• The Journal of Information Technology
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• v.8 no.3
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• pp.105-115
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• 2005

The CMA and MMA blind equalization algorithm has the inevitable large residual error caused by mismatching between the symbol constellation at a steady state after convergence. Stop-and-Go algorithm has a very superior residual error characteristics at a steady state but a relatively slow convergence characteristics. In this paper, we propose a SAG-Flagged MMA as a new adaptive blind equalization algorithm with a Stop-and-Go flag which follows a flagged MMA in update scheme of tap weights as appling the flag obtaining from Stop-and-Go algorithm to MMA. Using computer simulation, it is confirmed that the proposed algorithm has an enhancing performance from the viewpoint of residual ISI, residual error and convergence speed in comparison with MMA and Stop-and-Go algorithm. Algorithm has a new error function using the decided original constellation instead of the reduced constellation. By computer simulation, it is confirmed that the proposed algorithm has the performance superiority in terms of residual ISI and convergence speed compared with the adaptive blind equalization algorithm of CMA family, Constant Modulus Algorithm with Carrier Phase Recovery and Modified CMA(MCMA).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.429-437
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• 2019

This paper deals with a ZEM (Zero-Effort-Miss) based guidance law for the interception of moving targets and characteristics of the guidance law according to time-to-go estimation methods. To derive the ZEM vector feedback guidance command, we introduce a polynomial function with unknown coefficient, and then we determine the coefficient to satisfy initial and terminal constraints. Since the directions of the guidance command and ZEM vectors are adjusted by the time-to-go, general time-to-go estimation methods are proposed, which can generate the vertical and horizontal guidance commands with respect to an arbitrary reference frame. By performing various numerical simulations, the performance and characteristics of the proposed methods are investigated.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.324-330
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• 2019

Petal-like nickel cobaltite ($NiCo_2O_4$)/reduced graphene oxide (rGO) composites with different $rGO-to-NiCo_2O_4$ weight ratios were synthesized using a simple hydrothermal method and subsequent thermal treatment. In the $NiCo_2O_4/rGO$ composite, the $NiCo_2O_4$ 3-dimensional nanomaterials contributed to the improvement of electrochemical properties of the final composite material by preventing the restacking of the rGO sheet and securing ion movement passages. The composite structure was examined by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and Fourier-transform infrared (FT-IR) spectroscopy. The FE-SEM and TEM images showed that petal-like $NiCo_2O_4$ was supported on the rGO surface. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were used for the electrochemical analysis of composites. Among the prepared composites, $0.075g\;rGO/NiCo_2O_4$ composite showed the highest specific capacitance of $1,755Fg^{-1}$ at a current density of $2Ag^{-1}$. The cycle performance and rate capability of the composite material were higher than those of using the single $NiCo_2O_4$ material. These nano-structured composites could be regarded as valuable electrode materials for supercapacitors that require superior performance.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.677-683
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• 2019

In this paper, nitrogen-doped reduced graphene oxide(rGO) is obtained by thermal annealing of nitrogen-containing compounds and graphene oxide (GO) manufactured by modified Hummers' method. We use melamine as a nitrogen-containing compound and treat GO thermally with melamine at over $800{\sim}1,000^{\circ}C$ and 1 ~ 3 hr under Ar atmosphere. The electrical conductivity of doped rGO is measured by 4-point probe method. As a result, nitrogen contents on rGO are found to be in the range of 2.5 to 12.5 at% depending on the doping conditions after thermal annealing. The main doping site on graphene oxide is changed from pyridinic-N and pyrrolinic N to the graphitic site as the heat treatment temperature increases. The electrical conductivity of doped rGO increases as the N doping content increases. As the thermal treatment time increases, the change of both total doping contents and doping sites is slight and the surface resistance is remarkably reduced, which is caused by healing effects of doped graphene oxide at high temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.31-32
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• 2019

In this study, oxidized graphene nanoplatelet(GO) was prepared by oxidizing graphene nanoplatelet(GNP) with nitric acid in order to solve the problem of dispersion of GNP, one of nano materials. GNP/Epoxy and GO/Epoxy paint were prepared by mixing GNP, GO with 0.1, 0.3, 0.5 and 1.0 wt.% in epoxy paint and the mechanical properties were evaluated. As a result, GNP/Epoxy and GO/Epoxy paints showed better mechanical properties than Neat Epoxy which did not incorporate GNP, GO. Especially, when 0.3 wt.% of GO was incorporated into epoxy resin, it showed higher tensile strength than Neat Epoxy. It was confirmed that acid treatment of GNP was effective in improving the mechanical properties of epoxy paint. However, graphene material was found that it was not effective in improving the bond performance of the epoxy paint.

• Advances in aircraft and spacecraft science
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• v.9 no.1
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• pp.69-93
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• 2022

Reduced graphene oxide (rGO) is one of the derivatives of graphene, which has drawn some experimental research interests in recent years however, numerical research studying the mechanical behaviors of composites made of rGO has not been taken into consideration yet. The objective of this research is to investigate the buckling, and free vibration of functionally graded reduced graphene oxide reinforced nanocomposite (FG rGORC) plates employing isogeometric analysis (IGA). The effective Young's modulus of rGORC is determined based onthe Halpin-Tsai model. Four different FG distribution types of rGO are considered varying across plate thickness. Besides, the refined plate theory is used based on Reddy's third-order function. To capture the size effect, modified couple stress theory (MCST) is employed. A comprehensive study is provided examining the effect of various parameters including rGO weight fraction, FG distribution types, boundary conditions, material length scale parameter, etc. Our obtained results show that the addition of only 1% of uniformly distributed rGO into epoxy plates leads to the fundamental frequency and critical buckling load 18% and 39% higher than those of pure epoxy plates, respectively.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.314-327
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• 2008

Objective: The purpose of this study was to evaluate the reproducibility of measurements representing asymmetry of the mandible and to identify which landmarks would be more useful in 3-dimensional (3D) CT imaging. Methods: Facial CT images were obtained from forty normal occlusion individuals. Eighteen landmarks were established from the condyle, gonion, and menton areas, and 25 measurements were constructed to represent asymmetry of the mandible; 8 for ramus length, 12 for mandibular body length, 1 for condylar neck length, 2 for frontal ramal inclination, and 2 for lateral ramal inclination. Inter- and intra-examiner reproducibility of the measurements was evaluated. Results: Inter-examiner reproducibility of the measurements proved to be high except for 3 measurements. Intra-examiner reproducibility also proved to be high except for 2 measurements. Inter- and intra-examiner reproducibility of the measurements including Gonion proved to be low. Conclusions: The results of the present study indicate that the landmarks and measurements constructed in 3D CT images can be used for the diagnosis of facial asymmetry.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.523-538
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• 1997

In order to investigate TMD prevalence in malocclusion patients and to study its relationship with occlusal factors, 205 malocclusion patients (M67, F138, 6Y1M-46Y8M) were examined. The following examinations were carried out, Questionnaire personal history, TMD symptoms, and the associated factors Clinical examination : TMJ sound and maximum mouth opening Orthopantomogram : condyle abnormalities, length of Co'-Inc' and Co'-Go', ratio Co'- Inc'/ Co'-Go', and depth of antegonial notch Transcranial view limitation of anterior movement of condyle Model Angle classification, overjet, overbite, midline discrepancy, missing of posterior teeth, posterior crossbite, attrition of palatal cusp of maxillary molars, crowding/spacing The results could be summarized as follows, 1. The prevalence of TMD showed that Helkimo Anamestic Inder(Ai) 0 was $46.8\%$, Ai I was $22.0\%$, Ai II was $31.2\%$ and subjective symptoms increased with aging (p<0.001) and were frequent in females (p<0.05). 2. Flattening ($4.4\%$) was the most frequent condyle abnormality on Orthopantomogram, and $8.3\%$ of subjects showed some abnormalities on Orthopantomogram. 3. The cases with neck and shoulder pain (p<0.001), clenching, lip biting (p<0.01), and headache (p<0.05) showed higher scores of Ai. 4. Angle class II showed high frequency of condylar abnormalities on Orthopantomogram, and subjects whose palatal cusp of maxillary molars had been attrided had the tendency to show high hi scores (p<0.05). The other occlusal factors had nothing to do with the symptoms of TMD. 5. In the cases that 1)the value of Co'-Inc', Co'-Go' or Co'-Inc'/Co'-Go' were low or 2)the differences of Co'-Go' or Co'-Inc'/Co'-Go' between the right and the left were large, condylar abnormalities were frequently obserbed on Orthopantomogram.

• Journal of Sasang Constitutional Medicine
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• v.11 no.2
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• pp.267-281
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• 1999

1. Purpose : The purpose of this study was to determine the effects of Taeyeumjoweetang on the cerebral neurons injured by glucose oxidase(GO). 2. Methods : I observed cell viability in mouse cerebral neurons exposed to glucose oxidase by NR assay and MTT assay and determined lipid peroxidation in mouse cerebral neurons exposed to glucose oxidase. After administration of Taeyeumjoweetang water extracts, I observed significant changes of cell viability, lipid peroxidation in mouse cerebral neurons exposed to glucose oxidase. 3. Results : GO induced cell degeneration such as the decrease of cell viability was measured by MTT and NR assay in the cultured mouse cerebral cortical neurons. Taeyeumjoweetang was effective in the increase of total protein of neurons inhibited by GO. Taeyeumjoweetang was effective in the decrease of lipid peroxidation of neurons produced by GO.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.5
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• pp.1016-1019
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• 2002

To examine the cytotoxic effect of glucose oxidase(GO) in cultured mouse cerebral neurons, cytotoxicity was measured by MTT assay after cultured nerve cells were incubated for 3 hours in the media containing 1 ～ 60mU/ml concentrations of GO. In addition, the neuroprotective effect of Ramulus et uncus uncariae(REUU) was determined by MTT assay in these cultrures. Cell viability was remarkably decreased in a dose- and time-dependent manner after cultured mouse cerebral neurons were exposed to 30mU/ml GO for 3 hours. In the neuroprotective effect of REUU on GO-induced toxicity, REUU blocked the GO-mediated neurotoxicity in these cultures. From above the results, it suggests that GO is toxic in cultured mouse cerebral neurons and selective herb extract such as REUU is effective in prevetion of the neurotoxicity induced by GO.