• Journal of the Institute of Convergence Signal Processing
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• v.25 no.2
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• pp.77-85
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• 2024

The suspension device that connects the prosthetic leg and the residual limb allows lower limb amputees to wear prosthetic limbs, and is the most sensitive part when using prosthetic limbs as it is always in contact with the residual limb not only while walking but also in everyday life. In this paper, using the principles of attraction and repulsion of permanent magnets, we developed a magnetic lock suspension device that can fix the amputees and prosthetic legs of lower limb amputees by changing the polarity of the magnet. The operation method of the magnetic lock is that when neodymium magnets are placed on the left and right as NNSS based on a non-magnetic brass core, the magnetic force flows outward beyond the brass core using the adsorption member as a medium to generate bonding force. When rotated 90 degrees, the magnet moves to NSNS. The principle is that as the position moves, the magnetic force flows inward and cancels out.Based on this, we conducted a bonding test using tensile strength and a short-term comparative evaluation of the prosthesis with the shuttle lock suspension system, which was a comparison group, to verify reliability and evaluate satisfaction with the prototype. As a result, the tensile strength exceeding the appropriate bonding strength was confirmed, and the magnetic lock showed higher satisfaction than the shuttle lock. In the future, we plan to conduct long-term ADL clinical trials for commercialization and develop a product that can be distributed to actual amputees.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.426-434
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• 2009

A global simulation of $SiH_4/H_2$ discharge is conducted in a planar-type inductively coupled plasma (ICP) discharge. We numerically solve a set of spatially averaged fluid equations for electrons, positive ions, negative ions, neutrals, and radicals. Absorbed power by electrons is determined by an analytic electron heating theory including the anomalous skin effect. Also, we investigate functional dependence of various discharge quantities such as the densities of various species and the temperature of electron on external controllable parameters such as ratio between $SiH_4$ and $H_2$, power and pressure.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.162-172
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• 2008

In this paper, we propose a multimodal speaker verification method using teeth image and voice as biometric trait for personal verification in mobile terminal equipment. The proposed method obtains the biometric traits using image and sound input devices of smart-phone that is one of mobile terminal equipments, and performs verification with biometric traits. In addition, the proposed method consists the multimodal-fashion of combining two biometric authentication scores for totally performance enhancement, the fusion method is accompanied a weighted-summation method which has comparative simple structure and superior performance for considering limited resources of system. The performance evaluation of proposed multimodal speaker authentication system conducts using a database acquired in smart-phone for 40 subjects. The experimental result shows 8.59% of EER in case of teeth verification 11.73% in case of voice verification and the multimodal speaker authentication result presented the 4.05% of EER. In the experimental result, we obtain the enhanced performance more than each using teeth and voice by using the simple weight-summation method in the multimodal speaker verification system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.405-414
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• 2010

In the study, experiments are performed in the mixing region combined wave and current to investigate the characteristics of local scour around a slender pile. Wave generator and current generator are used for the experiments and currents are co-directions with the waves. The local scour depths around the pipeline are obtained according to the various pipe diameters, wave periods, wave heights, and current velocities. The experiments show that the maximum equilibrium local scour depth increases with pipe diameter, wave period, wave height, and current velocity. Using the experimental results, the correlations of scour depth and parameters such as Shields parameter ($\theta$), Froude number (Fr), Keulegan-Carpenter number (KC), Ursell number ($U_R$), modified Ursell number ($U_{RP}$) and ratio of velocities ($U_c/U_c+U_m$) are analyzed. In the mixing region combined with waves and currents, The Froude number of single parameters is the main parameter to cause the local scour around a slender pile due to waves and current and this means that current governs the scour within any limits of the currents.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.290.2-290.2
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• 2013

X-선 튜브는 의료 영상 및 치료, 산업용 제전 장치, 비파괴 X-선 영상 장치 등에서 사용되는데 기존의 열전자원을 이용한 X-선 튜브와는 달리, 냉음극형 X-선 튜브는 빠른 속도의 디지털 구동이 가능하며 전력 소비가 낮은 장점이 있다. 따라서, 최근 많은 연구자들에 의해서 냉음극형 X-선 튜브에 관한 연구가 활발하게 진행되고 있다. 냉음극형 X-선 튜브는 전계 방출을 이용한 전자원을 사용하며, 탄소나노튜브 (CNT), Si, 다양한 종류의 나노선 등이 대표적이다. 그 중에서 CNT는 높은 종횡비로 인해 전계 방출 특성이 우수하여 가장 대표적인 물질이다. CNT를 이용한 전자원을 제작하기 위해서는 직접 성장법, 전기영동법, 스크린 프린팅법, 디핑법 등 다양한 방법이 존재한다. 직접 성장법을 제외한 방법들은 모재료인 CNT와 용매, 금속재료들을 섞어 페이스트나 수용액의 상태를 제작하여야 한다. 이 때, 금속 재료는 기판과 CNT간의 접착 및 전자 전도 통로의 역할을 하는 무기 충전제이며 일반적으로 나노 혹은 수 마이크로미터 크기의 상태로 존재하는 것을 주로 사용한다. X-선 튜브 제작은 일반적으로 외벽을 유리 혹은 세라믹을 주로 사용하는데 아노드 전극 및 캐소드 전극 등과 결합하여 진공 밀봉된 형태가 되어야 한다. 브레이징 방법은 금속과 세라믹을 결합하는데 매우 유용한 방법이며, 그 중에서도 진공 브레이징 방법은 다량의 부품을 한 번에 결합시킬 수 있다. 하지만 진공 브레이징 공정의 온도는 약 $700{\sim}1,000^{\circ}C$이며 이는 금속 재료가 충분히 증발할 수 있는 온도가 된다. 본 발표에서는 고온 진공 상태에서의 무기 충전제의 증발에 대한 현상을 관찰하고 고온진공 상태에서 증발없이 무기 충전제로의 역할을 할 수 있도록 다양한 금속 및 합금에 대한 연구를 수행하였다. 또한, 이 연구를 통해 선택된 무기 충전제를 포함하여 CNT 페이스트를 볼밀링 방법을 이용하여 제작하였으며, 이를 이용한 CNT 에미터가 X-선 튜브의 전자원으로 사용될 수 있는지 확인하기 위해 전계 방출 실험을 함께 실시하였다. 제작된 CNT 에미터가 우수한 전계 방출 특성을 가지고 있음을 확인하였으며, 이는 본 연구를 통해 선택된 금속 및 합금 재료가 무기 충전제로의 역할을 잘 수행하고 있음을 보여준다.

• Journal of agriculture & life science
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• v.51 no.1
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• pp.205-212
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• 2017

This study aimed to output augmented reality display using chroma-key so that power tiller simulator can be operated smoothly while wearing the head mounted display. In this paper, we propose a chroma-eliminating image filtering method. Experimental results show that the maximum and minimum values of hue, saturation and intensity were 0.52, 0.153, 0.57, 0.16, 1, and 0.12, respectively. A keypad was used to set the initial position of augmented reality adjusted with the front, back, top, bottom, left, and right buttons. The initial position value is always maintained and managed according to the trailer attachment and detachment. Finally, we show that the augmented reality merged with virtual image and the acquired image of operation device using coordinate values obtained from the HMD and the position tracking sensor as relative coordinates in Unity program that is the ultimate game development platform.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.9
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• pp.685-697
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• 2017

In this paper, it is presented the result of design and fabrication for C-band solid state high power amplifier unit and components using in search radar. The solid state power amplifier(SSPA) assembly was fabricated using GaN(Gallium Nitride), which is semiconductor device, and the transmit signal output power of the solid state high power amplifier unit is generated by combining the transmit signal power of the solid state power amplifier configured in parallel through a design and fabricated waveguide type transmit signal combine assembler. Designed solid state high power amplifier unit demonstrated C-band 500 MHz bandwidth, maximum 10.5% duty cycle, transmit pulse width from $0.0{\mu}s{\sim}000{\mu}s$, and transmit signal power is 44.98 kW(76.53 dBm).

• Journal of The Korean Association of Information Education
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• v.23 no.5
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• pp.461-467
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• 2019

As the convergence solutions become more common, the use of Arduino and Raspberry Pi boards has been increasing. These control boards has to be executed under power blackout. In this environment, we take advantage of solar power system to overcome the power out. In this paper, we poposed a effficient power control strategy. Our experimental device is a DSLR shooting device executed based a predesigned interval time. The control module of our experimental device is the compound system of Raspberry Pi and Arduino boards. Arduino board send the force signals to wake up Raspberry Pi. We developed a new control strategy algorithm for the efficient use of solar power energy. In this paper, we mesured the efficiency of solar enery consuming of our system. We programmed a control system to send DSLR shooting signals. In experimentals, we ensured a stable consuming of electricity during 10 days. In the end, it was found that the consumption power of the Raspberry was reduced by about 81% when the Aduino was combined to save power.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.19-28
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• 2022

In this study, three types of combined isolator consisting of High Damping Rubber Bearing (HDRB) and wire isolator were developed for Uninterruptible Power Supply system (UPS). The dynamic characteristics of the combined isolator were investigated through one-axis shaking table test. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration were designed to be 0.5-2 times the required response spectrum defined in ICC-ES AC156. Based on the test results, damage and dynamic characteristics of the UPS were investigated: including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement. Based on that, it was found that the combined isolator developed in this study could improve the seismic behavior of the UPS, in particular, the response acceleration.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.4
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• pp.67-76
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• 2009

Recently, the active interaction control (AIC) system was proposed as a semi-active control system. The AIC system consists of a primary structure and an auxiliary structure. The objective of the AIC system is to control the response of the primary structure through engagement and disengagement between the primary and auxiliary structures. Previous switching control algorithms have been shown to be effective in reducing the response of the primary structure. However, they have the main drawback of requiring an excessive engagement-disengagement frequency and high interaction force. In this paper, the regions in which the switching is activated and the regions in which the switching is deactivated are described separately, to effectively determine the engagement or the disengagement. The general relationship between the switching regions and the deactivated switching regions selected according to the engagement-disengagement conditions is described within the newly-developed comprehensive switching framework. The proposed engagement-disengagement conditions are designed within a comprehensive switching framework, to reduce engagement-disengagement frequency and interaction force. Furthermore, the effect of a control sampling period on the AIC system is explained in terms of the engagement-disengagement frequency. The effectiveness of the proposed algorithms and the effect of the control sampling period are considered for a single degree of freedom model under free vibration. It is observed that increasing the duration of stay by using a large control sampling period prevents the AIC system from activating the possible chance of switching. The proposed algorithms are shown to be effective, both in restricting ineffective switching and in reducing interaction force.