• ETRI Journal
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• v.33 no.2
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• pp.219-229
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• 2011

In this paper, we propose a transformation scheme used to analyze online gaming traffic properties and develop a traffic model. We analyze the packet size and the inter departure time distributions of a popular first-person shooter game (Left 4 Dead) and a massively multiplayer online role-playing game (World of Warcraft) in order to compare them to the existing scheme. Recent online gaming traffic is erratically distributed, so it is very difficult to analyze. Therefore, our research focuses on a transformation scheme to obtain new smooth patterns from a messy dataset. It extracts relatively heavy-weighted density data and then transforms them into a corresponding dataset domain to obtain a simplified graph. We compare the analytical model histogram, the chi-square statistic, and the quantile-quantile plot of the proposed scheme to an existing scheme. The results show that the proposed scheme demonstrates a good fit in all parts. The chi-square statistic of our scheme for the Left 4 Dead packet size distribution is less than one ninth of the existing one when dealing with erratic traffic.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.251-268
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• 2007

A Gaussian sum filter (GSF) is proposed in this paper on simultaneous localization and mapping (SLAM) for mobile robot navigation. In particular, the SLAM problem is tackled here for cases when only bearing measurements are available. Within the stochastic mapping framework using an extended Kalman filter (EKF), a Gaussian probability density function (pdf) is assumed to describe the range-and-bearing sensor noise. In the case of a bearing-only sensor, a sum of weighted Gaussians is used to represent the non-Gaussian robot-landmark range uncertainty, resulting in a bank of EKFs for estimation of the robot and landmark locations. In our approach, the Gaussian parameters are designed on the basis of minimizing the representation error. The computational complexity of the GSF is reduced by applying the sequential probability ratio test (SPRT) to remove under-performing EKFs. Extensive experimental results are included to demonstrate the effectiveness and efficiency of the proposed techniques.

• The Korean Journal of Ceramics
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• v.6 no.4
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• pp.354-358
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• 2000

The SnO$_2$film was deposited on a corning glass 1737 substrate by plasma enhanced chemical vapor deposition using a gas mixture of SnCl$_4$, $O_2$, and Ar. The film thickness was measured using $\alpha$-step and was about 9400$\AA$. The conventional X-ray diffractometry and pole figure attachment were used to refine the crystal structure of SnO$_2$ thin film. Six pole figures, (200), (211), (310), (301), (321), and (411), were measured with CoK$_\alpha$ radiation in reflection geometry. The X-ray diffraction data were measured at room temperature using CuK$_\alpha$ radiation with graphite monochromator. The agreement between calculated and observed patterns for the normal direction of SnO$_2$ thin film was not satisfactory due to the severely preferred orientation effect. The Rietveld refinement of heavily textured SnO$_2$ thin film was successfully achieved by adopting the pole density distribution of each reflection obtained from the inverse pole figure as a correction factor for the preferred orientation effect. The R-weighted pattern, R$_wp$, was 15.30%.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.141-148
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• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.493-493
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• 2022

본 연구는 식생밀도와 흐름에 따른 수치모형(Nays2D) 하상변동 모의 결과를 서식처 적합도 분석 모델(PHABSIM:Phsical Habtiat Suitability Model)의 입력자료로 활용하여, 식생밀도에 따른 하상 지형 변화가 어류 서식처 적합도에 미치는 영향을 검토한다. 금강 부용리 인근 2km를 대상으로 2차원 모형인 Nays2D를 적용하여 흐름(댐 방류량, 2년 빈도 유량, 100년 빈도 유량 등)과 식생밀도(식생미반영, 현재 밀도, 밀도 감소, 밀도 증가 등)에 따른 하상변동 모의를 실시하였고, 모의 결과값(단면 표고, 유속, 수위)을 물리적 서식처 평가 모델인 PHABSIM의 입력자료로 활용하였다. 피라미 서식을 위한 적정 유속과 수심의 서식처 적합도 지수를 이용하여 각 시나리오 별가중가용면적(WUA: Weighted Usable Area)을 산정하여 비교 분석하여, 식생밀도에 따른 단면 구조의 변화가 WUA 면적과 피라미 서식처 적합도에 어떻게 영향을 미치는지 검토하였다. 그 결과, 수목 밀도를 미반영한 하상변동 모의 결과를 PHABSIM의 입력 자료로 활용하였을 때 가중가용면적이 가장 높았고, 식생 밀도를 증가시킨 하상변동 모의 결과를 입력 자료로 활용하였을 때 WUA값이 가장 낮게 나타났다. 이는 피라미의 서식처 적합도 측면에서 식생이 적어 특정 유량에 따른 하상변동의 폭이 커지면서 저수로 최저하상과 고수부 하상과의 표고차가 상대적으로 낮은 하상 단면이 피라미의 서식처 측면에서 유리할 가능성이 있음을 시사한다.

• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.124-133
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• 2018

We tried to investigate the changes in cortical activities according to emotional valence states during watching video clips. We examined the neural basis of two emotional states (positive and negative) using spectral power analysis and brain functional connectivity analysis of cortical current density time-series reconstructed from high-density electroencephalograms (EEGs). Fifteen healthy participants viewed a series of thirty-two 2 min emotional video clips. Sixty-four channel EEGs were recorded. Distributed cortical sources were reconstructed using weighted minimum norm estimation. The temporal and spatial characteristics of spectral source powers showing significant differences between positive and negative emotion were examined. Also, correlations between gamma-band activities and affective valence ratings were determined. We observed the changes of cortical current density time-series according to emotional states modulated by video clip. Gamma-band activities showed significant difference between emotional states for thirty seconds at the middle and the latter half of the video clip, mainly in prefrontal area. It was also significantly anti-correlated with the self-ratings of emotional valence. In addition, the gamma-band activities in frontal and temporal areas were strongly phase-synchronized, more strongly for negative emotional states. Cortical activities in frontal and temporal areas showed high spectral power and inter-regional phase synchronization in gamma-band during negative emotional states. It is inferred that the higher amygdala activation induced by negative stimuli resulted in strong emotional effects and caused strong local and global synchronization of neural activities in gamma-band in frontal and temporal areas.

• Applied Microscopy
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• v.27 no.3
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• pp.265-279
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• 1997

This study aims to demonstrate the effect of chitosan, one of the natural chelator, on the ultrastructural changes in the mouse liver caused by cadmium. A total of 60 healthy ICR that weighted 30 gm $({\pm}2gm)$ was used for experiment. The experimental group was divided into three groups; group A, B, and C. The group A and B administrated cadmium (4.0 mg/kg) to the intraperitoneal after pretreated with chitosan (0.5% solution) for 30 and 7 days, respectively. Each group was observed at 12, 24, 48, 72 hours and one week after injected cadmium. The results were as follows: 1. Group A The nuclear membrane and the chromatin were normal shapes at overall the time. The inner and outer membranes of the mitochondria damaged a little but almost normal in shapes. And electron-density showed slightly compacted. some enlarged rER (rough endoplasmic reticulum) showed at 12 hours. At 48 hours, typical lamellae of the rER were reformed, and a lot of transvesicles observed around them. To 48 hours, sER (smooth endoplasmic reticulum) was slightly dilated. From 72 hours, sER rehalizated in normal shape. 2. Group B Nuclear membranes were rounded-shape and chromatin showed evenly. To 72 hours, a lot of mitochondria observed around rER and development of cristae showed weakly. But at one week, cristae were clear and electron-density of matrix showed high. At 72 hours lamellae of rER showed some broken, but were reformed at one week. Also at one week, glycogen granules evenly showed over cytoplasm. 3. Group C At 12 hours, Nucleus showed the condensation of nuclear membrane and clear condensation at 24 hours. However, nuclear membrane had a slightly rounded-shape from 72 hours. From 12 hours to the one week, mitochondria showed the dilation of inner cavity and weak development of cristae. Also electron-density of matrix was a little low. Occasionally, destruction of inner and outer membrane observed at one week. The dilation of cisternae and destruction of lamellae of rER showed from 12 to 48 hours. From 72 hours, rER showed slightly dilated only. And lamella observed at one week. In sER, dilation of inner cavity was observed during whole period. These results suggest that chitosan attenuates the toxic effect of the cadmium in the mouse liver.

• Journal of Soil and Groundwater Environment
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• v.28 no.6
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• pp.71-89
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• 2023

A groundwater potential map (GPM) was built for the Nakdonggang River Basin based on ten variables, including hydrogeologic unit, fault-line density, depth to groundwater, distance to surface water, lineament density, slope, stream drainage density, soil drainage, land cover, and annual rainfall. To integrate the thematic layers for GPM, the criteria were first weighted using the Analytic Hierarchical Process (AHP) and then overlaid using the Technique for Ordering Preferences by Similarity to Ideal Solution (TOPSIS) model. Finally, the groundwater potential was categorized into five classes (very high (VH), high (H), moderate (M), low (L), very low (VL)) and verified by examining the specific capacity of individual wells on each class. The wells in the area categorized as VH showed the highest median specific capacity (5.2 m³/day/m), while the wells with specific capacity < 1.39 m³/day/m were distributed in the areas categorized as L or VL. The accuracy of GPM generated in the work looked acceptable, although the specific capacity data were not enough to verify GPM in the studied large watershed. To create GPMs for the determination of high-yield well locations, the resolution and reliability of thematic maps should be improved. Criterion values for groundwater potential should be established when machine learning or statistical models are used in the GPM evaluation process.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.21-30
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• 2005

Traffic volume data have been used for the plan, the design, and the operation of highway. Since 1955, traffic survey has been nation- widely carried out at national highway and the regular survey in national highway has been conducted at the intersections of highways. However, it is critical issue to select the priority of the regular survey because it is almost impossible to conduct regular survey at all intersections of national highways. In this study, MCDM(Multiple Criteria Decision Making) using AHP(Analytic Hierarchy Process) was applied to decide the priority of the regular survey. The following standard variables for determining the priority was selected the highway plan variables[AADT, VKT, Peak Hourly Volume, Location of highway from Urban], the highway design variables[Volume(pcu), Directional Traffic Volume, Heavy Vehicle Rate], and the highway operation variables[Speed, Density, V/C]. The standard variables were quantified and normalized. Using the Eigen vector method, the weighted values of each hierarchy based on the pair-wise comparison values from the questionnaire survey were calculated. The selection of the priority of regular survey was dependent on the size of the product of the weighted values for each hierarchy and the normalized values for the standard variables. Finally, the priority of regular survey of the intersections of national highways was determined according to the order in the size of the product of two values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.189-189
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• 2008

Due to the environmental issue vast research is going on to replace the widely used lead contented piezoelectric materials. Bismuth sodium titanate (abbreviated as BNT) based bismuth sodium titanate-barium titanate (abbreviated as BNBT) ceramic was prepared by using modified method rather than conventional mixed oxide method. This modification was made to improve the properties of BNT based ceramic. In this procedure $BaTiO_3$ (abbreviated as BT) was prepared using conventional mixed oxide method. Analytical grade raw materials of $BaCO_3$ and $TiO_2$ were weighted and ball milled using ethanol medium. The mixed slurry was dried and sieved under 80 mesh. Then the powder was calcined at $1100^{\circ}C$ for 2 hours. This calcined BT powder was used in the preparation of BNBT. Stoichiometric amount of $Bi_2O_3$, $Na_2CO_3$, $TiO_2$ and BT were weighted and mixed by using ball mill. The used calcination temperature was $850^{\circ}C$ for 2 hours. Calcined powder was taken for another milling step. BNBT disks were pressed to 15 mm of diameter and then cold isostatical press (CIP) was used. Pressed samples were sintered at $1150^{\circ}C$ for 2 hours. The SEM microstructure analysis revealed that the grain shape of the sintered ceramic was polyhedral and grain boundary was well matched where as the sample prepared by conventional method showed irregular arrangement and grain boundary not well matched. And sintered density was better (5.78 g/cc) for the modified method. It was strongly observed that the properties of BNBT ceramic near MPB composition was found to be improved by the modified method compare to the conventional mixed oxide method. The piezoelectric constant dB of 177.33 pC/N, electromechanical coupling factor $k_p$ of 33.4%, dielectric constant $K_{33}^T$ of 688.237 and mechanical quality factor $Q_m$ of 109.37 was found.