• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.153-163
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• 2004

The control objective in hard disk drives is to move head as fast as possible to target track and position the head over the center of target track in the presence of external disturbances. The external shock or disk clamping error in manufacturing process causes the disk center to deviate from the disk rotation center. The disk shift acts on the control system as disturbance and degrades severely the performance of disk drives. In this paper, we present a new controller that compensates for the periodic disturbances very fast. The disturbance compensator is arranged in parallel with the state feedback controller. To avoid the interference with the state feedback controller, the compensator creates compensation signal without the feedback of system output until steady state. The pulse type controller is included additionally for improving the transient performance due to initial state. Finally, in order to demonstrate the superior performance of the proposed compensator. we present some experimental results using a commercially available disk drive.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.521-527
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• 2002

This paper presents a dynamic modeling and a robust PID controller design process for the wire bonder head assembly. For the modeling elements, the system is divided into electrical system, magnetic system, and mechanical system. Each system is modeled by using the bond graph method. The PID controller is used for high speed/high accuracy position control of the wire bonder assembly. The Taguchi method is used to evaluate the more robust PID gain combinations than conventional one. This study makes use of an L18 array with three parameters varied on three levels. Computer simulations and experimental results show that the designed PID controller provides more improved signal to noise ratio and reduced sensitivity than the conventional PID controller.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.1
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• pp.33-39
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• 2012

In this paper, we propose robot control interface using gaze recognition which is not limited by head motion. Most of the existing gaze recognition methods are working well only if the head is fixed. Furthermore the methods require a correction process per each person. The interface in this paper uses a camera with built-in infrared filter and 2 LED light sources to see what direction the pupils turn to and can send command codes to control the system, thus it doesn't need any correction process per each person. The experimental results showed that the proposed interface can control the system exactly by recognizing user's gaze direction.

• Physical Therapy Korea
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• v.28 no.1
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• pp.36-46
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• 2021

Background: It is reported that the proprioceptive sensation of patients with neck pain is reduced, and neck sensory-motor control training using visual feedback is reported to be effective. Objects: The purpose of this study is to investigate how sensorimotor control training for the cervical spine affects pain, function, and psychosocial status in patients with chronic cervical pain. Methods: The subjects consisted of 36 adults (male: 15, female: 21) who had experienced cervical spine pain for more than 6 weeks. An exercise program composed of cervical stabilization exercise (10 minutes), electrotherapy (10 minutes), manual therapy (10 minutes), and cervical sensorimotor control training (10 minutes) was implemented for both the experimental and the control groups. The cervical range of motion (CROM) and head repositioning accuracy were assessed using a CROM device. In the experimental group, the subjects wore a laser device on the head to provide visual feedback while following pictures in front of their eyes; whereas, in the control group, the subjects had the same training of following pictures without the laser device. Results: There were no statistically significant differences between the two groups in pain, dysfunction, range of motion, or psychosocial status; however, post-test results showed significant decreases after 2 weeks and 4 weeks compared to baseline (p < 0.01), and after 4 weeks compared to after 2 weeks (p < 0.01). The cervical joint position sense differed significantly between the two groups (p < 0.05). Conclusion: In this study, visual feedback enhanced proprioception in the cervical spine, resulting in improved cervical joint position sense. On the other hand, there were no significant effects on pain, dysfunction, range of motion, or psychosocial status.

• Korean Journal of Head & Neck Oncology
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• v.17 no.2
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• pp.169-173
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• 2001

Objectives: The p53 tumor suppressor gene encodes a nuclear transcription factor that is critical regulator of cell growth and proliferation through its action in cell-cycle checkpoint control. The wide variety of stressful stmuli which include DNA damage, hypoxia, heat shock, metabolic changes activate the p53 protein, which in turn drives a series of events that culminate either in cell cycle arrest or apoptosis. Mutations of the p53 gene is the most common genetic alteration in human cancer. This gene is altered in approximately 40-60% of head and neck cancers. Whereas the wild-type form of the p53 protein plays a central role in cell-cycle control in response to DNA damage, most of the mutant forms are unable to do so. The high levels of p53 protein expression in tissues are related to the increased cellular proliferative activity and may be associated with the poor clinical outcome. To determine whether the expression of the p53 protein has prognostic significance and is associated with patterns of treatment failure in head and neck squamous cell carcinoma (HNSCC), We analyzed p53 overexpression in 40 cases of HNSCC. Materials and Methods: Immunohistochemical analysis with a monoclonal antibody (DO7) specific for p53 protein was used to detect expression of the protein in formalin-fixed, paraffin-embedded tumor samples from 40 HNSCC. We evaluated p53 protein expression and analyzed the relationship between the p53 overexpression and age, sex, primary tumor site, stage, survival rate, recurrence. All reported P values resulted from two-sided statistical tests. Results: Overexpression of p53 was detected in 20 cases(50%) among 40 cases of HNSCC. The p53 overexpression was not associated with age, sex, primary tumor site, stage, recurrence and survival rate. Conclusions: In our results, p53 was not significant prognostic factor in HNSCC. Based on many previous studies, It is evident that p53 has a certain role in tumorigenesis of HNSCC. So, the further study is needed to evaluate the prognostic significance of p53 in HNSCC.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.12-19
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• 2005

This paper proposed a dual actuator using Bimorph PZT for information storage device based on prove array NSOM(near-field scanning optical microscopy). The gap between the media and the optical head should be maintained within the optical tolerance. Therefore, a new actuator having high sensitivity is required. Bimorph PZT, which has fast access time and high sensitivity characteristic, is suitable for this precise actuating system. This paper is focused on derivation of mathematical model of dual Bimorph PZT actuator and control algorithm. Hamilton's principle was used for mathematical model. The model is verified by FEA(finite element analysis), and compared with experimental results. Different control algorithms were used for two Bimorph PZT actuating same direction and opposite direction. The gap between recording media and optical head was controlled within 20nm in experiment.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.31-35
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• 2016

For reaction injection molding (RIM) polyurethane was mixed in the mixing head by impingement mixing, injected into the mold, and cured quickly, as soon as the mold is filled. The shape of the nozzle in the mixing head is critical to improve the quality of polyurethane. To achieve homogeneous mixing, an intensive turbulence energy in the mixing nozzle is essential. In this study, a mixing nozzle for RIM was designed, and mixing efficiency was investigated based on experiment. Experiments were conducted with different combinations of nozzle tips and exit diameter to measure the mixing efficiency by measuring jet force and investigating mixing image with high speed camera. Jet force increased gradually and reaches steady state conditions. The jet force depended on shape of nozzle tip and outlet sizes. These results suggest that optimized nozzle configurations are necessary for high efficiency mixing with RIM.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.52-57
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• 2019

Studies to augment emotion and immersion in multimedia content through olfactory stimulation are being increasingly conducted in the past two decades, and a variety of scent devices have been developed. Most of the scent devices are very large and heavy; consequently, they are installed on a table rather than being attached to the Head-mounted Display (HMD). Even if such devices are mounted on the HMD, it is not possible to control the scent density because of the size limitation, and it is not easy to be immersed in the experience because of the noise caused by the scent device. In order for an actual virtual reality or an augmented reality system to work efficiently with the scent device, three conditions - noiseless, a compact design, and concentration control- must be satisfied. In this study, we design a scent device that satisfies these three conditions. By using a miniature piezoelectric pump, a small size scent device is designed so that it can be easily attached to the lower end of the HMD, and hardly any noise is generated. Moreover, it is possible to control the concentration of the scent by controlling the piezoelectric pump using amplitude and frequency.

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.06a
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• pp.12-20
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• 2004

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10329-10334
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• 2015

Background: To systematically summarize the association between the X-ray repair cross complementing 3 (XRCC3) gene polymorphism and oral cancer susceptibility by meta-analysis. Materials and Methods: Databases including PubMed, EMbase, CNKI, VIP and WanFang Data were searched to identify case-control studies concerning the association between an XRCC3 gene polymorphism and the risk of oral cancer from the inception to June 2014. Two reviewers independently screened the literature according to the criteria, extracted the data and assessed the quality. Then meta-analysis was performed using Stata 11.0 software. Results: Seven published case-control studies including 775 patients with oral cancer and 1922 controls were selected. Associations between the rs861539 polymorphism and overall oral cancer risk were not statistically significant in all kinds of comparison models (CT vs CC: OR=0.94, 95%CI=0.74-1.18; TT vs CC: OR=0.94, 95%CI=0.64-1.38; dominant model: OR=0.95, 95%CI=0.76-1.18; recessive model: OR=0.94, 95%CI=0.69-1.29; allele T vs C: OR=0.97, 95%CI=0.84-1.11). In the stratified analysis by ethnicity, no significant associations were found among Asians and Caucasians. On stratification by tumor type, no significant associations were found for cancer and oral premalignant lesions. Conclusions: The XRCC3 gene polymorphism was not found to be associated with the risk of oral cancer. Considering the limited quality of the included case-control studies, more high quality studies with large sample size are needed to verify the above conclusion.