Improved Frequency Mitigation of a Variable-Speed Wind Turbine

Mingguang Li,Dejian Yang,Yong Cheol Kang(강용철),Junhee Hong(홍준희) 대한전기학회 2018 전기학회논문지 Vol.67 No.6

For a power grid that has a high wind penetration level, when wind speeds are continuously fluctuating, the maximum power point tracking (MPPT) operation of a variable-speed wind turbine (VSWT) causes the significant output power fluctuation of a VSWT, thereby significantly fluctuating the system frequency. In this paper, an improved power-smoothing scheme of a VSWT is presented that significantly mitigates the frequency fluctuation caused by varying wind speeds. The proposed scheme employs an additional control loop based on the frequency deviation that operates in combination with the MPPT control loop. To improve the power-smoothing capability of a VSWT in the over-frequency section (OFS), the control gain of the additional loop, which is set to be inversely proportional to the rotor speed, is proposed. In contrast, the control gain in the under-frequency section is set to be proportional to the rotor speed to improve the power-smoothing capability while avoiding over-deceleration of the rotor speed of a VSWT. The proposed scheme significantly improves the performance of the power-smoothing capability in the OFS, thereby smoothing the frequency fluctuation. The results clearly demonstrate that the proposed scheme significantly mitigates the frequency fluctuation by employing the different control gain for the OFS under various wind penetration scenarios.

司法與産權

진명광(陈,明光,Chen Mingguang) 경북대학교 아시아연구소 2009 아시아연구 Vol.- No.5

범인의 모든 재산을 “籍沒”하는 것은, 중국고대의 전국시기 이래부터 시행된 일종의 형벌이었다. 그것은 사법행위이자, 경제행위이다. 본문에서는 사법과 재산권, 양방면을 고려하여, 唐律疏議과 유관한“籍沒家產”의 율령을 중심으로, 그 유래와 변화를 고찰하면서, 당오대“籍沒家產”의 죄범대상, 사법과정의 집행(실행), 籍沒의 家産範圍, 정 부의 籍沒家產의 계속되는 재산권 처리 및 법의 밖에서 형을 사용하는 등의 문제를 논하고자 한다. 진한에서 수에 이르기까지 비록 범인의 모든 재산을 籍沒하는 것의 약간의 규정은 있었으나, 재산을 籍沒의 대상이 있으면 용서함이 없어서 범람하였다. 이것은 중국고대전제왕권이 사유재산을 마음대로 박탈하는 일종의 표현이었다. 唐律疏議의 전에 전해져온 율문은, 단지 梁律에서 謀反, 降叛, 大逆세 가지 중죄의 범인에게만 모든 재산을 籍沒하게 한다고 명확하게 규정되어있다. 그러나, 관련 소송의 실례 분석에 의하면, 이러한 하나의 율문은 전 시기의 사법실행에 근 원이 있다.唐律疏議와 관련하여 재산권 籍沒의 범인 대상과 그 상관문제의 규정을 전대미문으로 상세하고도 명확하게 적용하고, 재산권 籍沒의 적용대상은 한정범 “모반”과 “대역”의 죄, 그리고 여러 실제행동에 한정되었으며, 일정한 위해자로 구성되었다. 뿐만 아니라 범죄의 내용과 경위에 따라 구분되었으며, 또한 죄에 연루되는 대상이 대단히 감소되었다. 이전 시기에, 이것은 사유재산의 일정한 수준으로 존중과 보호가 구현되었고, 중국고대법제와 재산권제도의 한 차례 진보를 이루었다는 것은 의심할 바 없다. 당대의 정부는 자산의 재산권 籍沒에 대한 후속조치형식에서 중요하게 여긴 두 가지가 있었는데, 하나는 재물을 파는 것(貨賣)으로서 일차성 地收利였고, 다른 하나는 관청의 자산을 가지고 경영하는 행위로, 전답을 내어 소작을 하게 하여 임차료를 받는 경우였다. 그 외에, 籍沒한 전답을 무상으로 백성에게 나누어준 사례도 소수 존재하였다. 오대시기에 가혹한 법과 잔혹한 형벌을 제멋대로 함부로 하여, “籍沒家產”의 사용범위를 확대 시켰는데, 심지어는 재산을 탐내어 모함하여 籍沒하는 “刑人利財”가 출현하였다. 이에 대해, 후주의 태조 곽위가 바로잡았다. 오대시기의 정부는 “籍沒家產”의 후속재산권 조치에 대하여, 관에서 부분적으로 가산을 籍沒하거나 혹은 관영의 세금으로 이득을 챙기거나, 사유 혹은 사영하게 하여 납세하는 방식으로 처리하였는데 이는 오대시기 재산권변동의 일종의 비교적 두드러진 현상이었다. Confiscate some of criminal's family property had been carried out as punishment since the Warring States Period in ancient China. It is not only a judicial action but also an economical action. This thesis will focus on the source and development of "Tang lu shu yi" about family property confiscation, and then discuss some issues such as, who needs to be confiscated the private property; the procedure of carring out the confiscation; the scope of confiscation; the disposure of the confiscated property and the cruel penalty beyond the legal means during the Tang and Five Dynasties.

Carbon nanofibers supported Ru catalyst for sorbitol hydrogenolysis to glycols: Effect of calcination

Jinghong Zhou,Long Zhao,Hong Chen,Mingguang Zhang,Zhijun Sui,Xinggui Zhou 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5

Carbon nanofiber (CNFs) supported Ru catalysts for sorbitol hydrogenolysis to ethylene glycol and propylene glycol were prepared by incipient wetness impregnation, calcination and reduction. The effect of calcination on catalyst properties was investigated using thermal gravimetry analysis, temperature-programmed reduction, X-ray diffraction,X-ray photoelectron spectroscopy, transmission electron microscopy and N2 physisorption. The results indicated that calcination introduced a great amount of surface oxygen-containing groups (SOCGs) onto CNF surface and induced the phase transformation of Ru species, but slightly changed the texture of Ru/CNFs. The catalytic performance in sorbitol hydrogenolysis showed that Ru/CNFs catalyst calcined at 240 oC presented the highest glycol selectivities and reasonable glycol yields. It was believed that the inhibition and confinement effect of SOCGs around Ru particles as well as the high dispersion of Ru particles was the key factor for the catalytic activity.

Speaker Recognition via Block Sparse Bayesian Learning

Wei Wang,Jiqing Han,Tieran Zheng,Guibin Zheng,Mingguang Shao 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.7

In order to demonstrate the effectiveness of sparse representation techniques for speaker recognition, a dictionary of feature vectors belonging to all speakers is constructed by total variability i-vectors. Each feature vector from unknown utterance is expressed as linear weighted sum of a dictionary. The weights are calculated using Block Sparse Bayesian Learning (BSBL) where the sparsest solution can be obtained. By exploiting the speech signal’s block structure and intra-block correlation, the system performance is improved. The experimental results validate that our method outperforms the baseline systems and the system using Orthogonal Matching Pursuit (OMP) algorithm on the typical corpus and realizes the identity validation function.

Dynamic Unloading Instability Mechanism of Underground Cavern Based on Seepage-Damage Coupling

Li-Ping Li,Wenfeng Tu,Zongqing Zhou,Shao-shuai Shi,Mingguang Zhang,Yuxue Chen 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.5

The seepage-damage coupling effect will aggravate the instability of the surrounding rock during the unloading process of underground cavern excavation. Considering this coupling effect and excavation disturbance, the theoretical solution of the stress state of surrounding rock is derived by using the elastic-brittle damage model. The dynamic criterion of the instability and water inrush is presented. Based on the theoretical derivation, the calculation program for the seepage-damage analysis of the surrounding rock under dynamic unloading is programmed, and the seepage flow and the radius of the damage zone of the surrounding rock are calculated. By analysing the variation of radius of the damaged zone with pore water pressure and excavation radius under different calculation conditions, the influence of dynamic unloading disturbance on the damaged zone of the surrounding rock is discussed. The radius of the damaged zone increases with the pore water pressure and excavation radius. Considering the effect of dynamic unloading, the calculation result of the damaged zone radius and seepage discharge of underground cavern are much larger than the theoretical calculation and coupling calculation of seepage-damage without dynamic unloading. Research methods and results can provide guidance and reference for similar engineering research.

Linkages between market orientation and brand performance with positioning strategies of significant fashion apparels in Pakistan

Rana Faizan Gul,Dunnan Liu,Khalid Jamil,Sajjad Ahmad Baig,Fazal Hussain Awan,Mingguang Liu 한국의류학회 2021 Fashion and Textiles Vol.8 No.1

The study explores the importance of market orientation strategy to enhance brand performance and the mediating role of positioning strategies. The researcher used questionnaires to collect data from the managers of middle and high fashion apparel manufacturing firms based on the quantitative research approach. The data was collected from 220 managers who were directly involved in the decision-making process. The analysis has revealed a significant impact of market orientation strategy on Pakistan’s fashion brands’ performance, with the mediating effect of positioning strategies. The management of firms must give considerable importance to market orientation strategies to enhance overall brand performance. The market orientation strategies’ development is also helpful in building different positioning strategies through which performance gets enhanced. This study contributes valuable literature because it focuses on the fashion apparel industry’s context, which is almost most important for everyone in the present era. Firms can focus on tight product quality control, innovative manufacturing processes, trained and experienced personnel, and extensive customer service.