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林土의 有機物의 分解速度와 無機養料의 垂直分布에 關한 考察
金遵敏,張楠基,鄭玩鎬 서울대학교 교육대학원 학술연구회 1966 論文集 - 서울대학교 교육대학원 Vol.3 No.-
Kim Choon Min, Chang Nam Kee and Chung Whan Ho: Decomposition rate of plant residue and the vertical distibution of mineral nutrients in the woodland soil. The relationship between decomposition rate of litter and the amount of mineral nutrients dispersed to the soil horizons were studied on the oak and pine forest stand. The results are as follows: 1. Decomposition rate of litter was highest in the F horizon of the oak stand, however in the pine stand it was highest in H horizon. 2. The correlation coefficients between decomposition rate and humus, organic carbon, moisture content, calcium, phosphorus, and nitrogen in the pine stand are; 0.90, 0.98, 0.76, 0.98, and 0.88, in oak stand; 0.97, 0.93, 0.92, 0.97, 0.74 and 0.73. 3. Factors which affect the decomposition rate of litter are humus, organic carbon, moisture content, calcium, phosphorus and nitrogen. 4. Among the variables, PH, moisture content and phosphorus under the oak and pine forest showed significant differences in each horizon. 5. C/N ratio of pine stands is higher than that of oak stands studied. 6. The vertical distribution of mineral nutrients is highly related with the amount of humus accumulated on top soil.
The Analysis of Spectrum on the Barkhausen Noise of Hysteresis Loops on Neutron Irradiated Material
Sim, Cheul-Muu,Chang, Kee-Ok,Park, Kook-Nam,Cho, Man-Soon,Park, Chang-Oong The Acoustical Society of Korea 1999 韓國音響學會誌 Vol.18 No.e1
In relation to a non-destructive evaluation of irradiation damages, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of 2.3 ×10/sup 19/ n/㎠ (E ≥1 MeV) at 288℃. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of 50 μ sec and 20 μ sec. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen. In addition to the amplitude, the harmonic frequency of Barkhausen noise is taken into accounts as a promising tool for monitoring the irradiation induced degradation of the reactor materials such as a SA508 of PWR-RPV steel and a Zr₄ of HANARO-CNH.
남기우,안석환,이상기,김현수,문창권 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.1
신호처리법으로 현재 많이 사용되고 있는 푸리에 변환은 신호의 주파수 성분이 사간에 따라 어떻게 변화하는지를 표현하지 못한다. 따라서 최근 이와 같은 푸리에 변환의 단점을 보완하여, 신호의 시간과 주파수에 대한 정보를 동시에 표현할 수 있는 시간-주파수 해석법들이 개발되었다. 본 연구에서는 음향방출을 이용하여 복합재료의 주요 발생원으로 알려져 있는 기지균열, 섬유분리, 섬유파괴 및 층간분리 등과 같은 파괴기구를 해석하였다. 각각의 파괴특성이 나타나도록 시험편을 제작하여 인장시험 시 검출된 음향방출신호의 시간-주파수 해석을 통해 전체 파괴기구의 특징을 분석하였다. Fourier transform has been one of the most common tools to study the frequency characteristics of signals. With the Fourier transform alone, however, it is difficult to tell whether signal's frequency contents evolve in time or not. Except for a few special cases, the frequency contents of most signals encountered in the real world change with time. Time-frequency analysis methods are developed recently to overcome the drawbacks of Fourier transform, which can represent the information of signals in time and frequency at the same time. In this study, damage process of cross-ply carbon fiber reinforced plastic (CFRP) under monotonic tensile loading was characterized by acoustic emission. Different kinds of CFRP specimens were used to determine the characteristics of AE signals. Time-frequency analysis methods were employed for the analysis of fracture mechanisms in CFRP such as matrix cracking, debonding, fiber fracture and delamination.
朴起雅,尹錫權,南昌祐 同德女子大學校 1986 同大論叢 Vol.16 No.1
Several methods of measuring rancidity were compared with respect to sensitivity against autooxidized perilla oil storing at 45℃. The results obtained were summarized as follows: 1. Peroxide value, hydroperoxide diene and triene levels, contents of acetaldehyde and hexanal in head space and refractive index of perilla oil were increased almost linearly with the incubation time tested at 45℃. 2. The best correlation with sensory test score was peroxide value(r=0.992**). Hydroperoxide diene value and acetaldehyde contents in head space also show highly significant correlationship with wensory test score. 3. Considering the rapidity and sensitivity, hydroperoxide diene method and peroxide method are the recommendable for measuring the rancidity of perilla oil.
Magnetron sputtering법으로 제조된 Al-1%Cu/Tungsten Nitride 다층 박막
이기선,서수정,김장현,김남철 공주대학교 자원재활용신소재지역협력센터 2000 2차년도 센터 사업 성과집 Vol.2000 No.1
표면 탄성파 디바이스의 전극재료로 사용되는 Al-1%Cu(4000Å)/tungsten nitride 박막을 magnetron sputtering법으로 제조하고 전기저항을 평가한 결과 비정질상의 tungsten nitride 박막을 제조할 수 있었고, 비정질 형성을 위해서 질소비 (R = N2/(Ar+N2))가 10∼40% 정도 필요하였다. Tungsten nitride 박막의 잔류응력은 비정질이 형성되면서 급격히 감소되었다. 이러한 비정질 박막위에 Al-1%Cu합금막이 형성되었다. 다층막은 453K에서 4시간 동안 열처리함으로써 3.6μΩ-cm의 저항를 나타냈는데, 이는 박막내 결정립 성장과 결정 결함의 감소에 기인하였다. As a power durable-electrode in SAW filter. Al-1%Cu/tungsten nitride multi-layer thin film was fabricated by magnetron sputtering process. Tungsten nitride films had the amorphours phase at the nitrogen ratio, R, ranging from 10~40%. The amorphization could be controlled by nitrogen ratio. R = N2/(N2+Ar) as a sputtering process parameter. Residual stress in tungsten nitride abruptly decreased with the formation of amorphous phase. Al-1%Cu thin film was deposited on the amorphous tungsten nitride. After the multi-layed thin film was annealed for 4 hours at 453K, the resistivity decreased as 3.6 μΩ-cm, which was due to grain growth and reduced crystal defects.