• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.2
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• pp.69-76
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• 2021

Background: Degenerative arthritis accounts for a large portion of the elderly, causing a lot of inconvenience in daily life. Total knee replacement (TKR) are performed to relieve pain in the knee joint. The purpose of this study was to determine whether knee joint stabilization exercises are effective in improving balance and walking ability in degenerative arthritis patients who have undergone TKR. Methods: A total of 30 TKR patients participated in this study. They were assigned to two groups. The experimental group, the group that underwent knee stabilization exercises, joint mobilization and general physical therapy. On the other hand, and the controlled group, the group that underwent joint mobilization and general physical therapy. All exercises were conducted thrice a week, for four weeks. The main balance outcomes were evaluated using the posture balance training system, while walking ability was assessed using a wireless 3-axis accelerometer. Results: The experimental group had significantly higher scores in postural stability testing (PST), limits stability testing, and waling ability. The post-intervention evaluation, there were significant differences in all variables between the two groups. However, no significant difference was noted in the foam eyes closed test in PST. Conclusion: This study suggests that knee joint stabilization exercises effectively improve the balance and walking ability of TKR patients. Thus, it could be presented as useful in clinical practice.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.353-360
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• 2022

Due to the dense and complicated working environment, the construction industry is susceptible to many accidents. Worker's fall is a severe problem at the construction site, including falling into holes or openings because of the inadequate coverings as per the safety rules. During the construction or demolition of a building, openings and holes are formed in the floors and roofs. Many workers neglect to cover openings for ease of work while being aware of the risks of holes, openings, and gaps at heights. However, there are safety rules for worker safety; the holes and openings must be covered to prevent falls. The safety inspector typically examines it by visiting the construction site, which is time-consuming and requires safety manager efforts. Therefore, this study presented a worker-driven approach (the worker is involved in the reporting process) to facilitate safety managers by developing integrated computer vision and inertia sensors-based mobile applications to identify openings. The TensorFlow framework is used to design Convolutional Neural Network (CNN); the designed CNN is trained on a custom dataset for binary class openings and covered and deployed on an android smartphone. When an application captures an image, the device also extracts the accelerometer values to determine the inclination in parallel with the classification task of the device to predict the final output as floor (openings/ covered), wall (openings/covered), and roof (openings / covered). The proposed worker-driven approach will be extended with other case scenarios at the construction site.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1890-1897
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• 2022

In this paper, we design a navigation filter for an underwater glider. Underwater gliders are low-cost, reusable, and can be used for a long time. Two types of filters are designed considering characteristics such as small size, low cost, and low power. The navigation filter estimates the reference velocity of the underwater glider's body frame based on the minimum sensor output. The sensor configuration of the first filter consists of an accelerometer, a magnetometer, and a depth sensor. the second filter include extra a gyroscope in the same configuration. The estimated velocity is fused with the attitude, converted into the velocity of the navigation frame and finally the position is estimated. To analyze the performance of the proposed filter, analysis was performed using Monte Carlo numerical analysis method, and the results were analyzed with standard deviation (1σ). Standard deviations of each filter's position error are 334.34m, 125.91m.

• Journal of Animal Science and Technology
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• v.65 no.4
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• pp.759-766
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• 2023

Visual estrus observation can only be confirmed at a rate of 50%-60%, which is lower than that obtained using a biosensor. Thus, the use of biosensors provides more opportunities for artificial insemination because it is easier to confirm estrus than by visual observation. This study determines the accuracy of estrus prediction using a ruminoreticular biosensor by analyzing ruminoreticular temperature during the estrus cycle and measuring changes in body activity. One hundred and twenty-five Hanwoo cows (64 with a ruminal biosensor in the test group and 61 without biosensors in the control group) were studied. Ruminoreticular temperatures and body activities were measured every 10 min. The first service of artificial insemination used gonadotropin-releasing hormone (GnRH)-based fixed-time artificial insemination protocol in the control and test groups. The test group received artificial insemination based on the estrus prediction made by the biosensor, and the control group received artificial insemination according to visual estrus observation. Before artificial insemination, the ruminoreticular temperature was maintained at an average of 38.95 ± 0.05℃ for 13 h (-21 to -9 h), 0.73℃ higher than the average temperature observed at -48 h (38.22 ± 0.06℃). The body activity, measured using an indwelling 3-axis accelerometer, averaged 1502.57 ± 27.35 for approximately 21 h from -4 to -24 h before artificial insemination, showing 203 indexes higher body activity than -48 hours (1299 ± 9.72). Therefore, using an information and communication techonology (ICT)-based biosensor is highly effective because it can reduce the reproductive cost of a farm by accurately detecting estrus and increasing the rate of estrus confirmation in cattle.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.4
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• pp.53-63
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• 2014

Moving context determination is an important issue to be resolved in a mobile computing environment. This paper presents a method for recognizing and classifying a mobile user's moving context by Euclidean distance similarity. In the proposed method, basic data are gathered using Global Positioning System (GPS) and accelerometer sensors, and by using the data, the system decides which moving situation the user is in. The decided situation is one of the four categories: stop, walking, run, and moved by a car. In order to evaluate the effectiveness and feasibility of the proposed scheme, we have implemented applications using several variations of Euclidean distance similarity on the Android system, and measured the accuracies. Experimental results show that the proposed system achieves more than 90% accuracy.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.1
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• pp.151-167
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• 1996

Temporary soft liners can be used to prevent chronic soreness from dentures or to aid in its treatment are as adjuncts in tissue conditioning, for temporary obturators, and to stabilize baseplate or surgical stent. The purpose of this study was to evaluate the shock absorption properties of several temporary soft denture liners using a free drop test with an accelerometer. The materials tested inclued Coe-comfort, Softone, Tissue conditioner and Viscogel. The specimens were fabricated with the thickness of 1, 2, 3mm and were stored in distilled water at $37^{\circ}C$ for a day, 1, 2, and 3 weeks. Six samples were made with each material for each test condition and the shock-absorbing behavior was evaluated according to material, thickness and duration. The results were as following : 1. Softone of 3mm thickness stored for a day showed the most excellent shock absorbability. 2. The shock absorbing behavior of duration according to materials and thickness showed a day to be the highest and decreased in 1 week, 2 weeks and 3 weeks in that order(p<0.05). And there was no significant difference between durations in Tissue conditioner. 3. The shock absorbability of thickness according to materials and duration showed 3mm to be highest and decreased in the order of 2mm, 1mm(p<0.05). 4. In comparison of the shock absorbability of temporary soft denture liners according to thickness, there was statistically significant difference between Softone and Visocgel, Tissue conditioner, Coe-comfort / Viscogel and Tissue conditioner, Coe-comfort in 1,2mm thickness, and between Softone, Viscogel and Tissue conditioner, Coe-comfort in 3mm thickness (p<0.05).

• KCI Concrete Journal
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• v.13 no.2
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• pp.10-18
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• 2001

The spectral analysis of surface waves (SASW) method, which is an in-situ seismic technique, has mainly been developed and used for many years to determine the stiffness profile of layered media (such as asphalt concrete and layered soils) in an infinite half-space. This paper presents a modified experimental technique for nondestructive evaluation of in-place cement mortar compressive strength in single-layer concrete slabs of rather a finite thickness through a correlation to surface wave velocity. This correlation can be used in the quality control of early age cement mortar structures and in evaluating the integrity of structural members where the infinite half space condition is not met. In the proposed SASW field test, the surface of the structural members is subjected to an impact, using a 12 mm steel ball, to generate surface wave energy at various frequencies. Two accelerometer receivers detect the energy transmitted through the medium. By digitizing the analog receiver outputs, and recording the signals for spectral analysis, surface wave velocities can be identified. Modifications to the SASW method includes the reduction of boundary reflections as adopted on the surface waves before the point where the reflected compression waves reach the receivers. In this study, the correlation between the surface wave velocity and the compressive strength of cement mortar is developed using one 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slab of 2,000 psi (140 kgf/$\textrm{cm}^2$) and two 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slabs of 3,000 psi (210 kgf/$\textrm{cm}^2$).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.541-546
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• 2005

Tracking control of an automatic pipe cutting robot (APCROMB) is studied. Using magnetic force APCROMB, which is designed and developed in Kyung Hee University, binds itself to the pipe and executes unmanned cutting process. The gravity effect on the movement of APCROMB varies as it rotates around the cylindrical pipe laid in the gravitational field. To maintain a constant velocity and consistent cutting performance against the varying gravitational effect, the authors adopt a multi-rate repetitive learning controller (MRLC), which learns the required effort to cancel the repetitive tracking errors caused by nonlinear effect. In addition to the varying gravity effect other types of nonlinear disturbances including backlash in the driving system and the slip between the wheels of APCROMB and the pipe also cause degradation in the cutting process. In order to identify those nonlinear disturbances the position estimation based on the encoder attached at the motor is not good enough. To identify the absolute angular position of APCROMB the authors propose the angular position estimation based on the signals from a MEMS-type two-axis accelerometer mounted on APCROMB. The tracking performances of APCROMB with a MRLC using the encoder-based position estimation is experimentally measured and results are shown. Also the difference between the encoder-based angular displacement measurement and the accelerometerbased angular displacement measurement is included.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.709-715
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• 2011

Chattering in cutting operations are usually a cumbersome part of the manufacturing process in mechanical. Particular, machining performance such as that of the boring process is limited by cutting condition at the movable components. Among various sources of chatter vibration, detrimental point in cutting condition is found a mechanical condition on overhang. It limits cutting speed, depth, surface roughness and tool wear failure as result because the all properties are varying with the metal removal process. In this case, we have to observe the resonance frequencies of a boring bar for continuous cutting. In the established research, boring bar vibration of cutting system has been measured with the aid of accelerometer. However, the inherent parameters of internal turning operations are severely limit for the real time monitoring on accelerometers. At this point, this paper is proposed other method for real time monitoring during continuous cutting with optical fiber at the inside of boring bar. This method has been used a plastic fiber in the special jig on boring bar by based on experimental modal analysis. In this study, improvement of monitoring system on continuous internal cutting was attempted using optical fiber sensor of inside type because usually chattering is investigated experimentally measuring the variation in chip thickness. It is demonstrated that the optical fiber sensor is possibility to measure of chattering with real time in boring process.

• Smart Structures and Systems
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• v.22 no.2
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• pp.133-137
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• 2018

Increasing interest in prognostics and health management has heightened the need for wireless sensor networks (WSN) with efficient power sources. Piezoelectric energy harvesters using Pb(Zr,Ti)O3 (PZT) are one of the candidate power sources for WSNs as they efficiently convert mechanical vibration energy into electrical energy. These types of devices are resonated at a specific frequency, which has a significant impact on the amount of energy harvested, by external vibration. Hence, precise prediction of mechanical deformation including modal analysis of piezoelectric devices is crucial for estimating the energy generated under specific conditions. In this study, an experimental vibrational system capable of controlling a wide range of frequencies and accelerations was designed to generate mechanical vibration for piezoelectric energy harvesters. In conjunction with MATLAB, the system automatically finds the resonance frequency of harvesters. A small accelerometer and non-contact laser displacement sensor are employed to investigate the mechanical deformation of harvesters. Mechanical deformation under various frequencies and accelerations were investigated and analyzed based on data from two types of sensors. The results verify that the proposed system can be employed to carry out vibration experiments for piezoelectric harvesters and measurement of their mechanical deformation.