• Environmental Engineering Research
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• 제20권2호
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• pp.181-189
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• 2015

A composite material was tested to eliminate phenol in aqueous solution combining adsorption on activated carbon and photocatalysis with $TiO_2$ in two different ways. A first implementation involved a sequential process with a loop reactor. The aim was to reuse this material as adsorbent several times with in situ photocatalytic regeneration. This process alternated a step of adsorption in the dark and a step of photocatalytic oxidation under UV irradiation with or without $H_2O_2$. Without $H_2O_2$, the composite material was poorly regenerated due to the accumulation of phenol and intermediates in the solution and on $TiO_2$ particles. In presence of $H_2O_2$, the regeneration of the composite material was clearly enhanced. After five consecutive adsorption runs, the amount of eliminated phenol was twice the maximum adsorption capacity. The phenol degradation could be described by a pseudo first-order kinetic model where constants were much higher with $H_2O_2$ (about tenfold) due to additional ${\bullet}OH$ radicals. The second implementation was in a continuous process as with a fixed bed reactor where adsorption and photocatalysis occurred simultaneously. The results were promising as a steady state was reached indicating stabilized behavior for both adsorption and photocatalysis.

• 대한원격탐사학회지
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• 제20권3호
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• pp.153-162
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• 2004

In the summer of 1998-2001, a huge flood occurred in the Yangtze River in the eastern China. Low salinity water less than 28 psu from the river was detected around the southwestern part of the Jeju Island, which is located in the southern part of the Korean Peninsula. We studied how to detect low salinity water from the Yangtze River, that cause a terrible damage to the Korean fisheries. We established a relationships between low salinity at surface, turbid water from the Yangtze River and digital ocean color remotely sensed data of SeaWiFS sensor in the northern East China Sea, in the summer of 1998, 1999, 2000 and 2001. The salinity charts of the northern East China Sea were created by regeneration of the satellite ocean color data using the empirical formula from the relationships between in situ low salinity, in situ measured turbid water with transparency and SeaWiFS ocean color data (normalized water leaving radiance of 490 nm/555 nm).

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권3호
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• pp.240-248
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• 1999

골재생유도술에 의한 골재생 과정에서의 생물학적 현상을 보다 구체적으로 이해하고자 인위적으로 골결손부를 형성하고, 비흡수성 비공유성 차폐막을 이용하여 골성회복 시 주위 연조직의 유입을 차단한 다음 골수강 및 골면으로부터 유래되는 세포들에 의한 골성회복 양상과 이때 이들 세포의 조골세포로의 분화정도를 판정하기 위하여 비교원성 골기질 단백질인 OSN, OPN 그리고 OSC mRNA의 발현 양상을 비교 검토하여 다음과 같은 결과를 얻었다. 실험 전기간에 걸쳐 골재생유도술을 시행한 군에서 보다 신속하고 양호한 골성회복을 보였다. 차폐막을 처리한 실험군에서는 인접골의 주변부로부터 신생골이 형성되어 조골세포의 분화가 조기에 골결손부에 국한되어 유도된 반면, 대조군에서는 주변연조직의 개입으로 인하여 실험군 보다는 약 1주정도 신생골의 형성이 지연되었으며, 따라서 골수강 내의 기질세포의 조골세포로의 분화 역시 지연되었다. 이상의 사실에서 골창상부에서 차폐막에 의해 형성된 차폐공간은 기질 세포들의 보다 신속한 조골세포로의 분화 증식과 이들에 의해 신생된 골주들의 빠른 골 개조를 조장하였음을 시사한다.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.71-76
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• 2006

Porous polymer monolithic columns were prepared by the direct free radical copolymerization of methacrylic acid and ethylene glycol dimethacrylate within the confines of a chromatographic column in the presence of toluene-dodecanol as a porogenic solvent. The separation characteristics of the monolithic columns were tested by a homologous series of xanthine derivatives, theophylline and caffeine. The effects of the polymerization mixture composition and polymerization condition, mobile phase composition, flow rate and temperature on the retention times and separation efficiencies were investigated. The results showed that the selection of correct porogenic solvents and appropriate polymerization conditions are crucial for the preparation of the monolithic stationary phases. The separation efficiency was only extremely weakly dependent on flow rate and temperatures. Hydrogen-bonding interaction played an important role in the retention and separation. Compared with conventional particle columns, the monolithic column exhibited good stability, ease of regeneration, high separation efficiency and fast analysis.

• ALGAE
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• 제36권4호
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• pp.327-332
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• 2021

Raw material of gelidioid red algae yielding high-quality agar has been in short supply due to overharvesting, but in situ farming of gelidioids has not been practical due to their slow growth. To produce vegetative seedstock of a cosmopolitan species, Pterocladiella capillacea, we investigated the number and length of regenerated branches arising from sectioned fragments during 3 weeks of laboratory culture at 10, 15, 20, and 25℃. All sectioned fragments formed axis-like branches mostly from the upper cut edge and stolon-like branches mostly from the lower cut edge, showing a high capacity of regeneration and intrinsic bipolarity. At 20℃, the number of regenerated branches increased to 2.74 ± 1.29 on the upper cut edge and 4.26 ± 2.66 on the lower cut edge. Our study reveals that the use of fragments bearing regenerated branches as seedstock can be a simple method to initiate fast propagation for mass cultivation in the sea or outdoor tank.

• 생체재료학회지
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• 제22권4호
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• pp.235-248
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• 2018

Background: Injectable hydrogels have been extensively researched for the use as scaffolds or as carriers of therapeutic agents such as drugs, cells, proteins, and bioactive molecules in the treatment of diseases and cancers and the repair and regeneration of tissues. It is because they have the injectability with minimal invasiveness and usability for irregularly shaped sites, in addition to typical advantages of conventional hydrogels such as biocompatibility, permeability to oxygen and nutrient, properties similar to the characteristics of the native extracellular matrix, and porous structure allowing therapeutic agents to be loaded. Main body: In this article, recent studies of injectable hydrogel systems applicable for therapeutic agent delivery, disease/cancer therapy, and tissue engineering have reviewed in terms of the various factors physically and chemically contributing to sol-gel transition via which gels have been formed. The various factors are as follows: several different non-covalent interactions resulting in physical crosslinking (the electrostatic interactions (e.g., the ionic and hydrogen bonds), hydrophobic interactions, ${\pi}$-interactions, and van der Waals forces), in-situ chemical reactions inducing chemical crosslinking (the Diels Alder click reactions, Michael reactions, Schiff base reactions, or enzyme-or photo-mediated reactions), and external stimuli (temperatures, pHs, lights, electric/magnetic fields, ultrasounds, or biomolecular species (e.g., enzyme)). Finally, their applications with accompanying therapeutic agents and notable properties used were reviewed as well. Conclusion: Injectable hydrogels, of which network morphology and properties could be tuned, have shown to control the load and release of therapeutic agents, consequently producing significant therapeutic efficacy. Accordingly, they are believed to be successful and promising biomaterials as scaffolds and carriers of therapeutic agents for disease and cancer therapy and tissue engineering.

• Corrosion Science and Technology
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• 제17권2호
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• pp.68-73
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• 2018

Substitution of hip and knee joints by CoCr alloys is in great demand due to their high wear resistance and good biocompatibility. Understanding of tribocorrosion in joint replacements requires study of variables such as coefficient of friction and the choice of a proper corrosive medium in wear-corrosion tests carried out in the lab. The objective of this study was to characterize tribocorrosion behaviour of CoCr alloy with low (LCCoCr) and high carbon (HCCoCr) contents in several corrosive media: NaCl, Phosphate Buffer Solution (PBS), and PBS with hyaluronic acid (PBS-HA). Tribocorrosion tests were carried out on a pin-on-disk tribometer with an integrated electrochemical cell. A normal load of 5N was applied on the alumina ball counterpart at a rotation rate of 120 rpm. Coefficient of friction (COF) was measured and tribocorrosion behaviour was characterized by in situ application of electrochemical techniques. HCCoCr alloy immersed in PBS-HA showed the best tribocorrosion behaviour with the lowest COF. In this case, in situ measurement of corrosion potential and the impedance data under wear corrosion process showed an active state while passive film was continuously destroyed without possibility of regeneration.

• 한국환경과학회지
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• 제11권6호
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• pp.519-528
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• 2002

This study was to evaluate the impact of river runoff and salt intrusion by tide on nutrient balance of estuary during a complete tidal cycle. 24 hours time series survey was carried out during a spring tide July 2001 on a tidal estuary in the Keum river. Three stations(A,B,C) were set along a transect line of about 10km, which linked the lower part of estuary dyke to the subtidal zone. Surface water was sampled simultaneously at each station every hours f3r the determination of nutrients. Water temperature, pH and dissolved oxygen were measured in situ. Riverine input of silicate and nitrate during ebb tide significantly increased the concentration of all stations. Conversely, during high tide, nutrient concentration were lowered by the mixing of fresh water with sea water Ammonium nitrogen concentration were higher at intertidal zone(Stn.B) due to sewage inflow to Kyeongpo stream and ammonium release under anaerobic conditions. Also, these results was discussed as a biological component that influences the processes of nutrient regeneration within the estuary. Best correlations were found at lower part of estuary dyke(Stn.A) for salinity against DIN(Y=0.121 Sal.+4.97, r2=0.956) and silicate(Y=0.040 Sal.+2.62, r2=0.785). But no significant correlation was found between salinity and ammonium. Unbalanced elemental ratio(N/P, Si/N and Si/P) depended significantly on the import of nutrients (silicate & nitrate nitrogen) from river and stream. The effect of the tidal cycle and river runoff is important that in determining the extend of the variations in nutrient concentrations at all station.

• KSBB Journal
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• 제20권3호
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• pp.142-148
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• 2005

이상을 통해 숙신산 분리정제를 위한 반응추출의 원리와 연구개발 및 적용 사례를 살펴보았다. 반응추출은 에너지가 적게 드는 고효율 생물분리공정이라는 장점을 확인 할 수 있었으며 향후 카르복실산 이외에 항생제를 비롯한 다양한 생물분자들의 분리정제에 적용할 수 있는 높은 응용 가능성을 갖고 있다. 그러나 특정 카르복실산의 회수를 목적으로 할 경우 추출제의 pH제한성은 극복되어야 할 문제점으로 작용할 수도 있다. 이와 병행하여 추출된 특정 카르복실산의 효과적인 회수 및 용매 재활용을 위한 재생공정의 개발도 요구된다. 기존에는 온도-스윙-재생법(temperature-swing-regeneration, TSR)이나 희석제-스윙-재생법 (diluent-swing-regeneration, DSR)을 주로 사용하였으나 회수율이 낮은 단점이 있다. 반응추출 공정의 경제성 향상을 위해서는 이를 개량하거나 대체할 수 있는 공정의 개발이 요구된다. 아울러 발효공정의 수율향상과 생성물의 동시분리를 위해 반응추출을 발효공정에 in-situ로 적용하기 위해서는 추출제 및 희석제의 생물적합성 향상을 위한 연구도 필요하다.

• 멤브레인
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• 제27권3호
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• pp.232-239
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• 2017

본 연구에서는 사용 후 폐기되는 정수기용 역삼투(Reverse Osmosis; RO)막 필터를 세정하여 새 필터의 수준으로 복원시키는 연구를 수행하였다. 화학적 세정액으로는 수산화나트륨, 중아황산나트륨, EDTA용액을 사용하였으며 마이크로버블 발생 장치와 함께 in-situ의 방법으로 세정하였다. EDTA를 0.1%의 농도로 제조한 뒤 마이크로버블과 함께 사용하여 30분 세정하였을 때 가장 좋은 결과를 나타내었다. 이때 폐 필터와 세정 후 폐필터의 성능을 비교해 보았을 때 투과도는 19.9%, 회수율은 49.5%증가하였으며 NaCl 100 mg/L 용액에 대한 염제거율은 2.3% 감소되었는데, 이는 새 필터와 동등한 수준으로 회복이 되었다. 또한 전자현미경 분석을 이용하여 막 표면의 오염물의 제거를 육안으로 확인하였다. 이로써 전량 매립 또는 소각 되어지는 정수기용 폐 RO막 필터의 세정을 통하여 재사용이 가능할 것으로 판단된다.