• Proceedings of the KIEE Conference
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• summer
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• pp.989-991
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• 2004

There are many elements that affect the average torque of the single phase SRM. It is related with the stator and rotor pole arcs, the dwell angle of the exciting current, the turn on/off angle, etc., Most of all, the turn on/off angle is affect the design procedure of the driving and control circuit. So, in this study, it is intend to analyze the effect that the variations of the turn on/off angle affects the average torque. and then this analyses will be used to design the control driver of the single phase SRM.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.5-6
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• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.148-151
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• 2004

For turn on high pressure sodium vapor lamp, Starting Voltage is very important factor. This starting voltage supply to high pressure sodium vapor lamp as electric discharge lamp, Electric field is producted in electric discharge tube, So accelerative electron collide against vapor atom and second electron is generated, And rapidly the current flow to electric discharge tube. This starting voltage is high voltage and source for melting contact that relay is according as turn on/off high pressure sodium vapor lamp. Consequently, This paper propose that the prevention of melting contact in accordance relay of controller for turn on/off high pressure sodium vapor lamp.

• Current Optics and Photonics
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• v.5 no.6
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• pp.660-671
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• 2021

We present a novel optical system for an augmented reality head-up display (AR HUD) with two virtual images at different conjugates by employing a confocal off-axis two-mirror and introducing the horopter circle. For a far virtual image with large asymmetrical aberrations, we initially obtain an off-axis two-mirror system corrected for these aberrations and compensated for the down angle by configuring its parameters to satisfy the confocal and Scheimpflug conditions, respectively. In addition, this system is designed to reduce the biocular parallax by matching Petzval surface into the longitudinal horopter circle in a near virtual image. This design approach enables us to easily balance the residual aberrations and biocular parallax when configuring the optical system with two different conjugates, which results in an AR HUD available for near and far virtual images together.

• Current Applied Physics
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• v.18 no.11
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• pp.1261-1267
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• 2018

In this paper, an off-axis digital holographic microscopy compensated with self-hologram rotation is presented. The process is implemented via subtracting the unwrapped phase maps of the off-axis parabolic hologram and its rotation $180^{\circ}$ to eliminate the tilt induced by the angle between the spherical object wave O and the plane reference wave R. Merit of the proposed method is that it can be done without prior knowledge of physical parameters and hence can reconstruct a parabolic hologram of $1024{\times}768$ pixels within tens of milliseconds since it doesn't require a digital reference wave. The method is applied to characterize rough gold bumps and the obtained results were compared with those extracted from the conventional reconstruction method. The comparison showed that the proposed method can characterize rough surfaces with excellent contrast and in realtime. Merit of the proposed method is that it can be used for monitoring smaller biological cells and micro-fluidic devices.

• Current Optics and Photonics
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• v.7 no.6
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• pp.761-765
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• 2023

We analyzed the absorption spectra of acetone in the 3.37 ㎛ mid-infrared range using the off-axis integrated cavity output spectroscopy technique to develop a real-time, in-line breath analysis device. The linear relationship between acetone concentration and absorption increase was confirmed as 0.32%/ppm, indicating that the developed device allows for a quantitative analysis of acetone concentration in exhaled breath. To further confirm the feasibility of using our device for breath analysis, we measured the acetone concentration of human breath samples at the sub-ppm level.

• Journal of the Korean Geotechnical Society
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• v.35 no.5
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• pp.43-51
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• 2019

At present, the ground anchor method is commonly applied to securing the slope stability in Korea. The ground anchor is reported to decrease in tensile load due to aging and environmental influences with time such as corrosion, relaxation, creep and so on. In Korea, the lift-off test is performed for the periodic inspection or cases when the symptoms of deterioration on anchors and the residual tensile load of the anchors is checked. However, the current lift-off test standard (MOLIT, 2010) is not fully specified in details. In this study, the factors affecting the lift-off test were investigated based on the previous research and foreign standards and lift-off tests were performed with consideration for the loading and unloading cycle, load increment method, and tensioning tendon method. Based on the results, this paper proposes improved testing and evaluation procedures of the lift-off test considering the workability and time limits in the field.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.472-478
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• 2022

Solar energy harvesting is practiced by various nations for the purpose of energy security and environment preservation in order to reduce overdependence on oil. Converting solar energy into electrical energy through Photovoltaic (PV) module can take place either in on-grid or off-grid applications. In recent time Lithium battery is exhibiting its presence in on-grid applications but its role in off-grid application is rarely discussed in the literature. The preliminary capacity and Peukert's study indicated that the battery quality is good and can be subjected for life cycle test. The capacity of the battery was 10.82 Ah at 1 A discharge current and the slope of 1.0117 in the Peukert's study indicated the reaction is very fast and independent on rate of discharge. In this study Lithium Iron Phosphate battery (LFP) after initial characterization was subjected to life cycle test which is specific to solar off-grid application as defined in IEC standard. The battery has delivered just 6 endurance units at room temperature before its capacity reached 75% of rated value. The low life of LFP battery in off-grid application is discussed based on State of Charge (SOC) operating window. The battery was operated both in high and low SOC's in off-grid application and both are detrimental to life of lithium battery. High SOC operation resulted in cell-to-cell variation and low SOC operation resulted in lithium plating on negative electrode. It is suggested that to make it more suitable for off-grid applications the battery by default has to be overdesigned by nearly 40% of its rated capacity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.359-363
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• 2011

To integrate the sensor driver and logic circuits, fabricating down scaled transistors has been main issue. At this research, short channel effects were analyzed after n channel polycrystalline silicon thin film transistor was fabricated at high temperature. As a result, on current, on/off current ratio and transconductance were increased but threshold voltage, electron mobility and s-slope were reduced with a decrease of channel length. When carriers that develop at grain boundary in activated polycrystalline silicon have no gate biased, on current was increased with punch through by drain current. Also, due to BJT effect (parallel bipolar effect) that developed under region of channel by increase of gate voltage on current was rapidly increased.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.241-246
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• 2016

This paper presents a method that can improve the performance of permanent magnet synchronous motor current control by minimizing the measured current phase delay caused by the Low Pass Filter(LPF) used to cut off the noises that flowed in when feedback currents are measured. Although existing methods that change the Cutoff Frequency of the LPF can minimize phase delays during high speed rotations, their noise cutoff effects are much lower and this may lead to the decline of control performance. Therefore, in this study, an algorithm that can compensate current phase delays through relatively simple calculations from the synchronous motor d-q axis coordinate transformation matrix and the inverse transformation matrix is proposed and the validity of the proposed method is verified by comparing the waveform of the calculated current with the waveform of actual currents through simulations and experiments.