• Journal of Energy Engineering
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• v.18 no.3
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• pp.163-168
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• 2009

This paper describes the homogeneous charge compression ignition (HCCI) engine for a new concept. HCCI engines are being considered as a future alternative for diesel and gasoline engines. HCCI engines have the potential for high indicated thermal efficiency under part load and very low NOx emissions. The objective of this paper is to clear the effects of exhaust gas recirculation (EGR) rate on the HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine This work has been run with propane and butane fuels at a constant speed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.519-527
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• 1997

AISI 316 steel has been used extensively for heater and boiler tube of the structural plants such as power, chemical and petroleum plants under severe operating conditions. Usually, material degradation due to microcrack or precipitation of carbides and segregation of impurity elements, is occured by damage accumulated for long-term service at high temperature in this material. In this study, the effect of aging time on fracture toughness was investigated to evaluate the measurement of material degradation. The elastic-plastic fracture toughness behaviour of AISI 316 steel pipe aged at $550^{\circ}C$for 1h-10000h (the aged material) was characterized using the single specimen J-R curve technique and eletric potential drop method at normal loading rate(load-line displacement speed of 0.2mm/min) in room temperature and air environment. The fracture toughness data from above experiments is compared with the $J_{in}$ obtained from predicted values of crack initiation point using potential drop method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.92-99
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• 2005

We are interaction refrigeration warehouse cold water pump system and photovoltaic generation system. At this time, a target pressure is able to control in spite of change of the pressure according to pump head and rate of flow of pump. Also, we carry out the vector control of BLDC motor with the maximum torque operation and a high reliability from territory of each operation speed. Therefore, in this paper, we conclude energy saving technique of refrigeration warehouse cold water pump system.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.595-602
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• 1994

PERISTOR-3000 loaded with 32 bit DSP(Digital Signal Processor) is a technically advanced versatile dc motor controller in applications with very high requirements for rapid response, control accuracy and reliability. The current controller of PERISTOR-3000 is of the predictive type and gives fast control with both discontinuous and continuous current compared to the conventional PI current control. The speed controller gain is compensated to improve response behavior. PERISTOR-3000 communicates with its host computer, POSTAR-3200, or any IBM or compatible PC and can be controlled. Dedicated monitoring system for MMI is introduced.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.1045-1052
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• 2013

In this study we deal with design procedures for the flywheel energy storage system that has the capacity to store the regenerative energy produced from the railway vehicles. The flywheel energy storage system (FESS) stores the regenerative electrical energy into the high speed rotational flywheel, by conversion the electrical energy into the mechanical rotational energy. Thus the FESS is composed of the energy conversion components, such as the motor and generator, mechanical support components, such as the rotational rotor, the magnetic bearings to support the rotor, and the digital controller to control the air gap between the rotor and the magnetic bearings. In this paper the design procedures for the rotor operating at the rigid mode and the magnetic bearings to support the rotational rotor without contact are presented.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.132-141
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• 2013

In this paper, method using electric braking from stop area to high-speed area was presented in order to improve air-brake. And electric braking method can be improved environmental problems, efficiency, economy, etc. Method for electrical complete braking are two ways that method of inserting series resistance between the motor and the inverter, and method of inverter output voltage increase. In this paper, use series resistance insert method because economical and easy to apply. In addition, Series resistor is used short circuit method for reduce the power loss. In improved efficiency and the laboratory environment for secure braking, resistance insert method and inverter output voltage increase method showed same characteristics in all areas.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.3
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• pp.244-252
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• 2002

In this paper, do link ripple currents for three-phase ac/dc/ac PWM converters feeding adjustable speed ac machine drives are analysed in a frequency domain. The expression of the harmonic currents is developed by using switching functions of the converter and exponential courier series expansion. The effect of the displacement angle between the switching Periods of line-side converters and motor-side inverters on the dc link ripple currents is Investigated. Also, the influence of asynchronization of PWM is observed. The result of analysis is compared with frequency spectrum which results from PSIM simulation. The proposed analysis technique is useful to understand the principles of P% and to derive an equivalent model of the dc link capacitors in a high frequency range.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.29-30
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• 2017

본 논문에서는 7상 BLDC 전동기를 이용한 수중 부하 시스템에서 전동기의 고속 운전 영역 확장을 위한 자동 진상각 알고리즘을 제안한다. 고속 운전 영역 운전 시 역기전력 상승에 따라 전류 지연 현상이 발생한다. 이를 보상하기 위해 기존의 제어 방식은 Look-Up Table을 이용한 진상각 방식 또는 추가적인 하드웨어를 구성하여 제어한다. 이는 운전점이 변경될 경우 제어 특성이 현저히 나빠지고, 전동기의 제정수에 의존적이고, 제어 시스템의 부피 및 비용 증가와 같은 문제를 야기 시킨다. 본 논문은 진상각 인가를 통해 확보할 수 있는 유효 전압을 계산하고 안티와인드업 출력 전압을 이용하여 필요한 진상각을 자동적으로 인가한다. 본 논문에서 제안하는 방식은 컴퓨터 시뮬레이션을 통해 비교 및 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.963-968
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• 2009

This paper deals with shrink fit analysis of rotor by 2D cross-section, 2D axis-symmetry, and 3D FEM model. And this paper presents 2nd order approximation function of thermal expansion displacement by design variables (shape dimension, heating temperature, sleeve length, interference etc.), table of orthogonal array and RSM(response surface methodology). The possibility of the rotor with shrink fit is evaluated by thermal expansion displacement. If thermal expansion displacement is larger than interference, shrink fit enable to make the rotor. 2D axis-symmetry model and 3D model are more reasonable than 2D cross-section model, because stress and strain is different along length of shaft.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.730-738
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• 2007

As well known when the linear machine is operated between two points repeatedly under positioning control, there are various positioning error at the moment of zero speed owing to the non-linear disturbance like as unpredictable friction force. To remove this positioning error, a simple least order disturbance observer is introduced and is actually implemented in this study. Due to this simple algorithm the over-all machine system can be modified to simple arbitrary given one-mass load without any disturbance. So, the total construction process for positioning control system is much easier than old one. Moreover, to generate a proper effective position profile with the limited actual machine force, a very powerful on-line mass identification algorithm using the load force estimator is presented. In the proposed mass identification algorithm, the exact load mass can be calculated during only one moving stage under a normally generated position profile. All presented algorithm is verified with experimental result with commercial linear servo machine system.