• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1674-1680
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• 2002

An experimental study was made of a large-scale vortical structure over a backward-facing step. The Reynolds number based on the step height was R $e_{H}$ =33,000. To recognize the large-scale vortex, three components of velocity were measured. The measurements were performed in the recirculation zone (x/H=4.0) and the reattachment zone(x/H=7.5). To measure the wall pressure fluctuations in a turbulent flow over a backward-facing step, a 32-channel microphone array was installed beneath the wall in the streamwise and spanwise directions. From the measured pressure field, the size of large-scale vortex was obtained. As a detailed study, a conditionally-averaging technique was employed to characterize the coherent structure of the large-scale vortex. To see the relationship between the flow field and the relevant spatial mode of the pressure field, the spatial box filtering (SBF) was examined. A cross-correlation between velocity and pressure fluctuations was performed to identify the structure and the length scale of the large-scale vortex.x.

• The Journal of Korean Physical Therapy
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• v.16 no.1
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• pp.183-207
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• 2004

The purpose of this study was to describe and compare the temporo-spatial gait characteristics of healthy elderly people with those osteoarthritis patients. 100 patients reported knee osteoarthritis, diagnosed at the hospital or clinic located in Daegu and Kyungbuk province and 100 normal elderly subjects were participated in this study. Temporal and spatial parameters of gait were analysed for using the computerized GAITRite system. The system integrates specific components of locomotions to provide a single, numerical representation of gait, the Functional Ambulation Performance score. Differences in gait characteristics between the two groups were examined using a correlated t-test and Pearson Correlation(p<.05). Significant differences were observed between the groups for temporal parameters(step time, double support time, stance phase, mean velocity) and spatial parameters(step length, step/extremity ratio)(p<.05). Also there was difference in the functional ambulation performance score between normal elderly subjects and knee osteoarthritis patients(p<.05). Consequently, it may help detect the abnormal gait pattern indicated the main problem in degenerative knee osteoarthritis patients as well as provide data analysing the pathokinesiologic components by comparing normal elderly.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.187-187
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• 2016

High intensity of population distribution in deltaic setting especially in Asia tends to have increased and causes coastal flood risk due to lower elevations and significant subsidence. Maximum or peak discharge of flood always causes numerous deaths and huge economic losses. New technology of spatial satellite image has been applied to analyze flood damage. In this research, the relationship of nightlight intensity associated with flood damages has been determined during 1992-2013 with spatial resolution of 30 arc sec ($0.0083^{\circ}$) which is nearly one kilometer at the equator in whole six countries along the Mekong River (i.e., China, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam). ArcGIS Hydrological Flow Length Tool has been used to determine the distance of each pixel areas from the rivers and streams. Statistical analysis results highlight the significant correlation R = 0.47 between nightlight digital number and economic damages per unit area (US$/km2) and R = 0.62 for number of affected people for unit area ($people/km^2$). The areas near by the Mekong River and its tributaries correspond to high flood damage. This spatial analysis result is going to be prestigious key information to the regions and all related stakeholders for decisions and mitigation strategies.

• Korean Institute of Interior Design Journal
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• v.25 no.4
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• pp.68-79
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• 2016

The purpose of this study is to provide a reference for stage space planning in modern theaters by analyzing and understanding stage components in terms of spatial composition, purposes, and correlation between them, and collecting various opinions from stage managers an directors. The findings are as follow: the determination of the size of proscenium arch is crucial, and it needs to be considered not only with the genre of the performance and the number of seats, but also with the size of the stage facility. The two-dimensional size of proscenium arch affects the scale of stage area in three-dimensional way; the size of main stage comes from the width of the arch, and the length of set battens comes from the stage width, and so on. The height of the arch affects the elevation of gridiron, and the height of the building itself ultimately. The number and length of the set battens are directly linked to the size of the winch room, and so is the number of the winches to the Mcc panel room. The 1st level gallery supplying power to lighting equipment needs to be wide enough for staffs to work with various equipments effectively and safely. Degree of practical usage of under-stage machinery turned out to be very low. In order to cut unnecessary waste and cost, the characteristics of the theater must get set first, and experts who know how stage works need to get involved in planning stage.

• Atmosphere
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• v.25 no.2
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• pp.339-351
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• 2015

The purpose of this study is for the fundamental understandings about building morphological parameters and aerodynamic roughness parameters of Seoul, Korea using the detailed urban geographic information datasets. Applied roughness parameter calculations are based on a digital map of buildings with lot area polygons. The quality of the developed roughness length ($z_0$) of Seoul was evaluated with densely installed 107 automatic weather stations. The correlation coefficient results between averaged wind speeds of AWS data and averaged $z_0$ is -0.303 in night and -0.398 in day (200 m radii circles case). Further $z_0$ enhancement should follow by considering other surface features such as high tree and orography of Seoul. However, this study would meet the needs to for local- or meso-scale meteorological modeling applications of Seoul. However, further studies would require for enhancing the $z_0$ applications of Seoul.

• Journal of Soil and Groundwater Environment
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• v.11 no.3
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• pp.52-58
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• 2006

Kim and Lee (2005) suggested Minimum Entropy Deconvolution (MED) to estimate the temporal sequence of the relative recharge. However this study by Kim and Lee (2005) was just related to the verification of the conceptual approach with MED. In this study, we try to characterize the applicability of MED in the case of spatially heterogeneous recharge (distance from recharge area). Simulated results were recorded with some specific sampling points. Estimated results from this study show higher than 0.8 in cross-correlation with the original recharge sequence. In addition, the physical and mathematical meanings of the applied filter length was also investigated. It was revealed that the length of filter is highly related to the spatial distance between recharge area and the monitoring site, and the apparent shape of hydraulic head change.

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.117-125
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• 2018

Recently, various building integrated wind power (BIWP) approaches have been used to produce energy by installing wind power generators in high-rise buildings constructed in urban areas. BIWP has advantages in that it does not require support to position the turbine up to the installation height, and the energy produced by the wind turbine can be applied directly to the building. The accurate evaluation of wind speed is important in urban wind power generation. In this study, a wind tunnel test and computational fluid dynamics (CFD) analysis were conducted to evaluate the wind speed for installing wind turbines between buildings. The analysis results showed that the longer the length of the buildings, which had the same height, the larger the wind speed between the two buildings. Furthermore, the narrower the building's width, the higher the wind velocity; these outcomes are due to the increase in the Venturi effect. In addition, the correlation coefficient between the results of the wind tunnel test and the CFD analysis was higher than 0.8, which is a very high value.

• Journal of The Korean Astronomical Society
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• v.50 no.3
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• pp.61-70
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• 2017

We study the angular correlation function of bright ($K_s{\leq}19.5$) Extremely Red Objects (EROs) selected in the Subaru GTO 2$deg^2$ field. By applying the color selection criteria of $R-K_s$ > 5.0, 5.5, and 6.0, we identify 9055, 4270, and 1777 EROs, respectively. The number density is consistent with similar studies on the optical - NIR color selected red galaxies. The angular correlation functions are derived for EROs with different limiting magnitude and different $R-K_s$ color cut. When we assume that the angular correlation function $w({\theta})$ follows a form of a power-law (i.e., $w({\theta})=A{\theta}^{-{\delta}}$), the value of the amplitude A was larger for brighter EROs compared to the fainter EROs. The result suggests that the brighter, thus more massive high-redshift galaxies, are clustered more strongly compared to the less massive galaxies. Assuming that EROs have redshift distribution centered at ~ 1.1 with ${\sigma}_z=0.15$, the spatial correlation length $r_0$ of the EROs estimated from the observed angular correlation function ranges ${\sim}6-10h^{-1}Mpc$. A comparison with the clustering of dark matter halos in numerical simulation suggests that the EROs are located in most massive dark matter halos and could be progenitors of $L_{\ast}$ elliptical galaxies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.698-706
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• 2013

Structural vibration induced by excitation forces under turbulent boundary layer is investigated in terms of the numerical analysis in this paper. Since the responses of structures excited by the wall pressure fluctuation(WPF) are described by the power spectral density functions, they are calculated and reviewed theoretically for finite and infinite length beams. For the use of numerical approaches, the WPF needs to be discretized but conventional finite element method is not much effective for that purpose because the WPF lose the spatial correlation characteristics. As an alternative numerical technique for WPF modelling, a wavenumber domain finite element approach, called waveguide finite element method, is examined here for infinite length beams. From the comparison between the numerical and theoretical results, it was confirmed that the WFE method can effectively and easily cope with the excitation from WPF and hence the suitable approach.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1947-1954
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• 2021

In the nuclear medicine imaging, quality control (QC) process using quadrant bar phantom is fundamental aspect of evaluating the spatial resolution. In addition, QC process of gamma camera is performed by daily or weekly. Recently, Monte Carlo simulation using the Geant4 application for tomographic emission (GATE) is widely applied in the pre-clinical nuclear medicine field for modeling gamma cameras with pixelated cadmium telluride (CdTe) semiconductor detector. In this study, we modeled a pixelated CdTe semiconductor detector and quadrant bar phantom (0.5, 1.0, 1.5, and 2.0 mm bar thicknesses) using the GATE tool. Similarity analysis based on correlation coefficients and peak signal-to-noise ratios was performed to compare image qualities for various source to collimator distances (0, 2, 4, 6, and 8 cm) and collimator lengths (0.2, 0.4, 0.6, 0.8, and 1.0 cm). To this end, we selected reference images based on collimator length and source to collimator distance settings. The results demonstrate that as the collimator length increases and the source to collimator distance decreases, the similarity to reference images improves. Therefore, our simulation results represent valuable information for the modeling of CdTe-based semiconductor gamma imaging systems and QC phantoms in the field of nuclear medicine.