기존의 교면 포장이나 측구 시공에 적용한 건설재료들의 성능저하로 인해 유지보수비가 증가하고 있는 추세이다. 이에 본 연구에서는 현장 실험을 통해 개질유황 콘크리트의 내구성을 평가하는데 있어 기존의 고정형 팬믹서와 건 비빔 시 자전속도 변환이 가능한 가변형 팬믹서를 이용하여 내구성 평가 시험으로 콘크리트의 압축강도 시험을 수 행하였다.

본 연구에서 페리다이나믹 이론 모델을 이용하여 준정적하중과 동적 하중, 균열전파와 분기균열 패턴 그리고 등방성재료, 직교 이방성 재료의 균열 진전 해석 등 다양한 조건을 고려한 전산 시뮬레이션을 수행하여 그 적합성을 검토하였다. 초기 균열은 없지만 중심에 홀이 있는 등방성 재료, 초기 균열이 존재하는 등방성 및 이방성 재료에 대한 전산 시뮬레이션이 수행되었다. 조정 동적 완화 기법이 사용되어 준정적 하중을 모사하였고, 이방성 재료 해석에서는 고전 연속체 역학과 페리다이나믹의 변형률 에너지를 고려한 균질화 방법이 사용되었다. 균열 전파와 분기 균열이 성공적으로 확인되었으며 파괴 거동의 시작과 그 방향 역시 페리다이나믹 이론으로 확인되었다. 페리다이나믹을 균질화 방법을 사용하여 비교적 복잡한 이방성 재료에 적용한 경우 역시 실험 결과 값과 비교하여 검증하였다.

This paper reviews on nano-materials as part of a study to apply nano-technology related technologies to the construction field. First, the synthesis method of nano-materials was examined. Secondly, the mechanical application method of nano-materials was investigated. Finally, the analysis method of nano-materials was investigated.

This study is to develop a composite material sleepers based on synthetic resin instead of neck sleepers applied to martial bridges. For this purpose, the properties of various polyols with various functional groups for the improvement of strength were evaluated, and the aim was to improve the physical properties by modifying isocyanate and expanding the reaction sites. The physical properties of polyurethane were evaluated according to the type and content of additive for the improvement of the physical strength of polyurethane

폴리락타이드 재질의 식품용 기구 및 용기·포장에서 식품으로 이행될 우려가 있는 유해 중금속인 납, 카드뮴 및 비소의 이행량을 측정하고 안전성을 평가하기 위하여 국내에 유통중인 폴리락타이드 시료 총 211건을 수거하였다. 용출실험은 ‘식품용 기구 및 용기·포장 공전’의 조건 에 따라 식품모사용매인 4% acetic acid로 하였으며 온도 조건으로 70oC와 가혹사용조건인 100oC 모두 적용하여 이 행량을 비교하였다. 납, 카드뮴 및 비소의 이행량은 모두 70oC보다 100oC의 조건에서 증가하는 경향을 보였으나, 납 의 최대 이행량은 기준·규격과 비교하여 1.0%의 낮은 수 준이었고, 카드뮴은 모두 미량이 검출되었으며, 비소의 최대 이행량은 기준·규격 대비 3.9%의 낮은 수준으로 기준·규격을 초과하는 시료는 없었다. 이행량 결과를 바탕으로 납, 카드뮴 및 비소의 일일추정섭취량을 산출한 후 잠정주간섭취허용량 등과 비교하는 안전성평가를 진행하였으며, 국내에 유통되는 식품용 폴리락타이드 기구 및 용기·포장을 통한 납, 카드뮴 및 비소의 일일추정섭취량은 2.5 × 10−5~ 2.0 × 10−3μg/kg bw/day인 것으로 산출되었다. 용출조건별로는 70oC, 30분에서 카드뮴의 일일추정섭취량이 가장 낮았고, 100oC, 30분에서의 납 일일추정섭취량이 2.0 × 10−3μg/kg bw/day로 제일 높게 나타났으나, 납의 위해도는 인체안전기준(25 μg/kg bw/week)과 비교시 0.055% 수준으로 매우 낮음을 확인되었다. 이를 통하여 국내 유통 폴리락타이드 재질 식품용 기구 및 용기·포장에서의 납, 카드뮴 및 비소의 이행량은 매우 낮은 수준임을 확인하였고, 본 연구의 결과는 향후 식품용 기구 및 용기· 포 장의 안전관리를 위한 과학적인 근거자료로 활용될 수 있을 것으로 사료된다.

The purpose of this study is to compare and evaluate the safety of the facility using the Abaqus finite element analysis program according to the material characteristics like steel and GFRP.

We carried out a dynamic instability assessment of carbon nanotube reinforced composite (CNTRC) and carbon nanotubes/fiber/polymer composite (CNTFPC) skew plates based on the high-order shear deformation plate theory (HSDT). The multiscale interactions between carbon nanotube (CNT) ratios and skew angles on the dynamic instability for various length-thickness ratios are studied using a two-dimensional finite element model developed for this study. The results were verified by those reported in the literature show the interactions between the CNT reinforcement and skew angles in the skew laminate. Numerical examples show the importance of CNT reinforcement when assessing the dynamic instability of CNTRC and CNTFPC skew plates.

식품생산현장에서 제품 생산 중 오염되는 이물의 발생경로, 원인은 식품 유형별로 매우 다양하나 크게 두 가지 원인으로 대별된다. 첫 번째는 원부자재, 작업 인원, 생산현장의 음압 발생으로 외부에서 유입되는 이물이며 두 번째는 생산현장 내부의 설비, 배관, 내벽 틈새 등에서 발생되는 이물이다. 따라서 식품생산현장에서는 기본적으로 현장내부의 곤충 포획 모니터링 결과를 토대로 외부에서 유입되는 곤충과 내부에서 발생되는 곤충 종을 구분하고 생산현장 입고단계 주변의 서식처 제거, 생산현장 양압공조 개선, 원부자재의 유입경로와 생산현장 작업동선을 고려하여 해충 유입 경로를 분석하고 유입된 해충과 내부 서식해충의 확산 경로를 추적하는 지속적인 모니터링, 시설, 설비, 공조, 배관의 불합리 개소 지속 발굴, 개선하는 관리가 수반되어야한다.

식품 중 발견 이물은 광물성, 동물성, 식물성 이물로 대별된다. 식약처 이물 발생 신고 자료를 보면 곤충(35%), 곰팡이(10%), 금속(8%), 플라스틱(5%) 순으로 곤충이물이 거의 모든 식품유형에서 가장 높은 빈도로 발생하며 제조 중 발생(6.5%) 보다는 소비, 유통 단계 유입(39.4%), 판정불가(53.4%)가 대부분인 것으로 보고되고 있다. 곤충 이물의 경우 일반적으로 인체 위해성과는 큰 관계는 없으나 소비자에게 혐오감을 불러일으키며(특히 생존곤충 발견 시) 비위생적 취급의 우려로 인해 식품 안전에 대한 소비자 불안감을 가중시키고 언론과 소비자단체를 통해 지속적인 이슈가 되어 식품 기업의 매출감소, 위생, 안전성 측면의 신뢰도를 감소시키고 이물관련 공무원의 이물조사 업무가중 등 행정력낭비를 유발하고 있다. 따라서 산업현장에서 실용화될 수 있는 효과적인 이물 저감화 기술의 개발로 이물발생을 낮추고 국민의 식품안전에 대한 체감도를 높이는 것이 필요하다.

Tyrosinase is a key enzyme in animal melanogenic pathway that is the rate-limiting step for the production of melanin. Several synthetic and naturally occurring tyrosinase inhibitors have been studied for skin whitening, the development of natural agents is becoming more important due to the disadvantages of synthetics such as high cytotoxicity, insufficient penetration power, and low activity. The purpose of this study was to evaluate the polyphenols, antioxidant and tyrosinase inhibition activity of mealworm (Tenebrio molitor) extract and optimization of extraction condition using statically-based optimization. The results showed that extraction temperature of 92.0°C, extraction time of 36.7 min, and ethanol concentration of 79.5% provided the maximum levels of compounds of 5.69 mg GAE/g DW, tyrosinase inhibition of 78.8%, and radical scavenging activity of 100.8 μg/ml in the validation experiment.

There has been growing concern over the emissions of formaldehyde and VOCs from automotive interior materials, as these could have an important impact on the in-vehicle air quality (IVAQ) of automotive vehicles. Odor, the components of which may include VOCs, refers to the automotive interior smell emitted directly or indirectly from any part of an automotive interior, based on human olfactory senses and a comfort evaluation of vehicle quality. The objective of this paper is to compare the instrument analysis with the sensory characteristics of an odor using GC/MS/Olfactometry. From the test, it was possible to identify the cause of odor, which can be difficult to distinguish among multiple odors, through the simultaneous performance of instrumental analysis and sensory evaluation.

This study was designed to evaluate the antioxidant activities and protective effects on PC12 cells of the extract of Epimedium koreanum and its main constituents icariin and icariside I. After screening the seven identified flavonoid glycosides from E. koreanum through DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay, E. koreanum, Icariin and Icariside I exhibited significant effect on radical scavenging activity. E. koreanum, icariin and icariside I were examined using DPPH, ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric reducing ability power) assay. In all antioxidant assays, E. koreanum, icariin and icariside I showed high radical scavenging activities in a dose-dependent manner. Protective effects against H2O2-induced PC12 cells were assessed with MTT assay. The results indicated that cell viability and protection on PC12 cells of icariside I and icariin increased dose dependently. These study results suggest that E. koreanum, icariin and icariside showed high antioxidant capacities and cell protective effects. Icariside I, one of the metabolites of icariin, may be a new and effective flavonoid compound as a functional component.

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.

점토를 이용하여 세 종류의 새로운 형태의 변형된 유기물점토를 제조하였다. Cetylpyridinium chloride (CPC)를 점토에 층간 삽입시켜 OC-CPC를 합성하였고, Aluminium 축을 갖는 Al-PILC 만든 후, cetylpyridinium chloride를 Al-PILC에 삽입시켜 IOC-CPC 화합물을 합성하였다. IR과 TGA를 이용하여 이들 구조를 분석한 결과 층간 삽입반응이 성공적으로 이루어졌음을 확인할 수 있었다. X-ray 회절을 이용하여 층간 거리를 조사하였는데 OC-CPC가 제일 큰 값을 보여 주었다. 층간 구조를 갖는 화합물들은 삽입반응을 이용하여 구조를 변형시킬 수 있으며 이를 통해 층간거리, 표면적, 공간 크기, 화학적 친화성 같은 여러 물리적 성질들을 바꿀 수 있으므로, 본 논문에서는 자연점토를 이용하여 층간 반응을 통해 휘발성 유기화합물의 흡착에 쓰일 수 있는 유용한 유기점토 화합물을 합성하고 이들의 구조를 확인코자 하였다. 벤젠과 톨루엔의 흡착은 IOC-CPC나 Al-PILC에서 보다 OC-CPC에서 더 잘 이루어졌으며, 자연점토에서는 거의 흡착이 일어나지 않았다. OC-CPC 화합물에서는 친 소수성 성질이 크고 층간 거리도 증가했기 때문에 흡착이 잘 일어났다고 볼 수 있으며, 반면에 친수성이 큰 Al-PILC 에서는 벤젠과 톨루엔 같은 휘발성 유기물에 대한 흡착이 상대적으로 적게 일어났다.

Sorghum is a rich source of various phytochemicals including phenolic compounds that have potential to significantly benefit human health. Phytochemical production may be induced not only by genotype but also by a number of environmental factors including temperature and an amount of sunshine. The objective of this study was to determine the effect of planting dates and harvesting stages on the quality traits of ‘Donganme,’ a grain sorghum variety developed to produce high antioxidants. ‘Donganme’ was planted in three locations on four dates from early May to early July. Each planted fraction was harvested 35, 40, 45, 50, and 55 days after the head shooting date, respectively. The results showed that significant differences existed between the growth period and content of polyphenol and flavonoid. The sorghum harvested at 35 days after head shooting had the higher polyphenol and flavonoid content in all planting times and the tannin content was increased as the planting date was delayed. So the sorghum grown in late planting dates (July 5) had highest polyphenol content (2.07 gGAE/100g) at early harvesting (35 days) while late planting gave the low grain yield (1.3 ton/ha). Polyphenol index to average temperature during 35 and 45 days after heading of ‘Donganme’ showed that total polyphenol contents were decreased by 5.2% and 4.4%, respectively, with increasing average temperature of 1oC. And high correlation (R=0.85) was observed between accumulated temperature and the amount of polyphenol of ‘Donganme’, confirming the major contribution of the quality traits is temperature. To produce high quality grain from sorghum the relation between the yield and nutrition components must be considered simultaneously (i.e., Sorghum produced the highest polyphenol and flavonoid when planted in June 15 and harvested at 40 to 45 days after head shooting .

Good Agricultural Practices (GAP) is the world's leading quality certification for food safety. Since its introduction in Korea in 2006, its importance has been increasing every year. In particular, food safety issues are becoming increasingly important in society, and food safety is directly linked to health. The core of GAP certification is the traceability of the production, distribution, and consumption of hazardous materials, including pesticide residues, heavy metals, and microbes. In the present study, pesticides and heavy metals in button mushroom (Agaricus bisporus) and associated cultivation materials were analyzed. Tricyclozole (0.0144 ppm), flubendiamide (0.147 ppm), and trifloxystrobin (0.0340 ppm) were detected in rice straw and wheat straw, and carbendazim (0.0142 ppm) was detected in mixed wheat straw and rice straw medium. Lead and cadmium were detected at levels higher than the standard level in rice straw and mixed medium. However, lead and cadmium were not detected in mushrooms, and levels of arsenic and mercury were below the safety limit. Therefore, it was confirmed that the residual pesticides and heavy metals are safely managed in the investigated mushroom species. The results of the present study suggest that if these materials are adequately managed in the surroundings during cultivation, all hazardous materials can be managed during mushroom production.

PURPOSES : The purpose of this study is to develop bridge deck concrete materials based on ordinary Portland cement concrete, and to evaluate the applicability of the developed materials through material properties tests.METHODS : For field implementation, raw material (cement, fine aggregate, and coarse aggregate) properties, fresh concrete properties (slump and air content), strength (compressive, flexural and bond strength) gain, and durability (freeze-thaw resistance, scaling resistance, and rapid chloride penetrating resistance) performance were evaluated in the laboratory.RESULTS: For the selected binder content of 410 kg/m3, W/B = 0.42, and S/a = 0.48, the following material performance results were obtained. Considering the capacity of the deck finisher, a minimum slump of 150 mm was required. At least 6 % of air content was obtained to resist freezethaw damage. In terms of strength, 51.28 MPa of compressive strength, 7.41 MPa of flexural strength, and 2.56 MPa of bond strength at 28 days after construction were obtained. A total of 94.9 % of the relative dynamic modulus of elasticity after 300 cycles of freeze-thaw resistance testing and 0.0056 kg/m2 of weight loss in a scaling resistance test were measured. However, in a chloride ion penetration resistance test, the result of 3,356 Coulomb, which exceeds the threshold value of the standard specification (1000 Coulomb at 56 days) was observed.CONCLUSIONS: Instead of using high-performance modified bridge deck materials such as latex or silica fume, we developed an optimum mix design based on ordinary Portland cement concrete. A test construction was carried out at ramp bridge B (bridge length = 111 m) in Gim Jai City. Immediately after the concrete was poured, the curing compound was applied, and then wet mat curing was applied for 28 days. Considering the fact that cracks did not occur during the monitoring period, the applicability of the developed material is considered to be high.

SiC-based composite materials with light weight, high durability, and high-temperature stability have been actively studied for use in aerospace and defense applications. Moreover, environmental barrier coating (EBC) technologies using oxide-based ceramic materials have been studied to prevent chemical deterioration at a high temperature of 1300℃ or higher. In this study, an ytterbium silicate material, which has recently been actively studied as an environmental barrier coating because of its high-temperature chemical stability, is fabricated on a sintered SiC substrate. Yb2O3 and SiO2 are used as the raw starting materials to form ytterbium disilicate (Yb2Si2O7). Suspension plasma spraying is applied as the coating method. The effect of the mixing method on the particle size and distribution, which affect the coating formation behavior, is investigated using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) analysis. It is found that the originally designed compounds are not effectively formed because of the refinement and vaporization of the raw material particles, i.e., SiO2, and the formation of a porous coating structure. By changing the coating parameters such as the deposition distance, it is found that a denser coating structure can be formed at a closer deposition distance.