• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.70-77
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• 2010

This paper presents the current and speed controller design procedure and their performance for the IPMSM based next generation high speed railway traction system. The next generation high speed railway system is a power distributed type and uses vector control method for a motor speed control. Since the speed and current controller gains of the vector control system directly affects to the transient characteristics and speed control capability, the systematic design of the controllers are required. In this paper the controllers are designed using the IPMSM based next generation high speed railway system parameters. Simulation programs based on Matlab/Simulink is developed. Finally the controller characteristics are analyzed by the simulation results.

• Journal of Drive and Control
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• v.20 no.1
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• pp.16-26
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• 2023

Although the upland field area of Korea is high as 44.8%, the platform optimized for the upland field is insufficient. It is necessary to develop an optimized platform for the upland field because the upland field environment is an irregular environment with many slopes. In addition, due to the characteristic of agricultural operations, the traction power and torque of the platform have to be sufficient. Therefore, in this study, a simulation model that can predict the traction power and driving torque of a crawler-type platform for the upland field was developed and validated using the specifications of the crawler platform. The simulation model was developed using Amesim (19.1, Siemens, Germany). The development of the model was conducted using the specifications of the platform. A measurement system was developed to validate the simulation model. The traction power data of the simulation model was validated with the traction force and vehicle speed. The driving torque data of the simulation model was validated with the torque of the sprocket on the crawler system. As a result of the analysis, the error between measurement and simulation results occurred within 10%, and it was determined that the traction power and driving torque prediction of the crawler platform using this model was possible.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.257-265
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• 2016

In this study, an optimal design for motor-driven track type traveling system applied into high clearance working machineries in orchard is proposed. Tractive performance and hill climbing ability were predicted and evaluated for the optimal motor traveling system by taking into account of soil characteristics in orchard utilizing the high clearance working machineries. Design criteria for tractive performance were based on the traction force calculated from tractive effort subtracted by motion resistance, while hill climbing ability had its design criteria that fulfill the climbing 20% slope ground at a speed of 3km/h. Based on the evaluation results of traction and climbing ability, two DC48V, 4500rpm, 1.6kW AC motors were independently applied to both left and right side of orbits; each motor is designed to transmit power on driving sprocket of track type traveling system via 50:1 reduction gear ratio. The motor-driven track type traveling system developed in the study found to have 396 kgf of tractive force, which is 12.5% higher than climbing resistance at orchard soil having 20% slope ground (352 kgf), demonstrating sufficient tractive performance and hill climbing ability.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.218-225
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• 1995

In this paper, a mechanical analysis model for steep-slope log-skidding operations of a rubber-tired tractor is discussed and the applicability of the model is investigated. The model largely consists of mathematical analysis models for log drag, dynamic vehicle weight distributions and soil-vehicle traction. For the case study, a theoretical data set for log skidding operations is used in investigating the effect of the factors influencing the results of mechanical analysis or the productivity of skidding operations. The analyses include 1) the effect of log choking methods on tangential log-skidding force, 2) the effects of the change in travel speed and log load on the required input power to the wheels and 3) the log skidding performance of a two-wheel drive compared with that of a four-wheel drive.

• KDI Journal of Economic Policy
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• v.22 no.1_2
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• pp.285-362
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• 2000

남북 정상회담 이후 남북경협 활성화에 대한 기대가 높아지면서 기업의 대북진출에 대한 관심도 크게 증가하고 있다. 우리 기업들이 대북투자에 대하여 커다란 관심을 가지는 이유로는 시장선점, 북한의 낮은 임금 이용, 국내의 유휴설비 이용 등 여러 가지가 있으나 그중 가장 직접적인 요인은 북한의 낮은 임금을 이용하고자 하는 것이라 할 수 있다. 그러나 대북투자의 주요 목적이 북한의 저임 노동력의 활용에 있음에도 불구하고 북한의 임금수준이 얼마나 낮은 것이며, 노동력의 수준은 어떠한지, 또한 이런 상황에서 대북진출시 북한 노동력을 어떻게 활용해야 할 것인지에 대해서는 충분한 검토가 이루어져 있지 않다. 따라서 본 연구에서는 북한 노동력의 임금 및 질적 수준을 분석하고 구체적인 사례에 대하여 살펴본 후 대북진출시 노동력 활용방안에 대하여 검토한다. 우선 북한의 임금수준은 이론적 측면, 동남아 국가 등 경재국과의 비교, 기업의 견해 등을 통해서 살펴볼 때 저렴한 것으로 보기는 어렵다. 질적 수준의 경우에도 일반적으로는 북한 노동력은 우수한 것이라고 인식되고 있으나, 교육수준, 작업규율, 노동생산성 등의 측면에서 분석한 결과 우수한 것으로 판단하기는 곤란하다. 실제 사례에 있어서도 많은 문제를 보이고 있는바, 북한 정책의 문제점, 계약 및 규정에 문제점, 기능 및 교육훈련의 문제점, 근로관습 및 의식의 문제점 등으로 나누어 볼 수 있다. 이러한 상황에서 대북진출은 기대한 만큼의 수익을 거두기가 힘들 것으로 예상된다. 그러나 현재 여건이 어렵다고 무작정 대북진출을 지연할 수도 없고, 기업의 입장에서는 선점 등의 목적으로 현 단계에서 투자를 실행하려고 할 수도 있을 것이다. 또한 일부 분야의 경우에는 이익의 창출이 가능한 사업도 있을 것이다. 본 연구에서는 대북진출에 대비해서 효율적인 북한 노동력 활용방안을 질적 수준 향상방안과 임금관리 방안으로 나누어 살펴보고 있다.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.660-664
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• 2007

Korea High-speed Railway (HSR-350x) was developed by Korean government, several institutes, and related companies. HSR-350x was investigated its performance and tested at the high speed line. In 2004 December, HSR-350x was run over 350km/h and proved its running performance. And Korean Train Express (KTX) served the commercial traffic for 4 years. These high speed railways have 12 motors to transfer the traction effort or the braking force. To obtain the load of the transfer shaft, it is necessary to measure the transferred torque of the shaft. In this paper, authors propose the construction the measurement system fur monitoring the force transferred to the train from the motor The system was installed to the tripod shaft which is located between the reduction gears and it measures the mechanical load directly.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.390-394
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• 2004

우리나라를 세계 최고의 IT강국으로 만든 초고속인터넷과 이동통신은 급속한 성장기를 거쳐 이제는 완만한 성숙기에 접어들고 있다. 이와 같은 상황에서 새로운 IT 성장동력을 견인하고 IT 선도국으로서 입지를 강화하기 위해 IT839 전략의 일환으로 통신사업자, 장비제조사, 정부 주도로 휴대인터넷 서비스의 조기 도입을 적극 추진하고 있다. 본 연구에서는 휴대인터넷서비스의 중요한 핵심요소로 인식되고 있는 단말기의 최근 동향, 예상되는 형상, 성공요인 등에 대해 검토하고 바람직한 추진방향을 제시해 보았다.

• Venture DIGEST
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• s.58
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• pp.18-19
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• 2004

불경기라 다들 한숨이 깊다. 하지만 불경기를 재도약의 발판으로 삼으려는 우리 벤처기업들에게는 이 위기 역시 기회일 수 있다. 무한한 잠재력을 가진 벤처, 대한민국 고용창출의 견인차이자 경제 성장동력의 핵심인 우리 벤처기업의 능력을 다시 한번 보여줄 때가 온 것이다. 이에 이번 호부터 총 5회에 걸쳐 벤처재도약을 주제로 벤처기업인들의 릴레이원고를 기획한다. 벤처재도약을 향한 릴레이 기고문 그 첫 번째, 휴맥스 변대규 대표의‘글로벌 챔피언십 육성방안’에 대한 생각을 들어보자.

• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.33-48
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• 1977

Transporting agricultural products and the other material by the two-wheel-tractor (power-tiler)and trailer system may be one of its most widely used farming functions.The safety and hitching load for all the previaling performing conditions may be the general concern over the operation of the tiller-trailer system. In this study, a mathematical model to determine the static and dynamic forces excerting on the hitch point were developed . Based on the analysis of the model and the field measurements. the limiting hitching load and critical slope were analyzed. The results of the study are summarized as follows ; 1) The limit angle of slope land for the safety steering that two-wheel tractor-single axle trailer system was able to transport agricultural products was the direct angle (${\gamma}$) = 8 ; the cross angle$\beta$) 15 ; and it was decreased in accordance with the increase of carrying load ($W_4). 2) The critical velocity for safe operation in case of running on downward hill road was about 1.08m/sec. 3) The limiting carrying load for the safe steering was W$_4$=600kg. The degree of the safe steering for different braking methods was given in order as follows ; Simulataneous braking the tractor and trailer , braking the trailer only, and braking tractor only. 4) Among the three components of impact loads excerting on the hitch point, the component in the lateral direction ($P_{Vy}$) was near zero in spite of increase of hitching load ($W_4) , while the components in the other two mutually perpedicular directions ($P_{Vx}$ and ($P_{Vz}$) ) had larger values in horizontal plane than those in the slope lands. 5) Moment of forces on the lateral direction (M$y$) had the largest value among the three components of impact moment acting on the hitch point, however all the components were sharply increased in accordance with the increase of hitching loads ($W_4. Three components of the moment were the negative values.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.95-101
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• 1986

A computer-controlled automatic vibratory tillage test equipment which attained minimum draft and power was developed. Three control program modes were developed and tested with this equipment. A computer simulation investigated the control performances of the above modes with the following primary results. 1) All of the three control modes converged to the same steady state when the velocity ratio was kept constant. 2) The control mode in which the blade frequency was twice of the soil shearing frequency (frequency control mode) showed optimum control with minimum draft and power, and also had greatest velocity convergence. 3) Results of the simulations showed the frequency control mode to have achieved the best control performance. The fluctuation of the draft reduction was less than 10% at various cutting depths and soil moistures.