• Title, Summary, Keyword: Mesopore

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Analysis of the Factors Influencing the Mesopore Ratio on the Soil Surface to Investigate the Site Factors in a Forest Stand(II) - With a Special Reference to Deciduous Stands - (산림(山林)의 입지환경인자(立地環境因子)가 표층토양(表層土壤)의 조공극율(粗孔隙率)에 미치는 영향인자(影響因子) 분석(分析)(II) - 활엽수림(闊葉樹林)을 중심(中心)으로 -)

  • Jeong, Yongho;Park, Jae Hyeon;Kim, Kyong Ha;Youn, Ho Joong
    • Journal of Korean Society of Forest Science
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    • v.90 no.4
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    • pp.450-457
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    • 2001
  • This study aimed to clarify the influencing site factors of the mesopore ratio on a pore geometry of surface soil in deciduous stands as an index of the water retention capacity. Fifteen factors including site conditions and soil properties were analyzed by spss/pc+ for the data collected during March to October of 1994. The factors influencing the mesopore ratio(pF2.7) on the surface soil were as follows; tree height, under vegetation coverage and organic matter contents of soil. And influencing factor on the ratio of mesopore in the soil surface was correlated with surface soil hardness shows high negative significance. Also, multiple regression equations for mesopore ratios of surface soil hardness, organic matter contents of soils show high significance($R^2=0.84$). In deciduous stands, it is effective in promoting development on the ratio of mesopore that forest practice for enhancing of the water resource retention capacity should be carried out when the under vegetation coverage rates of stands are maintained from 30 to 80 percentages.

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Analysis of the Factors Influencing the Mesopore Ratio on the Soil Surface to Investigate the Site Factors in a Forest Stand (III) - With a Special Reference to Mixed Stands - (산림(山林)의 입지환경인자(立地環境因子)가 표층토양(表層土壤)의 조공극률(組孔隙率)에 미치는 영향인자(影響因子) 분석(分析) (III) - 혼효임(混淆林)을 중심(中心)으로 -)

  • Park, Jae Hyeon;Jeong, Yongho;Kim, Kyong Ha;Youn, Ho Joong
    • Journal of Korean Society of Forest Science
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    • v.90 no.6
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    • pp.683-691
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    • 2001
  • This study aimed to clarify the influencing factors of the mesopore ratio on a pore geometry of surface soil in mixed stands as an index of the water retention capacity. Twenty four factors including site conditions and soil properties were analyzed by spss/pc+ for the data collected from during March to October of 1995. The factors influencing the mesopore ratio(pF2.7) on the surface soil were as follows; mesopore ratio(pF2.7) on the B horizon soil, under vegetation coverage, organic matter contents of surface soil and F layer depth. And influencing factor on the ratio of mesopore in the soil surface was correlated with surface soil hardness and depth of 10cm soil hardness shows high negative significance. Also, multiple regression equations for mesopore ratio of the mesopore ratio of B horizon soil and organic matter contents shows high significance($R^2$; 0.84).

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Improved Mesoporous Structure of High Surface Area Carbon Nanofiber for Electrical Double-Layer Capacitors

  • Lee, Young-Geun.;An, Geon-Hyoung;Ahn, Hyo-Jin
    • Korean Journal of Materials Research
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    • v.27 no.4
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    • pp.192-198
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    • 2017
  • Carbon nanofiber (CNF) is used as an electrode material for electrical double layer capacitors (EDLCs), and is being consistently researched to improve its electrochemical performance. However, CNF still faces important challenges due to the low mesopore volume, leading to a poor high-rate performance. In the present study, we prepared the unique architecture of the activated mesoporous CNF with a high specific surface area and high mesopore volume, which were successfully synthesized using PMMA as a pore-forming agent and the KOH activation. The activated mesoporous CNF was found to exhibit the high specific surface area of $703m^2g^{-1}$, total pore volume of $0.51cm^3g^{-1}$, average pore diameter of 2.9 nm, and high mesopore volume of 35.2 %. The activated mesoporous CNF also indicated the high specific capacitance of $143F\;g^{-1}$, high-rate performance, high energy density of $17.9-13.0W\;h\;kg^{-1}$, and excellent cycling stability. Therefore, this unique architecture with a high specific surface area and high mesopore volume provides profitable synergistic effects in terms of the increased electrical double-layer area and favorable ion diffusion at a high current density. Consequently, the activated mesoporous CNF is a promising candidate as an electrode material for high-performance EDLCs.

Analysis of the Factors Influencing the Mesopore Ratio on the Soil Surface to Investigate the Site Factors in a Forest Stand(I) - With a Special Reference to Coniferous Stands - (산림(山林)의 입지환경인자(立地環境因子)가 표층토양(表層土壤)의 조공극률(粗孔極律)에 미치는 영향인자(影響因子) 분석(分析)(I) - 침엽수림(針葉樹林)을 중심(中心)으로 -)

  • Jeong, Yongho;Park, Jae Hyeon;Kim, Kyong Ha;Youn, Ho Joong
    • Journal of Korean Society of Forest Science
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    • v.90 no.3
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    • pp.314-323
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    • 2001
  • This study aimed to clarify the influencing factors of mesopore ratio on a pore geometry of surface soil in coniferous stands as an index of the water retention capacity. Twenty three factors including site conditions and soil properties were analyzed by spss/pc + for the data collected during March to October of 1993. The factors influencing the mesopore ratio(pF2.7) on the surface soil were as follows; macropore ratio(pF1.6), slope, crown-cover rates, thickness of F layer, organic matter contents, and the growing stock. And influencing factor on the ratio of mesopore in the soil surface was correlated with percentage of amount of clay, soil surface, A and B horizon soil hardness shows high negative significance. Also, multiple regression equations for mesopore ratios of surface soil and surface soil hardness, clear length, growing stock, B horizon of soil hardness, organic matter contents show high significance($R^2$; 0.80). In coniferous stands, it is effective in promoting development on the ratio of mesopore that forest practice for enhancing of the water resource retention capacity should be carried out when the crown-cover rates of stands are more than 80 percentages.

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Highly Ordered Porous Silica Adsorbent with Dual Pore Size Regime for Bulky VOC Gas Sensing

  • Yun, Ji Sun;Jeong, Young Hun;Nam, Joong-Hee;Cho, Jeong-Ho;Paik, Jong-Hoo
    • Journal of Sensor Science and Technology
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    • v.22 no.3
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    • pp.181-184
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    • 2013
  • Highly ordered porous materials having mesopores in the walls of macropores showed improved adsorption dynamics results for VOC molecules, especially bulky molecules. These meso/macroporous mataerials were synthesized by the dual templating method, and mesopore and macropore size were controlled by adjusting the templates for each pore size regime. In the case of adsorption and desorption of small VOC molecules (toluene), although meso/macroporous MCM-41 with smaller mesopore size showed improved results, meso/macroporous SBA-15 with larger mesopore size was not improved regardless of the existence of macropores, since there was no limitation of movement through the larger mesopore. However, the adsorption dynamics of bulky VOC molecules (p-xylene) over meso/macroporous SBA-15 were drastically improved by increasing the macropore size.

Effects of Forest Practices on the Changes of Characteristics of Forest Stand, Mesopore Ratio and Soil Water Contents in Pinus koraiensis Stands (산림시업이 잣나무림의 생장, 토양조공극 및 토양함수능에 미치는 영향)

  • Jun, Jaehong;Jeong, Yongho;Choi, Hyung Tae;Yoo, Jae-Yun
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.11 no.3
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    • pp.20-27
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    • 2008
  • This study was conducted to investigate the influence of thinning and pruning on characteristics of forest stand, mesopore ratio and soil water content at the Pinus koraiensis stands in Gwangneung, Gyeonggido. The Pinus koraiensis had been planted in 1976 and thinning and pruning were carried out in 1996. A sample area survey was conducted at experimental plots (thinned and unthinned) in 1998 and 2005, and mesopore ratio and soil water content have been monitored from 2000 to present. Average tree height of the thinned plot increased from 10.9m to 13.2m and from 10.3m to 12.8m for the unthinned plot. Average D.B.H of the thinned plot increased from 15.9cm to 21.1cm and from 14.5cm to 16.7cm for the unthinned plot during the period 1998-2005. Crown density at the thinned plot increased from 81.5% to 95.0% and from 89.5% to 95.0% for the unthinned plot during the period 1998-2005. Mesopore ratio (pF2.7) of A layer soil at the thinned plot was 40.1% while that of the unthinned plot was 37.3%. Changes of mesopore ratio at unthinned plot were not associated with stand age, but those at thinned plot had increased and then decreased, showing declining of the practice effect. Average soil water content at the thinned plot were 23.7% and 22.4% for the unthinned plot. Soil watercontents at both plots have been increased with increase in stand age. But the difference of soil watercontent at each plot has been decreased, especially at the depth of 10cm.

Carbonization and Activation Behaviors of Metal Containing Carbon Fibers (금속함유 탄소섬유의 탄화 및 활성화 거동)

  • Young Ok CHOI;Kap Seung YANG
    • Proceedings of the Korean Fiber Society Conference
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    • pp.98-100
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    • 2003
  • The efficiency of the adsorption of adsorbents depends on both pore size and shape. In other to adsorb hydrated ion in application of electric double layer capacitor (EDLC), mesopore is necessary[1,2]. Tamai et al.[3] reported that an increased portion of mesopore was introduced through addition of metal or organometallic compound in the precursor and following activation of the carbon fibers with steam. (omitted)

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Effect of pore structure on electrochemical performance of EDLC (EDLC의 전기화학적 성능에 대한 메조기공 구조의 효과)

  • Lee, Myung-Suk;Shin, Yun-Sung;Lee, Jong-Dae
    • Journal of the Korean Applied Science and Technology
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    • v.27 no.3
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    • pp.310-317
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    • 2010
  • The electrochemical properties of electric double layer capacitor(EDLC) was studied by controlling pore size distribution and specific surface area of the activated carbon fiber(ACF). The mesoporous ACF, which was prepared by the iron exchange method, showed the tendency of increasing average pore size and decreasing total surface area. The mesoporous ACF (surface area = 2225 $m^2$/g, pore size=1.93 nm) showed increased mesopore(pore size=1~3nm) volume from 0.055 cc/g to 0.408 cc/g compared to its raw ACF. The charging capacity of the EDLC which uses the prepared mesoporous ACF also increased from 0.39 F/$cm^2$ to 0.55 F/$cm^2$. From these results, it can be known that the electrochemical properties of EDLC are mainly dependent on the specific surface area, but above the surface area 2200 $m^2$/g, it is the mesopore volume that affects the performance of the capacitor considerably. Because the increased mesopore volume results in a decreased ion mobility resistance, the charge capacitance is enhanced.

Preparation of Silica Monoliths with Macropores and Mesopores and of High Specific Surface Area with Low Shrinkage using a Template Induced Method

  • Guo, Jianyu;Lu, Yan;Whiting, Roger
    • Bulletin of the Korean Chemical Society
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    • v.34 no.2
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    • pp.447-452
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    • 2013
  • In this study we report a new method for the synthesis of a silica monolithic column bed with bimodal pores (throughpores and mesopores). The template induced synthesis method was used to direct bimodal pores simultaneously instead of the usual post base-treating method. Block polymer Pluronic F127 was chosen as a dual-function template to form hierarchically porous silica monolith with both macropores and mesopores. This is a simplification of the method of monolithic column preparation. Poly(ethylene glycol) was used as a partial substitute for F127 can effectively prevent shrinkage during the monolith aging process without losing much surface area (944 $m^2/g$ to 807 $m^2/g$). More importantly, the resultant material showed a much narrower mesopore size (centered at 6 nm) distribution than that made using only F127 as the template reagent, which helps the mass transfer process. The solvent washing method was used to remove the remaining organic template, and it was proved to be effective enough. The new synthesis method makes the fabrication of the silica monolithic column (especially capillary column) much easier. All the structure parameters indicate that monolith PFA05 prepared by the above method is a good material for separation, with the merits of much higher surface area than usual commercial HPLC silica particles, suitable mesopore volume, narrow mesopore size distribution, low shrinkage and it is easily prepared.

Fabrication and Characterization of Porous TiO2 Powder by Aerosol Process (에어로졸공정에 의한 다공성 TiO2분말의 제조 및 공극특성)

  • Chang, Han Kwon;Jang, Hee Dong;Park, Jin Ho;Cho, Kuk;Kil, Dae Sup
    • Korean Chemical Engineering Research
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    • v.46 no.3
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    • pp.479-485
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    • 2008
  • Porous $TiO_2$ nanostructured particles containing both mesopores and macropores were fabricated by utilizing an aerosol templating method from two kinds of starting materials (colloidal mixture of $TiO_2$ nanoparticles and PS particles, and that of TTIP solution and PS particles). The effects of mixing ratio of PS to $TiO_2$ and reactor temperature on the particle properties were investigated. When $TiO_2$ nanoparticles were used as starting materials, the increase of macropores number was observed by SEM and the specific surface area and total pore volume were increased from $31.6m^2/g$ to $39.1m^2/g$ and $0.068cm^3/g$ to $0.089cm^3/g$, respectively, by increasing the weight mixing ratio of $PS/TiO_2$ from 0.79 to 1.31. When TTIP was used as precursor, the specific surface area and mesopore volume of particles prepared at same condition decreased by 67% and 75%, respectively.