• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.485-489
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• 2006

In this paper, we slightly improve the Baby-step Giant-step for certain elliptic curves. This method gives the running time improvement of $200\%$ in precomputation (Baby-step) and requires half as much storage as the original Baby-step Giant-step method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.234-235
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• 2017

In order to improve the frictional resistance of existing high-speed planning hull, a step-like linear transformation has been researched which forms an air layer on the bottom. However, there is a lack of research on the proper position to confirm the effect of Running Attitude and step on each position. In this study, we confirmed the change of the Running Attitude, the effect of the step and the change of the frictional resistance when the step was applied in the longitudinal location.

• Korean Journal of Materials Research
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• v.34 no.2
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• pp.116-124
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• 2024

In this study, we investigated the microstructure and piezoelectric properties of 0.96(K_0.456Na_0.536)Nb_0.95Sb_0.05-0.04Bi_0.5(Na_0.82K_0.18)_0.5ZrO₃ (KNNS-BNKZ) ceramics based on one-step and two-step sintering processes. One-step sintering led to significant abnormal grain (AG) growth at temperatures above 1,085 ℃. With increasing sintering temperature, piezoelectric and dielectric properties were enhanced, resulting in a high d₃₃ = 506 pC/N for one-step specimen sintered at 1,100 ℃ (one-step 1,100 ℃ specimen). However, for one-step 1,115 ℃ specimen, a slight decrease in d₃₃ was observed, emphasizing the importance of a high tetragonal (T) phase fraction for superior piezoelectric properties. Achieving a relative density above 84 % for samples sintered by the one-step sintering process was challenging. Conversely, two-step sintering significantly improved the relative density of KNNS-BNKZ ceramics up to 96 %, attributed to the control of AG nucleation in the first step and grain growth rate control in the second step. The quantity of AG nucleation was affected by the duration of the first step, determining the final microstructure. Despite having a lower T phase fraction than that of the one-step 1,100 ℃ specimen, the two-step specimen exhibited higher piezoelectric coefficients (d₃₃ = 574 pC/N and k_p = 0.5) than those of the one-step 1,100 ℃ specimen due to its higher relative density. Performance evaluation of magnetoelectric composite devices composed of one-step and two-step specimens showed that despite having a higher g₃₃, the magnetoelectric composite with the one-step 1,100 ℃ specimen exhibited the lowest magnetoelectric voltage coefficient, due to its lowest k_p. This study highlights the essential role of phase fraction and relative density in enhancing the performance of piezoelectric materials and devices, showcasing the effectiveness of the two-step sintering process for controlling the microstructure of ceramic materials containing volatile elements.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.313-322
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• 2018

The height of the steps was almost the same as the grain size of bed materials and increased with channel slope. The step widths and step wavelengths are almost the same size, and the step wavelength was decreased when the channel slope was increased. It was analyzed that there was a clear correlation between channel width and step width, and the step width increases with channel width. In addition, the step wavelength was scaled by channel width, and the step height is governed by the grain size of the rock forming the step, so that the profile structure of the step-pool was changed according to the channel slope. the scale of the pool was found to be highly correlated with the channel width, grain size, and slope gradient. Therefore, the characteristics of step-pool structure in mountain streams were influenced by various factors, but it can be explained as the grain size, channel width and channel slope.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.317-320
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• 2005

기존의 블라인드 등화(blind equalization) 알고리즘의 step-size는 임의의 값을 알고리즘에 적용하여 수렴속도와 정상 상태의 특성을 고려하여 최적한 step-size를 결정하였다. step-size를 크게 하면 수렴속도는 빠른 반면에 정상 상태에서 에러가 크고, step-size를 작게 하면 수렴속도는 느린 반면에 정상 상태에서 에러가 작아진다. 그렇기 때문에 수렴속도와 정상 상태를 고려해서 step-size를 결정해야 되고, 특별하게 정해지는 기준이 없기 때문에 연구자의 판단에 의해서 다르게 선택된다. 본 논문에서는 등화기 출력의 잔류 심벌간 간섭에 따라 step-size를 가변함으로서 수렴속도 및 정상 상태 성능을 개선한 가변 step-size를 갖는 블라인드 등화 알고리즘을 제안한다.

• Mycobiology
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• v.39 no.1
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• pp.67-69
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• 2011

A cell-free extract of Saccharomyces cerevisiae containing the angiotensin I-converting enzyme (ACE) inhibitory peptide was treated in a successive simulated gastric-intestinal bioreactor (step 1: amylase digestion, step 2: gastric fluid digestion, step 3: intestinal fluid digestion) to illustrate the absorption pattern of antihypertensive ACE inhibitory peptide, and the ACE inhibitory activities of each step were determined. Total ACE inhibitory activities of step 1, step 2, and step 3 were 55.96%, 80.09%, and 76.77%, respectively. The peptide sequence of each steps was analyzed by MS/MS spectrophotometry. Eleven kinds of representative peptide sequences were conserved in each step, and representative new peptides including RLPTESVPEPK were identified in step 3.

• Journal of applied mathematics & informatics
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• v.28 no.3_4
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• pp.773-781
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• 2010

Recently, Yun [8] proposed a new three-step iterative method with the fourth-order convergence for solving nonlinear equations. By using his ideas, we develop a general form of multi-step iterative methods with higher order convergence for solving nonlinear equations, and then we study convergence analysis of the multi-step iterative methods. Lastly, some numerical experiments are given to illustrate the performance of the multi-step iterative methods.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.67-74
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• 2014

This study researched into the left-right inclination of the rear foot at the lower limb joints, knee joint angle, angular velocity of the knee joint, angular acceleration and the max. Based on the analysis of kinematics according to the changes in the height of step box (6, 8, 10 inches) during step aerobics of female college students majoring in physical education. The findings of this study are as follows: Then angle of the knee joint decreased as the height of the step box increased the min. Angle was measured right before the right foot was on the step box, and the angle tended to decrease as the step box get heightened. The left-right inclination of the rearfoot angle according to the height of step box increased as the height increased. In the 'pull-up' stage during which the weight was loaded on the right foot the angle increased, while in the right foot stepping stage during which the right foot was on the ground, the left-right inclination of the rearfoot angle increased as the height of the step box increased. The angular velocity of the knee joint according to the height of step box started increasing when the right foot initially stepped on the step box and during the initial stepping section, the angular velocity decreased as the height of step box increased. The changes in angular acceleration of the knee joint according to the height of step box increased as the height of step box increased.

• Journal of Veterinary Clinics
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• v.35 no.2
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• pp.39-45
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• 2018

We evaluated the effects of green tea extract (GTE) supplementation at different dilution steps on boar sperm freezing and in vitro fertilization. Sperm intracellular hydrogen peroxide ($H_2O_2$), motility, viability, acrosome integrity and morphology were determined. In addition, sperm IVF parameters (penetration and monospermy) and glutathione (GSH) levels of presumptive zygotes (PZs) were evaluated. Semen was diluted in lactose egg yolk (LEY) and cooled at $5^{\circ}C$ for 3 h (first dilution step) and then diluted in LEY with 9% glycerol and maintained at $5^{\circ}C$ for 30 min (second dilution step). Four experimental groups were compared: first and second dilution steps without GTE (control), first dilution step with GTE (Step 1), second dilution step with GTE (Step 2) and first and second dilution step with GTE (Step 1+2). The spermatozoa were frozen in nitrogen vapor. Higher sperm motility, viability and acrosome integrity after thawing were observed in Step 1, Step 2 and Step 1+2 groups compared with the control (P < 0.05). Lower $H_2O_2$ level was observed in Step 1+2 compared with control and Step 1 (P < 0.05). For IVF, matured oocytes were co-cultured with spermatozoa frozen according to the experimental groups. GSH levels of PZs were significantly higher in Step 2 and Step 1+2 than in control and Step 1 (P < 0.05) without a significant difference in IVF parameters. In conclusion, supplementation with GTE in both first and second dilution steps during the freezing process resulted in better boar sperm cryopreservation and might be beneficial for further embryo development.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.89-94
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• 2016

In this study, the crystalline property of a-plane GaN epitaxial layer grown on r-plane sapphire by a HVPE method has been investigated according to the V/III ratio and the growth time of multi-step growth. Furthermore, these results were compared with the previous result obtained from the single-step growth of a-plane GaN on r-plane sapphire substrate. In the multi-step growth for a-plane GaN epitaxial layer on r-plane sapphire, the FWHM values of rocking curve in GaN epitaxial layer were decreased as the HCl source flow rate and the growth time were increased. The void formed in epitaxial layer was continuously decreased as the growth time in first step and second step using a higher HCl flow rate was increased. As a result, the GaN layer obtained with the longest growth time on the first step and second step exhibited the lowest FWHM values of 584 arcsec and the smallest dependence of azimuth angle.