• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.119-128
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• 2006

A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 200km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, simulation of noise and vibration around the improved turnout system was performed in order to predict the generation level of noise and vibration due to passing of the tilting train through the turnout system.

• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.597-606
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• 2023

This study retrospectively analyzed the test results of 235 patients who visited a medical institution in Busan from May 2022 and February 2023 and conducted both carotid ultrasonography and blood tests. The purpose of this study was to investigate the effect on intima-media thickness and blood flow velocity by measuring the intima-media thickness and blood flow velocity through carotid ultrasonography and analyzing the factors influencing the subject's body mass index and metabolic syndrome. Correlation analysis between carotid intima-media thickness and body mass showed (p=0.000) confirming that there is a correlation. As a result Correlation analysis between blood flow velocity and body mass index (p=0.015) was found, comfirming that there was a correlation. Age (p= 0.000), fasting blood glucose (p=0.002) and alcohol consumption (p=0.006) were found to be correlated with carotid intima-media thickness. An increase in Carotid intima-media thicknesses causes an increase in events caused by cardiovascular disease. Therefore, efforts must be made to exclude factors that increase Carotid intima-media thicknesses, and it will be most important to prevent cardiovascular disease through research on various prediction methods and regular checkups.

• Science of Emotion and Sensibility
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• v.27 no.2
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• pp.81-90
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• 2024

In this study, we aimed to determine the effect on cerebral blood vessels of various stimulus intensities using transcutaneous electrical nerve stimulation (TENS). In particular, we wanted to monitor changes in blood flow and structural changes in the blood vessels in the common carotid artery (CCA) through low-intensity electrical stimulation that can cause non-perceptual sensory stimulation. Twenty-four healthy adults in their 20s participated in this study. Three stimulus intensities (below the sensory threshold, at the sensory threshold, and above the sensory threshold) were applied in random order. Changes in blood flow velocity according to the intensity of TENS stimulus were measured by placing the Doppler ultrasound transducer 1 cm below the CCA bifurcation, and the vascular structure was measured using B-mode imaging. C-mode Doppler and B-mode images were acquired before, during, and after the intervention for each stimulus, and changes in blood pressure were measured in each session. As a result, it was confirmed that peak systolic velocity (PSV) decreased significantly after the intervention in non-perceived sensory stimulation below the threshold, compared to other thresholds (p = .008). In particular, the PSV decreased by 3.04% on average compared to before stimulation (p = .011). However, there was no significant change in the CCA diameters before and after stimulation at all intensities. It was found that short-term, non-perceptual sensory stimulation was effective in reducing the blood flow rate without causing significant changes in either the blood vessel diameter or blood pressure. This change appears to be caused by a decrease in blood flow due to the effect of subtle vasodilation at non-perceptual sensory stimulation, and at stimulation intensity higher than that, the sympathetic nerves in the blood vessels are stimulated excessively and the blood vessels constrict. Therefore, this study can be rated as an important attempt to control blood flow through stimulation without such a psychological burden and sensory discomfort in the carotid area.

• Journal of KIISE
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• v.44 no.1
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• pp.78-83
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• 2017

Finding the densest subgraphs from social networks, such that people in the subgraph are in a particular community or have common interests, has been a recurring problem in numerous studies undertaken. However, these algorithms focused only on finding the single densest subgraph. We suggest a heuristic algorithm of the bottom-up type, which finds the densest subgraph by increasing its size from a given starting node, with the repeated addition of adjacent nodes with the maximum degree. Furthermore, since this approach matches well with parallel processing, we further implement a parallel algorithm on the MapReduce framework. In experiments using various graph data, we confirmed that the proposed algorithm finds the densest subgraphs in fewer steps, as compared to other related studies. It also scales efficiently for many given starting nodes.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.3
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• pp.9-18
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• 1999

In this study, Metallugical properties between Sn-3.5Ag, Sn-37Pb eutectic solders and Au/Ni/cu substrate according to time span above the melting point were investigated. A conventional reflow soldering machine wert used for this study and time span above the melting point was determined by changing peak soldering temperature and conveyor speed. As results, scallop type intermetallic compounds of $Ni_3Sn_4$ were formed at joint interface and no Cu-Sn compounds were found at all; Ni layer performed as a barrier for Cu diffusion. As the peak soldering temperature increased, thickness of the intermetallic compound layer increased; maximum thickness of the scallop-layer was 2.2$\mu\textrm{m}$. The shape of scallops were transformed from hemi-sphere type to elliptical shape with smaller size. Micro-hardness of the solder joint decreased as the eutectic structure of Sn-3.5Ag and Sn-37Pb increased.

• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.123-129
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• 2017

Morphological and ultrastructural characteristics of human hair medulla was investigated with scanning electron microscopy and transmission electron microscopy. The medulla is located in the central position of hair shaft and appear greatly variable forms which discontinuous shape arranged from hair root to apical portion according to longitudinal axis. The thickness of medulla from a single hair presented as very variable in size. The diameter of cross section of human hair medulla measured as $21{\mu}m$ and longitudinal section showed $27{\mu}m$. It grows up to 1/3 from 1/4 in diameter of human hair shaft. It appears emptied hole during separating of macrofibrils in the keratinocyte. The empty space measured $6.5{\mu}m$ in diameter as maximum size and it was filled with air.

• Journal of Korean Society of Forest Science
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• v.2 no.1
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• pp.19-28
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• 1962

Total area of bamboo groves in Korea which is limited to $37^{\circ}$ north latitude, i.e., to southern part of Chungchung-nam-do Province and Kangwon-do Province, is 3,235ha., but this country must import about 3,000 metric ton's bamboo culms from Japan every year. It may be true that the country is not so fit for economical cultivation of bamboo groves from the view point of climatic condition, but the author believes that self-sufficiency in bamboo is not impossible if some scientific method for improving bamboo groves is introduced to our primitive groves. Keeping this point in his mind the auther tried to study on the bamboo groves in the country, and as the first step set about to investigate the actual state of twenty good bamboo groves located in Cholla-nam-do Province from March, 1961 to January, 1962. This is a report on some characters of bamboo culms and growing stock with samples collected in the present investigation. 1) Numbers of bamboo culm per 0.1ha. are 1,183 in average, 1,840 in maximum and 87.5 in minimum before harvesting. 2) According to owners' saying, 1960 was such an off-year that they could hardly see any yearling bamboos in groves, but in 1961 very many new bamboos are produced as follows: the proportion of the number of yearling bamboos produced this year to that of mature bamboos (over 2 years old) is 58.7% in average; the highest 110.5% and the lowest 16.8%. 3) the average diameter of culms at eye height is 6.5cm, but the biggest diameter comes to 11.2 cm, and the average diameters of yearling and mature bamboos are 6.5cm and 6.6cm respectively. 4) Internode length records 29.4 cm in average, the shortest 21.3 cm and the longest 38.4 cm. Average internode lengths of new culms and mature culms are 27.6 cm and 29.4 cm respectively. This shows that the internode length of new culms is in the decrease to that of maturer's. 5) Through this investigation, it was found that internode length is in the influence of the exposure and density of bamboo groves, i. e., the more the dencity of bamboo groves is and the more the exposure nears the north-east, the longer the internode length becomes (see Table 7 and 8). 6) In the growing stock of bamboo groves, bundles per 0.1ha. amount to 271 sok (unit of bundle) in total average, 445 sok in maximum and 126 sok in minimum. 7) Among twenty typical bamboo groves, chosen in each County in Cholla-nam-do Province, only one passes perfectly by Veda's standard rule* prescribing the good bamboo grove, but the eight groves shown in Table 9 could be recommended as good ones in Cholla-nam-do Province, because the auther believes that those groves may be improved better, if we pay more attention to the management of them. 8) Considering that they have managed their groves carelessly and primitively, and that unfortunately their groves must have faced almost on clear felling over the entire area at the time of the Korean War, we can surely expect much more increments in bamboo groves, if we introduce some scientific methods in managing their groves.

• Journal of agriculture & life science
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• v.43 no.3
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• pp.15-26
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• 2009

This study was undertaken to determine inhibitory compounds from extracts of the softwood (larix leptolepis, Pseudotsuga menziesii) sawdust against Trichoderma spp. The sawdust of L. leptolepis and P. menziesii were hot water extracted, which were with fraction extracted organic solvents. The organic solvent extractions were carried out by n-hexane, methylene chloride, ethyl acetate. The antifungal activity of hot water extracts of L. leptolepis sawdust was determined to be 20.6% inhibition at a concentration of 1,000 ppm against Trichoderma spp. The antifungal activity of P. menziesii sawdust was outstanding about 60.3% against Trichoderma spp. The yields of the fractions of n-hexane soluble, methylene chloride soluble and ethyl acetate soluble from the hot water extract of L. leptolepis sawdust were 4.0%, 6.0% and 8.0%, repectively. However, the yields of the fractions of three solvents of P. menziesii sawdust were 8.0%, 13.0 and 14.0% correspondingly. The antifungal activity of n-hexane soluble fraction from hot water extracts of L. leptolepis sawdust was highest to about 68.5% to 79.9% against Trichoderma spp. compared to others. The antifungal activities of n-hexane soluble fraction from hot water extracts of P. menziesii sawdust showed 68.5%, 71.4%. 71.9%, 75.7% and 82.3% against T. aggressivum, T. atroviride, T. harzianum, T. koningii and T.viride, respectively. The n-hexane soluble fraction revealed much higher antifungal activity than the other fractions did. This study demonstrated that the n-hexane fraction of the hot water extracts of L. leptolepis and P. menziesii exhibited the greatest antifungal activity against Trichoderma spp.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1075-1082
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• 2016

In order to calculate the optimum installation interval between a speed hump and hump type crosswalk that are installed continuously in succession, this study examined the speed of a vehicle that passes different intervals between speed humps and hump type crosswalks from the approach section of a roundabout having a maximum speed limit of 30km/h; analyzed the effects of speed humps and hump type crosswalks installed continuously in succession on vehicle driving speed; and simulated the optimum installation height of hump type crosswalk. As a result, the following conclusion was drawn. First, it was found that the optimum interval between a speed hump and hump type crosswalk, which are the representative traffic calming techniques for reducing vehicle speed, to control vehicle speed under 30km/h is 30m. Second, as a result of comparing the deceleration of a vehicle that pass hump type crosswalks, it was found that if the installation interval is 65 m and above, a speed hump and hump type crosswalk had no effect. Therefore, it is desirable that the maximum installation interval between a speed hump and hump type crosswalk for controlling vehicle speed within a fixed road section should not exceed 65m. Third, the analysis showed that the optimum installation height of hump type crosswalk is 6-8cm in case vehicle speed at the approach section is 20km/h or lower, 8-10cm in case of 30km/h, and 10cm in case of 30km/h or higher, respectively. Fourth, even at a road section on which a speed hump and hump type crosswalk are installed, speed reduction effects may sometimes be insignificant due to a driver's studying effect, traffic conditions and so on. Thus, it is judged that speed reduction effects will be greater if several traffic calming techniques such as speed hump, chicane, and choker are applied at the same time. Therefore, in case of applying traffic calming techniques for the purpose of reducing vehicle speed in order to promote pedestrian safety, the composite application of several techniques should be considered.

• Journal of Environmental Policy
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• v.5 no.2
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• pp.1-26
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• 2006

This paper reveals Material Flow Analysis(MFA) has the possibility of reconciling the two contending theoretical viewpoints(weak sustainability v.s. strong sustainability) and thereby makes the concept of sustainability useful at operational level. For this purpose, this paper shows that the theoretical logic of MFA can be applied from national level to product level (EW-MFA, PIOT/NAMEA, LCI), and investigates the meanings and policy implications of MFA at each level.