• Asian-Australasian Journal of Animal Sciences
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• 제4권1호
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• pp.67-71
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• 1991

The purpose of this study was to investigate the possibility of using the buffer index curve as a criterion of silage quality evaluation. The buffer index (or buffer capacity, $\beta$) value is the amount of 0.1N NaOH consumed in titrating from the beginning to the end of the chosen pH step. This value equals the slope of the titration curve at the chosen pH range (${\beta}={\Delta}NaOH/{\Delta}pH$). There were two patterns of buffer index curve. Poorly preserved silages had a peak at pH 5.0, whereas with well preserved silages the peaks tended to rise to the pH 3.75 or 4.00. Well preserved, wilted silages with high pH also appeared to have peak values at pH 3.75 or 4.00. There was a high positive correlationship between the concentration of lactic acid and peak value of good quality silage (r = 0.994, p < 0.01). Also a high positive correlationship (r = 0.899, p < 0.001) was found between the sums of concentration of acetic and butyric acids and the peak values of poor quality silages. The results of these experiments verified the value of the buffer index method as a criterion of silage quality evaluation.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1958-1965
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• 2008

A denitrifying polyphosphate-accumulating bacterium (YKP-9) was isolated from activated sludge of a 5-stage biological nutrient removal process with step feed system. This organism was a Gram-negative, coccus-shaped, facultative aerobic chemoorganotroph. It had a respiratory type of metabolism with oxygen, nitrate, and nitrite as terminal electron acceptors. The 16S rRNA gene sequence of strain YKP-9 was most similar to the 16S rRNA gene sequence of Paracoccus sp. OL18 (AY312056) (similarity level, 97%). Denitrifying polyphosphate accumulation by strain YKP-9 was examined under anaerobic-anoxic and anaerobic-oxic batch conditions. It was able to use external carbon sources for polyhydroxyalkanoates(PHA) synthesis and to release phosphate under anaerobic condition. It accumulated polyphosphate and grew a little on energy provided by external carbon sources under anoxic condition, but did neither accumulate polyphosphate nor grow in the absence of external carbon sources under anoxic condition. Cells with intracellular PHA cannot accumulate polyphosphate in the absence of external carbon sources under anoxic condition. Under oxic condition, it grew but could not accumulate polyphosphate with external carbon sources. Based on the results from this study, strain YKP-9 is a new-type denitrifying polyphosphate-accumulating bacterium that accumulates polyphosphate only under anoxic condition, with nitrate and nitrite as the electron acceptors in the presence of external carbon sources.

• 공업화학
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• 제4권2호
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• pp.300-307
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• 1993

$Na_2S_2O_4$ 수용액과 $CCl_4$-toluene 용액의 2상에서 유기상에 용해하는 tricaprylmethylammonium chloride 상이동 촉매를 사용하여 methyl methacrylate의 라디칼 중합속도를 측정하여, 액-액 불균일계 접촉계면을 통한 라디칼 중합반응기구를 해석하였다. MMA의 중합속도는 수용액상에 존재하는 $Q^+$ 이온의 농도와 ${S_2O_4}^{-2}$ 이온의 농도의 제곱근에 정비례하고 $CCl_4$와 MMA의 농도에 각각 정비례하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.304-307
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• 2002

High speed machining was accomplished. through the technological advances which covers the whole field of mechanical industry. But tapping have many troubles because of its complicate cutting mechanism, for example. tool damage, chip elimination and synchronization between spindle rotation and feed motion. But High speed tapping is so important that it marches in step with the flow of the times and make improvement in the productivity. In this paper we analyze mechanism of high speed synchronized tapping with the signal of tapping torque and spindle speed obtained through the newly developed high speed tapping machine(NTT-30B). We made an experiment with this machine on condition of various speed from 1000rpm to 10000rpm. As one complete thread is performed through the whole chamfer cutting, cutting torque increases highly in chamfer cutting, but smoothly in full thread cutting functioning of the threads guide. And the size of cutting torque according to spindle speed(rpm) was not enough of a difference to be conspicuous.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1720-1723
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• 2000

Boron doped conducting diamond thin film were grown on Si substrate by microwave plasma chemical vapor deposition from a gaseous feed of hydrogen, acetone/methanol and solid boron. The doping level of boron was controlled from 0ppm to $10^4$ppm (B/C). The Si substrate was tilted ca. 10$^{\circ}$ to make Si substrate have different height and temperature. Experimental results show that same condition but different temperature of Si substrate by height made different crystalline of diamond thin film. There were appeared 3$\sim$4 step of different crystalline morphology of diamond. To characterize the boron-doped diamond thin film, Raman spectroscopy was used for identification of crystallinity. To survey surface morphology, microscope was used. Grain size was changed gradually by different temperature due to different height. The Raman spectrum of film exhibited a sharp peak at 1334$cm^{-1}$, which is characteristic of crystalline diamond. The lower position of diamond film position, the more non-diamond component peak appeared near 1550$cm^{-1}$.

• 한국세라믹학회지
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• 제45권1호
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• pp.75-81
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• 2008

In this study, machining characteristics of AIN-hBN composites were evaluated in end-milling process. As a first step, AIN-hBN composite specimens with various hBN contents were prepared using hot press method. Material properties of the composites, such as relative density, Young's modulus and fracture toughness, were measured and compared. Then, a series of end-milling experinients were performed under various cutting conditions by changing cutting speed, depth-of-cut and feed rate. Cutting force variations were measured using a tool dynamometer during the cutting experiments. Machined surfaces of the specimens were observed using SEM and a surface pro filer to investigate the surface integrity changes. The cutting force decreased with an increases of hBN content. The cutting process was almost impossible for monolithic AIN, owing to severe chipping. In contrast, at high content of hBN, surface damage and chipping decreased, and better surface roughness can be obtained.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 추계종합학술대회
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• pp.210-213
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• 1999

본 논문에서는 로봇 매니퓰레이터 제어를 위해 새로운 신경회로망을 제안한다. 제안한 신경회로망구조는 은닉층과 출력층의 출력이 피드백 층을 거쳐 다시 은닉층과 출력층으로 피드백되는 구조이다. 피드백 층은 한번의 시간 지연을 갖는다. 제안한 신경회로망의 학습은 일반적인 오차 역전파 알고리즘을 사용한다. 로봇 매니퓰레이터를 대상으로 시뮬레이션과 실험을 통해서 제안한 신경회로망 구조의 유용성을 확인한다.

• 한국정보통신학회논문지
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• 제18권9호
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• pp.2066-2072
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• 2014

본 논문에서는 O형 슬롯을 가진 계단 구조의 UWB 마이크로스트립 패치안테나를 제안하고 안테나의 특성을 분석하였다. 안테나의 특성 개선을 위하여 방사소자인 패치면의 크기, O형 슬롯의 반지름 변화, 급전선의 폭과, 사각 슬롯의 폭을 CST 시뮬레이션 프로그램을 이용하여 최적화 하였다. 제안된 안테나는 2.8GHz ~ 11.4GHz 주파수 대역에서 최소 반사손실은 약 -32.39dB 그리고 -10dB 대역폭은 8.6GHz의 대역폭을 특성을 나타냈다.

• Journal of Power Electronics
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• 제12권5호
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• pp.787-799
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• 2012

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1060-1071
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• 2014

Signals of the Electroencephalogram (EEG) can reflect the electrical background activity of the brain generated by the cerebral cortex nerve cells. This has been the mostly utilized signal, which helps in effective analysis of brain functions by supervised learning methods. In this paper, an approach for improving the accuracy of EEG signal classification is presented to detect epileptic seizures. Moreover, Independent Component Analysis (ICA) is incorporated as a preprocessing step and Short Time Fourier Transform (STFT) is used for denoising the signal adequately. Feature extraction of EEG signals is accomplished on the basis of three parameters namely, Standard Deviation, Correlation Dimension and Lyapunov Exponents. The Artificial Neural Network (ANN) is trained by incorporating Levenberg-Marquardt(LM) training algorithm into the backpropagation algorithm that results in high classification accuracy. Experimental results reveal that the methodology will improve the clinical service of the EEG recording and also provide better decision making in epileptic seizure detection than the existing techniques. The proposed EEG signal classification using feed forward Backpropagation Neural Network performs better than to the EEG signal classification using Adaptive Neuro Fuzzy Inference System (ANFIS) classifier in terms of accuracy, sensitivity, and specificity.