• Journal of Broadcast Engineering
• /
• v.25 no.3
• /
• pp.405-417
• /
• 2020

Due to the popularization of the Extended Reality, research is actively underway to implement human motion in real-time 3D animation. In particular, Microsoft developed Kinect cameras for 3D motion information can be obtained without the burden of facilities and with simple operation, real-time animation can be generated by combining with 3D formats such as FBX. Compared to the marker-based motion capture system, however, Kinect has low accuracy due to its lack of estimated performance of joint information. In this paper, two algorithms are proposed to correct joint estimation errors in order to realize natural human motion in motion capture animation system in Kinect camera-based FBX format. First, obtain the position information of a person with a Kinect and create a depth map to correct the wrong joint position value using the human body segment length constraint information, and estimate the new rotation value. Second, the pre-set joint motion range constraint is applied to the existing and estimated rotation value and implemented in FBX to eliminate abnormal behavior. From the experiment, we found improvements in human behavior and compared errors between algorithms to demonstrate the superiority of the system.

• Journal of KSNVE
• /
• v.8 no.5
• /
• pp.964-973
• /
• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• Clinics in Shoulder and Elbow
• /
• v.9 no.1
• /
• pp.89-95
• /
• 2006

Purpose: Arthroscopic repair of rotator cuff tears are many techniques that have been developed to improve the initial postoperative strength of the repair. There was a doubt that current arthroscopic cuff repairs using a single row of suture anchors reproduce insufficient area of the anatomic cuff insertion, and concerns about failure of fixation often lead surgeons to limit early motion. Newer technique of double-row repair in arthroscopic treatment may provide initial stronger fixation and more contact with bone at the repair site than single-row repair did. We studied the comparison between clinical outcomes of arthroscopic single- and double-row repair in cuff tears at 1year postoperatively. Materials and methods: We retrospectively analyzed 40 shoulders with single-row repair and 38 shoulders with double-row repair of full-thickness rotator cuff tears between May 2002 and October 2004. Out of total 78 shoulders, 42 (54%) were male patients and 36 (46%) were female patients and the mean age at surgery was 56 years. All patients were diagnosed by physical examination and MRI. At 1year' follow-up after operation, we evaluated with the ASES and the Constant scoring system, and measured muscle power of abduction, internal and external rotation of the affected shoulder then compared with each other. Results: Mean ASES scores and Constant scores in double-row repair group improved more than single-row repair group significantly at 1year postoperatively. Muscle power of abduction and internal rotation, especially abduction power, improved more significantly in double-row repair group than in single-row repair. Conclusion: Arthroscopic double-row repair for the full thickness rotator cuff tear may be a superior technique, which showed better clinical outcomes and restoration of muscle power compared with single-row repair at relatively short period of postoperative follow-up. Restoration of footprint close to normal anatomy by double-row repair seems to play an important role in the recovery of muscle strength.

• Journal of Navigation and Port Research
• /
• v.46 no.3
• /
• pp.280-288
• /
• 2022

This study examined the diagnostics of abnormalities and faults of equipment, whose rotational speed changes even during regular operation. The purpose of this study was to suggest a procedure that can properly apply machine learning to the time series data, comprising non-stationary characteristics as the rotational speed changes. Anomaly and fault diagnosis was performed using machine learning: k-Nearest Neighbor (k-NN), Support Vector Machine (SVM), and Random Forest. To compare the diagnostic accuracy, an autoencoder was used for anomaly detection and a convolution based Conv1D was additionally used for fault diagnosis. Feature vectors comprising statistical and frequency attributes were extracted, and normalization & dimensional reduction were applied to the extracted feature vectors. Changes in the diagnostic accuracy of machine learning according to feature selection, normalization, and dimensional reduction are explained. The hyperparameter optimization process and the layered structure are also described for each algorithm. Finally, results show that machine learning can accurately diagnose the failure of a variable-rotation machine under the appropriate feature treatment, although the convolution algorithms have been widely applied to the considered problem.

• Tunnel and Underground Space
• /
• v.34 no.1
• /
• pp.1-14
• /
• 2024

An image-reconstruction technology, involving the deployment of an unmanned mobility equipped with high-speed LiDAR (Light Detection And Ranging) has been proposed to reconstruct the shape of abandoned mine. Unmanned mobility operation is remarkably useful in abandoned mines fraught with operational difficulties including, but not limited to, obstacles, sludge, underwater and narrow tunnel with the diameter of 1.5 m or more. For cases of real abandoned mines, quadruped robots, quadcopter drones and underwater drones are respectively deployed on land, air, and water-filled sites. In addition to the advantage of scanning the abandoned mines with 2D solid-state lidar sensors, rotation of radiation at an inclination angle offers an increased efficiency for simultaneous reconstruction of mineshaft shapes and detecting obstacles. Sensor and robot posture were used for computing rotation matrices that helped compute geographical coordinates of the solid-state lidar data. Next, the quadruped robot scanned the actual site to reconstruct tunnel shape. Lastly, the optimal elements necessary to increase utility in actual fields were found and proposed.

• Journal of Intelligence and Information Systems
• /
• v.24 no.2
• /
• pp.243-264
• /
• 2018

Although the worldwide battery market is recently spurring the development of lithium secondary battery, lead acid batteries (rechargeable batteries) which have good-performance and can be reused are consumed in a wide range of industry fields. However, lead-acid batteries have a serious problem in that deterioration of a battery makes progress quickly in the presence of that degradation of only one cell among several cells which is packed in a battery begins. To overcome this problem, previous researches have attempted to identify the mechanism of deterioration of a battery in many ways. However, most of previous researches have used data obtained in a laboratory to analyze the mechanism of deterioration of a battery but not used data obtained in a real world. The usage of real data can increase the feasibility and the applicability of the findings of a research. Therefore, this study aims to develop a model which predicts the battery deterioration using data obtained in real world. To this end, we collected data which presents change of battery state by attaching sensors enabling to monitor the battery condition in real time to dozens of golf carts operated in the real golf field. As a result, total 16,883 samples were obtained. And then, we developed a model which predicts a precursor phenomenon representing deterioration of a battery by analyzing the data collected from the sensors using machine learning techniques. As initial independent variables, we used 1) inbound time of a cart, 2) outbound time of a cart, 3) duration(from outbound time to charge time), 4) charge amount, 5) used amount, 6) charge efficiency, 7) lowest temperature of battery cell 1 to 6, 8) lowest voltage of battery cell 1 to 6, 9) highest voltage of battery cell 1 to 6, 10) voltage of battery cell 1 to 6 at the beginning of operation, 11) voltage of battery cell 1 to 6 at the end of charge, 12) used amount of battery cell 1 to 6 during operation, 13) used amount of battery during operation(Max-Min), 14) duration of battery use, and 15) highest current during operation. Since the values of the independent variables, lowest temperature of battery cell 1 to 6, lowest voltage of battery cell 1 to 6, highest voltage of battery cell 1 to 6, voltage of battery cell 1 to 6 at the beginning of operation, voltage of battery cell 1 to 6 at the end of charge, and used amount of battery cell 1 to 6 during operation are similar to that of each battery cell, we conducted principal component analysis using verimax orthogonal rotation in order to mitigate the multiple collinearity problem. According to the results, we made new variables by averaging the values of independent variables clustered together, and used them as final independent variables instead of origin variables, thereby reducing the dimension. We used decision tree, logistic regression, Bayesian network as algorithms for building prediction models. And also, we built prediction models using the bagging of each of them, the boosting of each of them, and RandomForest. Experimental results show that the prediction model using the bagging of decision tree yields the best accuracy of 89.3923%. This study has some limitations in that the additional variables which affect the deterioration of battery such as weather (temperature, humidity) and driving habits, did not considered, therefore, we would like to consider the them in the future research. However, the battery deterioration prediction model proposed in the present study is expected to enable effective and efficient management of battery used in the real filed by dramatically and to reduce the cost caused by not detecting battery deterioration accordingly.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.3
• /
• pp.217-222
• /
• 2016

This study investigates the design, analysis, and implementation of the square-root extended Kalman filter by using an algorithm derived by combining the Potter or Carlson algorithm with the modified Gram-Schmidt algorithm, for sensorless speed control of a permanent-magnet synchronous motor. The sensitivity of the Kalman filter to round-off errors is a well-known problem. A possible way to address this limitation is by combining the square-root concept and Kalman filter that can improve the numerical performance and solve instability-related problems such as divergence. This paper presents the design and analysis of the implementation of such a square-root extended Kalman filter. To demonstrate the performance of the proposed filter, experimental results under several operating conditions, such as high and low speeds, reversal rotation, detuned parameters and load test, have been analyzed. Further, code sizes and operation times have been compared. Experimental results establish the performance of the proposed square-root extended Kalman filter-based estimation technique for sensorless speed control of a permanent-magnet synchronous motor.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.5
• /
• pp.433-441
• /
• 1999

This paper presents a S-FES(Superconducting magnetic becuing Flywheel Energy Storage System) for the p purpose of replacing battery used to store the energy. Especially, the design elements of FES, such as the b beming, wheel mateηaI, and power converter, etc., are described. The design and manufacturing techniques of t the controllable IXlwer converter are proposed to generate the sinusoidal output current in the high speed operation and to get the const빠synchronous motor with halbach cuTay of high coesive I\d-Fe-B permanent magnet is used as the driver of F FES. The proposed S-FES system shows the stable rotation characteristics at high speed range about l 10,000[rpm]. To verify the validity of proposed system, the comparative study with the conventional ball b beming s~rstem is proceeded and it is well confirmed with the result of the lower friction losses of S-FES S system.

• Journal of Korean Society of Transportation
• /
• v.24 no.1 s.87
• /
• pp.109-120
• /
• 2006

Since the 1st of July, 2004, the public transport system of the Seoul metropolitan area has been rearranged. In the new system, bus lines are divided into 4 classes-wide area, arterial road, branch, and rotation lines with renewed fare system based on the total distance travelled. Since central control center known as the Bus Management System (BMS) integrates the entire system operation. it now becomes feasible to collect travel information and provide it to the users scientifically and systematically. The Purpose of this study is to forecast transit travel time using real-time traffic data coming from both buses and subway. This is significant contribution since provision of real-time transit information and easy access to it would most likely boost the use of mass transit system, alleviating roadway congestion in the metropolitan area.

• Archives of Craniofacial Surgery
• /
• v.14 no.2
• /
• pp.107-110
• /
• 2013

Background: Basal cell carcinoma (BCC) is the most common skin cancer. About 74% cases of basal cell cancer occur on the head and neck. Basal cell carcinoma on the face may have a higher degree of subclinical spread than tumors arising elsewhere. And incompletely excised BCCs become more aggressive when they recur. So the surgical removal and reconstruction of BCC located on the face are important to make perfect curing and cosmetic results. Methods: A retrospective study was done with 128 patients (137 cancers) who were treated with BCC on the face since 1987 to 2011. General data of these cases such as the primary site of cancer, age and sex of the patients, operative methods, and recurrence rate were reviewed. Results: The ratio of men to women was 1:1.4. And 86.9% of the patients with BCC were older than the age of 50 years with the mean age of 65.8 years. The distribution of facial basal cell carcinoma was on the nose, eyelids, cheek, and nasolabial fold. Surgical methods for treatment were local flap, full thickness skin graft, primary closure, and split thickness skin graft. Specifically, local flap consists of V-Y advancement flap, cheek advancement flap, limberg flap, forehead flap, nasolabial flap, rotation flap, transposition flap, bilobed flap, and island flap. Six cases recurred and all of them were treated with reoperation. Conclusion: The authors reviewed facial basal cell carcinoma cases in our hospital. This study might be helpful to choose appropriate operation method to manage BCC on face in Korea.