• 재활복지공학회논문지
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• 제8권3호
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• pp.177-185
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• 2014

본 연구에서는 하지마비 장애인의 족하수 방지를 위하여 족배굴곡 보조를 위한 외골격 보조기를 개발하였다. 본 보조기는 인공 근육형 공압 액추에이터를 이용한 동력 전달부, 동력부의 고정을 위한 무릎 관절 착용부 및 보행 신호 검출을 위한 발목 관절 착용부로 구성되었다. 보조기는 무릎 관절 착용부와 발목 관절 착용부에 고정되어 족배굴곡 토크를 발생시켰으며, 발바닥 압력센서를 통해 사용자의 보행 단계를 검출하고, 족배굴곡 보조 타이밍을 감지하도록 하였다. 보행에 이상이 없는 건강한 65세 이상 고령자 7명과 20대 성인 10명을 대상으로 외골격 보조기의 족배굴곡 보조에 대한 성능을 확인한 결과, 인공 근육형 공압 액추에이터의 보조 시 전경골근의 근활성이 감소하는 결과가 나타났다. 향후 연구에서는 하지마비 환자를 대상으로 외골격 보조기의 효과를 검증할 것이다.

• 한국정밀공학회지
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• 제27권6호
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• pp.82-89
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• 2010

Ankle-foot orthosis with an artificial pneumatic muscle which is intended for the assistance of plantarfelxion torque was developed. In this study, power pattern of the device in the various pneumatics and the effectiveness of the system were investigated. The pneumatic power was provided by ankle-foot orthosis controlled by user‘s physiological signal, that is, muscular stiffness in soleus muscle. This pneumatic power can assist plantarflexion torque of ankle joint. The subjects performed maximal voluntary isokinetic plantarflexion motion on a biodexdynamometer in different pneumatics, and they completed three conditions: 1) without wearing the orthosis, 2) wearing the orthosis with artificial muscles turned off, 3) wearing the orthosis activated under muscular stiffness control. Through these experiments, we confirmed the effectiveness of the orthosis and muscular stiffness control using the analyzing isokinetic plantarflexion torque. The experimental results showed that isokinetic torques of plantarflexion motion of the ankle joints gradually increased in incremental pneumatic. The effectiveness of the orthosis was -7.26% and the effectiveness of the muscular stiffness control was 17.83% in normalized isokinetic plantarflexion torque. Subjects generated the less isokinetic torques of the ankle joints in wearing the orthosis with artificial muscles turned off, but isokinetic torques were appropriately reinforced in condition of wearing the orthosis activated under muscular stiffness control(17.83%) compared to wearing the orthosis(-7.26%). Therefore, we respect that developed powered orthosis is applied in the elderly that has weak muscular power as the rehabilitation equipment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1405-1411
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• 2011

It is very often for the experienced diesel locomotive drivers to identify the proper replacing time for the fuel adjustment tube only based on their experience. Because of that, sometimes the locomotive's fuel is burned out due to the unnecessary torque. Or sometimes, the locomotive does not operate with its accelerating performance because the fuel is not supplied at the appropriate moment. Meanwhile, recent typical auto vehicles provide drivers with the average fuel efficiency and the instant fuel efficiency in real-time. By providing the real time display mentioned above, it is one of the good examples that those drivers, who had driven their cars not properly and used a lot of fuel with their bad driving habits, obtain the efficient driving pattern by continuous educating effect. Similarly, if the diesel locomotive provides the train driver with the optimal driving pattern within a certain driving section, it will be effective for fuel saving. It is possible to make the most effective driving pattern by performing the repeated trial running especially for the railway because the track's operating routes, its grades, and etc are relatively precise. This research analyzes the result data which was obtained by many times trial running on the identical section after equipping the fuel use measuring device to a certain test vehicle, and confirms the fuel saving effect depending on the driving pattern along the test section. At the same time, the research to establish the optimal driving pattern was progressed.

• 한국기계가공학회지
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• 제10권4호
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• pp.70-75
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• 2011

Nowadays, modern gearboxes are characterized by high torque load demands, low running noise and compact design. Also durability of gearbox is specially a major issue for the industry. For the gearbox which used in wind turbine, gear transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. In this paper, tooth modification for the high speed stage is used to compensate for the deformation of the teeth due to load and to ensure a proper meshing to achieve an optimized tooth contact pattern. The gearbox is firstly modeled in Romax software, and then the various combination analysis of the tooth modification is presented by using Windows LDP software, and the prediction of transmission error under the loaded torque for the helical gear pair is investigated, the transmission error, contact stress, root stress and load distribution are also calculated and compared before and after tooth modification under one torque condition. The simulation result shows that the transmission error and stress under the loads can be minimized by the appropriate tooth modification.

• 한국지능시스템학회논문지
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• 제26권3호
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• pp.196-201
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• 2016

본 논문에서는 인간의 팔꿈치 관절의 기능을 활성화하기 위한 강성 기반 재활 메커니즘의 특성을 분석하 고자 한다.여기서,팔굼치 관절의 재활을 위한 도구는 탄성 줄을 사용하고, 사용된 줄은 선형 스프링으로 모델링하여 강성값으로 나타낸다. 이러한 메커니즘을 이용한 팔꿈치 관절 재활 훈련을 효과적으로 하기 위해서는 줄의 강성값에 따라 팔꿈치 관절에 가용할 수 있는 토오크 특성을 분석할 필요가 있다. 이러한 관점에서 다양한 시뮬레이션을 통하여 탄성 줄의 강성값 설정에 따른 팔꿈치 관절의 토오크 패턴 및 범위를 사전에 정의된 팔꿈치 관절의 운동 경로에 대하여 확인한다. 결과적으로, 이러한 강성 기반 재활 메커니즘이 팔꿈치 관절의 효과적인 재활을 수행하는데 유용하게 활용될 수 있음을 보인다.

• Journal of Power Electronics
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• 제11권4호
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• pp.401-407
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• 2011

In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vector decomposition, the mathematic model in two orthogonal space plane, $d_1-q_1$ and $d_3-q_3$, was deduced. And the corresponding dual-plane vector control method was accomplished to independently control fundamental and third harmonic currents in each vector plane. A five-phase PMSM prototype with quasi-trapezoidal flux pattern and its fivephase voltage source inverter were designed. Also, the dual-plane vector control was digitized in a single XC3S1200E FPGA. Simulation and experimental results prove that using the proposed optimum seeking method, the torque density of five-phase PMSM is enhanced by 20%, without any increase of power converter capacity, machine size and iron core saturation.

• 대한기계학회논문집A
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• 제26권5호
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• pp.822-827
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• 2002

In general, jerk phenomenon appeared because of gear changing, when a vehicle starts off or climbs an incline. Therefore, it makes ride quality worse. In this paper, an optimal pattern of automatic transmission was designed using fuzzy logic in order to improve ride quality. After del eloping fuzzy rule for shift pattern control of automatic transmission, dynamic characteristics (i.e. acceleration, velocity, distance and so on) were simulated using dynamic model of a car. To do this he powertrain model of a vehicle with automatic transmission including torque converter, gear box, and final gear drive - from engine to tire - is developed.

• 대한전기학회논문지
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• 제44권4호
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• pp.447-452
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• 1995

In this paper a simple method of a position control for brushless DC motor is presented. For precise position control, a high performance torque controller is needed and a novel current control method is proposed. The current controller detects the uncommutating mode current for every 60.deg. (elec. angle) and controls it with PI controller. The current control loop includes the feedforward of back EMF and the feedforward of the neutral voltage between the neutral point of the inverter and the neutral point of the machine. In the position control, the acceleration pattern is calculated from the position reference. Then the speed trajectory is calculated from the acceleration pattern. The experimental results are presented to verify the proposed methods.

• 대한방사선기술학회지:방사선기술과학
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• 제40권1호
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• pp.19-25
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• 2017

본 연구는 1.5 T와 3.0 T Magnetic Resonance Imaging에서 Bone-Anchored Hearing Aid (BAHA) implant의 수평인력, 회전력, 그리고 자화감수성 인공물의 크기를 표준측정 방법에 의해 측정하여 MR 안전성을 평가하였다. BAHA implant의 고정장치와 지지대는 0.5%의 철(iron)이 포함 된 티타늄으로 만들어졌으며, 길이는 10 mm (고정장치 4 mm, 지지대 6 mm), 최대 직경은 7.0 mm이다. 수평인력 측정장치와 자화감수성 인공물 측정장치는 각각 American Society for Testing and Materials (ASTM) F2052-06, F2119-07을 참조하여 아크릴을 이용해 제작했으며, 회전력 측정은 원형 플라스틱 용기를 이용한 측정장치를 사용하였다. 자기유도에 의한 BAHA implnat의 수평인력은 주자장이 가장 큰 지점인 96 cm지점에서 최대 변위각을 측정하였고, 회전력은 원형용기 내부의 $45^{\circ}$간격의 실선 위에 놓았을 때 나타난 회전형태를 정성적 평가기준으로 측정하였다. 자화감수성 인공물은 황산구리($CuS0_4$) 용액이 채워진 용기의 중앙에 BAHA implant를 매달아 영상을 획득한 후 Susceptibility Artifact Measurement (SAM) software를 이용해 크기를 측정하였다. 측정결과 수평인력은 1.5 T와 3.0 T에서 변위각과 변위력은 모두 0으로 나타났다. 회전력은 1.5 T에서는 0(no torque), 3.0 T에서는 +1(mild torque)로 나타났다. 자화감수성 인공물은 최소 13.20 mm, 최대 38.91 mm의 크기로 나타났다. 따라서 1.5 T, 3.0 T의 MR 환경에서 BAHA implant는 환자에게 안전하다.

• 천문학회보
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• 제38권2호
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• pp.39.1-39.1
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• 2013

We use high-resolution hydrodynamic simulations to study nonlinear gas responses to imposed non-axisymmetric stellar potentials in barred-spiral galaxies. The gas is assumed to be infinitesimally thin, isothermal, and unmagnetized. We consider various spiral-arm models with differing strength and pattern speed, while fixing the bar parameters. We find that the extent and shapes of spiral shocks as well as the related mass drift depend rather sensitively on the pattern speed. In models where the arm pattern is rotating more slowly than the bar, the gaseous arms extend from the bar ends all the way to the outer boundary, with a pitch angle slightly smaller than that of the stellar counterpart. The arms drive mass inflows at a rate of ${\sim}0.5-2.5M{\odot}/yr$ to the bar region to which the shock dissipation, external torque, and self-gravitational torque contribute about 50%, 40%, and 10%, respectively. About 85% of the inflowing mass is added to bar substructures such as an inner ring, dust lanes, and a nuclear ring. while the remaining 15% encircles the bar region. On the other hand, models where the arms corotate with the bar exhibit mass outflows, rather than inflows, over most of the arm region. In these models, spiral shocks are much more tightly wound than the stellar arms and cease to exist in the region where $M{\bot}/sinp*{\geq}25-40$, where $M{\bot}$ denotes the Mach number of a rotating gas perpendicular to the arms with pitch angle p*. We demonstrate that the distributions of line-of-sight velocities and densities can be a useful diagnostic tool to distinguish if the arms and bar corotate or not.