• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.602-603
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• 2006

Micro-porous nickel (Ni) with an open cell structure was fabricated by powder metallurgy. The pore size of the micro-porous Ni approximated $30{\mu}m$ and $150{\mu}m$. For comparison, porous Ni with a macro-porous structure were also prepared by both powder metallurgy (pore size $800{\mu}m$) and the traditional chemical vapour deposition method (pore size $1300{\mu}m$). The mechanical properties of the micro-and macro-porous Ni samples were evaluated using compressive tests. Results indicate that the micro-porous Ni samples exhibited significantly enhanced mechanical properties, compared to those of the macro-porous Ni samples.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.623-624
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• 2006

The behavior of hardmetals under cyclic loads is investigated. Unnotched specimens were employed to obtain practical information regarding fatigue in hardmetals. All the tested hardmetals exhibit an increase in the number of cycles until failure with a decrease in the maximum stress, i.e., the hardmetals exhibit a high fatigue sensitivity. The fatigue strength increases with the cobalt content. Although distinct fatigue limits, as observed in metals, cannot be observed, the calculated fatigue limit stress at $10^7$ cycles is found to be approximately 70% of the flexural strength, and the stress value exhibits a linear relationship with the flexural stress.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.621-622
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• 2006

In this paper, we show some experimental results of binder-free WC sintered by Pulsed Electric Current Sintering (PECS) also known as Field Assisted Sintering Technology (FAST). These binder-free WC have extremely hardness and stiffness. However, these mechanical properties are dependent on the sintering condition, e.g., maximum temperature, applied pressure, etc. We show some relationship between mechanical properties and sintering condition to improve to sinter the binder-free WC.

• The Journal of the Korea Contents Association
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• v.6 no.3
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• pp.28-37
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• 2006

In the last decades, inter-networking technologies advanced more rapidly than any other field. Today, the Internet is one of the most important infrastructure to society as becoming an indispensible tool of people and companies. During mid-1990's, developed countries recognized the advanced network as a basic infrastructure for the future science and technology development. They developed national research and education networks for the development of future science and network technology. In this paper, we made a comprehensive review of global research and education network developments. We also made analysis of Korea's activities on advanced network comparing with those of developed nations, then suggested approaches to improve Korean advanced networks.

• Journal of Korean Academy of Nursing Administration
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• v.15 no.2
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• pp.264-274
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• 2009

Purpose: This study is to develop job standards in order to propose proper job level of the advanced nurse practitioners and apply the results to the work and enhance the expertism. Method: This study is a methodical study. The validity was examined by using the content validity index(CVI). Result: The pre-items of job standards for advanced health insurance review nurses were established and the final job standards comprising of 12 standards, 46 criteria, 92 indicators, 418 activities were determined after the examination by the advisory group. The validity of the job standards were examined for two times by the seven professionals. The relevance of the modified job standards was examined by the working level employees above the assistant manager position working in the general hospitals and the result was 93.14% relevance. The job standards comprising of 12 standards, 46 criteria, 89 indicator and 409 activities were developed. Conclusions: By the development of the job standards, it is expected to prove that advanced health insurance review nurses are the most suitable professionals for dealing with medical affairs such as management and propriety evaluation of medical expenses while defining the roles of advanced health insurance review nurses.

• Korean Journal of Metals and Materials
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• v.50 no.6
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• pp.449-454
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• 2012

Nanopowder of FeAl and $Al_2O_3$ was synthesized from FeO and Al powders by high energy ball milling. Using the pulsed current activated sintering method, the nanocystalline $Al_2O_3$ reinforced FeAl composite was consolidated within two minutes from mechanically synthesized powders. The advantage of this process is that it allows very quick densification to near theoretical density and prohibits grain growth in nanostuctured materials. The grain size, sintering behavior and hardness of sintered $FeAl-Al_2O_3$ composite were investigated.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.84-89
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• 2020

Cancer cells secrete angiogenic factors, and nearby vasculatures make new blood vessels essential for cancer development and metastasis in response to these soluble factors. Many efforts have been made to elucidate cancer-endothelial cell interactions in vitro. However, not much is known due to the lack of a suitable co-culture platform. Here, we introduce a 3D printing-based microfluidic system that mimics the in vivo-like cancer-endothelial cell interactions. The tumoroids and endothelial cells are co-cultured, physically separated by porous fibrin gel, allowing communication between two cell types through soluble factors. Using this microfluidic system, we were able to visualize new vessel formation induced by tumoroids of different origins, including liver, breast, and ovary. We confirmed that the ovarian tumoroids most induced angiogenesis while the other two cancer types suppressed it. Utilization of the proposed co-culture platform will help the researchers unveil the underlying mechanisms of the dynamic interplay between tumor and angiogenesis.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.190-196
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• 2009

The inhibition effects of an Alpinia officinarum (AO, Zingiberaceae) on the formation of advanced glycation end products, aldose reductase, and scavenging effect on 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical for the prevention and/or treatment of diabetic complications were investigated. The ethyl acetate fraction of AO was the most effective among all fractions. Through the tests with electron impact-mass spectrometry and nuclear magnetic resonance, two compounds (compound 1 and 2) finally obtained from the ethyl acetate fraction of AO were identified as galangin (1) and kaempferide (2), respectively. In addition, the compound 1 and 2 and the ethyl acetate fraction were compared for the prevention effect on advanced glycation end products, aldose reductase, and the scavenging effect on DPPH radical. The ethyl acetate fraction was significantly more effective than the 2 compounds for those preventive activities.

• Resources Recycling
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• v.25 no.5
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• pp.14-27
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• 2016

Theoretical reviews of integrated gasification combined cycle one of the clean coal technologies and trends in the study and technology development for high temperature desulfurization sorbents were investigated. Reactivity, durability and abrasion resistance is an important key for development of high temperature desulfurization sorbents, the kind of things include calcium, zinc, manganese, iron and copper-based sorbents. Current status of high temperature desulfurization sorbents, manufacturing techniques of zinc-based sorbent in advanced countries has commercialized. In case of Korea, various research studies are underway to commercialize the Zn and non Zn-based high temperature desulfurization sorbents to cheaper and superior capability using various supports.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.82-91
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• 1998

The elastic modulus and wear resistance in austempered ductile cast iron(ADI) are two important mechanical properties for automobile parts. Therefore, the effect of Cu, Ni, Mo and special austempering treatment such as preheated, prequenched, and step austempering treatments on elastic modulus and wear resistance has been investigated systomatically. As a result, elastic modulus and wear resistance were increased by the addition of Mo-Cu and preheated austempering treatment.