• Journal of Power Electronics
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• 제12권3호
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• pp.458-467
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• 2012

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.

• 대한조선학회논문집
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• 제41권1호
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• pp.1-7
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• 2004

GUI program for analyzing directional spectrum waves is introduced in this paper Basically, MLM (Maximum Likelihood Method) was used for this program which was additionally consisted of performing spectral and time domain analysis for two dimensional irregular waves. Moreover, the directionality of directional spectrum waves generated by single summation and double summation method was investigated based on MLM. The directionality from each summation method has good agreement compared with that of target wave spreading function in the case of single wide directional spectrum waves. In addition to this, the resolution of directionality in double summation method was investigated as introducing coherence function between each wave component

• 한국음향학회지
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• 제21권4호
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• pp.146-146
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• 2002

We present a new technique for achieving source separation when given only a single channel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single channel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• Journal of Power Electronics
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• 제16권1호
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• pp.18-26
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• 2016

This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

• 한국정보과학회논문지:소프트웨어및응용
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• 제33권1호
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• pp.32-43
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• 2006

Enterprise JavaBeans (EJB)는 컴포넌트 기반 소프트웨어 개발 (Component-based Development, CBD)을 위해 보급된 환경이다. 컴포넌트는 재사용 단위의 복합 객체이지만, EJB는 객체단위의 작은 컴포넌트이므로 다수의 엔터프라이즈 빈을 복합하여 큰 단위 재사용을 지원해야 한다. 따라서 EJB를 이용하여 컴포넌트를 상세 설계 및 구현하기 위한 구체적이고 실용적인 기법이 필요하다. 본 논문에서는 CBD의 구성요소를 EJB를 이용하여 어떻게 설계하는지의 지침과 기법을 제시한다. 단일, 복합, 화이트, 블랙 박스, 다중 인터페이스, 가변성을 지원하는 EJB 환경의 컴포넌트 설계 및 구현 기법을 제시한다. 사례 연구를 이용하여 제시한 설계 기법을 보이고, CBD 컴포넌트의 특징과 본 논문의 기법을 비교하여 검증한다. 결론적으로 EJB 환경에서 컴포넌트의 재사용성, 활용성, 이식성을 더욱 증가 시킬 것이다.

• 방송공학회논문지
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• 제20권4호
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• pp.545-556
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• 2015

차세대 3차원 디스플레이 및 서비스를 지원하기 위한 HEVC 기반 3차원 비디오 코딩 표준(3D-HEVC)이 최근 완료되었다. 3D-HEVC는 소수의 텍스처 영상(Texture image)과 깊이 영상(Depth map image)으로 구성된 Multi-view plus depth (MVD) 포맷을 효율적으로 처리하기 위한 표준으로써 H.264/AVC와 HEVC에서 사용하는 단일 계층 부호화 방법과 더불어 텍스처 영상들간, 깊이 영상들간, 텍스처 영상과 깊이 영상들간의 예측을 수행하는 인터-컴포넌트 부호화 기술을 추가적으로 사용한다. 본 논문에서는 3D-HEVC 표준의 일반적인 코딩 구조, 3D-HEVC 기술의 기반이 되는 인터-컴포넌트 부호화 기술 및 인터-컴포넌트 부호화 효율에 중요한 영향을 미치는 시차 벡터(Disparity vector) 유도 기술에 대해 상세히 소개한다. 또한 본 논문에서는 3D-HEVC의 부호화 효율을 검증하기 위해 각 시점을 HEVC로 부호화한 방법과 단순 다시점 확장 표준인 MV-HEVC와의 성능평가를 수행한다.

• 공업화학
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• 제10권1호
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• pp.166-172
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• 1999

폐수중 중금속 이온을 제거하기 위한 방법으로 키토산 비드에 의한 금속 이온의 고정층 흡착 특성을 조사하였다. 게껍질로부터 키틴을 추출하고 이를 탈아세틸화 반응시켜 키토산을 제조하였다. 키토산은 비드로 만들어 중금속 흡착제로 사용하였다. 키토산 비드에 대한 $Cu^{2+}$, $Co^{2+}$, $Ni^{2+}$ 이온의 단성분 평형 흡착 실험 결과로부터 Freundlich와 Langmuir 흡착등온식을 결정하였다. 흡착등온식에 의하면 키토산 비드에 대한 중금속 이온의 흡착 세기는 $Cu^{2+}$>$Co^{2+}$>$Ni^{2+}$의 순서로 나타났다. 키토산 비드에 대한 중금속 이온의 단성분 또는 다성분계 고정층 흡착 실험으로부터 흡착 파과곡선을 구하였다. 단성분 흡착등온식으로 다성분 흡착 평형을 예측할 수 있는 IAS (ideal adsorbed solution) 이론을 적용하여 LDFA (linear driving force approximation)에 의한 고정층 흡착 모델식을 수치해 기법으로 모사하여 실험결과와 비교하였다. LDFA에 의한 모델식을 적용한 결과 키토산 비드에 대한 중금속 이온의 단성분 및 다성분계 고정층 흡착거동을 잘 모사할 수 있었다.

• 한국의류학회지
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• 제18권5호
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• pp.661-673
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• 1994

We have gathered a fatty acid to recycle the waste oil of food manufacturing process, and then made a soap from the waste oil by alkali saponification. Effects of the washing elements such as the concentration of the soap, temperature and time were evaluated to find out the optimum washing conditions, and results are as follows. 1. We could find soaps made from the soybean oil (A), corn oil (B), rape seed salad oil (C), cotton seed oil (D) and a soap consisting of the each oil 25% respectively (I) had the lowest surface tension at the concentration of 0.225% -0.25%. Compared with the single fatty-acid soap, the multi-component soap I showed the lower surface tension at the cmc. 2. All the samples of A-I showed the lowest contact angle for the solid material at the concentration of 0.25%. The multi-component soap of I showed higher contact angle than the single.component soaps of A, B, C and D. 3. The soap G, made from the waste oil, show lower surface tension than 5, made from the complex raw fats of the eatable fatty oil acid and H, commercial soap. 4. The washing efficiency depends on the washing time. Especially the 25-minute was found to be the optimum washing time. 5. The highest washing efficiency was found at the 0.25% cont. reagardless of the washing temperature. At 0.15% concentration level the washing efficiency reduces as washing tem- perature increases. At 0.3% concentration level the highest washing efficiency was found between $50^{\circ}$-$60^{\circ}$. 6. The soap made from the waste oil showed the highest washing efficiency in terms of concentration, temperature, and time. 7. The soap made from the waste oil showed the similiar concentration of hydrogen ion to the synthetic detergent. 8. The hand value of the fabric washed by the soap made from the waste oil was a little lower value than those washed by the synthetic detergent.

• 산업경영시스템학회지
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• 제42권4호
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• pp.194-202
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• 2019

Reliability analysis of the components frequently starts with the data that manufacturer provides. If enough failure data are collected from the field operations, the reliability should be recomputed and updated on the basis of the field failure data. However, when the failure time record for a component contains only a few observations, all statistical methodologies are limited. In this case, where the failure records for multiple number of identical components are available, a valid alternative is combining all the data from each component into one data set with enough sample size and utilizing the useful information in the censored data. The ROK Navy has been operating multiple Patrol Killer Guided missiles (PKGs) for several years. The Korea Multi-Function Control Console (KMFCC) is one of key components in PKG combat system. The maintenance record for the KMFCC contains less than ten failure observations and a censored datum. This paper proposes a Bayesian approach with a Dirichlet mixture model to estimate failure time density for KMFCC. Trends test for each component record indicated that null hypothesis, that failure occurrence is renewal process, is not rejected. Since the KMFCCs have been functioning under different operating environment, the failure time distribution may be a composition of a number of unknown distributions, i.e. a mixture distribution, rather than a single distribution. The Dirichlet mixture model was coded as probabilistic programming in Python using PyMC3. Then Markov Chain Monte Carlo (MCMC) sampling technique employed in PyMC3 probabilistically estimated the parameters' posterior distribution through the Dirichlet mixture model. The simulation results revealed that the mixture models provide superior fits to the combined data set over single models.

• The Korean Journal of Physiology
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• 제26권1호
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• pp.27-35
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• 1992

We used the whole cell patch clamp technique to examine the ionic basis for the tail current after depolarizing pulse in single atrial myocytes of the rabbit. We recorded the tail currents during various repolarizations after short depolarizing pulse from a holding potential of -70 mV. The potassium currents were blocked by external 4-aminopyridine and replacement of internal potassium with cesium. The current was reversed to the outward direction above +10 mV. High concentrations of intracellular calcium buffer inhibited the activation of the current. Diltiazem and ryanodine blocked it too. These data suggest that the current is activated by intracellular calcium released from sarcoplasmic reticulumn. When the internal chloride concentration was increased, the inward tail current was increased. The current was partially blocked by the anion transport blocker niflumic acid. The current voltage curve of the niflumic acid sensitive current component shows outward rectification and is well fitted to the current voltage curve of the theoretically predicted chloride current calculated from the constant field equation. The currents recorded in rabbit atrial myocytes, with the method showing isolated outward Na Ca exchange current in ventricular cells of the guinea pig, suggested that chloride conductance could be activated with the activation of Na/ca exchange current. From the above results it is concluded that a chloride sensitive component which is activated by intracellular calcium contributes to tail currents in rabbit atrial cells.