PZEV 후처리 장치 최적화를 위한 이론적 접근

김영웅(Youngwoong Kim),김대중(Daejoong Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

A cusp aftertreatment technology has been required in order to meet the most stringent regulation like PZEV. As TWC system has been tried to apply for, technology to reduce LOT has been still hot issue. In this paper the allowable limit value of LOt ofTWC will be pointed out. GMDAT's recent advanced calculation program(AU-85) which can offer more minute calculation including durability and poisoning effect than current program(AU-53) showed a good correlation with current ULEVII system. This can be extended to apply to PZEV especially predicting in LOt behavior during warm up condition In this program cold start region can be divided into three areas which have own characteristics regarding temperature profiles set by each RPM, A/F and even PGM's oxidation energy. In calculating catalyst oxidation and internal combustion energy we assumed propane as a model gas following ideal gas behavior in NMHC. Lots of factors were requested in order to correlate test result as input data like engine RPM, A/F, engine displacement, catalyst loading, ratio and even cell density. Consequently by modulating major variables comprising catalyst design we could take on appropriate LOt which met target value set down based on previous emission vehicle program. It was possible to finalize the optimized configuration of catalyst system in cost and performance including PGM loading, ratio and cell density.

빗 형태 패턴을 가지는 OFDM 시스템을 위한 파일럿 심볼 기반 채널 주파수 응답의 추정

김영웅(Youngwoong Kim),김남훈(Namhoon Kim),윤은철(Eunchul Yoon) 한국통신학회 2014 韓國通信學會論文誌 Vol.39 No.6(통신이론)

본 논문은 OFDM 블록에 파일럿 심볼들이 빗 형태의 패턴에 따라 배치된 경우, 가상 부반송파를 가지는 OFDM 시스템의 channel frequency response (CFR)를 추정하는 여러 방식들을 서로 비교한다. 채널 임펄스 응답을 먼저 예측하는 것이 목적인 minimum mean square error (MMSE) 기반의 채널추정 방식과 누설현상의 억제가 목적인 MMSE 기반의 채널추정 방식이 지금까지 비교되지 않았기 때문에, 본 논문에서는 후자 방식과 전자 방식의 mean square error (MSE) 값들의 차이가 양수가 됨을 유도함으로써 전자 방식의 우수성을 논리적으로 증명한다. 아울러 본 논문에서는 파일럿 수의 변화가 MMSE 기반 채널추정 방식과 least-square (LS) 기반채널 추정 방식의 성능에 미치는 영향을 조사한다. 컴퓨터 시뮬레이션을 통해 채널추정 방식들의 성능을 정량적으로 확인한다. The pilot assisted channel frequency response (CFR) estimation schemes for an OFDM-based system with virtual subcarriers are analyzed under the assumption that pilot symbols are located according to a comb-type pattern in the OFDM block. In particular, as the minimum mean square error (MMSE) based scheme aiming to directly predict the channel impulse response and the MMSE based scheme aiming to suppress the leakage have not been clearly compared, by proving that the mean square errors (MSEs) of the latter scheme is always larger than that of the former scheme, this paper shows that the former scheme is superior to the latter scheme. Moreover, the impact of the number of pilots on the performances of the MMSE and least-square based channel estimation schemes are investigated. The performance analyses of the presented schemes are confirmed by computer simulation.

SUV 차량의 FCC LOT(t) 특성 해석 시도

김영웅(Youngwoong Kim),정종현(Chonghyeon Cheong),용승열(Seungyoul Yong) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11

Time-resolved calculation during the cold start period of FCC and BCC has been tried in view of HC emission and energy. Light off time (LOt) calculation of NEDC was implemented for the first time. Category in this first cycle of mode was discerned four kinds of regions: 1) key-on and 11sec idle, 2) short acceleration which BCC`s power is demanded and start of catalyst warm-up,, 3) steady and declined speed which catalyst warmed-up, 4) re-idle which Lot of FCC is reached. Test for temperature measurement was implemented on the different loadings of FCC. Calculation of FCC bed can actually be conducted according to the simplified region area done previous FTP vehicle. Result was shown with good differentiations. AU53 measure, which was firstly applied to the Euro-5 vehicle with low speed, indicated a good correlation with measured data besides FTP driven vehicle with high speed is applied in calculation. Consequently by combined major variables comprising of FCC we could forecast Lot values by modulation of major variables like A/F and RPM of Vehicle, heat capacity of FCC.

Towards semi-empirical approach of cold start behaviors to gasoline vehicle`s FCC

Youngwoong Kim(김영웅),Chongyoul Hong(홍종열),Seungryoul Yong(용승열) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11

KSULEV FCC 최적화를 위한 programming 시도

김영웅(Youngwoong Kim),정종현(Chonghyeon Cheong),용승열(Seungryoul Yong) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11

A state-of-art FCC technology has been strongly requested in order to achieve the most stringent emission requirement like PZEV. Appropriate TWC system, which is applicable for the reduction of both LOT and LOt should be established for this solution. In this paper GMK’s recent advanced calculation program (AU-53), which can offer more specific calculation including durability and poisoning effect than current program(AU-85), showed a good correlation with current ULEVII system. This can be extended to apply to PZEV especially predicting in LOt behavior during warm up condition. In this improved program cold start region can be also divided into three areas which have own characteristics regarding temperature profiles set by each RPM, A/F and even PGM’s combustion energy. In calculating catalyst oxidation and internal combustion energy we assumed more specific components rather propane as a model gas following ideal gas behavior in NMOG. This new programing achieved well correlation with SULEV vehicle rather ULEV applied to old Programming (AU-85). Lots of factors for AU-53 were requested in order to correlate test result as input data like engine RPM, A/F, engine displacement, catalyst loading, ratio and even cell density as was used same in AU-85. Consequently by combined major variables comprising of catalyst design we could take on appropriate LOt figures. Here in cold start research we can introduce significantly advanced programming technology comparing to conventional method. Optimized configuration of FCC system could be proposed in cost and performance including PGM loading, ratio and cell density

FBG pair 기반 방사선 유도 광손실 측정 기법

김영웅(Youngwoong Kim),김종열(Jong-Yeol Kim),황영관(Young-Gwan Hwan),이민웅(Minwoong Lee),송근영(Keun-Young Song) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10

본 논문에서는 기존 광섬유 방사선량계 기술의 문제점이었던 방사선 외 다양한 내·외적 요인에 의한 광신호의 광량 변화에 따른 센서 계측 신호의 왜곡 문제를 해결하기 위한 목적으로 FBG pair 기반의 방사선 유도 광손실 측정 기법 및 구성도를 제시하였다. 본 기법을 통해 광섬유 방사선량계 구성에서 신호전송부 광손실과 센서부 광손실 구분이 가능하며, 방사선량 측정 신뢰도를 향상시킬 수 있음을 보였다.

광섬유 임베디드 센서 기반 분포 모니터링 기술

김영웅(Youngwoong Kim),김종열(Jong-Yeol Kim),류국빈(Gukbeen Ryu),황영관(Young-Gwan Hwang),김현길(Hyun-Gil Kim) 한국정보통신학회 2022 한국정보통신학회 종합학술대회 논문집 Vol.26 No.2

소셜 네트워크에서 원거리 노드를 고려한 동적 사용자 신뢰도 평가 스킴

김영웅(Youngwoong Kim),최윤성(Younsung Choi),권근(Keun Kwon),전웅렬(Woongryul Jeon),원동호(Dongho Won) 한국정보보호학회 2014 정보보호학회논문지 Vol.24 No.2

소셜 네트워크 서비스는 인터넷상에서 다른 사람들과 친구 또는 사회적 관계를 맺을 수 있는 양방향 서비스로써 개방성을 바탕으로 인적 교류 네트워크의 중심이 되었다. 그러나 최근에는 개방성을 악용하여 신뢰할 수 없는 유언비어가 확산되고 개인 정보를 침해하는 다양한 공격으로 인해 여러 사용자들이 피해를 보는 사례가 발생하였다. 따라서 소셜네트워크상에서의 정보는 신뢰할 수 있는 사람에게 전달하거나 혹은 제공 받을 수 있어야 한다. 최근의 신뢰도 연구에서는 사용자와 밀접한 한 홉 사이를 기반으로 한 신뢰도 평가방법들이 주로 제시되었다. 그러나 소셜 네트워크의 교류가 기존의 시공간성이 갖는 제약을 넘어서고 사용자도 큰 폭으로 늘어나면서 한 홉 사이뿐 아니라 여러 홉 사이에서의 교류 역시 최근에 많이 증가하고 있다. 이러한 흐름에 맞춰 본 논문에서는 전이성 및 결합성을 이용하여 원거리에서도 신뢰도 평가가 가능한 효과적인 사용자 신뢰도 평가 스킴을 제안한다. The social network service is the bidirectional media that many users can build relations not only friends but also other people. However, a process to approach in the social network is so simple that untrustable information, which malignant users make, is spreaded rapidly in many the social network uses. This causes many users to suffer material or psychological damages. Because of openness in the social network, there will be higher risk of the privacy invasion. Therefore, sensitive information should be transferred or provided only to reliable users. In general, because many users exchange among one hops, many researches have focused on one hop’s trust evaluation. However, exchanges between users happen not only one joint bridege but also far nodes more than two nodes on account of dense network and openness. In this paper we propose the efficient scheme combining transitivity and composability for remote users.

AU53에 의한 경차의 FCC loading 차이해석 시도

김영웅(Youngwoong Kim),정종현(Chonghyeon Cheong),심상경(Sangkyung Shim) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5

Calculation of FCC in cold start performance of gasoline vehicle has been continuously demanded in order to achieve not only emission requirement but also effective design. Specifically evolved HC emission and calculated LOT (LOt) in TWC femto-second reaction system can be closely related to current AU53 measure. Unlike any others, AU-53 program, which can be applicable to PZEV, indicated a good correlation with current ULEVII small BCC system. Of particular importance was the requested test result as correlation basis with engine RPM, A/F, engine displacement, catalyst loading, ratio and even cell density as usual. Loading differences in LOt of FCC could result in the little influence of effectiveness. Consequently by combined major variables comprising of FCC design we could forecast on solid LOt figures. Appropriate design configuration of current FCC system could be proposed in cost and performance including PGM loading and substrate shape besides modulation of A/F by using IVT and LOt.

Inverse Class-F 기법을 이용한 900 ㎒ 전류 모드 Class-D RF 전력 증폭기 설계

김영웅(Youngwoong Kim),임종균(Jonggyun Lim),강원실(Wonshil Kang),구현철(Hyunchul Ku) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.12

본 논문에서는 900 ㎒ 대역에서 동작하는 전류 모드 Class-D(Current-Mode Class-D: CMCD) 전력 증폭기를 설계 및 제작하고 특성을 분석하였다. 차동 구조에 의해 짝수차 고조파 성분이 제거된다는 점에 착안하여 출력단의 일반적인 CMCD 회로의 병렬 공진기를 제거하고 inverse class-F 전력 증폭기를 push-pull 구조로 연결하여 CMCD 전력 증폭기를 설계하였다. 로드-풀 기법을 이용하여 GaN 소자 기반의 inverse class-F 및 이를 적용한 CMCD 전력 증폭기를 설계 및 제작하였다. 제작한 CMCD는 34.2 ㏈m의 출력과 64.5 %의 드레인 효율을 가지며, 이는 출력측에 공진기 구조를 가지는 일반적인 CMCD 전력 증폭기의 드레인 효율과 비교했을 때 13.6 %의 효율 향상을 가진다. In this paper, Current-Mode Class-D(CMCD) RF Power Amplifier(PA) is designed and implemented at 900 ㎒. Conventional CMCD PA has output parallel resonator to reconstruct a fundamental frequency component of the output signal. However the resonator can be removed by connecting inverse class-F PAs because even-harmonic components can be removed by CMCD PA’s push-pull structure. Using load-pull, inverse class-F PA with GaN transistors is designed, and CMCD PA with the inverse class-F PA is implemented. The CMCD PA has 64.5 % drain efficiency, 34.2 ㏈m output power. Comparing with the drain efficiency of a CMCD PA with parallel resonator, the CMCD with the inverse class-F technology has 13.6 % improved drain efficiency.