• 한국염색가공학회지
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• 제34권3호
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• pp.173-184
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• 2022

In this study, the TPU film was laminated on an aramid fabric or circular knits in order to implement an air cushion material that can respond to high impact forces in case of a fall and is easy to expand. To increase the bonding strength between the fabric layer and the film layer, a primer layer was formed in two ways: one for thermally bonding and laminating PET film and two for coating and aging hot melt type PUR adhesive. The tensile strength of the aramid air cushion was 2.5 times higher than that of the circular knits, but the tensile elongation of the aramid air cushion was very low compared to that of the circular knits. The tear strength of the aramid air cushion was about twice or more superior to that of the circular knits, the primer treatment method was good at A, and the peel strength was excellent at method A. The aramid air cushion was the lightest in weight. Summarizing the above results, it was best to combine the air cushion material with aramid woven fabric and primer treatment method A to cope with the high impact force applied when falling.

• 한국안전학회지
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• 제37권6호
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• pp.81-88
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• 2022

It is necessary to better understand the effect of age-related degradation on the performance of reinforced concrete shear walls in nuclear power plants in order to ensure their structural safety in the event of earthquakes. Therefore, this paper studies seismic fragility of the typical shear wall in nuclear power plants under earthquake excitation Reinforced concrete shear wall is composed of wall, horizontal and vertical flanges. Due to characteristics of its geometry, it is difficult to predict the ultimate behavior of shear wall under earthquake excitation. In this study, for more realistic numerical simulation, the Latin Hyper-Cube (LHC) simulation technique was used to generate uncertain variables for the material properties of concrete shear walls. The effects of crack, characteristics of inelastic behavior of concrete, and loss of cross section were considered in the nonlinear finite element analysis. The effects of aging-related deterioration were investigated on the performance of reinforced concrete shear walls through analysis of undegraded concrete shear walls and degraded concrete shear walls. The resulting seismic fragility curves present the change of performance of concrete shear wall due to age-related degradation.

• 급식외식위생학회지
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• 제3권1호
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• pp.1-7
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• 2022

As one of the post-COVID-19 response strategies, representative processed products derived from the natural plant material flaxseed and a dietary supplement fortified with female hormones (estrogens) were developed in Canada, an eco-friendly country was introduced. These products were: 1) flaxseed oil to help maintain cognitive and immune function, 2) Lignan50, a substance with effects similar to estrogen, a female hormone, 3) XanFlax, a thickener for confectionery/baking and egg substitute, 4) MediFlax, a constipation reliever, 5) SesaFlax, which has a fragrance similar to sesame, 6) Linusorb, which is effective for its pharmaceutical anti-inflammatory/anti-oxidation and anti-aging properties, and 7) LinuLyte, a water/electrolyte supplement containing high dietary fiber. It is expected that these dietary products will help maintain and promote health as part of a response to the COVID-19 pandemic.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.80-99
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• 2023

This paper presents the results of investigating the change in welding residual stresses of the core shroud, which is one of subcomponents in reactor vessel internals, performing finite element analysis. First, the welding residual stresses of the core shroud were calculated by applying the heat conduction based lumped pass technique and finite element elastic-plastic stress analysis. Second, the temperature distribution of the core shroud during the normal operation was calculated by performing finite element temperature analysis considering gamma heating. Third, through the finite element viscoelastic-plastic stress analysis using the calculated temperature distribution and setting the calculated residual stresses as the initial stress state, the variation of the welding residual stresses was derived according to repeating the normal operation. In the viscoelastic-plastic stress analysis, the effects of neutron irradiation on mechanical properties during the cyclic normal operations were considered by using the previously developed user subroutines for the irradiation agings such as irradiation hardening/embrittlement, irradiation-induced creep, and void swelling. Finally, the effect of neutron irradiation on the welding residual stresses was analysed for each irradiation aging. As a result, it is found that as the normal operation is repeated, the welding residual stresses decrease and show insignificant magnitudes after the 10^th refueling cycle. In addition, the irradiation-induced creep/void swelling has significant mitigation effect on the residual stresses whereas the irradiation hardening/embrittlement has no effect on those.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.369-376
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• 2023

The quick-charging performance of SiO electrodes is evaluated with a focus on solid electrolyte interphase (SEI)-reinforcing effects. The study reveals that the incorporation of fluoroethylene carbonate (FEC) into the SiO electrode significantly reduced the electrode fatigue, which is from the the viscoelastic properties of the FEC-derived SEI film. The impact of FEC is attributed to its ability to minimize the mechanical failure of the electrode caused by additional electrolyte decomposition. This beneficial outcome arises from volumetric stain-tolerant characteristics of the FEC-derived SEI film, which limited exposure of the bare SiO surface during 0.5 C-rate cycling. Notably, FEC greatly improves Li deposition during quick-charge cycles following aging at 0.5 C-rate cycling due to its ability to maintain a strong electrical connection between active materials and the current collector, even after extended cycling. Given these findings, we assert that mitigating SEI layer deterioration, which compromises the electrode structure, is vital. Hence, enhancing the interfacial attributes of the SiO electrode becomes crucial for maintaining kinetic efficiency of battery system.

• 한국의사학회지
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• 제35권2호
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• pp.19-34
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• 2022

Objectives : The purpose of this study was to compare the prescriptions used for insomnia in Uihagimmun and Donguibogam. Methods : In Uihagimmun, 17 prescriptions were selected. If there was a change in the medicinal material, the altered herbal medicine was indicated along with the prescription name. In Donguibogam, 14 prescriptions were selected. Each prescription was analyzed by dividing it into prescription composition, and herbal medicine. Medications constituting a prescription were classified according to the classification of Korean herbal medicines and arranged based on their frequency of appearance. Result : The causes of insomnia were classified mainly as exhaustion in Uihagimmun and as exhaustion, stress, low energy, aging and discomfort in Donguibogam. In Uihagimmun, numerous medicines were used to relieve fever, and in Donguibogam, the use of stabilizers increased. More warm medicines were used in Donguibogam than in Uihagimmun, and the taste trend was similar in each. Conclusions : The types of causes of insomnia increased more in Donguibogam than Uihagimmun. Accordingly, the two books showed differences in drug classification and properties of a medicine. However, in terms of taste and action of medicinal herbs, they showed similar patterns, and there was only a difference in the order of frequency.

• 한국공간구조학회논문집
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• 제23권4호
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• pp.81-88
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• 2023

Numerous factors contribute to the deterioration of reinforced concrete structures. Elevated temperatures significantly alter the composition of the concrete ingredients, consequently diminishing the concrete's strength properties. With the escalation of global CO2 levels, the carbonation of concrete structures has emerged as a critical challenge, substantially affecting concrete durability research. Assessing and predicting concrete degradation due to thermal effects and carbonation are crucial yet intricate tasks. To address this, multiple prediction models for concrete carbonation and compressive strength under thermal impact have been developed. This study employs seven machine learning algorithms-specifically, multiple linear regression, decision trees, random forest, support vector machines, k-nearest neighbors, artificial neural networks, and extreme gradient boosting algorithms-to formulate predictive models for concrete carbonation and thermal impact. Two distinct datasets, derived from reported experimental studies, were utilized for training these predictive models. Performance evaluation relied on metrics like root mean square error, mean square error, mean absolute error, and coefficient of determination. The optimization of hyperparameters was achieved through k-fold cross-validation and grid search techniques. The analytical outcomes demonstrate that neural networks and extreme gradient boosting algorithms outshine the remaining five machine learning approaches, showcasing outstanding predictive performance for concrete carbonation and thermal effect modeling.

• 품질경영학회지
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• 제51권4호
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• pp.735-749
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• 2023

Purpose: The purpose of this study is to derive solutions and prevent similar cases from occurring by analyzing the causes of cracks found in temperature cycling tests of rocket motor. Methods: By combining the results of the current state confirmation test, non-destructive test, domestic and foreign rocket motor comparison test, cutting test, and adhesion test according to the number of times to apply mold release agent, a Cause and Effect Diagram analysis was performed to derive the cause of cracks. Results: Through this study, 26 factors that could cause cracking in rocket motors during temperature cycling tests were identified. Through various additional test results, a total of five causes were identified, including chemical and structural design of the joint between the propellant and stress relief insert, omission of procedure in the manufacturing procedures, natural aging due to temperature, and load accumulation due to temperature changes. The fundamental cause was confirmed to be insufficient consideration of the release properties of the propellant and stress relief insert. Conclusion: During the design process, it was confirmed that this could be solved by structurally or chemically designing the insert so that it does not combine with the propellant, or by applying a mold release agent during the manufacturing process.

• 한국식생활문화학회지
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• 제39권1호
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• pp.74-81
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• 2024

Ulcerative colitis (UC) is a chronic inflammatory intestinal disease characterized by an imbalance in immune function and the overexpression of inflammatory cytokines and mediators. Vitamin B2, also known as riboflavin (Libof), is an essential water-soluble vitamin with numerous beneficial properties, including antioxidant, anti-aging, anti-inflammatory, anti-nociceptive, and anti-cancer effects. In this study, we aimed to investigate the protective effects of Libof on dextran sulfate sodium (DSS)-induced experimental colitis. The C57BL/6 mice were used as the in vivo model of chronic colitis to investigate the anti-inflammatory effects of Libof. RAW 264.7 cells were used for the in vitro investigation of the molecular mechanisms underlying these effects. In vivo, Libof alleviated the DSS-induced disease activity index (DAI), colon length shortening, and colonic pathological damage. In vitro, Libof inhibited lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production in RAW 264.7 cells. Moreover, Libof inhibited LPS-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in RAW 264.7 cells. In conclusion, these findings indicate that Libof shows potential as an agent for the treatment of UC.

• 한국식품영양과학회지
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• 제46권1호
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• pp.61-67
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• 2017

치아시드는 오메가-3 지방산 및 식이섬유가 풍부한 식품이며 물에 넣었을 때 투명한 막을 형성하는 특성이 있다. 본 연구에서는 치아시드의 성질이 설기떡 제품이 미치는 영향을 알아보기 위하여 치아시드 분말의 첨가량을 달리하여 설기떡을 제조하고 품질 특성 및 항산화 활성을 검토하였다. 치아시드의 첨가는 수분함량에 영향을 주지 않았으며, pH는 치아시드 첨가군이 대조군보다 감소하는 경향을 보였다. 색도 측정 결과 치아시드 분말 첨가량에 따라 L값은 감소하고 a, b값은 증가하여 ${\Delta}E$는 증가하는 결과를 나타내었다. 조직감 측정에서는 경도 및 씹힘성에서 치아시드 분말 첨가군이 대조군보다 낮게 나타났다. 반면 탄력성은 치아시드 분말 첨가군이 대조군보다 더 높게 나타났으며, 응집성은 모든 시료에서 유의적인 차이를 보이지 않았다. 저장기간에 따른 경도 변화를 통해 노화도를 분석한 결과, 치아시드를 첨가하였을 때 CSP5에서 가장 좋은 효과가 나타났으며, 치아시드를 첨가하였을 때 설기떡의 노화 억제 효과가 있는 것으로 확인되었다. 소비자 기호도 분석에서는 색, 촉촉함, 씹힘성, 향미, 단맛, 전반적인 기호도 등 모든 항목에서 시료 간에 유의적인 차이를 보이지 않았으며 점수도 4(보통) 이상을 받아, 치아시드를 부재료로 첨가하였을 때 거부감이 거의 없을 것으로 추측된다. 한편 항산화성 분석을 위하여 총 폴리페놀 및 플라보노이드 함량을 측정한 결과 치아시드 첨가량에 따라 유의적으로 증가하는 경향을 보였으며, DPPH, ABTS 라디칼 소거 활성도 증가하였다. 이상의 결과는 치아시드를 설기떡에 첨가하면 설기떡이 더 부드러워져 떡의 노화 현상이 억제되며, 항산화 활성이 좋아지는 효과를 얻어 기능성 떡 제조의 가능성을 보인다. 또한, 설기떡에 치아시드를 5% 첨가하였을 때 노화 억제 효과와 항산화 물질 함량이 높아 제품화에 가장 적합한 것으로 생각한다.