• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.238-248
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• 2014

The metalloid arsenic (Z = 33) is considered to be a significant potential threat to human health due to its ubiquity and toxicity, even in rural regions. In this study a rural region contaminated with arsenic, located at longitude $85^{\circ}$ 32'E and latitude $25^{\circ}$ 11'N, was initially examined. Arsenic tolerant bacteria from the rhizosphere of Amaranthas viridis were found and identified as Bacillus licheniformis through 16S rRNA gene sequencing. The potential for the uptake and removal of arsenic at 3, 6 and 9 mM [As(V)], and 2, 4 and 6 mM [As(III)], and for the reduction of the above concentrations of As(V) to As(III) by the Bacillus licheniformis were then assessed. The minimal inhibitory concentrations (MIC) for As(V) and As(III) was determined to be 10 and 7 mM, respectively. At 3 mM 100% As(V) was uptaken by the bacteria with the liberation of 42% As(III) into the medium, whereas at 6 mM As(V), 76% AS(V) was removed from the media and 56% was reduced to As(III). At 2 mM As(III), the bacteria consumed 100%, whereas at 6 mM, the As(III) consumption was only 40%. The role of pH was significant for the speciation, availability and toxicity of the arsenic, which was measured as the variation in growth, uptake and content of cell protein. Both As(V) and As(III) were most toxic at around a neutral pH, whereas both acidic and basic pH favored growth, but at variable levels. Contrary to many reports, the total cell protein content in the bacteria was enhanced by both As(V) and As(III) stress.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.176-184
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• 2020

This study identified personality types of 433 college students of Busan, Ulsan and some regions of Gyeongsangnam-do and inquired into influences of personality types on their satisfaction with clinical practice. According to the results, students with extroverted and low-neurotic tendencies showed significant results in the subordinate factors of satisfaction with clinical practice. As for factors influencing the extraversion factors personality type, it turned out to have a significant level in satisfied with teach (p<0.001), satisfied with facility and satisfied with clinical practice (p<0.05). On the other hand, as for factors influencing the personality type of neurotic tendencies, it turned out to have a significant level in satisfied with practice content (p<0.05), satisfied with teach (p<0.001), satisfied with interpersonal (p<0.05) and satisfied with clinical practice (p<0.05). Therefore, it will be indispensable to conduct a personality type test during the period of university days, to increase satisfaction with clinical practice of students majoring in Dental hygienics. Moreover, based on the test results, it will be required to develop a variety of programs to strengthen a customized counseling program and improve interpersonal skills.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.495-502
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• 2014

Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.87-94
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• 2014

In solid mechanics, the peridynamics theory has provided a suitable framework for material failure and damage propagation simulation. Peridynamics is computationally expensive since it is required to solve enormous nonlocal interactions based upon integro-differential equations. Thus, multiscale coupling methods with other local models are of interest for efficient and accurate implementations of peridynamics. In this study, peridynamic models are restricted to regions where discontinuities or stress concentrations are present. In the domains characterized by smooth displacements, classical local models can be employed. We introduce a recently developed blending scheme to concurrently couple bond-based peridynamic models and the Navier equation of classical elasticity. We demonstrate numerically that the proposed blended model is suitable for point loads and static fracture, suggesting an alternative framework for cases where peridynamic models are too expensive, while classical local models are not accurate enough.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.1
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• pp.1-11
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• 2017

In order to assess risk of high temperature damages about corn during reproduction stages in the future, we carried out analysis of climate change scenarios RCP (Representative Concentration Pathway) 4.5 and RCP8.5 distributed by KMA (Korea Meteorological Administration) in 2012. We established two indexes such as average of annual risk days of high temperature damage which express frequency and strengthen index of high temperature damage. As results of producing maps for 157 cities and counties about average of annual risk days of high temperature damage during total periods of scenarios, the risk of high temperature in RCP8.5 was evaluated to increase at all over nation except inland area of Gangwon province, while RCP4.5 showed similar to present, or little higher. The maps of annual risk days of high temperature damage with 10 years interval in RCP8.5 prospected that the risk for damaging corn growth would increase rapidly from 2030's. The largest risk of high temperature damage in the future of RCP8.5 was analyzed at Changnyeong county located east-south inland area in Kyeongnam province, while the smallest of risk counties were Pyeongchang, Taebaek, Inje, and Jeongseon. The prospect at 12 counties which is large to produce corn at present and contains large plains have been showed that there will be only a little increase of risk of high temperature at Goesan, Yangpyeong, Hongcheon, Seosan, and Mooju until 2060's. But considering strengthen index of high temperature damage, most regions analyzed would be prospected to increase rapidly after 2030's. To cope with high temperature damage of corn in the future, we should develop various practical technologies including breeding adapted varieties and controlling cultivation periods.

• Earthquakes and Structures
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• v.8 no.3
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• pp.619-637
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• 2015

A field based non-destructive hardness method is being developed to determine plastic strain in steel elements subjected to seismic loading. The focus of this study is on the active links of eccentrically braced frames (EBFs). The 2010/2011 Christchurch earthquake series, especially the very intense February 22 shaking, which was the first earthquake worldwide to push complete EBF systems into their inelastic state, generating a moderate to high level of plastic strain in EBF active links for a range of buildings from 3 to 23 storeys in height. Plastic deformation was confined to the active links. This raised two important questions: what was the extent of plastic deformation and what effect does that have on post-earthquake steel properties? A non-destructive hardness test method is being used to determine a relationship between hardness and plastic strain in active link beams. Active links from the earthquake affected, 23-storey Pacific Tower building in Christchurch are being analysed in the field and laboratory. Test results to date show clear evidence that this method is able to give a good relationship between plastic strain and demand. This paper presents significant findings from this project to investigate the relationship between hardness and plastic strain that warrant publication prior to the completion of the project. Principal of these is the discovery that hot rolled steel beams carry manufacturing induced plastic strains, in regions of the webs, of up to 5%.

• Steel and Composite Structures
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• v.12 no.4
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• pp.291-302
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• 2012

Frequently, steel silos are supported by discrete supports or columns to permit easy access beneath the barrel. In such cases, large loads are transferred to the limited number of supports, causing locally high axial compressive stress concentrations in the shell wall above the supports. If not dealt with properly, these increased stresses will lead to premature failure of the silo due to local instability in the regions above the supports. Local stiffening near the supports is a way to improve the buckling resistance, as material is added in the region of elevated stresses, levelling these out to values found in uniformly supported silos. The aim of a study on the properties of local stiffening will then be to increase the failure load, governed by an interaction of plastic collapse and elastic instability, to that of a discrete supported silo. However, during the course of such a study it was found that, although the failure remains local, the cylinder height is also a parameter that influences the failure mechanism, a fact that is not properly taken into account in current design practice and codes. This paper describes the mechanism behind the effect of the cylinder height on the failure load, which is related to pre-buckling deformations of the shell structure. All results and conclusions are based on geometrically and materially non-linear finite element analyses.

• Molecules and Cells
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• v.27 no.2
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• pp.263-268
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• 2009

Gamma knife surgery (GKS) is used for the treatment of various human brain disorders. However, the biological effects of gamma ray irradiation on both the target area, and the surrounding tissues are not well studied. The effects of gamma ray exposure to both targeted and untargeted regions were therefore evaluated by monitoring gene expression changes in the unilateral irradiated (60 Gy) and contralateral un-irradiated striata in the rat. Striata of irradiated and control brains were dissected 16 hours post-irradiation for analysis using a whole genome 44K DNA oligo microarray approach. The results revealed 230 induced and 144 repressed genes in the irradiated striatum and 432 induced and 239 repressed genes in the unirradiated striatum. Out of these altered genes 39 of the induced and 16 of the reduced genes were common to both irradiated and un-irradiated tissue. Results of semiquantitative, confirmatory RT-PCR and western blot analyses suggested that ${\gamma}$-irradiation caused cellular damage, including oxidative stress, in the striata of both hemispheres of the brains of treated animals.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.04a
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• pp.34-34
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• 1997

The effect of alloying mode and porosity on the axial tension-tension fatigue behavior of a P/M steel of nominal composition Fe-4w/o Ni-1.5w/o Cu-O.5w/o Mo-O.5w/o C has been evaluated. Alloying modes utilized were elemental powder mixing, partial alloying(distaloy) and prealloying by water atomization; in each case the carbon was introduced as graphite prior to sintering. Powder compacts were sintered($1120{\circ}C$/30 min.) in 7Sv/o $H_2$/25v/o $N_2$ to densities in the range 6.77-7.2 g/$cm^3$. The dependence of fatigue limit response on alloying mode and porosity was interpreted in terms of the constituent phases and the pore and fracture morphologies associated with the three alloying modes. For the same nominal composition, the three alloying modes resulted in different sintered microstructures. In the elemental mix alloy and the distaloy, the major constituent was coarse and fine pearlite, with regions of Ni-rich ferrite, Ni-rich martensite and Ni-rich areas. In contrast, the prealloy consisted primarily of martensite by with some Ni-rich areas. From an examination of the fracture surfaces following fatigue testing it was concluded that essentially all of the fracture surfaces exhibited dimpled rupture, characteristic of tensile overload. Thus, the extent of growth of any fatigue cracks prior to overload was small. The stress amplitude for the three alloying modes at 2x$l0^6$ was used for the comparison of fatigue strengths. For load cycles <3x$l0^5$, the prealloy exhibited optimum fatigue response followed by the distaloy and elemental mix alloy, respectively. At load cycles >2x$l0^6$, similar fatigue limits were exhibited by the three alloys. It was concluded that fatigue cracks propagate primarily through pores, rather than through the constituent phases of the microstructure. A decrease in pore SIze improved the S-N behavior of the sintered steel.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.821-827
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• 2008

The unicellular green alga Dunaliella salina is a halotolerant eukaryotic organism. Its halophytic properties provide an important advantage for open pond mass cultivation, since D. salina can be grown selectively. D. salina was originally described by E. C. Teodoresco in 1905. Since that time, numerous isolates of D. salina have been identified from hypersaline environments on different continents. The new Dunaliella strain used for this study was isolated from the salt farm area of the west coastal side of South Korea. Cells of the new strain were approximately oval- or pear-shaped (approximately $16-24\;{\mu}m$ long and $10-15\;{\mu}m$ wide), and contained one pyrenoid, cytoplasmatic granules, and no visible eyespot. Although levels of $\beta$-carotene per cell were relatively low in cells grown at salinities between 0.5 to 2.5 M NaCl, cells grown at 4.5 M NaCl contained about a ten-fold increase in cellular levels of $\beta$-carotene, which demonstrated that cells of the new Korean strain of Dunaliella can overaccumulate $\beta$-carotene in response to salt stress. Analysis of the ITS1 and ITS2 regions of the new Korean isolate showed that it is in the same clade as D. salina. Consequently, based on comparative cell morphology, biochemistry, and molecular phylogeny, the new Dunaliella isolate from South Korea was classified as D. salina KCTC10654BP.