in bottled juices and $Q_{10}$ values for these parameters were in the range of $1.3{\sim}2.0$. Shelf-life calculated for canned juices at 10, 20 and $30^{\circ}C$ were 10, 6 and 3 months and that in bottled juices, 24, 12 and 6 months, respectively. When the distribution temperature of juices in Korea is assumed to be $15^{\circ}C$ average, the optimum shelf-life was estimated to be 8 months in canned juices and 18 months in bottled juices. In order to ascertain the safety of canned orange juices, efforts are needed to re-examine the recommended distribution period, legal limit for lead and improvement of container materials.

• Diabetes and Metabolism Journal
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• v.42 no.6
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• pp.513-518
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• 2018

Background: Recent studies have correlated serum cystatin C (CysC) with vascular complications, but few studies have investigated this correlation in diabetes patients without nephropathy. This study aimed to evaluate if higher serum CysC levels increase the risk for vascular complications in type 2 diabetes mellitus patients with normal renal function or mild renal impairment. Methods: A total of 806 consecutive patients with type 2 diabetes mellitus who were admitted to the diabetes center of Soonchunhyang University Hospital for blood glucose control were retrospectively reviewed. Patients with nephropathy were excluded. Subjects were categorized into quartiles of serum CysC levels (Q1, ${\leq}0.65mg/L$; Q2, 0.66 to 0.79 mg/L; Q3, 0.80 to 0.94 mg/L; and Q4, ${\geq}0.95mg/L$). Results: The proportion of patients with diabetic retinopathy (DR) (P for trend <0.001), coronary heart disease (CHD) (P for trend <0.001), and stroke (P for trend <0.001) increased across the serum CysC quartiles. After adjustment for confounding factors, the highest serum CysC level remained a significant risk factor for DR (odds ratio [OR], 1.929; 95% confidence interval [CI], 1.007 to 4.144; P=0.040). Compared with Q1, a significant positive association was observed between serum CysC and CHD in Q2 (OR, 7.321; 95% CI, 1.114 to 48.114; P=0.012), Q3 (OR, 6.027; 95% CI, 0.952 to 38.161; P=0.020), and Q4 (OR, 8.122; 95% CI, 1.258 to 52.453; P=0.007). No associations were observed between CysC and stroke after additional adjustment for confounding variables. Conclusion: Serum CysC levels are independently associated with DR and CHD, suggesting that CysC may be useful for identifying type 2 diabetes mellitus patients without nephropathy who are at high risk for vascular complications.