• Proceedings of the KSR Conference
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• 2011.10a
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• pp.303-310
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• 2011

This paper is focused on development of models for measuring lateral and vertical track irregularities from corresponding accelerometers of an in-service high-speed train. Generally, the track irregularity was measured by a special railway inspection vehicle or system with contact or non-contact sensors. However, the sensors are very expensive and vulnerable to a harsh environment. Displacement estimation from an inertial measurement unit and its wave-band filtering was already developed in the previous study, and it was found that their results included not only the track irregularities but also other information such as phase delay of the applied filters, and suspension and conicity of the wheel. To identify the track irregularities from those results, a compensation filtering method was proposed. Each directional compensation filter was derived by using a system identification method with the estimated directional displacement as input and the corresponding track irregularities as output. In this paper, they are integrated into a model for each direction and applied to the measured lateral and vertical acceleration data from the axle-box and bogie of an in-service high-speed train. Their results are compared with the data from the track geometry measurement system. From the comparison, the proposed models are a useful tool for the measurement of the track irregularities using accelerometers of in-service high-speed trains.

• IE interfaces
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• v.22 no.4
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• pp.336-346
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• 2009

One of primary assumptions on DEA is that all DMUs for evaluation should be homogeneous. In comparative analysis among DMUs with relative efficiency measurement, it should be evaluated under identical conditions by ruling out external environmental influences. In this study, a measurement of innovation efficiency using the three-stage approach is performed. The approach employs DEA to measure relative efficiency and Tobit regressions to control external variables affecting innovation activity. The approach applied to firms in Korean Innovation Survey: Service Sector 2003 and 2006. Final efficiency scores of the approach represent net efficiency of the innovation. This study found that there is a increasing on technical efficiency of third stage, and it has difference with first stage significantly. Besides, a decrease on standard deviation of third stage is found. It means DMUs biased lower due to unfavorable condition and ones biased higher due to favorable condition are fallen into an identical operating environment through the approach. A measurement of net efficiency, excluding external effects, ensures the homogeneity of DMUs so that improves the reliability in terms of its analysis results. This study is expected to provide a direction and to be a valuable reference to further evaluation of innovation performance in Korean service sector.

• ETRI Journal
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• v.40 no.1
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• pp.26-38
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• 2018

To overcome considerable path loss in millimeter-wave propagation, high-gain directional beamforming is considered to be a key enabling technology for outdoor 5G mobile networks. Associated with beamforming, this paper investigates propagation power loss characteristics in two aspects. The first is beamwidth effects. Owing to the multipath receiving nature of mobile environments, it is expected that a narrower beamwidth antenna will capture fewer multipath signals, while increasing directivity gain. If we normalize the directivity gain, this narrow-beamwidth reception incurs an additional power loss compared to omnidirectional-antenna power reception. With measurement data collected in an urban area at 28 GHz and 38 GHz, we illustrate the amount of these additional propagation losses as a function of the half-power beamwidth. Secondly, we investigate power losses due to steering beam misalignment, as well as the measurement data. The results show that a small angle misalignment can cause a large power loss. Considering that most standard documents provide omnidirectional antenna path loss characteristics, these results are expected to contribute to mmWave mobile system designs.

• Journal of Information Technology Applications and Management
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• v.12 no.3
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• pp.111-128
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• 2005

This paper examines the validity of the newly developed IT consulting SERVQUAL measurement tool. In an attempt to measure Ire IS customers' expectations and perceived quality of the services they received, the researchers developed a diagnostic tool of SERVQUAL based on the solid theoretical background, which can specifically be applied to the IT consulting service sector. This on-going research so far, has been applied to six (6) different organizations that have received IT consulting services over the past years. From the preliminary data collected, the correlation and the factor analyses were conducted to understand the underlying concept and refinement of the measurement tool. Although the correlation analysis showed a little tendency of collinearity among some of the variables, all showed sound relationship of the proposed hypotheses. The exploratory factor analytic approach was chosen because it does not set any priori constraints on the estimation of components or the number of components to be extracted. The number of different factor solutions was extracted and tested to see which solution represents better grouping of the variables. The Crombach's Alpha was computed on different combinations of the factor solutions to ensure validity. The results show 8-dimensional IT consulting SERVQUAL measures which they are, assurance, knowledge & skill, customer relationship, support, empathy, process management, expertise, and education, seem more appropriate than the originally proposed 6 dimensions. The study approach was non-experimental cross-sectional research design. The longitudinal design of follow-up studies to periodically revise and refine current measure is strongly recommended for fine tuning of the tool.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.270-274
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• 2007

In this paper, we present a Sound Source Localization (SSL) based GCC (Generalized Cross Correlation)-PHAT (Phase Transform) and new measurement method of angle with robot auditory system for a network-based intelligent service robot. The main goal of this paper is to analysis performance of TDOA and GCC-PHAT sound source localization method and new angle measurement method is compared. We use GCC-PHAT for measuring time delays between several microphones. And sound source location is calculated by using time delays and new measurement method of angle. The robot platform used in this work is wever-R2, which is a network-based intelligent service robot developed at Intelligent Robot Research Division in ETRI.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.61-82
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• 2020

The security risk management used by some service providers is not appropriate for effective security enhancement. The reason is that the security risk management methods did not take into account the opinions of security experts, types of service, and security vulnerability-based risk assessment. Moreover, the security risk assessment method, which has a great influence on the risk treatment method in an information security risk assessment model, should be security risk assessment for fine-grained risk assessment, considering security vulnerability rather than security threat. Therefore, we proposed an improved information security risk management model and methods that consider vulnerability-based risk assessment and mitigation to enhance security controls considering limited security budget. Moreover, we can evaluate the security cost allocation strategies based on security vulnerability measurement that consider the security weight.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.10
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• pp.968-975
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• 2010

The high interest for the ground vibrations which is caused by the train service is risen. When the trains are passed, a serious force is applied to ground and the caused vibration is propagated to the area of the building by the ground and rocks. This vibration comes to feel in the residents with the direct vibration, it is radiated in sound. The caused vibration and radiated sound affect the human's life, and this vibration brings about the operation interruption of the equipment which is sensitive to the vibration, or will bring about the structural damage of the building. In this study, the effect of the vibrations caused by the passing trains on the railway station and buildings is investigated by vibration measurement. Indoor and outdoor measurement is carried out by each trains.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.2
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• pp.313-329
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• 2011

To provide a seamless network to customers, Internet service providers must promptly detect and control abnormal traffic. One approach is to shorten the traffic information measurement cycle. However, performance degradation is inevitable if traffic measurement servers merely shorten the cycle and measure all traffic. This paper presents a software architecture that can measure traffic more frequently without degrading performance by estimating the level of abnormal traffic. The algorithm in the architecture estimates the values of the interface group objects in MIB by using the IP group objects thereby reducing the number of measurements and the size of measured data. We evaluated this architecture on part of Internet service provider's IP network. When the traffic was measured 5 times more than before, the CPU usage and TPS of the proposed scheme was 7% and 41% less than that of the original scheme while the false positive rate and false negative rate were 3.2% and 2.7% respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.387-393
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• 2009

In this paper, we have considered the network performance of the VoIP service with the measurement by an emulator, and analyzed the major factors to affect its performance. Also, we have used the measured values to investigate the traffic variations, where their values were observed in the commercial operated network after the delay, jitter and packet loss, and loss compensation methods were applied as the dominant elements. It is expected that our presented results will be a good data to provide the high-quality of voice service in the Internet.

• Journal of Korean Society for Quality Management
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• v.37 no.2
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• pp.1-11
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• 2009

Recently, many companies have been very interested in CRM(Customer Relationship Management). Most companies have been also considering the contact center as a key CRM channel, because it is a contact point between customers and companies. It turns out that the contact center handles over 70% of all customer-company interactions and the success or failure of a company can be determined by the customer satisfaction with contact center experiences. Despite of the strategic importance of the contact center, there has been few empirical study on the efficiency of contact center operations in the literature. One of the main purposes of this study is to evaluate the efficiency of contact centers so as to not only identify the current status of contact center operations, but also suggest ways to improve operational efficiency. For this purpose, we apply a non-parametric efficiency measurement method, DEA (Data Envelopment Analysis), to 57 domestic contact centers in order to compare their relative efficiency. It is expected that the measurement methods suggested in this study can be applied to various issues such as service KS certification, outsourcing service management, and the productivity analysis of service personnel.