• Journal of the Korea Safety Management & Science
• /
• v.17 no.4
• /
• pp.193-198
• /
• 2015

This study analyzed the total number of 19,636 patients and radiation technologists, 11,433 of male and 8,203 of female by examined body parts, age, types of detectors, the using contrast enhancement and working condition of the technologists, regular staffs or rotation-duty staffs, based on the K-DOS program distributed by FDA with the DLP value of diagnostic evaluation. The result shows that the effective radiation dose was 0.7mSv~41.7mSv for each region and male patients had more radiation exposure than females. And the amount of exposure was also affected by the types and the method of detectors. Furthermore, the regular staffs took the role of helping the patient to get reduced amount of radiation exposure than rotation duty-staffs. Computed tomography (CT) use has increased dramatically over the past several decades. In this reason, to support the patients and the workers' health in the field, the hospitals should apply specialized regular working radiation technologist system and manufacturing companies of those CTs should develop low medical radiation exposure devices.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.270-282
• /
• 2020

Analysis: of the propulsion performance considering ship motion in waves is an important factor for the efficient operation of a ship. The interaction between the propeller and the free surface due to the ship motion in waves has a significant influence on the propulsion performance. However, most recent studies regarding the hydrodynamic performance of ships in waves focus on the added resistance, and experimental and numerical data on the propulsion performance considering the ship motion in waves are very rare. In this study, a numerical investigation of the nominal wake in regular head waves is performed for a KVLCC2 model ship for the fully-loaded condition. Phase-averaged wake fields for one period are compared with experimental data measured using Stereo PIV, showing good agreement. The effect of the ship motion on the characteristics of the wake field and the axial velocity in the propeller plane are investigated while varying the wave length.

• Journal of the Chungcheong Mathematical Society
• /
• v.26 no.4
• /
• pp.799-809
• /
• 2013

An ideal I of a local ring (R, m, k) is said to be m-full if there exists an element $x{\in}m$ such that Im : x = I. An ideal I of a local ring R is said to have the Rees property if ${\mu}$(I) > ${\mu}$(J) for any ideal J containing I. We study properties of m-full ideals and we characterize m-primary m-full ideals in terms of the minimal number of generators of the ideals. In particular, for a m-primary ideal I of a 2-dimensional regular local ring (R, m, k), we will show that the following conditions are equivalent. 1. I is m-full 2. I has the Rees property 3. ${\mu}$(I)=o(I)+1 In this paper, let (R, m, k) be a commutative Noetherian local ring with infinite residue field k = R/m.

• Journal of the Korean Mathematical Society
• /
• v.48 no.2
• /
• pp.301-309
• /
• 2011

Let R = $Mat_2(F)$ be the ring of all 2 by 2 matrices over a finite field F, X the set of all nonzero, nonunits of R and G the group of all units of R. After investigating some properties of orbits under the left (and right) regular action on X by G, we show that the graph automorphisms group of $\Gamma(R)$ (the zero-divisor graph of R) is isomorphic to the symmetric group $S_{|F|+1}$ of degree |F|+1.

• Journal of the Korean Mathematical Society
• /
• v.46 no.3
• /
• pp.551-560
• /
• 2009

A theorem of Robert Blumenthal is used here in order to obtain a sufficient condition for a function between two Finsler manifolds to be a fibre bundle map. Our study is connected with two possible constructions: 1) a Finslerian generalization of usually Kaluza-Klein theories which use Riemannian metrics, the well-known particular case of Finsler metrics, 2) a Finslerian version of reduction process from geometric mechanics. Due to a condition in the Blumenthal's result the completeness of Euler-Lagrange vector fields of Finslerian type is discussed in detail and two situations yielding completeness are given: one concerning the energy and a second related to Finslerian fundamental function. The connection of our last framework, namely a regular Lagrangian having the energy as a proper (in topological sense) function, with the celebrated $Poincar{\acute{e}}$ Recurrence Theorem is pointed out.

• Journal of Communications and Networks
• /
• v.16 no.3
• /
• pp.249-257
• /
• 2014

This paper presents methods to the construction of regular and irregular low-density parity-check (LDPC) codes based on Euclidean geometries over the Galois field. Codes constructed by these methods have quasi-cyclic (QC) structure and large girth. By decomposing hyperplanes in Euclidean geometry, the proposed irregular LDPC codes have flexible column/row weights. Therefore, the degree distributions of proposed irregular LDPC codes can be optimized by technologies like the curve fitting in the extrinsic information transfer (EXIT) charts. Simulation results show that the proposed codes perform very well with an iterative decoding over the AWGN channel.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.376-379
• /
• 1999

The wavelet transform chip is implemented with Daubechies' 4 tap filter. It works at 20MHz in Field Programmable Gate array (FPGA) implementation of Quadrature Mirror Filter(QMF) Lattice Structure. In this paper, the structure contains taro-channel quadrature mirror filter, data format converter(DFC), delay control unit(DCU), and three 20$\times$8 bits real multiplier. The structures for the DFC and DCU need to he regular and scalable, require minimum number of regular, and thereby lead to an efficient and scalable architecture for the Discrete Wavelet Transform(DWT). These results present the possibility that it can be used in Digital Signal Processing(DSP) application faster than Fourier transform at small area with lour cost.

• Korean Journal of Mathematics
• /
• v.21 no.4
• /
• pp.463-471
• /
• 2013

Let R be a ring with identity 1, $I(R){\neq}\{0\}$ be the set of all nonunit idempotents in R, and M(R) be the set of all primitive idempotents and 0 of R. We say that I(R) is additive if for all e, $f{\in}I(R)$ ($e{\neq}f$), $e+f{\in}I(R)$. In this paper, the following are shown: (1) I(R) is a finite additive set if and only if $M(R){\backslash}\{0\}$ is a complete set of primitive central idempotents, char(R) = 2 and every nonzero idempotent of R can be expressed as a sum of orthogonal primitive idempotents of R; (2) for a regular ring R such that I(R) is a finite additive set, if the multiplicative group of all units of R is abelian (resp. cyclic), then R is a commutative ring (resp. R is a finite direct product of finite field).

• Communications of the Korean Mathematical Society
• /
• v.19 no.2
• /
• pp.233-242
• /
• 2004

The aim of this note is to study properties of the generalized centroid of the semi-prime gamma rings. Main results are the following theorems: (1) Let M be a semi-prime $\Gamma$-ring and Q a quotient $\Gamma$-ring of M. If W is a non-zero submodule of the right (left) M-module Q, then $W\Gamma$W $\neq 0. Furthermore Q is a semi-prime $\Gamma$-ring. (2) Let M be a semi-prime $\Gamma$-ring and $C_{{Gamma}$ the generalized centroid of M. Then $C_{\Gamma}$ is a regular $\Gamma$-ring. (3) Let M be a semi-prime $\Gamma$-ring and $C_{\gamma}$ the extended centroid of M. If $C_{\gamma}$ is a $\Gamma$-field, then the $\Gamma$-ring M is a prime $\Gamma$-ring.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.9 no.1
• /
• pp.63-73
• /
• 1991

The data type of the echo sounding for the contouring of coastal chart is continuous profiles, and there are no data between the profiles. In this study, at first, the depths of the regular grid along the sounding line were interpolated by linear equation. After that the depths of the regular grid located between the profiles were interpolated by kriging. The semivariogram contributes to the weight of interpolation. After comparison with the conventional Moving Average and Kriging, it turns out that this algorithm shows merits in the field of the accuracy and computing time.