• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.869-877
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• 2020

The power consumption in the low consistency (LC) refining is an important indicator for the optimal control of the process and it is composed of the net power and the no-load power. The refining efficiency and process characterization of LC refining are directly affected by power consumption. In this paper, the effect of pulp consistency and average fiber length on the power consumption and refining efficiency were studied through the LC refining trials conducted by an experimental disc refiner. It is found that the curve of power-gap clearance can be divided into constant power section, power reduction section, and power increase section. And the no-load power and the adjustable domain of loading applied by the refining plates will increase as the increase of pulp consistency, while the increase of net power is larger than that of no-load power which makes the increasing of refining efficiency. Meanwhile, the adjustable domain of loading applied by the refining plates can be slightly improved by increasing the average fiber length, but its effect on the no-load power in the LC refining process can be neglected. The study of power consumption in LC refining is of positive significance for the proper selection of pulp properties in LC refining, in-depth exploration of refining mechanism, and energy consumption reduction in refining.

• 한국위성정보통신학회논문지
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• 제12권4호
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• pp.115-119
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• 2017

상호변조왜곡은 원신호의 S/N도 악화시키고 인접채널에도 간섭 영향을 미친다. 상호변조왜곡은 전력증폭기의 비선형 특성에 의해서 주로 발생된다. 비선형 특성을 갖는 전력증폭기가 메모리 효과를 갖는다면 전력증폭기에서 발생되는 상호변조왜곡은 다양하고 복잡한 형태로 발생된다. 상호변조왜곡을 개선하는 방법으로 전치왜곡기가 주로 사용된다. 전치왜곡기의 성능을 충분하게 활용하기 위해서는 전력증폭기가 갖는 메모리 효과를 줄여야 한다. 본 논문에서는 전력증폭기에서 발생하는 메모리 효과를 줄이기 위한 바이어스 회로의 설계 방법에 대해서 기술하였다. 메모리 효과를 줄이기 위해서 바이어스 회로는 신호에 대해서는 높은 임피던스를 가져야 하며, 포락선(변조신호)에 대해서는 낮은 임피던스를 가져야 한다. 더불어 신호의 2차 고조파에 대해서도 낮은 임피던스를 가져야 한다. 메모리 효과를 고려해서 설계한 바이어스 회로의 성능을 확인해 보기 위해서 170 ~ 220MHz에서 동작하는 전력증폭기를 설계 및 구현하였다. 전력증폭기에 적용한 바이어스 회로는 동작주파수 대역에서 큰 임피던스를 가지며, 포락선 신호와 신호의 2차 고조파에서는 낮은 임피던스를 갖는다. 성능 측정결과 비대칭적으로 발생되는 상호변조왜곡 성분이 3.7dB 개선됨을 알 수 있었다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 춘계학술대회논문집
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• pp.30-34
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• 1995

The operator's performance of nuclear power plants is affected by many performance shaping factors(PSF). The objective of this study is to find out the PSFs and their effect on the nuclear power plant operations. We extracted PSFs in five category, and identified the relationships between PSFs and performance using the four survey methods; literture survey, case study, video task analysis and questionnaire survey. Finally the knowledge on PSFs and their effect was represented as rule form for cognitive simulation.

• Corrosion Science and Technology
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• 제15권4호
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• pp.171-181
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• 2016

In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

• 열처리공학회지
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• 제17권4호
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• pp.236-240
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• 2004

Effect of plasma power on PECVD process were investigated in this study. TiN and TiCN films were deposited on nitrided STD11 steel with 600W, 1,200W and 1,600W plasma power. As the plasma power was increased, the preferred orientation was reinforced from (200) to (111) and the hardness of films was improved. The low plasma power was, however, effective for improving of adhesion force of films. Regarding above properties, TiN and TiCN films were deposited by gradient plasma power. It was possible to get high hardness as well as adhesion force through gradient plasma power.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.1090-1094
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• 2017

The determinants of the public's nuclear power acceptance have received considerable attention as decisive factors regarding nuclear power policy. However, the contingency of the relative importance of different determinants has been less explored. Building on the literature of psychological distance between the individual and the object, the present study demonstrates that the relative effects of different types of perceived risks regarding nuclear power generation differ across acceptance targets. Using a sample of Korea, our results show that, regarding national acceptance of nuclear power generation, perceived risk from nuclear power plants exerts a stronger negative effect than that from radioactive waste management; however, the latter exerts a stronger negative effect than the former on local acceptance of a nuclear power plant. This finding provides implications for efficient public communication strategy to raise nuclear power acceptance.

• 조명전기설비학회논문지
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• 제15권5호
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• pp.41-45
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• 2001

본 논문은 전력계통의 조류해석시에 STATCOM과 UPEC의 모선전압 제어효과를 비교연구하였다. 시뮬레이션은 전력계통의 종합해석용 소프트웨어인 PSS/E를 사용하였으며, PSS/E에서 아직 제공하지 않는 UPFC의 모선 전압에 대한 효과를 해석하기 위해, 선로에서의 유효·무효전력과 모선의 전압이 적절히 제어되고 있는 상황에서 UPFC룰 동기조상기와 부하로 등가하여 나타내었다. 이러한 UPEC의 병렬 인버터가 설치된 모선의 전압제어뿐만 아니라 직렬 인버터를 통하여 선로의 유효·무효전력을 효과적으로 제어함으로써 전력계통의 조류해석시에 STATCOM 보다 넓은 범위의 모선전압을 효과적으로 제어할 수 있음을 확인할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1518-1526
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• 2015

For now, there are some low frequency oscillations in the power system which feature low frequency oscillation with positive damping and cannot be explained by traditional low frequency oscillation mechanisms. Concerning this issue, the dynamic damping effect is put forward on the basis of the power-angle curve and the study of damping torque in this article. That is, in the process of oscillation, damping will dynamically change and will be less than that of the stable operating point especially when the angle of the stable operating point and the oscillation amplitude are large. In a situation with weak damping, the damping may turn negative when the oscillation amplitude increases to a certain extent, which may result in an amplitude-increasing oscillation. Finally, the simulation of the two-machine two-area system verifies the arguments in this paper which may provide new ideas for the analysis and control of some unclear low frequency phenomena.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.155-157
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• 2001

This paper presents an comparative study on the effect of SSSC and UPFC to the power system static analysis. SSSC is used to control active power flow in transmission lines by controlling the phase angle of the injected voltage source which is in rectangular to the line current. UPFC is used to control the magnitude and phase of the injected voltage sources which are connected both in series and in parallel with the transmission line to control power flow and bus voltage. To compare the effect of SSSC and UPFC in power system static analysis, the PSS/E simulation program is used. As the FACTS device model such as SSSC and UPFC is not provided in PSS/E yet, an equivalent load model is used. This procedure is implemented by IPLAN which is an external macro program of PSS/E. The simulation results show that UPFC is more effective to improve bus voltage than SSSC in power system static analysis.

• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.132-139
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• 2011

We investigate theoretically the combined effect of fiber chromatic dispersion and self-phase modulation (SPM) on multi-channel subcarrier multiplexed (SCM) optical transmission systems in terms of the detected RF carrier power and SPM-induced power gain after transmission over single-mode fiber (SMF) links. According to the calculated power gain due to the SPM effect at the transmission distance of P3dB using the detected radio-frequency (RF) carrier power after photo-detection, the power gain is significantly degraded with large optical modulation index (OMI), small SCM channel spacing, and large fiber launching power because of the increased interaction between subcarrier channels. The nonlinear phase shift due to linear and nonlinear fiber characteristics is investigated to explain these results in detail. The numerical simulation results show that the OMI per SCM channel has to be smaller than 10 % for the fiber launching power of 10 dBm to guarantee prevention of SPM-induced power gain degradation below 0.5 dB for the SCM system with the channel spacing of 100 MHz. This result is expected to be utilized for the optical transmission systems using the SCM technology in future radio-over-fiber (RoF) networks.