• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.29-35
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• 2006

The flow patterns around multi-circular cylinders are studies, in order to obtain a global view on the structure of wave control and circulation of sea flow in coastal region. The flow force depends upon the vortex shedding exerted on the structure, especially how the vortex shedding affects the erosion when the structure sets on the sand bottom. Therefore, it is necessary that the flow pattern be hocked. In order to simulate the flow around multi-circular cylinders, the CFX and FLUENT of the computational fluid dynamics (CFD) program were used and compared with the experimental results of the flow visualization installation. The phenomena of flow around the multi-cylinders will be applied to fundamental data for predicting the flow force acting against the structure, erosion and sedimentation around cylinders in arrangement.

• Journal of the Korean Society of School Health
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• v.7 no.1
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• pp.45-55
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• 1994

The purpose of this study is to contribute to improvement of educational environment by analysing all problems related to environment around the school. To accomplish this purpose, this study was carried out by examining the problems in controlling the areas required for cleanup with 220 teachers in charging the cleanup duties of the primary and secondary schools in Taegu between June 1 and July 15, 1993 and by actually surveying the prejudical business stores around 72 primary schools between August 10 and September 20, 1993. Although most teachers answered to the questionnaires that it is necessary to cleanup the bad environment around the school, the duties of its cleanup tend not to be considered as an important matter. The teachers considered that the most prejudical business store around the school is totally the game room, and in such order as comic books' store, liquor selling shop and causing noise and pollution. 57.3% of total respondents answered that the present cleanup movements have resulted in failure mostly because of both supervising authorities' careless promotion and store owners' excessive commercial transactions. The result of actual survey in environmental and sanitary cleanup area around 72 primary schools showed that the greatest number of 1,258 prejudical stores was the video tapes shop, and then in such order as lodgings, and game rooms, while the number of prejudical store by the schools was 17.5 stores per school on the average which showed a various distribution from zero to 77 places. In general, these prejudical stores were mainly located around the schools in Jung-gu and Seo-gu areas. In addition, it was shown that the more the number of students, the more the number of the prejudical stores. In order to improve the environment around the school, it is necessary to strictly carry out the zoning system relating to the usage of land, to strongly restrict the stores without permit and abnormal stores and to establish the basis asking the city development authorities to go through the environmental evaluation. Moreover, it is absolutely required to make efforts to establish the national right sense of education, and to closely cooperate with the related authorities.

• Wind and Structures
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• v.9 no.4
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• pp.315-330
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• 2006

Flow and scalar dispersion around Cheomseongdae are numerically investigated using a three-dimensional computational fluid dynamics (CFD) model with the renormalization group (RNG) $k-{\varepsilon}$ turbulence closure scheme. Cheomseongdae is an ancient astronomical observatory in Gyeongju, Korea, and is chosen as a model obstacle because of its unique shape, that is, a cylinder-shaped architectural structure with its radius varying with height. An interesting feature found is a mid-height saddle point behind Cheomseongdae. Different obstacle shapes and corresponding flow convergences help to explain the presence of the saddle point. The predicted size of recirculation zone formed behind Cheomseongdae increases with increasing ambient wind speed and decreases with increasing ambient turbulence intensity. The relative roles of inertial and eddy forces in producing cavity flow zones around an obstacle are conceptually presented. An increase in inertial force promotes flow separation. Consequently, cavity flow zones around the obstacle expand and flow reattachment occurs farther downwind. An increase in eddy force weakens flow separation by mixing momentum there. This results in the contraction of cavity flow zones and flow reattachment occurs less far downwind. An increase in ambient wind speed lowers predicted scalar concentration. An increase in ambient turbulence intensity lowers predicted maximum scalar concentration and acts to distribute scalars evenly.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.3
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• pp.386-398
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• 1998

The present experiment is conducted to investigate heat transfer characteristics on the impinging surface with secondary flows around circular nozzle jets. The changed vortex pattern around jet affects significantly the flow characteristics and heat transfer coefficients on the impinging surface. The effects of the jet vortex control are also considered with jet nozzle-to-plate distances and main jet velocities. The vortex pattern around a jet is changed from a convective instability to an absolute instability with a velocity suction ratio of the main jet and the secondary counterflow. With the absolute instability condition, the jet potential core length increases and the heat transfer on the impinging surface is increased by small scale eddies. The region of high heat transfer coefficients is enlarged with the high Reynolds number due to increasing secondary peak values. The effect of suction flows is influenced largely with collars attached the exit of the jet nozzle because the attached collar guides well the counterflow around the main jet.

• Geomechanics and Engineering
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• v.5 no.6
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• pp.595-611
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• 2013

This paper presents a three-dimensional (3D) integrated numerical model where the wave-induced pore pressures in a porous seabed around breakwater heads were investigated. Unlike previous research, the Navier-Stokes equation is solved with internal wave generation for the flow model, while Biot's dynamic seabed behaviour is considered in the seabed model. With the present model, a parametric study was conducted to examine the effects of wave and soil characteristics and breakwater configuration on the wave-induced pore pressure around breakwater heads. Based on numerical examples, it was found that the wave-induced pore pressures at breakwater heads are greater than that beneath a breakwater. The wave-induced seabed response around breakwater heads become more important with: (i) a longer wave period; (ii) a seabed with higher permeability and degree of saturation; and (iii) larger angle between the incident waves and breakwater. Furthermore, the relative difference of wave-induced pore pressure between fully-dynamic and quasi-static solutions are larger at breakwater heads than that beneath a breakwater.

• The Korean Journal of Pain
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• v.13 no.1
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• pp.111-114
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• 2000

Pain around the posterior iliac crest area is usually attributed to disorders of the lower lumbar or lumbosacral spine. However, low back pain arising from the thoracolumbar region is common and it is very similar to low back pain of lumbosacral origin. Low back pain of thoracolumbar origin is clinically distinguished from other nonspecific low back pain syndrome. It is characterized by symptoms localized at one posterior iliac crest innervated by posterior branch of $T_{12}$ spinal nerve. Patients never complain of spontaneous pain at the thoracolumbar junction. Only localized tenderness over involved segments of thoracolumbar junction can be noted. We report two cases of posterior iliac crest pain of thoracolumbar origin which was relieved by the treatment on the thoracolumbar junction.

• Journal of Preventive Medicine and Public Health
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• v.5 no.1
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• pp.37-42
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• 1972

Mountain Wells are very important water source for the most of the climbers in Seoul area. But the facilities around the wells are not modernized to prevent from contamination of microorganism and the other pollutants. We focussed our intention on the detection of some harmful chemical ingredients and contaminants. A total of 58 wells were examined according to the Standard Methods(APHA) and the following results were obtained: 1) Among the examined 58 wells, only 10 wells were adequate to the drinking water standard, 2) 7.9mg of liberated $CO_2$ was found in the Tchun-Ho-Dong Mineral Well, 3) Chemically harmful ingredients were not found, 4) The Mountain Wells were contaminated by Coliform groups as many as 18 times than rural wells.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.3
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• pp.199-209
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• 2011

Purpose: Osteoporosis, is a major health problem for the elderly and post-menopausal women and shown to alter the properties of bone as well as impair bone healing around titanium implants in both human and animals. The objective of this study was to examine the effect of LIPUS with adipose-derived stem cells on the healing process around a titanium implant in rats with osteoporosis. Methods: Sixteen osteoporosis-induced rats were divided into two groups: an adipose-derived stem cell injected with Low Intensity Pulsed Ultrasound (LIPUS) application group and a control group. Titanium screw implants (diameter, 2.0 mm: length, 3.5 mm, Cowell Medi, Korea) were placed into both tibia of 16 rats, on 8 rats as the control group and the other 8 rats as the experimental group. Rats were sacrificed at different intervals from 1, 2, 4 and 8 weeks after implantation for histopathologic and immunohistochemical analyses. Results: Histopathological analysis revealed newly formed bone in experimental group earlier than that in control group. Especially at 1 week after implantation, more amounts of new bone matrix and collagen around the implant in the experimental group were seen compared with the control group. Immunohistochemical analysis showed that the levels of osteoprotegerin (OPG) expression in the experimental group were increased at early stages compared with that of control group until 2 weeks after implantation. But after 2 weeks, the expression level of OPG similar in both groups. The expression levels of receptor activator of nuclear factor kB ligand (RANKL) were stronger in the experimental group than the control group until 2 weeks after implantation. After 4 weeks, expression of RANKL in experimental group was similar to the control group. Conclusion: The results of this study suggest that LIPUS with Adipose-Derived Stem Cells in implantation could promote bone healing around titanium implants in rats with osteoporosis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.5
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• pp.386-395
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• 2011

Introduction: Osteoporosis is a major health problem in the elderly that involves changes in the properties of bone as well as impaired bone healing around a titanium implant in both humans and animals. This study examined effect of low intensity pulsed ultrasound (LIPUS) on the bone healing process around a titanium implant in osteoporosis-induced rats. Materials and Methods: Sixteen rats were divided into two groups. A control group with osteoporosis induced by removing both ovaries and an experimental group of rats that were applied with LIPUS after osteoporosis had been induced. A screw type titanium implant (diameter, 2.0 mm: length, 3.5 mm, Cowell-Medi, KOREA) was placed into the tibias of 16 rats. The control and experimental group contained 8 rats each. The rats were sacrificed at 1, 2, 4, and 8 weeks after implantation to examine the histopathology and immunochemistry. Results: The histopathology examination revealed earlier new bone formation in the experimental group than the control group. In particular, at 1 week after implantation, more new bone matrix and collagen were observed around the implant of the experimental group compared to the control group. Immunochemistry analysis showed that the level of OPG expression of the experimental group was higher in the early stages than in the control group. After 8 weeks, the levels of OPG expression were similar in both groups. The expression level of receptor activator of nuclear factor kB ligand (RANKL) was stronger in the experimental group than the control group. After 4 weeks, the level of RANKL expression was similar in both groups. Conclusion: These results suggest that the application of LIPUS to implantation can promote bone healing around titanium in osteoporosis animals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.249-254
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• 2004

The hydro-acoustic method is widely used for estimating biomass and distribution of fisheries resources along the coast and in the ocean. High costs and time are necessary to construct systems for this method and to initially educate specialists. It has been used in fisheries of advanced nations like Japan and Norway, because it is more efficient than other methods. In order to research the behavior of fish around an artificial reef using an echo sounder, volume backscattering strength (SV) and fish per cubic meter (FPCM) of darkbanded rockfish around the model artificial reef in a water tank were measured. Moreover, behavior of fish was observed in an adjacent artificial reef, which was constructed at Tongyeong marine ranching area. Following that, an acoustics survey was conducted at Mirukdo around the Tongyeong marine ranching area, in order to understand the spatial distribution and strength of fisheries resources. Very high patches of fish were found in a wide area around the artificial reef. It is thought that an approaching fish school around the artificial reef can be measured accurately by using an echo sounder of high resolution. Moreover, use of other monitoring methods like of diving or ROV simultaneous with an echo sounder is required in order to grasp the species and ecology of fish inhabiting the area around the artificial reef.