Policy-based Reinforcement Learning (RL) for Through Silicon Via (TSV) Array Design in High Bandwidth Memory (HBM) considering Signal Integrity (SI) (Prof. Kim, Joungho’s lab)

Abstract

In this article, a policy-based reinforcement learning (RL) method for optimizing through silicon via (TSV) array design in high-bandwidth memory (HBM) considering signal integrity is proposed. The proposed method can provide an optimal TSV-array signal/ground pattern design to maximize the eye opening (EO), which determines the bandwidth of the high-speed TSV channel. The proposed method adopts the proximal policy optimization algorithm, which directly trains the optimal policy, providing efficient handling of large action spaces rather than value-based RL. The convolutional neural network is used as a feature extractor to extract the location information of the TSV-array. To overcome the computational cost of the reward estimation, a fast EO estimation method is developed based on the equivalent circuit modeling and peak distortion analysis. The proposed method is applied to optimize 1-byte of TSV-array in a 16-high HBM and showed an 18.2% increase in EO compared with the initial design. The optimality performance of the proposed method is compared with deep q-network and random search algorithm, and the proposed method shows 3.4% and 9.6% better optimality, respectively.

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Generative Adversarial Learning Based Power Noise Induced Eye Diagram Estimation Method for High-Speed Channel Design(Prof. Joungho Kim’s Lab.)

Abstract

In this article, we present a novel power noise induced eye diagram estimation method for high-speed channel design with generative adversarial learning. By leveraging a tailored adaptive Gramian-Angular-Field segmentation integration (AGSI) framework with generative adversarial networks (GANs), the proposed
AGSI–GAN accurately and efficiently estimates eye diagrams under challenging design scenarios involving signal integrity (SI) and power integrity (PI) interactions, such as crosstalk and switching noise. Our approach, AGSI–GAN, enhances the U-Net generator’s learning efficiency by utilizing AGSI as condition images that encapsulate domain characteristics related to SI/PI. By integrating single-bit response, far-end crosstalk and simultaneous switching
noise as modular components, AGSI converts this integrated data into images to enable both the generator and the discriminator interpret condition images with metafeatures. The trained AGSI–GAN reduces runtime by 88.6% compared to full-transient simulation, while maintaining high accuracy with all eye diagram metrics, including cumulative areas, showing average mean absolute percentage errors below 3% . Furthermore, AGSI–GAN facilitates
accelerated design optimization while enabling the estimation of complete eye diagrams for the defined objective function, effectively addressing complex SI/PI tradeoffs. The framework shows significant potential for expediting the optimization process, integrating.

 

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Data-efficient prediction of OLED optical properties enabled by transfer learning(Prof. Min Seok Jang’s Lab.)

Abstract

It has long been desired to enable global structural optimization of organic light-emitting diodes (OLEDs) for maximal light extraction. The most critical obstacles to achieving this goal are time-consuming optical simulations and discrepancies between simulation and experiment. In this work, by leveraging transfer learning, we demonstrate that fast and reliable prediction of OLED optical properties is possible with several times higher data efficiency compared to previously demonstrated surrogate solvers based on artificial neural networks. Once a neural network is trained for a base OLED structure, it can be transferred to predict the properties of modified structures with additional layers with a relatively small number of additional training samples. Moreover, we demonstrate that, with only a few tenths of experimental data sets, a neural network can be trained to accurately predict experimental measurements of OLEDs, which often differ from simulation results due to fabrication and measurement errors. This is enabled by transferring a pre-trained network, built with a large amount of simulated data, to a new network capable of correcting systematic errors in experiment. Our work proposes a practical approach to designing and optimizing OLED structures with a large number of design parameters to achieve high optical efficiency.

 

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Inverse design of nanophotonic devices enabled by optimization algorithms and deep learning: recent achievements and future prospects(Prof. Hamza Kurt’s Lab.))

Abstract

Nanophotonics, which explores significant light-matter interactions at the nanoscale, has facilitated significant advancements across numerous research fields. A key objective in this area is the design of ultra-compact, high-performance nanophotonic devices to pave the way for next-generation photonics. While conventional brute-force, intuition-based forward design methods have produced successful nanophotonic solutions over the past several decades, recent developments in optimization methods and artificial intelligence offer new potential to expand these capabilities. In this review, we delve into the latest progress in the inverse design of nanophotonic devices, where AI and optimization methods are leveraged to automate and enhance the design process. We discuss representative methods commonly employed in nanophotonic design, including various meta-heuristic algorithms such as trajectory-based, evolutionary, and swarm-based approaches, in addition to adjoint-based optimization. Furthermore, we explore state-of-the-art deep learning techniques, involving discriminative models, generative models, and reinforcement learning. We also introduce and categorize several notable inverse-designed nanophotonic devices and their respective design methodologies. Additionally, we summarize the open-source inverse design tools and commercial foundries. Finally, we provide our perspectives on the current challenges of inverse design, while offering insights into future directions that could further advance this rapidly evolving field.

 

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EE Prof. Minsoo Rhu and Prof. Min Seok Jang, “Young Leaders to Lead the Development of Science and Technology” National Academy of Science and Technology, elected members of ‘2023 Y-KAIST’.

Professor Minsoo Rhu and Professor Minseok Jang of the electrical engineering department have been elected as members of the ‘2023 Y-KAST’ of the Korean Academy of Science and Technology (hereinafter ‘Hallymwon’).
 
Y-KAST members are researchers with outstanding academic achievements among young scientists under the age of 43, and Hallymwon prioritizes the achievements made as independent researchers in Korea after receiving a doctorate degree, and fosters next-generation science and technology leaders who are highly likely to contribute to the development of science and technology in Korea.
 
On December 13, 2022 at 4:00 PM, ‘2022 Y-KAST Members Day’ will be held both online and offline, and Hallymwon plans to present membership plaques to new Y-KAST members and introduce research achievements.
 
The head of Hallymwon said “Hallymwon wants to build an environment in which young scientists can fully demonstrate their skills and grow as leaders in the future science and technology field, and we will support them to present new ideas for R&D innovation.”
 
 
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[Prof. Minsoo Rhu]    [ Prof. Min Seok Jang]
 
Professor Minsu Rhu’s research achievements: Development of intelligent semiconductors and computer systems for artificial intelligence
 
Professor Min Seok Jang’s research achievements: 
Pioneering the border between science and engineering in the field of nano optics and metamaterials and solving important problems one after another in the research of two-dimensional material-based active optical devices, leading the field
 
 
Link: https://m.ajunews.com/view/20221212094151237
 
 

Dr. Hyunwook Park (Prof. Joungho Kim’s lab graduate), won Best Poster Award in IEEE EPEPS

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[Prof. Joungho Kim, Hyunwook Park, from left]

 

-Award Name: Best Poster Award

-Paper Title: Scalable Transformer Network-based Reinforcement Learning Method for PSIJ Optimization in HBM

-Authors: Hyunwook Park, Taein Shin, Seongguk Kim, Daehwan Lho, Boogyo Sim, Jinouk Song, Kyu-Bong, and Joungho Kim (Corresponding author) 

-Conference Name: 2022 IEEE 31th Conference on Electrical Performance of Electronic Packaging and Systems

-Time of the event: 9 to 12th October, 2022 at San Jose, CA, USA

 

KAIST EE Postdoc researcher Hyunwook Park (under the supervision of Professor Joungho Kim) won the Best Poster Award at 2022 IEEE 31th Conference on Electrical Performance of Electronic Packaging and Systems (EPEPS Conference), which was held at San Jose, California, from 9 to 12th October.  

 

EPEPS Conference is an annual academic conference in which many prestigious universities and companies share their research works in the field of signal and power integrity-based semiconductor.

 

Postdoc researcher Researcher Hyunwook Park presented the paper “Scalable Transformer Network-based Reinforcement Learning Method for PSIJ Optimization in HBM”, which was nominated for the Best Poster Award thanks to its excellence.

 

EPEPS Best Poster Award 수상사진 박현욱

EE Professor Jang, Min Seok’s Research Team Build New Platforms for Highly Compressed Polaritons

KAIST EE Prof. Jang, Min Seok and his research team succeed in observing strongly confined mid-infrared light propagating on monocrystalline gold with a scattering-type scanning near-field optical microscope (s-SNOM). 

It is highly applicable in next-generation optoelectronic devices development, with increasing the interaction between light and matter by confining the light in an atomically flat nanostructure. The study will be useful in advancing high-efficient nanophotonics and quantum computing.

 

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[From left, Prof. Jang, Min Seok and Research Prof. Sergey Menabde]

 

KAIST announced on the July 18th that a joint research effort has succeeded in implementing a new platform for strongly confined light propagation in a low-dimensional material. This finding is expected to contribute to the development of next-generation optoelectronic devices development based on strong light-matter interactions.

 

Stacking atomically flat two-dimensional materials results in van der Waals crystals, which exhibit properties different from the original two-dimensional materials. Phonon-polaritons are the composite quasi-particles resulting from the polar dielectric ions’ oscillations coupling with electromagnetic waves. In particular, phonon-polaritons forming in van der Waals crystals placed on highly conductive metals have a high degree of compression. This is because the charges in the polariton crystals reflect in the underneath metal due to the image charge effect, and thus produce a new kind of polariton called image phonon-polaritons.

 

Light propagating as image phonon-polaritons may induce strong light-matter interactions, but their propagation is limited on rough metal surfaces and thus suffers low feasibility.

 

Prof. Jang said, “This work illustrates very well the advantages of image polaritons, especially image phonon-polaritons. Image phonon-polaritons exhibit low loss and strong light-matter interactions useful in the development of next-generation optoelectronic devices.” He then added that he hopes to advance the commercialization of high-efficiency nanophotonic devices, including in metasurfaces, optical switches, and optical sensors.

 

This work, first-authored by Research Prof. Sergey Menabde, was published in Science Advances on the July 13th. It has been supported by Samsung Science & Technology Foundation and the National Research Foundation of Korea, as well as Korea Institute of Science and Technology, Japanese Ministry of Education, Culture, Sports, Science and Technology, and the Villum Foundation of Denmark.

 

 

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Fig. 1 Nanotip used in measuring the image phonon-polaritons traveling in h-BN in super-high resolution

Professor Joung-Ho Kim has written a book ‘The Future of Engineering,’ which deals with the vision after the post-corona era

‘The Future of Engineering’ has been published, which is written by Professor Joung-Ho Kim of our faculty.

This is a new book that contains that this is the best time to move forward to become a ‘First Mover’ in the era of the 4th industrial revolution in Korea, even in the chaotic situation of the post-corona era.

The professor described a discourse on the role of Korean engineering to achieve true digital technology independence.

Against the rapidly changing environment, he expressed his position that we should take the lead in overcoming the crisis caused by COVID-19 by focusing on ‘digital engineering.’

In particular, the book explained the basic principles of artificial intelligence, big data, computers, and semiconductors that are rapidly developing in the 4th industrial revolution. The book suggests the directions of future innovative development and golden opportunities. It also explained the principle of mathematics, which is the basis of digital engineering, in a refreshingly readable manner.

In addition, this book presents the future of the 4th industrial revolution that will unfold after COVID-19, the development strategy of Korea, also including the concept of talents who will lead the future.

Professor Joonwoo Bae and June-Koo Rhee Joins IBM Q-Network for Acceleration of Domestic Quantum Computing Research

Our university’s AI quantum computing IT research centers has announced last September 29th that it will be joining the IBM Q-network for developing quantum computing used in business and science. The IBM Q-network is a multi corporation, start-up, and research institute collaboration working with IBM.

As the first domestic academic member of the IBM Q-network, our university will use the highly advanced IBM’s quantum computing system to conduct research products for the development of quantum information science and early stage application usage. The vast IBM quantum resources will be also used for training professional quantum information related experts for the upcoming quantum computing era. Our university will take the lead for developing the quantum computing infrastructure, which is one the key technologies for the 4th industrial revolution.

Professor June-Koo Rhee, the head of the AI quantum computing IT research center, explains the quantum computing is a new technology that can solve difficult mathematic problems in a short time with low power and can reshape the future. He also mentioned that although our country is behind in quantum computing technologies, KAIST’s IBM Q-network will become an important resource for developing national competitiveness.

Our university’s A quantum computing IT research center have been using the IBM cloud open source IBM quantum experience for quantum AI, quantum chemistry calculation, quantum algorithm research and quantum computing education. Our university will be able to use IBM’s high end quantum computer for quantum AI based disease diagnosis, quantum chemical computer science, quantum machine learning, and other quantum related research and experiments. Also we will be able to communicate with other universities and corporations participating in the IBM Q-network.

 

About IBM Quantum

The IBM Quantum is an initiative for founding quantum systems for business and science applications. More can be found on http://www.ibm.com/ibmq. More information about the IBM Q-network with all partners, members, and hubs are listed in https://www.research.ibm.com/ibm-q/network/.

Professor June-Koo Rhee’s research team developed a quantum AI algorithm that goes beyond existing AI technology

Professor June-Koo Rhee’s research team developed a non-linear quantum machine-learning artificial intelligence algorithm through collaborative research with German and South African research teams.
Through this study, a non-linear kernel was devised to enable quantum machine learning of complex data. In particular, the quantum supervised learning algorithm developed by Professor June-Koo Rhee’s research team can be calculated with a minimal amount of computation. Therefore, the algorithm presents the possibility of overtaking current AI technologies that require large amounts of computation.
Professor June-Koo Rhee’s research team developed quantum forking technology that generates train and test data through quantum information and enables parallel computation of quantum information. A simple quantum measurement technique has been combined to create a quantum algorithm system that implements non-linear kernel-based supervised learning that efficiently calculates similarities between quantum data. The research team successfully demonstrated quantum supervised learning on real quantum computers through IBM cloud services. Research professor Kyung-Deock Park (KAIST) participated as the first author. The result of this study was published in the 6th volume of May 2020, ‘npj Quantum Information’, a sister journal of the international journal Nature. (Title: Quantum classifier with tailored quantum kernel).

Furthermore, the research team theoretically proved that it is possible to implement various quantum kernels through the systematic design of quantum circuits. In kernel-based machine learning, the optimal kernel may vary depending on the given input data. Therefore, being able to implement various quantum kernels efficiently is a significant achievement in the practical application of quantum kernel-based machine learning.

Research professor Kyung-Deock Park said, “The kernel-based quantum machine learning algorithm developed by the research team will surpass traditional kernel-based supervised learning in the era of hundreds of qubits of Noisy Intermediate-Scale Quantum (NISQ) computing, which is expected to be commercialized in the next few years. The developed algorithm will be actively used as a quantum machine learning algorithm for pattern recognition of complex non-linear data.”

Meanwhile, this research was carried out with the support of the Korea Research Foundation’s Creative Challenge Research Foundation Support Project, the Korea Research Foundation’s Korea-Africa Cooperation Foundation Project, and the Information and Communication Technology Expert Training Project (ITRC) supported by the Institute for Information and Communications Technology Promotion.
You can find information on related articles in the link below.

Congratulations again on Professor June-Koo Rhee’s research team for their outstanding performance in the field of quantum computing.