• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.353-360
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• 2012

The corrosion product of archaeological iron objects is supposed to be removed because it causes re-corrosion. So far it is removed by scapel and sand blaster but they depend on the skill and experience of a conservator and the glass-dust of the sand blaster is harmful to humans. Therefore this study applies a laser cleaning system which is used in various industrial cleaning processes, to remove corrosion product from archaeological iron objects. In addition, this work studies the alternation of corrosion product after laser irradiation, which evaluates the reliability of the laser cleaning system. Optical microscopy, SEM-EDS, XRD, Raman have been used to observe and analyse the surface of the objects. The results show the capacity of laser cleaning some corrosion product, but blackening appears with increasing pulses and laser energy, and some corrosion products, goethite and hematite, are partially altered to magnetite. These problems, blackening and alternation of corrosion product, should be solved by further studies which find the optimal laser irradiation condition and use a wetting agent.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.18-23
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• 2002

The detection characteristics of gamma-irradiated $(0{\sim}4\;kGy)$ soybeans produced in Korea and China were investigated by thermoluminescene (TL), electron spin resonance (ESR), and DNA comet assay. The TL glow curves were shown at around $200^{\circ}C$ for irradiated soybeans, while that at $280^{\circ}C$ for the non-irradiated one. The normalization with a re-irradiation step at 1 kGy could verify the above detection results. The Korean soybean showed higher glow curves than Chinese did. The ESR spectroscopy for husks of irradiated soybeans revealed specific signals (g = 2.02374, 1.98715) derived from cellulose radical, which intensities were proportional to irradiation does, with the higher peaks in Chinese sample than Korean one. The DNA comet for the non-irradiated sample showed no or little tails, while those for irradiated samples above 0.5 kGy were remarkably changed in their length, size, and concentration, thus resulting in distinguishing non-irradiated from irradiated samples. As a result, TL, ESR, and DNA comet determinations were found suitable for the detection of irradiated soybean at 0.5 kGy or more, and negligible differences were observed between Korean and Chinese origins in their detection characteristics.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.37-43
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• 2001

Polyvinylidenefluoride and Polytetrafluoroethylene have been irradiated by 1 keV Ar+ ion beam in an $O_2$ environment. Hydrophilic functional groups (such as -(C-O)-,-(C=O)-,-(C=O)-O- and so on) were formed on fluoropolymers. Contact angles of water to PVDF were reduced from $75^{\circ}$ to $31^{\circ}$. Re-increase of contact angle was originated from carbonization phase in case of high dose irradiation above $1{\times}10^{16} Ar^+cm^2$. Contact angles to PTFE decreased at low dose irradiation and were exaggerated to about $140^{\circ}$ due to cone type surface at high dose irradiation. Hydrophilic functional groups have played an important role on adhesion between metal and fluoropolymers by acid-base interaction and chemical bond formation. Adhesion of Pt/PVDF was enhanced by acid-base interaction because Pt is inert metal. Chemical bond formation between Cu and PTFE could enlarge the adhesion strength of Cu/PTFE.

• Korean Journal of Materials Research
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• v.24 no.6
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• pp.305-309
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• 2014

When sunlight irradiates a boron-doped p-type solar cell, the formation of BsO2i decreases the power-conversion efficiency in a phenomenon named light-induced degradation (LID). In this study, we used boron-doped p-type Cz-Si solar cells to monitor this degradation process in relation to irradiation wavelength, intensity and duration of the light source, and investigated the reliability of the LID effects, as well. When halogen light irradiated a substrate, the LID rate increased more rapidly than for irradiation with xenon light. For different intensities of halogen light (e.g., 1 SUN and 0.1 SUN), a lower-limit value of LID showed a similar trend in each case; however, the rate reached at the intensity of 0.1 SUN was three times slower than that at 1 SUN. Open-circuit voltage increased with increasing duration of irradiation because the defect-formation rate of LID was slow. Therefore, we suppose that sufficient time is needed to increase LID defects. After a recovery process to restore the initial value, the lower-limit open-circuit voltage exhibited during the re-degradation process showed a trend similar to that in the first degradation process. We suggest that the proportion of the LID in boron-doped p-type Cz-Si solar cells has high correlation with the normalized defect concentrations (NDC) of BsO2i. This can be calculated using the extracted minority-carrier diffusion-length with internal quantum efficiency (IQE) analysis.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.188-194
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• 2002

This study was carried out to observe changes in several detection factors derived from thermoluminescence (TL) of minerals separated from irradiated Korean perilla and sesame seeds during storage under normal room and darkroom conditions. The TL intensities of the first glow curves increased from 0 to 5 kGy but only slightly increase from 5 to 10 kGy. Maximum TL temperatures of the first glow curves in all irradiated samples were around 20$0^{\circ}C$, ranging from 150 to 25$0^{\circ}C$. Since the control (0 day of storage) glow curve ratios of G3 and G4, calculated from re-irradiated (1 kGy) sample were over 0.5, detection of irradiation was possible. However, because Gl ratios were below 0.1, they were classified as non-irradiated. There was n unique first glow curve shape that could be clearly seen in all irradiated samples, regardless of storage conditions, that was never seen in non-irradiated samples. In all samples, the maximum TL temperatures and shape of the second glow curve was in a lower temperature range than that of the first glow curve. Therefore, detection of irradiated Korean perilla and sesame seeds was possible fur up to 3 months after irradiation, regardless of storage conditions, by examining several TL detection factors; including TL intensity, glow curve ratios maximum TL temperatures, and the shapes of glow curves.

• Journal of Ginseng Research
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• v.48 no.2
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• pp.211-219
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• 2024

Background: Recently, plant-derived exosome-like nanoparticles (PDENs) have been isolated, and active research was focusing on understanding their properties and functions. In this study, the characteristics and molecular properties of ginseng root-derived exosome-like nanoparticles (GrDENs) were examined in terms of skin protection. Methods: HPLC-MS protocols were used to analyze the ginsenoside contents in GrDENs. To investigate the beneficial effect of GrDENs on skin, HaCaT cells were pre-treated with GrDENs (0-2 × 10⁹ particles/mL), and followed by UVB irradiation or H₂O₂ exposure. In addition, the antioxidant activity of GrDENs was measured using a fluorescence microscope or flow cytometry. Finally, molecular mechanisms were examined with immunoblotting analysis. Results: GrDENs contained detectable levels of ginsenosides (Re, Rg1, Rb1, Rf, Rg2 (S), Gyp17, Rd, C-Mc1, C-O, and F2). In UVB-irradiated HaCaT cells, GrDENs protected cells from death and reduced ROS production. GrDENs downregulated the mRNA expression of proapoptotic genes, including BAX, caspase-1, -3, -6, -7, and -8 and the ratio of cleaved caspase-8, -9, and -3 in a dose-dependent manner. In addition, GrDENs reduced the mRNA levels of aging-related genes (MMP2 and 3), proinflammatory genes (COX-2 and IL-6), and cellular senescence biomarker p21, possibly by suppressing activator protein-1 signaling. Conclusions: This study demonstrates the protective effects of GrDENs against skin damage caused by UV and oxidative stress, providing new insights into beneficial uses of ginseng. In particular, our results suggest GrDENs as a potential active ingredient in cosmeceuticals to promote skin health.

• Korean Journal of Pharmacognosy
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• v.41 no.1
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• pp.26-30
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• 2010

The root of Korean ginseng (Panax ginseng C.A. Meyer) is a commonly used herbal medicine in China, Korea, Japan. However, the compositions and effects of Korean ginseng berry are not clear to date. In order to investigate the anti-aging effects in the skin, Korean ginseng berry was extracted with 70% ethanol and tested the biological effects. In the results, Korean ginseng berry extract showed an excellent anti-oxidant effect against oxidative stress and decreased MMP-1 over-expression induced by UV irradiation. Especially the main component of Korean ginseng berry extract, ginsenoside Re, increased hyaluronic acid in HaCaT keratinocytes. We improved Korean ginseng berry could be a good material for the anti-aging effect of skin.

• Applied Microscopy
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• v.42 no.4
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• pp.207-211
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• 2012

We examined the electrical properties and microstructure of NiO produced using a sol-gel method and Ni nitrate hexahydrate ($Ni[NO_3]_2{\cdot}6H_2O$) to investigate if this NiO thin film can be used as an insulator layer for resistance random access memory (ReRAM) devices. It was found that as-prepared NiO film was polycrystalline and presented as the nonstoichiometric compound $Ni_{1+x}O$ with Ni interstitials (oxygen vacancies). Resistances-witching behavior was observed in the range of 0~2 V, and the low-resistance state and high-resistance state were clearly distinguishable (${\sim}10^3$ orders). It was also demonstrated that NiO could be patterned directly by KrF eximer laser irradiation using a shadow mask. NiO thin film fabricated by the sol-gel method does not require any photoresist or vacuum processes, and therefore has potential for application as an insulating layer in low-cost ReRAM devices.

• Journal of Acupuncture Research
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• v.36 no.4
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• pp.197-203
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• 2019

The purpose of this study was to investigate useful manual therapy techniques for peripheral facial nerve palsy and to propose guidelines to be applied for current manual therapy techniques. Several databases were searched to find manual therapies for facial palsy. These therapies included cervical, and temporomandibular joint chuna manual therapy, proprioceptive neuromuscular facilitation, neuromuscular re-education, facial exercise, and mime therapy. Both cervical, and temporomandibular joint chuna manual therapy release nerve compression, helping blood circulation and nerve conduction. Proprioceptive neuromuscular facilitation uses irradiation, bilateral activation, and eccentric facilitation to improve muscle power and symmetry. Neuromuscular re-education, as a retraining tool for facial movement patterns, enhances neuromuscular feedback. Facial exercise helps the patient continuously move and massage facial muscle themselves. Mime therapy aims to develop a conscious connection between the use of certain muscles and facial expressions. The use of facial chuna manual therapy for peripheral facial nerve palsy can stimulate the proprioceptive neuromuscular receptors in the face. Peripheral facial nerve palsy has 4 phases; progress phase, plateau phase, recovery phase, and sequelae phase. Each phase needs different treatments which include relaxation, assistance, resistance, origin-insertion extension, and nerve pathway expansion.

• Resources Recycling
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• v.30 no.6
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• pp.61-67
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• 2021

This work investigated the cementation of iridium from iridium-containing hydrochloric acid leachate. Zinc powder was used as the reducing agent, and the effects of the stoichiometric ratio of Zn/Ir, initial Ir concentration, initial pH, reaction time, and ultrasound irradiation on iridium recovery were investigated. When only the stirrer was used for cementation, the iridium recovery increased with the addition amount of zinc, and the recovery of about 70% at 40 times the stoichiometric ratio of Zn/Ir. In contrast, when employing ultrasonic irradiation with stirring, the recovery of iridium decreased at 20 times or less the stoichiometric amount of zinc. The recovery of iridium increased at 40 times the stoichiometric ratio of Zn/Ir. This result may be due to the ionization of zinc and re-dissolution of iridium during the ultrasound irradiation treatment. When a combination of ultrasonic irradiation and stirring was used for cementation, the iridium recovery increased by more than 27% compared to that when using only the stirrer. It was possible to recover 99% of iridium under the following conditions: reaction time, 60 min; initial pH, 0.01; volume of leachate, 100 mL; 1770 ppm Ir, 40 times the stoichiometric ratio of Zn/Ir.