• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.549-552
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• 2015

The galactic magnetic field (GMF) and the intergalactic magnetic field (IGMF) affect the propagation of ultra-high energy cosmic rays (UHECRs) from the source to us. Here we examine the influences of the GMF/IGFM and the dependence of their sky distribution on galactic latitude, b. We analyze the correlation between the arrival direction (AD) of UHECRs observed by the Pierre Auger Observatory and the large-scale structure of the universe in regions of sky divided by b. Specifically, we compare the AD distribution of observed UHECRs to that of mock UHECRs generated from a source model constructed with active galactic nuclei. Our source model has the smearing angle as a free parameter that reflects the deflection angle of UHECRs from the source. The results show that larger smearing angles are required for the observed distribution of UHECRs in lower galactic latitude regions. We obtain, for instance, a $1{\sigma}$ credible interval for smearing angle of $0^{\circ}{\leq}{\theta}_s{\leq}72^{\circ}$ at high galactic latitudes, $60^{\circ}$ < $\left|{b}\right|{\leq}90^{\circ}$, and of $75^{\circ}{\leq}{\theta}_s{\leq}180^{\circ}$, $-30^{\circ}{\leq}b{\leq}30^{\circ}$, at low galactic latitudes, respectively. The results show that the influence of the GMF is stronger than that of the IGMF. In addition, we can estimate the strength of GMFs by these values; if we assume that UHECRs would have heavier nuclei, the estimated strengths of GMF are consistent with the observational value of a few ${\mu}G$. More data from the future experiments may make UHECR astronomy possible.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.44-50
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• 1994

This study was carried out to select the appropriate medium(especially, carbon and nitrogen source ) for somatic embryogenesis in order to develop the rapid mass production system in suspension culture of chuanxiang Hort. Suitable medium for somatic embryo formation was MS medium. The half strength MS medium was effective for somatic embryo development. Sucrose was the most effective carbon source for somatic embryo formation, however, production of somatic embryos was reduced at higher concentration of sucrose. Effects of suger was the same as sucrose. Somatic embryo formation was higher as the decrease of $NH_{4}NO_3$, and optimum ratio of $KNO_3\;:\;NH_4NO_3$ was 825 : 238mg /1. Regenerated plant was obtained in MS basal medium and survival late of plantlet was 60-70% after transplanted directly to the vermiculite.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.76-84
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• 2017

This study selected a method which uses high early strength cement as a way to reduce the curing time and curing energy source of concrete secondary products and reviewed the improvement in the initial strength of concrete secondary products setting the target strength of the concrete capable of removing the form to 15MPa and the curing time to 6 hours. As a result of the test, the only specimen which achieved the form removal strength of 15 MPa only through atmospheric curing within the target curing time of 6hours was ACC-100, and the specimens of TRC-100 and TRC-50 satisfied the values of 6 hours and 15MPa through steam curing. However, we could see that it was difficult to secure workability in the case of the specimen of ACC-100 due to its high rapid setting property and a retarder such as anhydrous citric acid was required to be used to improve the workability. When we look into the pattern following changes in the water to binder ratio, while, in the case of stream curing, OPC-100, TRC-100, and TRC-50 were all found to satisfy achievement of the form removal strength within 6hours as the water to binder ratio decreased, in the case of atmospheric curing, TRC-100, and TRC-50 achieved 15MPa within 12hours.

• The korean journal of orthodontics
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• v.35 no.6 s.113
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• pp.443-450
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• 2005

This study was performed to compare the shear bond strength of orthodontic adhesive to amalgam according to different light sources (halogen-based light and light emitting diode (LED)) and amalgam surface treatments. Ninety extracted human premolars were randomly divided into 6 groups (4 experimental and 2 control groups) of 15 by light sources and surface treatments. Orthodontic brackets were bonded and shear bond strength was measured with an Instron universal testing machine. The findings were as follows: The bond strength of adhesive to amalgam surface was 3-5.5 MPa which was lower than that of acid-etched enamel (19 MPa) control. In the sandblasted amalgam surface, the shear bond strength of the halogen light group was higher than that of the LED group (p < 0.05) but. in the non-treated amalgam surface. there was no significant difference in the shear bond strength according to the light sources (p> 0.05). Within the same light source. sandblasting had no significant effect on the shear bond strength of the adhesive bonded to amalgam surface (p > 0.05). There was no significant difference in shear bond strength according to the light sources in acid-etched enamel control groups. This results suggest that there can be a limit in using light curing adhesives when brackets are bonded to an amalgam surface. Additional clinical studies are necessary before routine use of halogen light and LED light curing units can be recommended in bonding brackets to an amalgam surface.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.43-49
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• 2002

A7003 alloy has characteristics of their excellent weldability, high corrosion resistance and superior plastic working however the broadening of application for the alloy has been hampered by the lower extrudability associated by Mg content. For improvement of extrudability and enhanced recovery efficiency during Al scrap recyeling, it has been generally practiced to reduce Mg content in A7003 alloy. Therefore, it is necessary to investigate the influence of Mg content on mechanical strength and extrudability of A7003 alloy. For efficient material processing which has small amounts, life cycle assessment in material processing(MLCA) is evaluated. The quantitative analysis of energy requirements and $CO_2$ emission for production of A7003 extruded bar are estimated with different Mg content and billet pre-heating process (heating source by light oil or LPG). In particular, the estimation of energy requirements was performed within shipping and gating range (except the mining and extraction stages)to investigate the influence of the variables on energy requirements and $CO_2$ emission in detail. As Mg content increased, the flow stress and the extrusion pressure for A7003 alloy increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and increment in volume fraction of intermetallic compound, $Mg_2Si$. The extrudability and the tensile strength are equal to, or above that of conventional A 7003 alloy even the content of Mg varied from $1.1wt.\%\;to\;0.5wt.\%$ alloy. This means that minimizing the content of Mg in A7003 alloy can enhance recovery efficiency during Al scrap recycling. It can be quoted that rather than Mg content energy source for billet heating is a prime factor to determine the atmospheric $CO_2$ emission.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1725-1728
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• 2004

An experiment was conducted to investigate the efficiency of transfer of dietary iron sources to eggs of laying hens. Eighty ISA-Brown laying birds of 30 wk old were housed in 40 cages of 2 birds each. Eight birds in four cages were assigned to one of the following ten treatments: T1; control, T2; 100 ppm iron supplementation with iron-methionine chelate (Fe-Met-100), T3; Fe-Met- 200, T4; Fe-Met-300, T5; 100 ppm iron supplementation with iron sulfate ($FeSO_4$-100), T6; $FeSO_4$-200, T7; $FeSO_4$-300, T8; 100 ppm iron supplementation with Availa-$Fe^{(R)}$ (Availa-Fe-100), T9; Availa-Fe-200 and T10; Availa-Fe-300. Results of 40 d feeding trial showed that there were no consistent responses in laying performance by source and level of iron supplementation. However, eggshell strength and color were improved by Fe supplementation. Egg iron content was maximized at 10-15 days after feeding supplemental Fe. Fe- Met was the most effective source in enriching Fe of eggs followed by Availa-Fe and $FeSO_4$. Increasing supplementary Fe level more than 100 ppm was not effective in Fe-Met and Availa-Fe treatments. Average Fe enrichment of 18% was achieved after feeding Fe-Met-100 for 15 d. In conclusion, enrichment of Fe in egg could be effectively achieved by supplementation of Fe-Met-100 for 15 d.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.1-7
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• 1990

Theoretical evaluations of the vertical displacement at the epicenter on the circular glass plate have been carried out in the case of the unit point loading(1 dyne force strength) with the Heaviside step-function time dependency. Acoustic emission signals generated during pencil lead($\Phi$=0.5mm, HB) fracture on the soda-lime glass($\Phi$=22cm, thickness=2.8cm) were observed by the optical Michelson interferometer with the stabilized circuit, and then the source function of the observed acoustic emission signals was analyzed by the deconvolution method. The source function of acoustic emission during pencil lead fracture had a 'dip' of~0.7$\mu$sec duration time at the front portion and a step function of~0.5$\mu$sec rise time with a force strength of~4.5N.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.12-23
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• 2009

Sensor networks deployed in battlefields to support military operations or deployed in natural habitats to monitor the rare wildlifes must take account of protection of the location of valuable assets(i.e., soldiers or wildlifes) from an adversary or malicious tracing as well as the security of messages in transit. In this paper we propose a routing protocol GSLP(GPSR-based Source-Location Privacy) that is capable of enhancing the location privacy of an active source node(i.e., message-originating node) in the presence of multiple dormant sources(i.e., nodes lying nearby an asset whose location needs to be secured). Extended is a simple, yet scalable, routing scheme GPSR(greedy perimeter stateless routing) to select randomly a next-hop node with a certain probability for randomizing paths and to perform perimeter routing for detouring dormant sources so that the privacy strength of the active source, defined as safety period, keeps enhanced. The simulation results obtained by increasing the number of dormant sources up to 1.0% of the total number of nodes show that GSLP yields increased and nearly invariant safety periods, while those of PR-SP(Phantom Routing, Single Path), a notable existing protocol for source-location privacy, rapidly drop off as the number of dormant sources increases. It turns out that delivery latencies of GSLP are roughly less than two-fold of the shortest path length between the active source and the destination.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.490-497
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• 2020

This work has been initiated to find possibility whether recycled fine aggregate can be used as a source of aggregate for structural concrete or not. Two-stage mixing approach was chosen in order to maximize strength potential from recycled fine aggregate. Moisture content of the recycled fine aggregate was changed, and two different types of two-stage mixing approaches were applied to produce cement mortar. The strength of mortar made of 100% recycled fine aggregate by two-stage mixing approaches was compared to that of mortar made of 100% washed sea sand. According to the results, the effect of moisture content on compressive strength was observed from low water cement mortar(W/C 0.3). In case of W/C 0.5 cement mortar, no clear relationship was observed between moisture content and strength development. It was found that two-stage mixing approach has a potential to increase the strength of mortar made of 100% recycled fine aggregate. In case of modified version of two-stage mixing approach which first prepares cement paste and pours recycled fine aggregate into the cement paste, was more effective to increase the strength of mortar made of 100% recycled fine aggregate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.434-439
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• 2020

Selective laser melting (SLM) manufactures an alloy using laser as a heat source, and has recently been introduced in the dental industry. However, there is a lack of analytical research on metal-ceramic restorations achieved by SLM. This study evaluates and compares the metal-ceramic bond strength of Co-Cr alloys produced by selective laser melting and casting methods. Co-Cr samples required for this study were produced through the sintering process of ceramics, by applying the SLM and CAST methods. The metal-ceramic bond strength was measured by applying the shear bond strength test. In order to determine the area fraction of adherent ceramic, Si content of the specimen was measured using scanning electron microscopy SEM/ EDS. Results of the metal-ceramic bond strength and AFAC were analyzed by t-test (α = 0.05). No significant difference was observed comparing the bond strength of SLM and CAST Co-Cr alloys (P> 0.05). However, the SLM group had much better ceramic adherence than the CAST group (P < 0.001). Moreover, oxidation characteristics were similar for both SLM and CAST Co-Cr alloys, but metal structures were different. These results imply that although the bond of ceramic and Co-Cr alloy is not related to the manufacturing method, SLM alloys impart better ceramic adherence. This indicates that alloys made with SLM can be used to fabricate upper implant prostheses in the future. In particular, it is expected to overcome the shortcomings of the CAST method, and save time and cost.