• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.485-488
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• 2005

In this paper designed available pre-amplifier to Ultrabroadband power amplifier. Designed pre-amplifier used WJ company's AM1 which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\sim}$ 3GHz using feedback.

• Journal of Urban Science
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• v.11 no.1
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• pp.1-8
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• 2022

As the magnitude and frequency of earthquakes increase in Korea, interest in earthquake damage reduction technology has increased. Therefore, research on vibration damping devices that directly respond to seismic loads is being actively researched. After an earthquake, damage or destruction of the device occurs due to the yield of materials, and thus it takes considerable cost and time for restoration and replacement. To supplement the problems of the existing earthquake damage reduction technology, a study was conducted on the recentering smart damper that can be used continuously after an earthquake. In this study, the recentering smart damper that can be restored to its original shape after load removal was developed using superelastic shape memory alloy, pre-compressed polyurethane. General steel was commonly applied to verify the seismic performance of the superelastic shape memory alloy, and the performance of the smart damper was verified according to the amount of polyurethane pre-compressed

• Korean Journal of Child Studies
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• v.29 no.1
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• pp.275-292
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• 2008

This study investigated the effects of a teaching process using dynamic assessment for a unit on young children's measurement ability. Subjects were 45 5-year-old children in a kindergarten in Busan. The instrument was the Dynamic Assessment Tools for Young Children's Measurement Ability (Hwang & Ko, 2(07). Assessment consisted of four steps: pre-test, learning, transfer, post-test. Results were that at post-test, there were significant differences in scores of measurement ability between the dynamic assessment and control groups. In the dynamic assessment group there was significant improvement in length, width and weight between pre- and post-tests and there were significant shifts of measurement strategies and measurement errors between the pre- and post-tests.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.3 no.1
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• pp.108-127
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• 1996

The purpose of this research was to determine whether or not a education program of low back pain would have benificial effect on nurses. Nonequivalent control group pre-post test research was designed. Subjects for this study were 50 selected from nurses who work at a general hospital in Taegu. Of them, twenty seven were assigned to experimental group, twenty-three to control group. The data were collected during the period from June 27 to August 31, 1994. The instruments used in this study were Visual Analog Scale for low back pain, Sit-and-reach test for trunk flexibility, and 1 min sit up test for abdominal muscle endurance. Data related to general chracteristics and factors of low back pain were collected with questionnaire developed by this reseacher. The data were analyzed by $X^2-test$, t-test and paired t-test, using the SAS package program. The results of this study are summerized as follows : 1. The numbers of the experimental group with low back pain were not a statistically significant difference from pre to posttesting($X^2=0.77$, p=.379), and the numbers of the control group with low back pain were also not a statistically significant difference from pre to posttesting($X^2=0.09$, p=.767). 2. The severity of low back pain of the experimental group was not a statistically significant difference from pre to posttesting(t=-0.55, p=.5857), and the severity of low back pain of the control group was also not a statistically significant difference from pre to posttesting(t=-0.70, p=.3101). 3. The trunk flexibility of the experimental group was not a statistically significant difference from pre to posttesting(t= 1.08, p=.2835), and the control group's trunk flexibility was also not a statistically significant difference from pre to posttesting(t=0.85, p=.4026). 4. The abdominal muscle endurance of the experimental group was a statistically significant difference from pre to posttesting(t=-2.42, p=.0190), but the control group's abdominal muscle endurance was not a statistically significant difference from pre to posttesting(t=-0.06, p=.9556) This study suggest that replication of study with more sample and more rigid treatment should be needed. And furthermore, the longitudinal research is needed to determine the effectiveness of education program.

• Journal of The Korean Association of Information Education
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• v.24 no.1
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• pp.29-37
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• 2020

There is a great deal of effort to improve Computational Thinking in education. In this paper, we define the relationship between SW capability and Computational Thinking, and then examine the current status of pre-service teacher's computing thinking. For this purpose, a survey about the attitude toward SW education and computing thinking was administered to prospective teachers who learned Entry software for one semester. The results of the survey showed that the improvement of abstraction, data analysis, and automation among the pre-service teacher's computing thinking is needed. When educating preliminary teachers, we can see that we need an education method that can increase the analysis and design capability beyond the Entry Software development tool.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.161-172
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• 2020

The tensile property of A5082 and A6060 aluminium wrought alloys was investigated, in terms of the strain rate sensitivity on alloy conditions by heat treatment and bake hardenability on pre-strain prior to strain ageing. The tensile test was carried out in a range of strain rate of 4.17 × 10^-5 s^-1 ~ 4.17 × 10^-5 s^-1 in room temperature and the nominal range of pre-strain was 3.0 ~ 10.5%. The tensile deformation of A5082 alloys is characterized as typical case of dynamic strain ageing with negative strain rate sensitivity for all conditions, and the tensile strength indicates a similar level regardless of alloy conditions, except only in full annealed condition. The stress-relief annealing on A6060 alloys can induce practical decrease in strength level of over approximately 100 MPa without any ductility loss, compared to as-rolled condition, while a full annealed and aged condition leads remarkable strengthening effect with the decrease of tensile elongation. Additionally, the bake hardenability of A5082 alloy by strain ageing indicates a negative dependence upon the increase of pre-strain, while A6060 alloy exhibits a positive sign even in low level relatively compared with conventional SPCC.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.2
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• pp.335-342
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• 1999

This study is aimed at providing useful data which can be utilized for the design of their dress forms and enhancing the fitness of their apparels. To this end 330 pre-school children living in the capital area and aged from 4 to 6 were sampled to be subject to the measurement of their somatotypes. The results of this study can be summarized as follows ; 1 By the analysis of overlapped cross section diagram and silhouette diagram of each somatotype both had a common shape of lean-backed upper troso. 2. The type 1 showed less dimensions in most scales than type 2 while their shoulder were less developed. The type 2 showing more development in each element. 3. As a result of comparing the dress forms designed in reference with classified somatotypes and the commercial ones it was found that the former ones had the upper body part slanted slightly backwards and the belly part extruded forwards while the latter had a straight posture with large shoulder parts. After all the commercial dress forms were found not to reflect the actual somatotypes of Pre-School children's.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.35-40
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• 2002

In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strianed specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steel which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.61-66
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• 2008

For the production of urethane prepolymer, the effect of process parameters such as diisocyanate MDI and polyol TDI was tested. In this paper, design of experiments has been adopted for studying the effect of the process parameters on the improvement of NCO and viscosity of pre-polymer. As a result of comparison of different parameters, the effect of polyol was stronger than that of isocyanate in comparison of reactivity according to the amounts of isocyanate and polyol. Especially, NCO and viscosity of pre-polymer affected a product safety.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.237-238
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• 2008

It is believed that the pre-flashover phenomena would play a very important role in the procedure of the flashover in the interface between the insulators and vacuum. This paper is mainly concerned on the pre-flashover phenomena of Alumina insulators in vacuum. There are 24 different types of alumina insulators were tested with a $0.7/4{\mu}s$ pulsed voltage under a $1{\times}10^{-4}Pa$ vacuum. The observed pre-flashover phenomena were classified and the pre-flashover characteristics were concluded. It is useful to study further on the flashover mechanism in vacuum.