Fast Voltage-Balancing Scheme for a Carrier-Based Modulation in Three-Phase and Single-Phase NPC Three-Level Inverters

Xi Chen,Shenghua Huang,Dong Jiang,Bingzhang Li 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

In this paper, a novel neutral-point voltage balancing scheme for NPC three-level inverters using carrier-based sinusoidal pulse width modulation (SPWM) method is developed. The new modulation approach, based on the obtained expressions of zero sequence voltage in all six sectors, can significantly suppress the low-frequency voltage oscillation in the neutral point at high modulation index and achieve a fast voltage-balancing dynamic performance. The implementation of the proposed method is very simple. Another attractive feature is that the scheme can stably control any voltage difference between the two dc-link capacitors within a certain range without using any extra hardware. Furthermore, the presented scheme is also applicable to the single-phase NPC threelevel inverter. It can maintain the neutral-point voltage balance at full modulation index and improve the voltage-balancing dynamic performance of the single-phase NPC three-level inverter. The performance of the proposed strategy and its benefits over other previous techniques are verified experimentally.

3D 프린팅을 적용한 Iris van Herpen 컬렉션 시즌별 테마에 따른 표현방법 분석

XI CHEN,유영선 한국복식학회 2023 服飾 Vol.73 No.3

This study aims to investigate the change in 3D printing fashion expression characteristics over the past 10 years by examining the early 3D printing fashion works of Iris van Herpen, a leader in the application of this technology to fashion. The research method consisted of a literature review and case analysis. In this research, 166 3D printing works from Iris Van Herpen's collections (SS 2011 to SS 2021) were collected and analyzed. Iris van Herpen’s 3D printing fashion characteristics that appeared frequently were as follows: 'retro futurism', 'futuristic fantasy', 'biomimicry', and 'sustainability'. 'Retro futurism' was expressed as a mixture of handcraft and 3D printing technology based on chrome color. 'Futuristic fantasy' was expressed in 3D printing fashion with fantastic images on the theme of humans in a virtual world with digital technology. 'Biomimicry' was expressed as an innovative 3D printing fashion form inspired by nature with parametric technology. 'Sustainability' was expressed in nature-friendly fashion by applying a parametric design method to upcycled materials.

A linguistic analysis of lying in negative evaluations: The speech act performance of Chinese learners of Korean

Xi Chen,Jaehoon Yeon 국제한국어교육학회 2015 한국어 교육 Vol.26 No.영문호

이 논문은 중국인 한국어 학습자와 한국어 화자들 사이의 ‘거짓말’ 화행 양상을 언어학적으로 분석한 연구이다. 여기서 말하는 ‘거짓말’이란 요청, 사과, 거절 등과 같은 화행의 일종으로서 ‘부정적 평가’에 속하며 대화 참여자나 상황을 고려한 소위 ‘선의의 거짓말’을 가리키는 것으로 이해할 수 있을 것이다. 우리는 중국인 한국어 학습자 15 명과 한국어 화자 15명을 대상으로 담화완성테스트(DCT)와 부연설명질문지(QFE)를 사용하여 피실험자들의 화행을 분석하였다. 피실험자 자신들의 설명과 한국어교육 전문가 다섯 명의 판정을 종합해 ‘거짓말’ 화행을 가려내고 통계 처리를 바탕으로 다음과 같은 결론에 도달했다. 한국어 화자들이 중국인 한국어 학습자들보다 (선의의) 거짓말을 더 많이 수행하는 것으로 나타났다. 그리고 두 집단 모두 부정적 평가가 사물에 관련된 경우보다 사람에 관련된 경우에 ‘거짓말’ 화행을 더 많이 사용한다. 그러나 화자와 청자 사이의 친소관계(distance)나 상하관계(power)는 거짓말 사용에 직접적 상관 관계를 보여주지 않았다. 이 연구는 지금까지 화행 연구 중에서 상대적으로 연구가 부진했던 부정평가와 ‘거짓말’ 화행에 대한 분석을 시도했다는 점에서 의미가 있다. 또한 한국어 화자 와 중국인 한국어 학습자 사이에 보이는 화행 수행의 차이를 문화인식(cultural awareness)의 관점에서 해석해 볼 수 있는 가능성도 열어 주었다. The current study is concerned with cross-cultural speech act performance, specifically focusing on the performance of lying in situations where the speakers perceive or adopt a negative evaluation. The current study shows that more lies are found in the Korean native speaker group than the Chinese learner group. Also, lies are more frequent in situations where evaluations target people than in situations where evaluations target an entity. However, the number of lies is not directly correlated to changes in the relative social distance and power between the speaker and hearer. Moreover, the fact that the preference of different lying strategies also differs between the two groups may imply some differences in terms of cultural awareness.

Invited Mini Review : Stem cell maintenance by manipulating signaling pathways: past, current and future

( Xi Chen ),( Shoudong Ye ),( Qi Long Ying ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.12

Pluripotent stem cells only exist in a narrow window during early embryonic development, whereas multipotent stem cells are abundant throughout embryonic development and are retained in various adult tissues and organs. While pluripotent stem cell lines have been established from several species, including mouse, rat, and human, it is still challenging to establish stable multipotent stem cell lines from embryonic or adult tissues. Based on current knowledge, we anticipate that by manipulating extrinsic and intrinsic signaling pathways, most if not all types of stem cells can be maintained in a long-term culture. In this article, we summarize current culture conditions established for the long-term maintenance of authentic pluripotent and multipotent stem cells and the signaling pathways involved. We also discuss the general principles of stem cell maintenance and propose several strategies on the establishment of novel stem cell lines through manipulation of signaling pathways. [BMB Reports 2015; 48(12): 668-676]

Effect of windshields on the aerodynamic performance of a four-box bridge deck

Xi Chen,Elena Dragomirescu 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.1

A new type of bridge deck section consisting of four-box decks, two side decks for vehicular traffic lanes and two middle decks for railway traffic, has been experimentally investigated for determining its aerodynamic properties. The eight flutter derivatives were determined by the Iterative Least Squares (ILS) method for this new type of four-box deck model, with two windshields of 30 mm and 50 mm height respectively. Wind tunnel experiments were performed for angles of attack  = ±6°, ±4°, ±2° and 0° and Re numbers of 4.85×105 to 6.06×105 and it was found that the four-box deck with the 50 mm windshields had a better aerodynamic performance. Also, the results showed that the installation of the windshields reduced the values of the lift coefficient CL for the negative angles attack in the range of -6° to 0°, but the drag coefficient CD increased in the positive angle of attack range. However, galloping instability was not encountered for the tested reduced wind speeds, of up to 9.8. The aerodynamic force coefficients and the flutter derivatives for the four-box deck model were consistent with the results reported for the Messina triple-box bridge deck, but were different from those reported for the twin-box bridge decks.

Toward the AI-enabled digital financial services innovation: The role of positive emotional interactions with users

Xi Chen,Cheng Chen,Yi Cheng 한국지능정보시스템학회 2022 한국지능정보시스템학회 학술대회논문집 Vol.2022 No.6

Purpose: Advancements in the AI-enabled technology have made the mobile and online the dominant place for launching financial services innovation. The existing literatures have revealed that online environment is easy to arouse users’ emotions and promote emotional behavior, but still lack evidence how emotions affect the use of digital financial services. This study then develops a research model and two experiments to investigate whether and how the afforance of positive emotions through AI-enabled digital financial services innovation will enhance user’s services adoption. Design/methodology/approach: This paper used a mixed-methods approach to empirically study the role of emotions on users’ adoption of digital financial services then providing the evidence to the value of positive emotions arousal through AI-enabled interaction. An convenience nonprobability sampling approach with total of 280 responses were collected to examine the model and two behavioral experiment with total of 121 and 140 participants respectively, as well as the partial least squares technique and paired sample mean t-test were utilized for data analysis. Findings: Positive emotions promote users’ intentions to continue to use digital financial services and also exert a significant positive role through the intermediary effect of trust and satisfaction(Study 1). The users’ perceptions of the value rises in the state of positive emotional arousal and perception of the risk of financial loss decreases (Study 2). The anthropomorphic artificial intelligence service assistant can effectively evoke user’s positive emotions in service recommendations, improve their willingness of adoption and value perception and reduce perceived risk(Study 3). Originality/value: Based on emotion theory and expectation confirmation theory (ECT), this study reveals that as features, positive emotions interaction help improve users’ value perception and adoption intention, also help us further understand the role of user’s emotions arousal in digital financial service This research has practical importance in terms of understanding the affordance of positive emotional interaction through AI-enabaled service is a valuable way to carry out service innovation in digital financial platform.

Optimized Discriminant Locality Preserving Projection of Gabor Feature for Biometric Recognition

Xi Chen,Jiashu Zhang 보안공학연구지원센터 2012 International Journal of Security and Its Applicat Vol.6 No.2

Particle size distributions and concentrations above radiators in indoor environments: Exploratory results from Xi`an, China

Xi Chen,Angui Li 대한환경공학회 2015 Environmental Engineering Research Vol.20 No.3

Particulate matter in indoor environments has caused public concerns in recent years. The objective of this research is to explore the influence of radiators on particle size distributions and concentrations. The particle size distributions as well as concentrations above radiators and in the adjacent indoor air are monitored in forty-two indoor environments in Xi’an, China. The temperatures, relative humidity and air velocities are also measured. The particle size distributions above radiators at ten locations are analyzed. The results show that the functional difference of indoor environments has little impact on the particle size distributions above radiators. Then the effects of the environmental parameters (particle concentrations in the adjacent indoor air, temperatures, relative humidities and air velocities) on particle concentrations above radiators are assessed by applying multiple linear regression analysis. Three multiple linear regression models are established to predict the concentrations of PM10, PM2.5 and PM1 above radiators.

Performance-based Analysis of Elastoplastic Rotational Behavior of Multi-cell Shaped Concrete-filled Steel Tubular Connection

Xi Chen,Jian-yang Xue,Hechao Li,Guangxu Tu,Xin Lu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10

Experimental and theoretical research on the rotational behavior of Multi-cell shaped concrete-filled steel tubular (MCFST) connection under low-period cyclic load is performed. The experimental results showed that the design parameters had significant effects on the elastic rotational stiffness of the connection, and affected the sequence and position of the plastic hinges appearance at the column and beam ends. Furthermore, the damage mechanism of the plastic hinge lines is obtained, and the simultaneous yielding for the plastic hinges results in the rapid increase of the beam end rotation. In order to handle the problem with irregular geometry boundary and uneven distribution of tightening-ring stresses a differential element of an unified material is proposed considering the effective tightening-ring stresses of special-shaped steel tube on confined concrete, which can be used to analyse the whole mechanical and damage performance of the connection. Combining unified design theory and experimental results, the calculation for the elastic bending rigidity of the connection is obtained. Finally, the moment-rotation relation model of the connection is proposed by regression analysis on experimental results, and the theoretical results are observed to agree well with the experimental results.

Evaluation Indicators and Model of Network Technical Anonymity

Xi Chen,Gang Li 보안공학연구지원센터 2013 International Journal of Future Generation Communi Vol.6 No.4