• Proceedings of the KSR Conference
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.1240-1246
• /
• 2006

Generally, there are two types of main factors to affect output power quality of a auxiliary power supply an EMU(electric multiple unit). One is a voltage flicker by amplitude modulation of short time and air compressors. The other is repetitive motion of large capacity motor such as air compressors, HVAC unit etc. in main factors. This paper compared two kinds of fluorescent lamp, 32W (after remodeling interior) and 40W(before remodeling interior) and measured the light output varying input power(AC220V) for a flicker phenomenon related power supply of lamps in EMU. Also, we analyzed a flicker considering EMU operating time and density in order to grasp main factors of a load change to cause a voltage change. As a results of test, a 40W fluorescent lamp was more insensitive with 20.26% degree an eye recognition degree sides about changes of the input power and lower with 19.9% voltage side generating flicker compare with fluorescent lamp 32W. Also, we confirmed the fact which the fluorescent lamp flicker was generated by varying fluorescent lamp output voltage when the commercial EMU was in high driving density and at the busy time. Additionally, we confirmed the frequency band which an EMU passenger could feel sensitively blinking of a fluorescent lamp was visually $8Hz{\sim}15Hz$.

• Journal of the Institute of Electronics and Information Engineers
• /
• 제52권9호
• /
• pp.63-73
• /
• 2015

This work proposes a 2-channel time-interleaved (T-I) 10b 120MS/s pipeline SAR ADC minimizing offset mismatch between channels without any calibration scheme. The proposed ADC employs a 2-channel SAR and T-I topology based on a 2-step pipeline ADC with 4b and 7b in the first and second stage for high conversion rate and low power consumption. Analog circuits such as comparator and residue amplifier are shared between channels to minimize power consumption, chip area, and offset mismatch which limits the ADC linearity in the conventional T-I architecture, without any calibration scheme. The TSPC D flip-flop with a short propagation delay and a small number of transistors is used in the SAR logic instead of the conventional static D flip-flop to achieve high-speed SAR operation as well as low power consumption and chip area. Three separate reference voltage drivers for 4b SAR, 7b SAR circuits and a single residue amplifier prevent undesirable disturbance among the reference voltages due to each different switching operation and minimize gain mismatch between channels. High-frequency clocks with a controllable duty cycle are generated on chip to eliminate the need of external complicated high-frequency clocks for SAR operation. The prototype ADC in a 45nm CMOS technology demonstrates a measured DNL and INL within 0.69LSB and 0.77LSB, with a maximum SNDR and SFDR of 50.9dB and 59.7dB at 120MS/s, respectively. The proposed ADC occupies an active die area of 0.36mm2 and consumes 8.8mW at a 1.1V supply voltage.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• 제9권2호
• /
• pp.178-184
• /
• 2016

The motor power of the industry to use the electric energy is gradually increased. The electric motor generates a voltage drop in the starting current during startup. The starting current is started it is difficult to have an adverse effect on neighboring power systems with large motor starting when the voltage drop across the power grid. In addition to that the motor torque according to the load depending on the size of the rotation speed is changed to a motor start-up speed is important. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• Journal of IKEEE
• /
• 제15권1호
• /
• pp.49-56
• /
• 2011

In this paper, a compact doppler sensor with oscillator type active antenna operating at 2.4GHz frequency band is proposed to measure the distance or speed of a moving object. The active antenna has been realized by oscillator using radiator, patch antenna, as its resonator. The oscillation frequency is shifted depending on approaching of the object, and a detection circuit discriminates the frequency deviation. The oscillator type active antenna has been designed and simulated. The prototype fabricated has a very small circular disk type of diameter 30mm and height 4.2mm. As for antenna performance, broadside radiation pattern with beamwidth of $130^{\circ}$ and oscillation frequency of 2.373GHz has been measured. Test results as a doppler sensor shows that doppler signal voltage of about 190mV has been obtained for conducting plate moving 1 meter away from the sensor. And, doppler signal voltage has been linearly increased to the ground from 4.5m height by free-falling the sensor.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• 제23권5호
• /
• pp.559-565
• /
• 2010

In this study we propose noise energy harvesting for green infrastructure development. In this regard, infrastructures such as railroad, subway, and road are taken into consideration as sources of noise which provides energy through certain wave forms. As the need of recycling noise energy became reasonable due to the increase of infrastructure usage, the capacity and property of our noise energy generating device, which uses electromagnetic induction for electricity generation, are analysed in this paper. Consequently, the outcomes of this experiment show the fact that maximum electricity is generated from the device at a specific point of noise frequency, and the relation between air pressure caused by noise and the electricity generated by the device is in a specific proportional form either linear or non-linear. The major points of developing noise energy generating device in order to apply it into social infrastructure are discussed in this paper as well.

• Journal of the Korean Magnetics Society
• /
• 제18권2호
• /
• pp.79-83
• /
• 2008

We have investigated the effect of the formation of an initial oxide layer on the fabrication of the porous aluminium oxide. The porous aluminium oxide was fabricated by two-step anodization process with a electropolished aluminium foil. Before the first anodization step, the initial oxide layer with thickness of 10 nm was formed under the applied voltage of 1 V and later the anodization was continued under 40 V using oxalic acid solution. With the formation of the initial oxide layer, the anodization process was stable and the anodization current was constant throughout the process. In case of the absence of the initial oxide layer, the anodization was very unstable and the continuous increase in the anodization current was observed. This indicates the formation of the initial oxide layer on the aluminium surface prevents the burning of the surface due to the nonuniform distribution of the applied electric field, and allows the stable anodization process required for the porous aluminium oxide.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• 제28권9호
• /
• pp.698-706
• /
• 2017

The risk of high power electromagnetic(HPEM) pulse exposure to the devices used in digital control system such as PLC(programmable logic controller) and communication cable is increasing. In this paper, two different frequency ranges HPEMs were exposed to those control systems to assess the each vulnerability. The vulnerability of the EUTs exposed from HPEM were analyzed and compared with a variation of distances and source power. As the EUTs were exposed to higher level of HPEM, the voltage and communication waveform of the control system had shown a distorted response. And the unshielded twisted pair(UTP) cable connected to the EUTs showed operation failures with induced voltage. However, the foiled twisted pair(FTP) cable shielded the connected device efficiently from the HPEM exposure. Therefore, the necessity of the protection measures against the vulnerability of HPEM exposure for the digital control system used in power facilities and industrial site were verified.

• Journal of the Korean Institute of Intelligent Systems
• /
• 제24권2호
• /
• pp.129-135
• /
• 2014

In the paper, we propose a design method for the logistics transportation system using magnetic levitation that has a good characteristics without mechanical friction, noise and dust. The proposed transportation system consists of a levitation control system and a propulsion control system. Magnetic levitation system is an electromagnetic suspension system in which electromagnet generates magnetic attractive force and the attractive force pulls the rail. We design a PID controller for the current control of electromagnets. We use linear induction motors for propulsion of the proposed logistics transportation system and adapt the space vector PWM method for the propulsion control system. The proposed transportation system using magnetic levitation is verified performances through levitation and propulsion experiments.

• Journal of the Korean Ceramic Society
• /
• 제34권8호
• /
• pp.803-810
• /
• 1997

Ba0.5Sr0.5TiO3 thin films were deposited by RF magnetron sputliring method in order to clarify the anneal condition and doping effect on loakage current Nb and Al were selected as electron donor and acceptor dopants respectively, in the BST films because they have been known to have nearly same ionic radii as Ti and thought to substitute Ti sites to influence the charge carrier and the acceptor state adjacent to the gram boundary. BST thin films prepared in-situ at elevated temperature showed selatively high leakage current density and low breakdown voltage. In order to achieve smooth surface and to improve electrical properties, BST thin films were deposited at room temperature and annealed at elevated temperature. Post-annealed BST thin films showed smoother surface morphology and lower leakage current density than in-situ prepared thin films. The leakage current density of Al doped thin films was measured to be around 10-8A/cm2, which is much lower than those of undoped and Nb doped BST films. The result clearly demonstrates that higher Schottky barrier and lower mobile charge carrier concentration achieved by annealing in the oxygen atmosphere and by Al doping are desirable for reducing leakage current density in BST thin films.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• 제15권1호
• /
• pp.51-58
• /
• 2001

Recently, DC-DC converters significantly increase the total losses as rising switching frequency. Trnditional soft switching technique for reducing switching losses even increase voltage/Clment stress of switch In this paper, Resonant circuit for soft switching is connected in parallel with power stage and only operates just before tum-on of the main sWItch. Therefore, ills doesn't affect the total circuit QI'||'&'||'pound;ration. The object of tIns paper is to make the linearized equivalent loss mxleIs. and to analyze the total losses by experiment. ZVT-PWlvI converter designed with 170-260[V] input, 400[V] 5[A] output, and 100[kHz] switching frequency is tested respectively with 500[W], 1[kW], 1.5[kW], and 2[kW] loads. The total losses in input 220[V], 2[kW] load are analyzed by usirm the linearized equivalent loss models.