• Journal of Korean Dental Science
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• v.14 no.2
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• pp.51-60
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• 2021

Purpose: Measuring viability of a three-dimensional in vitro organotypic human oral tissue model has been suggested as an alternative test method to the oral mucosa irritation test of oral care products. The aim of this study was to investigate the production of two different cytokines using organotypic human oral tissue model following exposure to chemicals that are commonly used in oral care products. Materials and Methods: The organotypic human oral tissues were exposed to ethanol, sodium lauryl sulphate or hydrogen peroxide for 90 minutes. Following exposure, interleukin (IL)-1α and IL-8 productions were assessed and correlated with cell viability testing as well as histology of the organotypic human oral tissues. Result: High levels of IL-8 were released from organotypic human oral tissues in all of the test and control groups without any significant differences between them. In contrast, differences were found in IL-1α release between the test and control groups. Additionally, the trend of IL-1α release corresponded to the phenotypes observed in histological analysis while different trend existed between IL-1α release and cell viability. Conclusion: The study concluded the non-specific release of IL-8 for the assessment of oral care product chemicals' toxicity, while potential of measuring IL-1α cytokine level as the possible alternative test method.

• Mycobiology
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• v.50 no.5
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• pp.345-356
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• 2022

The fungal distribution, diversity, and load were analyzed in the geographically segregated island groundwater systems in Korea. A total of 79 fungal isolates were secured from seven islands and identified based on the internal transcribed spacer (ITS) sequences. They belonged to three phyla (Ascomycota, Basidiomycota, and Chlorophyta), five classes, sixteen orders, twenty-two families, and thirty-one genera. The dominant phylum was Ascomycota (91.1%), with most fungi belonging to the Cladosporium (21.5%), Aspergillus (15.2%), and Stachybotrys (8.9%) genera. Cladosporium showed higher dominance and diversity, being widely distributed throughout the geographically segregated groundwater systems. Based on the diversity indices, the genera richness (4.821) and diversity (2.550) were the highest in the groundwater system of the largest scale. As turbidity (0.064-0.462) increased, the overall fungal count increased and the residual chlorine (0.089-0.308) had low relevance compared with the total count and fungal diversity. Cladosporium showed normal mycelial growth in de-chlorinated sterilized samples. Overall, if turbidity increases under higher fungal diversity, bio-deterioration in groundwater-supplying facilities and public health problems could be intensified, regardless of chlorine treatment. In addition to fungal indicators and analyzing methods, physical hydrostatic treatment is necessary for monitoring and controlling fungal contamination.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.7-10
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• 2023

최근 기후 변화가 심각해짐에 따라 수소 에너지에 대한 관심이 집중되고 있으며 이를 안전하게 운송/보관할 수 있는 용기에 대한 연구도 활발히 진행되고 있다. 특히 고압 가스를 저장하는 TypeIII 용기의 노후화 및 안전과 관련되어 결함을 인지하는 연구가 활발하다. 그러나 이 용기의 외각층을 이루는 CFRP 소재는 탄소 섬유와 에폭시가 복잡한 구조로 구성되어 결함별 탐지가 매우 어렵다. 본 논문에서는 음향방출시험과 딥러닝을 활용하여 CFRP 결함 데이터셋을 구축하고 이를 분류할 수 있는 모델을 제안한다. 특히 CFRP 시편을 직접 제작하여 AE 센서를 부착하고 파괴하여 파형 데이터를 수집하였다. 이후 표현 학습을 통해 데이터의 특징을 압축/추출하고 유사도를 비교해 결함별 데이터를 판별하는 알고리즘을 개발하였다. 구축된 데이터셋의 실루엣 계수는 0.86으로 높은 군집도를 보였다. 마지막으로 구축된 데이터셋을 실시간으로 분류할 수 있는 1D-CNN 딥러닝 모델을 개발하였으며 99.33%의 높은 분류 정확도를 보였다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.290-291
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• 2022

본 논문에서는 우리나라 2030년 국가 온실가스 감축목표(NDC*, 291백만톤 감축)달성 및 2050년 탄소중립 목표 달성을 위해 필연적으로 수반되는 천연가스 내 수소 혼입에 따른 안전성확보 방안과 수소혼입에 따른 국민 불안감 해소 및 수용성 제고를 위한 대안을 제시하고, 해외 사례를 연구 하였다. 탄소중립은 온실가스(이산화탄소 등)의 배출량을 최대한 줄이고, 남은 온실가스를 흡수, 제거해서 실질적인 배출량이 "0"이 되는 것을 의미하고, 수소혼입은 도시가스의 주성분인 메탄 연소시 발생하는 CO₂를 최소화하기 위해 수소(H₂)를 도시가스에 일정비율 혼합하는 것을 말한다. 본 연구에서는 수소 혼입 시 우려되는 수소취성 및 배관내구성 문제와 수소 특성인 작은 입자로 인한 누출 위험성, 고층에서 메탄과 수소가 분리되는 현상 등에 따른 문제를 도출하고 이에 대한 안전관리 방안도 함께 제시하였다. 또한, 도시가스 배관에 수소 혼입시 천연가스 대체를 통한 온실가스 감축 및 기존 배관망 사용을 통한 경제성 분석결과와 국가 온실가스 감축에 어느 정도 기영할 수 있는지도 함께 기술하였다.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1513-1525
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• 2024

An improved mitigation system for thermally-induced steam generator tube rupture accidents was introduced to prevent direct environmental release of fission products bypassing the containment in the OPR1000. This involves injecting bypassed steam into the containment, cooling, and decontaminating it using a water coolant tank. To evaluate its performance, a severe accident analysis was performed using the MELCOR 2.2 code for OPR1000. Simulation results show that the proposed system sufficiently prevented the release of radioactive nuclides (RNs) into the environment via containment injection. The pool scrubbing system effectively decontaminated the injected RN and consequently reduced the aerosol mass in the containment atmosphere. However, the decay heat of the collected RNs causes re-vaporization. To restrict the re-vaporization, an external water source was considered, where the decontamination performance was significantly improved, and the RNs were effectively isolated. However, due to the continuous evaporation of the feed water caused by decay heat, a substantial amount of steam is released into the containment. Despite the slight pressurization inside the containment by the injected and evaporated steam, the steam decreased the hydrogen mole fraction, thereby reducing the possibility of ignition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.9
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• pp.1297-1301
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• 2005

This study was carried to develop the new functional food material by exploring natural antioxidant substances of Crotalaria sessiflora L. We compared antioxidative activity of potential antioxidant substances extracted from Crotalaria sessiflora L. The order of extract yield of Crotalaria sessiflora L. were stem > loaves > seed > root. Antioxidative activities of Crotalaria sessiflora L. were measured by total polyphenol contents EDA (electron donating activity), SOD (superoxide dismutase) -like activity, hydroxyl radical scavenging ability and hydrogen peroxide radical scavenging ability. Total polyphenol acid content was much higher in leaves Ex than other extracts. And leaves Ex showed the most excellent antioxidative activity ($86.27\%$) in terms of SOD-like activity. The EDA was ordered loaves Ex > stem Ex > seed Ex > root Ex. Hydroxy radical scavenging ability was the most effective in loaves Ex, and hydorogen Peroxide radical scavenging ability was the highest in seed Ex. Therefore we could be certain that leaves Ex was the most effective in antioxidative activity from Crotalaria sessiflora L.

• Journal of Food Hygiene and Safety
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• v.22 no.2
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• pp.127-131
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• 2007

This study evaluated the bactericidal effect of 10 sanitizers and disinfectants such as ethanol (75 and 95%), iodine (15 and 25 ppm), chlorine (100 and 200 ppm), quaternary ammonium, acid, hydrogen peroxide, and peroxide acetic acid against V. parahaemolyticus. Ten strains of V. parahaemolyticus isolated from Korean foods and 4 strains of standard V. parahaemolyticus were compared for efficacies of various sanitizers and disinfectants by EN 1276 method based on quantitative suspension test. Ethanol (75 and 95%), 25 ppm of iodine, 100 ppm of quaternary ammonium, 145 ppm of hydrogen peroxide and acid showed more than $5log_{10}CFU/mL$ reduction in both clean and dirty conditions. Tests result of chlorine (100 ppm) showed more than $5log_{10}CFU/mL$ reduction in clean condition. Iodine (15 ppm) showed more than $5log_{10}CFU/mL$ reduction except 4 isolated and 1 standard V. parahaemolyticus in clean condition. iodine (15 ppm) also showed under $5log_{10}CFU/mL$ reduction $(0.93{\sim}3.73log_{10}CFU/mL)$ in dirty condition. Eleven hundred ppm of hydrogen peroxide was evaluated as weak sanitizer and disinfectant due to their $0.99{\sim}4.79log_{10}CFU/mL$ reduction on both clean and dirty conditions. Consequently, ethanol, iodine (25 ppm), chlorine (200 ppm), quaternary ammonium, acid and peroxide acetic acid were thought to be effective sanitizer and disinfectant against V. parahaemolyticus.

• Restorative Dentistry and Endodontics
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• v.36 no.4
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• pp.306-312
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• 2011

Objectives: This clinical study evaluated the effect of light activation on the whitening efficacy and safety of in-office bleaching system containing 15% hydrogen peroxide gel. Materials and Methods: Thirty-three volunteers were randomly treated with (n = 17, experimental group) or without light activation (n = 16, control group), using Zoom2 white gel (15% $H_2O_2$, Discus Dental) for a total treatment time of 45 min. Visual and instrumental color measurements were obtained using Vitapan Classical shade guide and Shadepilot (DeguDent) at screening test, after bleaching, and 1 month and 3 month after bleaching. Data were analyzed using t-test, repeated measure ANOVA, and chi-squared test. Results: Zoom2 white gel produced significant shade changes in both experimental and control group when pre-treatment shade was compared with that after bleaching. However, shade difference between two groups was not statistically significant (p > 0.05). Tooth shade relapse was not detected at 3 months after bleaching. The incidence of transient tooth sensitivity was 39.4%, with being no differences between two groups. Conclusions: The application of light activation with Zoom2 white gel system neither achieved additional whitening effects nor showed more detrimental influences.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.404-411
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• 2019

This study was carried out to investigate the antioxidant effects of extracts from 9 species of forest plants in Korea. DPPH, ABTS, $NaNO_2$, hydrogen peroxide radical scavenging activity and reducing power activity were evaluated to measure the antioxidant activities of plant extracts. As a result, Geranium thunbergii has been identified as the most effective antioxidant resource. Also, total phenolic content was highest in Geranium thunbergii ($303.94{\pm}0.63mg\;GAE/g$) among 9 species extracts. Total flavonoid content was highest in Rosa multiflora ($24.32{\pm}0.22mg\;QE/g$) and proanthocyanidin content was highest in Vitis ficifolia ($279.00{\pm}4.58mg\;CE/g$) among 9 species extracts. In addition, the protective effect of plant extracts in $H_2O_2-induced$ human dermal fibroblast (HDF) cell systems were also assessed. Significant protective effects in $H_2O_2-induced$ human dermal fibroblast (HDF) cell systems were found in all plant extracts, especially in Geranium thunbergii. These results suggest that Geranium thunbergii could be a potential natural resource for antioxidant activity.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.23-29
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• 2017

As the Enforcement Ordinance of Environmental Policy Act was revised in 2013, Total Organic Carbon (TOC) was added as an indicative parameter for organic matter in Water and Aquatic Ecosystem Environmental Criteria. Under these imminent circumstances, a regulatory standard is needed to achieve the proposed TOC limitation control water quality from the STP (Sewage Treatment Plant). In this study, a electrolysis utilizing the electrochemical reaction was investigated in lab-scale experiments for the treatment of TOC in sewage effluent. TOC reduction by a electrolysis was investigated response surface methodology using the Box-Begnken methods were applied to the experimental results. A central composite design was used to investigate the effects of the independent variables of electrode space ($x_1$), current density ($x_2$) and electrolyte concentration ($x_3$) on the dependent variables removal efficiency of TOC (y). The optimal conditions for electrolysis were determined: electrode space, current density and electrolyte concentration were 50 mm, $10.3mA/cm^2$ and 0.1M, respectively. Statistical results showed the order of significance of the independent variables to be electrode space > current density > electrolyte concentration.