• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.126-133
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• 1997

In order to apply for the gas sensing layer and the piezoelectric thin film devices, we studied the effects of magnetron sputtering conditions and annealing temperature on the electrical and structual characteristics of the ZnO thin film. The optimal deposition conditions, in order to obtain a c axis of the ZnO (002) phase thin film which is perpendicular to SiO$_{2}$/Si substrate, were like these ; substrate temperature 150.deg. C, chamber pressure 2 mtorr, R.F. power 300 watts, gas flow ratio 0.4[O$_{2}$(Ar + $O_{2}$)]. When the ZnO thin film was annealed in 600.deg. C, $O_{2}$ gas ambient for 1 hr, the resistivity was 2.6 x 10$^{2}$.ohm.cm and the grain size of ZnO thin film was less than 1 .mu.m. So the ZnO thin film acquired from above conditions can apply for the gas sensing layer which require a c axis perpendicular to the substrate surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.818-823
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• 2005

Creep damage is one of the mosl important characteristics for the stability of high temperature structures such as huge energy converting facilities. Creep failure of Type 316LN stainless steel is highly correlated to generation and growth of the voids. In this paper, in order to investigate the correlation of creep rupture time and ultrasonic parameters (group velocity, angular velocity), creep-damaged Type 316LN specimens and measurements for the ultrasonic parameters were made. However, bi-directional measurements were applied along the load direction and the perpendicular direction to the load line by means of the contact type probe of which the central frequencies are 10MHz, 15MHz and 20MHz. Analyzing the angular velocities of the ultrasonic signals obtained from the load direction, it was confirmed that the angular velocities were declined as the creep time passed when 15MHz and 20MHz probes were used. Also, the group velocities were declined for all three frequencies as the creep time increased. Thus, positive feasibility for the creep damage evaluation by means of the angular and group velocities was confirmed. Moreover, result of analysis for the ultrasonic signal which was obtained from the perpendicular direction upon the angular and group velocities indicated little variation for both of the angular and group velocities. Therefore, the creep damage is likely to represent anisotropic itself.

• 한국재료학회지
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• 제4권5호
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.689-702
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• 2017

In this study, with the view to using effectively small and medium diameter Korean domestic woods as structural materials, cross-laminated woods were manufactured by using six species of Korean domestic softwoods and hardwoods, and bending creep properties were investigated for each species. The creep curves showed the shape of the exponential function plot, and the creep curves after 1 hour were able to estimate by fitting it to the power law. The initial and creep compliances of cross-laminated woods showed the higher values in wood species with a low density than in that with a high density. And by cross-laminating, the initial and creep compliances perpendicular to the grain considerably decreased, the extent of the decrease was found to be greater in creep deformation than in initial deformation. The creep anisotropies of cross-laminated woods were considerably decreased by cross-laminating. The relative creep of $C_{\bot}$ type composed of perpendicular-direction lamina in the faces decreased 0.59 - 0.64 times compared to that of $P_{\bot}$ type composed of perpendicular-direction laminae in all layers, and that for $C_{\parallel}$ type composed of parallel-direction laminae in the faces increased 1.5 - 1.6 times compared to that of $P_{\parallel}$ type composed of parallel-direction laminae in all layers.

• Journal of the Korean Wood Science and Technology
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• 제49권1호
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• pp.57-66
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• 2021

In recent years, the use of cross laminated timber (CLT) has been evolving. In addition, CLT manufactured with various species such as Japanese cedar has been developed to utilize the local resources in each country. However most factories in Japan produce CLT by bonding the laminae in width direction for orthogonal layers, where grain of element is perpendicular to the grain of outer layer, and this process is considered to be one of the factors that reduce productivity. A new wood based material (hereinafter referred to as Ply-lam) using wooden panel such as plywood for the orthogonal layer was developed in order to improve productivity in CLT manufacturing and improve quality. Japanese cypress lamina was used for the parallel layer, where grain of element is parallel to the grain of outer layer, of CLT and Korean larch plywood was used for the orthogonal layer, in order to effectively use Korean larch and expand the utilization of Japanese cypress. The cross-sectional construction of the Ply-lam was 5-layers 5-plies, and the dimensions were 1000 mm (width) × 150 mm (depth) × 4000 mm (length). As a performance evaluation of the manufactured Ply-lam, strength tests such as out-of-plane bending, in-plane bending, out-of-plane shearing and in-plane shearing tests were carried out. As the result of this study, Ply-lam composed of Japanese cypress lamina panels and Korean larch plywood showed very higher out-of-plane bending strength compared to the standard strength of CLT. And the result obtained in other tests seems to show a sufficiently high value.

• 한국표면공학회지
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• 제34권6호
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• pp.531-536
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• 2001

Co-22 %Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure (SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. The periodic fine Co-enriched phase and Cr-enriched phase is the plate shape of 80 (equation omitted)-wide and 1000 (equation omitted)-long. Cr-enriched phases are located at the center of grains. We prepared 5000 (equation omitted) -thick Co-22 %Cr films on polyimide substrate with varying substrate temperature of $ 30^{\circ}C$, $ 150^{\circ}C$ ,200 $^{\circ}C$, $300^{\circ}C$, and $400^{\circ}C$, respectively. A transmission electron microscope equipped with energy dispersive X-ray analyzer is employed to observe the microstructure of each samples after Co-enri-ched phase are etched selectively. The self organized nano structure of Co-enriched and Cr-enriched lamellar is observed above the substrate temperture of $150^{\circ}C$. No compositional change is observed with substrate temperature. The compositional phase separation in self organized structure becomes clear as the substrate temperature increases. Our results implies that the self organized nano structure in Co-22 %Cr film is ideal for ultra high density recording media by recording selectively on Co-enri-ohed phase.

• Journal of Forest and Environmental Science
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• 제9권1호
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• pp.10-18
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• 1993

북양산(北洋産) 주요(主要) 침(針), 활엽수재(闊葉樹材)의 물리적(物理的) 성질(性質)(밀도(密屠), 만재율(晩材率), 공권율(孔圈率), 평균년수폭(平均年輸幅))과 역학적(力學的) 성질(性質)(종압축강도, 횡압축강도, 전단강도에 관하여 연구(硏究) 조사하였다. 이 실험(實驗)의 연구(硏究) 결과(結果)는 다음과 같다. 밀도(密度)와 만재율(晩材率)은 물리적(物理的) 역학적(力學的) 성질(性質)과 밀접(密接)한 관계(關係)를 나타낸 반면, 공권율(孔圈率)과 평균년수폭(平均年輸幅)은 물리적(物理的) 역학적(力學的) 성질(性質)과 거의 관계(關係)가 없음을 나타내었다.

• 한국자기학회지
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• 제23권1호
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• pp.12-17
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• 2013

금속 분말 니켈(Ni)을 HCl용액에 용해시킨 후 $H_3BO_3$, KOH을 첨가하여 Chloride 도금용액을 제조 후 Ni plate 기판에 도금하였다. 도금두께는 $3{\mu}m$로 일정하게 유지하였다. 전류밀도를 $1{\sim}30mA/cm^2$ 변화를 준 결과 전류밀도를 증가시킬수록 Ni 후막표면이 거칠어졌다. $25mA/cm^2$와 $30mA/cm^2$에서는 균열된 표면형상을 관찰하였다. 또한 XRD patterns 변화를 관찰한 결과 전류밀도가 증가할수록 FCC(111)과 FCC(220) 및 FCC(311)상의 강도는 증가한 반면 FCC(200)상의 강도는 감소하는 것을 관찰하였다. 전기도금된 Ni의 수평 및 수직 자화 값을 측정하였는데 기판에 의한 수평자화 값이 크게 나왔고, 코팅층 두께가 증가할수록 수직자화 값이 커지는 것을 확인하였다.

• 대한전자공학회논문지SD
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• 제43권6호
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• pp.18-22
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• 2006

묽은 n-octadecyltrichlorosilane를 여러 가지 비율로 섞어 만든 유기물에 따라 처리된 $SiO_2$ 절연막의 특성에 대하여 분석하고 펜타센 증착 표면에 생긴 그레인 크기 사이의 상관관계를 조사하였다. 전압-전류 특성 곡선에 의한 누설전류의 증가량이 유기물 처리 농도에 따라 비례적으로 증가하지 않았으며, 0.3 % 처리 농도에서 누설전류가 가장 작게 나타났다. 0.3 % 처리 농도의 $SiO_2$ 절연막은 유무기 복합적인 하이브리드 특성을 나타내고 있으며, 펜타센이 증착된 후 표면 사진에서 그레인 크기가 가장 작게 성장된 것을 확인하였다. 반면에 유기물 특성의 절연막 혹은 무기물 특성의 절연막 위에서 펜타신 물질이 증착후 그레인 크기는 점점 증가하였다.

• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.61-69
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• 2003

This study investigated the effect of moisture content and loading direction on dowel bearing strength of two types of SCL. Dowel bearing tests of LVL and PSL were conducted with two different MC level, 7.5% and 19%, and two different oriention, L-direction(loading parallel to grain) and X-direction(loading perpendicular to grain). Most of specimens showed typical load-deformation curves and intersected 5% offset line. Failure modes were classified into two categories; spliting(for L-direction specimens) and peeling(for X-direction specimens). Dowel bearing strength generally decreased with increasing MC. The decreasing rate was more significant in X-directon. ESG also decreased with increasing MC, and the ratio of ESG of 7.5% versus 19% was about 1.47. Dowel bearing strength of LVL and PSL in L-direction was higher than that of X-direction. This results indicated that MC and loading orientation had a significant effect on dowel bearing strength of SCL. The average dowel bearing strength of LVL were higher than that of PSL in each loading direction. Two types of probability distribution model were chosen to quantify strength distribution, normal and 2-parameter weibull distribution. The two models showed good agreement with the data, especially in lower tail of the cumulative distribution. Normal and 2-parameter weibull distribution seemed to proper model of the dowel bearing strength for each MC levels.