• Journal of Power Electronics
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• v.5 no.3
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• pp.198-205
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• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.31-39
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• 2014

Recently, as Intelligent Transportation System (ITS) and self-driving system become influential in the ground transportation system, automotive radar systems have been actively studied among the various radar systems to implement the vehicle collision detection system and distance measurement system between vehicles. Most of the automotive radars are Frequency Modulated Continuous Wave (FMCW) radar type which can calculate distance and velocity of target by estimating the frequency difference between the transmitted signal and received signal. Therefore, accurate frequency estimation is very important in the FMCW radar system. For this reason, to improve the measurement accuracy of the FMCW radar, Reverse Directional FRI (RD-FRI) Super-Resolution technique which has high frequency estimation accuracy is applied to the FMCW radar system. The feasibility of the proposed technique is evaluated with simulation results and compared with FFT and conventional Super-Resolution techniques. The simulation results show that the proposed technique estimates the frequency with high accuracy and the distance with centimeter accuracy.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.1007-1010
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• 2019

주행 중인 자율주행차의 탑승자는 차량의 거동을 예측할 수 없기 때문에 불안함을 느낄 수 있으므로 차량의 거동 정보를 사전에 탑승자에게 전달하여 심리적 안정을 제공하는 것은 중요하다. 본 논문에서는 완전 자율주행 상황을 가정하여 자율주행 시스템이 발생시키는 주행 의도를 탑승자에게 전달하는 하드웨어 시스템을 제안한다. 제안하는 시스템은 자율주행차량이 사전에 생성된 경로를 따라 주행하면서 출발, 정지, 방향 전환 등과 같은 총 5 가지 상황에 대한 시각, 청각 및 촉각 알림을 통한 자율주행 의도 전달하는 것을 고려한다. 차량용 시트에 모터를 부착하여 촉각 알림을 통해 자율주행 의도를 전달 하였으며, 모니터를 통해 시각 및 청각 알림을 통해 자율주행 의도를 전달하였다. PC 에서 개발에 필요한 시뮬레이션 데이터를 처리하였으며, 시뮬레이션 환경에서 개발, 실험 및 평가가 진행되었다.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.31-39
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• 2021

This study collected 1,870 English news articles related to research and development of autonomous vehicles in order to identify various issues emerging in the research and development process of autonomous vehicles at home and abroad, and conducted topic modeling after data pre-processing. As a result of topic modeling, we extracted 20 topics, and we performed naming operations for topics and interpreted their meanings. A logical model for autonomous vehicle research and development projects was presented in response to the R&D process of input, activity, output, and outcome of derived topics. The analysis results of this study will be used as basic data to accurately determine the progress of domestic and foreign self-driving car research and development projects and prepare for the rapidly changing technology development.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.383-403
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• 2021

With the development of mobile edge computing (MEC), some late-model application technologies, such as self-driving, augmented reality (AR) and traffic perception, emerge as the times require. Nevertheless, the high-latency and low-reliability of the traditional cloud computing solutions are difficult to meet the requirement of growing smart cars (SCs) with computing-intensive applications. Hence, this paper studies an efficient offloading decision and resource allocation scheme in collaborative vehicular edge computing networks with multiple SCs and multiple MEC servers to reduce latency. To solve this problem with effect, we propose a context-aware offloading strategy based on differential evolution algorithm (DE) by considering vehicle mobility, roadside units (RSUs) coverage, vehicle priority. On this basis, an autoregressive integrated moving average (ARIMA) model is employed to predict idle computing resources according to the base station traffic in different periods. Simulation results demonstrate that the practical performance of the context-aware vehicular task offloading (CAVTO) optimization scheme could reduce the system delay significantly.

• Cross-Cultural Studies
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• v.35
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• pp.215-235
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• 2014

The purpose of this paper look at the basis of the cultural differences of Korean and Japan by comparing the craftsmanship. Korean craftsmanship and master craftsman making traditional handcrafts and artwork would die out at a critical moment. The craftsmanship and system could not be established because of discrimination in the traditional four classes of society( scholars, farmers, artisans and tradesmen), invasions of other countries and discontinuity of tradition from modernization. On the contrast, in Japan, it was possible to establish traditional handcrafts and artworks, technique and craftsmanship with apprentice system and various social privilege and treatment even in the same traditional four classes of society ( scholars, farmers, artisans and tradesmen). It was common to pass down the family business for a hundreds of years with self respect between Japanese master craftsmen and lots of people succeed the family business will now. Japanese craftsmanship is originated from 'worship to god' Medieval Japanese believed that the thing changes human mind, artistic talent, masterpieces and faith were connected to sacred power. Therefore, master craftsmen and their works were also made by the power of god. In this context, craftsmen were protected and treated in socially and nationally. It is that the social treatments and supports in national level and their own pride and continuous training of techniques and abilities as the main driving force to maintain the craftsmanship in Japan. Korea has the sale level of competitive tradition and technique in comparison any other countries. Japanese craftsmanship study will be a critical data in the protection and maintenance of Korean traditional and technique.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.2042-2059
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• 2019

Digital shadow puppet has traditionally relied on expensive motion capture equipments and complex design. In this paper, a low-cost driven technique is presented, that captures human pose estimation data with simple camera from real scenarios, and use them to drive virtual Chinese shadow play in a 2.5D scene. We propose a special method for extracting human pose data for driving virtual Chinese shadow play, which is called 2.5D human pose estimation. Firstly, we use the 3D human pose estimation method to obtain the initial data. In the process of the following transformation, we treat the depth feature as an implicit feature, and map body joints to the range of constraints. We call the obtain pose data as 2.5D pose data. However, the 2.5D pose data can not better control the shadow puppet directly, due to the difference in motion pattern and composition structure between real pose and shadow puppet. To this end, the 2.5D pose data transformation is carried out in the implicit pose mapping space based on self-network and the final 2.5D pose expression data is produced for animating shadow puppets. Experimental results have demonstrated the effectiveness of our new method.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.104-114
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• 2019

Energy is an essential driving force for modern society. In particular, electricity has become the standard source of power for almost every aspect of life. Electric power runs lights, televisions, cell phones, laptops, etc. However, it has become apparent that the current methods of producing this most valuable commodity combustion of fossil fuels are of limited supply and has become detrimental for the Earth's environment. It is also self-evident, given the fact that these resources are non-renewable, that these sources of energy will eventually run out. One of the most promising alternatives to the burning of fossil fuel in the production of electric power is the proton exchange membrane (PEM) fuel cell. The PEM fuel cell is environmentally friendly and achieves much higher efficiencies than a combustion engine. Water management is an important issue of PEM fuel cell operation. Water is the product of the electrochemical reactions inside fuel cell. If liquid water accumulation becomes excessive in a fuel cell, water columns will clog the gas flow channel. This condition is referred to as flooding. A number of researchers have examined the water removal methods in order to improve the performance. In this paper, a new water removal method that investigates the use of vibro-acoustic methods is presented. Piezo-actuators are devices to generate the flexural wave and are attached at end of a cathode bipolar plate. The "flexural wave" is used to impart energy to resting droplets and thus cause movement of the droplets in the direction of the traveling wave.

• Current Optics and Photonics
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• v.3 no.5
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• pp.423-428
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• 2019

Visibility of road-surface markings is one of the critical issues that should be secured for self-driving cars as well as human drivers. Glass beads are taking on the role of retroreflectors, and therefore are considered a necessity in modern pavements. In this context, retroreflectance is sensitively dependent not only on the refractive index of glass beads but also on that of the surrounding medium. This implies that the optimum refractive index of glass beads immersed in water, i.e. under wet conditions, is different from that of glass beads surrounded by air, i.e. under dry conditions. A refractive index of approximately 1.9, which is known to maximize retroreflectance under dry conditions, actually exhibits much poorer retroreflectance under wet conditions. This suggests that glass beads with optimal refractive index for wet conditions need to be installed together with those for dry conditions. We propose a facile but practical model capable of calculating retroreflectance of glass beads surrounded by an arbitrary medium, here water in particular, and experimentally verify its capability of assessing the refractive index of commercial glass beads. Changes in retroreflectance according to the mixing ratio of glass beads with different refractive indices are also discussed, in an effort to propose the proper use of glass beads produced for dry and wet conditions.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.181-189
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• 2021

The COVID-19 pandemic has impacted the tourism industry due to the resulting travel restrictions as well as a slump in demand among travelers. The tourism industry has been massively affected by the spread of coronavirus, as many countries have introduced travel restrictions in an attempt to contain its spread. In Vietnam, the government has largely been credited for the country's success in keeping COVID-19 transmission rates under control. Early awareness of the pandemic, appropriate, drastic, and people-centric measures, as well as public support, are the main factors behind the success of Vietnam. In that context, it is observed that people's travel demand has bounced back and this research will examine factors driving the public's travel intention in the post-crisis (pandemic) period. The survey was conducted on the Internet using questionnaires designed in the Google platform. Data was collected from April 16 to May 31, 2020, from 154 Vietnamese participants. Research findings demonstrate 4 direct and indirect determinants of travel intention. The strongest effects come from perceived behavioral control which is influenced by subjective well-being. Perceived risk negatively correlates with Self-efficacy and subjective well-being. Conducted in the context of post-COVID-19, the research implies that once the pandemic has been controlled, perceived risks, although still exist, insignificantly influence the public's travel intention.