• 설비공학논문집
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• 제8권4호
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• pp.550-560
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• 1996

Recently, fluidized bed heat exchangers with circulating liquid are widely used in a number of places-chemical, process, food concentration, waste water treatment facilities, etc. In a circulating heat exchanger, solid particles circulate with the liquid, thereby increase the heat transfer and reduce the fouling potential of the heat exchanger. In this study, glass beads were circulated through a vertical tube. The pressure loss and the heat transfer coefficient were measured. At low flow velocities, glass beads enhanced the heat transfer considerably. The enhancement increased as the volume fraction of the glass beads increased. The pressure loss showed a similar trend. From the observed particle behavior near tube wall, a possible explanation of the trend is provided.

• 도시과학
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• 제7권1호
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• pp.23-27
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• 2018

This research was carried out to investigate the corrosion prevention effect in the water distribution system by galvanized zinc-brass pipe which is using potential between brass and zinc. As a result of this study, pH and conductivity of influent were constant in spite of its installation, and it was difficult to estimate the effect of the installation with temporary increased and reduced concentration of Zn and Fe ions, respectively. However, since the corrosion rate of the steel coupon with galvanized zinc-brass pipe was relatively low, it has an effect of inhibiting corrosion.

• 한국입자에어로졸학회지
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• 제10권3호
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• pp.99-108
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• 2014

Liquid filtration by membrane filters is essential for the preparation of ultrapure water in semiconductor manufacturing processes. The separation of submicrometer particles suspended in ultrapure water with a laminated fibrous membrane filter was studied numerically and experimentally in the present work. We found that an electrical double layer around a single fiber expanded to a large extent at a low ion concentration, as in ultrapure water, and deformed toward the upstream of the fiber with increasing filtration velocity. Since an increase in the electrical double-layer thickness leads to a decrease in the electrical potential gradient, particles with the same polarity as the fiber approach the fiber more easily and are captured at a high filtration velocity. Experimental results also confirmed that the collection efficiency of polystyrene latex(PSL) particles through a PTFE filter became higher as the filtration velocity increased.

• Rapid Communication in Photoscience
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• 제4권2호
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• pp.41-44
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• 2015

Biomolecular photo-damaging activity of a water-soluble cationic porphyrin was examined using human serum albumin (HSA), a water-soluble protein as a target biomolecule model by a fluorometry. Dichlorophosphorus(V) tetraphenylporphyrin ($Cl_2P(V)TPP$), was synthesized and used as a photosensitizer. This porphyrin could bind to HSA and cause the photosensitized oxidation of HSA through the singlet oxygen generation and the oxidative photo-induced electron transfer (ET). Near infrared emission spectroscopy demonstrated the photosensitized singlet oxygen generation by this porphyrin. Decrement of the fluorescence lifetime of $Cl_2P(V)TPP$ by HSA supported the ET mechanism. Furthermore, the estimated Gibb's energy indicated that the ET mechanism is possible in the terms of energy. Because oxygen concentration in cancer cell is relatively low, ET mechanism is considered to be advantageous for photosensitizer of photodynamic therapy.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1996년도 춘계학술발표회 초록집
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• pp.121-131
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• 1996

Recently, circulating liquid fluidized bed heat exchangers are widely used in a number of places - chemical, process, food concentration, waste water treatment facilities, etc. In a circulating heat exchanger, solid particles circulate with the liquid, thereby increase the heat transfer and reduce the fouling potential of the heat exchanger. In this study, glass beads were circulated through a vertical tube. The pressure loss and the heat transfer coefficient were measured. At low flow velocities, glass beads enhanced the heat transfer considerably. The enhancement increased as the volume fraction of the glass beads increased. It also increased as the particle diameter increased. The pressure loss showed a similar trend. From the observed particle behavior near tube wall, a possible explanation of the trend is provided.

• 설비공학논문집
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• 제23권6호
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• pp.413-420
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• 2011

Thermodynamic cycles using binary mixtures as working fluids offer a high potential for utilization of low-temperature heat sources. This paper presents a thermodynamic performance analysis of Goswami cycle which was recently suggested to produce power and cooling simultaneously and combines the Rankine cycle and absorption refrigeration cycle by using ammoniawater mixture as working fluid. Effects of the system parameters such as concentration of ammonia and turbine inlet pressure on the system are parametrically investigated. Results show that refrigeration capacity or thermal efficiency has an optimum value with respect to ammonia concentration as well as to turbine inlet pressure.

• Journal of Life Science
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• 제9권2호
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• pp.57-61
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• 1999

This study was designed to develope the antioxidative activity on oxidation of human low density lipoprotein(LDL) from marine microbials. Bacillus KS-96 producign antioxidant have been isolated and identified from seawater, Bacillus sp. KS-96. The optimal medium pH was 7.0 and incubation temperature was 30$^{\circ}C$. The antiosidant of potential substance produced extracellularly in the culture broth by Bacillus sp. KS-96 was obtained by elution of silica gel culumn chromatography with hexane, ethylacetate and water. The ethylacetate faction are shown at highest level of antioxidant activity using thiocyanate method among them. By IR, NMR, and GC/MS, antioxidant purified from ehtylacetate fraction was identified and named as 2,6-dimethoxyphenol. 2,6-dimethoxyphenol inhibited the metal mediated oxidation of human LDL at concentration of 50∼100 ${\mu}$g/mL in the presence of 5uM CuSO4 with macrophage or J774 cells.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3201-3204
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• 2000

In general, analog tester or strip chart recorder have been used to measure the corrosion potential of structures such as gas pipelines, oil pipelines, hot water pipelines, power cables etc. Recently, automatic digital data logger substitutes for these manual equipment because using these manual equipments are tedious and time consuming. However, digital data logger also has a shortcoming, that is, short measuring time because of the short lifetime of batteries. Therefore, we developed a long lifetime and low power loss battery taking advantage of galvanic series. In this paper, the results of development for power generator using two metals and DC/DC converter in order to obtain enough voltage for the operation of digital data logger. DC/DC converter operates with 0.5[V]. Its output voltage is 3.5[V] and output current is from 60[mAh] to 1,200[mAh].

• 세라미스트
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• 제23권2호
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• pp.178-183
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• 2020

Solar energy conversion is now actively researching because of pollution. Especially silicon photocatalyst has big potential, because of wide absorption range. But low quantum yield of silicon photocatalyst can't be used for commercialization. This paper summarize mechanism of silicon photocatalyst. In addition, properties and current states of photo catalyst using nanomaterials of silicon are also introduced.

• 대한환경공학회지
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• 제27권7호
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• pp.753-761
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• 2005

전처리 공정에 따른 투과 flux 변화를 살펴보면 $MIEX^{(R)}$+UF 공정의 경우 응집+UF 공정에 비하여 높은 유기물 제거율을 나타내었으나 투과 flux 감소는 크게 나타났다. 따라서, 막 오염을 자세하게 규명하기 위하여 sequential filtration 실험결과 막 오염물질은 고분자 유기물질로 나타났으며, DOC 0.5 mg/L 이하의 유기물질이 막 오염 유발물질로 작용하고 있었다. 10 kDa 이하의 저분자 유기물질들은 $MIEX^{(R)}$ 처리에 의해 제거가 용이하여 막 표면에서 유기물 부하를 감소시켜 이로 인해 응집+UF공정에 비하여 투과 flux 감소율이 낮게 나타났다. $MIEX^{(R)}$+UF공정은 입자상 물질의 존재 유무에 관계없이 flux 감소율은 거의 유사한 경향을 보였으나 응집+UF공정은 용존성 유기물질만이 존재하는 시수에 비하여 입자상 물질이 존재하는 경우에 투과 flux 감소가 더 낮게 나타났다.