• Journal of Electrochemical Science and Technology
• /
• 제15권3호
• /
• pp.365-372
• /
• 2024

As the energy density of lithium-ion batteries (LIBs) continues to increase, various separators are being developed to with the aim of improving the safety performance. Although poly(imide) (PI)-based separators are widely used, it is difficult to control their pore size and distribution, and this may further increase the risk associated. Herein, a melamine phosphonic acid (MP)-coated PI separator that can effectively control the pore structure of the substrate is suggested as a remedy. After the MP material is embedded into the PI separator with a simple one-step casting process, it effectively clogs the large pores of the PI separator, preventing the occurrence of internal short circuits during charging. It is anticipated that the MP material can also suppress rapid thermal runaway upon cycling due to its ability to reduce the internal temperature of the LIB cell caused by the desirable endothermic behavior around 300℃. According to experiments, the MP-coated PI separator not only decreases the thermal shrinkage rate better than commercial poly(ethylene) (PE) separators but also exhibits a desirable Gurley number (109.6 s/100 cc) and electrolyte uptake rate (240%), which is unique. The proposed separator is electrochemically stable in the range 0.0-5.0 V (vs. Li/Li⁺), which is the typical working potential of conventional electrode materials. In practice, the MP-coated PI separator exhibits stable cycling performance in a graphite-LiNi_0.83Co_0.10Mn_0.07O₂ full cell without an internal short circuit (retention: 90.3%).

• 한국식품영양과학회지
• /
• 제46권6호
• /
• pp.730-738
• /
• 2017

본 연구에서는 커피 분쇄입도 조건에 따라 변화되는 커피의 이화학적 품질특성 및 휘발성 향기성분 변화에 미치는 영향을 조사하기 위하여 분쇄된 원두는 표준체(pore size 850, 600 및 $425{\mu}m$)를 사용하여 입자 크기를 whole bean(Control), $850{\mu}m$ 이상(coarse), $850{\sim}600{\mu}m$(medium), $600{\sim}425{\mu}m$(fine), $425{\mu}m$ 이하(very fine)의 크기가 되도록 사별하여 커피 추출 시료를 제조하였다. 품질특성으로는 pH, 산도, 갈색도, 색도, 총페놀, 카페인, 클로로겐산 함량 및 휘발성 화합물을 비교 분석하였다. pH 및 갈색도는 분쇄입도가 작아질수록 4.84~5.18, 0.257~0.284로 증가하였으나, 산도는 0.31~0.17로 감소하였다. 색도에서 L, a 값은 분쇄입도가 작아질수록 감소하였으나 L 값에서 분쇄입도별 유의적인 차이는 나타나지 않았으며 b 값은 분쇄입도가 제일 작은 very fine size($425{\mu}m$ 이하)에서 15.75로 가장 높은 황색도를 나타내었다. 색차에서 Control과 분쇄 커피분말과의 차이는 11 이상의 색차값을 나타내어 현저한 색의 차이 단계를 나타내었다. 총페놀, 카페인 및 클로로겐산 함량은 분쇄입도가 제일 작은 very fine size 입도($425{\mu}m$ 이하)에서 추출한 커피가 4.54 mg GAE/mL, 733.0 및 $383.7{\mu}g/mL$로 높은 함량을 나타내었고, 휘발성 화합물의 총함량도 100 mg/kg 이상 높게 검출되었다. 따라서 본 연구에서는 커피 추출의 기본 단계라고 할 수 있는 커피 분쇄입도 조건에 따라 변화되는 커피의 이화학적 품질특성을 상호 비교하고 향기성분 특성을 확인함으로써 커피 품질 평가에 관한 기초자료를 제시하였다고 생각된다.

• 동아시아식생활학회지
• /
• 제27권2호
• /
• pp.114-123
• /
• 2017

This study added black lentil ethanol extract to Yakgwa at ratios of 0%, 0.5%, 1.0%, and 2.0%, and its quality characteristics were compared to those of the synthetic antioxidant BHT added to Yakgwa. Yakgwa with black lentil extract had lower moisture content than Yakgwa with BHT (3.98%) but higher content than the control group (5.72%). Higher black lentil extract resulted in less moisture content (p<0.001) as well as a faster expansion rate and oil absorption rate (p<0.001). Scanning Electron Microscopy (SEM) showed that as black lentil extract content increased, pores merged and collapsed, whereas the number of pores decreased and pore size became larger. For chromaticity, all L, a, and b values of the group containing black lentil extract were higher compared to the control group and group with BHT (p<0.001). For texture, as amount of added black lentil extract increased, hardness (p<0.001) and gumminess (p<0.01) increased while cohesiveness (p<0.01) decreased compared to the control group. For sensory characteristics, Yakgwa with 1.0% black lentil extract showed the best preference for all items except for off-flavor. Thus, 1.0% black lentil added to Yakgwa was the best in terms of functionality including preference.

• Restorative Dentistry and Endodontics
• /
• 제14권1호
• /
• pp.25-40
• /
• 1989

This study was conducted to evaluate the influence of 5 microfilled composite resin to fibroblast cultivated from human pulp (age 13). Each composite resin was manually mixed and filled in cylinder. Resin filled cylinders were placed in dishes (35mm in diameter) containing 3 ml of ${\alpha}$-MEM. Filters (pore size 0.22 ${\mu}m$) to simulate dentin were also placed between the bottom of cylinder and the dish floor. Then stored in 5% $CO_2$ containing incubator for 1 and 2 weeks at the temperature 36.6 C. The results analysed after 1 and 2 weeks were as follows: 1. Experimental group except group 2, 2 weeks incubation cases showed the cytotoxicity compared to the control group in cell count. 2. After 2 week-incubation of group 1 and group 4, cell count was more decreased than 1 week cases and cytotoxicity seemed to be constantly influenced to the cell multiplication. 3. The cell growth rate of 1 week incubation in group 3 and group 5 was similar to the control group and recognized the cytotoxicities of these groups were mild. 4. The cell multiplication rate of 2 week incubation cases in group 2 was greater than control group.

• 대한본초학회지
• /
• 제38권2호
• /
• pp.9-16
• /
• 2023

Objectives : Many people use natural soap instead of commercially available bar type general soap for skin care. They tend to prefer cp (cold process) type soaps that go through a sufficient maturation process in formulation. The purpose of this study was to investigate the efficacy of PCPS (placenta cp soap). Methods : The researcher selected 36 subjects, 28 as the experimental group and 8 as the control group. I asked participants to wash their face twice a day in the morning and evening, and the period was set for 6 weeks. The researcher had the people who were selected as the control group use a commercially available foam cleanser, meanwhile the experimental group use PCPS. They performed a skin test before the start of the test, and the change status was continuously investigated after 2 weeks, 4 weeks, and 6 weeks after using the soap. Results : In the case of U zone oil and pores, there was a significant decrease and in the case of skin tone, there was a significant increase in the group of using PCPS. In T zone oil change, there was no significant effect in both the experimental group and the control group. Conclusion : In the case of PCPS, it is recommended to use it in the effect of reducing the size of pores and increasing skin tone, but it can reduce u-zone oil content.

• 국제학술발표논문집
• /
• The 10th International Conference on Construction Engineering and Project Management
• /
• pp.238-241
• /
• 2024

With the development of living standard, people spend more time indoors, and the diversified home decoration will lead to indoor hazardous gas emission. Among them, formaldehyde (HCHO) is one of the most important sources of indoor air pollution, which is commonly found in building materials as a human carcinogen. To address this issue, we developed highly efficient multifunctional green building coatings (GBC) by TiO₂, enhancement silica fume (ESF) and spent fluid catalytic cracking catalysts (sFCCC). Among these prepared GBC, the GBC-0.8 exhibited HCHO removal efficiency of 85.0 % under visible light at ambient temperature, which was much higher than that of commercial coatings (30.8%). In addition, moisture adsorption-desorption carrier tests were executed by different humidity. The humidity control capacity of GBC-0.8 could reach 293.8 g/m² and demonstrate superior stability after 3 cycles. Compared with pristine TiO₂, the addition of ESF and sFCCC showed higher specific surface area and pore size distribution, which was beneficial to improve humidity control and photocatalytic degradation performance. This study provides a promising green method for designing multifunctional green building materials coatings to recycle waste into high-value products and remove HCHO at room temperature

• 구강회복응용과학지
• /
• 제22권4호
• /
• pp.349-365
• /
• 2006

State of problem : A number of investigation about increase of surface area via various surface treatments and modification of surface constituent have been carried out. Purpose : The surface characteristics and stability of implants treated with anodic oxidation, fluoride ion incorporation, and groups treated with both methods were evaluated. Material and method : Specimens were divided into six groups, group 1 was the control group with machined surface implants, groups 2 and 3 were anodic oxidized implants (group 2 was treated with 1M $H_2SO_4$ and 185V, group 3 was treated with 0.25M $H_2SO_4$ and $H_3PO_4$ and 300V). Groups 4, 5 and 6 were treated with fluoride. Group 4 was machined implants treated with 0.1% HF, and groups 5 and 6 were groups 2 and 3 treated with 10% NaF respectively. Using variable methods, implant surface characteristics were observed, and the implant stability was evaluated on rabbit tibia at 0, 4, 8 and 12 weeks. Result : 1. In comparison of the surface characteristics of anodic oxidized groups, group 2 displayed delicate and uniform oxidation layer with small pore size containing Ti, C, O and showed mainly rutile, but group 3 displayed large pore size and irregular oxidation layer with many crators. 2. In comparison of the surface characteristics of fluoride treated groups 4, 5, 6 and non-fluoride treated groups 1, 2, 3, the configurations were similar but the fluoride treated groups displayed rougher surfaces and composition analysis revealed fluoride in groups 4, 5, 6. 3. The fluoride incorporated anodic oxidized groups showed the highest resonance frequency values and removal torque values, and the values decreased in the order of anodic oxidized groups, fluoride treated group, control group. 4. According to implant stability tests, group 2 and 3 showed significantly higher values than the control group (P<.05). The fluoride treated groups showed relatively higher values than the non fluoride treated groups and there were significant difference between group 4 and group 1 (P<.05). Conclusion : From the results above, it can be considered that the anodic oxidation method is an effective method to increase initial bone stability and osseointegration and fluoride containing implant surfaces enhance new bone formation. Implants containing both of these methods should increase osseointegration, and reduce the healing period.

• 대한의용생체공학회:의공학회지
• /
• 제20권2호
• /
• pp.221-230
• /
• 1999

다공성 인공 혈관을 제조하기 위한 새로운 기술에 대하여 연구하였다. 제조방법을 달리하여 만든 다공성의 시편을 준비하여 여러 가지 물성을 비교하였다. 용매/비용매 교환법에 의한 다공성 부여 방법과 고분자 용액의 냉각에 따른 상전이 현상을 이용하여 고분자 용액의 농도와 냉각속도를 달리하여 인공 혈관 시편을 제작하였다. 고분자 용액의 농도가 감소할수록 그리고 냉각속도가 작을수록 인공 혈관 재료로서 유리한 물성을 지닐 수 있음을 알 수 있었다. 위의 방법으로 다공성을 조절함으로써 재료의 기계적 물겅 또한 조절할 수 있음을 알 수 있었다. 냉각 속도를 조절하여 다공성을 부여하는 방법을 이용하여, 고안된 몰드를 사용하여 기존에는 만들기 어려웠던 균일한 두게의 U자형 소구경 인공 혈관을 만들 수 있었다. 비교적 간단한 도구로 균일한 물성을 지니며 원하는 물성의 인공 혈관을 제조할 수 있었다. 온도를 조절하여 고분자 박막에 다공성을 부여하는 기술은 다양한 기능의 의료용 고분자에 접목하여 필요로 하는 기능성을 부여할 수 있는 중요한 기술로 이용할 수 있을 것이다.

• Journal of Electrical Engineering and Technology
• /
• 제1권2호
• /
• pp.246-250
• /
• 2006

Highly ordered gold nanodot arrays have been successfully obtained by vacuum evaporation using an anodic aluminum oxide (AAO) as a shadow mask. An AAO mask with the thickness of 300 um was prepared through an anodization process. The structure of the nanodot arrays was studied by a field- emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectrometer (EDS). A tapping mode atomic force microscope (AFM) was employed for studies of height and phase feature. The nanodot arrays were precisely reproduced corresponding to the hexagonal structure of the AAO mask in a large area. In the gold nanodot arrays, the average diameter of dots is approximately the same as the AAO pore size in the range from 70 um to 80 nm and 100 nm center-to-center spacing. EDS analysis indicated that the gold dots were almost entirely consisted of gold, a highly demanded material.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.54.1-54.1
• /
• 2011

Porous hydroxyapatite has been widely used as clinical implanted material. However, it has poor mechanical properties. To increase the strength as well as the biocompatibility of the porous HAp based artificial bone, it was fabricated by multi-extrusion process. Hydroxyapatite and graphite powders were mixed separately with ethylene vinely acetate and steric acid by shear mixing process. Hydroxyapatite composites containing porous microstructure were fabricated by arranging it in the die and subject it to extrusion process. Burn-out and sintering processes were performed to remove the binder and graphite as well as increase the density. The external and internal diameter of cylindrical hollow core were approximately 10.4 mm and 4.2 mm, respectively. The size of pore channel designed to increase bone growth (osteconduction) was around 150 ${\mu}m$ in diameter. X-ray diffraction analysis and SEM observation were performed to identity the crystal structure and the detailed microstructure, respectively.