• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.650-657
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• 2013

This study uses a muscle activation sensor and elbow joint model to develop an estimation algorithm for human elbow joint torque for use in a human-robot interface. A modular-type MVS (Muscle Volume Sensor) and calibration algorithm are developed to measure the muscle activation signal, which is represented through the normalization of the calibrated signal of the MVS. A Hill-type model is applied to the muscle activation signal and the kinematic model of the muscle can be used to estimate the joint torques. Experiments were performed to evaluate the performance of the proposed algorithm by isotonic contraction motion using the KIN-COM$^{(R)}$ equipment at 5, 10, and 15Nm. The algorithm and its feasibility for use as a human-robot interface are verified by comparing the joint load condition and the torque estimated by the algorithm.

• Journal of Korea Multimedia Society
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• v.15 no.5
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• pp.606-614
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• 2012

Face detection using AdaBoost algorithm is one of the fastest and the most robust face detection algorithm so many improvements or extensions of this method have been proposed. However, almost all previous approaches deal with only frontal face and suffer from limited discriminant capability for inclined face because these methods apply the same features for both frontal and inclined face. Also conventional approaches for detecting inclined face which apply frontal face detecting method to inclined input image or make different detectors for each angle require heavy computational complexity and show low detection rate. In order to overcome this problem, a method for detecting inclined face using JointBoost is proposed in this paper. The computational and sample complexity is reduced by finding common features that can be shared across the classes. Simulation results show that the detection rate of the proposed method is at least 2% higher than that of the conventional AdaBoost method under the learning condition with the same iteration number. Also the proposed method not only detects the existence of a face but also gives information about the inclined direction of the detected face.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.31-38
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• 2006

The purpose of this study was to investigate the effect of changing the steps height on the joint moment of lower extremity in stair-descent activity of elderly persons. Data were collected by 3-D cinematography and force platform. 9 male elderly subjects in the 60s and 70s participated in this study. All subjects performed a stair-descent in four different heights of stairs (10, 14, 18, 22cm) having 5 step staircase. The results were as follows. 1. For the step height of 22cm the maximum. plantarflexion moment was the smallest and the largest for the step height of 14cm. 2. There was not a statistical difference shown for the extension moment of the knee joint for the different height of steps. 3. There was not a statistical difference shown for the flexion moment of the hip joint for the varying height of steps but on average for the 18cm step this increased rapidly. 4. The smallest maximum. value for inversion moment was revealed for the step height of 10cm and this increased significantly for the step height of 22cm. 5. The smallest maximum. value for abduction moment of the hip joint was revealed for the step height of 10cm and this increased significantly for the step height of 22cm. 6. There was no significant difference shown for the maximum. abduction moment for the hip joint. The main conclusion is that there is a huge difference in the moment of the lower extremities for the elderly while walking down a stairs with a step height above 18 cm and that this moment increased or decreased rapidly under a condition of step height being 22cm. With the results from this research and related research of elderly walking upstairs it can be shown that the step height has a large role in the safety for the elderly.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.633-639
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• 2006

High temperature superconductor (HTS) winding coil is one of the key component in superconducting device fabrication. Double-pancake style coils are widely used for such application. High resistance between pancake coils greatly affects the machine design, operating condition and thus the stability. In order to reduce such resistance, experimentalists are looking for efficient and damage free coil connecting methods. In this respect, here we proposed parallel joining method to connect the coils. This is to do crossly joining with HTS tapes on two parallel HTS tapes. Joint samples between two parallel HTS tapes were prepared by using HTS tapes and current-voltage (I-V) characteristic curves were investigated at liquid nitrogen temperature i.e., 77.3 K. A 20 cm length joint connected between two parallel HTS tapes shows $32.5n{\Omega}$, for currents up to 250 A. A small HTS magnet, having two double pancake sub-coils connected together through new parallel joint method was fabricated and their current-voltage (I-V) characteristic curve was investigated. At 77.3K, critical current(Ic) of 97 A and resistance of $55n{\Omega}$ for currents upto 130 A were measured. At operating current 86 A lower than Ic, Joule heats generated in whole magnet and at joint region between sub-coils were 226 mW and 0.4 mW, respectively. Low Joule heat generation suggests that this joining method may be used to fabricate HTS magnet or windings.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.415-426
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• 2013

Condition assessment and monitoring of bridges is critical for safe passenger travel, public transportation, and efficient freight. In monitoring, displacement measurement capability is important to keep track of performance of bridge, in part or as whole. One of the most important parts of a bridge is the expansion joint, which accommodates continuous cyclic thermal expansion of the whole bridge. Though expansion joint is critical for bridge performance, its inspection and monitoring has not been considered significantly because the monitoring requires long-term data using cost intensive equipment. Recently, a wireless smart sensor network (WSSN) has drawn significant attention for transportation infrastructure monitoring because of its merits in low cost, easy installation, and versatile on-board computation capability. In this paper, a rapid wireless displacement monitoring system, wireless hybrid sensor (WHS), has been developed to monitor displacement of expansion joints of bridges. The WHS has been calibrated for both static and dynamic displacement measurement in laboratory environment, and deployed on an in-service highway bridge to demonstrate rapid expansion joint monitoring. The test-bed is a continuous steel girder bridge, the Founders Bridge, in East Hartford, Connecticut. Using the WHS system, the static and dynamic displacement of the expansion joint has been measured. The short-term displacement trend in terms of temperature is calculated. With the WHS system, approximately 6% of the time has been spent for installation, and 94% of time for the measurement showing strong potential of the developed system for rapid displacement monitoring.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.2
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• pp.59-66
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• 2022

The Joint Coastal Guard System is composed of a maritime surveillance system and a anti-coastal infiltration system, and is a system in which the Navy is mainly responsible for the maritime and the Army is responsible for the coast. We analyzed the operations effectiveness of the joint coastal guard system, in which various weapon systems of the army and navy are operated in a complex way, to the extent to which successful operation is possible against small targets. The operations effectiveness analysis was conducted by defining the operations effectiveness by operation type, configuring the simulation environment using METT-T elements, establishing the assumptions of the simulation scenario, conducting the simulation and analyzing the simulation results by weather condition. The simulation tools used were NORAM and EADSIM. As a result of the operations effectiveness analysis, the joint coastal guard system currently in operation showed a significant difference in operational success depending on the size of the target and weather conditions. This research can be used as useful data for establishing an effective joint coastal guard system and conducting systematic guard operations.

• Journal of muscle and joint health
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• v.25 no.1
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• pp.50-59
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• 2018

Purpose: The purpose of this study was to investigate the relationships among health behavior, wellness condition, and stage of change in health behavior by risk of cardiocerebrovascular diseases (CVD) in male office workers. Methods: A total of 205 male office workers participated in the 2017 National Health Examination at a manufacturing/ R&D business in Seongnam and completed self-reported questionnaires. Results: There were significant differences in health behavior scores by risk of CVD (F=4.78, p=.009) and statistically significant differences in no smoking (F=5.86, p=.003), exercise (F=5.49, p=.005), and health checkup (F=4.39, p=.014). There were statistically significant differences in health behavior (t=-4.14, p<.001) and wellness condition (t=-2.61, p=.010) by the stage of change in health behavior. Health behavior had a weak positive correlation with wellness condition (r=.36, p<.001). Logistic regression analysis showed that, when adjusted for age and employment period, the probability of becoming attention or risk group was 11% lower for quitting smoking (OR 0.89, 95% CI 0.81~0.97, p=.006) and 18% lower for regular exercise (OR 0.82, 95% CI 0.70~0.95, p=.009). Conclusion: The direction of health management at the workplace should be changed to promote the wellness of all workers, not the management of the disease, and a health promotion program should be continued to emphasize health behaviors such as smoking cessation and regular exercise.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1115-1120
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• 2003

The recent tendency in the automobile industries is toward light weighting vehicle body to improve the problems by environmental pollution as well as improving fuel cost. The effective way to reduce the weight of vehicle body seems to be application of new materials for body structure and such trend is remarkable. Among the various materials for vehicle body, stainless steel sheet (for example, 301L and 304L), TRIP steel and cold rolled steel sheets are under the interests. However, in order to guarantee reliability of new material and to establish the long life design criteria of body structure, it is important and require condition to assess spot weldability of them and fatigue strength of spot welded lap joints which were fabricated under optimized spot welding condition. And, recently, a new issue in the design of the spot welded structure is to predict economically fatigue design criterion without additional fatigue tests. In general, for fatigue design of the spot-welded thin sheet structure, additional fatigue tests according to the welding condition, material, joint type, and fatigue loading condition are generally required. This indicates that much cost and time for it should be consumed. Therefore, in this paper, the maximum stresses at nugget edge of spot weld were calculated through nonlinear finite element analysis first. And next, obtained the ${\Delta}P-N_{f}$ relation through the actual fatigue tests on spot welded lap joints of similar and dissimilar high strength steel sheets. And then, the ${\Delta}P-N_{f}$ relation was rearranged in the ${\Delta}{\sigma}-N_{f}$ relation. From this ${\Delta}{\sigma}-N_{f}$ relation, developed the fatigue design technology for spot welded lap joints of them welded using the optimized welding conditions.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.1
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• pp.21-28
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• 2015

Background: The purpose is to investigate the immediate effects of kinesio taping on quadriceps induced fatigue by short-term squat. Methods: This research is cross-over designed study and conducted as a single-blind. Eleven students (Age: $18.91{\pm}0.49yrs$, height: $167.09{\pm}8.46cm$, $62.55{\pm}11.32kg$) were participated in this study. All the participants were applied short-term squat for inducing fatigue, and then intervented all three conditions (kinesio taping applied condition, placebo taping applied condition, non-taping applied condition). The interval of each intervention was at least a seven days to prevent carry-over effects. The participants were tested peak torque (isometric contracture) and active joint position sense (active JPS) pre-post intervention. A paired t-test was used to find the significance of pre-post intervention results and one-way ANOVA was used to find the significance between interventions with significant level as .05. Results: Peak torque was significantly increased on KT condition (p<.05). But there were no significant effects on active JPS. Because kinesio taping facilitates Ia afferent by tactile stimulation with stretched skin, reduced muscle power by short term squat which induce muscle fatigue was increased. But kinesio taping does not affect mechanoreceptor in muscles, induced active JPS by short-term squat had no changes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.321-327
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• 2017

In this study, to investigate the shape of the back bead as a weld quality parameter and to select the optimal condition of the root-pass TIG welding of a horizontal butt-joint, an experimental design and the response surface method (RSM) have been employed. Three parameters are used as input variables, which include the base current, peak current, and welding speed. The back bead width is selected as an output variable representing the weld quality, the target value of the width is 5.4 mm. Conducting the experiments according to the Box-Behnken experimental design, a $2^{nd}$ regression model for the back bead width was made, and the validation of the model was confirmed by using the F-test. The desirability function was designed through the nominal-the-best formula for the appropriate back bead width. Finally, the following optimal condition for welding was selected using the RSM: base current of 0.9204, peak current of 0.8676, and welding speed of 0.3776 in coded values. For verification, a test welding process under the optimal condition was executed and the result showed the back bead width of 5.38 mm that matched the target value well.