TESTING OF MEMORIES WITH TOLERABLE DEFECTS

Younggap You 대한전자공학회 1991 ICEIC:International Conference on Electronics, Inf Vol.1991 No.8

Energy-Efficient Transmit Power Control for Multi-tier MIMO HetNets

Younggap Kwon,Taewon Hwang,Xudong Wang IEEE 2015 IEEE journal on selected areas in communications Vol.33 No.10

<P>In this paper, we study energy-efficient transmit power control for multi-tier multi-antenna (MIMO) heterogeneous cellular networks (HetNets), where each tier operates in closed-access policy and base stations (BSs) in each tier are distributed as a stationary Poisson point process (PPP). Each BS serves multiple users at a fixed distance away from it. We first study noncooperative energy-efficient power control, where each tier selfishly chooses its transmit power to maximize its network energy efficiency (EE). This is modeled by a noncooperative power control game. We prove the existence and the uniqueness of the Nash equilibrium of the game. Moreover, we analyze the effects of circuit power and BS densities of the tiers on their transmit power at the Nash equilibrium. Then, we investigate cooperative energy-efficient power control, where all the tiers cooperatively choose their transmit power to optimize their network EE. This cooperative power control is formulated as a multiobjective problem. To obtain Pareto-optimal solutions of the problem, we develop an algorithm that alternately updates the transmit power of the tiers. In addition to the transmit power, the circuit power consumption of the operating BSs and their active antennas affects the network EE. Due to the circuit power, activating all the BSs and turning on all the antennas may not be optimal in maximizing the network EE. Motivated by this observation, we also develop energy-efficient BS activation control and antenna activation control schemes. Finally, we extend the analysis to the highest signal-to-interference-plus-noise ratio (SINR) association, where each user connects to the BS that offers the highest SINR among the BSs in its tier. Simulation results show that the proposed energy-efficient designs significantly improve the network EE at the cost of small spectral efficiency loss compared with the spectral-efficient designs.</P>

Sum-Rate Improved Interference Alignment for the M x 2 MIMO X Channel

Younggap Kwon,Taewon Hwang IEEE 2012 IEEE COMMUNICATIONS LETTERS Vol.16 No.7

<P>In this letter, we propose an improved interference alignment (IA) scheme for the M × 2 constant multiple-input multiple-output (MIMO) X channel composed of M transmitters and two receivers with multiple antennas each. The proposed IA scheme enhances the sum rate as well as achieving the DOF outerbound. To enhance the sum rate, the proposed scheme designs the transmit beamformers that make the desired signal space and the interference space as close to orthogonal as possible. Simulation results show that the proposed IA scheme achieves similar sum rate as the random search scheme but with less computational complexity.</P>

Fault TolII. 데이터 재배열과 오류 정정erant Encryption and Data Compression under Ubiquitous Environment

유영갑(Younggap You),김한벼리(Hanbyeori Kim),박경창(Kyungchang Park),이상진(Sangjin Lee),김승열(Seungyoul Kim),홍윤기(Yoonki Hong) 한국콘텐츠학회 2009 한국콘텐츠학회논문지 Vol.9 No.8

본 논문은 암호화된 영상 데이터가 유비쿼터스 환경 하에서 무선 간섭에 의한 랜덤 오류를 가질 때 복호화 과정의 오류 산사태에 대한 해결책을 제시하였다. 영상 획득 장치는 영상 압축과 암호화 기능을 가지고서 데이터 트래픽 양을 줄이고 개인 정보를 보호하도록 구성한다. 블록 암호 알고리즘은 암호문의 단일 비트 오류가 여러 개의 픽셀 결함을 유발하는 산사태 효과를 겪을 수 있다. 새로운 고장 극복 방식은 오류의 산사태 효과를 다루는데 3 차원 데이터 셔플을 활용하여 에러 비트를 여러 프레임으로 분산시켜서 고립된 영상 결함으로 나타나도록 한다. 인접 화소 값에 대한 평균화 또는 다수결 회로는 에러정정을 위한 데이터 증가 없이 두드러져 보이는 화소 결함을 극복하도록 한다. 이 방식은 기존 Hamming code 방식보다 33% 적은 데이터 트래픽 부하를 가진다. This paper presents a solution to error avalanche of deciphering where radio noise brings random bit errors in encrypted image data under ubiquitous environment. The image capturing module is to be made comprising data compression and encryption features to reduce data traffic volume and to protect privacy. Block cipher algorithms may experience error avalanche: multiple pixel defects due to single bit error in an encrypted message. The new fault tolerant scheme addresses error avalanche effect exploiting a three-dimensional data shuffling process, which disperses error bits on many frames resulting in sparsely isolated errors. Averaging or majority voting with neighboring pixels can tolerate prominent pixel defects without increase in data volume due to error correction. This scheme has 33% lower data traffic load with respect to the conventional Hamming code based approach.

A Game With Randomly Distributed Eavesdroppers in Wireless Ad Hoc Networks: A Secrecy EE Perspective

Kwon, Younggap,Wang, Xudong,Hwang, Taewon IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.11

<P>We study energy-efficient secure communication using the combined approach of game theory and stochastic geometry in a large-scale wireless network, where legitimate transmitters (Alice nodes) and eavesdroppers (Eve nodes) are randomly distributed in space. We consider the following two scenarios according to the Eve tier's strategy: I) the Eve tier activates all its nodes to maximally eavesdrop the confidential messages of the Alice tier; and II) the Eve tier activates only a portion of its nodes to maximize its energy efficiency (EE) in eavesdropping according to the Alice tier's node activation. In Scenario I, we propose an alternating optimization scheme that maximizes the secrecy EE of the Alice tier by controlling the node-activation probability, the confidential message rate, the redundancy rate, and the number of active antennas. Simulation result shows that the proposed scheme can achieve the optimal secrecy EE. In Scenario II, we study an energy-efficient node activation game between the Alice tier and the Eve tier, where the former and the latter control their node-activation probabilities to maximize the secrecy EE and the eavesdropping EE, respectively. We show that the node activation game admits a unique Nash equilibrium. The node-activation probabilities of the Alice tier and the Eve tier at the Nash equilibrium can be used to estimate their network lifetimes, which are important information for the energy-efficient secure network design. Simulation result shows that the best-response dynamics converges to the Nash equilibrium within a few iterations.</P>

긴급조향회피 상황에서의 사고방지를 위한 조향보조 알고리즘 개발

김영갑(Younggap Kim),박찬호(Chanho Park),유동연(Dongyeon Yu),전소연(So-Yeon Jeon),황성호(Sung-Ho Hwang) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.5

최근 카메라, 레이더 등의 센서와 함께 전기전자 기술을 결합하여 사고를 사전에 감지하고 방지하기 위한 다양한 보조시스템이 개발되고 있다. 제동제어를 통해 사고를 예방하는 자동긴급제동(AEB)이 대표적인 시스템이나, 차속에 따라서는 사고를 충분히 회피하지 못한다는 단점이 있다. 반면, ESC는 운전자의 조향의도에 따라 차량의 제동력을 제어함으로써 차량의 언더스티어 또는 오버스티어를 방지하는 장치이다. 하지만 긴급사고 상황의 경우, 운전자가 조향을 했음에도 불구하고 ESC의 작동으로 인해 차량이 사고지점을 충분히 벗어나지 못하는 경우를 발생시키기도 한다. 따라서 본 연구에서는 긴급조향 회피 상황에서 부분제동 방법으로 장애물 회피경로를 추종하도록 하는 긴급 조향보조 알고리즘을 개발하였으며, 이는 휴먼인더루프 시뮬레이터를 통해 그 유효성을 검증하였다. Recently, various assist systems have been developed to detect and prevent accidents by combining electric and electronic technologies together with sensors such as cameras and radars. An autonomous emergency brake, which prevents accidents through braking control, has been developed as a representative assist system. However, the accident may not be sufficiently avoided, depending on the vehicle speed in some accident situations. Electronic stability control (ESC) is a system to prevent understeer or oversteer of a vehicle by controlling the braking force of the vehicle according to the intention of the driver. However, in the case of an emergency, ESC operation may cause the vehicle to fail to escape from the accident site, despite the driver`s steering. In this study, we developed a new steering assist algorithm to follow an obstacle avoidance path by partial braking in an emergency steering avoidance situation. The effectiveness of the algorithm was verified through a human-in-the-loop simulator.

부동산 중개사고 예방을 위한 실증연구

송영갑(Younggap Song),최민섭(Minseob Choi) 한국주거환경학회 2024 주거환경(한국주거환경학회논문집) Vol.22 No.1

This study aims to recognize the seriousness of real estate brokerage accidents that may occur in real estate leasing contracts and to identify important factors that can be prioritized to prevent them. To prevent this from happening, let's take a look at the types of real estate brokerage accidents and how they occur, as well as the current state of lease damage. Then, based on the factors selected from government policies, reports, papers, and 1:1 in-depth interviews with experts, we prioritized the factors that are important to prevent real estate brokerage accidents in real estate lease contracts through the Analytical Hierarchy Process (AHP). The results of the analysis showed that the following steps were taken: researching and verifying the seniority of the security deposit and the date of occupancy for multifamily housing units, checking the seniority rights, checking and notifying the availability of a return guarantee for the security deposit, verifying the owner (trust property, registered owner), and checking the status of the property with public records (also checking the status of the building). The results of this study will be used as a basis for preventing real estate brokerage accidents when signing real estate leases to establish transaction order in the real estate market.

Energy-Efficient Routing and Link Adaptation for 2D Wireless Relay Networks in the Wideband Regime

Kwon, Younggap,Park, Hyunsung,Oh, Jintaek,Miao, Guowang,Hwang, Taewon IEEE 2018 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.17 No.11

<P>We discuss the globally optimal energy-efficient design of a 2D relay network. Different from the existing routing protocols on energy saving, which finds the minimal energy route for a given data rate, the proposed algorithm jointly optimizes routing and data rate to maximize energy efficiency (EE) defined as the achievable data rate per power consumption. We propose a low-complexity algorithm to circumvent the huge complexity of the exhaustive search for the network EE maximization and prove its global optimality. Moreover, the proposed algorithm is implemented in a distributed fashion because each relay needs to send its routing information only to the relays in its adjacent tiers, which significantly reduces the signaling overhead of the centralized implementation. Our analysis on the worst-case complexity in a fading channel shows that the complexity of the proposed algorithm increases linearly while that of the exhaustive search increases exponentially as the tier index increases. Simulation results confirm that the proposed algorithm outperforms the existing routing protocols on energy saving and achieves the globally optimal network EE at a significantly lower complexity than the exhaustive search.</P>

인간 감각 정보를 위한 평생 기억용량 평가

유영갑(Younggap You),송영준(Young-Jun Song),김동우(Dong-Woo Kim) 한국콘텐츠학회 2009 한국콘텐츠학회논문지 Vol.9 No.1

본 논문은 일생동안 한 개인이 느끼는 오감 정보를 모두 저장하는 데 필요한 기억 용량을 분석하고 저장공간을 추정하였다. 추정된 저장 공간은 현대 압축 기술을 사용하였고, 오감 정보는 입거나 이식 가능한 유비쿼터스 환경하에서 얻어지는 센싱 정보이다. 저장 공간의 약 76%가 일반 텔레비젼 수준의 화질인 비디오 시각 정보를 저장하는 데 사용되고 저장 공간의 나머지 부분은 인덱스 정보를 포함하는 음성, 미각, 후각, 촉각 정보를 저장한다. 한 개인의 태아기를 포함한 일생 동안, 약 100년간의 데이터 저장에는 약 600 tera bytes의 저장 용량이 필요한 것으로 분석되었다. This paper presents a capacity estimation of a storage system accumulating all data sensed during the lifetime of an individual human being. The calculation assumes modern data compression and data collection schemes based on wearable or implanted devices under ubiquitous environment. More than 76% of the storage area is found to be used for video data storage of common TV image quality. The remaining storage area is for data from other sensing organs including audio, taste, olfactory and tactual systems in addition to indexing information. Total storage area of around 600 tera bytes is needed to cover 100 years of human life including his fetal period.

전기하이브리드 자율주행차량의 연비향상알고리즘 개발을 위한 시뮬레이션 환경 구축

김영갑(YoungGap Kim),박찬호(ChanHo Park),황성호(SungHo Hwang) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.4