• Physical Therapy Rehabilitation Science
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• 제11권4호
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• pp.585-590
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• 2022

Objective: The purpose of this study was to investigate the effects of neuromuscular training of ballet dancers with chronic ankle instability on ankle stability and posture controlability. Design: A randomized controlled trial. Methods: A total of Thirty-twoyoung female ballet dancers with chronic ankle instability have voluntarily participated in the study. The participants were randomized to the neuromuscular training group(n₁=11), elastic resistance squat group(n₂=11), and control group(n₃=10). The intervention was applied to a total of 18 exercises per six weeks and conducted in each group for one hour a day, three times a week. All subjects were evaluated for Cumberland ankle instability tool(CAIT), static balance at before-after intervention. Results: In the comparison of the effects within the groups, the effect of the intervention on CAIT and posture control was significantly increased in the neuromuscular training group and elastic resistance squat group (p <0.05). In the comparison of the effects between the groups, the neuromuscular training group, and elastic resistance squat group were found to significantly increase more than the control group (p <0.05). The effect of ankle stability is similar in neuromuscular training and elastic resistance squat training, neuromuscular training is more effective in improving posture control rather than elastic resistance squat training. Conclusions: When planning a rehabilitation training program for a ballet dancer with chronic ankle instability, neuromuscular training can be applied as an intervention method to improve ankle stability and posture control ability.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.503-507
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• 2014

The on-state resistance ($R_{ON}$) instability of standard complementary metal-oxide-semiconductor (CMOS) antifuse cells has been observed for the first time by using acceleration factors: stress current and ambient temperature. If the program current is limited, the $R_{ON}$ increases as time passes during read operation.

• 한국응용곤충학회지
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• 제31권3호
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• pp.314-327
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• 1992

Insecticide resistance is a serious is a serious threat to IPM, resulting in various adverse effects not to mention the loss of yield in agriculture. One approach to counter the problem is the disruption of resistance mechanisms. This can be achieved by (1) compounds which show a negative correlation with resistance at the site of action, (2) specific metabolic inhibitors which serve as synergists, or (3) a certain combination of two insecticides producing a joint action. This approach, however, requires certain precautions for the side effects may cause an increase in toxicity to mammals. Owing to the recent advances in theoretical studies on resistance management employing computer simulation and mathematical models, a few principles to reduce the risk of development of resistance have been clarified. They are helpful in designing operational strategies with regard to, for instance, insecticide doses to be applied, mode of application, and choice and nature of the insecticide(s) to be used. For restoration of insecticide susceptibility of a resistant population, reintroduction of susceptible individuals to the resistant population is feasible when certain conditions are met. Natural enemies which developed resistance to insecticides can be an important component of IPM as has been shown in the pest management in apple orchards. After all, the implementation of a successful resistance management program depends upon cooperation between different sigments of the agricutural community. Although resistance is a preadaptive phenomenon, in some cases spontaneous loss of resistance does occur without contamination by susceptible individuals. The instability of resistance in these insects implies the possible existence of a switch machanism controlling the expression of resistance gene(s). Elucidation of such a mechanism may eventually provide us with a new technical approach with which we can combat the problem of insecticide resistance.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.129-136
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• 2005

Concentrically braced steel frames are considered as being quite prone to soft-story response due to the degradation in brace compressive resistance after buckling under severe ground motions. When combined with the system P-Delta effects, collapse of the concentrically braced frames by dynamic instability becomes a highly probable. In this study, a new, relatively simple dynamic instability coefficient was proposed for diagonally braced steel frames by considering the strength degradation of the brace after buckling. Nonlinear dynamic analysis was conducted to check the robustness of the proposed index based on simulated ground motions. The analysis results showed that the dynamic instability index proposed predicts the collapse potential more consistently than the conventional one. Dynamic instability was triggered when the index value was close to 0.7.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.288-295
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• 2004

Concentrically braced steel frames are considered as being quite pone to soft-story response due to the degradation in brace compressive resistance after buckling under severe ground motions. When combined with the system P-Delta effects, collapse of the concentrically brsced frames by dynamic instability becomes highly probable. In this stidy, a new, relatively simple dynamic instability coefficient was proposed for diagonally braced steel flames by explicitly considering the strength degradation of the brace after buckling. Nonlinear dynamic analysis results showed that the dynamic instability coefficient proposed in this study predicted collapse limit state more consistently than the conventional one which ignores the strength degradation of the brace.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.734-741
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• 2020

A new air-cooled waste heat removal system with a direct contact heat exchanger was designed for SMRs requiring 200 MW of waste heat removal. Conventional air-cooled systems use fin structure causing high thermal resistance; therefore, a large cooling tower is required. The new design replaces the fin structure with a vertical string type direct contact heat exchanger which has the most effective performance among tested heat exchangers in a previous study. The design results showed that the new system requires a cooling tower 50% smaller than that of the conventional system. However, droplet formation on a falling film along a string caused by Rayleigh-Plateau instability decreases heat removal performance of the new system. Analysis of Rayleigh-Plateau instability considering drag force on the falling film surface was developed. The analysis results showed that the instability can be prevented by providing thick string. The instability is prevented when the string radius exceeds the capillary length of liquid by a factor of 0.257 under stagnant air and 0.260 under 5 m/s air velocity.

• 대한족부족관절학회지
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• 제22권3호
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• pp.91-94
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• 2018

Ankle sprain is one of the most common musculoskeletal injuries. Although most ankle sprains respond well to conservative measures, chronic instability following an acute sprain has been reported to occur in 20% to 40% of patients. Some individuals are eventually indicated for a lateral ankle ligament reconstruction due to persistent ankle instability. More than 80 surgical procedures have been described to address lateral ankle stability. These range from direct repair of the anterior talofibular ligament (ATFL) and of the calcaneofibular ligament (CFL) to reconstructions based on the use of autograft or allograft tissues. However, the best surgical option remains debatable. The modified $Brostr{\ddot{o}}m$ procedure is most widely used for direct ligament repair, but not always possible because of the poor ATFL or CFL quality or deficiency of these ligaments, which prevents effective shortening imbrication. Furthermore, the importance of a CFL reconstruction has been emphasized recently. On the other hand, it is difficult to achieve an efficient CFL reconstruction during the $Brostr{\ddot{o}}m$ procedure. Others have reported that an anatomic reconstruction of injured ligaments restores the normal resistance to anterior translation and inversion without restricting subtalar or ankle motion, and as a result, anatomic reconstructions for lateral ankle instability utilizing an autograft or allograft tendon have gained popularity.

• 대한기계학회논문집
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• 제13권5호
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• pp.928-937
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• 1989

본 연구에서는 Shih등이 제안한 찢어짐 계수인 Ｔ$_{\delta}$의 불안정 파괴 매개 변수로서의 적용 가능성을 컴팩트 인장 시편(compact tension specimen dlgk CTS로 칭함)을 사용하여 검토한다. 이를 위하여 시험기에 스프링을 부착하여 시편에 불안정 파괴 실험을 수행한다. 재료의 불안정성을 판정하는 찢어짐 계수를 구하기 위해서는 CTOD-정항 곡선을 결정해야 한다. CTOD는 하중선 변위를 측정하여 CTOD- 하중선 변위 관계식으로 평가한다.한다.

• Journal of Power Electronics
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• 제17권5호
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• pp.1298-1307
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• 2017

The constant on-time current-mode controlled (COT-CMC) switching dc-dc converter is stable, with no subharmonic oscillation in its current loop when a voltage ripple in its outer voltage loop is ignored. However, when its output capacitance is small or its feedback gain is high, subharmonic oscillation may occur in a COT-CMC buck converter with a proportional-integral (PI) compensator. To investigate the subharmonic instability of COT-CMC buck converters with a PI compensator, an accurate reduced-order asynchronous-switching map model of a COT-CMC buck converter with a PI compensator is established. Based on this, the instability behaviors caused by output capacitance and feedback gain are investigated. Furthermore, an approximate instability condition is obtained and design-oriented stability boundaries in different circuit parameter spaces are yielded. The analysis results show that the instability of COT-CMC buck converters with a PI compensator is mainly affected by the output capacitance, output capacitor equivalent series resistance (ESR), feedback gain, current-sensing gain and constant on-time. The study results of this paper are helpful for the circuit parameter design of COT-CMC switching dc-dc converters. Experimental results are provided to verify the analysis results.

• Ocean Systems Engineering
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• 제4권2호
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• pp.117-136
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• 2014

The increased interest in the design of energy efficient ships post IMO regulation on enforcing EEDI has encouraged researchers to reevaluate the numerical methods in predicting important hull design parameters. The prediction of added resistance and stability of ships in the rough sea environment dictates selection of ship hulls. A 3D panel method based on Green function is developed for vessel motion prediction. The effects of parametric instability are also investigated using the Volterra series approach to model the hydrostatic variation due to ship motions. The added resistance is calculated using the near field pressure integration method.