• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.647-654
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• 2002

This study deals with the characteristic of quenching refrigerant for heat treatment deformation control of SM45C steel. Heat-treatment deformation must be controlled for the progress of production parts for landing gear. Most of deformation is occurred on inconsistent cooling. The inconsistent cooling is caused by a property of quenching refrigerant. When a heated metal is deposited in the quenching refrigerant, the cooling speed is so slow in early period of cooling because of a steam-curtain. After additional cooling, the steam-curtain is destroyed. In this progress, the cooling speed is very fast. The object of this study is to control the deformation of heat-treatment for landing gear by improving the conditions of quenching. The cooling curves and cooling rates of water, oil and polymer solution are obtained and illustrated. From the characteristics of the quenching refrigerant, the effects of heat-treatments on thermal deformation and fatigue strength are also investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.969-974
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• 2003

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a dc voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to 1 $\mu\textrm{m}$ at an airgap of 100 $\mu\textrm{m}$

• The Journal of the Acoustical Society of Korea
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• v.27 no.1E
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• pp.30-34
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• 2008

An improvement to the existing blind signal separation (BSS) method has been made in this paper. The proposed method models the inherent signal dependency observed in acoustic object to separate the real-world convolutive sound mixtures. The frequency domain approach requires solving the well known permutation problem, and the problem had been successfully solved by a vector representation of the sources whose multidimensional joint densities have a certain amount of dependency expressed by non-spherical distributions. Especially for speech signals, we observe strong dependencies across neighboring frequency bins and the decrease of those dependencies as the bins become far apart. The non-spherical joint density model proposed in this paper reflects this property of real-world speech signals. Experimental results show the improved performances over the spherical joint density representations.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.12
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• pp.62-67
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• 1997

The optical lithography wit an ArF excimer laser as a light source is expected to be used in the mass production of giga-bit DRAMs which require less than 0.2.mu.m minimum feature size. In this case, the distortion of a patterned image becomes very severe, since the lithography porcess is performed at the resolution limit. Traditionally, the photomask pattern was designed and revised with trial-and-error methods, such as repeated execution of process simulators or actual process experiments which require time and effort. Ths paper describes a program which automatically finds an optimal mask pattern. The program divides the mask plane into cells with same sizes, chooses a cell randomly, changes the transparent/opaque property of the cell, and eventually genrates a mask pattern which produces required image pattern. The program was applied to real DRAM cell patterns to produce mask patterns which genertes image patterns closer to object images than original mask patterns.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.32.2-32.2
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• 2010

Red dusty Active Galactic Nuclei (AGNs) are suspected to mid-stage between ULIRG and AGN phase. As well as, they are suspected that they have more than 50% of AGN population. To understand character of red AGN, Black Hole (BH) mass of red AGN is a key property and haven't measured by existing method such as reverberation mapping and single epoch method. So we still don't know their character and properties clearly. To estimate properties of red AGNs escape from effect of dust-obscuration, we have obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Object (QSO) using the infrared camera (IRC) for AKARI with unique wavelength range 2.5-$5.0{\mu}m$. From this spectra, we measured the FWHM and luminosity of brackett ${\alpha}$, ${\beta}$ at 4.0, 2.6 micron meter for deriving new BH mass estimators based on the properties of Brackett line emission.

• The Journal of Information Technology and Database
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• v.3 no.1
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• pp.45-63
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• 1996

This paper presents an integrated object-oriented database approach for managing the evolution of products in agile manufacturing environments, Schema evolution modification facilities are provided to support full potential versioning of type definitions. All of the possible versions for a composite product are not explicitly represented to avoid version proliferation. However, valid configurations of any composite products can be provided to comply with customer demands, The attributes of composite products are classified in order to provide well-defined representation scheme for composite products and to be exploited in version control. The attributes are partitioned into composite-related and non composite-related categories. Composite-related attributes consist of subproducts and description ones. Subproducts attributes represent physical constituents of a composite product. Description attributes represent external features, assembling, and correspondence property. Interface attributes are introduced for managing configurability and version propagation. Version derivations due to the changes to the interface attributes are propagated toward the product composition hierarchy, The validity of configurations of composite products is checked by using configurability maps. Instance objects which represent the actual product instances are stored and manipulated in the database in order to support traceability during product life cycle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.97-99
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• 2013

We introduced an earthquake-resistant design using acoustic rnetamaterials. There are two way in that field: one is a cloaking method and the other is a shadow zone method of seismic waves. Cloaking is a general property of a wave that changes the direction depending on the refractive index. Metamaterials control the propagation and transmission of specified parts of the wave and demonstrate the potential to render an object seemingly invisible. The shadow zone is a method of negative modulus using many huge resonators and it attenuates the amplitude of the wave exponentially. We compared and explained the fimdarnental principles of the two methods.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.369-371
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• 2012

Shadow detection and elimination is a critical issue in vision-based system to improve the detection performance of moving objects. However, traditional algorithms are useless at night time because they used the chromaticity and brightness information from the color image sequence. To obtain the high detection performance, we can use the thermal camera and there are shadows by the heat not the light. We proposed a novel algorithm to detect and eliminate the shadows using the thermal intensity and the locality property. By combining two results of the intensity-based and locality-based, we can detect the shadows by the heat and improve the detection performance of moving object.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.56-64
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• 2005

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to $1 {\mu}m$ at an airgap of $100{\mu}m$.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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• pp.267-271
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• 2002

The Hotelling transform is based on statistical properties of an image. The principal uses of this transform are in data compression. The basic concept of the Hotelling transform is that the choice of basis vectors pointing the direction of maximum variance of the data. This property can be used for rotation normalization. Many objects of interest in pattern recognition applications can be easily standardized by performing a rotation normalization that aligns the coordinate axes with the axes of maximum variance of the pixels in the object. However, this transform can not be used to rotation normalization of color images directly. In this paper, we propose a new method for rotation normalization of color images based on the Hotelling transform. The Hotelling transform is performed to calculate basis vectors of each channel. Then the summation of vectors of all channels are processed. Rotation normalization is performed using the result of summation of vectors. Experimental results showed the proposed method can be used for rotation normalization of color images effectively.