Publications (12)6.53 Total impact
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Article: The concentrations of serum, plasma and platelet BDNF are all increased by treadmill VO₂max performance in healthy college men.
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ABSTRACT: The most current human-based studies in which brain-derived neurotrophic factor (BDNF) levels in the peripheral blood system are analyzed use it as an indicator that represents BDNF levels in the CNS. However, whether circulating BDNF (serum and plasma) is positively or inversely associated with cardiorespiratory fitness levels (VO(2max)) is still controversial, and no study has done to investigate exercise effects on the concentration of BDNF stored in circulating platelets which, in fact, store a large amount of circulating BDNF. Thus, the purpose of this study was to determine the relation between VO(2max) and all circulating BDNF levels (serum, plasma and platelets) in college male students (N=18; age, 19 ± 1 years; height, 173.22 ± 7.65 cm; weight, 78.25 ± 14.25 kg; body fat percent, 13.82 ± 5.68%). Dual X-ray energy absorptiometry whole body scan was used to measure their body composition. After the overnight fast, all participants were performed VO(2max) test, and their blood was collected at rest and immediately after the exercise. Our data resulted in significant increases in platelet counts and serum, plasma and platelet BDNF levels immediately after the exercise (p<0.01). VO(2max) had a significant negative correlation with serum BDNF, plasma BDNF and platelet BDNF at rest (p<0.05) but a significant positive correlation with serum, plasma BDNF, and platelet BDNF immediately after the exercise (p<0.01). However, our data show no correlation between VO(2max) and platelet count both at rest and immediately after the exercise. In conclusion, this is the first study showing that basal BDNF levels are inversely correlated with cardiorespiratory fitness levels but that the inverse correlations turn into positive correlations with all circulating BDNF levels immediately after the exercise. Moreover, it is the first time to provide evidence that platelet BDNF levels are also positively affected by the exercise. However, future studies will be needed to investigate what tissues provide BDNF into the circulating system and to elucidate the role of circulating BDNF.Neuroscience Letters 05/2012; 519(1):78-83. · 2.11 Impact Factor -
Article: Design and stability analysis of impedance controller for bilateral teleoperation under a time delay
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ABSTRACT: A new impedance controller is proposed for bilateral teleoperation under a time delay. The proposed controller does not need to measure or estimate the time delay in the communication channel using the force loop-back. In designing a stable impedance controller, absolute stability is used as a stability analysis tool, which results in a less conservative controller than the passivity concept. Moreover, in order to remove the conservatism associated with the assumption of infinite port impedances, the boundaries of human and environment impedance are set to finite values. Based on this, this paper proposes a parameter design procedure for stable impedance controllers. The validity of the proposed control scheme is demonstrated by experiments with a 1-dof master/slave system.Journal of Mechanical Science and Technology 04/2012; 18(7):1131-1139. · 0.45 Impact Factor -
Article: Independent and joint associations of cardiorespiratory fitness and muscle fitness with metabolic syndrome in Korean men.
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ABSTRACT: Higher cardiorespiratory fitness (CRF) and muscle fitness (MF) attenuate metabolic syndrome prevalence in men. However, associations of CRF and MF with metabolic syndrome were poorly understood in South Korean men. Therefore, this study aimed to examine the independent and joint associations of CRF and MF on metabolic syndrome prevalence in Korean men. Korean men (n=1,097, mean age=44 years) were recruited from the central areas of South Korea for this Preventive Health Study (PHS) between May, 2007, and October, 2008, and they underwent a health examination, maximal treadmill test, and five different muscle fitness tests for this study. From our data, separate age- and current smoking-adjusted logistic regression models revealed a graded inverse association of metabolic syndrome prevalence with CRF (P<0.0001) and MF (P<0.0001). The association of MF with metabolic syndrome remained significant and became attenuated with further adjustment, for CRF (P=0.02). However, the association of CRF with metabolic syndrome remained unchanged when adjusted for MF (P<0.0001). In the joint analysis using the low-strength and CRF unfit group as the baseline, the odds ratios (95% confidence intervals) for having metabolic syndrome were 0.52 (0.26-1.05) for the high-strength and CRF unfit group, 0.39 (0.24-0.65) for the low-strength and CRF fit group, and 0.28 (0.17-0.46) for the high-strength and CRF fit group. Both cardiorespiratory fitness and muscle fitness showed independent and joint inverse associations with metabolic syndrome prevalence in Korean adult men.Metabolic syndrome and related disorders 03/2011; 9(4):273-9. -
Article: Influence of performance level on anaerobic power and body composition in elite male judoists.
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ABSTRACT: This study examined the relationship between 30-second anaerobic power and body composition by performance level in elite Judoists. During a 3-month period, 10 male Korean Judo national team athletes (NT), 26 male university varsity team athletes (VT), and 28 male junior varsity team athletes (JT) were assessed for 30-second anaerobic power and body composition at the Youngin University. Anaerobic power was measured using a 30-second Wingate test. Body composition was assessed via bioelectric impedance analysis in standardized conditions using BioSpace (Korean)-specific prediction formulas. All testing occurred at the beginning of the winter nonseason period but excluded a brief weight-loss period before the competition phase. Anaerobic power measures were significantly greater (p < 0.05) in NT and VT than in JT. Fat-free mass (FFM), muscle mass (MM), and total body water in JT were also greater than in VT and JT (p < 0.05). Muscle mass in VT was significantly lower than in NT (p < 0.05). Fat-free mass in NT was strongly correlated to mean and peak anaerobic power (r = 0.77, p = 0.009; r = 0.87, p < 0.001, respectively). Varsity team athletes also indicated a moderate association between FFM and peak and mean anaerobic power (r = 0.63, p < 0.001; r = 0.48, p = 0.013, respectively). However, relationship between FFM and anaerobic power was not statistically significantly correlated in JT (r = 0.14, p = 0.470; r = 0.23, p = 0.232, separately). In conclusion, our data indicated that anaerobic power is closely correlated with increase in FFM and MM and was different dependent among performance levels. Further research in the field is warranted to elucidate the Judo-specific relationship between FFM and performance.The Journal of Strength and Conditioning Research 10/2010; 25(5):1346-54. · 1.83 Impact Factor -
Article: Association among basal serum BDNF, cardiorespiratory fitness and cardiovascular disease risk factors in untrained healthy Korean men.
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ABSTRACT: Evidence suggests that serum brain-derived neurotrophic factor (serum BDNF) can be affected by cardiorespiratory fitness (CRF), but this relationship is far from clear. Recent reports show an inverse relationship between serum BDNF and CRF in healthy individuals, and other studies suggest a possible association between serum BDNF and cardiovascular disease. However, the possible interaction between serum BDNF, CRF, and cardiovascular disease risk has not been studied. The purpose of this study was to examine the association among serum BDNF, CRF, and cardiovascular disease risk factors in healthy men. The investigation involved a large sample of men (n = 995, age range: 20-76 years) who live in the central area of South Korea and were recruited into the Preventive Health Study. Our study showed a significant inverse relationship between serum BDNF and relative VO(2)max (r = -0.412, p < 0.0001) and heart rate reserve (r = -0.194, p < 0.0001). Serum BDNF was positively correlated with body mass index (r = 0.80, p < 0.0001), total cholesterol (r = 0.185, p < 0.0001), and triglyceride (r = 0.320, p < 0.0001). Our data suggest that serum BDNF may be associated with effects of increased CRF on cardiovascular disease. However, more research is clearly needed before a determination of whether, and to what extent, serum BDNF may be responsible for some of the health benefits associated with CRF.Arbeitsphysiologie 09/2010; 111(2):303-11. · 2.15 Impact Factor -
Conference Proceeding: A PID-Type Robust Controller Design for Industrial Robots with Flexible Joints
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ABSTRACT: In this paper, a robust control algorithm is proposed for industrial robots having flexible joints. A link with flexible joint is modeled as a two-mass system, which can be represented in terms of a cascade system. The controller is designed based on a recursive process for the cascade system and the robustness is obtained in each step of the design. Especially, we design the real control part having a PID-type control structure by including the integral action. The designed robust controller has capabilities of vibration suppression and robustness against disturbances and model uncertainties, e.g., perturbations due to the changes of the payload. The effectiveness of the designed controller is investigated through several simulations on a model of industrial robot and also shown through experiments using a HILS (hardware in the loop simulation) system incorporating a small size manipulatorSICE-ICASE, 2006. International Joint Conference; 11/2006 -
Conference Proceeding: Impedance controller design of Internet-based teleoperation using absolute stability concept
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ABSTRACT: Relationships between impedance parameters and scaling factors are derived using absolute stability and passivity. For this, the teleoperation system is represented as a two-port model with a. hybrid matrix. Design procedure of the impedance parameters for the absolute stability of the teleoperator under the time delay is proposed. The validity of the proposed control scheme is demonstrated by experiments with a 1-dof master/slave system connected through the Internet.Intelligent Robots and Systems, 2002. IEEE/RSJ International Conference on; 02/2002 -
Conference Proceeding: Sliding-mode-based impedance controller for bilateral teleoperation under varying time-delay
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ABSTRACT: In the previous works, we have proposed new control schemes based on the sliding mode control and impedance control in order to cope with varying time delays. However, the previous controller needs local compliance to reduce contact forces between the slave and environment. In this paper, we modify the previous one to have a sliding surface for the slave include an impedance model. Since the nonlinear gain of the sliding controller is independent of the time delay as in the previous proposed controllers, it is not necessary to measure or estimate the time delay to implement the controller. The validity of the proposed control scheme is demonstrated by experiments with a 1-DOF master/slave system connected through the Internet.Robotics and Automation, 2001. Proceedings 2001 ICRA. IEEE International Conference on; 02/2001 -
Conference Proceeding: An online trajectory modifier for the base link of biped robots to enhance locomotion stability
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ABSTRACT: This paper proposes an online trajectory modification scheme for biped robots to cope with uncertainty of their environment. The trajectory of the base link in the vertical direction is modified depending on the magnitude of zero moment point deviation from its safety boundary such that appropriate angular moment is generated to maintain stable walking. The modified trajectory then gradually returns to the original trajectory using a 3rd- or 5th-order interpolation polynomial. We expand the gravity-compensated inverted pendulum mode to generate the base-link trajectory not only for single support phases but also double support phases. In the simulations to evaluate the proposed scheme, an impedance controller is used to control a 6-DOF biped robot and the environment of the biped robot is assumed to consist of nonlinear and linear compliant contact models. The simulation results show that the proposed online trajectory modification scheme effectively enhances the stability of locomotionRobotics and Automation, 2000. Proceedings. ICRA '00. IEEE International Conference on; 02/2000 -
Conference Proceeding: An On-Line Trajectory Modifier for the Base Link of Biped Robots to Enhance Locomotion Stability.
Proceedings of the 2000 IEEE International Conference on Robotics and Automation, ICRA 2000, April 24-28, 2000, San Francisco, CA, USA; 01/2000 -
Conference Proceeding: Sliding-mode controller for bilateral teleoperation with varying time delay
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ABSTRACT: Bilateral teleoperation systems connected to computer networks, such as Internet, have to deal with varying communication time delay. The entire system is easy to become unstable due to irregular time delay. In this paper, we design a sliding-mode controller for the slave and an impedance controller for the master. We propose a modified sliding-mode controller, in which the nonlinear gain can be set independently of the time delay variation. The proposed controller effectively compensates the effects of the varying time delay which deteriorates the performance of the regular sliding-mode controller. We illustrate the validity of the proposed controller using simulations with 1-DOF master/slave bilateral teleoperation systemAdvanced Intelligent Mechatronics, 1999. Proceedings. 1999 IEEE/ASME International Conference on; 02/1999 -
Article: Stable bilateral teleoperation under a time delay using a robust impedance control
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ABSTRACT: This paper presents a new impedance controller for a bilateral teleoperation under a time delay. In the proposed controller, a dynamic characteristic at the operator–master (slave–environment) interface is designed by a desired master (slave) impedance model. To cope with the uncertainty in the slave, an impedance model is put into a sliding surface of a sliding-mode-controller. A stability condition is derived from absolute stability concept, and a parameter tuning algorithm is proposed using this. The validity of the proposed control scheme is demonstrated by experiments with a 1-DOF master/slave system. Experimental results show that the proposed control method works well with robustness.Mechatronics.
Top co-authors
Top Journals
Institutions
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2012
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Yong-In University
Yŏng-dong, North Chungcheong, South Korea
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2011
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Korea National Sport University
Seoul, Seoul, South Korea
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1999–2002
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Hanyang University
- Division of Mechanical Engineering
Ansan, Gyeonggi, South Korea
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