• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.387-393
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• 2001

This paper describes an advanced measuring method and precise evaluation of the ground resistance for the grounding system of energized substations and power equipments. A grounding system of substations consists of all interconnected grounding connections of grounded conductors, neutral ground wires, underground conductors of distribution lines, cable shields, grounding terminals of equipments, and etc. It is very difficult to measure the accurate ground resistance of the grounding terminals of equipments, and etc. It is very difficult to measure the accurate ground resistance of the grounding system of high voltage energized substations because of harmonic components caused by switched power supplies or overloads. The conventional fall-of-potential method may be subject to big error if stray ground currents and potentials are present. In this work, to improve the precision in measurements of the ground resistance by eliminating the effects of harmonic components and stray currents and potentials, the investigations of the ground resistance measurement by using a low pass filter in a model energized grounding system were conducted. The accuracy of ground resistance mesurements was evaluated as a function of the ratio of the test signal to noise (S/N). The errors due to the proposed ground resistance measurement method were decreased with increasing S/N and were less than 5[%] as S/N is 10. The proposed ground resistance measurement method appears to be considerably more accurate than the conventional fall-of -potential method. It is allows cancellation of the parasitic resistance of energized grounding systems, to employ the measurement method that allows cancellation of the parasitic effects due to other circulating ground currents and ground potential rises in practical situations.

• International Commerce and Information Review
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• v.6 no.2
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• pp.107-127
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• 2004

The rapid development of internet information technology has increased interest in e-Trade these days, but it is not activated greatly up to now. In order to promote e-Trade, it is essential to construct cooperative process such as connecting systems among trade related parties. Building e-Trade platform which is based on the infrastructure of the past trade automatic system is key point of promoting e-Trade. To do this, a study on the basic concept and specific components of e-Trade platform is needed absolutely. At this point of view, after this paper has examined domestic and foreign studies on the fundamental technologies about electronic commerce, it drew several key technologies that could be applied to e-Trade considering the current IT trend. Then it evaluates these technologies according to Technology Reference Model(TRM) of the National Computerization Agency. This will help us to show the operation strategy as well as the concept of future e-Trade platform and its composition. On the basis of the theoretical background, this paper classified NCA's technology model into 6 fields, which are application. data, platform, communication, security and management. Considering the key technologies, e-Trade platform has to be mutually connected and accept international standards such as XML. In the aspect of business side, trade relative agencies' business process as well as trading company's process has to be considered. Therefore, e-Trade platform can be classified into 3 parts which are service, infrastructure and connection. Infrastructure part is compared of circulating and managing system of electronic document, interface and service framework. Connecting service (application service) and additional service (application service) consist of service part. Connecting part is a linking mutual parts and can be divided into B2B service and B20 service. The organization operating this e-trade platform must have few responsibilities and requirements. It needs to positively accept existing infrastructure of trade automatic system and improving the system to complete e-trade platform. It also have to continuously develop new services and possess ability to operate the system for providing proper services to demanders. As a result, private sector that can play a role as TTP(Third Trust Party) is adequate for operating the system. In this case, revising law is necessary to support the responsibility and requirement of private sector.

• Journal of Pharmacopuncture
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• v.20 no.4
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• pp.235-242
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• 2017

Irisin is a novel hormone like polypeptide that is cleaved and secreted by an unknown protease from fibronectin type III domain-containing protein 5 (FNDC5), a membrane-spanning protein and which is highly expressed in skeletal muscle, heart, adipose tissue, and liver. Since its discovery in 2012, it has been the subject of many researches due to its potent physiological role. It is believed that understanding irisin's function may be the key to comprehend many diseases and their development. Irisin is a myokine that leads to increased energy expenditure by stimulating the 'browning' of white adipose tissue. In the first description of this hormone, increased levels of circulating irisin, which is cleaved from its precursor fibronectin type III domain-containing protein 5, were associated with improved glucose homeostasis by reducing insulin resistance. Irisin is a powerful messenger, sending the signal to determine the function of specific cells, like skeletal muscle, liver, pancreas, heart, fat and the brain. The action of irisin on different targeted tissues or organs in human being has revealed its physiological functions for promoting health or executing the regulation of variety of metabolic diseases. Numerous studies focus on the association of irisin with metabolic diseases which has gained great interest as a potential new target to combat type 2 diabetes mellitus and insulin resistance. Irisin is found to improve insulin resistance and type 2 diabetes by increasing sensitization of the insulin receptor in skeletal muscle and heart by improving hepatic glucose and lipid metabolism, promoting pancreatic ${\beta}$ cell functions, and transforming white adipose tissue to brown adipose tissue. This review is a thoughtful attempt to summarize the current knowledge of irisin and its effective role in mediating metabolic dysfunctions in insulin resistance and type 2 diabetes mellitus.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1189-1196
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• 1988

Thermal entrance lengths of turbulent tube flow for viscoelastic polymer solutions are investigated experimentally in the recirculating flow system with tubes of inside diameters 8.5mm(L/D=710) and 10.3mm(L/D=1158), respectively. In the present system, the hydrodynamic and thermal boundary layers develop simultaneously from the beginning of the test section. To provide the boundary condition of constant heat flux at the wall, the test tubes are heated directly by electricity. The polymer solution used in the current study is 1000 wppm aqueous solution of polyacrylamide(Separan AP-273). The apparent viscosity of the polymer solutions circulating in the flow system are measured by the capillary tube viscometer at regular time intervals. Thermal entrance lengths vary due to the rate of degradation. The entrance lengths of degraded polymer solutions are about 500~600 times the diameter. However, the entrance lengths of fresh polymer solutions are greater than the lengths of the test tubes used in this study suggesting that thermal entrance lengths for viscoelastic polymer solutions are greater than 1100 tube times the diameters. Friction factor is almost insensitive to the degradation, but the heat transfer $j_{H}$-factor is affected seriously by degradation. Based on the present experimental data of fresh solutions a correlation for the heat transfer $j_{H}$-factor is presented.ted.

• Nutrition Research and Practice
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• v.7 no.4
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• pp.315-325
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• 2013

We evaluated folate status of child-bearing age women diagnosed with abnormal pap smear in the US post-folic acid (FA) fortification era and assessed the determinants of NTD-protective and supra-physiologic (SP) concentrations of folate. The distribution of 843 women according to NTD-protective concentrations of RBC folate, plasma folate and SP concentrations of plasma folate were tested in relation to demographic and life-style factors. Logistic regression models specified NTD-protective concentrations of RBC and plasma folate or SP concentrations of plasma folate as dependent variables and demographic and life-style factors as independent predictors of interest. More than 82% reached NTD-protective concentrations of RBC and plasma folate and ~30% reached SP concentrations of plasma folate. FA supplement use was associated with having SP concentrations of plasma folate rather than NTD-protective concentrations of folate. African American (AA) women and smokers were significantly less likely to achieve NTD-protective concentrations of RBC and plasma folate. A large majority of women reached NTD-protective concentrations of folate with the current level of FA fortification without using supplementary FA. Therefore, the remaining disparities in AA women and in smokers should be addressed by targeted individual improvements in folate intake.

• Nutrition Research and Practice
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• v.11 no.4
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• pp.290-299
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• 2017

BACKGROUND/OBJECTIVES: Spirulina is a known a functional food related to lipid profiles, immune functions, and antioxidant capacity. Circulating monocyte chemoattractant protein-1 (MCP-1) level is associated with inflammation markers. Single nucleotide polymorphism in the MCP-1 promoter region -2518 have been identified and shown to affect gene transcription. Gene variation may also impact functional food supplementary effects. The current study investigated the interaction of MCP-1 -2518 polymorphism with spirulina supplements on anti-inflammatory capacity in Korean elderly. SUBJECTS/METHODS: After genotyping, healthy elderly subjects (n = 78) were included in a randomized, double blind, and placebo controlled study. Baseline characteristic, body composition, and dietary intake were measured twice (baseline vs. week 16). For 16 weeks, subjects consumed 8 g either spirulina or placebo daily. Plasma MCP-1, interleukin (IL) -2, IL-6, tumor necrosis factor (TNF)-${\alpha}$, complement (C) 3, immunoglobulin (Ig) G, and Ig A concentrations and lymphocyte proliferation rate (LPR) were analyzed as inflammatory markers. RESULTS: In the placebo group with A/A genotype, MCP-1 level was significantly increased, but the spirulina group with A/A genotype was unchanged. IL-2 was significantly increased only in subjects with spirulina supplementation. TNF-${\alpha}$ was significantly reduced in subjects with the G carrier. C3 was significantly increased in the placebo group, particularly when A/A increased more than G, but not when spirulina was ingested. LPR was significantly different only in subjects with A/A genotype; there was a significant increase in phytohemagglutinin and lipopolysaccharide induced LPR in the spirulina group. CONCLUSION: In healthy Korean elderly, spirulina supplementation may influence different inflammatory markers by the MCP-1 genotype. These results may be useful for customized dietary guidelines to improve immune function in Koreans.

• World Technopolis Review
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• v.1 no.4
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• pp.276-286
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• 2013

"Federal investments into the future of a region" - pushing economy in the right direction or throwing tax money into a black hole? Hot-headed contentions keep circulating within politics and economy discussing the effect of technology centers and their sustainability within a region. Start-up support and technological infrastructure with the auxiliary service of well developed sector-oriented clusters as a fertile soil for successful networks are an undeniable advantage of well organised technology centers. Sceptic contemporaries still hold against that in order to implement such a center millions of federal funds for infrastructure and operation are invested. What output of this tax money is verifiable in the long run? The case of Dortmund provides substantial food for this necessary and relevant discussion. Now, after 27 years of history of the TechnologieZentrumDortmund, TZDO for short, a positive balance can be drawn. This is not just a matter of personal belief and stance. Fortunately, a recent study on the economic effects of the TZDO on the whole region was performed by the Center of Applied Economy Research M$\ddot{u}$nster, Germany (Gundel and Luttmann 2008). The result is clear and measurable: the TZDO has shown to be of great impact on the positive development of a whole region. This paper presents an account of the approach of the TechnologieZentrumDortmund and its current strategy and mode of operation to reach an utmost of effectiveness of personal and pecuniary input in establishing economic success for the region of Dortmund. An immense change of minds, employment opportunities and a massive structural change of the whole region were some of the ambitious aims that had to be reached and that are achieved to a large extent.

• Journal of Power Electronics
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• v.19 no.4
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• pp.922-933
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• 2019

The arm inductance (AI) of a modular multilevel converter (MMC) affects both the fault and circulating current magnitudes. In addition, it has an impact on the inverter efficiency and harmonic content. In this study, the AI of a three-phase MMC is optimized in a novel way in terms of DC voltage utilization, harmonics and efficiency. This MMC has 10 submodules (SM) per arm and the power circuit topology of the SM is a half-bridge. The optimum AI is adopted and verified in an MMC that has 100 SMs per arm. Then the phase shift (PS) and phase disposition (PD) pulse width modulation (PWM) methods are investigated for better DC voltage utilization, efficiency and harmonics. It is found that similar performances are obtained for both modulation techniques in terms of DC voltage utilization. However, the total harmonic distortion (THD) of the PS-PWM is found to be 0.02%, which is slightly lower than the THD of the PD-PWM at 0.16%. In efficiency calculations, the switching and conduction losses for all of the semiconductor are considered separately and the minimum efficiency of the 100-SM based MMC is found to be 99.62% for the PS-PWM and 99.64% for the PD-PWM with the optimal value of the AI. Simulation results are verified with an experimental prototype of a 6-SM based MMC.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.299-303
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• 2020

Currently, electric furnace oxide slag is mostly used for soil or road use due to its nature. Although electric furnace oxidation slag is an industrial byproduct, not a circulating aggregate, the shortcomings of electric furnace oxidation slag are gradually being resolved due to the development of technology, and it is said that electric furnace oxidation slag is enough to be used as aggregates in light of research and technology conditions outside of Korea. However, there are difficulties in expanding construction and application, given that the current standard for electric furnace oxid slag only defines recycling purposes and does not have specific regulations. Therefore, institutional supplementation is needed to utilize oxidation slag as electricity. In this study, the laws and system related to oxidation slag by electricity are reviewed, laws related to recycled aggregate are examined, and measures for improvement are proposed.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.125-134
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• 2022

This study aims to critically discuss the problems that need to be solved from a humanities perspective in order to utilize big data. It identifies and discusses three research problems that may arise from collecting, processing, and using big data. First, it looks at the fake information circulating with regard to problems with the data itself, specifically looking at article-type advertisements and fake news related to politics. Second, discrimination by the algorithm was cited as a problem with big data processing and its results. This discrimination was seen while searching for engineers on the portal site. Finally, problems related to the invasion of personal related information were seen in three categories: the right to privacy, the right to self-determination of information, and the right to be forgotten. This study is meaningful in that it points out the problems facing in the aspect of big data utilization from the humanities perspective in the era of big data and discusses possible problems in the collection, processing, and use of big data, respectively.