• KSTLE International Journal
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• v.2 no.2
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• pp.114-119
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• 2001

The distribution of magnetic flux density of electro-magnetic chucks may clarify the clamping characteristics, which is strongly related to the machining efficiency and machining accuracy in surface grinding machine. Therefore the distribution of the normal and the tangential components of magnetic flux density have been analyzed theoretically. It appears that the normal component of magnetic flux density increases and the tangential component of magnetic flux density increases as the ratio of the separator width to the pitch, e/p decreases. The results seem to increase the stability and uniformity of normal component of magnetic flux density for the decreased e/p.

• Computational Structural Engineering : An International Journal
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• v.1 no.2
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• pp.89-96
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• 2001

A study on the topology optimization of a Hard-Disk-Driver(HDD) actuator arm is presented. The purpose of the present wert is to increase the natural frequency of tole first lateral mode of the HDD actuator arm under the constraint of total moment of inertia, so as to facilitate the position control of the high speed actuator arm. The first lateral mode is an important factor in the position control process. Thus the topology optimization for 2-D model of the HDD actuator arm is considered. A new objective function corresponding to multieigenvalue optimization is suggested to improve the solution of the eigenvalue optimization problem. The material density of the structure is treated as the design variable and the intermediate density is penalized. The effects of different element types and material property functions on the final topology are studied. When the problem is discretized using 8-node element of a uniform density, tole smoothly-varying density field is obtained without checker-board patterns incurred. AS a result of 7he study, an improved design of the HDD actuator arm is suggested. Dynamic characteristics of the suggested design are compared computationally with those of the old design. With the same amount of the moment of inertia, the natural frequency of the first lateral mode of the suggested design is subsequently increased over the existing one.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.57-65
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• 2007

Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1801-1809
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• 2000

A study on the topology optimization of Hard-Disk-Driver(HDD) actuator arm in free vibration is presented. The purpose of this research is to increasse the natural frequency of the first lateral mode of the HDD actuator arm under the constraint of total moment of inertia, so as to facilitate the position control of high speed actuator am. The first lateral mode is an important factor in the position control process. Thus the topology optimization for 2-D model of the HDD actuator arm is considered. A new objective function corresponding to multieigenvalue optimization is suggested to improve the solution of the eigenvalue optimization problem. The material density of the structure is treated as the design variable and the intermediate density is penalized. The effects of different element types and material property functions on the final topology are studied. When the problem is discretized using 8-node element of a uniform density, the smoothly-varying density field is obtained without checker-board patterns incurred. As a result of the study an improved design of the HDD actuator arm is suggested. Dynamic characteristics of the suggested design are compared computationally with those of the old design. With the same amount of the moment of inertia, the natural frequency of the first lateral mode or the suggested design is subsequently increased over the existing one.

• Journal of Korean Association for Spatial Structures
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• v.10 no.4
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• pp.59-66
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• 2010

This study presents the topology optimization technique by density method to determine the initial shape of space truss structures. Most initial shape design is performed by designer's previous experiences and trial and error method instead of the application of reasonable optimization method. Thus, the reasonable and economical optimization methods are needed to be introduced for the initial shape design. Therefore, we set design domain for cantilever space truss structure as an example model. And topology optimization is used to obtain optimum layout for them, and then size optimization method is used to find the optimum member size. Therefore, the reasonable initial optimal shapes of spatial truss structures can be obtained through the topology and size optimization using density method.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.279-284
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• 2010

This paper surveys basic research for data base system of the fabric structural design. For this purpose, the weave density coefficients of the worsted and cotton fabrics are analysed and discussed with cover factors suggested by Prof. Walz and Picanol company. And the relationship between weave density coefficients and cover factors of the worsted and cotton woven fabrics was analysed and discussed with weave pattern and yarn count. Finally, the process shrinkages of dyeing and finishing processes according to the weave density coefficients of the worsted and cotton fabrics were analysed and discussed as a preliminary study for the data base system of the fabric structural design. As a result, the density coefficients, K values of the worsted and cotton fabrics were ranged from 600 to 1000, and the weave density coefficients of those fabrics are ranged from 0.4 to 0.8 and from 0.2 to 1.0, respectively. The finishing shrinkages for the worsted fabrics are ranged from 2% to 10%, and for cotton fabrics, it was from 2% to 20%. The weave density coefficients of the worsted and cotton fabrics could be distributed according to the looms, weave pattern and weaving and finishing shrinkages as a concept of the data base for the fabric structural design.

• Journal of the Korean Institute of Navigation
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• v.11 no.2
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• pp.53-59
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• 1987

This paper describes the design theory of a weakly-coupled Tap-off with high density of coupling intervals for CATV and/or MATV systems, by which the degree of freedom in design and density of coupling intervals are significantly increased compared with the intrinsic one. It is also described how to construct the two-way divider (Tap-off) in the generalized type. Furthermore, the practical measurements of the frequency characteristics for a fabricated circuit show very good agreements with theoretical results.

• International Journal of High-Rise Buildings
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• v.12 no.1
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• pp.75-82
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• 2023

By limiting population and land resources, a high-density urban form has become the inevitable choice for central cities in the rapid growth of many large cities in China. Due to the shift in urban growth and focus, high-density urban areas require restoration and improvement. This study intends to combine ancient and new districts, establish strategies for enhancing urban function, spatial utility, industry, and transportation, and thus enhance regional holistic effectiveness, by performing in-depth research.

• Journal of information and communication convergence engineering
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• v.12 no.3
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• pp.186-192
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• 2014

Monolithic three-dimensional integrated chips (3D ICs) are an emerging technology that offers an integration density that is some orders of magnitude higher than the conventional through-silicon-via (TSV)-based 3D ICs. This is due to a sequential integration process that enables extremely small monolithic inter-tier vias (MIVs). For a monolithic 3D memory, we first explore the static random-access memory (SRAM) design. Next, for digital logic, we explore several design styles. The first is transistor-level, which is a design style unique to monolithic 3D ICs that are enabled by the ultra-high-density of MIVs. We also explore gate-level and block-level design styles, which are available for TSV-based 3D ICs. For each of these design styles, we present techniques to obtain the graphic database system (GDS) layouts, and perform a signoff-quality performance and power analysis. We also discuss various challenges facing monolithic 3D ICs, such as achieving 50% footprint reduction over two-dimensional (2D) ICs, routing congestion, power delivery network design, and thermal issues. Finally, we present design techniques to overcome these challenges.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.912-920
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• 2006

The purpose of this study is to present the design standard for load density in subway station. From the data of electric equipment capacity and electric power consumption for 43 subway stations, current levels of the load density and excess capacity factor were surveyed and analyzed, In addition mean value, standard deviation, maximum value, median value and correlation coefficient were evaluated through excel program. Also it was carried out the regression analysis. The estimation method of load density and design criterion were studied. As a result, load density in this thesis have been proposed : 51.3 $[VA/m^2]$ on the general power load can be a standard value for subway station.