• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1251-1260
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• 2018

High-quality sea-ice surface models generated from aerial images can be used effectively as field data for developing satellite-based remote sensing methods but also as analysis data for understanding geometric variations of Arctic sea-ice. However, the lack of texture information on sea-ice surfaces can reduce the accuracy of image matching. In this paper, we analyze the performance of matching cost functions for homogeneous sea-ice surfaces as a part of high-quality sea-ice surface model generation. The matching cost functions include sum of squared differences (SSD), normalized cross-correlation (NCC), and zero-mean normalized cross-correlation (ZNCC) in image domain and phase correlation (PC), orientation correlation (OC), and gradient correlation (GC) in frequency domain. In order to analyze the matching performance for texture changes clearly and objectively, a new evaluation methodology based on the principle of object-space matching technique was introduced. Experimental results showed that it is possible to secure reliability and accuracy of image matching only when optimal search windows are variably applied to each matching point in textureless regions such as sea-ice surfaces. Among the matching cost functions, NCC and ZNCC showed the best performance for texture changes.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.3
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• pp.29-41
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• 2010

In this study, the prediction errors of various spatial interpolation methods used to model values at unmeasured locations was compared and the accuracy of these predictions was evaluated. The root mean square (RMS) was calculated by processing different parameters associated with spatial interpolation by using techniques such as inverse distance weighting, kriging, local polynomial interpolation and radial basis function to known elevation data of the east coastal area under the same condition. As a result, a circular model of simple kriging reached the smallest RMS value. Prediction map using the multiquadric method of a radial basis function was coincident with the spatial distribution obtained by constructing a triangulated irregular network of the study area through the raster mathematics. In addition, better interpolation results can be obtained by setting the optimal power value provided under the selected condition.

• Journal of Trauma and Injury
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• v.23 no.1
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• pp.16-20
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• 2010

Purpose: High-grade (III, IV, V) renal injury may need interventional management. We investigated whether the selective embolization of the renal artery is effective for the treatment of major renal injury in comparison with emergency renal exploration. Methods: We retrospectively reviewed the medical and radiologic records of patients who underwent surgery or embolization for renal injury (Grade III, IV, V) between January 1990 and December 2007. We analyzed the change in treatment method before and after 2000, the blood pressure, the hemoglobin at the time of visit, the hospital days and the complications in patients who received surgery or embolization. Preserved renal functions of the embolized kidneys were identified by using enhanced CT. Results: Cases of surgery and embolization were 37 and 13, respectively: 5 and 4 in renal injury grade III, 17 and 6 in grade IV and 13 and 3 in grade V. Cases of surgery and embolization were 33 and 1 before 2000 and 2 and 12 after 2000, repectively: embolizations increased after 2000. No significant differences in mean diastolic pressure, hemoglobin, hospital days and complications existed between the surgery and the embolization groups (p>0.05). However, the transfusion volume was significantly smaller in the embolization group (p<0.05). One postoperative complication occurred in the surgery group. We identified the preserved renal functions of the embolized kidney by using enhanced CT. Conclusion: Embolization could be one treatment method for high-grade renal injury. Thus, we might suggest selective embolization a useful method for preserving the renal function in cases of high-grade renal injury.

• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.364-373
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• 2016

Disassembly is one of the important activities in treating with the product at the End of Life time (EOL). Disassembly is defined as a systematic technique in dividing the products into its constituent elements, segments, sub-assemblies, and other groups. We concern with a Fuzzy Disassembly Line Balancing Problem (FDLBP) with multiple objectives in this article that it needs to allocation of disassembly tasks to the ordered group of disassembly Work Stations. Tasks-processing times are fuzzy numbers with triangular membership functions. Four objectives are acquired that include: (1) Minimization of number of disassembly work stations; (2) Minimization of sum of idle time periods from all work stations by ensuring from similar idle time at any work-station; (3) Maximization of preference in removal the hazardous parts at the shortest possible time; and (4) Maximization of preference in removal the high-demand parts before low-demand parts. This suggested model was initially solved by GAMS software and then using Genetic Algorithm (GA) in MATLAB software. This model has been utilized to balance automotive engine disassembly line in fuzzy environment. The fuzzy results derived from two software programs have been compared by ranking technique using mean and fuzzy dispersion with each other. The result of this comparison shows that genetic algorithm and solving it by MATLAB may be assumed as an efficient solution and effective algorithm to solve FDLBP in terms of quality of solution and determination of optimal sequence.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.3
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• pp.43-50
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• 1984

A body form, which experiences minimum vertical wave-exciting forces in the vicinity of a prescribed wave frequency in water of finite depth, is obtained by an approximate method. Its configuration has the symmetry with respect to the vertical axis, expressed in terms of exponential functions. By distributing three-dimensional pulsating sources and dipoles on the immersed surface of the body, a velocity potential is determined and subsequently hydrodynamic forces including the 2nd-order time-mean drift forces are calculated. The dynamic behavior of the body moored in irregular waves is investigated numerically by using central difference method. Hereby irregular wave trains are simulated with examining its repeatability by comparing the resulting spectrum with original one. Numerical results indicated that the body form obtained from the present analysis possesses in general a favorable hydrodynamic characteristics in comparison with a spherical buoy and that the maximum excursion of the body can be significantly reduced by setting pre-tension of an appropriate amount in the mooring cable.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.3
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• pp.11-21
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• 2022

PURPOSE: This study examined the changes in the handgrip strength, dexterity, and hand function according to the presence or absence of gloves and types of gloves. METHODS: Seventy-six adults in their twenties (male: 24, female: 52, mean age 21.04 years) were the subjects of this study. The handgrip strength, dexterity, and hand function were evaluated with bare hands without gloves, poly gloves, and latex gloves. The handgrip strength was measured using a dynamometer, and three pinch strength tests were performed: tip pinch, lateral pinch, and three-jaw pinch. The hand dexterity was evaluated using the Minnesota manual dexterity test, and the hand function was evaluated using the Jabson-Taylor hand function test. RESULTS: There was no difference in the grip strength depending on whether the gloves were worn. The hand grip, dexterity, and hand function showed significant differences according to the type of glove. Regarding the handgrip, dexterity, and hand function, the latex glove had the best function, and the poly glove had the lowest function. CONCLUSION: There was a difference in dexterity among the hand functions but no difference in grip strength according to the type of glove. The results suggest that the use of latex gloves in daily life be recommended.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.31.2-31.2
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• 2012

We present the Yonsei Evolutionary Population Synthesis (YEPS) models for spectroscopic and photometric evolutions of simple and composite stellar populations. The models are based on the most up-to-date Yonsei-Yale stellar evolutionary tracks and BaSel 3.1 flux libraries, and provide integrated spectroscopic quantities of Lick/IDS system including high-order Balmer absorption-lines. Special care has been taken to incorporate the systematic variation of horizontal branch (HB) morphology as functions of metallicity, age, alpha-element mixture, and helium abundance of simple stellar populations. Our models for normal-helium stellar populations indicate that the realistic modeling of HB and alpha-element brings about 5 Gyr and 0.1 dex differences in age and metallicity estimations, respectively, compared to those without these effects. The HB effect does not depend on the specific choice of stellar libraries and alpha-element enhancements, and this effect is non-negligible even in the metal sensitive absorption indices, such as Mg2 and Mg b. Comparison of the models to observations reveals that the HB and alpha-element effects are critical in understanding otherwise inexplicable phenomena found in globular cluster systems in the Milky Way and nearby galaxies, including the observed bimodality of the line strengths of globular clusters in massive galaxies. In addition, we found that helium-enhanced stellar populations, which are the major sources of extreme HB stars, bring about increased FUV, NUV fluxes, and thus the model colors of those filters become extremely blue. Age dating based on the YEPS model with normal-helium stellar populations reveals that the evidence for 'downsizing' of elliptical galaxies is found not only in the local field but also in Coma cluster, and that the mean age of elliptical galaxies in Coma cluster is about 1.4 Gyr younger than the mean age of those in the local field. We also find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old GCs in the Milky Way.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.18 no.2
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• pp.129-133
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• 2007

Background and Objectives: Nasometry is an easy, noninvasive method to obtain objective data regarding the function of velopharynx. However, because articulation errors may affect the results of nasometry, the examiner should interpret the nasalance score based on appropriate speech stimuli. The purpose of this study is to examine the difference of nasalance score between glottal and oral articulations in patients with velopharyngeal insufficiency (VPI). Materials and Method: Nineteen children between 3.4 and 12.1 years of age (mean age 5.7 years) with a confirmed VPl showing hypernasality and articulation errors (glottal stops) were included. Nasalance scores were obtained for two speech patterns of glottal and oral stops. In addition, the velopharyngeal functions were analyzed in four subjects using video nasopharyngoscopy. Results: The $mean{\pm}S.D$ nasalance scores of the glottal stops and oral stops were $42.54{\pm}16.26%$ and $25.47{\pm}16.51%$ respectively (p=.000). Six of 19 patients achieved normal nasalance scores when glottal stops changed to oral stops by the trial speech therapy. Video nasopharyngoscope confirmed that large velopharyngeal gaps can be decreased into tiny gaps or complete closure when compensatory articulations were corrected for some cases. Conclusion: Compensatory articulation errors must be corrected for the reliable interpretation of the nasalance scores that are obtained in children with velopharyngeal insufficiency, which would facilitate to make a better decision for further management of these patients.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.401-410
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• 2017

Estimation of snow depth using optical image is conducted by using correlation with Snow Cover Fraction (SCF). Various algorithms have been proposed for the estimation of snow cover fraction based on Normalized Difference Snow Index (NDSI). In this study we tested linear, quadratic, and exponential equations for the generation of snow cover fraction maps using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite in order to evaluate their applicability to the complex terrain of South Korea and to search for improvements to the estimation of snow depth on this landscape. The results were validated by comparison with in-situ snowfall data from weather stations, with Root Mean Square Error (RMSE) calculated as 3.43, 2.37, and 3.99 cm for the linear, quadratic, and exponential approaches, respectively. Although quadratic results showed the best RMSE, this was due to the limitations of the data used in the study; there are few number of in-situ data recorded on the station at the time of image acquisition and even the data is mostly recorded on low snowfall. So, we conclude that linear-based algorithms are better suited for use in South Korea. However, in the case of using the linear equation, the SCF with a negative value can be calculated, so it should be corrected. Since the coefficients of the equation are not optimized for this area, further regression analysis is needed. In addition, if more variables such as Normalized Difference Vegetation Index (NDVI), land cover, etc. are considered, it could be possible that estimation of national-scale snow depth with higher accuracy.

• Journal of Biomedical Engineering Research
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• v.37 no.1
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• pp.21-30
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• 2016

Weibull distribution with two parameters, shape (k) and scale (s) parameters are used to model the fatigue failure analysis due to periodic vortex shedding of the synovial fluid in knee joints. In order to determine the later parameter, a suitable statistical model is required for velocity distribution of synovial fluid flow. Hence, wide applicability of Weibull distribution in life testing and reliability analysis can be applied to describe the probability distribution of synovial fluid flow velocity. In this work, comparisons of three most widely used methods for estimating Weibull parameters are carried out; i.e. the least square estimation method (LSEM), maximum likelihood estimator (MLE) and the method of moment (MOM), to study fatigue failure of bone joint due to periodic vortex shedding of synovial fluid. The performances of these methods are compared through the analysis of computer generated synovial fluidflow velocity distribution in the physiological range. Significant values for the (k) and (s) parameters are obtained by comparing these methods. The criterions such as root mean square error (RMSE), coefficient of determination ($R^2$), maximum error between the cumulative distribution functions (CDFs) or Kolmogorov-Smirnov (K-S) and the chi square tests are used for the comparison of the suitability of these methods. The results show that maximum likelihood method performs well for most of the cases studied and hence recommended.