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안주영,윤은영,박학수,전효수 국립중앙박물관 2012 박물관보존과학 Vol.13 No.-
국립중앙박물관 보존과학팀에서는 동북아지석묘연구소에서 의뢰한 전라남도 여수 월내동 출토 비파형동검에 대한 보존처리를 실시하였다. 여수 월내동 비파형동검은 현재까지 출토된 비파형동검 중 가장 길이가 긴 동검에 해당되며, 1차적으로 보존처리가 이루어진 상태였다. 부식이 진행되어 매우 취약한 상태로 상단부와 하단부 2개체로 분리되어 있었고, 상단부는 표면에 노출된 형태로 하단부는 흙과 함께 응급 수습되었다. 보존과학팀에서는 흙 속에 있는 비파형동검 하단부를 노출시켜 상단부와 접합하고, 결실된 부위는 추정 복원하는 방법으로 보존처리를 진행하였다. 보존처리 시 취약한 유물을 강화하는 방법으로 유리섬유는 10 wt% Paraloid B-72 (in Xylene)를 이용하였고, 성분을 확인하기 위해 X-선 형광분석기를 이용한 비파괴분석을 실시하였다. The Conservation Science Team of the National Museum of Korea has carried out the conservation on the mandolin-type bronze sword that was excavated from Wollae-dong, Yeosu as had been requested by the Research Center of Dolmens in Northeast Asia. The mandolin-type bronze sword from Wollae-dong, Yeosu is accounted to be the longest one among all the bronze swords of the same type that have ever been excavated until now and it was in a treated condition with the primary conservation treatment already achieved. Due to the corrosion in progress, it was in a very brittle condition being in two separate parts of the upper and lower parts. With the upper part exposed and the lower part with earth, they were urgently collected. The Conservation Science Team carried out the conservation treatment on them by connecting the lower part of the mandolin-type bronze sword to the upper part after making the lower part exposed, and then by using an estimated restoration method for lost portions. When carrying out the conservation treatment, the glass fibers of 10 wt% Paraloid B-72(in Xylene) was used as a method for strengthening the brittle artifact, and a non-destructive analysis was carried out to identify the ingredients using the X-ray fluorescence spectrometer.
Bimodal colloid gels of highly size-asymmetric particles.
Lee, Jooyoung,Lee, Seong Jae,Ahn, Kyung Hyun,Lee, Seung Jong Published by the American Physical Society through 2015 Physical review. E, Statistical, nonlinear, and so Vol.92 No.1
<P>We report a type of colloidal gel, induced by a minute incremental addition of mutually attractive small particles (size ???12 nm) to a suspension of highly charged large particles (size ???500 nm). The gel's morphological behavior does not follow the typical power-law scaling for fractal clusters. Its unique scaling behavior has two distinct power-law indices, based on particle volume fraction. We show the unique scaling behavior arises when nonfractal networks of large particles are bridged by small-particle clusters, which occurs between a lower and upper critical boundary of small particle volume fraction.</P>
Modeling handicapped pedestrians considering physical characteristics using cellular automaton
Kim, Jooyoung,Ahn, Chiwon,Lee, Seungjae Elsevier 2018 PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIO Vol.510 No.-
<P><B>Abstract</B></P> <P>In disaster situations, the evacuation of pedestrians is very important. In particular, handicapped pedestrians experience difficulties in evacuation situations because they cannot move quickly. Therefore, the evacuation of handicapped pedestrians is considered to be an important factor in disaster situations. In this study, we use a walking model based on a cellular automaton (CA) to study the effect of handicapped walking movement related to traffic flow. For the purpose of this research, handicapped walking encompasses wheelchairs, crutches, children, and elderly people. A new model is constructed and analyzed that reflects the physical characteristics of handicapped pedestrians. In this study, the change of pedestrian traffic flow was observed while simulating a 30% ratio of handicapped to normal people. The experimental results showed that the average walking speed decreased by approximately 12% for each simulation step. Therefore, the results of this study suggest that it is necessary to consider handicapped pedestrians in order to conduct realistic evacuation simulations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The paper contributes to the cellular automaton model considering on handicapped characteristics. </LI> <LI> We construct a fundamental diagram to represent our presented mixed pedestrian model. </LI> <LI> Our proposed approach can reveal the influence of handicapped better than the previous studies. </LI> </UL> </P>
Kim, Jooyoung,Kim, Junhyeong,Kim, Hyunki,Ahn, Sang Hyun American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.34
<P>Hydrogen production via a proton exchange membrane water electrolyzer (PEMWE) is an essential technology to complement discontinuity of renewable energies. Development of a high-efficiency and cost-effective gas diffusion electrode (GDE), which is a key component of this technology, remains a challenge. Here, we report a high-performance Ni phosphide GDE prepared by simple electrochemical methods. Selective leaching of excess Ni in electrodeposited Ni<SUB><I>x</I></SUB>P<SUB>1-<I>x</I></SUB> enabled fabrication of a nanoporous NiP GDE with a large electrochemical surface area (ECSA). In half-cell tests, the nanoporous NiP GDE demonstrated a hydrogen-evolving current density of −10 mA/cm<SUP>2</SUP> at an overpotential of 103 mV with good stability. In the single-cell tests, the PEMWE employing a nanoporous NiP cathode exhibited a current density of 1.47 A/cm<SUP>2</SUP> at a cell voltage of 2.0 V, which was the competitive performance among state-of-the-art non-noble cathodes reported to date.</P> [FIG OMISSION]</BR>
Jung, Jooyoung,Moon, Noory,Ahn, Ji-Yeon,Oh, Eun-Jee,Kim, Myungshin,Cho, Chul-Soo,Shin, Jong-Chul,Oh, Il-Hoan Mary Ann Liebert 2009 STEM CELLS AND DEVELOPMENT Vol.18 No.4
<P>Recent clinical trials using ex vivo expanded mesenchymal stromal cells (MSCs) have raised interest in the safety and function of cultured MSCs. Here, to assess the feasibility of using allogenic human umbilical cord blood serum (CBS) for humanized clinical-grade expansion of MSCs, we characterized MSCs expanded in CBS and compared them to MSCs expanded in fetal bovine serum (FBS). MSCs in CBS exhibited a higher preservation of colony-forming cells and an accelerated expansion over serial passages with increased Oct-4 expression compared to those cultured in FBS. Notably, CBS-expanded MSCs exhibited a unique differentiation potential characterized by a shift from adipogenic to osteogenic differentiation. The differentiation shift was associated with enhanced basal and Runx2-mediated transcriptional activation of the osteocalcin promoter, as well as increased accumulation of beta-catenin and the yes-associated protein (YAP) which was independent of changes in TAZ (transcriptional co-activator with PDZ-binding motif) levels. Interestingly, the phenotypes were reversed when the FBS and CBS media were switched, suggesting the unique stimulatory effects of CBS rather than the selection of heterogeneous MSC subpopulations. The distinct regulatory effects of CBS on MSC included selective activation of platelet-derived growth factor and epidermal growth factor signals in MSCs, but not in FBS. Taken together, these results provide insight into the dynamic regulation of MSCs during ex vivo culture and show that the ex vivo culture of MSCs in allogenic human CBS provides a novel tool for the accelerated expansion of a population of MSCs that exhibit a higher self-renewal and an enhanced osteogenic potential.</P>
A new paradigm of materials processing—heterogeneity control
Lee, Jooyoung,Sung, Sanghoon,Kim, Youngseok,Park, Jun Dong,Ahn, Kyung Hyun Elsevier Science B.V.Amsterdam 2017 Current opinion in chemical engineering Vol.16 No.-
<P>In most emerging industries including batteries, solar cells, electronic components, printed electronics, the material processing can be understood based on a single platform – ‘transport phenomena of complex fluids’ – which has rarely been in the subject of academic research. This paper covers the complexity in these applications, which is strengthened by the use of nanoparticles. The key concept hidden underneath of this platform is heterogeneity which keeps on changing during processing, leading to a broad spectrum of microstructure and composition. Thus, we have to control heterogeneity for better design of materials and processing. Conventional approach is not enough, and we need a new paradigm in materials processing, which is the control of heterogeneity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterogeneity always appears in materials processing. </LI> <LI> Microstructure constantly changes during the whole process. </LI> <LI> Same recipe never guarantees same product. </LI> <LI> Compositional distribution to the thickness direction during drying. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>