• Journal of Aerospace System Engineering
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• v.1 no.1
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• pp.45-52
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• 2007

This paper analyzed the extension effects of fatigue life and the application of pre-indentation in aircraft structural material such as aluminum alloys. The test specimen used the thin sheet of aluminum alloy with a single-edged notch. The experiments were conducted after making the pre-crack under a constant amplitude loading. As the fatigue life extension technique, the pre-indentation making an indent on the predicted path of crack propagation was applied. The work presented here discussed about a proper mathematical relation between crack growth rate and the range of stress intensity factor and about the generalization of crack growth mechanism with large retardation effect. A technique to enhance the applicability of pre-indentation if also mentioned.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.78-83
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• 2000

본 논문은 영광 1호기 원자력발전소를 기준발전소로 하여 개발된 PRE-MARK 소개 및 PRE-MARK을 기반으로 개발된 노심모델의 결과를 제시하고자 하는 것을 주된 목적으로 하고 있다. 노심 모델개발에는 REMARK 모델 프로그램을 기반으로 개발된 PRE-MARK를 이용하였으며, PRE-MARK의 주요 특징으로는 노심모델 입력자료를 노심설계코드 및 Lattice코드로부터 자동으로 생성하며 GUI 기반으로 변경된 REMARK으로 입력하여 노심모델을 구동함과 동시에 실시간으로 중요 변수의 현재 값들을 그래프로 도시해줌으로 조율 (Tuning) 상수를 용이하게 결정할 수 있도록 하는 것이다 또한 BOL 및 EOL에서 HFP 평형 Xenon 조건에서의 제어봉 위치에 따른 제어봉가(Rod worth)를 영광 1호기 12주기 NDR(Nuclear Design Report)과 비교하고, 원자로정지 이후 BOL, MOL 및 EOL에서의 시간에 따른 Xenon의 반응도 영향을 비교함으로 개발된 모델의 건전성을 입증하였다.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.440-447
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• 2003

Up until today, the key to contouring has been resumed in these two alternatives, either limiting the adipocyte storing capacity by modulating lipogenesis, or by stimulating lipolysis to eliminate adipocyte lipid content. Another interesting way could be the regulation of adipocyte differentiation. In this work, we have evaluated the effect of a brown algal extract of Sphacelaria scoparia (SSE) on the differentiation of pre-adipocytes into adipocytes. A pre-adipocyte line (3T3-L 1) was used. The differentiation was evaluated by the measure of produced lipids thanks to red oil coloration and spectrophotometry, and also by the expression of adipocyte differentiation markers: enzymes such as fatty acid synthase (FAS) and stearoyl CoA desaturase (SCD), or membrane proteins such as glucose transporters (GLUT -4) and fatty acid transporters (FAT) expressed on the surface of human adipocytes. These genes are under control of two transcription factors: CAAT-enhancer binding protein (c/EBP alpha) and sterol response element binding protein (SREBP1). All these markers were analysed at different stages of differentiation by RT -PCR. Sphacelaria extract (SSE) inhibits pre-adipocytes differentiating into adipocytes following a dose-dependant relation, using a kinetics similar to retinoic acid. It decreases the expression of mRNA specific to FAS, FAT, GLUT -4, SCD1, c/EBP alpha and SREBP1. Moreover, SSE regulated on collagen 1 and collagen 4 expression. A stimulation of collagen 1 was also measured in human skin fibroblasts. Thus, SSE performs as a genuine differentiation inhibitor and not only as a lipogenesis inhibitor, and could be used in slimming products.

• Journal of Korean Elementary Science Education
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• v.37 no.1
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• pp.54-65
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• 2018

The purpose of this study was to investigate the characteristics of lesson planning of pre-service elementary teachers to develop scientific communication skills for elementary school students. For this purpose, lesson plans and lesson planning journals written by the 53 pre-service teachers were collected and analyzed. The results of the research were as follows. The pre-service elementary teachers used an implicit and contextual approach to develop scientific communication skills. Teaching and learning activities for enhancing scientific communication were mainly conducted in words or in writing. There were many activities expressing elementary school students' thoughts and presenting the results of experiments in the lesson plan. There were many cases in which the pre-service teachers' lesson plans did not include the evaluation of scientific communication skills. In their lesson plans, there are a lot of mutual activities between teachers and students, team and whole students, and inter-students within teams together, and students' individual activities from requests of teachers. We found that the pre-service teachers had various difficulties when they planned the science lesson to develop scientific communication skills. The pre-service teachers were less likely to refer to specialized materials related to science education when planning their classes.

• Natural Product Sciences
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• v.22 no.1
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• pp.20-24
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• 2016

Pentacyclic triterpenes, mainly, asiatic acid, madecassic acid, asiaticoside, and madecassoside are the active constituents of Centella asiatica. A pentacyclic triterpene enriched C. asiatica extract (PRE) was prepared and standardized to contain a total pentacyclic triterpenes not less than 65% w/w. This work was focused on determination of antiinflammatory, antioxidant, and tyrosinase inhibitory activities of PRE and its stability. The PRE exhibited a satisfactory nitric oxide inhibitory effect, with an $IC_{50}$ value of $64.6{\mu}g/mL$. In addition, the PRE inhibited tyrosinase enzyme activity with an $IC_{50}$ value of $104.8{\mu}g/mL$. In contrast, the PRE possessed only weak antioxidant activity. The PRE was stable over a period of four months when stored as a dried powder but only in a well-closed container protected from light at $4^{\circ}C$. An aqueous alcoholic solution of the PRE was stable at pH values of 5.8 and 7.0, but was not stable at a pH of 8.2. Preparations of the PRE in an aqueous solution should be performed in acidic or neutral conditions.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.38.3-39
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• 2009

Equatorial Plasma Bubble (herafter, EPB) is a common feature in low-latitude F-region during the night time. Since EPB causes significant impacts on the satellite communication and navigation systems, its accurate forecast is highly demanded by the GNSS users. Thus, further understanding of these features and their configuration is a challenging issue in space weather studies. The day-to-day variability of the plasma bubble activity was investigated by analyzing the TIMED/GUVI, ROCSAT-1, DMSP, and CHAMP satellite data. The pre-reversal enhancement (PRE) is known as the most important single parameter for the onset of plasma bubbles but we do not know yet to what extent the day-to-day variability of the bubble activity can be attributed to the PRE. We obtained the magnitude of the PRE from ROCSAT-1 and the occurrence of bubbles in relation to the PRE was investigated by using the coincident observations of EPBs from TIMED/GUVI, DMSP, and CHAMP. By conducting one-to-one comparison of the PRE characteristics with the EPB occurrence we examined the role of the PRE in the onset of EPBs.

• Food Science and Preservation
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• v.6 no.1
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• pp.1-6
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• 1999

Fresh gingers, harvested in Seosan, Choongcheongnam-do, were pre-treated by a washing-pasteurizing-drying process, a curing process, and non-treated, respectively. Then they were stored in a lab-scale storage room(12$^{\circ}C$, >92%RH) to investigate the effect of pre-treatment methods on the quality changes during long-term storage. Weight loss of ginger during storage showed ranges in 0.7∼4.3%, and the weight of gingers pre-treated by washing-drying process showed a tendency to change less than those treated by curing. After storage of 130 days, spoilage rates were about 20% in non-treated, 11% in curing treated, and 12% in washing-drying treated ginger,, showing the effect of pre-treatment. The final rate of sprouting was 13∼15% regardless of treatment methods. The firmness of gingers showed a tendency to decrease in stored ginger for the longer period; however, the values were ranged from 1,200 to 1,400 g/$\textrm{cm}^2$, that is hard enough to show a marketable quality. The contents of reducing sugar showed a tendency to increase with the lapse of storage time.

• The Korean Journal of Food And Nutrition
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• v.33 no.1
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• pp.1-8
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• 2020

The purpose of this study was to prevent excessive softening of seasoned spinach by heating and freezing through the pre-heating treatment in calcium chloride solution. The pre-heating temperature was set at 60℃, which supports the highest activity of pectinesterase around 60℃. Pre-heating spinach in calcium solution does not affect the chromaticity characteristics of spinach leaves and significantly improves its texture compared to conventional blanching only and pre-heating in water. The improvement of the firmness is related to the formation of strongly cross-linkages between carboxyl groups and Ca²⁺ by the action of the pectinesterase in spinach. For reheated spinach, the firmness of calcium chloride treated stems were 37.80~44.44 kg, and the control was 28.73 kg. The firmness of calcium chloride treated leaves was 19.73~40.79 kg, and the control was 9.63 kg. Additionally, the total aerobic bacteria in the fresh samples were 3.25~3.99 log CFU/g and 1.97~2.72 log CFU/g in the reheated samples. And the total coliform was not detected in the reheated samples. Considering the color, texture, microbial characteristics and taste quality, the optimum pre-treatment conditions to prevent excessive softening of spinach were 3% calcium chloride solution and 15minutes of treatment.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.122-128
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• 2018

Purpose: To investigate positional uncertainty and its correlation with clinical parameters in spine stereotactic body radiotherapy (SBRT) using thermoplastic mask (TM) immobilization. Materials and Methods: A total of 21 patients who underwent spine SBRT for cervical or upper thoracic spinal lesions were retrospectively analyzed. All patients were treated with image guidance using cone beam computed tomography (CBCT) and 4 degrees-of-freedom (DoF) positional correction. Initial, pre-treatment, and post-treatment CBCTs were analyzed. Setup error (SE), pre-treatment residual error (preRE), post-treatment residual error (postRE), intrafraction motion before treatment (IM1), and intrafraction motion during treatment (IM2) were determined from 6 DoF manual rigid registration. Results: The three-dimensional (3D) magnitudes of translational uncertainties (mean ${\pm}$ 2 standard deviation) were $3.7{\pm}3.5mm$ (SE), $0.9{\pm}0.9mm$ (preRE), $1.2{\pm}1.5mm$ (postRE), $1.4{\pm}2.4mm$ (IM1), and $0.9{\pm}1.0mm$ (IM2), and average angular differences were $1.1^{\circ}{\pm}1.2^{\circ}$ (SE), $0.9^{\circ}{\pm}1.1^{\circ}$ (preRE), $0.9^{\circ}{\pm}1.1^{\circ}$ (postRE), $0.6^{\circ}{\pm}0.9^{\circ}$ (IM1), and $0.5^{\circ}{\pm}0.5^{\circ}$ (IM2). The 3D magnitude of SE, preRE, postRE, IM1, and IM2 exceeded 2 mm in 18, 0, 3, 3, and 1 patients, respectively. No association were found between all positional uncertainties and body mass index, pain score, and treatment location (p > 0.05, Mann-Whitney test). There was a tendency of intrafraction motion to increase with overall treatment time; however, the correlation was not statistically significant (p > 0.05, Spearman rank correlation test). Conclusion: In spine SBRT using TM immobilization, CBCT and 4 DoF alignment correction, a minimum residual translational uncertainty was 2 mm. Shortening overall treatment time and 6 DoF positional correction may further reduce positional uncertainties.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.71-78
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• 2015

This study was performed to optimize the integrated thermal-alkali pre-treatment of flotation scum for the enhanced biodegradability. The optimum conditions of the integrated thermal-alkali pre-treatment were obtained using response surface methodology. The disintegration degree of carbohydrate (69.2%) and protein (57.3) were estimated under the optimum conditions. Although the optimum conditions were different, the disintegration degrees were similarly. A fermentative hydrogen batch test was conducted to evaluate the hydrogen production from scum with and/or without. The maximum hydrogen production from scum with pre-treatment was of 0.64 mol H2/mol hexoseadded, which about 1.4 times higher than without pre-treatment.