• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.7
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• pp.693-700
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• 2016

It is important that we can calculate the order of non-supersingular elliptic curves with large prime factors over the finite field GF(q) to guarantee the security of public key cryptosystems based on discrete logarithm problem(DLP). Schoof algorithm, however, which is used to calculate the order of the non-supersingular elliptic curves currently is so complicated that many papers are appeared recently to update the algorithm. To avoid Schoof algorithm, in this paper, we propose an algorithm to calculate orders of elliptic curves over finite composite fields of the forms $GF(2^m)=GF(2^{rs})=GF((2^r)^s)$ using Weil's theorem. Implementing the program based on the proposed algorithm, we find a efficient non-supersingular elliptic curve over the finite composite field $GF(2^5)^{31})$ of the order larger than $10^{40}$ with prime factor larger than $10^{40}$ using the elliptic curve $E(GF(2^5))$ of the order 36.

• Journal of Educational Research in Mathematics
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• v.25 no.1
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• pp.1-19
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• 2015

This paper aims to explore what we can improve in the curriculum, teaching-learning, and evaluation on the bases of the analyses of multiple-choice items set in National Assessment of Educational Achievement. For this goal, by using the distribution curves of the responses percentages, we will grasp the features of educational achievement which appear to students through an in-depth analysis about not only item itself but also the contents included in particular distracters. These analyses provide more information than the descriptive statistical values such as the mean of correct answer percentage and the discrimination of whole group and the mean of responses percentages of replies of subgroups. Because the distribution curves of the responses percentages reveal the transition from the lowest to the highest educational achievement very well. From these analyses we acquire the implications about the concept of prime factor or prime factorization, ratio(proportion) such as velocity, linear function, volume of cone, properties of solid figure, and probabilities of empty event and total event.

• Analytical Science and Technology
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• v.13 no.1
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• pp.27-33
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• 2000

Simultaneous separation and analysis of Ni(II), Pd(II), Co(II), Cu(II) and Hg(II) in peperidinedithiocarbamate (PDTC) chelates were investigated by reversed phase liquid chromatography. The optimum conditions for the separation of PDTC metal chelates were examined with respect to the pH, extraction solvent, and mobile phase strength on Novapak $C_{18}$ column using methanol/water mixture as mobile phase. All metal PDTC chelates were eluted in an acceptable range of capacity factor value ($0{\leq}log\;k^{\prime}{\leq}1$). The linear calibration curves were obtained in the concentration range of $0{\sim}1.2{\mu}g/mL$ for five metal ions, and also good precision in the range of 1.96~3.41% RSD was obseved. Under the optimum conditions, trace metat ions in the composite water sample were successfully separated and determined with relative error of ${\pm}2.0%$.

• Journal of dental hygiene science
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• v.18 no.5
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• pp.280-287
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• 2018

Dental hygienists are important members of any dental clinic. They are recognized as reflecting the dental clinic's image because they spend a lot of time with patients. The longer the dental hygienist is employed, the better the relationship with the patients and the medical service provided. The purpose of the present study was to develop a scale to measure factors of long-term employment among dental hygienists. The basic questions were constructed by analyzing tools used to measure job embeddedness and satisfaction. Forty-one questions were developed that measured organizational fit (13), interpersonal relationships (8), job satisfaction (7), duty satisfaction (6), recognition (4), and self-esteem (3). A questionnaire survey was conducted, and the responses from 297 dental hygienists in dental clinics, after the exclusion of 20 incomplete surveys, were used for the exploratory and confirmatory factor analyses. As revealed by exploratory factor analysis, long-term employment intention was composed of 7 factors consisting of 29 items after the exclusion of 12. The subsequent confirmatory factor analysis revealed 4 factors ("organizational fit," "professional identity," "job connectivity," and "interpersonal relationship") consisting of 16 items, after the exclusion of 13. $Cronbach^{\prime}s\;{\alpha}$ were 0806, 0.836, 0.700, and 0.684 for the four factors. This study is meaningful in that it developed a long-term employment factor measurement tool that can be applied to domestic dental hygienists. Future studies will need to focus more on professional identity and job outcomes. The results of this study and future related ones could be used to improve dental hygienist's continuous service.

• Journal of the Korean Home Economics Association
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• v.44 no.5 s.219
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• pp.99-107
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• 2006

The purposes of this study are to identify the types of teacher efficacy, to present a theoretical base for teacher efficacy among Home Economics teachers and subsequently, to improve the quality in the practices of home economics education. To achieve these purposes, 263 secondary school home economics teachers were surveyed by the prime investigator. The three research questions of this study were: 1. What are the individual characteristics, the environmental characteristics and the trends of teacher efficacy among secondary school home economics teachers? 2. What is the factor in teacher efficacy among secondary school home economics teachers? 3. What are the types of teacher efficacy among secondary school home economics teachers? For these research questions, factor analysis and cluster analysis were conducted. The factor analysis on teacher efficacy with a survey of secondary school home economics teachers produced 5 factors of efficacy: classroom management, needs assistance, instructional strategies, environmental assistance and teaming assistance. The teacher efficacy had a mean of 3.58 and the home economics teachers showed a slightly higher level in teacher efficacy. Of the 5 efficacy factors, classroom management showed the highest level (M=3.89), followed by learning assistance (M=3.81), instrumental strategies (M=3.57), environmental assistance (M=3.42) and needs assistance (M=3.19). Overall, the teachers had positive feeling in teacher efficacy. Three types of teachers were found in the types of teacher efficacy: the supreme, the average and the efforts-needy. Those types were identified based on the mean scores of the five sub-domains from the factor analysis. To enhance the teacher efficacy, the needs assessments for the students and behavioral adjustment issues should be reflected in the curriculum of teacher education and workshops. The primary investigator suggested that continuous and long-term plans for teacher education need to be developed because short-term plans may not be effective in changing attitudes such as teacher efficacy.

• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.152-160
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• 2007

Recently, the government is very active to secure the financial resources by inducement of the private investment in fulfilling an extension of the SOC facilities. One of the reasons that the private investors hesitate to put money into the private finance projects, however, is the lack of knowledges about various risks to be possibly incurred during the project execution. This research was performed as one of the preparation works in order for a A engineering company to act as a prime contractor of the project management service in the private finance project, and finally developed the risk factor dictionary as a new concept to satisfy the requirement of a A company and overcome a limit of the existing risk checklists. Although the risk factor dictionary looks like the only simplified table to be the risk factors identified in three dimensions, the impacts and response strategies expressed in narrative and multi-items, and the responsible parties indicated, it has great meanings to get a lot of direct and indirect accomplishments over the simplified table during the development process.

• Restorative Dentistry and Endodontics
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• v.27 no.3
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• pp.239-248
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• 2002

이 연구의 목적은 와동의 형태가 굴곡강도와 탄성계수 등 복합레진의 물리적 성질에 미치는 영향을 평가하는 것이다. 복합레진은 Clearfil$^{TM}$ AP-X(Kuraray, Japan)와 Esthet-X$^{TM}$(Dentsply, USA)가 이용되었으며, 상아질 접착제는 Clearfil$^{TM}$ SE Bond(Kuraray, Japan)와 Prime & Bond NT$^{TM}$(Dentsply, USA)를 사용하였다. 대조군의 시편은 split steel mold(25mm$\times$2mm$\times$2mm) 내에 상기 2종류의 복합레진을 충전하여 2개의 대조군 시편을 제작하였으며, 2.4 및 3.4의 C-factor를 부여하기 위한 유리 모형와동을 제작하고, 와동 내에 상기 2종류의 복합레진을 충전하기 전 유리와동의 내면은 sandblasting 처리하고 각각의 복합레진과 동일회사 제품의 상기 상아질 접착제로 처리한 후, 복합 레진을 각각 충전하여 4개의 실험군을 제작하였다. 제작된 실험군 시편은 저속 diamond saw로 충전된 복합레진 부위의 중심부를 통과하도록 절단하여 레진기둥(25mm$\times$2mm$\times$2mm)이 되도록 제작하였다. 제작된 시편을 37$^{\circ}C$의 증류수에 24시간 동안 보관 후, 만능시험기(EZ Test, Shimadzu, Japan)를 이용하여 분당 1mm의 crosshead speed로 3점 굴곡강도를 측정하였다. 또 Linometer(R&B, Korea)를 이용하여 복합레진의 중합수축량을 측정하였으며 굴곡강도측정 후 시편의 파단면은 주사전자현미경(S-2300, Hitachi, Japan)을 이용하여 관찰하였다. 실험결과의 통계분석은 95% 수준의 one-way ANOVA/Tukey's test를 이용하여 결과를 얻었다. 실험에 이용된 2종류 복합레진의 굴곡강도와 탄성계수는 C-factor치 증가에 따라 감소하였으며, 파단면 또한 C-factor의 증가에 따라 더 불규칙해지는 양상을 나타내었다. 본 실험의 결과 hybrid형 복합레진이 micro-hybrid형 복합레진에 비해 C-factor의 영향을 더 많이 받는 것으로 나타났으며, 와동의 C-factor증가가 굴곡강도나 탄성계수와 같은 복합레진의 물리적 성질을 저하시킨다는 것을 의미하였다.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.246-252
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• 2019

In the system of GC-OTC/FID (Gas chromatography-Open Tubular Column/Flame Ionization Detector), DMSO (Dimethyl sulfide) solvent was used to separate the polar solvents (Alcohols). In this system DMSO was eluted later than the separated polar solvents. At this system to calculate chromatographic factors [adjusted retention time ($t_R^{\prime}=t_R-t_O$), capacity factor{$k^{\prime}=(t_R-t_O)/t_O$} and separation factor {${\alpha}=(t_{R2}-t_O)/(t_{R1}-t_O)$}], dead time($t_O$) is necessary, but the method to calculate it has not been reported yet. Therefore, we have tried to develop $t_O$. To calculate $t_O$, we conversed DMSO retention time (DMSO $t_R$) to logarithm ($f(x)={\log}\;t_{R(DMSO)}{\rightarrow}t_O$, $t_O={\log}$ 9.551=0.980). To confirm the optimization of the developed method, we compared with $CH_4\;t_R$ and ${\ln}\;t_{R(DMSO)}$. Both of the values calculated by $CH_4\;t_R$ and ${\ln}\;t_{R(DMSO)}$ were not suitable in the calculation k' and ${\alpha}$. The developed method in this study{${\log}\;t_{R(DMSO)}$} has satisfied both of the values k' criteria (1${\alpha}(1<{\alpha}<2)$. The developed calculation method in this study was easy and convenient, therefore it can be expected to be applied to these similar systems.

• 전기의세계
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• v.21 no.3
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• pp.41-47
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• 1972

The requirements of a successful design for single phase induction motors with a high efficiency have, in recent years, led to the use of non-quadrature stator windings motors in which a high starting torque is a prime requisite. The capacitor motor is one of above machines in which various possible forms of asymmetry can be occur. These forms of asymmetry in the stator phase windings, encountered in machine designs, are 1) an asymmetrical disposition in space of their magnetic axes, 2) a difference in their effective number of turns, 3) a difference in the distribution of their coil groups per pole and 4) amounts of capacitance of an auxiary winding. In order to apply the effective performance prediction of these form to motors, mading of lower quality-domestic magnetic materials, the analysis and the experimental investigations of its sample motors are described in this paper. The utility of such a motor is demonstrated and it is shown that the effects- a good efficiency, good power factor and high starting torque-of the motor mechanism with non-quadrature stator phase windings can development disadvantages by using the lower quality-domestis magnetic materials.

• Bulletin of the Korean Mathematical Society
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• v.51 no.4
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• pp.943-948
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• 2014

Suppose that G is a finite group and H is a subgroup of G. H is said to be an ss-quasinormal subgroup of G if there is a subgroup B of G such that G = HB and H permutes with every Sylow subgroup of B; H is said to be semi-p-cover-avoiding in G if there is a chief series 1 = $G_0$ < $G_1$ < ${\cdots}$ < $G_t=G$ of G such that, for every i = 1, 2, ${\ldots}$, t, if $G_i/G_{i-1}$ is a p-chief factor, then H either covers or avoids $G_i/G_{i-1}$. We give the structure of a finite group G in which some subgroups of G with prime-power order are either semi-p-cover-avoiding or ss-quasinormal in G. Some known results are generalized.