• 대한기계학회논문집B
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• 제28권4호
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• pp.371-381
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• 2004

Numerical simulation of $CO_2$ addition effects to fuel and oxidizer streams on flame structure has been conducted with detailed chemistry in H$_2$-O$_2$ diffusion flames of a counterflow configuration. An artificial species, which displaces added $CO_2$ in the fuel- and oxidizer-sides and has the same thermochemical, transport, and radiation properties to that of added $CO_2$, is introduced to extract pure chemical effects in flame structure. Chemical effects due to thermal dissociation of added $CO_2$ causes the reduction flame temperature in addition to some thermal effects. The reason why flame temperature due to chemical effects is larger in cases of $CO_2$ addition to oxidizer stream is well explained though a defined characteristic strain rate. The produced CO is responsible for the reaction, $CO_2$＋H=CO＋OH and takes its origin from chemical effects due to thermal dissociation. It is also found that the behavior of produced CO mole fraction is closely related to added $CO_2$ mole fraction, maximum H mole fraction and its position, and maximum flame temperature and its position.

• Membrane and Water Treatment
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• 제9권4호
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• pp.285-292
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• 2018

In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high $R^2$ value). Finally, the results present that ANN provide best results ($R^2$ value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

• 대한의용생체공학회:의공학회지
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• 제14권3호
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• pp.257-264
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• 1993

A study on the biocompatibility of two types of new glass-ceramics materials, metal disc and dental porcelain that were already made for dental artificial tooth in the previous study, have been attempted. The chemical behavior and the Victor's hardness change in she artificial saliva and Ringer's solution have been also investigated. From the experiment of Implantation of glass-ceramics Into dorsal subcutaneous tissue of Sprague-Dawley rats, glass-cerarmics did not show any particular system of rejection for histrocompatibility.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.109-112
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• 1997

Morphology of carbonate crystals grown on the surface of artificial cell membranes was controlled by changing the interfacial chemistry. For octadecyltriethoxysilane (OTE) films with terminal methyl groups interacting little with an aqueous calcium carbonate solution calcite (104) crystals were formed. Polymerized pentacosadiynoic acid (PDA) films with terminal carboxylic acid groups induced deposition of calcite (012) crystals aligned along with each other within a polymer domain. On the other hand, stearyl alcohol (StOH) films with terminal hydroxyl groups induced deposition of aragonite crystals. When PDA was mixed with StOH, the 8:1 PDA:StOH (molar ratio) film produced dominating calcite (012) crystals without any crystal alignment, and the 4:1 mixture film produced minor calcite (012) crystals and major aragonite crystals. For the 2:1, 1:1, 1:2, and 1:4 mixture films, aragonite crystals were dominating. Hence, it is found that the chemical composition at the interface plays a very important role in controlling the morphology of deposited carbonate crystals.

• 터널과지하공간
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• 제19권3호
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• pp.213-225
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• 2009

본 연구는 실내 화학풍화실험을 통하여 원주일대에 분포하는 화강암 및 화강편마암의 화학적 풍화특성을 평가하는데 목적이 있다. 이를 위하여 이중속실렛추출장치를 이용하여 170여일간의 용탈실험을 수행하고 연구 지역 암석의 화학적 풍화작용에 의한 원소 이동과 물성변화를 측정하였다. 풍화에 따른 구성광물의 반응정도에 따른 차별적 풍화침투와 P파속도의 전반적인 감소가 관찰되었으나, 공극률의 변화는 거의 없는 것으로 확인되었다. 화학풍화실험에 따른 화강암의 일축압축강도는 F 등급에서 20%, SW 등급에서 16% 정도 감소되는 것으로 나타났다. 연구지역에 분포한 화강편마암의 경우에는 뚜렷한 이방성에 의한 일축압축강도의 편차로 인하여 풍화에 따른 암석강도의 저감효과를 평가하기 어렵다. 연구지역에 대한 중 장기적인 풍화 예측을 위해서는 화학적 풍화와 더불어 물리적 풍화가 병행된 조건에서의 고찰 필요하며 앞으로도 심도있는 후속 연구가 요구된다.

• Macromolecular Research
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• 제11권5호
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• pp.368-374
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• 2003

Porous scaffolds composed of gelatin and polysaccharides such as hyaluronic acid and $\beta$-glucan were prepared by using the freeze-drying method after cross-linking with l-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The scaffold had an inter-connected pore structure with the sufficient pore size for use as a support for the growth of fibroblasts. Results for the contact angle and cell attachment confirmed that high gelatin content in a mixture was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures. However, the addition of polysaccharides aroused the synergistic effects of morphologic and mechanical property of gelatin-based scaffolds. To prepare the artificial dermis for the wound dressing to mimic the normal human dermal skin, fibroblasts were isolated from a child's foreskin, and cultured in gelatin-based scaffolds. An in vivo study showed that the artificial dermis containing the fibroblasts enhanced the wound healing rate and re-epithelialization of a full-thickness skin defect rather than the acellular scaffold after one week.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.366-366
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• 2016

Nanoscale observation of attachment systems of animals has revealed various exquisite multiscale architectures for essential functions such as gecko's locomotion, beetles' wing fixation, octopuses' sucking and crawling. In particular, the hierarchical 3-dimensional hexanonal nano-architectures in the tree frog's adhesion is known to have the capability of the enhancement of adhesion forces on the wet or rough surfaces due to the conformal contacts against rough surfaces and water-drainable micro channels. Here, we report that tree frog-inspired patches using unique artificial 3-dimensional hexagonal structures can be exploited to form reversibly enhanced adhesion against various highly curved and rough surfaces in dry and wet condition. To investigate the adhesion effect of micro-channels, we changed the arrangement of microstructure and spacing gaps between micro-channels. In addition, we introduced the 3-dimensional hexagonal hierarchical architectures to artificial patches to enhance to conformal contacts on the various rough surfaces such as skin and organs. Using the robust adhesion properties, we demonstrated the self-drainable and comfortable skin-attachable devices which can measure EKG (electrokardiogramme) for in-vitro diagnostics. As a result, bio-inspired programmable nano-architectures can be applied in versatile devices such as, medical patches, skin-attachable electronics etc., which would shed light on future smart, directional and reversible adhesion systems.

• 대한화학회지
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• 제62권6호
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• pp.433-440
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• 2018

일반적으로 열분해가 폐인조대리석을 재활용하기 위해 적용되어 왔다. 그러나 기존의 열처리 장치는 폐인조대리석 내부로의 비교적 낮은 열전달 효율을 갖는다. 첨가하여 이 장치는 폴리메틸 메타크릴레이트(polymethyl methacrylate; PMMA)의 부분적 탄화 과정에서 불필요한 가스를 과도하게 생성하고 극히 고온에서의 가열로 인해 인화 위험성이 높다. 본 연구는 위의 문제점을 극복 하고자 폐인조대리석에 전분 용액을 첨가한 후 성형 상태에서의 열처리 공정을 제시한다. 실험 결과, 이 방법은 폐인조대리석의 열분해가 비교적 $350^{\circ}C$의 낮은 온도에서도 상당히 향상 되었음을 보였다. 이외에도 메틸메타 크릴레이트(methyl methacrylate; MMA) 및 ${\alpha}$-알루미나(${\alpha}-Al_2O_3$) 회수에 필요한 안전성 확보 및 에너지를 절감하는 효과를 보였다.

• 터널과지하공간
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• 제22권1호
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• pp.32-42
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• 2012

암석에 대한 풍화특성 연구는 시공간적 제약으로 인한 어려움이 따른다. 이 연구는 경상남도 김해시 일대에 분포하는 백악기 화강암에 대하여 물리적 및 화학적 풍화과정을 인공적으로 재현하고 풍화진행에 따른 암석의 지질공학적 특성변화를 고찰하였다. 인공풍화과정에 의하여 시료의 탄성파속도는 현저하게 감소하였으며 공극률 및 흡수율은 뚜렷하게 증가하였다. 초기 풍화등급이 높은 암석일수록 인공풍화과정에 따른 물성변화의 폭이 크며 풍화에 취약한 것으로 나타났다. 공극률, 흡수율 및 탄성파속도는 연구지역의 화강암에 대한 풍화지수로 유용하게 사용할 수 있다. 물리적 및 화학적 풍화과정이 복합적으로 일어나는 조건에서 암석풍화는 더욱 촉진된다. 이 연구에서 복합적인 풍화과정을 재현한 연구방법은 암석의 풍화특성을 규명하고 예측하는 데에 활용할 수 있을 것으로 기대된다.

• 한국조경학회지
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• 제28권2호
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• pp.28-38
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• 2000

The aim of this study is evaluate artificial soils which are used alone or in a blend with field soil for the greening of artificial ground. To achieve these, determination of physicochemical properties was made in four artificial media[Perlite small grain(PSG), perlite large grain(PLG), crushed porous glass+bark(AS), crushed porous glass(CPG)] used alone and/or in a blend with field soil, then evaluation of their effect on th plant growth of Ligustrum obtusifolium and Syringa vulgaris were conducted. In bulk density of root media at field capacity and the saturated hydraulic conductivity, LG and AS showed good performance. But, PLG was though to be unsuitable as artificial soil when used alone because of poor plant growth. PLG, AS, and CPG were thought to be good when it is used in a blend with field soil. But, PSG was thought to be unsuitable. In the result, PSG is recommended as artificial soil which is used alone for greening of artificial ground. PLG is recommended as artificial soil which is used in a blend with field soil. AS is recommended as artificial soil which is used alone and in a blend with field soil. Thought CPG+field soil(v/v, 1:1) might be undesirable in consideration of the chemical properties in six months after planting, it was thought to be superior to th other treatments in the plant growth. CPG can be used as artificial soil which is used in a blend with field soil. Follow-up studies are being conducted to investigate their effects on the plant growth of the other plants and the practical use of them in artificial grounds.