• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.463-469
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• 2022

After reviewing the current status of hydrogen buses and hydrogen charging stations in the United States, as well as related laws and programs, it was found that the federal and state governments supported the supports of hydrogen buses and the deployment of hydrogen charging infrastructure through various policies and programs. In order to promote the spread of domestic and overseas hydrogen buses and hydrogen charging infrastructure, it is necessary to develop and apply various legal systems and programs that can provide incentives to hydrogen bus manufacturers, hydrogen charging station installers, hydrogen bus operating organizations and entities. It is necessary to develop and apply various legal systems and programs that can provide incentives to hydrogen bus manufacturers, hydrogen charging station installers, hydrogen bus operating organizations and entities.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.431-441
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• 2021

UAE is first country in Middle East to approve UN Paris Climate Agreement. Ministry of Climate Change and Environment of UAE announced National Climate Change Plan for carbon reduction to replace 24% by clean energy. Dubai open its first hydrogen station in UAE and Middle East in 2017, and Abu Dhabi planed to open second hydrogen station in 2019 but not realized. Korean government announced hydrogen economy roadmap in 2019 and various hydrogen cooperation are realized between UAE, Korea, Germany, USA, and Japan. MOU between Ministry of State of UAE and Ministry of Land, Infrastructure and Transport of Korea in 2019 for the cooperation of hydrogen city. This study propose strategies for the 'Hydrogen Based Public Transport in UAE' by the support of Korea government considering various stakeholder.

• Biomolecules & Therapeutics
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• 제12권4호
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• pp.228-234
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• 2004

Brazilin shows hypoglycemic effect in diabetic animals through enhancement of glucose metabolisms in insulin responsive tissues. One of the major mechanisms of brazilin to enhance glucose metabolism is stimulation of glucose transport in adipocytes. In this study, the essential molecular moiety of brazilin for the stimulation of glucose transport was investigated. We found that brazilin undergoes a structural change in physiological buffer and produces hydrogen peroxide. Methylation of hydroxyl group of brazilin or addition of catalase along with brazilin resulted in the complete inhibition of brazilin-induced glucose transport in adipocytes. Because hydrogen peroxide increases glucose transport by inhibition of phosphatases, we examined the effect of brazilin on phosphatase activity. Brazilin inhibited phosphatases in a wide range of activity, and protein phosphatase 1 and 2A were also inhibited. These results suggest that the production of hydrogen peroxide by oxidation of catechol hydroxyl group of brazilin mediates glucose transport through inhibition of phosphatases which otherwise decrease glucose transport in adipocytes.

• 대한기계학회논문집A
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• 제33권6호
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• pp.600-606
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• 2009

In this paper, the coupled model with hydrogen transport and elasto-plasticity behavior is introduced. This model is implemented to the general-purpose FE code, ABAQUS, via the user-defined subroutine UMAT and UMATHT. In UMAT, the spatial gradients of hydrostatic stress and hydrogen induced deformation are calculated, and then are passed into UMATHT. Heat transfer equation within UMATHT is substituted by hydrogen transport equation including the effects of stress states and strain hardening. To validate this model, the finite element analyses coupled with hydrogen transport and mechanical loading are performed for the boundary layer specimens with low and high strength steel properties. The FE results are compared with the previous studies by Taha and Sofronis (2001).

• 전기화학회지
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• 제8권1호
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• pp.47-54
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• 2005

This article covers the fundamentals of stress-induced diffusion, focusing on the theoretical model for hydrogen transport through self-stressed electrode. First, the relationship between hydrogen diffusion and macroscopic deformation of the electrode specimen was briefly introduced, and then it was classified into the diffusion-elastic and elasto-diffusive phenomena. Next, the transport equation for the flux of hydrogen caused simultaneously by both the concentration gradient and the stress gradient was theoretically derived. Finally, stress-induced diffusion was discussed on the basis of the numerical solutions to the derived transport equation under the permeable and impermeable boundary conditions.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.623-630
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• 2023

Recently, a hydrogen charging station-related memorandum of understanding (MOU) was signed between Korea Transport Institute and United Arab Emirates (UAE) Ministry of Transport in Abu Dhabi, creating a foundation for exporting green hydrogen charging stations and hydrogen powered public transit buses developed with Korean technology to Abu Dhabi. Reliable construction and operation of the charging stations require a thorough review on associated standards and legal requirements. In particular, it is essential to analyze currently effective standards related to hydrogen production, hydrogen vehicle charging, and hydrogen charging stations. This paper specifically focuses on comparative analysis of hydrogen-related standards in the UAE and the Republic of Korea. Similar to UAE, Korean hydrogen charging station-related standards follow International Organization for Standardization (ISO) standards. From real-life experiences in developing and operating charging stations, even more essence of ISO standards have been adopted in Korean standards than UAE. In particular, ISO standards related to fire prevention are additionally included in Korea. This paper also suggests procedural and administrative strategies for enabling application of Korean hydrogen charging station-related standards in UAE.

• Corrosion Science and Technology
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• 제16권4호
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• pp.209-225
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• 2017

Development of high strength steel requires proper understanding of hydrogen behavior since the higher the steel strength the greater the susceptibility of hydrogen assisted cracking. This paper provides a brief but broad overview on hydrogen entry and transport behavior of high-strength ferritic steels. First of all, hydrogen absorption, diffusion and trapping mechanism of the steels are briefly introduced. Secondly, several experimental methods for analyzing the physical/chemical nature of hydrogen uptake and transport in the steels are reviewed. Among the methods, electrochemical permeation technique utilized widely for evaluating the hydrogen diffusion and trapping behavior in metals and alloys is mainly discussed. Moreover, a modified permeation technique accommodating the externally applied load and its application to a variety of steels are intensively explored. Indeed, successful utilization of the modified permeation technique equipped with a constant load testing device leads to significant academic progress on the hydrogen assisted cracking (HAC) phenomenon of the steels. In order to show how the external and/or residual stress affects mechanical instability of steel due to hydrogen ingress, the relationship among the microstructure, hydrogen permeation, and HAC susceptibility is briefly introduced.

• International Journal of Safety
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• 제6권1호
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• pp.16-21
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• 2007

Carbon nanotubes hold much promise as future materials for safe storage of hydrogen. In this paper, hydrogen transport mechanisms in single-walled carbon nano-tubes (SWNTs) for various temperatures and chiral indices were studied using molecular dynamics simulation method. The SWNT models of zigzag (10,0), chiral (10,5) and armchair (10,10) with hydrogen molecules inside were simulated at temperatures ranging from 253K to 373K. Movements of hydrogen molecules ($H_2$) inside a SWNT were analyzed using mean-square displacements and velocity autocorrelation functions.

• Journal of Plant Biology
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• 제36권4호
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• pp.313-319
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• 1993

Photoproduction of hydrogen by free and polyvinylalcohol (PVA)-immobilized spinach chloroplasts was investigated. Immobilization of chloroplast with PVA increased the functional stability of the chloroplast during storage. PVA-immobilized chloroplasts preserved photosynthetic electron transport activity much better than free chloroplasts. The hydrogen production of free chloroplast decreased to 17% of initial activity after storage of six days. The hydrogen production of the PVA-immobilized chloroplast, however, showed 44% of initial activity after storage of 15 days. The maximal rate of hydrogen production was accomplished at 2$^{\circ}C$ under the light intensity above 116 $\mu$E.m-2.s-1. The amount of hydrogen produced was proportional to the chlorophyll concentration. The hydrogen production was inhibited by DCMU treatment, indicating hydrogen production is dependent on photosynthetic electron transport. These results suggest that PVA is a good candidate for the immobilization matrix of chloroplasts for the photoproduction of hydrogen.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.442-454
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• 2021

The porous transport layer (PTL) is essential to effectively remove oxygen and hydrogen gas from the electrode surface at high current density operation conditions. In this study, the effect of PTL with different characteristics such as pore size, pore gradient, interfacial coating was investigated by multi-layered sintered mesh. A water electrolysis single cell of active area of the 34.56 cm² was constructed, and IV performance and impedance analysis were conducted in the range of 0 to 2.0 A/cm². It was confirmed that the multi-layered sintered mesh PTL, which have an average pore size of 25 to 57 ㎛ and a larger pore gradient, removed bubbles effectively and thus seemed to improve IV performance. Also, it was confirmed that the catalytic metals such as Ni, NiMo coating on the PTL reduced activation overpotential, but increased mass transport overpotential.