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Mathematical Model and Design Optimization of Reduction Gear for Electric Agricultural Vehicle
Pandu Sandi Pratama,변재영,Eun-Suk Lee,Dimas Harris Sean Keefe,Ji-Ung Yang,정성원,최원식 한국산업융합학회 2019 한국산업융합학회 논문집 Vol.22 No.1
In electric agricultural machine the gearbox is used to increase torque and lower the output speed of the motor shaft. The gearbox consists of several shafts, helical gears and spur gears works in series. Optimization plays an important role in gear design as reducing the weight or volume of a gear set will increase its service life and improve the bearing capacity. In this paper the basic design parameters for gear like shaft diameter and face width are considered as the input variables. The bending stress and material volume is considered as the objective function. ANSYS was used to investigate the bending stress when the variable was changed. Artificial Neural Network (ANN) was used to obtain the mathematical model of the system based on the bending stress behaviour. The ANN was used since the output system is nonlinear. The Genetic Algorithm (GA) technique of optimization is used to obtain the optimized values of shaft diameter and face width on the pinion based on the ANN mathematical model and the results are compared as that obtained using the traditional method. The ANN and GA were performed using MATLAB. The simulation results were shown that the proposed algorithm was successfully calculated the value of shaft diameter and face width to obtain the minimal bending stress and material volume of the gearbox.
Merging Collaborative Learning and Blockchain: Privacy in Context
( Sandi Rahmadika ),( Kyung-hyune Rhee ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.1
The emergence of collaborative learning to the public is to tackle the user's privacy issue in centralized learning by bringing the AI models to the data source or client device for training Collaborative learning employs computing and storage resources on the client's device. Thus, it is privacy preserved by design. In harmony, blockchain is also prominent since it does not require an intermediary to process a transaction. However, these approaches are not yet fully ripe to be implemented in the real world, especially for the complex system (several challenges need to be addressed). In this work, we present the performance of collaborative learning and potential use case of blockchain. Further, we discuss privacy issues in the system.
Sandy E. Benitez-Garcia,Isao Kanda,Yukiyo Okazaki,Shinji Wakamatsu,Roberto Basaldud,Nobuji Horikoshi,Jose A. Ortinez,Victor R. Ramos-Benitez,Beatriz Cardenas 한국대기환경학회 2015 Asian Journal of Atmospheric Environment (AJAE) Vol.9 No.2
In the Mexico City Metropolitan Area (MCMA), ozone (O3) concentration is still higher than in other urban areas in developed countries. In order to reveal the current state of photochemical air pollution and to provide data for validation of chemical transport models, vertical profiles of meteorological parameters and ozone concentrations were measured by ozonesonde in two field campaigns: the first one, during the change of season from wet to dry-cold (November 2011) and the second during the drywarm season (March 2012). Unlike previous similar field campaigns, ozonesonde was launched twice daily. The observation data were used to analyze the production and distribution of ozone in the convective boundary layer. The observation days covered a wide range of meteorological conditions, and various profiles were obtained. The evolution of the mixing layer (ML) height was analyzed, revealing that ML evolution was faster during daytime in March 2012 than in November 2011. On a day in November 2011, the early-morning strong wind and the resulting vertical mixing was observed to have brought the high-ozone-concentration air-mass to the ground and caused relatively high surface ozone concentration in the morning. The amount of produced ozone in the MCMA was estimated by taking the difference between the two profiles on each day. In addition to the well-known positive correlation between daily maximum temperature and ozone production, effect of the ML height and wind stagnation was identified for a day in March 2012 when the maximum ground-level ozone concentration was observed during the two field campaigns. The relatively low ventilation coefficient in the morning and the relatively high value in the afternoon on this day implied efficient accumulation of the O3 precursors and rapid production of O3 in the ML.
Model Structuring of Taiwan’s Community Policing
Sandy Yeh,Charles Chang,Jeff Martin,Leo Chiou,Yuang-Sung Chang 아시아경찰학회 2007 아시아경찰학회 국제학술회의 Vol.2007 No.-
This study is sponsored by National Police Agency, Taiwan from December 29, 2006 to July 15, 2007. The purpose of this study explores the factors of the successful community model and tries to establish a model structuring that other communities can learn. On this paper, the SWOT analysis of community environment is introduced first. Second, the SARA analysis of community problems is addressed. Third, the key elements to promote community policing in Taiwan is presented. The last section is the conclusion.
The Dilemma of Parameterizing Propagation Time in Blockchain P2P Network
Sandi Rahmadika,노시완,이경모,Bruno Joachim Kweka,이경현 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.3
Propagation time on permissionless blockchain plays a significant role in terms of stability and performance inthe decentralized systems. A large number of activities are disseminated to the whole nodes in the decentralizedpeer-to-peer network, thus causing propagation delay. The stability of the system is our concern in the firstplace. The propagation delay opens up opportunities for attackers to apply their protocol. Either by acceleratingor decelerating the propagation time directly without proper calculation, it brings numerous negative impactsto the entire blockchain system. In this paper, we thoroughly review and elaborate on several parameters relatedto the propagation time in such a system. We describe our findings in terms of data communication, transactionpropagation, and the possibility of an interference attack that caused an extra propagation time. Furthermore,we present the influence of block size, consensus, and blockchain scalability, including the relation ofparameters. In the last session, we remark several points associated with the propagation time and use cases toavoid dilemmas in the light of the experiments and literary works.