• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.66.2-66.2
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• 2010

미니탭(Minitab) 프로그램에 있는 실험계획법(Design of experiment)를 이용하여 박막실리콘 I-layer의 주효과 및 교호작용에 대한 연구를 실시하였다. I-layer의 주요 특성은 증착속도 및 전도도에 대하여 분석을 하였으며, 최종적으로 선택된 증착조건을 사용하여 비정질 실리콘 태양전지를 제조하여 확인 하였다. 실험설계는 2수준 5인자 완전설계요인법을 사용하였다. 분석결과 단막의 증착속도에 영향을 주는 주효과로는 Power와 E/S거리고 나타났으며, Power와 E/S거리, Power와 Pressure에서 큰 교호작용이 일어남을 확인 할 수 있었다. 암전도의 영향을 주는 주효과는 Sub. Temp.를 제외하고는 모두 영향을 주고 있었으며, 상당히 복잡한 교호작용을 이루고 있어 정확한 분석을 할 수는 없었다. 광전도도의 경우도 주효과에서 SiH4 flow rate를 제외하고는 모두 영향을 주고 있었으며, 복잡한 교호작용으로 정확한 분석이 어려웠다. 따라서 P-value를 분석하여 최종 R-제곱값이 증착속도는 97%이상의 높은 값을 얻었으나 전도도의 경우 최대차수 3차항으로 70~80%정도의 낮은 값을 얻었을 수 있었다. 낮은 값을 얻은 이유로는 실험설계시 몇몇 조건이 불안정한 plasma 상태로 인하여 전도도의 측정 편차가 커 분석오차가 높았을 것으로 추정된다. 암전도를 망소특성, 광전도도를 망대특성으로 광민감도 $10^5$으로 최적화 하여 비정질 태양전지를 만들어 평가한 결과 약 9%대의 광변환 효율을 얻을 수 있었으나 만족도 40%대의 낮은 값으로 향후 이와 관련한 더 정밀한 측정 및 분석이 요구된다.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.1
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• pp.23-28
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• 2015

This study was conducted to evaluate the biodegradation characteristics of food waste on various collection systems using anaerobic batch test. The ultimate methane production from food waste in standard plastic garbage bags (sample A) was $285.6mL\;CH_4/g$ volatile solids (VS) which is the lowest, and reaction constant was $0.215d^{-1}$. The ultimate methane production from food waste in waste vessel based on RFID (sample D) was $493.4mL\;CH_4/g$ VS which is the highest, and reaction constant was $0.162d^{-1}$. The determinants of rate limiting step on all samples showed positive numbers, and the methane production step was found a rate limiting step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.9-14
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• 2018

The function of gas springs is based on the compression of a gas. They are used in a wide variety of industries, and demand for them is increasing. Gas springs can be divided into compression and extension springs. Extension springs have not been studied much in relation to control of the piston speed, unlike compression springs. In this study, the magnitude of the piston rebound pressure was theoretically predicted by calculating the pressure loss in a double-cylinder extension gas spring. Numerical simulations of the piston behavior were carried out for small and large amounts of friction between the piston and the cylinder. FLUENT was used for the simulation with a 6-DOF model and UDF to simulate the behavior of the piston. The calculation regions of the front and rear of the piston were separated, and different types of grids were generated in the regions to implement a dynamic mesh using only a layering method. The results show that the piston returns with the target speed in both cases. However, the patterns of the piston behavior reaching the final speed are different.

• KSBB Journal
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• v.10 no.5
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• pp.540-546
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• 1995

Dry corn gluten meal of 70% protein content was enzymatically hydrolyzed by alkaline protease in a pH-state reactor. Such process variables as temperature, pH, and enzyme-to-substrate ratio were varied, and at each condition degree of hydrolysis was monitored and calculated. The ultimate degree of hydrolysis, which ranged between 25 and 28% based on gluten protein mass, was not significantly affected by the process variables. However, $50^{\circ}C$ and pH 9-10 appeared optimum. Kinetic analysis indicated enzyme deactivation was negligible during the hydrolysis, and the experimental data were near perfectly fitted to the model kinetic equation which was modified after neglecting enzyme deactivation term. The enzyme reaction was 1$100\times$ scaled up and basically the same hydrolysis performance was resulted. Amino acid analysis showed the hydrolyzate was relatively rich in glutamine/glutamic acid, leucine, and alanine at 19.6, 16.1, and 12.3 mole %, respectively.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.577-583
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• 1998

Chestnut and paulownia boards for the traditional musical instruments were air dried to compare moisture contents(MC), drying rates and drying times between the air drying for 70 days in a yard and the shed drying for 150 days in a closed shed when piled in early June. An average final MC and the drying rate of chestnut boards were 20.6 percent and 0.78%/day for the air drying, and 16.6 percent and 0.44%/day for the shed drying. An average final MC and the drying rate of paulownia boards were 16.7 percent and 1.53%/day for the air drying, and 13.5 percent and 0.77%/day for the shed drying. Drying rates of air-dried boards were nearly twice as high as those of shed-dried boards for both species. Air drying rates of chestnut and paulownia boards were very high and exhibited falling drying rate above the fiber saturation point(30%), and then decreased irregularly. However, shed drying rates of chestnut and paulownia boards were high and exhibited falling drying rate above 55 percent MC for chestnut boards and above 80 percent MC for paulownia boards, and then decreased irregularly.

• Journal of the Korean Chemical Society
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• v.40 no.2
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• pp.128-134
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• 1996

The kinetics of the hydrolysis of dihydro-1, 4-oxathiin derivatives were investigated by ultraviolet spectrophotometry in H2O at $25^{\circ}C.$ A rate equation which can be applied over a wide pH range was obtained. The substituent effects on the hydrolysis of dihydro-1, 4-oxathiin derivatives were studied and the rate of hydrolysis was shown to be accelerated by electron accepting groups. Final product of the hydrolysis was 2-(2-hydroxyethylthio)acetoacet-anilide enol form. On the basis of rate equations derived and judging from hydrolysis products obtained and from general base effect and substituent effects, plausible mechanism of the hydrolysis in various pH range have been proposed. Below pH 3.5, the hydrolysis was initiated by the protonation and followed by the addition of water to 2-carbon. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxide to 2-carbon. In the range of pH 4.0∼10.0, the addition of water to dihydro-1,4-oxathiin is rate controlling step.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.503-510
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• 2013

Shear wave velocity is widely used as an parameter for investigating subsurface characteristics and for obtaining the design parameters based on theoretical equations. This study seeks to estimate the coefficient of shear wave velocity in Busan clay via laboratory tests. Eight specimens were extracted at depths of 10, 12, 15, 20, 22, 25, 30, and 31 m. The specimens were subjected to the consolidation test to determine the relationship between effective stress and shear wave velocity. The relationship shows a non-linear trend and is similar to the results of a previous study. The coefficient shows constant coverage and a relationship between ${\alpha}$ and ${\beta}$ is suggested. The results demonstrate that this coefficient could be used as a reference value to determine engineering parameters based on the shear wave velocity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.405-412
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• 2015

This paper represents a filter design to estimate the airspeed of a spin-stabilized, trajectory-correctible artillery ammunition. Due to the limited power and space in operational point of view, the airspeed sensor is not installed, and thus the airspeed need to be estimated using limited sensor measurements. The only IMU measurements(three-axis specific forces and angular rates) are used in this application. The extended Kalman filter algorithm is applied since a linear filter can not cover the its wide operational range in airspeed and altitude. In the implementation of the EKF, the state and measurement equations are transformed into the no-roll frame for simple form of Jacobian matrix. The simulation study is conducted to evaluate the performance of the filter under various environment conditions of sensor noise and wind turbulence. In addition, the effect of the choice in filter design parameters, i.e. process error covariance matrices is analyzed on the performance of the estimation of airspeed and angular rates.

• The Journal of the Acoustical Society of Korea
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• v.23 no.6
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• pp.462-472
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• 2004

In this paper a method for compensating for thp performance degradation or automatic speech recognition (ASR) is proposed. which is mainly caused by speaking rate variation. Before the new method is proposed. quantitative analysis of the performance of an HMM-based ASR system according to speaking rate is first performed. From this analysis, significant performance degradation was often observed in the rapidly speaking speech signals. A quantitative measure is then introduced, which is able to represent speaking rate. Time scale modification (TSM) is employed to compensate the speaking rate difference between input speech signals and training speech signals. Finally, a method for compensating the performance degradation caused by speaking rate variation is proposed, in which TSM is selectively employed according to speaking rate. By the results from the ASR experiments devised for the 10-digits mobile phone number, it is confirmed that the error rate was reduced by 15.5% when the proposed method is applied to the high speaking rate speech signals.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.111-122
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• 2012

There has been a strong demand for providing diverse services to drivers utilizing existing ITS infrastructure. To this end, this study is aiming at improving the accuracy of a variable speed limit system by determining recommended speeds for the system utilizing the information from Urban Traffic Information System(UTIS) and Weather Information System(WIS). In order to determine appropriate speed limits under inclement weather conditions for the variable speed limit system, this study examined three methods: i) the method utilizing the information from WIS, ii) the method utilizing the information from UTIS, and iii) the method which combines the information from WIS and UTIS using different weights for diverse weather conditions. Finally, this study selected the third method which determines an appropriate speed limit using the relationship between the vehicle operating speed and the minimum stopping distance which is estimated using the existing speed limit, surface coefficient of friction and superelevation.