• 한국재료학회지
• /
• 제13권5호
• /
• pp.297-302
• /
• 2003

The effects of risering design and alloying element on the formation of defects such as external depression, primary and secondary shrinkage cavity in gray cast iron were investigated. Two types of risering design for the cylindrically step-wise specimen, No. 1(progressive solidification) and No. 2(directional solidification) risering designs, were prepared and five different alloy compositions were casted. In the No. 1 risering design, external depression or primary shrinkage cavity due to liquid contraction was observed in all the specimens from ISO 150 to ISO 350. The primary shrinkage cavity was located right under the top surface or connected to the top surface, and was characterized by smooth surface. Its size increased with an increase in ISO number. However, neither secondary shrinkage cavity nor swollen surface was observed in all the castings. In the No.2 risering design, neither primary shrinkage cavity nor secondary shrinkage cavity was observed in all the specimens due to proper risering design. A swollen surface was also not observed in all the castings with the application of pep-set mold.

• 한국공작기계학회논문집
• /
• 제17권5호
• /
• pp.52-57
• /
• 2008

Most of the electrons emitted from the filament, are captured by the anode. The portion of the electron current that leaves the gun through the hole in the anode is called the beam current. Electron beam probe is called the focused beam on the specimen. Because of the lenes and aperture, the probe current becomes smaller than the beam current. It generate various signals(backscattered electron, secondary electron) in an interaction with the specimen atoms. Backscattered electron provide an useful signal for composition and local specimen surface inclination. Secondary electron is used far the formation of surface imagination. The steady electron beam probe is very important for the imagination formation and the brightness. In this paper, we show the results of developed elements that create electron beam probe and the measured beam probe in various acceleration voltages by Faraday cup. These data are used to analysis and improve the performance of the system in the development.

• 대한공업교육학회지
• /
• 제42권1호
• /
• pp.106-124
• /
• 2017

이 연구는 초 중등 발명 지식재산교육의 목표 및 교육과정에 대한 적정 편성 방안을 도출하기 위하여 전문가 대상으로 2차 델파이 조사를 실시하였다. 이를 통한 연구의 결론은 다음과 같다. 첫째, 이 연구에서 제안한 학교급별 발명 지식재산교육의 핵심 목적은 타당한 것으로 나타났다. 핵심 목적은 초등학교가 '발명 인식과 태도 함양'(M=4.5), 중학교가 '발명 과정과 기법 이해'(M=4.2), 일반계고가 '발명 기법 적용 및 평가'(M=4.1), 특성화고가 '직무 발명 이해와 적용'(M=4.6)으로 나타났다. 학교급별 교육목적 및 목표도 타당한 것으로 분석되었다. 둘째, 이 연구에서 제안한 초 중등 발명 지식재산교육의 핵심 학습요소에 대한 적정 편성 방안은 선행문헌의 편성 실태와 대동소이하게 나타났으나, 학교급별 발명 지식재산교육의 목적 및 목표에 따른 각 학습요소의 편성 비중은 전반적인 개선이 필요한 것으로 나타났다. 초등학교와 중학교의 경우 발명의 기본적인 학습요소(발명의 이해(A), 창의성 이해와 활동(B), 문제 인식과 활동(C), 문제해결과 활동(D), 발명 융합 지식(E), 발명 기법과 실제(F))에 집중하여 편성하고(73.2%, 65.1%), 고등학교는 초 중학교에서 집중했던 기본 학습요소의 비중을 낮추며(51.0%) 발명과 진로(H), 특허 출원(K) 등 발명과 연계되어 확장된 학습요소들의 비중을 높여 편성하는 것이 적정한 것으로 분석되었다. 셋째, 초 중등 발명 지식재산교육 체계는 학교급별 발명 지식재산교육의 목적 및 목표를 지향점으로 설정하고, 이를 달성하기 위해 핵심 학습요소는 계속성, 계열성, 통합성 등 타일러(Tyler)의 학습조직 원리에 근거하여 학교급별로 적정 편성 방안을 구축해야 한다. 특히 특성화고는 초 중학교뿐만 아니라 일반계고와의 차별화가 필요하며 직무 발명 이해와 적용을 위한 중등 단계 직업교육에서의 발명 지식재산교육체계 구축이 필요하다.

• Journal of Applied Biological Chemistry
• /
• 제51권3호
• /
• pp.83-87
• /
• 2008

Tension wood, a specialized tissue developed in the upper side of the leaning stem and drooping branches of angiosperm, is an attractive experimental system attractive for exploring the development and the biochemical pathways of the secondary cell wall formation, as well as the control mechanism of the carbon flux into lignin, cellulose, and hemicellulose. However, the mechanism underlying the induction and the development of the tension wood is largely unknown. Recently, several researchers suggested the possible roles of the plant growth hormones including auxin, gibberellin, and ethylene mainly based on the expression pattern of the genes in this specialized tissue. In addition, expressed sequence tag of Poplar and Eucalyptus provide global view of the genetic control underlying the tension wood formation. However, the roles of the majority of the identified genes have not yet been clearly elucidated. The present review summarized current knowledge on the biosynthesis of tension wood to provide a brief synopsis of the molecular mechanism underlying the development of the tension wood.

• 한국분무공학회지
• /
• 제4권1호
• /
• pp.13-18
• /
• 1999

It has been known that spray characteristics have an important effect on the mixture formation and directly influence the engine performances and the emissions. Up to now, the measurement of droplet size is well developed such as PDPA and PMAS though the behavior of small droplets during secondary atomization is not clear. Particle image velocimetry(PIV), a planar measuring technique, is a very efficient tool for studying complicated behavior and a fast and reliable method to track numerous droplets during injection. In this study, two-color scanning PIV is designed to obtain quasi-instantaneous two dimensional velocity data by using he-ion laser, rotating mirror and beam splitter. This PIV method which has high temporal and spatial resolution provides the information about the small complex droplet behavior.

• 한국세라믹학회지
• /
• 제36권10호
• /
• pp.1056-1061
• /
• 1999

Phase formation and oxygen ion conduction of La(Ba)Ga(Mg)O3-$\delta$ system was studied, BaLaGa3O7 and BaLaGaO4 formed as a secondary phase above the solubility limit of Ba2+ in La3+ sites. The oxygen ionic conductivity of La(Ba)Ga(Mg)O3-$\delta$ was 0.1 S/cm 80$0^{\circ}C$ The activation energy of the oxygen ion conduction was dependent on temperature. This value was higher at low temperature than at high temperature.

• BMB Reports
• /
• 제42권4호
• /
• pp.189-193
• /
• 2009

During development lymphoid tissue inducer (LTi) cells are the first hematopoietic cells to enter the secondary lymphoid anlagen and induce lymphoid tissue neogenesis. LTi cells induce lymphoid tissue neogensis by expressing a wide range of proteins that are associated with lymphoid organogenesis. Among these proteins, membrane-bound lymphotoxin (LT) $\alpha1\beta2$ has been identified as a critical component to this process. LT$\alpha1\beta2$ interacts with the LT$\beta$-receptor on stromal cells and this interaction induces up-regulation of adhesion molecules and production of chemokines that are necessary for the attraction, retention and organization of other cell types. Constitutive expression of LT$\alpha1\beta2$ in adult LTi cells can result in the formation of a lymphoid-like structure called tertiary lymphoid tissue. In this review, we summarize the function of fetal and adult LTi cells and their involvement in secondary and tertiary lymphoid tissue development in murine models.

• 조명전기설비학회논문지
• /
• 제26권11호
• /
• pp.62-74
• /
• 2012

This paper proposes a new secondary battery charger/discharger available for zero voltage discharge which is used for test equipments and formation process. The proposed system is a switching type converter, and thus the system is high efficiency and more compact as compared with linear type charger/discharger. Conventional switching type charger/discharger can not discharge secondary batteries to zero voltage because of voltage drops in the switching elements and long distributing line(typically 10m). However, the proposed system is able to discharge the battery to zero voltage in constant current mode regardless of the voltage drops. In this paper, we analyze the proposed charger/discharger and the validity of the system is verified by simulation and experiment.

• Asian Journal of Atmospheric Environment
• /
• 제3권1호
• /
• pp.42-51
• /
• 2009

Saturated n-dicarboxylic acids ($C_2-C_7$, $C_9$), unsaturated dicarboxylic acids (maleic, fumaric, phthalic acid), ketocarboxylic acids (pyruvic, glyoxylic acid), and dicarbonyls (glyoxal, methylglyoxal) were determined in size-segregated samples with a high-volume Andersen air sampler at a suburban site in Saitama, Japan, May 12-17 and July 24-27, 2007 and January 22-31, 2008. The seasonal average concentrations of these detected organic acids were 670 $ng/m^3$, accounting for about 4.4-5.7% (C/C) of water-soluble organic carbon (WSOC) and 2.3-3.6% (C/C) of organic carbon (OC). The most abundant species of dicarboxylic acids was oxalic acid, followed by malonic, phthalic, or succinic acids. Glyoxylic acid and methyglyoxal were most abundant ketocarboxylic acid and dicarbonyl, respectively. Seasonal differences, size-segregated concentrations, and the correlations of these acids with ambient temperatures, oxidants, elemental carbon (EC), OC, WSOC, and ionic components were also discussed in terms of their corresponding sources and possible secondary formation pathways. The results suggested that photochemical reactions contributed more to the formation of particulate organic acids in Saitama suburban areas than did direct emissions from anthropogenic and natural sources. However, direct emissions of vehicles were also important sources of several organic acids in particles, such as phthalic and adipic acids, especially in winter.

• 한국대기환경학회:학술대회논문집
• /
• 한국대기환경학회 2010년도 춘계학술대회 논문집
• /
• pp.232-236
• /
• 2010