• Title, Summary, Keyword: Stability index

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Study on the comparison topographical factor with slope stability using fractal dimension and surface area index (프랙탈 차원과 표면적 지수를 이용한 지형인자와 사면안정성 비교 연구)

  • Noh, Soo-Kack;Chang, Pyoung-Wuck;Cha, Kyung-Seob
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.387-392
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    • 2005
  • The research was performed to predict the potential landslide with roughness index. It was known that fractal dimension and surface area index can be represented the topography, specially when the natural slopes were rough or rugged. A test site was selected and fractal dimension and surface area index were calculated from the irregular triangle network. Fractal dimension were ranged between $2.016{\sim}2.046$ and surface area index $1.56E+07{\sim}2.59E+07$. Surface area index increased as fractal dimension increased. Slope stability was calculated by infinite slope stability analysis model and was compared to slope stability by fractal and surface area index. In the result, unsafe zones where slope stability is under 1.1 were $5.11{\sim}6.25%$ for the test site. It can be said that fractal dimension and surface area index are a good index to evaluate the slope stability because when fractal dimension and surface area index are greater, then stability of the site is more unsafe.

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The Effect of Postural Stability on Genu Varum in Young Adults

  • Chae, Yun-Won;Park, Ji-Won;Park, Seol
    • The Journal of Korean Physical Therapy
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    • v.24 no.6
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    • pp.419-422
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    • 2012
  • Purpose: Malalignment of the lower limbs may increases the difficulty of maintaining equilibrium. The purpose of this study was to study the effects of genu varum and poor posture in the sagittal plane on postural stability. Methods: We had 27 subjects with varus and 27 normal subjects participate in this study. Subjects for whom the distance between the medial epicondyles in the knee joint was more than 3 cm were classified as varus group, and subjects for whom the distance was less than 3 cm were classified as normal group. The measurements of static and dynamic stability were used overall stability index (OSI), anterioposterior stability index (APSI), and mediolateral stability index (MLSI) using a Biodex balance system. Results: When measuring the static stability index, there were significant differences in the mediolateral stability index between the varus and control groups. When measuring the dynamic stability index, there were significant differences in the overall, anteriorposterior, and mediolateral stability index between the varus and control groups. These results demonstrated that genu varum affects mediolateral movement in static stability, and overall, anterioposterior and mediolateral movements in dynamic stability. Conclusion: As genu varum affects static and dynamic stability in young adults, it increases the risk of injuries or falls. Exercise and surgery are required for realigning the genu varum. Future studies about postural stability in young children and elderly people who have a risk of falls due to lower postural control ability, are needed, as well as in young adults.

Development of Stability Index for Vessel Operators Support System (선박 운항자 지원 시스템용 선박 복원성능 지수 개발)

  • IM, Nam-Kyun;HWANG, SooJin;CHOE, Hun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.1
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    • pp.1-9
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    • 2018
  • All ships should ensure stability in accordance with IMO regulations. However, GM is only used to determine ship stability because it takes a lot of time to validate all regulations. This is a problem given that the safety of vessels cannot be guaranteed, potentially leading to accidents. There is a need for a more intuitive and comprehensive method of confirming the stability of ships. This study developed a stability index that expresses ship stability in one value. An index equation is defined based on the 6 stability criteria for ships prescribed by IMO and the result of calculating the ship stability of a model ship. A stability index has been derived for each loading condition by applying the index equation to the same ship. It can clearly be seen that this stability index appropriately explains the criteria. In other words, it is possible to assess ship stability with one value and confirm whether the ship stability satisfies IMO regulations. This index will help masters and officers more easily and accurately check ship stability.

The Index of the Stability of Misconceptions (오개념의 견고성 지수)

  • Lee, Yung-Jick;Kwon, Jae-Sool
    • Journal of The Korean Association For Science Education
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    • v.13 no.3
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    • pp.310-316
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    • 1993
  • One of the major characteristics in misconceptions is the stability over time. However, the concept of stability has not been defined clearly yet even though some trials to quantify the stability has been done. In this study, the researcher tried to establish a stability index of students' misconception for the quantification. In this study, the stability of a misconception was defined using mean correct choice (MC), the slope of correct choice (C), mean incorrent choice(MI) and the slope of incorrect choice(I) as follows; I=1/3 (1-C) (1+I)(1-MC)(1+MI). The index developed in the study was examined using artificial data. In this study, the index seemed to represent the charicteristics of the stability inferred by theoretically. This means the index developed in this study has some validity for the time being. Howerever, since artificial data were used to exame the index, it showed be reexamined using real data in the future study.

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The Effect of Progressive Lumbar Stability Exercise on the Transversus Abdominis Muscle Thickness and Lower extremity muscle Fatigue Index in Soccer Players (축구선수의 진행형 요부안정화운동이 복횡근 두께와 하지근육 피로지수에 미치는 영향)

  • Lee, Joon-Hee;Park, Seung-Kyu;Kang, Jeong-Il;Yang, Dae-Jung;Kim, Je-Ho;Jeong, Yong-Sik
    • Korean Journal of Sport Biomechanics
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    • v.22 no.3
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    • pp.349-356
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    • 2012
  • This study aimed to assess the effects of progressive lumbar stability exercises and lumbar stability exercises on changes in the transversus abdominis muscle thickness and lower extremity muscle fatigue index in soccer players. Ten subjects were assigned to undergo training in each of the 2 groups, namely, the progressive lumbar stability exercise group and lumbar stability exercise group. Each intervention session lasted for 30 min, and 4 sessions were conducted in a week for 6 weeks for soccer players of S. University in Jeonnam, Korea. Changes in the transversus abdominis muscle thickness and lower extremity muscle fatigue index were measured using ultrasound and surface electromyogram. The results of the ultrasound measurement for the transversus abdominis muscle thickness indicated that progressive lumbar stability exercises were more effective than lumbar stability exercises. The results of the lower extremity muscle fatigue index measurements using surface electromyogram indicated that the fatigue index decreased in the progressive lumbar stability exercise group. Progressive lumbar stability exercise is believed to have put more workload during the shaking of the limbs, leading to increased stability and increased efficiency of the lower extremity muscle, thereby decreasing the fatigue index. Therefore, progressive lumbar stability exercises can be an effective measure for preventing injuries and improving the game performance of sports players by increasing the transversus abdominis muscle thickness and decreasing the lower extremity muscle fatigue index.

Effect of Heel-heights of Insole on Balance in Healthy Adults (정상성인의 인솔 높이가 균형에 미치는 영향)

  • Oh, Myoung-Hwa;Lee, Jeon-Hyeong;Kwon, Yoo-Jung;Lee, Jong-Dae;Lee, Myoung-Hee;Kim, Kyung
    • Journal of the Korean Society of Physical Medicine
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    • v.4 no.2
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    • pp.79-86
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    • 2009
  • Purpose:The purpose of this study was to investigated the effect of stability on heel-heights of insole in healthy adults. Methods:Subjects of 39 males measured stability index of the Biodex Stability System(BSS) by wearing shoes of 2cm, 5cm insoles including bare feet. The BSS was consisted of a movable balance platform and the platform was interfaced with computer software that enables the device to serve as an assessment of balance performance. Stability index of the BSS included overall stability index(OSI), anteroposterior stability index(APSI), mediolateral stability index(MLSI). In the BSS, subjects were asked to step on to the platform of the BSS and assume a comfortable position while maintaining slight flexion in the knees, looking straight ahead. Subjects were trained for 10min for adaptation to the heel-height of insole and then they maintained double limb stance for 2min. Biodex platform set to convert Lv.8 into Lv.1 gradually. Results:There were statistically significant differences between heel-heights of insole and stability index of OSI, APSI, and MLSI(p<.05). The result of post-hoc test were as follows; 1)OSI had significant differences between bare feet and 2cm, 5cm. 2)APSI had significant differences between bare feet and 2cm, 5cm. 3)MLSI had significant differences between bare feet and 2cm, 5cm(p<.05). Conclusions:We found that the more heels of insole high, the more stability index increases. In particular, balance index of insole above 5cm more increased and we could acknowledge that the insole above 5cm more effected balance of healthy adults.

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Real-time estimation of arc stability in GMAW process (GMAW 공정에서 아크 안정성의 실시간 측정)

  • 원윤재;부광석;조형석
    • Journal of Welding and Joining
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    • v.8 no.1
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    • pp.31-42
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    • 1990
  • Arc must be stable during welding first of all other factors for obtaining sound weldment, especially in the automation of welding process. Arc stability is somewhat sophisticated phenomenon which is not clearly defined yet. In consumable electrode welding, the voltage and current variation due to metal transfer enables to assess arc stability. Recently, statistical analyses of the voltage and current waveform factors are performed to assess the degress of arc stability which is assessed and controlled by operator's own experience by now. But, considering the increasing need and the trend of automation of welding process, it is necessary to monitor arc stability in real-time. In this sutdy, the modified stability index composed of two voltage and current wvaeform factors (arc time and short circuit time) reduced from four factors (arc time, short circuit time, average arc current and average short circuit current) in Mita's index by the welding electrical circuit modeling is proposed and verified by experiments to be well estimating arc stability in the static sense. Also, the recursive calculation form estimating present arc stability in the dynamic sense is developed for real-time estimation. The results of applying the recursive index during welding show good estimation of arc stability in real-time. Therefore, the results of this study offers the mean for real-time control arc stability.

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Effects of Immobilization of the Ankle and Knee Joints on Postural Stability in Standing (바로 선 자세에서 발목과 무릎관절의 고정이 자세안정성에 미치는 영향)

  • Hwang, Su-Jin;Woo, Young-Keun;Jeon, Hye-Seon
    • Physical Therapy Korea
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    • v.15 no.1
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    • pp.30-37
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    • 2008
  • This study was designed to examine the effects of temporary immobilization of the ankle and knee joints on standing in healthy young adults with the use of a postural control mechanism. The subjects were twenty-four college students (12 males and 12 females, aged between 20 and 28). A Biodex balance system SD 950-302 and its software were used to measure indirect balance parameters in standing. Each subject underwent postural stability tests in 4-different joint conditions: free joints, ankle immobilization only, knee immobilization only, and ankle and knee immobilization. In addition, the postural stability test was conducted once with the subject's eyes open and once with the eyes closed conditions. For data analysis of the postural stability tests, the overall stability index, antero-posterior stability index, and medio-lateral stability index were recorded. The overall stability index (p=.000) and medial-lateral index (p=.003) were significantly greater different conditions with eyes closed in postural stability. Therefore, the eyes closed condition is expected to be used as an effective postural stability training for treatment planning in patients with unstable postures. In addition, training based on the dynamic multi-segment model can improve postural stability and is available to therapeutic programs, helping people with unstable balance to reduce their risk of falling.

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Characteristics of Atmospheric Stability Index of Airmass thunderstorm day at Busan (부산지역 기단성 뇌우 발생일의 대기안정도지수 특성)

  • Jeon, Byung Il
    • Journal of Wetlands Research
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    • v.5 no.1
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    • pp.29-40
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    • 2003
  • This study was performed to research the relation between airmass thunderstorm and stability index with 12 years meteorological data(1990~2001) at Busan. Also We used the analysed stability indices from University of Wyoming to consider airmass thunderstorm. The frequency of thunderstorm occurrence during 12 years was 156 days(annual mean 13days). The airmass thunderstorm frequency was 14 days, most of those occurrence were summertime(59%). And occurrence hour of airmass thunderstorm was distributed from 1300LST to 2100LST broadly. The highest forecast index for airmass thunderstorm at Busan was K index, the lowest forecast index was SWEAT index. The forecasting of thunderstorms is based primary on the concepts of conditional instability, convective instability, and forced lifting of air near the surface. Instability is a critical factor in severe weather development. Severe weather stability indices can be a useful tool when applied correctly to a given convective weather situation.

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Effects of Knee Malalignment on Static and Dynamic Postural Stability

  • Chae, Yun-Won;Park, Ji-Won;Park, Seol
    • The Journal of Korean Physical Therapy
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    • v.27 no.1
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    • pp.7-11
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    • 2015
  • Purpose: This study was conducted in order to determine the effects of knee malalignment including genu varum, valgum, and recurvatum on static and dynamic postural stability. Methods: A total of 80 subjects were enrolled in this study. Subjects who showed over 3 cm in the distance between the knees were classified as the genu varum group, and subjects who showed over 3 cm in the distance between the ankles were classified as the genu valgum group. Subjects who showed over 1 cm in the distance between the patella and a table in prone position were classified as the genu recurvatum group. Static and dynamic stability were measured as overall, anterioposterior, and mediolateral balance index using a Biodex Balance System. Results: This study showed that knee alignment affected static and dynamic postural stability. In particular, there were significant differences in the mediolateral stability index among genu varum, valgum group, and the other groups, but no differences in overall and anteriolateral stability index. Significant differences in the anterioposterior stability index were observed between genu recurvatum and the other groups, however, there were no differences in overall and mediolateral stability index. Conclusion: The findings were that knee malalignment affects postural stability toward a specific direction. Treatment to improve postural stability for treatment of knee malalignment or to prevent falling or injuries is needed and postural stability toward a specific direction according to the knee alignment conditions should be considered.