• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.438-446
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• 2020

Meju and nuruk (respectively soybean and malt) are traditional Korean fermentation starters that are vulnerable to contamination by harmful microorganisms such as aflatoxigenic fungi and their associated aflatoxins (AFs). In this study, Aspergillus spp. were isolated and identified from a total of 57 meju and 18 nuruk samples collected from Korean markets. Their potential aflatoxigenicity was investigated by examining the presence of three aflatoxin biosynthetic genes (aflO, aflP, and aflR) using multiplex polymerase chain reaction (mPCR) assays. Thereafter, aflatoxin production of isolates and the natural occurrence of AFs in meju and nuruk samples were analyzed by high-performance liquid chromatography (HPLC). A total of 177 Aspergillus isolates were identified and 130 isolates were obtained from meju samples. Of these, 25 isolates (19.2%) contained all three aflatoxin biosynthetic genes, and five (20%) of these isolates produced aflatoxins. Forty-seven of the Aspergillus isolates were obtained from nuruk samples, five of which (10.6%) expressed all three AF biosynthetic genes; however, none of these strains produced AFs. HPLC analysis showed that 88% (51/58) of the meju samples and 39% (7/18) of nuruk samples were not contaminated with AFs (below limit of detection). Among the isolates isolated from meju and nuruk, there were aflatoxigenic strains containing all three aflatoxin biosynthetic genes or producing aflatoxin in medium, but the frequency of aflatoxin contamination was low in the meju and nuruk samples.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.420-422
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• 2005

TMC (Tautomycetin) is a liner polyketide immunosuppressive antifungal compound produced by Streptomyces spp. Inhibition of T cell proliferation with TMC was observed highly efficient at 100-fold lower than those needed to achieve maximal inhibition with cyclosporin A. To elucidate the biosynthetic pathway of TMC, a genomic DNA library was constructed using a E. coil-Streptomyces shuttle cosmid vector, pOJ446. The DNA libraries were screened by colony blot hybridization using several polyketide ${\beta}-ketosynthase$ (KS) probes amplified from TMC-producing Streptomyces genomic DNA using polymerase chain reaction (PCR), of which the degenerate primers were designed based on the highly conserved sequences present in KS domains of various type I polyketide synthase genes in Streptomyces species. This library construction and screening approach led to the isolation of several positive cosmid clones representing type I polyketide biosynthetic gene clusters. In addition, a Streptomyces regulatory gene called afsR2 (a global regulatory gene stimulating antibiotic production in both S. coelicolor and S. lividans) was successfully integrated into the TMC-producing Streptomyces chromosome via E. coil-Streptomyces heterologous conjugation mehtod. The more detailed results of production improvement and genetic characterization of TMC-producing Streptomyces spp. will be discussed.

• Journal of Magnetics
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• v.6 no.4
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• pp.132-141
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• 2001

The switching characteristics and the magnetization-flop behavior in magnetic tunnel junctions exchange biased by synthetic antiferromagnets (SyAFs) are investigated by using a computer simulations based on a single-domain multilayer model. The bias field acting on the free layer is found to be sensitive to the thickness of neighboring layers, and the thickness dependence of the bias field is greater at smaller cell dimensions due to larger magnetostatic interactions. The resistance to magnetization flop increases with decreasing cell size due to increased shape anisotropy. When the cell dimensions are small and the synthetic antiferromagnet is weakly, or not pinned, the magnetization directions of the two layers sandwiching the insulating layer are aligned antiparallel due to a strong magnetostatic interaction, resulting in an abnormal magneto resistance (MR) change from the high-MR state to zero, irrespective of the direction of the free-layer switching. The threshold field for magnetization-flop is found to increase linearly with increasing antiferromagnetic exchange coupling in the synthetic antiferromagnet. Irrespective of the magnetic parameters and cell sizes, magnetization flop does not exist near zero applied field, indicating that magnetization flop is driven by the Zeeman energy.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.1
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• pp.51-57
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• 2004

Objective: To investigate whether polymorphism of gene encoding COMT is associated with the risk of endometriosis in Korean women. Methods: We investigated 136 patients with histopathologically confirmed endometriosis rAFS stage III/IV and 251 control group women who were surgically proven to have no endometriosis. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of PCR products were done to determine each participant's COMT genotype. Results: The distribution according to NIaIII genetic polymorphisms of COMT were as follows. $COMT^{HH}$, $COMT^{HL}$, and $COMT^{LL}$ genotypes were 56.6% (77 women), 34.6% (47 women) and 8.8% (12 women) in the study group and 50.6% (127 women), 39.4% (99 women) and 10.0% (25 women) in the control group. There was no significant difference between the study group and the control group. Conclusion: The results suggest that COMT genetic polymorphism may not be associated with the development of endometriosis in Korean women.

• Smart Structures and Systems
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• v.13 no.4
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• pp.615-636
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• 2014

Aluminium Foam Sandwich (AFS) panels are becoming always more attractive in transportation applications thanks to the excellent combination of mechanical properties, high strength and stiffness, with functional ones, thermo-acoustic isolation and vibration damping. These properties strongly depend on the density of the foam, the morphology of the pores, the type (open or closed cells) and the size of the gas bubbles enclosed in the solid material. In this paper, the vibrational performances of two classes of sandwich panels with an Alulight(R) foam core are studied. Experimental tests, in terms of frequency response function and modal analysis, are performed in order to investigate the effect of different percentage of porosity in the foam, as well as the effect of the random distribution of the gas bubbles. Experimental results are used as a reference for developing numerical models using finite element approach. Firstly, a sensitivity analysis is performed in order to obtain a limit-but-bounded dynamic response, modelling the foam core as a homogeneous one. The experimental-numerical correlation is evaluated in terms of natural frequencies and mode shapes. Afterwards, an update of the previous numerical model is presented, in which the core is not longer modelled as homogeneous. Mass and stiffness are randomly distributed in the core volume, exploring the space of the eigenvectors.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.18-18
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• 2017

ISO11783은 농업 산업분야 통신 프로토콜의 국제 표준으로, 농용트랙터 및 작업기 ECU 간의 통신 프로토콜을 표준화한다. 이 표준은 서로 다른 제조사의 제품 간에 호환성을 갖게 하며, 정밀 농업에 대한 핵심 기반을 제공한다. 현재 해외에서는 이미 ISO11783 기반의 AFS(Advanced Farming System)를 통한 정밀농업이 상용화되어 농가에 보급되고 있다. 이에 비해, 국내에서 이러한 표준을 따르는 농기계들은 미비한 실정이며, 향후 농업의 정밀 농업화를 통한 고부가가치 창출 및 선진국의 무역 장벽에 대비와 해외 수출 판로 개척을 위해 ISO11783 표준에 대한 R&D가 필요로 한다. 이에 IsoAgLib를 분석하고 임베디드 보드에 Porting하여 ISO11783 기반 작업기 ECU를 구현하였고, 이를 기반으로 ISO11783 기반 작업기 ECU의 구현 방법을 발표한다. IsoAgLib의 시스템 아키텍처는 계층화 되어 있어, 타겟에 의존적인 계층만 수정하여, IAR 환경에서 Cortex M3 보드에 포팅을 완료하였다. 작업기 ECU들은 자신만의 인터페이스 화면을 갖으며, 이를 Object pool이라 한다. 이것을 Virtual Terminal(VT)에 업로드 하여, VT가 해당 작업기 ECU의 사용자 인터페이스 기능을 제공하도록 한다. 이에 작업기 ECU 구현 1 단계로, 'VT-Designer'를 통하여 Object pool를 설계한다. 2 단계, 'vt2iso'를 통해서 Object pool을 IsoAgLib 상에서 사용할 수 있도록 변환한다. 3 단계, 포팅된 IsoAgLib project에 변환된 파일을 포함 시킨다. 4 단계, 작업기 ECU의 주기적인 작업 및 각 메시지 수신시 수행할 작업을 코딩한다. 5 단계, 빌드 및 타겟 보드에 업로딩 한 후, New Holland 사의 $Intelliview^{TM}$ iv display (VT)과 연결하여 동작을 확인한다. 확인 결과로 VT에 디자인한 Object pool이 표시 되며 soft key 입력 시 작업기 ECU에서 LED가 변한다. 결론적으로, 연구 결과를 바탕으로 ISO11783 기반의 작업기 ECU의 디자인 및 구현이 가능하며, 이를 통해 향후 국내의 ISO11783 기반의 작업기 ECU의 개발에 도움을 줄 수 있다.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.2
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• pp.85-95
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• 2006

Objective: To investigate whether polymorphisms of gene encoding CYP1B1 is associated with the risk of endometriosis in Korean women. Methods: We investigated 199 patients with histopathologically confirmed endometriosis rAFS stage III/IV and 183 control group women who were surgically proven to have no endometriosis. The genetic distribution of four different CYP1B1 polymorphisms at $G^{119}-T$, $G^{432}-C$, $T^{449}-C$, and $A^{453}-G$ were analyzed by polymerase chain reaction(PCR) and restriction fragment length polymorphism of PCR products. Results: We found no overall association between each individual CYP1B1 genotype and the risk of endometriosis. The odds ratio of genotype GG/GC+GG/TC+TT/AA compared to GG/CC/CC/AA(reference) was calculated as 2.06 with a 95% confidence interval of 1.003~4.216. Conclusion: This results suggest that CYP1B1 genetic polymorphism may be associated with development of endometriosis in Korean women.