• 대한인간공학회:학술대회논문집
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• 대한인간공학회 2004년도 추계학술대회
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• pp.54-54
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• 2004

• 한국소음진동공학회논문집
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• 제19권10호
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• pp.996-1002
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• 2009

Elimination of squeal noise occurred during brake application is an important task for the improvement of comforts in an industrial forklift. In this paper, a test rig was developed which was possible for testing of brake noise and an experimental measurement on squeal noise was performed. The causes of the brake noise are identified by experimenting how the factors such as automatic transmission fluid and rpm of drive axle affect the squeal. In order to identify the squeal characteristics, the signal analyses for noise are performed by using frequency spectrums. Also, brake test using a forklift was carried out to confirm the reliability of test results by using a test rig comparing with the occurrence of squeal noise. Experimental results showed that the tendencies of occurrence of squeal noise are well agreed at two test methods by using the test rig and forklift.

• 한국안전학회지
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• 제20권1호
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• pp.133-136
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• 2005

The accidents attributed to the forklift have increased as the number of the forklift increases. It is significant that most of the accidents were fatal. This study investigated slip distance of forklift depending upon the floor materials and their conditions in industrial site. For doing this, an experiment was conducted, in which the floor materials and their conditions were adopted as independent variables and the slip distance as dependent variable. Six floor materials included asphalt concrete, two color hardener mortar, epoxy paint and deluxe tile. Two types of floor conditions, wet and dry, were used in the experiment. The results showed that the slip distance was shorter on the asphalt and concrete floors than on other floors, and that the distance on the wet floor was six times longer than that on the dry condition. Based on this result, it is recommended that as in the advanced countries, the regulation or standard on the floor conditions such as friction coefficient be established for reducing forklift relevant accidents.

• 한국생산제조학회지
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• 제18권6호
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• pp.565-575
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• 2009

A forklift (also called a lift truck) is a powered industrial truck that is used to lift and transport materials. It has become an indispensable piece of equipment in manufacturing and warehousing operations. The modem forklift is equipped with automatic transmission to meet the requirement of loading and easy operation of the vehicle. This paper proposes the design of TECU(Transmission Electronic Control Unit) which is applied to PSD322-Axle transmission. Garofalo's control technique is generally used to the automatic transmission. We consider the work quality and market requirement that does not want to control engine throttle. This paper proposes new controller system which guarantees efficient speed changes with simple system. This new system does not control the engine throttle spontaneously. But it has the load of engine and vehicle as a maximum disturbance. The scope of the disturbance is limited to the stoll area of the torque converter. This paper proposes a ideal control commander that converges relative velocity of the input and ouput of a clutch into a zero. We design linear controller to execute the idea control commander. We applied the control algorithm to the forklift of PSD322-Axle type and the performance of this controller was verified.

• 한국기계가공학회지
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• 제20권4호
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• pp.57-65
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• 2021

This paper explains a DMFC-Lithium Battery hybrid system applied to a forklift. A conventional Lead Acid battery forklift has several problems: long charging times, short operation times, and frequent battery replacements. As a result, hydrogen-powered forklifts are replacing Lead acid battery-powered forklifts due to their shorter refueling time and longer operation times. However, in doing so, we are confronted with the problem of a high hydrogen refueling infrastructure. A Direct Methanol Fuel Cell (DMFC), on the other hand, is an eco-friendly generator that directly converts the chemical energy of methanol into electricity. In general, DMFC is regarded as a small power generator under kW power. In this paper, a DMFC-Battery hybrid system is applied to a 1.5 ton forklift by increasing the power output of the DMFC stack and utilizing the high charge-discharge characteristics of a lithium battery.

• 드라이브 ㆍ 컨트롤
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• 제18권2호
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• pp.46-55
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• 2021

A forklift is a powered industrial vehicle used to lift and move materials over short distances. Nowadays, almost all forklifts are equipped with an automatic transmission due to its improved operator comfort and increased productivity. Thanks to marked improvement of transmission control unit equipped with highly-advanced microcontrollers, recently developed automatic transmission for forklift have various auxiliary functions such as creep, auto retardation, and automatic shift with excellent shift quality. This paper deals with the creep function which enables one to maneuver a forklift at the designated low speed by slip control of clutches. The design of creep function was based on four modes of creep operation depending on the status of the operator's shift lever and accelerator pedal. Control algorithms and control parameters for each mode were designed to achieve the desired static and dynamic performance. Vehicle test for the designed creep function was carried out with an independently developed embedded controller. Test results confirmed good creep speed control without speed error at a steady state with a mild shift shock during mode changes by stepping or releasing the accelerator.

• 드라이브 ㆍ 컨트롤
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• 제20권2호
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• pp.24-30
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• 2023

This study aimed to analyze the fatigue of forklifts in industrial settings by assessing their stress levels during operation. Strain gauges were affixed to the dynamic components of the forklifts to gather real-time data and enhance the reliability of the analysis. Although monitoring structural loads in harsh testing environments can be challenging, the affixed strain gauges on the dynamic components can provide more precise results and improve the interpretation of data. By creating testing modes that simulate forklift usage environments and performing experiments with selected cargo and driving modes, a comparison of the damage severity of forklift parts under different driving conditions was done. These results can be utilized to forecast the lifespan of forklift parts under extreme driving conditions and assist in the design and optimization of new parts in the future.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.17-26
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• 2023

A forklift is an industrial vehicle that lifts or transports heavy objects using a hydraulically operated fork, and is equipped with an automatic transmission for the convenience of repetitive transportation, loading, and unloading work. The Transmission Control Unit (TCU) is a key component in charge of the shift control function of an automatic transmission. It consists of an electric circuit with an input/output signal interface function and firmware running on a microcontroller. To develop TCU firmware, the development process of shifting algorithm design, firmware programming, verification test, and performance improvement must be repeated. A simulator is a device that simulates a mechanical system having dynamic characteristics in real time and simulates various sensor signals installed in the system. The embedded transmission simulator is a simulator that is embedded in the TCU firmware. information related to the mechanical system that is necessary for TCU normal operation. In this study, an embedded transmission simulator applied to the originally developed forklift TCU firmware was designed and used to verify various forklift shift control algorithms.

• 대한안전경영과학회지
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• 제8권2호
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• pp.39-49
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• 2006

Forklift achieves transportation of freight and continues loading and unloading work repeatedly long for hours in industry spot. Therefore, drivers feel tired make a mistake for wrong operation of vehicle caused by continuous work. These components are resulted in CTDs, some industrial accident. That is the forklift need to ergonomics access. So, in this paper, requirements of forklift user were abstracted using questionnaire, produced important design factor for pedal and lever using QFD(Quality Function Deployment), and then suggested ergonomic considerations for industrial accident prevention.

• 한국소음진동공학회논문집
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• 제24권2호
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• pp.102-107
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• 2014

The engine excitation forces are considered as major vibration source for the forklift truck, especially in small class. Even though the current engine mounting system designs are acceptable for vibration isolation, the performance of the engine mounting system is still required for the tendency of light weight, higher power and driver's higher vibration requirement. In this paper vibration reduction technique of forklift engine which is supported on rubber mounts is presented. Based on the dynamic model of resilient engine mounting system, design evaluation program is established. The design optimization technique and evaluation method of system properties are discussed. Effects of optimal design are validated through comparison with test results.