• BMB Reports
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• v.39 no.2
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• pp.167-170
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• 2006

Bovine adenosine deaminase undergoes a nondenaturational conformational change at $29^{\circ}C$ upon heating which is characterized by a large increase in heat capacity. We have determined the transition state thermodynamics of the conformational change using a novel application of differential scanning calorimetry (DSC) which employs very slow scan rates. DSC scans at the conventional, and arbitrary, scan rate of $1^{\circ}C/min$ show no evidence of the transition. Scan rates from 0.030 to $0.20^{\circ}C/min$ reveal the transition indicating it is under kinetic control. The transition temperature $T_t$ and the transition temperature interval ${\Delta}T$ increase with scan rate. A first order rate constant $k_1$ is calculated at each $T_t$ from $k_1\;=\;r_{scan}/{\Delta}T$, where $r_{scan}$ is the scan rate, and an Arrhenius plot is constructed. Standard transition state analysis reveals an activation free energy ${\Delta}G^{\neq}$ of 88.1 kJ/mole and suggests that the conformational change has an unfolding quality that appears to be on the direct path to the physiological-temperature conformer.

• Korean Journal of Computational Design and Engineering
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• v.16 no.4
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• pp.300-304
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• 2011

This paper proposes an approach to generate tool-path for laser pattern machining. Considering the mechanical structure of a laser pattern machine, it is quite similar to that of a 2D milling machine. Based on the observation, one may try to utilize the tool-path generation methodologies of 2D milling for the laser pattern machining. However, it is not possible to generate tool-path without considering the technological requirements of laser pattern machining which are different from those of 2D milling. In this paper, we identify the technological requirement of laser pattern machining, and propose a proper tool-path generation methodology to satisfy the technological requirements. For the efficient generation of tool-path, this paper proposes a tool-path element computation method, which is based on the concept of a monotone chain.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.723-728
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• 1999

In this paper, we designed a Circular Path Built-In Self Test circuit and embedded it into a simple 8-bit microprocessor. Register cells of the microprocessor have been modified into Circular Path register cells and each register cells have been connected to form a scan chain. A BIST controller has been designed for controlling BIST operations and its operation has been verified through simulation. The BIST circuit described in this paper has increased size overhead of the microprocessor by 29.8% and delay time in the longest delay path from clock input to output by 2.9㎱.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.8
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• pp.29-34
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• 2009

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.199-208
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• 1994

This paper proposes a delay fault test technique for ICs and PCBs with the boundary-scan architectures supporting ANSI/IEEE Std 1149.1-1990. The hybrid delay fault model, which comprises both of gate delay faults and path delay faults, is selected. We developed a procedure for testing delay faults in the circuits with typical boundary scan cells supporting the standard. Analyzing it,we concluded that it is impractical because the test clock must be 2.5 times faster than the system clock with the cell architect-ures following up the state transition of the TAP controller and test instruction set. We modified the boundary-scan cell and developed test instructions and the test procedure. The modified cell and the procedure need test clock two times slower than the system clock and support the ANSI/IEEE standard perfectly. A 4-bit ALU is selected for the circuits under test. and delay tests are simulated by the SILOS simulator. The simulation results ascertain the accurate operation and effectiveeness of the modified mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.56-62
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• 2000

A fast and precise technique to make 3-dimensional object which is called direct metal shaping process is processed. It is very useful technique in design and inspection. Using this developed system, a solid object is made. In experiment, test parts are built by varying three factors, laser power, scan path, scan speed. This process used device, which is different from the widely used in rapid prototyping in that powder feeding device is used. Spraying powder directly at the focused laser beam and then three dimensional object is made by the deposit of melted metal powder. The optimum scanning path is found to be zigzag path, which had little thermal affection on base metal. As a result of these experiments, it was found that optimum scanning speed is 15mm/sec laser power is 50W. This constructed 3-dimensional object could be used in mold manufacturing directly.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.213.1-213.1
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1295-1298
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• 2004

Selective Laser Sintering(SLS) method is one of Rapid Prototyping(RP) technologies. It is used to fabricate desirable part to sinter powder and stack the fabricated layer. To develop this SLS machine, it needs effective scanning path and the development of scanning device. This paper shows how to make fast scanning path with respect to scan spacing, laser beam size and scanning direction from 2-dimensional sliced file generated in commercial CAD/CAM software. Also, we develop the scanning device and its control algorithm to precisely follow the generated scanning path. Scanning path affects precision and total machining time of the final fabricated part. Sintering occurs using infrared laser which has high thermal energy. As a result, shrinkage and curling of the fabricated part occurs according to thermal distribution. Therefore, fast scanning path generation is needed to eliminate the factors of quality deterioration. It highly affects machining efficiency and prevents shrinkage and curling by relatively lessening the thermal distribution of the surface of sintering layer. To generate this fast scanning path, adaptive path generation is needed with respect to the shape of each layer, and not simply x, y scanning, but the scanning of arbitrary direction must be enabled. This paper addresses path generation method to focus on fast scanning, and development of scanning system and control algorithm to precisely follow generated path.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.34-39
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• 2010

We developed a path algorithm for ultrafast/wide area laser processing. Demands for high precision laser processing with a wide area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component and automobile industry. Expansion of the area in which laser processing is an important factor to handle the ultrafast/wide area processing, it will require a processing path. Processing path is path of 2- axis stage and stage of change in velocity can be smooth as possible. In this paper, we proposed a smoothingnurbs method of improved speed profile. This method creates soft path from edge part, it is main purpose that scan area ($50mm{\times}50mm$) inside processing path makes path of topology of possible straight line. We developed a simulation tool using Visual C++.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.1
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• pp.23-30
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• 1997

Recently high frequency ultrasonic transducers to employ polyvinylidene fluoride(PVDF) or polyvinylidene fluoride trifluoroethylene P(VDF-TrFE) have been used to detect small flaws in immersion testing. The detection field depending on the water path between the transducer and a specimen and the path in a tested specimen was measured using a PVDF transducer with nominal frequency 80MHz. Also, C-scan and B-scan were performed for the specimens made of Cr-Ni steel with the artificial flaws, the flat-bottom holes with diameter ranging from $50{\mu}m$ to $560{\mu}m$ at 12mm depth. As the result, the flaws with diameter larger than $280{\mu}m$ were detected, but the flaws with the ratio of diameter to wavelength smaller than about 0.48 were not detected. That the smaller flaws could not be detected was attributed to the attenuation of high frequency components in the steel specimens.