• Membrane and Water Treatment
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• 제9권6호
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• pp.447-454
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• 2018

Although flotation techniques are often used for the removal of algal particles, the practicality of algae-harvesting technologies is limited owing to the complex and expensive facilities and equipment required for chemical coagulation. Here, we examined the feasibility of an approach to separating algal particles from water bodies without the need for chemical coagulants, depending on the condition of the algae, and to determine the optimal conditions. Using Anabaena sp., a cyanobacterium causes algal blooms in lakes, we stimulated auto-flocculation in algal particles without coagulants and conducted solid-liquid separation experiments of algal particles under various conditions. The six cultivation columns included in our analysis comprised four factors: Water temperature, light intensity, nutrients, and carbon source; auto-flocculation was induced under all treatments, with the exception of the treatment involving no limits to all factors, and algal particles were well-settled under all conditions for which auto-flocculation occurred. Meanwhile, flotation removal of auto-flocculated algal particles was attained only when nutrients were blocked after algae were grown in an optimal medium. However, no significant differences were detected between the functional groups of the extracellular polymeric substances (EPSs) of floated and settled algal particles in the FT-IR peak, which can cause attachment by collision with micro-bubbles.

• Composites Research
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• 제17권3호
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• pp.23-28
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• 2004

불균등 단면이나 임의의 경계조건을 가진 보나 탑 구조물의 고유진동수를 계산하는 방법은 김덕현에 의해 1960년 후반기에 개발 응용되고 1974년의 한 국제회의에서 발표되었다. 이 논문에는 이 방법을 탄성지지된 3경간연속 철근콘크리트 교량에 적용한 결과가 실려있다. 콘크리트 상판은 특별직교 이방성 판으로 취급되었다. 이 진동해석에 필요한 변위의 영향계수는 여러 방법으로 구할 수 있으나 이 논문에서는 유한차분법이 사용되었다. 기초의 탄성계수와, $D_{22}$, $D_{12}$, $D_{66}$ 강성의 고유진동수에 대한 영향이 철저하게 연구되었다.

• Journal of Microbiology and Biotechnology
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• 제25권6호
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• pp.803-813
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• 2015

The growth of Irpex lacteus F17 and manganese peroxidase (MnP) production in a selfdesigned tray bioreactor, operating in solid-state conditions at a laboratory scale, were studied. The bioreactor was divided into three layers by three perforated trays. Agroindustrial residues were used both as the carrier of bound mycelia and as a nutrient medium for the growth of I. lacteus F17. The maximum biomass production in the bioreactor was detected at 60 h of fermentation, which was consistent with the CO₂ releasing rate by the fungus. During the stationary phase of fungal growth, the maximum MnP activity was observed, reaching 950 U/l at 84 h. Scanning electron microscopy images clearly showed the growth situation of mycelia on the support matrix. Furthermore, the MnP produced by I. lacteus F17 in the bioreactor was isolated and purified, and the internal peptide sequences were also identified with mass spectrometry. The optimal activity of the enzyme was detected at pH 7 and 25℃, with a long half-life time of 9 days. In addition, the MnP exhibited significant stability within a broad pH range of 4-7 and at temperature up to 55℃. Besides this, the MnP showed the ability to decolorize the polymeric model dye Poly R-478 in vitro.

• 한국세라믹학회지
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• 제42권12호
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• pp.827-832
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• 2005

In this study, thin electrolyte layer was prepared by 8YSZ ($8mol\%$ Yttria-Stabilized Zirconia) slurry dip and sol coating onto the porous anode support in order to reduce ohmic resistance. 8YSZ polymeric sol was prepared from inorganic salt of nitrate and XRF results of xerogel powder exhibited similar results $(99.2\pm1wt\%)$ compared with standard sample (TZ-8YS, Tosoh Co.). The dense and thin YSZ film with $1{\mu}m$ thickness was synthesized by coating of 0.7M YSZ sol followed by heat-treatment at $600^{\circ}C$ for 1 h. Thin film electrolyte sintered at $1400^{\circ}C$ showed no gas leakage at the differential pressure condition of 3 atm.

• 센서학회지
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• 제31권5호
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• pp.312-317
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• 2022

Piezoelectric energy harvesting has attracted increasing attention over the last decade as a means for generating sustainable and long-lasting energy from wasted mechanical energy. To develop self-powered wearable devices, piezoelectric materials should be flexible, stretchable, and bio-eco-friendly. This study proposed the fabrication of stretchable piezoelectric composites via dispersing perovskite-structured BaTiO₃ nanoparticles inside an Ecoflex polymeric matrix. In particular, the stretchable piezoelectric sensor array was fabricated via a simple and cost-effective spin-coating process by exploiting the piezoelectric composite comprising of BaTiO₃ nanoparticles, Ecoflex matrix, and stretchable Ag coated textile electrodes. The fabricated sensor generated an output voltage of ~4.3 V under repeated compressing deformations. Moreover, the piezoelectric sensor array exhibited robust mechanical stability during mechanical pushing of ~5,000 cycles. Finite element method with multiphysics COMSOL simulation program was employed to support the experimental output performance of the fabricated device. Finally, the stretchable piezoelectric sensor array can be used as a self-powered touch sensor that can effectively detect and distinguish mechanical stimuli, such as pressing by a human finger. The fabricated sensor demonstrated potential to be used in a stretchable, lead-free, and scalable piezoelectric sensor array.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.440-441
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• 2011

온난화 등 기후변화의 영향으로 국내에 미치는 태풍의 수와 강도가 점점 증가하는 추세이며, 태풍 및 국지성 돌풍에 의한 송전선로의 과도한 점퍼선 횡진은 점퍼선과 철탑간의 공기절연거리를 감소시켜 지락사고가 발생하는 원인이다. 따라서 점퍼선의 횡진으로 인한 섬락고장을 예방하기 위하여 세계적으로 사용량이 증가하고 있는 폴리머 재질의 애자를 적용하여 전기 기계적 특성을 분석하고 국내 최대 순간풍속 62.7m/s의 풍압력 조건에도 견딜 수 있는 철탑부착 고정형 폴리머 점퍼지지 애자장치를 개발하게 되었다.

• Macromolecular Research
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• 제14권2호
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• pp.121-128
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• 2006

Microfluidic systems have attracted much research attention recently in the areas of genomics, proteomics, pharmaceutics, clinical diagnostics, and analytical biochemistry, as they provide miniaturized platforms for conventional analysis techniques. The microfluidic systems allow faster and cheaper analysis using much smaller amounts of sample and reagent than conventional methods. Polymers have recently found useful applications in microfluidic systems due to the wide range of available polymeric materials and the relative ease of chemical modification. This paper discusses the fundamentals of microfluidic systems and the roles, essential properties and various forms of polymers used as solid supports in microfluidic systems, based on the recent advances in the use of polymers for microfluidic chips.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.220-223
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• 2000

A method of calculating the natural frequency corresponding to the modes of vibration of beams and tower structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the three span continuous reinforced concrete bridge with elastic intermediate supports is presented. Such bridge represents either concrete or sandwich type three span bridge on polymeric supports for passive control or on actuators for active control The concrete slab is considered as a special orthotropic plate. The influence of the modulus of the foundation and $D_{22}$, $D_{12}$, $D_{66}$ stiffnesses on the natural frequency is thoroughly studied.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.97-104
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• 2004

원자력시설의 해체를 위한 표면오염도를 측정함에 있어 기존의 일반적인 단일층 함침 복합체의 단점을 개선한 치밀한 구조의 지지층 위에 활성층의 2차막을 도포 하여 제조된 이중 구조의 고분자 복합체를 제조하고 이들의 특성을 분석하였다. 세륨활성화된 이트리움실리케이트(Cerium-activated ytttrium silicate, CAYS)를 함침시킨 폴리설폰 이중구조 필름은 1차 지지층으로서 폴리설폰 (polysulfone, PSF)과 메틸렌클로라이드 (methylene chloride, MC)로 이루어진 2액용액을 유리판 위에 제막하고 증발을 통해 MC를 제거하여 고분자의 유리화(vitrification)를 통해 치밀한 구조로 고형화하도록 하였다. 고형화한 1차층 위에 CAYS 와 용매로 이루어진 2차 제막용액을 덧붙여 도포하고 물에 침지시키거나 대기방치를 통해 고형화시켰다. 이렇게 이루어진 2중 구조의 무기섬광체 함침 복합체 필름은 2차 제막층에 손가락 형태의 큰 기공이 생성되었으며, 1차층과 2차층이 완전히 결합되어 있어 우수한 기계적 물성을 나타냈다. 한편, 섬광체인 CAYS를 첨가하였을 때 필름에 생성되는 은 기공의 형성이 증대되는 특성을 보였으며, 용매의 증발에 의해 고형화 된 필름은 치밀한 구조의 형상을 보였다. 제조된 필름들은 방사성핵종의 탐지에 있어 신뢰할만한 탐지 결과를 보였다.

• 멤브레인
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• 제23권3호
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• pp.251-256
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• 2013

본 연구에서는 아세틸화된 메틸 셀룰로스를 복합박막 정삼투막의 지지층으로 사용하였다. 계면중합법을 이용하여 선택성이 우수한 폴리아미드 활성층을 다양한 지지층 위에 코팅하였다. 아세틸화된 메틸 셀룰로스 지지층 위에 코팅된 복합박막 정삼투막의 구조와 성능을 다른 지지층 위에 코팅된 복합박막 정삼투막과 비교하였다. 실험적 결과는 아세틸화된 메틸 셀룰로스 지지층 위에 코팅된 복합박막 정삼투막의 성능이 다른 정삼투막들에 비해서 우수하였으며 이것은 구조적인 특성과 염의 낮은 역확산속도 때문인 것으로 사료된다.