• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.94-101
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• 2009

Complex Products may present more than one type of defects and these defects are not always of equal severity. These defects are classified according to their seriousness and effect on product quality and performance. Demerit systems are very effective systems to monitoring the different types of defects. So, classical demerit control chart used to monitor counts of several different types of defects simultaneously in complex products. S.M. Na et al.(2003) proposed the Demerit-CUSUM for the improvement of the demerit control chart performance and Nembhard, D. A. et al.(2001) and G.Y Cho et al.(2004) developed a Demerit control chart using the EWMA technique and evaluated the performance of the control chart. In this paper, we present an effective method for process control using the Demerit-CUSUM with fast initial response. Moreover, we evaluate exact performance of the Demerit-CUSUM control chart with fast initial response, Demerit-CUSUM and Demerit-EWMA according to changing sample size or parameters.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.452-462
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• 1985

The axisymmetric forward extrusion is analyzed by using the rigid-plastic finite element formulation. The distribution of stresses and strains as well as the deformation pattern in solid extrusion is very important for the improvement of product quality. The initial velocity field is determined by assuming the material as a Newtonian fluid through an arbitrarily shaped axisymmetric die. The workhardening effect and the friction of the die-material interface are considered in the formulation. Some reduction of area and die shapes(conical and biquadratic-curved) are chosen for computation. Experiments are carried out for steel alloy(SCM4) specimens using conical and curved dies. It is found that experimental observation is in good agreement with FEM results. The strain distribution is curved(biquadratic) dies is shown to be more uniform than in conical dies at the same reduction of area.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.45-51
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• 2010

Electrical discharge drilling (ED-drilling) is a widespread machining method used to bore small holes with a high aspect ratio. This paper presents additional methods by which ED-drilling can improve machining speed, tool wear, and machined surface quality. Firstly, for high machining speed, and low tool wear, a new-type electrode that was ground on one side or both sides of the cylindrical electrodes was suggested to expel debris. The debris which is generated during the machining process can cause sludge deposition and secondary discharge problems: major reasons to decrease machining speed. This new-type electrode also reduced tool wear that was due to the decrease of unstable discharge in a machining gap by helping to expel waste water and debris from the gap. Secondly, to improve the machined surface roughness, an electrolyzation process was included after drilling. This process made the machined surface smooth by means of an electrochemical reaction between an electrode and a workpiece. In this study, the machining speed, electrode wear, and surface roughness were improved by the newtype electrode and the electrolytic process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.353-354
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• 2006

The automatic inspection system is developed for the formed end part of automotive fuel pipe. The developed system has functions of outer diameter and formed end length measurement by LVDT(linear variable differential transformer) together with burr cleaning of automotive fuel pipe. The measured data are managed and controlled in real time by embedded SPC(statistical process control) program. The system is composed of mechanical part, electronic part and developed software system. These three parts operate automatically by mutual communication with each other. The developed system showed good results in finding inferior goods and efficiency improvement of the fuel pipe production line. It also eliminated the unreliable manual inspection processes and improved the confidence of product quality.

• Journal of Fashion Business
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• v.6 no.5
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• pp.41-47
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• 2002

Until now, there is a tendency of most textile research focused on the certain specific area of textiles in profound. This paper based on the case study of inspection of manufacturing men's formal wear has been investigated in the relationship between defection of men's formal wear and mechanical properties of textile for fall and winter. As a results of implementing Pearson's Correlation, density, blend rate, bending property, the rate of silk blend, the formality of sewing are correlated with defection of men's formal wear. However, it is required the defection of classification standard in various types of the finished product in a further study. In addition to increase efficiency of production in the manufacture, it is necessary for scholars to investigate the direction of research according to the contingency approach based on the systems approach.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.269-275
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• 1999

A variable blank holding force method is proposed to improve deep drawing characteristics of sheet materials. In this method, the blank holding force (BHF) is controlled throughout a drawing process so that the punch load does not exceed a critical value, which is slightly less than the conventional process with the conforming process with the variable BHF is more flexible than the conventional process with the constant BHF and it could be used for improving the product's quality and drawability. In this paper we suggest a method controlling the BHF as a function of punch travel during the forming process. The optimization BHF curves are determined theoretically and experimentally. It is concluded that for the case of optimum BHF control methods the drawn cup height and the drawing formability achieved by this method are increased than those for constant BHF method. Also, as comparing the wall thickness distribution of the cup drawn by the constant BHF and the optimum BHF control, the BHF control reduce the wall thickness variation of the drawn cup at the cup wall and make the cup thickness distribution more uniformly than the constant BHF.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.577-582
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• 2012

Recently, noise reduction of air-conditioner is one of the important design factors for high quality product. Especially, customer complaints arise due to noise problem of the outdoor unit. After the operation of air-conditioner start, noise level of outdoor unit is increased gradually and sometimes abnormal noise occurs until it reaches steady state condition. The aim of this paper is to investigate the relation between noise of outdoor unit and thermodynamic properties of cycle at transient condition of room air-conditioner. In order to find out the noise characteristics of outdoor unit, noise and vibration measurements are carried out. Also, the thermodynamic properties of compressor and heat exchanger are measured by using temperature and pressure sensors and experimental results are discussed. Finally, we find out the relation between noise and cycle properties at starting of room air-conditioner and the improvement method to reduce noise level is proposed.

• Journal of the Korean Society of Food Culture
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• v.26 no.3
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• pp.283-294
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• 2011

The purpose of this study was to determine the optimal mixing conditions for three different amounts of mulberry juice, sugar, and agar powder for Yanggaeng prepared with mulberry juice. The experiment was designed according to the central composite design for estimating the response surface, which demonstrated 16 experimental points including 2 replicates for mulberry juice, sugar and agar powder each?? The mechanical and sensory properties of test materials were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the final product mixture. Measurement results of the mechanical properties showed a significant increase or decrease?? in pH, sugar content, water content, viscosity, l-value, a-value, b-value, hardness, springiness, chewiness, gumminess, cohesiveness. Also the sensory measurements showed a significant improvement?? in appearance, flavor, color, sweetness, texture, overall quality. As a result, the optimum formulation by numerical and graphical methods was calculated as mulberry juice 41.99 g, sugar 90.00 g, agar powder 3.18 g.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.283-292
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• 2013

This paper aims to propose a new steps of hypothesis testing using analysis process and improvement process in the six sigma DMAIC. The six sigma implementation models proposed in this paper consist of six steps. The first step is to establish a research hypothesis by specification directionality and FBP(Falsibility By Popper). The second step is to translate the research hypothesis such as RHAT(Research Hypothesis Absent Type) and RHPT(Research Hypothesis Present Type) into statistical hypothesis such as $H_0$(Null Hypothesis) and $H_1$(Alternative Hypothesis). The third step is to implement statistical hypothesis testing by PBC(Proof By Contradiction) and proper sample size. The fourth step is to interpret the result of statistical hypothesis test. The fifth step is to establish the best conditions of product and process conditions by experimental optimization and interval estimation. The sixth step is to draw a conclusion by considering practical significance and statistical significance. Important for both quality practitioners and academicians, case analysis on six sigma projects with implementation guidelines are provided.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.5-9
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• 2007

The construction method for Foamed-Concrete has not been important due to following process of construction work. However, according to the code about enhance of energy saving design policy and impact noise, noised isolation has been used in construction site so that the resistance for cracking and capability for insulating of Foamed-Concrete has been required. Therefore, new alternatives are demanded. Optimum mixing design, which can get the improvement of insulation and resistance of crack for Foamed-Concrete adding EVA chip, was derived and also the device, applying to construction site, was invented to equalize quality. This device can measure quantity of all input and placement, and show up the sum of placement and mixing design on a touch screen. This valuable construction method is friendly environment and recycling method because of using EVA chip, by-product of an EVA insole scrap burned or embedded, as a light-weight aggregate.