• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.505-510
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• 2006

A gallocyanine-bound nanoporous titanium dioxide electrode system was investigated to carry out a mediated enzyme reaction. Gallocyanine was bound either directly or through an aminopropylsilane linker to the film of nanoporous titanium dioxide and used as a mediator for nitrate reductase in the mediated enzymatic nitrate reduction. The electrode with the aminopropylsilane linker showed 20% higher efficiency of electron transfer at the same potential than that directly linked. The prepared electrodes showed $0.26{\mu}mol/h$ nitrate reduction at a $100mm^2$ surface of the electrode, and linear current response on nitrate ion concentration up to 1.0 mM, which is very useful as a biosensor of nitrate ion in water.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.6
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• pp.211-218
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• 1983

In this paper, an attempt is made to match the continuous state trajectory of the digital control system with that of its continuous data model. Matching the state trajectories instead of the output responses assures that the performances of the internal variables of the plant as well as the output variables are preserved in the discretization. The mathematical tool used in this research is an extended maximum principle of the Pontryagin type, which enables one to synthesize a staircase type of optimal control signals, such as the output signal of a zero-order hold asociated with a digital controller. A general mathematical expression of the digital controller which may be used to replace the analog controller of a general system while preserving as mauch as possible the performance characteristics of the original continuous-data control system is derived in this paper.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.365-366
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• 2017

LLC resonant DC-DC converter is widely used in many kinds of applications such as battery energy storage systems, wireless power transfer and high voltage power supply. It is because of characteristics like high efficiency, power density, isolation, wide power level and stability enhancement at high switching frequency. Small signal modeling helps to design controller of the converter by approximating the behavior of nonlinear system with linear state equations. This paper presents comparison between small signal modeling analysis and experimental results of LLC resonant converter.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.41-45
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• 2016

In this study, LET (Linear Energy Transfer) calibration of CR-39 SSNTD (Solid State Nuclear Track Detector) was performed using 500 MeV/u Fe heavy ions in HIMAC (Heavy Ion Medical Accelerator) for high LET radiation dosimetry. The irradiated CR-39 SSNDT were etched according JAXA (Japan Aerospace Exploration Agency) etching conditions. And the etched SSNTD were analyzed by using Image J. Determined dose-mean lineal energy ($\overline{y_D}$) of 500 MeV/u Fe is about 283.3 keV/um by using the CR-39 SSNTD. This value is very similar result compare to the results calculated by GEANT4 Monte Carlo simulation and measured with TEPC active radiation detector. We confirmed that the CR-39 SSNTD was useful for high LET radiation dosimetry such as heavy iron ions.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.78-85
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• 2017

This paper presents the development of a 3D printer based piezo-driven vertical micro-positioning stage. The stage consists of two flexure bridge structures which amplify and transfer the horizontal motion of the piezo-element into vertical motion of the end-effector. The stage is fabricated with ABS material using a precision 3D printer. This enables a one-body design eliminating the need for assembly, and significantly increases the freedom in design while shortening fabrication time. The design of the stage was optimized using response surface analysis method. Experimental results are presented which demonstrate 100nm stepping in the vertical out-of-plane direction. The results demonstrate the future possibilities of applying 3D printers and ABS material in fabricating linear driven motion stages.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.675-685
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• 2013

Generation capacities and transmission line constraints in a competitive electricity market make it troublesome to compute Nash Equilibrium (NE) for analyzing participants' strategic generation quantities. The NE can cause a mixed strategy NE rather than a pure strategy NE resulting in a more complicated computation of NE, especially in a multiplayer game. A two-level hierarchical optimization problem is used to model competition among multiple participants. There are difficulties in using a mathematical programming approach to solve a mixed strategy NE. This paper presents heuristics applied to the mathematical programming method for dealing with the constraints on generation capacities and transmission line flows. A new formulation based on the heuristics is provided with a set of linear and nonlinear equations, and an algorithm is suggested for using the heuristics and the newly-formulated equations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.85-86
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• 2005

In case of attaching thermoelectric module and heat source, the polymer sheet is attached on the $Al_2O_3$ plate, which is cooling side of thermoelectric module, in order to enhance mechanical safety of the system. It is impossible to calculate the exact distribution of temperature and flow pattern of inner gap of thermoelectric module. Therefore CFD analyses was executed to determine the thermo-fluid phenomena and distribution by Fluent. As the result of these analyses, heat transfer was dominated by conduction and the difference of temperature was linear distribution according to the thickness of polymer sheet.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1675-1677
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• 2005

In case of attaching thermoelectric module and heat source, the polymer sheet is attached on the $AL_{2}O_3$ plate, which Is cold and hot side of thermoelectric module, in order to enhance mechanical safty of the system. It is impossible to calculate the exact distribution of temperature and flow pattern of inner gap of thermoelectric module. Therefore CFD(Computational Fluid Dynamics) analysis was executed to determine the thermo-fluid phenomena and distribution by Fluent. As the result of these analysis, heat transfer was dominated by conduction and the difference of temperature was linear distribution according to the thickness of polymer sheet.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.333-338
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• 1997

A hollow crankshaft is considered as part of an effort to reduce the weight of the automobile powertrain. Since the resulting mass reduction alters both the inertia and stiffness properties of the crankshaft, the vibration characteristics of the hollow crankshaft needs to be investigated in comparison with the original solid crankshaft. The crankshafts are modeled by 38 lumped mass and stiffness elements, in which the dynamic parameters for each lumped element are obtained by the finite element calculation. The fluid-film bearings supporting the crankshaft give rise to linear spring and damping elements that can be derived from the hydrodynamic bearing model. The transfer matrix method is applied to yield the natural frequencies and mode shapes of the crankshaft vibration. The natural frequencies of the hollow crankshaft are founded to be greater than that of the solid crankshaft, and the incorporation of the bearing stiffness tends to accentuate the difference.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1044-1049
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• 2001

Classical deconvolution methods for source identification following linear filtering can only be used if the transfer function of the system is known. For many practical situations, however, this information is not accessible and/or is time varying. The problem addressed here is that of reconstruction of the original input from only the measured signal. This is known as 'blind deconvolution'. By using Higher Order Statistics (HOS), the restoration of the input signal is established through the maximisation of higher order moments (cumulants) with respect to the characteristics of the signals concerned. This restoration is achieved by constructing an inverse filter considering the choice of the initial inverse filter type. As a practical application, an experimental verification is carried out for the restoration of our impacting signal arising in the response of a cantilever beam with an end stop when randomly excited.