• Korean Management Science Review
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• v.26 no.1
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• pp.183-196
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• 2009

Customer retention has been a pressing issue for companies to get and maintain the loyal customers in the competing environment. Lots of researchers make effort to seek the characteristics of the churning customers and the loyal customers using the data mining techniques such as decision tree. However, such existing researches don't consider relationships among customers. Social network analysis has been used to search relationships among social entities such as genetics network, traffic network, organization network and so on. In this study, a customer network is proposed to investigate the differences of network characteristics of churning customers and loyal customers. The customer networks are constructed by analyzing the real purchase data collected from a Korean cosmetic provider. We investigated whether the churning customers and the loyal customers have different degree centralities and densities of the customer networks. In addition, we compared products purchased by the churning customers and those by the loyal customers. Our data analysis results indicate that degree centrality and density of the churning customer network are higher than those of the loyal customer network, and the various products are purchased by churning customers rather than by the loyal customers. We expect that the suggested social network analysis is used to as a complementary analysis methodology with existing statistical analysis and data mining analysis.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.4
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• pp.57-72
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• 2009

As development of information technologies, customer retention has been an important issue in the competing environment. A lot of researches focus on prediction of the churning customers and seeking their characteristics. However, relationships among customers or products have not been considered in existing researches. In this study, product networks are proposed and analyzed to investigate the differences of network characteristics of products purchased by potential churning customers and those of loyal customers. The product networks are constructed from real product purchase data collected from a Korean department store. We investigated the characteristic differences, such as the degree centrality, degree centralization, and density, of two product networks constructed by potential churning customers and the loyal customers. The results indicate that degree centrality, density and degree centralization of the product network of the loyal customers are higher than those of the potential churning customers. And the promotional products of the department store are resulted to be effective in attracting the loyal customers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1059-1067
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• 1999

In this paper characteristics of ATM-PON is described and a TC layer controller for ATM-PON OLT is designed. This paper proposes an algorithm of economically controlling the grant information written by CPU to dynamically allocate the upstream bandwidth on the PON among the ONUs in a fair way and of encrypting the downstream data using a lower standard of encryption, termed data churning, which is used to distinguish it from existing transmission system scramblers and higher layer encryption methods. This paper also proposes a method of allocating churning-related message into the PLOAM cell in order to synchronously change the churning key between the OLT and the ONU.

• Journal of Service Research and Studies
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• v.6 no.3
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• pp.57-78
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• 2016

The purpose of this research is to study how service recovery activities influence customers' commodity churning in the media telecommunication industry(CATV industry). Put it differently, we tried to identify this change of commodity churning rates by the stages of service failures, by which we intend to emphasize the importance of service recoveries. Korean media telecommunication market has already been saturated; customers tend to move to bigger major companies with better customer care increasingly. As once customers gone never returns, CRM functions are being reinforced over the time. We were able to have the following results. First, turning rates, for those experienced service failure, who were dissatisfied with service recovery activities are 2~5 times (monthly average turning rates are 1.3%) higher than those satisfied. Secondly, active service recovery activities at the customer's service request after experiencing service failure lowered churning rates significantly. The most effective timing is service recovery activities pre-recovery stage. Thirdly, reward activities after service recovery activities at the immediate recovery stage is more effective than service recovery at the arranged recovery schedule and reward activities after customer's expressing churning intension. The implications of this study are that firms should engage in service recovery activities at the time of identifying service failures, prior to customer's expressing churning intention, which means relatively lower ROI for the service recovery activities than the times of customers' expressing churning intention.

• Information Systems Review
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• v.8 no.3
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• pp.125-134
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• 2006

This article adopts a decision tree algorithm(C5.0) to predict customer churning in online auto insurance environment. Using a sample of on-line auto insurance customers contracts sold between 2003 and 2004, we test how decision tree-based model(C5.0) works on the prediction of customer churning. We compare the result of C5.0 with those of logistic regression model(LRM), multivariate discriminant analysis(MDA) model. The result shows C5.0 outperforms other models in the predictability. Based on the result, this study suggests a way of setting marketing strategy and of developing online auto insurance business.

• Journal of Intelligence and Information Systems
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• v.8 no.2
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• pp.15-35
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• 2002

Data mining has received a lot of attention from practitioners. That is partly because it allows company to extract a set of useful knowledge about customers from database, thereby retaining current customers and magneting potential customers. This logic is especially essential in the field of credit card industry, where just 5% increase of number of customers is hewn to cause 120% increase in profit. The problem is how to retain current customers and even make them more loyal to company. However, previous studies lacked proposing extensive strategies of reducing the churning rate. In this sense, this study attempts to suggest such strategies by applying neural network, logistic regression, and C5.0 techniques to credit card data. We used a real data set of four years from 1997 to 2000, which were gathered from a credit card company. Experimental results revealed that our approach could yield robust strategies for retaining customers by reducing the churning rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.51-57
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• 2011

Parametric studies based on analysis of lubrication system of a four cylinder gasoline engine are illustrated system in this paper. In development process of engine lubrication system, parts of failure cases are related with oil pull over and oil churning phenomenon. The crankcase & head system pressure by oil churning phenomenon are gradual increased. It cause oil pull over phenomenon at engine breather line and oil over-consumption. In order to improve oil reduction and oil pull over phenomenon are also considered in the developing state. For this study, the characteristics of engine lubrication system are measured at various tilting angle and drain hole sizes. In addition, the oil flow & oil quantity are tested by blow by meter and catch jar. Results are presented to stabilize the oil supply system at sever driving condition. The data from present study are available for the engine lubrication system.

• Journal of Korea Multimedia Society
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• v.20 no.1
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• pp.1-9
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• 2017

Explosive deployment of smart mobile devices such as smart phones, and tablets along with expansion of wireless internet bandwidth have enabled the deployment of mobile video streaming such that video traffic becomes the most important service in wireless networks. Recently, for more efficient video streaming services, the ISO MPEG group standardized a protocol called DASH (Dynamic Adaptive Streaming over HTTP) and the standard has been quickly adopted by many service providers such as YouTube and Netflix. Despite of the convenience of mobile streaming services, users also suffer from low QoE(Quality of Experience) due to dynamic channel fluctuations and unnecessary downloading due to high churning rates. This paper proposes a noble efficient video rate selection algorithm considering user buffer level, channel condition and churning rate. Computer simulation based performance study showed that the proposed algorithm improved the QoE significantly compared to a method that determines the video rate based on current channel conditions. Especially, the proposed method reduced the rebuffering rate, one of the most important performance factors of the QoE, to a nonnegligible level.

• Journal of Intelligence and Information Systems
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• v.7 no.1
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• pp.17-25
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• 2001

Tree model is the most popular classification algorithm in data mining due to easy interpretation of the result. In CART(Breiman et al., 1984) and C4.5(Quinlan, 1993) which are representative of tree algorithms, the split fur classification proceeds to attain the homogeneous terminal nodes with respect to the composition of levels in target variable. But, fur instance, in the chum prediction modeling fur CRM(Customer Relationship management), the rate of churn is generally very low although we are interested in mining the churners. Thus it is difficult to get accurate prediction modes using tree model based on the traditional split rule, such as mini or deviance. Buja and Lee(1999) introduced a new split rule, one-sided purity for classifying minor interesting group. In this paper, we compared one-sided purity with traditional split rule, deviance analyzing churning vs. non-churning data of ISP company. Also reviewing the result of tree model based on one-sided purity with some simulated data, we discussed problems and researchable topics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1441-1446
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• 2012

An axial-piston-type hydraulic motor involves friction and leakage losses at the sliding parts, contact loss at the mechanism assembly parts, volumetric loss caused by the pressure drop, housing oil churning loss and compressibility from the hydraulic oil pipe resistance, etc. the friction and volumetric loss at the hydrostatic bearing between the piston shoe and the swash plate rotating at high speed and having an oil film gap of 8-15 ${\mu}m$ strongly affects the total efficiency of the hydraulic motor. In this study, a variable swash-plate-type hydraulic piston motor operating under a maximum pressure of 35 MPa, maximum speed of 2,500 rpm, and displacement of 320 cc/rev is tested to verify the optimal ratio of the hydrostatic bearing which is closely related to the hydraulic motor performance.