• 한국초전도ㆍ저온공학회논문지
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• 제15권1호
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• pp.45-50
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• 2013

Closed-loop J-T (Joule-Thomson) refrigeration cycle is advantageous compared to common open loop $N_2$ decompression system in terms of nitrogen consumption. In this study, two closed-loop pure $N_2$ J-T refrigeration systems with sub-atmospheric device for cooling High Temperature Superconductor (HTS) power cable are investigated. J-T cooling systems include 2-stage compressor, 2-stage precooling cycle, J-T valve and a cold compressor or an auxiliary vacuum pump at the room temperature. The cold compressor and the vacuum pump are installed after the J-T valve to create sub-atmospheric condition. The temperature of 67 K is possible by lowering the pressure up to 24 kPa at the cold part. The optimized hydrocarbon mixed refrigerant (MR) J-T system is applied for precooling stage. The cold head of precooling MR J-T have the temperature from 120 K to 150 K. The various characteristics of cold compressor are invstigated and applied to design parameter of the cold compressor. The Carnot efficiency of cold compressor system is calculated as 16.7% and that of vacuum pump system as 16.4%. The efficiency difference between the cold compressor system and the vacuum pump system is due to difference of enthalpy change at cryogenic temperature, enthalpy change at room temperature and different work load at the pre-cooling cycle. The efficiency of neon-nitrogen MR J-T system is also presented for comparison with the sub-atmospheric devices. These systems have several pros and cons in comparison to typical MR J-T systems such as vacuum line maintainability, system's COP and etc. In this paper, the detailed design of the subcooled $N_2$ J-T systems are examined and some practical issues of the sub-atmospheric devices are discussed.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
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• pp.230.2-230
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• 2003

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1563-1567
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• 2007

AfsKav is a eukaryotic-type serine/threonine protein kinase, required for sporulation and avermectin production in Streptomyces avermitilis. In terms of their ability to complement SJW4001 (${\Delta}afsK$-av), afsK-av mutants T165A and T168A were not functional, whereas mutants T165D and T168D retained their ability, indicating that Thr-165 and Thr-168 are the phosphorylation sites required for the role of AfsKav. Expression of the S-adenosylmethione synthetase gene promoted avermectin production in the wild-type S. avermitilis, yet not in the mutant harboring T168D or T165D, demonstrating that tandem phosphorylation on Thr-165 and Thr-168 in AfsKav is the mechanism modulating avermectin production in response to S-adenosylmethione accumulation in S. avermitilis.

• 한국전자현미경학회:학술대회논문집
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• 한국현미경학회 2001년도 제32차 추계학술대회
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• pp.100-101
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• 2001

• 한국자기학회지
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• 제5권5호
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• pp.376-379
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• 1995

Employing the muffin-tin-orbital theory combined with pseudo-potential concepts, we have evaluated hybridization matrix elements between R and T sites in $RT_{2}$ compounds. The matrix elements are calculated with two parameters, the interatomic distance between R and T atoms from the crystal structure data, and the expectation values of the radial distances for the radial wave functions of the ground state charge densities, which are obtained from the linearized muffin-tin orbital band method within the local density approximation. It is found that the R 4f/T 3d hybridization matrix elements decrease with an increasing atomic number from R=Ce to Gd, and that they are smaller in $RNi_{2}$ than in $RCo_{2}$, which are consistent with trends observed in recent photoemission spectroscopy experiments. It is also found that the magnitudes of the hybridization matrix elements in $RFe_{2}$ are comparable to those in $RNi_{2}$.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6357-6362
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• 2013

Background: The C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) has been associated with acute lymphoblastic leukemia (ALL). However, results were conflicting. The aim of this study was to quantitatively summarize the evidence for the MTHFRC677T polymorphism and ALL risk. Methods: Electronic searches of PubMed and the Chinese Biomedicine database were conducted to select case-control studies containing available genotype frequencies of C677T and the odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of any association. Results: Case-control studies including 6,371 cases and 10,850 controls were identified. The meta-analysis stratified by ethnicity showed that individuals with the homozygous TT genotype had decreased risk of ALL (OR= 0.776, 95% CI: 0.687~0.877, p< 0.001) in Caucasians (OR= 0.715, 95% CI: 0.655~0.781, p= 0.000). However, results among Asians (OR=0.711, 95% CI: 0.591~1.005, p= 0.055) and others (OR=0.913, 95% CI: 0.656~1.271, p= 0. 590) did not suggest an association. A symmetric funnel plot, the Egger's test (P=0.093), and the Begg- test (P=0.072) were all suggestive of the lack of publication bias. Conclusion: This meta-analysis supports the idea that the MTHFR C677T genotype is associated with risk of ALL in Caucasians. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between the MTHFRC677T polymorphism and ALL.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.75-75
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• 2003

• 한국전자통신학회논문지
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• 제7권4호
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• pp.693-705
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• 2012

최근 들어 기술협력의 필요성은 세계 각국에서 점점 더 증대하고 있는데, 이러한 기술개발을 위한 국제적 협력은 비용과 위험을 분산시키며, 또한 개발된 기술의 오용을 방지하고, 기업의 해외시장접근을 용이하게 하는 주요한 방법이기 때문이다. 현재 한국의 과학기술외교는 과학과 기술혁신의 기초를 강화하기 위한 관련 기술들을 보장하는데 목적을 두고, 과학기술에 있어서의 국제협력에 중점을 두고 있다. 사실상, 이러한 과학기술 관련 국제협력은 거버넌스 이슈로서, 기업들을 국제화하는 것에 연계되지만, 한국의 중소기업 같은 작은 회사에 있어, 일정기간 동안 보다 우위의 기술적 이점을 유지하는 것은 쉽지 않으며, 나아가 한국의 중소기업은 축적된 정보와 경험이 제한된 이유로 국제 R&D 역시 어려운 실정이다. 따라서 이러한 상황을 타개하고자, 본고는 한국 중소기업의 기술적 이점을 유지하는 그리고 과학기술의 국제협력을 강화하는, 역할조정자(혹은 역할자)로서 '중소기업 코디네이터'라는 새로운 개념을 제안한다. 곧 본고의 '중소기업 코디네이터'는 한국중소기업의 산업에 있어서의 R&D국제화를 위한 국제적인 과학기술협력을 조력하기 위한 목적에서, 적당한 파트너와 능력 있는 종업원에 대한 적합한 정보를 제공할 뿐만 아니라, '닫힌 혁신'이 아닌 '열린 혁신'으로 이끈다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2005년도 동계학술연구발표회 및 2차 아시안포럼
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• pp.217-217
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• 2005

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.133-133
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• 1999

We have fabricated and tested a simple circuit of the rapid single-flux-quantum(RSFQ) four-stage shift register using a single layer high-T$_c$ superconducting (HTS) YBa$_2Cu_3O_{7-x}$ (YBCO) thin film structure with 9 step-edge Josephson junctions. The circuit includes two read superconducting quantum interference devices(SQUID) and four stages. To establish a robust HTS RSFQ device fabrication process, we have focussed the reproducible process of sharp and straight step-edge formation as well as the ratio of film thickness to step height t/h. The spread of step-edge junction parameters was measured from each13 junctions with t/h=l/3, l/2, and 2/3 at various temperatures. We have demonstrated the simplified operation of the shift register at 65 K..