• Journal of the Korean institute of surface engineering
• /
• v.22 no.2
• /
• pp.88-92
• /
• 1989

양극산화 피막의 졀정구조에 관한 연구는 1960년대부터 반응 Mechanism의 연구와 병행하여 많은 논란이 되어왔다. 결정구조의 정확한 Model 이 아직까지 확립되어 있지 않은 상태에서, 여러 가지 접근방식으로 연구되고 있는 실정이다. 최근에는 HRTEM, NAS-NMR등의 고성밀 장비의 응용에 의한 결정구조의 분석에 활발히 진행이 되고 있으며, 이론 물리학의 응용 또한 이곳까지 확산되고 있는 상태이다. 본 고에서는 반응 Mechanism을 연구하는데 가장 밀접한 분야인 양극산화 피막 결정 구조에 관해 1950년대이후 어떻게 연구되고 설명되었는가를 조명하기로 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.702-705
• /
• 2001

This paper deals with a method to predict the flying state of the head slider in a optical disk drive(ODD). The Dual Solver based on the Quasi-Newton method and the Newton method has been developed to simulate the steady-state flying conditions. The numerical results show the effectiveness and reliability of this new solver.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.05a
• /
• pp.136-137
• /
• 2009

전자파 차폐재로 메쉬를 제작하는 기존의 배치 방식은 복잡한 작업공정과 비싼 설비로 인해 생산원가 높다. 그래서 pulse reverse current를 이용하여 Cu mesh 도금을 하였다. 정펄스의 전류밀도가 $31mA/cm^2$일일 때 역펄스의 전류밀도 및 duty cycle에 상관없이 표면은 매끄럽게 나왔다. 정펄스의 전류밀도가 $454mA/cm^2$일때는 duty cycle이 25%이하는 표면상태가 매끄럽게 나타났지만 33%이상에서 표면상태가 거칠게 도금이 되었다.

• Journal of the Korean Vacuum Society
• /
• v.2 no.3
• /
• pp.339-345
• /
• 1993

계면의 원자구조와 전자특성간의 상관성을 연구하기 위하여 GaAs-Ge(AlAs) 이종접합에서 전자의 국소상태밀도(LDOS)를 계산하였다. 본 연구에서는 tight-binding recursion 방법을 기초로 하여 계면의 국소상태밀도로부터 band-offsets, 계면형성에너지, 계면결합의 bond order 등을 연구하는 보다 편리한 방법을 제시하였다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.5
• /
• pp.423-429
• /
• 2001

Prediction of the variation in annual biomass was conducted for the white croaker. Argyrosomus argentatus in Korean waters using leslie Matrix, based upon fishery data for the past 21 years and biological data, We used density-independent and density-dependent Leslie Matrix models. Similar parameters were estimated from two models except that the density-dependent model was influenced by the density effect variable, q(i,t), The eigenvalue of the white croaker population for the $1984\~1995$ period was estimated to be 0.8, indicating a declining pattern of the population. The survival rate of 0-th year class was calculated to be 0.00005. Based on the schedule of the age-specific survival rate and fecundity, the future biomass and catch was predicted for various levels of fishing mortalities (F), If F was set at 0.252/yr ($F_{35x}$) or 0.368/yr ($F_{0.1}$), the biomass and catch increased, and if F was set at 0.922 ($F_{current}$), the biomass and catch decreased, The fishing mortality at equilibrium was estimated to be 0.7/yr. Finally, the management strategy of the white croaker was discussed.

• Korean Journal of Soil Science and Fertilizer
• /
• v.22 no.3
• /
• pp.221-227
• /
• 1989

This study was conducted to understand the influence of soil compaction on root growth and nutrient uptake characteristics of the soybean roots grown in two soils with different texture. Tap root elongation was measured on young seedling grown in cores compacted to different bulk densities of 1.2, 1.4 and $1.6/cm^3$ with different soil water retention in laboratory. The soil used were Samgag sandy loam and Baegsan loam soils. The wet and dry weight, total length, average radius and total surface area of roots were measured on soybean plants grown in 1/5000 a Wagner pots compacted to different bulk density of 1.2 and $1.4g/cm^3$. The nutrient uptake of soybean shoot was measured and evaluated with the unit surface area of roots at the 7th, 17th and 27th days after germination. The results were as follows: 1. The tap root elongation rate was faster in the loam soil with low bulk density than in the sandy loam soil with high bulk density. The elongation rates were remarkedly decreased when soil water was lower than the retention of 4 bars in loam soil and that of 1 bars in sandy loam soil. 2. Tap root elongation rate sharply decreased as increased soil strength higher than $2kgf/cm^2$ measured by ELE penetrometer showing curvillinear regression. However, it was low regardless of soil strength when soil water retention was 10 bars in sandy loam soil. 3. From the pot experiment, the total length of roots were longer in loam soil than in sandy loam soil and was longer in the soils with lower bulk density. The average radius of fine roots grown in sandy loam soil was larger than that grown in loam soil. The total surface area of roots was greater in the loam soil with low bulk density than in the sandy loam soil with high bulk density as the total length of roots. 4. The amounts of nutrient uptake by soybean shoots were greater in loam soil primarily due to more production of dry matter than in sandy loam soil. The nitrogen influx rates through the unit surface area were 597 to $753nmoles/day-cm^2$ in loam soil and 222 to $365nmoles/day\;cm^2$ in sandy loam soilshowing higher value in higher bulk density. The potasium influx rates were 99 to $175nmoles/day-cm^2$, and those of phosphate were 26 to $46nmoles/day\;cm^2$. Those of Ca and Mg were 175 to 246 and 163 to $205nmoles/day\;cm^2$. The difference in nutrient influx rates between bulk densities of these elements were lower than that of nitrogen.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.8
• /
• pp.823-833
• /
• 2010

For the study of thermophysical properties of kerosene for the liquid rocket and aviation fuels, the surrogate models are investigated. The density distributions based on the real gas equations of state(Soave modification of Redlich-Kwong and Peng-Robinson equation of state) and NIST SUPERTRAPP(extended corresponding state principle) are compared with the previous experimental results at supercritical conditions. The error range of thermophysical properties analyzed for the surrogate models as well. Peng-Robinson equation of state and extended corresponding state principle are especially accurate for the hydrocarbon fuels but the appropriate surrogate models need to be chosen to the operation conditions such as pressure and temperature.

• Journal of the Korean Magnetics Society
• /
• v.9 no.5
• /
• pp.223-226
• /
• 1999

We have investigated the magnetic properties and the electronic structures of Tc half-monolayer (0.5-ML) on Pd(001) using the full-potential linearized augmented plane wave(FLAPW) energy band method. We calculated the total energies for ferromagnetic and paramagnetic states to determine the stable magnetic state. The calculated results show that the total energy of the ferromagnetic state is lower than that of the paramagnetic one. The overlayer Tc 0.5-ML has considerably large magnetic moment $(2.09\;{\mu}_B)$, while the substrate Pd layers have been negatively polarized. The calculated density of states and total electrons inside the muffin-tin (MT) sphere are presented and discussed in relation with the magnetic properties.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.121-122
• /
• 2007

• Journal of the Korean Professional Engineers Association
• /
• v.9 no.1
• /
• pp.4-14
• /
• 1976

천마총출토유물의 직물류 20여편을 화학적 및 물리적 시험분석을 통하여 그 사용섬유, 직물의 밀도, 구성계의 섬도, 조직, 염색상태등을 조사하므로서 그 직물의 신라시대 당시의 명칭 또는 품질의 정도와 염색기술등을 추정하여 문헌상의 기술자료를 확인할 수 있는 결과를 제시하였다.