• Proceedings of the KIPE Conference
• /
• 2009.11a
• /
• pp.268-270
• /
• 2009

This paper proposes a simple starting method to arrange the rotor position of the blushless DC motor (BLDC) without additional sensors and any information of motor parameters. Both the stator current and time period for arranging the rotor position can be easily adjusted by modulating a pulse width of switching devices. Using the proposed method, it is demonstrated experimentally that the BLDC starts up very smoothly.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.5 no.4
• /
• pp.113-128
• /
• 2010

Moblie games are getting popular in that more mobile handsets are available. The mobile phone is expected to be the dominant platform the way the PC turned out to be the dominant platform of desktop computing. Ubiquity enables the mobile phone users interact socially with other users. Mobile game developers are now competing globally on the Apple Appstore, where any developers in the world are able to publish their own games easily. This study reviews the case of Gamevil, one of the leading mobile game service providers, from its foundation to the current global competition in order to draw implications for mobile game industry.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.10
• /
• pp.1858-1864
• /
• 2011

This paper suggests a control technique of the sensorless brushless DC (BLDC) motor drive for a vehicle fuel pump application. The sensorless technique based on a comparator and a potential start-up method with high starting torque are proposed. The comparator is used to generate the commutation signals in phase with the three-phase back-EMFs. The rotor position is aligned at standstill for maximum starting torque without an additional sensor and any information of motor parameters. Also, the stator current can be easily adjusted by modulating the pulse width of the switching devices during alignment. Some experiments are implemented on a single chip 16-bit DSP controller to demonstrate the feasibility of the sensorless techniques.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.1
• /
• pp.81-87
• /
• 2000

A variable cutting speed control model was developed to be implemented for the flexible disk grinding process Control algorithm was based on the error referred by the discrepancy between current disk angle and intended one that are pro-posed to produce desired resulting depth of cut. Controller was implemented in two different aspect One was to initiate the control law from the beginning while the other was to activate as soon as the disk start to produce ground surface i.e. The beginning of the between edges stage. Several performance analysis were conducted comparing various process parameters such as cutting force disk angle depth of cut and disk speed with respect to process transition time Tentative results revealed that controller implemented from the earlier stages of the process showed better performance than the other revealed that controller implemented from the earlier stages of the process showed better performance that the other.

• Archives of design research
• /
• v.19 no.3 s.65
• /
• pp.117-130
• /
• 2006

This paper analyzed the current status of universal design in the Republic of Korea (Korea) and Japan. In the case of Japan, the aged society or the super aged society has been preparing from 1985 when the aging rate was 10%. Japan's activity to prepare it became promoted during 1990's when per capita Gross National Income (GNI) was $$20,000{\sim}40,000$. In Korea, the preparation for the aging society such as physical environment, barrier free buildings or traffic systems, economic support and investigation or survey is not yet sufficient. Korea must start preparation for an aged society, possibly and quickly. And it needs to prepare until 2026, when the aging rate will be 20%. To prepare a barrier free and an aged society must consider both aging and economic status.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.563-567
• /
• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are 1~8L/min on $H_2$ volume and $20{\sim}70^{\circ}C$ on stack temperature.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.5 no.1
• /
• pp.32-37
• /
• 2009

The emergency diesel generator (EDG) in a nuclear power plant (NPP) shall start within 10 secondss and supply electrical power to engineered safety features within one minute and less if a loss of offsite power (LOOP), A design-basis event, or their combination occur. Each NPP has an EDG set consisting of two diesel generators for redundancy. In addition to the EDG set, an alternate Alternating Current Diesel Generator (AAC DG) is installed and shared by several units to cope with a station black out (SBO), i.e., loss of the offsite power concurrent with reactor trip and unavailability of the EDG set. The objective of this study is to analyze the failure data of emergency diesel generators reported in overseas nuclear power plants.

• Journal of Korea Technology Innovation Society
• /
• v.9 no.3
• /
• pp.471-495
• /
• 2006

This paper reviews the distribution patterns of research equipments in Korea. We start, however, discussion with the introduction to research equipments, theoretical issues and rationale for government intervention. Nation-wide distribution of research equipments is shown by region, type of institution, university, and major equipment. Old patterns are derived from the history of equipping science, and three new current patterns are introduced. Based on this discussion, we recommend policies for research equipments.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.646-650
• /
• 2004

This paper presents a novel method to detect the rotor position of the BrushLess DC(BLDC) motor at standstill and a start-up method to accelerate the rotor up to a certain speed where the conventional position sensorless control methods based on the back EMF could work reasonably The proposed initial rotor position estimation method is suitable to avoid the temporary reverse rotation or the starting failure. This method can be implemented using only one current sensor at DC link of the inverter. It does not depend on the model of the motor , and it is robust to motor parameter variations. By the proposed method, it is demonstrated experimentally that a stable starting can be achieved even with severe mechanical disturbance.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.523-525
• /
• 2008

Novel zero-voltage switching(ZVS) dual inductor-fed DC-DC converter integrating a conventional dual inductor-fed boost converter(DIFBC) and a parallel bidirectional boost converter has been proposed. Most of current-fed type boost topologies including dual inductor schemes have crucial defects such as a high voltage spike on the main switch when it comes to turning off, an unattainable soft start-up due to the limited range of duty ratio, above 50%, and considerable switching losses due to the hard switching. By adding two auxiliary switches and an output capacitor on the conventional DIFBC, the proposed circuit can solve mentioned problems and improve the efficiency with simple methods. The operational principle and theoretical analysis of the proposed converter have been included. Experimental results based on a 42V input, 400V/1A output and 50kHz prototype are shown to verify the proposed scheme.