• Journal of the Korean Society for Precision Engineering
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• v.3 no.4
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• pp.10-19
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• 1986

산업기술의 일반적 추이: 최근 우리경제가 잘되고 있다고는 하나 기술수준면에서 볼때 세계수준에 도전하기에는 아직도 취약점을 지니고 있다. 이번 상공부가 실시한 산업기술수요조사는 지금 우리의 기술수준이 정확히 어디에 왔으며 낙후된 기술을 향상시키기 위해 어떤 과제들이 해결되어야 하는가에 대한 현실적인 방안을 제시했다는 데서 그 의의를 찾 을 수 있었다. 상공부는 공업발전법 시행에 따라 생산현장에 필요로 하는 기술개발을 전담하고 지난 2월부터 7개월에 걸 쳐 산업기술수요조사를 실시하였으며 여기에는 모두 818명의 품목별 전문가(생산업계와 학계)가 참여하여 1,500 개 업체를 대상으로 끝을 맺었다. 그 결과에서 밝혀졌듯이 제조,가공이나 조립, 기타 작업원의 기능에 주로 의존하는 기술은 선진국 수준을 거의 쫓아가고 있으나 제품의 품질향상과 직결되는 금형제작, 자동화, 고도정밀가공 및 측정기술등에서는 상당한 격차를 보여주고 있다. 이에따라 기술의 경제성장에 대한 기여도도 미국. 일본등에 비해 크게 낮은 실정이며 우리의 경우, 지난 63-82년 기간동안 기술진보가 경제성장에 기여한 비중이 11.8%에 그친데 비해 미국은 29.8%, 일본은 22%로나타나 그 만큼 전반적인 기술수준이 낙후되어 있음을 반증해 주고 있다.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.73-79
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• 2001

The purpose of this investigation is experimentally to clarify the machinability and tool wear of STS 304 steel pipe material for piping. In order to determine the effects of cutting parameters and tool wear on thrust, torque, AE RMS, drilling is conducted on CNC milling machine. In this experiment, it is measured that thrust, torque, tool wear length, tool wear area and AE RMS during drilling using Hss tool. It has been found that a) During the drilling, the thrust and the torque of the STS 304 pipe are received more the effect of the feed than the spindle speed and the thrust increase with the increase of feed, b) The value of the AE RMS is been larger the effect of the cutting speed than the feed rate, and the value of the AE RMS increase with the increase of spindle speed, c) It has been found that the suitable feed in feed condition of 0.03, 0.05, 0.1, 0.15mm/rev is below 0.05mm/rev, d) The value of the AE RMS was shown a characteristic of the jump value during it was a sudden inrcrease of the tool wear. The increased character of the AE RMS value can be known an effective factor of the tool wear detection, and e) It can be quantitatively evaluated the condition of the tool according to calculate a area of the drill wear image which is obtained by a vision system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.98-103
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• 2015

Swing reducers are widely used in special vehicles that have swing motions. Generally, compact swing reducers were constituted by a worm gear pair. Worm gears are one of the most important technical devices for transmitting torque between spatially crossed axes. Due to their high transmission ratio and compact structure, they are widely used in power transmission applications where high reduction is required. This paper presented approaches to improve the transmission efficiency and assembling performance of 3.5 ton class worm gear swing reducers. Worm wheel and the case of swing reducers were optimized and certified by a finite element method. Finally, an actual swing reducer was processed and assembled to test the performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.28-35
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• 2016

Forging operations are non-stationary processes occurring because of indirect pressure, generally, under conditions of three-dimensional stress and deformation. Furthermore, due to friction and the constraints of die geometry, deformation is not homogeneous. Material flow and deformation are largely determined by the shape of the tools. It is well known that net-shape forging can improve the mechanical strength of the final product as well as reduce material waste. Oxygen-free copper that is used for electrical and electronic components has excellent electrical and thermal conductivity. Oxygen-free copper parts have a low productivity in cutting process. Thus, the forging process is performed in order to improve the low productivity in cutting process. The forging of oxygen-free copper for electrode body parts was modeled using finite element simulation and forging experiments that were conducted for producing electrode body parts at room temperature. In order to reduce the cost of cutting products, the forging was performed in a closed cavity to obtain near-net or net-shape parts.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.122-128
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• 2016

The purpose of this study was to develop improved strength of an arm and a boom on over-load environment, which causes damage in the initial design statement. To develop improved strength of an excavator front group, we calculated load conditions using the MATLAB program, and using these conditions, we performed a structural analysis of an excavator front group for the maximum digging force condition. Finally we performed a topology optimization to reduce weights of an arm and a boom, and we re-modeled an arm and a boom based on the topology design results and re-performed the structural analysis. The strength of the re-design is higher than the initial design but its weight is almost the same as the initial design.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.647-654
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• 1985

A computer aided design package is developed that can perform such functions as computer aided inputing/drafting/modifying/outputing, automatic determination of volumetric properties, finite element analysis and post processing for the design of axisymmetric shell with slight asymmetry. In order to make the design modification easy and to accelerate the computation time for analysis, developed is a new finite element analysis which utilizes an approximate solution method and a conical ring eleement with slight asymmetry. Also proposed is a computer aided process planning algorithm which is based on the axiomatic approach.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.38-45
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• 2017

A finite element analysis-based approach which investigates the causes of the breakdown in the outer ring of the choke at hot rod rolling mill is presented. Two-dimensional drawings of the whole vertical-type mill stand are transformed into three-dimensional CAD models. Non-linear elasto-plastic deformation analysis of material at the roll gap is performed for computing roll force and torque of the work roll. Then, the reaction forces of the bearing rings together with a set of roller bearings that support the work roll are obtained by means of rigid body motion analysis. Finally, stress behaviors in the bearing rings together with a set of roller bearings that support the work roll are investigated by linear elastic analysis. Results reveal that stress at the contact area between the outer ring and roller bearing is extraordinary high when an internal gap between an external surface of the outer ring and the internal surface of the chock due to wear of the inside of the chock occurs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.80-87
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• 2021

Our study introduces an improved modular agricultural platform to provide convenience to agricultural workers. We upgrade the platform design in three parts, namely, by adding a 458 pattern tire, electricity control, and four-wheel steering function, to improve the platform performance. Results showed that the upgrades enhanced the platform performance and reduced its overall weight as compared with the existing platform. To demonstrate the performance of our improved platform, we conducted five types of experiments with respect to the climbing angle, variable width, attitude control, speed, and obstacle passing.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.69-76
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• 1995

This paper describes characteristics of EDT(Electro Discharge Texturing) and that the strip surface has influence on the paintability. The pulse mode and the capacitor mode of recently developed EDT method were investigated about the peak shape and the roughness of strip surface. And EDT method compared the above-mentioned contents with the SBT(Shot Blast Texturing) method. The peak count of the pulse mode is more than that of the capacitor mode. But the lower roughness below the Ra 3.2 .mu. m of the strip surface, the texturing time of the pulse mode is longer than the capacitor mode. In SBT method, the peak shape is similar to capacitor mode. But the EDT roll has more uniformity than the SBT roll and has more peak count than that of SBT roll. Therefore, in the painted steel sheet, EDT roll gives better surface of clarity image than the SBT roll.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.16-25
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• 2019

Recently, due to labor shortages in rural areas within South Korea, the demand for upland-field machinery is growing. In addition, there is a lack of development of systematic performance testing of upland-field machinery. Thus, this study examined structural safety and drawbar pull based on soil properties, as a first step for systematic performance testing on the test bed. First, the properties of soil samples from 10 spots within the experimental site were examined. Second, the strain was measured and converted into stress on 8 points of an onion harvester that are likely to fail. More specifically, the chosen parts are linked to the power, along with the drawbar pull, using a 6-component load cell equipped between the tractor and the onion harvester. The water content of the soil ranged between 5.7%-7.5%, and the strength between 250-1171 kPa. The test soil was subsequently classified into loam soil based on the size distribution ratio of the sieved soil. The onion harvester can be considered as structurally safe based on the derived safety factor and the drawbar pull of 115-1194 kgf, according to the working speed based on agricultural fieldwork.