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Decision feedback equalizer for holographic data storage
Kim, Kyuhwan,Kim, Seung Hun,Koo, Gyogwon,Seo, Min Seok,Kim, Sang Woo The Optical Society 2018 Applied Optics Vol.57 No.15
<P>Holographic data storage (HDS) has attracted much attention as a next-generation storage medium. Because HDS suffers from two-dimensional (2D) inter-symbol interference (IST), the partial-response maximum likelihood (PRML) method has been studied to reduce 2D IST. However, the PRML method has various drawbacks. To solve the problems, we propose a modified decision feedback equalizer (DFE) for HDS. To prevent the error propagation problem, which is a typical problem in DFEs, we also propose a reliability factor for HDS. Various simulations were executed to analyze the performance of the proposed methods. The proposed methods showed fast processing speed after training, superior bit error rate performance, and consistency. (C) 2018 Optical Society of America</P>
Estimation of Electrode Consumption using Mast Position in Electric Arc Furnace
Kyuhwan Kim,Jae Jin Jeong,Taewon Kim,Sang Woo Kim 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
In order to automate the electrode replacement process, it is necessary to estimate the electrode consumption. Because the electrode controller lowers the electrode according to the electrode consumption, it is possible to estimate the consumption by measuring the position of the electrode. However, due to the structure of the electrode and the electrode arm, it is difficult to measure the electrode position directly. Thus we measured the position of the mast which holds up the electrode arm. In order to determine when to replace the electrode, it is necessary to know the consumption of the electrode per operation. So, we calculated the representative value of the mast position for every operation. Then, we analyzed the changing trend of the representative values of the mast position to estimate the electrode consumption. Also, because the arc length increases about 1 cm when the arc voltage increases 10 V, we modified the representative values and estimated the electrode consumption. The results which were obtained from the analysis of the mast position are in good agreement with the real operation pattern.
Kyuhwan Jung,우숙영,A Ran Kim,Kim Honsoul 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.2
Purpose: The purpose of this study was to elucidate whether contrast-enhanced ultrasonography (CEUS) can visualize orally administered Sonazoid leaking into the peritoneal cavity in a postoperative stomach leakage mouse model. Methods: Adult female mice (n=33, 9-10 weeks old) were used. Preoperative CEUS was performed after delivering Sonazoid via intraperitoneal injection and the per oral route. A gastric leakage model was then generated by making a surgical incision of about 0.5 cm at the stomach wall, and CEUS with per oral Sonazoid administration was performed. A region of interest was drawn on the CEUS images and the signal intensity was quantitatively measured. Statistical analysis was performed using a mixed model to compare the signal intensity sampled from the pre-contrast images with those of the post-contrast images obtained at different time points. Results: CEUS after Sonazoid intraperitoneal injection in normal mice and after oral administration in mice with gastric perforation visualized the contrast medium spreading within the liver interlobar fissures continuous to the peritoneal cavity. A quantitative analysis showed that in the mice with gastric perforation, the orally delivered Sonazoid leaking into the peritoneal cavity induced a statistically significant (P<0.05) increase in signal intensity in all CEUS images obtained 10 seconds or longer after contrast delivery. However, enhancement was not observed before gastric perforation surgery (P=0.167). Conclusion: CEUS with oral Sonazoid administration efficiently visualized the contrast medium spreading within the peritoneal cavity in a postoperative stomach leakage mouse model.
High Temperature Oxidation and Sulfidation of Ni-15at.%W Coatings
Chanwou Kim,Teayoul You,Yuriy Shapovalov,Jaehwang Ko,Dongbok Lee,Kyuhwan Lee,Doyon Chang,Dongsoo Kim,Sikchol Kwon 한국표면공학회 2005 한국표면공학회지 Vol.38 No.1
Ni-15at. %W coatings with film thicknesses of 20-40 ㎛ were electroplated on a steel substrate, and their oxidation behavior was investigated at 700 and 800℃ in air. For comparison, a pure Ni coating and a bulk Ni were also oxidized. The Ni-15at. %W coating displayed the worst oxidation resistance, due to the formation of less-protective NiO, Fe₂O₃, NiFe₂O₄and NiWO₄. The corrosion behavior Ni-15at.%W coatings electroplated on a steel substrate was similarly investigated at 700 and 800℃ in the Ar-1%SO₂ atmosphere. For comparison, the uncoated steel substrate was also corrosion-tested in the Ar-1%SO₂ atmosphere. Severe scale spallation and the internal corrosion of the steel that occurred in the uncoated substrate were not observed in the coated specimen. However, it seemed that the Ni-15at.%W coating cannot be a potential candidate as a sulfidation-resistant coating, due to the formation of less-protective NiO, NiS, WO₃ and NiWO₄.
Arc Stability Index Using Phase Electrical Power in AC Electric Arc Furnace
SeungHun Kim,Jae Jin Jeong,KyuHwan Kim,Jong Hyun Choi,Sang Woo Kim 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
In AC electric arc furnace, the state of the arc is a major concern to save the electrical power and to increase the productivity. There have been several researches about the arc stability index, such as the index based on the direct measurements of arc current and the index using the three-phase to ground voltage. In this paper, a modified index, which considers the concepts of both voltages and currents, is introduced. This index is the mapped phase electrical power by a mapping function, and the electrical power is calculated from the phase to ground voltages and currents. The simulations of various cases are performed, and the modified index shows a good performance in analyzing the arc state compared to existing index.