• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.246-259
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• 2021

IMO stability regulations include various stability parameters such as GM values. To assess the stability of the ships, we should check all stability parameters of the IMO requirements. However, since this process is complex, a more convenient way to evaluate stability performance is required. In this research, the index for marine ship intact stability assessment (IMSISA) model was developed to solve these problems. The IMSISA model consists of a stability index calculation module and a stability assessment module. In the stability index calculation module, ten stability parameters, including GM, were used to develop the stability index, which has the advantage of being able to quantify the ship stability. The stability assessment module uses the stability index value to determine the stability status of the ship and provides the captain with stability management guidelines. To verify the proposed model, the basic stability calculations were performed for two model ships in 32 loading situations. The proposed model was found to provide better performance in the stability assessment than the previous study. By applying the IMSISA model to the ships, the captain can assess the ship stability more quantitatively and efficiently.

• 해양환경안전학회지
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• 제24권1호
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• pp.1-9
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• 2018

선박의 안전 확보를 위해 준수해야 하는 IMO 복원성 규칙에는 복원정 곡선(GZ Curve) 등에 관한 내용이 다양하게 규정되어 있다. 이 IMO 복원성 규정에는 다양한 항목의 만족 기준이 제시되고 있으나, 선박을 운항하는 선장에게 선박의 복원성능을 종합적이며, 간편하게 제공할 수 있는 방법은 부재한 상황이다. 이를 위해 본 연구에서는 복원성을 하나의 값으로 표현할 수 있는 지수를 개발하였다. IMO에서 규정한 선박의 6가지 복원성 항목과 대상선박의 적재상황에 따른 복원성 계산결과를 바탕으로 지수산정식이 도출되었다. 또한 개발된 지수산정식을 적용하여 다양한 화물 적재 상황별 복원성 지수(Stability Index)를 계산하였으며, 복원성능의 전반적인 정도를 수치적으로 적절하게 설명할 수 있음을 검증하였다. 이는 선박의 선장에게 복원성 평가하고 판단하는데 도움을 줄 것으로 판단된다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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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.

• 한국과학교육학회지
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• 제13권3호
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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.

• 한국운동역학회지
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• 제22권3호
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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.

• The Journal of Korean Physical Therapy
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• 제24권6호
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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.

• Journal of Welding and Joining
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• 제8권1호
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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.

• 한국전문물리치료학회지
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• 제15권1호
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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.

• 한국습지학회지
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• 제5권1호
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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.

• The Journal of Korean Physical Therapy
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• 제27권1호
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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.