• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.246-249
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• 2007

It is very important that there are saving resource and energy in the future as well as in these day. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. Extruded aluminum parts' cross sections are constant in the axial direction by conventional extrusion method. Especially these aluminum parts used in the car need other processes to vary the cross section in the axial direction. Thus, applications of these parts are limited by high cost. if the cross section of the parts is variable by only extrusion, application of extruded aluminum parts will more increase. Therefore, a new CNC extruder which can control the section area of a car part was invented the nation's first. Using the extrusion machine, the experiment was performed to validate the workability.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.214-218
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• 2011

In order to survive in turbulent and competitive markets, automotive part manufacturers try efforts to develop new manufacturing technologies for ultra-lightweight, high-intensity and environmentally-friendly parts. Most of front lower arm is manufactured by welding process between upper- and lower panel which are produced by press stamping process. Because lower arm mounted on the cross member parts is one of the important complementary parts. So, to improve safety and lightweight of these parts, hybrid technologies are used in this paper. As hybrid technologies are applied to be front sub-frame, rear cross member and other chassis parts as well as front lower arm, the 20% lightweight has been achieved compared with existing steel parts.

• Journal of the military operations research society of Korea
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• v.30 no.2
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• pp.108-121
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• 2004

This paper deals with a procedure of changing the current inspection & replacement periods for ROKAF aircraft parts. ROKAF is mostly operating aircraft of foreign makes, and takes maintenance actions according to Technical Orders(TO.) published by foreign aircraft manufacturers. Therefore ROKAF inspects and replaces specific parts at the time noticed from T.O.. These inspection and replacement periods are determined by manufacturers according to the standard operating environment and parts' durability. But the standard operating environment Is different from operator's environment. Because of this difference, the inspection and replacement periods have to be changed according to operators' operation environment. It is resonable that the manufacturer, having design materials and life test data of parts, changes those periods together with materials of operators' operation environment. But we have many difficulties in obtaining the design materials and life test data. Then this paper proposes a procedure of changing the periods of aircraft's parts with life data obtained during operating aircraft. For the reliability analysis, a software of RELEST (Reliability Estimation Version 1.0) is used.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.87-99
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• 1998

This study is concerned with a problem of determining the optimal requirements level of the spare parts, especially Concurrent Spare Parts(CSP). CSP is supplied with the procurement of new equipment system, and is used to sustain the equipment without resupply during the initial coverage period. We consider this situation as a multiechelon inventory model with several bases and one depot. And we assume a equipment system which consists of many types of parts would grounded if one of the parts fail. Also this multiechelon CSP problem is considering a time-varing (dynamic) environment. We develop a computational procedure to find the optimal number of spare parts minimizing the total expected cost, while achieving the required system availability. Finally we present a simple example of suggested method.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.140-145
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• 2014

The globally used PV qualification tests and reports the pass/fail only. Therefore, the reliability of new PV materials and parts can't be compared quantitatively with the reliability of the PV parts and materials in the market. Global PV materials and parts companies test and compare their materials, parts, and modules using the failure-to-test (FTT). However, it takes a long accelerated stress test (AST) until failure. It also needs to test the new and existing materials and parts. Therefore, it requires excessive equipment time and cost. In order to reduce the time and cost, a new reliability enhancement methodology has been developed. It tests the PV materials, parts, and modules in the global market and stores them in the PV reliability database. It reduces the time and cost of the comparison and enhancement of PV reliability. An example of the reliability enhancement of the PV encapsulant, EVA is presented.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.19-24
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• 2016

Rubber parts are widely used in many applications such as dampers, shock absorbers, and seals used in railway and automotive industries. Much research has thus far been conducted on property estimation and life prediction of rubber parts. To predict the service life of rubber parts at room temperature, most prior work adopts the well-known Arrhenius model that needs the accelerated life test in high-temperature conditions. However, they may not reflect the actual conditions of use that rubber parts are usually used under a specific strain condition during long period of time. In this context, we propose a method for the life prediction of rubber parts in actual conditions of use. The proposed method is based on the accelerated life test using stress relaxation during which three relatively high elongation percentages (100%, 200%, and 300%) are applied to the rubber specimens. Rubber specimens were prepared in accordance with KS M 6518 standard and three stress relaxation testers were fabricated for actual experiments. Finally, a inverse power model for life prediction was derived from experimental results. The predicted life was compared with the actual test life for validation.

• Journal of Distribution Science
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• v.11 no.11
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• pp.89-99
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• 2013

Purpose - The purpose of this research was to examine the regulation and distribution channel of second-hand goods in cross-border trade in order to propose methods of protecting consumers through the international standardization of the intensifying second-hand trade and resource recycling. Research design, data, methodology - This study first defines several concepts relevant to research in international second-hand goods. Second, a questionnaire and interviews were conducted with manufacturers of second-hand toner cartridges and automobile parts to identify the current status of export and manufacturing. Results - The study proposes the international standardization of second-hand goods and waste to protect consumers and promote efficient resource recycling. Conclusions - The results of the study reveal that second-hand goods (except automobiles) do not have an HSK code to use for import/export data collection. Though used car exports are declining, used cars are increasing. Collecting data on used car parts is impossible because the buyers purchase and ship the second-hand parts.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.2
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• pp.74-80
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• 2012

In this paper, we developed the profile analysis-based machine vision system for inspecting assembly parts in the industrial field. Implemented system composed of triple set of camera: one was used for acquiring slant image; other is required to acquire a top image; the other was used for side image. After obtaining parts which have gray scale image, threshold value was calculated by analyzing the profile of the image. Experimental results showed that proposed algorithm have a good performance for detecting fault parts and for classifying each parts as well.

• 연구논문집
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• s.32
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• pp.35-43
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• 2002

This study was performed to develop accelerated life test method of machanical parts using cumulative damage theory that used to model the fatigue of parts that receive variable load. The cumulative damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the cumulative damage theory, because test time can shorten in case increase test load, test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7. This accelerated test method was used to develop accelerated test method of gear reducer, hydraulic hose and bearing as well as agricultural tractor transmission and it is considered to be applied comprehensively to machanical parts the fatigue of which is happened by load or pressure etc.

• Industrial Engineering and Management Systems
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• v.13 no.2
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• pp.129-147
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• 2014

This study proposes an optimal operational policy for a green supply chain (GSC) where a retailer pays an incentive for collection of used products from customers and determines the optimal order quantity of a single product under uncertainty in product demand. A manufacturer produces the optimal order quantity of product using recyclable parts with acceptable quality levels and covers a part of the retailer's incentive from the recycled parts. Here, two scenarios for the product demand are assumed as: the distribution of product demand is known, and only both mean and variance are known. This paper develops mathematical models to find how order quantity, collection incentive of used products and lower limit of quality level for recycling affect the expected profits of each member and the whole supply chain under both a decentralized GSC (DGSC) and an integrated GSC (IGSC). The analysis numerically compares the results under DGSC with those under IGSC for each scenario of product demand. Also, the effect of the quality of the recyclable parts on the optimal decisions is shown. Moreover, supply chain coordination to shift the optimal decisions of IGSC is discussed based on: I) profit ratio, II) Nash bargaining solution, and III) Combination of (I) and (II).