• Carbon letters
• /
• 제25권
• /
• pp.103-112
• /
• 2018

Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be $700^{\circ}C$. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of $2861.4m^2\;g^{-1}$. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of $402.3F\;g^{-1}$ at $0.5A\;g^{-1}$, a good rate capability of 79.8% at current densities from $0.5A\;g^{-1}$ to $10A\;g^{-1}$, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at $20A\;g^{-1}$.

• Carbon letters
• /
• 제10권3호
• /
• pp.181-189
• /
• 2009

Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at $950^{\circ}C$ in $N_2$ atmosphere followed by activation of the resultant char at different temperatures for 5 h in $CO_2$ atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than $2260\;m^2/g$ and $1.63\;cm^3/g$ respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.

• 건축역사연구
• /
• 제16권4호
• /
• pp.37-56
• /
• 2007

The '凸'-shaped, the '呂'-shaped and the hexagonal-shaped pit houses were excavated at the Youngdong area, some location along the upper the Imjin River and Han River between the Iron age and the kingdom of Hanseong Baekje. The aim of this study is to analyze various structural system and developement of the pit house with rectangular plan. It is considered a matter in all its aspects which are plan, scale, aspect, pillar holes, carbonized wood and several traces. These pit houses removes the pillar on the inside or it reduces to secure a wider space, it pursued the chamfered corner, the change of the front, the entrance fixed. Also these adopted diverse structural systems(the chuandou structure, the structural system of columns and beams and a bearing wall). But in the course of time, the Korean wooden architecture is developed gradually the structural system of columns and beams. It is presumed the result that overcome the limit with the close space and pursue the flowing space and compose a group of organizable buildings.

• Journal of Electrical Engineering and information Science
• /
• 제2권3호
• /
• pp.71-76
• /
• 1997

A lot of experiments and analyses have been done to determine the aging mechanism of mica-epoxy composite material used for large generator stator windings in order to estimate remaining life of the generator for last decades. After degrading artificially the mica-epoxy composite material, the surface analysis is performed to analyze breakdown mechanism of insulation in air and hydrogen atmosphere; i) In the case of air atmosphere, it is observed that an aging propagation from conductor to core by partial discharge effect and the formation of cracks between layers is widely carbonized surface. ii) In case of hydrogen atmosphere, the partial discharge effect is reduced by the hydrogen pressure (4kg/$\textrm{cm}^2$). Potassium ions forming a sheet of mica is replaced by hydrogen ions, which can lead to microcracks. It is confirmed that the sizes of crack by SEM analysis are 10∼20[$\mu\textrm{m}$] in length under air, and 1∼5[$\mu\textrm{m}$] in diameter, 10∼50[$\mu\textrm{m}$] in length under hydrogen atmosphere respectively. The breakdown mechanism of sttor winding insulation materials which are composed of mica-epoxy is analyzed by the component of materials with EDS, SEM techniques. We concluded that the postassium ions of mica components are replaced by H\ulcorner, H$_3$O\ulcorner at boundary area of mica-epoxy and/or mica-mica. It is proposed that through these phenomena, the conductive layers of potassium enable creation of voids and cracks due to thermal, mechanical, electrical and environmental stresses.

• Journal of the Korean Wood Science and Technology
• /
• 제20권2호
• /
• pp.31-42
• /
• 1992

In this study, the relative effectiveness of antimony trioxide-containing coat on fire retardancy of plywood, particleboard and medium density fiberboard was investigated and compared through ISO ignition test and inclined panel test with non-coated ones. The results obtained were summarized as fallows: Any treated materials was not ignited in inclined panel test with 5 minutes, but only particleboard among treated ones burned in ISO ignition test with fairly delayed time. The weight loss rate of plywood decreased with the increased addition level of fire-retardant and the least values were obtained in particleboard and MDF at addition level of 7% and 5% respectively. Carbonized area of wood based materials decreased with the increased addition level of fire retardant. The temperatures of back in plywood, particleboard treated with fire-retard ant coat containing 7% $Sb_2O_3$ showed the lowest but MDF did not show any effectiveness with the increased addition level. The first flash time of plywood treated with fire retardant coat containing 9% $Sb_2O_3$, MDF and particleboard treated with fire retardant coat containing 7% $Sb_2O_3$ were 257sec., 286.4sec., 165.4sec. respectively.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 추계 학술논문 발표대회
• /
• pp.172-173
• /
• 2019

As the damage to fine dust increased, the Republic of Korea designated fine dust as a social disaster. The composition of the fine dust is composed of carbon, sulfate, nitrate, ammonium and minerals. The cause of fine dust is naturally generated by dirt, pollen, etc. In addition, there are artificial causes such as gaseous vehicle exhaust gas emitted from the use of fossil fuel. When fine dust enters the human body through breathing, it causes various respiratory diseases and skin diseases. In IARC, fine dust was designated as a carcinogen group 1. In this research, we tried to adsorb fine dust by physical adsorption using powdered activate carbon. Powdered activate carbon is a powdered activated carbon activated in a carbonized state. Porous material with high specific surface area and low density. Experimental items were tested for density, water absorption, and fine dust concentration according to the PAC addition ratio. Basic experiments were carried out to fabricate the fine dust adsorption matrix.

• 생물환경조절학회지
• /
• 제16권2호
• /
• pp.108-114
• /
• 2007

피트모스를 기본으로 한 3종의 혼합 고형배지의 물리화학적 특성 분석과 3종의 배지 및 양액농도(EC $0.5{\sim}1.5dS{\cdot}m^{-1}$가 토마토(일광 토마토 ) 플러그묘의 초기생장(파종 후 31일째)에 미치는 영향을 조사하였다. 혼합배지의 물리화학적 특성은 피트모스의 혼입비율이 많아질수록 보수력이 증가하였고, 공극율은 모든 혼합 배지 처리에서 80% 이상이었다. pH와 EC피트모스의 혼입비율이 많을수록 pH는 낮아졌고, EC는 전반적으로 $3.6{\sim}4.8dS{\cdot}m^{-1}$ 정도의 범위로 비교적 높게 나타났다. 양질의 토마토 플러그묘 생산에 가장 좋았던 혼합배지는 피트모스:왕겨:훈탄:부숙톱밥:펄라이트=25:10:25:20:20(v/v)였다. 관비 양액농도(EC)는 대조구(수돗물, EC $1dS{\cdot}m^{-1}$)에 비해 관비 양액농도(EC 0.5, 1.0, $1.5dS{\cdot}m^{-1}$)가 높아질수록 초장, 엽면적 및 총건물 생산량 등이 현저히 높아졌다.

• 청정기술
• /
• 제19권3호
• /
• pp.279-286
• /
• 2013

탄소원으로 구형 고분자수지 중 폴리스티렌-DVB 공중합으로 제조된 양이온교환수지를 사용하여 활성탄제조 시 활성탄의 주요물성인 비표면적과 비용적에 미치는 운전인자의 영향이 실험적으로 연구되었다. 활성탄의 비표면적과 비용적은 탄화공정에서 탄화온도 및 탄화시간이 증가함에 따라 감소하였고, 활성화공정에서는 활성화온도와 활성화시간에 따라 증가하였지만 특정 온도와 시간 이상에서는 감소하였다. 탄화공정에서 승온속도가 증가함에 따라 감소하였지만, 반대로 활성화 후 승온속도에 비례하는 물성을 보였다. 2가이온으로 포화된 수지로 제조된 활성탄은 새 수지로 제조된 활성탄에 비해 낮은 비표면적을 보였다.

• 한국응용과학기술학회지
• /
• 제31권3호
• /
• pp.408-415
• /
• 2014

In order to prepare high-quality activated carbons (ACs), coal tar pitch (CTP), and mixtures of CTP and petroleum pitch (PP) were activated with KOH. The ACs prepared by activation of CTP in the range of $700{\sim}1000^{\circ}C$ for 1~5 h had very porous textures with large specific surface areas of $2470{\sim}3081m^2/g$. The optimal activation conditions of CTP were determined as CTP/KOH ratio of 1:4, activation temperature of $900^{\circ}C$, and activation time of 3 h. The obtained AC showed the highest micro-pore volume, and pretty high specific surface area and meso-pore volume. The micro-pore volumes and specific areas of activated mixtures of CTP and PP were similar to each other but the meso-pore volume could be increased. In order to change the degree of crystallinity of precursors before KOH activation process, the CTPs were carbonized in the range of $500{\sim}900^{\circ}C$. As the carbonization temperature increased, the specific surface area and pore volume of the activated ACs with the same activation conditions for CTP decreased dramatically. It was demonstrated that the increased pore size distribution of AC electrodes in the range of 1 to 2 nm plays an important role in the performance of electric double-layer capacitor.

• 공업화학
• /
• 제34권2호
• /
• pp.153-160
• /
• 2023

본 논문에서는 미이용 바이오매스로부터 바이오차를 생산하고 메틸렌블루 흡착 특성을 평가하였다. 바이오매스는 주로 셀룰로오스, 헤미셀룰로오스, 리그닌으로 구성되어 있으며 회분의 함량은 벌채부산물에서 가장 높았다. 탄화 온도가 증가할수록 탄화 수율은 감소하였으며, 수소와 산소 함량도 감소하였다. 반면, 탄소 함량은 증가하였다. 탄화 온도가 증가할수록 바이오차의 비표면적과 미세기공은 증가하였다. 바이오차 비표면적은 탄화 온도 600 ℃에서 가장 높았다(216.15~301.80 m² /g). 600 ℃에서 탄화한 바이오차를 이용하여 메틸렌블루 흡착 실험을 수행한 결과, 참나무, 벌채부산물, 사과 전정가지의 흡착 거동은 Freundlich model, 복숭아 전정가지는 Langmuir model에 적합하였다. 흡착 동역학에서 참나무와 복숭아 전정가지는 pseudo-first-order model, 벌채부산물과 사과 전정가지는 pseudo-second-order model에 적합하였다.