• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.243-250
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• 1999

We consider $Y=X{\lambda}Z,\;{\lambda}>0$, where X and Z are independent random variables, and Y is the length biased distribution or the equilibrium distribution of X. The purpose of this paper is to consider the distribution of X or Y when the distribution of Z is given and the distribution of Z when the distribution of X or Y is given, In particular, we obtain that the necessary and sufficient conditions for X to be $X^{2}({\upsilon})\;is\;Z{\sim}X^{2}(2)\;and\;for\;Z\;to\;be\;X^{2}(1)\;is\;X{\sim}IG({\mu},\;{\mu}^{2}/{\lambda})$, where $IG({\mu},\;{\mu}^{2}/{\lambda})$ is two-parameter inverse Gaussian distribution. Also we show that X is smaller than Y in the reverse Laplace transform ratio order if and only if $X_{e}$ is smaller than $Y_{e}$ in the Laplace transform ratio order. Finally, we can get the results that if X is smaller than Y in the Laplace transform ratio order, then $Y_{L}$ is smaller than $X_{L}$ in the Laplace transform order, and that if X is smaller than Y in the reverse Laplace transform ratio order, then $_{\mu}X_{L}$ is smaller than $_{\nu}Y_{L}$ in the Laplace transform order.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.509-517
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• 2009

Seagrass meadows are important biogenic habitats for a wide variety of marine animals and plants, a source of organic carbon for commercially important animals, and act as a nutrient filter in estuarine and coastal ecosystems. As such, mapping the distribution of seagrass beds provides us with an important component of management and conservation strategies. To survey seagrass distribution within Deukryang Bay, we directly observed seagrass beds using SCUBA in Boseong-gun, Goheung-gun, and Jangheung-gun. Seagrass distribution in Geogeum and Gumdang islands were not observed. Specifically, we monitored the distribution area, species composition, morphology, density, and biomass of seagrass meadows. Seagarss beds were mapped for Daikum-ri coast, Deukryang island, Yongjeong-ri coast, Samsan-ri coast and Ongam-ri coast. Total seagrass coverage in Deukryang Bay was $5.1\;km^2$, $4.8\;km^2$ of which was Zostera marina, $0.3\;km^2$ Z. caulescence and $0.01\;km^2$ Z. japonica. Z. japonica was found in intertidal zones, Z. marina was found from the intertidal to subtidal zones of 2 m MSL (mean sea level) depth, and Z. caulescence was found in subtidal zones of 2.5-5 m MSL.

• Journal of Ecology and Environment
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• v.46 no.2
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• pp.111-125
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• 2022

Background: Zanthoxylum armatum is one of the 30 prioritized medicinal plants for economic development of Nepal with a high trade value. Understanding the ecology of individual species is important for conservation and cultivation purposes. However, relation of ecological factors on the distribution and populations of Z. armatum in Nepal remain unknown. To address this knowledge gap, an attempt has been made to study the population structure, distribution, and regeneration potentiality of Z. armatum. Vegetation sampling was conducted at six different localities of Salyan district along the elevation range of 1,000 m to 2,000 m. Results: Altogether 50 plant species belonging to 44 genera under 34 families were found to be associated with Z. armatum. Significantly higher species richness was found at Rim (1,400-1,700 m) and Chhatreshwori (1,800-2,000 m) and lower at Kupinde (1,600-1,800 m). The highest population density of Z. armatum was at Kupinde (1,600-1,800 m) with a total of 1,100 individuals/ha. and the lowest at Chhatreshwori (1,800-2,000 m) with 740 individuals/ha. Based on the A/F value (Whitford index), it can be said that Z. armatum has random distribution in the study area. The plants were categorized into seedlings, saplings and adults based on plant height and the status of natural regeneration category determined. The regeneration potentiality of Z. armatum in the study area was fair with the average seedlings and saplings densities of 150 and 100 individuals/ha. Respectively. A Shannon-Weinner index mean value of 2.8 was obtained suggesting high species diversity in the study area. Conclusions: The natural distribution and regeneration of Z. armatum is being affected in the recent years due to anthropogenic disturbances. Increasing market demand and unsustainable harvesting procedures are posing serious threat to Z. armatum. Thus, effective conservation and management initiatives are most important for conserving the natural population of Z. armatum in the study area.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.261-265
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• 2017

Let X and Y be independent identically distributed nondegenerate random variables with common absolutely continuous probability distribution function F(x) and the corresponding probability density function f(x) and $E(X^2)$<${\infty}$. Put Z = max(X, Y) and W = min(X, Y). In this paper, it is proved that Z - W and Z + W or$(X-Y)^2$ and X + Y are independent if and only if X and Y have normal distribution.

• Bulletin of the Korean Mathematical Society
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• v.47 no.3
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• pp.443-454
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• 2010

In this paper, we investigate the zeros distribution and Borel direction for the solutions of linear homogeneous differential equation $f^{(n)}+A_{n-2}(z)f^{(n-2)}+{\cdots}+A_1(z)f'+A_0(z)f=0(n{\geq}2)$ in an angular domain. Especially, we establish a relation between a cluster ray of zeros and Borel direction.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2161-2166
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• 2008

This paper deals with a Z-source active power filter(Z-AFU) for mitigation voltage THD(total harmonic distortion) due to voltage harmonic propagation(amplification) in 6.6kv power distribution system. Bus voltage harmonic signal is detected by 60Hz butterworth BPF(band pass filter). As an ESS(energy storage system) of the proposed system, PEM fuel cells(Ballard NEXA, 1.2kw) is employed. Test results based on PSIM(power electronics simulation tool) validate the proposed approach.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.339-348
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• 2012

To survey the seagrass distribution in Jeju and Chuja Islands, we directly observed seagrass beds using SCUBA in July, 2011. Distributional area, species composition, morphology, density, and biomass of seagrasses and environmental characteristics were examined in investigation sites. In particular, three protected seagrass species (Zostera marina, Z. caulescens and Z. caespitosa) were found in the investigation areas. While the three species were found in Chuja Island, only Z. marina was distributed in Jeju Island. Z. marina was distributed only north-eastern coast of Jeju Island, and the total coverage was $238,572m^2$. Total seagrass coverage of Chuja Island was $23,584m^2$. In detail, Z. caulescens Z. caespitosa and Z. marina were 21,216, 1,870 and $498m^2$, respectively. Of these, Z. marina was found from the intertidal to subtidal zones of 5m MSL (mean sea level) depth. Z. caespitosa and Z. caulescens were found in subtidal zones of 3~4 m and 4~6m MSL depth, respectively.

• Bulletin of the Korean Mathematical Society
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• v.53 no.1
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• pp.29-38
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• 2016

For a transcendental entire function f(z) with zero order, the purpose of this article is to study the value distributions of q-difference polynomial $f(qz)-a(f(z))^n$ and $f(q_1z)f(q_2z){\cdots}f(q_mz)-a(f(z))^n$. The property of entire solution of a certain q-difference equation is also considered.

• Kyungpook Mathematical Journal
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• v.61 no.1
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• pp.99-110
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• 2021

In the present paper, we determine new characterisations of the subclasses ����∗��(α, β; γ) and ������(α, β; γ) of analytic functions associated with Pascal distribution series ${\Phi}^m_q(z)=z-{\sum_{n=2}^{\infty}}(^{n+m-2}_{m-1})q^{n-1}(1-q)^mz^n$. Further, we give necessary and sufficient conditions for an integral operator related to Pascal distribution series ${\mathcal{G}}^m_qf(z)={\int_{0}^{z}}{\frac{{\Phi}^m_q(t)}{t}}dt$ to belong to the above classes. Several corollaries and consequences of the main results are also considered.

• Journal of the Korean earth science society
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• v.38 no.7
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• pp.511-521
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• 2017

This study analyzes Two-dimensional video disdrometer (2DVD) data while summer 2011-2012 in Daegu region and compares with Marshall and Palmer (MP) distribution to find out statistical characteristics and characteristics variability about drop size distribution (DSD) of Daegu region. As the characterize DSD of Daegu region, this study uses single moment parameters such as rainfall intensity (R), reflectivity factor (Z) and double moment parameters such as generalized characteristics number concentration ($N{_0}^{\prime}$) and generalized characteristics diameter ($D{_m}^{\prime}$). Also, this study makes an assumption that DSD function can be expressed as general gamma distribution. The results of analysis show that DSD of Daegu region has ${\log}_{10}N{_0}^{\prime}=2.37$, $D{_m}^{\prime}=1.04mm$, and c =2.37, ${\mu}=0.39$ on average. When the assumption of MP distribution is used, these figures then end up with the different characteristics; ${\log}_{10}N{_0}^{\prime}=2.27$, $D{_m}^{\prime}=0.9mm$, c =1, ${\mu}=1$ on average. The differences indicate liquid water content (LWC) of Daegu distribution is generally larger than MP distribution at equal Z. Second, DSD shape of Daegu distribution is concave upward. Other important facts are the characteristics of Daegu distribution change when Z changes. DSD shape of Daegu region changes concave downward (c =2.05~2.55, ${\mu}=0.33{\sim}0.77$) to cubic function-like shape (c =3.0, ${\mu}=-0.13{\sim}-0.33$) at Z > 45 dBZ. 35 dBZ ${\leq}$ Z > 45 dBZ group of Daegu distribution has characteristics similar to maritime cluster of diverse climate DSD study. However, Z > 45 dBZ group of Daegu distribution has a difference from the cluster.