• 농촌지도와개발
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• 제7권1호
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• pp.75-100
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• 2000

In the 21th century, many people predict the change of agricultural conditions in our country because of the arrival of knowledge- information age. Now it is supposed that agricultural technology comes to $45%{\sim}50%$ level compare to advanced countries. So the development of new technology in agriculture are demanded all the more. Agriculture in the 21th century will be grown based on the connection of environment, knowledge and taffeta. The agricultural conditions in Kyongbuk has more profitablity and potentiality, because there are wide lands, distinguished 4 seasons, various main production crops and cultural inheritance etc. For the innovation of agricultural technology in Kyungbuk, province this plan presented 7 visions; such as foods-life, knowledge-brain, precisious environment, resouces-saving, export-market, traditional- specialization and development-participation agriculture and 7 basic strategies; such as environment-stabilization, speciality-discrimination, standard-modeliztion, demand-market, field-practicality, management-information, specialization-cooperation strategy. The major contents of this plan were presented to achieve strengthen -ment and advancement of competitive power on the agriculture of Kyongbuk; 21 superme technologies get to develop the highest technique, 21 major conventional projects will be mown continuously, 21 main clops snakes to intensify competitive power. Wheras, we will be propulsed 21 special projects for increasing a phase of Kyongbuk R D. A. and we inculuded 74 items of Si-Gym region for balanced development of area This plan consisted of 1,730 items in 84 fields and about 260 billion won will be invest every year. When it is finished successfully in 10 years, agricultural technical level of Kyungbuk will be not only promote to $80{\sim}90%$ level to advanced country, but also clanged to competitive industry, and farming villiages might be changed to a space of comfortable life.

• 한국자기학회지
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• 제12권2호
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• pp.57-63
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• 2002

Nd-Fe-B계 소결자석의 특성을 향상시키기 위해서는 Nd-Fe-B계 합금의 조성 및 제조공정을 조절하여 자성분말의 입도 및 입도분포, 강자성상인 N $d_2$F $e_{14}$B상의 분율, 자성분말의 배향도, 산소 함량, grain size 등과 같은 factor들을 최적화 하여야 한다. 본 연구에서는 실험실 규모로 Nd-Fe-B계 합금 조성 및 공정 조절을 통하여 Nd-Fe-B계 소결자석을 제조하는 연구를 수행하였으며, 분쇄매체 분쇄시간 및 ball size에 따른 Nd-Fe-B계 소결자석의 자기적특성을 분석하여 최적의 분쇄조건을 조사하였다. 또한 분쇄공정 중 FeGa합금을 첨가하여 잔류자속밀도의 감소없이 Nd-Fe-B계 소결자석의 보자력을 향상시킬 수 있었다. 이와 같은 분쇄 조건의 연구, FeGa 합금에 의한 보자력 향상, 건식분쇄 방법 및 powder blending 공정을 적용하여 잔류자속밀도( $B_{r}$,) : 14.4kG, 보자력($_{i}$ $H_{c}$) : 9.4kOe, 최대자기에너지적((BH)$_{\max}$) : 47 MGOe의 자기적 특성을 갖는 Nd-Fe-B계 소결자석을 제조하였다.

• Archives of Pharmacal Research
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• 제24권5호
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• pp.455-465
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• 2001

The highly potent cytotoxic DNA-DNA cross-linker consists of two cyclopropa[c]pyrrolo[3,4-3]indol-4(5H)-ones insoles [(+)-CPI-I] joined by a bisamido pyrrole (abbreviated to "Pyrrole"). The Pyrrole is a synthetic analog of Bizelesin, which is currently in phase II clinical trials due to its excellent in vivo antitumor activity. The Pyrrole has 10 times more potent cytotoxicity than Bizelesin and mostly form DNA-DNA interstrand cross-links through the N3 of adenines spaced 7 bp apart. The Pyrrole requires a centrally positioned GC base pair for high cross-linking reactivity (i.e., $5^1$-T$AT_2$A*-$3^1$), while Bizelesin prefers purely AT-rich sequences (i.e., $5^1$-T$AT_4$A*-$3^1$, where /(equation omitted) represents the cross-strand adenine alkylation and A* represents an adenine alkylation) (Park et al., 1996). In this study, the high-field $^1$H-NMR and rMD studies are conducted on the 1 1-mer DNA duplex adduct of the Pyrrole where the 5′(equation omitted)TAGTTA*-3′sequence is cross-linked by the drug. A severe structural perturbation is observed in the intervening sequences of cross-linking site, while a normal B-DNA structure is maintained in the region next to the drug-modified adenines. Based upon these observations, we propose that the interplay between the bisamido pyrrole unit of the drug and central C/C base pair (hydrogen-bonding interactions) is involved in the process of cross-linking reaction, and sequence specificity is the outcome of those interactions. This study suggests a mechanism for the sequence specific cross-linking reaction of the Pyrrole, and provides a further insight to develop new DNA sequence selective and distortive cross-linking agents.

• 공업화학
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• 제5권1호
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• pp.127-138
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• 1994

CTA(cellulose triacetate) 막을 이용한 물과 에탄올의 투과증발(pervaporation) 막분리에서 수착과 투과실험으로부터 용해-확산 투과기구modeling 및 그 함수형과 parameters에 대한 해석을 시도하였다. 순성분들의 수착 data를 사용하여 Flory-Huggins 식으로 계산한 3 성분계(에탄올/물/CTA) 수착평형 조성을 추산하여 실측치와 비교하였다. 막 내부의 조성과 액상의 평형 조성간에 열역학적 평형 관계식을 적용하기 위해 막 내 겉보기 활동도를 Wilson식과 Van Laar식으로 상관시켰다. 투과속도식은 한 성분의 투과속도가 그 성분의 막 내 농도구배에 비례하며, 또한 확산계수의 농도 의존성이 에탄올 농도만의 지수함수라고 가정하여 물과 에탄을 투과속도를 계산하였으며 이는 실측치와 잘 일치하였다. 한 성분의 투과속도와 수착량이 다른 성분에 비해 현저히 작은 경우에는 대류항을 무시할 수 없음을 알았고, 온도가 높고, 투과측 압력이 낮을수록 투과속도와 투과선택도가 증가하였다.

• Progress in Superconductivity
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• 제6권2호
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• pp.118-123
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• 2005

A low cost YBCO oxide powder was employed as a starting precursor for MOD process. YBCO oxide is advantageous over metal acetates or TFA salts which are popular starting precursors for conventional MOD-TFA process because that YBCO oxide precursor is cheap and easy to control molar ratio. YBCO thin films were prepared by this oxide-precursor-based MOD process and annealing condition was optimized. The YBCO thin film annealed at below $780^{\circ}C$ shows no transport $I_c$ and poor microstructure. Raman spectroscopic study of YBCO thin film indicates that YBCO thin film prepared at below $780^{\circ}C$ contains a number of imperfections such as non-superconducting $BaCuO_2$ phase, cation disorder, etc. However, the YBCO thin film treated at above $800^{\circ}C$ shows improvement in microstructure and current transport properties. This research was supported by a grant from Center for Applied Superconductivity Technology of the 21st Century Frontier R&D Program funded by the Ministry of Science and Technology, Republic of Korea.

• Progress in Superconductivity
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• 제11권2호
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• pp.83-86
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• 2010

There are theoretical and experimental evidences for the pseudo-gap in electron doped cuprates being due to interaction between electrons and anti-ferromagnetism(AFM). A remaining issue is on how AFM correlates with pseudo-gap, and eventually with superconductivity. To elucidate the issue, we have performed temperature dependent angle-resolved photoemission studies of an e-doped cuprate superconductor $Sm_{2-x}Ce_xCuO_4$(SCCO) x=0.18 at 20K and 150K. In the case of $Nd_{2-x}Ce_xCuO_4$, the most well known e-doped cuprate, pseudo-gap disappears at around 100 K for x=0.17. Our experimental result reveals that the pseudo-gap of SCCO exists even at 150K for x=0.18. This result implies that the AFM of SCCO survives even in x=0.18, which agrees with previously reported phase diagram of SCCO. Yet, the superconductivity disappears around x=0.18 for both NCCO and SCCO in spite of the difference in the magnetic order. This result sheds a light on the disappearance of superconductivity on the over-doped side.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.237-242
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• 2014

이 논문은 발전소에서 설치 운전 중인 6.6kV 고전압 케이블이 시간에 따라 성능이 악화되는 현상의 추세를 결정하는 수명지수를 파악하기 위한 논문이다. 우리가 연구한 케이블 시스템은 설치 후 13 년 동안 운전하고 있다. 삼상전력에 연결되는 변류기, 온도센서 LPF 등을 이용한 측정장치를 개발하여 케이블의 절연저항 변화 특성을 해석하였다. 고전압 22kV 케이블과 비교하면 절연체의 두께가 더 두껍기 때문에 특성을 다르게 나타낸다. 동작시간이 경과함에 따라, 절연저항이 계속 감소하지 않음을 확인 하였다. 일정한 값으로 감소하다가 더 이상 감소하지 않고 상하진동하는 특성을 나타내었다. 지난 13 년 동안의 열화과정을 파악할 수 없었지만, 시스템이 안정 상태에서 동작을 하였다는 사실은 열화가 아직 발생하지 않았다는 의미이다. 이런 경우에는, 수명지수를 예측할 수 없기 때문에 케이블의 수명을 정량적으로 예측할 수 없음을 확인하였다.

• Carbon letters
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• 제8권4호
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• pp.326-334
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• 2007

In this study, graphite composites were fabricated by warm press molding method to realize commercialization of PEM fuel cells. Graphite composites have been considered as alternative economic materials for bipolar plate of PEM fuel cells. Graphite powder that enables to provide electrical conductivity was selected as the main substance. The graphite powder was mixed with phenolic resin and the mixture was pressed using a warm press method. First of all, the graphite powder was pulverized with a ball mill for the dense packing of composite. As the ball milling time increases, the average size of particles decreases and the size distribution becomes narrow. This allows for improvement of the uniformity of graphite composite. However, the surface electrical resistivity of graphite composite increases as the ball milling time increases. It is due to that graphite particles with amorphous phase are generated on the surface due to the friction and collision of particles during pulverizing. We found that the contact electrical resistivity of graphite particles increases as the particle size decreases. The contact electrical resistivity of graphite powders was reduced due to high molding pressure by warm press molding. This leads to improvement of the mechanical properties of graphite composite. Hydrogen gas impermeability was measured with the graphite composite, showing a possibility of the application for bipolar plate in fuel cell. And, I-V curves of the graphite composite bipolar plate exhibit a similar performance to the graphite bipolar plate.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권1호
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• pp.52-58
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• 2006

Single-electron transistor (SET)-based logic cells and SET/FET hybrid integrated circuits have been fabricated on SOI chips. The input-output voltage transfer characteristic of the SET-based complementary logic cell shows an inverting behavior where the output voltage gain is estimated to be about 1.2 at 4.2K. The SET/FET output driver, consisting of one SET and three FETs, yields a high voltage gain of 13 and power amplification with a wide-range output window for driving next circuit. Finally, the SET/FET literal gate for a multi-valued logic cell, comprising of an SET, an FET and a constant-current load, displays a periodic voltage output of high/low level multiple switching with a swing as high as 200mV. The multiple switching functionality of all the fabricated logic circuits could be enhanced by utilizing a side gate incorporated to each SET component to enable the phase control of Coulomb oscillations, which is one of the unique characteristics of the SET-based logic circuits.

• 한국주조공학회지
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• 제25권1호
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• pp.16-22
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• 2005

This study aims to investigate the effects of the microstructures and nodule type on the fatigue characteristics of cast iron. Fatigue tests were carried out in tension-tension mode using a servo-hydraulic testing machine with load control mode operating at a frequency of 15 Hz. The tests were conducted at stress ratio R=Kmin/Kmax, of 0.1. Initial crack ${\Dalta}K$ values were highly performed with increase in tensile strength of DCI fatigue specimens. ${\Dalta}K_{th}$ region, fatigue crack propagation was primarily advanced through cell boundary and in periphery of near nodule. Fatigue crack propagation rate of D2 consisted with 2Phase(Ferrite+Pearlite) was slow due to crack closure enhanced by crack deflection and occurred crack branching. The generation of crack branch was occurred due to interaction of crack-nodule. At Threshold and Paris zone, the fractographs of the fatigue fracture surface for DCI show typical striations of a ductile fracture and isolated cleavage planes near graphite. The effect of microstructure on fatigue crack propagation of GC strongly depends on the type of flake. The generation of crack branch occurred due to interaction of crack-nodule. The fractographs of the fatigue fracture surface for GC show cleavage plane along the flake graphite.