• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.204-207
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• 2005

We discuss two possibilities of using femtosecond pulse lasers as a new interferometric light source fer enhanced precision surface profile metrology. First, a train of ultra-fast laser pulses yields repeated low temporal coherence, which allows performing unequal-path scanning interferometry that is not feasible with white light. Second, high spatial coherence of femtosecond pulse lasers enables to test large size optics in non-symmetric configurations with relatively small size reference surfaces. These two advantages are verified experimentally using Fizeau and Twyman-Green type scanning interferometers.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.406-407
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• 2012

Texture transfer is a NPR technique for expressing various styles according to source (reference) image. By late 2000s, there are many texture transfer researches. But video base researchers are not active. Moreover, they didn't use important feature like directional information which need to express detail characteristics of target. So, we propose a new method to generate texture transfer animation (using video) with directional effect for maintaining temporal coherence and controlling coherence direction of texture. For maintaining temporal coherence, we use optical flow and confidence map to adapt for occlusion/disocclusion boundaries. And we control direction of texture for taking structure of input. For expressing various texture effects according to different regions, we calculate gradient based on directional weight. With these techniques, our algorithm can make animation result that maintain temporal coherence and express directional texture effect. It is reflect the characteristics of source and target image well. And our result can express various texture directions automatically.

• Journal of the Optical Society of Korea
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• v.14 no.1
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• pp.49-54
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• 2010

In this study, the use of a continuous-wave (CW) supercontinuum (SC) seeded by an erbium-doped fiber's amplified spontaneous emission (ASE) for optical-coherence tomography imaging is experimentally demonstrated. It was shown, by taking an in-depth image of a human tooth sample, that due to the smooth, flat spectrum and long-term stability of the proposed CW SC, it can be readily applied to the spectral-domain optical-coherence tomography system. The relative-intensity noise level and spectral bandwidth of the CW SC are also experimentally analyzed as a function of the ASE beam power.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2771-2779
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• 2018

The recent financial crises cause the co-movement and transmit the risk across different markets and assets. It is well known that market fear affects the quality of credit in the financial markets. In this context, this study examines the co-movement between the volatility index (VIX) of the Chicago Board Options Exchange (CBOE), or VIX, and six emerging countries' credit default swaps (CDSs), by implementing wavelet coherence. Our research aims at revealing whether the VIX can be used to hedge against the bubble behavior of the CDS market in different investment holding periods (short-run, medium-run, and long-run), as well as whether either market can be used to manage and hedge overall market downside risks. The wavelet coherence results show a high degree of co-movement between the VIX and CDS during the 2007-2009 global financial crisis, across the 16-64 weeks' frequency band. In addition, we observe that the positive correlation between the VIX and the CDS markets, implying that the market turmoil intensifies the co-movement between the VIX and CDS markets.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.365-374
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• 2022

Mining activity causes environmental pollution and geological hazards such as ground subsidence or landslide of which continuous monitoring is necessary. In this study, the activity on the Fushun West Open-Pit Mine (FWOPM), one of the largest open-pit coal mines in Asia located in Fushun, Liaoning Province, China, was analyzed by using a time-series Sentinel-1 InSAR coherence dataset. By using the difference between the two Digital Elevation Models (DEM) of the area, it was possible to confirm that there was a stockpiling activity in the western area of the FWOPM while excavation activity in the eastern area. By using RGB composite images using the yearly-averaged InSAR coherence images, the activity of the mine was confirmed by period, which was confirmed by Google Earth optical images. As a result, it was possible to confirm three landslides and the related activities on the northwest slope and the dumping activity on the west slope of FWOPM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.43-44
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.202-203
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.358-359
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• 2004

• Journal of Korean Academy of Nursing
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• v.36 no.6
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• pp.983-991
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• 2006

Purpose: The purpose of this study was to identify the relationship among quality of life, family coherence, family hardiness, and family resources of the family care-giver caring for a cancer patient. Method: Data was collected by questionnaires from 137 families with a cancer patient at a General Hospital and Government Cancer Hospital. Data was analyzed using descriptive statistics, pearson correlation coefficients, and stepwise multiple regression. Results: The score of quality of life showed a significant positive correlation with the score of the level of family sense of coherence, family hardiness, and family resources. The most powerful predictor of quality of life was sense of coherence and the variance was 30%. A combination of sense of coherence and family resources account for 34 % of the variance in quality of life of the family care-giver caring for a cancer patient. Conclusion: The results showed that family sense of coherence, hardiness, and family resources were significant influencing factors on the quality of life of the family care-giver caring for a cancer patient.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.425-434
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• 2020

Practical non-synoptic fluctuating wind often exhibits nonstationary features and should be modeled as nonstationary random processes. Generally, the coherence function of the fluctuating wind field has time-varying characteristics. Some studies have shown that there is a big difference between the fluctuating wind field of the coherent function model with and without time variability. Therefore, it is of significance to simulate nonstationary fluctuating wind field with time-varying coherent function. However, current studies on the numerical simulation of nonstationary fluctuating wind field with time-varying coherence are very limited, and the proposed approaches are usually based on the traditional spectral representation method with low simulation efficiency. Especially, for the simulation of multi-variable wind field of large span structures such as transmission tower-line, not only the simulation is inefficient but also the matrix decomposition may have singularity problem. In this paper, it is proposed to conduct the numerical simulation of nonstationary fluctuating wind field in one-spatial dimension with time-varying coherence based on the wavenumber-frequency spectrum. The simulated multivariable nonstationary wind field with time-varying coherence is transformed into one-dimensional nonstationary random waves in the simulated spatial domain, and the simulation by wavenumber frequency spectrum is derived. So, the proposed simulation method can avoid the complicated Cholesky decomposition. Then, the proper orthogonal decomposition is employed to decompose the time-space dependent evolutionary power spectral density and the Fourier transform of time-varying coherent function, simultaneously, so that the two-dimensional Fast Fourier transform can be applied to further improve the simulation efficiency. Finally, the proposed method is applied to simulate the longitudinal nonstationary fluctuating wind velocity field along the transmission line to illustrate its performances.