• Journal of The Korean Astronomical Society
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• v.49 no.5
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• pp.209-223
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• 2016

We present analyses of ~1250 variable sources identified in a 20 square degree field toward NGC 2784 by the KMTNet Supernova Program. We categorize the variable sources into three groups based on their B-band variability. The first group consists of 31 high variability sources with their B-band RMS variability greater than 0.3 magnitudes. The second group of medium variability contains 265 sources with RMS variability between 0.05 and 0.3 magnitudes. The remaining 951 sources belong to the third group of low variability with an RMS variability smaller than 0.05 magnitudes. Of the entire ~1250 sources, 4 clearly show periods of variability greater than 100 days, while the rest have periods shorter than ~51 days or no reliable periods. The majority of the sources show either rather irregular variability or short periods faster than 2 days. Most of the sources with reliable period determination between 2 and 51 days belong to the low-variability group, although a few belong to the medium-variability group. All the variable sources with periods longer than 35 days appear to be very red with B - V > 1.5 and V - I > 2.1 magnitudes. We classify candidates of 51 Cepheids, 17 semi-regular variables, 3 Mira types, 2 RV(B) Tauri stars, 26 eclipsing binary systems and 1 active galactic nucleus. The majority of long-term variables in our sample belong to either Mira or semi-regular types, indicating that long-term variability may be more prominent in post-main sequence phases of late-type stars. The depth of the eclipsing dips of the 26 candidates for eclipsing binaries is equivalent to ~0.61 as the average relative size of the two stars in the binary system. Our results illustrate the power of the KMTNet Supernova Program for future studies of variable objects.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.479-482
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• 2004

This paper proposes a new framework for variability analysis in QFD. The proposed framework considers the uncertainty of the information contained in the house of quality chart and analyzes the variability resulting in the outcome. A new framework provides a dominance index and a difference index for each pairwise ECs. The indices are helpful to evaluate priorities of each pairwise EC.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.163-167
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• 2002

Autonomic nervous system play an important role of keeping our health as balancing homeostasis. But the abnormality of these abilities makes our presence be feeble. To obtain these information of body which helps for us to decide whether one is healthy or not, based on the study of Heart Rate Variability. In this paper, we presented HRV model and its processing steps to extract some information of human body. After that, some experimental results are presented in time-domain and frequency-domain.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.207-215
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• 1993

With the aid of finite element method, this paper deals with the problem of structural response variability of transmission tower subjected to the spatial variability of material properties, Young's modulus herein. The spatial variability of material property are modeled as two-dimensional stochastic field which has an isotropic auto-correlation function. Response variability has been computed based on two numerical techniques, such as the Neumann expansion method in conjunction with the Monte Carlo simulation method. The results by these numerical methods are compared with those by the deterministic approach.

• Journal of the Korean Data and Information Science Society
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• v.17 no.3
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• pp.991-997
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• 2006

Recently, Liu (2005) proposed a special type of weighting function under a given preference index level with the minimal variability similar to the minimal variability OWA operator weights problem proposed by Fuller and Majlender (2003). He solved this problem using a result of classical optimal control theory. In this note, we give a direct elementary proof of this problem without using any known results.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.1-54.1
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• 2016

Multi-wavelength variability is a staple of active galactic nuclei (AGN). Optical variability probes the nature of the central engine of AGN at smaller linear scales than conventional imaging and spectroscopic techniques. Previous studies have shown that optical variability is more prevalent at longer timescales and at shorter wavelengths. Intra-night variability can be explained through the damped random walk model but small samples and inhomogeneous data have made constraining this model hard. To understand the properties and physical mechanism of intra-night optical variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Using KMTNet, we aim to study the intra-night variability of ~1000 AGN at a magnitude depth of ~19mag in R band over a total area of ${\sim}24deg^2$ on the sky. Test data in the COSMOS, XMM-LSS, and S82-2 fields was obtained over 4, 6, and 8 nights respectively during 2015, in B, V, R, and I bands. Each night was composed of 5-13 epoch with ~30 min cadence and 80-120 sec exposure times. As a pilot study, we analyzed data in the COSMOS field where we reach a magnitude depth of ~19.5 in R band (at S/N~100) with seeing varying between 1.5-2.0 arcsec. We used the Chandra-COSMOS catalog to identify 166 AGNs among 549 AGNs at B<23. We performed differential photometry between the selected AGN and nearby stars, achieving photometric uncertainty ~0.01mag. We employ various standard time-series analysis tools to identify variable AGN, including the chi-square test. Preliminarily results indicate that intra-night variability is found for ~17%, 17%, 8% and 7% of all X-ray selected AGN in the B, V, R, and I band, respectively. The majority of the identified variable AGN are classified as Type 1 AGN, with only a handful of Type 2 AGN showing evidence for variability. The work done so far confirms there are more variable AGN at shorter wavelengths and that intra-night variability most likely originates in the accretion disk of these objects. We will briefly discuss the quality of the data, challenges we encountered, solutions we employed for this work, and our updated future plans.

• Journal of Acupuncture Research
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• v.25 no.2
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• pp.189-197
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• 2008

Objectives : This study was performed in order to investigate the effectiveness of electromyography and the Heart Rate Variability(HRV) test as prognosis factors, and to clarify correlation between Electromyography and the Heart Rate Variability test. Methods : 44 Bell's palsy patients who were graded V on the House-Brackmann scale and underwent HRV and EMG testing were retrospectively reviewed based on medical records. Results from both tests were analyzed via simple linear regression, and bivariate correlation analysis was performed to investigate the correlation between results from the two tests. The severity of the facial palsy at onset and at 2 weeks after treatment were evaluated with the H-B grade and Yanagihara grading system, and was converted into improvement scores. Results : Mean axonal loss according to electromyography showed a statistically significant correlation in predicting peripheral facial palsy improvement(p<0.01). HR, SDNN, TP, LF, HF, VLF, and LF/HF ratio on the Heart Rate Variability test showed no significant correlation in predicting peripheral facial palsy improvement. Mean axonal loss determined by electromyography, and HR, SDNN, TP, LF, HF, VLF, and LF/HF ratio recorded with the Heart Rate Variability test was analyzed with the bivariate correlation analysis method. Mean axonal loss and SDNN showed a statistically significant correlation(p<0.01) Conclusions : The Heart Rate Variability test has no statistical significance in predicting peripheral facial palsy improvement. SDNN has a statistically significant correlation with mean axonal loss as determined by electromyography.

• Journal of the Korean housing association
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• v.26 no.4
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• pp.75-82
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• 2015

Although the government has revised the child welfare act, institutionalized the establishment of local children's centers, and given financial support for them, there are a number of problems with respect to their operation. Specifically, one of main problems is their limited space. Diverse problems that go with the arrangement of limited space and usability have occurred, however there are only a few strategies to use limited space flexibly. This study assumed variability as one of the methods to solve spatial problems. As a basic research for the assumption, Analyzing the variable method and characteristics of domestic and foreign child-care facility guidelines was performed trying to take advantage of as a basic data in order to seek a variable scheme of local children centers' indoor space. For this purpose, study analysed the methods and characteristics of variability centering on aspects related to variability which are environmental design elements required by local children's centers as suggested in previous studies. The results are as follows. First, the variability of space should be planned according to activity and time, and consider the methods of division, storage, and other facilities necessary. Second, methods of variability in space can be classified into creating areas and structures that are variable. Third, as a result of analysing the environmental design elements required by local children's centers, this study discovered the following characteristics: multi-purpose usability through a combination of variable devices, transition through a variable space medium and setting up areas and expansion of indoor variability assuming usability through internal and external connections.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.3
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• pp.51-60
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• 2015

Traceability targets provision of information to stakeholders required for analyzing impacts among artifacts due to changes. Unlike single product development, in software product line developing the family of products the complexity of maintaining and managing traceability between two life cycles, domain and application engineering is so high. Accordingly, variability traceability management approach centred on orthogonal variability model that manages variability separated from development artifacts has been conceptually proposed, but its efficiency has not verified yet. This paper verifies whether orthogonal variability model based traceability can provide required traceability through an example. As the results, the OVM-based variability tracing method supports well to narrow down artifacts affected by the changes. However, the method does not support tracing the exact artifacts or exact part of an artifact affected by the change.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.1076-1085
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• 2006

It is difficult to design a component to satisfy several domain requirements and almost impossible to support a specific business logic completely. To satisfy this requirement, there need white box components rather than black box components. So, in this paper, we propose the variability design technique and the customization technique that can support the various requirements of domains. The initial variability of the component is designed at the CD (component development) phase and the customization technique is used for further application of the variability. In the paper, the behavior variability design and customization techniques are used for altering component behavior. As the components that have been developed using the variability technique can easily be re designed during the development of the applications, the variability of the components can be generalized further.