• Journal of Plant Biology
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• v.36 no.3
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• pp.195-201
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• 1993

The room temperature fluorescence induction of chloroplasts was utilized as a probe to locate the site of inhibition by mercury, copper and zinc on PS II by mercury. Inhibitory effect of Hg2+ on electron transport activity was notable as compared with Cu2+ and Zn2+. At concentrations of HgCl2 over 50 $\mu$M, activities of PS II and whole-chain electron transport decreased more than 70%, while that of PS I decreased about 10~30%. This suggests that PS II is more susceptible to Hg2+ than PS I is. In the presence of diphenylcarbazide (DPC), 50 $\mu$M HgCl2 inhibited the reduction of dichlorophenolindophenol (DCPIP) about 50%. Addition of heavy metals induced marked decrease in maximal variable fluorescence/initial fluorescence [(Fv)m/Fo], but no changes in Fo. With various concentrations of heavy metals, changes of chlorophyll a fluorescence emitted by PS II showed gradual decrease in photochemical quenching (qQ), which indicates an increase in reduced state of electron acceptor, QA. Especially, the addition of HgCl2 caused a notable decrease of qQ. In the presence of 50 $\mu$M CuCl2, energy-depended quenching (qE) was completely reduced, whereas in the presence of 50 $\mu$M CuCl2 and ZnCl2 it was still remained. The above results are discussed on the effects of mercury in relation to water-splitting system and plastoquinone (PQ) shuttle system.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.180-185
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• 1997

Variations of core loss and coercivity with heat treatment condition have been studied in amorphous ribbon core specimens. All measurements were performed at 10 kHz with a maximum induction of 0.1 T. With increasing annealing time, both core loss and coercivity of core specimens decreased first, reaching minimum values, and increased thereafter. Specimen heat treated in an air showed better soft magnetic properties than those treated in Ar atmosphere. The specimens annealed under magnetic field higher than 6 Oe in radial direction showed reduced core loss and coercivity. The field annealing effects were increased with increasing cooling rate near Curie temperature of the material. The specimen annealed under an applied field in perpendicular direction of the core showed increased coercivity and decreased permeability.

• Transactions of Materials Processing
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• v.20 no.4
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• pp.296-302
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• 2011

The objective of this paper is to determine the effect of process parameters on the behavior of a 18Cr-10Mn-$0.44N_2$ nitrogen steel sample deformed by hot rolling. Compression tests were carried out at high temperatures to determine the flow stresses needed for a finite element(FE) analysis. The strain rate, ranging from 0.1 to $1.0s^{-1}$, significantly affected the flow stress at temperatures higher than $1,000^{\circ}C$. Non-isothermal rolling simulations and laboratory rolling tests were performed with plate specimens 14.5mm thick, 135mm wide and 226mm long. A rolling reduction of 15% per pass leading to a cumulative rolling reduction of 60% was determined as optimal. The extension ratio of 176.5% in the length direction was about 30.4 times greater than the extension ratio of 5.8% in the width direction. Isotropic properties for tensile strength, microstructure and grain size were measured after mock-up hot rolling tests. The results from the mockup tests were found to be in good agreement with those of the simulations.

• Journal of Korea Foundry Society
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• v.28 no.6
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• pp.282-287
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• 2008

The effect of CaO mold on the formation of reaction layer was investigated. CaO mold was prepared by mixing of Colloidal silica($NALCO^{(R)}$ 1130) and an $ZrO_2$, CaO at room temperature. The dried at $20{\pm}3^{\circ}C$, 75% humidity for 12hrs. Sample was prepared from the Cp-Ti(grade-2) and melted by high frequence induction melting system in the vacuum condition. The react ion layer of Ti was confirmed by optical microscopy, microhardness(Hv) and X-ray diffraction. Thickness of reaction layer using the CaO stabilized ZrO2 was thinner than the CaO added ZrO2. And thickness of reaction layer were decreased with decreasing pH of slurry. CaO addition in the slurry could not controlled reaction between molten Ti and investment mold. On the other hand, the CaO chemical bonded ZrO2 by stabilization treatment could controlled reaction between molten Ti and investment mold.

• Journal of Aquaculture
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• v.10 no.1
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• pp.17-24
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• 1997

In order to understand the spawning and larval development of Perinereis aibuhitensis for the effective seedling production, the influence of water temperature on spawning induction, egg and larval development of the worm were investigated from October 30, 1989 to October 30, 1990. Main spawning period was from July through September, and average diameter of mature eggs was $220\mu m$. The relationship between the adult weight (Wt) and the number of spawned eggs (NS) was given as follws : NS=48635.589Wt1.3044 (r=0.8572). Adult males and females died immediately after spawning. Trochophore larvae developed 12 hours after fertilization, and hatched out after 56 hours.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.887-890
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• 2010

The family of ClpB protein is a molecular chaperone which protects cellular proteins from being aggregated upon exposure to severe environmental stresses in association with DnaK/DanJ/GrpE in the ATP-dependent manner. In a psychrophilic bacterium which survives at a subzero temperature, any functional role of cold-active ClpB protein can be rather crucial. In order to identify a ClpB encoding gene from a cold-adapted bacterium whose genome sequence has not been fully discovered, we have employed a series of PCR technologies, including a gradient PCR with homologous primers, an inverse PCR and a cassette PCR. The full sequence of PaclpB gene was successfully identified and compared with those of other psychrophilic species. We have further cloned the gene in E.coli expression systems and were able to induce PaClpB protein expression by IPTG, which help us understand a molecular mechanism for survival against extremely cold environments.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.114-121
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• 2001

Effect of sintering temperature and dusts content on sintered density ($\rho$) and magnetic properties were evaluated. Cores sintered at 1350 $^{\circ}C$ for 1 hour with the Fe powders containing up to 10 wt.% dusts showed a good AC/DC properties. For example, the DC magnetic properties of magnetic induction (B$_{15}$), coercive force (H$_{c}$) and permeability ($\mu$$_{max}$) of cores containing 10 wt.% dusts were ranging over 9.8~ 10.9 kG, 2.2-2.3 Oe and 1950~2050, respectively. These magnetic properties are equivalent to those of competitor's (i.e, Ancorsteel produced by Hoganas). The cores obtained from the present work are expected to apply for high-performance soft magnetic components such as automotive and DC motor.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.117.2-117.2
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• 2012

It is generally accepted that sudden compressions of the magnetosphere cause electromagnetic ion cyclotron (EMIC) wave growth by increasing the proton temperature anisotropy. These compression-associated EMIC waves are expected to be on higher latitudes (i.e., higher-L regions close to the magnetopause). In this study we examine Pc1 pulsations, which are believed to be generated by the EMIC instability, observed at subauroral latitude near the nominal plasmapause when the magnetosphere is suddenly compressed by solar wind dynamic pressure variations, using induction magnetometer data obtained from Athabasca, Canada (geomagnetic latitude = 61.7 N, L ~ 4.5). We identified 9 compression-associated Pc1 waves with frequencies of ~0.5-2.0 Hz. The wave activity appears in the horizontal H (positive north) and D (positive eastward) components. All of events show low coherence between H and D components. This indicates that the Pc1 pulsations in H and D oscillate with a different frequency. Thus, we cannot determine the polarization state of the waves. We will discuss the occurrence location of compression-associated Pc1 pulsations, their spectral structure, and wave properties.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.502-507
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• 2003

The HANARO, multi-purpose research reactor, 30 MWth open-tank-in-pool type, is under normal operation since it reached the initial critical in February 1995. The HANARO is used for fuel performance tests, radio isotope productions, reactor material performance tests, silicone semiconductor productions and etc. Specially, the HANARO is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and is under developing a target handling tool for loading and unloading those at a flow tube (OR-5). The target should be sufficiently cooled in the flow tube without an interference with the cooling of the others and an induction of extremely vibration. This topic is described an analectic analysis for the cooling characteristics of the fission moly-99 target to find the minimum cooling water. It was confirmed through the analysis results that the minimum cooling water, about 2.717 kg/s flew through the flow tube under the worst case that the guide tube got no perforating holes for cooling water to pass through the holes and that the target was safely cooled under about seventy percent (70%) of the maximum allowable temperature of the target.

• KSBB Journal
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• v.26 no.5
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• pp.439-442
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• 2011

1,2-propanediol (1,2-PD) is a commodity chemical that is currently produced from petrochemical derivatives. Saccharomyces cerevisiae is well characterized and a successful industrial microorganism to enable the improvement of the 1,2-propanediol production by metabolic engineering. A recombinant S. cerevisiae M3G3 was used to produce 1,2-propanediol. S. cerevisiae M3G3 is the diploid strain that contains 3 copies of mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase). S. cerevisiae M3G3 was cultivated at various culture conditions by changing culture temperature, glucose concentration, and inducer concentration. Also the effect of induction time was studied to optimize the production of 1,2-propanediol. Batch and fed-batch cultivation of S. cerevisiae M3G3 was performed by using a 5 L jar fermenter. The highest concentration of 1,2-propanediol in batch cultivation was 0.86 g/L and it was further improved to 1.33 g/L in fed-batch cultivation.