• Korean Journal of Metals and Materials
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• v.47 no.9
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• pp.533-541
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• 2009

Materials used for a reactor pressure vessel(RPV) are required high strength and toughness, which determine the safety margin and life of a reactor. Ni-Mo-Cr low alloy steel shows better mechanical properties than existing RPV steels due to higher Ni and Cr contents compared to the existing RPV steels. The present study focuses on effects of Ni, Cr contents on the cleavage fracture toughness of Ni-Mo-Cr low alloy steels in the transition temperature region. The fracture toughness was characterized by a 3-point bend test of precracked Charpy V-notch(PCVN) specimens based on ASTM E1921-08. The test results indicated that the fracture toughness was considerably improved with an increase of Ni and Cr contents. Especially, control of Cr content was more effective in improving fracture toughness than manipulating Ni content, though Charpy impact toughness was changed more extensively by adjusting Ni content. These differences between changes in the fracture toughness and that in the impact toughness were derived from microstructural features, such as martensite lath size and carbide precipitation behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.386-392
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• 2021

Multiferroics exhibiting the coexistence and a possible coupling of ferromagnetic and ferroelectric order are attracting widespread interest in terms of academic interests and possible applications. However, room-temperature single-phase multiferroics with soft ferromagnetic and displacive ferroelectric properties are still rare owing to the contradiction in the origin of ferromagnetism and ferroelectricity. In this study, we demonstrated that sizable ferromagnetic properties are induced in the ferroelectric bismuth ferrite-barium titanate system simply by introducing Co ions into the A-site. It is noted that all modified compositions exhibit well-saturated magnetic hysteresis loops at room temperature. Especially, 70Bi_0.95Co_0.05FeO₃-30Ba_0.95Co_0.05TiO₃ manifests noticeable ferroelectric and ferromagnetic properties; the spontaneous polarization and the saturation magnetization are 42 µC/cm² and 3.6 emu/g, respectively. We expect that our methodology will be widely used in the development of perovskite-structured multiferroic oxides.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.1-10
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• 2002

The aim of this research was to investigate the manufacturing possibility of the paper sludge-synthetic fiber-wood fiber composite. Three levels of the formulation of paper sludge, synthetic fiber and wood fiber (5:5:90, 15:15:70, 25:25:50), two types of adhesive (PMDI, urea-formaldehyde resin) and three levels of density(0.7, 0.8, 0.9) were designed. From the test result, composites with similar or better properties, when compared with commercial fiberboard, appeared to be possible by the addition of up to 30~50% paper sludge and synthetic fiber into wood fiber.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.284-288
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• 1993

Low temperature magnetic properties and crystal structures of melt-spun $Sm_{2}Co_{7}B_{3}$ compound were characterized. The magnetic measurements in the temperature range 77 K~450 K indicated that a spin-reorientation took place at about 150~160 K. A large anisotropy was observed(Ha=135 kOe at 300 K, 725 kOe at 77 K) for $Sm_{2}Co_{7}B_{3}$ although the magnetic moment is rather low. The crystal structure of the $Sm_{2}Co_{7}B_{3}$ compound was analyzed in detail by Rietveld analysis of powder diffraction pattern, and it was revealed that B(4h) atoms are not placed in the Sm(2e) layer but in between the Sm(2e) and Co($6i_{1}$) layers.

• The Science & Technology
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• v.32 no.2 s.357
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• pp.80-81
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• 1999

20여년동안 수소저장합금분야 연구에만 매달려온 전남대 금속공학과 박충년교수. 수소저장합금은 미래의 청정에너지로 각광을 받고 있는데 박교수는 수소저장합금 분말로 구리도금하여 금속수소화물 전극을 제조하는 방법에 대한 특허를 갖고 있다. 박교수는 전남대 자동차연구소 기능재료실장과 한국수소에너지학회 편집위원장을 맡고 있다.

• The Science & Technology
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• v.31 no.3 s.346
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• pp.55-60
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• 1998

인류문명사에서 새로운 소재는 언제나 기술혁신의 방아쇠구실을 해 왔다. 예컨대 20세기 중반 반도체의 발견은 오늘날 컴퓨터를 포함한 정보통신 기술의 비약적인 발전을 가져왔고 초내열합금의 개발로 초음속 제트기 시대의 막이 오르게 되었다. 재료과학기술은 새로운 소재를 창조하고 신소재는 다시 새로운 기술을 만들어 내면서 기술혁신은 모든 분야로 번져 나간다. 21세기에는 부서지기 전에 스스로 알아서 바로잡을 수 있는 강철과 지능형 다리 (교량)와 살아서 숨쉬는 신형도시가 등장한다.

• The Science & Technology
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• v.35 no.10 s.401
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• pp.40-41
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• 2002

조선 후기 이조판서ㆍ대제학을 지낸 서유구(1764~1845년)는 조부와 부친의 가문과 전통을 계승하여 농학에 큰 업적을 남겼다. 서유구의 농학 대표작은 "임원경제지"로 1백13권에 52책으로 되어있는데, 이는 농학지라기보다 농촌생활의 백과사전이라 할 수 있다. 이 책은 한국 과학기술사 또는 농업기술사 연구에 좋은 재료가 되고 있다.

• The Science & Technology
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• v.30 no.9 s.340
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• pp.50-51
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• 1997

"사양기를 맞은 우리 섬유, 그러나 산ㆍ학ㆍ연이 손잡고 노력하면 높은 부가가치를 창출해내는 경쟁력있는 산업으로 키워나갈 수 있습니다." 고성능 섬유재료개발과 섬유복합소재연구에 심혈을 기울이고 있는 서울대 공대 강태진교수는 말한다. 서울대와 동대학원을 나와 미국 노스캐롤라이나 주립대학에서 박사학위를 받은 강교수는 우리나라의 섬유산업을 밝게 진단하고 있다.

• The Science & Technology
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• v.30 no.12 s.343
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• pp.82-83
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• 1997

혈전형성 억제기능은 물론 항감염성이 뛰어난 무독성 고분자물질을 개발한 KIST 고분자연구부장 김영하박사. 고분자중에서도 의료용 고분자를 전공하고 있는 김박사는 종래의 방법을 개선하여 보다 혈전생성이 적고 칼슘화가 감소도는 재료를 개발해 외국에서도 높이 평가를 받고 있다. 특히 김박사는 산업계의 지속적인 연구투자와 후배들의 창의적 연구활동을 당부하고 있다.

• Composites Research
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• v.21 no.2
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• pp.31-35
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• 2008

In order to design light weight and high efficient electromagnetic wave absorbing materials, hollow magnetic particles have been introduced in this study. The electroless plating method has been utilized to coat Ni and Fe on the substrates of synthesized polystyrene particles of submicron size. Removing polystyrene particles by heat treatment resulted in hollow structures. Observation by SEM, TEM and EDS confirmed the surface morphology and coating thickness of Ni and Fe. Polymeric composites containing hollow particles were tested in order to compare the electromagnetic properties between Ni coated and Fe costed particles. The composite of 30 wt% Fe hollow particles showed the higher complex permeability than Ni hollow particles or the conventional barium ferrite particles.