• Communications of the Korean Mathematical Society
• /
• v.22 no.3
• /
• pp.411-417
• /
• 2007

N(k)-quasi Einstein manifolds are introduced and studied.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2008.12a
• /
• pp.216.2-216.2
• /
• 2008

• Ocean and Polar Research
• /
• v.26 no.2
• /
• pp.255-263
• /
• 2004

This study was conducted to investigate the community structure and distributional pattern of meiobenthos in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of the northeastern Pacific during July 2003. The samples were collected using the multiple corer at 13 stations along the transects fiom $5^{\circ}N\;to\;17^{\circ}N$. The most abundant meiobenthos was nematodes and followed by sarcomastigophorans; these two taxa comprised more than 70% of the total abundance at all stations. For size distribution analyses showed that animals which fit into the sieve mesh size of 0.063mm were abundant. The maximum density of meiobenthos was $147inds./10cm^2$ at station located in $7^{\circ}N$, and the minimum density was $6 inds./10cm^2$ at station located in $14^{\circ}N$. More than 60% of meiobenthos were distributed at surface sediment layer within 1.0cm, and the peak abundance was found at $0{\sim}0.25cm$ layer. The latitudinal distribution pattern of meiobenthos in the study area seemed to be related with the primary productivity of the surface water that is also connected to the water circulation pattern of the Pacific Ocean near the Equator, diverging at latitude of $8^{\circ}N$ and conversing at $5^{\circ}N$.

• Journal of People, Plants, and Environment
• /
• v.24 no.5
• /
• pp.469-483
• /
• 2021

Background and objective: If the Nelumbo nucifera spreads in a wetland at a high density, it can have considerable positive and negative ecological effects on habitats. For this reason, it is necessary to precisely investigate the impacts of its rapid proliferation. This study was conducted to propose the distribution and management of N. nucifera, which can cause the degradation of wildlife habitats due to the rapid spread of internal and external environmental factors that may affect the Junam wetland ecosystem. Methods: For the investigation and analysis of physical and ecological characteristics, factors of the abiotic environment such as general weather conditions, topography and water depth structure, and soil and water quality analysis, and bioenvironment characteristics such as changes in the N. nucifera community distribution were evaluated. To assess whether the differences in the soil depth and physicochemical characteristics between the N. nucifera community and the aquatic plant community are statistically significant, a One-way ANOVA was executed. Results: N. nucifera was presumably introduced in approximately 2007 and observed at a prevalence of only 0.8% in 2009, but had expanded to 11.1% in 2014. After that, the area was increased to 19.3% in 2015 and 40.0% in 2017, about twice that of the previous survey year. The rapid diffusion of an N. nucifera colony can have adverse effects on wildlife habitats and biodiversity at Junam Wetland. To solve these problems, four management methods can be proposed; water level management, mowing management, installation of posts and removal of lotus roots. Control of the N. nucifera community using these methods was judged to be suitable for cutting and water level management when considering expansion rate, water level variation, and wildlife habitat impacts. Conclusion: As the biotic and abiotic environmental factors are different for each wetland, it is necessary to determine the timing and method of management through a detailed investigation.

• Animal Systematics, Evolution and Diversity
• /
• no.nspc7
• /
• pp.1-90
• /
• 2009

Twenty-two new species of poecilostome copepods associated with marine invertebrates are described from the West Indies, Madagascar, and Pacific coast of Panama. They are Anthessius nosybensis n. sp. and Discanthessius solitarius n. gen. n. sp. in the Anthessiidae; Cemihyclops tenuis n. sp., Hemicyclops tripartitus n. sp., H. humesi n. sp., H. magnus n. sp., and Leptinogaster minuta n. sp. in the Clausidiidae; Schedomolgus crenulatus n. sp. and S. parvipediger n. sp. in the Anchimolgidae; Kelleria multiovigera n. sp. in the Kelleridae; Lichomolgus angustus n. sp. and L. fusiformis n. sp. in the Lichomolgidae; Pseudanthessius acutus n. sp., P. asper n. sp., and Tubiporicola pediger n. gen. n. sp. in the Pseudanthessiidae; Acanthomolgus tenuispinatus n. sp. and Notoxynus lokobensis n. sp. in the Rhynchomolgidae; Eupolymniphilus occidentalis n. sp. and E. brevicaudatus n. sp. in the Sabellephilidae; Enalcyonium robustum n. sp. and E. grandisetigerum n. sp. in the Lamippidae; and O. binoviger n. sp. in the Myicolidae. Hemicyclops geminus Stock is synonymized with H. columnaris Humes which is now known as a species of amphi-American distribution. Hemicyclops columnaris Humes, Modiolicola trabalis Humes, and Ostrincola breviseti Ho and Kim are redescribed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.2
• /
• pp.128-131
• /
• 2009

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used Monte-Carlo method. We simulated the effect of channeling by Al implantation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the effect of varying the implantation energies and the corresponding doses on the distribution of Al in 4H-SiC. The controlled implantation energies were 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2{\times}10^{14}$ to $1{\times}10^{15}\;cm^{-2}$. The Al ion distribution was deeper with increasing implantation energy, whereas the doping level increased with increasing dose. The effect of post-implantation annealing on the electrical properties of Al-implanted p-n junction diode were also investigated.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.10 no.3
• /
• pp.158-163
• /
• 1990

This experiment was to study the effect of pure mineral nitrogen fertilizing on seasonal distribution of dry matter yield and the advisable mineral nitrogen amounts on grassland. The results were as follows: 1. With longer regrowth periods the absolute dry matter yields and the nitrogen-efficiences due to nitrogen fertilizing increased substantially, whereas the quality declined at the relatively lesser cutting frequencies. 2. The first cut at 3-cut regimes, the first and fourth cut at 4-cut regimes, and the second and last cut at 5-and 6-cut regimes showed the highest nitrogen-efficiency, respectively. 3. By the sigmaformed process of production curve the most efficient mineral N-dressing rate per ha and cut was calculated: 42-56kg N on the 3-cut areas, 39-55kg N on the 4-cut areas, 38-47kg N on the 5-cut areas and 35-48kg N/ha/cut on the &cut areas. 4. In dependence on site and kind of calculation the economical borders were reached with the following dressings of mineral N/ha/cut: 90-100kg on the 3-cut areas, 70-100kg on the 4-cut areas and 50- 90kg on the 5-and 6-cut areas.

• Journal of Korean Institute of Industrial Engineers
• /
• v.21 no.3
• /
• pp.313-327
• /
• 1995

This paper deals with ordering policies for a multi-echelon distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N nonidentical Regional Distribution Centers(RDCs) which have different demand rates, minimum filtrates, leadtimes, etc. We develop an algorithm for determining the optimal ordering policies of the CDC and the RDCs under the constraints of minimum filtrates of RDCs and maximum allowable delay of CDC.

• Journal of applied mathematics & informatics
• /
• v.24 no.1_2
• /
• pp.221-230
• /
• 2007

The exponential and the gamma distributions have been the traditional models for drought duration and drought intensity data, respectively. However, it is often assumed that the drought duration and drought intensity are independent, which is not true in practice. In this paper, an application of the bivariate gamma exponential distribution is provided to drought data from Nebraska. The exact distributions of R=X+Y, P=XY and W=X/(X+Y) and the corresponding moment properties are derived when X and Y follow this bivariate distribution.

• Communications for Statistical Applications and Methods
• /
• v.1 no.1
• /
• pp.52-56
• /
• 1994

When we have an i.i.d. sample of size n from a continuous distribution, the distribution truncated on the left at the rth order statistic plays an important role in the theoretical analysis of the Type 2 censored data. The charaterization of distributions by the average of the conditional expectation and the average of the conditional information concerning the truncated distribution is studied here.