• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.87-103
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• 2019

Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.1
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• pp.15-21
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• 2022

The purpose of our study was to investigate the migration level of lead (Pb), cadmium (Cd), and barium (Ba) from glassware into a food simulant and to evaluate the exposure of each element. The test articles were glassware, including tableware, pots, and other containers. Pb, Cd, and Ba were analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The analytical performance of the method was validated in terms of its linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, precision, and uncertainty. The monitoring was performed for 110 samples such as glass cups, containers, pots, and bottles. a food simulant. Migration test was conducted at 25? for 24 hours in a dark place using 4% acetic acid as a food simulant. Based on the data; exposure assessment was carried out to compare the estimated daily intake (EDI) to the human safety criteria. The risk levels of Pb and Ba determined in this study were approximately 1.9% and 0.3% of the provisional tolerable weekly intake (PTWI) and tolerable daily intake (TDI) value, respectively, thereby indicating a low exposure to the population.

• Composites Research
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• v.19 no.5
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• pp.20-27
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• 2006

Self-sensing and interfacial evaluation of Ni nanowire/polymer composites were investigated using electro-macromechanical technique, which can be used fur a feasible sensing measurement on tensile and compressive loading/consequent unloading, temperature, and humidity. Mechanical properties of Ni nanowire with different aspect ratio and adding contents in either epoxy or silicone composites were measured indirectly using electro-pullout test under uniform and non-uniform cyclic loadings. Comparing apparent modulus with the conventional mechanical tensile modulus of Ni nanowire/epoxy composites, the trends were consistent with each other. Ni nanowire/epoxy composites showed the sensing response on humidity and temperature. Self-sensing on applied tensile and compressive loading/unloading was also responded for Ni nanowire/silicone composites via electrical contact resistivity showing the opposite trend between tension and compression. It can be due to the different electrically-interconnecting mechanisms of dispersed Ni nanowires embedded in silicone matrix.

• Korean Journal of Materials Research
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• v.34 no.1
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• pp.1-11
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• 2024

This research investigated the preparation of activated carbon derived from Krabok (Irvingia malayana) seed shells to improve the quality of crude glycerol obtained during biodiesel production. The activated carbon was prepared using a dry chemical activation method with NaOH, utilizing an innovative biomass incinerator. The results revealed that the resulting KC/AC-two-step exhibited favorable physicochemical adsorption properties, with a high surface area of 758.72 m²/g and an iodine number of 611.10 mg/g. These values meet the criteria of the industrial product standard for activated carbon No. TIS 900-2004, as specified by the Ministry of Industry in Thailand. Additionally, the adsorption efficiency for methylene blue reached an impressive 99.35 %. This developed activated carbon was then used to improve the quality of crude glycerol obtained from biodiesel production. The experimental results showed that the KC/AC-two-step increased the purity of crude glycerol to 73.61 %. In comparison, commercially available activated carbon (C/AC) resulted in a higher crude glycerol purity of 81.19 %, as analyzed by the GC technique. Additionally, the metal content (Zn, Cu, Fe, Pb, Cd, and Na) in purified glycerol using KC/AC-two-step was below the standards for heavy metals permitted in food and cosmeceuticals by the Food and Drug Administration of Thailand and the European Committee for Food Contact Materials and Articles. As a result, it can be inferred that Krabok seed shells have favorable properties for producing activated carbon suitable as an adsorbent to enhance crude glycerol purity. Furthermore, the improved crude glycerol from this research has potential for various industrial applications.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.14 no.1
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• pp.35-42
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• 2008

Twenty eight gas impermeable plastic films for food-contact application were collected in the domestic market and material and/or migration tests for overall migration, antioxidants, potassium permanganate consumption, heavy metal, and plasticizers were carried out. The average overall migration values for NY/PE or NY/LLDPE, PETP/PE, and PVDC packaging films obtained by using n-heptane as fatty food simulant were 7.6, 6.9 and 14.1 mg/L, respectively. These values were much lower than the limit values of 150 and 30 mg/L for polyethylene and polyvinylidene chloride prescribed in the Korea Food Code. In almost of the packaging materials tested, the antioxidants such as Irganox 1010, Irganox 1076 and Irgafos 168 were found. The migration test result showed that almost of all samples except PVDC film contained Irganox 1076 and Irgafos 168, while the maximum migration value of Irganox 1076 into n-heptane was found in the Ny/PE/LLDPE(15/25/50 ${\mu}m$) sample at the concentration of 216.9 ${\mu}g/g$. From the plastic packaging samples tested, plasticizers such as DEP, DPRP, DBP, DPP, BBP, DCHP, DEHP, DEHA and observed above the detection limit. Consumption amount of potassium permanganate was much lower than the limit value of 10 mg/L. In the material test for heavy metals, cadmium and lead were determined at the concentrations far below the limit value of 100 mg/kg. The migration test for cadmium and lead showed a lower value than the detection limit. Therefore, it can be concluded that the safety status of the plastic films tested met the requirement of limit values as prescribed for the material and migration tests of food packaging utensils, containers and packages of the Korea Food Code.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.102-109
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• 2018

In the present study, a variety of polylactide (PLA) articles (n = 211) were tested for migration of lead (Pb), cadmium (Cd) and arsenic (As) into the food simulant (4% v/v acetic acid). Pb, Cd, and As were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Migration tests were performed at $70^{\circ}C$ and $100^{\circ}C$ for 30 min. The amounts of Pb, Cd, and As increased at $100^{\circ}C$ for 30 min compared with levels at $70^{\circ}C$. However, the migration at both conditions was very low. The maximum level of Pb at $100^{\circ}C$ for 30 min corresponded to 1% of the migration limit. The estimated daily intakes (EDI) based on safety evaluation ranged from $2.5{\times}10^{-5}$ to $2.0{\times}10^{-3}{\mu}g/kg\;bw/day$ for Pb, Cd, and As. The EDI calculated from migration of Pb at $100^{\circ}C$ for 30 min in PLA was the maximum value, $2.0{\times}10^{-3}{\mu}g/kg\;bw/day$, which corresponded to 0.055% of provisional tolerable weekly intake (PTWI, $25{\mu}g/kg\;bw/week$). The data from this study represent a valuable source for science-based safety control and management of hazardous heavy metals migrating from polylactide food contact materials.

• Applied Microscopy
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• v.30 no.4
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• pp.347-355
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• 2000

Zinc is one of the most abundant oligoelements in the living cell. It appears tightly bound to some metalloproteins and nucleic acids, loosely bound to some metallothioneins or even as free ion. Small amounts of zinc ions (in the nanomolar range) regulate a plentitude of enzymatic proteins, receptors and transcription factors, thus rolls need accurate homeostasis of zinc ions. Zinc is an essential catalytic or structural element of many proteins, and a signaling messenger that is released by neural activity at many central excitatory synapses. Growing evidences suggest that zinc may also be a key mediator and modulator of the neuronal death associated with transient global ischemia and sustained seizures, as well as perhaps other neurological disease stoles. Some neurons have developed mechanisms to accumulate zinc in specific membrane compartment ('vesicular zinc') which can be evidenced using histochemical techniques. Substances giving a bright colour or emitting fluorescence when in contact with divalent metal ions are currently used to detect them inside cells; their use leads to the so called 'direct' methods. The fixation and precipitation of metal ions as insoluble salt precipitates, their maintenance along the histological process and, finally, their demonstration after autometallographic development are essential steps for other methods, the so called 'indirect methods'. This study is a short report on the autometallograhical approaches for zinc detection in the central nervous system (CNS) by means of a modified selenium method.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.535-545
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• 2005

Environmental survey from some abandoned metal mine areas was undertaken on to assess the risk of adverse health effects on human exposure to arsenic influenced by past Au-Ag mining activities. Elevated levels of As were found in tailings from the studied mine areas. This high concentration may have a impact on soils and waters around the tailing piles. In order to perform the human risk assessment, chemical analysis data of soils, rice grains and waters fur As have been used. The HQ values fer As via the rice grain and groundwater consumption were significantly higher compared with other exposure pathways in all metal mine areas. However, there were minimal soil and water dermal contact risks. The resulting Hl values of As from the Dongil, Okdong and Hwacheon mine areas were higher than 5.0, and their toxic risk due to drinking water and rice grain was strong in these mine areas. The cancer risk of being exposed to As by the rice grain route from the Dongil, Okdong and Hwacheon mine areas was $5.2\times10^{-4},\;6.0\times10^{-4}\;and\;8.1\times10^{-4}$, respectively. The As cancer risk via the exposure pathway of drinking water from these mine areas exceeded the acceptable risk of 1 in 10,000 fer regulatory purposes. Thus, the daily intakes of groundwater and rice grain by the local residents from the Dongil, Okdong and Hwacheon mine areas can pose a potential health threat if exposed by long-term arsenic exposure.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.206-214
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• 2003

Purpose : To analysis each clinical results after arthroscopic ACL reconstruction with using variable fixatives which are metallic and bioabsorbable interference screw, and RIGIDfix. Therefore, We reported the clinical reliability and safty of ACL reconstruction using RIGIDfix. Materials and Methods : We evaluated the results of arthroscopic ACL resconstruction with patellar tendon autograft among three groups, of which group 1 is used metal interference screw for 44 patients, group 2 used bioabsorbable interference screw for 47 patients, group 3 used RIGIDfix for 42 patients. We compared the clinical results by physical examination (anterior drawer test, Lachman test and pivot shift test), Lysholm score and KT-2000 arthrometer and compared the radiological results by measurement of tunnel and fixatives position and widening and by MRI findings. We analyzed the results by SAS 8.2 Ducan. Tukey and paired t-test Results : Physical instability was in 5 cases, which group 2 had 4 cases and group 3 had 1 case. Lysholm score improved from 59.8. 64.4, 61 to 90.1, 92.3. 92. KT-2000 arthrometer instability improved from 9.20, 10.2, 9.5 to 1.43. 1.62. 2.00 (p=0.478). Radiologically, all cases had excellent tunnel position and cyst change was observed the 8 cases in the group 2, but, all 20 cases 2nd MRI had signal change of peri-fixatives. But, no correlation of clinical results. Conclusion : No statistical difference of clinical instability was found among three groups. And femoral tunnel changes were much observed in group I, II than III. We considered the RIGIDfix has much advantages because the short operation time, better fixation position and much bone contact surface. But, further long term follow up study was needed.

• The Journal of the Petrological Society of Korea
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• v.9 no.1
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• pp.13-28
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• 2000

Chojeong area is mainly composed of the Ogcheon Group which consists of regionally metamorphosed, age-unknown sedimentary rocks. In the northwestern parts, the Group is intruded by the Jurassic Daebo granite and Cretaceous felsic and mafic dykes. The lowermost, Midongsan Formation which consists of milky white impure quartzite, crops out along the anticline axes with N40E trend. Ungyori quartzite Formation is intercalated with quartzite and slate. Miwon Formation is most widely exposed in the area and consists mainly of phyllitic sandy rocks with a thin crystalline limestone bed. Hwajeonri Formation is divided into two parts, pelitic lower and calcareous upper parts, composed with phyllite and slate. Changri and Hwanggangri Formations are typical members of Ogcheon Group, the former bearing coally graphite seams consists mainly of black slate and phyllite with intercalated greenish grey phyllite, the latter is pebble bearing phyllite formation of which matrix and pebbles are variable in compositions and size. Biotite granite, porphyritic granite and two mica granite belong to Jurassic so-called Dabo granite. They intruded the Ogcheon Group forming vast contact metarnophic zone. Quartz porphyry, mafic dyke and felsite intruded along the marginal zone of porphyritic granite batholith and fracture of NS trend. Main structural lineaments in Ogcheon Group shows N25-45E, NS and N30-45W trends. The N25-45E trends are mainly from general ductile deformation during regional metamorphism, showing isoclinal folding, Fl foliations and lithological erosional characters. Some of these trends are due to normal faults. The NS and N30-45W trends represent brittle deformation including faults and joints. In the area of granitic batholith, NS to N30- 45 trends are from the direction of dykes. In the soils of the area, average contents of heavy metal elements such as Cd, Cr, Cu, Pb, and Zn are 0.2, 50.6, 35.5, 27.9, and 93.4 ppm respectively, which are not higher than the average values of natural soils, under the tolerable level. Enrichment Index does not show any heavy metal pollution in the area. Average depths of weathering(5m vs. 2m), porosities(43.94 vs. 51.80), densities(l.29 vs. 1.15), and permeabilities(2.52 vs. 8.07) are comparable in granite areas and in the phyllite areas of Ogcheon Group.