• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.417-423
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• 2011

Purpose: This study was to investigate that near gradient AC/A ratio could be used to prescribe a patient with distance exophoria, we compared the difference between distance gradient AC/A ratio and near gradient AC/A ratio. Also, this thesis was to understand the relationship between calculated AC/A ratio and gradient AC/A ratio. Methods: Objective and subjective refractive error were corrected and we used Howell (3 m) chart for distance phoria tests and Howell-Kim (40 cm) chart for near phoria tests. The near gradient AC/A ratio and calculated AC/A ratio were used by Howell-Kim (40 cm) combined with +1.00 D, -1.00 D, +2.00 D and -2.00 D. Results: The average value of distance exophoria was 1.17${\pm}$1.17 $\Delta$, and the average value of near exophoria was 3.71${\pm}$2.80 $\Delta$ (t-test. p<0.001). The correlation of distance phoria with near phoria was little higher (r = 0.59, p < 0.001). Gradient AC/A ratios depending on measuring distance and stimulus were higher (r = 0.11~0.53. P < 0.001), when distance was shorter and stimulus to accommodation was more. Also, stimulus to accommodation by plus lens was higher than stimulus to accommodation by minus lens (paired t-test. p < 0.001). There was negative correlation between calculated AC/A ratio and gradient AC/A ratio. As the calculated AC/A ratio was higher, gradient AC/A ratio was lesser. Near gradient AC/A ratio was slightly higher than distance gradient AC/A ratio. Distance and near gradient AC/A ratio taken through the subjective -1.00 D were 1.30 $\Delta$/D and 1.68 $\Delta$/D(t-test. t=1.67, p < 0.001). Conclusions: There is negative correlation between calculated AC/A ratio and gradient AC/A ratio. Also, there is subtle difference between near gradient AC/A ratio and distance gradient AC/A ratio. Therefore, we need to measure distance gradient AC/A ratio when a practitioner prescribe glasses for a patient with distance exophoria.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.4
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• pp.543-550
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• 2010

This study was conducted to determine the characteristics of chungkukjang with added isoflavone extracted from arrowroot and to determine its utility as a functional food substance. Crude isoflavone was prepared from arrowroot by the ethanol extraction method and frozen dried (AI). Samples of chungkukjang each had different amounts of isoflavone extracts added to them: 0 (control), 1.76 (AC1-chungkukjang), 3.52 (AC2-chungkukjang), and 7.11 (AC3-chungkukjang) g/kg. The pH, color, slime material content, calcium, and isoflavone of each sample were measured to investigate the quality and changes in isoflavone content. As AI increased, the pH of chungkukjang decreased to 7.46~7.53 compared to the pH of control (7.63). The slime material content range increased to 4.46~6.16%. However, there was no significant difference in the general components of chungkukjang between each of the groups (Con, AC1, AC2, AC3). In colors of chungkukjang, values for $L^*$, $a^*$, and $b^*$ decreased as AI increased. Meanwhile, the calcium content of AC1, AC2 and AC3 tended to increase by 11.18~12.82% compared to the control. This may be due to the influence of Ca in the arrowroot extract powder. There was a remarkable increase in total isoflavone content, by 30.81~130.66%, with an order of AC3>AC2>AC1. In all of the groups, the content of genistein and daidzein, aglycone form, increased dramatically, by 65.00~128.34%, and 89.38~142.91%, respectively, compared to the control. In AC3, in particular the genistin and daidzin content increased by 103.47% and 188.13%. These results showed that AI can be used as a source of isoflavone supplementation in chungkukjang.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.223-231
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• 2004

In most previous studies, the assessment of accommodative convergence to accommodative stimulus (AC/A) ratio was commonly made by measuring gradient AC/A ratio. This study deals with the proximal convergence/accommodation(PC/A)ratio measured by comparing values of the gradient AC/A ratio and the calculated AC/A ratio to prevail the clinical use of the AC/A ratio. Visual acuities of All 124 subjects had been corrected to at least 1.0 with either eye through their habitual refractive correction and the MEM dynamic retinoscopy was performed to estimate their accommodative response. And then the PC/A ratio was calculated by making use of the calculated AC/A ratio and the gradient AC/A ratio. This study showed that the difference between the mean calculated AC/A ratio and the mean gradient AC/A ratio in subgroups may be attributable to proximal convergence. Consequently, further studies on proximity cues including the PC/A ratio could be helpful to prevail the clinical use of the AC/A ratio.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.465-471
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• 2004

This study was designed to investigate the effect of a butanol (BuOH) fraction of Alisma canaliculatum (Ac) with/without vitamin E (VE) on glycogen, lipid levels and oxidative stress in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley rats were divided into 5 groups: normal, STZ-control, and 3 diabetic experimental groups. Diabetes was induced by injection of STZ (45 mg) into the tail vein. The BuOH fraction of Ac and VE were administrated orally in rats for 21 days: Ac group (400 mg), Ac-VE group (Ac 400 mg & vitamin E 10 mg) and VE group (10 mg). Liver and muscle glycogen levels decrease in STZ-control group versus normal group and these alteration in glycogen levels were prevented Ac-VE group and VE group. Oral administration of Ac or VE resulted in reduction in liver cholesterol. Liver triglycerides were significantly higher in the VE group than in STZ-control group. Liver malondialdehyde (MDA) was increase in STZ-control group compared to normal group, but that of Ac group and Ac-VE group were similar to normal group. Meanwhile MDA in kidney, lung and pancreas were not significantly different among five groups. Ac-VE group increase lung protein that were significantly higher than diabetic control rats. These results suggest that the VE could increase glycogen and triglyceride levels and BuOH fraction of Ac decrease MDA of liver in the diabetic rats. The use of Ac together with VE did not show better control hyperglycemia-induced oxidative stress.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.435-436
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• 2016

본 논문에서는 3상 Quasi Z-소스 AC/AC 전력변환기를 제안한다. 제안된 전력변환기는 3대의 단상 Quasi Z-소스 AC/AC 컨버터로 구성되어 있으며, 간단한 듀티 비 제어만으로도 동상 및 역상의 벅-부스트 출력 전압의 발생이 가능하다. 제안된 방식은 PSIM 시뮬레이션을 통하여 타당성을 확인하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.415-429
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• 2011

In this study, a single-phase quasi Z-source AC-AC converters with a series connection of the output terminals is proposed. The proposed system has configuration that the input terminals of two quasi Z-source AC-AC converters are connected in parallel and its output terminals are connected in series. The out of phase mode and in phase mode of the proposed system are presented. To verify the validity of the proposed converter, a DSP controlled hardware was made and PSIM simulation was executed. As a result, controlling the duty ratio of the converter, the desired buck-boost output voltages could be generated. For each modes, as compared with the single converter operation, the proposed converter could enhance the efficiency and input power factor according to different loads. Also, in case of the out of phase mode under the constant load, the efficiency and input power factor of the proposed system are increased 10[%], 35[%] respectively in compared with the single converter. And, the output voltage is constantly controlled in dynamic state in case while the load is suddenly changed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.6
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• pp.88-94
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• 2008

A DCT-based energy-ratio measure for autofocus in digital camera is proposed in this paper. This measure, namely AC2DC1 and AC5DC1, determines the sharpness of an image using a ratio between AC and DC energy in the DCT domain. This method is derived from energy analysis of DCT coefficients. Autofocus score calculation method is used to assess the performance of the proposed measure and to compare it with other measures. Experimental results under various conditions verify the robustness of the proposed focus measure for the Gaussian as well as impulsive noises.

• Composites Research
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• v.13 no.6
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• pp.1-8
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• 2000

The fabrication Process of $Al_2O_{3p}$/AC8A composites by pressureless infiltration technique and the effects of additive Mg content and volume fraction of particulate reinforcement on mechanical and wear properties were investigated. It was found that the bending strength decreased with increasing volume fraction of $Al_2O_{3p}$ particles. Whereas hardness increased with volume fraction of $Al_2O_{3p}$ particles. The decrement of strength in case of high volume fraction of $Al_2O_{3p}$ particles was attributed to high porosity level. In terms of additive Mg content, $Al_2O_{3p}$/AC8A composites containing around 5~7wt% of additive Mg indicated the highest strength, and hardness values increased with additive Mg contents. Wear resistance of AC8A alloy were improved by reinforcement of $Al_2O_{3p}$ particles especially at high sliding velocity. Wear property of $Al_2O_{3p}$/AC8A composites and AC8A alloy exhibited different aspects. $Al_2O_{3p}$/AC8A composites indicated more wear loss than AC8A alloy at slow velocity region. However a transition point of wear loss was found at middle velocity region which shows the minimum wear loss and wear loss at high velocity region exhibited almost same value as at slow velocity region, whereas wear loss of AC8A alloy almost linearly increased with sliding velocity. It was found that $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 20% exhibited abrasive wear surface regardless of sliding velocity and $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 40% showed slightly adhesive wear surface at low sliding velocity, and it progressed to severe wear as increasing the sliding velocity.

• Korean Journal of Materials Research
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• v.2 no.6
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• pp.461-467
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• 1992

A fabrication process for SiC whisker preform reinforced AC4A Al composites is being developed. The Al alloy used as the matrix in this study is AC4A. SiC whisker preform made by Tokai Carbon Co. Ltd. Shizuoka, Japan were used. These consisted of $\beta$-type single crystals 0.1 ~ 10${\mu}$m in diameter and 20~10${\mu}$m in length. The most adequate fabrication condition was that whisker preform was preheated up to 750~80$0^{\circ}C$, set into a mould preheated to ~40$0^{\circ}C$, molten Al alloy heated to ~80$0^{\circ}C$ and applied pressure 75MPa. And Si$C_w$reinforced AC4A composite was advanced above twice than AC4AI/M. Also it was not large effect by pressure at Si$C_w$ 20v/o.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.382-390
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• 1998

Purpose: The purpose of this study was to evaluate the accuracy of radioactivity quantitation in Tc-99m SPECT by using combined scatter and attenuation correction. Materials and Methods: A cylindrical phantom which simulates tumors (T) and normal tissue (B) was filled with varying activity ratios of Tc-99m. We acquired emission scans of the phantom using a three-headed SPECT system (Trionix, Inc.) with two energy windows (photopeak window: $126{\sim}154keV$ and scatter window: $101{\sim}123keV$). We performed the scatter correction with dual-energy window subtraction method (k=0.4) and Chang attenuation correction. Three sets of SPECT images were reconstructed using combined scatter and attenuation correction (SC+AC), attenuation correction (AC) and without any correction (NONE). We compared T/B ratio, image contrast [(T-B)/(T+B)] and absolute radioactivity with true values. Results: SC+AC images had the highest mean values of T/B ratios. Image contrast was 0.92 in SC+AC, which was close to the true value of 1, and higher than AC (0.77) or NONE (0.80). Errors of true activity by SPECT images ranged from 1 to 11% for SC+AC, $22{\sim}47%$ for AC, and $2{\sim}16%$ for NONE in a phantom which was located 2.4cm from the phantom surface. In a phantom located 10.0cm from the surface, SC+AC underestimated by 24%, NONE 40%. However, AC overestimated by 10%. Conclusion: We conclude that accurate SPECT activity quantitation of Tc-99m distribution can be achieved by dual window scatter correction combind with attenuation correction.