코발트계 극박형 비정질합금의 형성과 자기적 성질

노태환(Tae-Hwan Noh) 한국자기학회 1998 韓國磁氣學會誌 Vol.8 No.5

Fabrication condition and magnetic properties of ultrathin Co-based amorphous alloy have been investigated. When the ejection gas pressure was lower than 0.05 ㎏f/㎠ at the roll speed of 55 m/s, ultrathin ribbons with the thickness less than 10 ㎛ were successfully obtained. The ribbon thickness decreased linearly with the decrease in ejection pressure. Moreover the significant decrease in ribbon width was accompanied with the decrease of thickness in the range of ejection pressure to form an ultrathin ribbon. This behavior was attributed to the decrease of effective ejection pressure in the both end-sides of rectangular nozzle due to the larger friction between molten metal and nozzle wall. The effective permeability at low frequency (1 ㎑) decreased largely with the decrease in ribbon thickness, while the coercive force increased with the thickness decrease. It was considered that these behaviors were due to the enhancement of surface effect leading to the suppression of wall motion. However effective permeability at high frequency (1 ㎒) increased with the decrease in ribbon thickness, and this was ascribed to the easier magnetization rotation owing to the reduction of eddy current.

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.

가스 분무법으로 제조된 NixFe100-x(x=40~50) 퍼멀로이 분말 및 압분 코아의 자기적 특성

노태환(T. H. Noh),김구현(G. H. Kim),최광보(G. B. Choi),김광윤(K. Y. Kim) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.6

We investigated the magnetic properties of High Flux-type Ni_xFe_(100-x)(x=40~50, wt.%) permalloy powders and dust cores. The powder was prepared by conventional gas atomization in mass production scale. At the composition of Ni_(45)Fe_(55), saturation magnetization was maximum. In case of lower Ni content than X=45, the Ms decreased largely with the decrease in Ni content, which is due to the invar effect. The permeability of compressed powder cores increased with the decrease in Ni content, which was considered to be due to the decrease in the magnetostriction. In addition, the dust core with Ni=45% showed the lowest core loss because of the increase in electrical resistivity leading to the low eddy current loss. From the better frequency dependence of permeability, larger Q value and superior DC bias characteristics of Ni=45 % than those of Ni=50% core, it was confirmed that the 45%Ni-55%Fe powder alloy was better material for the dust core than commercial High Flux core materials.

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.

고 비정질 형성능을 가진 FeBSiNb 합금 리본의 자기적 특성

노태환(Tae-Hwan Noh),김구현(Gu-Hyun Kim) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.4

Amorphous FeBSiNb alloy ribbons having bulk glass forming ability and high saturation magnetic flux density were produced by single-roller melt spinning apparatus in the thickness range of 22~102㎛. With the increase of thickness, the coercive force and squareness ratio decreased, while maximum permeability and AC permeability increased. However electrical resistivity was almost constant. Furthermore refined and complex magnetic domain structure was observed in thicker ribbons owing to the change in internal magnetic anisotropy. For the alloy with the thickness of 81㎛, small coercive force of 24 mOe and high effective permeability of 12,000 at 1 ㎑ were obtained, those are considered to be better comparing to the conventional soft magnetic amorphous alloys (~20㎛). The good soft magnetic properties of the thick FeBSiNb amorphous alloys were attributed to the decrease in surface pinning effect during wall motion, appearance of perpendicular anisotropy and resulted domain refinement.

Fe78Si9B₁₃ 비정질 합금의 쵸크 코어 특성에 미치는 열처리 효과

노태환(Tae-Hwan Noh),장완희(Wan-Hee Jang) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.5

With the object of developing a non-gap choke core, effects of annealing in oxygen atmosphere on magnetic properties for Fe_(78)Si_9B₁₃ amorphous alloy were investigated. After annealing for 2 hrs at 440℃, optimum magnetic properties for choke core were obtained, where the effective permeability was 180 and was almost constant up to several ㎒, and the decrease in permeability upon large DC bias current of 12 A or DC bias magnetic field of 8,000 A/m was very little. Moreover the AC magnetic loss was very low as compared to the conventional choke cores. Upon the optimum annealing, the magnetic hysteresis loop was inclined accompanying the increase of coercive force and the appearance of fine crystallites of α-Fe phase. The good choke core properties was considered to be due to the suppression of domain boundary motion and domain refinement by the crystallites.

연구논문 : 자연과학; 정량 PCR을 이용한 벼 흰잎마름병균 밀도 측정

노태환 ( Tae Hwan Noh ),강미형 ( Mi Hyung Kang ),서수좌 ( Su Joa Seo ),심형권 ( Hyeong Kwon Shim ),최만영 ( Man Young Choi ),박종철 ( Jong Chul Park ),백채훈 ( Chae Hoon Paik ),김형무 ( Hyung Moo Kim ) 한국국제농업개발학회 2013 韓國國際農業開發學會誌 Vol.25 No.2

Real Time PCR을 이용한 벼 흰잎마름병균의 밀도를 측정할 수 있는 새로운 방법을 개발하였다. Real Time PCR을 이용하여 벼 흰잎마름병을 예찰하기 위하여 TaqMan MGB probe를 이용한 프라이머인 Xan_PahgeF & Xan_PahgeR primer와 Xan_Pahge FAM MGB probe를 제작하였으며, 높은 특이성이 인정되었다. 병원균 배양액, 벼 흰잎마름병원균의 DNA, 병원세균에 오염된 물에서도 효과적으로 검출이 되었다. 농수로물이나 관개수에서 벼 흰잎마름병균의 밀도를 측정할 때 정량 PCR의 저해인자 제거 후 신속하게 벼 흰잎마름병균의 밀도를 측정할 수 있다. We developed a new measurement method for the density of Xanthomonas oryzae pv. oryzae(Xoo), a casual pathogen of bacterial leaf blight of rice. The new method used real time PCR with the highly characterized and specific Xan_PahgeF & Xan_PahgeR primer and Xan_Pahge FAM MGB probe primer pairs derived from phage-related integrase gene. The method was effective when tested with a variety of templates including isolated Xoo DNA, pure colonies or liquid culture sources, and could also work on contaminating water. A main advantage of this assay is to accurately and rapidly quantitate the population density of Xoo in paddy field water containing inhibitors.

비정질합금 자기센서

노태환(T. H. Noh) 한국자기학회 1997 韓國磁氣學會誌 Vol.7 No.4

급냉응고에 의한 연자성합금의 (軟磁性合金) 제조와 그 특성

노태환 ( Tae Hwan Noh ) 대한금속재료학회 1991 大韓金屬學會會報 Vol.4 No.4

강원도 대관령 목장 현존식생 및 식물군집구조

노태환 ( Tai Hwan Noh ),한봉호 ( Bong Ho Han ),김종엽 ( Jong Yup Kim ),이민영 ( Min Young Lee ),유기준 ( Ki Joon Yoo ) 한국환경생태학회 2013 한국환경생태학회지 Vol.27 No.5

본 연구는 온대 북부 기후대에 위치한 강원도 대관령 목장 산림생태계의 현존식생, 식물군집구조, 천이계열 특성과 보전가치를 밝히고, 향후 복원 및 관리계획 수립 시 필요한 기초자료를 제공하고자 수행하였다. 현존식생은 총 56개 유형으로 분류되었고, 조사면적 19,397,361㎡ 중 신갈나무가 우점하는 지역은 7,669,593㎡(39.1%), 1차 초지 지역은 4,785,417㎡(24.7%), 신갈나무-낙엽활엽수군집이 우점하는 지역은 2,182,276㎡(11.3%)이었다. 조사구는 20m×20m (400㎡) 28개소를 설정하였으며, DCA분석 결과 군집 Ⅰ(소나무-신갈나무군집), 군집 Ⅱ(신갈나무-소나무군집), 군집 Ⅲ(신갈나무군집), 군집 Ⅳ(신갈나무-낙엽활엽수군집), 군집 Ⅴ(낙엽활엽수군집), 군집 Ⅵ(팥배나무군집) 등 6개의 식물군집으로 분류되었다. 표본목 수령은 군집 Ⅰ은 57~62년생, 군집 Ⅱ는 41~77년생, 군집 Ⅲ은 47~108년생, 군집 Ⅳ는 47~82년생, 군집 Ⅴ는 47년생, 군집 Ⅵ은 55년생으로 전체적으로 41~108년생이었다. 대관령 목장의 생태적 천이는 소나무군집에서 신갈나무군집으로 발달하고 있는 것으로 예측되었으며, 계곡부를 중심으로 낙엽활엽수군집도 분포하고 있었다. 단위면적 400㎡당 샤논의 종다양도지수를 분석한 결과, 군집 Ⅳ(0.8203~1.1439) → 군집 Ⅲ(0.8019~1.1375) → 군집 Ⅴ(1.0993) → 군집 Ⅰ(0.9475~1.0797) → 군집 Ⅱ(0.6896~1.0324) → 군집 Ⅵ(0.9909) 순으로 높았다. This study was carried out to investigate the actual vegetation, the structure of plant community, and ecological succession sere of forest ecosystem in temperate northern climate zone, Daegwallyeong Ranch, Gangwon-do (Province) and to offer the basic data for planning of the forest managemant. As a result of analysis of actual vegetation, vegetation types divided into 56types and the area of survey site was 19,397,361㎡. The ratio of vegetation type dominated by Quercus mongolica forest was 39.1%, primary grassland was 24.7%, Quercus mongolica-Deciduous broad-leaved forest was 11.3%. Twenty eight plots (size is 20m×20m) were set up and the results analyzed by DCA which in one of the ordination technique showed that the plant communities were divided into six groups which area community Ⅰ (Pinus densiflora-Quercus mongolica community), community Ⅱ (Quercus mongolica-Pinus densiflora community), community Ⅲ (Quercus mongolica community), community Ⅳ (Quercus mongolica-Deciduous broad-leaved community), community Ⅴ (Deciduous broad-leaved community), community Ⅵ (Sorbus alnifolia community). The age of community Ⅰwas ranged from 57 to 62 years old, that of community Ⅱ was ranged from 41 to 77 years old, community Ⅲ was ranged from 47 to 108 years old, community Ⅳ was ranged from 47 to 82 years old, community Ⅴ was 47 years old, community Ⅵ was 55 years old, thus we supposed that the age of the study site is about from 41 to 108 years old. The Ecological succession is predicted from Pinus densiflora community to Quercus mongolica community and Deciduous broad-leaved were distributed in the center of the valley in Daegwallyeong Ranch. According to the index of Shannon``s diversity (unit: 400㎡), community Ⅳ was ranged from 0.8203 to 1.1439, community Ⅲ was ranged from 0.8019 to 1.1375, community Ⅴ was 1.0993, community Ⅰ was ranged from 0.9475 to 1.0797, community Ⅱ was ranged from 0.6896 to 1.0324, community Ⅵ was 0.9909.