• 대한수학교육학회지:수학교육학연구
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• 제24권3호
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• pp.375-385
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• 2014

이 연구는 학교수학의 모평균과 모비율의 신뢰구간의 추정을 비교하면서 두 추정간에 일관성이 확보되고 있는지에 대해 고찰하였다. 이 결과를 토대로, 이 연구에서는 표본평균과 표본비율을 동일한 방식으로 취급하는 것, 모평균과 모비율의 신뢰구간의 예를 구성할 때 모표준편차 대신에 표본표준편차의 관측값을 대입하는 절차를 동일하게 적용하는 것, 표본비율 $\hat{P}$와 그에 대한 관측값 $\hat{p}$을 구별하는 것과 같은 일관성 확보 방안을 제안하였다.

• 한국유체기계학회 논문집
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• 제14권3호
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• pp.50-58
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• 2011

To utilize wind resources effectively around buildings in urban area, the magnitudes of wind velocity and turbulence intensity are important, which means the need of the information about the relationship between the magnitude of wind velocity and that of fluctuating wind velocity. In the paper, wind-tunnel experiments were performed to provide the information about Characteristic of Wind flow around buildings with the spanwise distance and the side ratio of buildings as variables. For a single building with the side ratios of one and two, the average velocity ratio was 1.4 and the velocity standard deviation ratio ranged from 1.4 to 2.6 at the height of 0.02m at the corner of the windward side, in which flow separation occurred. For twin buildings with the side ratios of one and two, the velocity ratio ranged from 2 to 2.5 as the spanwise distance varied at the height of 0.02m, and the velocity standard deviation ratio varied near 1.25. For twin buildings with the side ratios of one and two, the maximum velocity ratio was 1.75 at the height of 0.6m, and the maximum velocity standard deviation ratio was 2.1. It was also found from the results of CFD analysis and wind-tunnel experiments that for twin buildings with the side ratios of one and two, the difference between the velocity ratio of CFD analysis and that of wind-tunnel experiments at streamwise distances was near 0.75.

• 대한방사선기술학회지:방사선기술과학
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• 제41권6호
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• pp.603-610
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• 2018

This study examined the following: accuracy of the exposure conditions in the inverter device and three-phase device; output waveform over the exposure conditions; and average and standard deviation of the output waveform. After assessing whether the dose corresponding to the theoretical dose was presented, the following conclusions were obtained: 1. The accuracy of the tube voltage(kVp) and tube current(mA) exposure time(sec) was within the tolerable level prescribed in Korea's Safety Management Standards. In the error, Inverter device was large the tube voltage and exposure time, the three-phase device was large the tube current. 2. In terms of the output waveform of the exposure conditions and the average and standard deviation of the output waveform, the higher tube voltage and larger tube current resulted in greater standard deviation in pulsation. Moreover, the standard deviation of pulsation was shown to be greater in the inverter device than the three-phase device; there was also greater standard deviation in the inverter device considering the exposure time. 3. Regarding the exposure conditions over the output dose, all linearity showed the coefficient of variation which had an allowable limit of error within 0.05. Although the output dose ratio for the inverter device was 1.00~1.10 times no difference that of the three-phase device, there was almost no difference in dose ratio between the tube currents.

• Physical Therapy Rehabilitation Science
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• 제12권2호
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• pp.201-205
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• 2023

Objective: Resistance exercise is a necessary element to improve quality of life, and measurement and evaluation of muscle strength provide important information for prescription and management of rehabilitation and exercise programs. This study analyzed the correlation between direct and indirect 1RM for isokinetic maximum torque of the knee joint in order to provide useful information in the field of exercise programs. In addition, the flexion-extension ratio and the difference in left-right deviation were verified. Design: A cross-sectional study Methods: The subjects of this study were 33 healthy adult men and women without medical problems who participated in the health exercise class program at S University in Seoul. The correlation between isokinetic maximum torque and direct and indirect 1RM was analyzed, and a dependent t-test was performed to analyze the flexion-extension ratio and left-right deviation. Results: There was a high correlation between the isokinetic maximum torque and direct and indirect 1RM, and no statistically significant difference was shown between the test methods in the analysis of the flexion-extension ratio and left-right deviation. Conclusions: Isokinetic muscle function measuring equipment is expensive, so it is difficult to use it in local exercise rehabilitation and training sites. Through this study, it was found that direct and indirect 1RM isokinetic maximum torque showed a high correlation, and there was no difference in evaluating muscle function such as flexion-extension ratio and left-right deviation. Therefore, it is considered that the muscle function evaluation using 1RM in general field can be usefully utilized.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.252-252
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• 2011

Rainfall-runoff models are calibrated and validated by using a same data set such as observations. The past climate change effects the present rainfall pattern and also will effect on the future. To predict rainfall-runoff more preciously we have to consider the climate change pattern in the past, present and the future time. Thus, in this study, the climate change represents changes in mean precipitation and standard deviation in different patterns. In some river basins, there is no enough length of data for the analysis. Therefore, we have to generate the synthetic data using proper distribution for calculation of precipitation based on the observed data. In this study, Kajiyama model is used to analyze the runoff in the dry and the wet period, separately. Mean and standard deviation are used for generating precipitation from the gamma distribution. Twenty hypothetical scenarios are considered to show the climate change conditions. The mean precipitation are changed by -20%, -10%, 0%, +10% and +20% for the data generation with keeping the standard deviation constant in the wet and the dry period respectively. Similarly, the standard deviations of precipitation are changed by -20%, -10%, 0%, +10% and +20% keeping the mean value of precipitation constant for the wet and the dry period sequentially. In the wet period, when the standard deviation value varies then the mean NSE ratio is more fluctuate rather than the dry period. On the other hand, the mean NSE ratio in some extent is more fluctuate in the wet period and sometimes in the dry period, if the mean value of precipitation varies while keeping the standard deviation constant.

• 대한물리의학회지
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• 제10권1호
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• pp.37-43
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• 2015

PURPOSE: The purpose of this study is to investigate the effect of the physical therapy treatment room environment using microwave diathermy on the autonomic nervous system of human body. METHODS: Participants were 24 healthy adults. Standard deviation of all normal R-R intervals(SDNN), root mean square of successive differences(RMSSD), low frequency(LF), high frequency(HF), LF/HF ratio were compared in microwave irradiation and non-irradiation group. Data were analyzed in Wilcoxon's signed-ranks test and Mann-Whitney U test. RESULTS: Standard deviation of all normal R-R intervals (SDNN), root mean square of successive differences (RMSSD), low frequency(LF), high frequency(HF), LF/HF ratio were not significantly different in microwave irradiation group. Standard deviation of all normal R-R intervals(SDNN), root mean square of successive differences (RMSSD), low frequency(LF), high frequency(HF), LF/HF ratio were not significantly different in microwave non-irradiation group. Standard deviation of all normal R-R intervals(SDNN), root mean square of successive differences (RMSSD), low frequency(LF), high frequency(HF), LF/HF ratio were not significantly different between two groups. CONCLUSION: There was no significant change in the sympathetic nervous system and parasympathetic nervous system regardless of the presence of microwave irradiation. There was no significant change in the autonomic nervous system adaptability regardless of the presence of microwave irradiation.According to this study, microwave diathermy does not have significant effect on the autonomic nervous system.Future study is necessary to investigate the long term effect of the physical therapy treatment room environment using microwave diathermy on the autonomic nervous system of the human body.

• Journal of Welding and Joining
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• 제19권5호
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• pp.486-491
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• 2001

The effect of S content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80%Ar-$20%CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with S content of wire. Sulfur addition in wire reduced surface tension of droplet and weld pool, and made arc more stable in MAG welding. With increasing S content, the spattering ratio and the ratio of large size spatter ($d{\geq}1.0mm$) were reduced in short circuit transfer mode. In spray transfer mode, spattering ratio, however was increased when sulfur was added more than 0.020wt.% because surface tension of droplets and weld pool was reduced too much even though arc stability was improved.

• Restorative Dentistry and Endodontics
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• 제31권1호
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• pp.50-57
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• 2006

이 연구의 목적은 $ProTaper^{(R)}$ system을 사용하였을 때, 각 단계별로 근관 형성 결과를 분석 하는 것이다. 20개의 레진 블락을 근관 성형 방법에 따라, 엔진 구동형 $ProTaper^{(R)}$로 전체 근관을 성형한 군을 R군, 수동형 $ProTaper^{(R)}$로 전체 근관을 성형한 군을 M군으로 하였다. 근관의 술 전, 술 후 이미지를 각 파일 단계별로 스캔한 후, 중심이동률 산출을 위해 원래의 근관 이미지와 각 단계의 파일 사용후의 이미지를 각각 중첩하였고, 근관의 변위량 산출을 위해 각 단계의 파일 사용후의 이미지와 직전 파일 사용후의 이미지를 중첩하였다. 근단공으로부터의 수직거리 1 2, 3, 4그리고 5mm위치에서 중심이동률과 근관의 변위량을 측정하였다. 실험 결과 R군의 모든지점에서 각 단계별 중심이동률과 근관 변위량은 각각 유의한 차이가 없었다 (p<0.05). M군에서 1 mm를 제외한 모든 지점에서 각 단계별 중심 이동률과 근관 변위 량은 각각 유의한 차이가 없었다 (p<0.05). 그러나 M군의 1mm 지점에서 F2 file step은 통계학적으로 큰 중심 이동률과 근관 변위량을 보였다 (p<0.05). 본 연구의 결과에서 엔진 구동형 $ProTaper^{(R)}$ 사용 시에는 각 파일 단계별 근관 변위 정도에 유의한 차이가 없었으나, 수동형 ProTaper로 근관 성형을 하였을 때 , F2 file step에서 특히 근관 변위가 크게 나타났다.

• 천문학회보
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• 제37권2호
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• pp.108.2-108.2
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• 2012

Recent results from microlensing surveys show that a free-floating planet or a wide-separation planet is more numerous than a main-sequence star in the Galaxy. Moreover, the detection efficiency of the planets will be improved in next-generation experiments with a high survey monitoring frequency. However, microlensing events produced by both planets appear similar light curves with a short duration timescale, thus it is difficult to distinguish them. In this paper, we investigated the detectable separation range of a wide-separation planet as the planet bound to its host star. We construct the fractional deviation maps using the magnifications of the planetary lensing and the single-lensing by planet itself for various parameters such as a mass ratio, separation, and source radius. As a result, we found that the pattern of the fractional deviation is related to the ratio of source radius to caustic size, and the ratio satisfying the detection criterion (i.e., ${\geq}5%$ in the fractional deviation) varies with a separation. Hence, we derived a fitting formula as the function of a mass ratio and a source radius to reflect the variation in the calculations of the detectable separation range of a wide-separation planet as the planet bound to its host star. In addition, we estimated the condition that a wide-separation planet can be detected as a single-lensing event under the finite source effect. We found that such a case is possible provided that the source radius is smaller than ~2.5 times of Einstein ring radius of a planet, regardless of a separation or a mass ratio.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.818-827
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• 2008

In this paper, we propose a new noise estimation and reduction algorithm for stationary and nonstationary noisy environments. This approach uses an algorithm that classifies the speech and noise signal contributions in time-frequency bins. It relies on the ratio of the normalized standard deviation of the noisy power spectrum in time-frequency bins to its average. If the ratio is greater than an adaptive estimator, speech is considered to be present. The propose method uses an auto control parameter for an adaptive estimator to work well in highly nonstationary noisy environments. The auto control parameter is controlled by a linear function using a posteriori signal to noise ratio(SNR) according to the increase or the decrease of the noise level. The estimated clean speech power spectrum is obtained by a modified gain function and the updated noisy power spectrum of the time-frequency bin. This new algorithm has the advantages of much more simplicity and light computational load for estimating the stationary and nonstationary noise environments. The proposed algorithm is superior to conventional methods. To evaluate the algorithm's performance, we test it using the NOIZEUS database, and use the segment signal-to-noise ratio(SNR) and ITU-T P.835 as evaluation criteria.