• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.542-545
• /
• 2005

This paper is concerned wi th the generation of the Lamb waves in a non­ferromagnetic plate by a recently-developed orientation-adjustable patch-type magnetostrictive transducer (OPMT) and the dispersion analysis from the measured Lamb waves. OPMT is capable of adjusting wave-propagation orientation only with a single installation on a plate. The mechanics behind the wave generation and measurement by the magnetostrictive phenomenon, the working principle of OPMT is explained and the actual generation and measurement of the Lamb waves were conducted in a 3 mm-thick aluminum plate. For the accurate analysis of the dispersion characteristics of the measured Lamb waves, a modified version of the short-time Fourier transform, known as the dispersion-based short-time Fourier transform, was employed. The results presented in this work would serve as the underlying research for an advanced non-destructive evaluation based on ultrasonic waves.

• Journal of Welding and Joining
• /
• v.8 no.1
• /
• pp.31-42
• /
• 1990

Arc must be stable during welding first of all other factors for obtaining sound weldment, especially in the automation of welding process. Arc stability is somewhat sophisticated phenomenon which is not clearly defined yet. In consumable electrode welding, the voltage and current variation due to metal transfer enables to assess arc stability. Recently, statistical analyses of the voltage and current waveform factors are performed to assess the degress of arc stability which is assessed and controlled by operator's own experience by now. But, considering the increasing need and the trend of automation of welding process, it is necessary to monitor arc stability in real-time. In this sutdy, the modified stability index composed of two voltage and current wvaeform factors (arc time and short circuit time) reduced from four factors (arc time, short circuit time, average arc current and average short circuit current) in Mita's index by the welding electrical circuit modeling is proposed and verified by experiments to be well estimating arc stability in the static sense. Also, the recursive calculation form estimating present arc stability in the dynamic sense is developed for real-time estimation. The results of applying the recursive index during welding show good estimation of arc stability in real-time. Therefore, the results of this study offers the mean for real-time control arc stability.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.2100-2101
• /
• 2008

This paper is studied on a protective control system for electrical fire and electrical faults due to over current or electric short circuit faults by using electrical thermal characteristics of PTC (Positive Temperature Coefficient) thermistor and current response characteristics of high sensitive reed switch. The PTC thermistor has characteristic of positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with BaTiO3_Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point, and reed switch, which is used for electrical fault current sensing devices, have a excellent characteristic of response velocity in degree of ${\mu}s{\sim}ms$ that sensing magnetic flux in proportion to dimension of line current. This paper is proposed on a protective control system use PTC thermistor and reed switch for sensor which is protected from electrical fire due to overload faults or electric short circuit faults. Some experimental results of the proposed electric safety control device are confirmed to the validity of the analytical results.

• Transactions on Electrical and Electronic Materials
• /
• v.8 no.4
• /
• pp.166-169
• /
• 2007

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive TN-LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by counting between on time and off time for video signal input during 1 frame (16.7 ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by CCFL blinking drive and TN-LCD overdriving. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.888-891
• /
• 2011

In this paper, drain induced barrier lowering(DIBL) has been analyzed as one of short channel effects occurred in double gate(DG) MOSFET. The DIBL is very important short channel effects as phenomenon that barrier height becomes lower since drain voltage influences on potential barrier of source in short channel. The analytical potential distribution of Poisson equation, validated in previous papers, has been used to analyze DIBL. Since Gaussian function been used as carrier distribution for solving Poisson's equation to obtain analytical solution of potential distribution, we expect our results using this model agree with experimental results. The change of DIBL has been investigated for device parameters such as channel thickness, oxide thickness and channel doping intensity.

• Journal of the Korean Society of Safety
• /
• v.28 no.4
• /
• pp.38-42
• /
• 2013

This study performed the quantitative distribution analysis of created voids to an insulator when applying general flame and DC short-circuit current to 2.5 $mm^2$ HIV (600 V Grade Heat-Resistant Polyvinyl Chloride Insulated Wires). The diameter of cross-section of HIV normal product and the radius of conductor were measured to be 3.3 mm and 1.8 mm. The exterior of HIV exposed to general flame showed severe carbonization and its interior exhibited voids created by dechlorination reaction. This study observed the characteristics that, when the shortcircuit current applied for 2 seconds from a DC 12 V lead battery, the conductor and neighboring insulator were melted, causing the insulator adhering to the conductor. On average, 87 voids were created on 10 mm of the HIV. The average diameter of voids was 0.25 mm. In addition, it was found that, when the short-circuit current applied for 4 seconds, the interior of insulator in contact with conductor severely carbonized and showed exfoliation phenomenon. On average, 47 voids were created, with more voids at the bottom. The average diameter of voids was 0.20 mm. When the short-circuit current for 6 seconds, most parts of upper part of conductor was carbonized, 20 voids were created. The average diameter of voids was measured to be 0.24 mm. It could be seen that the created voids received little influence by the type of energy source and the number of created voids was reduced as the energy supply time increased.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.4
• /
• pp.652-658
• /
• 2006

This paper deals with an electronic ballast for hish intensity short-arc discharge lamps, which consists of a boost converter, a step down converter operated as a current source with power regulation and a low frequency inverter with external ignition circuit The ignition circuit generates high voltage pulses of 130[Hz] up to 5 [kV]. A reignition circuit is equipped in the ballast, and it operates the lamp at a regular interval for protection when an ignition fails. Acoustic resonance phenomenon was eliminated by operating a low frequency square wave voltage and current. The measured lamp voltage, current and consumption power were 123.8 [V], 8.1 [A] and 1,002 [W], respectively. From the experiment, we confirmed that the prototype ballast operates the lamp with a constant power.

• The Journal of the Korea Contents Association
• /
• v.22 no.10
• /
• pp.642-657
• /
• 2022

The fourth industrial revolution became a decisive opportunity to increase our dependence on non-face-to-face services. Therefore, this study tried to derive a new strategic plan for non-face-to-face marketing by discussing the short-form branded content currently in the spotlight among the digital native generation. In particular, focusing on the phenomenon of co-viewing, where short-form branded content is viewed and communicated on social media, how exposure type of branded content affect attitudes toward short-form branded content and the products it contains verified. In addition, this research presents the perceived sense of belonging as a mediating variable. It was confirmed through an experiment whether the sense of belonging perceived by consumers during the co-viewing process significantly mediated the relationship between the exposure types and consumer attitudes. As a result of the study, it was found that the exposure type significantly affected the attitude towards the contents and the products contained in them. Furthermore, the perceived sense of belonging was also significant as a mediating variable.

• Journal of Distribution Science
• /
• v.18 no.3
• /
• pp.37-41
• /
• 2020

Purpose: The purpose of this paper is to examine the recent resurgence of popularism and the possible impacts it may have on contemporary business and economics. Research design, data and methodology: This is an exploratory case study that examines the rise of popularism and identifies and analyzes the likely implications for contemporary business and economics. Results: Although populists tend to reject elitism, capitalism, economic globalization, and political establishment, their ethnocentric behavior is no different from those of the corrupt political and economic elites. Popularism does enable nationalism and protectionism and negatively impacts business and economic growth. Conclusions: Popularism existed for a long time, and this phenomenon will continue to exist as long as a triggered mechanism exist, e.g., income inequality, resurgence of immigration, recession, insufficient factors of resources and social welfare. The recent rise of popularism is not a fad or a short-lived anti-establishment and anti-elitism movements but, rather, a force to be reckoned with in the near future. The rise of economic nationalism limits international trade, integration, and cooperation. As a result, international capital, service, and product flows will decline, and countries and multinational corporations have to develop and restructure their international supply and value chain to cope with this phenomenon.

• Proceedings of the Korea Database Society Conference
• /
• 2010.06a
• /
• pp.109-123
• /
• 2010

Compared to research on the success of IT projects In general, research on the management of conflict in IT teams and its impact on project success is insufficient. This research performed a comparative study to analyze the nature and evolving phenomenon of conflicts in IT project teams. This study aimed at; First, Why a conflict is created within and around an IT project team. Second, What is the phenomenon of conflict evolution, diffusion, and/or resolution? Third, How the differences in conflict management style affects the IT project performance? Three propositions were drawn from the analysis of two intensive analysis of conflict cases and their comparison. Proposition 1 : Both 'the method of pointing out a problem' and 'the pointed-out contents' can be the trigger of conflicts around an IT project. Proposition 2 : While the focus of attention of one party is 'the method of pointing out a problem', if the other's and focus of attention of one party is 'the pointed-out contents', that is, if the focus of attention mismatch, the conflict can be amplified. Proposition 3 : According to the temporal nature of the relationship, e.g., short-term versus long-term, the way people approach and deal with the conflict differs.