• Composites Research
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• 제12권5호
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• pp.40-53
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• 1999

저속시험 및 약 11.4m/s까지의 고속시험을 받는 다방향 탄소섬유/에폭시 복합적층판의 층간파괴거동에 대해 양외팔보(DCB)시험편을 이용하여 연구했다. 모드I의 하중을 1.0m/s이상으로 가한 결과 하중-시간곡선에 동적효과가 발생하여, 시험속도에 비례하는 단순관게식으로 예상되는 것보다 더 큰 균열속도가 나타났다. 시험편 개구변위와 균열길이만을 사용하는 수정된 선형보해석식은 동적인 층간파괴에너지$G_{IC}$를 평가하기 위해 유효했다. 또한 굽힘탕선계수의 실측값은 시험속도의 증가에 다라 증가했는데, 이를 $G_{IC}$의 평가시에 고려했다. 시험속도가 1.0m/s까지 증가할 때, 균열개시 및 정지시의 $G_{IC}$값은 변화가 없었으나, 11.4m/s의 속도에서 최대 GIC값은 섬유가교효과의 증대로 크게 증가했다. 또한 초기균열길이가 길수록 고속시의 최대GIC값은 저하했다.

• 대한수의학회지
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• 제32권4호
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• pp.677-681
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• 1992

This experiment was carried out to establish a proper method of indocyanine green(ICG) excrection test for a applicable liver function test in three Korean native cattle average weighing about 450kg and dairy cattle parity of 3~5. The results obtained the half life($T^1/_2$), fractional clearance rate(KICG), retention rate and plasma enzyme activities before or after injection of ICG were as follows. 1. The maximum absorbance of ICG in plasma was at 805nm. 2. Average half life and fractional clearance rate following the injection of ICG 0.25mg/kg body weight were $5.53{\pm}1.27$ minute and $0.131{\pm}0.031$/minute in Korean native cattle, $4.55{\pm}0.68$ minute and $0.156{\pm}0.031$/minute in dairy cattle, respectively. The ICG removal rate was exponentially liner for the first 15 minutes after injection both of Korean native cattle and dairy cattle. 3. Average plasma retention rate when 10, 15, 30 minutes after injection was $35.7{\pm}13.9$, $23.2{\pm}7.1$, $10.8{\pm}3.5%$ in Korean native cattle, $26.8{\pm}3.3$, $14.2{\pm}1.2$, $5.5{\pm}2.2%$ in dairy cattle, respectively. 4. Plasma enzyme activities(AST, ALT, r-GTP) were no variation among the before, during and after injection of ICG. From these results, ICG excretion test to cattle is applicable to evaluation of liver funtion in both clinical and research, and adopted the 15 minutes plasma sample as the sample taken at the ideal time for comparative purposes.

• 한국농공학회지
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• 제18권4호
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• pp.4209-4217
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• 1976

The purpose of this thesis is to search for the determination method of pumping rates in the existing tube wells for irrigation. Pumping tests were carried out for the twelve test tube wells which were selected in the provinces of Kyounggi, Kangwon, Chungbuk and Chungnam. The depths, static water levels, pumping levels, drawdowns and yields of tube wells were measured in the pumping tests, and a centrifugal pump with 3 inches diameter, a 5 HP motor and a 90$^{\circ}$ V-notch were used in the pumping tests. The average coefficient of transmissibility calculated by Chow's and Jacob's methods is 0.0336 square meter per second, and the average pumping rate calculated by Thiem's, Smreker's, Brinkhaus' and Theis' formulae, is 919 cubic meter per day, Therefore, the ground water storage in the test areas is comparatively abundant. Correlation between pumping rates and depths of tube wells is not in existence. Also, correlation between pumping rates and the thickness of aquifer is not found in this experiment. This shows that the depths of some tube wells are deep and their thicknesses of aquifer are thick, but their ground water storages are poor, and that the depths of some tube wells are shallow and their thicknesses of aquifer are thin, but their ground water storages are abundant. It seems that the test tube wells are influenced by the peculiar characteristics that the ground water in the test areas is free ground water in alluvium layer closely related with surface water. As drawdown increases, pumping rate decreases, and as the coefficient of transmissibility increases, pumping rate also increases. Namely, there are negative correlation between pumping rate and drawdown, and positive correlation between pumping rate and the coefficient of transmissibility. Judging from the results of the pumping tests in these tests areas, the pumping rate calculated by the formula, {{{{ { Q}_{m } =Q { ( { { S}_{ m} } over { TRIANGLE S } )}^{ { 2} over {3 } } }}}} used traditionally, is likely to be higher than real pumping rates. The formula, {{{{ { Q}_{m } =Q { { H}^{ 2} } over { (2H- TRIANGLE S) TRIANGLE S} }}}} derived from Thiem's theory, is looked upon as the reasonable one to detemine pumping rates in the existing tube wells for irrigation.

• 말소리와 음성과학
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• 제8권2호
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• pp.41-48
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• 2016

The purpose of this study is to evaluate the association among articulation rate, speech intelligibility and working memory in children with dysarthria. Two subject groups of 11 spastic and 11 flaccid dysarthria, respectively, aged between 8 and 17 years of age participated in this study. All participants were administered the following tests: K-WISC III PIQ test, speech intelligibility, working memory and articulation rate. Group differences were compared by an independent t-test. Pearson correlation were computed between all measures. The results of this study are as follows: First, articulation rate and intelligibility were significantly lower for the spastic dysarthria than for the flaccid dysarthria. Second, there was a significant correlation between articulation rate and intelligibility in children with flaccid dysarthria. Lastly, there was no significant correlation between articulation rate and working memory in both groups. The results suggest that articulation rate is not necessarily accompanied by working memory capacity in children with dysarthria, and there are differences in the effect of articulation rate on intelligibility depending on the type of dysarthria.

• 소성∙가공
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• 제15권2호
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• pp.132-137
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• 2006

This paper is concerned with the thermo-mechanical behavior including temperature dependent strain-rate sensitivity of steel sheet for an auto-body. In order to identify the temperature dependent strain-rate sensitivity of SPRC35R and SPRC45E, uniaxial tension tests are performed with the variation of the strain-rates from 0.001 /sec to 200 /sec at environmental temperatures varied from $-40^{\circ}C\;to\;200^{\circ}C$. The thermo-mechanical response at the quasi-static state is obtained with the static tensile test and at the intermediate strain-rate is from the high speed tensile test. Experimental results show that the strain-rate sensitivity increases at low temperature. It represents that as the strain-rate increases, the variation of flow stress becomes sensitive on the temperature. The results indicate that the flow stress of SPRC35R is more dependent on the changes of strain-rate and temperature than those of SPRC45E.

• 펄프종이기술
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• 제41권1호
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• pp.44-51
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• 2009

Proper test methods and instruments for evaluating score or creasing crack have not been provided, although score crack trouble occurs frequently in manufacturing corrugated containers. Because existing creasability tester has the limitation of the available thickness of test piece and folding rate, it cannot be used for corrugated fiberboards with high thickness. In this study, we developed the laboratory test instrument and the method to determine the score or creasing crack of corrugated fiberboard. This instrument can evaluate folding resistance of corrugated board without restriction on the folding rate and thickness of specimen. Corrugated fiberboard had the different folding behavior from linerboard when it was creased. By using this test machine, score crack can be objectively determined by folding test piece to the certain folding angle with constant folding rate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.447-452
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• 2004

Vacuum interrupters in order to be used in various switch-gear components such as circuit breakers, distribution switches, contactors, etc. spread the arc uniformly over the surface of the contacts. The electrodes of vacuum interrupters are made of sinter-forged Cu-Cr materials for good electrical and mechanical characteristics. Since the closing velocity is 1-2m/s and impact deformation of the electrode depends on the strain rate at that velocity, the dynamic behavior of the sinter-forged Cu-Cr is a key to investigate the impact characteristics of the electrodes. The dynamic response of the material at intermediate strain rate is obtained from the high speed tensile test machine test and at the high strain rate is obtained from the split Hopkinson pressure bar test. Experimental results from both quasi-static and dynamic compressive tests are interpolated to construct the Johnson-Cook model as the constitutive relation that should be applied to simulation of the dynamic behavior of the electrodes. The impact characteristics of a vacuum interrupter are investigated with computer simulations by changing the amount of chromium content.

• 품질경영학회지
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• 제17권2호
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• pp.17-26
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• 1989

This paper is concerned with forecasting the existing number of errors in the computer software and optimizing the stopping time of the software test based upon the forecasted number of errors. The most commonly used models have assessed software reliability under the assumption that the software failure late is proportional to the current fault content of the software but invariant to time since software faults are independents of others and equally likely to cause a failure during testing. In practice, it has been observed that in many situations, the failure rate decrease. Hence, this paper proposes a mathematical model to describe testing situations where the failure rate of software limearly decreases proportional to testing time. The least square method is used to estimate parameters of the mathematical model. A cost model to optimize the software testing time is also proposed. In this cost mode two cost factors are considered. The first cost is to test execution cost directly proportional to test time and the second cost is the failure cost incurred after delivery of the software to user. The failure cost is assumed to be proportional to the number of errors remained in the software at the test stopping time. The optimal stopping time is determined to minimize the total cost, which is the sum of test execution cast and the failure cost. A numerical example is solved to illustrate the proposed procedure.

• The Journal of Asian Finance, Economics and Business
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• 제5권3호
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• pp.7-17
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• 2018

This paper examines short-run and long-run dynamic relationships between selected macroeconomic variables and stock prices in the Korea Stock Exchange. The data is restricted to the period for which monthly data are available from January 1986 to October 2016 (370 observations) retrieved from the Economic Statistics System database sponsored by the Bank of Korea. The study employs unit root test, cointegration test, vector error correction estimates, impulse response test, and structural break test. The results of the Johansen cointegration test indicate at least three cointegrating equations exist at the 0.05 level in the model, confirming that there is a long-run equilibrium relationship between stock prices and macroeconomic variables in Korea. The results of vector error correction model (VECM) estimates indicate that money supply and short-term interest rate are not related to stock prices in the short-run. However, exchange rate is positively related to stock prices while the industrial production index and inflation are negatively related to stock prices in the short-run. Furthermore, the VECM estimates indicate that the external shock, such as regional and global financial crisis shocks, neither affects changes in the endogenous variables nor causes instability in the cointegrating vector. This study finds that the endogenous variables are determined by their own dynamics in the model.

• 대한의생명과학회지
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• 제23권3호
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• pp.215-222
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• 2017

Obesity has been directly associated with the development of hypertension and cardiovascular disease. The purpose of this study was to investigate the blood pressure response during graded exercise test in obese adults. 189 subjects (age: $47.96{\pm}10.23$) were assigned to two groups: non-obese group (N=105, BMI: $22.05{\pm}1.57$, waist circumference: $76.90{\pm}6.17$) and obese group (N=84, BMI: $26.96{\pm}2.51$, waist circumference: $88.29{\pm}6.41$). The subjects underwent health screening and exercise treadmill test from January 2012 to December 2014. Graded exercise test was performed according to the Bruce protocol. Exercise duration (P=0.046) and METs (P=0.015) were significantly lower in obese group than non-obese group. There was no difference in the rate of change in blood pressure response between obese group and non-obese group during exercise, and the recovery rate of systolic blood pressure was delayed in the obese group compared to non-obese group in the first recovery period (P=0.020). The significant factors of increasing rate of change in maximum systolic blood pressure was waist (P=0.046) and hip circumference (P=0.008). In conclusion, these results demonstrate that, for hypertension prevention in obese adults, waist and hip circumference levels should be managed within normal range.