• Journal of the Korean Society for Precision Engineering
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• 제32권4호
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• pp.377-386
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• 2015

Joint force/torque estimation by inverse dynamics is a traditional tool in biomechanical studies. Conventionally for this, kinematic data of human body is obtained by motion capture cameras, of which the bulkiness and occlusion problem make it hard to capture a broad range of movement. As an alternative, inertial motion sensing using cheap and small inertial sensors has been studied recently. In this research, the performance of inertial motion sensing especially to calculate inverse dynamics is studied. Kinematic data from inertial motion sensors is used to calculate ground reaction force (GRF), which is compared to the force plate readings (ground truth) and additionally to the estimation result from optical method. The GRF estimation result showed high correlation and low normalized RMSE(R=0.93, normalized RMSE<0.02 of body weight), which performed even better than conventional optical method. This result guarantees enough accuracy of inertial motion sensing to be used in inverse dynamics analysis.

• PNF and Movement
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• 제20권1호
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• pp.59-66
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• 2022

Purpose: The aim of this research was to verify the relationship between three-dimensional (3D) ground reaction force (GRF) and severity of leg length discrepancy (LLD) while walking at a normal speed. It used a 3D motion analysis system with force platforms in standing workers with LLD. Methods: Subjects comprising 45 standing workers with LLD were selected. Two force platforms were used to acquire 3D GRF data based on a motion analysis system during gait. Vicon Nexus and Visual3D v6 Professional software were used to analyze kinetic GRF data. The subjects were asked to walk on a walkway with 40 infrared reflective markers attached to their lower extremities to collect 3D GRF data. Results: The results indicated the maximal force in the posterior and lateral direction of the long limb occurring in the early stance phase during gait had significant positive correlation with LLD severity (r = 0.664~0.738, p <0.01). In addition, the maximal force medial direction of the long limb occurring in the late stance phase showed a highly positive correlation with the LLD measurement (r = 0.527, p <0.01). Conclusion: Our results indicate that greater measured LLD severity results in more plantar pressure occurring in the foot area during heel contact to loading response of the stance phase and the stance push-off period during gait.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.385-386
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• 2023

In this application study, field pilot tests were performed to evaluate the validity of a proposed formula between the exerted electrical energy and SPT N-value based on the result of the basic study. Measurement sensors and recording system were developed to obtain exerted motor current and drilling depth in a field. By using the correlation formula proposed in the basic study, the measured motor current and boring speed were applied to predict SPT N-value and the predicted N-values were compared to SPT N-value of site exploration. From the comparisons it is verified that the exerted electrical energy to bore ground might be used to predict SPT N-value and pile tip location.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제17권5호
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• pp.490-499
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• 2006

In this paper, we present the newly developed propagation toss model of a long range maritime communication channel, measured by a ground to air flight test, and discuss its validity compared with the predictive value based on the spherical earth reflection model. To measure the propagation loss, actual flight test was performed in the Yellow Sea and the measurement of receiving signal strength was made for overall test range. As far as the test condition is concerned, it is expected that the receiving signal strength must be interfered with the reflected wave by an island existing around the reflection point. Therefore we introduce some modifications on the conventional spherical earth reflection model by including the effect due to the reflected wave from the island. And then, we compare the path loss measured by flight test with that one analyzed by the spherical earth reflection model accounting for reflected wave of the island. As a result of the comparison, it is verified to predict the path loss accurately by the spherical earth reflection model including the effect due to the reflected wave from an island for a long range ground to air communication.

• Tunnel and Underground Space
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• 제34권3호
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• pp.196-207
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• 2024

In this study, a comprehensive management plan was proposed to ensure the stability of the existing subway when constructing ground structures adjacent to the subway. In the first step, the measurement inspection cycle is selected through proximity evaluation, in the second step, the stability of existing subway and station structures such as displacement and stress is reviewed through 3D numerical analysis considering the construction stage and groundwater influence, and in the third stage, the safety of train operation was reviewed by examining the track stability, and based on the numerical analysis results in the fourth stage, the displacement concentration section was selected as an intensive management section and it was proposed that intensive measurement management be performed.

• Transactions of the Korean Society of Automotive Engineers
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• 제3권3호
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• pp.1-8
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• 1995

In the companion paper of the present paper, a coast down test method to determine the resistance forces on running vehicle based on the distance-time measurement was explained along with the suggestions to improve its accuracy and testing methodology. In the present paper some of the suggestions discussed previously are implemented and actually road tested to see the applicability of the improved method(short distance method) in the field. From the results. it is shown that the short distance method which requires only 600m long proving ground road gives at least comparable results on the accuracy compared to the original S-t method which requires 2000m. It is hoped that the present method be further refiend to give more accurate results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.218-221
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• 2005

Grounding electrodes as discharge paths to the earth are normally used to ensure the safety of human body and facilities from the over-voltages in distribution power system, and each grounding mode has a prescribed ground resistance value respectively which is applied by the utilities. As the various electrodes for distribution power system are recently developing to improve the performance of them and resolve the problem of space restriction, it is necessary to measure and investigate the safety of human body of developed electrodes. Therefore, in this paper, we provide briefly a technical comparison of two standards, i.e. IEEE Std 80 and the IEC 479-1, and describe the configuration of safety measurement system which can measure the step voltage and the touch voltage of grounding electrodes based on IEEE Std 80.

• Transactions of the Korean Society of Automotive Engineers
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• 제5권4호
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• pp.21-28
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• 1997

The vehicle handling performances have a close relation with the driver's safety. And the CAT(Computer aided testing) system has been introduced as a powerful tool for improving the handling performances. In this study, a CAT system for effectively measuring and analysing the handling performances is developed based on the windows GUI(Graphic user interface) environment. Especially, in order to derive a lot of significant handling performance parameters from a series of proving ground tests, the CAT system has various functions related to real time measurement, time domain analysis, frequency domain analysis, steady state analysis and so on.

• The Journal of Pediatrics of Korean Medicine
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• 제30권1호
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• pp.32-39
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• 2016

Objectives To evaluate the effectiveness of allergic rhinitis treatment, and to set the ground in clinical studies, adequate outcome measures must be established. Thus, this study was designed to develop useful criteria based on those that have been suggested, and those that we are using today. Methods To assess outcome measures used in allergic rhinitis in Korean medicine, related articles found in Korea Traditional Knowledge Portal from 2000-2015 were evaluated. Then pattern identification and outcome measures were reviewed in each study. Results Among 27 studies, we have found 24 studies used subjective symptoms as outcome measures, 9 studies used quality of life, and most of allergic rhinitis were caused by Spleen-Gi deficiency. Conclusions It is necessary to develop outcome measures that directly reflect pattern identifications in Korean medicine, and those measures need to be further evaluated for their applicability, validity and sensitivity.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.891-892
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• 2006

Photoplethsymogram (PPG) drifts due to the changes in respiration and blood perfusion as well as external light. This hinders a proper PPG measurement. We controlled DC drifts by controlling the signal ground of PPG signals. A microprocessor-based system successfully controlled DC drifts of PPG signals.