• 대한기계학회논문집A
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• 제24권2호
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• pp.506-517
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• 2000

One dimensional performance model has been used for the design of torque converter. The model is based on the concept of constant mean flow path and constant flow angle. These constant-assumed para meters make the design procedure to be simple. In practice, some parameters are usually replaced with geometric raw data and, the constant experiential correction factors have been used to minimize the design error. These factors have no definite physical meaning and so they cannot be applied confidently to the other design condition. In this study, the detail dynamic model of torque converter is presented to establish the theoretical background of correction factors. To verify the validity of theoretical model, steady state performance test was carried out on the several input speed. The oil temperature effect on the performance is analysed and adjusted. The constant equivalent flow angles are determined at a part of performance region by comparing the theoretical model and the test data. The sensitivity of correction factors to the input speeds are studied and the change of torus flow is presented.

• 대한물리의학회지
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• 제15권2호
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• pp.11-21
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• 2020

PURPOSE: This study examined the effects of posture improvement exercise using virtual reality programs on the posture and balance of patients with forward head postures. METHODS: Thirty men and women in their 20 s, who had a forward head posture, were divided randomly into a group with posture correction exercise and a group with posture correction exercise combined with virtual reality programs. The posture correction exercise was composed of squats, XCO training, and chin-tuck exercise. In contrast, exercise with virtual reality games involved the Hot Squat, Climbey, and Baskhead programs while wearing a headset. Both groups performed the exercises 15 min a day, three times per week, for four weeks. The balance ability, distance between the acromion and earlobe, and neck joint range of motion were assessed before and after the exercises. RESULTS: Both groups showed significant reductions in the distance between the acromion and the earlobe, along with significant improvements in the range of joint motion. The group that performed the virtual reality exercises showed a significant increase in the limit of stability. Both groups showed a significant decrease in the sway length. In contrast, the group given the virtual reality exercises showed a significant reduction in the sway speed while standing with their eyes closed. CONCLUSION: Exercise applying virtual reality programs can be used in clinical and home programs to correct the postures of individuals with a forward head posture because they can trigger interest in inducing active participation.

• 한국생산제조학회지
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• 제24권1호
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• pp.130-134
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• 2015

The automobile industry is ubiquitous and involved in the handling of metal, machines, electricity, electron, and chemistry including the products of many types of processes. In the process of installing engines as a part of the car assembly line, the measurement and correction of the position of the stud bolts consumes a great deal of time. Additionally, defective parts must be manually removed. In the process of engine installation, the speed of the operation, related to the economics of vehicle assembly, is dependent upon measuring the precise position of the stud bolt, reducing the length of correction time, and increasing the working rate. This paper deals with securing the economic feasibility of the manufacturing process, increasing the safety by removing risk factors in the working area, and improving and equalizing the quality by developing an automatic system for the process involving a stud bolt.

• 센서학회지
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• 제31권1호
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• pp.64-68
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• 2022

Herein, we propose a LoRaWAN-based small draft system that can measure the ocean current flow (speed, direction, and distance) in real time at the request of the Coast Guard to develop a device that can promptly find survivors at sea. This system has been implemented and verified in the early stages of rescue after maritime vessel accidents, which are frequent. GPS signals often transmit considerable errors, so correction algorithms using the improved triangulation method algorithm are required to accurately indicate the direction of currents in real time. This paper is structured in the following manner. The introduction section elucidates rescue activities in the case of a maritime accident. Chapter 2 explains the characteristics and main parameters of the GPS surveying technique and LoRaWAN communication, which are related studies. It explains and expands on the critical distance error correction algorithm for GPS signals and its improvement. Chapter 3 discusses the design and analysis of small draft buoys. Chapter 4 presents the testing and validation of the implemented system in both onshore and offshore environments. Finally, Section 5 concludes the study with the expected impact and effects in the future.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.58-65
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• 2005

A method measuring angular speed and estimating angular acceleration of an automotive wind shield wiper pivot with limited resources has been proposed. Limited resources refer to the fact that processes cannot be operated in real-time with a regular notebook running a Microsoft Windows. Also, they refer to the fact that data acquisition cards have only two general purpose counters as many generic cards do. An optical incremental encoder has been employed for measuring angular motion. To measure the angular speed of the pivot, periods for the encoder's output pulses have been measured as the speed is related to the reciprocal of the period. Since only information acquired from one counter channel is the magnitude of the angular speed, sign correction is necessary. Also the information for the exact time when a pivot passes left and right dead points is also missing and the situation is inherent to the hardware setup. To find out the zero-crossing time of the angular speed, a linear interpolation technique has been employed. Lastly, to overcome the imperfection of the mechanical encoders, the angular speed has been curve fitted to a spline. Angular acceleration can be obtained by a differentiation of the angular speed.

• 한국정보통신학회논문지
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• 제18권7호
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• pp.1579-1588
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• 2014

LAN 방식은 국내의 초고속 인터넷 서비스에서 가장 널리 사용되며, UHD TV와 같은 고속의 서비스를 제공하기 위하여 100 메가급에서 1 기가급 이더넷으로 빠르게 전환되고 있다. 1000BASE-T 물리계층은 1 Gbps의 전송속도를 달성하기 위해, 4조의 UTP상에서 각 조당 125 MHz의 PAM-5신호로 데이터를 전송한다. 채널 상에서 발생한 오류를 정정하기 위하여 송신측에서는 컨벌루션 부호와 PAM-5신호를 결합한 TCM을 사용하고, 수신측에서는 비터비 복호기를 사용한다. 본 논문에서는 1000BASE-T의 수신측에서 최소 125 MHz 속도와 최대 2조까지 오류 정정 능력을 제공하는 비터비 디코더를 구현한다. 그리고 구현한 디코더를 논리분석기로 이용해서 동작속도와 오류 정정 능력을 검증한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.757-766
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• 2005

A speed of a train is controlled by Automatic Train Control system and the continuous transmission system provide the speed related information in the Korean High Speed Line. The primary objective of this paper is to measure the level of continuous signal and to calculate the message of that signal. A measuring equipment is introduced and the equipment provide the base line of the level of current and the correction information of the message.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.920-922
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• 2004

This paper presents a speed control system for a linear induction motor(LIM) with cage-type secondary using direct thrust control(DTC). The actual speed of the LIM is detected by the linear scale with the resolution of $100{\mu}m$. Thrust correction coefficient due to the end effect of the LIM is utilized in estimating actual thrust. As a result, responses of the thrust, current, speed, and flux are shown.

• 한국항공운항학회:학술대회논문집
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• 한국항공운항학회 2006년도 추계학술대회 논문집
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• pp.173-176
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• 2006

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.375-378
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• 2003

This paper presents a study on the power factor improvement of the Wind turbine Generation System(WTGS) at Haeng-won wind farm in Jeju Island. Vestas WTGS named V47 as a model system is selected in this paper, and has 660 kW Power ratings. In this system, power factor correction is controlled by the conventional method with power condenor bank. So, model system at Haeng-won wind farm has very low power factor in the area of low wind speed, which is from 4 m/s to 6 m/s. This is caused by the power factor correction using power condenser bank To improve the power factor in the area of low wind speed, we used the static var compensator(SVC) using current controlled PWM power converter by IGBT switching device. finally, to verify the profosed method, the results of computer simulation using Psim program are presented to support the discussion.