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저압 EGR 시스템을 이용한 V6 3.0ℓ엔진의 연비 최적화 개발
이해욱(Haewook Lee),조청훈(Chunghoon Jo),남기훈(Kihoon Nam),이세영(Seyoung Lee),이은현(Eunhyun Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
As the markets require more environmentally friendly and high fuel consumption vehicle, we have to satisfy bilateral target. Though many new after-treatment techniques like LNT, SCR are investigated to meet both strong emission regulations and low fuel consumption, high cost of these techniques should be solved to adopt widely. This paper describes how to optimize the dual loop EGR as a tool to reduce CO2 emission of a HSDI diesel engine in the passenger car application. Focus is not only on the optimization to obtain the maximum CO2 reduction but also on how to assess and overcome various side effects. As a result of careful optimization, as much as 6% CO2 reduction was achieved by introduction of low pressure EGR loop, maintaining the same boundary conditions as those with high pressure EGR loop only. Not only the dual EGR system but also further improvement was applied such as combustion improvement, friction reduction and many others to achieve as much as 20% total CO2 reduction. The dual loop EGR was proven to be an effective solution to reduce CO2 and therefore it is considered to be one of the core technologies in the passenger diesel applications of Hyundai-Kia Motors to meet the future CO2 regulation.
MMSE-Based Filter Designs for Cognitive Multiuser Two-Way Relay Networks
Haewook Park,Changick Song,Hoon Lee,Inkyu Lee IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.4
<P>This paper considers cognitive multiuser two-way relay networks (MU-TRNs) where multiple secondary users (SUs) concurrently exchange their data with other SUs with an aid of a two-way relay in licensed primary networks. In this paper, we particularly focus on linear relay filter designs that effectively minimize the mean square error of SUs while providing a certain level of quality of service for the primary network. To this end, we first propose an iterative algorithm that identifies a solution based on an alternating optimization technique. Then, a closed-form relay filter design is presented, which employs a high signal-to-noise ratio approximation to reduce the computational complexity. Through the simulation results, we confirm that the proposed closed-form relay filter design outperforms conventional approaches and provides the performance close to the proposed iterative algorithm with much reduced complexity.</P>
이해욱(Haewook Lee),추정범(Jungbum Choo),조청훈(Chunghoon Jo),지요한(Yohan Ji),윤금중(Kumjung Yoon) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, 'Clean Diesel' is rising for a countermeasure of high oil prices and global warming. And it accelerates the extension of the passenger car diesel engine market in North America as well as in Europe. We need to contrive the emission of engine for more dynamic driving mode than FTP75 and US06, which are the test cycle of US emission regulation as well as NEDC, which is that of European emission regulation. Existing emission development based on dynamometer by mapping of steady state 14-mode which simulates NEDC, relatively mild driving condition, has limitation because it cannot fully simulate vehicle driving motion. In this research, it is introduced a necessary simulation of vehicle motion, test conditions, test method for developing vehicle emission by using dynamic dynamometer. In addition, the difference of test results is compared and the methods for more accurate simulation are proposed.
Park, Haewook,Lee, Seungeun,Ko, Guen Bae,Lee, Jae Sung Institute of Physics in association with the Ameri 2018 Physics in medicine & biology Vol.63 No.24
<P>Coincidence resolving time (CRT) is one of the most important physical-performance measures for positron emission tomography (PET), as reconstruction with accurate time-of-flight information enhances the lesion detectability in patient studies. Accordingly, various PET detector designs and high-performance front-end readout circuits have been actively investigated to improve timing performance. The resulting PET detectors are often evaluated using multichannel waveform digitizers for versatile data analysis of the output signals. However, we have found that inappropriate data acquisition (DAQ) using a multichannel waveform digitizer based on the domino-ring-sampler 4 (DRS4) chip can lead to a considerable error when determining CRT. To address this issue, we performed CRT measurements using a pair of Hamamatsu R9800 photomultiplier tube based PET detectors. Then, considering intra- and inter-chip sampling, we employed four different combinations of input channels into the CAEN DT5742B waveform digitizer and obtained 2D CRT maps according to the leading-edge discriminator threshold for assessing each DAQ scheme. The intra-chip CRT measurement exhibited unusual streak patterns in the 2D CRT map and yielded the artificially-low CRT information in PET detector pairs, whereas the inter-chip CRT measurement provided the reliable estimation of timing resolution. Further, we could prevent the high-frequency signal crosstalk among input channels within the DRS4 chip using the inter-chip CRT measurement. We expect that our findings will also be useful for achieving the reliable CRT measurements when using other single-chip-based multichannel waveform digitizers.</P>
이해욱(Lee, Haewook) 한국실내디자인학회 2010 한국실내디자인학회논문집 Vol.19 No.6
The population of the elderly is rapidly increased because maturation of the social welfare system and development of medical technology. However, welfare environments for the elderly are poor either in its quality or its quantity. The aims of this study is to confirm the space improvement possibility to change the Gyung Ro Dang to the senior life support center as a community welfare service network. This study is done by the comparative analysis between existing Gyung Ro Dang in korea and former cases in Japan based on the elderly’s facility preference. The facility’s space reprogramming alternative from that analysis is applied to change the Gyung Ro Dang to a network facility for the regional senior life support. Afterward, it is proposed that first, facilities should be expanded scale by the new education and health improvement facilities functional room that the modern elderly need. second, Facility space will be reconstitution because the Gyung Ro Dang have to be extended it’s role as a community welfare network.
Bit Allocation and Pairing Methods for Multi-User Distributed Antenna Systems With Limited Feedback
Hoon Lee,Eunsung Park,Haewook Park,Inkyu Lee Institute of Electrical and Electronics Engineers 2014 IEEE Transactions on Communications Vol. No.
<P>In this paper, we study bit allocation and pairing methods based on distributed zero forcing beamforming for downlink multi-user distributed antenna (DA) systems with limited feedback. Before assigning the feedback bit for each DA port, we need to solve the pairing issue that determines the set of DA ports to support a user. To this end, we first analyze an upper bound of a mean rate loss between perfect channel state information systems and limited feedback systems. Since minimizing the obtained bound is a joint optimization problem with respect to the pairing and the bit allocation, it is difficult to identify a solution analytically. Instead, we propose a two-step algorithm that derives the pairing based on the bound of the rate loss and then obtain the non-iterative bit allocation method independently. To further improve the performance, an enhanced feedback bit allocation algorithm is also proposed by applying an iterative optimization technique. In addition, we investigate a scaling law of limited feedback systems to maintain a constant rate loss as signal-to-noise ratio increases. From simulation results, we confirm that the proposed algorithms offer about 135% performance gains over a conventional scheme for five DA port systems and verify that our analysis is well matched with the numerical results.</P>