• 한국안전학회지
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• 제15권4호
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• pp.88-94
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• 2000

The adsorption characteristics of Tharonil on granular activated carbon were experimentally investigated in an adsorber and in a packed column. It was estabilished that the adsorption equilibrium of Tharonil on granular activated carbon was more successfully fitted by Freundlich isotherm equation than Langmuir isotherm equation in the concentration range from 1 to 1000 mg/1. Intraparticle diffusivities (pore and surface diffusivity) of Tharonil were estimated by the concentration-time curve and adsorption isotherm. The estimated values of pore diffusivity and surface diffusivity are $6.70{\times}10^{-6}$ and $2.0{\times}10^{-9}cm^2/s$, respectively. From comparison of intraparticle diffusivities, it was found that surface diffusion was the limiting step for adsorption rate. The break time and breakthrough curve predicted by constant pattern-linear driving force model were shown to agree with the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.303-307
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• 1995

The pulse width modulated inverters based on fully digitalized method are becoming an industrial standard. This paper describes a real time generation of fully digitalized PWM pulses and its realization by single chip microprocessor. To verify the effectiveness of the proposed technique, the algorithm is implemented by using single chip microprocessor, 8097BH. The proposed method is compared with the well known triangular comparison method through experimental results, and the speed control of a motor is experimentally done by voltage-to-frequency constant control based on the proposed PWM generation method.

• Communications for Statistical Applications and Methods
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• 제31권1호
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• pp.87-104
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• 2024

Most functional magnetic resonance imaging (fMRI) studies in resting state have assumed that the functional connectivity (FC) between time series from distinct brain regions is constant. However, increased interest has recently been in quantifying possible dynamic changes in FC during fMRI experiments. FC study may provide insight into the fundamental workings of brain networks to brain activity. In this work, we focus on the specific problem of estimating the dynamic behavior of pairwise correlations between time courses extracted from two different brain regions. We compare the sliding-window techniques such as moving average (MA) and exponentially weighted moving average (EWMA), dynamic causality with vector autoregressive (VAR) model, dynamic conditional correlation (DCC) based on volatility, and the proposed alternative methods to use differencing and recursive residuals. We investigate the properties of those techniques in a series of simulation studies. We also provide an application with major depressive disorder (MDD) patient fMRI data to demonstrate studying dynamic correlations.

• 혜화의학회지
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• 제4권1호
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• pp.357-371
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• 1995

We have completed a study to measure the contents of glucose, BUN, creatinine. LDH, and T-protein with respect to a fatigued condition in the bloods of rats which a constant swimming is loaded and to measure the maximun swimming time of mice The test has been carried out as a part of the basic study on the efficacy of B. E. P. (Biological Energy Projector) for emitting a light energy having a specific wavelength out of far-infrared rays. As a result. We have reached the following conclusions: 1. At testing of mice's maximun swimming time, all of B.E.P.(2. 4. 8. 24hrs) treated group have been increased in comparison with the control group, but only 24hrs-B.E.P. treated group significantly increased during 4 weeks. 2. The contents of glucose, BUN. creatinine, LDH, and T-protein measured immediately after the swimming of mice have been distinctly changed but not been significantly changed at their increase and decrease in comparison with the control group. 3. At 3rd day out of the swimming loading, the contents of glucose in the blood serum of the white rat have been distinctly increased in comparison with the control group. And 24hrs-B.E.P treated group surpassed 8hrs-B.E.P. treated group. 4. At 1st and 3rd day, the contents of creatinine in the blood serum of the white rat have been distinctly increased at B.E.P. (8, 24hrs) treated groups in comparison with the control group and have been recovered to the condition of the normal group. 5. After three days, the contents of BUN in the blood serum of the white rat have been significantly decreased in B.E.P.(8, 24hrs) treated groups at 3rd day in comparison with the control group and have been recovered to the condition of the normal group. 6. The contents of LDH in the blood serum of the white rat have been decreased in B.E.P.(8, 24hrs) treated groups at 3rd day in comparison with the control group, in particular 24hrs-B.E.P. treated group has been decreased distinctly than the normal group. 7. The contents of T-protein in the blood serum of the white rat have been distinctly increased in B.E.P. (8, 24hrs) treated groups at 3rd day in comparison with the control and normal group. As the above results, it has been proved that the execise of mice and the fatigue metabolism of rats were influenced by the light energy emitted the B.E.P., and it has been also proved that the external stimulation could be used as a preferable stimulative factor for the biological metabolism. If the clinical training and study are positively achieved, the B.E.P. would be used as curative means and preventive measures for helping human body.

• Industrial Engineering and Management Systems
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• 제12권3호
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• pp.244-253
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• 2013

In industries, shipping is an important issue in improving the forecasting accuracy of sales. This paper introduces a hybrid method and plural methods are compared. Focusing the equation of exponential smoothing method (ESM) that is equivalent to (1, 1) order autoregressive-moving-average (ARMA) model equation, a new method of estimating the smoothing constant in ESM had been proposed previously by us which satisfies minimum variance of forecasting error. Generally, the smoothing constant is selected arbitrarily. However, this paper utilizes the above stated theoretical solution. Firstly, we make estimation of ARMA model parameter and then estimate the smoothing constant. Thus, theoretical solution is derived in a simple way and it may be utilized in various fields. Furthermore, combining the trend removing method with this method, we aim to improve forecasting accuracy. This method is executed in the following method. Trend removing by the combination of linear and 2nd order nonlinear function and 3rd order nonlinear function is executed to the original production data of two kinds of bread. Genetic algorithm is utilized to search the optimal weight for the weighting parameters of linear and nonlinear function. For comparison, the monthly trend is removed after that. Theoretical solution of smoothing constant of ESM is calculated for both of the monthly trend removing data and the non-monthly trend removing data. Then forecasting is executed on these data. The new method shows that it is useful for the time series that has various trend characteristics and has rather strong seasonal trend. The effectiveness of this method should be examined in various cases.

• 한국해안·해양공학회논문집
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• 제28권1호
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• pp.27-33
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• 2016

불규칙 파랑 중에서 직접 예인하는 케이슨의 상판침수에 대한 수치해석을 수행하였다. 패널법을 이용하여 주파수 영역에서의 선형 운동해석을 수행하였고, 통계적 방법을 통해 상판침수를 예측하였다. 시간영역 해석에서는 예인시스템, 환경하중 등을 상세히 구현하여 운동해석을 수행하였고, 상판침수 결과를 주파수 영역에서의 결과와 비교하였다. 또한, 시간 영역 해석에서는 예인선의 수 및 배치에 대한 검토를 수행하여 상판침수 측면에서 예인시스템이 미치는 영향과 운송조건을 고찰하였다.

• 대한치과보철학회지
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• 제43권6호
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• pp.717-726
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• 2005

Statement of problem. One of the common problems of provisional crown and fixed partial denture materials is that when they are subjected to constant loads for a long period of time, they exhibit a dimensional change (creep). Purpose. The aim of this study was to investigate the viscoelastic behaviour of polymer-based provisional crown and fixed partial denture materials with time at constant compressive load. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Temphase, Luxatemp) and one monomethacrylate-based material (Trim) were selected. Dimensional changes of the specimens were recorded by a LVDT to evaluate their viscoelastic behavior and creep strain. For all specimens, two loading procedures were used. At first, static compressive stress of 4 MPa was applied for 30 minutes and followed by 1 hour of strain recovery. Then, after 24 hours of water storage, the specimens were loaded again. The creep values between materials were statistically analyzed using one-way ANOVA and multiple comparison $Scheff\acute{e}$ test. Independent samples t-test was also used to identify the difference of creep strain between first and secondary loading conditions at the significance level of 0.05. Results. Following application of the first loading, Trim showed the highest maximum creep strain (32.7%) followed by Luxatemp, Protemp 3 Garant and Temphase, with values of 3.78%, 2.86% and 1.77%, respectively. Trim was significantly different from other materials (P<0.05), while there were no significant differences among Luxatemp, Protemp 3 Garant and Temphase (P>0.05). The highest recovery and permanent set of Trim, were significantly different from those of others (P<0.05). At the secondary loading of the dimethacrylate-based materials, creep deformation, recovery and permanent set decreased and the percentage of recovery increased, while in Trim, all values of the measurements increased. This result showed that the secondary loading at 24 hours produced a significant creep magnitude. Conclusion. The dimethacrylate-based provisional crown and fixed partial denture materials showed significantly higher creep resistance and lower deformation than the monomethacrylate-based material. Thus, monomethacrylate-based materials should not be used in long-term stress-bearing situations.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.896-905
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• 1993

Thin-layers of wheat and barley are dried at near-ambient temperatures(3.5$^{\circ}C$ -5$0^{\circ}C$) in order to obtain the intrinsic drying data. The well established apparatus was modified to enable it to record all the sample weight data in still air by using a purpose -built automatically controlled sliding valve. The air could be diverted in less than 0.5seconds and a 7 second period was required to attain a steady weight reading. With this apparatus, very smooth drying curves were obtained. The data of sample weight , drying temperature and dew point temperature wee recorded continuously . The drying process was terminated when the moisture content change in 24 hours was less than 0.004 d.b. This was achieved by drying a sample for about a week . The final points were recorded as the dynamic equilibrium moisture content(EMC). The drying data were than fitted to the exponential Newton model and the dynamic EMC data were fitted to the Modified-Chung-Pfost Model . All the fitted parameters are given and comparison is made with previous published data. The comparisons who that the current drying constants are lower than the previous data, the dynamic EMC data obtained for wheat and barely agree with the previous data. The results show that to obtain the drying constant in the exponential Newton model, adequate drying time is necessary.

• 물과 미래
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• 제10권1호
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• pp.20-24
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• 1977

43,000 shallow water wells have been installed as a part of all weather irrigation water supply project executed during 1969 to 1970 in all over Korea penninsula in order to solve water shortage problem of farming land by developing shallow ground water reserved in unconsolidated materials. But after 3 years later it was reported that 34% of the wells were abandoned by the reasons of artificial and natural defects. 48 wells distributed uniformly in the penninsula are selected to determine their well loss constants, relation between well loss and specific capacity, and tophographic classification of the well loss on the shallow water well. The results show that average well loss consatnt and the value of $CQ^2/S_w$ is ranged from $5.95{\times}10^{-5}\;to\;3.65{\times}10^{-8}Day^2M^{-5}$ and from 35.5% to maximum 68.48% respectvely and that relation between specific capacity and well loss constant can be approximately formulated as $C=0.61S_p2.246$ However this result indicates that most wells installed in this time have too high value of well loss constant $CQ^2/S_w$ in comparison with properly deseigned well. The most favorable and producable water bearing formation among unconsolidated deposits such as sand & gravel, boulderly gravel, clayey boulderly gravel, and sand formation in Korea is sand formation deposited in center of valley.

• 한국지반공학회지:지반
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• 제9권2호
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• pp.27-40
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• 1993

한 개의 공시체에 대해 일정한 크기의 높은 구속압력을 가하고, 단계별로 압밀배수시간을 조정하여 압밀비배수 삼축압축시헙을 할 수 있는 방법을 이 논문에서 제안하였다. 이 방법으로 시험하면 하나의 공시체로 여러 단계의 시험을 하여 강도정수를 구할 수 있음은 물론 시험시간이 종전의 다단계시험에 비해 현저히 절약된다. 이 시험에 대한 적합성을 증명하기 위하여 불교란 시료와 재성형시료에 대해 표준압축시험과 재래의 다단계시험을 수행하고 그 결과를 비교하였다. 여기서 제안하는 시험방법으로 결정된 강도정수는 다른 시험방법으로 얻은 강도정수와 잘 일치하였으며, 이 방법이 대단히 효과적이고 실용적이라는 것을 입증하였다.