• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제12권2호
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• pp.109-118
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• 2008

We present a new version of the first return time test for pseudorandomness. Let $R_n$ be the first return time of initial n-block with overlapping. An algorithm to calculate the probability distribution of the first return time $R_n$ for each starting block is presented and used to test pseudorandom number generators. The standard Z-test for log $R_n$ is applied to test the pseudorandom number generators.

• Korean Journal of Mathematics
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• 제16권3호
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• pp.301-307
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• 2008

Let $R_n$ be the the first return time to its initial n-word. Then the Ornstein-Weiss first return time theorem implies that log$R_n$ divided by n converges to entropy. We consider the convergence of log$R_n$ for Sturmian sequences which has the lowest complexity. In this case, we normalize the logarithm of the first return time by log n. We show that for any numbers $1{\leq}{\alpha},\;{\beta}{\leq}{\infty}$, there is a Sturmian sequence of which limsup is ${\alpha}$ and liminf is $1/{\beta}$.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권4호
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• pp.120-126
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• 2001

For the past five years, Inha University has been observing the electric fields produced by cloud-to-ground return strokes. This paper presents the summary of most recent results. Statistics on the zero-to-peak rise time, the zero-to-zero crossing time and the amplitude ratio of the second peak in the opposite polarity to the first peak were examined. The radiation electric fields produced by distant cloud-to-ground return strokes were substantially same pattern. The first return stroke field starts with a slowly increasing front and rises abruptly to peak. The rising portions of the electric fields produced by cloud-to-ground return strokes last 1 $mutextrm{s}$ to a few $mutextrm{s}$. The mean values of the zero-to-peak rise times of electric fields were 5.72 $mutextrm{s}$ and 4.12 $mutextrm{s}$ for the positive and the negative cloud-to-ground return strokes, respectively. The mean of the zero-to-zero crossing time for the positive return strokes was 29.48 $mutextrm{s}$ compared with 38.54 $mutextrm{s}$ for the negative return strokes. The depths of the dip after the peak of return stroke electric fields also have the dependence on the polarity of cloud-to-ground return stroke, and the mean values for the positive and negative cloud-to-ground return strokes were 33.55 and 28.19%, respectively.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권6호
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• pp.330-336
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• 2004

In this work, in order to obtain the detailed information about lightning electromagnetic pulses, the electric fields radiated from multiple lightning return strokes were measured and analyzed statistically. The electric field measuring system consists of a hemisphere antenna of 30cm in diameter, integrator and data acquisition device, and its frequency bandwidth ranges from 200Hz to 1.56MHz, and the sensitivity is 0.96㎷/V/m. The electric field signals are digitized every 200ns with the transient signal analyzer having the resolution of 12-bit and the recording length of 5 kilowords and are registered at personal computer. As a result, the electric fields produced by the first return stroke begin with a slow initial part or front, which starts just after or during the last stepped leader. On the average the rise times of the electric fields for the positive first, second and third strokes are 4.21${\mu}\textrm{s}$, 3.94${\mu}\textrm{s}$ and 2.75${\mu}\textrm{s}$, respectively, and those for the negative first, second and third strokes are 3.46${\mu}\textrm{s}$, 3.15${\mu}\textrm{s}$ and 2.79${\mu}\textrm{s}$, respectively. The zero-crossing times of the electric fields for first return strokes range from about 10 to 80${\mu}\textrm{s}$. The mean zero-crossing times for subsequent return strokes are shorter than those for first lightning return strokes.

• 대한수학회논문집
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• 제15권4호
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• pp.683-689
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• 2000

The convergence rate of the expectation of the logarithm of the first return time R(sub)n with block length n has been investigated for Bernoulli processes. This idea is applied to check the randomness of the digits of the decimal expansion of $\pi$, e and √2.

• 농촌계획
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• 제19권3호
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• pp.169-182
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• 2013

The purpose of this study is derived by Utilization Strategy for Rural empty houses stability of Return to the Farm and Rural. The main findings can be summarized as follows. First, the recent return to the farm and rural has increased, and life patterns of diversification, and the retirement of the baby boomer generation return to the farm and rural ratio differed by region. Second, the required first order accurate and detailed to maximize the utilization of the rural empty houses Survey, and the integrated management system based on it should be built. Third, the public lead in pushing for policy to take advantage of an empty house, leasing and management capabilities by strengthening return to the farm and rural characters, revitalizing rural and residential stabilization is necessary. Finally, in order to enhance the utilization of the rural empty houses should prepare return to the farm and rural, Multi-Habitation and a common space for existing residents for a variety of purposes. The results of these studies has a significance that can promote rural housing return to the farm and rural, resource utilization and stable settlement, and rural areas activated at the same time. Utilization of specific rural empty houses feasible policy being prepared, by linking rural areas that can bring effects on the activation of alternative hope.

• Fisheries and Aquatic Sciences
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• 제8권4호
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• pp.228-234
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• 2005

Despite the relatively high production of fingerlings of the olive flounder Paralichthys olivaceus, its larval rearing in terms of first feeding has not been fully analyzed. We evaluated the variations of amino acids and fatty acids of starved larvae over 96 hr after hatching. We also investigated depletion of the yolk and oil globule of starved larvae and those fed the rotifer Brachionus plicatilis. In addition, the optimum size of the rotifers according to the mouth size of the larvae, and the point of no return with delay of the first feeding, were also examined. The amino acids in the egg decreased abruptly during embryo development. At 48 to 72 hr after hatching, the amino acids of starved larvae decreased by $30-40\%$ from the level in newly hatched larvae. The concentrations of fatty acids in newly hatched larvae were lower than those of floating eggs and dropped sharply at 48 hr after hatching, when the yolk disappeared. The starved larvae depleted their yolksacs and oil globules earlier than the fed larvae did. At 84 hr after hatching, rotifers were detected for the first time in the guts of the larvae, which were about 3 mm in total length. The point of no return appeared to be close to the fourth day from the first feeding. For a high survival rate of P. olivaceus larvae, the first feeding should occur before the third day after hatching.

• Structural Engineering and Mechanics
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• 제49권3호
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• pp.355-372
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• 2014

Considering the history of severe earthquakes and the presence of active faults in the greater Tehran region, the possibility of a destructive earthquake occurring is high and seismic hazard analysis is crucial. Gumbel distributions are commonly-used statistical distributions in earthquake engineering and seismology. Their main advantage is their basis on the largest earthquake magnitudes selected from an equal-time predefined set. In this study, the first asymptotic distribution of extremes is used to estimate seismicity parameters and peak ground acceleration (PGA). By assuming a Poisson distribution for the earthquakes, after estimation of seismicity parameters, the mean return period and the probable maximum magnitude within a given time interval are obtained. A maximum probable magnitude of 7.0 has a mean return period of 100 years in this region. For a return period of 475 years, the PGA in the greater Tehran region is estimated to be 0.39g to 0.42g, depending on local site conditions. This value is greater than that of the Iranian Code for Seismic Design of Buildings, indicating that a revision of the code is necessary.

• 노동경제논집
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• 제26권3호
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• pp.181-207
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• 2003

본 연구는 노동시장 이행을 중점적으로 분석할 수 있는 한국노동패널(KLIPS) 자료를 이용하여 출산 후 노동시장으로의 복귀를 결정하는 요인을 콕스 비례재해를 모형(Cox Regression Hazard Model)으로 분석한 연구이다. 분석 결과 출산 후 노동시장으로의 복귀를 결정하는 데 있어 학력이라는 인적자본이 정(+)의 효과가 뚜렷이 나타났으며, 자녀보육 대행자가 있는가의 여부에 따라 출산 후 노동시장으로 복귀할 이행률이 2배 이상 차이가 나는 것으로 밝혀졌다. 또한 출산 전 취업 형태가 임금근로일 경우 노동시장 복귀로의 이행률이 비임금근로자보다 낮은 것으로 나타났다.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.145-158
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• 2005

We formulate a stochastic control problem on proportional reinsurance that includes impulse and regular control strategies. For the first time we combine impulse control with regular control, and derive the expected total discount pay-out (return function) from present to bankruptcy. By relying on both stochastic calculus and the classical theory of impulse and regular controls, we state a set of sufficient conditions for its solution in terms of optimal return function. Moreover, we also derive its explicit form and corresponding impulse and regular control strategies.