Incheon National University study pioneers breakthrough in wireless charging technology

The novel resonant, auto-adjusting rectifier developed for wireless power, can enhance efficiency via dynamic frequency adaptation

Incheon National University

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Wireless power transfer (WPT) enables device charging without direct physical or wired connections. Resonant circuits are key components of WPT systems that optimize energy transfer from the transmitter to the receiver. In parallel compensated receivers, capacitors balance the inductance of the receiver coil to achieve resonance, reducing circuit impedance, thereby enhancing power transfer.

The electromagnetic fields generated by such receivers can interfere with other electronic devices. Controlling this interference requires modulating the system's operating frequency. However, this modulation creates a mismatch between the modulated and resonant frequencies, severely degrading power output and system efficiency. Current strategies to correct this mismatch rely on additional hardware or complex circuitry, leading to energy loss, complex control settings, and bulkier designs.

In an attempt to find an innovative solution to overcome these challenges, a group of scientists led by Professor Dukju Ahn at Incheon National University, Korea, proposed a resonant tuning rectifier (RTR) for parallel resonant receiver systems. The novel RTR features a minimalist design that synchronizes its operation with the natural rhythm of the system’s primary current. “Our RTR does not require extra power components or complex feedback circuitry, rendering it more practical for real-world use,” says Prof. Ahn. The study was made available online on May 14, 2024 and was published in Volume 71, Issue 12 of IEEE Transactions on Industrial Electronics on December 01, 2024.

The RTR automatically adjusts effective capacitance to tune the resonant frequency by syncing control signals with the system’s current, compensating for differences between intrinsic resonance and modulation periods. Unlike existing methods, it uses a simple sensor coil to extract phase information without impacting performance, eliminating the need for transmitter-receiver communication.

Testing a 2.2 kW prototype for automobile charging showed that the RTR compensates for frequency modulation (80—90 kHz) in 70 ms, maintaining stable power output during misalignment and improving efficiency from 3.5% to 8.1%. Its zero-voltage system optimizes control settings to reduce power loss, offering a simple, cost-effective solution for real-time adaptation and stable power delivery.

“The automatic adjustment of resonant frequency impacts not only wireless charging but also induction heating, plasma generation, and power conversion,” explains Prof. Ahn. “With minimal energy loss, high efficiency, stable throughput, a minimalist design, and low system impact, RTR can significantly enhance wireless power system performance,” he concludes. As wireless charging becomes more widespread, the proposed RTR offers a promising solution to mitigate existing challenges, making this technology more accessible to everyday users.

 

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Reference

Authors: Saidul Alam Chowdhury1,2, Seongmin Kim3, Sangwon Kim3, Inkui Cho3, and Dukju Ahn1, *

Title of original paper: Resonant Tuning Rectifier for Parallel Compensated Receivers in Wireless Power Transfer

Journal: IEEE Transactions on Industrial Electronics

DOI: https://doi.org/10.1109/TIE.2024.3390737

Affiliations:        

1Incheon National University, Korea

2The University of Auckland, New Zealand

3Electronics and Telecommunications Research Institute, Korea

 

About Incheon National University

Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.

Website: https://www.inu.ac.kr/sites/inuengl/index.do?epTicket=LOG

 

About the author

Professor Dukju Ahn received a B.S. degree in electrical engineering from Seoul National University, Seoul, Korea, in 2007 and M.S. and Ph.D. degrees in electrical engineering from Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, in 2010 and 2012, respectively. He is now with Incheon National University, Incheon, Korea. In 2020, Prof. Ahn received the Second Prize Paper Award from IEEE Transactions on Power Electronics.

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Journal

IEEE Transactions on Industrial Electronics

DOI

10.1109/TIE.2024.3390737 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Resonant Tuning Rectifier for Parallel Compensated Receivers in Wireless Power Transfer

Enhancing shareholder accountability: Lessons from Japan’s corporate governance reforms

Study finds increased shareholder dissent in director elections after Japan’s Stewardship Code amendment on voluntary vote disclosure

Waseda University

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The study found that the voluntary disclosure of institutional investor’s voting records led to increased shareholder dissent in director elections, particularly among domestic investors, demonstrating how transparency regulations can strengthen corporate governance.

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Credit: Professor Toru Yoshikawa from Waseda University, Japan

Shareholders play a crucial role in corporate governance by voting on key decisions in the companies they invest in. To enhance transparency, regulatory bodies worldwide—such as government agencies and stock exchanges—are increasingly implementing guidelines to hold institutional investors accountable for their voting behavior and ensure they fulfill their fiduciary duties.

A study published in the journal Corporate Governance: An International Review on 22 January 2025 demonstrates that these regulations, even if non-binding, can encourage institutional investors to play a more active role and improve corporate governance. The study, conducted by Professor Toru Yoshikawa from Waseda University and Associate Professor Daisuke Uchida from Keio University, examined how institutional investors responded to the 2017 amendment to Japan’s Stewardship Code, which encouraged them to disclose their voting records.

“The regulatory change in the disclosure of voting records in 2017 encourages institutional investors to engage in corporate governance of their invested firms,” says Yoshikawa. “We were interested in how institutional investors, who are major corporate governance actors, reacted to this change, especially in the differences between domestic investors that were often perceived as passive in their corporate governance role and foreign investors that tend to be more active.”

To examine the impact of the regulatory change on shareholder voting, the researchers analyzed 7,887 voting proposals, covering 5,051 directors from 495 TOPIX 500 firms and the top 500 companies on the Tokyo Stock Exchange. Director candidates are recommended by the company’s board, and historically, domestic Japanese institutional investors often supported these nominees to maintain good relationships with the companies they invested in. However, after the disclosure rule took effect, the study found a significant increase in shareholder dissent in director elections.

This shift was especially noticeable in companies with high domestic institutional ownership, while companies with more foreign institutional investors saw little to no change in voting patterns. Moreover, shareholder dissent against board-recommended directors was strongest when directors were seen as underperforming or unqualified. “Prior studies show that foreign investors have different objectives from domestic investors, and they tend to pay greater attention to the corporate governance of their invested firms. However, our study shows that domestic investors more strongly reacted to the regulatory change on disclosure of voting records than foreign investors; domestic investors started to cast more dissenting votes on director candidates at general shareholders’ meetings,” says Yoshikawa.

The researchers explain that domestic institutional investors—such as local banks, trust banks, and insurance companies—are more likely to respond to local regulations because they rely on local regulatory bodies for legitimacy, whereas foreign institutional investors, who often adhere to international standards, are less influenced by domestic regulations. “Our theory and findings show that domestic institutional investors tend to diverge from foreign institutional investors in response to regulatory signals due to their different levels of dependence on the legitimacy conferred by regulatory bodies, even though they all fall under the same label of institutional investors. This suggests that shareholder preferences are not only heterogeneous but also mutable over time,” says Yoshikawa.

The increased accountability in shareholder voting following Japan’s disclosure rule demonstrates that regulatory reforms can improve corporate governance. The findings can serve as a blueprint for implementing regulatory measures in other countries in Asia that are transitioning to Western-style corporate governance systems.

 

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Reference
Authors: Daisuke Uchida1 and Toru Yoshikawa2
DOI: 10.1111/corg.12640
Affiliations: (1) Faculty of Business and Commerce, Keio University, Tokyo
                      (2) School of Social Sciences, Waseda University, Tokyo

 

About Waseda University
Located in the heart of Tokyo, Waseda University is a leading private research university that has long been dedicated to academic excellence, innovative research, and civic engagement at both the local and global levels since 1882. The University has produced many changemakers in its history, including nine prime ministers and many leaders in business, science and technology, literature, sports, and film. Waseda has strong collaborations with overseas research institutions and is committed to advancing cutting-edge research and developing leaders who can contribute to the resolution of complex global social issues. The University has set a target of achieving a zero-carbon campus by 2032, which is in line with the Sustainable Development Goals (SDGs) adopted by the United Nations in 2015. 
To learn more about Waseda University, visit https://www.waseda.jp/top/en  

 

About Professor Toru Yoshikawa from Waseda University
Dr. Toru Yoshikawa began working at Waseda University’s Faculty of Social Sciences in 2023. He specializes in business administration, strategic management, corporate governance, top management teams, innovation, and international business. He obtained his PhD from York University and has previously taught at Nihon University, McMaster University, and Singapore Management University. Prior to that, he spent a number of years working in the finance industry. Dr. Yoshikawa is a member of the Academy of Management, the Academy of International Business, the Strategic Management Society, and the International Corporate Governance Society.

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DOI

10.1111/corg.12640 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

The Differential Effect of Regulatory Signals on Shareholder Dissent: The Case of Shareholder Voting in Director Elections

 

Socially dominant individuals are more confident but not necessarily more competent

People who strive for dominance, whether in personal or professional life, are more confident in their decision-making but are no more accurate in their choices than those of a low social status

University of Kent

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Research from the University of Kent’s School of Psychology has found that people who strive for dominance, whether in personal or professional life, are more confident in their decision-making but are no more accurate in their choices than those of a lower social status.

 

The research, published by the journal Personality and Individual Differences, challenges the idea that confidence signals competence, a perception that often propels dominant individuals into leadership roles.

 

Led by Dr Andrew Martin, the research found that social dominance was comparable between males and females and both showed an effect of greater confidence, debunking the long-held belief that dominance-driven strategies are primarily male traits. 

 

Dr Martin said: ‘While high status within social hierarchies is often associated with socially dominant individuals, our research goes to show that there is no superiority in decision performance and why acting confidently can actually be an effective social strategy, regardless of ability. Our findings uncover how socially dominant individuals may traverse society, acquire and possibly even retain positions of social power and influence.’

 

To reach their conclusions the psychologists assessed performance from participants through three studies using a two-choice statistical learning decision- making task and a self-referential memory task.

 

The research paper ‘Confidence does not equal competence: Socially dominant individuals are more confident in their decisions without being more accurate’ is published by Personality and Individual Differences. (A.Martin; A Belotelova, University of Kent) doi: 10.1016/j.paid.2024.113037.

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Journal

Personality and Individual Differences

DOI

10.1016/j.paid.2024.113037 

Method of Research

Experimental study

Subject of Research

People

Article Title

Confidence does not equal competence: Socially dominant individuals are more confident in their decisions without being more accurate

ARACHNOLOGY

New insights into the evolution of spiders, scorpions, and their relatives

The Hebrew University of Jerusalem

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A new study challenges traditional views on arachnid evolution, suggesting that the transition from water to land occurred multiple times rather than in a single event. The research also highlights the role of whole-genome duplication in shaping key traits in spiders and scorpions, such as silk production and venom synthesis. These findings offer new insights into chelicerate phylogeny and provide a foundation for future genetic and evolutionary studies.

[Hebrew University of Jerusalem]– A new review paper  by Dr. Efrat Gavish-Regev from The National Natural History Collections at The Hebrew University of Jerusalem and Professor Prashant P. Sharma from the Department of Integrative Biology and Zoological Museum at the University of Wisconsin provides an updated perspective on the evolutionary history of chelicerates- a diverse and ecologically significant group of arthropods that includes spiders, scorpions, mites, and horseshoe crabs.

Published in the Annual Review of Entomology, the review examines how advances in molecular phylogenetics, evolutionary developmental biology, and genomic research have reshaped our understanding of chelicerate evolution. Traditionally, arachnids were considered a terrestrial monophyletic group—meaning they descended from a single colonization event of land by a terrestrial ancestor. However, recent phylogenomic studies challenge this view, indicating that horseshoe crabs are nested within the arachnids rather than forming a separate, sister lineage. This suggests that arachnids may have colonized land multiple times rather than through a single evolutionary event.

“The idea that all arachnids share a single terrestrial ancestor has been widely accepted for decades, but the latest molecular evidence and a different interposition of some homologies points to a more complex scenario,” says Dr. Gavish-Regev. “Instead of a straightforward transition from water to land, our research suggests that different arachnid groups may have independently adapted to terrestrial life at different points in their evolutionary history.”

One of the key findings of the study is the role of whole-genome duplications in chelicerate evolution. These events, which resulted in the duplication of entire genomes, have been identified in spiders and scorpions and may have contributed to the diversification of these groups by enabling the evolution of new biological functions, including silk production and venom synthesis.

“Arachnoid evolution has been shaped by a number of factors, including gene duplications that likely played a role in the development of key traits,” explains Prof. Sharma. “By combining phylogenetic research with new gene-editing tools, we are now in a position to explore these evolutionary changes in greater detail than ever before.”

The study also highlights new developments in the study of chelicerate phylogeny, including the application of advanced genomic techniques to resolve long-standing questions about interrelationships within the group. While some evolutionary relationships remain unresolved, the increasing availability of high-quality genomic data is expected to provide further clarity in the coming years.

The findings have broad implications for evolutionary biology, shedding light on the mechanisms that drive biodiversity and adaptation in arthropods. Beyond fundamental research, understanding chelicerate evolution can also have practical applications in areas such as pest management, biomedicine, and bio-inspired materials.

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Journal

Annual Review of Entomology

DOI

10.1146/annurev-ento-022024-011250 

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

The Evolutionary Biology of Chelicerata

FEMICIDE NORMALIZED

1 in 5 older adults get infections after heart surgery, and women have a 60% higher risk

Investigators say postoperative infections may be greatly underestimated

Michigan Medicine - University of Michigan

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One in five older adults gets an infection up to six months after heart surgery — with women far more likely to develop one, according to studies led by Michigan Medicine.

The two studies examined thousands of cases involving Medicare beneficiaries who underwent coronary artery bypass grafting, also known as CABG or heart bypass, or aortic valve replacement.

Women had 60% greater odds of developing postoperative infections, the three most common being urinary tract, pneumonia and sepsis.

Black patients also had higher rates of overall infection (28%) compared to white patients (19.2%).

The studies are published in The Journal of Thoracic and Cardiovascular Surgery.

“Our investigations highlight persistent disparities in outcomes for patients undergoing cardiac surgery that will require multidisciplinary efforts to correct,” said J'undra N. Pegues, M.D., M.S., first author of the study on infection disparities and a T32 research fellow in the Department of Cardiac Surgery at U-M Health.

In one of the studies, which covered hospitals across the state of Michigan, 21.2% of Medicare beneficiaries developed an infection up to six months after surgery.

Pneumonia and UTIs accounted for nearly 17% of all infections, and rates of infection varied nearly 40% across hospitals.

“Tracking infections beyond the short time horizon is important, as some hospitals are better equipped than others to prevent infections, and some patients face disproportionate challenges given social determinants of health,” Pegues said. 

Several past studies have uncovered lower rates of infection after these procedures.

The higher numbers found in the two current studies, investigators say, are likely due to the longer follow-up period of six months.

“Patients who have a heart bypass or valve replacement surgery are at risk for developing other infections that may come about over a longer period of time, such as UTIs and gastrointestinal infections,” said Donald Likosky, Ph.D., senior author of both studies and Richard and Norma Sarns Research Professor of Cardiac Surgery at U-M Medical School.

Most national registries neither track these additional infections nor conduct surveillance beyond 30 days after the procedure, says Charles Schwartz, M.D., chair of the Department of Surgery at Trinity Health Oakland and co-author on both of these studies.

“This likely results in a vast underestimation of the burden of infections following cardiac surgery,” Schwartz said.

Heart bypass and aortic valve replacement account for more than half of all cardiac surgical procedures in Michigan. Nationwide, CABG accounts more than 70% of all heart surgeries.

In one of the Michigan studies, patients receiving their operation at lower performing hospitals, with higher expected rates of infection, were more likely to be discharged to extended care or rehabilitation facilities.

“The findings highlight that patients are at risk for developing infections early and late after their cardiac surgical procedure,” said co-author of both studies Francis Pagani, M.D., Ph.D., the Otto Gago M.D. Endowed Professor in Cardiac Surgery at U-M Medical School and associate director of the Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative.

“Other age-related health conditions, such as diabetes, high blood pressure and cancer, may contribute to later-occurring infections identified in this study.”

Likosky’s study team notes that collaborative learning efforts between health care systems are needed to reduce disparities in patient outcomes.

Through a statewide quality improvement intervention spanning 2012 through 2017, hospitals that adopted infection prevention strategies were able to achieve lower the risk of pneumonia relative to the rest of the country.

“Our study reinforces the importance of bringing together hospitals and community stakeholders to identify and subsequently implement potentially modifiable hospital and community practices to prevent postoperative infections” said Syed Sikandar Raza, M.D., first author and integrated thoracic surgery resident at U-M Health.

Additional authors: Chiang-Hua Chang, Ph.D., Shiwei Zhou, M.D., Robert B. Hawkins, M.D., M.Sc., Michael P. Thompson, Ph.D., Thomas M. Braun, Ph.D., Geoffrey D. Barnes, M.D., M.Sc., Eric N. Hammond, Ph.D., Francis D. Pagani, M.D., Ph.D., Noah M. Barnett, and Jeremy Wolverton, M.D., all of University of Michigan, Alphonse DeLucia III, M.D., of University of Michigan Health-West, and Raed Alnajjar, M.D., of Henry Ford Hospital.

The Agency for Healthcare Research and Quality Provided study-related funding (R01HS029026).

The NHLBI supports Dr. Pegues under Award Number T32HL166113.

The Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative (MSTCVS-QC) and the Michigan Value Collaborative (MVC) supported this project.

Support for the MSTCVS-QC and MVC is provided by Blue Cross Blue Shield of Michigan as part of its Value Partnerships program. Although BCBSM and MSTCVS-QC work collaboratively, the opinions, beliefs, and viewpoints expressed by the author do not necessarily reflect the opinions, beliefs, and viewpoints of BCBSM or any of its employees. The content of this work is solely the responsibility of the authors and does not represent the official views of the Agency for Healthcare Research and Quality and the National Institutes of Health.

Papers cited:

“Interhospital Variability in 180-day Infections Following Cardiac Surgery,” The Journal of Thoracic and Cardiovascular Surgery. DOI: 10.1016/j.jtcvs.2025.01.006

“Disparities in 180-day Infection Rates Following Coronary Artery Bypass Grafting and Aortic Valve Replacement,” The Journal of Thoracic and Cardiovascular Surgery.  DOI: 10.1016/j.jtcvs.2024.12.033

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Journal

Journal of Thoracic and Cardiovascular Surgery

DOI

10.1016/j.jtcvs.2025.01.006 

Method of Research

Observational study

Subject of Research

People

Article Title

Interhospital Variability in 180-day Infections Following Cardiac Surgery,

COI Statement

The Agency for Healthcare Research and Quality Provided study-related funding (R01HS029026). The NHLBI supports Dr. Pegues under Award Number T32HL166113. The Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative (MSTCVS-QC) and the Michigan Value Collaborative (MVC) supported this project. Support for the MSTCVS-QC and MVC is provided by Blue Cross Blue Shield of Michigan as part of its Value Partnerships program. Although BCBSM and MSTCVS-QC work collaboratively, the opinions, beliefs, and viewpoints expressed by the author do not necessarily reflect the opinions, beliefs, and viewpoints of BCBSM or any of its employees. The content of this work is solely the responsibility of the authors and does not represent the official views of the Agency for Healthcare Research and Quality and the National Institutes of Health.