Collective behaviors of second-order nonlinear consensus models with a bonding force

Hyunjin Ahn,Junhyeok Byeon,하승열,Jaeyoung Yoon 대한수학회 2024 대한수학회지 Vol.61 No.3

We study the collective behaviors of two second-order nonlinear consensus models with a bonding force, namely the Kuramoto model and the Cucker-Smale model with inter-particle bonding force. The proposed models contain feedback control terms which induce collision avoidance and emergent consensus dynamics in a suitable framework. Through the cooperative interplays between feedback controls, initial state configuration tends to an ordered configuration asymptotically under suitable frameworks which are formulated in terms of system parameters and initial configurations. For a two-particle system on the real line, we show that the relative state tends to the preassigned value asymptotically, and we also provide several numerical examples to analyze the possible nonlinear dynamics of the proposed models, and compare them with analytical results.

A Hardware-Efficient Pattern Matching Architecture Using Process Element Tree for Deep Packet Inspection

AHN, Seongyong,HONG, Hyejeong,KIM, HyunJin,AHN, Jin-Ho,BAEK, Dongmyong,KANG, Sungho The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.9

<P>This paper proposes a new pattern matching architecture with multi-character processing for deep packet inspection. The proposed pattern matching architecture detects the start point of pattern matching from multi-character input using input text alignment. By eliminating duplicate hardware components using process element tree, hardware cost is greatly reduced in the proposed pattern matching architecture.</P>

Optimal MIFARE Classic Attack Flow on Actual Environment

Hyunjin Ahn(안현진),Yerim Lee(이예림),Su-Jin Lee(이수진),Dong-Guk Han(한동국) 대한전기학회 2016 전기학회논문지 Vol.65 No.12

MIFARE Classic is the most popular contactless smart card, which is primarily used in the management of access control and public transport payment systems. It has several security features such as the proprietary stream cipher Crypto 1, a challenge-response mutual authentication protocol, and a random number generator. Unfortunately, multiple studies have reported structural flaws in its security features. Furthermore, various attack methods that target genuine MIFARE Classic cards or readers have been proposed to crack the card. From a practical perspective, these attacks can be partitioned according to the attacker’s ability. However, this measure is insufficient to determine the optimal attack flow due to the refined random number generator. Most card-only attack methods assume a predicted or fixed random number, whereas several commercial cards use unpredictable and unfixable random numbers. In this paper, we propose optimal MIFARE Classic attack procedures with regards to the type of random number generator, as well as an adversary’s ability. In addition, we show actual attack results from our portable experimental setup, which is comprised of a commercially developed attack device, a smartphone, and our own application retrieving secret data and sector key.

An Integrated Low-loss Lumped-element Quadrature Coupler Using a Distributed Model

Hyunjin Ahn,남일구,Dong-Ho Lee,이옥구 대한전자공학회 2020 Journal of semiconductor technology and science Vol.20 No.3

This paper presents a distributed model of a lumped-element quadrature coupler that accounts for the distributed nature of parasitic elements. The required capacitors in the constitution of lumped-element quadrature couplers can be properly considered using the proposed distributed model. An integrated low loss lumped-element quadrature coupler is implemented using the proposed model. The modeled responses are compared with the corresponding measured responses; they exhibit good agreement. The measured insertion loss for both direct and coupled ports is 3.23 dB at 5.5 GHz. The variation in the insertion loss is ± 0.3 dB with a phase imbalance of less than 0.95° across a 760-MHz bandwidth.

A Fully Integrated Dual-Mode CMOS Power Amplifier With an Autotransformer-Based Parallel Combining Transformer

Ahn, Hyunjin,Baek, Seungjun,Nam, Ilku,An, Deokgi,Lee, Jae Kyung,Jeong, Minsu,Kim, Bo-Eun,Choi, Jaehyouk,Lee, Ockgoo THE INSTITUTE OF ELECTRICAL ENGINEERS 2017 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.27 No.9

<P>This letter presents a fully integrated dual-mode power amplifier (PA) with an autotransformer-based parallel combining transformer (ABPCT), fabricated with a standard 40-nm CMOS process. In comparison with a parallel combining transformer, the proposed ABPCT can offer high-efficiency performance in both high-power (HP) and low-power (LP) modes, and does so with a compact die area. With an 802.11g signal (64-QAM 54 Mbps) of 20-MHz channel bandwidth, the fully integrated dual-mode PA achieves 19.7 and 15.7 dBm average output powers with PAEs of 17.1% and 13%, in HP and LP modes, respectively, while satisfying a -25 dB error vector magnitude and spectral mask requirements. Operating the PA in the LP mode can save more than 40% of the current consumption at a 10-dBm average output power when compared with that in the HP mode.</P>

2.3-GHz HBT Power Amplifier With Parallel-Segmented On-Chip Autotransformer

Ahn, Hyunjin,Choi, Se-Eun,Ryu, Hyunsik,Baek, Seungjun,Nam, Ilku,Lee, Ockgoo THE INSTITUTE OF ELECTRICAL ENGINEERS 2017 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.27 No.12

<P>A parallel-segmented primary autotransformer is proposed to optimize passive efficiency as well as impedance transformation ratio. In addition, a corresponding equivalent lumped model has been proposed and shows a good agreement with electromagnetic -simulated and measured data. This paper also presents a fully integrated HBT power amplifier with a parallel-segmented primary autotransformer to obtain watt-level output power with low loss. The saturated output power of the power amplifier (PA) is 31 dBm at 2.3 GHz. The PA achieves output power of 24.84 dBm with adjacent channel leakage ratio of less than -40.4 dBc for LTE signal with a 10-MHz bandwidth and 7.3-dB PAPR.</P>

Octopus Launcher: 중증 지체장애인을 위한 전동 휠체어 조이스틱 기반 스마트폰 컨트롤 솔루션

안현진(Hyunjin Ahn),이승현(Seunghyun Lee),정글지(Gulji Chung),강호민(Homin Kang),박철준(Cheoljun Park),조영록(Youngrok Cho) 한국HCI학회 2014 한국HCI학회 학술대회 Vol.2014 No.2

손이 불편한 중증 지체 장애인의 경우 터치 스크린 인터페이스를 사용하는데 한계가 있는데 반해, 이에 대한 뚜렷한 대책이 없는 실정이다. 본 연구에서는 중증 지체 장애인에 대한 사용자 조사를 실시하고 이를 통해 도출한 Design implication 을 통해 전동 휠체어 조이스틱을 이용한 스마트폰 컨트롤 솔루션인 Octopus Launcher 를 제안한다. Octopus Launcher 는 전동휠체어와 스마트폰을 연동하기 위한 에볼루션 박스와 Android OS 기반 Launcher 형 어플리케이션으로 구성되어 있으며 조이스틱 조작 방식에 최적화된 UI 를 제공한다. 본 연구를 통해 손이 불편한 중증 지체 장애인들의 정보 격차를 해소하고 이를 통해 장애인의 사회참여를 보다 용이하게 할 것이다. The Motor impairments who have problem with using their hands are unable to use touch screen interface well but, there"s no proper actions for them. In this study, we implement the user ability test and found out the design implication. By this, we suggest the smart phone control solution which control by the joystick on an electric wheelchair, "Octopus Launcher". The "Octopus Launcher" is made up with evolution box which helps interwork with smartphone and wheel chair, and the Launcher application based on Android OS and it provide the user interface which is optimize with the way of controlling the joystick. By this study, it will reduce the digital divide to the motor impairments who are unable to use their hands well. And also, it will help disable people to participate in the society.

병렬 분할된 CMOS 점증 단권변압기와 모델링

안현진(Hyunjin Ahn),손병찬(Byung Chan Son),류현식(Hyunsik Ryu),이옥구(Ockgoo Lee) 한국전자파학회 2020 한국전자파학회논문지 Vol.31 No.11

본 논문에서는 임피던스 변환율을 개선하기 위한 병렬 분할된 CMOS 점증 단권변압기를 제안한다. 또한, 이에 상응하는 확장성이 있는 CMOS 공정을 사용한 병렬 분할 기법을 사용한 모델링이 개발되었다. 제안된 병렬 분할 기법의 모델링을 사용하여 병렬 분할된 단권변압기의 정확한 성능 예측이 가능하다. 병렬 분할된 점증 단권변압기는 표준 CMOS 65 ㎚ 공정을 사용하여 제작되었다. 모델링된 결과는 측정된 결과와 우수한 일치를 보여준다. 제작된 1개/2개 병렬 분할된 CMOS 점증 단권변압기는 3 ㎓ 주파수에서 −1.21 ㏈/−1.54 ㏈의 최소삽입손실의 특성을 보이며, 50 Ω 임피던스가 9.5 Ω/6.1 Ω의 임피던스로 변환되어 보인다. In this study, a parallel-segmented complementary metal-oxide–semiconductor (CMOS) step-up autotransformer was developed to improve the impedance transformation ratio. In addition, a corresponding scalable segmentation-based model was developed on a CMOS case. The proposed segmentation-based model was used to predict the accurate performance of a parallel-segmented autotransformer. The parallel-segmented step-up autotransformer was fabricated through a standard 65 ㎚ CMOS process. The modeled results showed good agreement with the measured results. The implemented one/two parallel-segmented CMOS step-up autotransformer changed the impedance from 50 Ω to 9.5 Ω/6.1 Ω with −1.21 ㏈/−1.54 ㏈ minimum insertion loss at 3 ㎓.

DOWELL: 상지운동장애인을 위한 Dwell 기반 스마트폰 조작 솔루션

안현진(Hyunjin Ahn),윤재석(Jaeseok Yoon),김기범(Kibum Kim),정글지(Gulji Chung),최현빈(Hyunbin Choi),마지연(Jiyeon Ma) 한국HCI학회 2014 한국HCI학회 학술대회 Vol.2014 No.12

몸의 움직임이 불편한 장애인들은 자신들의 장애유형에 맞는 특수한 보조기구를 통해 컴퓨터를 사용해왔다. 그들 중에서도 손/팔의 움직임이 불편한 상지장애인은 버튼의 누르는 동작자체가 어렵기 때문에 보조기구와 함께 Dwell-time 방식 등의 버튼 대체 소프트웨어를 사용했다. 하지만 아직까지 스마트폰에 맞는 버튼 대체 소프트웨어가 없어 상지장애인이 스마트폰을 사용할 방법이 없는 실정이다. 본 연구에서는 상지운동장애인을 위한 Dwell 기반 스마트폰 조작 솔루션인 DOWELL 을 소개한다. 기존에 사용하던 컴퓨터용 보조기구를 스마트폰에 연결하고 DOWELL 을 실행하면 버튼 없이 일정시간 멈추는 동작으로 스마트폰을 사용할 수 있다. DOWELL 은 동작 정확도가 떨어지는 장애인을 위해 네 방향 모서리를 이용하여 인터페이스를 설계하였다. 또한 스마트폰의 작은 화면 특성을 감안하여 펼침 메뉴를 사용하였고 다양한 입력 제스쳐를 제공하여 제약 없이 일반인처럼 스마트폰의 모든 기능을 사용할 수 있게 하였다. DOWELL 을 통해 상지운동 장애인들도 스마트폰을 사용할 수 있으며 이는 장애인의 자립심 증대 및 정보격차 해소에 도움이 될 것이다. The disabled who cannot as easily move their bodies have used the computer with assistance devices specially developed for their type of disability. Among the disabled, people with upper limb disorders, who have difficulties moving their hands and arms, have used button substitution software such as Dwelltime with assistance devices since they cannot press the button. However, these people cannot as of yet use smartphones because there is no button substitution software for smartphones. In this research, I would like to introduce DOWELL, a smartphone control solution based on Dwell for people with upper limb disorders. If a person with upper limb disorders connect the assistance device that already use to the smartphone a nd activate D OWELL, heors he will be able to use the smartphone without buttons by just stopping movements for a predetermined time. DOWELL has built its interface using fourdirection corners for the disabled who lack movement accuracy. Also, considering the small-sized screen of smartphones, we have used pop-up menus and provided various input gestures so that the disabled can use all functions that people without disabilities can use. With DOWELL, people with upper-limb movement disorder will be able to use smartphones, which will contribute to an increase in the disabled people’s sense of independence and a reduction of information gap.

신발 부착형 NFC Tag를 이용한 콘텐츠 제공 서비스 컨셉 제안

안현진(Hyunjin Ahn),정혜윤(Hyeyoon Jeong),박천현(Cheonhyun Park) 한국HCI학회 2014 한국HCI학회 학술대회 Vol.2014 No.2