• Title/Summary/Keyword: large pores

Search Result 280, Processing Time 0.028 seconds

The Effect of Seosiokyongsan fermented soap on facial pores (서시옥용산 발효비누가 얼굴모공에 미치는 영향)

  • CHoi, Sang Rak;Kim, Jeong Ja;Koo, Jin Suk
    • The Korea Journal of Herbology
    • /
    • v.34 no.2
    • /
    • pp.33-39
    • /
    • 2019
  • Objectives : The pores are the openings of sebaceous glands or apocrine glands. They are enlarged by various factors such as sex, age, genetic influence, sebum secretion, acne and so on. When the pores are visually recognizable, they become aesthetically problematic. There are various methods of treating pores, but we have tried to develop a method to reduce pore size by using daily cleanser. Methods : Facial skin examination was performed on 104 students of A university. Among them, 10 persons with large pore size were selected. We surveyed 72 students to determine their subjective skin condition, lifestyle, and washing habits etc. We made herbal fermented soaps using Seosiokyongsan and distributed them to experiment participants. We let them wash their face in the morning and evening for 6 weeks using herbal fermented soap. Prior to the experiment, their skin condition was checked and assessed using A-ONE Smart One-Click Automatic Facial Diagnosis System three times at 3-week intervals. After the experiment, the changes of skin were measured and analyzed through facial analysis test. Results : In our experiment, the early 20s, 9.6% of the students had slightly larger pores. For students with large pores, there was a high likelihood of side effects from using facial products. Using the fermented soap made of Seosiokyongsan, the average size of the pores and the number of large-sized pores were significantly reduced. Conclusion : Seosiokyongsan fermented soap can effectively reduce especially the large size of pores.

Synthesis of Porous Cu-Sn by Freeze Drying and Hydrogen Reduction Treatment of Metal Oxide Composite Powders (금속산화물 복합분말의 동결건조 및 수소분위기 환원처리에 의한 Cu-Sn 다공체 제조)

  • Kim, Min-Sung;Yoo, Ho-Suk;Oh, Sung-Tag;Hyun, Chang-Yong
    • Korean Journal of Materials Research
    • /
    • v.23 no.12
    • /
    • pp.722-726
    • /
    • 2013
  • Freeze drying of a porous Cu-Sn alloy with unidirectionally aligned pore channels was accomplished by using a composite powder of CuO-$SnO_2$ and camphene. Camphene slurries with CuO-$SnO_2$ content of 3, 5 and 10 vol% were prepared by mixing with a small amount of dispersant at $50^{\circ}C$. Freezing of a slurry was done at $-25^{\circ}C$ while the growth direction of the camphene was unidirectionally controlled. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies were hydrogen-reduced at $650^{\circ}C$ and then were sintered at $650^{\circ}C$ and $750^{\circ}C$ for 1 h. XRD analysis revealed that the CuO-$SnO_2$ powder was completely converted to Cu-Sn alloy without any reaction phases. The sintered samples showed large pores with an average size of above $100{\mu}m$ which were aligned parallel to the camphene growth direction. Also, the internal walls of the large pores had relatively small pores. The size of the large pores decreased with increasing CuO-$SnO_2$ content due to the change of the degree of powder rearrangement in the slurry. The size of the small pores decreased with increase of the sintering temperature from $650^{\circ}C$ to $750^{\circ}C$, while that of the large pores was unchanged. These results suggest that a porous alloy body with aligned large pores can be fabricated by a freeze-drying and hydrogen reduction process using oxide powders.

Fabrication of Al2O3 Dispersed Porous Cu by Freeze Drying of CuO-Al2O3/Camphene Slurry (CuO-Al2O3/camphene 슬러리의 동결건조 공정에 의한 Al2O3 입자분산 Cu 다공체 제조)

  • Kang, Hyunji;Riu, Doh-Hyung;Oh, Sung-Tag
    • Journal of Powder Materials
    • /
    • v.25 no.1
    • /
    • pp.25-29
    • /
    • 2018
  • Porous Cu with a dispersion of nanoscale $Al_2O_3$ particles is fabricated by freeze-drying $CuO-Al_2O_3$/camphene slurry and sintering. Camphene slurries with $CuO-Al_2O_3$ contents of 5 and 10 vol% are unidirectionally frozen at $-30^{\circ}C$, and pores are generated in the frozen specimens by camphene sublimation during air drying. The green bodies are sintered for 1 h at $700^{\circ}C$ and $800^{\circ}C$ in $H_2$ atmosphere. The sintered samples show large pores of $100{\mu}m$ in average size aligned parallel to the camphene growth direction. The internal walls of the large pores feature relatively small pores of ${\sim}10{\mu}m$ in size. The size of the large pores decreases with increasing $CuO-Al_2O_3$ content by the changing degree of powder rearrangement in the slurry. The size of the small pores decreases with increasing sintering temperature. Microstructural analysis reveals that 100-nm $Al_2O_3$ particles are homogeneously dispersed in the Cu matrix. These results suggest that a porous composite body with aligned large pores could be fabricated by a freeze-drying and $H_2$ reducing process.

Synthesis of Porous Cu-Co using Freeze Drying Process of Camphene Slurry with Oxide Composite Powders (산화물 복합분말 첨가 Camphene 슬러리의 동결건조 공정에 의한 Cu-Co 복합계 다공체 제조)

  • Lee, Gyuhwi;Han, Ju-Yeon;Oh, Sung-Tag
    • Journal of Powder Materials
    • /
    • v.27 no.3
    • /
    • pp.193-197
    • /
    • 2020
  • Porous Cu-14 wt% Co with aligned pores is produced by a freeze drying and sintering process. Unidirectional freezing of camphene slurry with CuO-Co3O4 powders is conducted, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The dried bodies are hydrogen-reduced at 500℃ and sintered at 800℃ for 1 h. The reduction behavior of the CuO-Co3O4 powder mixture is analyzed using a temperature-programmed reduction method in an Ar-10% H2 atmosphere. The sintered bodies show large and aligned parallel pores in the camphene growth direction. In addition, small pores are distributed around the internal walls of the large pores. The size and fraction of the pores decrease as the amount of solid powder added to the slurry increases. The change in pore characteristics according to the amount of the mixed powder is interpreted to be due to the rearrangement and accumulation behavior of the solid particles in the freezing process of the slurry.

Packing of Alumina Particles in 3D Preform of Mullite Fiber by Slurry Pressure-Infiltration (슬러리 가압함침에 의한 3D Mullite 섬유 Preform의 알루미나 입자 충전)

  • Sim, Soo-Man
    • Journal of the Korean Ceramic Society
    • /
    • v.50 no.6
    • /
    • pp.528-532
    • /
    • 2013
  • Well-dispersed slurries of submicron-sized alumina powders were pressure-infiltrated in 3D preforms of mullite fibers and the effects of the particle size and infiltration pressure on the particle packing characteristics were investigated. Infiltration without pressure showed that the packing density increased as the particle size decreased due to the reduction of the friction between the particles and the fibers. The infiltrated preforms contained large pores in the large voids between the fiber tows and small pores in the narrow voids between the individual fibers. Pressure infiltration resulted in a packing density of 77% regardless of the particle size or the infiltration pressure(210 ~ 620 kPa). Pressure infiltration shortened the infiltration time and eliminated the large pores in preforms infiltrated with the slurries of smaller particles. The slurry pressure-infiltration process is thus an efficient method for the packing of matrix materials in various preforms.

Fabrication of Porous Mo by Freeze-Drying and Hydrogen Reduction of MoO3/Camphene Slurry (MoO3/camphene 슬러리의 동결건조 및 수소환원에 의한 Mo 다공체 제조)

  • Lee, Wonsuk;Oh, Sung-Tag
    • Journal of Powder Materials
    • /
    • v.19 no.6
    • /
    • pp.446-450
    • /
    • 2012
  • In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using $MoO_3$ powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% $MoO_3$ slurries, prepared by milling at $50^{\circ}C$ with a small amount of dispersant, were frozen at $-25^{\circ}C$. Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at $750^{\circ}C$, and sintered at $1000-1100^{\circ}C$ for 1 h. After heat treatment in hydrogen atmosphere, $MoO_3$ powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about $150{\mu}m$ which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores due to the difference in the camphene growth rate during freezing process. The size of small pores was decreased with increase in sintering temperature, while that of large pores was unchanged. The results are strongly suggested that the porous metal with required pore characteristics can be successfully fabricated by freeze-drying process using metal oxide powders.

Synthesis and Microstructure of Porous Al2O3 with Nano-Sized Cu Dispersions (나노크기 Cu 분산입자를 갖는 Al2O3 다공체의 제조 및 미세조직 특성)

  • Yoo, Ho-Suk;Kim, An-Gi;Hyun, Chang-Yong
    • Korean Journal of Materials Research
    • /
    • v.23 no.1
    • /
    • pp.67-71
    • /
    • 2013
  • Porous $Al_2O_3$ dispersed with nano-sized Cu was fabricated by freeze-drying process and solution chemistry method using Cu-nitrate. To prepare porous $Al_2O_3$, camphene was used as the sublimable vehicle. Camphene slurries with $Al_2O_3$ content of 10 vol% were prepared by milling at $50^{\circ}C$ with a small amount of oligomeric polyester dispersant. Freezing of the slurry was done in a Teflon cylinder attached to a copper bottom plate cooled to $-25^{\circ}C$ while unidirectionally controlling the growth direction of the camphene. Pores were subsequently generated by sublimation of the camphene during drying in air for 48 h. The green body was sintered in a furnace at $1400^{\circ}C$ for 1 h. Cu particles were dispersed in porous $Al_2O_3$ by calcination and hydrogen reduction of Cu-nitrate. The sintered samples showed large pores with sizes of about $150{\mu}m$; these pores were aligned parallel to the camphene growth direction. Also, the internal walls of the large pores had relatively small pores due to the traces of camphene left between the concentrated $Al_2O_3$ particles on the internal wall. EDS analysis revealed that the Cu particles were mainly dispersed on the surfaces of the large pores. These results strongly suggest that porous $Al_2O_3$ with Cu dispersion can be successfully fabricated by freeze-drying and solution chemistry routes.

Fabrication of Porous Ni by Freeze Drying and Hydrogen Reduction of NiO/Camphene Slurry (NiO/camphene 슬러리의 동결건조 및 수소환원 공정에 의한 Ni 다공체 제조)

  • Jeong, Jae-Hun;Oh, Sung-Tag;Hyun, Chang-Yong
    • Journal of Powder Materials
    • /
    • v.26 no.1
    • /
    • pp.6-10
    • /
    • 2019
  • In this study, freeze drying of a porous Ni with unidirectionally aligned pore channels is accomplished by using a NiO powder and camphene. Camphene slurries with NiO content of 5 and 10 vol% are prepared by mixing them with a small amount of dispersant at $50^{\circ}C$. Freezing of a slurry is performed at $-25^{\circ}C$ while the growth direction of the camphene is unidirectionally controlled. Pores are generated subsequently by sublimation of the camphene during drying in air for 48 h. The green bodies are hydrogen-reduced at $400^{\circ}C$ and then sintered at $800^{\circ}C$ and $900^{\circ}C$ for 1 h. X-ray diffraction analysis reveals that the NiO powder is completely converted to the Ni phase without any reaction phases. The sintered samples show large pores that align parallel pores in the camphene growth direction as well as small pores in the internal walls of large pores. The size of large and small pores decreases with increasing powder content from 5 to 10 vol%. The influence of powder content on the pore structure is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

Photoionization of $TiO_2$ Particles Incorporated into Silica Gels Studied by EPR Spectroscopy

  • Ahn, Sang-Won;Kang, Kee-Hoon;Hong, Dea-Il
    • Journal of the Korean Magnetic Resonance Society
    • /
    • v.4 no.1
    • /
    • pp.50-63
    • /
    • 2000
  • Titanium dioxide particles with three different average sizes, prepared by three different methods, were incorporated into silica gel pores by impregnation. The titanium dioxide incorporated into the silica gel pores was photoionized by 240-400 nm irradiation at 77 K by a one-photon process to from trapped hole centers on OH group and trapped electron centers on titanium which were detected by electron paramagnetic resonance at 77 K. During the impregnation the smallest size range of TiO2 particles can be incorporated into silica gels with 2.5-1.5 nm pores. However, the largest size range of TiO2 particles can only be incorporated into silica gels with 6-15 nm pores and not into silica gels with 2.5-4 nm pores. The photoyield and stability of photoinduced hole and electron centers depends on the silica pore sizes of silica gels and surface area as well as on the TiO2 loading. In large pore silica gels and large particle size of TiO2, photoinduced charge separation reaches to a plateau at shorter irradiation times and the trapped hole and electron centers are more stable to decay.

  • PDF

Fabrication of Porous Cu-Ni by Freeze Drying and Hydrogen Reduction of CuO-NiO Powder Mixture (CuO-NiO 혼합분말의 동결건조 및 수소환원에 의한 Cu-Ni 다공체 제조)

  • Seo, Han Gil;Oh, Sung-Tag
    • Journal of Powder Materials
    • /
    • v.21 no.1
    • /
    • pp.34-38
    • /
    • 2014
  • Cu-Ni alloys with unidirectionally aligned pores were prepared by freeze-drying process of CuO-NiO/camphene slurry. Camphene slurries with dispersion stability by the addition of oligomeric polyester were frozen at $-25^{\circ}C$, and pores in the frozen specimens were generated by sublimation of the camphene during drying in air. The green bodies were hydrogen-reduced at $300^{\circ}C$ and sintered at $850^{\circ}C$ for 1 h. X-ray diffraction analysis revealed that CuO-NiO composite powders were completely converted to Cu-Ni alloy without any reaction phases by hydrogen reduction. The sintered samples showed large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The pore size and porosity decreased with increase in CuO-NiO content from 5 to 10 vol%. The change of pore characteristics was explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.