• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.10
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• pp.1195-1200
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• 2013

In recent years, variable stiffness actuation has attracted much attention because interaction between a robot and the environment is increasingly required for various robot tasks. Several variable stiffness actuators (VSAs) have been developed; however, they find limited applications owing to their size and weight. For realizing their widespread use, we developed a compact and lightweight mini-VSA. The mini-VSA consists of a control module based on an adjustable moment arm mechanism and a drive module with two motors. By controlling the relative motion of cams in the control module, the position and stiffness can be simultaneously controlled. Experimental results are presented to show its ability to change stiffness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.434-439
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• 2021

We assessed the effects of intravenous (IV) ascorbic acid administration on fatigue in women undergoing laparoscopic myomectomy. We analyzed the secondary endpoint results of a randomized, double-blind, placebo-controlled trial. Fifty patients undergoing laparoscopic myomectomy received IV ascorbic acid (2g) or placebo (randomly 1:1 ratio) intravenously during surgery. On day 2 post-surgery, we measured the level of fatigue using the Brief Fatigue Inventory-Korean version. Forty-five women (experimental arm 23, control arm 22) were eligible for analysis after 5 women (experimental arm 2, control arm 3) were excluded due to withdrawal of consent, cancellation of surgery or non-measurement of the endpoints. The baseline and operative characteristics were similar between arms and the global fatigue score of the experimental arm (4.56 ± 2.63) was not significantly different from that of the control arm (5.21 ± 2.02, P = 0.351). However, the fatigue score of the experimental arm tended to be lower than that of the control arm in most domains. IV ascorbic acid administration did not significantly reduce the level of fatigue in women undergoing laparoscopic myomectomy as compared to placebo. More research is needed to better understand the effects of ascorbic acid on fatigue in surgical patients.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.1
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• pp.67-72
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• 2015

The system for controlling the robotic arm through the foot motion detection was implemented for the disabled who not free to use of the arm. In order to get an image on foot movement, two cameras were setup in front of both foot. After defining multiple regions of interest by using LabView-based Vision Assistant from acquired images, we could detect foot movement based on left/right and up/down edge detection within the left/right image area. After transferring control data which was obtained according to left/right and up/down edge detection numbers from two foot images of left/right sides through serial communication, control system was implemented to control 6-joint robotic arm into up/down and left/right direction by foot. As a result of experiment, we was able to get within 0.5 second reaction time and operational recognition rate of more 88%.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.589-594
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• 2013

Background: Prospective cohort studies to determine cofactors with oncogenic HPV-infections for cervical cancer are very rare from developing countries and such data are limited to the few screening trials. Large screening trials provide such data as a by product. Some of the cases are prevented by screening and do not surface as invasive cancers at all. Also, pre-invasive lesions are detected almost entirely by screening. Screening causes selection bias if attendance in or effectiveness of screening is correlated with the risk factors. The aim of this study was to quantify the influence of screening on risk factors for cervical cancer. Materials and Methods: Our material stems from a rural cohort of 80,000 women subjected to a randomised screening trial. The effect of screening on the incidence of cervix cancer was estimated with reference to socio-demographic and reproductive risk factors of cervical cancer. We compared these risks with the incidence of cancer in the randomised control population by the same determinants of risk. Results: The results in the screening arm compared to the control arm showed that the women of low SES and young age were benefitting more than those of high SES and old age. The relative risk by age (30-39 vs 50-59) was 0.33 in the control arm and 0.24 in the screening arm. The relative risk by education (not educated vs educated) was 2.8 in the control arm and 1.8 in the screening arm. The previously married women did not benefit (incidence 113 and 115 per 100,000 women years in control vs screening arms) whereas the effect was substantial in those married (86 vs 54). Conclusions: The results in controls were consistent with the general evidence, but results in attenders and nonattenders of the screening arm showed that screening itself and self-selection in attendance and effectiveness can influence the effect estimates of risk factors. The effect of cervical cancer screening programmes on the estimates of incidence of cervical cancer causes bias in the studies on etiology and, therefore, they should be interpreted with caution.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.610-615
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• 2005

Visual servoing is the fusion of results from many elemental areas including high-speed image processing, kinematics, dynamics, control theory, and real-time computing. It has much in common with research into active vision and structure from motion, but is quite different from the often described use of vision in hierarchical task-level robot control systems. We present a new approach to visual feedback control using image-based visual servoing with the stereo vision in this paper. In order to control the position and orientation of a robot with respect to an object, a new technique is proposed using a binocular stereo vision. The stereo vision enables us to calculate an exact image Jacobian not only at around a desired location but also at the other locations. The suggested technique can guide a robot manipulator to the desired location without giving such priori knowledge as the relative distance to the desired location or the model of an object even if the initial positioning error is large. This paper describes a model of stereo vision and how to generate feedback commands. The performance of the proposed visual servoing system is illustrated by the simulation and experimental results and compared with the case of conventional method for dual-arm robot made in Samsung Electronics Co., Ltd.

• Journal of Biomedical Engineering Research
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• v.35 no.3
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• pp.50-54
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• 2014

It is being tried to control robot arm using brain signal in the field of brain-machine interface (BMI). This study is focused on applying guidance laws for efficient robot arm control using 3D coordinates obtained from Magnetoencephalography (MEG) signal which represents movement of upper limb. The 3D coordinates obtained from brain signal is inappropriate to be used directly because of the spatial difference between human upper limb and robot arm's end-effector. The spatial difference makes the robot arm to be controlled from a third-person point of view with assist of visual feedback. To resolve this inconvenience, guidance laws which are frequently used for tactical ballistic missile are applied. It could be applied for the users to control robot arm from a first-person point of view which is expected to be more comfortable. The algorithm which enables robot arm to trace MEG signal is provided in this study. The algorithm is simulated and applied to 6-DOF robot arm for verification. The result was satisfactory and demonstrated a possibility in decreasing the training period and increasing the rate of success for certain tasks such as gripping object.

• Physical Therapy Korea
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• v.26 no.2
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• pp.61-68
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• 2019

Background: Forward head posture (FHP) is a postural alignment of the cervical vertebrae that leads to increased gravitational load on cervical segmental motions. The overhead arm lift test assesses the ability to actively dissociate and control low cervical flexion and move the shoulders through overhead flexion. Objects: The purpose of this study was to explore muscle activities in the upper trapezius (UT), serratus anterior (SA), sternocleidomastoid (SCM), and lower trapezius (LT) alongside changes in head position during the overhead arm lift test in individuals with FHP. Methods: Fifteen subjects with forward head posture and fifteen subjects with normal subjcects were enrolled in this study. The patients performed the overhead arm lift test, and muscle activities of the UT, SCM, SA, and LT were measured using surface electromyography and by evaluating changes in head position. Independent t-tests were used to detect significant differences between the two groups and Cohen's d was calculated to measure the size of the mean difference between the groups. Results: The FHP group demonstrated significantly increased muscle activity of the UT ($32.46{\pm}7.64$), SCM ($12.79{\pm}4.01$), and LT ($45.65{\pm}10.52$) and significantly decreased activity in the SA ($26.65{\pm}6.15$) than the normal group. The change in head position was significantly higher in the FHP group ($6.66{\pm}2.08$) than the normal group. Effect sizes for all parameters assessed were large between the two groups. Conclusion: The subjects with excessive FHP displayed were unable to fix their heads in position during the overhead arm lift test. The overhead arm lift test can thus be used in clinical settings to confirm control of the neck in these subjects.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.684-686
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• 1998

This paper consider fuzzy control of a single-inverted pendulum attached to the tip end of a rotating arm driven by a direct driven motor. Control objectives stabilization of the pendulum at the upright position and regulation of the arm at an arbitrary specified position. Fuzzy control is an effective method to achieve multiple control objectives in control of nonlinear systems. In this paper, fuzzy logic control is proposed to obtain increased control performance and stability.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.105-108
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• 1993

This paper is concerned with a two-degree-offreedom control system design for a flexible arm, a two-degree-of-frecdom control system can achieve a robust stability specification and a control performance specification independently. By this property we improve the control performance with maintaining the same robust stability level as that of the onc-dcgree-of-freedom control system. At First we design a two-degree-of-fteedom control system which includes a feedforward controller and a feedback controller. The feedforward controller can be given by specifying a transfer function of a dcsired closed-loop model. We obtain a feedback controller by solving a mixed sensitivity problem. Several numerical results show that two-degree-of-freedom control systems acheive a better control performance than that of one-degree-of-freedom control systems.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.884-889
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• 1990

In this paper, a new hybrid position control algorithm for the direct drive arm is proposed. The proposed control is composed of discrete feedforward component and continuous feedback component. The discrete component is the nominal torque which approximately compensates the strong nonlinear coupling torques between the links, while the continuous control is a modified version of sliding mode control which is known to have a robust property to the disturbances of system. For the proposed control law, we give sufficient condition which guarantees the bounded tracking error in spite of the modeling errors, and the efficiency of the proposed algorithm is demonstrated by the numerical simulation of a three link manipulator position control with payloads and parameter errors.