• Journal of Power Electronics
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• 제12권1호
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• pp.113-119
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• 2012

This paper describes the design and control of a phase shift full bridge converter with a current doubler, which can be used for the on-board charger for the lead-acid battery of electric forklifts. Unlike the common resistance load, the battery has a large capacitance element and it absorbs the entire converter output ripple current, thereby shortening the battery life and degrading the system efficiency. In this paper a phase shift full bridge converter with a current doubler has been adopted to decrease the output ripple current and the transformer rating of the charger. The charge controller is designed by using the small signal model of the converter, taking into consideration the internal impedance of the battery. The stability and performance of the battery charger is then verified by constant current (CC) and constant voltage (CV) charge experiments using a lead-acid battery bank for an electric forklift.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.371-376
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• 2003

In general, the electronic forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by speed control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the electronic forklift is demanded the robust drive mode. Some cases of the mode, there are trouble in torque and speed control following slope capacity. The control is sensitive concerning with slope angle and output speed, various control method is studied for stability of speed control. We apply speed controller for the self-tuning using DSP(TMS320F240) as main controller for high speed processor, embody dynamic characteristic of control compared the PI control to the fuzzy control.

• 대한산업공학회지
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• 제39권1호
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• pp.55-60
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• 2013

VNA(Very Narrow Aisle) forklift trucks require narrower aisle width than traditional counter-balanced trucks do because only the fork assembly turns in the aisle instead of the entire body of the truck. Substituting the VNA trucks for the existing counter-balanced trucks will result in the significant increase of revenue due to the increased storage capacity in the distribution centers. In this study, we present an economic analysis model for the substitution, in which we present a closed-form equation for the number of racks to stay unmoved, while maximizing the additional storage capacity; and resulting payback period of the substitution. A case study shows the payback period of only 8.1 months, indicating that this substitution is very profitable.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1487-1492
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• 2000

To identify forklift's booming noise in cabin under idling engine revolution, we discussed and applied conditioned input analysis. Acceleration signals at engine mounts and front window and rear window were considered as candidate input signals and output signal was sound pressure signal at driver's ear position in cabin. To reduce the numbers of the input signals, one idea were applied; Each one input signal from each input groups was selected, respectively because input signals in the same group were highly correlated. And Hilbert transform was used to determine the ordering of three selected inputs. Partial coherence functions, multiple coherence function and conditioned spectral density functions were investigate to the effects of booming noise by partial inputs.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.80-86
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• 2008

In this study. the noise sources were identified and the noise and vibration were reduced for an industrial forklift. To identify the noise sourses, noise signals were measured by a microphone on a driver seat and these signals were analyzed with a waterfall plot. For this purpose, the gear mesh frequencies from the gear box of a reducer were not only investigated but noise/vibration sourses of an electric motor were also examined. Furthermore, the frequency response functions were obtained to confirm the vibration and noise sourses. It was found that severe vibration and noise were generated in the casing and the connecting part of the reducer. The severe vibration and noise could be reduced by a structure modification.

• 전력전자학회논문지
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• 제27권2호
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• pp.150-156
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• 2022

This study proposes a design method of fuel cell DC/DC converter using in 5-ton forklift. For efficient hydrogen usage, targeted fuel cell system recirculates discarded hydrogen after fuel cell reaction. Recirculating hydrogen contains much impurities that reduces output power, increasing pressure that can damage the internal fuel cell reaction system. The proposed DC/DC converter effectively converts fuel cell power considering the voltage drop rate to reflect the recirculating hydrogen. Then, frequency control method is used to regulate the current ripple amount for battery and fuel cell hybrid configuration. Proposed power converter system design and control methods are verified in a practical fuel cell system that implements recirculating hydrogen.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.665-666
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• 2014

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 2004년도 추계학술대회
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• pp.10-10
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• 2004

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.229-231
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• 2018

자율주행 차량 기술이 점차 발전해 오면서 점차 산업 현장 및 사고 현장과 같이 인명하고가 많이 일어나는 분야에 자율주행 시스템을 도입한 로봇으로 대처를 많이 해 오고 있다. 이러한 이유로 자율주행시스템을 탑재한 무인이송장치는 사람의 접근이 어려운 유해환경 등에 많이 이용된다. 또한 자율주행 시스템의 도입은 산업현장과 같이 정신없이 움직이는 환경 속에서 일어나는 충돌 사고 및 인명피해를 줄이고, 효율성 있는 업무처리를 도와준다. 또한 자율주행 차량끼리 매인서버로 차량별 주변 환경을 전송하여 매인서버에서 이를 통재하면 더욱 넓은 지역에서 보다 안전하고 신속한 업무처리가 가능하다. 본 논문에서는 자율주행이 가능한 무인지게차 시스템에 대한 V2X 통신을 활용함으로써, 보다 넓은 지역의 지게차들을 통재하여 산업 업무량을 높이며, 인명피해와 재산피해를 줄일 수 있다.

• 동력기계공학회지
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• 제16권5호
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• pp.70-75
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• 2012

In mechanical industries, forging is one of the basic process. But comparing the other developed industries, forging industries can not reach at the level of that development. In forging industries, the quality of the products totally depends on the skills of workers and also the precision of the equipments. Particularly because the open die forging industry is unable to deviate from the past method of production and all works are manually progressed, the operator is always exposed to the danger. In the regard some additional device has been made especially. Thus, in this research, by using the forklift as the means for the manipulation of the development object system, it tries to be comprised the process automation. After than it is fitted with the forklift for safe and easy handling of jobs and products during open die forging process. First of all, development system mold has been assembled to the system, after than it is assembled with forklift. This development system has been applied for handling of large scale products more than 300kg, and the satisfactory result with uniform quality of the products have been achieved due to this mechanical setup.