• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.119-135
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• 1987

For the determination of instantaneous centre of rotation in the mandibular movement, the habitual opening path was recorded on the sagittal tracing plate by a Gnathorecorder attached on the lower anterior teeth which was designed for this study. The opening path was demonstrated mathematically and the instantaneous centre of rotation in the opening path were calculated and plotted by computer programs, and then a computer graphic movement of the mandible was obtained according to the opening path. The hinge path of posterior border movement was graphied by the Gnathorecorder as well and demonstated mathematically. This hinge path was compared with the same obtained by Visitrainer to prove a reliability of the Gnathorecorder. The results obtained from this study were as follows. 1. The habitual opening path and hinge path obtained from the Gnathorecorder movement were expressed mathematically as follows: $y=0.11x^2-0.66x+3.09$ (equation of opening path), $y=0.04x^2+0.21x+3.71$ (equation of hinge path), and a kinematic hinge axis was not shown in the equation of kings path. 2. The early habitual opening movement of the mandible demonstrated almost a straight opening path or an arc motion with the larger radius and it's centre of rotation moved parallelly in the more rear and lower position than a kinematic hinge axis. 3. Instantaneous centre of rotation occured along with the translation of the condyle, and mandible was rotated around an axis in the close to the maximum opening and then moved toward the forward and upward position. 4. There were some similarities between the articular eminence and the movement pattern of a special point which was the kinematic hinge axis.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.6
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• pp.25-37
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• 2000

The trajectories of feature points can be defined by the correspondences between points in consecutive frames. The correspondence problem is known to be difficult to solve because false positives and false negatives almost always exist in real image sequences. In this paper, we propose a robust feature tracking algorithm considering incomplete trajectories such as entering and/or vanishing trajectories. The trajectories of feature points are determined by calculating the matching measure, which is defined as the minimum weighted Euclidean distance between two feature points. The weights are automatically updated in order to properly reflect the motion characteristics. We solve the correspondence problem as an optimal graph search problem, considering that the existence of false feature points may have serious effect on the correspondence search. The proposed algorithm finds a local optimal correspondence so that the effect of false feature point can be minimized in the decision process. The time complexity of the proposed graph search algorithm is given by O(mn) in the best case and O($m^2n$) in the worst case, where m and n arc the number of feature points in two consecutive frames. By considering false feature points and by properly reflecting motion characteristics, the proposed algorithm can find trajectories correctly and robustly, which has been shown by experimental results.

• Clinics in Shoulder and Elbow
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• v.23 no.2
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• pp.94-99
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• 2020

Background: Intra-articular distal humeral fractures can be surgically challenging. It remains under discussion whether open reduction and internal fixation (ORIF) or total elbow arthroplasty (TEA) is more beneficial for treatment of the elderly. This study aimed to compare the clinical and functional outcomes of ORIF and TEA for managing intra-articular distal humerus fractures in patients aged 65 years or older. Methods: Patients who underwent ORIF (n=28) or TEA (n=43) for in intra-articular distal humerus fracture between May 2008 and December 2018 were reviewed. Range of motion, Mayo Elbow Performance Score (MEPS), Disabilities of the Arm, Shoulder, and Hand (DASH) score, radiologic outcomes, and surgical complications were evaluated at the final follow-up visit. Results: The ORIF and TEA groups showed a mean arc of flexion-extension of 97°±21° and 101°±12°, respectively. The mean MEPS and DASH scores were 94±15 and 27±12 points, respectively, in the ORIF group and 81±27 and 47±28 points in the TEA group. This difference was statistically significant. The incidence of total complications was similar between the groups. Conclusions: In patients older than 65 years with intra-articular distal humerus fracture, ORIF had better outcomes than TEA.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1119-1127
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• 2010

In this paper, the design and nonlinear simulation of a multistable electromagnetic microactuator, which provides four stable equilibrium positions within its operating range, have been discussed. Quadstable actuator motion has been made possible by using both X- and Y-directional bistable structures with snapping curved beams. Two pairs of the curved beams are attached to an inner frame in both X- and Y-directions to realize independent bistable behavior in each direction. For the actuation of the actuator at the micrometer scale, an electromagnetic actuation method in which Lorentz force is taken into consideration was used. By using this method, micrometer-stroke quadstability in a plane parallel to a substrate was possible. The feasibility of designing an actuator that can realize quadstable motion by using the electromagnetic actuation method has been thoroughly clarified by performing nonlinear static and dynamic analyses and electrothermal coupled-field analysis of the multistable microactuator.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.410-418
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• 2015

A slider of the pantograph undergoes uneven and abnormal wear due to sliding contact with the catenary. In the case of rain, the loss of lubricant increases the frictional resistance for the reciprocating motion between the catenary and the slider, accelerating local wear. The slider in the winter should have good wear resistance, which can be achieved through alloy design. Uneven and abnormal wear were not observed in the results of a driving test using a wear resistant slider. It was found that the increased density of the slider enhanced the corrosive effects of Fe-Ti, preventing the occurrence of abnormal wear by maintaining the wear and arc resistance in the rainy season. Also, mechanical and electrical wear did not affect the composition of the slider, and this improved the wear resistance. Inaddition, the slider was applied to an entire train and was tested during driving; ananalysis of the correlation of the catenary was performed, including during the rainy season and the winter season.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.242-248
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• 2002

It is important to develop new effective technologies to increase the interruption capacity and to reduce the size of a UB(Gas Circuit Breakers). Major design parameters such as nozzle geometries and interrupting chamber dimensions affect the cooling of the arc and the breaking performance. But it is not easy to test real GCB model in practice as in theory. Therefore, a simulation tool based on a computational fluid dynamics(CFD) algorithm has been developed to facilitate an optimization of the interrupter. Special attention has been paid to the supersonic flow phenomena between contacts and the observation of hat-gas flow for estimating the breaking performance. However, there are many difficult problems in calculating the flow characteristics in a GCB such as shock wave and complex geometries, which may be either static or in relative motion. Although a number of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a GCB is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program using CFB-CAD integration technique based on Cartesian cut-cell method, which could reduce researcher's efforts to generate the mesh and achieve the accurate representation of the geometry designed by a CAD tools.

• Fashion & Textile Research Journal
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• v.8 no.1
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• pp.99-106
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• 2006

With the growing interest in pet dogs and pet dog's wear I used this study to compare and analyze the pattern used by each supplier and developed a new pattern for pet dogs' wear which is appropriate for pet dogs' body lines and movement. Test subjects were 91 pet dogs in Busan and after comparing 3 patterns from different suppliers, I developed the pattern reflecting pet dogs' body shapes and movement. Results are as follows; 1) As a result of analyzing measurements, it was found that pet dogs motion in walking on four feet, is different from that of people on two feet. For center measurements, their waist to bust length is longer than their waist to back length. The result of analysis shows that bust circumference impacts most other measurement results and it seems that better results are achieved if the bust line is taken into consideration when measuring bust back length, bust front length, neck base circumference, front leg arc, the length between lateral shoulder etc. 2) As a result of comparing suppliers' patterns, it was discovered that each supplier has different sizes for the same patterns and those sizes are not standardized across the board. Even if the same size of pattern was actually used in the production of pet dogs' wear by the individual companies, there were many variations in size for each item. 3) To develop a more standard pattern of pet dogs' wear, I collected and analyzed 3 patterns from each supplier and designed a new pattern, revising it three times. After test-wearing of the experimental pattern and the studied patterns, and comparing and analyzing the results, the studied pattern had similarly better estimation than the experimental one.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.27-47
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• 1992

Engineers have developed new instruments that aid in diagnosis and therapy Ultrasonic imaging has provided a nondamaging method of imaging internal organs. A complex transducer emits ultrasonic waves at many angles and reconstructs a map of internal anatomy and also velocities of blood in vessels. Fast computed tomography permits reconstruction of the 3-dimensional anatomy and perfusion of the heart at 20-Hz rates. Positron emission tomography uses certain isotopes that produce positrons that react with electrons to simultaneously emit two gamma rays in opposite directions. It locates the region of origin by using a ring of discrete scintillation detectors, each in electronic coincidence with an opposing detector. In magnetic resonance imaging, the patient is placed in a very strong magnetic field. The precessing of the hydrogen atoms is perturbed by an interrogating field to yield two-dimensional images of soft tissue having exceptional clarity. As an alternative to radiology image processing, film archiving, and retrieval, picture archiving and communication systems (PACS) are being implemented. Images from computed radiography, magnetic resonance imaging (MRI), nuclear medicine, and ultrasound are digitized, transmitted, and stored in computers for retrieval at distributed work stations. In electrical impedance tomography, electrodes are placed around the thorax. 50-kHz current is injected between two electrodes and voltages are measured on all other electrodes. A computer processes the data to yield an image of the resistivity of a 2-dimensional slice of the thorax. During fetal monitoring, a corkscrew electrode is screwed into the fetal scalp to measure the fetal electrocardiogram. Correlations with uterine contractions yield information on the status of the fetus during delivery To measure cardiac output by thermodilution, cold saline is injected into the right atrium. A thermistor in the right pulmonary artery yields temperature measurements, from which we can calculate cardiac output. In impedance cardiography, we measure the changes in electrical impedance as the heart ejects blood into the arteries. Motion artifacts are large, so signal averaging is useful during monitoring. An intraarterial blood gas monitoring system permits monitoring in real time. Light is sent down optical fibers inserted into the radial artery, where it is absorbed by dyes, which reemit the light at a different wavelength. The emitted light travels up optical fibers where an external instrument determines O2, CO2, and pH. Therapeutic devices include the electrosurgical unit. A high-frequency electric arc is drawn between the knife and the tissue. The arc cuts and the heat coagulates, thus preventing blood loss. Hyperthermia has demonstrated antitumor effects in patients in whom all conventional modes of therapy have failed. Methods of raising tumor temperature include focused ultrasound, radio-frequency power through needles, or microwaves. When the heart stops pumping, we use the defibrillator to restore normal pumping. A brief, high-current pulse through the heart synchronizes all cardiac fibers to restore normal rhythm. When the cardiac rhythm is too slow, we implant the cardiac pacemaker. An electrode within the heart stimulates the cardiac muscle to contract at the normal rate. When the cardiac valves are narrowed or leak, we implant an artificial valve. Silicone rubber and Teflon are used for biocompatibility. Artificial hearts powered by pneumatic hoses have been implanted in humans. However, the quality of life gradually degrades, and death ensues. When kidney stones develop, lithotripsy is used. A spark creates a pressure wave, which is focused on the stone and fragments it. The pieces pass out normally. When kidneys fail, the blood is cleansed during hemodialysis. Urea passes through a porous membrane to a dialysate bath to lower its concentration in the blood. The blind are able to read by scanning the Optacon with their fingertips. A camera scans letters and converts them to an array of vibrating pins. The deaf are able to hear using a cochlear implant. A microphone detects sound and divides it into frequency bands. 22 electrodes within the cochlea stimulate the acoustic the acoustic nerve to provide sound patterns. For those who have lost muscle function in the limbs, researchers are implanting electrodes to stimulate the muscle. Sensors in the legs and arms feed back signals to a computer that coordinates the stimulators to provide limb motion. For those with high spinal cord injury, a puff and sip switch can control a computer and permit the disabled person operate the computer and communicate with the outside world.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.137-147
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• 2014

Purpose : The purpose of this study is to verify the accuracy of dose delivery according to the patient's breathing cycle in Gated Volumetric Modulated Arc Therapy Materials and Methods : TrueBeam STxTM(Varian Medical System, Palo Alto, CA) was used in this experiment. The Computed tomography(CT) images that were acquired with RANDO Phantom(Alderson Research Laboratories Inc. Stamford. CT, USA), using Computerized treatment planning system(Eclipse 10.0, Varian, USA), were used to create VMAT plans using 10MV FFF with 1500 cGy/fx (case 1, 2, 3) and 220 cGy/fx(case 4, 5, 6) of doserate of 1200 MU/min. The regular respiratory period of 1.5, 2.5, 3.5 and 4.5 sec and the patients respiratory period of 2.2 and 3.5 sec were reproduced with the $QUASAR^{TM}$ Respiratory Motion Phantom(Modus Medical Devices Inc), and it was set up to deliver radiation at the phase mode between the ranges of 30 to 70%. The results were measured at respective respiratory conditions by a 2-Dimensional ion chamber array detector(I'mRT Matrixx, IBA Dosimetry, Germany) and a MultiCube Phantom(IBA Dosimetry, Germany), and the Gamma pass rate(3 mm, 3%) were compared by the IMRT analysis program(OmniPro I'mRT system software Version 1.7b, IBA Dosimetry, Germany) Results : The gamma pass rates of Case 1, 2, 3, 4, 5 and 6 were the results of 100.0, 97.6, 98.1, 96.3, 93.0, 94.8% at a regular respiratory period of 1.5 sec and 98.8, 99.5, 97.5, 99.5, 98.3, 99.6% at 2.5 sec, 99.6, 96.6, 97.5, 99.2, 97.8, 99.1% at 3.5 sec and 99.4, 96.3, 97.2, 99.0, 98.0, 99.3% at 4.5 sec, respectively. When a patient's respiration was reproduced, 97.7, 95.4, 96.2, 98.9, 96.2, 98.4% at average respiratory period of 2.2 sec, and 97.3, 97.5, 96.8, 100.0, 99.3, 99.8% at 3.5 sec, respectively. Conclusion : The experiment showed clinically reliable results of a Gamma pass rate of 95% or more when 2.5 sec or more of a regular breathing period and the patient's breathing were reproduced. While it showed the results of 93.0% and 94.8% at a regular breathing period of 1.5 sec of Case 5 and 6, it could be confirmed that the accurate dose delivery could be possible on the most respiratory conditions because based on the results of 100 patients's respiratory period analysis as no one sustained a respiration of 1.5 sec. But, pretreatment dose verification should be precede because we can't exclude the possibility of error occurrence due to extremely short respiratory period, also a training at the simulation and careful monitoring are necessary for a patient to maintain stable breathing. Consequently, more reliable and accurate treatments can be administered.

• Progress in Medical Physics
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• v.26 no.3
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• pp.127-136
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• 2015

The purpose of this study is to perform a dosimetric evaluation of amplitude-based respiratory gating for the delivery of volumetric modulated arc therapy (VMAT). We selected two types of breathing patterns, subjectively among patients with respiratory-gated treatment log files. For patients that showed consistent breathing patterns (CBP) relative to the 4D CT respiration patterns, the variability of the breath-holding position during treatment was observed within the thresholds. However, patients with inconsistent breathing patterns (IBP) show differences relative to those with CBP. The relative isodose distribution was evaluated using an EBT3 film by comparing gated delivery to static delivery, and an absolute dose measurement was performed with a $0.6cm^3$ Farmer-type ion chamber. The passing rate percentages under the 3%/3 mm gamma analysis for Patients 1, 2 and 3 were respectively 93.18%, 91.16%, and 95.46% for CBP, and 66.77%, 48.79%, and 40.36% for IBP. Under the more stringent criteria of 2%/2 mm, passing rates for Patients 1, 2 and 3 were respectively 73.05%, 67.14%, and 86.85% for CBP, and 46.53%, 32.73%, and 36.51% for IBP. The ion chamber measurements were within 3.5%, on average, of those calculated by the TPS and within 2.0%, on average, when compared to the static-point dose measurements for all cases of CBP. Inconsistent breathing patterns between 4D CT simulation and treatment may cause considerable dosimetric differences. Therefore, patient training is important to maintain consistent breathing amplitude during CT scan acquisition and treatment delivery.