• Journal of Drive and Control
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• v.13 no.3
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• pp.47-52
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• 2016

This paper presents a control method for the performance improvement of a proportional solenoid actuator using a Pulse Width Modulation (PWM) signal. It is very difficult to obtain excellent response performance from a proportional solenoid actuator using a simple proportional controller with no PWM signal or dither because the mass and structure of a proportional solenoid actuator changes according to the application target, friction force in the proportional solenoid tube, operating force and displacement range. To solve the above problems, first, a controller with a PWM function for experimenting with attraction force characteristics was designed and manufactured. Secondly, an experimental setup for solenoid performance measurement with a force sensor and a displacement sensor was also manufactured. The attraction force characteristics according to the frequency and duty ratio variations of a PWM signal were tested and the relationships among the frequency, duty ratio, plunger mass and friction characteristics were analyzed. Finally, response characteristics improvements for proportional solenoid actuators are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.11
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• pp.611-616
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• 1999

The introduction of the eddy current braking(ECB) system in HSRT(high speed railway train) is known to be advantageous, in that the system is independent on wheel-rail adhesion coefficient which is greatly affected by weather condition. It also minimize the maintenance of the brake system and does not require any additional electric energy because it is powered form the regenerated power at the time of the braking. In this study, the braking and attraction forces of the ECB are simulated by 2-D FEM and are experimentally verified on a down-scaled prototype. A control algorithm of the ECB is proposed to generate constant braking torque using linear variation of the reference current according to speed. Experimental results shows that the constant torque is generated over all operating speed region by developed control algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1424-1429
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• 2007

This paper presents a simple and reliable one-touch type multi-immunosensing lab-on-a-chip (LOC) detecting antibodies as multi-disease markers using electrochemical method suitable for a portable point-of-care system (POCS). The multi-stacked LOC consists of a PDMS space layer for liquids loading, a PDMS valve layer with 50 im in height for the membrane, a PDMS channel layer for the fluid paths, and a glass layer for multi electrodes. For the disposable immunoassay which needs sequential flow control of sample and buffer liquids according to the designed strategies, reliable and easy-controlled on-chip operation mechanisms without any electric power are necessary. The driving forces of sequential liquids transfer are the capillary attraction force and the pneumatic pressure generated by air bladder push. These passive fluid transport mechanisms are suitable for single-use LOC module. Prior to the application of detection of the antibody as a disease marker, the model experiments were performed with anti-DNP antibody and anti-biotin antibody as target analytes. The flow test results demonstrate that we can control the fluid flow easily by using the capillary stop valve and the PDMS check valves. By the model tests, we confirmed that the proposed LOC is easily applicable to the bioanalytic immunosensors using bioelectrocatalysis.

• Journal of Contemporary Eastern Asia
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• v.17 no.1
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• pp.5-26
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• 2018

Joseph S. Nye defined soft power as the power of attraction to affect the behavior of other states through the use of non-coercive instruments including culture, political values and foreign policy. Over the last two decades, environmental issues have grown in importance on the international agenda and become critical components of states' foreign policy-making. This paper aims to analyze environmental foreign policy as a soft power instrument focusing on two major rising powers: China and India. Traditionally, China and India had been reluctant to make any commitments in the field. However, they have shown greater willingness to act in global environmental governance in the past decade. They started playing more active roles in global climate change negotiations and supported a number of initiatives. Their current rise in global environmental governance has even been praised by the international community as the Paris agreement case demonstrated. This study evaluates China's and India's recent efforts in global environmental governance with a focus on climate change negotiations linking their constructive position to their soft power potential. It is argued that environmental issues are used by these two states as foreign policy strategy to gain more influence in international politics. This study finds out that China's climate-related environmental diplomacy has been more ambitious than that of India and thus has been closer to fulfill its potential as a soft power asset.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.19-24
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• 2003

Exhaust brake system for Diesel engines is composed of gate valve, pneumatic cylinder and exhaust brake valve with on-off solenoid. Exhaust brake valve which is core component of exhaust brake system should have characteristics such as high reliability and long life. In this paper. exhaust brake valve with on-off solenoid which is used for vehicle brake system was studied. For the performance evaluation of on-off solenoid, electromagnetic characteristics and dynamic characteristics are analyzed. As a basic study for the performance improvement of exhaust brake system, pneumatic circuit and pneumatic valve with on-off solenoid were suggested and the performance of the pneumatic valve was evaluated through tests.

• Textile Coloration and Finishing
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• v.17 no.2 s.81
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• pp.40-45
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• 2005

Electret filter is good enough to protect health and environment from air pollution. The reason why is gathering particles not only by mechanical mechanism but also by electrostatic attraction. Especially this filter is shown lower pressure drop than general mechanical filters as glass fiber. For making electret filter media using polypropylene meltblown(M/B) nonwoven, the nonwoven is charged with corona which was supplied high voltage DC, AC, and pulse with DC power. The electret filter media is tested with $0.3{\mu}m$ sodium chloride and dioctyl phthalate(DOP) aerosol. Results revealed that filtration performance of electret filter media increased as corona was applied with higher voltage and with AC power rather than DC, and fiber diameter was fine and uniform.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.172-175
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• 2001

This paper presents a new energy function reflecting the damping effect in multi-machine power systems. The Lyapunov direct method provides precise and rigorous theoretical backgrounds for stability analysis of nonlinear systems. Incorporating damping effects into accurate estimates of the domain of attraction, which is a minor but crucial point, has been attempted with long history to yield partial success for single machine systems. In this paper, the damping-reflected energy function presented in the previous work has been generalized for application to multi-machine systems. The generalized energy function is tested for the WSCC 9-bus system to show the semi-negativeness of its time derivative.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.171-173
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• 2001

Conventional potential concept does not allow different currents before and after the electric load. Experimental examples in case of bioloads show a lot of different currents before and after the bioload, which means that the true potential concept is not the conventional concept from Coulomb attraction energy but the new concept from Gibb's free energy. Gibb's free energy is a kind of potential heat energies and also they are rotating electromagnetic waves. We might think that electric current is not a flow of electrons but a flow of rotating electromagnetic waves, which induces electrons' vibrations. A new measuring method for integral electrical power is suggested for the new Gibb's free energy concept.

• Proceedings of the KIEE Conference
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• summer
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• pp.1052-1054
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• 2004

This paper deals with a Double type Transverse Flux Linear Motor(TFLM) which can be applied to high power system. This type can reduce overall system volume because of the configuration which has double flux path of prototype per phase, and less number of phase and turns. This TFLM is based on permanent magnet excitation, and the pole shape is designed to reduce attraction force between stator and mover poles. In the paper, the basic configuration of double type and the principle of movement are introduced. After performing the characteristic analysis by 3-dimensional equivalent magnetic circuit network, the results are discussed.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.434-447
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• 2016

The aim of this paper is the study of instability state of boiling water reactors with a method based in largest Lyapunov exponents (LLEs). Detecting the presence of chaos in a dynamical system is an important problem that is solved by measuring the LLE. Lyapunov exponents quantify the exponential divergence of initially close state-space trajectories and estimate the amount of chaos in a system. This method was applied to a set of signals from several nuclear power plant (NPP) reactors under commercial operating conditions that experienced instabilities events, apparently each of a different nature. Laguna Verde and Forsmark NPPs with in-phase instabilities, and Cofrentes NPP with out-of-phases instability. This study presents the results of intrinsic instability in the boiling water reactors of three NPPs. In the analyzed cases the limit cycle was not reached, which implies that the point of equilibrium exerts influence and attraction on system evolution.