[편집자주] IT제품 설계 시 발생하는 전자파 노이즈는 제품 성능 저하와 오작동 등 치명적인 결함을 유발한다. 최근 자동차의 전동화와 각종 IT 디바이스의 소형화, 5G·6G 통신으로의 패러다임 전환 등으로 전자파 환경에서의 노이즈가 증가하고 있으며, 각종 기기와 시스템의 오작동으로 이어지고 있다. 이에 기획연재 시리즈인 ‘EMI/EMC 명사(名士) 대담’을 통해 안전하고 신뢰성 높은 첨단 IT 제품 개발을 위해 EMI·EMC 대책의 중요성을 조명하고, 각계각층에서 활동하는 EMI/EMC 전문가들을 만나 최신의 이야기를 듣는 자리를 마련했다.
“Changing and evolving electromagnetic environment, EMI/EMC considerations in early design stages are important”
Electrification increases power circuit noise and high-reliability design issues
Interconnect design considering SIPI and EMC is essential in semiconductor packaging
'Contactless High-Speed Interconnect' Research Completes LVDS Transmission Stage
“I want to focus on nurturing EMI/EMC experts”... Emphasizes talent development
[Editor's Note] Electromagnetic noise generated during the design of IT products causes fatal defects such as product performance degradation and malfunction. Recently, noise in the electromagnetic environment is increasing due to the electrification of automobiles, miniaturization of various IT devices, and paradigm shift to 5G and 6G communications, leading to malfunctions in various devices and systems. Accordingly, through the planned serial publication series 'EMI/EMC Expert Talk', we have highlighted the importance of EMI/EMC countermeasures for the development of safe and reliable cutting-edge IT products, and have created an opportunity to meet EMI/EMC experts from all walks of life and hear their latest stories.
We met with Professor Ji-Sung Kim of the KAIST Green Transportation System Research Center, the first interviewee for the EMI/EMC expert dialogue.

▲Professor Kim Ji-seong
[Reporter] Please introduce yourself briefly.
[Professor Kim Ji-seong] He received his Ph.D. from Texas State University and worked at Samsung Electronics on high-speed digital system design. After that, he worked as a professor at Suwon Science College and is currently a visiting professor at the KAIST Green Transportation System Research Center.
We mainly research electromagnetic waves (EMI/EMC) of high-speed digital systems and power systems. These technologies are important for reducing noise generated during electronic product design and minimizing electromagnetic waves harmful to the human body, thereby ensuring high-reliability design.
We are also researching interconnect design for high-speed signal transmission, and this technology is required in all fields that involve electronic circuits, including semiconductors, IT, home appliances, automobiles, military, and aviation.
[Reporter] I'm curious about your recent activities. What activities are you doing?
[Professor Kim Ji-seong] Recently, I have been focusing on academic activities and industry-university cooperation.
As a specialist in my field of study, I am active as a researcher in the EMC Research Group of the Korean Institute of Electromagnetic Engineering and Science, as well as in the High-Speed Interconnect and Packaging Research Group. I give many lectures and provide advice to employees of large domestic companies and small and medium-sized enterprises on related technologies.
The EMI/EMC field is an essential technology for product development from small and medium-sized businesses to large corporations. However, small and medium-sized businesses in particular are having difficulty internalizing the technology and require a lot of help from external experts. Therefore, I am constantly learning and researching new technologies, but I am also trying to contribute more to the industrial field based on my experience and knowledge so far.

▲Professor Ji-Seong Kim receiving a plaque of merit at EMC KOREA 2023, hosted by the EMC Technology Research Group of the Korean Institute of Electromagnetic Engineering and Science last year.
[Reporter] What are some of the hot topics related to EMI/EMC? If there are any latest countermeasure technologies that you are interested in, please introduce them.
[Professor Kim Ji-seong] A recent hot topic is the electrification of automobiles, which is resulting in an increase in electromagnetic waves, especially in power circuits, and increasing issues in high-reliability design.
In particular, noise generated from motors/inverters is occurring relatively more, and most of the components are electronic, so signal integrity (SI), power integrity (PI), and EMI/EMC design are becoming more important.
Another issue is the semiconductor industry. Semiconductor IC design is important, but recently, chiplet technology, which connects individual chips implemented by function such as CPU, GPU, power, I/O, and memory, through packaging, is being actively researched and developed in academia and industry.
In these 2.5D/3D advanced packaging technologies, not only fine processes and materials are important, but also the connection structure and interconnect design are important parts. The convergence of various research fields such as materials, machinery, and semiconductor engineering is an essential technology, and SI, PI, and EMI/EMC technologies are also very important. This is because the optimal design of interconnects is important in order to connect individual chips with various functions and transmit high-speed signals.
[Reporter] Recently, there seems to be a noticeable trend toward reducing system size while increasing switching frequency for greater efficiency. What are the EMC considerations in this case?
[Professor Kim Ji-seong] When developing a switching power system (SMPS), it is difficult to consider efficiency, same performance, and electromagnetic waves.
In order to increase efficiency, which is the most important performance indicator, switching can increase electromagnetic noise, and additional components are needed to reduce noise, which increases the price. However, electromagnetic response design is essential for launching a product, so it should be considered along with various performance indicators from the design stage.
Looking at technology trends, in the mobile field, switching frequencies are increasing to miniaturize power circuits, and on-chip DC-DC converters are being developed. As the frequency increases, components can become smaller and smaller, but in terms of electromagnetic waves, problems such as interference with communication frequencies can become greater as the frequency increases, so designs that take EMI into account must be made at the design stage.
The main noise in power circuits comes from switching elements such as MOSFETs, but recently, wide-bandgap elements such as SiC and GaN devices are being widely used. Since changes in the characteristics of these devices along with changes in frequency also affect the generated noise, much research is being conducted in the EMC field.
[Reporter] I heard that electric vehicles are showing a trend toward integrating systems for efficiency, such as integrating OBCs and converters, and that noise is also becoming a significant problem.
[Professor Kim Ji-seong] In the case of high-voltage, high-power systems such as automobiles, the generated noise is relatively large, making countermeasures difficult. In particular, when switching circuits of various frequencies are designed together, and when low-voltage, high-voltage, sensor, and communication circuits are packaged together in a single housing, electromagnetic noise can easily couple between circuits within the housing, making it difficult to not only countermeasures for conducted and radiated noise, but also design high reliability.
Because these issues are difficult to address after development, it is important to consider them from the early design stages.
[Reporter] The most recent academic research you published was 'Digital Communication Using Contactless Interconnects'. What is it about?
[Professor Kim Ji-seong] We have been promoting the 'Development of Advanced Power and Signal EMC Technology for Hyper-connected E-Vehicles' project supported by the Ministry of Science and ICT for the past four years. Through this project, we are conducting research on electromagnetic technology required for future electric vehicles, and one of the researches I am conducting is on contactless high-speed interconnect.
It is a technology that transmits signals through a short-range non-contact interconnect without transmitting signals through a connector, and is different from wireless communication that uses antennas in that it transmits signals using near-field capacitive coupling.
Recently, commercial ICs that transmit high-speed digital signals of 10Gbps using 60GHz millimeter waves and antennas have been released, and a related market has also been formed. This technology transmits high-speed digital signals without directly connecting through connectors, and requires RF components and antennas. The research I am doing uses capacitive coupling between nearby conductors, so it can be implemented at low cost and can be used in fields such as automobiles.
[Reporter] How is additional research and development progressing since the announcement?
[Professor Kim Ji-seong] We have already implemented CAN/LIN communication used in automobiles, and recently we have developed LVDS communication, which is the interface for camera modules, to enable transmission. In the future, we plan to research technology that can transmit data at speeds up to several Gbps using the automobile body.
[Reporter] It seems that the era of wireless communication and hyper-connected society is deepening as advanced non-contact interconnection technologies, as well as wireless power transmission, short-range wireless communication technologies, and IoT, are being developed and applied throughout society. In this flood of radio technology, what do you think are the EMI/EMC points that need to be addressed and prepared for?
[Professor Kim Ji-seong] As mentioned briefly earlier, many wireless communication technologies are emerging and frequencies are also continuously increasing. Accordingly, regulations are continuously being added and revised to prevent electromagnetic noise from interfering with the corresponding frequencies.
For example, the transmission speed of digital communication is increasing. In the case of USB, the speed of 10Gbps is currently used, but it is expected to increase to an even faster speed. The frequency generated by these digital signals easily causes interference with Wi-Fi, GPS, etc.
The switching noise of the power circuit mentioned above can easily affect the communication frequency of the AM/FM band. Accordingly, the EMI/EMC field is continuously researching related countermeasures to respond to new technologies, including changes in wireless communication technology.
[Reporter] What are your plans and goals for the future?
[Professor Kim Ji-seong] I am personally continuing my research in related fields, but in the future, I would like to focus on nurturing experts in the EMI/EMC field. It is a field-oriented technology that is absolutely necessary in industrial settings, but there is a lack of related education programs, and it is a field that requires a lot of experience along with theory, so nurturing experts is not easy.
In this field, our country has already secured technology that is not behind that of advanced countries. In order to secure technological competitiveness at the national level, many experts in this field are needed. Based on my knowledge and experience to date, I would like to contribute to the training of experts in this field through education and technical advice.
[Reporter] This is already the last question. What is your outlook for the future of the EMI/EMC field?
[Professor Kim Ji-seong] Technological changes are becoming increasingly rapid, and recently, new technologies such as AI have had a significant impact on society. EMI/EMC technology has not received much attention amidst these technological changes, but EMI/EMC is a technology that is absolutely necessary for any technology or product. In this regard, I believe that the demand for EMI/EMC technology will remain steady from the past to the present and into the future.
thank you