• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.359-364
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• 2012

In order to prevent the decrease in well efficiencies due to friction in the axial flow in long, large-diameter laterals, a multi-diameter lateral was devised and tested through lab-scale sand-box experiments to assess its performance. In the experiment, three different production rates were applied over the multi-diameter and the three single-diameter laterals to obtain the hydraulic head distributions for each, which was used to assess the performance of the laterals. Results elucidated that the multi-diameter lateral reduced the material cost by more than a third, in comparison to the single-diameter lateral, while maintaining the production rate at higher than 93%, proving its superiority. Furthermore, results indicated that exit velocities exceeding 0.8 m/sec in horizontal wells tended to distort the hydraulic head distribution near the exit, providing evidence of its inefficiency.

• Journal of the Korean Regional Science Association
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• v.31 no.3
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• pp.39-54
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• 2015

To assess an economic value of Cheonggyecheon river restoration project, an in-depth exit survey data was collected to apply travel cost method in this study. Poisson model, Negative Binomial, Zero-truncated Poisson, and Zero-truncated Negative Binomial model were executed due to the nature of count data. Empirical results showed that regressors were statistically significant and corresponded to general consumer theory. Since our survey data showed over-dispersion, Zero-truncated Negative Binomial was selected as an optimal one to analyze travel demand of Cheonggyecheon by model goodness of fit test among those aforementioned empirical models. Estimating an economic value of Cheonggyecheon river restoration project, which is known as an ecological river restoration project, we used annual visit of individual traveler and an optimal model. Suffice to say that the annual economic value of Cheonggyecheon river restoration project was estimated as 193.4 billion won in 2013.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.94-102
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• 2015

The high-pass(brand name of Electronic Toll Collection System) utilization trend on the highway continues to grow as 59.4% (by the end of 2013). In this study, we applied the carbon balance method using a fuel chassis dynamometer with the four passenger car classes in order to measure the fuel consumption of the car using the expressway tollgate. We experimented 18 driving mode at general tollgate and high-pass tollgate. As a result, in case of entry/exit toll there were 21.0~56.4ml/veh fuel consumption savings, in case of open toll fuel consumption savings was analyzed as 10.5~28.1ml/veh. In addition, the annual fuel cost savings by virtue of high-pass was 28.2~57.3 billion won at 70% utilization rate, 32.2~65.5 billion won at 80%, 36.2~73.7 billion won at 90% and 40.3~81.9 billion won at 100%.

• The Journal of Society for e-Business Studies
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• v.22 no.4
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• pp.141-158
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• 2017

Along with IT development, customers are getting more easily to express their opinions using various IT channels. In this situation, complaint management is a pressing issue for companies to acquire and maintain loyal customers with low cost. Most of previous studies have investigated customer complaint information by quantitative variables such as demographic information, transaction information, or complaint frequency, but studies focusing on qualitative aspects of complaint information are limited. Therefore, this paper considers the possibility for customers to leave even when they complain occasionally or briefly. This paper analyzes the quantitive aspects as well as the qualitative aspects using sentiment analysis with Exit-voice theory. The dataset contains 268,364 inquiries of 46,235 customers obtained from a contact center of a private security company in Korea. This paper carries out logistic regression and the results imply that the customers's explicit response and their implicit sentiment have different effect on customers leave. This study is expected to provide useful suggestions for the effective complaint management.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.127-133
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• 2013

PURPOSES : The impact performance of flexible barrier system such as structural response, vehicular motion and occupant safety vary depending on the impact point. Thus, to properly evaluate the performance of a flexible barrier system, impact should be made to a point which will lead to the worst possible results. This point is called the Critical Impact Point (CIP). This paper presents the way to determine the CIP for a SB2 class flexible barrier system which is consisted of Thrie-Beam rail and circular hollow tube post of 2m span. METHODS: Barrier VII simulations were made for impact points; Case 1 at a post, Case 2 at 1/3 span downstream from a post, Case 3 at middle of the span, Case 4 at 2/3 span downstream from a post. For the structural performance (deflections), impact simulation of 8000kg-65km/h-15degree was used, and for vehicle motion and occupant safety, simulation of 1300kg-80km/h-20degree impact was made and analysed. RESULTS: Case 1 gave the largest dynamic deflection of 75.72cm and also gave the largest snag value of 44.3cm. Occupant safety and exit angle of the vehicle after the impact were not sensitive to the impact point and were all below the allowable limit. CONCLUSIONS : For the SB2 class flexible barrier system's CIP can be regarded as a post which is sufficiently away from the end of Length of Need in order to avoid the end-effect of the barrier system. It can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.449-455
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• 2002

This paper considers that advanced planning and scheduling (APS) in manufacturing and the efficient purchasing where each customer order has its due date and multi-suppliers exit We present a Make-To­Order Supply Chan (MTOSC) model of efficient purchasing process from multi-suppliers and APS with outsourcing in a supply chain, which requires the absolute due date and minimized total cost. Our research has included two states. One is for efficient purchasing from suppliers: (a) selection of suppliers for required parts; (b) optimum part lead­time of selected suppliers. Supplier selection process has received considerable attention in the business­management literature. Determining suitable suppliers in the supply chain has become a key strategic consideration. However, the nature of these decisions usually is complex and unstructured. These influence factors can be divided into quantitative and qualitative factors. In the first level, linguistic values are used to assess the ratings for the qualitative factors such as profitability, relationship closeness and quality. In the second level a MTOSC model determines the solutions (supplier selection and order quantity) by considering quantitative factors such as part unit price, supplier's lead-time, and storage cost, etc. The other is for APS: (a) selection of the best machine for each operation; (b) deciding sequence of operations; (c) picking out the operations to be outsourcing; and (d) minimizing makespan under the due date of each customer's order. To solve the model, a genetic algorithm (GA)-based heuristic approach is developed. From the numerical experiments, GA­based approach could efficiently solve the proposed model, and show the best process plan and schedule for all customers' orders.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.138-147
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• 2015

The primary focus of Korea's advertisement policy has been on the securing of stability in the market through building categorical entry barriers whenever a new broadcaster came into the market. But the recent contraction of the advertisement market is pressing the policy makers to lift the categorical barriers to create one large-enough market. This change in the policy and the market, in turn, is triggering heightened competition among drama producers to get advertisements, at times, even at the expense of cost efficiency. The market is supposed to search for its own equilibrium in principle. This means that players, who fall behind, should be left to die out and exit, and the patient policy to let the market function on its own should be institutionalized. Separately, the fee-based public broadcasters should be banned from running advertisements.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1178-1186
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• 2002

Clean stockers are being used by semiconductor and TFT-LCD manufacturers to store and buffer work in process. The only way to keep the stored product clean is to provide constant clean airflow the product and through stocker. Up to now, stockers typically have been configured to receive their laminar airflow from fan filter units that are located on the side of the stocker. This type of stocker may have such problems as complexity of structure, increment of temperature, mechanical vibration, initial investment and running cost. In this study, in order to solve the above mentioned problems, new air control system in stocker is proposed, which is to control open ratios of exits that are located on the side of the stocker without fan filter units. In this study, static pressure regain was used for the analysis of the open ratios of exits theoretically and experiment was also conducted using actual clean stocker for TFT-LCD manufacturers and CFDesign, was used for simulating airflow in stocker. As a result, open ratios of exits can be obtained by the analysis of static pressure regain and was verified by experiment and simulation results. Therefore, new air control system in stocker can be used by the semiconductor and TFT-LCD manufacturers.

• Journal of Korean Library and Information Science Society
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• v.32 no.3
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• pp.1-29
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• 2001

This study is to investigate extensively the complaint responses of the public library users, as an example of the complaining behaviors of the clients in not-for-profit organization. It selects and analyzes empirically some of the antecedents of the complaining behaviors including attitude toward complaining, cost of the complaining, likelihood of success, of success, product, external attributions and loyalty, and complaint responses including exit, voice(redress seeking), negative word-of-mouth and third party complaints, of the public library users, based on the theoretical backgrounds. It also examines the free use as a new variable of antecedents for not-for-profit organizations. Final data through questionaries are obtained from 515 unsatisfied adult public library users in Taegu, 456 of them analysed with SPSS 10.0 for Windows.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.693-702
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• 2009

A computational fluid analysis was performed on an LOx line system of a liquid rocket engine. The model was created with 3D CAD and imbedded to the 3D CFD program. Before the full scale analysis on the system was carried out, each components with simplified models was analyzed to save time and cost. As a result, the inlet pressure of the gas generator should be compensated with a certain device unless the inlet pressure of the line system is sufficiently high. The flow pattern of the exit of the system was dependant upon the location of the orifice as well as the size. As a whole the line system analyzed met the requirements, and will be tested and confirmed after being manufactured.