• Journal of Science Education
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• v.47 no.1
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• pp.24-36
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• 2023

In this study, we investigated chemistry teachers' the Stage of Concern (SoC) and the Level of Use (LoU) regarding competency assessment, which was emphasized along with the introduction of the 2015 revised curriculum. A questionnaire was developed based on the CBAM, and responses from 123 chemistry teachers were analyzed. The frequency was investigated for both SoC and LoU, and then the chi-square test was performed according to demographic variables. As a result of the SoC analysis, most of the teachers stayed in stage 3 (management concern, 26.8%) and stage 2 (personal concern, 19.5%). Additionally, among the demographic variables, there was a statistically significant difference in whether or not related education experience was present during the pre-service teacher period. In LoU analysis, Level III (mechanical) was the most frequent (26.8%), followed by Level I (orientation, 22.8%), Level II (preparation, 13.8%). In LoU, there was also a statistically significant difference in whether or not related education experience was present during the pre-service teacher period. The Spearman correlation coefficient between SoC and LoU in the competency assessment was .298 and there was a positive correlation. Based on the above results, educational implications for improving the concern and use of chemistry teachers for competency assessment were discussed.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1976.04a
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• pp.184.5-184
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• 1976

In the course of studies on thermostable liquefying amylase from thermostable Bacillus spp., we have isolated a strain which produces amylase activity. This strain was identified to be Bacillus stearothermophlus. The amylase of this strain demonstrated a maximum activity at 65$^{\circ}C$ and Ca$\^$＋＋/ did not improve thermostability of the enzyme although the erzyme was capable of hydrolyzing starch at temperature of 80$^{\circ}C$ and above. The maximum amount of the enzyme was product at pH 7.0, 50$^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.254-258
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• 2000

Current leads of high $T_{c}$ superconductor were fabricated with Bi excess B $i_{2.2}$/S $r_{1.8}$/C $a_{1}$/C $u_{2}$/ $O_{x}$ composition by rapid cooling method. The dimensions of final samples were fixed 3 mm and 8 mm diameter with 50 mm length each To control uniform density the samples were preformed by CIP(Cold Isostatic Press) process and followed by partial or full melting process after raising up to 90$0^{\circ}C$ for 30min. Plate shaped microstructure was clearly observed adjacent to the Ag tube wall and the size of plate was about 100$\mu$m. However the severe destruction of growth orientation was shown in the inner growth part. critical temperature ( $T_{c}$) was about 53~71K after directional growth while Tc was decreased about 77~80 K before directional growth. After directional growth critical current( $I_{c}$) and critical current density( $J_{c}$) in the specimen of 8 mm diameter at 50 K were about 110 A and 280 A/c $m^2$ respectively.pectively.ely.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.159-169
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• 2002

The present study investigates in detail the combined effects of the Coriolis and centrifugal farce on the development of laminar flows in a square-sectioned U-bend rotating about an axis parallel to the center of bend curvature. When a viscous fluid flows through a rotating curved region, two types of secondary flow occur. One is caused by the Coriolis force due to the rotation of U-bend and the other by the centrifugal farce due to the curvature of U-bend. When the values of Rossby number and curvature ratio are large, the flow field in a rotating U-bend can be represented by two dimensionless parameters ; the Dean number K$\_$LC/=Re/√λ and a body ratio F=λ/Po. For positive rotation, where the rotation is in the same direction as that of the main flow, both the Coriolis force and the centrifugal force act radially outwards, the directions of the two secondary flows are the same. Therefore, the flow structure is qualitatively similar to that observed in a stationary curved duct with a larger f7c. On the other hand, in case of negative rotation, where two farces act in opposite direction, more complex flow fields can be observed depending on the relative magnitudes of the forces.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.317-320
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• 2004

• Journal of the Korean Operations Research and Management Science Society
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• v.7 no.2
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• pp.49-52
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• 1982

정규형(cannonical form) 또는 표준형(standard form)의 선형계획법문제의 감도분석은 이미 잘 알려져 있다. 여기에서는 다음과 같은 일반한계문제의 감도분석을 다루기로 한다. max CX s.t. (I) AX= b 0$\leq$ι$\leq$X$\leq$u 이 경우에서도 일반 선형계획법문제와 같이 C,b,A에 대해 감도분석을 수행할 수 있다. C와 b에 대한 강도분석은 비교적 쉬우나 A에 대한 것은 퍽 복잡하다.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.604-607
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• 1989

In this paper, the commutating devices of the forced commutating circuit and the relation between load current and source voltage are theoretically analyzed, by this approach commutating condition is considered. As a result some basic design methodes of commutating circuit are presented, whitch commutating loss becomes low and commutating failure is not occured.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.428-430
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• 2001

This paper describes development of a preventive diagnostic system for the substation equipments. Data acquisition system, communication control unit and computer systems have been developed in the recent 2 years. The developed system is operating in 345kV U-Ryung substation for performance and environment tests.

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.137.2-138
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• 2000

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1315-1316
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• 2011