• 농업생명과학연구
• /
• 제44권6호
• /
• pp.69-78
• /
• 2010

본 연구에서는 우리나라의 고층기상 관측자료와 수치모델(RDAPS 10km) 예상 자료를 활용하여 대기 불안정도와 건조도를 포함하는 산불잠재 위험지수인 Haines Index(HI)와 산불과의 관계를 분석하였고, 그 결과 산불 확산 잠재성이 높은 HI=5, 6은 4월에 가장 높게 나타났고, 대기의 안정도 보다는 건조도가 높게 나타났으며, 산불의 발생과 확산에 큰 영향을 주는 것으로 나타났다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
• /
• pp.259-264
• /
• 2005

연소불안정과 밀접한 관련이 있는 열방출의 측정은 연소불안정을 제어하는데 매우 중요하다. 따라서 본 연구에서는 희박예혼합연소에서 반응영역의 위치와 전체, 국소 열방출률의 지표로 많이 사용되는 $OH^{\ast}$ 이미지를 ICCD를 이용해 취득하였다. 본 연구의 목적은 당량비가 전체 열방출률과 국소 레일라이 지수 분포에 미치는 영향을 알아보는 것이다. 국소 레일라이 지수 분포는 선적분된 이미지를 아벨 역변환 시켜서 화염의 중앙 단면 정보를 통해 얻을 수 있었다. 각 당량비 조건에서, 한 주기 동안의 열방출의 평균값은 당량비가 증가함에 따라 지수 함수적으로 증가하였다. 국소 레일라이 지수 분포 결과로부터, 연소불안정을 증폭시키거나 소멸시키는 영역을 분명히 알 수 있었다. 이것은 넓은 당량비 조건에 대한 화염구조와 연소불안정 영역에 대한 통찰력을 제공한다.

• Structural Engineering and Mechanics
• /
• 제48권1호
• /
• pp.103-124
• /
• 2013

This paper studies the static and dynamic characteristics of composite plates subjected to an arbitrary periodic load in hygrothermal environments. The material properties of composite plates are depended on the temperature and moisture. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunction transforms. A periodic load is taken to be a combination of axial pulsating load and bending stress in the example problem. The regions of dynamic instability of laminated composite plates are determined by solving the eigenvalue problems based on Bolotin's method. The effects of temperature rise and moisture concentration on the dynamic instability of laminated composite plates are investigated and discussed. The influences of various parameters on the instability region and dynamic instability index are also investigated. The numerical results reveal that the influences of hygrothermal effect on the dynamic instability of laminated plates are significant.

• PNF and Movement
• /
• 제18권2호
• /
• pp.173-182
• /
• 2020

Purpose: The purpose of the study was to investigate the effects of visual feedback exercise (VFE), sandal exercise (SE), and thera-band exercise (TE) on people with functional ankle instability. Methods: The 45 study participants were divided into three groups of 15. In the VFE group, participants performed short-foot exercises using visual feedback; the SE group performed sandal exercises, and the TE group performed thera-band exercises. Over a period of 8 consecutive weeks, the experimental groups exercised for 15 minutes per session, four times per week. Balance was measured using the Biodex Balance System for dynamic balance ability (overall balance index [OBI], mediolateral balance index [MBI], and anterioposterior balance index [ABI]). Vibration threshold sense (VTS) was assessed using a vibratory sensory analyzer. Ankle muscular strength was measured using the Biodex 4 Pro. The main outcome measures were assessed at baseline and after 8 weeks of training. Results: Significant improvements in dynamic balance were noted in all three groups (p < 0.05). Significant improvements in VTS and muscular strength were also noted in the VFE and TE groups but not in the SE group (p < 0.05). Conclusion: Appropriate environmental and situational mediation may be of great clinical significance for patients suffering from chronic ankle instability. It is hoped that the findings will inform a program for prevention of ankle instability.

• The Journal of Asian Finance, Economics and Business
• /
• 제9권1호
• /
• pp.177-187
• /
• 2022

Theoretical literature agrees on the interaction between financial instability and economic activity but explains it's dynamic in two points of view: one is that the transmission mechanism occurs in one unique regime and the other reckons a shift of regime leads to the alteration of the transmission mechanism. This study aims to find evidence of the multi-regime transmission for ASEAN developing countries. The author employs the technique of Threshold vector auto regression using the financial stress index standing for financial instability. Monthly data is collected, covering a period long enough with many episodes of high stress in recent decades. There are two conclusions: (1) A financial shock has a negative and stronger impact on economic activity during a high-stress period than it does during a low-stress period; (2) the response of economic activity to a negative financial shock during high-stress periods is stronger than it is during normal times. The findings point to the importance of the financial stress index as an additional early warning indicator for the real economy sector, as well as the positive effect that a reduction in financial stress may have on economic activity, implying the importance of "unconventional" monetary policy in times of high financial stress.

• 대한통합의학회지
• /
• 제11권1호
• /
• pp.121-130
• /
• 2023

Purpose : This study aimed to investigate the effect of blood flow restriction exercise on ankle muscle strength and balance ability to achieve maximum efficiency with the same exercise intensity and time. Methods : Twenty-six adults are randomly assigned to experimental group (n=13) and comparison group (n=13). The experimental group performed ankle joint strength exercises with blood flow restriction applied while the comparison group performed ankle joint strength exercises without blood flow restriction applied three times a week for four weeks. The digital muscle measurement, Y-balance test, and Cumberland ankle instability tool were used to evaluate the subject's muscle strength, dynamic balance, and ankle instability index before and after the intervention. Results : In within-group comparison muscle strength, all the two groups showed significant improvements post intervention (p<.05). In between-group comparison, there was significant difference in the change of dorsiflexion, eversion strength pre and post intervention (p<.05). but plantarflexion was no significant difference between pre and post intervention in the group comparison (p>.05). In within-group comparison dynamic balance, all the two groups showed significant improvements post intervention (p<.05). In between-group comparison, there was no significant difference in the change of Y-balance score pre and post intervention (p>.05). In within-group comparison ankle instability index, all the two groups showed significant improvements post intervention (p<.05). In between-group comparison, there was no significant difference in the change of CAIT score pre and post intervention (p>.05). Conclusion : The results of this study show that ankle joint strength exercise improved the strength and balance ability of those complaining of chronic ankle instability, and ankle joint strength exercise applied with blood flow restriction was more effective in dorsiflexion and eversion strength exercise than ankle joint strength exercise without blood flow restriction.

• 한국전문물리치료학회지
• /
• 제27권4호
• /
• pp.292-297
• /
• 2020

Background: Ankle sprain is one of the most common musculoskeletal injuries in the sports population or during usual daily life activities. The sprain can cause functional ankle instability (FAI), and it is very important to treat FAI. However, the optimum intervention method for FAI has yet to be determined. Objects: This study investigated the impact that virtual reality (VR) training program on balance with ankle kinesio taping for FAI. Methods: Twenty-two people were selected for the study and randomly divided into the experimental (n = 11) and the control group (n = 11). The experimental group had attached kinesio taping on the ankle and then implemented a virtual reality exercise program for 30 minutes a day. Nintendo Wii Fit Plus was used for the VR intervention three times a week for four weeks. The control group performed only two measurements without intervention. Results: There were no statistically significant differences in overall, anterior-posterior (AP), medial-lateral (ML) index of the static balance, and significant differences in overall, AP, ML index of the dynamic balance when taping and VR exercise were applied at the same time (p < 0.05). There were no significant differences in overall and ML index of static and dynamic balance compared with before and after assessment between the experimental and the control group, and found differences in AP index of static and dynamic balance (p < 0.05). Conclusion: Kinesio taping may not influence the balance of FAI as great as people expected. VR approach does not affect the static balance of FAI, but it influences dynamic balance in overall, AP, ML index. The authors suggest that VR-based exercises can be used as an additional concept in clinicians for FAI or as part of a home program because the exercises still have limitations.

• Journal of Electrical Engineering and Technology
• /
• 제4권4호
• /
• pp.438-442
• /
• 2009

Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.

• 대한통합의학회지
• /
• 제9권1호
• /
• pp.123-131
• /
• 2021

Purpose : The time spent using smart devices is constantly increasing, particularly in recent times. Using smart devices for a long time with an incorrect posture may lead to cerebral palsy (CP), instability, and abnormal muscle tone. Therefore, we aimed to investigate the relationships among cervical instability, deep neck flexor (DNF) activity, range of motion (ROM), and muscle tonus. Methods : Fifty subjects with CP participated in this study, and they were physiotherapists at W Hospital in Daejeon. Those who voluntarily participated in the research were selected as candidates who fulfilled the selection criteria. According to an instability test, 25 subjects were assigned to the instability and control groups. All subjects first underwent the instability test to be allocated to the appropriate group. Those in the instability group tested positive on the instability test. The Neck Disability Index (NDI), ROM, muscle tone, and DNF activity were measured to evaluate their relationships. The DNF strength and endurance were measured using a cranio-cervical flexion test. The upper trapezius (UT), sternocleidomastoid (SCM), and suboccipital (SO) muscle tones were measured using a contact soft tissue tone measuring instrument. The statistical significance level was set to .05. Results : There were significant differences in the flexion, extension, and rotation of the cervical ROM (CROM) between the two groups (p<.05). The SCM, UT, and SO muscle tones were significantly different between the two groups (p<.05). The DNF strength and endurance showed a significant difference between the two groups (p<.05). Conclusion : We found that there were significant increases in the CROM and muscle tone and decrease in the DNF strength and endurance in the instability group. This indicated that cervical instability is affected by the DNF strength and endurance. We may recommend DNF exercises in cases of cervical instability in clinical environments.

• 대한물리의학회지
• /
• 제8권1호
• /
• pp.29-39
• /
• 2013

PURPOSE: The purpose of this study was to determine if the program focusing on gluteal muscle exercise combined lumbar stabilization had an effects on pain, functional disability and lumbar instability in chronic low back pain patients who had lumbar instability. METHODS: Thirty four patients were recruited in this study. The participants were randomly allocated stabilization exercise group (SEG) (n=17) and gluteal muscle exercise group (GEG) (n=17). The gluteal muscle exercise group conducted gluteal muscle exercises combined lumbar stabilization and stabilization exercise group did only lumbar stabilization exercise for 30 minutes three times a week for six weeks. Pre-exercise assessment tools, visual analogue scale (VAS) and Korean version Oswestry Disability Index level (KODI) were used for pain and functional disability each. Also, these were scored by the tool of lumbar instability. The pain, functional disability levels, and lumbar instability after six weeks with this exercise were re-evaluated. RESULTS: First, SEG showed a significant decrease in the lumbar pain, functional disability levels and lumbar instability. Second, GEG showed a significant decrease in the lumbar pain, functional disability levels and lumbar instability. The third, GEG showed even more significant decrease in the lumbar pain levels, functional disability levels and lumbar instability than SEG. CONCLUSION: Gluteal muscle exercises combined lumbar stabilization are more effective than only lumbar stabilization exercise in the pain levels, functional disability levels and lumbar instability for the chronic low back pain patients with lumbar instability.