본 연구에서는 고분자 점도 조절제를 첨가하여 졸-겔법 기반 알루미나 나노여과막을 단일 공정으로 제조하고, 코 팅층의 구조 및 성능을 제어하는 방법을 제시하였다. Hydroxypropyl cellulose (HPC, Mw ~80000) 고분자를 알루미나 졸에 첨가하여 점도를 10 mPa·s에서 최대 4200 mPa·s까지 조절하였으며, 이를 통해 알루미나 중공사 지지체 표면에 균일하고 결 함이 없는 선택층을 형성하였다. HPC 함량이 증가할수록 코팅층 두께가 증가하였으나, 기공 크기 증가에 따라 분리 성능이 저하되었다. 2:1 (졸:HPC 고분자 용액) 혼합비에서 제조된 나노여과막은 두께 3.20 μm의 얇은 선택층을 형성하여 높은 수투 과도(12.9 LMH/bar)와 우수한 제거 성능(PPG 1050 Da 제거율 60%, PEG 1500 Da 제거율 90%, MgCl2 제거율 80%)을 나타 냈다. 반면, 1:2 혼합비에서는 선택층 두께가 10.2 μm로 증가하였으나, 기공 크기가 증가하여 3400 Da MWCO와 64% 염 제 거율을 보였다. HPC 고분자를 활용한 점도 제어는 졸-겔 코팅층의 두께, 기공 구조 및 분리 성능을 효과적으로 조절할 수 있 음을 입증하였다.

This research explores the mechanical behavior of whole blood as a shear-thinning fluid and examines yield stress as a crucial parameter for evaluating flow properties in the microvasculature. While previous studies have primarily focused on whole blood viscosity (WBV), this study presents an engineering-based approach to quantitatively evaluate the yield stress of non-Newtonian whole blood using a U-shaped capillary tube. A custom-designed scanning capillary tube, incorporating a biocompatible U-shaped capillary channel, was employed to determine whole blood viscosity (WBV) across shear rates from 1 to 1,000 s⁻1. Yield stress was estimated by extrapolating the shear stress-shear rate relationship using a non-Newtonian shear-thinning flow model. The analysis revealed a strong cubic correlation between hematocrit and yield stress, suggesting an increased risk of flow impairment in the microvasculature with elevated hematocrit levels. This work emphasizes the critical influence of yield stress in regulating microvascular blood flow, particularly under low-shear conditions.

This study evaluates the analytical performance of a newly developed miniaturized disposable U-tube for an automated blood viscometer and compares it to conventional viscometers. Whole blood viscosity (WBV), essential for circulatory function, exhibits non-Newtonian behavior, posing challenges for measurement at low shear rates. The blood viscometer, based on a scanning capillary tube method, used disposable U-tubes to measure viscosities across a shear rate range of 1s⁻¹ to 1,000s⁻¹. Precision evaluation showed stable coefficients of variation (CV) across different viscosity levels. Repeatability assessment indicated consistent CV values, demonstrating the reliability of the device. The agreement with the LV-III Brookfield viscometer and MCR 92 Rheometer was analyzed using Bland-Altman plots, which revealed minor systematic biases and consistent differences across the measurement range. Correlation analysis using Passing-Bablok regression showed high correlation coefficients (R > 0.96) with regression slopes close to 1. The newly developed miniaturized disposable U-tube exhibits excellent precision, reliable repeatability, and high correlation with established methods, enhancing laboratory productivity and offering potential for clinical applications. Further studies with human blood samples are recommended to confirm its clinical applicability.

PURPOSES : The objective of this study is to evaluate the feasibility of applying properties of asphalt binder other than absolute viscosity (AV) to evaluate the rejuvenation level of the binder from reclaimed asphalt pavement (RAP) in recycled asphalt mixtures (RAMs). METHODS : The G*/sin and critical temperature (CT) for determining high performance grade by DSR, and the large molecular size (LMS) using gel-permeation chromatography (GPC) were measured simultaneously with the AV of two virgin asphalt binders (58–22 for RAM and 64–22 for normal mix) and recovered binders from a RAP and four RAMs. Based on mix design, 20%, 30%, 40%, and 50% recycled RAMs were prepared, and the deformation strength (SD) of the RAMs were measured. The AV, LMS, G*/sin , and CT were measured from the recovered binders from each RAM of the SD-tested specimens. Regression analyses were performed between the LMS and AV, G*/ sin and AV, and CT and AV to determine the correlation of each property with the AV. The feasibility of evaluating the rejuvenation level of the RMA binder using the three properties (LMS, G*/sin , and CT) was evaluated. Regression analysis was performed between SD and AV, and the feasibility of using SD instead of AV ≤ 5,000 poise (p) was analyzed to evaluate the rejuvenation level of the RAM. RESULTS : The AV, LMS, G*/sin , and CT of RAM binders increased with the recycling ratio. Mixes with recycle ratios of 20% and 30% satisfied the AV ≤ 5,000 p criterion, unlike mixes with higher recycle ratios. The regression analysis results showed that the R2 values between the LMS and AV, G*/sin and AV, and CT and AV exceeded 0.96. Since these regressions showed extremely high R2 values, it can be inferred that the estimation of binder rejuvenation level using the LMS, G*/sin and CT, i.e., instead of the AV criterion, is applicable. Because SD exhibits high correlation with the binder stiffness, and the regression between SD and AV indicated R2 > 0.98, SD can be applied instead of the AV for binder rejuvenation level estimation. The main advantage of using the LMS and SD is to estimate the binder rejuvenation level without recovering the binder from the mix. CONCLUSIONS : For the binder rejuvenation level estimation of recycled mixes, it is concluded that the LMS by GPC and G*/sin and CT by DSR, and SD can be applied instead of the AV criterion. However, since this study was performed using limited materials, further studies involving many other materials may be performed to generalize the current conclusion.

Recently, air pollution from fossil fuels is at a serious level, and the IMO proposes to reduce greenhouse gas emissions by about 70% by 2050, and controls greenhouse gas emissions by applying the energy efficiency disign index(EEDI) to each ship type. In this study, the marine fuel oil viscosity of MGO, MDO, HFO and CGO according to the temperature change was compared and measured and the difference was analyzed. As a result, the viscosity of CGO was 3.32mPa·s, which was almost similar to MGO(3.40mPa·s) and MDO(3.51mPa·s) so it was judged that it could be used as a marine fuel, and it was found that there was a significant difference with HFO at P<0.01 there was.

이 연구는 최대근력형과 근지구력형 저항운동이 총운동량과 혈액점도 및 적혈구용적률에 미치는 영향을 조사하고자 하였다. 연구대상자는 저항운동 경력 12개월 이상의 20대 남성 15명으로 선정하였으며, 실험 전 벤치프레스 1RM을 측정하였으며, 조건 별 실험은 1주일간의 간격을 두고 교차배분하여 6세트 씩 최대반복수행 하였다. 그 결과 총운동량은 근지구력강도가 최대근력강도에 비해 높게 나타났으며 (p<.001), 혈액점도와 적혈구용적률은 총운동량에 관계없이 운동 전보다 운동 후에 높아졌다(p<.01). 종합 하면 혈액점도는 운동강도와 운동량에 영향을 받지 않으며, 일회성 저항운동으로 증가한다는 것을 알 수 있었다. 이는 저항운동 프로그램을 구성하는데 있어 임상적으로 의의가 있으며 혈관질환에 관련된 임상환 자들의 운동프로그램을 작성하는데 있어 참고자료가 될 수 있을 것으로 판단된다.

In the manufacturing of bulk graphite, pores produced by vaporization and discharge of volatile materials in binders during carbonization reduce the density of bulk graphite, which adversely affects the electrical conductivity, strength and mechanical properties. Therefore, an impregnation process is introduced to fill the pores and increase the density of bulk graphite. In this study, bulk graphite is prepared by varying the viscosity of the impregnant. The microstructure of bulk graphite is observed. The flexural strength and electrical resistivity are measured. As the viscosity of the impregnants decreases and the number of impregnations increases, it is shown that the number of pores decreases. The density before impregnation is 1.62 g/cm3. The density increases to 1.67 g/cm3 and porosity decreases by 18.6 % after three impregnations using 5.1 cP impregnant, resulting in the best pore-filling effect. After three times of impregnation with a viscosity of 5.1 cP, the flexural strength increases by 55.2 % and the electrical resistivity decreases by 86.76 %. This shows that a slight increase in density due to the pore-filling effect improves the properties of bulk graphite.

Pores produced by carbonization in bulk graphite process degrade the mechanical and electrical properties of bulk graphite. Therefore, the pores of bulk graphite must be reduced and an impregnation process needs to be performed for this reason. In this study, bulk graphite is impregnated by varying the viscosity of the impregnant. The pore volume and pore size distribution, according to the viscosity of the impregnant, are analyzed using a porosimeter. The total pore volume of bulk graphite is analyzed from the cumulative amount of mercury penetrated. The volume for a specific pore size is interpreted as the amount of mercury penetrating into that pore size. This decreases the cumulative amount of mercury penetrating into the recarbonized bulk graphite after impregnation because the viscosity of the impregnant is lower. The cumulative amount of mercury penetrating into bulk graphite before impregnation and after three times of impregnation with 5.1cP are 0.144 mL/g and 0.125 mL/gm, respectively. Therefore, it is confirmed that the impregnant filled the pores of the bulk graphite well. In this study, the impregnant with 5.1 cP, which is the lowest viscosity, shows the best effect for reducing the total pore volume. In addition, it is confirmed by Raman analysis that the impregnant is filled inside the pores. It is confirmed that phenolic resin, the impregnant, exists inside the pores through micro-Raman analysis from the inside of the pore to the outside.

In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2–3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

Tungsten heavy alloys (W–Ni–Fe) play an important role in various industries because of their excellent mechanical properties, such as the excellent hardness of tungsten, low thermal expansion, corrosion resistance of nickel, and ductility of iron. In tungsten heavy alloys, tungsten nanoparticles allow the relatively low-temperature molding of high-melting-point tungsten and can improve densification. In this study, to improve the densification of tungsten heavy alloy, nanoparticles are manufactured by ultrasonic milling of metal oxide. The physical properties of the metal oxide and the solvent viscosity are selected as the main parameters. When the density is low and the Mohs hardness is high, the particle size distribution is relatively high. When the density is high and the Mohs hardness is low, the particle size distribution is relatively low. Additionally, the average particle size tends to decrease with increasing viscosity. Metal oxides prepared by ultrasonic milling in high-viscosity solvent show an average particle size of less than 300 nm based on the dynamic light scattering and scanning electron microscopy analysis. The effects of the physical properties of the metal oxide and the solvent viscosity on the pulverization are analyzed experimentally.

국내 법적 기준에 따라 2016년부터 거의 모든 도로 포장에 아스팔트 혼합물 물량의 40% 이상을 재활용 아스팔트 혼합물로 사용하게 되었다. 이에 따라 폐아스팔트 콘크리트를 이용한 재활용 아스팔트 혼합물의 품질확보가 중요한 이슈로 부각되고 있다. 아스팔트 콘크리트 포장은 아스팔트 플랜트에서 아스팔트 혼합물이 생산되어 현장에 시공된 후 공용 중에 환경하중, 교통하중 등에 의하여 물성이 변화되고, 누적된 피로에 의해 결국은 파손에 이르게 된다. 이에 따라 도로에서 발생된 폐아스팔트 콘크리트는 아스팔트 혼합물 생산시의 품질, 공용기간, 환경하중이나 교통하중 등에 따라 노화정도가 다르며 물성이 다양하다. 그러므로 폐아스팔트 콘크리트를 이용한 아스팔트 콘크리트 순환골재(이후 순환골재라고 함)의 품질은 폐아스팔트 콘크리트 발생 당시의 물성과 밀링 방법, 순환골재 생산과정에서의 파쇄 및 선별 방법 등에 따라 영향을 받아 변동된다. 따라서 재활용 아스팔트 포장의 조기 균열 등의 문제가 발생하지 않기 위해서는 배합설계시 순환골재의 물성에 따라 노화된 아스팔트를 회복시켜 줄 수 있는 재생 첨가제 등의 적합한 함량을 결정하고, 생산된 아스팔트 혼합물에 포함된 아스팔트의 점도 회복이 중요하다. 본 연구의 목적은 재활용 아스팔트 혼합물 배합설계시 아스팔트 점도를 회복시키기 위한 설계 방안을 제시하는 것이다. 국내 기준에서 재활용 아스팔트 혼합물에서 추출한 아스팔트의 점도는 5,000 Poise 이하이어야 한다. 이에 따라 국내에서는 혼합물 생산 및 운반의 단기노화 과정에서의 점도변화를 감안하여 대부분 설계점도를 2,000 Poise로 설정하고 배합설계를 수행한다. 그런데, 해외 연구 결과 재생 첨가제의 특성에 따라 단기노화 과정에서의 점도 변화율이 다른 것으로 나타났다. 이에 따라 본 연구에서는 혼합 전의 설계점도, RFTO 단기 노화 후의 점도, 제작된 아스팔트 혼합물에서 추출된 아스팔트 점도 등을 비교하여 적합한 배합설계 방안을 검토하였다