• Smart Structures and Systems
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• 제18권6호
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• pp.1203-1215
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• 2016

When strain sensing cables are under long-term stress and cyclic loading, creep may occur in the jacket material and each layer of the cable structure may slide relative to other layers, causing fatigue in the cables. This study proposes a device for testing the fatigue characteristics of three types of cables operating under different conditions to establish a decay model for observing the patterns of strain decay. The fatigue characteristics of cables encased in polyurethane (PU), GFRP-reinforced, and wire rope-reinforced jackets were compared. The findings are outlined as follows. The cable strain decayed exponentially, and the decay process involved quick decay, slow decay, and stabilization stages. Moreover, the strain decay increased with the initial strain and tensile frequency. The shorter the unstrained period was, the more similar the initial strain levels of the strain decay curves were to the stabilized strain levels of the first cyclic elongation. As the unstrained period increased, the initial strain levels of the strain decay curves approached those of the first cyclic elongation. The tested sensing cables differed in the amount and rate of strain decay. The wire rope-reinforced cable exhibited the smallest amount and rate of decay, whereas the GFRP-reinforced cable demonstrated the largest.

• 한국인쇄학회지
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• 제11권1호
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• pp.103-122
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• 1993

A cause and counterplan of the increase in dark decay rate of$\varepsilon$-CuPc/PVCz photoreceptor which is consist of the carrier generation layer (CGL) of$\varepsilon$type copper phthalocyanine ($\varepsilon$-CuPc) thin film by an aqueous coating method and the carrier transport layer (CTL) of polyvinylcarbazol (PVCz) by spin coating, are studied in this paper. Electrochemical deposition of CGL was accompanied by an increase in work function of the aluminium substrate during the processes and the enhanced work function 5.3 eV rose above the ionization potential 5.16 eV of $\varepsilon$-CuPc. This resulted in the increased injection of holes from substrate into CGL and a fast dark decay rate. Improved photoreceptor, an electron-transport $\varepsilon$-CuPc/TNF photoreceptor, led to lowing of dark decay rate and increasing of photosensitivity. The carrier generation efficiency (ηg), carrier injection efficiency (ηi) and xerographic gain (G) of the $\varepsilon$-CuPc/TNF photoreceptor were obtained by XTOF method and PIDC.

• 비파괴검사학회지
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• 제36권3호
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• pp.231-235
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• 2016

원자력발전소에서 격납건물 국부누설률시험(LLRT)에 사용되는 누설률 측정 방법에는 유량보충법과 압력감소법이 있으며, 대부분의 발전소에서는 유량보충법을 우선 적용하고 있다. 유량보충법은 누설되는 양만큼 보충되는 유량을 측정하여 누설률을 계산하는 방식이다. 그러나 과도한 누설이 발생하여 시험압력 유지가 어려울 경우 압력감소법이 보완적으로 사용될 수 있다. 압력감소법은 시험압력보다 낮은 압력을 적용하여 누설률을 측정할 수 있기 때문이다. 본 논문에서는 원자력발전소 격납건물 국부누설률시험에서 압력감소법을 이용한 과다누설 측정 방안을 연구하고자 하였다. 이에 따라 현장에서의 누설시험 조건과 유사하게 실험장치를 구성하여 실증실험을 수행하였다. 실험 결과 압력감소법에서의 누설률 변화 특성을 확인하였으며, 여러조건에서 측정된 누설량을 바탕으로 실제 누설률 계산에 필요한 보상비를 산출하였다.

• The Korean Journal of Ecology
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• 제9권4호
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• pp.185-192
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• 1986

The production and decomposition rate of litters from the three different locations, Quercus acutissium forest at 630 m, Q. mongolica forests at 1, 005m and 1, 490 m of Mt. Dokyoo, were estimated by Olson model. The contents of N, P, K, Ca and Na in soils were measured and the relationships among them were elucidated. The amounts of litter production in Q. mangolica were the lowest, 378.96g/$m^2$ at 1, 490 m and the highest, 876.12g/$m^2$ at 1, 005 m. And the amounts of litter production in Q. acutissima at 630 m was 686.16 g/$m^2$. The decay rate of litters in Q. mongolica was the smallest, 0.123 at 1, 490 m, and the largest, 0.222 at 1, 005 m. And that in Q. acutissima was 0.169 at 630 m which was the medium rate. The production and decay rate of litters decreased with the ascending altitude. The values at 630 m were maller than those at 1, 005 m. This might be due to the fact that the tree species at 630 m was Q. acutissima was 0.169 at 630 m which was the medium rate. The production and decay rate of litters decreased with the ascending altitude. The values at 630 m was Q. acutissima which was different from Q. mongolica at 1, 005 m and 1, 490 m. The half-0life of litter decay in Q. monglica was 5, 634 years at 1, 490 m and 3.134 years at 1, 005 m. And that in Q. acutissima was 4.132 years at 630 m. The decay rates of litters were tend to be inversely proportional to the ascending altitude. The annual standing stocks of mineral and their amounts returned to the soil were proportional to the decay rate of organic matters.

• 한국환경과학회지
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• 제17권8호
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• pp.833-840
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• 2008

Deoxygenation process in which CBOD(carbonaceous BOD) is biochemically oxidized to reduced inorganic compounds is of great significance in the oxygen demand of stream waters. The CBOD decay rate has traditionally been determined in a laboratory by CBOD bottle incubation method. But in this study, CBOD decay rates were obtained by laboratory incubation method and natural waters experiment. Average CBOD decay rate for the Nakdong river(upper zone) in natural waters were 0.553 $day^{-1}$ during April 2005 to January 2007. The values in the middle and down parts of the Nakdong river in natural waters were 0.384 $day^{-1}$ and 0.252 $day^{-1}$ at the same period of time, respectively. Average CBOD decay rates using by incubation method in the upper/middle/down parts of the main stream in the Nakdong river basin was 0.270 $day^{-1}$, and 0.289 $day^{-1}$, and 0.283 $day^{-1}$ during April 2005 to January 2007, respectively.

• 농업과학연구
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• 제48권2호
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• pp.241-250
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• 2021

This investigation assessed the berry quality after two months of low-temperature storage (3 ± 1℃) of 'Shine Muscat' grapes, which were treated with CPPU (N-[2-chloro-4-pyridyl]-N'-phenylurea) or TDZ (1-phenyl-3-[1,2,3-thiadiazol-5-yl] urea) in combination with gibbrellic acid (GA₃). The berry shatter rate was the lowest (1%) in 4 cm + CPPU treatment, while it was the highest (2.4%) in 3 cm floral length treated with CPPU. On the other hand, the 4 cm + TDZ treatment resulted in a shatter rate of 2.0%, which was twice as high as that observed after 4 cm + CPPU treatment. The 4 cm + TDZ treatment resulted in a 5.5% berry decay rate, which was the highest among all treatments. Alternatives to using a sulfur dioxide (SD) pad to maintain the quality of 'Shine Muscat' grapes, namely, using ethylene scrubbers (ESs, 3 g × 2 sachet) and alcohol releasers (ARs, 2 g × 2 sachet) in a 2 kg carton package for export, were explored in this study. The berry shatter rate with ES treatment (1.0%) was found to be comparable to that with SD treatment (0.6%) during three months of cold storage. Regarding the berry decay rate, that of the untreated control surged to 36.0% in the three months of storage, followed by 19.9% and 15.5% in samples subjected to AR and ES treatments respectively. Compared with the untreated control, the samples subjected to SD treatment showed a decay rate of 2.2%, which was the most effective in reducing berry decay by 95%. These results demonstrated that SD pad treatment of 'Shine Muscat' grapes was the most effective method of maintaining berry quality, and ES treatment partially reduced the berry shatter and berry decay rates.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.529-536
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• 2016

In this paper we proposed an unsupervised algorithm to estimate the reverberation time (RT) directly from the reverberant speech signal. For estimation process we use maximum likelihood estimation (MLE) which is a very well-known and state of the art method for estimation in the field of signal processing. All existing RT estimation methods are based on the decay rate distribution. The decay rate can be obtained either from the energy envelop decay curve analysis of noise source when it is switch off or from decay curve of impulse response of an enclosure. The analysis of a pre-existing method of reverberation time estimation is the foundation of the proposed method. In one of the state of the art method, the reverberation decay is modeled as a Laplacian distribution. In this paper, the proposed method models the reverberation decay as a Gamma distribution along with the unification of an effective technique for spotting free decay in reverberant speech. Maximum likelihood estimation technique is then used to estimate the RT from the free decays. The method was motivated by our observation that the RT of a reverberant signal when falls in specific range, then the decay rate of the signal follows Gamma distribution. Experiments are carried out on different reverberant speech signal to measure the accuracy of the suggested method. The experimental results reveal that the proposed method performs better and the accuracy is high in comparison to the state of the art method.

• East Asian mathematical journal
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• 제34권1호
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• pp.69-84
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• 2018

In this paper, we study the viscoelastic Kirchhoff type equation with a nonlinear source for each independent kernels h and g with respect to Volterra terms. Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.

• East Asian mathematical journal
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• 제32권3호
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• pp.355-364
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• 2016

In this paper, we study exponential stabilization of the vibrations of the Kelvin-Voigt type wave equation with Balakrishnan-Taylor damping and acoustic boundary in a bounded domain in $R^n$. To stabilize the systems, we incorporate separately, the internal material damping in the model as like Kang [3]. Energy decay rate are obtained by the exponential stability of solutions by using multiplier technique.

• East Asian mathematical journal
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• 제28권3호
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• pp.339-345
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• 2012

In this paper, we study uniform exponential stabilization of the vibrations of the Kirchho type wave equation with acoustic boundary in a bounded domain in $R^n$. To stabilize the system, we incorporate separately, the passive viscous damping in the model as like Gannesh C. Gorain [1]. Energy decay rate is obtained by the exponential stability of solutions by using multiplier technique.