• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.847-849
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• 2009

Usually, after the decisions of the performance and range in the commercial vehicle, it is designed the ratings of the electric and mechanical elements for the vehicles. In this paper, the given performance and driving conditions, which are the maximum velocity, mileage, total weight of the normal gasoline scooter, battery type and size, and so on, are analysed for the design of the electric scooter. The maximum rotational speed and needed torque values of the electric motor which is substituted for the gasoline engine are calculated. These values can help to calculate the rating of the electric motor. In the calculation to obtain the torque and speed values, battery discharge and the running resistances are considered. We can decide the electric motor current value from the torque and speed values. The electric motor current values, which are significant parameter to decide the motor type and dimensions and characteristics of the electric motor, are decided by numerical simulation by the above conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.1-8
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• 2000

For the purpose of a cost effective design of practical subsoni $c^ersonic ejector systems, an experiment was carried out using a superheated steam as a primary driving flow. The superheated steam jet was produced by several different kinds of subsonic and supersonic nozzles. The secondary flow of atmospheric air inside a plenum chamber was drawn into the primary steam jet. The vacuum performance of the plenum chamber was investigated for a wide range of the ejector operation pressure ratio. The result showed that the static pressure of the mixed flow at the ejector throat is only a function of the ejector operation pressure ratio, regardless of the primary nozzle type employed.ed.

• Journal of the Korea Safety Management & Science
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• v.14 no.4
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• pp.93-105
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• 2012

The purpose of this study was to investigate drivers' postures in different car pedal systems and skilled levels under fatigue. Twenty four subjects participated in this experiment. For three-dimensional analyses, six cameras (Proreflex MCU-240, Qualisys) were used to acquire raw data. The parameters were calculated and analyzed with Visual-3D. In conclusion, ROAs of two leg-pedal system were less than one leg pedal system by pattern analysis. Through statistical tests, skilled levels have effects on ROAs(X, Y, Z) of ankle joint at breaking a pedal and ROAs(Y, Z) of ankle joint at accelerating a pedal. Also, car pedal systems have effects on ROAs(Y, Z) of ankle joint, and ROA(Z) of knee joint at accelerating a pedal. In addition, skilled levels and car pedal systems (cross effects) have an effect on ROA(Z) of ankle joint. These findings suggested that we should improve a present single pedal system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.2042-2059
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• 2019

Digital shadow puppet has traditionally relied on expensive motion capture equipments and complex design. In this paper, a low-cost driven technique is presented, that captures human pose estimation data with simple camera from real scenarios, and use them to drive virtual Chinese shadow play in a 2.5D scene. We propose a special method for extracting human pose data for driving virtual Chinese shadow play, which is called 2.5D human pose estimation. Firstly, we use the 3D human pose estimation method to obtain the initial data. In the process of the following transformation, we treat the depth feature as an implicit feature, and map body joints to the range of constraints. We call the obtain pose data as 2.5D pose data. However, the 2.5D pose data can not better control the shadow puppet directly, due to the difference in motion pattern and composition structure between real pose and shadow puppet. To this end, the 2.5D pose data transformation is carried out in the implicit pose mapping space based on self-network and the final 2.5D pose expression data is produced for animating shadow puppets. Experimental results have demonstrated the effectiveness of our new method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.391-394
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• 2014

In this paper, we introduce a method of determining the absolute position of the rotor for the vector control of Hall sensor type multi-pole BLDC motor using the DSP(TMS320F28335), and implement an algorithm to complement the problems of the conventional method. The switching method of the inverter for providing desired sinusoidal current to each phase of a motor, we adopt Space-Vector pulse width modulation method. In order to increase the speed range, Field-Weakness control method are used. In order to verify the proposed algorithm, we compare the value of Iqe, Ide and phase currents with the values before compensated.

• Korean Journal of Materials Research
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• v.29 no.6
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• pp.343-348
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• 2019

Structural and mechanical effects of the dynamical precipitation in two copper-base alloys have been investigated over a wide range of deformation temperatures. Basing upon the information gained during the experiment, also some general conclusion may be formulated. A one concerns the nature of dynamic precipitation(DP). Under this term it is commonly understood decomposition of a supersaturated solid solution during plastic straining. The process may, however, proceed in two different ways. It may be a homogeneous one from the point of view of distribution and morphological aspect of particles or it may lead to substantial difference in shape, size and particles distribution. The effect is controlled by the mode of deformation. Hence it seems to be reasonable to distinguish DP during homogeneous deformation from that which takes place in heterogeneously deformed alloy. In the first case the process can be analyzed solely in terms of particle-dislocation-particle interrelation. Much more complex problem we are facing in heterogeneously deforming alloy. Deformation bands and specific arrangement of dislocations in form of pile-ups at grain boundaries generate additional driving force and additional nucleation sites for precipitation. Along with heterogeneous precipitation, there is a homogeneous precipitation in areas between bands of coarse slip which also deform but at much smaller rate. This form of decomposition is responsible for a specially high hardening rate during high temperature straining and for thermally stable product of the decomposition of alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.110-115
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• 2019

$Pb(Sb_{0.5}Nb_{0.5})_x(Zr_{0.51}Ti_{0.49})_{1-x}O_3$ (abbreviation: PSN-PZT) ceramics were synthesized, using conventional bulk ceramic processing technology, with various PSN doping contents. The maximum density of PSN-PZT was 97% of the theoretical density in the samples sintered at $1,250^{\circ}C$. The maximum values of the piezoelectric properties achieved using the conventional processes were: $k_p$ of 0.625, $d_{33}$ of 531 pC/N, and $g_{33}$ of $33mV{\cdot}m/N$. Finally, we fabricated a piezo-speaker with the optimized PSN-PZT ceramics. The SPL of the speaker was measured at a distance of 1 m, with a driving voltage of $40V_{rms}$ in the frequency range of ~300 Hz to 9 kHz. The measured $SPL_{max}$ was at a very high level (95 dB), which was superior in quality in comparison with those of other commercial products.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.32.3-32.3
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• 2018

We use the synthetic light-cone from the cosmological hydrodynamical simulation Horizon-AGN to produce a mock photometric galaxy catalogue on the redshift range 0

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.40-44
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• 2020

This paper describes the real operation of 2 kW class reverse-Brayton refrigeration system with neon as a working fluid. The refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa at low and high pressure side, respectively. Compressor package consists of several helium scroll compressors witch are originally used for driving GM cryocooler. Three segments of plate heat exchanger are adopted to cover the wide temperature range and the refrigeration power is produced by turbo expander. The developed refrigeration system is successfully operated at its target temperature of 77 K. In experiments, all parameters such as pressure, temperature, mass flow rate and valve opening are measured to investigate characteristics during cool-down process and normal state. The difference between design and real operation is discussed with measured experimental data. At normal state of 77 K operation, the developed reverse-Brayton refrigeration system shows 1.83 kW at 68.2 K of cold-end temperature.

• Journal of Forest and Environmental Science
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• v.38 no.1
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• pp.12-20
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• 2022

Pongamia (Pongamia pinnata L.) as a source of non-edible oil, is potential tree species for biodiesel production. For several reasons, both technical and economical, the potential of P. pinnata is far from being realized. The exploitation of genetic diversity for crop improvement has been the major driving force for the exploration and ex situ/in situ conservation of plant genetic resources. However, P. pinnata improvement for high oil and seed production is not achieved because of unsystematic way of tree improvement. Performance of P. pinnata planted by Karnataka Forest Department was assessed based on yield potential by collecting 157 clones out of 264 clones established by Karnataka Forest Department research wing under different research circles/ranges. It was evident that the all the seed and pod traits were significantly different. Further, selection of superior germplasm based on oil and pod/seed parameters was achieved by application of Mahalanobis statistics and Tocher's technique. On the basis of D² values for all possible 253 pairs of populations the 157 genotypes were grouped into 28 clusters. The clustering pattern showed that geographical diversity is not necessarily related to genetic diversity. Cluster means indicated a wide range of variation for all the pod and seed traits. The best cluster having total oil content of more than 34.9% with 100 seed weight of above 125 g viz. Cluster I, II, III, IX, XV, XIX, XXI, XXIII, XXVI and XXVII were selected for clonal propagation.