• KDI Journal of Economic Policy
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• v.14 no.1
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• pp.167-189
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• 1992

The most difficult problem one faces in estimating North Korea's GNP is the lack of basic national income data. In addition, there is no appropriate foreign exchange rate available to convert North Korea's GNP to dollar values. The physical indicators method is particularly useful in estimating North Korean GNP because it requires only a modest amount of data and obtains dollar GNP directly by applying a relationship between physical indicators and GNP, which is estimated from reference countries, to physical indicators of North Korea. The estimated result of North Korean GNP in 1990 is 27.1 billion dollars and per capita GNP 1,268 dollars. The trade participation ratio (Trade/GNP) implied by the GNP estimate was plausible and so was the ratio of fiscal expenditure to GNP. This paper examined the physical indicators method's logic, the quality of the North Korean data that was used in the estimation, and the plausibility of estimation result. Relatively simple data requirement, comparative ease of computation and plausible estimation results suggest that use of physical indicators method could enhance the reliability of North Korean GNP estimate.

• Polymer(Korea)
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• v.37 no.4
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• pp.518-525
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• 2013

To improve the mechanical properties of polypropylene (PP) biocomposites reinforced with sulfuric acidtreated green algae (SGA), SGA/graphite nanoplatelets (GNP)/PP biocomposites were prepared and their properties were evaluated depending on the particle size and content of GNP. The flexural and impact strength of SGA/GNP/PP biocomposites decreased with the addition of GNP, whereas the flexrual and storage moduli were greatly improved with increasing GNP loading. SGA/GNP/PP biocomposites reinforced with GNP5 showed generally better mechanical properties compared to that reinforced with GNP15 mainly due to the improved dispersion of the smaller GNP. SGA/GNP/PP biocomposites reinforced with GNP5 showed a lower resistance to the thermal expansion because the relatively uniform dispersion of smaller GNP was responsible for the effective heat transfer to the polymer matrix. As a result, SGA/GNP/PP biocomposite was acceptable for the general purpose application due to the improved flexural resistance, storage moduli, and damping characteristics.

• Korean Journal of Adult Nursing
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• v.19 no.4
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• pp.656-669
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• 2007

Purpose: The purposes of this article were to analyze curricula of gerontological nurse practitioner(GNP) programs in the United States, to compare the curricula with Korean GNP programs, and to provide suggestions for better GNP programs in Korea. Methods: Top GNP programs in the United States were identified from the US NEWS and 12 universities were included in the analyses. Class distribution, credit hours, and clinical hours were analyzed and suggestions for Korean GNP programs were made. Results: Average credit hours for class lectures in the US GNP programs were 47 and emphases on physiology, pharmacology, physical assessment, and disease management were identified. Most US GNP programs(75%) provided health concerns for both middle aged and older adults. Not all US GNP programs included 'theory' or 'the introduction to GNP' classes, while these are required classes in the Korean GNP program. The mean clinical hours in the US GNP Programs were 537 which are much higher than those in the Korean GNP program. Conclusion: Based on the analyses, we can conclude that Korean GNP programs are lacking in many ways. Further evaluation and curricula modifications are required to settle down the program better and to have the graduates prepared more as internationally competent nurse practitioners.

• Polymer(Korea)
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• v.38 no.4
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• pp.502-509
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• 2014

Carbon-based nanoplatelets such as graphene oxide (GO) sheets and graphite nanoplatelets (GNPs) are frequently used as conductive nanofillers for polymer nanocomposites. In this study, polystyrene (PS)/GO and PS/GNP nanocomposites were prepared through a latex technology and investigated to compare the effect of nanofillers on rheological and electrical properties of the PS nanocomposites. PS particles were prepared by emulsifier-free emulsion polymerization and GO was synthesized by using the modified Hummers' method from graphite. Hydrophilic GO was dispersed in aqueous PS suspension, but hydrophobic GNPs were dispersed with the help of a surfactant. In comparison with PS/GO nanocomposites, the rheological properties of PS/GNP counterparts were not too high because GNP existed in aggregates of graphene layers. Conducting pathways of PS/GO and PS/GNP nanocomposites were achieved at the electrical percolation threshold of 0.50 and 5.82 wt%, respectively. The reason for enhanced electrical conductivity in PS/GO nanocomposites is that GO was thermally reduced during molding.

• Composites Research
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• v.28 no.3
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• pp.124-129
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• 2015

CNT and GNP have several excellent mechanical properties including, high strength, Young's modulus, thermal conductivity, corrosion resistance, electronic shielding and so on. In this study, CF/CNT, GNP/epoxy composites were manufactured by varying the CNT weight ratio at 2wt% and 3wt%, GNP weight ratio at 0.5wt% and 1 wt%. The composites were manufactured by mechanical method (3-roll-mill). Tensile, impact and wear tests were performed according to ASTM standards D638, D256 and D3181 respectively. The results showed that, CF/GNP0.5 wt%/epoxy composites gave good mechanical property in all composites, e.g., tensile strength, impact and were resistance.

• Composites Research
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• v.32 no.3
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• pp.134-140
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• 2019

Graphene nanoplatelets (GNP), one of the graphene derivatives is famous as the most proper candidate for industrial applications. However, current performance of GNPs as reinforcing filler in composites is limited by their agglomeration and physicochemical heterogeneity. Herein, an approach to produce non-covalently functionalized GNPs (F-GNPs) is reported which possesses potential to be extended as the industrial level of mass production. The one-step functionalization process uses melamine, a low-cost chemical, to prevent agglomeration and dispersion in polar solvents. Furthermore, a purification strategy called salting-out process based on differences in the dispersibility of the individual F-GNP flakes is reported to separate F-GNPs. The functionalization and separation process developed in this paper provides a strategy to use GNPs at the industrial level in composite applications.

• Progress in Medical Physics
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• v.33 no.4
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• pp.114-120
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• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.117-122
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• 2002

고체산화물 연료전지의 구성요소인 양극(공기극)을 GNP와 Pechini 법을 이용하여 $(La{1-x}Sr_x)MnO_3$ 양극을 합성하여 합성한 분말의 특성과 단위전지로 사용하기 위한 조건에서의 특성을 측정하였다. GNP로 합성한 분말의 경우 직접 $(LaSr)MnO_3$ 단일 결정상을 얻을 수 있었으나, Pechini 법으로 합성한 분말의 경우는 비정질이었다. 또한 각각의 방법으로 합성한 분말의 입자형태는 구형이었고 1차상 입자크기는 GNP가 40nm, Pechini, 법으로 합성한 경우 20nm 정도의 크기를 갖고 있었다. GNP로 합성한 분말의 입자크기와 비표면적의 경우 glycine의 첨가량이 증가함에 따라 입자크기는 감소하였으나 최적 glycine 첨가량은 2.0mole 였고, 이 때 평균2차상의 입자크기는 $13.24{\mu}m$로 agglomeration 되어있었다. 최적 cathode조성은 GNP법으로 합성한 $(La_{0.9}Sr_{0.1}MnO_3$로서 가능하였고, 이 조성에서의 열팽창계수는 $9.89\times10^{-6}/^{\circ}C$이고, 전기전도도($1200^{\circ}C$에서 2시간소결)는 110 S/cm을 나타내었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.31-32
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• 2019

In this study, oxidized graphene nanoplatelet(GO) was prepared by oxidizing graphene nanoplatelet(GNP) with nitric acid in order to solve the problem of dispersion of GNP, one of nano materials. GNP/Epoxy and GO/Epoxy paint were prepared by mixing GNP, GO with 0.1, 0.3, 0.5 and 1.0 wt.% in epoxy paint and the mechanical properties were evaluated. As a result, GNP/Epoxy and GO/Epoxy paints showed better mechanical properties than Neat Epoxy which did not incorporate GNP, GO. Especially, when 0.3 wt.% of GO was incorporated into epoxy resin, it showed higher tensile strength than Neat Epoxy. It was confirmed that acid treatment of GNP was effective in improving the mechanical properties of epoxy paint. However, graphene material was found that it was not effective in improving the bond performance of the epoxy paint.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.465-471
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• 2017

In this study, oxidized graphene nanoplatelet(GO) was prepared by oxidizing graphene nanoplatelet(GNP) with nitric acid in order to solve the problem of dispersion of GNP, one of nano materials. The surface chemical composition of the prepared GO was analyzed by fourier transform infrared spectroscopy(FT-IR) before incorporation into the epoxy paint, and the dispersibility in the solvent was confirmed. Meanwhile, GNP/Epoxy and GO/Epoxy paint were prepared by mixing GNP, GO with 0.1, 0.3, 0.5 and 1.0wt.% in epoxy paint and the mechanical properties were evaluated. As a result, GNP/Epoxy and GO/Epoxy paints showed better mechanical properties than Neat Epoxy which did not incorporate GNP, GO. Especially, when 0.3wt.% of GO was incorporated into epoxy resin, it showed higher tensile strength than Neat Epoxy. It was confirmed that acid treatment of GNP was effective in improving the mechanical properties of epoxy paint.