• The Journal of Korean Academy of Prosthodontics
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• v.51 no.2
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• pp.119-124
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• 2013

Many of the patients with extensive abrasion need comprehensive restorative treatment. The abrasion is usually caused by attrition, besides of it, there are many reasons for it. The plan of treatment should be started on assessment of the type of attrition and the etiologic analysis. Patient with well-developed masticatory muscle, alveolar process, and high occlusal force and also with little muscle length difference between the stable and the contracted state should be carefully assessed for the vertical dimensional loss and the restoration should be carefully designed. Decrease of tooth length can be compensated by the growth of the alveolar bone height; therefore, consistency of the occlusal vertical dimension is maintained. Accordingly, a careless increase of the vertical dimension can produce muscle fatigue, depressed tooth and pain, and fracture of the restoration. In this case, the patient with multiple tooth abrasion and clenching habit, the edentulous maxillary area is restored with amalgam inserted RPD, and the dentulous area of the maxilla and mandible are treated with fixed restoration accompanying with the increase of vertical dimension. Consequently, we are going to report about the satisfying result in both functional and esthetic aspects.

• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.204-214
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• 2015

Depth map upsampling is an approach to increase the spatial resolution of depth maps obtained from a depth camera. Depth map quality is closely related to 3D perception of stereoscopic image, multi-view image and holography. In general, the performance of upsampled depth map is evaluated by PSNR (Peak Signal to Noise Ratio). On the other hand, time-consuming 3D subjective tests requiring human subjects are carried out for examining the 3D perception as well as visual fatigue for 3D contents. Therefore, if an objective metric is closely correlated with a subjective test, the latter can be replaced by the objective metric. For this, this paper proposes a best metric by investigating the relationship between diverse objective metrics and 3D subjective tests. Diverse reference and no-reference metrics are adopted to evaluate the performance of upsampled depth maps. The subjective test is performed based on DSCQS test. From the utilization and analysis of three kinds of correlations, we validated that SSIM and Edge-PSNR can replace the subjective test.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.11 no.1
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• pp.105-129
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• 2007

Objectives: The purpose of this research is to obtain basic data about the effects of Constitution-Acupuncture (CA) based on Eight-Constitution Medicine (ECM) by the expert CA Oriental Medical Doctors. Methods: The resources were collected from the internet survey method. 35 samples were collected. The SPSS 13.0 for windows and Answer Tree 3.0 was used for statistical analysis. Results: The results from this research are as follow. 1. The motivation that apply ECM to clinic are 'Because ECM is effective for diagnosis, treatment and prevention against disease' 48.6% and 'Because CA therapy is effective' 25.7%. 2. The advantage that CA therapy compare to the other acupuncture therapy are 'Management and prevention against disease are available by ECM theory to a person who exact constitution is confirmed' 82.9%, 'CA therapy is superior in treatment of hard symptoms to treat by the other acupuncture therapy' 80%, 'Treatment effect is good' 77.1%, 'Needle manipulation of CA is simple comparatively' 57.1%, 'It is definite whether treatment effect is good or not' 54.3% and CA therapy is superior all in diseases of twelve category. 3. When the effects of CA is good, patients expressed much 'Eyesight lightened', 'Took deep sleep at night', 'Fatigue decreased', 'Body is light', 'Feelings became refreshing' as well as 'Symptoms were improved' and also physicians confirmed as those reactions whether treatment is effective. Conclusions: The research suggest that CA is effective therapy in clinic, and so further study is needed for CA therapy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.498-507
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• 2017

Electronic equipments comprised of high density components with various packaging types have been recently applied to a satellite. Therefore, to guarantee high reliability of electrical equipment, a design approach, which can reduce the development period and cost through an early diagnosis in potential risks of failure, should be established. In the previous research, the reliability assesment of the electronic equipments have based on Steinberg's fatigue failure theory. However, this theory was not enough for further investigation of life prediction and reliability of the electronic equipments comprised of various sizes and packaging types due to its theoretical limitations and analysis results sensitivity with regard to different modeling technic. In that case, if detailed finite element model is established, aforementioned problems can be readily solved. However, this approach might arise disadvantage of spending much time. In this paper, to establish strategy for high reliability design of electronic equipment, we performed mechanical reliability evaluation of CCB (Camera Controller Box) at qualification level based on the approach using Sherlock unlike design techniques applied to existing business.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.169-174
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• 2005

Traditionally, keyboards have been one of the most frequently used input devices for information processing using computers. As most computers adopt the Microsoft Windows for their operating system however, the usage of mouse has recently increased to a great extent. Moreover, the mouse has been used as the leading input device in such areas as industrial design and computer aided design. Excessive uses of mouse may cause a severe pain and fatigue on neck and upper limb due to the intensive and repetitive use of corresponding muscles, which renders a decline in efficiency and leads to musculoskeletal disorders. The main purpose of this study is to find the best working conditions to prevent musculoskeletal disorders when using mouse in a neutral posture. Utilizing electromyogram amplitude and Borg's scale, the role change and strength imposed on the muscles were measured and analyzed with and without the forearm support concerned. Also investigated were the effects of changes in elbow forearm supporter.

• Journal of Preventive Medicine and Public Health
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• v.28 no.2 s.50
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• pp.433-449
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• 1995

The study subjects in this study are 295 workers who work on one electronics industry, and they were composed of 93 VDT and 202 non-VDT workers. This study was carried out to obtain the prevalence of subjective symptoms and to compare psychological symptom scores from SCL-90-R between VDT and non-VDT work groups. And to verify the relationship between VDT work related symptoms and psychological symptoms, the author compared SCL-90-R T scores between symptom complaining and non-complaining groups. The results are summarized as follows : 1. Throughout the prevalence study of VDT work related symptoms according to VDT work state, the author could select the final 10 symptoms by sex;'eye fatigue', 'foggy vision', 'neck discomfort or pain', 'shoulder discomfort and pain', 'light headedness', 'dizziness', 'acne', 'itching sensation on face', 'difficulty in concentration', 'memory disturbance' in males, and 'blurred vision', 'foggy vision', 'neck discomfort or pain', 'shoulder discomfort and pain', 'abdominal distention', 'indigestion', 'acne', 'prickling sensation on face', 'difficulty in concentration', 'memory disturbance' in females. 2. Throughout comparison of psychological symptom scores from SCL-90-R between VDT and non-VDT workers, except 'Interpersonal sensitivity' in female, Mean T score were higher in VDT workers, but not significantly different between the two groups. These results indicate that the relation between VDT work status and psychological symptoms are not strongly correlated. 3. Because of the nonspecific characteristics of VDT work related symptoms, from the 40 subjective symptoms, the author selected the final 10 symptoms by sex, especially correlated to VDT, and divided the study subjects into symptom complaining and non-complaining groups. The mean SCL-90-R T scores between the two groups were compared. Except for the opthalmologic symptoms in females, the scores were significantly different between the two groups in all symptoms. And this indicates that the VDT work related symptoms strongly correlated with the present individual psychological conditions. 4. Due to understand that which of the 9 psychological symptom dimensions are strongly correlated with the subjective symptoms, the author excuted muliple logistic regression analysis, and the result were as follows; 'depression' and 'somatization', in male, and 'obsessive-compulsive' and 'somatization' in female.

• Journal of the Korean Society of School Health
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• v.1 no.1
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• pp.160-177
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• 1988

This study is an analysis of the teachers' health problems that focuses on the frequencies and types of their visiting to school clinics and the management of health-related problems. The participants for this study are consisted of 1,650 teachers employed at 30 public schools in the Seoul area. Data for the study came from diagnostic records for 1986, the results of a questionaire-type survey conducted between June 20th and of the same year an from other documents recorded by school nurses. The main results of this study are as follows: 1. The teachers' health problems. a) According to health diagnosis records, 6.1 % of all teachers had a health problem. Liver-related ailments topped the list, followed by circulatory and diabetic problems. b) The survey data had 71.9 % of the respondents indicating that trey suffered from some health problem. The most frequent response concerned respiratory problems, followed by gastro-intestinal and nervous system problems. c) A check of clinic utilization records revealed that the main reasons for visiting are concerned with fatigue (30.5 %), gastro-intestinal(18.7 %) and respiratory(18.2 %) ailments. These three categories accounted for 67.4 % of total use. 2. Frequencies of their visiting to school clinics 40.5 % of the teachers indicated that they have visited the school clinic. And 62.0 % visited it with a self-diagnosed ailment and 15.3 % utilized the facility after a problem had been detected in a health examination. Clinics were visited a total of 1,458 times which breaks down to 0.9 times per month per teacher. For a patient, the figures are 2.2 times on the average with a range from 1 to 19. 3. Health management problems a) Of those respondents. 53.4 % stated that they didn't have enough time to consult about their health problems and diagnose their disease b) Also, 47.3 % of the respondents indicated that school nurses should give health counsels and health education. c) When questioned about improvements in the current system, the teachers placed importance on the prevention and management of chronic diseases (35.2 %) and pre- and posteducation concerning periodic health examinations In conclusion, the following points must be considered: First, school administrators need to pay more attention to the health problems of the teachers. Second, school nurses should be more active in managing a health program for teachers. Finally, education and training for nurses should be continually upgraded so that they can dispense proper and timely care for teachers.

• Science of Emotion and Sensibility
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• v.22 no.3
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• pp.3-20
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• 2019

With advancements in technology of virtual reality, it is used for various purposes in many fields such as medical care and healthcare, but as the same time there are also increasing reports of nausea, eye fatigue, dizziness, and headache from users. These symptoms of motion sickness are referred to as cybersickness, and various researches are under way to solve the cybersickness problem because it can cause inconvenience to the user and cause adverse effects such as discomfort or stress. However, there is no official standard for the causes and solutions of cybersickness at present. This is also related to the absence of tools to quantitatively measure the cybersickness. In order to overcome these limitations, this study proposed quantitative and objective cybersickness evaluation method. We measured 128-channel EEG waves from ten participants experiencing visually stimulated virtual reality. We calculated the relative power of delta and alpha in 11 regions (left, middle, right frontal, parietal, occipital and left, right temporal lobe). Multiple regression models were obtained in a stepwise manner with the motion sickness susceptibility questionnaire (MSSQ) scores indicating the susceptibility of the subject to the motion sickness. A multiple regression model with the highest under the area ROC curve (AUC) was derived. In the multiple regression model derived from this study, it was possible to distinguish cybersickness by accuracy of 95.1% with 11 explanatory variables (P_D.MF, P_D.LP, P_D.MP, P_D.RP, P_D.MO, P_A.LF, P_A.MF, P_A.RF, P_A.LP, P_A.RP, P_A.MO). In summary, in this study, objective response to cybersickness was confirmed through 128 channels of EEG. The analysis results showed that there was a clearly distinguished reaction at a specific part of the brain. Using the results and analytical methods of this study, it is expected that it will be useful for the future studies related to the cybersickness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.66-73
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• 2020

In the hydrogen compression cycle, which is currently being developed, hydrogen is compressed to a very high pressure using a compressor, and then stored and used in a high-pressure vessel. This shows that an increase in the temperature of hydrogen in the vessel due to a pressure rise during the filling process and the pressure fatigue due to the repeated cycle may cause problems in the reliability of the vessel. In this paper, for the entire processes in a 50 MPa hydrogen compression system, theoretical and numerical methods were conducted to analyze the following: the temperature increase of hydrogen in the vessel and the time required to reach thermal equilibrium with the surroundings, the change in temperature of hydrogen passing through the pressure reducing valve, and the required capacity of the heat exchanger for cooling the vessel. The results will be useful for the design and construction of hydrogen compression systems, such as hydrogen charging stations.