• Tribology and Lubricants
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• 제35권2호
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• pp.132-138
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• 2019

In this study, we demonstrate the effects of the acidic properties of montmorillonite (MMT), which is commonly used as a catalyst, on the conversion and selectivity of the dimer acid methyl ester (DAME) synthesis. We synthesize DAME by the dimerization of conjugated linoleic acid methyl ester (CLAME) and oleic acid methyl ester using MMT KSF. Incidentally, trimer acid methyl ester was formed as a by-product during the DAME synthesis. There is a necessity to adequately adjust the strength and quantity of the acid site to control the selectivity of DAME. Therefore, we vary the pH of the MMT acid by using various metal hydroxides. The purpose of this study is to increase the yield of monocyclic dimer acid methyl ester, which is a substance with adequate physical properties for industrial applications (e.g., lubricant and adhesive, etc.), using a heterogeneous catalyst. We report the dimerization of fatty acid methyl ester by using base treated-KSF, and apply it to conjugated soybean oil methyl ester. Then, we transmute the acid site properties of KSF, such as pH of 5 wt.% slurry KSF and various alkali metals (Li, Na, K, Ca). Characterization of base treated-KSF using a pH meter, x-ray diffraction, inductively coupled plasma-atomic emission spectrometer, Brunauer-Emmett-Teller surface analysis, and temperature-programmed desorption. We conduct an analysis of CLAME and DAME using nuclear magnetic resonance spectroscopy, gas chromatography, and gel permeation chromatography. Through these experiments, we demonstrate the effects of the acidic properties of KSF on the conversion and selectivity of the DAME synthesis, and evaluate its industrial potential by application to waste vegetable oil.

• Asian-Australasian Journal of Animal Sciences
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• 제32권7호
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• pp.977-987
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• 2019

Objective: The use of tannin extract and other phytochemicals as dietary additives in ruminants is becoming more popular due to their wide biological actions such as in methane mitigation, bypass of dietary protein, intestinal nematode control, among other uses. Unfortunately, some have strong astringency, low stability and bioavailability, and negatively affecting dry matter intake and digestibility. To circumvent these drawbacks, an effective delivery system may offer a promising approach to administer these extracts to the site where they are required. The objectives of this study were to encapsulate acacia tannin extract (ATE) with native starch and maltodextrin-gum arabic and to test the effect of encapsulation parameters on encapsulation efficiency, yield and morphology of the microparticles obtained as well as the effect on rumen in vitro gas production. Methods: The ATE was encapsulated with the wall materials, and the morphological features of freeze-dried microparticles were evaluated by scanning electron microscopy. The in vitro release pattern of microparticles in acetate buffer, simulating the rumen, and its effect on in vitro gas production was evaluated. Results: The morphological features revealed that maltodextrin/gum-arabic microparticles were irregular shaped, glossy and smaller, compared with those encapsulated with native starch, which were bigger, and more homogenous. Maltodextrin-gum arabic could be used up to 30% loading concentration compared with starch, which could not hold the core material beyond 15% loading capacity. Encapsulation efficiency ranged from $27.7%{\pm}6.4%$ to $48.8%{\pm}5.5%$ in starch and $56.1%{\pm}4.9%$ to $64.8%{\pm}2.8%$ in maltodextrin-gum arabic microparticles. Only a slight reduction in methane emission was recorded in encapsulated microparticles when compared with the samples containing only wall materials. Conclusion: Both encapsulated products exhibited the burst release pattern under the pH conditions and methane reduction associated with tannin was marginal. This is attributable to small loading percentages and therefore, other wall materials or encapsulation methods should be investigated.

• 산업식품공학
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• 제21권3호
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• pp.233-241
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• 2017

Scaffolds of cell substrates are biophysical platforms for cell attachment, proliferation, and differentiation. They ultimately play a leading-edge role in the regeneration of tissues. Recent studies have shown the potential of bioactive scaffolds (i.e., osteo-inductive) through 3D printing. In this study, rice bran-derived biocomposite was fabricated for fused deposition modeling (FDM)-based 3D printing as a potential bone-graft analogue. Rice bran by-product was blended with poly caprolactone (PCL), a synthetic commercial biodegradable polymer. An extruder with extrusion process molding was adopted to manufacture the newly blended "green material." Processing conditions affected the performance of these blends. Bio-filament composite was characterized using field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). Mechanical characterization of bio-filament composite was carried out to determine stress-strain and compressive strength. Biological behaviors of bio-filament composites were also investigated by assessing cell cytotoxicity and water contact angle. EDX results of bio-filament composites indicated the presence of organic compounds. These bio-filament composites were found to have higher tensile strength than conventional PCL filament. They exhibited positive response in cytotoxicity. Biological analysis revealed better compatibility of r-PCL with rice bran. Such rice bran blended bio-filament composite was found to have higher elongation and strength compared to control PCL.

• 한국기후변화학회지
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• 제8권1호
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• pp.31-39
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• 2017

The emission quantity of nitrous oxide is second largest among non-$CO_2$ greenhouse gas in Korea. In this study, we investigated loss rate of nitrous oxide which was filled in PVF and Al-PE bag as time goes on. Concentrations of tested samples were about 25 ppmv, 50 ppmv, 75 ppmv prepared by standard reference gas. In case of all experiments, loss rate of PVF bag was higher than Al-PE bag. After 18 days, loss rate of PVF bag was from 29.7% to 38.6% while Al-PE bag was from 21.7% to 23.7%. Especially the differential growed bigger when initial concentration of $N_2O$ in PVF bag was lower. And we also studied the effect of cock opening/closing procedures on loss rate. Prepared samples in experimental group were analyzed several times for 20 days and samples in control group were analysed only 1 time after 20 days. The experimental results showed that cock opening/closing procedures appeared to have little impact on loss rate.

• 대한토목학회논문집
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• 제39권5호
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• pp.637-645
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• 2019

기후변화와 새로운 에너지정책의 변화등 대내외적인 환경정책의 변화로 도시특성과 에너지 사용량에 대한 파악이 필요하다. 기존에도 도시공간 구조를 활용한 연구는 누적되어왔지만 대부분 거시적으로 국가별, 수도권 위주, 대도시를 대상으로 했으며 경제성장이나 탄소배출과 에너지 사용량의 관계에 주목하였다. 본 연구는 이와는 달리 세부적으로 도시특성을 반영한 데이터를 바탕으로 기존의 교통에너지를 제외하고 가정과 산업 에너지 환경의 기반인 전기와 가스에너지 사용량과의 상관관계를 파악하고자 한다. 본 연구는 도시 토지이용과 제조업특성을 고려하여 도시 특성과 전기와 가스 에너지 사용량과의 연관성을 실증적으로 분석하였다. 통계적으로 유의미한 변수 중에서도 세대수와 면적의 도시 규모 특성과 지방세 징수액, 자동차 등록대수와 같은 경제적 특성, 도로와 시가화밀도등의 도시화 특성은 에너지사용량을 증가시키는 상관요인들로 도출되었다. 본 연구는 수도권 중심의 에너지 소비 분석에서 벗어나 부산광역도시권 지역사회 에너지 정책의 이론적 근거를 마련하는 데 도움이 되고자 하였다.

• 환경영향평가
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• 제28권5호
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• pp.483-491
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• 2019

파리 협약에 따른 post-2020에 대비하기 위한 환경영향평가(EIA : Environmental Impact Assessment) 측면에서의 온실가스 감축방안을 모색하였다. 2010~2019년 금강유역환경청의 EIA대상사업 중 26건의 환경영향평가서(EIS : Environmental Impact Statement)를 사례분석한 결과로, '온실가스 항목'은 대부분 형식적으로 작성된 것으로 분석되었다. 본 연구에서는 EIA시 '온실가스 항목'의 형식적 평가를 개선하기 위한 방안으로서, 1) EIA대상사업별 온실가스 배출량에 따른 배출부과금 할당, 2) "환경오염시설의 통합관리에 관한 법률"에 근거한 '허가배출기준 설정'에 '온실가스 항목'의 추가, 3)이해당사자들이 EIA대상 개발사업의 초기단계에 참여하는 거버넌스 확립으로 온실가스 감축 등을 제안하였고, 구체적인 내용을 논의하였다.

• 한국재료학회지
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• 제31권1호
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• pp.16-22
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• 2021

In this study, quantum dot-sensitized solar cells (QDSSC) using CdSe/ZnS quantum dots (QD) of various sizes with green, yellow, and red colors are developed. Quantum dots, depending their different sizes, have advantages of absorbing light of various wavelengths. This absorption of light of various wavelengths increases the photocurrent production of solar cells. The absorption and emission peaks and excellent photochemical properties of the synthesized quantum dots are confirmed through UV-visible and photoluminescence (PL) analysis. In TEM analysis, the average sizes of individual green, yellow, and red quantum dots are shown to be 5 nm, 6 nm, and 8 nm. The J-V curves of QDSSC for one type of QD show a current density of 1.7 mA/㎠ and an open-circuit voltage of 0.49 V, while QDSSC using three type of QDs shows improved electrical characteristics of 5.52 mA/㎠ and 0.52 V. As a result, the photoelectric conversion efficiency of QDSSC using one type of QD is as low as 0.53 %, but QDSSC using three type of QDs has a measured efficiency of 1.4 %.

• 대한건축학회논문집:계획계
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• 제34권2호
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• pp.41-48
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• 2018

This study is expected to provide some basic data on how to apply more economical and efficient eco-friendly factors to reduce the carbon emissions. It has been scrutinized and analyzed the environmental factors of passive eco-friendly elements along with active eco-friendly elements as more efficient factors for energy conservation based on the case of a newly constructed broadcasting building with the green building certification in Sangam-dong DMC area. The first analysis was the energy consumption trends in Korea and the necessity of energy saving. Secondly, it was examined the energy consumption in the current status of the broadcasting building. Thirdly, it was looked into the correlation between the eco-friendly design application factors applied to the broadcasting building and the energy consumption types. As a result of the analysis, the application of fan and feed pump inverter along with ventilation system of waste heat recovery ventilation system were more meaningful in accordance with the economic feasibility of broadcasting buildings rather than economical effect of passive elements such as rooftop garden, reinforcement of building insulation. Also, the application of lighting control had the economical feasibility. Therefore, when it is intended to change the green building certification energy related evaluation items of the similar broadcasting building types, it is necessary to change the direction of adding weight to the more economical active element items in the future.

• 한국환경보건학회지
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• 제47권1호
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• pp.20-35
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• 2021

Objectives: Waste treatment by incineration is gradually increasing as the emission of harmful substances has decreased owing to developments in incineration technology. However, residents living near incinerators continue to express anxiety regarding the effects on their health. Therefore, we attempted to summarize the health impact of incinerators by comprehensively reviewing the recently reported literature. Methods: Sixty-two epidemiological research papers related to incineration and health effects were selected from the Google Scholar database and analyzed (from between January 2001 and December 2019). Results: When compared to older incinerators, newer incinerators established after 2000 are considered relatively safe in terms of health effects. Nevertheless, there have been some studies that have linked them to various diseases, such as malignant tumors including soft tissue cancer and non-Hodgkin's lymphoma, reproductive disorders, respiratory diseases, and more. In addition, incinerator workers and local residents are considered to be exposed to dioxins and some heavy metals from the incinerator. Since most studies included subjects exposed to older incinerators, it is difficult to apply these results to the health impact assessment of new incinerators. However, it is not appropriate to conclude that new incinerators made with state-of-the-art technology are safe, as chronic environmental diseases caused by hazardous substances tend to appear only after prolonged exposure. Conclusions: In terms of environmental health, it is necessary to continuously monitor the health effects of incinerators. Also, there is a need to develop a research methodology that can minimize various confounders in incineration-related epidemiological study.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.244-254
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• 2018

Surface modified poly ${\text\tiny{L}}$-lactic acid (PLLA) samples with hydroxyapatite (HA), heparin and bone morphogenetic protein-2 (BMP-2) mediated by polydopamine (pDA) coating (PLLA/pDA/HA/Hep/BMP-2) were prepared, and their effects on the enhancements of bone formation and osseointegration were evaluated in vitro and in vivo as compared to PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. The changes in surface chemical compositions, morphologies and wettabilities were observed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and water contact angle measurements. Pre-coating of HA particles with pDA provided uniform and homogeneous anchoring of particles to PLLA surface. In addition, the strong ionic interaction between heparin and pDA led PLLA surface readily heparinized for loading of BMP-2. In vitro experiments revealed that the levels of alkaline phosphatase (ALP) activity, calcium deposition, and osteocalcin (OCN) gene expression were higher in MG-63 human osteosarcoma cell lines grown on PLLA/pDA/HA/Hep/BMP-2 than on control PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. In vivo studies using micro-computed tomography (micro-CT) also showed that PLLA/pDA/HA/Hep/BMP-2 screw exhibited greatest value of bone volume (BV) and bone volume/tissue volume (BV/TV) among samples. Histological evaluations with H&E and Von Kossa staining demonstrated that a combination of HA and BMP-2 contributed to the strong osseointegration.