• 대한본초학회지
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• 제36권4호
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• pp.31-39
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• 2021

Objectives : The purpose of this study was to find out the efficacy of ginseng on the skin by comparing the difference effect between only MTS (microneedle therapy system) and the ginseng solution application after MTS treatment. Methods : The present author performed once a week and total 3 times of MTS treatment. The treatment time took about 5~10 minutes and the depth of the needle was adjusted according to the participant's skin condition. In the control group, skin toner was applied after MTS and in the experimental group, ginseng extract dissolved toner was applied. One week after each treatment, the change of skin condition was measured. Two weeks after the end of the clinical trial, the skin condition was checked again. Results : In the case of t-zone oil, there was a significant decrease in the test group and in the case of pores and pigmentation, there was a significant decrease in both the test group and the control group, but the degree of significance was greater in the test group. In the case of skin tone, there was an increase, but no significance. Conclusion : The MTS treatment itself showed good effects on t-zone oil, pores, pigmentation, and skin tone. But the effect was much better when the ginseng extract solution was applied to the skin after MTS treatment. This study suggests that ginseng solution increases the efficacy of MTS.

• 한국재료학회지
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• 제31권2호
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• pp.108-114
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• 2021

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/㎤. The density increases to 1.67 g/㎤ 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.

• 한국기계가공학회지
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• 제21권9호
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• pp.85-91
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• 2022

The demand for electric vehicles has increased because of environmental regulations. The lithium-ion battery, the most widely used type of battery in electric vehicles, is composed of a cathode, an anode, and an electrolyte. It is manufactured according to the pole plate, assembly, and formation processes. To improve battery performance and increase manufacturing efficiency, the manufacturing process must be optimized. To do so, simulation can be used to reduce wasted resources and time, and a finite-element method can be utilized. For high simulation quality, it is essential to reflect the material properties of the electrode by considering the pores. However, the material properties of electrodes are difficult to derive through measurement. In this study, the representative volume element method, which is a homogenization method, was applied to estimate the representative material properties of the electrode considering the pores. The representative volume element method assumes that the strain energy before and after the conversion into a representative volume is conserved. The method can be converted into one representative property, even when nonhomogeneous materials are mixed in a unit volume. In this study, the material properties of the electrode considering the pores were derived. The results should be helpful in optimizing the electrode manufacturing process and related element technologies.

• Current Optics and Photonics
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• 제5권4호
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• pp.370-374
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• 2021

Corals are the remains of animals that grow on warm beaches. They have been used as decorative jewels because of their variety of colors, and as medicinal materials for treating cancers, AIDS, and other therapeutic uses because of their chemical elements. Corals are mainly composed of calcium carbonate (CaCO₃) and have many air pores, tens to hundreds of micrometers in size. The refractive indices and absorption coefficients of dried sliced staghorn corals are investigated using terahertz time-domain spectroscopy. The measured values are similar to those for CaCO₃, as expected. It is observed that a sample with a microstructure formed by air pores can guide terahertz waves. The dispersion, effective index, and loss of the guiding modes of coral core surrounded by five triangular air pores are numerically calculated. The simulated spatial distribution of the electric field of the guide mode at 1.25 THz shows the mode to be tightly confined to the core.

• 한국초전도ㆍ저온공학회논문지
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• 제8권1호
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• pp.5-8
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• 2006

The growth properties of MOD-YBCO films were investigated. To enhance the growth rate of YBCO layer and inhibit the build-up of HF gas during the annealing process in TFA-MOD for YBCO coated conductors the method of low pressure annealing was employed. Total pressure was changed from 700Torr to 1Torr and its effect on growth of YBCO films was compared with atmospheric one. The lower Pressure was effective to control of the pore size in MOD method . Surface morphology of YBCO films processed at low total pres sure was rough and composed of random YBCO (103) grains. But large pores, usually observed at atmospheric process in MOD disappeared and also the number of pores was reduced at low pressure annealing. Also discussed ate the effects of Fluorine-free Y and Cu precursor solution on the development of microstructure. Dense surface me phology and with less and small pores can be provided through controlling Fluorine content.

• 대한본초학회지
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• 제38권3호
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• pp.11-18
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• 2023

Objectives : This study aimed to investigate the effect of face washing on pore changes in a controlled environment without external condition changes. The research compared the results of water washing, foam cleanser (F/C) washing, and herb cp (cold process) soap washing on pore reduction. Methods : The experiment was conducted using the same water and towel, in the same place, before and 10 minutes after washing. The skin test was performed before and after washing, and three cases of herb cp soap were tested: Ginseng, Liriope platyphylla (LP), and Castanea crenata inner shell (CCIS). A control group was established using water and F/C washing. Results : Water washing and F/C washing showed a similar degree of pore reduction. Men and individuals with complex skin types showed significantly larger pores. LP cp soap showed the greatest significance in pore reduction. Conclusion : This study found that pore shrinking effects were observed regardless of the use of facial cleansers. LP cp soap was found to be the most effective in reducing pore size. It is important to emphasize the importance of face washing for individuals with large pores and combination skin types, especially men.

• Geomechanics and Engineering
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• 제36권2호
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• pp.121-130
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• 2024

Many foundation projects are built on red-bed soft rocks, and the damage evolution of this kind of rocks affects the safety of these projects. At present, there is insufficient research on the damage evolution of red-bed soft rocks, especially the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation. Therefore, based on the dual-porosity characteristics of pores and fissures in soft rock, we adopted a cellular automata model to simulate the propagation of these voids in soft rocks under an external load. Further, we established a macro-mesoscopic damage model of red-bed soft rocks, and its reliability was verified by tests. The results indicate that the relationship between the number and voids size conformed to a quartic polynomial, whereas the relationship between the damage variable and damage porosity conformed to a logistic curve. The damage porosity was affected by dual-porosity parameters such as the fractal dimension of pores and fissures. We verified the reliability of the model by comparing the test results with an established damage model. Our research results described the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation and provided a theoretical basis for the damage evolution of these rocks.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.521-529
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• 2011

원형 세공과 선형 세공이 독립적으로 발달한 MWW와 구부러진 세공과 선형 세공이 서로 교차하는 MFI 제올라이트에서 세공 구조가 메탄올의 저급 올레핀으로 전환(MTO) 반응에서 생성물 분포와 활성 저하에 미치는 영향을 조사하였다. 산성도가 비슷한 MWW와 MFI 제올라이트는 MTO 반응에서 전환율이 높고 활성 저하가 느린 점이 서로 비슷하지만, MWW에서는 $C_3-C_9$의 선형 탄화수소가 많이 생성되나 MFI에서는 $C_2{^=}$와 방향족 화합물의 수율이 높았다. MTO 반응 중 MWW에는 다고리 방향족 화합물(PAHs)이 많이 축적되나 MFI에서는 벤젠과 나프탈렌 유도체만 생성되었다. MFI와 달리 MWW에 인을 담지하면 MTO 반응에서 촉매 활성과 톨루엔의 흡착량이 크게 줄었다. MWW의 선형 세공에는 MTO 반응 중 PAHs가 축적되어 활성이 없어지나 PAHs가 생성되지 않은 원형 세공에서 선형 탄화수소가 생성된다. 그러나 원형 세공에 인이 담지되면 세공이 막혀 활성이 크게 줄어든다. MFI에는 세공 교차 부분에 인이 담지되어 강한 산점이 중화되어 생성물 분포는 달라지나 활성은 저하되지 않았다. 세공 구조의 차이로 MTO 반응에서 MWW와 MFI의 촉매로서 거동 차이를 설명하였다.

• KSBB Journal
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• 제15권3호
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• pp.285-292
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• 2000

난초를 키우는 화분에 보습용으로 사용되는 다공성 화산석을 2-3 mm크기로 파쇄한 후 $600^{\circ}C$에서 1시간 태워서 가연성 물질 을 제거하고 IN의 염산용액으로$60-70^{\circ}C$에서 2시간 이물질을 녹여댄 후 세척할 경우 효모 고정화에 적당한 담체를 얻을 수 있었다 이 때 염산 용액 대신 NaOH 용액을 세척용액으로 사용 할 수 있으나 담체 구성성분의 용출이 있을 수 있으므로 용액 농도, 처리온도 및 시간에 주의하여야 한다 이렇게 제조된 담체 는 기공의 크기가 $15-80\mu\textrm{m}$이고 충전 밀도는 0.4-0.6 g/mL 였으며 $SiO_2$가 주성분이었고, $Al_2O_3$가 소량함유되어 있었으며, CaO, MgO가 미량 함유되어 있었다. 이 담제의 구조와 효모 고 정화 능력을 국내외 기업에서 제조한 실리카 및 알루미나 재질 의 담체의 경우와 비교한 결과 고상포말법으로 제조한 실리가 담체의 구조 및 고정화능력($5{\times108}$ cells/mL bed)과 비슷한 결 과를 보여 효모 고정화용 담체로 손색이 없었다.. Cordierite 담체 와 알루미나 담체는 고정화능이 실리카 담체의 50% 이하로 낮 았는데 이는 기공의 표면이 매끄럽지 못했기 때문으로 효모가 쉽게 흡착하기 위해서는 가능한 한 매끄러운 표면이 바람직하다 는 사실을 알 수 있었다.

• 한국세라믹학회지
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• 제56권2호
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• pp.178-183
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• 2019

A process of fabricating the foamed glass that has closed pores with 8 ~ 580 ㎛ sizes without a blowing agent by sintering 10 ㎛ boron-free glass powder composed of CaO, MgO, SO₃, Al₂O₃-83 wt% SiO₂ at a molding pressure of 0 ~ 120 MPa and a sintering temperature of 750 ~ 1000℃ was investigated. To analyze the glass transition temperature of glass powder, thermogravimetric analysis-differential thermal analysis (TGA-DTA) method were used. The microstructure and pore size of foamed glass were examined using the optical microscopy and field emission scanning electron microscopy (FE-SEM). For the thermal diffusivity and color of the fabricated samples, a heat flow meter and ultraviolet-visible-near-infrared (UV-VIS-NIR)-colormetry were used, respectively. In the TGA-DTA result, the glass transition temperature of glass powder was confirmed to be 626℃. In the microstructure result, closed pores of 7 ~ 20 ㎛ were formed at 750 ~ 900℃, and they were not affected by the molding pressure and sintering temperature. However, at 1,000℃, when there was 0 MPa molding pressure, closed pores of 580 ㎛ were confirmed, and the pore size decreased as the molding pressure increased. Moreover, at a molding pressure of 30 MPa or higher, closed pores of approximately 400 ㎛ were formed. The porosity showed an increasing trend of smaller molding pressure and larger sintering temperature, and it was controllable in the range of 5.69 ~ 68.45%. In the thermal diffusivity result, there was no change according to the molding pressure, and, by increasing the sintering temperature, up to 0.115 W/m·K could be obtained. The Lab color index (CIE-Lab) results all showed a similar translucent white color regardless of molding pressure and sintering temperature. Therefore, based on the foamed glass without boron and blowing agent, it was confirmed that white foamed glass, which has closed pores of 8 ~ 580 ㎛ and a thermal diffusivity characteristic of 0.115 W/m·K, can be fabricated by changing the molding pressure and sintering temperature.