• Corrosion Science and Technology
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• 제18권4호
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• pp.138-147
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• 2019

Pipes and components of the secondary system in the pressurized water reactor (PWR) are mainly comprised of manufactured carbon steel. Thus, the generated carbon steel corrosion products are transported into the steam generator and deposited, thereby deteriorating the integrity of the steam generator. Environmental condition in the secondary system of the PWRs differs across different locations. So, the corrosion rate and types of corrosion products depend on specific locations in the secondary system. In this study, the quantity and chemical compositions of corrosion products generated in various locations that vary in different temperatures and chemistry conditions were investigated. As a result of evaluating the PWR "Unit A" that is in current operation, the amount of corrosion products generated in the section of high temperature feedwater system was identified as the largest source in the secondary system. Major components of corrosion products were iron oxides such as magnetite, hematite, and lepidocrocite.

• 농업과학연구
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• 제49권2호
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• pp.331-339
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• 2022

Deforestation and conservation of coniferous forest have been recognized as critical issues in Korea due to climate change. The main purpose of this research was to monitor changes of secondary metabolite contents and growth of Korean fir (Abies koreana) according to the temperature change in Mt. Halla. The Korean fir located at three different regions, Yeongsil, Witseoreum, and Jindallaebat, was monitored in April, July, and October from 2016 to 2018 and secondary metabolites, specifically lutein, α-carotenoid, and β-carotenoid, were analysed with high performance liquid chromatography. The results showed that average concentrations of lutein, α-carotenoid, and β-carotenoid were 0.82 - 23.30, 0.02 - 2.01, and 0.11 - 2.84 ㎍·g-1 and the highest concentration of secondary metabolite was observed in October compared to April and July. The average length and width of Korean fir in the three regions were 11.84 - 20.70 and 1.78 - 2.41 mm from 2016 - 2018. A correlation analysis showed that the concentrations of all three secondary metabolites were negatively correlated with temperature and a significant difference was observed between temperature and lutein concentration in Korean fir. Overall, growth and production of secondary metabolites in Korean fir highly depended on the temperature, and global warming thus might have an adverse effect on the growth and physiological changes of Korean fir in Mt. Halla.

• 천문학회보
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• 제41권2호
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• pp.66.3-67
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• 2016

The Giant Magellan Telescope (GMT) will feature two interchangeable Gregorian secondary mirrors, an adaptive secondary mirror (ASM) and a fast-steering secondary mirror (FSM). The FSM has an effective diameter of 3.2 m and built as seven 1.1 m diameter circular segments, which are conjugated 1:1 to the seven 8.4m segments of the primary. Each FSM segment contains a tip-tilt capability for fine co-alignment of the telescope subapertures and fast guiding to attenuate telescope wind shake and mount control jitter. This tip-tilt capability thus enhances performance of the telescope in the seeing limited observation mode. As the first stage of the FSM development, KASI conducted a Phase 0 study to develop a program plan detailing the design and manufacturing process for the seven FSM segments. The GMTO-KASI team matured this plan via an internal review in May 2016 and the revised plan was further assessed by an external review in June 2016. In this poster, we present the technical aspects of the FSM development plan.

• 한국약용작물학회지
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• 제12권2호
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• pp.163-170
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• 2004

Secondary phenolic metabolites play an important role in plant defense mechanisms, and increasing evidence indicates that many phenolic compounds are important in human health. To date, few studies have investigated the impact of various medicinal plants on levels of secondary plant metabolites. To address this issue, 82 species of Korean medicinal plants were screened to determine their resveratrol contents. Among 82 medicinal plants, 5 species such as Gardenia jasmonoides, Phlomis umbrosa, Rheum palmatum L., Polygala tenuifolia, Rubus chingii HU contained relatively high concentrations of resveratrol $(179.75{\sim}42.71\;{\mu}g/g)$. But, 40 species including Adenophora triphylla var. japonica HARA were only observed low concentrations or trace of resveratrol, and 20 species including Alpinia officinarum HANCE did not contain a resveratrol.

• 한국지구과학회지
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• 제38권5호
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• pp.367-377
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• 2017

The purpose of this research is to investigate characteristics of science content knowledge and pedagogical content knowledge shown in the primary school science classes. Through analysis of classroom teaching, explore the features and differences between primary and secondary school science PCK. Using open-ended interviews with the teachers and group discussions on a regular basis to analyze and compare classes of five primary school teachers, the relationship between CK and PCK. Regardless of the school level the teacher's PCK and professionalism is required with varying focus and emphasis. The features of the primary school teacher's PCK are as follows: Firstly, elementary teach secondary teach content, teachers value pedagogical knowledge (PK) content knowledge (CK). The primary school PCK requires more of understanding of students and teaching methods that to subject areas. PCK be without content knowledge, and the teacher's PCK is subject-specific In addition to the characteristics of PCK in the primary school science teaching, ways to set up professional exchange or collaboration between primary and secondary teachers, and to provide supplementary in-service training focused on content knowledge for primary school teachers.

• Nuclear Engineering and Technology
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• 제3권3호
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• pp.129-140
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• 1971

3.25% 규소를 함유하는 규소강을 융해·합금하고 압연·열처리하여 연질 자심재료로서 응용범위가 넓은 방향성 규소강판을 제조·실험했다. 이 연구에서는 잉고트 중의 망간 및 유황함량, 탄화물 석출과 유관한 열간압연 직후의 열처리조건, 2차 냉간 압연율 등이 2차 재결정 및 집합조직에 미치는 영향을 다루었다. 그 중에서도 특히 2차 냉간 압연율이 2차 재결정과 관련한 각종 활성화 에너지와 집합조직에 미치는 영향을 중점적으로 구명하였다. 2차 냉간 압연율이 10%인 시편은 응력 병형의 도입으로 인한 결정입계 이동으로 결정립성장 만이 관찰되었으며 핵생성을 동반한 2차 재결정은 일어나지 않았다. 2차 냉간 압연율이 30%인 시편에서는 2차 재결정을 위한 핵생성만 있었으며 2차 재결정이 완전히는 일어나지 않았다. 이 실험 조건하에서 50%의 2차 냉간압연율이 2차 재결정을 일으키기에 최적 냉간 압연율이며 가장 높은 직접도를 얻을 수 있는 압연율이었다.

• 한국농림기상학회지
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• 제7권4호
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• pp.258-264
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• 2005

The objectives of this study were to study 1) emergence of pine bark beetles, 2) larval density in residual timber on Idlest land by each felling season, and 3) the secondary damage rates in the tended forest. Pine forest land which had undergone tending had a higher secondary damage ratio $(59.6\%)$ by pine bark beetles than forest land that was not tended $(2.8\%)$. The number of escape holes averaged 11.3 0.31 per $250 cm^2$ on the bark of leaf trees in the tended forest. The number of escape holes was higher in the Jinju site than in the Hamyang site. The larval habitat density of pine bark beetles as compared with each felling period was higher after mid-October than in forests tended early in October. Thus, forests should be tended before early October in order to prevent secondary damage from pine bark beetles. Secondary damage in the tended forest was higher in the upper part $(75.5\%)$ of the tree crown than in the lower part $(49.2\%)$. The damage was higher in terminal shoots $(80\%)$ than in lateral shoots $(48\%)$. Therefore, secondary damage by pine bark beetles can cause deterioration of the elongation growth of the forest trees. In conclusion, if by-products of tended pine forest forests are neglected, they will be utilized as a propagation site for pine bark beetles (Blastophagus piniperda L). The propagated adults will damage the tender shoots of the leaf trees and thus seriously limittheir elongation.

• Journal of Plant Biotechnology
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• 제3권2호
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• pp.45-57
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• 2001

Trees have the ability to undergo secondary growth and produce a woody body. This tree-specific growth is affected by the secondary vascular system and the developmental continuum of secondary phloem and xylem. Secondary growth is one of the most important biological processes on earth. Considering its economic and environmental significance, our knowledge of tree growth and development is surprisingly limited. Trees have received little attention as model species in plant science, as most Plant biology questions can be best addressed by using herbaceous model species, such as Arabidopsis. Furthermore, tree biology is difficult to study mainly due to the inherent problems of tree species, including large size, long generation time, large genome size, and recalcitrance to biotechnological manipulations. Despite all of this, one must rely on trees as models to study tree-specific questions, such as secondary growth, which cannot be studied effectively in non-woody model species. Recent advances in genomics technology provide a unique opportunity to overcome these inherent tree-related problems. Several groups, including our own, have been successful in studying the biology of wood formation with a variety of hardwood and softwood species. In this article, 1 first review the current understanding of tree growth and then discuss the recent attempts to fully explore and realize the potential of molecular biology as a tool for enhanced understanding of secondary growth.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.111-125
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• 2013

Among the hazardous air pollutions(HAPs), characteristics of secondary organic aerosols are not well understood. In this study, the current state for the measurement and analysis of representative secondary PAHs such as oxy-PAHs and nitro-PAHs are presented with the discussion of their toxicity. Also, further research directions for the secondary PAHs are suggested. It was found that the chemical reaction mechanisms and products of PAHs in the air are poorly identified and their toxicities are not well studied. Moreover ambient concentrations of those secondary PAHs are not well documented. Sampling methodologies of those secondary PAHs are similar with PAHs but the analytical protocols for those secondary PAHs are more complicated than PAHs. Future management directions are suggested along with future research directions.

• The Journal of Asian Finance, Economics and Business
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• 제8권10호
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• pp.259-267
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• 2021

Both structural transformation and education are the predominant subjects in the literature of development economics. This study examines the relationship between education before the tertiary level and the structural transformation of provinces by using Vietnam as a case study. In this study, education before the tertiary level would be disaggregated into three groups: primary, lower secondary, and upper secondary, then analyzed simultaneously on three-panel data models. Research data is taken from the statistical yearbook of provinces in Vietnam for 2015-2018. Research results show that education before the tertiary level plays a vital role in structural transformation. The enrolment rate of various education levels has a different influence on economic structure, and the lower secondary level has more significant effects than the upper secondary level. This reflects that participating in lower secondary is a fundamental requirement for taking some jobs in the non-agriculture sector, while upper secondary helps to upgrade the learner's abilities to respond to higher requirement jobs. The high rate of repeaters in upper secondary education will slow down the structural shift towards non-agriculture, and changing the traditional attitude about repeaters plays an essential role in improving this rate.