• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.631-636
• /
• 1987

The design of ultrasonic transducer energy processing systems requires highly reliable command featuring mechanical frequency tracking and constant velocity control of the ultrasonic transducer with an acoustic load. This paper presents a new conceptional instantaneous current resultant control base high-frequency inverter using self turn-off devices driving an electrostrictive ultrasonic transducer system and its optimum control technique, which is implemented by feed-back of the ultrasonic transducer applied voltage and instantaneous velocity of the transducer vibrating system through a Phase-Locked-Loop control scheme. The feedback voltage corresponding to instantaneous velocity is averaged over a half-period with respect to constant amplitude/constant velocity control strategy. Described are the theory of this signal detection technique and the experimental set-up.

• Journal of Information Technology Applications and Management
• /
• v.31 no.1
• /
• pp.139-161
• /
• 2024

The Fourth Industrial Revolution has spurred widespread adoption of AI-based services, driving global interest in AI semiconductors for efficient large-scale computation. Text mining research, historically using LDA, has evolved with machine learning integration, exemplified by the 2021 BERTopic technology. This study employs BERTopic to analyze AI semiconductor-related patents and research data, generating 48 topics from 2,256 patents and 40 topics from 1,112 publications. While providing valuable insights into technology trends, the study acknowledges limitations in taking a macro approach to the entire AI semiconductor industry. Future research may explore specific technologies for more nuanced insights as the industry matures.

• The Journal of the Convergence on Culture Technology
• /
• v.4 no.3
• /
• pp.235-240
• /
• 2018

ICT converged smart factory started from German Industry 4.0 has been the driving force for the $4^{th}$ Industrial Revolution and the center of manufacturing innovation for major industrial countries. It will be developed according to industry characteristics of each country. Korea is relatively later than other competing countries in the smart factory area. So, the government is establishing related policy and tendering all sorts of supports for smart factory mainly to the small and medium-sized enterprises to spread over the manufacturing industry. It is necessary for government to categorize among similar manufacturing industry and make them share digitalized production information mutually. It will be more effective method for securing global competitiveness than the uniform support. Also, large companies need to establish cloud based production forecasting system over similar industry and share it with other companies rather than expansion of individual smart factory. Mutual development in the manufacturing industry will be realized when the small and medium-sized enterprises and large companies take part in the cooperating ground of smart factory.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1565-1576
• /
• 2002

By way of driving a 2-way on/off solenoid hydraulic valve with a pulse width modulation (PWM) signal, control of the pressure in a certain volume is frequently used in various applications. However, the pressure built-up according to the duty ratio and carrier frequency of the PWM signal is not so well understood. In order to clarify the characteristics of 2-way valve hydraulic pressure control systems, in this paper two formula fur the mean and ripple of the load pressure were derived through theoretical analysis. And the accuracy of the derived formula were verified by comparison with the experimental test result. Generally 2-way valve systems are constructed as a bleed-off circuit, while 3-way valves are used as a control element in a meter-in circuit pressure control system. In a bleed-off circuit, the system supply pressure from a hydraulic power pack does not remain constant, but changes according to their external load. In turn, the relief valve in the hydraulic power pack reacts accordingly showing complicated dynamic behavior, which makes an analytical study difficult. In order to resolve the problem, simple but accurate empirical dynamic models fer a bleed-off system were used in the course of formula derivation. As the result, selection criteria for two major control parameters of the driving signal is established and the basic strategy to suppress the unnecessary pressure fluctuation can be provided for a hydraulic pressure control system using a 2-way on/off solenoid valve.

• Journal of Korea Game Society
• /
• v.15 no.2
• /
• pp.95-104
• /
• 2015

Many games for English vocabulary learning, such as hangman, cross puzzle, matching, etc, have been developed which are of board-type or computer game-type. Most of these computer games are adapting strategy-style game plays so that there is a limit on giving the fun, a nature of games, to learners who do not like games of this style. In this paper, a system for memorizing new English words is proposed which is based on a single-player car racing game targeting youths and adults. In the game, the core of our system, a learner drives a car and obtains game points by colliding with English word texts like game items appearing on the track. The learner keeps on viewing English words being exposed on the track while driving, resulting in memorizing those words according to a learning principle stating viewing is memorization. To our experiment, the effect of memorizing English words by our car racing game is good, and the degree of satisfaction with our system as a English vocabulary learning tool is reasonably high. Also, previous word games are suitable for the memory enforcement of English words but our game can be used for the memorization of new words.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.13 no.6
• /
• pp.420-429
• /
• 2008

This paper describes design procedure and control strategy of HDC(High side DC/DC Converter) and MCU(Motor Control Unit) for diesel hybrid electric vehicle. In designing HDC and MCU for HEV high power density and reliability is strongly needed to meet the demand of automotive industry. In order to achieve the high performance of a controller, MPC5554 based control board is developed. An optimized film capacitor and inductor are also developed for high efficiency driving. Skim 63 IGBT module of SEMIKRON for automotive is used for power switching device. The most efficient cooling model for optimal size and reliability were verified by simulation. These procedures are verified by bench or driving test and the results are present in this paper.

• Journal of Digital Convergence
• /
• v.18 no.10
• /
• pp.239-252
• /
• 2020

By using text mining, we explore the factors responsible for an increase in SUV preference. We collected 32,679 posts related to SUVs from "Bobaedream," the largest online automobile community in South Korea, and applied the LDA topic model. While previous studies have explained the SUV boom as an individual's risk aversion strategy from crime, the result shows that the topic of 'Safety' appears to be an important factor in the SUV discourse in the context of a car accident and high-speed driving situation. To conclude, the consumption of SUVs in Korean society serves as a mean to prevent anxiety and danger to individuals when driving. We insist that decreasing social trust, caused by an increase in inequality, underlies the perception of risk on the road.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.4
• /
• pp.653-658
• /
• 2021

Convergence of ICT technology and various industry have been proliferated. It makes human life affluent pulling existing industry paradigm down while they do not realize. Also, it impacts on personal life and becomes a driving force which strengthen the state level and its competitiveness. Complexity is increasing, knowledge is expanding and ICT technology is evolving in the present industrial society. Thus, new business model is being created, established business without competitiveness is eliminated and new ecosystem is constructed for industry change or creation. The new business and its competitive order driving in current convergence environment is apt to be exposed to uncertainty risk. These changes promote the collapse of existing industry or create new business models. There are digital transformation and ICT convergence in the center of the changes. The change of society and industry caused by this phenomenon will be analyzed. Also, development direction, strategy and execution method for securing industry competitiveness of ICT convergence will be researched.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.73-80
• /
• 2005

This paper addresses a newly proposed start-up method of the HAUSAT-2 momentum wheel. The HAUSAT-2 is a 25kg class nanosatellite which is stabilized to earth pointing by 3-axis active control method. A momentum wheel performs two functions. It provides a pitch-axis momentum bias while measuring satellite pitch and roll attitude. Pitch control is accomplished in the conventional way by driving a momentum wheel in response to pitch attitude errors. Precession control and nutation damping are provided by driving the pitch axis magnetic torquer. A momentum wheel is nominally spinning at a particular rate and changes speed. This simulation study investigates the feasibility and performance of a proposed strategy for starting-up the wheel. A proposed strategy to start-up the wheel shows that a pitch momentum wheel can be successfully started-up to its nominal speed from rest and be stabilized to nadir pointing.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.3
• /
• pp.30-41
• /
• 2022

With the advent of autonomous driving, personal mobility, drones, and smart roads, it is necessary to respond to changes in the road traffic environment in the road guidance system. However, the use of road signs to guide the road is decreasing compared to the past due to the advent of devices such as navigation and smartphones. Therefore, in this study, a large-scale survey was conducted to derive road sign issues and usage plans to respond to future changes. Based on this, this study presented a strategy to diversify road sign functions by analyzing the factors affecting the use of road signs by citizens. As a result, first, it is necessary to provide real-time variable road guidance information that reflects user needs such as traffic, weather, and local events. Second, it is necessary to informatize digital road signs such as reflecting maps with precision. Third, it is necessary to demonstrate road guidance in a virtual environment that reflects various future mobility and road environments.