• Journal of Korea Foundry Society
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• v.33 no.3
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• pp.122-126
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• 2013

Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1551-1554
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• 2004

In the presence of laccase, low molecular weight (M.W.) fractions from lignosulfonate (M.W. 97 kD) were produced. By Sephadex column chromatography, four lower M.W. fractions of 9 kD, 1.8 kD, 1 kD and 0.85 kD were identified. The addition of acetovanillone (AV) or acetosyringone (AS) enhanced to the degradation of lignosulfonate with fungal laccase. During this process, there were found new generation of lower M.W. fractions, e.g. approximately 20 kD, 1.8 kD, 1 kD and 0.85 kD for AV, and 20 kD, 3 kD, 1 kD and 0.85 kD for AS, respectively. The quantities of lower M.W. products (especially the fractions of M.W. 1 kD and 0.85 kD) were larger than those in the controls. Also, its degradation became more active in the presence of AS than AV. The presence of AS or AV seems to prevent the re-polymerization of degraded lignosulfonate by the laccase.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.145-152
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• 2021

Microbial bioconversion using lactic acid bacteria (LAB) provides several human health benefits. Although whey and whey-derived bioactive compounds can contribute to an improvement in human health, the potential anti-obesity effect of whey bioconversion by LAB has not been well studied. This study aimed to investigate whether bioconversion of whey by Pediococcus pentosaceus KI31 and Lactobacillus sakei KI36 (KI31-W and KI36-W, respectively) inhibits 3T3-L1 preadipocyte differentiation. Both KI31-W and KI36-W reduced intracellular lipid accumulation significantly, without decreasing 3T3-L1 preadipocyte proliferation. In addition, obesity-related transcription factor (peroxisome proliferator-activated receptor γ) and genes (adipocyte fatty acid-binding protein and lipoprotein lipase) were down-regulated significantly in 3T3-L1 cells in the presence of KI31-W and KI36-W. Collectively, these results suggest that bioconversion of whey by LAB exhibits anti-adipogenic activity and may be applied as a therapeutic agent for obesity.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4404-4411
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• 2024

The dissolved oxygen in a coolant can affect the oxidation properties of structural materials. A desirable oxide phase formation is achieved by manipulating the oxygen level in the coolant, which can mitigate structural material degradation in nuclear power plants. Therefore, the role of dissolved oxygen in the corrosion of structural materials in aqueous environments needs to be understood. In this study, a short-term corrosion test (up to 300 h) of Ferritic/Martensitic steels (F/M steels; FeCrW model alloys), namely, Fe12Cr1W, Fe9Cr1W, and Fe9Cr, in stagnant water at 360 ℃ was performed in a pressurized autoclave with the dissolved oxygen concentration controlled to 1 ppm or a very low level (<1 ppm). The results of the corrosion tests showed that an increase in the oxygen level in the water elevated the corrosion potential, allowing the phase transition of iron oxide from magnetite (Fe₃O₄) to hematite (Fe₂O₃), whereas there was no significant correlation between the concentrations of the alloying elements Cr and W and the oxide growth rate. In addition, hematite was found to mitigate further oxide growth. Finally, a mechanism for the growth of the initial oxide layer was proposed based on the experimental results.

• Culinary science and hospitality research
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• v.19 no.2
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• pp.203-214
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• 2013

This study was performed to examine the optimum addition amount of saltwort(Salicornia herbacea L.) powder to rice flour in the preparation of saltwort Sulgidduk. Saltwort powder was added to rice powder at ratios of 5, 10, 15 and 20%(w/w). The moisture contents of Sulgidduk were increased with the addition of saltwort powder. The pH contents of Sulgidduk were decreased with the addition of saltwort powder. The incorporation of saltwort powder in Sulgidduk lowered the lightness but increased the redness values. Mineral contents of Sulgidduk were increased with the addition of saltwort powder. The hardness and brittleness were decreased, whereas cohesiveness was increased with the addition of saltwort powder. In the sensory evaluation of saltwort Sulgidduk, the acceptance of flavor, taste, chewiness and overall acceptability characteristics was the highest at the 5% level. Saltwort Sulgidduk, with the addition of 5% of saltwort powder to rice flour was found to be the best recipe in terms of the sensory qualities.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.5
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• pp.499-506
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• 2019

This paper is concerned with the operating stability of 7kW inverter using SIC hybrid module and verifies the validity of the simulation results by comparing the result of the loss equation and the simulation result, Simulation results using Si module and SiC hybrid module are compared to compare switch loss and diode loss. Through the loss equation calculation, the conduction loss of SiC Hybrid module is 168W, switching loss is 9.3W, diode loss is 10.5nW, When compared with the simulation results, similar values were shown. As a result of comparing the simulation results of the Si module and the SiC Hybrid module, The total device loss of the Si module was 246.2W, and the total device loss of the SiC Hybrid module was 189.9W. The loss difference was 56.3W, which was about 0.8W. thereby verifying the reverse recovery characteristics of the SiC SBD. In addition, temperature saturation test was conducted to confirm the stability of SiC Hybrid module and Si module under high temperature saturation, In the case of the Si module, the output power was stopped at 4kW, and the SiC Hybrid module was confirmed to operate at 7kW. Based on this, an efficiency graph and a temperature graph are presented, and the Si module is graphed up to 4kW and the SiC Hybrid module is graphed up to 7kW.

• Journal of Embryo Transfer
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• v.21 no.2
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• pp.121-128
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• 2006

In this study, we examined the effects of molecular weight, concentrations and treat the duration of polyvinylpyrrolidone (PVP) in vitro maturation (IVM) medium (Experiment 1), and the effect of PVP in IVM, in vitro fertilization (IVF) and in vitro culture (IVC) medium on the development and cell number of porcine embryos (Experiment 2). The base mediums were NCSU 23 solution for IVM, mTBM solution for IVF and PZM3 solution for IVC. In experiment 1, the development rates to 2 cell and blastocyst stage were not differ from the different molecular weight (MW), concentration and duration of PVP in IVM medium. However, the hatching rate of blastocyst was significantly higher in the group of MW 40,000, 0.5% and $0{\sim}44hr$ than in the other groups (p<0.05). In experiment 2, the results of IVM, IVF and IVC medium with (W) or without (W/O) 0.5% MW 40,000 PVP are follows. The development rate to 2 cell stage was highest in the group of W-W/O-W (p<0.05). The development rate to blastocyst and hatching rate was higher in the group of W-W/O-W and W-W/O-W/O than that of other treatments (p<0.05).

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.68-69
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• 1998

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.260-263
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• 2002

이 연구는 과량의 유분(dodecane)으로 오염된 토양을 효율적으로 정화시키기 위한 화학적 토양세정(soil flushing)에서 알코올 성분에 의한 유동성을 고찰한 것이다. 탄소수가 다른 알코올 (methanol, ethanol, butanol)과 Tween-80 계면활성제를 세정용액으로 사용하여 혼합비, 조용매 종류 및 체류시간에 따른 세정결과를 도시하였다. 조용매 사용시 세척효율은 최대 94%(Butanol/Tween-80(w/w)=0.1) 이었다. 체류시간의 연장은 재흡착되는 admicelle의 증가로 말미암아 세정효율을 감소시키는 것으로 나타났다.

• Bulletin of the Korean Mathematical Society
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• v.54 no.2
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• pp.633-646
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• 2017

Recently, Curto, Lee and Yoon considered the properties (such as, hyponormality, subnormality, and flatness, etc.) for 2-variable weighted shifts and constructed several families of commuting pairs of subnormal operators such that each family can be used to answer a conjecture of Curto, Muhly and Xia negatively. In this paper, we consider the weak and quadratic hyponormality of 2-variable weighted shifts ($W_1,W_2$). In addition, we detect the weak and quadratic hyponormality with some interesting 2-variable weighted shifts.