• 자원ㆍ환경경제연구
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• 제9권2호
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• pp.333-347
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• 2000

We employed various econometic methods to estimate the production index elasticity and the price elasticity of elecricity demand in Korea and compared the forecasting power of those methods. Cointegration models (ADL model, Engle-Granger model, Full Informtion Maximum Likelihood method by Johansen and Juselius) and Dynamic OLS by Stock and Watson were considered. The forecasting power test shows that Dynamic OLS has the best forecasting power. According to Dynamic OLS, the production index elasticity and the price elasticity of electricity demand in Korea are 0.13 and -0.40, respectively.

• The Journal of Asian Finance, Economics and Business
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• 제7권8호
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• pp.533-542
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• 2020

This study estimates the nature of the relationship of entrepreneurship and business confidence on youth unemployment in the Philippines over the 2001-2017 period. The paper employed a range of cointegrating regression models, namely, autoregressive distributed lag (ARDL) bounds testing approach, Johansen-Juselius (JJ) and Engle-Granger (EG) cointegration models, dynamic OLS, fully modified OLS, and canonical cointegrating regression (CCR) estimation techniques. The Granger causality based on error correction model (ECM) was also performed to determine the causal link of entrepreneurship and business confidence on youth unemployment. The ARDL bounds testing approach, Johansen-Juselius (JJ) and Engle-Granger (EG) cointegration models confirmed the existence of long-run equilibrium relationship of entrepreneurship and business confidence on youth unemployment. The long-run coefficients from JJ and dynamic OLS show significant long-run and positive relationship of entrepreneurship and business confidence on youth unemployment. While results of the long-run coefficients from fully modified OLS and canonical cointegrating regression (CCR) found that only entrepreneurship has significant and positive relationship with youth unemployment in the long-run. The Granger causality based on error correction model (ECM) estimates show evidence of long-run causal relationship of entrepreneurship and business confidence on youth unemployment. In the short-run, increases in entrepreneurship and business confidence causes youth unemployment to decrease.

• Physical Therapy Rehabilitation Science
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• 제9권3호
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• pp.165-170
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• 2020

Objective: To investigate the association between one-leg standing ability and postural control for chronic hemiparetic stroke. Design: Cross-sectional study. Methods: Forty individuals who had a first diagnosis of stroke with hemiparesis before six months and over had participated in this study. To analyze the relationship between one-leg standing ability and postural control in the participants, six clinical measurement tools were used for assessment, including the Timed-Up-and-Go (TUG) test, Berg Balance Scale (BBS), Dynamic Gait Index (DGI), Fugl-Meyer Assessment (FMA), 5 times sit-to-stand (5TSTS) and one-leg standing (OLS). Results: After analyzation, the OLS scores in the more-affected side showed significant positive correlations with BBS scores (r=0.469, p<0.01), DGI scores (r=0.459, p<0.01).and FMA scores (r=0.425, p<0.01). The OLS scores in the more-affected side showed significant negative correlations with TUG score (r=-0.351, p<0.05). The OLS score in the less-affected side showed significant positive correlations with BBS scores (r=0.485, p<0.01), DGI scores (r=0.488, p<0.01) and FMA score (r=0.352, p<0.05). The OLS scores in the less-affected side showed significant negative correlation with TUG scores (r=-0.392, p<0.05) and 5TSTS (r= -0.430, p<0.01). The OLS scores in the more-affected side showed significant positive correlations with the OLS scores in less-affected side (r=0.712, p<0.01). Conclusions: The results of the study suggest that the OLS time may be moderately correlated with static and dynamic postural stabilities and motor recovery following stroke. This study also suggests that the OLS test is as a simple clinical tool for predicting postural control performance for individuals with chronic hemiparetic stroke.

• 자원ㆍ환경경제연구
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• 제9권1호
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• pp.49-69
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• 1999

본 연구는 1983년부터 1996년까지의 월별 자료를 이용하여, 전력 수요의 장기 탄력성을 추정하였다. 공적분모형인 Stock-Watson(1993)의 동태적 OLS(Dynamic OLS) 모형을 이용하여, 전력수요의 장기가격탄력성과 소득탄력성을 추정하였다. 장기균형식을 이용한 결과를 살펴보면, 실질국내총생산의 장기탄력성은 0.23으로 나타났으며, 실질전력요금의 장기탄력성은 -0.12로 추정되었다. 이와 같은 결과는 가격과 소득이 전력수요에 직접적 영향을 미치는 것을 의미한다. 단기오차수정모형에서 오차수정항의 계수는 -0.23으로 추정되었으며, 이는 단기적으로 장기수요곡선을 이탈하였을 경우 단기적 불안정이 새로운 균형을 찾아가는 기간이 약 4.4 개월 걸리는 것을 의미한다.

• Elastomers and Composites
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• 제41권4호
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• pp.260-267
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• 2006

유기화 클레이(organically modified layered silicates)가 보강된 SBR 나노 복합체를 라텍스법(latex method)에 의해서 제조하였다. 유기화 MMT는 dodecylamine으로 유기화한 DA-MMT와 dimethyldodecylamine으로 유기화한 DDA-MMT의 두 가지를 제조하였다. 유기화 클레이의 층간거리와 분산도를 확인하기 위하여 XRD와 TEM촬영을 하였다 Na-MMT, DA-MMT, DDA-MMT의 XRD 회절 패턴을 분석한 결과 Na-MMT는 $2{\theta}=7.2^{\circ}$로써 층간거리가 $12.3{\AA}$, DA-MMT는 $2{\theta}=5.1^{\circ}$로 층간거리가 $17{\AA}$를 나타내었으며, DDA-MMT의 경우, 회절 피크는 $2{\theta}=4.8^{\circ}$로써. 층간거리는 $18.4{\AA}$으로 나타났다. 이는 DDA-MMT와 DA-MMT가 각각 5 phr 첨가된 SBR 나노 복합체의 TEM 결과에서도 확인할 수 있었다. SBR 나노 복합체에 filler system (carbon black/silica/OLS)을 적용 후 시편을 제조하였다. 제조된 시편의 동적 점탄성 평가 (DMTA)는 $-20^{\circ}C{\sim}80^{\circ}C$ 사이에서 이루어졌으며, loss factor (tan $\delta$)의 거동을 확인하였다. 그 결과, 타이어 트래드용 컴파운드를 대상으로 할 경우, 카본블랙과 실리카의 혼용비가 35:25일 때, 빗길 제동특성과 연비특성을 대변하는 $0^{\circ}C$와 $50{\sim}60^{\circ}C$에서의 tan $\delta$가 가장 우수함을 알 수 있었다. 또한 이 시스템에 실리카의 일정 부분을 DDA-MMT($0{\sim}10phr$)로 대체할 경우, $0^{\circ}C$의 tan $\delta$값은 높아지는 반면, $50{\sim}60^{\circ}C$의 tan $\delta$값은 감소하였다.

• Macromolecular Research
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• 제17권10호
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• pp.776-784
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• 2009

N,N-dimethyldodecylamine (tertiary amine)-modified MMT (DDA-MMT) was prepared as an organically modified layered silicate (OLS), after which styrene-butadiene rubber (SBR) nanocomposites reinforced with the OLS were manufactured via the latex method. The layer distance of the OLS and the morphology of the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By increasing the amount of N,N-dimethyldodecylamine (DDA) up to 2.5 g, the maximum values of torque, tensile strength and wear resistance of the SBR nanocomposites were increased due to the increased dispersion of the silicate layers in the rubber matrix and the increased crosslinking of the SBR nanocomposites by DDA itself. When SBR nanocomposites were manufactured by using the ternary filler system (carbon black/silica/OLS) to improve their dynamic properties as a tire tread compound, the tan $\delta$(at $0^{\circ}C$ and $60^{\circ}C$) property of the compounds was improved by using metal stearates instead of stearic acid. The mechanical properties and wear resistance were increased by direct substitution of calcium stearate for stearic acid because the filler-rubber interaction was increased by the strong ionic effect between the calcium cation and silicates with anionic surface. However, as the amount of calcium stearate was further increased above 0.5 phr, the mechanical properties and wear resistance were degraded due to the lubrication effect of the excessive amount of calcium stearate. Consequently, the SBR/organoclay nanocomposites that used carbon black, silica, and organoclay as their ternary filler system showed excellent dynamic properties, mechanical properties and wear resistance as a tire tread compound for passenger cars when 0.5 phr of calcium stearate was substituted for the conventionally used stearic acid.

• PNF and Movement
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• 제8권1호
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• pp.67-77
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• 2010

Purpose : The purpose of this study was to investigate the usefulness of clinical balance tests through the correlation of balance evaluation using by forceplate in elderly. Methods : Thirty nine healthy elderly subjects (14 males, 25 females) participated in the study. The subjects were evaluated with clinical balance tests [(Berg balance scale (BBS), Functional reach test (FRT), Tinetti's performance oriented mobility assessment (POMA), and one leg standing (OLS)]. Static balance evaluation was assessed by using forceplate. Center of pressure (COP) parameters were obtained using it as total path distance, total sway area, X mean frequency and Y mean frequency for 20 seconds in the following conditions: (1) comfortable standing with eyes opened and closed, (2) uncomfortable standing with eyes opened and closed. After static balance evaluation tested, dynamic balance evaluation was assessed. COP parameters were error distance and area during sine curve trace. COP parameters were movement time, error distance, and maintained time in the circle during COP movement task. Results : Clinical balance tests showed statistically significant correlation between static and dynamic balance evaluations. Among the clinical balance tests, the BBS, POMA, and OLS showed significant correlation with to assess the balance ability of elderly in clinical setting both evaluations. Conclusion : Clinical balance tests can be recommended in clinical setting because of low costs and simplicity.

• 국제지역연구
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• 제20권3호
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• pp.3-22
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• 2016

본 연구는 중국의 에너지 수요함수를 추정하기 위해 다양한 방법 중 Dynamic OLS(DOLS) 모형을 이용하고, 그 결과를 표준 공적분 모형과 비교하였다. 내생성을 고려한 DOLS 모형은 Johansen 방법과 비슷한 추정값을 보이지만, Engle-Granger(EG) 모형은 편의를 가지는 것으로 나타났다. DOLS 모형의 결과를 중심으로 살펴보면 중국의 에너지 수요함수 추정결과 노동인구 1인당 실질 GDP가 1% 상승하면 에너지 소비가 0.83% 증가하고, 에너지 가격 1%가 상승하면 에너지 수요는 0.45% 정도 감소하는 것으로 나타났다. 향후 중국의 에너지 소비는 지속적으로 성장할 것으로 예상되며, 우리나라는 세계 에너지 수요 증가와 온실가스 저감에 대비하는 에너지 정책을 수립해야 한다.

• Physical Therapy Rehabilitation Science
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• 제9권4호
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• pp.275-280
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• 2020

Objective: Compression wear is an external aid which promotes performance and recovery, diminishes muscular microtrauma, reduces muscle fiber recruitment, improves neuromechanics, enhances coordinative activities, and reduces the perceived exertion. The purpose of this study was to investigate the relationship between athletic taping and compression wear on dynamic postural balance in healthy young men. The hypothesis was that the athletic taping and compression wear would affect dynamic postural balance, with athletic taping having a different effect on dynamic postural balance in healthy young adults. Design: Cross-sectional study. Methods: Thirty-seven healthy young men participated in this study. To examine the association between athletic taping and compression wear, 3 clinical measurement tools, including 5 times sit-to-stand (5xSTS), one-leg standing (OLS) test, and Y-balance test (YBT) in 5 different conditions, namely (1) non-supporting, and support with (2) athletic taping, (3) regular compression wear, (4) silicon compression wear, and (5) double-fiber compression wear were used. Results: The distance of the Y-balance test (YBT) on both the dominant and non-dominant sides showed a statistically difference among the 5 supporting conditions (p<0.05). The distance measured via the YBT in the non-support condition was significantly different than that in the other four supporting conditions (p<0.05). However, 5xSTS and OLS were not significantly different in these supporting conditions. Conclusions: The results of this study suggest that athletic taping, silicon compression wear, and double-fiber compression wear were more effective for dynamic balance than non-supporting and regular compression wear.

• 대한물리의학회지
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• 제14권1호
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• pp.75-89
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• 2019

PURPOSE: This study measured the impact of a 12-week fall-prevention exercise program on balance, ambulatory ability, lower limb strength, and psychosocial characteristics in older adults diagnosed with dementia. METHODS: The participants comprised 31 older adults (9 men, 22 women) diagnosed with Alzheimer's or vascular dementia at a long-term care hospital located in Gunsan City. A fall-prevention exercise program was provided to the experimental group, while the control group was only provided with instruction and materials related to the fall-prevention exercise program. The participants were evaluated before the intervention, 6 weeks after the intervention, and 12 weeks after the intervention on static and dynamic balance abilities (using Timed Up and Go test: TUG, Tinetti-balance scale, one-leg standing test: OLS), gait (Tinetti-balance scale, 6-minute walk test: 6MWT), lower limb strength (sit to stand test; STS), and psychosocial characteristics (Short Form 36 Health Survey-Korean version, Korean Mini-Mental State Exam). RESULTS: An independent samples t-test and repeated measures analysis of variance were used for the statistical analysis. There were statistically significant improvements after the intervention (p<.05) in dynamic balance abilities (TUG and OLS using the left foot), gait (6MWT), and lower limb strength (STS) for the experimental group, but not for the control group. No difference was seen in psychosocial characteristics. CONCLUSION: Older adults with dementia who participated in the fall-prevention exercise program showed significant improvements in their static and dynamic balance abilities, lower limb strength, and ambulatory ability after the intervention.