• Physical Therapy Rehabilitation Science
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• 제10권3호
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• pp.311-319
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• 2021

Objective: To investigate the effect of emphasized initial contact by using a wearable air-pressure insole to provide auditory-feedback with variations of maximum peak pressure (MPP) of the affected side on spatiotemporal gait parameters and gait symmetry of stroke patients Design: A cross-sectional study Methods: Eighteen stroke patients participated in this study. All subjects walked five trials using an air-pressure insole that provides auditory feedback with different thresholds set on the insole. First, subjects walked without any auditory feedback. Then, the MPP threshold on the affected side was set from 70% and increase threshold by 10% after each trial until 100%. They walked three times or more on the gait analyzer for each trial, and the average values were measured. Before starting the experiment, subjects measured body weight, initial gait abilities and affected side MPP without auditory feedback. Results: Temporal and spatial variables were significantly increased in trials with auditory feedback from air-pressure insole except for non-paralyzed single support time and spatial gait symmetry compared to trials without auditory feedback(p<0.05). Among the four different thresholds, the walking speed, unaffected side single support time, affected and unaffected side stride, and affected side step length were greatest at 80% threshold of maximum peak, while affected single support time, temporal gait symmetry, and unaffected step length were greatest at the maximum peak of 100% threshold. Conclusions: These results indicate that auditory feedback gait using air-pressure insoles can be an effective way to improve walking speed, single support time, step length, stride, and temporal gait symmetry in stroke patients.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1138-1147
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• 2018

Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demanding environment of nuclear reactors. The threshold stress intensity factor, $K_{IH}$, and critical hydride length, $l_C$, are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubes undergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tip and thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip is proposed according to the fracture mechanics theory of second-order estimate of plastic zone size. The developed models with fewer fitting parameters are validated with the experimental results for $K_{IH}$ and $l_C$. The research results for radial cracking cases indicate that a better agreement for $K_{IH}$ can be achieved; the negative axial thermal stresses can lessen $K_{IH}$ and enlarge the critical hydride length, so its effect should be considered in the safety evaluation and constraint design for fuel rods; the critical hydride length $l_C$ changes slightly in a certain range of stress intensity factors, which interprets the phenomenon that the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis of model parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease in the critical hydride length $l_C$, and $K_{IH}$ will firstly decrease and then have a trend to increase with the yield strength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values of threshold stress intensity factor and critical hydride length at higher temperatures, which might be the main mechanism of crack arrest for some Zircaloy materials.

• 응용통계연구
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• 제36권4호
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• pp.295-307
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• 2023

HAR 모형은 간단한 선형 모형으로 실현 변동성의 장기기억성을 비교적 잘 설명할 수 있어 널리 쓰이고 있다. 하지만, 실현 변동성은 조건부 이분산성, 레버리지 효과, 변동성 집중 등과 같은 복잡한 특징을 보이고 있기에 단순 HAR 모형을 확장할 필요가 있다. 따라서 본 연구는 조건부 이분산성을 설명하는 GARCH 모형에 임계값에 따라 계수가 달라지는 비선형 모형인 임계 HAR 모형(THAR-GARCH)을 제안하고 그 추정 방법 및 예측 성능에 대해서 살펴보고자 한다. 보다 구체적으로 오차항의 등분산 가정을 벗어났기 때문에 모형의 계수를 추정하기 위해서 반복적인 가중최소제곱추정법을 제안하고 모의실험을 통해 일치성을 보였다. 또한 전세계 21개의 주요 주가 지수의 실현 변동성에 대한 예측 오차를 비교함으로써 제안한 GARCH 오차를 가지는 임계 HAR 모형이 일반적으로 더 우수한 예측력을 보임을 확인하였다.

• Journal of Audiology & Otology
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• 제23권3호
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• pp.145-152
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• 2019

Background and Objectives: The present study aims to investigate whether the cochlear implant electrode array design affects the electrophysiological and psychophysical measures. Subjects and Methods: Eighty five ears were used as data in this retrospective study. They were divided into two groups by the electrode array design: lateral wall type (LW) and perimodiolar type (PM). The electrode site was divided into three regions (basal, medial, apical). The evoked compound action potential (ECAP) threshold, T level, C level, dynamic range (DR), and aided air conduction threshold were measured. Results: The ECAP threshold was lower for the PM than for the LW, and decreased as the electrode site was closer to the apical region. The T level was lower for the PM than for the LW, and was lower on the apical region than on the other regions. The C level on the basal region was lower for the PM than for the LW whereas the C level was lower on the apical region than on the other regions. The DRs on the apical region was greater for the PM than for the LW whereas the DR was narrower on the apical region than on the other regions. The aided air conduction threshold was not different for the electrode design and frequency. Conclusions: The current study would support the advantages of the PM over the LW in that the PM had the lower current level and greater DR, which could result in more localized neural stimulation and reduced power consumption.

• 대한청각학회지
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• 제23권3호
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• pp.145-152
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• 2019

Background and Objectives: The present study aims to investigate whether the cochlear implant electrode array design affects the electrophysiological and psychophysical measures. Subjects and Methods: Eighty five ears were used as data in this retrospective study. They were divided into two groups by the electrode array design: lateral wall type (LW) and perimodiolar type (PM). The electrode site was divided into three regions (basal, medial, apical). The evoked compound action potential (ECAP) threshold, T level, C level, dynamic range (DR), and aided air conduction threshold were measured. Results: The ECAP threshold was lower for the PM than for the LW, and decreased as the electrode site was closer to the apical region. The T level was lower for the PM than for the LW, and was lower on the apical region than on the other regions. The C level on the basal region was lower for the PM than for the LW whereas the C level was lower on the apical region than on the other regions. The DRs on the apical region was greater for the PM than for the LW whereas the DR was narrower on the apical region than on the other regions. The aided air conduction threshold was not different for the electrode design and frequency. Conclusions: The current study would support the advantages of the PM over the LW in that the PM had the lower current level and greater DR, which could result in more localized neural stimulation and reduced power consumption.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.599-602
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• 1998

In this paper, a speech enhancement method based on phonemic properties and masking effect is propsoed. It is a modified type of spectral subtraction wherein the spectral sharpening process is exploited in unvoiced state considering the phonemic properties. The masking threshold is used to remove the residual noise. The proposed spectral subtraction shows similar performance as that of the classical spectral subtraction method in view of the SNR. But by the prposed scheme, the unvoiced sound region is shown to exhibit relatively less signal distortion in the enhanced speech.

• 전기의세계
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• 제28권11호
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• pp.33-36
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• 1979

In a uniform field, when an electrode with a hemispherical protrusion is set in atmosphere, by applying the streamer breakdown criterion and the surface roughness factor, the effect of field distortion due to electrode surface roughness on breakdown is investigated theoretically. A quantitative relation between the threshold of breakdown and the air pressure times the heigh of protrusion is derived by the aid of a computor and the results are compared with that of SF$_{6}$./.

• 전기의세계
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• 제24권5호
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• pp.91-96
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• 1975

In this paper, with a view to study the impurity effect, Ge-Si-Te memory devices are investigated experimentally about the dependence of temperature and frequency. Conductivity depends upon temperature and frequency and it is some-what influenced by heat treatment. With increasing frequency, conductivity has a tendency to be independent of temperature. We found that switching time and threshold voltage are reduced by it.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 춘계학술대회
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• pp.18-21
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• 1991

In this paper, the effect of background grey levels on the visual perception of target image displayed on CRT monitor has been investigated. The purpose of this study is to investigate the efficacy of CRT monitor as a display medium of image information especially in medical imaging field. Three sets of experiments have been performed in this study; the first was to measure the luminance response of CRT monitor and to find the best fitting equation, and the second was the psychophysical experiment measuring the threshold grey level difference between the target image and the background required for visual discrimination for various background grey levels, and the third was to develop a visual model that is predictable of the threshold grey level difference measured in the psychophysical experiment. The result of psycophysical experiment shows that the visual perception performance is significantly degraded in the range of grey levels lower than 50, which is turned out due to the low luminance change of CRT monitor in this range while human eye has been adapted to relatively bright ambient illumination.

• 대한간호학회지
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• 제43권3호
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• pp.361-369
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• 2013

Purpose: The purpose of this study was to examine the effect of anorexia and neuropathic pain induced by cisplatin on hindlimb muscles of rats. Methods: Adult male Sprague-Dawley rats were divided into two groups, a cisplatin-treated group (n=10) and a control group (n=10). In the cisplatin-treated group, cisplatin at a dose of 2 mg/kg was injected intraperitoneally two times a week up to a cumulative dose of 20 mg/kg over 5 weeks, and in the control group saline (0.9% NaCl) was injected intraperitoneally at the same dose and duration as the cisplatin-treated group. At 34 days all rats were anesthetized, after which the soleus and plantaris muscles were dissected. Withdrawal threshold, body weight, food intake, activity, muscle weight, Type I and II fiber cross-sectional areas and myofibrillar protein content of the dissected muscles were determined. Results: Compared with the control group, the cisplatin-treated group showed significant decreases (p<.05) in withdrawal threshold, activity, food intake, body weight, Type I and II fiber cross-sectional areas, myofibrillar protein content and weight of the soleus and plantaris muscles. Conclusion: Muscular atrophy in hindlimb occurs due to anorexia and neuropathic pain induced by the cisplatin treatment.