• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.230-230
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• 2007

전력선 통신(Power Line Communication)은 최근 전력선을 이용한 통신기술의 발달과 더불어 세계적으로 관심도가 높아지고 연구 개발 및 자본 투자가 활발히 진행되고 있으며, 안정적인 네트워크를 구성하기 위해서는 고주파 전력선 통신 신호를 차단하는 블로킹 필터가 반드시 적용되어야 한다. 전력선 통신용 블로킹 필터는 광대역의 주파수 특성과 높은 신호감쇄 특성 및 대전류 특성이 요구되며, 이러한 특성을 구현하기 위해서는 블로킹 필터의 핵심부품인 자심재료의 고투자율 및 대전류화가 이루어져야 한다. 따라서 본 연구에서는 우수한 전 자기적 특성이 균일하게 유지되고, 전력선에 흐르는 대전류에 의한 자심재료의 포화가 발생하지 않도륵 새로운 자심 재료를 설계하여, 전력선 통신을 적용한 홈 네트워크 구축의 핵심 부품인 광대역 블로킹 필터를 개발하고자 하였다. 2350과 0.3 T의 투자율과 포화자속 밀도를 갖는 EI 형상의 자심재료를 해석모델로 설정하고 다중 에어 갭의 위치에 따른 전류와 자속밀도 변화를 유한요소 해석법으로 분석한 결과 자심재료의 대전류 특성에 지배적인 영향을 미치는 에어 캡의 삽입 위치를 알 수 있었고, 새로운 해석 모델인 I 형상의 로드(ROD) 코어에 대해 수치해석을 수행하여, 100A의 통전 전류에서도 자기적으로 포화되지 않고 인덕턴스의 정밀 제어가 가능하고, 특성의 신뢰성과 대전류에 대한 안정성을 증가시킬 수 있는 인덕터를 설계하였다. 또한 수동소자를 이용한 LC 공진회로를 기본 구성으로 하고, 주파수 대역, 신호 감쇄율과 대전류 특성, 상용화를 고려하여 블로킹 필터 회로를 설계하였으며, 유한요소해석법을 적용한 전자장 모의해석을 통하여 최소의 크기를 갖는 I 형상의 자심재료에 $6{\Phi}$의 에나멜 동선을 6.5턴, 6턴 권선하여 2.5, $2.15\;{\mu}H$의 인덕턴스를 갖는 직렬 인덕터를 구현하였고 블로킹 필터를 구성하였다. 주파수에 따른 신호감쇄 특성을 5 Hz~1 MHz의 주파수 범위에서 측정한 결과 약 490 kHz~450 kHz의 주파수 대역에서 -70dB의 신호감쇄 특성을 나타냈다. 본 연구를 통해 개발된 100A급 광대역 블로킹 필터가 적용되어 상용화 될 수 있을 것으로 판단되며, 또한 모뎀 통신 주파수 대역에서 -70dB 이상의 높은 감쇄 특성을 갖기 때문에 신호차단 특성이 보다 우수할 것으로 사료된다.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.696-704
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• 2017

In this study, we investigated antioxidative and matrix metalloproteinases (MMPs) inhibitory effects of Sorbus commixta twig extracts and fermented extracts with Lactobacillus pentosus and analyzed active ingredients. The free radical scavenging activity ($FSC_{50}$) of non-fermented and fermented extracts of S. commixta twig' were 41.04 and $58.2{\mu}g/mL$, respectively. In the $Fe^{3+}-EDTA/H_2O_2$ system, the active oxygen scavenging activity ($OSC_{50}$) was 2.6 and $3.0{\mu}g/mL$, respectively. In the dermal fibroblasts, the intracellular reactive oxygen species (ROS) scavenging activity was 35.3% for non-fermented extract and 40.2% for fermented extracts at the concentration of $10{\mu}g/mL$. Also at the same concentration, the expression of MMPs (MMP-1, -2, -3) by western blot was 68.3, 35.0 and 24.2%, respectively for non-fermented extracts and 84.3, 70.5 and 69.2% for fermented extracts. TLC, HPLC, and LC/ESI-MS/MS were used for measuring the changes in the components of the extract before and after fermentation. As a result, caffeic acid, (-)-epicatechin, isoquercitrin, and quercetin were identified. From the results, S. commixta twig fermented extracts by L. pentosus showed greater ROS scavenging activity and inhibitory effects on MMPs expression than those of using non-fermented extracts. Therefore, it is suggested that S. commixta twig fermented extracts can be used as an anti-aging cosmetic material.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.176-184
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• 2018

In the present study, we investigated the antioxidative properties, cellular protective effects and component analyses of 50% ethanol extract, ethyl acetate fraction and aglycone fraction obtained from Lysimachia christinae Hance (L. christinae Hance). In the evaluation of antioxidative properties, the free radical scavenging activities ($FSC_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction were 146.8, 22.2 and $27.2{\mu}g/mL$, respectively and total antioxidant capacities ($OSC_{50}$) were 29.3, 2.9 and $4.5{\mu}g/mL$, respectively. The ethyl acetate fraction showed the highest free radical scavenging activity and total antioxidant capacity. Also, the cellular protective effects (${\tau}_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction on $^1O_2$ induced photohemolysis of human erythrocytes were 26.9, 57.5 and 103.9 min at $5{\mu}g/mL$, respectively. In particular, ${\tau}_{50}$ of the aglycone fraction exhibited a higher cellular protective effect than that of (+)-${\alpha}$-tocopherol (37.7 min). The cell viability of the ethyl acetate fraction on the UVB-induced cell damage increased up to 90.1%. In addition, the ethyl acetate fraction ($5-25{\mu}g/mL$) showed cellular protective effects on the $H_2O_2-induced$ cell damages in a dose-dependent manner. TLC, HPLC, UV-vis spectroscopy and LC-MS were used to analyse components of the ethyl acetate fraction and the main components were quercetin, kaempferol and their glycosides. In conclusion, L. christinae Hance extract/fraction can function as antioxidants to protect the skin exposed to UV radiation and may also be used as a novel functional cosmetic material, for example, an antioxidant against skin photoaging.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.379-391
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• 2022

The current study aimed to compare the pH, solubility value, and ion release capability of premixed mineral trioxide aggregates (MTAs) versus conventional pulp capping materials before and after setting. The following materials were used: resin-modified calcium silicate cement (TheraCal LC^®, TLC), resin-modified calcium hydroxide cement (Ultra-Blend^TM plus, UBP), and 2 kinds of premixed MTA (Endocem MTA^® premixed regular [EMPR] and Well-Root^TM PT [WRP]). The specimens of each material were prepared before and after setting and were immersed in distilled water. The materials' pH and solubility value were assessed. Next, three kinds of ion (calcium, sulfide, and strontium) released by pulp capping materials were evaluated via inductively coupled plasma atomic emission spectrometry. In the after-setting group, the pH of TLC and UBP decreased. However, the pH of the premixed MTAs increased with time. TLC released a higher concentration of strontium ion compared with the other materials. Meanwhile, EMPR released a significantly high concentration of sulfide ion (p < 0.05). In the after-setting group, the 2 kinds of premixed MTAs released a significantly higher concentration of calcium ion compared with the other materials (p < 0.05). In the after-setting group, EMPR had a significantly low solubility value (p < 0.05). The Kruskal-Wallis test, followed by the Mann-Whitney U test with Bonferroni correction, was used in statistical analysis. In conclusion, resin-modified calcium silicate cement, modified calcium hydroxide cement, and the 2 kinds of premixed MTAs had an alkaline pH and low solubility value and they released various concentrations of ions after setting.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.37-48
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• 2024

Songla (Usnea diffracta Vain.) is one of the lichens belonging to the genus Usnea, and pharmacological activities such as antioxidant, antimicrobial, anti-inflammatory, anti-tumor and cardiovascular protection have been reported in previous studies, but its efficacy in skin and hair is not well known. In this study, the effect of Usnea diffracta extract (UDE) on anti-aging and dermal papilla cell proliferation was verified in vitro. As a result of the experiment, it was confirmed that the UDE significantly reduced the expression of MMP-1 and the activity of MAPKs (ERK, p38, JNK) and AP-1 (c-Fos, c-Jun), which were increased by UVA in HDFn. In addition, the UDE significantly increased the proliferation of HFDPC and significantly increased the mRNA expression of VEGF and KGF, which are hair growth factors. Accordingly, the phosphorylation of ERK/CREB involved in hair proliferation and expression of growth factors was increased in a concentration-dependent manner. The main component represented by the main peak was separated and purified using Prep LC by concentrating the UDE, which was confirmed as diffractaic acid through NMR and Mess analysis. Isolated diffractaic acid significantly reduced the expression of MMP-1 increased by UVA in HDFn and increased the proliferation of HFDPC in a concentration-dependent manner. The result suggest that UDE proved its usability as a natural cosmetic material with anti-aging and dermal papilla cell activation effects.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.211-218
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• 2007

This study was carried out to develop the technique for manufacturing activated carbon from livestock manure and to analyse it's odor absorptiveness. Each of layer manure(LM), litter from broiler house(BL) and litter from dairy barn(DL), compost from layer manure(LC) and pig manure(PC), and coconut shell(CS) was used as a raw material. Activated carbon by grinding the raw material, adding the coal tar as a binder, palletizing, drying, heating with $N_2$ gas at $400^{\circ}C$ for 1 hour, activating by reaction with steam at a temperature of $750^{\circ}C$ for 1 hour. Moisture contents of raw material was 44.9% in layer compost, 71.9% in layer manure, 24.4% in broiler litter, 47% in pig manure compost and 33.9% in dairy litter. Volatile matter in layer compost, layer manure, broiler litter, pig manure compost and dairy litter was 18.8%, 31.0%, 49.8%, 22.3% and 11.6%, respectively. Surface area(BET) of activated carbon from layer compost, layer manure, broiler litter, pig manure compost, dairy litter and coconut shell was 259.8, 209.8, 63.5, 442.3, 812.9 and $1,040\;m^2/g$, respectively. Activated carbon made by livestock manure or litter were examined with scanning electron microscope, and micropore was a type of sponge like particles honeycombed with chambers. Pore size of activated carbon was ranged from 0.39 to $5.02\;{\AA}$, but coconut shell was $0.30\;{\AA}$. Iodine absorptiveness of activated carbon from livestock manure was $530{\sim}580mg/g$. But activated carbon made by coconut shell was 1000 mg/g. Each activated carbon could absorb odor compound very well. Absorptiveness of activated carbon from layer manure for hydrogen sulfide and trimethyl amino was 74.5% and 73.9% at the accumulated flux of 60,000 ml, but, in the case of ammonia was only 15.2% at the accumulated flux of 10,000 ml

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.3
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• pp.224-238
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• 2008

The aim of this study is to confirm the physicochemical property and hazard of thinner (012), which is a diluent of enamel paint used for floor coating for waterproofing and oil painting for the outer wall. The literatures of physicochemical property and hazard of thinner were surveyed and its physicochemical property were evaluated. And then, the inhalation toxicity of thinner affecting the central nervous system and reproductive organs in rats were examined by subchronic (6 h./day. 5 days/ week for 13 weeks) inhalation test. 1) According to the 13-week subchronic inhalation test, there were no significant changes in clinical test and body weight. However, a significant evidence of toxicity was observed in the hematological test and organ weight such as heart, kidney, liver and brain (p<0.01) in the 200 ppm and 1,000 ppm exposure groups in a dose response manner. In the histopathology analysis, there were no significant evidence of toxicity. Therefore, thinner was not classified as an organ targeted toxic agent. In case of Harmfulness, it could be classified as a chronic toxic agent 3($500 ppm/4hr, rat). 2) The reproductive toxicity such as extension of the period of estrous cycle, reduction of serum estradiol concentration and increase of frequency of the abnormal sperm was observed in the 1,000 ppm exposed animals. 3) The result of the physicochemical property of the test material showed that the specific gravity was 0.793, boiling point $155.8^{\circ}C$, steam pressure 2.1 kPa, ignition point $34.5^{\circ}C$, and spontaneous ignition point $280^{\circ}C$. The endothermic and exothermic values were 371.4 J/g and 159.1 J/g. respectively. The explosion limit was 214 mg/l. These data showed that thinner could be classified as an explosion agent level 1.2 and ignitive liquid agent 3 ($23-60^{\circ}C$) according to the notification No. 2008-1 of the Labor Ministry, "Classifying Standard of Chemical Materials."

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.369-379
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• 2012

The collapse of concrete structures by extreme loads such as impact, explosion, and blast from terrorist attacks causes severe property damage and human casualties. Concrete has excellent impact resistance to such extreme loads in comparison with other construction materials. Nevertheless, existing concrete structures designed without consideration of the impact or blast load with high strain rate are endangered by those unexpected extreme loads. In this study, to improve the impact resistance, the static and impact behaviors of concrete beams caste with steel fiber reinforced concrete (SFRC) with 0~1.5% (by volume) of 30 mm long hooked steel fibers were assessed. Test results indicated that the static and impact resistances, flexural strength, ductility, etc., were significantly increased when higher steel fiber volume fraction was applied. In the case of the layered concrete (LC) beams including greater steel fiber volume fraction in the tensile zone, the higher static and impact resistances were achieved than those of the normal steel fiber reinforced concrete beam with an equivalent steel fiber volume fraction. The impact test results were also compared with the analysis results obtained from the single degree of freedom (SDOF) system anaysis considering non-linear material behaviors of steel fiber reinforced concrete. The analysis results from SDOF system showed good agreement with the experimental maximum deflections.

• Journal of Environmental Health Sciences
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• v.46 no.4
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• pp.398-409
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• 2020

Objectives: This study aimed to evaluate environmental exposure to tobacco-specific nitrosamines (TSNAs) by conducting an analysis of the concentration of TSNAs in deposited dust collected from a fertilizer plant and the surrounding village, a simulation of high-temperature drying of tobacco waste, and CALPUFF modeling. Methods: The raw materials of the products, deposited dust (inside and outside the plant and residential area), soil, and wastewater were sampled and the TSNA concentrations were analyzed by LC-MS/MS. As the plant was closed down before the investigation, simulation tests were conducted to confirm the substances discharged during high-temperature (300℃) drying of tobacco waste. CALPUFF modeling was performed to identify the area of influence due to exposure to TSNAs. Results: TSNAs were detected in organic fertilizers estimated to contain tobacco waste, deposited dust, and soil collected from inside and outside the plant. N'-nitrosonornicotine (NNN), 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK), and N'-nitrosoanatabine (NAT) components were detected in five of 15 deposited dust samples collected from the residential area around the plant, while TSNAs were not detected in the five sampling points in the control area. Also, the simulation test for the high temperature drying of tobacco waste found emissions of TSNAs. The CALPUFF modeling results showed that the survey area was likely to be included in the area of influence of TSNA emissions from the plant. Conclusions: It is estimated that harmful tobacco ingredients such as TSNAs were dispersed in nearby areas due to the illegal use of tobacco waste as a raw material to produce organic fertilizers at the plant. These findings assume that the residents have been exposed to TSNAs and suggest that the need for the establishment of measures to manage environmental health.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.429-437
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• 2010

The aim of this study was to evaluate the fluoride release and microhardness of Beautifil II as giomer(Group I), F2000 Compomer as compomer(Group II), GC Fuji II LC Capsule as resin-modified glass ionomer(Group III) and $Filtek^{TM}$ Z350 as composite resin(Group IV) according to time. Forty discs(5 mm diameter and 2 mm height) were prepared for each material. Each disc was immersed in 3 ml of de-ionized water within polyethylene tube and stored at $37^{\circ}C$. Evaluations were performed by pH/ISE meter for analysis of fluoride release and hardness testing machine for analysis of microhardness over 31 days. The results can be summarized as follows : 1. For all groups except group IV, the greatest fluoride release was observed after the first day of the study period and then dramatically diminished over time. On the 7th day of the study period, fluoride release level was stabilized. 2. Group III showed the highest fluoride release among test groups and then group II, group I were followed. Significant difference in cumulative fluoride release over 31 days was found between each groups. Group IV showed no fluoride release during study period. 3. Group IV showed the highest microhardness among test groups and then group I, group II, group III were followed. Significant difference in microhardness was found between each group, except between group I and group II. 4. After 31 days, microhardness was slightly diminished in every group. However, no significant difference was found.