• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.585-608
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• 2009

The aim of this study was to research the characteristics of science teachers' thinking related to dissolution and diffusion. For this study, five science teachers who majored in chemistry or chemistry education were selected and interviewed. These teachers have been teaching on average for 2$\sim$6 years. From the study, it was discovered that the science teachers didn't recognize the necessity of sorting out diffusion from dissolution. The teachers divided in various mixing phenomena with diverse criteria. The science teachers had difficulty in sorting out diffusion from dissolution based on solubility and Gibbs' energy. The teachers didn't see the linkage between the contents that were divided into chapters, and didn't find omitted contents themselves in the chapters that introduced applicable principles. During the interviews, the teachers felt the need to understand the principles for understanding phenomena. But they did not have the ability to teach these principles after learning about the principles themselves. Therefore, it is necessary to develop teacher education programs, as well as a science curriculum, that helps in linking the knowledge between natural phenomena and principles.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.572-578
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• 2006

The accumulation of phenol in apples was measured by exposing them to phenol vapor at $25^{\circ}C$. The effective diffusivities of phenol in the rind and flesh of apples were estimated by comparing the experimentally determined fractional uptake curve with the simulated ones based on a consecutive diffusion model in the rind and flesh. Phenol was detected in the flesh of apples after 5 day exposure due to its slow diffusion in the rind. The consecutive diffusion model of phenol in apples simulated well the measured fractional uptake curve when the effective diffusivities of phenol in the rind and flesh were assumed to be $5.0{\times}10^{-13}m^2/s$ and $1.5{\times}10^{-10}m^2/s$, respectively.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.3
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• pp.5-12
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• 1990

This study has been conducted to establish the carburizing characteristics of low carbon alloy steels with varying amount of Ni element gas-carburized for 2 hours at $930^{\circ}C$ in an atmosphere of 94% $N_2$-6% $C_3H_8$ gas mixture with some changes in gas pressure passing through the diffusion plate in the fluidized-bed furnace. The results obtained from the experiment are as follows : (1) Optical micrograph has shown that the carburized layer consists of retained austenite and plate martensite and that retained austenite increases as the pressure of gas mixture passing through the diffusion plate as well as Ni content increase. (2) Chemical analysis has shown that carbon potential increases and carburizability is also improved due to a less degree of fluidization as the pressures of gas mixtures passing through the diffusion plate increase, resulting in, however, a severe formation of soot, and the gas pressure is necessarily regulated. (3) It has been revealed that carbon concentration hardness values at a given distance measured from the surface within the carburized case. Increase with increasing the pressure of gas mixtures passing through the diffusion plate and decrease with increasing Ni content. (4) The effective case depth has been shown to almost linearly increase as the pressure of gas mixtures passing through the diffusion plate is increased and to decrease with increasing Ni content.

• Korean Journal of Metals and Materials
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• v.48 no.8
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• pp.691-698
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• 2010

A study has been carried out to evaluate the interaction behavior between a lanthanide element and clad material in order to analyze the effect of the lanthanide element on the fuel cladding chemical interaction (FCCI). A diffusion couple test between Misch metal (70Ce-30La) and ferritic-martensitic steel (Gr.92) was performed at $660^{\circ}C$, followed by a microstructural analysis of the coupled sample. The results showed that Ce in the Misch metal, rather than La, reacted with the ferritic-martensitic steel (FMS) to form an interaction layer that penetrated the clad thickness. Fe diffused outside the clad interface to form an $Fe_2Ce$ compound, leaving a depletion of Fe caused by excess diffusion as well as by the formation of Cr-rich precipitation inside the interaction layer. The rate of growth followed the cubic rate law, which indicated that Fe depletion was caused by the diffusion of Fe and that the associated Cr-rich phase formation controlled the whole diffusion process.

• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.995-1002
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• 2010

This study investigated the effect of process temperature on the alloying process during synthesis of $Sm_2Fe_{17}$ powder from ball-milled samarium oxide ($Sm_2O_3$) powders and a solid reducing agent of calcium hydrides ($CaH_2$) using iron nanopowder (n-Fe powder) by a reduction-diffusion (R-D) process. The $n-Fe-Sm_2O_3-CaH_2$ mixed powders were subjected to heat treatment at $850{\sim}1100^{\circ}C$ in $Ar-H_2$ for 5 h. It was found that the iron nanopowders in the mixed powders are sintered below $850^{\circ}C$ during the R-D process and the $SmH_2$ is synthesized by a reduced Sm that combines with $H_2$ around $850^{\circ}C$. The results showed that $SmH_2$ is able to separate Sm and $H_2$ respectively depending on an increase in process temperature, and the formed $Sm_2Fe_{17}$ phase on the surface of the sintered Fe nanopowder agglomerated at temperatures of $950{\sim}1100^{\circ}C$ in this study. The formation of the $Sm_2Fe_{17}$ layer is mainly due to the diffusion reaction of Sm atoms into the sintered Fe nanopowder, which agglomerates above $950^{\circ}C$. We concluded that nanoscale $Sm_2Fe_{17}$ powder can be synthesized by controlling the diffusion depth using well-dispersed Fe nanopowders.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.228-236
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• 2015

Fluorescence recovery after photobleaching (FRAP) is a well-established method commonly used to measure the diffusion of fluorescent solutes and biomolecules in living cells or tissues. Here a fiber-optic-based FRAP (f-FRAP) system was developed, and validated using macromolecules in water and agarose gels of different concentrations. We applied f-FRAP to measure the site-specific diffusion of fluorescein (NaFluo) in peritoneal membranes (PMs) on the liver, cecum, and kidney of a living rat during peritoneal dialysis. Diffusion of fluorescein in PM varied in a time-dependent manner according to the type of organ ($D_{PM\;on\;Liver}/D_{NaFluo}=0.199{\pm}0.085$, $D_{PM\;on\;Cecum}/D_{NaFluo}=0.292{\pm}0.151$, $D_{PM\;on\;Kidney}/D_{NaFluo}=0.218{\pm}0.110$). The proposed method allows direct quantitative measurement of the three-dimensional diffusion in local PM in vivo, which was previously inaccessible by peritoneal function test methods such as peritoneal equilibration test (PET) and standardized PM assessment (SPA). f-FRAP is promising for local and dynamic assessments of peritoneal pathophysiology and the mass transport properties of PMs, presumed to be affected by variation of tissue structures over different organs and functional changes of the PM with years of peritoneal dialysis.

• Current Photovoltaic Research
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• v.9 no.3
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• pp.96-105
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• 2021

Even though above 22% efficiencies have been reported in Cd-free Cu(In,Ga)Se₂ (CIGS) solar cell with Zn-containing buffers, the efficiencies with Zn-containing buffers, in general, are well below 20%. One of the reasons is Zn diffusion from the Zn-containing buffer layer to CIGS film during buffer growth. To avoid the degradation, it is necessary to prevent the diffusion of Zn atoms from Zn-containing buffer to CIGS film. For the purpose, we characterized an In₂Se₃ film as a possible diffusion barrier layer because In₂Se₃ has no Zn component. It was found that an In₂Se₃ layer grown at 300℃ was very effective in preventing Zn diffusion from a Zn-containing buffer. Also, the In₂Se₃ had a large potential barrier in the valence band at the In₂Se₃/CIGS interface. Therefore, In₂Se₃ passivation has the potential to achieve a super-high efficiency in CIGS solar cells that employ Cd-free ALD processed buffers containing Zn.

• Journal of Agricultural Extension & Community Development
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• v.7 no.1
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• pp.101-119
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• 2000

Agricultural Extension Services in Korea have accomplished a significant role in self- sufficiency of rice, a national staple food, through green revolution in 1970's; supplying green vegetables even during the winter season through white revolution in 1980's; and establishing technical agriculture by organizing rural leaders and 4-H members. In 1990s changes were made in international situations under the Uruguay Round multilateral trade negotiations and inauguration of the World Trade Organization. This was followed by localization of the extension staffs and the functions of extension services in Korea changed dramatically from national government to local governments. Thus, a weakened national function resulted in loosening of the linkages of research and extension in central government and local extension offices. Difficulties were reported in diffusion of new agricultural technology and efficient management of extension personnel. Developmental tasks for better extension services for the 21st century in Korea would include recovering national functions of agricultural extension, and developing a new paradigm for extension service. This should include the following measures; 1) Cooperative extension service should be adapted to involve national as well as local governments and non-government organization. 2) The target groups for extension services should be expanded to include farmers, noel residents as well as urban consumers. 3) The role of the extension service should cover agricultural technological diffusion of innovations as well as managerial skills and leadership development for rural organizations. 4) Extension services should be introduced to small farmers as well as consultation services for advanced farms. Diversified approaches should be employed for mama effective services. 5) Pre-service as well as in-service education should be offered to secure better extension educators equipped with knowledge, understanding and abilities on agricultural technology, information, agricultural philosophy, instructional methods and communication skills.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.750-753
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• 2016

Quorum sensing (QS) is a bacterium-to-bacterium cell communication mechanism allowing bio-cell network construction but such mechanism is not well defined yet. We construct a QS-based multiple access network (MAN) and then numerically analyse its average uplink channel capacity as well as BER performance over diffusion-based 3-D molecular communication channels.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.1
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• pp.143-151
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• 2015

Technology convergence, recently accelerated in various technical fields, can be achieved by discovering a new technology while exchanging the knowledge among the different technologies and utilizing such knowledge into the existing fields of technology. In particular, technology convergence actively occurs in knowledge-intensive ICT. However, limited research is available on the routes of ICT technical knowledge diffusion because of insufficient data. Therefore, this study built a database on the citations of patent data applied from 2006 to 2013 in Korea and their cited patents. We drew a patent citation network, a technology citation network and an applicant citation network, after which we analyzed the routes of technical knowledge diffusion. Results showed that ICT played a leading role in knowledge citation among technologies and that such diffusion took a shorter time in technology citation when it occurred more frequently and when the citation occurred between ICTs. In addition, most of the ICT showed a strong citation relationship with the other ICTs or such technologies in the field of physics or electricity, whereas electric elements (H01) showed various citation relationships with technologies other than ICT. Furthermore, we found a strong technology diffusion relationship between domestic corporations and domestic natural persons. National organizations often cited the patents of other applicants, whereas the patents of domestic corporations were actively cited between domestic corporations or by other applicants. Thus, this study is expected to be useful in measuring the performance of technologies, including the diffusion to other technologies. As well as in considering the routes of technical knowledge diffusion in Korea.