• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.381-388
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• 2012

Purpose: In this study, the changes in the shape of silicone hydrogel lenses, dryness of lens and objective/ subjective symptoms that could be induced by repeating dryness of lens and objective/subjective symptoms were investigated. Methods: After drying and rehydrating of silicone hydrogel lenses with different lens material and thickness for 4 times, their overall diameters and base curves were compared. Subjective symptoms, non-invasive tear break-up time (NIBUTs) and blinking rate were evaluated after wearing dehydrated silicone hydrogel lens. Results: Overall diameter and base curve increased in all tested silicone hydrogel lenses by repeating dryness and rehydration. The degree of change in over all diameter and base curve were variable on the material. There were irregular change of lens parameters in thicker lens. When the subjects wore silicone hydrogel lenses after drying and rehydrating, their NIBUTs were decreased and blink rates were increased regardless of lens material or thickness. In addition, repetitive drying of silicone hydrogel lenses affected the lens fitting. Therefore, subjective symptoms such as itching, pain, irritation, foreign body sensation, dryness tended to be increased. Conclusions: The results obtained from the study may suggest to develop durable silicone hydrogel contact lenses against dry environment since the changes in parameters of silicone hydrogel lens and the subjective discomfort were observed after repetitive drying and rehydration.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.37-45
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• 2012

Purpose: The change of alignment between RGP lens and cornea according to the lens design was investigated by comparing the areas of fluorescein pattern in central and peripheral regions analyzed by astigmatic degree and corneal type when spherical and aspherical RGP lenses fitted in alignment. Methods: The fluorescein patterns of 90 eyes (19-30 years, $25.12{\pm}3.52$) having with-the-rule astigmatism were analyzed after spherical and aspherical RGP lenses fitted in alignment. Then, their fluorescent areas in central and peripheral regions were calculated and compared for the quantitative evaluation. Results: The case showing concordant base curve between spherical and aspherical RGP lenses in alignment fitting was 72% however, the possibility to have same base curves between spherical and aspherical RGP lenses in alignment fitting was to be less in the case of symmetric bowtietyped cornea and high astigmatism. The fluorescent area in peripheral region of aspherical RGP lens in alignment fitting was smaller than it of spherical RGP lens. Peripheral fluorescent areas in both RGP lenses decreased according to the increase of astigmatic degree and peripheral area in symmetric bowtie-typed corea was smaller than round-typed cornea's peripheral area. In the case of same astigmatic degree, peripheral fluorescent area of aspherical RGP lens was smaller in both corneal types. Conclusions: The results above suggest the changing degree in the alignment between RGP lens and cornea can be varied according to lens design, corneal astigmatism and corneal type. Thus, the results obtained from the quantitative analysis of the alignment between lens design and cornea may be used as the basic information about the establishment of guidelines for RGP lens fitting, the development of proper lens design, and different tear volume in partial regions.

• Journal of Astronomy and Space Sciences
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• v.10 no.2
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• pp.123-145
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• 1993

UBVRi photometry of Algol was carried out from December of 1988 to March of 1991 at Chungbuk National University Observatory and a total of 3465 observations in U, B, V, R, I were obtained. Three times of primary minimum light of JDH el 2447898.0938, JEH el 2448265.1205 and JDH el 2448288.0598, and two secondary minimum light of JDH el 2447808.1014 and JDH el 2448275.146 were determined from our observations. We analyzed simultaneously the UBVRI light curves of the Algol system with the Wilson-Devinney method for the determination of the photometric parameters. Indivisual masses for the 3 components of Algol are derived as $m_1$=3.36, $m_2$=0.76, $m_3$=1.6 in solar mass and radii as $R_1$=2.97, $R_2$=0.76 in solar radinus using i=$82.{\circ}47$, q=0.227, $r_1$=0.2102, $r_2$=0.2512 of our solution and some parameters of the spectroscopic solution of Hill et al. (1971). Our results is simiar to those reported by Kim (1989). The temperature of Algol C, $T_3$=8800 was obtained by means of fitting $l_1$, $l_2$, and $l_3$ of five colors to Planckian curve, and $R_3$=$1.6R_\odot$ is derived from its result. It is believed that its semidetached configuration of Algol A and B is the consequence of case B mass transfer. According to its location in a mass-radius diagram. Algol b may have evolved significantly in its Hburnning phase.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.273-281
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• 2010

In this paper, we propose an automatic segmentation method of the endo- and epicardial boundary by using ray-casting profile based on intensity distribution and gradient information in CT images. First, endo-cardial boundary points are detected by using adaptive thresholding and seeded region growing. To include papillary muscles inside the boundary, the endo-cardial boundary points are refined by using ray-casting based profile. Second, epi-cardial boundary points which have both a myocardial intensity value and a maximum gradient are detected by using ray-casting based adaptive gradient profile. Finally, to preserve an elliptical or circular shape, the endo- and epi-cardial boundary points are refined by using elliptical interpolation and B-spline curve fitting. Then, curvature-based contour fitting is performed to overcome problems associated with heterogeneity of the myocardium intensity and lack of clear delineation between myocardium and adjacent anatomic structures. To evaluate our method, we performed visual inspection, accuracy and processing time. For accuracy evaluation, average distance difference and overalpping region ratio between automatic segmentation and manual segmentation are calculated. Experimental results show that the average distnace difference was $0.56{\pm}0.24mm$. The overlapping region ratio was $82{\pm}4.2%$ on average. In all experimental datasets, the whole process of our method was finished within 1 second.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.770-781
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• 2021

Objective: Chemical exchange-dependent saturation transfer (CEST) MRI is sensitive for detecting solid-like proteins and may detect changes in the levels of mobile proteins and peptides in tissues. The objective of this study was to evaluate the characteristics of chemical exchange proton pools using the CEST MRI technique in patients with dementia. Materials and Methods: Our institutional review board approved this cross-sectional prospective study and informed consent was obtained from all participants. This study included 41 subjects (19 with dementia and 22 without dementia). Complete CEST data of the brain were obtained using a three-dimensional gradient and spin-echo sequence to map CEST indices, such as amide, amine, hydroxyl, and magnetization transfer ratio asymmetry (MTR_asym) values, using six-pool Lorentzian fitting. Statistical analyses of CEST indices were performed to evaluate group comparisons, their correlations with gray matter volume (GMV) and Mini-Mental State Examination (MMSE) scores, and receiver operating characteristic (ROC) curves. Results: Amine signals (0.029 for non-dementia, 0.046 for dementia, p = 0.011 at hippocampus) and MTR_asym values at 3 ppm (0.748 for non-dementia, 1.138 for dementia, p = 0.022 at hippocampus), and 3.5 ppm (0.463 for non-dementia, 0.875 for dementia, p = 0.029 at hippocampus) were significantly higher in the dementia group than in the non-dementia group. Most CEST indices were not significantly correlated with GMV; however, except amide, most indices were significantly correlated with the MMSE scores. The classification power of most CEST indices was lower than that of GMV but adding one of the CEST indices in GMV improved the classification between the subject groups. The largest improvement was seen in the MTR_asym values at 2 ppm in the anterior cingulate (area under the ROC curve = 0.981), with a sensitivity of 100 and a specificity of 90.91. Conclusion: CEST MRI potentially allows noninvasive image alterations in the Alzheimer's disease brain without injecting isotopes for monitoring different disease states and may provide a new imaging biomarker in the future.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.353-356
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• 2005

In this paper, the proposed $gamma({\gamma})$ line system is developed for reducing the error between non-linear gamma curve produced by a formula and result produced by hardware implementation. The proposed algorithm and system is based on the specific gamma value 2.2, namely the formula is represented by {0,1}$^{2.2}$ and the bit width of input and out data is 10bit. In order to reduce the error, the system is using least squares polynomial of the numerical method which is calculating the best fitting polynomial through a set of points. The proposed gamma line is consisting of nine kinds of quadratic equations, each with their own overlap sections to get more precise. Based on the algorithm verified by $MATLAB^{TM}$ 7.0, the proposed system is implemented by using Verilog-HDL. The proposed system has 2 clock latency; 1 result per clock. The error range (LSB) is -4 and +3. Its standard deviation is 1.287956238. The total gate count of system is 2,083 gates and the maximum timing is 15.56[ns].

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.1-11
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• 2002

A mathematical model is proposed to analyze the force; acting on the hard contact lens fitted on the cornea. The model incorporates the nonlinear equations and their numerical solution program, based on the formulations of surface tension force arising from the capillary action in the tear-film layer between the lens and cornea. The model simulates how the adhesion between lens and cornea varies according to the base curves and diameters of the lenses. When the spherical lens is fitted on the spherical cornea it is to rotate downward due to the weight of lens itself until it reaches an equilibrium position along the cornea where the counter(upward) moment caused by net force between the upper and lower portion of the periphery of lens. It is found that both the adhesion and displacement of lens along the cornea, where the gravity of lens balances the capillary-induced upward force, increases rapidly as the base curve of lens increases, i.e., as the lens gets flatter, while the increase in the diameter of lenses has resulted in the less increase in the rotation and adhesion. With the base curve and diameters of lenses being remained constant the increase in surface tension of tear film yields the increase in the adhesion between the cornea and lens while the initial rotation of lens is inversely proportional to the surface tension of the tear film.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.3 s.309
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• pp.25-33
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• 2006

This paper proposed device-independent color matching algorithm based on the 3D RGB lookup table (LUT) between mobile camera and mobile LCD (Liquid Crystal Display) to improve the color-fidelity. Proposed algorithm is composed of thee steps, which is device characterization, gamut mapping, 3D RGB-LUT design. First, the characterization of mobile LCD is executed using the sigmoidal function, different from conventional method such as GOG (Gain Offset Gamma) and S-curve modeling, based on the observation of electro-optical transfer function of mobile LCD. Next, mobile camera characterization is conducted by fitting the digital value of GretagColor chart captured under the daylight environment (D65) and tristimulus values (CIELAB) using the polynomial regression. However, the CIELAB values estimated by polynomial regression exceed the maximum boundary of the CIELAB color space. Therefore, these values are corrected by linear compression of the lightness and chroma. Finally, gamut mapping is used to overcome the gamut difference between mobile camera and moible LCD. To implement the real-time processing, 3D RGB-LUT is designed based on the 3D RGB-LUT and its performance is evaluated and compared with conventional method.

• Food Science of Animal Resources
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• v.28 no.2
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• pp.187-195
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• 2008

The purpose of this study was to establish proper shipping weight and backfat thickness by applying the growth model to backfat thickness, measured by means of not only body weight, but also ultrasonography, and predicting the changes by age. Three breeds, i.e. Duroc, Landrace, and Yorkshie, were analyzed, and the Gompertz, logistic, and Von Bertalanffy model were used for inference with the parameter of the growth model being sex. As a result, both body weight and backfat thickness showed different growth curve parameters and characteristics at inflection points depending on model selection and sex. As for backfat thickness, in estimating the inflection point, unlike the case of body weight, the inflection ages of the boars of the Duroc breed was earlier than that of sows, whereas the inflection ages of the sows of the Landrace and Yorkshire breeds was earlier than that of boars. More than anything else, in the analysis of the changes in backfat thickness according to body weight, as the body weight reached 145kg, the backfat thickness showed much variation as great as 1.7-3.2 cm in each breed and sex. In addition, unlike the other breeds, the boars of the Landrace breed showed an exponential type of relationship between body weight and backfat thickness. As they grow to become 100 kg or heavier, abrupt change in back fat thickness was confirmed. If the growth of body weight and backfat thickness is understood and the genetic relationship is taken advantage of like this, it would be possible to set desired body weight and backfat thickness, and thus help effectively set the shipping time. If not only the phenotype, but also genetic parameters about growth characteristics are estimated and analyzed additionally, more effective data can be generated.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.79.2-79.2
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• 2012

SN 2011fe (also known as PTF 11kly) is a Type-1a supernova that appeared in M101, 2011 August. Being only 6.4 Mpc away, this supernova has been intensively observed by various facilities in the world. We monitored this supernova in UBVRI, grizY, and ZYJHK-bands using SNUO, LOAO, SOAO, CQUEAN/McDonald, UKIRT telescopes, and small telescopes in Korea and Mongolia. The monitoring observation is still ongoing, and the light curve has been accumulated over a year. We present the results of the long-term monitoring observation, together with a light-curve fitting result. We will also discuss our findings in terms of the usefulness of Type-Ia supernovae as a distance indicator.