• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.5
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• pp.486-496
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• 2013

Time synchronization in underwater environment is challenging due to high propagation delay and mobility of sensor nodes. Previous researches do not consider practical issues affecting on the accuracy of time synchronization such as high-channel access delay and relative position between sensor nodes. Also, those protocols using bidirectional message exchange shorten the network lifetime and decrease the network throughput because numerous transmission, reception and unnecessary overhearing can be occurred. Therefore, in our research, we suggest enhanced time synchronization based on features of underwater environment. It controls the instant of transmission by exploiting the feature of an oceanic movement and node deployment. Moreover, the protocol uses more accurate time information by removing channel access delay from the timestamp. The proposed scheme is also practical on the underwater sensor network requiring low-power consumption because the scheme conducts time-synchronization with smaller transmission and reception compared with previous works. Finally, simulation results show that the proposed protocol deceases time error by 2.5ms and 0.56ms compared with TSHL and MU-Sync respectively, reducing energy consumption by 68.4%.

• Journal of muscle and joint health
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• v.8 no.2
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• pp.217-229
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• 2001

The purpose of this study is to analyze the needs of instructors for developing self-help and aquatic exercise programs of Korean Rheumatology Health Professionals Society (KRHPS). Data were collected by self-administered questionnaires via mail for 63 out of 248 certified instructors from KRHPS. Authors analyzed the data based upon following 3 criteria, 1) demographical data of the instructors, 2) content of the programs, 3) evaluation of arthritis self-help and aquatic exercise program. As a result, most of respondents satisfied with the two programs in general, but they need some modification of the program in partly. They need more information about practical method of exercise, complementary theray, and treatment of arthritis. Also they proposed developing more interesting exercise program which can be learn with ease and enjoyable. It is also suggested that developing new exercise program would be needed to improve adherence of exercise.

• Journal of muscle and joint health
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• v.2 no.2
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• pp.131-146
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• 1995

Many arthritis patients experience weakness of muscles in extremities mainly due to disuse atrophy and weight gain because of the limited activities and exercises. This study examines the effects of the 6-week aquatic-exercise program on the body fat and the muscle of the rheumatoid arthritis patients. Seventeen patients in the experimental group and 18 in the control group were assigned depending on their preference and physical condition. These patients had more than 3 points of pain out of 10, deformities in knee, wrist and ankle joints. The amount of aquatic exercise increases from 35 minutes in the first week to 60 minutes in the 6th week. In the resting period they discussed their own experiences about exercise, personal and family affairs, and performed some recreation programs in order to increase the self-efficacy and promote the relationship with other patients by the group activities. Skinfold thickness and circumferences of both extremities were measured before and after experiment to compare the difference. For testing the body fat Saham Model was used. Prior to the experiment two group's body weight, skinfold thickness and skin circumferences were not significantly different which indicates the homogeneity of two groups. Body weight and most parts of skinfold thickness of the experimental group were significantly lower than the control group after 6-week aquatic exercise program. Circumference was not significantly lower than the control after the program. These findings indicate the in-crease of muscle sizes and the reduction of the body fat. Therefore a more active application of aquatic exercise into a variety of clients is strongly suggested.

• Journal of muscle and joint health
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• v.21 no.2
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• pp.97-105
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• 2014

Purpose: The purpose of this study was to identify the effects of an aquatic exercise program on physical fitness, body composition, and gait characteristics using trunk and pelvic angle in women living in urban fringe area. Methods: An aquatic exercise program consists of exercise in a swimming pool and self-help group activity with 16 women living in urban fringe (mean age: 63 years) for 8 weeks (twice a week for 2 hours). Physical fitness, body composition, trunk and pelvic angle using 2D video motion analyzer, and a questionnaire including socio-demographic variables were measured from July to August, 2013. Data were analyzed using a paired t-test with the SPSS/WIN 18.0 program. Results: At the end of 8 weeks intervention, there were significant decreases on body weight (p=.025), body fat (p=.030) and BMI (p=.011). There were significant increases on muscle strength (p=.001) and flexibility (p=.015). Trunk angle was significantly improved, which means participants less moved their body from side to side when they walked (p=.001). Conclusion: From this results, the aquatic exercise program could be an effective nursing intervention to improve physical fitness, body composition, and gait ability for women living in urban fringe area.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.9 no.2
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• pp.257-267
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• 2002

Purpose: Aquatic exercise program is known to have positive effects for health maintenance and improvement in inpatients with arthritis. Aquatic exercise program could be a way to obtain wellness in middle-aged women. However, there have been few studies to evaluate physical function. The purpose of this study was to identify the effects of aquatic exercise on physical health such as body weight, BMI, muscle strength (grip strength, pinch pressure), and flexibility in healthy middle-aged women. Method: The subjects of the study were fifty healthy middle-aged women (40-59 years) who had no experience with exercise. Twenty five subjects were assigned to the experimental group and 25 to the control group. An aquatic exercise program which consisted of approximately one hour of exercise in the water two days per week. for six weeks was given to the experimental group. Data were gathered from October 2000 to April 2001 using a questionnaire and physical function measure tool (pinch pressure, grip strength. weight. centimeter ruler). Data were analyzed with the SPSS win 10.0 using frequency, t-test, $x^2$ test, paired t-test. and ANCOVA. Result: The results of this study are as follows: There were significant differences in body weight, BMI, right, left grip strength and right and left pinch pressure between the two groups. Conclusion: From these results, it is concluded that the aquatic exercise program for healthy middle-aged women can be effective in increasing physical health in these women.

• Journal of muscle and joint health
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• v.3 no.1
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• pp.23-36
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• 1996

This study was undertaken to evaluate the effect of long-term(6 Month) aquatic exercise through home nursing care demonstration on body weight, body fat, pain, muscle strength, self-efficacy and quality of life. Twenty-one women with rheumatoid arthritis were enrolled in the study. The sample was restricted to women in order to increase homogeneity. All patients were stable medication regimens in rheumatism center. The data was collected from October, 1994 to November, 1995. The data were analyzed Mean, Standard Deviation, $x^2$ Test, Mann-Whitney U-Wilcoxon Rank Sum W Test, Wilcoxon Matched-pairs signed-ranks test using SPSS $pc^+$ program. The results of this study were as follows : 1. There was no significant difference between the control and the experimental group on body weight. 2. There was no significant difference between the control and the experimental group on body fat. 3. There was no significant difference between the control and the experimental group on pain(RAI). 4. There was no significant difference between the control and the experimental group on muscle strength. 5. There was no significant difference between the control and the experimental group on quality of life. But in the experimental group, finding from additional analysis showed significant difference in the score of quality of life between pre and post experiment. 6. There was no significant difference between the control and the experimental group on self-efficacy. The findings in this study were not support the positive effect of long-term aquatic exercise in women with rheumatoid arthritis. A further study is necessary to determine the pure effect of aquatic exercise except the effect of home nursing care.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.2
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• pp.45-56
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• 1994

A computationally efficient numerical method based on potential flow is developed for time-domain simulation of the nonlinear free-surface flows around a 2-dimensional hydrofoil. This numerical method, namely, spectral/boundary-element method, is a mixed one of the high-order spectral method and the boundary-element method in time-domain. The high-order spectral method is used to calculate the nonlinear evolution of free-surface, and the boundary-element method is used to calculate the effects of the hydrofoil and the shed vortex. As application examples, nonlinear free-surface flows around a 2-dimensional hydrofoil which starts from the rest and translates near the free-surface with or without harmonic oscillations are calculated. Nonlinear/unsteady results of free-surface waves and hydrodynamic farces are shown and discussed. Particularly, the results of steady-state which are obtained as a special case of the present unsteady solution are compared with others' calculated and experimental results, and good agreements are observed.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.184-192
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• 2003

This study were investigated the effects to the starting-time of the applied aquatic exercise to the functional healing phase on the Achilles tendon injured rats. The Spraque-Dawley female rats weights($246{\pm}18g$) were assigned to the four groups(24 rats), all experimental groups were able to walling training for 20 min. on the rolling bar motor before injured, one group; control group and three groups; aquatic exercise groups, The aquatic groups were derived into the first day, fourth day and seventh day groups after injuring Achilles tendon according to the levels of aquatic exercise. This studied were investigated the effects of functional healing after appling the aquatic exercising after first day, fourth day and seven days after injured Achilles tendon by the method of rolling bar-motor(Jc-35L-H/GEAR MOTOR, DC, 12V-20RPM, TAIWAN)R.O.C. and to the phase of healing phase to the Achilles tendon. After injuring Achilles tendon, the starting-times of walling on the rolling bar motor were showed from 10th day in the first day aquatic groups, after injuring, from the eight day of fourth day and seventh day aquatic groups, but those, of the all aquatic groups were not significantly showed from the ninth day after injured in the control group. There were showed healing phase without adherence like normal tissue from the fourth day group after injured to the control group. The results stewed that aquatic exercising were effected the healing phase to the injured Achilles tendon to apply exercise, after being the late period of inflammation.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.16-22
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• 1994

수중 예인시스템의 동적 거동 해석을 위한 3차원 비선형 수학모델이 제시되었다. 수중 예인체는 세장보로 이상화되었으며, 보요소의 굽임강성 및 비틈강성의 영향이 수학모델에 포함되었다. 축류가 지배적인 비정상 상대유동장내의 세장예인체의 횡방향 운동에 따른 유체동역학적 반력과 기진력에 관한 비선형 3차원 수학 정식화가 수행되었다.

• Journal of the Korean Institute of Navigation
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• v.17 no.1
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• pp.99-105
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• 1993

Underwater acoustic positioning systems have been extensively used not only in surface position fixing but also in underwater position fixing. Recently, these systems have been applied in the field of installation and underwater inspection offshore platforms etc. But in these systems are included the fixing errors as results of a signal with noise and irregular motion of vessel by ocean waves. In this paper to improve the accuracy of the position fixing a Kalman filter is applied to the short baseline(SBL) acoustic positioning system. The optimal position obtained by the Kalman filter is compared with the raw position and it is confirmed that the former is more accurate than the latter.