보이드 생성기구에 의한 복합조직강의 연성 파괴거동에 관한 연구

吳澤烈,崔明振,楡龍錫,金松正 慶熙大學校 材料科學技術硏究所 1993 材料科學技術硏究論集 Vol.6 No.-

Ductile Fracture of Dual Pase Steel begins with void nucleation, at Martensite-Ferrite interface or deformed Martensite particle. In this study void nucleation, void growth, void volume fraction and void coalescence at given strain were studied in dual phase steel. Therefore, by means of the heat treatment of low corbon steel the study deal with void nucleation and void growth for ferrite grain sizeof dual phase steel. Void nucleaton and void growth with increasing strain are shown depend upon the ferrit grain size. The number of voids and volume fraction of voids generary increase as ferrite grain size decrease. At the close to fracture the void coalescence in the direction of the applied tensile stress, but near the fracture surface they linked in direction transverse to the tensile axis.

회전익 항공기용 외활형식 착륙장치의 정ㆍ동적 분석에 관한 연구

유용석,이동명,채경덕,오택열 경희대학교 산학협력기술연구원 1996 산학협력기술연구논문집 Vol.2 No.-

It is important to make sure of design's reasonability concerning of structural vibration problems and safety with fulfilling the research and with analyzing the body structures that include the landing gear which has dynamic significant characteristics in helicopter, and to make systematical procedure which obtains engineering data to guarantee the quality of the helicopter that was developed by testing of parts, subsystems and body. In this study, Analysis of landing gear under FAR regulations was attempted, and systematical procedure for static and dynamic characteristics of the landing gear in many subsystems of the helicopter was classified.

벼 무논골뿌림栽培時 播種期 및 立毛數가 生育 및 收量에 미치는 影響

洪性澤,朴栽成,朴成圭,李尙榮,池在浚,孫錫龍 충북대학교 농업과학기술연구소 1999 農業科學硏究 Vol.16 No.-

This study was conducted to establish the cultural techniques of the puddled-soil drill seeding of race (Oryza sativa L.), which is one of the efficient labor saving cultural methods, in the central part of Korea. Seoanbyeo was seeded at three times from April 10 to May 20 with the 20 day interval in 1994. The number of seedling stands per m2 at each seeding date were 50, 90, 130 and 170. The tillering characteristics, lodging characters, dry matter production, yield components and yield were investigated. The number of days to the maximum tillering stage was reduced at the later seeding date. It was 70, 55 and 25 days in seedings on April 10, April 30 and May 20, respectively. The critical effective tillering stage was also shortened at the delayed seeding. The higher the number of seedling stands was, the higher number of tillers, the shorter duration to the maximum tillering stage and the earlier critical effective tillering stage were resulted. The number of tillers was higher at the earlier seeding date. The number of tillers was increased in the order of 50, 90, 130 and 170 seedling stands per m2. The ratios of effective tillers were 53, 61 and 63% at seeding on April 10, April 30 and May 20, respectively. The ratios were not significantly different at April 10. But the ratios in seeding on April 30 and May 20 were reduced as the number of seedling stands was increased. The weight of stem base related to lodging was the highest with 2.01g/10 plants in the optimum seeding on April 30, while it was 1.59g/10 plants in the late seeding on May 20. It was also decreased as the number of seedling stands was increased. The dry weights at 30 days before the heading stage were increased at the later seeding, while the dry weight at the heading stage was the highest at seeding on April 30 which is considered as the adequate seeding time. The dry weights at 30 days before the heading stage were increased as the number of seedling stands was increased and they were increased up to 130 seedling stands per m2 at the heading stage. The length of panicle exsertion was shortened at the later seeding. The length of panicle exsertion was increased up to 130 seedling stands. but it was shorter at 170 seedling stands. The heading dates were later at seeding on April 30 and May 20 than at seeding on April 10. They were not remarkedly different among seeding dates at 50 seedling stands, it was earlier at the higher number of seedling stands over 90. The number of spikelets per panicle was decreased at the higher number of seedling stands. The ratio of ripened grains was higher at earlier seeding than at later seeding. It was not significantly different among the number of seedling stands at the same seeding time. Yields at seeding on April 30, April 10 and May 20 were 644, 624 and 551kg/10a, respectively. The seeding on April 30, the optimum seeding time, resulted the highest yield. Rice quality was decreased due to the increase of the green kerneled rice as the seeding date was delayed.

적층각 변화에 따른 복합재료 회전익의 구조적 연성에 관한 연구

변창환,유용석,오택열 경희대학교 산학협력기술연구원 1997 산학협력기술연구논문집 Vol.3 No.-

This study is made allowance for using one dimensional modeling method that extracts equivalent stiffness matrix used the reduction of degree of freedom in order to sufficiently express the cross section of rotor blade and the material properties of composite. Modern helicopter rotor blade which are made from anisotropic material is very important a subject on the tailoring based on coupling tearms by changing of ply angle. In basing on this, we have searched for coupling terms by changing of ply angle of composite rotor blade and the dynamic behaviour of rotor blade for each coupling term.

PECVD법으로 증착된 전자소자용 thiophene 박막의 전기화학적 신뢰성에 관한 연구

김정구,박진택,최윤석,부진효,유용재 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.6

The corrosion failure of electronic devices has been a major reliability concern lately. This failure is an ongoing concern because of miniaturization of integrated circuits(IC) and the increased use of polymers in electronic packaging. In this paper plasma-polymerized thiophene films were considered as a possible candidate for an interlayer dielectric for multilever metallization of ultra large scale integrated (ULSI) semiconductor devices. The protective ability of above films as a function RF power in an 3.5 wt.% NaCl solution was examined by electrochemical methods and contact angle measurement. The protective efficiency of the film increased with increasing RF power, which induced the higher degree of cross-linking and hydrophobicity of the films.

Al-Zn-Mg-Cu-Zr 합금의 집합조직 발달과 기계적 특성에 미치는 Sc 첨가의 영향

제창웅,진승준,정동석,임성택,이용연,박노진 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.10

The texture and mechanical properties during fabrication processes - extrusion, cold rolling and aging treatment - of plate in the 7050 Al alloys without/with 0.1%Sc were investigated. In both the cross section(CS) and longitudinal section(LS) of the specimen without Sc, after cold rolling, texture of R-fiber was predominant. In the Sc added alloy after cold rolling, {112}<111>(Cu)+weak (123)<634>(S) texture components developed in the CS of the specimen while strong (3-fiber+(110)<001>(Goss) components developed in the LS of the specimen. After solution treatment and aging treatment, the alloy (CS and LS) without Sc had random texture, but by the alloys with the 0.1%Sc, the components of the rolling texture are not changed. After the aging treatment, hardness and tensile strength of the alloy with 0.1%Sc increased about 15% and 17%, respectively, than those without Sc. Tensile strength of the Sc added specimen was the highest along the rolling direction where the <111> texture was strongly developed. On the other hand, in the specimen without Sc, the mechanical properties were not dependent on the direction of the sample. (Received May 3, 2004)

벼 乾沓直播栽培時 播種期가 乾物生産에 미치는 影響

朴栽成,朴成圭,李尙榮,洪性澤,池在浚,趙東三,孫錫龍 충북대학교 농업과학기술연구소 1999 農業科學硏究 Vol.16 No.-

This experiment was carried out to obtain indispensable information to establish comprehensive cultural method of rice in direct seeding on dry paddy at Chungbuk Agricultural Research and Extension Services. Effect of seeding date on dry matter production, yield components and yield were studied. Seeding on May 5 ensured the highest maximum number of tillers, while transplanting on May 20 gave the highest rate of effective tillers. Number of effective tillers was greater in the order of Hwajinbyeo, Hwaseongbyeo, Daekwanbyeo. Lengths of upper three leaves were increased at later seeding, but leaf width was not affected by seeding date. Ratio of leaf blade weight was higher in earlier seeding during 30 days before heading but was higher in later seeding during 30 days after seeding, and was higher in the order of Hwajinbyeo, Hwaseongbyeo, Daekwanbyeo. CGR, RGR and NAR were not significantly different among seeding dates during 30 days before heading, but were lower in later seeding during 30 days after seeding. LAR was not affected by seeding date during 30 days before heading, but was higher at seeding on May 5 in heading date and during 30 days after heading. Dry weight of leaf blade, leaf sheath and culm, ear and total biomass during 30 days before heading and heading were highest in May 5 seeding. Daekwanbyeo and Hwaseongbyeo in May 5 seeding and Hwajinbyeo in April 20 seeding brought the highest yield with greater number of spikelets, higher ripening ratio and greater 1,000 grain weight, and harvest index and grain/straw ratio were Increased at earlier seeding. There were significantly positive correlations between number of panicles per m2 and LAI at 30 days before heading and heading, dry matter weight of leaf blade and total mass at heading. On the other hand, there were significantly negative correlations between seeding date and ripened grain ratio. 1,000 grain weight and yield, and between 1,000 grain weight and leaf length of 2nd, respectively.

벼 무논골뿌림裁培時 播種期가 生育 및 收量에 미치는 影響

池在浚,朴裁成,朴成圭,李尙榮,洪性澤,孫錫龍 충북대학교 농업과학기술연구소 1999 農業科學硏究 Vol.16 No.-

This study was carried out to determine the optimum seeding date for the rice(Oryza sativa L.) cultivation of the puddled-soil drill seeding, which is one of the efficient labor saving cultural methods, at the central part of Korea. Namweonbyeo, Anjungbyeo and Ilpumbyeo were seeded on four dates from April 10 to May 25, 1994 with the 15 day interval in the paddy field. In order to examine the adequate seeding date, the growth characters, yield components and yields were investigated. The coleoptile emerged 1 or 2 days earlier in Namweonbyeo than in Anjungbyeo and Ilpumbyeo, and later seeding resulted earlier coleoptile emergence. The number of seedling stands were higher in the order of Namweonbyeo, Anjungbyeo and Ilpumbyeo, was increased at the later seeding and was 81 to 88 seedlings on April 10 seeding. The plant height, number of leaves, number of tillers and dry weight at 50 days after seeding of all three cultivars were higher at later seeding. Leaf area index(LAI) were higher in the order of Ilpumbyeo, Anjungbyeo and Namweonbyeo. LAIs at the heading stage, at 30 days after heading and at 30 days before heading were higher in that order. The dry matter weight at the 30 days before heading was higher in sheath and stem than that in leaf blade, while, at heading stage, it was higher in the order of sheath and stem, leaf blade and panicle. On the other hand, at 30 days after heading, it was higher in the order of panicle, sheath and stem and leaf blade. The number of panicles per m2 was greater in the order of Ilpumbyeo, Anjungbyeo and Namweonbyeo. The ratio of ripened grain was reduced as the later seeding date. Its ratio was higher in Namweonbyeo than in Anjungbyeo and Ilpumbyeo. Yield of Namweonbyeo was lower than those of Anjungbyeo and Ilpumbyeo. Yield was decreased as the seeding date was delayed. Namweonbyeo showed the highest yield at seeding on May 10, while Anjungbyeo and Ilpumbyeo showed at seeding on April 25. The seeding date was negatively correlated with the ratio of ripened grain. while the number of seedling stands was positively correlated with the number of panicle per m2.

An Efficient Finite-Difference Time-Domain Algorithm to Simulate the Absorbed Energy of Nonflat Layers or Particles of Thin-Film Solar Cells

Seok Yong Byun,Seok-Joo Byun,Dongwoo Sheen,Taek-Sung Lee IEEE 2015 IEEE journal of photovoltaics Vol.5 No.4

<P>We propose an efficient and accurate finite-difference time-domain (FDTD) algorithm to simulate the absorbance of a thin-film solar cell containing nanometer particles or nonflat layers. This algorithm can extract a closed boundary for an arbitrarily shaped object, with the solar cell model being discretized into a set of Yee's cells to construct the FDTD system. Using this information, we can distinguish the closed boundaries of the components (e.g., particles or layers) of the solar cell and accurately calculate the absorbance of each particle or layer. Moreover, using the closed line (in 3-D, surface) integration instead of the area (in 3-D, volume) integration enables faster calculation and requires less memory.</P>

SYNCHRONIZATION ON THE POINTS OF TURN-OFF TIME OF SERIES-CONVECTED POWER SEMICONDUCTOR DEVICES USING MILLER EFFECT

Eun-Yong Shim,Hong-Taek Yong,Beom-Seok Seo,Dong-Seok Hyun 전력전자학회 1992 ICPE(ISPE)논문집 Vol.1992 No.4

The large value of the snubber capacitor is needed to protect the devices in high voltage converters using series-connected pover semiconductors. But that re­sults m more losses and longer commutation times. So, the new technique of series connection is required, which can minimize the value of snubber capacitor and also promote the reliability of high voltage converters.<br/> We study on the switching characteristics of series-connected pover semiconductors and then propose a novel switching algorithm for series connection vhich is able to implement not only the dynamic voltage balancing in spite of the difference of switching characteristics but the minimization of the value of snubber capacitor,through the change of the value of snubber capacitor by Miller effect. Finally, we illustrate the validity of this synchronization by computer simuiation and experimental results.<br/>