• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.143-146
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• 1999

A method to control the speed of DC motor with one-chip microprocessor PIC using PWM is discussed in this paper. This thesis deals with the DC motor speed control for electric bicycles which may be used as an alternative means of transformation in the future. We tried to design a stable system for controlling the speed of DC motor and materialized an electric bicycle loading this system. Now we are on the way to find out the problems this system has and work out the solutions.

• Journal of Information Processing Systems
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• 제19권2호
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• pp.219-231
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• 2023

Intelligent applications are crucial for increasing the popularity of shared urban electric bicycles (EBs). Building an application platform architectural system that can satisfy independent user operations is critical for increasing the intelligent usage of shared EBs. Consequently, we collected online reviews of shared EB applications, conducted semantic processing and sentiment analysis, and refined the positive and negative review data for each function. The positive and negative review indices of each function were calculated using the formulae for positive and negative review indices of product functions, thereby determining the functions that need to be improved. Each function of the Shared EB application was improved according to its business process. The main contributions of this study are to build a user requirement architecture system for the Shared EB application with five dimensions and 22 functions using the Delphi method to design the user interface (UI) of this application based on user satisfaction evaluation results; to create a high-fidelity dynamic interaction prototype and compare user satisfaction before and after improving the Shared EB application functions. The testing results indicate that the changes in the UI significantly improve the user experience satisfaction of the urban Shared EB application, with the positive experience index increasing by 69.21% and the negative experience index decreasing by 75.85% overall. This information can be directly used by relevant companies to improve the functions of the Shared EB application.

• 한국정보기술학회 영문논문지
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• 제10권1호
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• pp.85-97
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• 2020

As a solution to the rapid urbanization problem, interest in and use of personal mobility devices such as bicycles and electric kickboards are increasing, and accidents are also rising every year. In this study, a smart vest to prevent traffic accidents and promote safe driving of personal mobility users was designed and implemented. Unlike the existing products on the market that indicate directions using buttons, the smart vest designed and implemented in this study indicates the moving direction by shaking a bracelet and displays the direction by LEDs on the vest. Therefore, this product was designed and implemented to be safer and differentiated from other existing products.

• 한국ITS학회 논문지
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• 제13권1호
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• pp.75-85
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• 2014

기존 카쉐어링 시스템은 원웨이 트립 수요에 대한 대응과 타 쉐어링 시스템과의 연계가 어려운 문제점이 있다. 이에 본 연구에서는 원웨이와 라운드웨이 트립에 대응이 가능하며, 자동차(전기/가솔린), 전기오토바이, 자전거 등의 다양한 교통수단을 공유할 수 있는 멀티모빌리티 쉐어링 서비스 메니지먼트 시스템을 개발하여 일본 치바현 카시와시 카시와노하지역과 나가레야마시에 모의실험을 실시하였다. 모의실험 결과, 이 시스템을 통해 전체 자동차 트립 중 54.9%의 원웨이 트립 수요가 충족되었으며, 전체 이용자 중 43.9%가 공통 인터페이스를 통해 복수의 교통수단을 이용한 것이 확인되었다. 또한, 차량의 공동이용과 친환경 차량 이용을 통해 이산화탄소 배출량도 삭감에도 공헌하였다. 개발된 쉐어링 시스템은 기존 카쉐어링 시스템 보다 다양한 교통수요에 대응하면서 이동성을 향상 시킬 것으로 기대된다.

• 한국정밀공학회지
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• 제32권2호
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• pp.149-157
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• 2015

Ball and roller bearings are commonly used machine elements for supporting rotating motion about shafts in simple devices including bicycles, in-line skates, and electric motors, as well as in complex machines. Heat is generated by the friction in the bearings, which causes the temperature inside the bearing to increase. If the heat is not appropriately removed from the bearing, elevated temperatures may give rise to premature failure. It is, therefore, important to be able to calculate the temperature in the bearings due to friction.Here, we describe a method to estimate the frictional torque in bearings using an empirical formula developed using a method based on bearing analysis tool and the measured frictional torque in a spindle system. Thermal analysis of the spindle system including the bearings was achieved using the finite element method (FEM), and the bearing temperature was compared with measured data to verify the empirical formula.

• 산업기술연구
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• 제40권1호
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• pp.13-18
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• 2020

Lithium-ion batteries have a small volume, light weight and high energy density, maximizing the utilization of mobile devices. It is widely used for various purposes such as electric bicycles and scooters (e-Mobility), mass energy storage (ESS), and electric and hybrid vehicles. To date, lithium-ion batteries have grown to focus on increasing energy density and reducing production costs in line with the required capacity. However, the research and development level of lithium-ion batteries seems to have reached the limit in terms of energy density. In addition, the charging time is an important factor for using lithium-ion batteries. Therefore, it was urgent to develop a high-speed charger to shorten the charging time. In this thesis, a discharger was fabricated to evaluate the capacity and characteristics of Li-ion battery pack which can be used for e-mobility. To achieve this, a smart discharger is designed with a combination of active load, current sensor, and temperature sensor. To carry out this thesis, an active load switching using sensor control circuit, signal processing circuit, and FET was designed and manufactured as hardware with the characteristics of active discharger. And as software for controlling the hardware of the active discharger, a Raspberry Pi control device and a touch screen program were designed. The developed discharger is designed to change the 600W capacity battery in the form of active load.

• 한국전자통신학회논문지
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• 제18권4호
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• pp.723-730
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• 2023

본 논문에서는 Personal Mobility에 사용되는 스마트헬멧의 안전성 보강을 제안한다. 주요 내용은 헬멧이 안전 신호를 보낼 수 있도록 아두이노를 베이스로 사용하여 초음파 센서를 활용한 거리별, 각도별 변화에 따라 센서의 값을 설정하여 오차를 최소화하여 원활한 인식이 되도록 하였다. 또한, 자이로센서를 활용하여 각 기울기에 따른 방향지시등이 점등되도록 하였다. CDS 센서를 이용하여 야간에 150 lux 이하로 내려갈 시 LED가 점등되도록 설계하였다. 최종적으로 5cm 이내에서 헬멧 착용 여부를 확인할 수 있으며, 평균속도 주행 시 10도에서 방향지시등이 점등되며, 150lux 이하에서 LED가 점등됨을 확인하였다.

• 한국빅데이터학회지
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• 제8권2호
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• pp.233-248
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• 2023

스마트시티의 미래를 구축하는 과정에서, 모빌리티와 도로 인프라의 혁신은 중요한 주제 중 하나이다. 특히 오늘날 자율주행 자동차의 보급과 전기자전거, 전동킥보드, 전동휠 등 도로에 등장하는 모빌리티의 종류가 다양해짐에 따라 도로는 기존의 자동차와 보행자를 비롯해 수용해야 할 주체들이 다양해졌으며 각 모빌리티 간의 상충 또한 해결해야 할 문제이다. 완전도로(Complete Street)는 2003년 미국에서 등장한 용어로 보행자, 자전거 이용자, 대중교통 이용자, PM(Personal Mobility) 이용자, 자동차 운전자 등 모든 도로 이용자의 공평한 안전과 편의를 고려한 도로 설계와 운영을 의미한다. 현재 해외 여러 도시에서 완전도로를 구현하고 있으며, 이를 제도화하기 위한 연구도 활발히 진행되고 있다. 그러나 국내에서는 완전도로에 대한 연구와 논의가 부족한 실정이다. 따라서 본 연구는 델파이 (Delphi)기법을 통해 학계 및 실무 전문가들의 의견을 수집 및 분석하여 완전도로 설계에서 고려해야 할 주요 요인들을 정형화하고자 한다. 총 세 차례의 델파이 설문이 진행되며 1차 개방형 설문을 통해 전문가들의 자유로운 답변을 수집하고 이를 키워드 위주로 정리하여 2·3차 폐쇄형 설문을 작성하였다. 2·3차 설문은 총 52개의 문항으로 구성되었으며 설문 결과 52개의 문항 중 34개의 항목이 최종 요인으로 채택되었다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1324-1335
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• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.

• 한국염색가공학회지
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• 제34권2호
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• pp.109-116
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• 2022

Tire codes are made of materials such as hemp, cotton, rayon, nylon, steel, polyester, glass, and aramid are fiber reinforcement materials that go inside rubber to increase durability, driveability, and stability of vehicle tires. The reinforcement of the tire cord may construct a composite material using tires such as automobiles, trucks, aircraft, bicycles, and fibrous materials such as electric belts and hoses as reinforcement materials. Therefore, it is essential to ensure that the adhesive force between the rubber and the reinforced fiber exhibits the desired physical properties in the rubber composite material made of a rubber matrix with reinforced fibers. This study is a study on the heat treatment conditions for improving the adhesion strength of the tire cord and the reinforced fiber for tires. The core technology of the drying process is a uniform drying technology, which has a great influence on the quality of the reinforcement. Therefore, the uniform airflow distribution is determined by the geometry and operating conditions of the dryer. Therefore, this study carried out a numerical analysis of the shape of a drying nozzle for improving the performance of hot air drying in a dryer used for drying the coated reinforced fibers. In addition, the flow characteristics were examined through numerical analysis of the study on the change in the shape of the chamber affecting drying.