• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.61 no.2
• /
• pp.82-86
• /
• 2012

Recently, due to the expansion of electric power demands, nonlinear load such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electric devices, disturbance of the electric power system and its influences on industries have been continuously increasing. In this research, power quality was analyzed for 11 extra-high voltage customers by considering voltage unbalance condition, power factor, THD and TDD. This research will be utilized as fundamental data to improve power quality for power utility.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2003.05a
• /
• pp.369-388
• /
• 2003

This research has been focused upon and analyzing Medison, once a leading New Technology-Based Firm (NTBF) in Korea with exceptionally advanced technology in 3D ultrasound diagnostic imaging devices (UDIDs) (armored with 23 subsidiaries at its peak expansion), from the perspective if Dynamic Firm Capability(DFC). The underlying hypothesis is that the various problems from its pointless pursuit of the business styles or precedents of the existing large firms might be traced to its specific characteristics as an NTBF, which should have more preferably been based upon the distinctive competences such as differentiated technologies, institutional linkages, organizational routines, and complementary assets, etc. In conclusion, for the NTBFs with different DFC domains from those of the large firms, the optimal external linkages and comprehensive integration efforts (Process) under their specific organizational characteristics and constraints (Path) are highly recommended for the continuous accumulation of their core capabilities based upon the technological assets (Position).

• Proceedings of the Korea Society for Simulation Conference
• /
• 2001.10a
• /
• pp.209-214
• /
• 2001

Acoustic field in steady-state is characterized by a Helmholtz equation. The transmission characteristics of acoustic wave devices is however influenced by the presence of the mean flow in the medium. The effect of the mean How introduces additional terms in the equation. In the present paper, two approaches are considered. One is that the equation is directly discretized by FEM for one-dimensional and the axisymmetric case. Another is that the equation is first transformed into the standard Helmholtz equation which is solved by BEM. The numerical demonstrations are made for the axisymmetric FEM and the three-dimensional BEM modeling. The numerical examination for a straight circular duct is first considered. The solutions are compared wish the analytical ones. The examination is then extended to the case when the mean How is locally present in a muser with expansion chamber.

• Journal of Information Technology Applications and Management
• /
• v.22 no.2
• /
• pp.123-148
• /
• 2015

Today the mobile devices including smart phones have influenced on the users' daily activities in the mobile internet society, and the expansion of social media has also affected on the purchasing behavior of consumers. This study examines whether the quality of corporate twitter, a typical social network service for call centers influences on the customer satisfaction, and brand loyalty. In order to achieve the research goal, the quality of twitter has been divided into four variables; information quality, service quality, system quality, and social quality. The results of our empirical analysis show that the three variables except service quality have significantly influenced on the customer satisfaction and the customer satisfaction also significantly has a casual effect on the brand loyalty. The empirical results are expected as a guideline to contribute on the practical improvement of customer service, satisfaction, and brand loyalty through corporate social network services such as corporate twitters in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.156-159
• /
• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be fabricated as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible Suspended FBAR using surface micromachining. It is possible to make Si$_3$N$_4$/SiO$_2$/Si$_3$N$_4$membrane by using surface micromachining and its good effect is to remove the substrate silicon loss. FBAR was made on 2$\mu\textrm{m}$ multi-layered membrane using CVD process. According to our result, Fabricated film bulk acoustic wave resonator has two adventages. First, in the respect of device Process, our Process of the resonator using surface micromachining is very simple better than that of resonator using bull micromachining. Second, because of using the multiple layer, thermal expansion coefficient is compensated, so, the stress of thin film is reduced.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2628-2630
• /
• 2004

In this study, a system that has a high speed digital data I/O and distributive structure is developed and the hardware and software of the system are described in detail. PCI master card to PC slot has maximum 63 slaves which are connected by Ethernet cables and can handle 16 I/O points. The system has some features : easy expansion by adding slaves as needed, space and wiring advantage with distributed characteristics, and select from a range of slave devices that fits best for the use.

• Korean Institute of Interior Design Journal
• /
• no.33
• /
• pp.46-53
• /
• 2002

The development of data communication and network technology has brought a change to various communications through the internet. Regarding the stable internet service, corporations and Individuals came to require an internet data center in which there is computer equipment and network devices available 24 hours everyday. The internet data center is now on a large scale in its structure and facility, suitable for the internet environment that is under development in various dimensions, and effective for task support, stable facility, capable of space expansion and flexibility, and easiness in ease of maintenance and management, etc. The monitoring center of the data center which is one of the core facilities in the center, special space elements and functions as well as a function of task space are to be put into consideration additionally. This study was to present a proposal for the space elements and environmental design of a monitoring center, which could create an efficient and comfortable room.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1407-1412
• /
• 2003

In MEMS devices, packaging induced stress or stress induced structure deformation become increasing concerns since it directly affects the performance of the device. In this paper, deformation behavior of MEMS gyroscope package subjected to temparature change is investigated using high-sensitivity $Moir{\acute{e}}$ interferometry. Using the real-time $Moir{\acute{e}}$ setup, fringe patterns are recorded and analyzed at several temperatures. Temperature dependent analyses of warpages and extensions/contractions of the package are presented. Linear elastic behavior is documented in the temperature region of room temperature to $125^{\circ}C$. Analysis of the package reveals that global bending occurs due to the mismatch of thermal expansion coefficient between the chip, the molding compond and the PCB.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.269-274
• /
• 1998

This paper describes a scaled model for PWM thyristor current-source inverter with a commutation circuit. The system consists of a 6-pulse thyristor bridge and an LC resonant circuit with thyristor switches, which offers thyristors to have turn-off capability for PWM operation with minimal switching losses. The proposed system can be used as a reactive power compensator with PWM operation for the utilitity application. There would be two advantages in the proposed system over the existing voltage source inverter. One is the low system cost due to using the conventional thyristors. Another is easy expansion of system operation voltage because th series operation of thyristor devices is already proven in HVDC system.

• Journal of Sensor Science and Technology
• /
• v.16 no.4
• /
• pp.247-253
• /
• 2007

Low power consumption sensor network platform (sensor node) for sensor networking with IEEE 802.15.4 protocol was fabricated. The sensor node used ceramic bar type antenna for increasing RF signal performance and decreasing PCB size occupied by antenna. The communication range of the fabricated sensor node was about $20{\sim}30$ m in open environment with 915 MHz frequency bandwidth and well supported by Tiny OS. The sensor node have good connectivity with various external devices by RS-232, I2C, analogue and digital expansion board, hence, this sensor node can be applied to various applications in wireless sensor network and ubiquitous sensor network.