• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.7
• /
• pp.46-53
• /
• 2007

Micro-grid consists of micro-sources which adopt environmentally friendly and reliable power sources such as Fuel-Cell and Micro-Turbines with independent real and reactive power control capability for providing premium power quality. This paper deals with the basic aspect of dynamic modeling and the stability analysis of the micro-grid system. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system Stability analysis is performed based on the linearized dynamic model of the micro-grid system Case study results show the parameters affecting the stability of the micro-grid.

• Journal of Korean Society for Quality Management
• /
• v.47 no.3
• /
• pp.641-659
• /
• 2019

Purpose: Recently, the managing customer complaints properly has emerged as key source of competitive advantage in the large distribution industry. Effective customer complaint management helps firms minimize service failures and incense the capability to respond to customer's needs. Despite this importance, the in-depth prior study of a firm's service failures is very limited. Therefore, the actual service failure cases of large discount stores in Korea were analyzed in this study, and the types of service failures that occur at the service interface were identified. Method: Specifically, a total of 48,307 cases of customer complaints that have occurred in the past three years were collected from 1 January 2016 to 31 December 2018. Using 7 dimensions of service marketing mix. we have classified and analyzed systematically the service failure cases collected. Results: Among the cases of service failures, 34,921 (72.3%) cases were involved with the product factor, followed by 6,152 (12.7%) cases with person factor and 5,392 (11.2%) cases with process factor. Conclusion: By linking the main causes of service failure with the service marketing mix variables, this research presented a more systematic analytic model and verified by applying it to large domestic distribution company. Understanding the main factors affecting customer complaints n the large distribution industry can provide managers useful information and insight who want to achieve an effective customer complaint management.

• Proceedings of the KIPE Conference
• /
• 2018.11a
• /
• pp.86-88
• /
• 2018

The three level(3L) neutral point clamped (NPC) voltage source converter (VSC) topology is widely used for grid interface in high power wind energy due to its superior performance as compared to the two level(2L) VS. However, one of the major drawbacks of this topology is the unequal dispersion of loss and therefore the junction temperature among the power devices. The 3L ANPC topology derived from the NPC topology was proposed to resolve this drawback of unequal loss profile of 3L NPC. The 3L ANPC can work under various switching strategies. In this paper a comparative study of the various switching strategies of 3L ANPC using the recently developed 10kV IGCTs which has the capability to raise the current and voltage rating of the wind turbines is carried out. The comparison is performed using ABB make 10kV IGCT 5SHY17L9000 and PLECs simulations.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.9
• /
• pp.2980-2993
• /
• 2000

In order to achieve the rapid deployment of services. B-ISON network is being combined with terrestrial ATM and satellite network. Cell delay variation (CDV) generated by the difference of transfer mode between TOMA and ATM deteriorates transmission quality of the network system. We proposed the Partial Timestamps algorithm to supplement the problems of existing COV compensation methods. To minimize CDV and to utilize the satellite channels efficiently. only the optimized timestamps of a few cells within a control unit time of TDMA are selected and transmitted to the receiving earth station. The COV compensating efficiency of Partial Timestamps is evaluated by simulation. It is confirmed that CDV compensation capability of the proposed mechanism is superior to the other methods.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.3
• /
• pp.155-160
• /
• 2011

IPTV functions not only as media player that does play the broadcasting industry's contents, also as the gateway is guaranteed of QoS(Quality of Service). This is for free contents-sharing that device stores contents using home network circumstance, and is for watching with seamless network service. Also this have required next QoS model that can handle stably as it may contain more data of the small computing device in next generation home system. We need ubiquitous-oriented QoS's design and development project that focuses on internal and external media service, not the existing QoS nor one-sided QoS of media sevice industry. This paper focuses on network module development. This supports IPTV in media industry and two-way capability of QoS highlighting multimedia service in network industry. In additional, this can handle stably the multiplex signal of USN/RFID as the representative ubiquitous and home network that services high-speed wire and wireless interface, and support the seamless u-QoS.

• Journal of the Korea Computer Industry Society
• /
• v.7 no.4
• /
• pp.421-426
• /
• 2006

Because the 3-Tier structure cia share a business logic, the reuse of existing code could be guaranteed Al so tiny and little client application in charge of user interface can he made that it doesn't need plenty of client memory and calculation capability. Catering system that capable of meal material code management autom atic production of requiring quantity, purchase and shipping management menu management, account management was developed for grafting 3-Tire structure technology using database language and ADO(ActiveX Dat a Object). This system improved production in field of school lunch program and saved o(poises. finally, this system is suitable to the service environment of school lunch program and lots of utilizations would be anticipated.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.43 no.4 s.346
• /
• pp.31-37
• /
• 2006

Strongly motivated by the need for significant reduction in the optics-to-antenna interface circuitry used in a Photonically controlled array, it has proposed the design development of a novel 'true photonic antenna' consisted of optical fiber and micro-strip antenna. To clarify the design capability of the geometry, modal transmission-line theory including the discontinuity property between circular i,nd planar guiding structures is defined, md the optical power coupling of a slot-coupled microstrip antenna directly fed from an optical fiber using photoconductive effect is evaluated numerically. The numerical results reveal that the maximum power transfer between the two different guiding structures occurs at a new point in which the guiding powers of two rigorous modes are equally partitioned.

• Journal of Magnetics
• /
• v.16 no.3
• /
• pp.246-252
• /
• 2011

A high-voltage power supply has been built for activation of the brain via stimulation using a Full Wave Cockroft-Walton Circuit (FWCW). A resonant half-bridge inverter was applied (with half plus/half minus DC voltage) through a bidirectional power transistor to a magnetic stimulation device with the capability of producing a variety of pulse forms. The energy obtained from the previous stage runs the transformer and FW-CW, and the current pulse coming from the pulse-forming circuit is transmitted to a stimulation coil device. In addition, the residual energy in each circuit will again generate stimulation pulses through the transformer. In particular, the bidirectional device modifies the control mode of the stimulation coil to which the current that exceeds the rated current is applied, consequently controlling the output voltage as a constant current mode. Since a serial resonant half-bridge has less switching loss and is able to reduce parasitic capacitance, a device, which can simultaneously change the charging voltage of the energy-storage condenser and the pulse repetition rate, could be implemented. Image processing of the brain activity was implemented using a graphical user interface (GUI) through a data mining technique (data mining) after measuring the vital signs separated from the frequencies of EEG and ECG spectra obtained from the pulse stimulation using a 90S8535 chip (AMTEL Corporation).

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.228.1-228.1
• /
• 2012

Digital waveform generation technology for SAR payload can be divided into DDS(Direct Digital Synthesizer) method and Memory Mapped(M/M) method. DDS is the single chip which consists of the Sine Table, NCO(Numerically Controlled Oscillator), DAC, and so on. DDS method is a very simple method because the circuit configuration is not complex but has a disadvantage that can not control phase and amplitude easily by using NCO. M/M method has the complexity of the circuit configuration because it requires the memories which stores the waveforms, the control circuits, and DAC. And this method should apply the high interface technology for being compatible with the wide bandwidth of the digital signal and has the difficulty for PCB design because the number of the signal lines should be increased according to the number of the data bits for DAC. Although it has several disadvantages, this method has the capability of pre-distortion function which can compensate the phase and amplitude characteristics of the system and also has an excellent advantage to make any arbitrary waveform, so this method is considered as an important technology with DDS method. This research describes the technological trends of the waveform generator for the SAR payload and analyzes the characteristics of the technology.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.235-237
• /
• 2008

A unified hydrocode, ExLO, in which Largrangian, ALE and Eulerian solvers are incorporated into a single framework, has recently been developed in Korea. It is based on the three dimensional explicit finite element method and written in C++. ExLO is mainly designed for the calculation of structural responses to highly transient loading conditions, such as high-speed impacts, high-speed machining, high speed forming and explosions. In this paper the numerical schemes are described. Some improvements of the material interface and advection scheme are included. Details and issues of the momentum advection scheme are provided. In this paper the modeling capability of ExLO has been described for two extreme loading events; high-speed impacts and explosions. Numerical predictions are in good agreement with the existing experimental data. Specific applications of the code are discussed in a separate paper in this journal. Eventually ExLO will be providing an optimum simulation environment to engineering problems including the fluid-structure interaction problems, since it allows regions of a problem to be modeled with Lagrangian, ALE or Eulerian schemes in a single framework.