• 소성∙가공
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• 제33권1호
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• pp.5-11
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• 2024

The development of a next-generation hydrogen compressor, a key component in the expansion of hydrogen charging infrastructure, is in progress. In order to improve compression efficiency and durability, it is important to optimize the precision forming and shearing processes of the diaphragm, which is the bellows unit cell, as well as the optimization of diaphragm shape itself. In this study, we aim to show that die and process design technology that can synchronize the inner and outer shearing points of the diaphragm for the precision forming of product can be constructed based on a numerical simulation. First, the damage model that can predict the fracture points will be determined using the shear load and shear zone measurements obtained by performing a blanking test of AISI-633 stainless steel. Next, we will explain the overall procedure based on numerical analysis model how to determine the shearing points according to the deformation pattern of urethane die for various shearing die design.

• 한국가스학회지
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• 제27권4호
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• pp.70-77
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• 2023

기후변화에 대한 대응으로 각국에서는 에너지수급계획에서 온실가스를 줄이는 목표를 제시하고 있으며, 그 이행을 위한 에너지 자원의 우선순위에서 늘 빠지지 않은 화두가 수소가스 이용이다. 이 수소가스를 이용하기 위한 대중적인 방법으로 수소연료전지 자동차의 이용을 꼽을 수 있으며, 이 수소연료전지 자동차를 이용하는데 필수적인 것이 수소충전소의 확충이다. 하지만 수소충전소의 확충을 위해서 여러 제약사항이 발생하고 있으며 그 중 가장 대표적인 것이 주민 수용성이다. 현재 국내 건립된 수소충전소 중 대부분은 인구밀도가 떨어진 외곽에 위치하고 있으며, 때문에 수소연료전지 자동차 이용자들의 불편은 해소되지 않고 있고 그에 따라 수소연료전지 자동차의 보급도 진전이 없다. 본 논문에서는 시민들이 많이 이용하는 철도부지에 수소충전소를 건설하였을 때의 위험성을 알아보기 위해 사고 피해 영향을 분석하였다. 대상 수소충전소 부지는 부산의 한 철도기지창을 대상으로 하였으며, 이 부지 주위에는 철도차량, 국도 및 상업시설이 존재한다. 최악의 시나리오를 가정했을 때 사로고 인해 영향을 받은 지역과 그 영향을 분석하여 수소충전소 부지의 안전에 대한 고찰을 하고자 한다.

• 대한예방한의학회지
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• 제19권3호
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• pp.141-154
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• 2015

Objective : In this paper, we investigated the anti-oxidative capacities and protective effects of water extract of palmul-tang (PMT) against Ultraviolet B(UVB)-induced oxidative damage in human keratinocytes(HaCaT). Method : To evaluate the anti-oxidative activities of PMT, we measured scavenging activities on 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical, hydroxyl radical, hydrogen peroxide, superoxide anion, lipid peroxidation and reducing power of PMT. To give an oxidative stress to HaCaT cells, UVB was irradiated with $40mJ/cm^2$ to HaCaT cells. To detect the protective effects of PMT against UVB, we measured cell viability, apoptotic bodies and reactive oxygen species(ROS) generation. Results : PMT showed the anti-oxidative activities by scavenging DPPH radical, hydroxyl radical, hydrogen peroxide, superoxide anion, lipid peroxidation. Also PMT showed high reducing values. The UVB-induced oxidative conditions led to the cell apoptosis. However, treatment with PMT reduced oxidative stress conditions, including inhibition of cell apoptosis and expression of ROS. Conclusion : PMT had anti-oxidative activities and exhibited protective effects against UVB on HaCaT cells. PMT would be useful for the development of cosmetics treating UVB-induced skin aging.

• 한국환경성돌연변이발암원학회지
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• 제19권2호
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• pp.116-121
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• 1999

Quercetin and its glycosides showed a strong free radical scavenging effect to DPPH radical generation. However, there were not big differences between quercetin aglycone and glycosides under experimental condition of this study. On the other hand, quercetin had pro-oxidant effect in bleomycin-dependent DNA assay. Quercetin aglycone and its glycosides, quercitrin inhibited $H_2$$O_2$- induced DNA damage in CHL cells. They also have an anticlastogenicity toward DNA breakage agent by radical generation like bleomycin. These results indicate that quercetin aglycone and its glycosides are capable of protecting the free radical generation induced by reactive oxygen species like $H_2$$O_2$. The mechanism of inhibition in hydrogen peroxide-induced genotoxicity may be due to their free radical scavenging properties. Therefore, quercetin aglycone and its glycosides may be useful chemopreventive agents by protecting of free radical generation which are involved in carcinogenesis and aging. However, quercetin and its glycosides must also carefully examined for pro-oxidant properties before being proposed for use in vivo.

• 한국의류학회지
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• 제30권2호
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• pp.338-347
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• 2006

Due to the complex environment in the ground, most of excavated costumes undergo deterioration and color change. To reduce the extent and intensity of the staining and to recover the original color or gray fabrics of excavated costumes, bleaching would be required. Excavated historical costumes are very delicate in nature, therefore, special care is needed in bleaching process. Several bleaching agents were selected and applied to the control cotton fabric and pre-deteriorated cotton fabrics to examine the change of color and physical properties after bleaching. A dual bleaching using hydrogen peroxide and sodiumborohydride showed the superior bleaching effect to the other bleaching agents. The strength of pre-deteriorated fabrics slightly increased after dual bleaching. The six historical costumes which belonged to General Duk-Ryung Kim's nephew's wife were dual bleached. They became remarkably cleaned and brightened. The treatments improved the appearance of costumes. By microscopic investigation, it is found that costumes did not show the damage after treatment. In conclusion, it is possible to bleach historical textiles without damage using appropriate bleaching agents like hydrogen peroxide and sodiumborohydride.

• 한국안전학회지
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• 제31권6호
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• pp.32-38
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• 2016

In general, lots of containers including various dangerous materials are transported to the port located in big cities such as Busan where massive residents live. Thus, it's really important how to make the emergency response for the leak accidents of dangerous materials and evaluate the direct or indirect damages to adjacent areas. In this study, in order to make reasonable emergency plans, CA (Consequence Analysis) is employed after selecting a key hazardous and noxious material, hydrogen fluroide. This material accounts for the third largest portion of cargo volume among all dangerous materials and can cause a huge damage in case of leakages. As a case study, Busan North port is selected as a test port since the portion of dangerous materials is higher than that of other ports in Busan. It is assumed that 1 ton of hydrogen fluoride is spilled at Busan North port. CA is performed to assess the impact of this accident. Throughout CA, the ERPG-2 range of a leak accident can be evaluated and this result can be used for decision making tools for mitigating the impact of a leak accident. To mitigate the damage of this accident, suitable a protective equipment and resident evacuation procedures should be prepared. Finally, this study can provide a systematic approach to make the emergency plan for reducing economical and personal losses.

• 동의생리병리학회지
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• 제29권6호
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• pp.475-484
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• 2015

In this paper, we studied the anti-oxidative capacities and protective effects of water extract of Gagam-Danguieumja(GDE) against Ultraviolet B(UVB)-induced oxidative damage in human keratinocytes(HaCaT). To evaluate the anti-oxidative activities of GDE, we measured scavenging activities on DPPH radical, hydroxyl radical, hydrogen peroxide, superoxide anion, lipid peroxidation and reducing power of GDE. To detect the protective effects of GDE against UVB, we irradiated with 40 mJ/㎠`s UVB to HaCaT cells then we measured reactive oxygen species(ROS) generation, apoptotic bodies and cell viability using DCFH-DA assay, Hoechst 33342 staining and MTT assay. GDE showed the anti-oxidative activities by scavenging DPPH radical, hydroxyl radical, hydrogen peroxide, superoxide anion, lipid peroxidation. Also GDE showed high reducing values. GDE reduced oxidative stress conditions by inhibition of ROS expression. Also the cell apoptosis by UVB-induced oxidative conditions was decreased by GDE treatment. These results could suggest that GDE had anti-oxidative activities and exhibited protective effects against UVB on HaCaT cells. GDE would be useful for the development of cosmetics treating UVB-induced skin aging.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.207-216
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• 2014

This paper revisits the Fukushima accident to draw lessons in the aspect of nuclear safety considering the fact that the Fukushima accident resulted in core damage for three nuclear power plants simultaneously and that there is a high possibility of a failure of the integrity of reactor vessel and primary containment vessel. A brief review on the accident progression at Fukushima nuclear power plants is discussed to highlight the nature and characteristic of the event. As the severe accident management measures at the Fukushima Daiich nuclear power plants seem to be not fully effective, limitations of current severe accident management strategy are discussed to identify the areas for the potential improvements including core cooling strategy, containment venting, hydrogen control, depressurization of primary system, and proper indication of event progression. The gap between the Fukushima accident event progression and current understanding of severe accident phenomenology including the core damage, reactor vessel failure, containment failure, and hydrogen explosion are discussed. Adequacy of current safety goals are also discussed in view of the socio-economic impact of the Fukushima accident. As a conclusion, it is suggested that an investigation on a coherent integrated safety principle for the severe accident and development of innovative mitigation features is necessary for robust and resilient nuclear power system.

• Archives of Pharmacal Research
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• 제28권11호
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• pp.1251-1256
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• 2005

In this study, we evaluated the cytoprotective effects of antioxidative substances in hydrogen peroxide ($H_{2}O_{2}$) treated Mel-Ab melanocytes. Tested substances include selenium, quercetin, green tea (GT) extract, and several vitamins (ascorbic acid, Trolox, and folic acid). Of these, both quercetin and GT extract were found to have strong cytoprotective effects on $H_{2}O_{2}$­induced cell death. We also examined additive effects, but no combination of two of any of the above substances was found to act synergistically against oxidative damage in Mel-Ab cells. Nevertheless, a multi-combination of GT extract, quercetin, and folic acid appeared to prevent cellular damage in a synergistic manner, which suggests that combinations of antioxidants may be of importance, and that co-treatment with antioxidants offers a possible means of treating vitiligo, which is known to be related to melanocyte oxidative stress.

• 한국수산과학회지
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• 제36권4호
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• pp.346-351
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• 2003

Single-cell gel electrophoresis (comet assay) was used to detect DNA single strand break in blood cells from several marine fish species. Three fish species were collected from Georgia coastal area. Mummichog, Fundulus heteroclitus showed higher DNA damage than sea bass, Lateolabrax japonicus and trout, Oncorhynchus masou masou under the same experimental conditions. Mummichogs had more alkaline-labile sites on their DNA than other fish species. The comet assay with mummichog blood cells at pH 12.5 showed a dose-response curve with the increasing concentrations of hydrogen peroxide. While the isolated leucocytes showed no increase of DNA damage after in vitro exposure to 2-methyl-1,4-naphthoquinone (MNQ), erythrocytes showed dose-dependent DNA damage. These results indicate that the comet assay can be applied successfully as a bioassay using erythrocyte for environmental monitoring.