• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.18-23
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• 1996

This paper proposes a new levitation scheme for EDS MAGLEV vehicle with AC superconducting magnet(ACSCM). The eddy current and the levitation force are generated at all speed including stand still in this scheme, therefore, the auxiliary wheels on DCSCM can be eliminated. To reduce the ac loss of the magnet, the ACSCM also can be operated as a DCASCM at high speed because levitation force generated by DCSCM is enough at high speed. To prove the effectiveness of the proposed scheme, the repulsive force and power loss versus frequency of ACSCM is calculated. For comparison, characteristics of DCSCM of same cross section versus speed are also given. (author). 6 refs., 9 figs.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.197-204
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• 2005

In this study, ground reaction force(GRF), absolute symmetry index(ASI) and coefficient of variation(CV) of fixed, single-axis and multi-axis prosthetic ankle assemblies were investigated to show the biomechanical evaluation for above knee amputees. In the experiments, 37 normal male volunteers, two male and two female AK amputees were tested with fixed, single-axis and multi-axis prosthetic ankle assembly. A gait analysis was carried out to derive the ratio of GRF to weight as the percentage of total stance phase for ten points. The results showed that fixed-axis ankle was superior to the other two ankle assemblies for the characteristic of forwarding and breaking forces. Multi-axis ankle was relatively superior to the other two ankle assemblies for gait balancing and movement of the center for mass. single-axis ankle was relatively superior to the other two ankle assemblies for CV and ASI of GRF.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.424-433
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• 2019

The purpose of this study was to investigate the effects of gender difference in injury experience on biomechanical variables of lower extremity during two leg drop landing. 20 male(injury experience=8, non-injury experience=12) and 20 female(injury experience=11, non-Injury Experience=9) in their 20's were selected as subjects. Two-way mixed ANOVA was performed on the biomechanical variables obtained from the two leg drop landing in a 45cm height box and post-test was performed with bonferroni adjustment(p <.05). The results of this study suggest that the group of female who injury experience could induce the reduction of the peak vertical ground reaction force by increasing the valgus and internal rotation of the knee joint and flexion and internal rotation of the hip joint. In the INE(injury non-experienced) female group, the peak knee flexion angle was the smallest, as well as the flexion of the hip joint and the external rotation angle, and the peak vertical ground reaction force was the highest. On the other hand, the INE female group showed high vertical ground reaction force because they did not utilize the knee and hip joints relatively than the IE(injury experienced) female group, this means that it is relatively exposed to the risk of injury. Therefore, it was found that gender difference in injury experience is a factor affecting factors of knee and hip joint movement and peak vertical GRF(ground reaction force).

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1159_1160
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• 2009

This paper presents the numerical simulation results on the supercodnucting electrodynamic suspension (EDS) simulator according to the variation of the ground conductor. The levitation force of the EDS system is formed by the reaction between the moving magnet and the fixed ground conductor. The possible way to simulate the EDS system were simulated in this paper by using finite element method (FEM). The static type simulator which consists of the fixed magnet, the fixed ground conductor and the ac current supply system. To verify the characteristics of high speed EDS system with the moving type simulator heavy, large and fast moving ground conductor is needed. The static type simulator can get the characteristics of the high speed EDS system by applying equivalent ac current to velocity, therefore it does not need large moving part. The static type EDS simulator, which can consist of an HTS magnet, the fixed ground conductor(s), an AC power supply and the measuring devices, also test the effect of the shape of the ground conductor easily. The plate type ground conductor made stronger levitation force than ring type ground conductor. Although the outer diameter 335 mm ring type ground conductor (Ring3) was larger than the outer diameter 235 mm ground conductor (Ring2), the levitation force by Ring2 was stronger than that by Ring3. From the calculation results on this paper, the consideration of the magnetic flux distribution according to the levitation height should be included in the process of the ground conductor design.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.125-132
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• 2002

This paper shows an experimental magnetic levitation table using one degree-of-freedom active control. The magnetic levitation table using repulsions of permanent magnets was theoretically presented already. Thus the objective of this paper is to prove stable levitation with only one degree-of-freedom active control experimentally. For the design of the system, at first, permanent magnets are selected. Secondly, the spring constants of the virtual spring are obtained by simulation. Thirdly, the moving magnets are arranged using a stable layout relation. Fourthly, a linear voice coil motor is designed. Finally, the magnetic levitation system is manufactured. The phenomenon of stable levitation in the manufactured table is proven by means of dynamic time and frequency responses. The differences between the theoretical natural frequencies and experimental ones are analyzed. Also, stable range in the control direction is shown experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.723-724
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.1005-1006
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• 2010

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.283-291
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• 2010

The purpose of this study was to investigate the effect of foot placement and height of bed surface on lumbar spine load in a dummy transfer activity. Fifteen healthy male students participated in this study. All subjects were involved in four different conditions according to foot placement (11 figure and $90^{\circ}$ figure) and height of bed surface (44 cm and 66 cm) randomly. Muscular activations of the biceps brachii, rectus femoris, elector spinae using surface-EMG, vertical ground reaction using force plate, and L4/L5 compression force using 3DSSPP (3D Static Strength Prediction Program) were measured and analysed. The results showed that muscular activations were not significantly different for the various conditions except for the rectus femoris on the right side (p<.05). Futhermore, the vertical ground reaction and L4/L5 compression force were significantly different conditions (p<.05). In conclusion, it is suggested that foot placement at $90^{\circ}$ figure is safer for transfer activity compared with the 11 figure.

• Explosives and Blasting
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• v.28 no.2
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• pp.59-68
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• 2010

Building demolition and blasting work in urban areas has a possibility which has an effect on the structural stability of nearby structures. In this study, the compressive strength and chemical composition of decrepit concrete materials were estimated by Schmidt rebound test and XRD phase analysis. The damage index of the concrete materials was calculated by measured P-wave velocities. It was revealed that the constituents of the concrete materials affect on the compressive strength. The damage index decreases with increasing compressive strength and decreasing impact energy.

• 전기의세계
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• v.43 no.3
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• pp.18-28
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• 1994

현재까지 개발되고 있는 자기부상열차는 상전도 방식과 초전도 방식의 2종류로 대별 할 수 있다. 즉 상전도방식은 상전도 전자석에 의한 흡인력에 의해 지상에서 1cm정도를 부상하여 주행하는 시스템으로 영국의 버밍행공항의 People mover, 독일의 Transrapid, 일본의 HSST, 우리나라의 한양대, 자기 부상열차사업단, 대우중공업, 현대정공의 EXPO전시운행선등이 개발되어 있다. 초전도방식으로는 초전도전류에 의한 반발력에 의해 10cm이상 부상되어 운행되는 시스템으로 MLU 시스템이 있는데 지진이 심한 일본에서 개발되었다. 영국의 버밍햄공함의 People mover는 1984년부터 실용화되어 무인자동운전시스템으로 10년간을 아무 문제 없이 운행되고는 있지만 선로길이 620m 정도의 소규모 저속운송시스템에 지나지 않는다. 반면 독일의 Transrapid시스템은 31.5km의 트랙을 설치하여 시속 450km까지 운행을 계속하여 현재 15만km정도의 운행실적을 올리고 있다. 최근 독일내각은 함부르크-베를린 사이의 290km에 이르는 선로를 2005년까지 완공하기로 결정을 내리고 금년 상반기에 착공을 할 예정이다. 따라서 세계적으로 실용화단계에까지 도달한 대규모 고속시스템으로는 단연 Transrapid시스템을 꼽을 수 있다. 이에 Transrapid사와 미국, 일본등의 각 국에서 그간 세밀하게 조사하여 검토한 자료를 상세하게 소개하므로써 신교통시스템으로서의, 자기부상열차의 적합성과 개발의 타당성 및 당위성을 제시하여 이 분야에 관심있는 분들에게 참고는 물론 우리나라의 개발방향 설정에 유익한 자료가 되었으면 한다.