• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2207-2220
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• 2021

Lead alloy is used as coolant in Lead-based cooled Fast Reactor (LFR). The natural characteristics of lead alloy are combined with the simple structural design of LFR. This constitutes the inherent safety characteristics of LFR. The main work of this paper is to take the main coolant pump (MCP) in the lead-cooled fast reactor (LFR) as the research object, and to study the flow pattern distribution of the internal flow field under the reverse rotation pump condition, the reverse rotation positive-flow braking condition and the reverse rotation negative-flow braking condition. In this paper, the double-outlet volute type and the space guide vane are selected as the potential designs of the CLEAR-I MCP. In this paper, the CFD method is used to study the potential reverse accident of the MCP. It is found that the highest flow velocity in the impeller appears at the impeller outlet, and the Q-H curves of the two design programs basically coincide. The space guide vane type MCP has better hydraulic performance under the reverse rotation positive-flow condition, the Q-H curves of the two designs gradually separate with increasing flow rate, and the maximum flow velocity inside the space guide vane type MCP is obviously lower than that of the double-outlet volute type. For the reverse rotation test of MCP, only the condition of the forward rotating pump of the main coolant pump is tested and verified. For the simulation of the MCP in LBE medium, it proved that the turbulence model and basic settings selected in the simulation are reliable.

• Journal of the Korean institute of surface engineering
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• v.56 no.4
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• pp.227-232
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• 2023

In this study, complex admittance as a function of temperature and frequency was measured to analyze the important relaxation properties of lead scandium niobate, which is physically important, although it is not an environmentally friendly electrical and electronic material, including lead. Lead scandium niobate was synthesized by heat treating the solid oxide, and the conductance, susceptance and capacitance were measured as a function of temperature and frequency from the temperature dependence of the RLC circuit. The relaxation characteristics of lead scandium niobate were found to be affected by contributions such as grain size, grain boundary characteristics, space charge, and dipole arrangement. As the temperature rises, the maximum admittance and susceptance increase in one direction, but the resonance frequency decreases below the transition temperature but increases after the phase transition.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2687-2692
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• 2003

Recent advancement in information technology requires new interpretations for the space among human, machines and environment. Investigation of space between information and human could lead to the proper ways, in which human and machines meet. Various concepts regarding space have been explored in terms of “virtual reality in cyberspace” and “embodiment in tangible space.” “Mom (embodiment),” space, virtuality, sensation/perception, and interactive technology are some of the key ideas to be explored. Human “Mom” is such a fundamental membrane through which human can interact with the environment physically and mentally. An embodied interaction paradigm, based on “Mom,” is investigated. This leads to interactive technology paradigm. Sound space is an invisible but a tangible space in a sense that it travels in emotional tremors and stimulates new sensations and perceptions. Three cases are introduced to experiment such tangible space as a new and proper interactive paradigm. Also, a historical model of interaction is reviewed, which includes electrical, symbolic, textual, graphical, tangible, and social interaction.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.151-164
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• 2003

In this paper, induction motor drives with low switching acoustic noise based on the 2 phase modulated RLL(Random Lead-Lag) PWM is proposed and implemented. The proposed switching method is much bettor than 3 phase modulated RLL-PWM from the standpoint of the broadening effect of the acoustic noise spectrum. Along with the randomization of PWM Pulses, SVM(Space Vector Modulation) is executed in the TMS320C31 DSP(Digital Signal Processor). To verify the validity of the proposed RPWM(Random PWM), the experimental study was tried. The experimental results show that the performance of the proposed method and the 3 phase center-aligned SVM / conventional RLL-PWM are nearly the same from the viewpoint of the constant v/f centrel. But, in case of the proposed 2 phase modulated RLL-PWM, the spectrum characteristics of the voltage and the switching acoustic noise are shown to have better broadening effect than 3 phase modulated one.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.101-109
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• 2000

Mutual torque ripple in a brushless DC motor is the main source of acoustic noise, especially fur motor operation with high speed and torque. This paper presents a method to obtain mutual torque ripple to identify acoustic noise source. Mutual torque ripple can be determined by analyzing phase current shape and magnetic circuit with different lead angles. Current shape is determined by state space model of voltage equation with the use of inductance calculated by FEM, and confirmed by experimental results. Mutual torque ripple is also determined by FEM analysis for the calculated current shape. Acoustic noise experiment reveals that mutual torque ripple with different lead angle is one of the main sources for noise generation in a brushless DC motor.

• Korean Institute of Interior Design Journal
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• no.38
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• pp.258-265
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• 2003

The design of space, which focuses on human senses and perception, has become more prominent. It can be understood as the space needed for a field of experience. Phenomenological attitude focuses on the relations between human in the context of their environment. The experiences generated were used as a method of design. The method guides a formation of active space through phenomenological experience in interior space as well as architecture. To stimulate a phenomenological sensitive experience, the parameters for certain experiences were connected to the five senses, finally creating a concrete space. Water, light, air, vapor, and earth as architectural media are connected to the five senses and lead to intermediation from abstract to actual. In particular, water is deeply rooted in peoples subconsciousness and stimulates our instincts. Using water by effectively combining its symbols and physical characteristics will be a method to reinforce the experience with a given space. This study will examine the need for space experience and characteristics of water as an essential elements for perception experience and present possible experimental design.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2001.05a
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• pp.100-105
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• 2001

The space in today's digital era is developing in a new direction with the changing paradigm, which is different from that in the analog era. The space that appeals to the advanced technology mobilizes all the five senses of the space user with the technical elements of the more variable fields and aesthetic productions, and creates an interactive environment by motivating the user's active participation through the digital media. The environmental device called digital media connects the function pace with living performance. Unlike in the analog space, the different sides of the digital media space create a human consciousness that corresponds to the realistic ambience, further contributing to the lively condition. For the main production technique in the digital medias performance-active space, there are electronic image production, changeable production, impromptu-active production, light and sound production, and total artistic production that lead to the progressive interaction between man and space.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.188-198
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• 2012

An improvement to the k-${\varepsilon}$ turbulence model is presented and is shown to lead to better agreement with data regarding supersonic base flows. The improvement was achieved by imposing a grid-independent realizability constraint in the Launder-Sharma k-${\varepsilon}$ model. The effects of compressibility were also examined. The numerical results show that the modified Launder-Sharma model leads to some improvement in the prediction of the velocity and turbulent kinetic energy profiles. Compressibility corrections also lead to better agreement in both the turbulent kinetic energy and the Reynolds stress profiles with the experimental data.

• Advances in materials Research
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• v.2 no.3
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• pp.173-180
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• 2013

Lead-free complex perovskite ceramics $NaMeO_3$ ($Me{\equiv}Nb$, Ta) were synthesized using conventional solid state reaction technique and characterized by structural, FTIR and electrical (dielectric and ac conductivity) studies. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of single-phase orthorhombic structure with the space group Pmmm (47). Dielectric studies showed the diffuse phase transition at $394^{\circ}C$ for $NaNbO_3$ and $430^{\circ}C$ for $NaTaO_3$. Ac conductivity in both the compounds follows Jonscher's power law.

• Journal of Korea Multimedia Society
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• v.22 no.6
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• pp.729-737
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• 2019

This study defined the animation space as the concept of map based on the space of Joseph Campbell's heroic narrative. The space in which the animated character exists is an image symbolic language that reflects the inner and outer growth stages of the hero. I focused on the spatiality that plays the role of the power to lead the narrative and examined the meaning as the mediator that leads the heroic narrative. First, 6 spatial variables were derived by observing 'Hero's Journey 'which is used as a basis of US commercial animation scenario. Second, spatial variables are defined as 64 zones and proposed as 'Spatial Map Model of the Hero's Journey' (SMMH). Third, the character space of was applied to 'SMMH', and the change of space utilization rate and spatiality and the narrative meaning were analyzed. This study extended the narrative of animation space which was not actively studied to map concept. It is possible to provide a different viewpoint in animation production and research.