• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.573-576
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• 2016

In this study, hydrogenation of 1,2,3,3,3-pentafluoropropene was performed to produce R-1234yf as an environmentally friendly refrigerant. Palladium based carbon was prepared as a catalyst in the hydrogenation reaction. The effect of reaction conditions including the weight hourly space velocity (WHSV), reaction temperature and ratio of hydrogen and reactants on the catalytic performance was investigated. Under the identical reaction conditions, the effect of WHSV on the main product selectivity was insignificant, but a high reaction temperature was essential for the good product selectivity. A high product selectivity was also obtained when the ratio of hydrogen and reactants kept less than 1.5. Moreover, a correlation model involving the statistical approach to predict product yields was developed.

• International Journal of Concrete Structures and Materials
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• v.6 no.3
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• pp.155-163
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• 2012

In order to predict the neutralization of concrete which is the reaction of carbonation dioxide from the outside and cement hydration product, such as calcium hydroxide and C-S-H, it was studied the numerical analysis method considering change of the pore structure and relative humidity during the neutralization reaction. Diffusion-reaction neutralization model was developed to predict the neutralization depth of concrete with coating finishing material. In order to build numerical analysis models considering outdoor environment and finishing materials, the adaption of proposed model was shown the results of existing outdoor exposure test results and accelerated carbonation test.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.44-49
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• 2007

Recent manufacturing system requires development on new production technology to enable prompt manufacturing of diverse products. Most of the researchers have been working on micro-factory. Especially, focus on manufacturing of micro parts. Present manufacturing system consumes excessive resources in the form of energy and space to manufacture the micro parts. In this study, the micro lens module assembly system was modeled, analyzed with MST(Micro System Technology) Application Module and simulated through UML Language (Unified Modeling Language) with object-oriented logical model analysis method. Digital model of micro-factory was modeled, to execute the new paradigm of digitalization on products, resources and processes of micro-factory.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.248-252
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• 2000

Form-ratio means the ratio of height/Width/Depth in 3-dimensions. The golden ratio or golden section is included as one of the form-ratio. We conducted two kinds of kansei experiments of cubic model and refrigerator varied from 1:1:1 to 1:1:3.66 on the scale of x:y:z. The subjects evaluate the form-ratios of 3-dimensional cubes and virtual products with SD-scale Kansei words(feelings and images). We applied the factor analysis to identify semantic space in cube model and virtual products. Finally, we compared with kansei structure of cube model and virtual product.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.1
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• pp.1-15
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• 1989

In the past few years, increasing numbers of automatic storage/retrieval system (AS/RS) using computer controlled storage/retrieval machine have been installed. This paper introduces two modeling approaches to determine the best operating policy for AS/RS : an M/G/1 queueing model and a computer simulation model. The operating policy consists of three elements. : the operation command cycle, the storage location method, and the operation dispatching rule. The analysis based on M/G/1 model is suitable for a quick and approximate evaluation, due to its inherent strict assumptions. The computer simulation can be used to perform a more realistic analysis. It is shown through the study that a significant improvement in the throughput and/or the space requirement can be expected by determining the best operating policy to a particular system. Most important, the computer simulation demonstrates its powerful capability in evaluating dynamic stochatic systems with imperfect information.

• Journal of the Korea Safety Management & Science
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• v.22 no.4
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• pp.45-52
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• 2020

Recently, a multi facility, multi product and multi period industrial problem has been widely investigated in Supply Chain Network(SCN). One of keys issues in the current SCN research area involves minimizing both production and distribution costs. This study deals with finding an optimal solution for minimizing the total cost of production and distribution problems in supply chain network. First, we presented an integrated mathematical model that satisfies the minimum cost in the supply chain. To solve the presented mathematical model, we used a genetic algorithm with an excellent searching ability for complicated solution space. To represent the given model effectively, the matrix based real-number coding schema is used. The difference rate of the objective function value for the termination condition is applied. Computational experimental results show that the real size problems we encountered can be solved within a reasonable time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.606-614
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• 2016

In order to expand the market of the domestic space information industry, which is currently saturated, overseas expansion is essential, but the prospects are limited. Therefore, an effective strategy of overseas expansion is needed. Given the current state of such spatial information industry, V-World is expected to play a very important role. In the world market for space information, in order to ensure the export competitiveness of the domestic space information industry, in the present study, research and development was carried out on the V-World-based packaged goods model as one possible method. First of all, to analyze the current situation and characteristics of the spatial information industry, to grasp V-World as a commodity and derive the relationship between foreign demand and V-World, the sales destinations and methods were defined. To formulate the basic strategy of the fusion-composite package export utilizing V-World on the basis of the basic concept of the product, the necessary components were designed. In response to this fusion-composite package product mix, the overseas promotion of spatial information-related companies it to be expected.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.9-16
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• 1995

Model material technique, which requires only the small space of experimental set-up and low cost for experiment, is used to estimate the deformed profile and the forging load in rotary forging. The materials and working conditions are determined to satisfy the similitude conditions between the model test and the prototype test. The model material of the so-called plasticine and the mild steel are chosen as specimens, and they represent almost the same value of strain gardening exponent in the stress-strain relationship. Lubricant in the model test is also carefully selected so that it gives the same frictional conditions at the tool-specimen interface. Experiments for two kinds of specimens are carried out in each testing equipment at room temperatue. From the experiments the deformed dimensions and the forging loads are measured and compared with each other by using the simulation coefficients. It is shown that there are good agreements between the model test and the prototype test. Finally, for verifying the availability of the model material technique this mathod is applied to forging of bevel gear product. the good result is obained which can demonstrate that the model material technique is very efficent for estimating or developing a new process.

• Journal of Internet Computing and Services
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• v.18 no.3
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• pp.19-28
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• 2017

Collaborative filtering (CF) is a system that interprets the relationship between a user and a product and recommends the product to a specific user. The CF model is advantageous in that it can recommend products to users with only rating data without any additional information such as contents. However, there are many cases where a user does not give a rating even after consuming the product as well as consuming only a small portion of the total product. This means that the number of ratings observed is very small and the user rating matrix is very sparse. The sparsity of this rating data poses a problem in raising CF performance. In this paper, we concentrate on raising the performance of latent factor model (especially SVD). We propose a new model that includes product similarity information and co occurrence information in SVD. The similarity and concurrence information obtained from the rating data increased the expressiveness of the latent space in terms of latent factors. Thus, Recall increased by 16% and Precision and NDCG increased by 8% and 7%, respectively. The proposed method of the paper will show better performance than the existing method when combined with other recommender systems in the future.

• Information Systems Review
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• v.7 no.2
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• pp.117-128
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• 2005

This study proposes an integrated monitoring system for data reliability improvement in a steel manufacturing industry. The data obtained from existing steel manufacturing process is not micro data which is gathered at the occurring point, but average value (macro data) which is gathered from the occurring point to ending point. This kind of macro data is not only difficult for a detailed analysis for an error causing factor, but it might cause a fatal influence as well on the quality of produced goods even if the error is within an error tolerance. And during the process of steel production, thousands of data is produced in a second, thus requiring database plan to manage abundant amount of data. Therefore, the following proposed system is capable of collecting as well as analyzing all the data generated from the process of product production. And the system was able to raise the efficiency of the database server by planning the database to handle large capacity data. Also, by applying web-based technology, inquiries and analysis of data with no limit on time and space was possible with PC connected to the intranet. Hence, the system was able to work on effective quality improvement of manufactured products, plus able to raise the reliability of the product. Also, accumulated data from long period of time was used for fundamental material for new controlling model, operation technology, and new product development.