• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.2
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• pp.55-62
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• 2012

In this paper we propose a control system to preserve the interior angle between back section and upper leg section to be larger than 90 degrees using a single limit switch. To design the control system we analyze the kinematics of actuation mechanisms for the back section and the upper leg section, and find out an optimal solution for the controller design. Using a prototype control system we perform experiments to test the controller performance, and show that the interior angle between the back section and the upper leg section is always preserved larger than 90 degree. From the experimental results, we show the proposed control system is feasible to keep the body posture stability.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.5
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• pp.478-485
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• 2015

Availability of the climbing angle information is crucial for the intelligent vehicle system. However, the climbing angle information can't be measured with the sensor mounted on the vehicle. In this paper, climbing angle estimation system is proposed. First, longitudinal acceleration obtained from gyro-sensor is compared with the actual longitudinal acceleration of the vehicle. If the vehicle is in yawing motion, actual longitudinal acceleration can't be approximated from time derivative of wheel speed, because lateral velocity and yaw rate affect actual longitudinal acceleration. Wheel speed and yaw rate can be obtained from the sensors mounted on the vehicle, but lateral velocity can't be measured from the sensor. Therefore, lateral velocity is estimated using unknown input observer with nonlinear tire model. Simulation results show that the compensated results using lateral velocity and yaw rate show better performance than uncompensated results.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.85-92
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• 1994

본 연구에서는 작업용 의자를 설계하고 평가하기 위한 한국인의 좌판과 등판의 형태 (contour) 모형을 제시하고자 한다. 신장, 앉은키, 몸무게, L5폭, T7폭 등을 측정하여 통계적으로 분석한 결과, 앉은키와 AC폭, 몸무게와 L5폭은 상관관계가 있는 것으로 밝혀졌다. 따라서, 사람의 좌판, 등판 접촉 형태를 측정하기 위해서 몸무게와 앉은키에 따라 각각 세 그룹으로 나누어 총 아홉 그룹으로 분류하였다. 자체 제작된 좌판과 등판의 접촉형태 측정기를 사용하여 각 그룹별로 측정점에 대한 계측을 통하여 형태자료를 수집하고, 통계분석을 통하여 한국인의 형태모형을 추출하고, 컴퓨터 그래픽을 이용하여 시각적 평가를 가능하게 하였다. 이를 통하여 작업용 의자의 성능 및 안락도 향상을 위한 체계적 접근방법을 제시하고, 평가에 있어서는 정량적인 척도를 제공할 수 있을 것이다.

• Science of Emotion and Sensibility
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• v.3 no.2
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• pp.57-65
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• 2000

컨조인트 분석기법은 Marketing 분야에서 주로 많이 쓰여온 분석 방법으로서 제품의 중요한 속성들을 찾아내어 다양한 종류의 제품들에 대한 고객의 선호도를 분석하는 방법이다. 본 연구에서는 컨조인트 분석기법을 이용하여 의자의 물리적 적합도를 분석, 평가하여 사용자가 적합하다고 느끼는 최적의 의자를 밝히는데 목적을 두었다. 안정성, 여유성, 인체적합성, 안락성등 4개의 적합도 요소를 종속변수로 선택하고 의자 자체의 설계 요소에 해당하는 휴먼인테페이스 요소(HIE) 중 높이 조절 기능, 팔걸이, 등판길이의 3가지 속성을 독립변수로 사용하였다. 분석에 사용된 의자는 각 속성을 특징적으로 대표하는 8개의 의자들로서 구성되었다. 분석의 결과 네 가지의 적합성에 공통성적으로 가장 큰 영향을 주는 속성은 (남자 안정성은 예외) 등판길이로서 남자와 여자 모두 등판길이가 높을 때 안정적이며 안락하고 인체적합하며 여유성이 있다고 느낀다는 결과가 나왔다. 적합도의 네가지 항목 모두에서 공통적으로 등판길이가 높고 팔걸이가 있는 경우에 평가가 높게 나타났으며, 안정성의 경우에는 남·녀 모두 높이조절 기능이 없는 고정형을 더 높게 평가하는 것으로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.535-540
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• 2015

The location of the pivot between the backrest and seat pan of a reclining chair should be identical to the hip joint center to prevent unpleasant user experiences during tilting motion. However, mechanical friction occurs in the pin-in-slot joints that are installed under the seat pan as an alternative to the hinge joint. This reduces the reaction force between the backrest and the occupant's back when reclining and returning to an upright position, which causes the occupant's discomfort. In this study, bearings, rollers, and sliders were suggested as alternatives for the pin component, and the percentage of the reaction force on the backrest was measured while reclining the backrest and subsequently returning it to an upright position. The results show when bearings, rollers, and sliders were used for the pin-in-slot joint, the percentages of the reaction force were $59.7{\pm}10.3$, $47.2{\pm}13.6$, and $30.3{\pm}18.1$, respectively, indicating that the friction of the bearing was the lowest among the three pin components. Because the three alternatives have different manufacturing costs, synthetic judgment requires the consideration of not only mechanical friction but also user experience.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1523-1531
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• 2011

Multi-axle driving vehicle are favored for military use in off road operations because of their high mobility on extreme terrains and obstacles. Especially, Military Vehicle needs an ability to driving on hills of 60% angle slope. This paper presents the improvement of the ability of hill climbing for 6WD/6WS vehicle through the optimal tire force distribution method. From the driver's commands, the desired longitudinal force, the desired lateral force, and the desired yaw moment were obtained for the hill climbing of vehicle using optimal tire force distribution method. These three values were distributed to each wheel as the torque based on optimal tire force distribution method using friction circle and cost function. To verify the performance of the proposed algorithm, the simulation is executed using TruckSim software. Two vehicles, the one the proposed algorithm is implemented and the another the tire's forces are equivalently distributed, are compared. At the hill slop, the ability to driving on hills is improved by using the optimum tire force distribution method.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.4
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• pp.279-285
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• 2016

In this paper, a platform design of caterpillar typed electrical vehicle is proposed. Nowadays, there have been many researches on mobile robots in the various ways. Many different fields such as military, exploration, agricultural assistance and disaster relief have applied the mobile robot. Design condition of stable angle, upset angle is reflect to caterpillar typed electrical vehicle. To experiment, developed a caterpillar typed electrical vehicle and design a driving controller. Developed caterpillar typed electrical vehicle is tested about operating and driving. Test environment is consisted of driving on flatland and climbing 15 degree and outdoor 40 degree slope. It is confirmed that developed tracked electric vehicular robot can driving and climbing.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.323-326
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• 2002

본 연구는 새로 개발된 에어쿠션의자의 인체 적합성 검증에 관한 실험으로 기존 에어쿠션의자와 스펀지 매트의자를 새로 개발된 의자와 비교 평가 하였다. 본 연구를 위해 설문지를 통한 사용자의 감성 및 사용성을 측정하였고 객관적 검증에 필요한 체압분포측정을 하였다. 실험의 결과 사용성 평가에서 대부분의 피험자들이 신형 의자가 보다 편안하고 안락하다고 응답하였으며, 각 의자를 비교하는 전체 14항목의 설문 중 11개 항목이 의자A에서 중요도 순위가 좋게 나타났다. 체압분포에서도 좌판의 경우 신형 에어쿠션의자의 체압의 평균값이 적게 나오면서 고르게 분포하였고, 좌골결절을 중심으로 좌, 우 대칭이 되게 나왔다. 또한 등판부위에서도 등판의 수직선을 중심으로 체압분포가 좌, 우 대칭이 되게 나왔다.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.171-177
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• 2008

This work intends to investigate the effects of pedaling directions on the muscle actions during the bicycle's uphill propulsion. A test rig was developed that consists of a bicyle with a special planetary geartrain, a height-adjustable treadmill, a rear-wheel support and a magnetic brake. A three-dimensional motion analysis was performed for measuring kinematic characteristics of the forward backward pedaling and the electromygraphy(EMG) measurements were simultaneously performed for estimating the muscle actions of the leg. In this work, four muscles are considered including Gastrocnemius muscle(GM), Vastus lateralis(VL), Tibialis anterior(TA) and Soleus(SOL) while the uphill slope is varied from $0^{\circ}$ to $6^{\circ}$. Raw EMG signals were first processed through the root-mean-square(RMS) averaging and then ensemble curves were derived by averaging the EMG RMS envelopes over 50 consecutive cycles. Results show that both the kinemactic characteristics and the muscle actions are significantly affected by the pedaling direction. The crank speed of the forward pedaling is higher but the difference in speed is reduced as the slope is increased. The ensemble curves of the :ac signals clearly exhibit some differences in their patterns, peak values and the corresponding locations with respect to the crank angle. The peak values of most EMG signals are higher for the forward pedaling regardless of the slope magnitude. However, the averages of the EMG signals are not observed to have a similar relationship with the pedaling direction, which seems to be affected by several factors such as less experience of the participants' backward pedaling. inappropriate bicycle design for the backward pedaling. These limitations will be further considered in future work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3708-3713
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• 2015

The objective of this study is to numerically investigate the heat transfer rate for evaluating the thermal performances of the stack thermal system using the commercial software. In order to perform this, the cooling performances of the stack system for fuel cell electric vehicle were tested under both driving road conditions including the general driving road and uphill driving road and operating conditions with and without of the air conditioning system. The heat transfer rate of the stack radiator for the stack system was increased with the increase of the inlet air flow velocity. The heat transfer rate of the stack radiator increased by 105.3% at the coolant flow rate of 20 l/min and 221.3% at the coolant flow rate of 120 l/min with the increase of the air flow velocity from 2 m/s to 10 m/s. $9.45^{\circ}C$ of inlet coolant temperature of the stack radiator at the severe driving condition of the slope of 8% and velocity of 50 km/h showed higher 85.3% than $5.1^{\circ}C$ of inlet coolant temperature at the general driving condition of the slope of 0% and velocity of 120 km/h. In addition, as the fuel cell electric vehicle with the air conditioning system operation was driving under severe uphill driving condition, the radiator coolant temperature for a stable stack operation could be exceeded over $70^{\circ}C$.