• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.15-18
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• 2003

The present study addresses an experimental investigations of the near field flow structures of supersonic, dual, coaxial, swirl jet. The swirl stream is discharged from the secondary annular nozzle and the primary inner nozzle provides the sonic and supersonic free jets. The interactions between the secondary swirl and inner soni $c^ersonic jets are quantified by a fine pilot impact and static pressure measurements and are visualized by using a shadowgraph optical method. The pressure ratios of the secondary swirl and primary soni $c^ersonic jets are varied below 7.0. Experiments are conducted to investigate the effects of the secondary swirl stream on the primary sonic and supersonic jets, compared with the secondary stream of no swirl. The results show that the presence of annular swirl stream causes the Mach disk to move more downstream, with the increased diameter, and remarkably reduces the fluctuations of the impact pressures in the supersonic dual coaxial jet, compared with the case of the secondary annular stream of no swirl.swirl.

• Journal of Korean Neurosurgical Society
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• v.64 no.3
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• pp.414-417
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• 2021

During the last two decades, there have been remarkable advances in knowledge regarding secondary neurulation. An increased number of cases of occult spinal dysraphism and progress in basic embryology research have provoked the continuous discovery of new disease entities and the reclassification of occult spinal dysraphic lesions. Examples of such changes are described. The characteristics of secondary neurulation compared with those of primary neurulation are listed and discussed. Our fundamental questions include what the evolutionary significance of secondary neurulation is and what the advantages of having secondary neurulation are. However, our current data and speculations are insufficient to support scientific inference. The direction of future progress of research in this field is predicted. The role of clinicians in this progress is emphasized.

• Applied Microscopy
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• v.51
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• pp.15.1-15.2
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• 2021

Puccinia miscanthi teliospores were observed on the leaf surface of Miscanthus sinensis using a field emission scanning electron microscope. Details of teliospore mucilage could be visualized through the axial imaging of secondary electrons for a better understanding of pathogen behavior in rust diseases.

• Journal of Trauma and Injury
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• v.25 no.4
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• pp.145-151
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• 2012

Purpose: The objective of this study was to determine the appropriateness of Emergency Medical Service's (EMS's) triage and transport of severely injured patients in Busan and Kyungnam, Korea. Methods: The medical records of the Emergency Medical Information Center were retrospectively reviewed from January 1, 2010 to December 31, 2010. We identified the number of patients that should have been transferred from a secondary to a tertiary hospital according to the EMS field triage protocol. Results: In a total of 472 cases requests to be transferred to a third hospital were made through the Emergency Medical Information Center. Of these, 207 patients(43.9%) should have been transferred to a tertiary hospital according to the EMS field triage protocol. Among them, thirty-three(15.9%) patients satisfied step 1, 15(7.0%) satisfied step 2, and 117(56.5%) satisfied step 3. Twenty-three(11.1%) patients satisfied both steps 1 and 3. Conclusion: We found the triage by the EMS in the transfer of severely injured patients to a tertiary hospital to be inappropriate and re-education of EMS personnel regarding the EMS field triage protocol is needed. Because many patients are transferred from a secondary to a third hospital, we suggest changing the EMS field triage protocol to expand the severe injury criteria. A need exists to authorize secondary hospitals to transfer severely injured patients directly because there are no trauma centers in Korea.

• Journal of Climate Change Research
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• v.6 no.4
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• pp.257-265
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• 2015

For estimating a net removal of carbon dioxides from a forest carbon offset project, it is necessary to consider secondary emissions occurred from the use of machineries or vehicles. According to the forest carbon standard in Korea, a default rate (5%) could be applied for estimating secondary emissions of small projects, which provide annual net removals less than or equal to $600tCO_2$, while secondary emissions should be estimated for larger projects with field survey. In this study, we intended to develop a methodology for estimating the secondary emission of a forest carbon project. For this purpose, we analyzed the working process and the carbon emissions of the forest management activities for major tree species in Korea. Based on the developed methodology, we estimated the secondary carbon emission of a reforestation project. The result showed that the secondary carbon emission of a reforestation project was estimated between 0.42% and 1.19 % compared to net removals, that is to say that the current default rate in the forest carbon standard could give an overestimated secondary emission.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.1029-1040
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• 2021

For the structural integrity evaluation of pressurized water reactor (PWR) steam generator (SG) tubes subjected to transient hydraulic loading, determination of the tube-to-tube gap velocity and static pressure distributions along the tubes is prerequisite. This paper addresses both computational fluid dynamics (CFD) and analytical approaches for predicting the tube-to-tube gap velocity and static pressure distributions during blowdown following a feedwater line break (FWLB) accident at a PWR SG. First of all, a comparative study on CFD calculations of the transient velocity and pressure distributions in the SG secondary sides for two different models having 30 or no tubes is performed. The result shows that the velocities of sub-cooled water flowing between any adjacent two tubes of a tubed SG model during blowdown can be roughly estimated by applying the specified SG secondary side porosity to those of the no-tubed SG model. Secondly, simplified analytical approximate solutions for the steady two-dimensional SG secondary flow velocity and pressure distributions under a given discharge flowrate are derived using a line sink model. The simplified analytical solutions are validated by comparing them to the CFD calculations.

• Economic and Environmental Geology
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• v.17 no.2
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• pp.141-147
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• 1984

For the discussion of palaeogeomagnetic field direction and the movement and rotation of geotectonic blocks it is prerequisite to eliminate the secondary remanent magnetization component out of the NRM vector of given rock samples. Among various techniques alternating field and thermal demagnetization methods are most easily applicable and most widely used ones. Physical principle underlying these methods is the concept of relaxation time: Either with an action of external magnetic field or with an elevated temperature relaxation time of magnetic minerals can be drastically shortened. It has been furthermore shown experimentally that the secondary remanent magnetization can be more easily demagnetized than the primary remanent magnetization. Through careful stepwise demagnetization it should also be possible to discriminate the kind of various remanent magnetizations. In addition to the introduction to the underlying physical principles and experimental results of the alternating field and thermal demagnetization this paper gives various practical tips in earring out the demagnetization experiments. Each alternating field and thermal demagnetization instrumentation which is easily adaptable to domestic palaeomagnetic laboratories is also introduced. This paper provides a compact and practical introduction to the methods in palaeomagnetism and would be of interest to present workers and to those who want to embark on research in this field.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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• pp.637-643
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• 2001

Two-phase flow in a combustion chamber is experimentally analyzed according to the five different conditions in the Reynolds numbers of $1.02{\times}10^4$. As the height difference between the primary and secondary jets increases, the secondary has a little less effect on the primary one in the case on the same height difference, the primary jet is affects as the velocity of th secondary on increase. The primary-jet flow field cause the particle concentration since is controlled by the velocity of secondary jet, the height difference, and the angle of primary jet in the test section.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.927-930
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• 2004

We report on a new type of a flat and thin display with a secondary emission electron source. In this display device electrons are multiplied between two secondary emission plates under a high frequency electric field. This principle has a few important advantages over a field emission display: the emission comes from flat plates, which reduces the life-time problems of ion bombardment of field emitter tips. Furthermore, the electron emission is space charge limited which gives a uniform electron distribution. The electrons are extracted from the source and accelerated to a phosphor screen to generate light. Gray levels are made by pulse width modulation.

• Journal of computational fluids engineering
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• v.5 no.3
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• pp.8-15
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• 2000

This research is aimed to find out how the inlet angle of secondary air affects the uniformity of temperature distribution inside a small incinerator. A commercial code, PHOENICS, is used to simulate the thermal-flow field of an incinerator. The computational grid system is constructed by Multi-Block technique provided by PHOENICS. Numerical experiments are done with the five different angles of secondary air inlet. The uniformity of temperature distribution is evaluated by checking the standard deviation of temperature distribution in an incinerator. The computational results show that there is the minimum value of standard deviation at the certain angle of secondary air inlet, which means that there is an optimum angle of secondary air inlet that could improve the uniformity of temperature distribution in an incinerator. The optimum angle of secondary air inlet is between 30 degree and 45 degree in this particular case.