• KSBB Journal
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• 제22권3호
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• pp.157-161
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• 2007

본 연구는 수계에서의 생물학적 고찰이 거의 없었던 MEA 단독 물질을 전형적 활성슬러지와 Pseudomonas계 균주를 이용하여 분해특성을 분석한 것이다. 잠정적 결론으로서 첫째, MEA는 수계 유입 시 COD 및 $NH_4^+$ 농도의 상당한 증가를 유발하여 MEA는 $NH_4^+$로 78.1% 이상 전환되었다. 둘째, 공기 공급이 조절된 회분식 반응기에서 MEA 분해속도는 1000 mg/L에서 최대 19.23 mg/L/h, 고농도인 5000 mg/L에서 17.55 mg/L/h로서 미생물 순응이 담보되는 경우 큰 차이를 보이지 않았다. 셋째, 순차적 순응단계를 거쳐 MLVSS가 상대적으로 작은 조건 (최대 820 mg/L)에서도 약 3개월간 안정적 장기 운전이 가능하였고, 최대 분해율은 약 95%였다. 넷째, $COD_{cr}$를 기초로 한 반응속도론 분석에 의하면 MEA 생분해는 1차 반응에 부합하였다. 향후 MEA의 생물학적 공법을 확립하기 위해 활성슬러지 시스템의 미생물 효소분석을 통해 순응단계를 최적화하는 연구를 수행할 계획이다.

• Journal of the Korean Wood Science and Technology
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• 제28권1호
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• pp.36-41
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• 2000

목재는 2-메타크릴로일옥시에틸 이소시아네이트(MOI)와 $50-60^{\circ}C$에서 촉매존재하에서 매우 쉽게 반응하였다. 적외선 분광분석을 통하여, 목재가 MOI와 우레탄결합($1715cm^{-1}$)를 형성하고 있을 뿐만 아니라, 올레핀구조의 탄소간 이중결합 ($1635cm^{-1}$)이 존재하고 있음이 밝혀졌다. 도입된 메타크릴산기는 다른 비닐모노머와의 그래프트공중합시 반응시점으로 작용할 것이다. 또한 MOI처리목재는, MOI와의 반응에 의해 친수성이던 목재의 표면이 소수화되어 접촉각이 증대되는 결과를 낳았다. X선광전자분광분석(XPS)의 결과, 목재의 표면부위의 대부분은 MOI에 의해 개질되었음을 밝혀졌다.

• 한국의류산업학회지
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• 제19권1호
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• pp.49-60
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• 2017

In this study, change trends and specific times for change in body size were sought to be identified by using manual measurements for Korean adult women at 20 to 89 of age, along with examinations of change trends and specific times of change in body shape based on body index values. The examinations of means, deviations, and variation coefficients revealed that there was a tendency of most height related measures to decrease. In addition, combined with decrease in height, growth in weight led to increased BMI, thus resulting in increase in measures of circumference, thickness, and breadth in the torso area. The BMI trends showed that with increasing age, BMI increased, reaching the peak between the ages of 55 and 59 and then decreasing from 64 of age, with the steepest increase in BMI at ages from 50 to 54. The examination of differences in the body flatness ratio for different parts of body found that with increasing age the ratio decreased, indicating a tendency for gradual change to round body shapes. The analysis of 3D body shape found that there were more back-bends and lowered shoulder levels with age, accompanied with a tendency for more bended legs and more inclined-forward necks. The key trends in changes in body measurements by age and detailed estimates of 3D standard body shape drawn out from this study are expected to significantly contribute to establishing a basic database for generating patterns reflecting age features of Korean adult females.

• Korean Chemical Engineering Research
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• 제40권6호
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• pp.664-668
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• 2002

본 연구에서는 전해 도금되어진 활성탄소섬유(activated carbon fibers; ACFs)가 NO 환원거동에 미치는 영향에 대하여 고찰해보았다. 전해도금 시간이 증가함에 따라 탄소표면의 구리의 양은 점차 증가하였으나, 활성탄소섬유의 흡착 특성인 잘 발달된 비표면적 등의 기공구조는 약간씩 감소하는 경향을 보였다. 본 실험 결과, ACFs 및 ACFs/Cu 촉매 표면에서 $500^{\circ}C$로 NO를 반응시켰을 때 NO가 $N_2$ 및 $O_2$로 환원되는 것을 확인하였다. 특히, ACFs/Cu 촉매를 사용한 반응에서는 촉매반응 중 발생하는 산소를 촉매표면에서 잡아주는 역할을 하는 것으로 관찰되었다. 이는 NO환원에 있어서 ACFs와 ACFs/Cu 촉매 사이에 다른 기작이 있다는 것을 보여주는 것으로 생각되어진다.

• 폴리머
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• 제26권6호
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• pp.812-820
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• 2002

본 연구에서는 나노입자인 카본블랙을 고분자에 분산시킨 복합체를 각각 용액혼합과 용융혼합을 이용하여 positive temperature coefficient (PTC) 특성을 연구하였다. 전도성 나노입자인 카본블랙과 고분자 복합체의 저항 통전 (threshold)은 용융혼합하였을 때 카본블랙의 함량이 35wt% 이상에서 나타났으며. 용액혼합에서는 카본블랙 함량이 40 wt% 이상에서 나타났다. Ethyl-one vinylacetate copolymer (EVA)의 경우, 온도의 변화에 따라서 저항이 서서히 증가하다가 용융점 근처에서 극대값을 나타내었지만, high density polyethylene (HDPE)의 경우는 저항이 온도의 변화에 따라 일정하다가 용융점 근처에서 증가하기 시작하여 용융점에서 극대값을 나타내었다. 통전 후의 낮은 저항과, scanning electron microscopy (SEM)으로 관찰한 결과로부터 전도성 나노입자의 카본블랙 분산방법에서 용액혼합의 분산 정도가 용융혼합 못지않게 나타났다. PTC 소재에 전류인가시 큐리온도에서 1차적으로 저항이 증가하였으며, 고분자의 용융점에서 2차적으로 트립온도가 될 때까지 저항이 증가하다가 트립온도 이후에는 저항이 일정하게 유지됨을 알 수 있었다.

• 한국축산식품학회지
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• 제36권5호
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• pp.601-611
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• 2016

The objective of this study was to evaluate effects of Gaeddongssuk powder (GP) on quality characteristics and shelf stability of emulsion sausages during storage. Proximate composition properties showed no significant differences in all treatment (p>0.05). Control showed the highest cooking loss while the treatment with GP showed decreased cooking loss depending on increasing GP content (p<0.05). Apparent viscosity of batter was increased as the amount of GP increased, whereas hardness of emulsion sausages was decreased with increasing GP level. In sensory evaluation, emulsion sausage with 0.1% GP resulted in the highest score in overall acceptability. The pH values of all treatments decreased at the early storage stage, followed by gradual increase. The lightness and redness of treatments were decreased when the level of GP was increased. However, the yellowness of sausages with GP were higher than that of control (p<0.05). The addition of GP inhibited lipid oxidation of emulsion sausages during storage depending on its level. The aerobic bacteria population and VBN was unaffected by addition of GP during the storage (p>0.05). Therefore, Gaeddongssuk powder up to 0.1% has a potential as a natural antioxidant for meat products because it can inhibit lipid oxidation of sausages without decreasing their sensory properties.

• 한국물환경학회지
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• 제21권3호
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• pp.242-247
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• 2005

In this study, we investigated the removal efficiencies of pollutants and permeate fluxes depending on chemistry of feed water, various molecular weight cut-offs (MWCOs) and materials of membrane, operating pressure. We used seven MWCO membranes of YC0.5, YM1, YM3, YM10, YM30, YM100 and PM30, humic acid solution and surface water as feed water, and examined variation in permeate flux. Results of TOC removal experiment demonstrate that MWCO lower 1,000daltons could remove humic acid effectively. As increasing solution pH and decreasing divalent cations ($Ca^{2+}$) concentration, TOC removal increased. But $UV_{254}$ removal efficiency increased with higher divalent cation concentration and solution pH. Membrane fouling increased with increasing electrolyte (NaCl), divalent cation concentration and decreasing solution pH. In spite of initial permeate flux of the hydrophobic membrane (PM30) was higher than that of the hydrophilic membrane (YM30), flux decline of PM30 was significant during operation. At higher operating pressure, compactness of the cake layer on the membrane surface increased, resulting in gradual increase in hydraulic resistance.

• 한국균학회지
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• 제47권3호
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• pp.219-232
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• 2019

Chemicals related to hydrogen peroxide ($H_2O_2$) and nitric oxide (NO) generations were exogenously applied to Fusarium oxysporum f. sp. fragariae (Fof) causing Fusarium wilt disease in strawberry plants, and regulations of in vitro conidial germination and mycelial growth of the fungus by the chemical treatments were evaluated. $H_2O_2$ drastically reduced the conidial germination of Fof in a dose-dependent manner, and treatment with 3-amino-1,2,4-triazole (3-AT) catalase inhibitor also led to dose-dependent inhibition of conidial germination but relatively moderately. Gradual decreases in mycelial growth of Fof were found by high concentrations of $H_2O_2$, whilst exogenous 3-AT slightly increased the mycelial growth. Increasing sodium nitroprusside (SNP) NO donor, $N^G$-nitro-l-arginine methyl ester (L-NAME) NO synthase (NOS)-inhibitor and tungstate nitrate reductase (NR) inhibitor led to dose-dependent reductions in conidial germination of Fof in quite different levels. SNP conversely increased the mycelial growth but increasing L-NAME moderately decreased the mycelial growth. Tungstate strongly enhanced mycelial growth. Differentially regulated in vitro mycelial growths of Fof were demonstrated by SNP, L-NAME and tungstate with or without $H_2O_2$ supplement. Superoxide anion production was also regulated during the mycelial growth of Fof by nitric oxide. These results show that $H_2O_2$ and NO-associated enzymes can be suggested as fungal growth regulators of Fof as well as eco-friendly disease-managing agents in strawberry production fields.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.192-199
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• 2021

Alpine glaciers harbor a large quantity of bio-labile dissolved organic matter (DOM), which plays a pivotal role in global carbon cycling as glacial-fed streams are headwaters of numerous large rivers. To understand the complexity, origin, and fate of DOM in glaciers and downstream-linked streams and lakes, we elucidated the molecular composition of DOM in two different Tibetan Plateau glaciers, eight glacial-fed streams and five lakes, using an ultrahigh-resolution 15 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The compositional changes of the DOM samples revealed that glacier DOM mostly exhibited sulfur-containing organic compounds (CHOS species). We also found that aliphatic formulae contributed more than 50% of the total abundance of assigned molecules in glacier samples, and those compounds were significantly related to CHOS species. The CHO proportions of glacial-fed streams and lakes samples increased with increasing distance from glacial terminals. The relative contribution of terrestrial-derived organics (i.e., lignins and tannins) declined while microbial-originated organics (aliphatics) increased with increasing elevation. This suggested the gradual input of allochthonous materials from non-glacial environment and the degradation of microbe-derived compounds along lower elevations. Alpine glaciers are retreating as a result of climate change and they nourished numerous streams, rivers, and downstream-linked lakes. Therefore, the interpretations of the detailed molecular changes in glacier ice, glacial-fed streams, and alpine lakes on the Tibetan Plateau could provide broad insights for understanding the biogeochemical cycling of glacial DOM and assessing how the nature of DOM impacts fluvial ecosystems.

• Geomechanics and Engineering
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• 제24권2호
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• pp.179-191
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• 2021

In this study, the strength and failure mechanism of red sandstones with combined defects were investigated by uniaxial compression tests on red sandstones with different crack angles using two-dimensional particle flow code numerical software, and their mechanical parameters and failure process were studied and analyzed. The results showed that the mechanical characteristics such as peak strength, peak strain, and elastic modulus of the samples with prefabricated combined defects were significantly inferior than those of the intact samples. With increasing crack angle from 15° to 60°, the weakening area of cracks increased, elastic modulus, peak strength, and peak strain gradually reduced, the total number of cracks increased, and more strain energy was released. In addition, the samples underwent initial brittle failure to plastic failure stage, and the failure form was more significant, leading to peeling phenomenon. However, with increasing crack angle from 75° to 90°, the crack-hole combination shared the stress concentration at the tip of the crack-crack combination, resulted in a gradual increase in elastic modulus, peak strain and peak strength, but a decrease in the number of total cracks, the release of strain energy reduced, the plastic failure state weakened, and the spalling phenomenon slowed down. On this basis, the samples with 30° and 45° crack-crack combination were selected for further experimental investigation. Through comparative analysis between the experimental and simulation results, the failure strength and final failure mode with cracks propagation of samples were found to be relatively similar.