As part of planning for waste minimization, decontamination foam has been considered as a potential application for the cleaning of radioactive contaminant. In this study, we synthesized silica particles to improve foam stability by varying synthesis parameters. Cetyltrimethylammonium bromide (CTAB) was found to influence the stability of the decontamination foam. The reason was that higher interaction between SiO2 nanoparticles and surfactant at the air-water interface in aqueous solution is beneficial for foam stability. CTAB can also be used as an additive for the aggregation of silica nanoparticles. In the separation of SiO2 nanoparticles, CTAB plays a critical role in the nanoparticles flocculation because of the charge neutralization and hydrophobic effects of its hydrocarbon tails.

Chronic problems of water treatment membranes are fouling phenomena and membrane damage during the cleaning process. In this study, to solve these problems, a separation membrane in the form of a hollow fiber having excellent physical properties was produced by using the thermally induced phase separation (TIPS). The material used to make the water treatment membrane is poly(vinylidene fluoride) (PVDF). In the evaluation of the properties of the manufactured hollow fiber, citric acid which is an acidic solution and NaCl which is a basic solution were used and experiments of chemical resistance were proceed. In order to confirm the performance of hollow fiber membrane, water flux and tensile strength were measured.

Climate change is believed to increase the amount of dissolved organic matter in surface water, as a result of the release of bulk organic matter, which make difficult to achieve a high quality of drinking water via conventional water treatment techniques. Therefore, the natural water treatment techniques, such as managed aquifer recharge (MAR), can be proposed as a alternative method to improve water quality greatly. Removal of bulk organic matter using managed aquifer recharge system is mainly achieved by biodegradation. Biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) can be used as water quality indicators for biological stability of drinking water. In this study, we compared the change of BDOC and AOC with respect to pretreatment methods (i.e., ozone or peroxone). The oxidative pretreatment can transform the recalcitrant organic matter into readily biodegradable one (i.e., BDOC and AOC). We also investigated the differences of organic matter characteristics between BDOC and AOC. We observed the decreases in dissolved organic carbon (DOC) and the tryptophan-like fluorescence intensities. Liquid chromatographic - organic carbon detection (LC-OCD) analysis also showed the reduction of the low molecular weight (LMW) fraction (15% removed, less than 500 Da), which is known to be easily biodegradable, and the biopolymers, high molecular weight fractions (66%). Therefore, BDOC consists of a broad range of organic matter characteristics with respect to molecular weight. In AOC, low molecular weight organic matter and biopolymers fraction was reduced by 11 and 6%, respectively. It confirmed that biodegradation by microorganisms as the main removal mechanism in AOC, while BDOC has biodegradation by microorganism as well as the sorption effects from the sand. O3 and O3 + H2O2 were compared with respect to biological stability and dissolved organic matter characteristics. BDOC and AOC were determined to be about 1.9 times for O3 and about 1.4 times for O3 + H2O2. It was confirmed that O3 enhanced the biodegradability by increasing LMW dissolved organic matter.

두유는 단백질, 지방, 다당류 등으로 구성된 에멀젼으로서 저장 중 상분리 또는 침전 현상이 발생하게 되는데, 이에 가장 큰 영향을 미치는 것은 입도크기인 것으로 알려져 있다. 최근 보고에 의하면 양친매성의 계면활성제는 두유의 이러한 현상을 억제하는 중요한 역할을 하는 것으로 알려져 있다. 따라서 본 연구에서는 두유의 가공조건과 천연 계면활성제인 사포닌(순도=80%)이 두유의 저장 안정성에 미치는 영향을 확인하고자 하였다. 실험에 사용한 두유액은 고형분을 제거한 후, 사포닌을 0%, 1%(w/w)를 각각 첨가하였으며, 고속균질기와 고압균질기를 순차적으로 사용하여 입도가 균일한 두유로 제조하였다. 두유의 저장 안정성 테스트를 위하여 15일 동안 저장(온도=4℃, 25℃ and 37 ℃) 하면서 visual appearance, microstructure, transmittance, particle size distribution, terminal velocity를 각각 측정 하였다. 두유의 상분리는 25 ℃와 37 ℃에서 GSP 0% 첨가의 경우 각각 120 및 48 h 후 GSP 1% 첨가의 경우 각각 192 및 48 h 후에 발생하였으나, 4℃에서는 저장기간 동안에 관찰되지 않았다. 저장기간 동안, 두유의 microstructure는 GSP 0% 첨가의 경우 입자가 응집되는 것이 관찰 되었으나, GSP 1%를 첨가한 경우 두유 입자의 응집 현상은 관찰되지 않았다. 모든 샘플은 저장 시간이 지남에 따라 transmittance가 증가하는 경향을 보였는데, 높은 저장온도에서 transmittance가 빠르게 증가하였다. 두유의 입도크기는 저장 0 h에서 GSP 0% 첨가의 경우 8.8 μm로서 GSP 1% 첨가의 경우(12.3 μm)보다 작은 값을 나타내었다. 이후 저장 시간이 지남에 따라 입도 크기가 감소하는 경향을 보였는데, 저장온도 25 및 37 ℃에서는 저장 2 h 이후부터 GSP 1%와 0% 간에 유의적인 차이는 나타나지 않았으나, 4 ℃ 저장의 경우 360 h에서 GSP 0% 첨가의 경우 0.99 μm로서 GSP 1% 첨가의 경우(0.72 μm)보다 큰 값을 나타내었다. GSP가 입자 침전 속도에 미치는 영향인 terminal velocity는 저장온도 25 및 37 ℃에서는 유의적인 차이는 나타나지 않았으나, 4 ℃ 저장의 경우 360 h 후 GSP 0%와 1% 첨가하였을 때 각각 0.31 mm/h, 0.16 mm/h로 측정되어, GSP를 첨가하는 경우에 terminal velocity를 낮추었다. 위의 결과를 토대로, 천연 계면활성제인 사포닌은 두유의 상분리를 억제하여 저장 안정성을 향상시키는 효과가 있음을 확인하였다.

클로렐라 열수 추출물을 첨가하여 제조한 물김치의 저장 기간 중 품질 안정성을 조사하기 위하여 클로렐라 추출물 분말을 0~0.1%(w/w) 첨가한 물김치를 제조하여 물김치의 숙성 적기에 이르도록 10℃에서 6일간 발효하여 시료를 준비하였다. 최적으로 숙성시킨 클로렐라 추출물 첨가 물김치를 4℃에서 보관하면서 pH, 적정산도 및 젖산균 수의 변화를 경시적으로 조사하였다. 저장 15일까지 대조구와 클로렐라 추출물 첨가 물김치의 pH는 거의 변화하지 않았다. 그러나 적정산도는 모든 물김치에서 동일하게 서서히 증가하여 저장 15일에는 저장 첫날에 비하여 약 2배까지 증가하였다. 또한 저장 중 젖산균 수는 모든 물김치에서 저장 2일 후에 107CFU/g수준으로 약간 감소하였으나 저장 15일까지 107CFU/g이상으로 유지되었다. 전체적으로 4℃에서 클로렐라 추출물을 첨가한 물김치의 저장 중 품질 안정성은 15일까지 대조구와 유사한 경향이었다.

In the present study, we investigate the effects of milling time and the addition of a process control agent (PCA) on the austenite stability of a nanocrystalline Fe-7%Mn alloy by XRD analysis and micrograph observation. Nanocrystalline Fe-7%Mn alloys samples are successfully fabricated by spark plasma sintering. The crystallite size of ball-milled powder and the volume fraction of austenite in the sintered sample are calculated using XRD analysis. Changes in the shape and structure of alloyed powder according to milling conditions are observed through FE-SEM. It is found that the crystallite size is reduced with increasing milling time and amount of PCA addition due to the variation in the balance between the cold-welding and fracturing processes. As a result, the austenite stability increased, resulting in an exceptionally high volume fraction of austenite retained at room temperature.

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.

본 연구는 멍게 껍질을 100.0 % 에탄올 용매로 추출한 후 DMSO로 희석하여 색소안정성을 평가하였다. pH에 따른 흡광도와 색차계 값을 측정한 결과 pH 7.0에서 흡광도와 색도의 ±a값이 가장 안정하게 나타났다. pH 3.0에서 흡광도의 감소가 나타났고 색도의 ±a값이 감소하여 멍게 껍질 색소는 pH가 중성에 가까울수록 변색방지의 효과가 있을 것으로 판단된다. 항산화제 첨가시 색소의 흡광도가 증가하였으며 α-tocopherol과 Glutathione이 가장 우수한 효과를 나타내었다.

본 연구는 홍삼 유화 음료의 유통기한 예측을 위하여 수행하였다. 저장기간 동안 이화학적 특성 (산도, pH, 지방구크기, 색도) 및 관능적 특성의 변화를 주기적으로 조사하였다. 저장 초기에 홍삼 유화 음료의 산도, pH 및 지방구 크기는 거의 변화하지 않았으나 저장 후반기(70일 이후)에는 유의적으로 변화하 였으며 이는 주로 Maillard reaction 의한 것으로 추정하였다. 관능특성과 이화학적 특성들과의 상관분석을 통하여 색도 a 값(적색도)을 홍삼 유화 음료의 이화학적 품질지표로 설정하였다. Arrhenius 식에 의한 a값 변화에 대한 활성화 에너지 및 Q10-value는 각각 13.37 kcal/mol, 1.56-2.14로 조사되었으며, 홍삼 유화 음료의 유통기한은 상온(20℃) 보관의 경우 730일(약 2년)로 예측되었다.

The aim of this paper is to clarify the structural stability of 30m fly(maximum working radius of 30m) and telescopic boom with composition. In order to reduce the weight and insulate, the boom of special vehicle has a 3-stage telescopic boom of DOMEX960, pocket part of acetal, 2-stage refracting boom of ATOS80, insulation boom of glass fiber composition and effector. In this process, CATIA is applied to create 3D modeling, then ANSYS are performed the structural analysis. The structural analysis is performed for a case where the thickness of the insulating boom of the ATOS 80 is 7[㎜] and the thickness of the insulating boom of the FRP material is 15[㎜] and 16[㎜].

본 연구에서는 용액 공정으로 제작된 단분자 기반의 유기 반도체 전계효과 트랜지스터에 적용된 보호막이 유기 트랜지스터의 전기적 안정성에 미치는 영향에 대해여 살펴보았다. Solvay社에서 제공한 용액 공정형 유기 단분자 반도 체를 채널로 사용하여 제작한 유기 트랜지스터는 약 1 cm2/Vs의 상대적으로 높은 이동도를 보였으며, 대략 2.5 ~ 20 k Ωcm 범위의 낮은 접촉저항을 가진 것으로 측정되었다. 무엇보다 중요한 것은, 제작한 유기 트랜지스터에 불소원자가 함유된 Hyflon AD를 보호막으로 적용하였을 때, 보호막을 적용하기 전에 비해 훨씬 더 향상된 전기적 안정성을 보였 다. 이는 불소원자가 함유된 Hyflon AD 고분자막이 대기 중의 수분을 효과적으로 차단하기 때문으로 추측된다.

In recent years, single layer latticed domes have attracted many designers and researchers’s attention all over the world, because single layer latticed domes as space structure are of great advantage in not only mechanical rationality but also function, fabrication, construction and economic aspect. Yamada developed the shape factor S which represents the shape of spherical latticed dome from a structural perspective as well as a geometric perspective. According to a prior study, the structural behavior and the buckling characteristics of the latticed dome were mostly noticeable when the shape factor of latticed dome was in the range of 1.5 to 5. That is, S, in the range of 1.5 to 5, are able to estimate not only overall buckling, but also member buckling and nodal buckling. In this study, we developed shape models using various size of members with the fixed rise-span ratio. One particular characteristic of the latticed dome is that it is not only light in weight but also high in strength. But the aiming at the use of light-weight materials and at the minimized section of members may result in buckling to cause an unstable state of the overall structure when the external force reaches a limitation. Especially, the structural strength is disadvantageous to the snow loads than the earthquake loads because of light-weight, and is greatly affected by the conditions of loading. This paper is to develop the structural stability according to the shapes and load conditions for single-layer latticed spherical dome with 300m span.

In this study, the homogeneity and stability of standard samples for proficiency testing in indoor air quality within the country (formaldehyde, benzene, toluene, ethylbenzene, p-xylene, styrene, TVOC) were evaluated. The procedures and statistical analysis methods applied in ISO/IEC 13528 (2009) and KS A ISO Guide 35 (2005) were applied as evaluation methods. The homogeneity evaluation was a statistical analysis of repeated measurements of each of the 11 ports and between the 11 ports concentration data. As a result, the coefficient of variation (CV) was within the range of 1.9%~5.9%. The difference between the ports was found to be insignificant and met the statistical standard specified in KS Q ISO 13528. The stability evaluation was assessed by the change in concentration over the long-term stability of the standard samples stored for 90 days. The coefficient of variation (CV), which was within the range of 2.6%~9.0%, exhibited changes in the concentration of the long-term stored standard samples. However, the results satisfy the statistical standard specified in KS A ISO Guide 35. Overall, there is no significant difference between the homogeneity of the standard samples by the port and the stability of the long-term stored samples. Therefore, it is considered to be an appropriate method to supply standard samples in an indoor air quality proficiency test.

Fish skin peptide-loaded liposomes were prepared in 100 mL and 1 L solution as lab scales, and 10 L solution as a prototype scale. The particle size and zeta potential were measured to determine the optimal conditions for the production of fish skin peptide-loaded liposome. The liposome was manufactured by the following conditions: (1) primary homogenization at 4,000 rpm, 8,000 rpm, and 12,000 rpm for 3 minutes; (2) secondary homogenization at 40 watt (W), 60 W, and 80 W for 3 minutes. From this experimental design, the optimal conditions of homogenization were selected as 4,000 rpm and 60 W. For the next step, fish peptides were prepared as the concentrations of 3, 6, and 12% at the optimum manufacturing conditions of liposome and stored at 4ºC. Particle size, polydispersion index (pdI), and zeta potential of peptide-loaded liposome were measured for its stability. Particle size increased significantly as manufacture scale and peptide concentration increased, and decreased over storage time. The zeta potential results increased as storage time increased at 10 L scale. In addition, 12% peptide showed the formation of a sediment layer after 3 weeks, and 6% peptide was considered to be the most suitable for industrial application.