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공공청사 아트리움공간의 공공성에 관한 연구- 청사 아트리움의 공공성 평가와 디자인 요소 도출을 중심으로 -
최혁열,최윤경,전영훈 한국문화공간건축학회 2014 한국문화공간건축학회논문집 Vol.- No.46
This Study aimed to analyze the evaluation of publicness and deduction of cultural design elements in government office and to conduct basic design elements for the cultural space design. The main users of government offices were divided by public citizens and private officials, and atrium is a core space which formulate the boundary areas between them. So, the openness of Atrium could be an index of publicness of government office. For it, this study researched domestic and foreign case studies between 1950’ to contemporary architecture and could found out that the domestic atrium compositions were far from the concept of publicness and openness. For foreign case studies, this study selected 4 european city halls which were constructed recently. Finally, we can found out five basic design elements for publicness of atrium space in government office. Those are accessibility, occupying ability, event connectivity, affair connectivity and visibility between public and private area.
Fe_(73.5)Cu₁Nb₃Si_(13.5)B_(9) 초미세 결정립 합금의 분말코아 특성
노태환,최혁열 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.6
The melt-spun Fe_(73.5)Cu₁Nb₃Si_(13.5)B_(9) ribbons so called Finemet alloy were annealed in the temperature range of 490 to 610℃ for 1 h and milled by using a planetary ball mill into the powders with the size of 250~850 sm. Then the powder cores were produced through the blending of the magnetic powders with the 5 wt% of ceramic insulator and cold compaction. Further the annealing responses of magnetic, electrical properties and microstructure were investigated. At the annealing temperature of 550℃, the microstructure was transformed from amorphous to crystalline a-Fe phase with the grain size of 10.7 nm, and the electrical resistivity of 117 μΩ-㎝ was obtained. At the same time, the effective permeability and quality factor reached 120 and 50, respectively, and the permeability persisted up to about 500 kHz. Moreover the core loss at the frequency of 50 kHz and the magnetic induction of 0.1 T was about 300 mW/cm³. These magnetic properties were comparable to the conventional powder core materials such as MPP(molybdenum permalloy powder), Sendust etc. However the dc bias characteristics represented by the permeability stability upon dc magnetic field superposition were found to be unsatisfactory. (Received February 16, 2004)
Fe73.5Cu₁Nb₃Si15.5B7 나노 결정립 합금 분말 코아의 자기적 특성
노태환(T. H. Noh),최혁열(H. Y. Choi),안상재(S. J. Ahn) 한국자기학회 2004 韓國磁氣學會誌 Vol.14 No.1
The annealing-temperature dependence of magnetic properties in compressed powder cores being composed of ball-milled Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 alloy powders (size : 250~850 ㎛) and 5 wt% of ceramic insulators has been investigated. When annealed at 550 ℃ for 1 h and so transformed to α-Fe phase nanocrystalline structure with the grain size of 11 ㎚ (electrical resistivity : 110 μΩ·㎝), the highest effective permeability of 125 and quality factor of 53 were obtained, and the permeability persisted up to about 500 ㎑. Further the core loss measured at the frequency of 50 ㎑ and the induction amplitude of 0.1 T was very low (230 ㎽/㎤). However the dc bias characteristics was not satisfactory as compared to that of conventional powder core materials(MPP, Sendust etc.). The inferior dc bias property of Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 alloy powder cores was attributed to the fact that the size of powder was too large for obtaining the same permeability with that of conventional materials.
FeCuNbSiB 나노결정립 합금 분말코아의 자기적 특성에 미치는 절연체의 영향
노태환(T. H. Noh),최혁열(H. Y. Choi) 한국자기학회 2004 韓國磁氣學會誌 Vol.14 No.5
The variation of magnetic properties with insulating materials(glass frits, talc and polyamide) in compressed powder cores composed of Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 nanocrystalline alloy powders(size : 250~850 ㎛) and 3 wt% insulators has been investigated. Larger permeability was obtained at the frequency lower than 300~400 ㎑ for the powder cores including ceramic insulators(glass frits and talc) as compared to the cores with polyamide, while at higher frequency than 1 ㎒ the permeability of the former cores decreased rapidly. Further the cores with ceramic insulators showed larger core loss and smaller peak quality factor attained at lower frequency. On the contrary, the powder cores with polyamide exhibited high stability of permeabilities up to several ㎒ and superior core-loss and quality-factor properties. Moreover the de bias property was better in the wide field range for the cores having polyamide. The enhanced magnetic properties of polyamide-added cores were attributed to the more sufficient electrical insulation between magnetic particles, where the higher insulation state was considered to be obtained from the larger volume fraction of polyamide in the powder cores.
철계 비정질 합금 분말코아의 자기적 특성에 미치는 분말 제조방식의 영향
노태환(T. H. Noh),최혁열(H. Y. Choi) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.3
In the fabrication process of Fe-based amorphous alloy powder cores by pulverization of the melt-spun ribbons and cold compaction, the effects of powder preparation method on the magnetic & electric properties, powder shapes and microstructure of cores have been investigated. The powder cores made by using rotor mill showed low effective permeability as compared to the cores prepared by ball milling. However the frequency dependence and quality factor properties were superior in the case of rotor-milling. Further the powders prepared by rotor mill had homogeneous and round shapes through strong shearing in the sieve ring, while the ball milled powders were inhomogeneous and relatively small. The lower permeability of the powder cores fabricated with rotor mill was considered to be due to the high internal stress occurred by very intensive shearing. Moreover the powder cores produced by rotor-milling showed lower core loss and good frequency dependence of effective permeability possibly due to the higher electrical insulation between magnetic particles. The dc bias property of the powder cores made by rotor-milling was better than the one by ballmilling.