• Imaging Science in Dentistry
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• 제49권2호
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• pp.171-176
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• 2019

The available methods for veneer evaluation are limited to clinical and radiographic examinations, which may not allow the appropriate identification of failure. In this report, we demonstrate the use of optical coherence tomography (OCT) as a noninvasive diagnostic and follow-up method to evaluate gingival recovery and the adhesive interface in aesthetic oral rehabilitation involving periodontal plastic surgery and ceramic laminate veneers. OCT was efficient for evaluating both soft and hard tissues, as well as the quality of the adhesive interface. In conclusion, OCT was found to be a promising approach for the professional evaluation of aesthetic oral rehabilitation, as it was capable of generating images that enabled the analysis of gingival recovery and the adhesive interface.

• The Journal of the Acoustical Society of Korea
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• 제25권4호
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• pp.172-177
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• 2006

Various research and development on Synthetic Aperture Sonar technique is under way to enhance bearing resolution of a SONAR system. In this paper, we estimated perturbed array shapes, and compensated distortion by using estimated away shapes and synthesized arrays in aperture domain such as an ETAM technique. As experimental data, we used the one obtained from towed array in neighboring waters of the Korean peninsula. Through simulation on data where tow-ship speed is maintained at a constant level, we confirmed that synthesis effect of increasing SNR and narrowed beam width of main lobe was consistently demonstrated for about 1 minute when coherence of target signal was maintained. Also, we showed that the synthesis effect with respect to time was constantly maintained.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제21권1호
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• pp.232-239
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• 2020

The purpose of this study was to identify the effect of stress and sense of coherence on health behavior compliance in patients with stroke. The subjects were 124 outpatients with stroke at a general hospital in Ulsan from May to July, 2019. The data were analyzed using descriptive statistics, t-test, one-way ANOVA, Scheffé test, Pearson's correlation coefficient and hierarchical multiple regression analysis by using SPSS 25.0. In the results, the health behavior compliance showed a significantly positive correlation with sense of coherence(r=.71, p<.001) and a negative correlation with stress(r=-.53, p<.001). The predictors of model 1 were gender(t=4.07, p<.001), education level(t=4.18, p<.001), and monthly income(t=-2.34, p=.021) and the statistical power was 39.6%. The predictors of model 2 were gender(t=4.65, p<.001), education level(t=43.24, p<.001), and sense of coherence(t=4.33, p<.001) and the statistical power was 60.4%. Thus, a nursing intervention program which is focused on a sense of coherence could promote health behavior compliance in patients with stroke.

• Journal of the Institute of Convergence Signal Processing
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• 제15권4호
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• pp.162-168
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• 2014

The OFDM system have been widely studied for the purpose of increasing data rate with more reliable communications in underwater channel environments. And it is possible only when the sub-carrier's bandwidth is smaller than the coherence bandwidth of channel in the underwater OFDM communication system. However, the size of the FFT for the OFDM system will be increased because the coherence bandwidth is as small as several tens of Hz in real underwater channel environments. Also, It is necessary to add a CP having a length longer than the rms delay spread of a channel. So the complexity of the system is increased and the data efficiency is reduced. Therefore, in this paper, we have studied the increase of the coherence bandwidth by adapting the beamforming technologies. To do this, we have collected data from real underwater channel environments and analyzed the coherence bandwidth when adapting the beamforming technologies. Analyzing the experimental data show that the coherence bandwidth by the beamforming technologies in underwater channel environments was greatly increased compared to that of a single sensor.

• Journal of the Institute of Electronics and Information Engineers
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• 제50권10호
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• pp.217-228
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• 2013

In this paper, the brain function in relation with human's visual attention was investigated by means of coherence and bicoherence methods. Throughout experimentation with attentional visual stimulus ERP (Event Related Potential) data and synthesized simulated data with different combinations of parameters, it is demonstrated that bicoherence and coherence can be useful to reveal the phase synchronies between different frequency bands at fixed scalp location, and between different scalp locations at fixed frequency band, respectively. Both methods are also affected by time interval from the onset, and the level of white noise added. The phase coupled relationships among ${\Theta}$, ${\delta}$, and ${\alpha}$ bands, and between frontal and central lobes were observed for attentional tasks, while those were little observable for inattentional tasks, which can show brain's functional spatio-spectral differences associated with human's attention.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제31권2A호
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• pp.110-118
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• 2006

In part-I of the paper, two sub-channel structures, either contiguous or distributed, were considered. Modeling the SNR distribution over a sub-channel as Ricean in general, the statistical chracteristics were investigated. In this part of the paper, we develop a generalized two step channel/resource allocation algorithm, which incorporates the two statistical measurements, and analyze the spectral efficiency of OFDMA in terms of average frequency utilization for the two sub-channel structures. In OFDMA with distributed structure, the key design parameter would be the sub-channel bandwidth. To give an insight into the impact on this parameter, we show in the numerical results the frequency utilization as a function of sub-channel bandwidth normalized to coherence bandwidth. As confirmed by numerical results, for contiguous sub-channel structure, we obtain the nominal multiuser diversity gain when the sub-channel bandwidth is smaller than the coherence bandwidth and lose the gain as it is getting larger.

• The Journal of the Korea Contents Association
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• 제7권3호
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• pp.176-186
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• 2007

As SAR data have the strong point that is not influenced by weather or light amount in comparison with optical sensor data, they are highly useful for temporary analysis and can be collected in time of unforeseen circumstances like disaster. This study is to extract DEM from L-band data of JERS-1 SAR imagery using InSAR and DInSAR processing techniques. As a result of analyzing the extracted coherence and interferogram images, it was shown that the DInSAR 3-pass method produces more suitable coherence values than the InSAR method. The accuracies of DEM extracted from the SAR data were evaluated by employing the DEM derived from the digital topographic maps of 1:5000 scale as reference data. And it was ascertained that baselines between antenna locations largely affect the accuracy of extracted DEM.

• Korea Journal of Hospital Management
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• 제11권3호
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• pp.42-55
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• 2006

The present study is designed to develop surveying tools to measure stressors of and social supports for Radiological Technologists which may play a role to alleviate their stresses caused from their job environments. For this purpose, an analysis of reliability by factors of personal stressors was conducted on 890 radiologists who are working at 44 general hospitals in 16 cities and provinces across the country. The results of the analysis may be summed up as follows: Six factors in 2 concerned fields turned out to be major tools for use as items of questionnaires to measure social supports for and organizational culture of Radiological Technologists. The factors determined to be applicable for survey with reliability coefficient of more than 0.7 measured by factors for internal coherence included social supports on the job(0.90), off-the-job social supports(0.81), job satisfaction(0.80), devotion for job by length of service(0.81) and emotional devotion for job(0.80), all deemed to be appropriate as survey items. In the verifying process of the results, it was found that normative devotion for job(0.61) showed lower reliability as its statistical coefficient was analyzed to be less than 0.7. It seemed, therefore, necessary to reconstruct items or re-select such ones only that can maintain internal coherence in order to analyze appropriateness of related measuring tools, or to develop new measuring tools. Although the outcomes of this study can be used to verify reliability and appropriateness of concerned concepts to assess stresses caused during the job performance of Radiological Technologists, it may be improper to adopt them to measure all types of social supports and stresses that occur generally under the job environment. It is desired, however, to compare and analyze the findings of the present study with others and to utilize them as basic data for further development of tools that can maintain internal coherence in terms of reliability and appropriateness in spite of changing social environments.

• Korean Journal of Cognitive Science
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• 제24권4호
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• pp.301-321
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• 2013

For the task of sentence ordering, this paper attempts to utilize the Entity-Grid model, a type of entity-based modeling approach, as well as Latent Semantic analysis, which is based on vector space modeling, The task is well known as one of the fundamental tools used to measure text coherence and to enhance text generation processes. For the implementation of the Entity-Grid model, we attempt to use the syntactic roles of the nouns in the Korean text for the ordering task, and measure its impact on the result, since its contribution has been discussed in previous research. Contrary to the case of German, it shows a positive result. In order to obtain the information on the syntactic roles, we use a strategy of using Korean case-markers for the nouns. As a result, it is revealed that the cues can be helpful to measure text coherence. In addition, we compare the results with the ones of the LSA-based model, discussing the advantages and disadvantages of the models, and options for future studies.

• International conference on construction engineering and project management
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.8-13
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• 2017

Nuclear power plant (NPP) constructions are large scale projects that are executed for several years, and schedule control utilizing various schedules is a critically important factor. Recently Korea independently developed the Advanced Power Reactor (APR) 1400 and is building nuclear facilities applying this new reactor type. The construction of Shin-Kori NPP (SKN) Unit 3, which adopted the APR1400, was completed and commercial operation has begun, while, SKN 4, Shin-Hanul NPP (SHN) Units 1&2, and SKN 5&6 are currently under construction. Prior to the development of the APR1400, Korea built 24 reactors and accumulated the schedule data of various reactor types which provided the foundation for schedule reduction to be possible. However, as there is no schedule development and review system established based on the standard schedule data (standard activities, durations, etc.) by reactor type, the process for developing the schedule for new builds is low in efficiency consuming much time and manpower. Also all construction data has been accumulated based on schedule activities. But because the connectivity of activities between projects is low, it is difficult to utilize such accumulated data (causes for schedule delay, causes for design changes, etc.) in new build projects. Due to such reasons, issues continue to arise in the process of developing standard schedule activities and a standard schedule for nuclear power plant construction. In order to develop a standard schedule for NPP construction, i) the development of an NPP standard schedule activity list, ii) development of the connection logic of NPP standard schedule activities, iii) development of NPP standard schedule activity resources and duration, and iv) integration of schedule data need to be performed. In this paper, an analysis was made on the coherence of schedule activity descriptions of existing NPPs by applying the probabilistic methodology on activities with low connectivity due to the utilization of the numbering system of four APR1400 reactors (SHN 1&2 and SKN 3&4).This study also describes the method for developing a standard schedule activity list and connectivity measures by extracting same and/or similar schedule activities.