• 대한수학회지
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• 제46권5호
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• pp.1027-1040
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• 2009

A ring R is called IFP, due to Bell, if ab = 0 implies aRb = 0 for a, b $\in$ R. Huh et al. showed that the IFP condition is not preserved by polynomial ring extensions. In this note we concentrate on a generalized condition of the IFPness that can be lifted up to polynomial rings, introducing the concept of quasi-IFP rings. The structure of quasi-IFP rings will be studied, characterizing quasi-IFP rings via minimal strongly prime ideals. The connections between quasi-IFP rings and related concepts are also observed in various situations, constructing necessary examples in the process. The structure of minimal noncommutative (quasi-)IFP rings is also observed.

• 대한수학회보
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• 제59권6호
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• pp.1327-1337
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• 2022

Zero-difference balanced (ZDB) functions can be applied to many areas like optimal constant composition codes, optimal frequency hopping sequences etc. Moreover, it has been shown that the image set of some ZDB functions is a regular partial difference set, and hence provides strongly regular graphs. Besides, perfect nonlinear functions are zero-difference balanced functions. However, the converse is not true in general. In this paper, we use the decomposition of cyclotomic polynomials into irreducible factors over 𝔽_p, where p is an odd prime to generalize some recent results on ZDB functions. Also we extend a result introduced by Claude et al. [3] regarding zero-difference-p-balanced functions over 𝔽_pⁿ. Eventually, we use these results to construct some optimal constant composition codes.

• 한국병원경영학회지
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• 제6권3호
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• pp.109-129
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• 2001

The purpose of this study was the acquisition of the optimum scale of the apportionment of standard & high-class bed for the maximum profit representative of the desire of customers in a General Hospital with 1,100 beds located in Seoul. This investigation was proceeded by the analysis of the result of the simulation with the survey of both the patients' needs for bed and the degree of the medical service by the grade of the ward. And finally the consequence was obtained as follows: 1. The result of the investigation of the inpatients' preference for the grade of ward classes shows that a private ward reflected 4.3 percent, a semi-private ward 1.7 percent, a three-bed ward 0.1 percent, and a ward with six beds 93.9 percent each other. 2. A questionnaire poll was paralleled of service terms of a medical doctor and a nurse by ward class, the data were used for the standard of the allotment of labor cost by the ward class. The poll shows that the service tenn of a medical doctor and a nurse based on a ward with six beds by ward class showed 1.7 times in internal medicine and 1.9 times in surgery at a private ward; 1.4 times in internal medicine and 1.7 times in surgery at a semi-private room; and 1.2 times both in internal medicine and in surgery at a three-bed ward 3. The resultant findings revealed the most profit per bed and per patient in a private ward. However, an analysis of profit with a standard of unit area by ward class represented a higher profit in both the internal medicine and the surgery semi-private ward than other ward classes. 4. The result of the analysis through simulation based on the data of the prime cost per the ward class proved the optimum scale of the distribution of beds by class as follows: sixteen beds of the internal medicine and twenty three beds of the surgery in the private ward; two hundreds and two of the internal medicine and one hundred and ninety eight of the surgery in the semi-private room; three of both the internal medicine and the surgery each other in the three-bed ward; one hundred and ninety eight of the internal medicine and two hundred and fifty two of the surgery in the ward with six beds. The result of this research exhibits that the income and expenditure of the hospital could be improved by changing parts of wards into private ones(containing the maximum profit per a unit of width) in case the scale of the number of beds is reset with the consideration of the profit per the unit width. In the near future it's strongly expected that the research for the more scientific standard of the allotment of labour cost by ward class and for definition of the optimum scale of the number of beds that actualize the maximum profit with the change of the three elements of the prime cost: cost of materials; labor costs; management expenses.

• 대한수학회보
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• 제40권2호
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• pp.223-234
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• 2003

This note contains the following results for a ring A : (1) A is simple Artinian if and only if A is a prime right YJ-injective, right and left V-ring with a maximal right annihilator ; (2) if A is a left quasi-duo ring with Jacobson radical J such that $_{A}$A/J is p-injective, then the ring A/J is strongly regular ; (3) A is von Neumann regular with non-zero socle if and only if A is a left p.p.ring containing a finitely generated p-injective maximal left ideal satisfying the following condition : if e is an idempotent in A, then eA is a minimal right ideal if and only if Ae is a minimal left ideal ; (4) If A is left non-singular, left YJ-injective such that each maximal left ideal of A is either injective or a two-sided ideal of A, then A is either left self-injective regular or strongly regular : (5) A is left continuous regular if and only if A is right p-injective such that for every cyclic left A-module M, $_{A}$M/Z(M) is projective. ((5) remains valid if 《continuous》 is replaced by 《self-injective》 and 《cyclic》 is replaced by 《finitely generated》. Finally, we have the following two equivalent properties for A to be von Neumann regula. : (a) A is left non-singular such that every finitely generated left ideal is the left annihilator of an element of A and every principal right ideal of A is the right annihilator of an element of A ; (b) Change 《left non-singular》 into 《right non-singular》in (a).(a).

• 한국자동차공학회논문집
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• 제16권4호
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• pp.110-119
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• 2008

Computer methods with simplified mathematical models in conjunction with empirical model parameters can be efficiently practiced into an optimization of a diesel aftertreatment system. Components of prime interests are diesel particulate filter, diesel oxidation catalyst and de-$NO_x$ catalytic converter. de-$NO_x$, de-PM, and de-HC processes in each part are individually modeled, formulated and then combined into an integrated analysis procedure for a unified simulation of the diesel emission aftertreatment. The model is empirically tuned and validated with comprehensive engine and laboratory data. The effects of emission species and space velocity on the $NO_x$ and soot reductions are parametrically investigated. A lowered $NO_2/NO_x$ ratio due to PM oxidation in DPF contributes to promote the $NO_x$ reduction by SCR at intermediate gas temperatures. $NO_x$ reduction is inert to the PM oxidation at high temperatures. Rate of PM trapping strongly depends on temperature and $NO_x$ concentration.

• Carbon letters
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• 제16권1호
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• pp.25-33
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• 2015

The prime objective of this research was to study the influence of hot-pressing pressure and matrix-to-reinforcement ratio on the densification of short-carbon-fiber-reinforced, randomly oriented carbon/carbon-composite. Secondary objectives included determination of the physical and mechanical properties of the resulting composite. The 'hybrid carbon-fiber-reinforced mesophase-pitch-derived carbon-matrix' composite was fabricated by hot pressing. During hot pressing, pressure was varied from 5 to 20 MPa, and reinforcement wt% from 30 to 70. Densification of all the compacts was carried at low impregnation pressure with phenolic resin. The effect of the impregnation cycles was determined using measurements of microstructure and density. The results showed that effective densification strongly depended on the hot-pressing pressure and reinforcement wt%. Furthermore, results showed that compacts processed at lower hot-pressing pressure, and at higher reinforcement wt%, gained density gradually during three densification cycles and showed the symptoms of further gains with additional densification cycles. In contrast, samples that were hot-pressed at moderate pressure and at moderate reinforcement wt%, achieved maximum density within three densification cycles. Furthermore, examination of microstructure revealed the formation of cracks in samples processed at lower pressure and with low reinforcement wt%.

• 한국군사과학기술학회지
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• 제13권4호
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• pp.699-707
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• 2010

Electric-field-induced electron emission from the three kinds of $Pb(Zr_{0.56}Ti_{0.44})O_3$ ferroelectric cathodes with different electrode structure has been investigated. Regardless of the electrode structures, a threshold field of the each cathode was 2.5-2.6kV/mm, which is 3 times higher than the coercive field of $Pb(Zr_{0.56}Ti_{0.44})O_3$ material. Although the waveform of the electron currents was affected by the structure of the electrode, no significant difference for the emission properties such as the peak current and the pulse width was observed from the three kinds of the cathodes. However, the current density of the cathode was dependent on the electrode structure. From the simulation of electric field distribution, the surface flashover, and the injury region of the cathode surface, it was proved that the prime electrons were initiated at the electrode-ceramic-vacuum triple point by field emission and the emission currents were strongly enhanced by the surface plasma.

• 대한토목학회논문집
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• 제11권3호
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• pp.85-93
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• 1991

실트질 접토의 심강(沈降) 특성(特性)에 미치는 초기농도(初期濃度)($C_o$) 및 저면전단응력(底面剪斷應力)(${\tau}_b$)의 효과에 대한 연구를 하기 위해 황해안 영광해역에서 채취한 실트질 점토를 사용하여 순환식 개수로에서 퇴적실험(堆積實驗)을 하였다. 상대농도(相對濃度) $C/C_o$(C=수심 평균한 농도) 및 상대평형농도(相對平衡濃度) $C_{eq}/C_o$($C_{eq}$=평형상태에서 수심 평균한 농도)는 저면전단응력(底面剪斷應力)에 강하게 좌우되며, 초기농도(初期濃度)에는 큰 영향을 받지 않는 것으로 나타났고, 또한 이들 값은 저면전단응력(底面剪斷應力)이 클수록 증가하였다. 황해안 영광해역 퇴적물(堆積物)의 퇴적한계저면전단응력(堆積限界底面剪斷應力)의 최소치는 ${\tau}_{bmin}{\simeq}0.017N/m^2$, 퇴적한계저면전단응력(堆積限界底面剪斷應力)의 최대치는 ${\tau}_{bmax}{\simeq}1.25N/m^2$이며, 이들 값은 퇴적물(堆積物)의 구성성분에 강하게 좌우된다. ${\tau}_b{\geq}{\tau}_{bmin}$ 범위에서 상대농도(相對濃度)($C_{eq}/C_o$)와 겉보기 중앙심강속도(中央沈降速度)($W_{s50}{^{\prime}}$)에 대한 식을 유도하였다. 겉보기 중앙심강속도(中央沈降速度)는 초기농도(初期濃度)보다 저면전단응력(底面剪斷應力)에 훨씬 더 강한 영향을 받고, 저면전단응력(底面剪斷應力)이 증가할수록 지수적으로 감소하였다.

• 직업교육연구
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• 제35권4호
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• pp.109-129
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• 2016

최근 우리나라는 미래국가성장동력을 마련하기 위해 과학인재양성에 힘쓰고 있다. 이에 교육부에서는 이공계 대학교육의 내실화를 위한 특별법을 마련하고, 산업연계 교육 활성화 선도대학(PRIME)과 같은 사업을 시행하여 교육적인 지원을 제공하고 있다. 그러나 이러한 지원에도 불구하고 이공계 내 다른 계열과 비교하여 현재 자연과학계열 인력은 수요와 공급이 불균형을 이루고 있는 실정이며, 더욱이 자연과학계열 대학생들은 전공 외 분야에 취업하는 경우가 많아, 이들을 위한 진로교육이 필요하다는 목소리가 제기되고 있다. 이에 본 연구에서는 한 개인의 진로발달과정에서 진로결정에 영향을 미치는 변인에 대한 포괄적인 이해가 가능한 사회인지진로모형(SSCT)을 바탕으로 자연과학계열 대학생들의 진로준비행동에 대한 그릿(Grit), 진로결정자기효능감, 진로결과기대, 전공흥미 변인의 예측력 및 이들 간의 경로관계를 실증적으로 규명하고자 하였다. 이를 위해 A대학 자연계열 학생 153명을 대상으로 자료를 수집하여 경로분석을 실시하였다. 연구 결과, 그릿에서 진로결정자기효능감, 진로결과기대, 전공흥미, 진로준비행동으로 가는 경로모형은 통계적으로 적합한 것으로 나타났다. 이를 바탕으로 자연과학계열 대학생들이 그들의 전공 분야와 관련한 진로준비행동을 촉진하기 위해서는 그릿, 진로결정자기효능감, 진로결과기대, 전공흥미를 통합적으로 고려한 체계적인 진로교육이 제공되어야 함을 제안하였다.

• 한국게임학회 논문지
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• 제12권3호
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• pp.37-48
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• 2012

우리 게임사에 큰 족적을 남기고 있는 호러어드벤처게임인 <화이트데이>는 흉측한 몬스터들과 음산한 분위기의 스테이지를 디자인하고 있는 잔혹한 호러가 아니라, 귀신 소리를 효과음으로 나타내는 청각적인 공포를 활용하여 한국적인 공포를 디자인해내고 있다. 본고는 <화이트데이>의 구성요소들을 통해 순기능적인 스토리텔링의 구조를 파악해 보는 것이 연구 목적이다. 연구 결과, <화이트데이>는 배경, 사건, 인물이 매우 탄탄한 시나리오를 지니고 있다는 사실을 파악할 수 있었다. 또한 모든 설계구조와 스토리텔링구조는 서구형 호러게임이 지닌 스플레터적인 호러를 모방하지 않고 순기능적인 요소를 강화시키고 있다는 사실을 확인하였다. 플레이어에게 미미크리와 일링크스가 내재된 놀이요소를 제공하여 인터랙티브한 재미성을 확대시켜주고 있는 <화이트데이>는 이 시대에 가장 필요성을 느끼는 순기능적인 게임의 표본이다.