• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.84-94
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• 2018

In recent years, the diminishing of operation and maintenance cost using advanced maintenance technology is attracting many companies' attention. Especially, the heavy machinery industry regards it as a crucial problem since a failure of heavy machinery requires high cost and long downtime. To improve the current maintenance process, the heavy machinery industry tries to develop a methodology to predict failure in advance and to find its causes using usage data. A better analysis of failure causes requires more data so that various kinds of sensor are attached to machines and abundant amount of product usage data is collected through the sensor network. However, the systemic analysis of the collected product usage data is still in its infant stage. Many previous works have focused on failure occurrence as statistical data for reliability analysis. There have been less works to apply product usage data into root cause analysis of product failure. The product usage data collected while failures occur should be considered failure cause analysis. To do this, this study proposes a methodology to apply product usage data into failure cause analysis. The proposed methodology in this study is composed of several steps to transform product usage into failure causes. Various statistical analysis combined with product usage data such as multinomial logistic regression, T-test, and so on are used for the root cause analysis. The proposed methodology is applied to field data coming from operated locomotive and the analysis result shows its effectiveness.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.887-898
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• 2016

The purpose of this study is to improve the learning ability of probability/statistics for H/W majors. Firstly, we developed a teaching method coupling probability/statistics with programming and multimedia signal processing courses that are opened in the H/W major curriculum. By use of its teaching-learning, we tried to verify the effectiveness on the improvement of learner's academic achievement and then analyze its educational efficiency through the regression analysis. Secondly, by analyzing the surveys and the statistical results of the education cases, we proposed a management plan on efficient teaching-learning in order to cultivate the learning ability of probability/statistics at a future time. Lastly, we concluded that probability/statistics is a required course of learners so as to contribute for the advanced technical development and the enhanced competitiveness in the field of the H/W.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.208-211
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• 2016

Device-to-Device communication(D2D) enables devices in proximity to communicate directly without going through the network infrastructure. In particular, D2D communications in a cellular network can improve the spectral efficiency by allowing the reuse of cellular resources. However, it is not easy to maintain the channel quality of the D2D links and to protect the cellular links from the D2D interferences, since the resource allocations for the cellular users will change with time due to the time-varying nature of the cellular channels. To mitigate the performance degradation of D2D links, we propose to exploit unlicensed bands as auxiliary resources when the D2D links share the uplink cellular resources. The effectiveness of the proposed scheme is verified through simulations.

• Korean Journal of Social Welfare
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• v.47
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• pp.272-309
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• 2001

It is a recent trend to emphasize community services for the rehabilitation of the mentally ill. However, it is also necessary to provide social work services for those living in the institutions, who is the most underprivileged in our society. To deal with interpersonal skill deficits which is one of the main characteristics of the mentally ill, social skills programs are being utilized, usually in the communities, but not in the institutions. Therefore, the objective of this study is to develop and evaluate institution-relevant program for the improvement of assertiveness, which is the basic ability among the interpersonal skills, and self-esteem, which is the emotional basis of assertiveness. Because there has been little literature on such a program, a preliminary program had been implemented in order to include the peculiarities of the life in the institutions on the main program. The evaluation of the program effect was done by pretest-post test control group design, and its results are as follows. Firstly, in regard to program effectiveness, the pre and post test showed that self-esteem improved in a statistically meaningful way, but that assertiveness did not so. However, the staff verified the improvement of the group members' assertiveness to some degree in their actual lives. Secondly, in regard to the group process, the group interaction improved in a statistically meaningful way between 2nd and 5th session, and the improvement maintained till the program termination. Also the group members evaluated the program as helpful in their everyday lives. Therefore it can be said that the result of this program is encouraging. In light of this, several suggestions were made: utilizing more dynamic techniques in the program; developing the advanced level of the program; making an effort to change environmental structures as well as individuals; applying this kind of program to another living facilities such as those for the homeless or handicapped.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.609-614
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• 2014

Cerebellar ataxia is a steadily progressive neurodegenerative disease associated with loss of motor control, leaving patients unable to walk, talk, or perform activities of daily living. Direct motor instruction in cerebella ataxia patients has limited effectiveness, presumably because an inappropriate closed-loop cerebellar response to the inevitable observed error confounds motor learning mechanisms. Recent studies have validated the age-old technique of employing motor imagery training (mental rehearsal of a movement) to boost motor performance in athletes, much as a champion downhill skier visualizes the course prior to embarking on a run. Could the use of EEG based BCI provide advanced biofeedback to improve motor imagery and provide a "backdoor" to improving motor performance in ataxia patients? In order to determine the feasibility of using EEG-based BCI control in this population, we compare the ability to modulate mu-band power (8-12 Hz) by performing a cued motor imagery task in an ataxia patient and healthy control.

• Journal of the HCI Society of Korea
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• v.7 no.2
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• pp.11-16
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• 2012

R&D Strategic Planning plays a crucial role in determining success or failure of R&D. However, current automatic services for supporting the purpose merely provide fragmentary quantitative/qualitative analytics, and force domain experts to carry out further manual analysis by themselves. Thus, this study aims at automatically supporting R&D strategic planning with efficiency and effectiveness. To achieve the goal, we design major services in the viewpoint of the relationship between technology and R&D actor, which are essential elements in R&D. 'Trends and Predictions', 'Technology Levels', 'Relationship Paths', 'Roadmaps', and 'Competitors and Collaborators' services were designed and implemented on about 15 millions papers and patents. Future works will include the support of higher level in the hierarchy of strategic intelligence.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.424-429
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• 2014

This paper investigates the problem of synchronization of the Pehlivan chaotic system based on sliding mode control and GA. For this, a brief overview of the Pehlivan chaotic system is given. Then, the conventional sliding mode control technique is described and a synchronization method using GA strategy is proposed. The proposed method is that the GA searched the parameters including sliding plane and control gains) selected by the designer in the sliding mode control are searched optimally through the GA. The GA in the MATLAB Toolbox was used and simulation work is shown to illustrate the effectiveness of the synchronization schemes for the chaotic system.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.818-823
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• 2016

Millimeter wave (mm-wave) communication systems provide high data rates owing to the large bandwidths available at mm-wave frequencies. Recently, analogue and digital combined beamforming, namely "hybrid beamforming" has drawn attentions owing to its ability to realize the required link margins in mm-wave systems. Taking into account the radio frequency (RF) hardware limitations, such as the analogue phase shifter gain constraint and the low resolution of the phase controller, we introduce an uplink hybrid beamforming system that includes discrete Fourier transform (DFT) based "fixed" analogue beamforming. We adopt a zero-forcing (ZF) multiple-input multiple-output (MIMO) equalizer to eliminate the uplink inter-user interferences. Moreover, to improve the sum-rate performances, we propose a transmit beam selection algorithm which makes the uplink effective channels, i.e., the beamformed channels, become near orthogonal. The effectiveness of the proposed beam selection algorithm was verified through numerical simulations.

• Journal of The Korean Association of Information Education
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• v.13 no.2
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• pp.159-168
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• 2009

This study is a project case research on PVR-based e-book systems for the cultural property learning effectively. In this study, we designed and implemented the systems and contents using a photographic virtual reality technique. This system could provide the students an effectiveness of virtual experience such as a student is at place that has the cultural property. Moreover we developed the educational contents in image DB. We also converted these contents into e-book typed contents that the students easily searched and used the system in class. This systems were applied the students in elementary school. As the result of applying, we found that the PVR-based e-book systems were more effective than plain web-based systems. This study will give advanced education environment to students as well as teachers in future.

• Tuberculosis and Respiratory Diseases
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• v.38 no.2
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• pp.93-98
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• 1991

A clinical trial was made on 76 patients with pulmonary tuberculosis to determine the effectiveness and acceptibility of 6 month 2SHRZ/4HR antituberculosis regimen. Out of 76 patients, 13 patients (17.1%) dropped out and 11 patients (14.5%) were excluded due to drug resistance. In 3 patients (3.9%), regimen was changed due to adverse effects. Treatment failure rate was 2.0% in 50 patients. One patient, who had far advanced lesion, was treated longer than 6 months due to failure of sputum conversion. The most common adverse effect was arthralgia, which was controlled by the administration of allopurinol and nonsteroidal anti-inflammatory drug. In conclusion, 2SHRZ/4HR for 6 months was effective regimen in treating the newly-diagnosed patients with tuberculosis, but change of the regimen and duration might be carefully considered by the severity of the lesion and adverse effect of the drug But further study will be needed to evaluate not only the efficacy and efficiency of 6 month chemotherapy but also relapse rates.