• Proceedings of the KIEE Conference
• /
• 1989.07a
• /
• pp.522-526
• /
• 1989

Recently developments of high-speed Semi-conductor Switches as Power MOSFETS, Power IGBT, power SIT have enwidened the performance of classical inverter configuration, and also allowed the practical applications of new inverter configuration, with improved performance and wider operating zones. Static power converters are now used in a great variety of applications including induction heating, high-frequency generation, DC/DC power converter, etc.

• Journal of the Korean Ceramic Society
• /
• v.47 no.1
• /
• pp.47-53
• /
• 2010

Ceramics with perovskite-type structure are interesting functional materials for several energy conversion processes due to their flexible structure and a variety of properties. Prominent examples are electrode materials in fuel cells and batteries, thermoelectric converters, piezoelectrics, and photocatalysts. The very attractive physical-chemical properties of perovskite-type phases can be modified in a controlled way by changing the composition and crystallographic structure in tailor-made soft chemistry synthesis processes. Improved thermoelectric materials such as cobaltates with p-type conductivity and n-type manganates are developed by following theoretical predictions and tested to be applied in oxidic thermoelectric converters.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.87-88
• /
• 2010

The strength and ductile capacity of reinforced concrete column can be improved by confinement using transverse reinforcement. Variety stress-strain models about the reinforced concrete confined by transverse reinforcement has been proposed. In this paper, parameters which effect to the ultimate confinement stress of circular cylinder confined by high strength transverse steel is examined. And the possion's ratio equation is proposed by analysis of strain between concrete and transverse reinforcement.

• International Journal of Aeronautical and Space Sciences
• /
• v.8 no.1
• /
• pp.122-128
• /
• 2007

In this paper, a method of station keeping strategy using relative orbital motion and numerical optimization technique is presented for geostationary satellite. Relative position vector with respect to an ideal geostationary orbit is generated using high precision orbit propagation, and compressed in terms of polynomial and trigonometric function. Then, this relative orbit model is combined with optimization scheme to propose a very efficient and flexible method of station keeping planning. Proper selection of objective and constraint functions for optimization can yield a variety of station keeping methods improved over the classical ones. Nonlinear simulation results have been shown to support such concept.

• Korean Journal of Biological Psychiatry
• /
• v.23 no.3
• /
• pp.89-101
• /
• 2016

Transcranial magnetic stimulation (TMS) is a safe, noninvasive and useful technique for exploring brain function. Especially, for the study of cognition, the technique can modulate a cognitive performance if the targeted area is engaged, because TMS has an effect on cortical network. The effect of TMS can vary depending on the frequency, intensity, and timing of stimulation. In this paper, we review the studies with TMS targeting various regions for evaluation of cognitive function. Cognitive functions, such as attention, working memory, semantic decision, discrimination and social cognition can be improved or deteriorated according to TMS stimulation protocols. Furthermore, potential therapeutic applications of TMS, including therapy in a variety of illness and research into cortical localization, are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.5 no.1
• /
• pp.113-122
• /
• 1985

Although PERT/CPM has been used for over twenty years as a technique for scheduling in a variety of industries and various extention to the basic model have been improved the realism of considering resource constraints, none of these techniqueis have integrated resource acquistion load times and inventory records into scheduling technique. This paper is to designed to over-come basic shortcoming of previous CPM into incorperate with MRP technique.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1996.04a
• /
• pp.389-394
• /
• 1996

The product-user interface for consumer electronic products became complex due to the increased variety of functions corresponding to consumer needs. In this study, three types fo design improvement of the menu interface for a video cassette recorder is studied. Three modifications to an existing menu interface was designed using the semantic, the syntactic and the lexical design factors. A series of the validation experiments was performed to test the effect of the three types of task modifications. The results showed that performance time, number of errors and learning effect were improved for all task modification. It also showed that the performance improvement effect of the semantic factors was 8.8%, that of the syntactic factors was 5.9% and that of the lexical factors was 5.6% respectively. It was found out that the performance improvement effect of the semantic design factors were relatively more significant than the syntactic and the lexical design factors.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.8 s.173
• /
• pp.64-70
• /
• 2005

The development of an accurate and energy saving pneumatic regulator that may be applied to a variety of practical pressure control applications is described in this paper. A novel modified pulse width modulation(MPWM) valve pulsing algorithm allows the pneumatic regulator to become energy saying system. A comparison between the system response of conventional PWM algorithm and that of the modified PWM(MPWM) algorithm shows that control performance is almost the same, but energy saving is greatly improved by adopting this new MPWM algorithm. The effectiveness of the proposed control algorithm are demonstrated through experiments with various reference trajectories.

• Journal of the Korea Furniture Society
• /
• v.26 no.4
• /
• pp.398-408
• /
• 2015

Though the physical environment of life through technological evolution has rapidly improved, the quality of life due to a variety of undesirable environmental issues has been seriously damaging. This study has tried to suggest the positive & sustainable direction of space design which can contribute to improving the quality of human lives by reviving 'place property' which a site itself has, trying to analyze the recycling space which the sustainability has been applied to in a true sense. For this cause, we've tried to draw four 'methods of realizing place property' such as meeting a site, understanding a site, finding the identity of a site, and adding novelty to a site through advanced research. I've tried to suggest the design direction for reviving space which can relieve the artificial aspect of design with pursuing the co-existence with nature on the foundation of realizing 'place property' through case analysis selected on the basis of this, and can express the 'sustainability' through environment-friendly space structures & high efficiency of its function.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.7
• /
• pp.37-44
• /
• 1997

A dadaptive refinement tetrahedron mesh has been presented for using in full band GaAs monte carlo simulation. A uniform tetrahedron mesh is used without regard to energy values and energy variety in case of the past full band simulation. For the uniform tetrahedron mesh, a fine tetrahedron is demanded for keeping up accuracy of calculation in the low energy region such as .GAMMA.-valley, but calculation time is vast due to usin gthe same tetrahedron in the high energy region. The mesh of this study, thererfore, is consisted of the fine mesh in the low energy and large variable energy region and rough mesh n the high energy. The density of states (DOS) calculated with this mesh is compared with the one of the uniform mesh. The DOS of this mesh is improved th efive times or so in root mean square error and the ten times in the correlation coefficient than the one of a uniform mesh. This refinement mesh, therefore, can be used a sthe basic mesh for the full band GaAs monte carlo simulation.