• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.211-218
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• 2021

A recent spread of personal mobility devices such as electric kickboards has brought about a rapid increase in accident cases. Such vehicles are susceptible to falling accidents due to their low dynamic stability and lack of outer protection chassis. This paper presents the development of an automatic emergency braking system and a safe starting system as driving assistance devices for electric kickboards. The braking system employed artificial intelligence to detect nearby threaening objects. The starting system was developed to disable powder to the motor until when the driver's boarding is confirmed. This study is meaningful in that it proposes the convergence technology of advanced driver assistance systems specialized for personal mobility devices.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.422-425
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• 2001

권선형 유도전동기는 기동시에 충분히 큰 저항을 외부에서 삽입하여 기동전류를 작게하는 동시에 기동 토크를 크게 할 수 있다. 또한, 유도전동기의 각 기동 방식중에서 가장 우수한 시동특성을 가지고 있으며 크레인, 시멘트공장 등 중부하 시동이 요구되는 경우 널리 사용되고 있다. 권선형 유도전동기 드라이브 시스템의 전류, 토크, 위치 및 속도 등의 제어를 위하여 일반적으로 산업현장에서는 Pl 제어기가 많이 적용되고 있다. 그러나 이러한 시스템은 센서 부착시 여러가지 환경적 제약으로 인한 전체시스템의 성능 저하를 가져올 수 있어 이를 개선하기 위한 센서리스 벡터제어가 활발히 연구되고 있다. 본 논문은 권선형 유도 전동기의 센서리스 벡터제어를 위해 MRAS 기법을 적용하였고, 기존의 MRAS 기법 적용시 발생하는 파라미터 변동에 따른 속도추정오차를 개선하기 위해 센서리스 벡터제어의 속도제어에 크게 영향을 미치는 고정자 저항을 온라인으로 튜닝함으로서 파라미터 변화에 강인한 센서리스 속도제어를 구현하였다. 제안된 기법의 타당성 및 유효성을 디지털 컴퓨터에 의한 시뮬레이션에 의해 확인하였다.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.76-85
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• 2016

This study introduces the system layout and control strategy necessary to start and operate a fuel processor in a wide range of temperatures where a gasoline was selected as the fuel of fuel processor considering logistic support of Korea Army. The autothermal reformig(ATR) catalyst is heated to light-off temperature by combustion method in the initial stage. In order to ignite the gasoline and air mixture stably, the glow plug is installed after ATR catalyst. When the catalyst is increased to light-off temperature, the reformer is operated from initiation to steady state conditions as follows: Partial oxidation(POX) mode, partial ATR mode, full ATR mode. Finally the start-up and control strategy is validated by the operational test of gasoline fuel processor at low and room temperature. As a result the gasoline fuel processor is able to start-up within 40 min and to produce the reformate gas which has 37 ~ 42 vol.%(dry basis) of $H_2$ and 0.3 vol.% of CO.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.184-186
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• 2008

리니어 발전기는 리니어 엔진의 시동에 필요한 연소조건을 만들기 위하여 전동기로 동작하다가 연소가 안정화되면 발전기로 동작을 하여 PCS(Power Conditioning System)를 통해서 전력을 계통으로 보내주게 된다. 리니어 엔진의 초기 시동을 하기 위하여 발전기는 운동주파수와 운동방향, 그리고 힘의 크기를 제어해야 하며, 발전 시에는 엔진의 동작에 맞도록 전력을 제어해야 한다. 이를 효율적으로 제어하기 위하여 MSC(Machine Side Converter)에서 상전류를 독립적으로 조절할 수 있는 H-bridge로 각 상을 구성하였다. LSI(Line Side Inverter)는 DC-Link 전압을 제어하여, MSC의 동력/발전 동작에 따라서 전력을 계통에서 받아오거나 전력을 계통으로 보내는 동작을 한다. 본 연구에서는 리니어 발전기 모델링를 통해서 PCS 제어 알고리즘을 확인하고 전체 시스템과 연동을 한 실제 운전특성에 대하여 살펴보았다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.210-214
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• 2004

This study proposes a design method for blade pitch control mechanism in order to regulate the power and to improve the starting characteristic. This power control unit which is assembled by spring and mass is planing to equip with 1kW class wind turbine system which is developed for low wind speed area like Korea. For the design of this control unit, the proper geometry of the hub was designed and the calculation of the mechanics was carried out. Especially, It is expected that the operational efficiency will be improved because of additional high pitch starting function by using 2 step spring structure.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.5
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• pp.52-56
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• 1996

Fluorescent lamps are widely accepted to energy efficient commercial lighting applications. In designing a fluorescent lamp system, a ballast design heavily relies on the characteristic of a fluorescent lamp under consideration. Especially, at startup time, the transient characteristic of a fluorescent lamp puts much tighter specification of a design. In this paper, based on the transient characteristic at the startup time, a transient behavioral model of a fluorescent lamp is presented with an equivalent circuit. The model is applicable to the wide range of fluorescent lamps provided by different manufacturers. The experimental results are compared with the results provided by PSPICE simulation. The result shows the model is effective In practice. As a result, we could identify more accurate startup constraints to decide the design of either an electro mechanical or an electronic ballast.

• Journal of IKEEE
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• v.18 no.2
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• pp.185-191
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• 2014

In this paper, we have implemented the low temperature fluidity test system with the composited package fuel heater, which has tested the low temperature fluidity and start time to evaluate the performance. Then we have compared the separation and the unified fuel heater type at $+20{\sim}-30^{\circ}C$. Also, we have tested the flowing pressure and start time, power consumption of heater. By comparing the performance with several condition, the experimental results obtain an improved start time of 23% and low temperature fluidity of 19%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7A
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• pp.568-573
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• 2009

This paper presents a step-down DC-DC converter with On-chip Compensation for battery-operated portable electronic devices which are designed in O.13um CMOS standard process. In an effort to decrease system volume, this paper proposes the on chip compensation circuit using capacitor multiplier method. Capacitor multiplier method can minimize error amplifier's compensation capacitor size by 10%. It allows the compensation block of DC-DC converter be easily integrated on a chip and occupy less layout area. But capacitor multiplier operation reduces DC-DC converter efficiency. As a result, this converter shows maximum efficiency over 87.2% for the output voltage of 1.2V (input voltage : 3.3V), maximum load current 500mA, and 25mA output ripple current. This voltage mode controled buck converter has 1MHz switching frequency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.213-217
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• 2017

Since more than 30% of the liquid rocket engine failures occur during the start-up process, and the Space Shuttle Main Engine (SSME) is especially sensitive to small changes in propellant conditions, a 2% error in the valve position or a 0.1sec timing error could lead to significant damage of the engine, simulation modeling of start-up process is important. However, there are many difficulties associated with engine start-up process caused by nonlinear mass flow and heat transfer characteristics associated with filling an unconditioned engine system with cryogenic propellants. In this paper, we modelled a SSME simulation model using partially Computational Fluid Dynamics (CFD) method to solve these problems and checked the performance by comparing with the performance of the simulation model using the lumped method under the state of normal condition.

• Journal of IKEEE
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• v.17 no.1
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• pp.63-70
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• 2013

In this paper, we have implemented the performance evaluation system of the unified fuel heater for CRDI diesel engine. If the diesel engine be cold by low temperature in winter, then that makes the waxing materials like a paraffin and is the source of poor engine starting. The unified fuel heater is the barrow meter that estimate the start performance of diesel engine, and be tested by test chamber. The chamber perform the normal temperature, an extremely low temperature, an operating performance in an extremely high temperature, the resistance operation delay time and current operation delay time in setting up test resistance, the bimetal delay time test in temperature variation, the current and resistor test of the composited heater, a heating operation test.