• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1140-1141
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• 2006

Maglev is a non-contact traffic system in which cars are supported by magnetic force instead of wheels. This is a ground-breaking traffic system providing superior environmental friendliness and cost efficiency due to the minimal noise and vibration offered by its non-contacting nature. We study the present specification and performance of the low speed urban maglev system in Korea and other countries. After set up the test line, to success the "Commercialization of Korean Urban Maglev System" project, we establish proper requirement of maglev system in Korean environment on base of "Daejeon National Science Museum Maglev Establish Project".

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.42-45
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• 2001

Switched Reluctance Motors(SRM) are a promising candidated automotive drives of the next generations. The successful commercialization of SRM drives in automobiles depends highly on the developments of SRM design and control techniques. This paper descrives the control issues of SRMs, ranging from drive system structure, rotor position sensing and torque control. Both simulation studies and test results are presented for a 160W SRM drive for automotive application.

• 한국컴퓨터정보학회논문지
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• 제23권12호
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• pp.145-151
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• 2018

While commercialization of IoT technologies in the safety management sector is being promoted in terms of industrial safety of large indoor businesses, implementing a system for risk management of small outdoor work sites with frequent site movements is not actively implemented. In this paper, we propose an efficient dynamic workload balancing strategy which combined low-power, wide-bandwidth (LPWA) communication and low-power Bluetooth (BLE) communication technologies to support customized risk management alarm systems for each individual (driver/operator/manager). This study was designed to enable long-term low-power collection and transmission of traffic information in outdoor environment, as well as to implement an integrated real-time safety management system that notifies a whole field worker who does not carry a separate smart device in advance. Performance assessments of the system, including risk alerts to drivers and workers via Bluetooth communication, the speed at which critical text messages are received, and the operation of warning/lighting lamps are all well suited to field application.

• Current Optics and Photonics
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• 제6권1호
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• pp.51-59
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• 2022

Holographic display technology is one of the promising 3D display technologies. However, the large amount of computation time required to generate computer-generated holograms (CGH) is a major obstacle to the commercialization of digital hologram. In various systems such as multi-depth head-up-displays with hologram contents, it is important to transmit hologram data in real time. In this paper, we propose a rapid CGH computation method by applying an arraying of a down-scaled hologram with the multiplication of a shifted concave lens function array. Compared to conventional angular spectrum method (ASM) calculation, we achieved about 39 times faster calculation speed for 3840 × 2160 pixel CGH calculation. Through the numerical investigation and experiments, we verified the degradation of reconstructed hologram image quality made by the proposed method is not so much compared to conventional ASM.

• 한국정보통신학회논문지
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• 제22권6호
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• pp.903-909
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• 2018

2017년 12월 원주~강릉구간 고속철도 개통과 함께 250km/h급 철도통합무선망(LTE-R)이 세계 최초로 상용화되었다. LTE-R은 음성 및 영상 통화, 고속 데이터 전송, 커버리지 이중화 및 DU 이중화 등 많은 장점이 있으나 UL, DL 각 10MHz의 한정된 대역폭을 사용하므로 효율적인 무선자원 활용이 필요하다. 기존의 Unicast 방식은 주파수 효율이 제안적으로 사용자 수가 증가할 경우 망 부하로 인하여 서비스에 제한이 있으며 이는 안정성과 신뢰성을 보장해야 하는 LTE-R 특성 상 큰 문제로 이어질 수도 있다. 반면 eMBMS를 통한 Multicast 방식을 적용하면 영상데이터와 같은 대용량 데이터 전송수가 늘어도 안정적인 서비스 제공이 가능하다. 본 논문에서는 이론전 계산값과 시험을 통해 LTE-R 망 부하를 고려한 Unicast 기반의 사용자 임계수를 도출하고 향후 LTE-R의 eMBMS 상용화 적용을 위한 고려사항을 제시하고자 한다.

• 한국인터넷방송통신학회논문지
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• 제22권2호
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• pp.123-128
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• 2022

SRM(Switched Reluctance Motor)의 토크는 인덕턴스의 기울기에 비례하여 발생하기 때문에 비선형 토크 특성을 가지며 토크 맥동이 크고 소음이 심한 단점을 가지고 있다. 특히 SRM의 상용화에 가장 큰 장해 요인으로 작용하고 있는 것은 회전축에서 발생하는 맥동 토크로 이에 의해 기기자체는 물론이고 주변장치에까지 여러 가지 악영향을 미친다. 따라서 맥동 토크를 저감시키는 방법으로 다양한 방안이 국내외 연구자들에 의하여 발표되었고 히스테리시스 제어기의 경우 초핑 제어에 비해 평활한 전류를 흘려줄 수 있다는 장점이 있다는 연구결과가 있다. 그러나 히스테리시스 밴드를 결정함에 있어서 밴드가 너무 작을 경우 많은 스위칭으로 인한 스위칭 손실과 엔코더의 사용 시 불안정한 초기 기동을 야기할 수 있는 둥의 단점을 가지고 있다. 따라서 본 논문에서는 속도오차에 따른 히스테리시스 밴드의 변화를 통하여 보다 안정적이고 빠른 속도응답을 가지면서 정상상태에서 토크 리플을 줄일 수 있는 가변 히스테리시스 제어기에 대하여 연구하였다.

• 자동차안전학회지
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• 제10권2호
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• pp.20-28
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• 2018

Currently, sharp increase of car is on the rise as a serious social problem due to loss of lives from car accident and environmental pollution. There is a study on ITS (Intelligent Transportation System) to seek coping measures. As for the commercialization of ITS, we aim for occupancy of world market through ASV (Advanced Safety Vehicle) related system development and international standardization. However, the domestic environment is very insufficient. Core factor technologies of ITS are Adaptive Cruise Control, Lane Keeping Assist System, Forward Collision Warning System, AEB (Autonomous Emergency Braking) system etc. These technologies are applied to cars to support driving of a driver. AEB system is stop the car automatically based on the result decided by the relative speed and distance with obstacle detected through sensor attached on car rather than depending on the driver. The purpose of AEB system is to measure the distance and speed of car and to prevent accident. Thus, AEB will be a system useful for prevention of accident by decreasing car accident along with the development of automobile technology. This study suggests a scenario to suggest a test evaluation method that accords with domestic environment and active response of international standard regarding the test evaluation method of AEB. Also, by setting the goal with function for distance, it suggests theoretic model according to the result. And the study aims to verify the theoretic evaluation standard per proposed scenario using car which is installed with AEB device through field car driving test on test road. It will be useful to utilize the suggested scenario and theoretical model when conducting AEB test evaluation.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.

• 농업과학연구
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• 제45권2호
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• pp.290-297
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• 2018

Electric drive technology is continually advanced to improve fuel efficiency in the automobile industry. It could improve the fuel efficiency of automobiles by 50% as well as agricultural machinery. The purpose of this study was to measure and analyze the power and current of an electric transplanter based on the planting distances during field operations. The electric transplanter was constructed by mounting the major components of a motor drive system onto a transplanter. The electric transplanter had a 3 kW motor power, and the major components included an inverter, battery, and a battery management system (BMS). The field tests were conducted by travelling at two speeds (300 and 760 mm/s) and by planting at three distances (260, 420 and 630 mm) with the working speed (300 mm/s), during travelling and transplanting. The results showed that the required power increased when the travelling speed was fast. One-way ANOVA for the planting distance and Duncan's multiple range test at a significance level of 0.05 were used to analyze the motor power using statistical analysis software. In addition, the required power increased when the planting distances were short at every working condition. The results of this study would provide useful information for the development an electric transplanter.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3634-3641
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• 2012

본 논문은 로프리스 엘리베이터의 상용화에 앞서 로프리스 엘리베이터 구동제어기의 요구기술과 개발 시의 문제점 및 개선방향을 제시하기 위한 속도제어 연구를 수행하였다. 특히 본 연구에서는 기존 일반적인 PI제어기의 적용 시 문제점의 도출과 부하옵저버를 사용한 개선된 제어기의 방안에 대해서 중점을 두었으며 연구의 구현을 위하여 로프리스 엘리베이터를 소형시스템으로 제작하고 또한 자체 리니어 속도센서를 제작, 본 시스템에 적용하여 속도제어시험을 통하여 제어 성능의 정도와 리니어 속도센서의 적용가능성도 검토하였다. 본 연구의 수행 결과 로프리스 엘리베이터의 실현 가능성을 확인하였으며 구동제어 기술의 만족할 만한 결과를 얻었다. 그러나 향후 상용화를 위해는 속도센서의 분해능, 승차감을 고려한 추력리플의 저감 문제, 정밀 구조물의 제작 및 조립 등 지속적인 개선연구도 요구되었다.