• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.459-465
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• 2017

This paper describes a performance analysis of self-excited eddy current brake(SECB). Stator winding of SECB is connected by capacitor instead of voltage source, and SECB's braking force is generated by L-C resonance. SECB has wide range of driving and nonlinear inductance as well. Therefore, it is important to select capacitance based on the value of inductance. This paper discusses about the process of deciding capacitance and the change of resonance frequency based on the inductance change in each speed. Also the braking force was confirmed by the experimental model of SECB.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.744-750
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• 2001

Higher directivity acoustic transducer using the self-demodulation effect was fabricated. The structure of transducer was designed such as dimension and support type of the piezoelectric element, the vibrating metal plate, and the housing case. Based on the design, the transducer was fabricated and measured its acoustic characteristics. Also, AM modulated driving circuit was designed for using the self-demodulation effect. The piezoelectric sounder with 200kHz resonant frequency and 20kHz bandwidth was designed by considering the sharp directivity and the sound pressure. The design and fabrication method worked in this study can be utilized in development of various speakers with higher directivity and broader bandwidth.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.1005-1018
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• 2017

This paper proposes an App Visualization (AppV) based on IoT Self-diagnosis Micro Control Unit (ISMCU) for accident prevention. It collects a current status of a vehicle through a sensor, visualizes it on a smart phone and prevents vehicles from accident. The AppV consists of 5 components. First, a Sensor Layer (SL) judges noxious gas from a current vehicle and a driver's driving habit by collecting data from various sensors such as an Accelerator Position Sensor, an O2 sensor, an Oil Pressure Sensor, etc. and computing the concentration of the CO collected by a semiconductor gas sensor. Second, a Wireless Sensor Communication Layer (WSCL) supports Zigbee, Wi-Fi, and Bluetooth protocol so that it may transfer the sensor data collected in the SL to ISMCU and the data in the ISMCU to a Mobile. Third, an ISMCU integrates the transferred sensor information and transfers the integrated result to a Mobile. Fourth, a Mobile App Block Programming Tool (MABPT) is an independent App generation tool that changes to visual data just the vehicle information which drivers want from a smart phone. Fifth, an Embedded Module (EM) records the data collected through a Smart Phone real time in a Cloud Server. Therefore, because the AppV checks a vehicle' fault and bad driving habits that are not known from sensors and performs self-diagnosis through a mobile, it can reduce time and cost spending on accidents caused by a vehicle's fault and noxious gas emitted to the outside.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4123-4141
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• 2019

Autonomous driving technology is divided into 0~5 levels. Of these, Level 5 is a fully autonomous vehicle that does not require a person to drive at all. The automobile industry has been trying to develop Level 5 to satisfy safety, but commercialization has not yet been achieved. In order to commercialize autonomous unmanned vehicles, there are several problems to be solved for driving safety. To solve one of these, this paper proposes 'A Deep Learning Part-diagnosis Platform(DLPP) based on an In-vehicle On-board gateway for an Autonomous Vehicle' that diagnoses not only the parts of a vehicle and the sensors belonging to the parts, but also the influence upon other parts when a certain fault happens. The DLPP consists of an In-vehicle On-board gateway(IOG) and a Part Self-diagnosis Module(PSM). Though an existing vehicle gateway was used for the translation of messages happening in a vehicle, the IOG not only has the translation function of an existing gateway but also judges whether a fault happened in a sensor or parts by using a Loopback. The payloads which are used to judge a sensor as normal in the IOG is transferred to the PSM for self-diagnosis. The Part Self-diagnosis Module(PSM) diagnoses parts itself by using the payloads transferred from the IOG. Because the PSM is designed based on an LSTM algorithm, it diagnoses a vehicle's fault by considering the correlation between previous diagnosis result and current measured parts data.

• 한국정보전자통신기술학회논문지
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• 제14권3호
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• pp.223-230
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• 2021

현재 자율주행차량은 테스트 이후 상용화를 눈앞에 두고 있다. 그러나 아직 자율주행차량이 완벽히 상용화되지 않았음에도 81건의 사고가 발생했으며, 사고를 피하기 위한 차량의 주행 방식은 LiDAR에 많이 의존하고 있다. 현재 상용화된 3레벨 자율주행차량이 4레벨 자율주행차량으로 발전하기 위해서는 기존에 수집되는 정보보다 더 많은 정보를 수집해야만 한다. 따라서 본 논문에서는 기존의 자율주행차량에서 수집하는 정보인 도로 정보, 기상정보를 포함하여 차량이 주행 중인 도로의 거칠기와 자기 자신 및 주변 차량의 탑승객 상태를 정확하게 인식하여 차량이 처한 위기 상황을 정확하게 계산하는 Driving Situation Judgment System (DSJS)을 제안한다. DSJS의 PDM에 대한 실험 결과, PDM은 기존 차량의 탑승객 인식 시스템보다 평균적으로 15.52% 더 정확하게 탑승객을 분류할 수 있었다. 본 연구는 기존 3단계 자율주행차량이 수집하는 데이터보다 더 다양한 종류를 수집하여 4단계 자율주행차량을 달성하는 기초연구가 될 수 있다.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.454-461
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• 1999

A concrete floor trowel machine, developed in the U.S in 1990's, consists of only two rotary trowels, and doesn't need any other mechanism for motion such as wheels. When the machine flattens a concrete floor with its rotary trowels, the machine can move in any direction by utilizing the unbalanced friction forces occurring between the rotary wheels and the floor when the trowels are tilted in appropriate directions. In order to automate the trowels machine, this paper proposed the self-propulsive concrete finishing trowel robot which has twin trowels. For the control of the robot, this paper discussed the following. Firstly, the dynamics model of the driving frictional force applied on each trowel from the floor is derived. Secondly, the relationship between the driving force for the robot and the control variable of the robot is derived. Finally, the basic motion of the robot are realized by using the obtained relationship. This paper figures out how the concrete floor finishing robot with tow trowels moves and will contribute to realizing it.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.521-527
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• 2001

The dynamic performance analyses and tests for a 50kW turbo-generator (KIMM-TG50) were carried out. The operating concept of this machine is that it gets the initial driving force from the built-in motor-generator until it reaches its self-sustaining speed of 40,000 rpm, and then the driving mode is changed to self-operating mode by the combustor installed between the centrifugal compressor and the turbine. Due to winding mistake of motor-generator, the system could go only up to 22000 rpm by the motor so that high pressure air externally fed into the turbine was utilized to get the system to run up to 62,000 rpm thereafter. The vibration data collected during the tests revealed that the first bending critical speed is in near 5,600 rpm as predicted in the design stage of the rotor-bearing system, and that there were no other identifiable critical speeds up until 62,000 rpm due to high damping from the squeeze film damper-bearings supporting the rotor. This paper presented some of the experimental results along with dynamic performance predictions made in the design stage as a part of progress being made.

• 한국실천공학교육학회논문지
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• 제4권2호
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• pp.60-66
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• 2012

본 논문에서는 대학에서의 학습의 질을 높이기 위해 지금까지 연구된 많은 이론들을 정리하여, 더 나은 수업을 준비하고 실제로 더 높은 수준의 수업을 듣는데 도움이 되는 학습방법을 제안한다. 대학생들은 대학에 들어와서 자기주도적 학습 방법을 각자 확보하여, 학창시절에 전공 및 중요한 교양 과목을 효과적으로 학습하여야 한다. 그런데 대부분의 대학생들은 저학년일 때 이러한 자기주도적 학습방법을 확보하지 못한 상태에서 고학년으로 진급하게 된다. 그리고 그 때에 가서야 비로서 학습의 중요성을 인지하여 나름대로 학습할려 하지만 이미 학창시절의 상당기간이 지나 우왕좌왕하는 경향이 있다. 본 논문에서는 각종 기존의 각종 학습방법에 대해 소개 및 분석을 하였다. 그리고 학습목적찾기, 시간관리, 수업을 효율적이고 효과적으로 수강하기 위한 수업 준비에 대해 논의하였다. 그리고, 효율적인 학습법의 모델을 제안하였다. 제안한 방법은 각 학생들의 수준과 강의실 환경 등을 고려하여 적절히 선택적으로 적용한다면 효과적인 학습방법이 될 것으로 사료된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.269-270
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• 2006

Brake noise is classified according to frequency territory: judder, groan and squeal. Squeal noise of disk brake is a noise and self excited vibration with frequency of $1{\sim}10Khz$ caused by the friction force between the disk and the pad of the automobile. Passengers in a vehicle feel uncomfortable. It causes unstable characteristic to the brake system when you try to stop the vehicle. Thus this study aims to find in which conditions the vehicles are stable during the braking hour and find ways to decrease a squeal noise and the vibration by measuring various factors including squeal noise and self excited vibration between the pad and disk brake system during the braking hour. From the result the countermeasure for a squeal noise and a vibration decrease is established. Also the analyzed data is found to be useful and can be applied to the actual brake model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.150-151
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• 2007

We present an one-axis parallel-plate type of bulk micromachined torsional micromirror array with single crystalline silicon (SCS) fabricated on the glass substrate. Structurally, bottom electrodes (amophous silicon) in this mirror are DRIEed along the aluminum mirror patterns on SCS, which are self-aligned with mirror plates. Tracing the history of the micromirror study, we found that few papers have been published on research for uniform driving voltages based upon the tilting direction. If there is a slight misalignment during anodic bonding between top (mirror plate) and bottom electrodes, the non-uniformity of driving voltage will be led depending on two different tilting direction. This paper discusses how much the pull-in voltages can be different due to misalignment between two electrodes. Moreover, We achieve uniform pull-in voltage regardless of misalignments in photolithography and anodic-bonding between two individual layers.