• Archives of design research
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• v.13 no.3
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• pp.201-210
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• 2000

A current of culture changes constantly. The changes in culture have been taken the lead in by new generations. Now, we are connected with a new trend of culture led by new generation. Moreover, it is the younger class from teens to mid-twenties, that is, the new generation group that plays a major part in the new culture. They, in economic affluence, are accustomed to a particular consumption-oriented purchasing pattern in their own way while the old generations had to tighten their belts. A business cannot help getting fascinated with their potential consuming power. The new generation has established itself as a powerful individual consumer class, and is presenting more and more explosive and destructive purchasing pattern in today's consumption market where turmoil of IMF is at the end and 21st century started. As of now, it cannot be emphasized too much to research their consuming culture and tendency. It is suggested that existing designers work out a marketing strategy based on a close investigation of their disposition and cultural characteristics and go on looking into what the properties of a new coming generation's culture vary every time generations change in order to take them to a future consumer group.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2971-2978
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• 2013

Recently, with the world-wide issues about global warming and CO2 reduction, a number of distributed generations(DGs) such as photovoltaic(PV) and wind power(WP), are interconnected with the distribution systems. However, DGs can change the direction of the power flow from one-direction to bi-direction, and also change the direction and amount of fault current of existing distribution systems. Therefore, it may cause the critical problems on the power quality and protection coordination. This paper proposes an operation algorithm for bi-directional protection coordination using and apply it for the evaluation system for protection coordination. From the simulation results It is found that the proposed method is more effective and convenient than existing method.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.2
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• pp.67-72
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• 2015

Power grid techniques are distributed over general power systems ranging from power stations to power transmission, power distribution, and users. To monitor and control the elements and performance of a power system in real time in the extensive area of power generation, power transmission, wide-area monitoring (WAM) and control techniques are required (Sattinger et al. 2007). Also, to efficiently operate a power grid, integrated techniques of information and communication technology are required for the application of communication network and relevant equipment, computing, and system control software. WAM should make a precise power grid measurement of more than once per cycle by time synchronization using GPS. By collecting the measurement values of a power grid from substations located at faraway regions through remote communication, the current status of the entire power grid system can be examined. However, for GPS that is used in general national industries, unexpected dangerous situations have occurred due to its deterioration and jamming. Currently, the power grid is based on a synchronization system using GPS. Thus, interruption of the time synchronization system of the power system due to the failure or abnormal condition of GPS would have enormous effects on each field such as economy, security, and the lives of the public due to the destruction of the synchronization system of the national power grid. Developed countries have an emergency substitute system in preparation for this abnormal situation of GPS. Therefore, in Korea, a system that is used to prepare for the interruption of GPS reception should also be established on a long-term basis; but prior to this, it is required that an evaluation technique for the time synchronization performance of a GPS receiver using an atomic clock within the power grid. In this study, a monitoring system of time synchronization based on GPS at a power grid was implemented, and the results were presented.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.3910-3917
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• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.414-417
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• 2001

SRG (Switched Reluctance Generator) have many advantages such as high efficiency, low cost, high-speed capability and robustness compared with characteristics of other machines. However, the control methods that have been adopted for SRGs are complicated. This paper proposes a simple control method using PID controller that only controls turn-off angles while keeping turn-on angles of SRG constant. The linear characteristics between the generated current and the turn-off angle can be used to control the turn-off angle for load variations. Since the reference current for generation can be produced from an error between the reference and the real voltage, it can be controlled to keep the output voltage constant. The proposed control method enhances the robustness of this system and simplifies the hardware and software by using only the voltage and speed sensors. The proposed method is verified by experimental results.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.333_335
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• 2009

It is expected, in the near future, that the use of distributed generation systems should be increased considerably. In this case, distance relay algorithm should be developed in the manner that it can reduce the error due to the in-feed effect. This paper presents a method to consider the fault current rushed from the remote end of a line. In the steady-state, the relays in both ends exchange the voltages of upper nodes. If a fault is perceived, the relay calculates fault location taking the fault current from the remote end by using voltage data of the remote ends obtained just before the fault. Even though this method has inevitable error, it can show more precise fault allocation. The suggested method is applied to a typical transmission system with two power sources in both ends to verify its effectiveness.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.578-579
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• 2005

HVDC(High Voltage Direct Current) is an underwater cable between Jeju Island and Haenam in main land and supplies approximately 50% of electrical usage in Jeju Island. If there is any power failure due to HVDC, it will cost approximately 50,000 US dollars per day including Thermal Electrical Generation. Therefore it is absolutely necessary to recover the problem in rapid timely basis. In conclusion, new method and new systems(ULTRA #44 Model) are needed urgently to upgrade current HVDC underwater cable survey technique in Korea to minimize the cost and time factors.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.180-184
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• 1998

Recently the performance of CO2 arc welding machine has been advanced significantly through the adoption of inverter circuit topology which made it possible to control the waveform of welding current and thus to suppress the spatter generation. However, the optimum waveform is still uncertain. As a first step for figuring out the promising waveforms, this study was performed to set-up the experimental system for studying the effect of waveform variables. The overal system is controlled digital controller using single chip microprocessor of 80C196KC. As a result of performance test of this system, it was demonstrated all of the waveform variables could be set individually and the generated spatter is reduced compare to conventional inverter arc welding machine.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.247-253
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• 2014

In this paper, a new two dimensional (2D) analytical modeling and simulation for a Dual Material Double Gate tunnel field effect transistor (DMDG TFET) is proposed. The Parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions and analytical expressions for surface potential and electric field are derived. This electric field distribution is further used to calculate the tunnelling generation rate and thus we numerically extract the tunnelling current. The results show a significant improvement in on-current characteristics while short channel effects are greatly reduced. Effectiveness of the proposed model has been confirmed by comparing the analytical results with the TCAD simulation results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.11
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• pp.1219-1226
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• 1990

This paper is to report the results on the design and construction of a thermal plasma generator with high current DC source. Also, this paper presents the methods to stabilize plasma and to find effects of process variables on plasma characteristics. For this purpose, the reaction chamber, vacuum system, plasma generating torch, magnetic field generating coil with power supply, high current DC source and the other parts have been designed. Fundamental properties of the thermal plasma under various conditions have been measured and analyzed. Magnetic Reynolds Number has been introduced to explain the relationship between plasma and external magnetic field. Through this number, the effect of magnetic field on the plasma has been explained under various flow rates and pressure. A sudden increase in the plasma voltage has been observed with the increase of magnetic field. From this, fundamental changes in plasma flow are believed to occur at the nozzle, and an effort to explain the phenomenon has been tried.