• Defense and Technology
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• no.4 s.254
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• pp.18-29
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• 2000

다급한 전력화 요구를 충족시키느라 급속히 팽창한 우리 나라 방위산업은 괄목할 외형성장의 내면에 구조적인 취약성의 씨앗도 은밀히 배태하고 있었다. 따라서 방산업계는 업체차원에서 경영개선, 전략계획 등을 통해 체질개선과 경쟁력을 강화하고, 업체상호간 연대강화 모색, 해외로의 수출 및 국제적 공동개발 참여 등을 통해서, 그리고 민수겸업을 통한 군수의존도 축소, 방산 틈새시장 개척 등 근본적인 자구노력을 통해 생존과 성장전략을 능동적으로 추구해야 할 것이다.

• KOREAN POULTRY JOURNAL
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• v.41 no.1
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• pp.133-135
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• 2009

기축년(己丑年) 새해가 밝았다. 지난해를 뒤돌아보면 2008년 4월에 발생한 조류인플루엔자는 많은 농가에 고통을 안겨주었다. 급기야 토종닭 가격은 1,000/kg 이하까지 형성되면서 예방적 살처분 등 방역이 강화되면서 수급이 조정되었고, 정부는 수매를 통한 신속한 대처로 냉동비축을 통해 어려운 시기를 넘겼지만 열악한 영세구조의 사업자나, 농가들을 부도 공포에 떨게 했다. 다행히도 업계는 서로 단합하는 모습을 보이며 상생의 희망을 갖고 자체적인 종란 감축 등 슬기롭게 위기를 극복하는 모습을 보여 주었다.

• The Journal of the Petrological Society of Korea
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• v.24 no.3
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• pp.209-231
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• 2015

In granite quarry, stones are generally quarried along easily separating planes called as 'rock cleavage'. Because orientation and characteristics of the rock cleavage are directly involved with easy quarrying, it is the most important factor on selecting a direction of digging. Using AMS (anisotropy of magnetic susceptibility), we attempt to interpret rock fabrics in Geochang Granite Stone (JS, SD, AR, GD, BW, MD quarry) and discuss about determination of rock cleavages and correlation between the rock fabrics and cleavages. Based on mean susceptibility, thermo-susceptibility curves, and hysteresis parameters, Ti-poor MD and/or PSD magnetites are the main contributor to AMS of the granite stones. The systematic magnetic foliations with sub-vertical dip angle are developed in the whole granite quarries. In most of the granite quarries, the magnetic foliations are significantly consistent with grain plane. In the BW quarry, which has higher $P_J$ values than the others, the magnetic foliations coincide exceptionally with rift plane. These results suggest that rock cleavages in granite stone are related to rock fabrics meaning shape and spatial arrangement of crystals. Magnetic fabrics analysis using AMS method, therefore, can be a quantitative and effective tool for determination of rock cleavages in granite quarry.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.2
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• pp.197-203
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• 2001

Micro-defects induced by design and production failure or working environments are known as the cause of SCC(Stress Corrosion Cracking) in aged structures. Therefore, the evaluation of structural integrity based on micro-cracks is required not only a manufacturing step but also in-service term. So we introduce a new nondestructive inspection method using the magneto-optical film to detect micro-cracks. The method has some advantage such as high testing speed, real time data acquistion and the possibility of remote sensing by using of a magneto-optical film that takes advantage of the change of magnetic domains and domain walls. This paper introduces the concept of the new nondestructive inspection method using the magneto-optical film, also proves the possibility of this method as a remote testing system under oscillating load considering application on real fields by applying the method to four types of specimens.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.54-61
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• 2001

Magnetostrictive materials have nonlinear elasto-magnetic properties. However the constitutive equations to describe the nonlinear properties are not available, yet. In this study we develope the equation in magnetostrictive materials by use of piezomagnetic constitutive equation which is quasi-linearized. With the wave equation, we determine the propagation velocity inside the magnetostrictive materials when a plane wave propagates along a given magnetic field. Validity of the calculated velocity is verified through comparison with experimental velocity measurement results for the most representative magnetostrictive materials. Terfenol-D.

• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.190-195
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• 2007

A novel optical coupling filter with finite-thickness metal-strip gratings printed on optical planar dielectric slabs is proposed, and Bragg conditions of the device are rigorously evaluated by using Modal Transmission-Line Theory (MTLT). The numerical results reveal that the guiding structures have filtering properties due to a leaky-wave stop-band while conventional DFB guiding structures consisted of dielectric gratings depend on a feedback-wave stop-band. Consequently, it shows that the optical coupling titter dependent on the leaky-wave filtering characteristics can be compounded of such optical devices as LD and optical fiber.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.187-187
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• 2011

방재마을 구축 및 운영은 구조적 및 비구조적 재해예방사업을 통하여 지역의 전체적인 방재능력을 향상시키는 것을 기본방향으로 방재마을 구축에 따라 구조적 및 비구조적 컨텐츠가 활용된다. 방재마을 조성에 따른 구조적 및 비구조적 사업은 서로 상호보완적으로 작용되며, 이를 통해 각각의 재해유형과의 연계 및 컨텐츠 제시로 방재력향상을 도모한다. 현재 도시화로 인해 풍수해 발생시 우수유출량 증가로 침수피해 위험이 가중되고 있다. 이에 도시가 돌발성 집중강우에 의한 도시형 침수로부터 주민의 인명과 재산을 보호하기 위해 우수를 신속하게 저류시켜 우수유출량을 줄이는 대책을 수립해야 하며, 풍수해에 대비한 방재마을 구축 컨텐츠 및 운영방안에는 하천정비 및 하도개수, 하수도 정비 및 확충, 홍수조절, 저류지설치, 우수저류 및 우수침투시설 설치 등이 있다. 방재마을 운영 및 활성화를 위한 비구조적 사업은 재해예방을 위한 주민 기업 단체자구노력, 풍수해 예방주민활동, 침수피해 주민예방 활동, 지역자율방재단 운영, 주민주도의 추진체계 구축 등이 있다. 성공적인 방재마을만들기를 위해서는 주민주도의 추진체계를 확립하도록 하는 것이 무엇보다 중요하며, 방재마을에 있어 주민참여가 방재도시만들기와 밀착되어 전개될 때 방재마을의 운영 및 관리 효과가 향상된다. 따라서 구조적 운영방안과 함께 주민추진체계를 중심으로 한 방재마을 구축 및 운영을 통해 방재마을 활성화를 도모할 수 있을 것으로 사료된다.

• Journal of the Korean Magnetics Society
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• v.6 no.2
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• pp.98-105
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• 1996

스퍼터링 방법으로 제작된 NiFe 박막에서 Ar 압력이 자기 및 자기저항 성질에 미치는 여향을 조사하였다. 타겟으로는 Ni$_{81}$$Fe_{19}$ 조성의 합금타겟을 사용하였다. TEM을 써서 박막의 미세구조를 조사하였으며, 보자력과 포화자화는 VSM으로 측정하였다. 합금박막의 조성은 ICPS로 분석 확인하였다. 10 mTorr 이상의 높은 Ar 압력에서 제작된 박막에서 갈라진 틈새(crack-like void)를 갖는 주상구조가 관찰되었다. 이러한 주상 결정립경계(columnar grain boundary)가 자화 과정에서 자구벽 핀닝자리(pinning site)가 되어, Ar 압력이 커짐에 따라 보자력이 증가 하였으며, 박막의 밀도가 감소하여 포화자화가 줄어드는 것을 볼 수 있었다. 한편, Ar 압력이 증가하면서 자기저항비가 감소하는 결과를 얻었다. 결정립 경계 산란과 결정립간 터널링에 의한 박막의 비저항의 증가가 이러한 자기저항비 감소의 주원인임을 알 수 있었다.다.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.175-184
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• 1993

Abstract Co-and/or AI-added Nd-Fe-B-based magnetic alloys were fabricated by using vacuum induction melting frunace, and melt-spun ribbons were made of the magnetic alloys with single roll rapid quenching method. The variation of magnetic properties of the melt-spun ribbons as a function of Cuwheel velocity (Vs) were investigated. Bonded magnets were made of the optimally quenched ribbon fragments, and the magnetic properties of the melt-spun ribbons and the bonded magnets were studied, relating to the microstructure and crystalline structure. Cu-wheel surface velocity had a strong effect on the magnetic properties of the melt-spun ribbons, and the maximum properties were obtained around Vs =20m/sec. The optimally quenched ribbon had a cellura-type microstructure, in which fine N$d_2$F$e_14$B grains were surrounded by thin Nd-rich phase. In case of a 2.1at% AI-added melt-spun ribbon, the magnetic properties were as follows: iHc, Br, and (BH)max were 15.5KOe, 7.8KG and 8.5MGOe respectively. And resin bonded magnets were fabricated by mixing optimally quenched ribbon fragments with 2.5wt % polyamide resin, compacting and binding at room temperature. The iHc, Br and (BH)max of bonded magnet were lO.2KOe, 4.4KG and 3.3MGOe respectively. And hot-pressed magnets were made by pressing the overquenched ribbons at high temperature. The magnetic properties of hot-pressed magnets were better than those of bonded magnets, and when the holding time was 8 minutes, the iHc, Br, and (BH)max of the hot-pressed magnet were 1O.8KOe, 7.3KG and 8.0MGOe respectively. Domain structure was mainly maze pattern, which means that the easy magnetization axis could be aligned, and the domain width of the hot-pressed magnets was smaller than that of bonded magnets.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.144-149
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• 2011

This research has been carried out to examine the effects of quality promoting agents on global quality and epidermal changes of Chamaecereus silvestrii 'Hee-mang' for quality maintenance of the transportation. D-sorbitol than D-mannitol treatment was effective in a lower reduction of fresh weight in C. silvestrii transportations. Application of diniconazole 200 ppm suppressed growth of C. silvestrii. However, it enabled the possibility of long-tenn plant transportation (up to 50 days) and color formation was also effective. As for epidermis structure of C. silvestrii, hypodermis development was lower compared to Gymnocalycium friedrichii and its long-term transportation became poor quality due to single layered, thin cell wall. Application of diniconazole 200 ppm + D-mannitol 10,000 ppm showed higher growth suppressing effects and diniconazole 200 ppm + wax treatment showed better color formation suitable for quality maintenance and storage purposes for C. silvestrii.