• Title/Summary/Keyword: 시동성능

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An Empirical Study on the Quality Reliability of the Start-up performance of the Fixed Wing Aircraft at low temperature (고정익 항공기 저온 시동 성능의 품질 신뢰성 향상에 관한 실증적 연구)

  • Kim, DW;Jeong, SH
    • Journal of Korean Society for Quality Management
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    • v.46 no.1
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    • pp.169-188
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    • 2018
  • Purpose: The purpose of this study is to analyze low-temperature starting performance of the light attacker and to search and improve the aircraft system including battery and Battery Charge and Control Unit(BCCU). Methods: In order to improve the starting up performance of the light attacker at low-temp, various deficiency cause were derived and analyzed using Fault Tree Analysis method. As a result, it was confirmed there were drawbacks in the charging and discharging mechanism of the battery. The inactivation of the battery's electrolyte at low-temp and the premature termination of the battery charge were the main cause. After long error and trial, we improved these problems by improving performance of battery and optimizing the charging algorithm of BCCU. Results: It was confirmed that the problems of starting up failures were solved through the combined performance test of the battery and BCCU, the ground test using the aircraft system and the operation test conducted by Korea Airforce operating unit for 3 months in winter. Conclusion: This study showed that the improvement of quality reliability was achieved and thus the start-up performance issue of the light attacker has been resolved at low temperature. And it is expected that the design methodologies of temperature-affected electrical system of aircraft will contribute to the development of the aircraft industry in the future.

Self-Starting Characteristics of Blades for Vertical Axis Wind turbine (수직축 풍력발전용 날개의 기동력특성)

  • Kim, Sung-Hoon;Kim, Young-Ik;Lee, Joon-Min
    • Journal of Energy Engineering
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    • v.29 no.1
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    • pp.34-43
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    • 2020
  • A study has been done for self-starting torque of vertical axis wind turbine blade. It is especially concentrated to evaluate the torque coefficient before starting rotation. Two different aerofoils(AMI903 and AMI904) are proposed to benchmark the possible best blade(supercritical airfoil) for self-starting performance. Torque coefficients in the tangential direction of rotation are given with respect to the angle of attack in terms of drag coefficient and lift coefficient. Torque coefficient shows that the effect of Reynolds number is minimal. The thicker blade(AMI904) between two different proposed airfoils has bigger torque coefficient, which is attributed to lower lift coefficient and higher drag coefficient.

A Study on the Control Algorithm for Engine Clutch Engagement During Mode Change of Plug-in Hybrid Electric Vehicles (플러그인 하이브리드 차량의 모드변환에 따른 엔진클러치 접합 제어알고리즘 연구)

  • Sim, Kyuhyun;Lee, Suji;Namkoong, Choul;Lee, Ji-Suk;Han, Kwan-Soo;Hwang, Sung-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.9
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    • pp.801-805
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    • 2016
  • In this paper, engine clutch engagement shock is analyzed during the mode change of plug-in hybrid electric vehicles. Multi-driving mode includes the EV (electric vehicle) mode, HEV (hybrid electric vehicle) mode, and engine operating mode. Depending on the mode change, the engine clutch is either engaged or disengaged. The magnitude of shock during clutch engagement is very important because it impacts vehicle acceleration and clutch synchronization speed, which affects ride comfort substantially. The performance simulator of plug-in hybrid electric vehicles was developed using MATLAB/Simulink. The simulation results show that the mode change control algorithm is necessary for minimizing shock during clutch engagement.

Micromachined Multiple Gas Sensor for Automotive Ventilation and Air Conditioning Systems (미세기계가공된 자동차 HVAC 시스템용 다중 가스센서)

  • Choi, W.S.;Lee, S.H.;Kim, S.D.;Park, J.S.;Park, H.D.;Min, N.K.
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1637-1638
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    • 2006
  • HVAC 시스템은 쾌적하고 깨끗한 운전환경을 만들어 줌으로써 운전자에게 향상된 안락성과 안전성을 제공한다. 이때 센서는 시시각각으로 변화하는 차실 내외의 환경변화에 대한 정보를 검출하여 HVAC 제어 유니트에 제공한다. 현재 HVAC 시스템에 사용되고 있는 후막 가스센서는 소자 크기와 소비전력이 크고, 제작공정이 까다로워 생산성이 낮은 단점이 있다. 이와 같은 문제점을 해결하기 위해서 최근에는 초소형화, 저소비전력, 대량생산에 의한 저가격화가 가능한 MEMS 가스센서의 연구개발이 활발히 진행되고 있다. 본 연구에서는 MEMS 구조체를 이용한 마이크로 가스센서를 설계 및 제작하였고, 감도특성을 고찰하였다. 가스 감지막은 금속산화물 페이스트를 스크린 프린팅 하는 종래의 방법 대신 MEMS 구조체에 적용 가능한 sol-gel 프로세스에 의해 형성하였다. 또 가스 감지전극과 micro-heater를 동일 평면상에 제작, 공정을 간소화하여 저가화를 시도하였다. MEMS 구조체 위에 제작된 Pt 박막 micro-heater의 인가전압에 따른 발열특성을 조사한 결과, 발열온도가 인가전압에 비례하는 이상적인 선형성을 나타내었으며, $300^{\circ}C$의 동작 온도에 도달하기 위해 65mW 이하의 저전력 동작이 가능하였다. 가스 센서의 감도특성 확인 실험은 CO 가스 10ppm, NO 가스 0.3ppm을 기준으로 수행되었으며, CO 및 NO에 대해 Rs(sensitivity, 가스반응저항/초기저항) 값은 각각 0.753 과 2.416로 우수한 성능을 나타내었다.

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Failure Case Studies of Sensors for Electronic Controlled Engine in LPG Vehicle (LPG 자동차에서 전자제어엔진용 센서의 고장사례에 관한 연구)

  • Kim, Chung-Kyun;Lee, Il-Kwon
    • Journal of the Korean Institute of Gas
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    • v.14 no.4
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    • pp.56-62
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    • 2010
  • The purpose of this paper analyzes and investigates the failure case studies of electronic control sensors for a LP gas engine. The malfunction of crank angle sensor, which controls a fuel injection volume of LP gas, displays an irregular and non-uniform pulse wave form. The pulse form, which is related to the noise of the crank angle sensor, displays at the rectangular peak with a saw-toothed shape and is intermittently generated with a level of 2.46V noise signal. The malfunction of No. 1 TDC sensor in which is caused from the internal disorder affects to the reduction of engine power and engine stop suddenly. If the malfunction of oxygen sensor is occurred due to a wiring problem of a sensor connector, the LP gas vehicle may produce a shaking and disharmony of an engine because of no signal supply from the oxygen sensor. The air cleaner replica produces the clogging of continuous supply of fresh air. This may cause the retardation of vehicle acceleration and engine disharmony intermittently.

A Study on the Chilling Start-up Characteristics and Performance of a Gas Loaded Heat Pipe (가스내장 히트파이프의 냉시동특성과 성능에 관한 연구)

  • Hong, Sung-Eun;Kang, Hwan-Kook
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.11
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    • pp.915-922
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    • 2006
  • Considering heat pipe design principles in fabrication and operational performances, water is one of the most recommended working fluids to make mid to low tempera lure heat pipes. But the conventional water heat pipes might encounter the failure in a cold start-up operation when socked at a chilling temperature lower than the freezing point. If they are subjected to a heat supply for start-up at a temperature around $-20^{\circ}C$, the rate of the vapor flow and the corresponding heat transfer from the evaporator to the condenser is so small that the vapor keeps to stick on the surface of the chilling condenser wall, forming an ice layer, resulting in a liquid deficiency in the evaporator. This kind of problems was resolved by Kang et al. in 2004 by adopting a gas loading heat pipe technology to the conventional water heat pipes. This study was conducted to examine a chilling start-up procedure of gas loading heat pipes by investigating the behaviors of heat pipe wall temperatures. And the thermal resistance of the gas loaded heat pipe that depends on the operating temperatures and heat loads was measured and examined. Two water heat pipes were designed and fabricated for the comparison of performances, one conventional and the other loaded with $N_2$ gas. They were put on start-up test at a heat supply of 30 W after having been socked at an initial temperature around $-20^{\circ}C$. It was observed that the gas loaded one had succeeded in chilling start-up operation.

An Experimental Study on Internal Drag Correction of High Speed Vehicle Using Three Probes (세 가지 프로브를 이용한 초고속 비행체 내부 항력 보정 기법의 실험적 연구)

  • Jin, Hyeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.7
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    • pp.529-537
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    • 2021
  • Wind tunnel tests were carried out with a scramjet high speed vehicle. Since the scramjet engine does not have a compressor, it has a simple structure, but it is important to design the intake for the supersonic combustion in the combustion chamber. In this study, internal flow characteristics and the starting condition were analyzed by measuring the pressure at the isolator exit just before the combustion chamber, and the intake performance parameters were calculated and compared the result on every Mach number. The aerodynamic characteristics of the flow-through high speed vehicle were analyzed and internal drag correction is required to precisely analyze the aerodynamic characteristics. In this paper, an experimental technique using three probes for internal drag correction was proposed. By applying internal drag correction, it was able to figure out the effect of the internal flow on the aerodynamic force of the vehicle.

Performance Evaluation of the Vibro Hammer with Variable Amplitude by Field Tests (현장실험을 통한 저진동·저소음 진폭가변형 진동해머 성능 평가)

  • Han, Jin-Tae;Lee, Joonyong;Choi, Changho;Park, Jeong-Yel
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.3
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    • pp.1-12
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    • 2015
  • During installing sheet piles for an impermeable wall or a retaining wall, vibratory hammers are widely used. Among vibratory hammers, a hydraulic hammer is used most commonly. However, a hydraulic hammer causes excessive vibration and noise due to resonance by change of natural frequency according to movements of eccentric shaft when the hammer starts and stops. In this study, new variable amplitude type hammer is developed in order to reduce the vibration and noise due to resonance produced in starting and stopping the hammer. By controlling horizontal angle in two pairs of eccentric body inside of the hammer, the amplitude and vibration of the new hammer can be controlled. The performance tests with the new hammer and existing hammers such as the hydraulic hammer and electric hammer are carried out, and the new hammer shows reduced vibration and noise results in comparison with existing hammers from performance tests. Also, this study shows that penetration rates of sheet pile using the new hammer increase due to impellent force of a backhoe in comparison with the electric hammer and penetration rate increase in comparison with a general hydraulic hammer, since the new hammer can control the amplitude during penetration of sheet pile according to soil condition.

Analysis of Oil Performance by Different Type of Engine Oil In the Field (필드조건, 엔진오일의 종류에 따른 오일성능 분석)

  • Kim, Young Whan;Song, Jun Hee;Kim, Han Joo
    • Journal of Energy Engineering
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    • v.26 no.3
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    • pp.131-136
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    • 2017
  • Automobile engine oil is the most important lubricant for operating as the engine is started. Recently, manufacturers of the automotive industry and lubricants are considerably improving the quality of oil with additive to extend change cycle period. Most customers are recommended genuine oil among different types from shop expert. Through this report we suggest another reference point for consumer to pick highly efficient lubricant. This report is investigated oil compounds to compare with 6 different automotive considering actual running condition for 7 months. we conducted experiment from physical and chemical perspectives. In the field, through various experiments oil compounds between mineral oil and synthetic oil are largely distinguished in oxidation, viscosity, fluid and TBN. These are influenced by engine part wear as piston, bearing etc. Comparing various investigation with different oil the performance of synthetic oil is shown better condition in flash point, oxidation stability and also found less in change pollutant iron, Al compounds. Additives of oil show clear difference Ca level in detergent-dispersant both mineral oil and synthetic oil. And Zn in extreme pressure additives and P in Lubricity improver make no difference to both.

Development Status of Technology Demonstration Model for Staged Combustion Cycle Engine (다단연소사이클 엔진 기술검증시제 개발 현황)

  • Kim, Chaehyoung;Lee, Jungho;Woo, Seongphil;So, Younseok;Yi, SeungJae;Lee, Kwang-Jin;Cho, Namkyung;Han, Yeoungmin;Kim, Jin-han
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.4
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    • pp.104-111
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    • 2019
  • Staged combustion cycle engines exhibit higher combustion performance compared with open cycle engines with a gas generator. An advanced research of the staged combustion cycle engine is going on for the next program following the KSLV-II program. Various experiments have been carried out for the technology demonstration model, TDM0A and TDM0B. The experiments on the combustion performance are aimed to understand the engine start condition and combustion characteristics. They also aim to develop the oxidizer-rich pre-burner and the combustor of the staged combustion cycle engine. The engine-shaped model, TDM1A is fabricated based on the experimental data. The combustion experiment of the TDM1A shows that the combustion pressure of the combustor is approximately 91 bar and the turbine rotation is approximately 28,00 rpm. The result is stable and satisfies the development requirements. The present paper reports on the development process and characteristics of engine models from TDM0A to TDM1A.