• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1512-1518
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• 2009

Recently, new dispersed power sources such as photovoltaics, wind power, fuel cell etc. are energetically interconnected and operated in the distribution systems, as one of the national projects for alternative energy. This paper deals with the optimal countermeasures for the mal-function of protective devices at primary feeder in distribution systems when new power sources like photovoltaic (PV) systems are interconnected, based on the symmetrical components of short circuit studies. When new power sources are considered to be interconnected to distribution systems, bi-directional power flow and interconnection transformer connection of new power sources may cause the operation problems of protective devices (mainly re-closer), since new power sources can change typical characteristics of distribution systems. Therefore, this paper shows an analysis skill of the mal-functional mechanism of protective relay and proposes the optimal solution for the mal-function problem using the symmetrical components of fault analysis. And, this paper also shows the effectiveness of proposed method by the simulation at the field distribution systems.

• Journal of the Korean Society of Safety
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• v.21 no.3 s.75
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• pp.53-58
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• 2006

Following a Mediterranean fruit fly outbreak in South Australia, a bait spray program involving the pesticides like malathion(MAL) was carried out. During the application, dermal exposure was considered for the pest controllers wearing PVC gloves. However there is a lack of information about PVC glove performance like break through times and permeation rates with MAL, therefore, a new analytical method for HPLC-UV was developed. A standard permeation test cell was used in this study. From the results of this study, more than 96% solubility of MAL was provided at 30% isopropyl alcohol in distilled water as a collecting media. However, there was significant decomposition of MAL when the solutions were kept at over $50^{\circ}C$ for 2-3 hours. As a mobile phase, 50% acetonitrile water solution (pH 6.0) gave the greater sensitivity compared with other compositions of acetonitrile solution. The arm section of the gloves had shorter breakthrough times and higher permeation rates compared with the palm. There was no malathion solution breakthrough up to 24 hours using the 1% MAL working strength solution. When the temperature was changed from $22{\pm}1^{\circ}C\;to\;37{\pm}1^{\circ}C$, the breakthrough times were decreased by 14.5% on palm and 37.5% on arm, and permeation rates were increased significantly. The findings of this study indicate that further investigations on used gloves, periods of use and varying working conditions like tasks and seasons should be carried out to assess potential worst case scenarios.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1503-1509
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• 2014

With the purpose of facilitating the process of stable strain generation, a shuttle vector for integration of genes via a double recombination event into two ectopic sites on the Sulfolobus acidocaldarius chromosome was constructed. The novel chromosomal integration and expression vector pINEX contains a pyrE gene from S. solfataricus P2 ($pyrE_{sso}$) as an auxotrophic selection marker, a multiple cloning site with histidine tag, the internal sequences of malE and malG for homologous recombination, and the entire region of pGEM-T vector, except for the multiple cloning region, for propagation in E. coli. For stable expression of the target gene, an ${\alpha}$-glucosidase-producing strain of S. acidocaldarius was generated employing this vector. The malA gene (saci_1160) encoding an ${\alpha}$-glucosidase from S. acidocaldarius fused with the glutamate dehydrogenase ($gdhA_{saci}$) promoter and leader sequence was ligated to pINEX to generate pINEX_malA. Using the "pop-in" and "pop-out" method, the malA gene was inserted into the genome of MR31 and correct insertion was verified by colony PCR and sequencing. This strain was grown in YT medium without uracil and purified by His-tag affinity chromatography. The ${\alpha}$-glucosidase activity was confirmed by the hydrolysis of $pNP{\alpha}G$. The pINEX vector should be applicable in delineating gene functions in this organism.

• Journal of Hydrogen and New Energy
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• v.21 no.2
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• pp.104-110
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• 2010

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. We tried to find out the optimum cell concentration for $H_2$ production in each of the two new Korean nitrogen-fixing unicellular cyanobacterial strains to compare with Synechococcus sp. strain Miami BG043511. The two Korean strains, Cyanothece sp. KNU CB MAL-031 and KNU CB MAL-058, were isolated from Korean west coasts. Cell concentrations up to 17 billion cells $ml^{-1}$ were applied to the tests. High cell concentration over 15 billion cells $ml^{-1}$ resulted in drastically reduced $H_2$ production in all the three strains. The two domestic strains, however, produced 2-3 time more hydrogen than Synechococcus sp. Miami BG043511 at cell concentrations of 5-10 billion cells $ml^{-1}$. At lower cell concentrations than 2 billion cells $ml^{-1}$, MAL-031 exhibited highest $H_2$ production followed by Miami BG043511, with far less production in MAL-058. Present result suggests that Cyanothece sp. MAL-CB031 might be one of the ideal nitrogen-fixing unicellular cyanobacterial strains for the photobiological hydrogen production.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.43-50
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• 2021

A newly cloned 4-α-glucanotransferase (αGT) from Deinococcus geothermalis and two typical bacterial αGTs from Thermus scotoductus and Escherichia coli (MalQ) were investigated. Among 4 types of catalysis, the cyclization activity of αGTs that produces cycloamylose (CA), a valuable carbohydrate making inclusion complexes, was intensively studied. The new αGT, DgαGT, showed close protein sequence to the αGT from T. scotoductus (TsαGT). MalQ was clearly separated from the other two αGTs in the phylogenetic and the conserved regions analyses. The reaction velocities of disproportionation, cyclization, coupling, and hydrolysis of three αGTs were determined. Intriguingly, MalQ exhibited more than 100-fold lower cyclization activity than the others. To lesser extent, the disproportionation activity of MalQ was relatively low. DgαGT and TsαGT showed similar kinetics results, but TsαGT had nearly 10-fold lower hydrolysis activity than DgαGT. Due to the very low cyclizing activity of MalQ, DgαGT and TsαGT were selected for further analyses. When amylose was treated with DgαGT or TsαGT, CA with a broad DP range was generated immediately. The DP distribution of CA had a bimodal shape (DP 7 and 27 as peaks) for the both enzymes, but larger DPs of CA quickly decreased in the DgαGT. Cyclomaltopentaose, a rare cyclic sugar, was produced at early reaction stage and accumulated as the reactions went on in the both enzymes, but the increase was more profound in the TsαGT. Taken together, we clearly demonstrated the catalytic differences between αGT groups from thermophilic and pathogenic bacteria that and showed that αGTs play different roles depending on their lifestyle.

• Research in Mathematical Education
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• v.16 no.1
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• pp.1-13
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• 2012

This paper explores gifted students' reasoning abilities. Three tests were developed in order to assess and analyze their reasoning abilities building on previous research on covariational reasoning. Giving consideration to the arising problems in the tests, we constructed a LOGO-based JavaMAL microworld environment which engages students in an active learning environment. This environment was designed by applying 'instrumental approach' in microworld. Based upon the post test results, the role of activity in microworld environment as 'instrument mediated activity' is also discussed.

• Research in Mathematical Education
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• v.18 no.4
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• pp.289-305
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• 2014

The current mathematical education calls for a learning environment from the constructionism perspective that actively creates mathematical objects. This research first analyzes JavaMAL's expression 'move' that enables students to express the agent's behavior constructively before they learn vector as a formal concept. Since expression 'move' is based on a coordinate, it naturally corresponds with the expression of vectors used in school mathematics and lets students take an embodied approach to the concept of vector. Furthermore, as a design tool, expression 'move' can be used in various activities that include vector structure. This research studies the educational significance entailed in JavaMAL's expression 'move'.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.225-228
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• 2001

RhRnBp and Peysn5 are the proteins related to carbohydrate synthesis. RhRnBp originated form human was expressed as inclusion body in E. coli. Peysn5 originated form actinomadura was expressed as low level and inclusion body in E. coli. Ub, Trx, MalE and NusA is used as fusion partner to RhRnBp and Peysn5. The solubility of all fusion protein is NusA > MalE> Trx > Ub. Expression level of RhRnBp fusions in $37^{\circ}C$ is higher than that in $25^{\circ}C$. However in the case of Peysn5. Expression levels in $25^{\circ}C$ were higher. MalE fusion had highest activity in RhRnBp fusions. There were no activity in Peysn5.

• KSBB Journal
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• v.26 no.3
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• pp.183-188
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• 2011

Adult stem cells, which have characteristic of self-renewal and multipotency, are specialized cell types, responsible for the tissue regeneration of the damaged tissue. Recent studies suggest that stem cells senescence (or stem cells' ageing) is closely associated with the variety of ageing-related phenotypes such as tissue atrophy, degenerative diseases and onset of cancers. During ageing, declining of stem cells function and subsequently occurring mal-differentiation of stem cells would be important to understand the biological process of development of ageing-related phenotypes such as tissue degenerations and cancers. This review focuses on the DNA damage stress as a cause of senescence of stem cells and their mal differentiation, which is closely link to defect of regeneration potentials and neoplastic transformation. Understanding of molecular mechanisms governingsuch events is likely to have important implications for developing novel avenues for balancing tissue homeostasis longer period of time, further leading to 'Healthy ageing'.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.59-63
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• 2008

Rapid production of therapeutic proteins such as angiostatin and endostatin angiogenic inhibititors has been highly demanded for cancer treatment. In this regard, recombinant human angiostatin and endostatin were successfully expressed as soluble forms by maltose binding protein (MBP)-mediated fusion expression in Escherichia coli. PCR amplified, angiostatin and endostatin genes from human placenta cDNA library were inserted into an expression vector pMAL-c2e to construct prokaryotic expression vectors, pMAL-c2e/AS and pMAL-c2e/ES, respectively. Recombinant angiostatin and endostatin were efficiently expressed in E. coli origami (DE3) after IPTG induction and protein expression were confirmed by SDS-PAGE analyses. The expressed recombinant proteins were purified near homogenity using an amylose affinty column chromatography. In contrast that previous E. coli expressions were all insoluble, our results first time demonstrated that MBP fused human angiostatin and endostatin were soluble in E. coli.