Research on the Inter-harmonics Equivalent Impedance of Series Hybrid Active Power Filter

Jian-gong, Zhang,Jian-ben, Liu,Shao-jun, Dai,Qiao-fu, Chen,Jun-jia, He The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

In the series hybrid active power filter (SHAPF) with magnetic flux compensation (MFC), the system current oscillate in the experimental results when adding the same phase harmonic current command in current control block. This condition endangers the security of the SHAPF. Taking the digit period average arithmetic as example, this paper explains the inter-harmonics current oscillation in the experiment. The conclusion is that the SHAPF is unstable to the inter-harmonics current in theory. Limited by the capacity of the inverter, the system current and the inverter output current do not increase to infinite. At last, some methods are proposed to solve this problem. From the practical viewpoint, the voltage feed-forward control is easy to achieve. It can suppress the current oscillation problems, and also improve the filtering effect. The feasibility of the methods is validated by both the emulation and experiment results.

First-principles calculations on ferroelectricity and lattice dynamics of Type-II multiferroic SmMn2O5

Dai Jian-Qing,Yuan Jin 한국물리학회 2021 Current Applied Physics Vol.29 No.-

In this work, we report on the structural, electronic, and ferroelectric properties of SmMn2O5 by using firstprinciples density functional theory plus on-site Coulomb interaction (DFT + U) calculations. A thorough analysis was preformed to reveal the competing characteristics of different high-temperature (T) phases and the polarization mechanism in the low-T multiferroic phase. We show that the structural characteristics of the high-T phases have a strong influence on the low-T multiferroicity. In addition to the spin-induced lattice distortion that reduces substantially the purely electronic ferroelectricity, the dominant polarization mechanism in low-T SmMn2O5 still originates from the electronic polarization. By performing mode decomposition of the Hellmann– Feynman forces and the lattice distortion induced by the q = (0.5, 0, 0) magnetic order, we find that the Raman-active Ag mode characterized by the Mn4+O6 octahedron distortion and synergistic displacement of Mn3+ and Sm ions is of primary importance, while the infrared (IR)-active B2u mode plays a secondary role. These findings provide a theoretical foundation for future studies concerning the enhanced magnetoelectric effects of SmMn2O5 due to its pure exchange–striction mechanism.

Bronchopulmonary Infection of Lophomonas blattarum

Jian Xue,Ying-Li Li,Xue-Mei Yu,Dai-Kun Li,Ming-Fang Liu,Jing-Fu Qiu,Jian-Jiang Xue 대한기생충학열대의학회 2014 The Korean Journal of Parasitology Vol.52 No.5

Reflection on Conservation of Cultural Heritage based on “Public/Common Heritage”

Dai Jian 국제온돌학회 2014 International Journal of Ondol Vol.2014 No.-

A critical steel yielding length model for predicting intermediate crack-induced debonding in FRP -strengthened RC members

Jian-Guo Dai,Kent A. Harries,Hiroshi Yokota 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.6

Yielding of the internal steel reinforcement is an important mechanism that influences the Intermediate Crack-induced debonding (IC debonding) behavior in FRP-strengthened RC members since the FRP is required to carry additional forces beyond the condition of steel yielding. However, rational design practice dictates an appropriate limit state is defined when steel yielding is assured prior to FRP debonding. This paper proposes a criterion which correlates the occurrence of IC debonding to the formulation of a critical steel yielding length. Once this length is exceeded the average bond stress in the FRP/concrete interface exceeds its threshold value, which proves to correlate with the average bond resistance in an FRP/concrete joint under simple shear loading. This proposed IC debonding concept is based on traditional sections analysis which is conventionally applied in design practice. Hence complex bond stress-slip analyses are avoided. Furthermore, the proposed model incorporates not only the bond properties of FRP/concrete interface but also the beam geometry, and properties of steel and FRP reinforcement in the analysis of IC debonding strength. Based upon a solid database, the validity of the proposed simple IC debonding criterion is demonstrated.

Ulleungdo and the Island Policy of the Joseon Period

Lin-jian DAI The Academy of Korean Studies 2024 Korea Journal Vol.64 No.1

In the Joseon period, the maritime ban policy gradually became a means of controlling the people when a reorganization of the military defense system and the preparation of countermeasures against the appearance of unidentified vessels were required. In the process, a maritime boundary consciousness was formed, and a defense system centered on the inner sea was established. As a result, islands located in the West and South Seas were transformed into garrison areas, receiving increased attention from the central government. By contrast, the change in the island policy toward Ulleungdo was relatively uncomplicated. In the early Joseon period, the governance of evacuating residents of Ulleungdo and the so-called island vacancy policy were carried out as a way of preventing damage from Japanese pirates. And the sutoje of Ulleungdo was formalized when the territorial dispute over Ulleungdo with Japan began in earnest at the end of the 17th century. The character of Ulleungdo was the same as that of the islands located on the West and South Seas in that it revealed the government’s determination to properly control domestic territory. The development of the sutoje of Ulleungdo was also related to changes in maritime territorial consciousness and island policies.

Research on the Inter-harmonics Equivalent Impedance of Series Hybrid Active Power Filter

Zhang Jian-gong,Liu Jian-ben,Dai Shao-jun,Chen Qiao-fu,He Jun-jia 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

In the series hybrid active power filter (SHAPF) with magnetic flux compensation (MFC), the system current oscillate in the experimental results when adding the same phase harmonic current command in current control block. This condition endangers the security of the SHAPF. Taking the digit period average arithmetic as example, this paper explains the inter-harmonics current oscillation in the experiment. The conclusion is that the SHAPF is unstable to the inter-harmonics current in theory. Limited by the capacity of the inverter, the system current and the inverter output current do not increase to infinite. At last, some methods are proposed to solve this problem. From the practical viewpoint, the voltage feed-forward control is easy to achieve. It can suppress the current oscillation problems, and also improve the filtering effect. The feasibility of the methods is validated by both the emulation and experiment results.

표류기록(漂流記錄)을 통해 본 19세기 초 조선 선비의 실천론(實踐論)과 대청인식(對淸認識) ― 『승차록(乘槎錄)』·『표해록(漂海錄)』을 중심으로―

대림검 ( Dai Lin-jian ) 고려대학교 민족문화연구원 2018 民族文化硏究 Vol.81 No.-

본고에서는 기존 조선후기 燕行使를 중심으로 對淸認識을 살펴보는 방식을 지양하며 19세기 초의 표류기록인 『乘槎錄』과 『漂海錄』을 연구 대상으로 삼아 거기서 나타난 재지 선비의 대청인식을 동시대 재경 선비의 대청인식과 비교하면서 고찰하였다. 18세기 말 19세기 초 재경 선비의 대청인식은 주로 청의 번영함을 목도하던 연행사에 의해 반영되었는데, 그들이 청의 현실적인 문제에 대한 주목을 통해 기존의 華夷論을 극복하고 北學論까지 나아갔지만 그 논리는 여전히 對明義理와 朝鮮中華主義를 근간으로 전개할 수밖에 없었다. 한편 청의 현실을 재성찰함에 따라 그들이 청에 대한 복수심이 위기의식으로 전환되기도 하였다. 이에 비해 『乘槎錄』과 『漂海錄』에서 나타난 재지 선비의 대청인식에서는 전통적 성리학에 대한 實踐論을 중심으로 청을 ‘道學적 修身의 공간’으로 간주할 뿐이지 조선의 현실을 반성할 수 있게 해주는 ‘타자’의 이미지로 객관화 시키지 못하였다. 다만 사실적으로 청의 주체성을 인정하면서도 문화적으로 조선을 청과 대등한 위치에 두려고 하던 점에서 재지 선비와 재경 선비의 공통점을 볼 수 있다. This paper, different from the previous researches which were focusing on Joseon envoys' perception of the Qing Dynasty in the Late Joseon Dynasty, surveyed the local scholars' perception of the Qing Dynasty by the records of drifting Seungsalok and Pyohaelok in the early 19th century, and compared with the perception of literati residing in Seoul in the same period. From the late 18th to the early 19th century, perception of the Qing Dynasty of literati residing in Seoul was mainly reflected by Joseon envoys. They witnessed the prosperity of the Qing Dynasty and paid close attention to the Qing's practical problems, thereby overcoming the established sino-barbarianism and moving towards the Bukhak thoughts. But, its theory was still based on the Joseon intellectuals' views on the Ming Dynasty and the Joseon sino-centrism. In addition, with the re-examination of the Qing's practical problems, their avenge minds on the Qing Dynasty turned into a crisis consciousness. By contrast, the local scholars' perception of the Qing Dynasty which was embodied in Seungsalok and Pyohaelok, centered on the practical theory of neo-confucianism. They could only regarded the Qing as a “space of self-cultivating through Taoist philosophy” but could not objectify it as “the other” that enables them to reflect on Joseon's own reality. In spite of this, the literati residing in Seoul and the local scholars still had something in common: while acknowledging the identity of the Qing Dynasty from the objective facts, and at the cultural aspects, hoping to put Joseon into a place where was equal to the Qing.

Hath1 Inhibits Proliferation of Colon Cancer Cells Probably Through Up-regulating Expression of Muc2 and p27 and Down-regulating Expression of Cyclin D1

Zhu, Dai-Hua,Niu, Bai-Lin,Du, Hui-Min,Ren, Ke,Sun, Jian-Ming,Gong, Jian-Ping Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Previous studies showed that Math1 homologous to human Hath1 can cause mouse goblet cells to differentiate. In this context it is important that the majority of colon cancers have few goblet cells. In the present study, the potential role of Hath1 in colon carcinogenesis was investigated. Sections of paraffin-embedded tissues were used to investigate the goblet cell population of normal colon mucosa, mucosa adjacent colon cancer and colon cancer samples from 48 patients. Hath1 and Muc2 expression in these samples were tested by immunohistochemistry, quantitative real-time reverse transcription -PCR and Western blotting. After the recombinant plasmid, pcDNA3.1(+)-Hath1 had been transfected into HT29 colon cancer cells, three clones were selected randomly to test the levels of Hath1 mRNA, Muc2 mRNA, Hath1, Muc2, cyclin D1 and p27 by quantitative real-time reverse transcription-PCR and Western blotting. Moreover, the proliferative ability of HT29 cells introduced with Hath1 was assessed by means of colony formation assay and xenografting. Expression of Hath1, Muc2, cyclin D1 and p27 in the xenograft tumors was also detected by Western blotting. No goblet cells were to be found in colon cancer and levels of Hath1 mRNA and Hath1, Muc2 mRNA and Muc2 were significantly down-regulated. Hath1 could decrease cyclin D1, increase p27 and Muc2 in HT29 cells and inhibit their proliferation. Hath1 may be an anti-oncogene in colon carcinogenesis.

Method for Group Decision-Making of Multi-Stakeholders with Category Preference on Alternatives

Dai Quan-chen,Zhu Jian-jun,Zhang Shi-tao 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.8

This paper studies the issue of decision making on some alternatives with category preference of multiple decision makers in which interest conflicts exist and the weights are unknown. It puts forward the method to firstly calculate the attribute weight in each decision maker’s circumstance through case-based learning and thus meet subjective preferences of different decision makers. Considering the interest conflicts between multiple decision makers, the fuzzy set theory is then used to optimize the weight of each decision makers to comply with objective requirements of group decision-making process. Finally, the total order relation of the alternative which does not only conform to the subjective preference information of the decision maker but also consist with the objective fact of group decision-making is obtained based on the calculation result of overall off-target distance for the alternative. The case indicates application procedures and method feasibility.