• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.79-88
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• 2009

The objective of this study is to develop the new vehicle classification algorithm and minimize classification errors. The existing vehicle classification algorithm collects data from loop and piezo sensors according to the specification("Vehicle classification guide for traffic volume survey" 2006) given by the Ministry of Land, Transport and Maritime Affairs. The new vehicle classification system collects the vehicle length, distance between axles, axle type, wheel-base and tire type to minimize classification error. The main difference of new system is the "Wandering" sensor which is capable of measuring the wheel-base and tire type(single or dual). The wandering sensor obtains the wheel-base and tire type by detecting both left and right tire imprint. Verification tests were completed with the total traffic volume of 762,420 vehicles in a month for the new vehicle classification algorithm. Among them, 47 vehicles(0.006%) were not classified within 12 vehicle types. This results proves very high level of classification accuracy for the new system. Using the new vehicle classification algorithm will improve the accuracy and it can be broadly applicable to the road planning, design, and management. It can also upgrade the level of traffic research for the road and transportation infrastructure.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.159-166
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• 2009

The purpose of this study was to develop and automatic gait event detection algorithm using single accelerometer which is attached at the top of the shoe. The sinal vector magnitude and anterior-posterior(x-axis) directional component of accelerometer were used to detect heel strike(HS) and toe off(TO), respectively. To evaluate proposed algorithm, gait event timing was compared with that by force plate and kinematic data. In experiment, 7 subjects performed 10 trials level walking with 3 different walking conditions such as fast, preferred & slow walking. An accelerometer, force plate and 3D motion capture system were used during experiment. Gait event by force plate was used as reference timing. Results showed that gait event by accelerometer is similar to that by force plate. The distribution of differences were spread about $22.33{\pm}17.45m$ for HS and $26.82{\pm}14.78m$ for To and most error was existed consistently prior to 20ms. The difference between gait event by kinematic data and developed algorithm was small. Thus it can be concluded that developed algorithm can be used during outdoor walking experiment. Further study is necessary to extract gait spatial variables by removing gravity factor.

• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.779-791
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• 2009

The purpose of this study is to develop a program that computes the position of the instantaneous center of rotation while an object moves in a circular motion. For this study, a mathematical algorithm was developed and implemented on the experimental data. Data for pitching (40m carry) and putting (4m) strokes were obtained from a skilled female golfer. A computer program (Centering 1.0) calculated the experimental data and found the radius of the instantaneous center of rotation. When the data were taken broadly, the program produced an error distance of radius. When the data were divided gradually, the program produced a very close instantaneous center of rotation. On comparing pitching and putting strokes, putting was found to have a greater radius than pitching. The instantaneous centers of rotation of putting were not in the golfer's body rather, they were 3m away from the club head. The Centering 1.0 program can calculate the instantaneous center of rotation with at least three sets of experimental data.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.115-126
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• 2014

Purpose : Depending on a variety of therapeutic areas using MVCT(Megavoltage computed tomography) intra-and interfraction is to evaluate changes in patient position. Materials and Methods : In this study, head and neck, thorax, liver, and prostate tumor patients, 48 people with a full course of treatment for patients with various MVCT scan was performed. Average 60 per patient MVCT images were acquired and analyzed. Results : Interfraction error thorax and abdomen, and pelvis in the longitudinal difference was more than 3 mm. Intrafraction to see a change after the end of treatment MVCT taken, and the results confirmed Intrafraction 2 mm in motion around the longitudinal difference. In addition, due to changes in the movement before and after treatment, Inter-and Intrafraction difference was found. Conclusion : In the present study, the Head and Neck, Thorax, liver, prostate cancer in patients with inter-and intrafraction changes and target the appropriate fixtures to complete the outline of the margin would be helpful is considered.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.2
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• pp.137-144
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• 2015

In this paper, we present an inertial sensor-based gait analysis system to measure and analyze lower-limb movements. We developed an integral AHRS(Attitude Heading Reference System) using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE(Root Mean Square Error) of 1.08 and 1.72 degree in yaw and pitch angle. In order to evaluate the performance of our the gait analysis system, we compared the joint angle for the hip, knee and ankle with those provided by Vicon system. The result shows that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limb or gait analysis during the post-stroke recovery.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.201-209
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• 2015

The deformed degree of car body varies largely with the collision part from side collision of car-to-car. In case of deformation of car body caused by collision, the movement is different as speed energy changes to strain energy. Generally, in the analysis of traffic accident, the movement of car after the collision is analyzed by law of conservation of motion and the error of energy absorption rate along the deformation of car body can be calibrated by inputting coefficient of restitution, but it is current situation that coefficient of restitution applied by referring to the research results of forward collision and backward collision because the research results of side collision is rare. Vehicle model of finite element method applied by structure of car body and materials of each component was analyzed by explicit finite element method, and coefficient of restitution and collision detection time along contact part of side collision was drawn by analyzing the results. Analysis result acquired through the law of conservation momentum by applying finally-computed coefficient of restitution and crash detection time compared to collision result of actual vehicle. As a result, the reliability of analysis was higher than the existing analysis method were acquired when applying the drawn initial input value that used finite element method analysis model.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.2
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• pp.79-88
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• 2004

Gaze detection is to locate the position on a monitor screen where a user is looking by computer vision. Gaze detection systems have numerous fields of application. They are applicable to the man-machine interface for helping the handicapped to use computers and the view control in three dimensional simulation programs. In our work, we implement it with a computer vision system setting a IR-LED based single camera. To detect the gaze position, we locate facial features, which is effectively performed with IR-LED based camera and SVM(Support Vector Machine). When a user gazes at a position of monitor, we can compute the 3D positions of those features based on 3D rotation and translation estimation and affine transform. Finally, the gaze position by the facial movements is computed from the normal vector of the plane determined by those computed 3D positions of features. In addition, we use a trained neural network to detect the gaze position by eye's movement. As experimental results, we can obtain the facial and eye gaze position on a monitor and the gaze position accuracy between the computed positions and the real ones is about 4.8 cm of RMS error.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.141-148
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• 2011

Most of the previous works on scene change detection algorithm focus on the detection of abrupt rather than gradual changes. In general, gradual scene change detection algorithms require heavy computation. Some of those approaches don't consider the error factors such as flashlights, camera or object movements, and special effects. Many scenes change detection algorithms based on the histogram show better performances than other approaches, but they have computation load problem. In this paper, we proposed a scene change detection algorithm with fast and accurate performance using the vertical and horizontal blocked slice images and their macro block informations. We apply graph cut partitioning algorithm for clustering and partitioning of video sequence using generated spatio-temporal histogram. When making spatio-temporal histogram, we only use the central block on vertical and horizontal direction for performance improvement. To detect camera and object movement as well as various special effects accurately, we utilize the motion vector and type information of the macro block.

• Progress in Medical Physics
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• v.17 no.1
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• pp.40-46
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• 2006

Hepatoma is one of 3 most common malignancies in Korea, the survival rate is not improved since last decades because of delayed diagnosis and limited treatment conditions. Radiation was one of treatment options but the impact on the survival is not remarkable. High dose exposure to target area was suggested for improved effect but low tolerance dose of normal liver tissue is the main limited factor. IMRT is the advanced form of 3DCRT, for focusing high dose on target with minimal dose to surrounding normal tissues. Motion of the tumor by respiration, cardiac pulsation and peristalsis is the main treatment harrier of IMRT for treatment of hepatoma patients. Development of QA technique for acceptable geometrical uncertainties and dose error on target volume is essential for IMRT in clinical treatment but proper QA technique is not yet developed. This study compared the verification film dosimetry with measured dose in phantom and calculated dose in planning computer on exactly same conditions of patient treatments. Within 3% dose differences between 3 groups were confirmed. We suggest that our verification QA technique is easy, economic, iterative and acceptable in clinical application for advanced hepatoma patients.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.125-133
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• 2017

Time comparison is necessary for the verification and synchronization of the clock. Two-way satellite time and frequency (TWSTFT) is a method for time comparison over long distances. This method includes errors such as atmospheric effects, satellite motion, and environmental conditions. Ionospheric delay is one of the significant time comparison error in case of the carrier-phase TWSTFT (TWCP). Global Ionosphere Map (GIM) from Center for Orbit Determination in Europe (CODE) is used to compare with Bernese. Thin shell model of the ionosphere is used for the calculation of the Ionosphere Pierce Point (IPP) between stations and a GEO satellite. Korea Research Institute of Standards and Science (KRISS) and Koganei (KGNI) stations are used, and the analysis is conducted at 29 January 2017. Vertical Total Electron Content (VTEC) which is generated by Bernese at the latitude and longitude of the receiver by processing a Receiver Independent Exchange (RINEX) observation file that is generated from the receiver has demonstrated adequacy by showing similar variation trends with the CODE GIM. Bernese also has showed the capability to produce high resolution IONosphere map EXchange (IONEX) data compared to the CODE GIM. At each station IPP, VTEC difference in two stations showed absolute maximum 3.3 and 2.3 Total Electron Content Unit (TECU) in Bernese and GIM, respectively. The ionospheric delay of the TWCP has showed maximum 5.69 and 2.54 ps from Bernese and CODE GIM, respectively. Bernese could correct up to 6.29 ps in ionospheric delay rather than using CODE GIM. The peak-to-peak value of the ionospheric delay for TWCP in Bernese is about 10 ps, and this has to be eliminated to get high precision TWCP results. The $10^{-16}$ level uncertainty of atomic clock corresponds to 10 ps for 1 day averaging time, so time synchronization performance needs less than 10 ps. Current time synchronization of a satellite and ground station is about 2 ns level, but the smaller required performance, like less than 1 ns, the better. In this perspective, since the ionospheric delay could exceed over 100 ps in a long baseline different from this short baseline case, the elimination of the ionospheric delay is thought to be important for more high precision time synchronization of a satellite and ground station. This paper showed detailed method how to eliminate ionospheric delay for TWCP, and a specific case is applied by using this technique. Anyone could apply this method to establish high precision TWCP capability, and it is possible to use other software such as GIPSYOASIS and GPSTk. This TWCP could be applied in the high precision atomic clocks and used in the ground stations of the future domestic satellite navigation system.