• IE interfaces
• /
• v.12 no.1
• /
• pp.150-157
• /
• 1999

Mini-Mill process has been recently in operation at Pohang steel company, which enables more flexible steel coil production on customer demands. The effects of process parameters in Mini-Mill process need to be analyzed not only to make the process stable but also to improve product quality. This work aims to develop a regression model of Mini-Mill process using accumulated product data such that the process parameter effects on product tensile strength may be analyzed. The analysis shows that tensile strength is influenced mainly by the amount of components such as carbon, manganese, silicon, and sulfur. The effect of temperature is shown to be small. It is concluded that control of the components is much more responsible for both meeting the target and reducing the variation of the product tensile strength. Heat treatment is more useful in compensating tensile strength variations due to thickness differences and improving workability and other quality characteristics. More work is necessary for establishing regression expressions of the process that is reliable and accurate enough to dispense with the off-line inspection of the product tensile strength.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.176-179
• /
• 2003

The mean temperature prediction of strip is very important in hot strip finishing mill because of affecting on product quality and shape. Also, temperature can be used by basic information in other on-line control models with affecting control accuracy in factory. So, FE based on-line temperature model was developed for predicting strip mean temperature accurately in various process conditions and factory environments. There are many variables in affecting strip mean temperature in on-line states of factory. But some problems are occurred in considering all variables for making temperature model because of the bad efficiency of regression or fitting analysis. In this report, we have adopted dimensional analysis for solving these problems. We have many variables with dimensions affecting strip temperature but we are able to make non-dimensional variables less than dimensional variables from the combination of dimensional variables caused by PI-Theorem in fluid mechanics. The developed models are divided by two parts. The one is interstand temperature prediction model. The other is roll gap temperature model.

• Journal of the Korea Safety Management & Science
• /
• v.6 no.2
• /
• pp.11-21
• /
• 2004

Objectives: The aim of this study is to determine prevalence and related factors of musculoskeletal symptoms in electronics assembly line workers. Method: A questionnaire survey was performed on 350 workers in In-chon city. The questionnaire consisted of questions on the general characteristics, work duration, working hours, hobby activity hours, housekeeping activity hours and standardized descriptions of NOISH on musculoskeletal symptoms. Result: Complaint rates of musculoskeletal symptoms by anatomical site were as follows: shoulder, 67% : neck, 40.4% : waist, 28.7% : wrist and hand, 27.1% : foot and leg, 14.4% : arm and elbow, 11.2%. Significantly higher prevalence of shoulder musculoskeletal symptom was found women than men, married than unmarried, less than 1hours housekeeping activity than over 1hours housekeeping activity. Multiple logistic regression analysis identified gender, marital status and housekeeping activity as the main affecting factors for shoulder musculoskeletal symptoms. Conclusions: The most prevalence of musculoskeletal symptoms was shoulder site. It was higher in married women and over 1hours housekeeping activity in a day. It is recommended that married women should be reduce housekeeping activity time.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.3
• /
• pp.274-279
• /
• 2008

Roll to roll (R2R) manufacturing process, also known as 'web processing', has been tried for producing electronic devices on a flexible plastic or metal foil. To increase the performance and productivity the R2R process, effective control and on-line supervision for web quality becomes very important. Wrinkle is one of the defects, which is incurred due to compressive stresses. A system for on-line measurement of wrinkle is developed using area scan camera and machine vision laser. The 2D image, obtained by area scan camera, is produced by Gaussian regression method to characterize the wrinkle on a transparent web. The experiment proves that 0.3mm wrinkle height can be measured successfully with 74fps.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.905-906
• /
• 2008

This paper presents a method where the best focues points are calculated using line fitting. Two datasets are selected for each pixel based on the maximum value which is calculated using Laplacian operator. Then linear regression model is used to find lines that approximate these datasets. The best fit lines are found using least squares method. After approximating the two lines, their intersection point is calculated and weights are assigned to calculate the new value for the depth map.

• International Journal of Internet, Broadcasting and Communication
• /
• v.8 no.3
• /
• pp.1-11
• /
• 2016

This study investigates whether different SNS with different characteristics have different impacts on participatory social capital in Korea. At least in Korea, SNS are categorized into five types (community, blog, micro-blog, profile-based service and instant message service), and participatory social capital is specified by three types (off-line political participation, on-line political participation, on-line civic engagement). Using Nielsen KoreanClick's web-based survey data, our regression analysis shows that SNS which are more open and focused on information sharing contribute more to participatory social capital.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.08a
• /
• pp.368-377
• /
• 2004

A mathematical model was developed for the prediction of the average temperature and RDT(RM Delivery temperature) in a roughing mill. The model consisted of three parts as follows (1) The intermediate numerical model calculated the deformation and heat transfer phenomena in the rolling: region by steady state FEM and the heat transfer phenomena in the interpass region by unsteady state FEM (2) The Off-line prediction model was derived from non-linear regression analysis based on the results of intermediate numerical model considering the various rolling conditions, (3) Using the heat flux in rolling region, temperature profile along thickness direction was calculated. For validation of the presented model, the rolling force per pass and RDT measued in on-line process was compared with those of model and the results showed close agreement with the existing data. In order to demonstrate the effectiveness of the proposed model, the various rolling conditions was tested.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.24 no.7
• /
• pp.976-986
• /
• 2000

The purpose of this study is to clarify the relationship between the visual sensibility and the decorative design of clothing. 41 kinds of costume samples have been selected from photographs in fashion magazines under detail and trimming, and divided into three types according to line, shape, and form. I have measured these images by using Semantic Differential method. The obtained data were analyzed by factor analysis ANOVA, discriminant analysis, regression analysis and MDS. The results of analysis are as follow; 1. Factor analysis has extracted five factors which consist of decorative design sensibility. These factors are Attractiveness, Hardness and Softness, Rhythm, Decorativeness, Cuteness. 2. There were significant differences in visual evaluation of decorative design and demographics 3. The discrimination among formative designs was closely related to decorative image, especially between line and form. 4. The Image effect on Preference, Buying needs, Riches and Pleasant was consist of complicated sensibility. 5. Evaluative dimensions of decorative design were identified by Simple-Complicated, Cubic -Plane perceptive image differed in degree of similarity in spite of same formative design.

• International Journal of Concrete Structures and Materials
• /
• v.3 no.1
• /
• pp.63-69
• /
• 2009

This paper provides the engineer with a simple design method dealing with situations arise where in-situ reinforced concrete joints are cast between hollow core units. Using finite element method, hollow core slabs with wide in-situ RC joints under point load and line loads are analysed. In addition, some important behavioural characteristics of the floor slab subjected to line and point loads are investigated. In-situ reinforced concrete joint causes reduction of load distribution for remote units because distance to the remote units from the point of load is increased, while the portion of load distribution carried by loaded unit increases. Also, it was turned out load distribution factors for point load and line loads are almost same. Finally, we suggest a simple analytical method, which can determine load distribution factors using normalized deflections by regression analysis for design purposes.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.10
• /
• pp.1869-1880
• /
• 2009

Distribution line fault has been reduced gradually by the efforts on improving the quality of electrical materials and distribution system maintenance. However faults caused by medium voltage customers have been increased gradually even though we have done many efforts. The problem is that we don't know which customer will cause the fault. This paper presents the concept to find these customers using data mining techniques, which is based on accumulated fault records of medium voltage customers in the past. It also suggests the prediction model construction of medium voltage customers causing distribution line fault and methods to enhance the reliability of distribution system. We expect that we can effectively reduce faults resulted from medium voltage customers, which is 30% of total faults.