• 제목/요약/키워드: prime numbers

검색결과 111건 처리시간 0.023초

An Experimental Study of Accelerating Phase Change Heat Transfer

  • Oh, Yool-Kwon;Park, Seul-Hyun;Cha, Kyung-Ok
    • Journal of Mechanical Science and Technology
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    • 제15권12호
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    • pp.1882-1891
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    • 2001
  • The present paper investigated the effect of ultrasonic vibrations on the melting process of a phase-change material (PCM). Furthermore, the present study considered constant heat flux boundary conditions unlike many of the previous researches adopted constant wall temperature conditions. Therefore, in the present study, modified dimensionless parameters such as Ste* and Ra* were used. Also, general relationships between melting with ultrasonic vibrations and melting without ultrasonic vibrations were established during the melting of PCM. Experimental observations show that the effect of ultrasonic vibrations on heat transfer is very important throughout the melting process. The results of the present study reveal that ultrasonic vibrations accompany the effects like agitation, acoustic streaming, cavitation, and oscillating fluid motion. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. They enhance the melting process as much as 2.5 tildes, compared with the result of natural melting. Also, energy can be saved by applying ultrasonic vibrations to the natural melting. In addition, various time-wise dimensionless numbers provide conclusive evidence of the important role of ultrasonic vibrations on the melting phenomena.

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건설현장의 안전 분위기와 작업자 안전행동에 관한 실증적 연구 (A Study on the Safety Climate and Worker's Safe Work Behavior in Construction Site)

  • 최수일;김홍
    • 한국안전학회지
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    • 제21권5호
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    • pp.60-71
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    • 2006
  • In recent years, the most safety studies have been focused on identifying the relationship between safety climate and safe work behavior in accordance with the awareness that prime causes of accidents are organizational, managerial, and human factors rather than pure technical failures across the world. This study focused empirical research aimed at finding out the safety climate factors and examining the relationships of the safety climate and safe work behavior in construction site in Korea, too. A 10 numbers of safety climate factors were adapted from the Mohamed's study(2002) and tested using PLS-GRAPH 3.0 expecting same results as Mohamed' study. And then the relationship between safety climate and safe work behavior was examined. Only two safety climate factors-personal risk appreciation and worker's safety competence-were found and a strong positive relationship between safety climate and safe work behavior was identified in this study. Discussed in details about the results and implications and suggested further studies.

LOCAL PERMUTATION POLYNOMIALS OVER FINITE FIELDS

  • Lee, Jung-Bok;Ko, Hyoung-June
    • 대한수학회논문집
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    • 제9권3호
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    • pp.539-545
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    • 1994
  • Let $q = p^r$, where p is a prime. A polynomial $f(x) \in GF(q)[x]$ is called a permutation polynomial (PP) over GF(q) if the numbers f(a) where $a \in GF(Q)$ are a permutation of the a's. In other words, the equation f(x) = a has a unique solution in GF(q) for each $a \in GF(q)$. More generally, $f(x_1, \cdots, x_n)$ is a PP in n variables if $f(x_1,\cdots,x_n) = \alpha$ has exactly $q^{n-1}$ solutions in $GF(q)^n$ for each $\alpha \in GF(q)$. Mullen ([3], [4], [5]) has studied the concepts of local permutation polynomials (LPP's) over finite fields. A polynomial $f(x_i, x_2, \cdots, x_n) \in GF(q)[x_i, \codts,x_n]$ is called a LPP if for each i = 1,\cdots, n, f(a_i,\cdots,x_n]$ is a PP in $x_i$ for all $a_j \in GF(q), j \neq 1$.Mullen ([3],[4]) found a set of necessary and three variables over GF(q) in order that f be a LPP. As examples, there are 12 LPP's over GF(3) in two indeterminates ; $f(x_1, x_2) = a_{10}x_1 + a_{10}x_2 + a_{00}$ where $a_{10} = 1$ or 2, $a_{01} = 1$ or x, $a_{00} = 0,1$, or 2. There are 24 LPP's over GF(3) of three indeterminates ; $F(x_1, x_2, x_3) = ax_1 + bx_2 +cx_3 +d$ where a,b and c = 1 or 2, d = 0,1, or 2.

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Can We Reduce Workplace Fatalities by Half?

  • Koh, David Soo Quee
    • Safety and Health at Work
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    • 제3권2호
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    • pp.104-109
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    • 2012
  • Singapore, an island republic of over 5 million inhabitants, has 3.1 million workers. Most are employed in the service, finance and tourist/transport industry. Significant numbers work in manufacturing, construction and heavy industry. Following a series of construction and shipyard accidents with multiple deaths in 2004, the government announced its intention to reduce workplace fatalities from 4.9 to 2.5 per 100,000 by 2015. There was strong political will to achieve this target. The strategic approaches were to build workplace safety and health (WSH) capabilities; implement legislative changes with enforcement; promote benefits of WSH and recognize best practices, and enhance partnership with stakeholders. The anticipated outcomes were to reduce workplace fatality and injury rates; have WSH as an integral part of business; and establish a progressive and pervasive WSH culture. With these measures, the workplace fatality rate declined from 4.9/100,000 in 2004, to 2.2/100,000 in 2010. However, other confounding factors could also account for this decline, and have to be considered. The next target, announced by Singapore's Prime Minister in 2008, is to further reduce the workplace fatality rate to 1.8/100,000 by 2018, and to have "one of the best workplace safety records in the world".

종합병원 간호사의 자기주장과 간호사-의사의 협업에 대한 태도의 관계 (Relationship between Assertiveness and Attitudes toward Nurse-Physician Collaboration in General Hospital Nurses)

  • 이상민;손수경
    • 동서간호학연구지
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    • 제21권2호
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    • pp.156-164
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    • 2015
  • Purpose: This study was conducted to identify the relationship of assertiveness and attitudes toward nurse-physician collaboration in general hospital nurses. Methods: The subjects were 196 clinical nurses from two general hospitals in P city. Data were collected from August 1 to 30, 2014 and analyzed by SPSS 18.0 program using descriptive statistics, t-test, ANOVA, $Sheff{\acute{e}}^{\prime}s$ test, and Pearson's correlation coefficients. Results: The mean scores of assertiveness and attitudes toward nurse-physician collaboration were $3.20{\pm}.42$ and $3.20{\pm}.30$, respectively. Assertiveness and attitudes toward nurse-physician collaboration according to the general characteristics showed significant differences on the numbers of advisors and job satisfaction. There was a significant positive correlation between assertiveness and attitudes toward nurse-physician collaboration. Conclusion: Based on results of this study, additional variables related to attitudes toward nurse-physician collaboration need to be identified. Educational programs to improve the attitudes toward nurse-physician collaboration should be developed.

ANALOGUE OF WIENER INTEGRAL IN THE SPACE OF SEQUENCES OF REAL NUMBERS

  • Ryu, Kun Sik
    • 충청수학회지
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    • 제25권1호
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    • pp.65-72
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    • 2012
  • Let T > 0 be given. Let $(C[0,T],m_{\varphi})$ be the analogue of Wiener measure space, associated with the Borel proba-bility measure ${\varphi}$ on ${\mathbb{R}}$, let $(L_{2}[0,T],\tilde{\omega})$ be the centered Gaussian measure space with the correlation operator $(-\frac{d^{2}}{dx^{2}})^{-1}$ and ${\el}_2,\;\tilde{m}$ be the abstract Wiener measure space. Let U be the space of all sequence $<c_{n}>$ in ${\el}_{2}$ such that the limit $lim_{{m}{\rightarrow}\infty}\;\frac{1}{m+1}\;\sum{^{m}}{_{n=0}}\;\sum_{k=0}^{n}\;c_{k}\;cos\;\frac{k{\pi}t}{T}$ converges uniformly on [0,T] and give a set function m such that for any Borel subset G of $\el_2$, $m(\mathcal{U}\cap\;P_{0}^{-1}\;o\;P_{0}(G))\;=\tilde{m}(P_{0}^{-1}\;o\;P_{0}(G))$. The goal of this note is to study the relationship among the measures $m_{\varphi},\;\tilde{\omega},\;\tilde{m}$ and $m$.

치과위생사의 내적·외적만족과 조직몰입도의 관련성 (The correlation between the internal·external satisfaction and organizational commitment of dental hygienist)

  • 류혜겸
    • 한국치위생학회지
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    • 제17권5호
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    • pp.735-745
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    • 2017
  • Objectives: This study was conducted to provide a basic set of data on the correlation relationship between the internal external satisfaction and organizational commitment of dental hygienist. Methods: The research subjects were a total 264 numbers of dental hygienists in Busan and Gyeongnam. The study was conducted from July 1 to August 30, 2016. Structured questionnaires were used for analysis. The collected data was analyzed using IBM SPSS. Statistics 20.0. Results: Job satisfaction according to general characteristics showed high internal satisfaction and external satisfaction in age and prime duty, and internal satisfaction in career. The factors affecting organizational commitment were sub-factors of job satisfaction, external satisfaction and internal satisfaction. Conclusions: The atmosphere composition must be to improve that in the dental clinic, the dental hygienist's scope of work, autonomy, and sense of accomplishment through job the organizational commitment of the dental hygienists. This should be supported by the effective management of human resources, salary structure and the improvement of the system.

제초제 저항성 유전자와 기존 병 저항성 유전자가 연관된 형질전환 토마토 개체 선발 및 후대분석 (Progeny Analysis and Selection of Tomato Transformants with patII Gene linked to Inherent Disease Resistance Gene)

  • 안순영;강권규;윤해근;박효근
    • 원예과학기술지
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    • 제29권4호
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    • pp.345-351
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    • 2011
  • 원예작물의 내병성 육종에 있어 $F_2$와 그 이후 분리 세대에서 유용하게 사용할 수 있는 선발방법의 모델 시스템을 개발하고자 하였다. 상용 토마토 품종인 '모모따로 요크'에 제초제 저항성 유전자를 도입한 후 획득된 형질전환체의 도입 유전자 수와 후대 분리비를 분석하고, 제초제 저항성 유전자와 기존 병 저항성 유전자가 연관된 개체를 선발하였다. 총 60개의 형질전환체 중에서 42개체에 Southern blot을 실시하여 도입 유전자 수를 확인하고, 제초제 저항성 유전자에 대한 분리비를 비교 분석하여 Southern 결과와 도입된 유전자의 표현형의 분리비가 일치하지 않으며 여러 개의 copy가 삽입된 대부분의 경우, 실제 도입된 copy 수보다 더 적은 copy 수를 가지는 것처럼 분리비를 나타내는 것을 알 수 있었다. 삽입된 제초제 저항성 유전자와 기존 병 저항성 유전자가 가깝게 연관된 개체를 찾기 위해 $T_1(F_2)$세대 개체에 대하여 two-stepwise screening 방법을 실시하여 위조병 저항성 I2 유전자(11번 염색체)와 제초제 저항성 patII 유전자가 대략 12-13cM으로 가깝게 연관된 개체(T-20)를 선발하였다.

n+1 소인수분해 알고리즘 (The n+1 Integer Factorization Algorithm)

  • 최명복;이상운
    • 한국인터넷방송통신학회논문지
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    • 제11권2호
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    • pp.107-112
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    • 2011
  • $n=pq$인 합성수 을 크기가 비슷한 p와 q로 소인수분해하는 것은 매우 어려운 문제이다. 대부분의 소인수분해 알고리즘은 $a^2{\equiv}b^2$ (mod $n$)인 제곱 합동이 되는 ($a,b$)를 소수의 곱 (인자 기준, factor base, B)으로 찾아 $a^2-b^2=(a-b)(a+b)$ 공식에 의거 유클리드의 최대공약수 공식을 적용하여 $p=GCD(a-b,n)$, $q=GCD(a+b,n)$으로 구한다. 여기서 ($a,b$)를 얼마나 빨리 찾는가에 알고리즘들의 차이가 있으며, B를 결정하는 어려움이 있다. 본 논문은 좀 더 효율적인 알고리즘을 제안한다. 제안된 알고리즘에서는 $n+1$을 3자리 소수까지 소인수분해하여 B를 추출하고 B의 조합 $f$를 결정한다. 다음으로, $a=fxy$가 되는 값을 $\sqrt{n}$ < $a$ < $\sqrt{2n}$ 범위에서 구하여 $n-2$의 소인수분해로 $x$를 얻고, $y=\frac{a}{fx}$, $y_1$={1,3,7,9}을 구한다. 제안된 알고리즘을 몇 가지 사례에 적용한 결과 $\sqrt{n}$ < $a$를 순차적으로 찾는 기존의 페르마 알고리즘에 비해 수행 속도를 현격히 단축시키는 효과를 얻었다.

초등에서의 곱셈적 사고 지도 - 초등 5학년을 위한 교수-학습 자료 개발을 중심으로 - (Multiplicative Thinking in Elementary Mathematics Education - Focusing on the development of teaching-learning materials for 5th graders -)

  • 한은혜;류희수
    • 대한수학교육학회지:학교수학
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    • 제10권2호
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    • pp.155-179
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    • 2008
  • 7차 교육과정에서 곱셈 문제들은 구구단을 암기하고 적용하여 푸는 기능적인 면에 치중하고 있어 아동들이 세거나 그리는 덧셈적 사고에 머무르고 있다. 정수, 소수, 분수, 비 비율과 같은 수의 확장에서 효율적으로 곱셈과 나눗셈을 사용하여 풀 수 있는 능력과 자신이 풀이한 방법을 정확하게 설명할 수 있는 곱셈적 사고로의 이행을 위한 다양한 연구가 부족하다. 본 논문은 초등학교 5학년을 중심으로 덧셈적 사고에 머무르는 아동의 사고가 보다 높은 수준의 곱셈적 사고로 이행하도록 하기 위한 교수-학습 자료를 개발하고, 적용한 후 그 결과를 분석하였다. 덧셈적 사고와 곱셈적 사고에 대한 새로운 틀을 제시하고 이에 알맞은 자료를 개발함으로써 개발된 자료의 타당성과 곱셈적 사고로의 용이로운 전이가 가능함을 검증할 수 있었다.

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