• Environmental Engineering Research
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• 제23권2호
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• pp.205-209
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• 2018

The spectral composition of light can affect the growth and biochemical composition of photosynthetic microalgae. This study examined the use of light filtering through a solution of soluble colored additives, a cost-effective method to alter the light spectrum, on the growth and lipid production of an oleaginous microalga, Nannochloropsis gaditana (N. gaditana). Cells were photoautotrophically cultivated under a white light emitting diode (LED) alone (control) or under a white LED that passed through a solution of red and yellow color additive (4:1 ratio) that blocked light below 600 nm. The specific growth rate was significantly greater under filtered light than white light ($0.2672d^{-1}$ vs. $0.1930d^{-1}$). Growth under filtered light also increased the fatty acid methyl ester (FAME) yield by 22.4% and FAME productivity by 80.0%, relative to the white light control. In addition, the content of saturated fatty acids was greater under filtered light, so the biodiesel products had better stability. These results show that passing white light through an inexpensive color filter can simultaneously enhance cellular growth and lipid productivity of N. gaditana. This approach of optimizing the light spectrum may be applicable to other species of microalgae.

• 상하수도학회지
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• 제27권2호
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• pp.261-272
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• 2013

Algae boom (Red tide) in south coastal area of Korea has been appeared several times during a decade. If algae boom appears in the desalination plant, media filter and UF filter are clogged quickly, and the plant should be shutdown. In general, Algae can be removed from water by flotation better than by sedimentation, because of the low density of algal cell. The purpose of this study conducts the CFD simulation of DAF flotation basin to apply the design of the dissolved air flotation with ball filter in the Test Bed for SWRO desalination plant. In this study, Eulerian-Eulerian multiphase model was applied to simulate the behavior of air bubbles and seawater. Density difference model and gravity were used. But de-sludge process and mass transfer between air bubbles and seawater were ignored. Main parameter is hydraulic loading rate which is varied from 20 m/hr to 27.5 m/hr. Geometry of flotation basin were changed to improve the DAF performance. According to the result of this study, the increase of hydraulic loading rate causes that the flow in the separation basin is widely affected and the concentration of air is increased. The flow pattern in the contact zone of flotation basin is greatly affected by the location of nozzle header. When the nozzle header was installed not the bottom of the contact zone but the above, the opportunity of contact between influent and recycle flow was increased.

• 상하수도학회지
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• 제33권1호
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• pp.79-86
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• 2019

In order to measure the filtration characteristics of a cotton ball shape filter, the experiments of suspended solids(SS) surrogate material selection and filtration performance have been carried out in this study. Between the two materials of powdered activated carbon(PAC) and powdered red-clay, PAC is more suitable surrogate material in terms of experimental criteria and particle size distribution in the non-point source pollutants removal system. As a result of the filtration experiments with the cotton ball shape filter, the initial headloss was about 8 cm, and the headloss slightly increased over filtration time. The Kozeny-Carman equation was used to analyze the changes of pressure and porosity during the filtration. The initial porosity was calculated as 0.945 and it decreased to 0.936 at the end of design filtration time. As the filtration continued, the SS concentration of the filtered water gradually increased and the SS removal rate gradually decreased. When the SS target removal efficiency is assumed to be 80%, the cumulative SS removal capacity is expected as $28.8kg/m^2$. This means the volume loading rate of the cotton ball shape filter can be $115m^3/m^2$ when the typical SS concentration of non-point source water pollution is assumed as 250 mg/L.

• 한국산업융합학회 논문집
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• 제27권2_2호
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• pp.475-485
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• 2024

In many regions of Korea, including the Four Major Rivers, the seriousness of the problem of algal blooms due to eutrophication of water quality is being raised.In this study, in order to solve these social problems, we manufactured a filter using natural mineral fusion (red illite, zeolite, germanium ceramic, selenium ceramic, carbon ceramic) and independently developed a tank system for green algae experiments to observe and determine the stages of change in water quality. In order to study ways to improve water quality through quantitative analysis, 1 ton of severely polluted green algae water from the Nak dong River region was stored in a water tank and exposed to ultraviolet rays in the same environment as the Nak dong River. Then, the same environment as the Nak dong River was created. The results were derived from a 5-week water quality test. The results of this experiment confirmed that green-colored cyano bacteria were significantly reduced just by the turbidity results. The results were obtained through a request to the Korea Testing & Research Institute located in Changwon-si, Gyeong sang nam-do. CI-(chlorine ion) and NH3-N(ammonia nitrogen) had the effect of saving every week. The device used in this study was made of natural minerals free of heavy metals that are harmless to the human body and nature through long-term consideration and exploration to kill and prevent various strains living in water. Green purification system using natural hydrogen generating mineral filter were effective a non-chemical and physical methods. The results of this study are one way to contribute to the serious problems caused by green algae in many countries, and will contribute to the water quality environment by preventing the waste of environmental resources, improving the health of the people, and increasing the ability to purify environmental water quality at home and abroad.

• 환경영향평가
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• 제32권3호
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• pp.166-175
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• 2023

본 연구는 용인시 내 하천 중 일부 지점 및 구간에서 발생하는 적수현상(물이 붉은 색을 띠는 현상)에 대한 원인 규명을 목적으로 하였다. 사전조사에서 적수현상이 타나나는 3개 지점을 조사지점으로 선정하였다. 조사결과 용인시 내 하천의 주요 적수 발생원인은 지역의 토색과 철 성분에 의한 것으로 판단된다. JPS, SBS, JJS 지점 모두 적갈색과 적황색이 주를 이루는 토색 특성을 보였다. Fe 농도 평균은 각각 1.31 mg/L, 10.85 mg/L, 13.75 mg/L로 나타났으며, 일반적인 하천수 중 Fe 농도가 0.5 mg/L 이하임을 고려했을 때 상당히 높은 농도임을 확인할 수 있었다. JPS, JJS 지점은 주로 정체된 곳에서 적수현상이 발생했으며, 이는 유기물 및 미생물 등이 반응하며 적수현상이 강화되는 것으로 판단된다. SBS의 경우 물이 적색을 띠고 있으나, 실제 물색을 관찰한 결과 관거에 침착된 철 성분으로 인해 진한 적색을 띠는 착시현상을 일으키는 것으로 판단된다. 또한, 대부분이 입자성 철 성분으로 유리섬유여지로 여과한 결과 95% 이상 감소하는 결과를 통해 입자성 철 성분 제거를 통해 일반적인 하천수 농도범위로 철 농도를 감소시킬 수 있을 것으로 사료된다. 본 연구결과, 물이 정체되지 않고 유수의 흐름이 유지될 수 있도록 하도 관리가 필요하며, 식생 피복을 통한 uptake 작용과 입자상 철 처리를 위한 응집침전 및 응집여과 방법을 통해 조사지점의 적수 발생을 완화할 수 있을 것으로 사료된다.

• 한국전자파학회논문지
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• 제13권4호
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• pp.379-385
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• 2002

본 논문에서는 MESFET을 이용하여 8 GHz 대역 국부발진기용 주파수 3체배기를 설계 및 제작하였다. A급에 동작점을 두어 3차 하모닉 성분을 발생시켰고, λ$_{g}$/2 개방형 스터브와 대역통과 여파기를 이용하여 기본주파수와 2차 하모닉성분을 억제하였다. 측정결과 0 ㏈m 입력신호에 대해 출력주파수인 8.31 GHz에서의 변환이 득은 2.67 ㏈, -41.17 ㏈c의 고조파 쳐압 특성을 얻었다. 또한 -3 ㏈ 이상의 변환이득을 갖는 대역폭은 510 MHz로 나타났다.다.

• 한국화재소방학회논문지
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• 제14권2호
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• pp.1-6
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• 2000

가연물 연소시 불꽃의 복사에너지 Spectrum분석을 통하여 태양광, 인공광과 Flame의 spectrum특성해석으로 불꽃감지기술을 정립하였다. IR파장대의 복사에너지를 감지하기 위해 초전형 감지소자개발로 PZT소자를 개발하였으며, Band Pass Filter와 회로안정화기술을 적용한 적외선 불꽃화재감지기를 개발하였다. 시작품의 성능은 신뢰성 있는 적외선 불꽃감지기로 검증이 되었으며, 연구결과는 휘발유, 석유화학제품의 연소시 발생되는 불꽃을 조기에 감지하는 복사에너지 감지기가 개발되었다.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.35-39
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• 1995

After making the light modulator using the BLN-PZT 9.0/65/35 specimen which has the slim-loop hysteresis characteristics and quadratic electro-optic characteristics, switching and spectral response characteristics were investigated. As the results of switching characteristics of the light modulator, it was found that the transmitted light intensity was modulated by both AC and pulse voltage. From the possibility of the selective transmission of the RGB(Red, Green, Blue) spectrum with electric field, the application for the light modulator, light shutter and color filter was expected.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 춘계학술대회 논문집
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• pp.88-91
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• 1993

In this study 9.5/65/35 PLZT was selected which has the excellent quadratic electro-optic property and slim-loop. It was fabricated by the methods of vacuum hot-pressing and sintering. The electrode of color filter was evaporated using the interdigital type masks. Hysteresis and transmission characteristics were measured. The coercive field and the nontransmited field were correlative. Aging effect was measured according to time at same temperature. Wavelengths of RGB were chosen 700[nm] for red, 545[nm] for green and 435[nm] for blue by the standard of the Commission Internationale del Eclaiage.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.117-120
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• 2000

Pulse oximetry is a well established non-invasive optical technique for monitoring the SpO$_2$ during anaesthesia, recovery and intensive care. Pulse oximeters determine the oxygen saturation level of blood by measuring the light absorption of arterial blood. The sensors consists of red and infrared light sources and photodetectors. In the measurement of the hemoglobin oxygen saturation, conventional method has required the technique of filtering of remove the noise, and of complex signal processing algorithm. So much time have required to signal processing. In this research, we separate AC signal and DC signal in the stage of signal detection. We filter the noise from each signal and convert A/D. We obtain the SpO$_2$ using the DSP algorithm.