• Journal of The Korean Association For Science Education
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• v.19 no.2
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• pp.340-352
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• 1999

Constructivist theory and teaching science in the social context are a main stream in science education. This study was purposed to introduce the STS in-service program implementing in Chonnam National University. and to analyze the results of the program in terms of changes of teachers' and students' perceptions and attitudes. The major features of the STS in-service program were as follows: teacher-centered. teaching in the social context. emphasis on constructivist approach. development of STS module and implementations. A total of 20 secondary science teachers participated in the in-service program. and filled out two questionnaires. Science Education Reform Inventory and Constructivist Teachings Survey. Three of the 20 teachers were selected to gain information from their implementations of a STS module into their respective classrooms. The students completed two instruments. Constructivist Learning Environment Survey. and Scientific Attitude Survey. The responses from teachers and students are as follows: 1. The participating teachers were very aware of the necessity of reform in science education. and the degree of the perception of the necessity increased after the STS in-service program. 2. The STS program significantly improved constructivist teaching techniques. 3. The perceptions of the students about constructivist learning environments improved significantly after the STS in-service program. 4. Students' scientific attitudes improved significantly through STS approach. The STS in-service program with the above mentioned features was found to be effective in our current school system. and could be implemented successfully if teachers were willing to learn and participate in the reforms of science education.

• Journal of Korean Elementary Science Education
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• v.21 no.2
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• pp.289-296
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• 2002

The purpose of this study is to analyze STS contents in the elementary school science textbooks developed under the 7th national curriculum. Major findings from the analyses are as follows: (1) The Percentage of STS contents included is 26% by the number of pages, and 40% by the lesson hour, Higher proportions of the STS contents are found in the domains of ‘energy’ and ‘material’. By grade level, the coverage of 5th grade textbooks is relatively low. (2) Most STS topics are related to science rather than technology or society. (3) In many cases, STS contents are used in the whole processes of a lesson. (4) Most activities are 'group activity' or 'experiment.observation'. There are few activities of 'role playing', 'spot study' or 'interview'. These results indicate that recent STS education trends are reflected on the revised textbooks well. However, it is suggested that some improvement is needed, such as diversification of topic or activity.

• Journal of The Korean Association For Science Education
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• v.24 no.3
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• pp.659-667
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• 2004

The purposes of this study were to examine the middle school science textbooks published according to the 7th curriculum by analyzing overall structure of the books and STS contents, and to diagnose the current status of STS education in science classroom through interviews with teachers and students of the middle schools. It was found that STS approaches were of increasing importance in the science textbooks, however, they were not popular in the science classes. STS topics in the middle school textbooks were related mostly to 'applications of science' and 'social problems and issues', and few of the topics were related to 'cooperative work on real problems', 'multiple dimensions of science' and 'practice with decision making strategies'. Major barriers of STS education implementation in middle school science classroom were identified as follows; difficulties of assessment, teachers' insufficient cognitions and experiences regarding STS education, perceptions of students and parents that prefer didactic lecture methods and working on exercises. Desirable directions for the improvement of present status of STS education in middle school science classes were proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.626-634
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• 2018

These days, widespread use of sensitive loads and distributed generators makes static transfer switch (STS) an essential component in power circuits to achieve a good power quality for AC Grids. In case of a short-circuit fault, previous STS cannot break the fault current. However, the proposed STS has the capability of breaking it quickly as a circuit breaker. Also if there are power quality problems such as Sag/Swell, the proposed STS can quickly transfers the load to the good quality source. Furthermore it is proved that the transfer time of the proposed STS is within one half of period of 3-phase source frequency regardless of the type of load. It is anticipated that the proposed STS may be utilized to realize many stable and reliable AC grid systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.390-395
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• 2003

This study examined the effects of the testing temperature on the mechanical properties of the stainless steels (STS301CSP-3/4H and STS301CSP-H) for flat spring. Hardness test and fatigue test were performed at room temperature (2$0^{\circ}C$ Tensile testandcreeptestwere performed attemperature range 2$0^{\circ}C$~10$0^{\circ}C$. The micro-victors hardness values of STS301CSP-3/4H and STS301CSP-H were HV=443 and HV=488. respectively. The Elastic modulus, tensile strength, yield strength and strain of these materials were decreased with increasing testing temperature. respectively. The maximum creep strain for 100hr atcreep temperature (10$0^{\circ}C$~20$0^{\circ}C$ and creep stress (Tensile strength$\times$50%) of these materials were 0.53％~0.58%. The fatigue limit of STS301CSP-3/4H and STS301CSP-H were 64.5Kgf/mm$^2$ and 67.4Kgf/mm$^2$, respectively.

• Corrosion Science and Technology
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• v.6 no.1
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• pp.1-6
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• 2007

Ferritic stainless steels for the SOFC interconnect applications are required to possess not only a good oxidation resistance, but also a high electrical conductivity of the oxide scale that forms during exposure at the SOFC operating environment. In order to understand the effects of alloying elements on the oxidation behavior of ferritic stainless steels and on the electrical properties of oxide scales, two kinds of commercial ferritic stainless steels, STS 430 and STS 444, were investigated by performing isothermal oxidations at $800^{\circ}C$ in a wet air containing 3% $H_{2}O$. The results showed that STS 444 was superior to STS 430 in both of the oxidation resistance and the area specific resistance. Although STS 444 contained a less amount of Mn for the $(Mn,Cr)_{3}O_{4}$ spinel formation than STS 430, the minor alloying elements of Al and Mo in STS 444, which were accumulated in the base metal region adjacent the scale, were suggested to reduce the scale growth rate and to enhance the scale adherence to the base metal.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.66-72
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• 2000

In these days, with development of industry, the use of machines and structures like ships, airplanes, bridges, power plants, and structure for construction has increased and these machines and structures are used in various corrosive environment. Especially, in case of STS 304, which is material for every kind of machine and chemical plant, it makes many problems related with corrosion and as a result of this, there are happening tremendous economic loss. Therefor, in this study, the test for polarization characteristics was carried out to study characteristics of crevice corrosion of STS 304 which is austenitic stainless steel, in NaCl environment.The main results obtained are as follows :1) Part of crevice is corroded, neighboring outside surface of crevice is passivation. 2) In polarization behavior, corrosion potential of STS 304 become more noble as the concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5% that of STS 3.4 become less noble. 3) The current density under corrosion potential was high drained as concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, the current density was low drained.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.2
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• pp.78-82
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• 2003

Nitrided compound layer and diffusion layer structure were observed by SEM. The compound layer and the constituent of nitrided surface of STS 304, STS 316, STS 410 and SACM 645 steel were analysed using EMPA and XRD respectively. The depth of nitriding layer that is obtained from similar nitriding condition decrease in the order of SACM 645 > STS 410 > STS 316 > STS 304. Result of phase transformation of the nitrided at $550^{\circ}C$ by XRD analysis were as follows; The austenitic stainless steel was mainly consist of $Cr_2N$ accompanying with $Fe_4N$ and $Fe_{2-3}N$ phase and martensitic stainless steel was mainly consist of present $Fe_{2-3}N+Cr_2N$ phase, but SACM 645 steel was $Fe_{2-3}N$ phase present only.

• Journal of The Korean Association For Science Education
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• v.19 no.2
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• pp.248-255
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• 1999

In this study, the effect of the STS program that was oriented from jurisprudental inquiry model on high school underachievers was investigated. The subjects were 76 high school students. They were divided into two groups, the STS program applied class(treatment group) and the traditional lecture-centered class(control group). The STS program was consisted of three subunits. 'nutrient and health', 'stimulation and reaction' and 'reproduction',of 'life' unit of high school general science. And these 3 subunits consisting of eight contents were lectured over 8 hours. The treatment group showed much better achievement in learning significantly (p<.05) than the control group showing that the STS program affected. Therefore, it is necessary to develop the STS program compatible with achievement level of students, and teaching-learning approaches and learning programs for underachievers.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.58-63
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• 2014

This paper deals with the effects of counterpart materials on the wear behavior of thermally sprayed STS316 coatings. STS316 powders were flame-sprayed onto a carbon steel substrate. Dry sliding wear tests were performed using the applied loads of 15 N. AISI52100, $Al_2O_3$, $ZrO_2$ and $Si_3N_4$ balls were used as counterpart materials. Wear behavior of STS316 coatings against different counterpart materials were studied using a scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS). The results show that the wear behavior of thermally sprayed STS316 coatings strongly depends on the type of counterpart material. Dominant wear mechanism was similar for all studied materials as failure of adhesion film except for Si3N4 used as counterpart material. In the case of Si3N4 used as counterpart material, dominant wear mechanism was abrasion.