• Proceedings of the Korean Society of Marine Engineers Conference
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.130-134
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• 2001

In the re-entry control system, errors apt to induce because the time derivative of drag acceleration is analytically estimated. Still more, the difficulty of estimation of the exact drag coefficient in hypersonic velocity and the nun-reality of the scale height cause a steady-state drag error. This paper proposes the additional method of the disturbance observer. This reduces the steady-state drag error according to the following series. First, this method estimates a error in drag acceleration time derivative by the analytic calculation and then creates the new drag acceleration time derivative using the estimated error. The performance of the re-entry control system is verified about 32 reference trajectories.

• Journal of the Korea Institute of Military Science and Technology
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• 제10권2호
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• pp.12-20
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• 2007

The aiming ability is a key to improve the accuracy performance of the gun pointing system in the ground military vehicle. This paper describes the new detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis the vibration trends of the pointing system occurred while the vehicle driving, acceleration data obtained from vehicle was processed by using data processing algorithm with moving average and Hilbert transform. The specific mode constants of acceleration were obtained from various disturbances. Vehicle velocity, road condition and property of pointing structure were considered as factors which make the change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition of the classification of vibration signal in various driving conditions. Results of signal processing were compared with other condition result and analysed.

• International Journal of Control, Automation, and Systems
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• 제6권1호
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• pp.142-148
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• 2008

In this paper, we deal with the problem of reducing the order of the detection filter for the linear time-invariant system. Even if the detection filter is generally designed in the form of full order linear observer, we show that it is possible to reduce its order when the response of fault signals is limited to a subspace of the estimation state space. We propose a method to extract the subspace using the observer canonical form considering the dynamics related to the remaining subspace acts as a disturbance. We designed a reduced order detection filter to reject the disturbance as well as to guarantee fault detection and isolation. A simulation result for a 5th order system is presented as an illustrative example of the proposed design method.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• 제28권1호
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• pp.155-169
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• 1998

The purpose of this study was to prove the relationship between arthrographic and clinical features in temporomandibular joint disorders. In order to carry out this study, ninety-eight arthrographic examinations of temporomandibular joints were performed on eighty-two patients who had the temporomandibular joint disorders. As the arthrographic examination, the cases were classified in three groups, disk displacement with reduction, disk displacement without reduction, within normal limit. After this, the cases were clinically examined, and the results were compared and analyzed in each other group. The obtained results were as follows; 1. As the classification by arthrographic examination, three groups (disc displacement with reduction, disc displacement without reduction, within normal limit) were 41 ％, 54％, 5％ of total cases in this study, respectively. 2. The third decade(65％) was most frequent in this study. The average age of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 24, 28, 21, and disc displacement without reduction group was higher than any other group. 3. In the chief complaint, pain was the most frequent in all three groups. Joint sound was also frequent in disc displacement with reduction group, but in disc displacement without reduction group, limitation of mouth opening was more frequent. 4. Of the various pain, the movement pain was most frequent ( 61 ％) in this study. In joint sound, click(63％) was the most frequent in disc displacement with reduction group, but sound history(42％) and no sound (31 ％) were more frequent in disc displacement without reduction group. 5. The average maximum opening of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 44mm, 32.9mm, 44mm, and disc displacement without reduction group was less than any other group. 6. The masticatory disturbance of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 53％, 79％, 40％, and the trauma history of each group was 50％, 40％,60％.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.372-377
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• 2004

Tilting bogie system allow the train to pass curve at higher speed without affecting passenger comfort. As the tilting trains offer the optimum means of providing faster and more comfortable rail service with minimum of environmental disturbance and capital investment, mere than 14 countries have now adopted or are about to adopt tilting train technology. The Korean National Railroad is also planing to apply faster tilting train to the areas where the High speed rail service are not provided. This paper describes the parametric study to achieve the optimal suspension parameters of the Bogie for 180 km/h Korean Tilting Train(TTX) from the view point of the vertical and lateral vibration reduction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제16권5호
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• pp.529-536
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• 2006

In high-speed optical disk drive, the excitation caused by rotation of a mass-unbalanced disk is a major source of vibration. The vibration can be a disturbance to the servo system, which is sufficient to cause severe failures in the reading and writing process. The vibration also causes users to feel unpleasantness. The vibration reduction is therefore essential for the reliable operation of optical disk drive. One of the approaches to reduce the vibration is a dynamic vibration absorber(DVA). In this paper, we analyze the dynamic behavior of $DVD{\pm}RW$ combo drive system with DVA through 12-dof rigid multi-body dynamic model. The effective location and the optimal frequency ratio for the DVA are obtained from the analysis. The DVA are fabricated based on the analysis and its usefulness is confirmed.

• Journal of muscle and joint health
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• 제5권1호
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• pp.39-56
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• 1998

This study was an quasi-experimental study, done to identify factors Influencing the reduction of symptoms in patients with fibromyalgia. The primary purpose of the study was to develop a Self-Help Program suitable for patients with fibromyalgia in Korea. The secondary purpose was to identify the effects of a Self-Help Program which included stretching exercise. This study was carried out between Feb. 24 and July 8, 1997 and patients in the study Included out patient diagnosed with fibromyalgia based on the criteria developed by the American College of Rheumatology(1990) and H, University which is a tertiary patient care clinic for Rheumatism. The experimental group included 38 patients who were residents of Seoul or Kyungi province, and a control group of 38 patients who were residents of other areas. The control patients were matched to the experimental group patients and they were selected considering the number of tender points on the Fibromyalgia Impact Questionnaire score and a score of self-efficacy. The experimental group participated in a Self-Help Program based on the American Arthritis Foundation(1995) guidelines. The program participants participated in a small group which consisted of 12-15 members attending the program once a week, for 6 weeks with each program lasted two to two and a half hours. The stretching exercise was carried out in each patient's home every day following the video tape exercise provided by the researcher, and the researcher provided encouragement and concern to the patients by calling them once a week. The number times the exercise was performed was divided by the number of participants to calculate the percentage of performance and determine the amount of exercise. Self-efficacy was measured by the Self-Efficacy Scale developed by Lorig et al. (1989) for arthritis patients. The degree of pain was converted to scores based on the Visual Analog Scale, the number of tender points was converted to scores based on the criteria of the ACR(1990) and of Yunus. Depression was measured by CES-D and physical disability, sleep disturbance, fatigue, and anxiety of patients with fibromyalgia were measured by the Fibromyalgia Impact Questionnaire. The level of the exercise performance was converted to scores using the number of times the exercise was performed following the video tape prepared by Association of Rheumatology Health Professionals. Data were analyzed by SPSS windows and the results ire described below. 1. The experimental group which participated in the Self-Help Program showed higher efficacy scores than the control group when both groups were analyzed for depression and the number of tender points as common variables(F=9.146, p=.003). 2. The experimental group which participated in the Self-Help Program showed lower scores than the control group, for pain, the number of tender points, depression, physical disability, fatigue, sleep disturbance and anxiety. These symptoms of fibromyalgia can all be seen to have subsided(F=9.483, p=.003 : F=32.680, p=.001 ; F=11.104, p=.001, F=5.344 : p=.024, F=7.630 : P=.007, F=15.6512, p=.003 : F= 7.5412, p=.008). 3. In the experimental group, the self-efficacy score for the first three weeks showed a positive correlation with the exercise-performance score for four to six weeks (r=.387, p=.043). 4. In the experimental group, the relationship between the level of exercise-performance and the reduction of symptoms showed a significant correlation only to physical disability(r= -.500, p=.001). 5. In the experimental group, the relationship between the self-efficacy score and pain, the number of tender points, depression, physical disability, fatigue, sleep disturbance and anxiety score showed inverse correlations and thus, a reduction of symptoms occured when the self-efficacy score increased(r=-.325, p=.004 ; r= -.253, p=.027, r=-.452, p=.001 : r=-.434, p=.001 ; r=-.316, p=.005 ; r=-.460, p=.001 ; r=-.397, p=.014). Therefore, self-efficacy improved following the Self-Help Program including the stretching exercise. It was also found that physical symptoms (pain, number of tender points, level physical disability) and psychological symptoms (depression, fatigue, sleep disturbance, anxiety) were reduced. Moreover, It was found that the higher the self-efficacy, the the higher the degree of achievement of goals set for the stretching exercises. In addition, the level of exercise-performance influenced the level of physical disability, one of the symptoms of fibromyalgia. Accordingly, the conclusions from this study are that exercise-performance and the reduction of symptoms is achieved through promotion of self-efficacy. Therefore, it is proposed that are the Self-Help Program including stretching exercises is an appropriate nursing intervention for the reduction of symptoms of fibromyalgia.

• Journal of the Korean Society of Propulsion Engineers
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• 제17권5호
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• pp.101-112
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• 2013

Large eddy simulation was performed to investigate the effect of linearly increasing wall disturbance on the modification of turbulent characteristics of temperature field in the vicinity of the wall. It was noted that temperature variance increased monotonically whereas temperature dissipation decreased significantly, resulting in a noticeable reduction in both time and length-scales. A sudden drop in turbulent Prandtl number down to around 0.25 in the near-wall region indicated that the similarity between velocity and temperature fields decreases near the wall as a result of linear wall disturbance.

• Archives of Plastic Surgery
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• 제39권4호
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• pp.301-308
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• 2012

In the treatment of mandibular condyle fracture, conservative treatment using closed reduction or surgical treatment using open reduction can be used. Management of mandibular condylar fractures remains a source of ongoing controversy in oral and maxillofacial trauma. For each type of condylar fracture,the treatment method must be chosen taking into consideration the presence of teeth, fracture height, patient'sadaptation, patient's masticatory system, disturbance of occlusal function, and deviation of the mandible. In the past, closed reduction with concomitant active physical therapy conducted after intermaxillary fixation during the recovery period had been mainly used, but in recent years, open treatment of condylar fractures with rigid internal fixation has become more common. The objective of this review was to evaluate the main variables that determine the choice of an open or closed method for treatment of condylar fractures, identifying their indications, advantages, and disadvantages, and to appraise the current evidence regarding the effectiveness of interventions that are used in the management of fractures of the mandibular condyle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.108.5-108
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• 2001

The research of friction compensation control system seeks the accuracy, the velocity increase of the table, and the settling time reduction. The friction is the disturbance which has the greatest influence, but the past research of control system doesn´t perform exact modeling of the friction. So this research aims at the friction compensation control system, the exact modeling of the friction, comparison between the model simulation and experimental data, and the design of observer for the friction estimation.