• Food Science and Preservation
• /
• v.22 no.3
• /
• pp.385-391
• /
• 2015

This study was conducted to develop a spray-dried garlic chives (Allium tuberosum) powder and to evaluate its quality characteristics depending on the treatment of steam blanching pretreatment $100^{\circ}C$, 3 min) and the addition of forming agents (dextrin (DE=10), ${\beta}$-cyclodextrin) during process. The steam blanching pretreatment showed an increase in $L^*$ value while a decrease in $-a^*$, $b^*$, $C^*$, and $h^o$ values of the powder. Moisture content and water soluble index were not affected by the treatment of steam blanching and the addition of forming agents, whereas the particle diameter was the smallest in the steam blanching treatment and dextrin addition. Chlorophyll, phenolic compound, and vitamin C content, and DPPH radical scavenging activity of non-pretreated powder were significantly higher than those of the steam blanching treated powders. However, there was no significant difference between the two forming agents. The sensory acceptability (color, smell, and overall acceptability) of powder treated with steam blanching were significantly higher than those of non-pretreated powders. Therefore, the steam blanching pretreatment of fresh garlic chives affected on the better quality characteristics of the spray-dried powders when compared with non-pretreated powder though it adversely affected the natural chemical quality of fresh garlic chives.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.7 no.2
• /
• pp.26-33
• /
• 2011

To evaluate steam oxidation behaviours of Alloy 617 and Haynes 230, oxidation test were performed at $900^{\circ}C$ in steam and $steam+20\;vol.-%\;H_2$ environments. Oxidation rate in steam condition was similar to that in air for Alloy 617, while it was slightly lower for Haynes 230. When hydrogen was added to steam, oxidation rate was enhanced. Isolated $MnTiO_3$ particle were formed on $Cr_2O_3$ oxide layer and sub layer $Cr_2O_3$ were formed in steam and $steam+20\;vol.-%\;H_2$ for Alloy 617. On the other hands, $MnCr_2O_3$ layer were formed on top of $Cr_2O_3$ oxide layer for Haynes 230. The extensive sub layer $Cr_2O_3$ formation was resulted from the oxygen inward diffusion in such environments. When hydrogen was added, the oxide morphology was changed from polygonal to platelet because of the accelerated diffusion of cations under the oxide layer. In addition, decarburized zone was extended as hydrogen participated into the reactions causing carbide dissolution.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.8
• /
• pp.996-1008
• /
• 1997

This paper describes a methodology and results for the analysis of a small steam injected gas turbine cogeneration system. A performance analysis program for the gas turbine engine is utilized with modifications required for the model of steam injection and the heat recovery steam generator (HRSG). The object of simulation is a simple cycle gas turbine engine under development which adopts a centrifugal compressor. The analysis is based on the off-design operation of the gas turbine and the compressor performance map is utilized. Analyses are carried out with the injection ratio as the main parameter. The effect of steam injection on the power and efficiency of gas turbine and cogeneration capacity is investigated. Also presented is the variation in the main operating parameters inside the HRSG. Remarkable reduction in NOx generation by steam injection is confirmed. In addition, it is observed that for the 100% power operation the temperature of the cooled first nozzle blade decreases by 100.deg. C at full steam injection, which seems to have a favorable effect on the engine life time.

• Journal of the Korean Society of Earth Science Education
• /
• v.7 no.2
• /
• pp.226-233
• /
• 2014

This study is to develop a subject substitute STEAM program which can be applied instead of classes in school field and to seek development plan of a subject substitute STEAM program based on that. The program was developed by experts on science education and teachers who participated in developing STEAM program business conducted by the Korea Foundation for the Advancement of Science and Creativity and one 6th grade located in small and medium city was chosen for application. As a result, the subject substitute STEAM program attracted students' interest and helped to understand for them. In addition, the development plan was found that teachers' participation is very important, an inquiry activity related to real life is to be included and enough activity time is helpful in students' understanding, when developing a subject substitute STEAM program.

• Journal of The Korean Association For Science Education
• /
• v.35 no.4
• /
• pp.665-676
• /
• 2015

In this case study, we analyzed the processes of STEAM lessons conducted by preservice secondary science teachers. Three preservice science teachers at a college of education in Seoul participated in this study. After the workshop for STEAM education, they planned and practiced STEAM lessons. All of the teaching-learning materials were collected before lessons, and their lessons were observed and videotaped. Semi-structured interviews were also conducted before and after their lessons. The processes of STEAM lessons were analyzed while focusing on PCK and PDC. Their difficulties, needs, and views on STEAM education were also studied. It was found that they have taken much efforts to reflect the objectives and characteristics of STEAM education, and prepared teaching-learning materials by searching on the internet and arranging creative contents. Their great difficulty was to determine topics for STEAM lessons. While one preservice teacher satisfied with her lesson perceived STEAM education positively, the others perceived that it would be very difficult to practice STEAM lessons in school. For their STEAM lessons to be successful, the workshop needs to include some specific information on grades, proper topics for each grade, ways of making materials, and tips for effective STEAM lessons. In addition, it will be effective if the workshop is carried out after their study on constructivist learning theory and if they experience successful STEAM lessons.

• Journal of Magnetics
• /
• v.15 no.2
• /
• pp.70-73
• /
• 2010

A magnetic phase is partly produced in a steam generator tube due to stress and heat, because steam generator tubes are exposed to high temperature, high pressure and radioactivity conditions. This adversely affects the safety of steam generator tubes. However, it is difficult to detect it using conventional eddy current methods. Therefore, a new type of probe is needed to separate the signals from the defects and magnetic phases. In this study, a new U-type yoke, which contained two types of coils, a magnetizing coil and detecting coil, was designed. In addition, the signal induced by the magnetic phase and defect in an Inconel 600 plate were simulated.

• Journal of Science Education
• /
• v.43 no.1
• /
• pp.136-156
• /
• 2019

This study examined the effects of STEAM program on preservice science teachers' communication competency and further explored their experiences of and reflection on STEAM program. The study design is one group pretest-posttest with mixed methodology using both quantitative and qualitative data. The STEAM program consists of three stages: introduction of STEAM, participation in STEAM activities, and reflection on the STEAM program. The preservice science teachers improved their communication competency after the STEAM program (p < .01). The preservice science teachers represented statistically higher scores on the three subscales of communication competency: Interpretation ability, self-presenting ability, and understanding others' viewpoints. In addition, the preservice science teachers reflected on their STEAM experiences. During the first stage of 'Presentation of the Problem Situation,' the preservice science teachers mentioned that they roused their curiosity due to everyday experience-related, social issues or present issues. In the stage of 'Creative Design,' the preservice science teachers mentioned that they selected the final idea through mutual consent of the members, the practical possibility of everyday life, the previous experience-based decisions, or persuasive power. Further, about 87.5% of preservice science teachers mentioned that they were fully engaged in the 'Emotional Learning' stages due to the application of integrated thinking, everyday related issues, and communication among group members. About 85% of the preservice science teachers mentioned that they could challenge new problems in future situations.

• International Journal of Concrete Structures and Materials
• /
• v.4 no.1
• /
• pp.9-15
• /
• 2010

Silica fume is a common addition to high performance concrete mix designs. The use of silica fume in concrete leads to increased water demand. For this reason, Florida Department of Transportation (FDOT) allows only a 72-hour continuous moist cure process for concrete containing silica fume. Accelerated curing has been shown to be effective in producing high-performance characteristics at early ages in silica-fume concrete. However, the heat greatly increases the moisture loss from exposed surfaces, which may cause shrinkage problems. An experimental study was undertaken to determine the feasibility of steam curing of FDOT concrete with silica fume in order to reduce precast turnaround time. Various steam curing durations were utilized with full-scale precast prestressed pile specimens. The concrete compressive strength and shrinkage were determined for various durations of steam curing. Results indicate that steam cured silica fume concrete met all FDOT requirements for the 12, 18 and 24 hours of curing periods. No shrinkage cracking was observed in any samples up to one year age. It was recommended that FDOT allow the 12 hour steam curing for concrete with silica fume.

• Nuclear Engineering and Technology
• /
• v.54 no.8
• /
• pp.3140-3153
• /
• 2022

A numerical feasibility study was conducted to investigate the thermal-hydraulic characteristics of a steam generator with corrugated plates for a small modular reactor. Accordingly, a one-dimensional thermal-hydraulic analysis code was developed based on the existing state-of-the-art thermal-hydraulic models and correlations for corrugated plate heat exchangers. Subsequently, the pressure loss, heat transfer, and instability characteristics of the steam generator with corrugated plates were investigated according to the chevron angle and mass flux. Additionally, the characteristics of rectangular and disk-type corrugated plate steam generators with equivalent heat transfer areas were analyzed. The steam generator with disk-type corrugated plates exhibited better performance in terms of pressure loss and heat transfer rate than the rectangular type. In addition, when the mass flux decreased from the onset of boiling points, reverse gradients of the total pressure change were observed in both types. Thus, it was confirmed that Ledinegg instability could occur in the steam generator with corrugated plates. However, it was dependent on the chevron angle, and the optimal chevron angle to minimize instability was 45° under the conditions of the present analysis.

• Journal of the Korean Society of Earth Science Education
• /
• v.7 no.1
• /
• pp.75-90
• /
• 2014

The purpose of this study was to explore the characteristics of STEAM program developed and implemented by two docents and its educational impact for the use of natural history museum. Two docents developed this program with the help of science educators who ran five times of workshop during five months. The STEAM program implemented in the natural history museum demonstrated the following characteristics. The exhibitions in museum were reached by visitors only for learning science concepts (S) out of five components in STEAM. The other components, T (technology) and E (engineering), were delivered through lectures in the room, not exhibition hall. M (Mathematics)was achieved by guessing the animal's size, or calculating the walking or running speed with the clue of foot prints. The three phases of STEAM program (presentation of context, creatively design the investigation, and emotional touch) were explicitly implemented but partially successful. Two docents participating in this study responded that they formed new or extended the understandings about STEAM education, but they had the difficulties in implementing STEAM program for various type of visitors. All visitors who participated in this study displayed the favorable responses in educational impact by STEAM program in natural history museum. The heavier emphasis on E and T of STEAM program is recommended through community-based learning. In addition, educator professional program through which docents can bridge theory into practice is suggested for revitalization of STEAM education.