• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.237-241
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• 2002

In this paper, we describe how to represent hand witten decimal digits by a sequence of one to five fuzzy sets. Each fuzzy set represents an arc segment of the digit and is a Cartesian product of four fuzzy sets; the first is fur the arc length of the segment, the second is for the arc direction, the third is fur the arc shape, and the fourth is a crisp number indicating whether it has a junction point and if it has an end point of a stroke. We show that an arbitrary pair of these sequences representing two different digits is mutually disjoint. We also show that various forms of a digit written in different styles can be represented by the same sequence of fuzzy sets and hence the deviations due to different writers can be modeled by using these fuzzy sets.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.612-615
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• 2002

The main advantages of Disk type Single-Phase Switched Reluctance Motor (DSPSRM) is the simple construction, rugged structure, low manufacturing cost and simple driving circuit. It is especially possible to make the short axial length of DSPSRM. Therefore, it is suitable to setup this motor in a narrow space. This paper presents the shape design to maximize the average torque of DSPSRM that is achieved by 3D Finite Element Method (3D FEM) considering the nonlinear of magnetic material. The characteristics of two different rotor shapes are compared. The design parameters, such as the rotor and stator pole arc, are selected to the parametric study. The effect of pole arc ratios on the torque performance is investigated. From these results, the optimal pole arc to produce the maximum torque is determined.

• Advances in nano research
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• 제9권4호
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• pp.277-294
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• 2020

In current paper, nonlocal (NLT), nonlocal strain gradient (NSGT) and Gurtin-Murdoch surface/interface (GMSIT) theories with classical theory (CT) are utilized to investigate vibration and stability analysis of Double Walled Piezoelectric Nanosensor (DWPENS) based on cylindrical nanoshell. DWPENS simultaneously subjected to direct electrostatic voltage DC and harmonic excitations, structural damping, two piezoelectric layers and also nonlinear van der Waals force. For this purpose, Hamilton's principle, Galerkin technique, complex averaging and with arc-length continuation methods are used to analyze nonlinear behavior of DWPENS. For this work, three nonclassical theories compared with classical theory CT to investigate Dimensionless Natural Frequency (DNF), pull-in voltage, nonlinear frequency response and stability analysis of the DWPENS considering the nonlocal, material length scale, surface/interface (S/I) effects, electrostatic and harmonic excitation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.824-827
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• 2003

Recently, Development of Rare Earth Permanent magnet with the high remanence, high coercivity allow the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to the machines output ripple, vibration, and noise. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, Some airgap length and magnet arc that reduce cogging torque are found by FEM(Finite element method). The SPM type of high-capacity BLDC motor is optimized as a sample model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.107-109
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• 2001

The salient pole rotor type single phase SRM has a salient pole in the rotor in order to use axial direction fluxes and radial direction fluxes simultaneously. A flux linkage between the rotor and the stator are increased because of the salient pole in the rotor. But, the inductance at unaligned position and aligned position is increased together. Therefore, the length of pole are and salient pole should be selected that the inductance increment at aligned position is higher than the inductance increment at unaligned position. On this paper, we will be studied the influence of the pole arc and the salient pole length on the torque of the salient pole rotor type single phase SRM.

• Carbon letters
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• 제11권3호
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• pp.184-191
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• 2010

Carbon nanotubes are unique tubular structures of nanometer diameter and large length/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ~0.34 nm. Multiwalled carbon nanotubes were synthesized by arc-discharge technique. MWCNTs were formed at the cathode deposit along with other carbonaceous materials like amorphous carbon, graphite etc. However, to get the best advantage of carbon nanotubes in various advanced applications, these undesired carbonaceous materials to be removed which is a challenging task. In the present study, various techniques were tried out for purifying MWCNTs such as physical filtration, chemical treatment and thermal annealing. SEM, FTIR, TGA and BET techniques were used to characterize the CNTs at various stages. Results shows that suitable chemical treatment followed by thermal annealing under controlled flow of oxygen gives the better route for purification of carbon nanotubes.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.189-200
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• 2015

In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

• 한국물환경학회지
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• 제24권2호
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• pp.147-155
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• 2008

Because of increased nonpoint source runoff potential at highland agricultural fields of Kangwon province, effective agricultural management practices are required to reduce the inflow of sediment and other nonpoint source pollutants into the water bodies. The watershed-scale model, Soil and Water Assessment Tool (SWAT), model has been used worldwide for developing effective watershed management. However, the SWAT model simulated sediment values are significantly affected by the number of subwatershed delineated. This result indicates that the SWAT estimated watershed characteristics from the watershed delineation process affects the soil erosion and sediment behaviors. However, most SWAT users do not spend time and efforts to analyze variations in sediment estimation due to watershed delineation with various threshold value although topography falsification affecting soil erosion process can be caused with watershed delineation processes. The SWAT model estimates the field slope length of Hydrologic Response Unit (HRU) based on average slope of subwatershed within the watershed. Thus the SWAT ArcView GIS Patch, developed by using the regression relationship between average watershed slope and field slope length, was utilized in this study to compare the simulated sediment from various watershed delineation scenarios. Four watershed delineation scenarios were made with various threshold values (700 ha, 300 ha, 100 ha, and 75 ha) and the SWAT estimated flow and sediment values were compared with and without applying the SWAT ArcView GIS Patch. With the SWAT ArcView GIS Patch applied, the simulated flow values are almost same irrespective of the number of subwatershed delineated while the simulated flow values changes to some extent without the SWAT ArcView GIS Patch applied. However when the SWAT ArcView GIS Patch applied, the simulated sediment values vary 9.7% to 29.8% with four watershed delineation scenarios, while the simulated sediment values vary 0.5% to 126.6% without SWAT ArcView GIS applied. As shown, the SWAT estimated flow and sediment values are not affected by the number of watershed delineation significant compared with the estimated flow and sediment value without applying the SWAT ArcView GIS Patch.

• East Asian mathematical journal
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• 제10권2호
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• pp.255-260
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• 1994

• 공업화학
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• 제22권1호
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• pp.31-36
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• 2011

사불화탄소($CF_4$)는 반도체 제조공정에서 플라즈마 에칭과 화학기상증착(CVD)에서 사용되어온 가스이다. $CF_4$는 적외선을 강하게 흡수하고 대기 중 잔류시간이 길어서 지구온난화에 영향을 미치기 때문에 고효율의 분해가 필요하다. 본 연구에서는 플라즈마와 워터젯을 결합하여 방전영역을 증가시키고 다량의 OH 라디칼을 생성시켜 $CF_4$를 고효율로 분해할 수 있는 워터젯 글라이딩 아크 플라즈마 시스템을 개발하였다. 실험 변수로 전극 형태, 전극 각도, 가스 노즐직경, 전극 간격과 전극 길이를 취하였다. 변수실험을 통하여 Arc 형태의 전극에서 전극 각도가 $20^{\circ}$, 가스 노즐 직경이 3 mm, 전극 간격이 3 mm, 전극 길이가 120 mm일 때 $CF_4$ 분해율은 최고 93.4%까지 도달하였다.