• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.423-424
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• 2020

기후변화 규제에 대응하기 위해 자동차 산업에서는 엔진의 배기가스는 줄이고, 출력은 향상시키는 과급기를 필요로한다. 전동식 과급기에 필요한 압축기는 초고속의 모터회전이 필요하고, 압축기 전기모터의 속도, 회전자의 위치 추정을 위해서는 센서가 필요하다. 하지만 센서의 사용은 비용의 증가, 신뢰도저하 등과 같은 문제점들이 있고, 이러한 문제점들을 해결하기 위해 여러 센서리스 방식들이 사용되고 있다. 본 논문에서는 PSIM 시뮬레이터를 이용하여 전류모델 기반의 센서리스 방식으로 동기전동기(SPMSM)를 구동하는 0.8초 내로 90000rpm의 속도까지 도달하도록 시뮬레이션을 구현하였다.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.118-127
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• 2004

The purpose of this study is experimentally to analyze that intake port swirl, injection system and turbocharger have an effect on the engine performance and the emission characteristics in a V8 type turbocharged intercooler D.I. diesel engine of the displacement 16.7ι, and to suggest the improvement of engine performance. Generally to enhance engine power, TCI diesel engine is put to practically use turbo-charged intercoler in order to increase boost efficiency which is cooled boost air. As results of considering the factors of the intake port of swirl ratio 2.25, compression ratio 17.5, re-entrant 8.5$^{\circ}$ combustion bowl, nozzle hole diameter ${\Phi}$0.33*3+${\Phi}$0.35*2, nozzle protrusion 3.18mm, injection timing BTDC 12$^{\circ}$CA and turbo charger (compressor 0.6A/R+46Trim, turbine 1.0A/R+57Trim) is the best in the full range of operating in the engine performance and the exhaust characteristics of NO$\_$x/ concentration. Therefore their factors are appropriated as intake system, injection and turbocharger system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.229-234
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• 2017

In this study, TiAl alloy was fabricated by a centrifugal casting method for turbo charge of automotive. Optimum conditions for defectless morphology using various ceramic mold were investigated. The crystal structure, microstructure, and chemical composition of the TiAl prepared by centrifugal casting were studied by X-ray diffractometer (XRD), optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS), microvickers hardness analyzer (HV). Two kinds of dendrite structures were observed with 4-fold and 6-fold symmetries. The FE-SEM, EDS and HV examinations of the as-cast TiAl showed that the thickness of the oxide layer (${\alpha}$-case) was typically less than $50{\mu}m$.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.56-64
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• 2017

A high altitude long endurance aircraft which carries out missions of environmental research communication relay or ground surveillance, should have the capacity to cruise in the stratosphere at a relatively low speed for a long dwell time without the necessity of refueling. When one considers the propulsion system for such an aircraft, a reciprocating engine with a serial turbo-charger system to boost rarefied ambient air up to sea level condition, would represent an good, informed and practical choice regardless of the cruising altitude of the aircraft. In this paper, high altitude long endurance aircraft developed by overseas research groups and research trends, regarding multi-stage turbocharger systems, are introduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.536-540
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• 2018

As the performance of engines improves, the temperature of engines is increasing, resulting in a high piston temperature. An excessively high piston temperature may result in torque drop or engine failure. An oil jet is used to reduce the piston temperature. In this study, to monitor the effect of oil jet, a templug was used to measure the piston temperature. A templug is a kind of sensor and the hardness of the templug changes according to the piston temperature. Using a templug, the maximum temperature of the piston was measured with and without an oil jet. The piston temperature was lowered using the oil jet. The highest temperature region changed from the center crown to the front/rear area. In addition, the temperature difference between the highest and lowest regions became smaller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.5
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• pp.502-509
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• 2010

A test facility which can simultaneously measure turbocharger operating condition variables and vibro-acoustic emission in the situations that are quite similar to real internal combustion engine operating conditions has been introduced. Using this facility, a new method sweeping from full open throttle to deep surge region along constant speed curves can be utilized instead of the stationary method that has been traditionally used to obtain turbocharger compressor maps. Data covering an extensive range of the compressor performance map have been collected and analyzed. An experimental study is performed to define a noise diagram that correlates vibro-acoustic measurements to aerothermodynamic operating conditions. An instrumentation set in the facility allows the automatic definition of the operating point on the turbine and compressor map of the turbocharger. Also, radiated sound pressure and casing vibration data corresponding to the point are obtained by a microphone in the vicinity of the compressor casing and an accelerometer on the casing. The major source(s) of noise at specific operating point on the map can be easily identified with these maps. Also, acoustic characteristics of a given turbocharger at the vicinity of the surge as well as in the surge are also defined. Finally, the possibility to define mild surge region of a turbocharger using vibro-acoustic measurements is studied.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.24-30
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• 2016

In this study, a 2W micro-gas turbine engine was designed using micro-electro-mechanical systems (MEMS) technology, and experimental investigations of its potential under actual combustion conditions were performed. A micro-gas turbine (MGT) contains a turbo-charger, combustor, and generator. Compressor and turbine blades, and generator coil were manufactured using MEMS technology. The shaft was supported by a precision computer numerical control (CNC) machined static air bearing, and a permanent magnet was attached to the end of the shaft for generation. A heat transfer analysis found that the cooling effect of the air bearing and compressor was sufficient to cover the combustor's high temperature, which was verified in an actual experiment. The generator performance test showed that it can generate 2W at design rotational speed. Prototype micro-gas turbine generated maximum 1 mW electric power and lasted up to 15 minutes.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.151-158
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• 2007

The static and dynamic behaviour of VGT and EGR systems has a significant impact on overall engine performance, fuel economy and exhaust emissions. This is because they define the state and composition of the air charge entering the engine. This work focused on the effect of the aperture ratio of VGT and EGR on the emission and flow characteristics under partial loads conditions. The investigation carried out using 2 liter PCCI 4 cylinder diesel engine with VGT and EGR. The result of this study shows that smoke increases with increasing EGR rate and NOx decreases with increasing EGR rate. It was also found that the residual gas contents greatly impact on soot emission under partial load condition. Finally, it can be concluded that VGT and EGR aperture ratio can greatly impact not only on soot and NOx but also air charging.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.8
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• pp.671-675
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• 2014

Nozzle ring is an important part of turbocharger which is applied to today's most diesel engines. Turbo charger nozzle ring is difficult to process and takes a high cost and a long time relatively. For this reason, it is largely produced by using a precision casting. Investment method, the representative technology of precision casting, has excellent dimensional accuracy and can produce complex shapes relatively easily. However, it is difficult to avoid the casting defects such as shrinkage cavity and short shot. This study is to predict the casting defects which could be occurred during the investment method by use of finite element analysis software and to design the process and mold of the marine turbocharger nozzle ring.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.65-73
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• 2007

The use of an Exhaust Gas Recirculation(EGR) for a diesel engine with variable geometry turbocharger(VGT) has confronted how to obtain the amount of EGR for NOx reduction requirement at wide operating range and less side effect. Through a combined effort of modeling(wave action simulation) and experiment, an investigation into the effect of EGR area ratio and pipe length on EGR characteristics of common rail diesel engine with VGT has been performed. For accurate computation, calibration of constants involved in empirical and semi-empirical correlations has been performed at a specific operating point, before of its use for engine simulation. From the results of this study, it was found that EGR rate is sharply increased with increasing EGR area ratio until area ratio of 0.3. However, the effect of EGR area ratio on EGR rate is negligible beyond this criteria. This study also investigates the effect of EGR pipe length on a EGR amount and pulsating flow characteristics at EGR junction. The results showed that the longer EGR pipe length, the lower EGR amount was achieved due to the flow loss resulting in lower amplitude of pressure wave.