• Fibers and Polymers
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• 제4권4호
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• pp.188-194
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• 2003

Phase behavior and spinodal phase separation kinetics in binary blends of a random copolymer of vinylidene fluoride and trifluoroethylene (75/25) [P(VDF/TrFE)] and poly(l,4-butylene adipate) (PBA) have been investigated by means of optical microscopic observation and time-resolved light scattering. The blends exhibited a typical lower critical solution temperature (LCST)∼${34}^{\circ}C$ above the melting temperature of the P(VDF/TrFE) crystals over the entire blend composition range. P(VDF/TrFE) and PBA were totally miscible in the temperature gap between the melting point of P(VDF/TrFE) and the LCST. Temperature jump experiments of the 3/7 P(VDF/TrFE)/PBA blend were carried out on a light-scattering apparatus from a single-phase melt state (${180}^{\circ}C$) to a two-phase region (205∼${215}^{\circ}C$). Since the late stage of spinodal decomposition (SD) is prevalent in the 3/7 blend, SD was analyzed using a power law scheme. Self-similarity was preserved well in the late stage of SD in the 3/7 blend.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.67-74
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• 2016

프러시안 블루 유사체(Prussian Blue Analogue : PBA)는 3차원 구조와 기공을 갖는 금속-유기골격체이며, 유기 리간드의 종류에 따라 다양한 구조를 갖는다. PBA는 바이오센서, 광학, 촉매, 수소 저장 장치 등의 분야에서 주목 받고 있으며 화학적 안정성을 가진 환경 친화적인 물질이다. 또한 다양한 크기의 미세기공을 조정할 수 있어 흡착분야에서 많이 활용되고 있다. 본 연구는 수열합성법을 이용하여 금속유기골격체인 $Mn_3[Fe(CN)_6]_2$를 합성하였다. 전구체로 $K_4[Fe(CN)_6]$와 $MnCl_2$를 사용하였고, 합성된 물질은 소성하여 망간철산화물을 생성하였다. 실험 변수로 전구용액의 pH, 전구체의 몰농도, 반응시간을 조절하여 입자의 크기와 형태에 대한 영향을 확인하였다. 합성된 다공체는 XRD, SEM, FT-IR, UV-Vis, TG/DTA에 의해 분석하였고, 여러 염료에 대한 흡착 특성을 평가하였다.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2560-2566
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• 2012

The present study investigates how the thermal stability of retinol (vitamin A) encapsulated in polyester nanoparticles is influenced by the types of polyester used for the nanoparticles. A variety of polyester-retinol nanoparticles were prepared with various polyesters like: poly(ethylene adipate), PEA; poly(butylene adipate), PBA; poly(hexamethylene adipate), PHMA; and three polycaprolactones, PCL, of different molecular weights ($M_n$ ~10, 40, and 80K). The chemical stability of retinol in these nanoparticles, monitored in an aqueous solution at $25^{\circ}C$ and $40^{\circ}C$ for 4 weeks, was high in the following order of the nanoparticles prepared with PHMA > PCL 40K > PCL 10K > PCL 80K > PBA~PEA at $25^{\circ}C$ and PCL 10K > PCL 40K > PHMA > PCL 80K > PEA > PBA at $40^{\circ}C$. More importantly, this study has also found that the thermal stability of the retinol in the nanoparticles was closely connected with the melting temperatures of polyesters and polyester nanoparticles. The results were further discussed with possible factors - such as sample preparation condition (or history) and miscibility between the polyesters and retinol - affecting $T_m$ of the polyesters and the nanoparticles.

• 한국환경보건학회지
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• 제43권4호
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• pp.280-297
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• 2017

Objectives: We assessed pesticide exposure levels according to cultivation and crop type and investigated agricultural factors related to exposure. Methods: The participants, 341 male and 127 female farmers, were divided into three groups by cultivation crop type: chili greenhouse, cucumber greenhouse, and orchard. We collected questionnaires, socioeconomic characteristics and agricultural factors, and spot urine. Pesticide exposure was examined using four organophosphate and four pyrethroids urinary metabolites: dimethylphosphate, dimethylthiophosphate, diethylphosphate, diethylthiophosphate, Cis and Trans-3-(2-2dichlorovinyl)-2, 2-dimethylcyclopropane carboxylic acid, 3-phenoxybenzoic acid (3-PBA), Cis-3-(2-2dibrmovinyl)-2, and 2-dimethylcyclopropane carboxylic acid. Each metabolite was summed ${\Sigma}DAP$ and ${\Sigma}PY$ according to the chemical class. Results: Urinary metabolite detection rates and concentrations were similar between the greenhouse groups, but the orchard group was different. Similar 3-PBA detection rates were found in the three groups, but the geometric mean was very high in the orchard group compared to the two greenhouse groups. 3-PBA concentration in the orchard group was $4.11{\mu}g/g$ creatinine; the chili and cucumber greenhouse groups were 1.27 and $1.16{\mu}g/g$ creatinine, respectively. ${\Sigma}DAP$ was significantly associated with cultivation crop type and seasonal variation, but ${\Sigma}PY$ was not relevant. Conclusions: Our results suggest that cultivation and crop type may be correlated with different pesticide types and exposure levels. Furthermore, seasonal factors were related as potential factors influencing the level of organophosphate metabolites, but not for pyrethroid metabolites.

• 한국식품과학회지
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• 제39권4호
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• pp.360-365
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• 2007

간장 중 3-MCPD 분석을 위한 HFBI, PBA, BSTFA 및 MBTFA를 사용한 유도체화 방법 및 시료 정제를 위한 흡착제, 용출용매 및 Surrogate, 내부표준물질 등을 검증한 결과 MBTFA를 이용한 acylation 방법을 제외한 나머지 세가지 유도체화 방법 모두 0.01 mg/kg 이하의 검출한계를 확인하였으며 정량한계(검출한계 ${\times}$3배)를 고려하더라도 현재의 국내 0.3 mg/kg 기준을 분석하는데 문제가 없는 것으로 판단되었으나 유럽의 허용치 0.02 mg/kg을 분석하기 위해서는 PBA방법이나 BSTFA를 사용한 유도체화 방법의 경우 최종 시료액을 약 5배 이상 농축할 필요가 있다. 한편, 유도체화를 위한 반응조건으로 가열시간 및 온도는 HFBI와 BSTFA를 사용하는 경우 $70^{\circ}C$에서 각각 30 및 60분 그리고 PBA는 첨가 직후부터 가열 없이 반응이 완결되는 것으로 나타났다. 흡착제는 Extrelut20 혹은 Florisil 이 가장 적합한 것으로 확인되었으며, 흡착제로부터의 3-MCPD 용출용매로는 ethyl acetate가 상대적으로 높은 추출능을 보여 주었다. 또한 고가의 3-MCPD 중수 소치환 동위원소 surrogate 물질을 대체하기 위한 surrogate 표준물질로는 1,2-butanediol이 그리고 내부표준물질로는 1,2-dibromo-3-chloropropane이 가장 적합한 것으로 확인하였다.

• 한국버섯학회지
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• 제3권2호
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• pp.45-51
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• 2005

농촌진흥청 응용미생물과와 농가에서 수집한 꽃송이버섯 균주의 배양적 특성을 조사하였다. 기본배지는 감자 추출물을 이용한 PBA, PDA, PDM 배지에서 균사생장이 양호한 경향이었고, 특히 대나무톱밥 추출물이 함유된 PBA 배지에서 균사생장 및 밀도가 가장 좋았다. 꽃송이버섯 균사의 최적 배양온도는 $25^{\circ}C$이었으며, $30^{\circ}C$ 이상에서는 균사생장이 전혀 이루어지지 않았다. 최적 pH 조건은 모든 균주가 pH 5.0에서 균사생장 및 밀도가 양호하였다. 대부분 균주가 pH 4.0에서 균사생장은 좋았으나 밀도가 현저히 낮은 경향이었지만, SC12 균주는 pH 4.0에서도 균사생장이 양호하였다. 탄소원은 단당류인 glucose, fructose, mannose, xylose와 이당류인 maltose에서 균사생장이 양호하고 밀도가 높았다. 이중 가장 경제적인 탄소원 glucose를 1.0~1.5% 농도로 처리하였을 때 균사생장이 양호하였다. 질소원은 threonine, peptone, glycine, glutamine 그리고 valine을 첨가한 배지에서 균사생장이 양호하고 밀도가 높았으며, 질소원 peptone을 0.3% 처리하였을 때 균사생장 및 밀도가 가장 좋았다.

• 대한환경공학회지
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• 제39권12호
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• pp.698-705
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• 2017

전과정평가 기법을 적용하여 재생 플라스틱을 사용한 휴대폰 충전기의 전과정 환경영향을 정량화하고, 신재 플라스틱과 재생플라스틱의 환경영향을 비교하였다. 충전기의 제조전, 제조, 유통, 사용 및 폐기를 포함하는 전과정 단계별로 자원고갈, 산성화, 부영양화, 지구온난화, 오존층고갈, 광화학산화물생성 환경영향을 분석하였다. 자원고갈 및 지구온난화 영향범주에서는 충전기의 사용단계 환경영향이 각각 94.4%, 70%를 차지하여 가장 큰 환경영향을 나타냈고, 그 외 영향범주에서는 제조전단계의 환경영향이 98% 이상을 차지하였다. 사용단계의 경우 충전기에 의해 소모되는 전력이 주요 원인이고, 제조전단계 경우 PBA (Printed Board Assembly)와 외장 Case 제조공정이 주요 원인이었다. 외장 Case에 사용되는 재생 PC (Polycarbonate)의 환경개선 효과를 정량화하기 위해 재생 PC와 신재 PC 각 1 kg 생산할 때의 환경영향을 평가하였다. 재생 PC는 신재 PC 대비 자원고갈영향은 30% 수준이며 다른 영향범주에서는 5% 미만으로 잠재적인 환경개선효과가 큰 것으로 분석되었다. 연구에 활용된 주요 데이터 및 가정에 대해 민감도 분석을 수행하였고, 총 12개 항목 분석결과 모든 항목에서 민감도는 10% 미만으로 도출되어 연구 결과의 신뢰도는 높다고 판단된다. 이 연구결과를 통해 충전기의 친환경성 개선을 위해서는 PBA의 소형/경량화 설계, 충전효율의 개선, 재생플라스틱 사용 확대가 전과정 환경영향을 줄이는데 중요한 설계 인자임을 확인하였다.

• 한국환경보건학회지
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• 제48권2호
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• pp.96-105
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• 2022

Background: Pyrethroid insecticides account for more than 30% of the global insecticide market and are frequently used in agricultural settings and residential and public pest control among the general population. While several animal studies have suggested that exposure to pyrethroids can alter glucose homeostasis, there is only limited evidence of the association between environmental pyrethroid exposure and diabetes in humans. Objectives: This study aimed to report environmental 3-phenoxybenzoic acid (3-PBA) concentrations in urine and evaluate its association with the risk of diabetes in Korean adults. Methods: We analyzed data from the Korean National Environmental Health Survey (KoNEHS) Cycle 2 (2012~2014) and Cycle 3 (2015~2017). A total of 10,123 participants aged ≥19 years were included. Multiple logistic regressions were used to calculate the odds ratios (ORs) for diabetes according to log-transformed urinary 3-PBA levels. We also evaluated age, sex, education, monthly income, marital status, alcohol drinking, physical activity, urinary cotinine, body mass index, and sampling season as potential effect modifiers of these associations. Results: After adjusting for all the covariates, we found significant dose-response relationships between urinary 3-PBA as quartile and the prevalence of diabetes in pooled data of KoNEHS Cycles 2 and 3. In subgroup analyses, the adverse effects of pyrethroid exposure on diabetes were significantly stronger among those aged 19~39 years (p-interaction<0.001) and those who consumed high levels of cotinine (p-interaction=0.020). Conclusions: Our findings highlight the potential diabetes risk of environmental exposure to pyrethroids and should be confirmed in large prospective studies in different populations in the future.

• Mycobiology
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• 제28권4호
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• pp.165-170
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• 2000

This study was carried out to obtain the basic data for artificial culture of veiled lady mushroom (Dictyophora spp). The optimal conditions for the mycelial growth were $25^{\circ}C$ and pH 5.0 for all isolates except the optimal temperature of $30^{\circ}C$ for D. echinovolvata ASI 32002 and Phallus rugulosus. The optimal medium for Dictyophora spp. was PBA (potato bamboo sawdust extract agar) medium. The strain ASI 32002, D. echinovolvata, grew faster than. D. indusiata ASI 32003 and Phallus rugulosus ASI 25007 on the medium. Carbon sources such as glucose, maltose and inuline were favorable for stimulating a mycelial growth of the two strains of ASI 32002 and ASI 32003. Asparagine and glutamine appeared to be favorable to the strain ASI 32002 and ASI 32003, where as alanine, one of nitrogen source also favorable to the strain ASI 32002. The optimum C/N ratio of the two isolates of ASI 32002 and ASI 32003 was about 25 : 1 when 2% glucose as carbon source was mixed with the basal medium. While, in the case of 4% as carbon source, the optimum C/N ratio was about 30 : 1.

• Elastomers and Composites
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• 제58권4호
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• pp.208-215
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• 2023

In this study, the properties of polyurethane-polydimethylsiloxane (PU-PDMS) hybrid foams containing different types and contents of physical blowing agents (PBAs) were investigated. Two types of blowing agents, namely physical blowing agents and thermally expandable microspheres (TEM), were applied. The apparent density was measured using precisely cut foam samples, and the pore size was measured using image software. In addition, the microstructure of the foam was confirmed via scanning electron microscopy and transmission electron microscopy. The thermal conductivities related to the microstructures of the different foams were compared. When 0.5 phr of the hydrocarbon-based PBA was added, the apparent density and pore size of the foam were minimal; however, the pore size was larger than that of neat foam. In contrast, the addition of 3 phr of TEM effectively reduced both the apparent density and pore size of the PBAs. The increase in resin viscosity owing to TEM could enhance bubble production stability, leading to the formation of more uniform and smaller pores. These results indicate that TEM is a highly efficient PBA that can be employed to decrease the weight and pore size of PU-PDMS hybrid foams.