광릉늑대거미 (Arctosa kwangreungensis) 배후발생과정의 조직 미세구조 분석

양성찬,문명진,Yang, Sung-Chan,Moon, Myung-Jin 한국현미경학회 2012 Applied microscopy Vol.42 No.1

배회성거미류의 배후발생과정에서 형태적 분화가 행동학적 특성으로 발현되는 기전을 규명하기 위하여 광릉늑대거미(Arctosa kwangreungensis) 후기배아와 각 발생 단계의 유충을 실험재료로 그 조직학적 및 미세구조적 변화를 광학 및 주사전자현미경으로 분석하였다. 난황주머니를 가진 후기배아는 부속지의 근육조직과 신경절의 미분화로 비활성상태를 유지하며, 시각기의 신경절과 신경의 발달도 미약하였다. 제1령 유충의 두흉부에서는 미분화된 세포집단이 관찰되고 체색의 발현과 복부신경절의 분화가 현저하였다. 먹이 활동을 시작하는 제2령 유충의 중추신경계에는 신경섬유가 급격히 증가되었고, 성체와 유사한 부속지의 분절구조와 시각기의 조직학적 체제가 확립되었다. 제3령 이후의 유충들은 탈피를 거듭하여 두흉부에서 중추신경계가 차지하는 영역이 축소되었고 독선과 근육조직, 그리고 결합조직등의 활발한 분화가 진행되었다. 먹이활동을 시작하는 제2령 유충 단계에서 부속지와 시각기의 조직학적 발생과 이를 통제하는 신경계의 분화가 완료되는 것으로 미루어, 섭식환경이 배후발생과정을 조절할 수 있으며, 특히 시각과 부속지에 의존하여 먹이를 포획하는 배회성거미류의 행동 습성이 형태조직학적 분화와 연관되어 있음을 확인할 수 있었다. Histologic and microstructural changes during the postembryonic development of the wolf spider Arctosa kwangreungensis were studied using light and scanning electron microscopy to examine the relationship between a morphological differentiation and behavioral properties. The postembryo with abdominal yolk sac was stayed inactive in the egg case because its muscular and visual systems were not fully developed to a functional level. The first instar spiderlings, developed from the postembryo by a first molting process, started to exhibit its pigmentation on their body cuticles. In particular, undifferentiated cell clusters of central nervous system (CNS) were densely distributed within the cephalothorax, and highly differentiated abdominal ganglion was observed. They had a characteristic visual system looks more like its adult counterpart, and had segmented appendages looks more like the tiny spiders containing well oriented muscular system. After 3rd instar, spiderlings grew more rapidly with accordance to their consistent growth and periodical molting processes. Thus, the relative area of CNS with respect to cephalothorax was gradually decreased, instead a pair of venom glands, musculature, and connectives occupied the residual area. It has been revealed that the early development of spider can be controled by the feeding condition of larval period, since histologic and microstructural differentiations in both appendages and optic system were completed at the second instar. In particular, behavioral properties of the wandering spiders that depend on vision and their running ability were deeply related to physiological differentiation of the microstructural development.

A generality in stress development of silica/poly(vinyl alcohol) mixtures during drying process

Kim, Sunhyung,Sung, Jun Hee,Lim, Sanghyuk,Ahn, Kyung Hyun Elsevier 2015 Progress in organic coatings Vol.88 No.-

<P><B>Abstract</B></P> <P>Colloidal dispersions in polymer solution are important material systems in coating and printing applications. Understanding the role of polymers in drying process is important to obtain the desired performance of the solid film. In this study, we investigated the role of polymers in stress development during drying of aqueous silica and poly(vinyl alcohol) (PVA) suspensions, and the microstructure of solid film. Adsorbed polymers were found to affect the spatial organization of silica particles, which reduces the size of aggregates and the increase in stress development. The effect of adsorbed polymers on the stress development was hindered as the amount of non-adsorbed polymer increased. The role of adsorbed and non-adsorbed PVA in stress development was found to be generalized to yield a single master curve independent of polymer concentration.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We investigate the role of polymers in stress development of drying silica/PVA mixtures. </LI> <LI> Adsorbed PVA reduces the size of aggregates, thus increases the stress in the solid film. </LI> <LI> The effect of adsorbed PVA is hindered as non-adsorbed PVA increases. </LI> <LI> The role of PVA in stress development is generalized to yield a single master curve. </LI> </UL> </P>

Prediction of Microstructure in High-Strength Ductile Forging Parts

M. Urban,C. Keul,A. Back,W. Bleck,G. Hirt 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Governmental, environmental and economic demands call for lighter, stiffer and at the same time cheaper products in the vehicle industry. Especially safety relevant parts have to be stiff and at the same time ductile. The strategy of this project was to improve the mechanical properties of forging steel alloys by employing a high-strength and ductile bainitic microstructure in the parts while maintaining cost effective process chains to reach these goals for high stressed forged parts. Therefore, a new steel alloy combined with an optimized process chain has been developed. To optimize the process chain with a minimum of expensive experiments, a numerical approach was developed to predict the microstructure of the steel alloy after the process chain based on FEM simulations of the forging and cooling combined with deformation-time-temperature-transformation-diagrams.

열간가공된 γ-TiAl 합금의 미세조직 제어 및 기계적 특성 평가

박성현 ( Sung-hyun Park ),김재권 ( Jae-kwon Kim ),김성웅 ( Seong-woong Kim ),김승언 ( Seung-eon Kim ),박노진 ( No-jin Park ),오명훈 ( Myung-hoon Oh ) 한국열처리공학회 2019 熱處理工學會誌 Vol.32 No.6

The microstructural features and texture development by both hot rolling and hot forging in γ-TiAl alloy were investigated. In addition, additional heat treatment after hot forging was conducted to recognize change of the microstructure and texture evolution. The obtained microstructural features through dynamic recrystallization after hot deformed γ-TiAl were quite different because two kinds of formation process were occurred depending on deformation condition. However, analyzed texture tends to be random orientation due to intermediate annealing up to α+β region during the hot deformation process. After additional heat treatment, microstructure transformed into fully lamellar microstructure and randomly oriented texture was also observed due to the same reason as before. Tensile test at room temperature demonstrated that anisotropy of mechanical properties were not appeared and transgranular fracture was occurred between interface of α2/γ. As a result, it could be suggested that microstructural features influenced much more than texture development on mechanical properties at room temperature. (Received October 22, 2019; Revised October 31, 2019; Accepted November 4, 2019)

Analytical Quantification and Effect of Microstructure Development in Thick Film Resistor Processing

Lee, Byung Soo The Korean Microelectronics and Packaging Society 2012 마이크로전자 및 패키징학회지 Vol.19 No.4

Microstructure developments of $RuO_2$ based thick film resistors during firing as a function of glass viscosity were analytically quantified and its effect on the electrical property was investigated. The microstructure development was retarded as the viscosity of glass was increased. It was found that the viscosity range for each stage of microstructure development are as follows ; $7500-10^5Pa{\cdot}s$ for the glass sintering, $2000-7500Pa{\cdot}s$ for the glass island formation, $700-2000Pa{\cdot}s$ for the glass spreading, and $50-700Pa{\cdot}s$ for the infiltration. The sheet resistivity decreased as the viscosity of glass in the resistor film increased due to the higher chance of sintering for the conductive particles with the higher viscosity of the glass.

Microstructure evolution and strength development of ultra rapid hardening cement modified with redispersible polymer powder

Gwon, Seongwoo,Jang, Seung Yup,Shin, Myoungsu Elsevier 2018 Construction and Building Materials Vol.192 No.-

<P><B>Abstract</B></P> <P>Ultra rapid hardening (URH) cement is used where ultra high early strength is required in construction. This study investigated the age-dependent characteristics of calcium sulfoaluminate (CSA)-based URH cement modified by the addition of acrylic redispersible polymer powder. Specifically, the effects of polymer powder on the microstructure evolution and strength development were examined from an early age of 2 h up to 90 days. The macro- and microstructural properties of various cement paste, mortar, and concrete samples were characterized by compressive strength, rheology, mercury intrusion porosimetry, powder X-ray diffraction, and scanning electron microscopy with energy-dispersive spectroscopy. The test results revealed that increasing the polymer proportion up to 10% by mass of cement not only delayed the setting and hydration, but also refined the pore structures of the URH cement systems, which is considered the main cause of the long-term strength convergence of the mortars with different polymer ratios. The polymer addition induced the formation of more ordered and denser ITZs between the mortar and coarse aggregate. All findings support the favorable effects of the polymer powder on the long-term strength and durability of the URH cement systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effects of polymer on the microstructure evolution and strength development were examined from 2 h to 90 days. </LI> <LI> Increasing the polymer proportion up to 10% delayed the setting and hydration and reduced the early strength. </LI> <LI> The long-term strengths of mortars exhibited convergence regardless of the polymer ratio. </LI> <LI> The polymer addition induced the formation of more ordered and denser ITZs between the mortar and coarse aggregate. </LI> </UL> </P>

Estimation of the Effect of Grain Boundary Diffusion on Microstructure Development in Magnetite Bi-crystal under Oxygen Chemical Potential Gradient at 823 K

Ueda, Mitsutoshi,Maruyama, Toshio The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.1

Mass transport near grain boundary in a magnetite bi-crystal has been estimated at 823 K by finite element method. Mass transport near grain boundary strongly depends on the diffusivities along grain boundary. If grain boundary diffusion has the same oxygen activity dependence as lattice diffusion, there is no mass transport between grains and grain boundary. On the other hand, mass transport between grains and grain boundary is observed in the case that grain boundary diffusion has different oxygen activity dependence.

Estimation of the Effect of Grain Boundary Diffusion on Microstructure Development in Magnetite Bi-crystal under Oxygen Chemical Potential Gradient at 823 K

Mitsutoshi Ueda,Toshio Maruyama 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.1

Mass transport near grain boundary in a magnetite bi-crystal has been estimated at 823 K by finite element method. Mass transport near grain boundary strongly depends on the diffusivities along grain boundary. If grain boundary diffusion has the same oxygen activity dependence as lattice diffusion, there is no mass transport between grains and grain boundary. On the other hand, mass transport between grains and grain boundary is observed in the case that grain boundary diffusion has different oxygen activity dependence.

달걀껍질의 재 사용에 의해 제조 된 생체용 Calcium Phosphate 분말의 상변화 거동 및 미세구조 변화에 관한 연구

이상진,김주원,Lee Sang-Jin,Kim Joo-Won 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.5

Calcium phosphate powders were successfully synthesized by using re-cycled eggshell and phosphoric acid. The crystallization behavior and powder morphologies of the synthesized powders were dependent on the starting condition of the eggshell, the mixing ratio and method of the eggshell and phosphoric acid, and calcination temperature. In general, $\beta$-tricalcium phosphate was stably synthesized at about $900^{\circ}C$ for 1h at each proper mixing ratio. And, the synthesized powders showed the similar microstructures to the morphology of original eggshell with uniform particle sizes. In this study, the calcium phosphate powders were synthesized with eggshell in various processing method. And their unique microstructures obtained from the eggshell were also. observed. The crystalline developments and microstructures of the synthesized powders were examined by X-ray diffractometer and scanning electron microscopy.

초등 2, 4, 6학년 아동의 이야기 쓰기 발달과 읽기, 음운 처리 및 언어 능력과의 관계

윤효진,이혜원,김보림 이화여자대학교 교과교육연구소 2022 교과교육학연구 Vol.26 No.2

This study investigated the narrative writing development of second, fourth, and sixth graders and the relationship between writing, reading, phonological processing and language abilities. In particular, this study focused on the microstructure and the macrostructure, and each index was analyzed by a rating scaled score. A total of 65 participants with 26 second graders, 19 fourth graders, and 20 sixth graders participated. All participants were typically developing children with no cognition and language problems. A total of 6 writing composition with a lead-in sentence, reading, phonological processing, and language were assessed. The results showed that writing skills developed over time as students advanced to second, fourth, and sixth grades. There was no significant difference between grades on sentence completeness. The index of grammatical error and cohesion showed a clear improvement between second to fourth grade, while syntax complexity showed rapid development in the fourth to sixth graders. In terms of spelling, they showed improvement across all the grades. As well, each writing indexes was found to be have correlations with reading, phonological processing, and language skills. The results suggest that various writing index should be examined using writing composition in order to evaluate achievement ability for the curriculum of writing. 본 연구는 초등 2, 4, 6학년을 대상으로 서두제시형 이야기 쓰기과제를 실시하고, 전반적인 작문능력을 살펴보았다. 특히, 본 연구는 쓰기발달에서 중요한 성취기준인 미시구조(문장쓰기, 문법오류, 구문복잡도, 철자법)와 거시구조(글의 응집성)의 지표들을 척도점수로 분석함으로써 각 지표들이 어떠한 발달적 특성을 가지는지를 살펴보았으며, 더불어 이러한 쓰기지표들이 읽기, 음운처리, 언어능력과 어떠한 관련성을 가지는지도 함께 분석하고자 하였다. 초등 2학년 26명, 4학년 19명, 6학년 20명의 총 65명이 참여하였으며, 모든 참여자는 언어와 인지발달에 어려움이 없는 일반아동으로 선정하였다. 총 6문항의 서두제시형 이야기 쓰기과제와 읽기(해독과 읽기이해), 음운처리능력(음운인식, 빠른이름대기, 음운기억)과 언어검사(수용어휘, 구문의미이해력, 문장따라말하기, 구문인식)를 실시하였다. 연구결과 초등 2, 4, 6학년에 따라 쓰기능력이 발달하는것으로 나타났다. 문장을 의미와 구문에 적절하게 쓰는 능력은 학년 간 차이를 보이지 않았다. 문법형태소 오류와 응집성은2학년에서 4학년으로 올라가면서 뚜렷한 차이를 보이는 것으로 나타난 반면, 구문복잡도는 4학년에서 6학년 시기에 급격한발달을 보였다. 철자는 모든 학년 간에 차이를 보이며 계속적인 발달을 하는 것으로 나타났다. 또한 쓰기의 각 지표들은 읽기, 음운처리 및 언어능력과 관련성이 있었다. 본 연구결과는 교육과정에 맞는 성취능력을 평가하기 위해 작문쓰기과제를 사용하여 여러 쓰기지표를 살펴보는 것이 필요함을 시사한다.