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A study on Improvement of Critical Current for Bi-2223 HTS Tapes (Bi-2223 고온초전도 선재의 임계전류 향상에 관한 연구)

  • 하홍수;정종만;이남진;장현만;하동우;오상수;권영길;류강식
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2000.02a
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    • pp.3-5
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    • 2000
  • Among the various processing techniques used in HTS wire fabrication, the PIP(Powder In Tube) method is currently one of the most promising for applications on an industrial scale. In this study, we have fabricated Bi-2223/Ag superconducting tapes using the modified PIT process, where several process factors were changed and improved, ie., powder packing, drawing, rolling and heat treatment. We obtained Bi-2223 tape that have high critical current, 46 a at 77.3 K, have high critical current, 46A at 77.3 K, self field although the tape was not pressed but only rolled. The critical current of 100m class long length tape was measured 21.6A at the same criterion. Besides, the critical current of Bi-2223/Ag tape was measured applying magnetic fields with different directions at various temperatures.

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Capacity Analysis of MMR(Mobile Multihop Relay) System (MMR(Mobile Multihop Relay) 시스템의 용량 분석)

  • Lee, Kang-Won;Kook, Kwang-Ho;Choi, Song-In
    • IE interfaces
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    • v.21 no.2
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    • pp.189-197
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    • 2008
  • This study shows achievable capacity gain from the MMR system. Relay stations are placed along the cell boundary in tiers. We can have as many tiers of relays and as many relays in each tier as we want. A model is developed, which can estimate the system capacity varying the number of relays in each tier and the bandwidths allocated to the BS and the RS. It is shown that maximum capacity increases are 21.5% and 18.9% when we have relays in the first tier only and in the first and the second tiers, respectively.

Strategies of the Knowledge and Information Services for Vulnerable Classes in Public Libraries (공공도서관의 지식정보 취약계층서비스 전략)

  • Yoon, Hee-Yoon
    • Journal of Korean Library and Information Science Society
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    • v.43 no.2
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    • pp.53-75
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    • 2012
  • In recent years, many studies on the public library services for individual vulnerable groups have been performed in Korea. From the standpoint of public libraries with limited human and physical resources, however, all proposed alternatives are difficult to accommodate due to overload and in an integrated perspective, the several alternatives have a logical contradiction and possibility of realistic conflicts. Focusing on these facts, this study proposed an integrated direction and strategic plan to strengthen knowledge and information services of public libraries for five vulnerable classes, ie., the disabled persons, multi-cultural families, the elderly, rural residents, basic living subsidies.

Coincidences of composites of u.s.c. maps on h-spaces and applications

  • Park, Seh-Ie;Kim, Hoon-Joo
    • Journal of the Korean Mathematical Society
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    • v.32 no.2
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    • pp.251-264
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    • 1995
  • Applications of the classical Knaster-Kuratowski-Mazurkiewicz (si-mply, KKM) theorem and the fixed point theory of multifunctions defined on convex subsets of topological vector spaces have been greatly improved by adopting the concept of convex spaces due to Lassonde [L1]. In this direction, the first author [P5] found that certain coincidence theorems on a large class of composites of upper semicontinuous multifunctions imply many fundamental results in the KKM theory.

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PREFERRED ORIENTATION AND MICROSTRUCTURE OF MOD DERIVED SrBi$_{2x}$Ta$_2$O$_9$ THIN FILMS WITH Bi CONTENT x

  • Yeon, Dae-Joong;Park, Joo-Dong;Oh, Tae-Sung
    • Journal of the Korean institute of surface engineering
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    • v.29 no.6
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    • pp.621-627
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    • 1996
  • $SrBi_{2x}TaO_9$ ferroelectric thin films were prepared on platinized silicon substrates using MOD proces, and crystallization behavior of the films was investigated with variation of the annealing temperature and Bi content x. Crystalline phase of bismuth layered perovskite structure was formed even by baking the films at $800^{\circ}C$ for 5 minutes in air, and was not changed by annealing at temperatures raning from $700^{\circ}C$ to $900^{\circ}C$ for 1 hour in oxygen ambient. When $SrBi_{2x}TaO_9$ thin films ($0.8\lex\ie1.6$) were annealed at $800^{\circ}C$, Preferred orientation of the films along c-axis was observed with $x\ge1.2$. With increasing Bi content x, surface morphology of the films was changed from equiaxed grains to elongated grains.

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Optimum Maintenance Strategy of Bridges Based on System Reliability (시스템 신뢰성에 기초한 교량의 최적 유지관리 계획)

  • Yang, Seung Ie
    • Journal of Korean Society of Steel Construction
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    • v.14 no.5 s.60
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    • pp.627-639
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    • 2002
  • Bridge construction is almost complete in many countries. Thus, the government and highway agencies change their focus from constructing to maintaining. Effectively maintaining bridges require predicting their lifespan using a system reliability viewpoint. Likewise, maintenance models based on the system reliability concept should be developed. Thus, this study developed maintenance models for preventive maintenance and essential maintenance using system reliability and lifetime distributions. The optimal maintenance strategy for an existing bridge was obtained using the developed maintenance models.

Etude sur Ie Costume de Style d'Empire -De 1789 $\`{a}$ 1815 en France- (Empire Style의 복장에 관한 연구 -프랑스의 1789~1815년을 중심으로-)

  • Kim Ok Jin
    • Journal of the Korean Society of Clothing and Textiles
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    • v.5 no.2
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    • pp.1-12
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    • 1981
  • Nous avons essaye, dans cette etude, de deceler les caracteristiques de la silhouette du style d'Empire en eclairant it la fois le processus de sa formation ai travers La Monarchie, La Republique, Le Directoire, Le Consulat et l'Empire. Nous avons souligne comme suit: En premier lieu, comme les caracteristiques generaux, la simp lification et la democratisation. En second lieu, comme celles de La Monarchie et de La Republique, la transformation renovatrice en forme grossiere du style cylindriforme de la mode d'epoque ancienne. En troisieme lieu, comme celles du Directoire, la formation de l'unite esthetique au haut degre et les lignes naturelles du corps. En quatrieme lieu, comme celles du Consulat et de l'Empire, l'achevement du style d'Empire d'ornement somptueux refletant l'autorite politique de l'Empereur.

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A Literature study on the Erythema nodosum (結節 紅斑에 對한 文獻的 考察)

  • Kim, Hae-Jung;Chae, Bhung-Yoon
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.10 no.1
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    • pp.39-49
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    • 1997
  • Erythema nodosum is a nodular erythematous eruption usually limited to the low extremities. Erythema nodosum seems to be Gwadungjun(瓜藤纏) and Damp-heat flow(濕毒流注) in oriental medicine. The symptom of erythema nodosum is similar to that of Gwadungjun, so we investigated the literatures of oriental medicine and recet medicine. The results were summarized as follows; 1. In Oriental medicine, erythema nodosum regarded as Damp-heat flow and Gwadungjun. 2. Inflammatory nodus of lower extremity, ie, similar to Gwadungjun, Damp-heat flow, Bichonbal(비천發), Samnibal(三里發), Ududok(魚두毒), etc. 3. Erythema nodosum results from inner damp-heat(內有濕熱), affection due to pathogenic wind(外感風邪). 4. Treatment is to clear away heat(淸熱), remove dampness(利濕), heat from blood(凉血), cold-damp(祛寒), and promote blood flood(活血通絡). 5. We can use Bangpungtongsungsan(防風通聖散), Sopunghwa1hyultang(疏風活血湯), and Danguijumtongtang(當歸拈通湯), etc.

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Characterization of Creep-Fatigue Crack Growth Behavior for HAZ Crack Using {TEX}$C_{t}${/TEX} ($C_t$를 사용한 용접열영향부 균열의 크리프-피로 균열성장거동 특성화)

  • 백운봉;서창민;윤기봉
    • Journal of Welding and Joining
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    • v.18 no.6
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    • pp.89-95
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    • 2000
  • Creep-fatigue crack growth behavior at the heat affected zone of 1Cr-0.5Mo steel weldment has been experimentally studied. Load hold times of the tests for trapezoidal fatigue waveshapes were varied among 0, 30, 300 and 3,600 seconds. Time-dependent crack growth rates were characterized by the {TEX}$C_{t}${/TEX} estimated with the equation proposed by the previous finite element analysis work. It was concluded that the {TEX}$C_{t}${/TEX} values calculated from the properties of parent metal were quite comparable to the accurate {TEX}$C_{t}${/TEX} values calculated from both of weld and parent metals. Scatter of data was claimed due to the difference of exact location of the cracks in HAZ. The cracks have a tendency to change their path from the original location eventually to the relatively soft HAZ(ie, near-FGHAZ region, fine grained heat affected zone).

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A Study on Response Time Index for Sprinkler Head (스프링클러 헤드의 응답시간지수 측정)

  • 태순호;이병곤
    • Journal of the Korean Society of Safety
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    • v.5 no.3
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    • pp.51-55
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    • 1990
  • This study describes the engineering approach adopted to investigate sprinkler head during the early stage of a fire when they are subjected to convective heating and low gas velocities. Comparions are made between the parameters derived using basic methods, ie. ramp test, for evaluating sprinkler parameters(time constant, response time index) is illustrated. Evidence is presented that the propotion of heat loss by conduction from a sprinkler element may very typically employed in the rate of rise test. This fact alone may justfy the precautionary need to perform a limited number of rate of rise tests to confirm a sprinklers capacity to function correctly in reasonably unfavourable yet realistic conditions. The work is aimed primarily at meeting the needs of sprinkler industry.

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