STUDY ON THE CHARACTERISTICS OF DI DIESEL ENGINE WITH SWIRL CHAMBER

Yu Liu,Mincheol Kim,Jongsang Park,Jeongkuk Yeom,Jongyul Ha,Sungsik Chung 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

The purpose of this study is to obtain both low emissions and high thermal efficiency by using strong swirl in DI diesel engine. A special combustion chamber is designed which can generate strong swirl with the piston movement. With strong swirl the well-mixed gas can be formed quickly, and the combustion performance can be improved accordingly. Software FIRE is used to simulate injection and combustion process of DI diesel engine with swirl chamber. Equivalence ratio, temperature field and emissions distribution have been analyzed. Some characteristics of this DI engine with swirl chamber have been compared with normal DI diesel engine too. The study results show: The engine with swirl chamber has the characteristics of fast mixture formulation and quick diffusive combustion; the soot of this combustion system is much better than normal DI engine, but the NOx emission is not quite satisfied.

A Study on the Factors Affecting E-logistics Systems in the Chinese Logistics Industry

Yu, Liu,Bae, Jung-Han Korea Association for International Commerce and I 2009 통상정보연구 Vol.11 No.2

With the rapid growth of e-logistics in the global logistics industry, it is important to gain further insight into this growing segment of Chinese logistics industry. The current situation in China consists of many small and medium-sized logistics firms. Furthermore, e-logistics is still relatively undeveloped in the majority of the Chinese logistics companies and presently there are still many problems unresolved. This paper attempted to review the concepts and theoretical background of e-logistics systems from previous studies. After acknowledging the essential issues related to e-logistics systems, a research model based on the theory acceptance model was designed and tested. The key factors to the e-logistics system (reliability, maintainability, software, facility and transportation) were validated through the modeling and testing process. Included in the modelling and testing process are other related factors of e-logistics process, logistics information system and added value as dependent variables in this model. The results of this study confirm that the e-logistics Process is affected by transportation, while maintainability and software factors influence logistics information system. reliability, maintainability, facility and transportation are significant factors associated with added value. This research aimed to provide theoretical and practical contribution to Chinese logistics companies and to give some insights into e-logistics system as a whole. The paper also provided some useful theoretical implication and practical guidelines for the development of e-logistics system in the chinese logistics industry.

A Study on the Factors Affecting E-logistics Systems in the Chinese Logistics Industry

Yu, Liu,Bae, Jung-Han Korea Association for International Commerce and I 2009 International Commerce and Information Review Vol.2 No.1

With the rapid growth of e-logistics in the global logistics industry, it is important to gain further insight into this growing segment of Chinese logistics industry. The current situation in China consists of many small and medium-sized logistics firms. Furthermore, e-logistics is still relatively undeveloped in the majority of the Chinese logistics companies and presently there are still many problems unresolved. This paper attempted to review the concepts and theoretical background of e-logistics systems from previous studies. After acknowledging the essential issues related to e-logistics systems, a research model based on the theory acceptance model was designed and tested. The key factors to the e-logistics system (reliability, maintainability, software, facility and transportation) were validated through the modeling and testing process. Included in the modelling and testing process are other related factors of e-logistics process, logistics information system and added value as dependent variables in this model. The results of this study confirm that the e-logistics Process is affected by transportation, while maintainability and software factors influence logistics information system. reliability, maintainability, facility and transportation are significant factors associated with added value. This research aimed to provide theoretical and practical contribution to Chinese logistics companies and to give some insights into e-logistics system as a whole. The paper also provided some useful theoretical implication and practical guidelines for the development of e-logistics system in the chinese logistics industry.

Audio Fingerprinting Based on Multiple Hashing in DCT Domain

Yu Liu,Hwan Sik Yun,Nam Soo Kim IEEE 2009 IEEE signal processing letters Vol.16 No.6

<P>Audio fingerprinting techniques aim at successfully performing content-based audio identification even when the audio signals are slightly or seriously distorted. In this letter, we propose a novel audio fingerprinting technique based on multiple hashing. In order to improve the robustness of hashing, multiple hash strings are generated through the discrete cosine transform (DCT) which is applied to the temporal energy sequence in each subband. Experimental results show that the proposed algorithm outperforms the Philips Robust Hash (PRH) algorithm under various distortions.</P>

다중 해싱을 이용한 새로운 오디오 핑거프린팅 알고리즘

Yu Liu,윤환식(Hwan Sik Yun),조기호(Kiho Cho),김남수(Nam Soo Kim) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6

A Kalman Filter based Video Denoising Method Using Intensity and Structure Tensor

( Yu Liu ),( Chenlin Zuo ),( Xin Tan ),( Huaxin Xiao ),( Maojun Zhang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.8

We propose a video denoising method based on Kalman filter to reduce the noise in video sequences. Firstly, with the strong spatiotemporal correlations of neighboring frames, motion estimation is performed on video frames consisting of previous denoised frames and current noisy frame based on intensity and structure tensor. The current noisy frame is processed in temporal domain by using motion estimation result as the parameter in the Kalman filter, while it is also processed in spatial domain using the Wiener filter. Finally, by weighting the denoised frames from the Kalman and the Wiener filtering, a satisfactory result can be obtained. Experimental results show that the performance of our proposed method is competitive when compared with state-of-the-art video denoising algorithms based on both peak signal-to-noise-ratio and structural similarity evaluations.

Scratchpad Memory Architectures and Allocation Algorithms for Hard Real-Time Multicore Processors

Yu Liu,Wei Zhang 한국정보과학회 2015 Journal of Computing Science and Engineering Vol.9 No.2

Time predictability is crucial in hard real-time and safety-critical systems. Cache memories, while useful for improving the average-case memory performance, are not time predictable, especially when they are shared in multicore processors. To achieve time predictability while minimizing the impact on performance, this paper explores several time-predictable scratch-pad memory (SPM) based architectures for multicore processors. To support these architectures, we propose the dynamic memory objects allocation based partition, the static allocation based partition, and the static allocation based priority L2 SPM strategy to retain the characteristic of time predictability while attempting to maximize the performance and energy efficiency. The SPM based multicore architectural design and the related allocation methods thus form a comprehensive solution to hard real-time multicore based computing. Our experimental results indicate the strengths and weaknesses of each proposed architecture and the allocation method, which offers interesting on-chip memory design options to enable multicore platforms for hard real-time systems.

Study of Combustion and Emission Characteristics for DI Diesel Engine with a Swirl-Chamber

( Yu Liu ),( S. S. Chung ) 한국분무공학회 2010 한국액체미립화학회지 Vol.15 No.3

DEVELOPMENT OF CHINA LIGHT-DUTY VEHICLE TEST CYCLE

Yu Liu,Zhi Xin Wu,Hua Zhou,Han Zheng Nan Yu,Xiao Pan An,Jing Yuan Li,Meng Liang Li 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5

Driving cycles provide a basis for vehicle development and calibration and also serves as the foundation for energy consumption and emissions certification of vehicles. This paper presents the China Light-Duty Vehicle Test Cycle (CLTC) developed by the China Automotive Technology & Research Center (CATARC). First, the important steps and technical routes toward the CLTC development process are summarized. Second, the specific CLTC development process is presented in detail, including the data acquisition and data analysis procedures, weighting factor development and driving cycle construction. Then, the main driving characteristics of the New European Driving Cycle (NEDC), the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC), the Federal Test Procedure (FTP-75), the CLTC and the actual collected data are compared. The CLTC has low average speed, a high idle speed ratio and more frequent acceleration and deceleration characteristics. Finally, 70 vehicles are t ested based on the NEDC, WLTC, and CLTC according to their legislative procedures in the vehicle emission laboratories of the CATARC and the manufacturers. The results show that the CLTC’s fuel consumption is much higher than that of the NEDC and WLTC, and CLTC can effectively reflect the actual fuel consumption of users.

4차 산업혁명 기술의 플랫폼을 활용한 중소기업의 수출 및 유통 개선 전략: 중국 중소기업을 중심으로

( Yu Liu ),( Hui-fang Liu ),정진섭 ( Jin-sup Jung ) 한국유통경영학회(구 한국유통정보학회) 2020 유통경영학회지 Vol.23 No.6

Purpose: This study recognizes the importance of platforms in the era of the 4th Industrial Revolution, and applies them to small and medium enterprises (SMEs). If we narrow down further, it is important to have a high-tech platform to expand exports or distribution of SMEs. In other words, we want to emphasize the importance of export and distribution platforms in improving the management performance of SMEs. Research design, data, and methodology: The key capabilities and activities - marketing competency, business strategy, production system, and logistics systems - were used as independent variables, and the dependent variable was business performance. We also analyzed the impact of export and distribution platform based on the 4th Industrial Revolution Technology as mediating variables on the business performance of SMEs. The questionnaire in this study used a five-point scale and the survey period was from March 15 to April 15, 2020. A survey was conducted on SMEs based in Shandong Province, China. A total of 289 survey data were used for the final analysis. Results: First of all, marketing competency, business strategy, production system, and logistics system [independent variables] have positive effects on both export platform and distribution platform. Subsequently, independent variables, which were value chain-based capabilities and activities, have positive effects on business performance. Finally, both export platform and distribution platform showed positive partial mediating effects on business performance of SMEs. Conclusions: Results shows that the use of the platform based on the 4th Industrial Revolution Technology can enhance business performance. Therefore, in subsequent studies to be based on this study, the issue of "how to create a useful export platform and improve the distribution platform" will be more important. In particular, this article presents meaningful implications in terms of applying the state-of-the-art platform of export and distribution to enhance business performance of SMEs.