• 한국환경농학회지
• /
• 제32권2호
• /
• pp.108-116
• /
• 2013

BACKGROUND: Certain crop-based waste materials have been recognized as cost-effective and highly efficient adsorbents for removal and recovery of different kind of heavy metals from aqueous solutions. The ability is strongly attributed to the carboxyl functional group of some pectin substances such as galacturonic acid often found in fruit peels. The present manuscript was aimed at assessing the potential applicability of banana peel for metal removal from contaminated waters. METHODS AND RESULTS: As revealed by laboratory investigations, banana peel contains pectin (10-21%), lignin (6-12%), cellulose (7.6-9.6%), and hemicelluloses (6.4-9.4%). The pectin extraction is reported to have glucose, galactose, arabinose, rhamnose, xylose, and galactouroninc acid. Several studies conducted under different conditions proved that banana peel is capable of adsorbing 5.71, 2.55, 28.00, 6.88, 7.97, and 5.80 mg/g of $Cd^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Ni^{2+}$, $Pb^{2+}$, and $Zn^{2+}$, respectively, from aqueous solutions. Adsorption capacity is, however, dependent upon several factors including solution pH, dose of adsorbent and metal concentration, contact time and shaking speed. CONCLUSION(S): Since the annual world production of banana exceeds 100 million tons, about 40 million tons of banana peel (40% of total weight of the fresh fruit) remains vastly unused. Exploring a sound technology with banana peel would therefore, not only address the much needed sustainable tool for cleaning contaminated waters, but of course bring an additional value to the banana industry worldwide.

• Earthquakes and Structures
• /
• 제2권3호
• /
• pp.233-256
• /
• 2011

This paper investigates the applicability of newly developed Cu-Al-Mn shape memory alloy (SMA) bars to retrofitting of historical masonry constructions by performing quasi-static tests of half-scale brick walls subjected to cyclic out-of-plane flexure. Problems associated with conventional steel reinforcing bars lie in pinching, or degradation of stiffness and strength under cyclic loading, and in their inability to restrain residual deformations in structures during and after intense earthquakes. This paper attempts to resolve the problems by applying newly developed Cu-Al-Mn SMA bars, characterized by large recovery strain, low material cost, and high machinability, as partial replacements for steel bars. Three types of brick wall specimens, unreinforced, steel reinforced, and SMA reinforced specimens are prepared. The specimens are subjected to quasi-static cyclic loading up to rotation angle enough to cause yielding of reinforcing bars. Corresponding nonlinear finite element models are developed to simulate the experimental observations. It was found from the experimental and numerical results that both the steel reinforced and SMA reinforced specimens showed substantial increment in strength and ductility as compared to the unreinforced specimen. The steel reinforced specimen showed pinching and significant residual elongation in reinforcing bars while the SMA reinforced specimen did not. Both the experimental and numerical observations demonstrate the superiority of Cu-Al-Mn SMA bars to conventional steel reinforcing bars in retrofitting historical masonry constructions.

• Membrane and Water Treatment
• /
• 제11권2호
• /
• pp.97-109
• /
• 2020

Membrane fouling is the main drawback of membrane technology. Frequent membrane cleaning and membrane replacement are, therefore, required to reduce membrane fouling that causes permeate flux reduction, lower rejection, or higher operating pressure. Studies have proved that the alteration of membrane properties is the key controlling factor in lessening membrane fouling. Among stimuli-responsive membranes, thermo-responsive membrane is the most popular, with a drastic phase transition and swelling-shrinking behavior caused by the temperature change. In this study, the thermo-responsive ability of two commercial membranes, PolyCera® Titan membrane and PolyCera® Hydro membrane, at different temperatures was studied on the antifouling function of the membrane in palm oil mill effluent (POME) treatment. The evaluation of the membrane's thermo-responsive ability was done through three cycles of adsorption (fouling) and desorption (defouling) processes in a membrane filtration process. The experimental result depicted that PolyCera® Hydro membrane had a higher membrane permeability of 67.869 L/㎡.h.bar than PolyCera® Titan membrane at 46.011 L/㎡.h.bar. However, the high membrane permeability of PolyCera® Hydro membrane was compensated with low removal efficiency. PolyCera® Titan membrane with a smaller mean pore size had better rejection performance than PolyCera® Hydro membrane for all tested parameters. On the other hand, PolyCera® Titan membrane had a better hydrodynamic cleaning efficiency than PolyCera® Hydro membrane regardless of the hydrodynamic cleaning temperature. The best hydrodynamic cleaning performed by PolyCera® Titan membrane was at 35℃ with the flux recovery ratio (FRR) of 99.17 ± 1.43%. The excellent thermo-responsive properties of the PolyCera® Titan membrane could eventually reduce the frequency of membrane replacement and lessen the use of chemicals for membrane cleaning. This outstanding exploration helps to provide a solution to the chemical industry and membrane technology bottleneck, which is the membrane fouling, thus reducing the operating cost incurred by the membrane fouling.

• Journal of Microbiology and Biotechnology
• /
• 제23권5호
• /
• pp.587-601
• /
• 2013

During the last few decades, it has become evident that the compatibility of the yeast biochemical environment with the ability to process and translate the RNA transcript, along with its capacity to modify a translated protein, are relevant requirements for selecting this host cell for protein expression in several pharmaceutical and clinical applications. In particular, Pichia pastoris is used as an industrial host for recombinant protein and metabolite production, showing a powerful capacity to meet required biomolecular target production levels in high-throughput assays for functional genomics and drug screening. In addition, there is a great advantage to using P. pastoris for protein secretion, even at high molecular weights, since the recovery and purification steps are simplified owing to relatively low levels of endogenous proteins in the extracellular medium. Clearly, no single microexpression system can provide all of the desired properties for human protein production. Moreover, chemical and physical bioprocess parameters, including culture medium formulation, temperature, pH, agitation, aeration rates, induction, and feeding strategies, can highly influence product yield and quality. In order to benefit from the currently available wide range of biosynthesis strategies using P. pastoris, this mini review focuses on the developments and technological fermentation achievements, providing both a comparative and an overall integration analysis. The main aim is to highlight the relevance and versatility of the P. pastoris biosystem to the design of more cost-effective microfactories to meet the increasing demands for recombinant membrane proteins and clinical antibodies for several therapeutic applications.

• 대한환경공학회지
• /
• 제38권5호
• /
• pp.219-227
• /
• 2016

음식물쓰레기의 최대 배출원인 주택에서 생성되는 음식물쓰레기의 성상은 양호하여 재활용 가치가 크지만, 기존의 음식물쓰레기 관리방식으로는 한계가 있어 개선안이 요구되고 있다. 본 연구는 수도권과 비수도권 소재 공동주택단지의 음식물쓰레기 관리 실태를 조사하고, 발효 소멸기술을 이용한 음식물쓰레기 무배출 시스템 보급에 대한 지자체 태도를 파악하고자 한다. 전국 지자체 공무원을 대상으로 실시한 설문조사를 통해 수집한 자료는 통계분석을 하였고, 그 주요 결과를 요약하면 다음과 같다. 공동주택단지에서 배출되는 음식물쓰레기는 차량수거를 통해 퇴비나 사료로 재활용되고 있었다. 상당수의 지자체들은 음식물쓰레기 무배출 시스템에 관심이 있으나, 지자체의 예산 부족은 그 보급에 걸림돌이 되었다. 또한, 음식물쓰레기 무배출 시스템을 실용화하기 위해서는 비용절감효과, 에너지로의 자원화, 설치 후 유지운영 관리의 용이성 등이 뒷받침되어야 할 것으로 나타났다.

• Journal of Korean Neurosurgical Society
• /
• 제38권4호
• /
• pp.281-286
• /
• 2005

Objective : The authors report our experience of urokinase thrombolysis in treating patients harboring nonaneurysmal spontanesous intraventricular hemorrhage[IVH] and evaluated complications, safety and feasibility of this procedure retrospectively. Methods : Fifty-three patients with nonaneurysmal IVH>15mL without underlying structural etiology or coagulopathy were recruited. The patients with Glasgow Coma Scale[GCS]<5 were excluded. A catheter was directed into the IVH. Hematoma aspiration was followed by instillation of urokinase at the ear level of drainage bag under intracranial pressure monitoring system. This was repeated every 6hours until half of its initial volume. For analysis of prognostic factors, we classified the patients into two groups by Glasgow outcome scale[GOS]; good [$GOS\;{\ge}3$] and bad [GOS<3] prognosis group, and performed comparative analysis between two groups. Results : Mean age was 60.2years. The baseline hematoma size ranged 16 to 72mL. IVH volume reduction was done by an average of 74.2%. As complications, there were 3cases of rebleeding and 2cases of ventriculitis. No intracranial adverse effects were observed during thrombolytic theraphy. At 6months after the procedure, 29patients had achieved a good recovery, 15remained vegetative. 9patients died in hospital. The main good prognostic factors were young age, small IVH volume, and high GCS. Conclusion : The results of this study suggest that this relatively easy and safe method of treatment will improve the prognosis. However, further clinical studies also must assess optimal thrombolytic dosage, frequency, and timing of urokinase instillation for safety and effectiveness and must include controlled comparisons of mortality, disability outcome, quality of life, time until convalescence, and cost of care in treated and untreated patients.

• 한국방재학회 논문집
• /
• 제4권1호
• /
• pp.65-75
• /
• 2004

자연재해에 기인한 철도노반의 유실 및 파괴는 유실된 선로복구를 위한 공사가 장기간 소요됨으로써 정상적인 철도운행에 지장을 초래하여 사회적, 경제적으로 많은 비용 및 시간의 손실을 유발시키고 있다. 본 연구에서는 자연재해로 인해 유실된 철도노반에 대한 신속하고 안전한 복구대책으로서 토목섬유로 제조된 Soilbag의 적용성을 평가하고자 정적하중 및 모사반복 열차하중 재하 실대형시험을 수행하였다. 실대형시험을 통해 심도별 연직토압과 침하량을 계측한 결과, 하중분산효과에 기인한 토압 및 침하 저감 효과를 확인할 수 있었으며 시공성과 장기적 안정성을 고려할 때 Soilbag 공법의 현장적용성은 가능할 것으로 판단된다.

• 한국정보통신학회논문지
• /
• 제20권12호
• /
• pp.2305-2309
• /
• 2016

클라우드 컴퓨팅 서비스는 그 효율성과 안정성이 기반이 되어야 한다. 한 예로 미국은 클라우드 컴퓨팅 서비스의 안전성을 위하여 FedRAMP 인증을 제시하고 클라우드 컴퓨팅 서비스 산업의 성장은 많은 기업들에게 비용 절감과 업무의 효율성을 제공하고 있으나, 그에 따른 위험성 역시 높아지고 있다. 해킹 등으로 클라우드 서비스 특징상 데이터에 대한 통제성을 잃게 되고, 많은 데이터가 한 곳에 몰리는 현상은 장애가 발생하면 모든 기기의 데이터가 일제히 삭제되는 되는 문제점이 있다. 본 논문에서는 클라우드 보안 인증 제도의 비즈니스 연속성의 문제점을 알리고 이를 위한 솔루션인 서비스 가입자 내부에 백업과 외부 백업의 장단점을 비교한다. 결론적으로 외부 백업이 구조상으로 우위에 있음을 보인다.

• 전자공학회논문지SC
• /
• 제37권6호
• /
• pp.25-34
• /
• 2000

본 논문에서 범용의 CMOS 트랜지스터 공정을 사용하여 250-Mbps 10-채널 CMOS 광 수신기 어레이칩을 설계하였다. 이러한 광 수신기 어레이는 병렬 광 신호 전송 시스템의 성능을 결정하는 가장 중요한 블록이며 이를 CMOS 트랜지스터로 설계함으로써 낮은 단가의 시스템의 구현을 가능하게 하였다. 각 데이터 채널은 집적화 된 광 검출 소자 및 여러 단의 증폭기로 구성된 아날로그 프런트-엔드, D-FF (D-flip flop)과 칩 외부 구동기로 구성된 디지털 블록으로 구성되어 있다. 전체 칩은 광 수신기 어레이와 데이터의 동기식 복원을 위해 PLL (Phase-Lock Loop) 회로로 구성 되어있다. 설계한 광 수신기 어레이 칩은 0.65-㎛ 2-poly, 2-metal CMOS 공정을 사용하여 제작하였으며, 각 채널은 ±2.5V의 전원 전압에 대하여 330㎽의 소비 전력을 보였다.

• 전력전자학회논문지
• /
• 제20권3호
• /
• pp.214-222
• /
• 2015

The superiority of gallium nitride FET (GaN FET) over silicon MOSFET is examined in this paper. One of the outstanding features of GaN FET is low reverse-recovery charge, which enables continuous conduction mode operation of totem-pole bridgeless boost power factor correction (PFC) circuit. Among many bridgeless topologies, totem-pole bridgeless shows high efficiency and low conducted electromagnetic interference performance, with low cost and simple control scheme. The operation principle, control scheme, and circuit implementation of the proposed topology are provided. The converter is driven in two-module interleaved topology to operate at a power level of 5.5 kW, whereas phase-shedding control is adopted for light load efficiency improvement. Negative bias circuit is used in gate drivers to avoid the shoot-through induced by high speed switching. The superiority of GaN FET is verified by constructing a 5.5 kW prototype of two-module interleaved totem-pole bridgeless boost PFC converter. The experiment results show the highest efficiency of 98.7% at 1.6 kW load and an efficiency of 97.7% at the rated load.