• Proceedings of the KSME Conference
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• 2001.11b
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• pp.324-329
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• 2001

This experimental study concerns the characteristics of a transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure losses and skin-friction coefficients have been measured for the fully developed flow of $0.1\sim0.4%$ aqueous solution of sodium carbomethyl cellulose (CMC), respectively at inner cylinder rotational speed of $0\sim600rpm$. The transitional flow has been examined by the measurement of pressure losses to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients. The present results show that the skin-friction coefficients have the significant relation with the Rossby numbers, only for laminar regime. The occurrence of transition has been checked by the gradient changes of pressure losses and skin-friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficients due to the rotation in uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, is gradually declined for turbulent flow regime. Consequently, the critical(axial-flow) Reynolds number decrease as the rotational speed increases. Thus, the rotation of inner cylinder promotes the early occurrence of transition due to the onset of taylor vortices.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.573-579
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• 2013

Once-through helically coiled steam generator tubes subjected to external pressure are of interest because of their application to advanced small- and medium-sized integral reactors, in which a primary coolant with a relatively higher pressure flows outside the tubes, while secondary water with a relatively lower pressure flows inside the tubes. Another notable point is that the values of the mean radius to thickness ratio of these steam generator tubes are very small, which means that a thick-walled cylinder is employed for these steam generator tubes. In the present paper, the maximum allowable pressure of helically coiled and thick-walled steam generator tubes with through-wall cracks under external pressure is investigated based on a detailed nonlinear three-dimensional finite element analysis. In terms of the crack orientation, either circumferential or axial through-wall cracks are considered. In particular, in order to quantify the effect of the crack location on the maximum external pressure, these cracks are assumed to be located in the intrados, extrados, and flank of helically coiled cylinders. Moreover, an evaluation is also made of how the maximum external pressure is affected by the ovality, which might be inherently induced during the tube coiling process used to fabricate the helically coiled steam generator tubes.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.111-117
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• 2006

The improvement of energy conservation mandates decrease consumption of fossil fuels and minimize negative impacts on the environment, which originates from large cooling and heating demand. The absorption heat pump technology has a large potential for energy saving in this respect. Adsorption heat pump is a means to upgrade waste heat without addition of extra thermal energy. The increase of absorbed amount is of great importance for absorption heat pump cycle. In this study, in order to improve the performance of absorber, the absorbers of two different types have been investigated using methanol-glycerine as a working fluid. The former was tangential feed of liquid phase without spiral tube in the absorber and the latter was with spiral tube in the absorber. The latter was found to be more effective in enhancing the mass and heat transfer to increase the absorption performance.

• The Korean Journal of Malacology
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• v.26 no.2
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• pp.165-170
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• 2010

The location of the style sac and morphology of the crystalline style were described morphologically in three bivalve species (Tegillarca granosa, Mytilus galloprovincialis and Saxidomus purpuratus) which inhabited in different area. The style sac of them was connected to the posterior stomach. There was the crystalline style in the style sac. The crystalline style of three species was long circular cone of translucent gelatin form, which was hard and elastic. There was a red-yellow and spiral filament inside the crystalline style of Tegillarca granosa and Mytilus galloprovincialis. A white and long tube was located from basal portion to the end of crystalline style in Saxidomus purpuratus. RLC (relative length of crystalline style) of Tegillarca granosa, Mytilus galloprovincialis and Saxidomus purpuratus was 47.69, 48.97, 64.20% and RWC (relative weight of crystalline style) was 0.54, 0.54, 0.39%, respectively.

• Geotechnical Engineering
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• v.5 no.1
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• pp.27-34
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• 1989

This study presents a probabilistic analysis of the stability of homogeneous soil slopes during earthquakes. The stability of the slope is measured through its probability of failure rather than the customary factor of safety. The maximum horizontal ground acceleration is deterimined with Donovan and McGuire equation. The earthquake magnitude (m) is a random variable the Probability density function f(m) has been obtained with a use of Richter law. The potential failure surfaces are taken to be of an exponential shape (log-spiral) , Uncertainties of the shear strength parameters along potential failure surface are expressed by one-dimensional random field model. From a first order analysis the mean and variance of safety margin is osculated. The dependence on significant seismic parameters of the probability of failure of the slope is examined and the results are presented in a number of graphs and tables. On the base of the results obtained in this study, it is concluled that (1) the present model is useful in assessing the reliability of soil slopes under both static and seismic conditions: and (2) the probability of failure of a soil slope is greatly affected by the values of the seismic parameters that are associated with it.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4124-4129
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• 2013

This purpose of this research is to build up a prototype of bean threshing machine after three dimensional design which can be driven independently by engine and hydraulic equipments and wheels. To accomplish the functionality of bean threshing machine the cutters are placed in a swirl type on a threshing drum the thresing capability would be improved. Also a exit pipe was designed to clear the remains to solve the past problems that the normal machines had. A fan was designed to blow to send the waste only to the outside. Only clean beans will be transferred through a blowing fan wind power to exit pipe and the system was designed to help the worker to collect the beans in front of the machine. This threshing machine using independent driving engine which can provide the power to drive the system and do the threshing is the first developed technology in domestic area through the University and Industry cooperation.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.131-137
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• 2019

The purpose of this study is to draw the factors that makes the visitors decide to visit the art-museum and verifying the influence of visit determinants on recommendation intention and revisit intention. Visitors to Gwangju Museum of Art and Gwangju Biennale in Gwang-ju city were chosen for this study. Data were collected for 30 days from September 15 to October 14, 2018. A total of 350 visitors were attended in this research and finally 315 samples were used for the empirical analysis. The result of this study showed that 4 determinant factors(Escape from the ordinary, self-development, novelty, culture experience) of visiting art-museum were identified which all influences on behavioral intention(recommendation intention, revisit intention). Particularly, 'novelity' is the major factor influences on recommendation intention followed by 'escape from the ordinary' factor. Moreover, 'escape from the ordinary' factor influences the most on revisit intention among all determinants of visiting art-museum.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.826-837
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• 2021

Immunoglobulin G4-related disease (IgG4-RD) is a chronic inflammatory condition involving multiple organs, including the salivary or lacrimal glands, orbit, pancreas, bile duct, liver, kidney, retroperitoneum, aorta, lung, and lymph nodes. It is histologically characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells, storiform fibrosis, and obliterative phlebitis. In the thoracic involvement of IgG4-RD, mediastinal lymphadenopathy and perilymphangitic interstitial thickening of the lung are the most common findings. Peribronchovascular and septal thickening and paravertebral band-like soft tissue are characteristic findings of IgG4-RD. Other findings include pulmonary nodules or masses, ground-glass opacity, alveolar interstitial thickening, pleural effusion or thickening, mass in the chest wall or mediastinum, and arteritis involving the aorta and coronary artery. Radiologic differential diagnosis of various malignancies, infections, and inflammatory conditions is needed. In this review, we describe the imaging findings of IgG4-RD and the radiologic differential diagnoses in the thorax.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.525-534
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• 2017

The study aims to observe the cellular anatomical properties of Dahurian larch and Japanese larch for the species identification. In addition, other factors - the ring width, tracheid length, density, and strength - were compared and analyzed to clarify their physical and mechanical properties. To the end, three Dahurian larch trees and three Japanese larch trees by each diameter class were collected as specimens from Jeongseon-eup, Jeongseon-gun, Gangwon-do, to conduct a stem analysis. It was found that the average stand age, average diameter at breast height, and average tree height of three Dahurian larch trees and Japanese larch trees were 74 years and 51 years, 442 mm and 352 mm, and 26.1 m and 20.8 m, respectively. The cellular anatomical difference between Dahurian larch and Japanese larch can be usually found by spiral thickening, considering that it doesn't occur in Dahurian larch at all, while rarely does in the ray tracheids of Japanese larch. However, in this study, spiral thickening was not observed in the radial section of Japanese larch. The average annual growth diameters measured at 1.2 m-height of Dahurian larch and Japanese larch were 5.167 mm and 5.954 mm, respectively. Meanwhile, arboreal growth of Japanese larch was observed to be higher than that of Dahurian larch. In the physical properties test, it was measured that the latewood proportion and oven-dry density of Dahurian larch with low annual diameter growth were higher than those of Japanese larch, while the mechanical properties of Dahurian larch wood were measured 2-7% higher than those of Japanese larch wood. The data obtained from this study are expected to be used as the basic reference for species identification between Dahurian larch and Japanese larch by DNA analysis.

• Journal of Korean Society of Forest Science
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• v.78 no.2
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• pp.119-131
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• 1989

This experiment was executed to investigate and compare qualitative and quantitative anatomical features in compression wood, opposite wood, and side wood formed in a bent stem, a straight branch, and an exposed horizontal root of Korean red pine(Pinus densiflora S. et Z.). The respective four discs containing compression wood taken at 20cm interval both in stem and branch as well as a disc containing well developed compression wood from horizontal root were analyzed. Percentage of compression wood and eccentricity showed decreasing tendency with the increasing distance in height direction of stem and length direction of branch. The qualitative anatomical features of compression wood appeared to differ from those of side and opposite wood in very gradual tracheid transition from earlywood to latewood, roundish tracheid shape on cross surface, tracheid distortion at tip on radial surface, existence of intercellular space, and helical cavity in tracheid wall. And the differences in these qualitative features among the compression wood, opposite wood, and side wood became less intensive with the decreasing trends in percentage of compression wood and eccentricity. The quantitative anatomical features in compression wood also appeared to be wider in that respective widths of fusiform and uniseriate ray than those of opposite and side wood, but the heights of fusiform and uniseriate ray in compression wood were smaller than in opposite and side wood. The number of horizontal resin canal(fusiform ray) and uniseriate ray, however, showed no differences among the compression wood, opposite wood, and side wood. And the number of vertical resin canal in unit area, $4{\pi}mm^2$ of compression wood was fewer than that in opposite wood, whereas numerous vertical resin canals contained in a growth ring. These rays of compression wood seemed to be characterized by smaller height and wider width than those of opposite and side wood.