• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.205-210
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• 2004

According to Diriclet's Theorem, there are infinitely many primes of the form An+ 1 for any fixed positive integer A. For this, there already exists a classical simple proof using cyclotomic polynomials. In this paper, we develop another elementary proof of this statement.

• Korean Journal of Mathematics
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• v.26 no.2
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• pp.293-297
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• 2018

In the paper [4], we constructed 3-part of the Hilbert class field of imaginary quadratic fields whose class number is divisible exactly by 3. In this paper, we extend the result for any odd prime p.

• Journal of Integrative Natural Science
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• v.14 no.4
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• pp.159-161
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• 2021

In this article, we will study which prime numbers are represented by the principal form. p = x² + ny². We will also give some results related to the form of primes of the form x² + axy + y².

• Atmosphere
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• v.15 no.3
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• pp.149-153
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• 2005

A balloon-borne Optical Particle Counter (hereafter "OPC Sonde"), which was developed by the atmospheric research group of Nagoya University, is used for getting the information of vertical profile of particle size and concentration in Anmyeon ($36^{\circ}32^{\prime}N$ $126^{\circ}19^{\prime}E$) on 18 March 2005. A range of five different particle sizes is shown in the vertical profile of aerosol number density estimated from the OPC Sonde. It was found that small size particles have vertically larger aerosol number density than relatively big ones. For all size ranges the vertical aerosol number density shows a decreased pattern as the altitude becomes higher. The aerosol number density of $0.3{\sim}0.5{\mu}m$, $0.5{\sim}0.8{\mu}m$, $0.8{\sim}1.2{\mu}m$ size ranges at the 10km height, which is the tropopause approximately, are $1,000,000ea/m^3$, $100,000ea/m^3$, $10,000ea/m^3$ respectively. The data of OPC Sonde are also compared with the data of PM10 $\beta$-ray) and Micro Pulse Lidar which are operating at Korea Global Atmosphere Watch Observatory in Anmyeon.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.657-660
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• 2000

This paper proposes a Data-Flow-Graph (DFG) restructuring to reduce calculating errors in loop folding scheduling. The prime cause of calculating error is rounding errors due to the restriction of the operation digit of functional units. This rounding error is increased more by using multipliers than adders, so reducing the number of multiplications and putting off them as much as possible reduce rounding errors. The proposed approach reduces the number of multiplications by restructuring DFG in loop folding.

• Korean Journal of Mathematics
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• v.30 no.2
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• pp.187-198
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• 2022

In this paper, we introduce a new concept in number theory called ζ-factors associated with a positive integer n. Applications of ζ-factors are in the arrangement of the defining polynomials in cyclic n-roots algebraic system and are thoroughly investigated. More precisely, ζ-factors arise in the proofs of vanishing theorems in regard to associated prime factors of the system. Exact computations through concrete examples of positive dimensions for n = 16, 18 support the results.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.101-111
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• 1983

This experiment was conducted to investigate the flora of Kyungpook National University Forests, which is located in Walme-Ri, Hyundong-Myon, Chungsong-Kun and at $128^{\circ}$ 59' $55^{\prime\prime}-129^{\circ}$ 01' 30"E longitude and $36^{\circ}$ 10' $30^{\prime\prime}-36^{\circ}$ 13' 00"N latitude. The results obtained can be summarized as follows; The kinds of the vascular plants identified are 298 which are composed of 79 families, 188 genera, 248 species, 1 subspecies, 46 varieties and 3 formae. Woody plants are composed of 39 families, 67 genera, 112 species, 7 varieties and 3 formae. The total number of woody plants listed are 122, tall trees of woody plants 50, shrubs 46 and winders 16, respectively. The kinds of edible plants listed are 118 such as Lithospermum erythrohizon, Codonopsis lanceolata and Aster scaber etc. Medical plants are listed as 48 kinds such as Schizandra chinensis, and A canthopanax sessiliflorus etc. Con Codonopsis Schizandra. It is the first time to report that the populations of Ulmusmacrocarpa, Acanthopanax sessiliflorus, Schizandra chinensis, and Lithospermum erythrorhizon are existed in this area.

• Wind and Structures
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• v.26 no.5
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• pp.331-341
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• 2018

A numerical study on the flow over a square cylinder in the vicinity of a wall is conducted for different Couette-Poiseuille-based non-uniform flow with the non-dimensional pressure gradient P varying from 0 to 5. The non-dimensional gap ratio L (=$H^{\ast}/a^{\ast}$) is changed from 0.1 to 2, where $H^{\ast}$ is gap height between the cylinder and wall, and $a^{\ast}$ is the cylinder width. The governing equations are solved numerically through finite volume method based on SIMPLE algorithm on a staggered grid system. Both P and L have a substantial influence on the flow structure, time-mean drag coefficient ${\bar{C}}_D$, fluctuating (rms) lift coefficient ($C_L{^{\prime}}$), and Strouhal number St. The changes in P and L leads to four distinct flow regimes (I, II, III and IV). Following the flow structure change, the ${\bar{C}}_D$, $C_L{^{\prime}}$, and St all vary greatly with the change in L and/or P. The ${\bar{C}}_D$ and $C_L{^{\prime}}$ both grow with increasing P and/or L. The St increases with P for a given L, being less sensitive to L for a smaller P (< 2) and more sensitive to L for a larger P (> 2). A strong relationship is observed between the flow regimes and the values of ${\bar{C}}_D$, $C_L{^{\prime}}$ and St. An increase in P affects the pressure distribution more on the top surface than on bottom surface while an increase in L does the opposite.

• Journal of Radiation Protection and Research
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• v.43 no.2
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• pp.75-84
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• 2018

Background: Gamma-ray spectrometry helps in radiation shielding problems and different applications of radioisotopes. Experimental arrangements including broad beam geometries are widely used. The aim is to investigate and evaluate the ${\gamma}-ray$ spectra via attenuation by environmental materials. Materials and Methods: The photo peak to nominated parts in the ${\gamma}-ray$ spectra and the attenuation coefficients ${\mu}_b/{\rho}$ from broad beam geometries are measured for the materials water, soil, sand and cement at the energies 0.662, 1.25, and 1.332 MeV with a $3{^{\prime}^{\prime}}{\times}3{^{\prime}^{\prime}}$ NaI(Tl) detector. Results and Discussion: The ${\gamma}-ray$ spectra vary according to changes in the effective atomic number $Z_{eff}$ of the attenuator, the photon energy and the solid angle. The peak to total ratios are the most sensitive parts to variations in the experimental conditions and overturn in the region 0.663 MeV to 1.332 MeV. This is indicated as inversion trend. The results are discussed in view of $Z_{eff}$ and the experimental conditions. The intensity build-up is larger at the lower energy and larger scattering angles in agreement with Klein-Nishina formula and other results. The build-up factor B is$${\sim_=}$$1 at high ${\gamma}-energies$ and small scattering angles. Conclusion: The sensitivity to material characteristics decrease gradually from peak: to total, to Compton valley, to Compton plateau ratios. Rigorous collimation is necessary at small energies. Cement, of the largest $Z_{eff}$, is characterized by the maximum broad beam mass attenuation coefficients ${\mu}_b/{\rho}$. The obtained results provide information to decide for the suitable experimental set-up based on aim of the work.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.373-379
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• 2015

Supply units in each command are multi-tiered and each supply unit keeps a supply level independently, which can cause excess stock, leading false reports to the Logistics Command and increasing difficulties in managing user needs. This causes excess assets and the excess then causes deformation in demand. therefore, the supply support systems of our armed forces have become high-cost/low-efficiency and are insufficient to meet the needs of users in combat units. Civilian corporations and the US Department of Defense are downsizing the aforementioned multi-tiered supply systems thus revolutionizing efficient and effective logistics by adopting Supply Chain Management(SCM), and Prime Vendor policies. Prime Vendor policy is a logistics support method that allows users to directly request and receive supply items from suppliers, based on supply contracts between suppliers and central maintenance organizations like KDA. In other words, it is a system that allows for users to make orders to suppliers directly and suppliers to deliver goods to the users directly, cutting out the middle stage, thus allowing an efficient supply. This is a way forward in finance that cuts costs in net supplies and allows an efficient utilization of civilian assets. which is also known to fasten the speed of logistical support and stripping down the logistical structure. therefore, this report will explore Prime Vendor policies adopted in certain number of units for medical supplies that were taken in consideration of improvements in stock management in civilian organizations and the US Army, and aims to apply such policies for repair parts.