• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.3
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• pp.467-476
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• 2000

An unsteady numerical simulation was performed for locally-forced separated and reattaching flow over a backward-facing step. The local forcing was given to the separated and reattaching flow by means of a sinusoidally oscillating jet from a separation line. A version of the $k-{\varepsilon}-f_{\mu}$ model was employed, in which the near-wall behavior without reference to distance and the nonequilibrium effect in the recirculation region were incorporated. The Reynolds number based on the step height (H) was fixed at $Re_H=33000$, and the forcing frequency was varied in the range $0{\leq}St_H{\leq}2$. The predicted results were compared and validated with the experimental data of Chun and Sung. It was shown that the unsteady locally-forced separated and reattaching flows are predicted reasonably well with the $k-{\varepsilon}-f_{\mu}$ model. To characterize the large-scale vortex evolution due to the local forcing, numerical flow visualizations were carried out.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.647-652
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• 2005

When a vessel passes near a channel boundary, the boundary creates forces and moments acting on the vessel. With the same reason passing of two vessels closely gives same effects to each other. The principal difference between the above two cases is that the channel boundary is long and constant shape compared to those of vessels. The interaction forces and moments between two vessels could be assumed to be functions of the longitudinal distance $chi_0$, transverse distance $y_0$ and speeds of the two vessels. Passage of one vessel close to another is important operationally from the viewpoint of replenishment at sea, avoidance of collisions and passage of two vessels in restricted channels. The authors studied the interactions between two vessels running closely and calculated safe conducting distances according to separated distances and speeds of the two vessels.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.11-16
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• 2005

When a vessel passes near a channel boundary, the boundary creates forces and moments acting on the vessel. With the same reason passing of two vessels closely gives same effects to each other. The principal. difference between the above two cases is that the channel boundary is long and constant shape compared to those of vessels. The interaction forces and moments between two vessels could be assumed to be functions of the longitudinal distance $x_0$, transverse distance $y_0$ and speeds of the two vessels. Passage of one vessel close to another is important operationally from the viewpoint of replenishment at sea, avoidance of collisions and passage of two vessels in restricted channels. The authors studied the interactions between two vessels running closely and calculated safe conducting distances according to separated distances and speeds of the two vessels.

• Journal of Ecology and Environment
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• v.40 no.2
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• pp.84-88
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• 2016

To understand the effects of habitat characteristics on the genetic diversity of Persicaria thunbergii, three sites of different environmental conditions in a water system were surveyed. Site A was the closest to the source of the water system, and there was a dam between sites A and B. Site C is located on the lowest downstream in the water system. Vegetation survey of four quadrats at each site was performed, and soil samples were collected for physicochemical analysis. Random amplification of polymorphic DNA (RAPD) analysis of ten P. thunbergii individuals at each site was conducted to calculate population genetic diversity and genetic distance among populations. Soil was sterile sand at site A, whereas loamy soil at sites B and C. A pure stand of P. thunbergii appeared at site A, while other species occurred together (such as Humulus japonicus and Phragmites australis) at sites B (Shannon-Wiener index; $H_B=0.309$) and C ($H_C=0.299$). Similar to the species diversity, genetic diversity (Nei's gene diversity; h) within population of site A ($h_A=0.2381$) was relatively lower than sites B ($h_B=0.2761$) and C ($h_C=0.2618$). However, site C was separated from sites A and B in genetic distance rather than the geographical distance (Nei's genetic distance; A~B, 0.0338; B~C, 0.0685; A~C, 0.0833).

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.200-207
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• 2003

In this paper we present a new method of measuring the relative distance of two point objects in three-dimensional space by using phase-shifting digital holography. In our system the reference beam of a spherical wave is used instead of a plane wave. The system is computer simulated and built on an optical table for experiments. It is shown from computer simulations and experiments that the relative distance can be measured without the exact information on the reference beam used in the hologram record. It is shown from experiments that the relative distance between two point objects separated by 0.5 cm in the distance of about 300 cm from the CCD can be measured with an error less than 10％.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.219-230
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• 2021

International seismic codes stipulate that adjacent buildings should be separated by a specified minimum distance, otherwise the pounding effect should be considered in the design. Recent researches proposed an alternative method (Double Difference Combination Rule) to estimate seismic gap between structures, as this method considers the cross relation of adjacent buildings behavior during earthquakes. Four different criteria were used to calculate the minimum separation distance using this method and results are compared to the international codes for five separation cases. These cases used four case study buildings classified by different heights, lateral load resisting systems and fundamental periods of vibrations to assess the consistency in results for the alternative methods. Non-linear analysis was performed to calculate the inelastic displacements of the four buildings, and the results were used to evaluate the relation between elastic and inelastic displacements due to the ductility of structural elements resisting seismic loads. A verification analysis was conducted to guarantee that the separation distance calculated is sufficient to avoid pounding. Results shows that the use of two out of the four studied methods yields separation distances smaller than that calculated by the code specified equations without under-estimating the minimum separation distance required to avoid pounding.

• Korean Journal of Poultry Science
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• v.44 no.2
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• pp.75-81
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• 2017

A total of 340 individuals from seven duck populations were studied using 24 polymorphic microsatellite (MS) markers to identify plumage colors with genetic diversity. The estimated average number of alleles (Na), polymorphic information content (PIC) value, and expected heterozygosity (He) per locus of all populations were 11.5, 0.602, and 0.635, respectively. The calculated population genetic distance (Fst), inbreeding coefficient of individuals within duck populations (Fis), and total inbreeding among populations (Fit) were 0.135, 0.105, and 0.229, respectively. Statistical analyses for each population using 24 marker combinations, revealed that the estimated average number of effective alleles (Ne), observed heterozygosity (Ho), and fixation index of inbreeding within populations (F) were 3.129, 0.505, and 0.104, respectively. The results of genetic distance and phylogenetic analysis revealed that Korean native duck populations were clearly separated from all Bangladeshi duck populations. Moreover, all populations clustered well according to their genetic distance, but could not be clearly separated according to black and white plumage colors or plumage color pattern. The combination of these 24 MS markers can be used for discrimination and determination of the genetic diversity of native duck breeds in further investigations for conservation and special development purposes.

• The Korean Journal of Nuclear Medicine
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• v.23 no.2
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• pp.189-193
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• 1989

To observe the effect of gastric filling on the images of hepatic scintigraphy, we performed hepatic scintigraphy using $^{99m}Tc-tin$ colloid in twenty patients both in the fasting state and after meal, and made the visual comparison of both images. We found that gastric filling could cause some of the following changes in individual patients. 1) In the anterior view, the distance between the liver and the spleen increased and the interlobar notch of the inferior hepatic border was obliterated. The spleen was displaced downwards, its radioactivity in the upper medial part was reduced, and its upper pole was laterally displaced. 2) In the posterior view, the left lobe of the liver was separated from the spleen and the distance between the liver and the spleen increased. 3) In the right lateral view, the notch separating the right and the left lobes of the liver was well demarcated. 4) In the left lateral view, the spleen was separated from the liver and the distance between the liver and the spleen increased. The shape of the spleen was also changed. In case of the follow-up study, above changes should make one consider the possibility of the effect of gastric filling.

• Journal of Korea Water Resources Association
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• v.48 no.5
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• pp.357-365
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• 2015

Both exponents of distance and elevation into distance-and-elevation ratio method for estimating missing rainfall data are expressed as squares together but in this study the two exponents are differently separated and analyzed. We used 326 hourly rainfall events of precipitation data during 10 years of 2004 to 2013 observed at a base station of Pyeongchang and the five neighboring index stations-Bangrim, Suju, Cheongoksan, Jinbu, Yeongwol1-in Han River basin for a case study. As a result, exponent values of distance and elevation appropriate for a topography of the site appear as 3.7 and 0.57 respectively. The exponents of distance and elevation difference need to be applied according to topographical characteristics of site where estimating missing data or interpolation are required.

• Journal of the Korean Society for information Management
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• v.34 no.1
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• pp.51-71
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• 2017

This study conducted a survey to measure recognition distance between the materials which are located separately in a children's library targeting 200 elementary school lower grade students, higher grade students, and school parents(adults). And compared recognition distance between the elements of materials of individual visitor group with multidimensional scaling and K-mean group analysis. Multidimensional Scaling (MDS) is a technique for projecting the cognitive state in space by evaluating the similarity or attribute of the analysis target. Even though it is mainly used for market diagnosis in marketing, It can also be applied to present an ideal physical layout plan by analyzing the distance. As a result of analysis, the main discoveries are as follows. First, elementary school students cognize child, baby and computer materials should be adjacent as a same group. But recognition of adults(school parents) is reflected by differing from elementary school students vastly. They cognize that computer materials should be formed as a special group separated from child and baby's materials. Second, elementary school higher graders and adults(school parents) groups also want to separate their main reading materials from baby's book, therefore They both want to secure silent reading space separating from baby. Third, as a result to confirming how this recognition distance system of materials is reflected in a real children's library through three children's libraries in Y-gu, Incheon, there is no library with structure according perfectly with a recognition system of a particular class, but a recognition system of adults and elementary school students is partially reflected because baby, child and computer materials, and baby and child materials are commonly separated and placed. It is difficult to insist that a recognition system of a visitor group, especially a recognition system of children is absolute consideration conditions in material placement of a children's library. However, understanding cognition of the user groups can be an important evidentiary factors to offer differentiated service space according to visitors and effective placement of the elements of library resources.