• Journal of the Korean Wood Science and Technology
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• 제26권2호
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• pp.6-15
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• 1998

A total of forty five-ply, 30- by 30-cm lauan and larch plywood sheets were manufactured in the laboratory using commercial urea and phenol resin adhesives; half of these sheets were treated with fresh concrete. Each sheet was carbonized for 2, 4, and 6hours at $400^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$, respectively, and their physical properties were measured. The yie1d of charcoal decreased as carbonization temperature and time increased. Charcoal yield was greater in plywood than in veneer, and slightly greater in plywood treated with concrete compared to untreated plywood. Plywood manufactured with phenol resin adhesive had higher pH, higher equilibrium moisture content (EMC), and greater adsorption of methylene-blue dye compared to plywood manufactured with urea resin. For concrete-treated plywood, pH was greater than 10 even when the sheets were carbonized for 2hours at $400^{\circ}C$. Although the EMC of the phenol resin plywood was higher than that of the urea resin plywood, EMC of the phenol resin was lower than that of the urea resin. The larch phenol resin plywood that was carbonized for 6 hours at $750^{\circ}C$ adsorbed more methylene-blue than did the commercia1 wood-based activated charcoal as a result of total pore volume and surface area.

• 한국지반공학회지:지반
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• 제5권4호
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• pp.47-60
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• 1989

해성토는 유기질등 부폐등으로 흔히 methane등을 생성하여 개스를 간극속에 함유하는 경우가 많다. 따라서 이 개스는흙의 포화를 방해하게 되고,외부에서 작용하는 압력에 따라흙의 반응이 다양하게 나타난다. 특히, 개스를 함유한 흙의 거동의 대표적인 차이에는 비배수상태에서 외력이 작용할 때의 반응에 관한 것이다. 본 연구는 비배수 및 배수상태하에서 개스를 함유한 흙의 압밀거동을 실험을 통해 관찰하고, 개스를 포함한 간극수의 변화는 총응력에 상관관계가 있음을 알았으며, 압밀 압력의 변화에 따른 개스기포를 감싸는 포화된 흙의 거동을 분석하였고, 비배수상태에서 반복하중이 작용하는 경우, gassy soil의 거동을 살펴보았다.

• 한국지반환경공학회 논문집
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• 제12권6호
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• pp.17-23
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• 2011

본 연구에서는 석유계총탄화수소와 톨루엔을 토양세정에 의해 제거하기 위하여 일련의 실험을 수행하였다. 회분식 실험 결과 Triton X-100과 SWA 1503의 경우 각각 79.0%와 69.0%의 TPH 제거효율을 나타내었다. 계면활성제의 농도 1-11mmol/L에서 계면활성제 농도 증가에 따라 TPH 제거효율은 증가하였으나 주입량 대비 제거효율 고려 시 최적 농도는 1mmol/L로 나타났다. 칼럼 실험 결과 최적의 유속은 0.3mL/min으로 나타났다. PAM(Physical Aquifer Model) 실험 결과 3 PV(Pore Volume) 동안 토양세정을 통해 주입한 톨루엔 중 약 5.5%가 제거된 것으로 나타났다. 따라서 토양세정의 효율을 증가시키기 위해서는 계면활성제의 재순화 또는 재이용을 통한 최적 운전조건의 도출이 필요하다.

• Journal of the Korean Wood Science and Technology
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• 제30권4호
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• pp.33-40
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• 2002

본 연구는 한국산 주요 수종의 간벌재 및 목질재료 탄화물의 흡착 특성과 기본적인 성질과의 관계를 검토하였다. 탄화온도가 높아지고, 탄화시간이 길어짐에 따라 국산 간벌재 탄화물의 메틸렌블루 흡착량(MBA)이 증가하는 경향을 보였지만, 탄화온도 600℃에서 최고치를 보이는 목재 수종도 있었다. 수종간 MBA에는 큰 차이가 있었는데 가장 큰 값은 잣나무 탄화물(134 m²/g)이였고, 가장 작은 값은 굴참나무 탄화물(34 m²/g)이였다. 또한 침엽수재는 활엽수재보다 높은 MBA를 나타냈으며, MBA와 탄화전 간벌재의 기건비중과는 부의 상관성을 나타냈다. 목질재료 탄화물의 MBA도 탄화온도가 높아지고, 탄화시간이 길어짐에 따라 증가하는 경향을 보였고, 목질 재료간 MBA의 차이는 크지 않았다. 목질재료 탄화물의 MBA는 간벌재 탄화물에 비해 낮은 수준을 나타내는 것으로 드러났다. 탄화온도가 높아지고, 탄화시간이 길어짐에 따라 간벌재 및 목질재료 탄화물의 비표면적, 총세공용적은 증가하는 경향을 보였고, 탄화온도 600℃에서 MBA의 최고치를 보인 수종은 비표면적도 같은 온도에서 최고치를 나타냈다. MBA와 비표면적 및 총 세공용적간에는 정의 상관을 보였다. 목질재료 탄화물에는 주로 미세 세공이 발달하는 것으로 밝혀졌다.

• 상하수도학회지
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• 제21권6호
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• pp.671-678
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• 2007

2-methylisoborneol (MIB) is a musty odor compound produced as a secondary metabolite by some cyanobacteria and actinomycetes. It is lead to distrust in tap water due to taste and odor. It is well known that activated carbon (AC) adsorption is the best available technology to remove 2-MIB and geosmin. In this study, physical characteristics of virgin AC and reactivated AC was compared. The effect of variation of NOM molecular weight on adsorption of 2-MIB in virgin AC and reactivated AC were also evaluated. BET surface area was decreased by 13 to 23% and total pore volume was decreased by 18 to 21% due to first and second reactivation compare to the virgin carbon. However, mesopore volume ($V_{meso}$) was increased about 14% after reactivation. It showed that micropore volume was decreased and move to mesopore or macropore after reactivation. Decreased adsorption capacity of 2-MIB was greatly related to below 3000Da. Adsorption capacity of 2-MIB was rather greater in virgin AC than in reactivated, which is strongly related to micropore volume.

• Korean Membrane Journal
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• 제1권1호
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• pp.100-105
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• 1999

A novel system to thicken the concentrated colloidal solution from membrane water treat-ment processes was developed. A hollow-fiber microfilter(hydrophilic polyethylene nominal pore size 0.1 ${\mu}$m total surface area 0.42 m2) was installed in an acrylic housing that has an aeration port 5 cm below the membrane and a clarifier in the bottom. The concentrate was uniformly supplied from the top of the housing. Bacuum filtration caused downward flow of concentrate and as a result thickening interface. The addition of poly-aluminum chloride (PAC) resulted in rapid increase of trans-membrane pressure (TMP) and in no improvement of the filtered water turbidity and thickening process. Two types of con-centrate and concentrate turbidity had little effect on the increase of TMP and concentrate thickening. It was observed that for the same height of membrane housing membrane surface area to housing volume (A/V) ratio had significant effect on the increase of TMP. When the housing volume was increased ten times the increasing rate of TMP was three times faster as compared to the original housing. A hydraulic model successfully simulated the formation and sedimentation of thickening interface.

• 농업과학연구
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• 제27권2호
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• pp.125-134
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• 2000

This observation was to investigate the influence of raw organic matter incorporated into soil at various rates on hydraulic conductivity and elution of solute throughout soil column. Generally the organic matter content in a practical agricultural field was approximately 3%. However, the application rate of organic matter in the field tends to rapidly increase in these days. Therefore, we raised the application rate of organic matter up to 10% in this investigation. From the experiment, we found that the hydraulic conductivities rapidly decreased with increasing rate of organic matter as well as rapid decrease in total volume of eluent during the same period. And electrical conductivities in the effluent significantly decreased after 2 pore volume, resulting in approaching to the criteria of saline soli. From this we could assume that the organic matter may influence the crop growth in the beginning. However excessive irrigation in the field may cause saturation of soil leading to reduction of soil. Therefore, there must be a management methods in application of organic matter with respect to soil water control.

• 한국토양환경학회지
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• 제3권2호
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• pp.101-114
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• 1998

토양오염 정화방법의 하나인 토양증기추출법 (soil vapor extraction, SVE) 은 오염된 토양에 진공 또는 가압의 공기를 공급하여 연속적인 공기 흐름을 유도함으로써 토양의 기공에 잔류하는 유해화합물의 증발을 촉진하여 오염물질을 제거하는 공정이다. 본 연구에서는 토양증기추출법의 효율에 영향을 주는 인자들 가운데에서 토양의 수분함량과 오염물질의 종류가 오염물질의 제거효율에 미치는 영향에 대하여 실험연구를 수행하였다. 인공토양으로 미세기공이 없는 glass bead, sand, 그리고 미세기공이 많고 흡착능이 강한 molecular sieve가 사용되었으며, 오염물질로는 톨루엔, 메틸에틸케톤, 트리클로로에틸렌이 사용되었다. 본 연구에서는 오염물질의 탈착실험을 180분 이내로 수행하였으며, 이 범위 내에서는 인공토양으로부터의 유기화합물 탈착 현상에서 제거효율과 기공부피수, 각각에 로그를 취하였을 때 선형적 특성이 나타났다. 여기에서 기공부피수란 반응기를 통과한 공기의 부피를 기공부피로 나눈 것이다. 세 가지 유기화합물 모두 수분함량이 0%일 때 가장 낮은 제거속도를 보였으며 일정량의 수분이 포함됨으로써 유기화합물 제거에 필요한 기공부피수가 현저히 줄어듦을 관찰할 수 있었다. 또한, 트리클로로에틸렌과 같이 밀도가 큰 유기화합물의 제거를 위해서는 많은 양의 기공부피수가 소요되며 따라서 작업시간이 매우 길어지게 되므로, 토양증기추출법 외에 다른 정화방법을 함께 사용하여야 한다. 또한 인공토양의 특성에 따른 유기화합물의 탈착현상에 대하여 조사하였으며, 미세기공의 유무가 오염물질의 탈착속도에 미치는 영향이 톨루엔과 메틸에틸케톤에서 상이하게 나타났음을 알 수 있었다. 이러한 연구결과는 정화대상지역의 토양특성, 오염물질 등에 대한 조사를 시행한 후 SVE를 이용한 적절한 정화방법을 설계하는데 기초자료로 이용할 수 있을 것이다.

• 한국식생활문화학회지
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• 제34권6호
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• pp.793-800
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• 2019

This study was performed to examine the physicochemical and antioxidative properties of the sponge cakes with different contents (0, 2, 4, 6, 8%, w/w) of lemon balm (Melissa officinalis) powder (LBP). An increase in LBP content in the cake led to a significant increase in the baking loss rate, specific volume, DPPH radical scavenging activity, ABTS radical scavenging activity, total phenol contents and total flavonoid contents of the cakes (p<0.05). As the LBP content increased, significant decreases were shown in the specific gravity of batter, sugar contents, pH, lightness, redness and yellowness of the cakes (p<0.05). Ash contents, uniformity index and other textural properties of hardness, springness, cohesiveness, and brittleness did not show any significant differences between the sample groups (p>0.05). These results suggest that LBP can be applied to sponge cakes to achieve positive textural properties such as uniform pore formation and increased volume with increased antioxidant properties.

• Advances in concrete construction
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• 제4권2호
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• pp.71-88
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• 2016

Metakaolin, a dehydroxylated product of the mineral kaolinite, is one of the most valuable admixtures for high-performance concrete applications, including constructing reinforced concrete bridges and impact- and fire-resistant structures. Concretes produced using metakaolin become more homogeneous and denser compared to normal-strength concrete. Yet, these changes cause a change of volume throughout hardening, and increase the brittleness of hardened concrete significantly. In order to examine how the use of metakaolin affects the fracture and mechanical behavior of high-performance concrete we produced concretes using a range of water to binder ratio (0.42, 0.35 and 0.28) at three different weight fractions of metakaolin replacement (8%, 16% and 24%). The results showed that the rigidity of concretes increased with using 8% and 16% metakaolin, while it decreased in all series with 24% of metakaolin replacement. Similar effect has also been observed for other mechanical properties. While the peak loads in load-displacement curves of concretes decreased significantly with increasing water to binder ratio, this effect have been found to be diminished by using metakaolin. Pore structure analysis through mercury intrusion porosimetry test showed that the addition of metakaolin decreased the critical pore size of paste phases of concrete, and increasing the amount of metakaolin reduced the total porosity for the specimens with low water to binder ratios in particular. To determine the optimal values of water to binder ratio and metakaolin content in producing high-strength and high-performance concrete we applied a multi-objective optimization, where several responses were simultaneously assessed to find the best solution for each parameter.