• Journal of ILASS-Korea
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• v.21 no.3
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• pp.155-161
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• 2016

Injected fuel pressure waves of a common rail injector with various current profiles supplied to the injecor were measured using Bosch method. In order to drive the common rail injector, the current in the solenoid should be controlled using what is known as a peak and hold pattern, which consists of a high current level with a short time duration (peak) in the first step and a low current level with a long time duration (hold) in the subsequent step. The current profile can be shaped by swithcing an injector driving power source with the peak and hold waves. The capture, compare and PWM (CCP) pin in the microprocessor was used to generate the combined peak and hold waves. The PWM square wave generated from the CCP pin has a duty ratio of 100% for the peak current and 10% or 30% for the hold pattern. Five patterns of the current profile were generated by combining the peak and hold wave. The common rail pressure is controlled at 75, 100, and 130 MPa. As the fuel rail pressure increases, the variations of the measured fuel injection pressure wave according to the current profiles decrease.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.840-846
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• 2000

In this work, small-size, high-performance solenoid-type RF chip inductors utilizing a low-loss Al$_2$O$_3$core material were investigated. The size of the chip inductors fabricated in this work were 15$\times$10$\times$0.7㎣, 2.1$\times$1.5$\times$10㎣, and 2.4$\times$2.0$\times$1.4㎣ and copper (Cu) wire with 40 ㎛ diameter was used as the coils. High frequency characteristics of the inductance, quality factor, and impedance of developed inductors were measured suing an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). It was observed that the developed inductors with the number of turns of 7 have the inductance of 33 to 100nH and exhibit the self-resonant frequency (SRF) of .26 to 1.1 GHz. The SRF of inductors decreases with increasing the inductance and the inductors have the quality factor of 60 to 80 in the frequency range of 300 MHz to 1.1 GHz. In this study, small-size solenoid-type RF chip inductors with high inductance and high quality factor were fabricated successfully. It is suggested that the thin film-type inductor is necessary to fabricate the smaller size inductors at the expence of inductance and quality factor values.

• Progress in Superconductivity and Cryogenics
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• v.14 no.1
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• pp.14-19
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• 2012

Shimming, active and/or passive, is indispensable for most MR (magnetic resonance) magnets where homogeneous magnetic fields are required within target spaces. Generally, shimming consists of two steps, field mapping and correcting of fields, and they are recursively repeated until the target field homogeneity is reached. Thus, accuracy of the field mapping is crucial for fast and efficient shimming of MR magnets. For an accurate shimming, a "magnetic" center, which is a mathematical origin for harmonic analysis, must be carefully defined, Although the magnetic center is in general identical to the physical center of a magnet, it is not rare that both centers are different particularly in HTS (high temperature superconducting) magnets of which harmonic field errors, especially high orders, are significantly dependent on a location of the magnetic center. This paper presents a new algorithm, based on a field mapping theory with harmonic analysis, to define the best magnetic center of an MR magnet in terms of minimization of pre-shimming field errors. And the proposed algorithm is tested with simulation under gaussian noise environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1164-1176
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• 1996

A magnetically levitated micro-positioner is implemented to avoid mechanical friction and increase precision. Since magnetic levitation system is inherently unstable, most concern is focused on a magnetic circuit design to increase the system dynamic stability. For this, the proposed levitation system is constructed by using an antagonistic structure which permits a simple design and robust stability. From the dynamic equations of motion, it is verified that the proposed magnetically levitated system is decoupled in 6 degree-of-freedom motion. Experimental results are presented in terms of time response and accuracy.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.548-552
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• 2010

The air suction filter of the power plant decrease the dust and impurities of suction air that reduce the life and efficiency of the boiler. The suction efficiency of the air filter falls with the dust and impurities when the time of use comes to be long. Therefore, the various contaminant of the filter must remove periodically. This paper presents a developed quick exhaust valve to use in the thermo-electric power plant. to removing contaminants on the filter, the blowing is done shortly by air pressure. The Air flowed out to the out side from the inside of the filter. The performance test of the developed valve is done by making a test-bench according to JIS and KS standards. The efficiency is found higher than the existing related valve.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.2
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• pp.120-124
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• 2003

This paper describes a MEMS-based micro-fluxgate magnetic sensing element using Ni$\_$0.8/Fe$\_$0.2/ film formed by electroplating. The micro-fluxgate magnetic sensor composed of a thin film magnetic core and micro-structure solenoids for the pick-up and the excitation coils, is developed by using MEMS technologies in order to take advantage of low-cost, small size and lower power consumption in the fabrication. A copper with 20${\mu}$m width and 3${\mu}$m thickness is electroplated on Cr (300${\AA}$) / Au (1500${\AA}$) films for the pick-up (42turn) and the excitation (24turn) coils. In order to improve the sensitivity of the sensing element, we designed the magnetic core into a rectangular-ring shape to reduce the magnetic flux leakage. An electroplated permalloy film with the thickness of 3${\mu}$m is obtained under 2000 gauss to induce magnetic anisotropy. The magnetic core has the high DC effective permeability of ~1,100 and coercive field of ~0.1 Oe. The fabricated sensing element using rectangular-ring shaped magnetic film has the sensitivity of about 150 V/T at the excitation frequency of 2 MHz and the excitation voltage of 4.4 V$\_$p p/. The power consumption is estimated to be 50mW.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.183.1-183.1
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• 2013

70 MeV 사이클로트론의 인젝션 빔 라인은 Multi-CUSP 이온원에서 인출된 H- 빔을 펄스 또는 번칭하여 인플렉터를 통해 사이클로트론의 가속영역인 Dee로 전송하는 역할을 한다. 이 때, 빔을 번칭 시킴으로써 가속효율을 높이고, 손실을 줄여 높은 전류의 빔을 공급할 수 있도록 해야한다. 인젝션 시스템은 einzel lens, chopper, buncher, solenoid 등으로 구성된다. Einzel lens는 빔을 buncher의 중심으로 집속시켜 buncher의 번칭 효율을 높이고, buncher는 전기장을 이용하여 빔을 진행방향으로 집속시키는 기능을 갖는다. Chopper는 번칭된 빔을 일정 주기로 편향을 시켜 펄스 빔의 형태로 전송하는 역할을 한다. 솔레노이드는 적절한 자기장을 이용하여 빔을 집속시켜 인플렉터로 전송한다. 본 연구에서는 사이클로트론의 고전류 인젝션 시스템을 구축하고 각각의 구성요소에서 빔 envelope를 계산하고 비교하였다. SIMION code는 user가 지정한 특성을 가진 개별 입자의 궤도를 추적하는 프로그램으로 인젝션 시스템을 구성하는 각각의 컴포넌트에서의 입자의 진행모습과 buncher를 이용하여 빔의 전송 밀도가 향상됨을 확인하였다. 아울러 TRANSPORT 및 TURTLE 프로그램을 이용하여 SIMION을 통해 계산된 빔의 envelope과 비교하였다.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.55-62
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• 2004

In general, control performance of the active control system is superior to that of the passive control devices. However, the active system require a large amount of external energy to operate the actuators. Semi-active control systems maintain the reliability of the passive control systems while taking advantage of the adjustability of the active control system. In this research, a semi-active orificed fluid damper having the capacity of about 2 tons was designed and fabricated. It is a two-stage damper with normally open solenoid valve. A series of tests was performed to grasp its performance characteristics. It was also applied to a 6-story steel structure subjected to random and seismic excitations for the confirmation of its validity on structural vibration absorption.

• Journal of Drive and Control
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• v.11 no.3
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• pp.47-54
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• 2014

Clutches are an integral part of the automatic transmission for changing gears. Modern automatic transmissions make extensive use of wet multiple-disc clutches employing hydraulic actuation mechanism with electronic control. Although nowadays, highly advanced shifting algorithm implements the superior shift quality and transmission efficiency, its performance should be based on smooth, reliable engagement with a reasonably durable friction material as well as stable clutch piston dynamics. Particularly, clutch filling control is the crucial part of shifting process because only the open-loop control is available due to the lack of measurement. In this paper, the effect of clutch-fill control parameters on clutch piston dynamics is experimentally investigated by using clutch piston test equipment which enables the clutch piston to actuate similar to real shifting conditions. The experimental analysis results can be expected to be utilized for the calibration of proportional solenoid valve as reference current profile data in vehicle test.

• Journal of Drive and Control
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• v.14 no.4
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• pp.29-36
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• 2017

Electronic control technologies that have long been developed for passenger cars spread to construction equipment and agricultural vehicles because of its outstanding performance achieved by embedded software. Especially, system program of transmission control unit (TCU) plays a crucial role for the superb shift quality, driving performance and fuel efficiency, etc. Since the control algorithm is embedded in software that is rarely analyzed, development of such a TCU cannot be conducted by conventional reverse engineering. Transmission simulator is a kind of electronic device that simulates the electric signals including driver operation command and output of various sensors installed in transmission. Standalone TCU can be run in normal operation mode with the signals provided by transmission simulator. In this research, transmission simulator for the tracked vehicle TCU is developed for the analysis of shift control algorithm from the experiments with standalone TCU. It was confirmed that shift experimental data for the simulator setup conditions can be used for the analysis of control algorithms on proportional solenoid valves and shift map.