• 대한환경공학회지
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• 제39권5호
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• pp.246-254
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• 2017

호소, 하천 등에 다량의 영양염류의 유입과 수문학적, 지리학적, 생물학적 요소 등으로 인해 남조류가 대량 발생하게 되며 대표적 독성물질인 마이크로시스틴-LR(MC-LR)이 증가한다. MC-LR이 포함된 지표수를 적절하게 처리하기 위하여 정수처리공정에서는 고도산화공정을 적용하고 있다. 다양한 고도산화공정 중 특히 UV, $UV/H_2O_2$, $UV/O_3$, $UV/TiO_2$ 등에 대한 연구는 꾸준히 되어왔다. 기존의 UV램프의 짧은 교체주기, 수은 폐기물 발생, 큰 열 손실 등의 단점을 보완한 UV-LED를 MC-LR제거에 적용하였다. MC-LR 초기농도 $100{\mu}g/L$을 280 nm의 파장인 LED-L ($0.024mW/cm^2$)와 LED-H ($2.18mW/cm^2$)를 이용하여 산화시켰을 때 각각 최대 약 30%, 95.9%의 MC-LR 제거율을 나타냈다. LED-H를 조사 시 자연유기물 변화는 휴믹물질, UVD, SUVA가 감소하는 경향을 보였고 방향족 유기물이 지방족 유기물로 분해되어 저분자 물질이 되었다. $LED-H/H_2O_2$($H_2O_2$: 1, 2, 5, 10 mg/L)산화반응에 의한 MC-LR제거율은 LED-H 단독에 의한 MC-LR 제거율과 유사하였다. 남조류가 발생한 낙동강 원수를 대상으로 LED-L산화를 적용하여 수질분석을 통하여 특성변화를 확인하였다. DOC 및 TOC의 변화는 거의 없었으나 SUVA와 $UV_{254}$의 감소로 인하여 유기물의 분해되었으며 조류유래물질인 용존 및 총 MC-LR, geosmin, 2-MIB농도가 시간이 지남에 따라 서서히 감소하였다.

• Current Photovoltaic Research
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• 제9권1호
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• pp.17-21
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• 2021

In this study, the effect of water level and temperature on the power generation was investigated in a water tank with an aquavoltaic PV module to perform feasibility research for the development of salt farm aquavoltaic system. The silicon solar cell attached to the bottom of each water tank is a 1-cell mini module, and the underwater effects of the crystal phase (19.0~19.9% of single- & 17.9~19.9% of poly-crystalline) of the PV module were investigated, and power generation characteristics for water level (0~10 cm) and temperature (10~40℃) were analyzed. The deterioration coefficients according to the water level and temperature of each single- and poly-crystalline module were investigated at very similar levels such as, -2.01 %/cm and -2.02 %/cm, -0.50 %/℃ and -0.48 %/℃, respectively. Therefore, in salt farm aquavoltaic system, water levels need to maintain as low as possible, and heat-induced degradation is similar to those shown in general land, and no factors have been found to be affected by the underwater environment depending on the determination.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권3호
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• pp.63-71
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• 2001

This paper presents a model-based method for detecting and diagnosing some faults in the cooling tower of healing, ventilating, and air-conditioning systems. A simple model for the cooling tower is employed. Faults in cooling tower operation are detected through the deviations in the values of system characteristic parameters such as the heat transfer coefficient-area product, the tower approach, the tower effectiveness, and fan power. Three distinct faults are considered: cooling tower inlet water temperature sensor fault, cooling tower pump fault, and cooling tower fan fault. As a result, most values of the system characteristics parameter variations due to a fault are much higher or lower than the values without faults. This allows the faults in a cooling tower to be detected easily using above methods. The diagnostic rules for the faults were also developed through investigating the changes in the different parameter due to each faults.

• 한국재료학회지
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• 제25권1호
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• pp.21-26
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• 2015

CMP(Chemical Mechanical Polishing) Processes have been used to improve the planarization of the wafers in the semiconductor manufacturing industry. Polishing performance of CMP Process is determined by the chemical reaction of the liquid sol containing abrasive, pressure of the head portion and rotational speed of the polishing pad. However, frictional heat generated during the CMP process causes agglomeration of the particles and the liquidity degradation, resulting in a non-uniform of surface roughness and surface scratch. To overcome this chronic problem, herein, we introduced NaCl salt as an additive into silica sol for elimination the generation of frictional heat. The added NaCl reduced the zata potential of silica sol and increased the contact surface of silica particles onto the sapphire wafer, resulting in increase of the removal rate up to 17 %. Additionally, it seems that the silica particles adsorbed on the polishing pad decreased the contact area between the sapphire water and polishing pad, which suppressed the generation of frictional heat.

• 약학회지
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• 제3권1호
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• pp.26-34
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• 1957

The solar evaporation method is one of the most important and popular salt manufecturing method in Korea. The rate of evaporation of sea water depends on a complex climate factors. Of these factors, the most important is solar radiation and in particular the extent to which it is absorbed in the brine. By the addition of suitable dyestuff, a further increase in absorption is obtained and can result in all the radiation entering the brine being made available as heat. "Solivap Green", one of several dyestuffs which have been suggested for accelerating solar evaporation, was tested in this experiment. The results of the experiment. 1. Increase the evaporation rate of brine up to 20-25%. 2. Elevate the temperature of brine 2-$4^{\circ}C$. higher than that of brine adding no dyestuff. 3. Optimum dyestuff concentration is 25-30 mg/L and allowable maximum concentration can not exceeded 1000 mg/$m^2$ (50 mg/L). 4. Addition of dyestuff does not cause the degradation of salt produced. 5. A conversion table which indicates the concentrations for various depths of brine was prepared for engineering purpose. 6. Absorption spectrum of the dyestuff was studies, but toxicological and structural studies for the dyestuff have not been done in this experiment.

• 한국수자원학회논문집
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• 제47권1호
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• pp.49-62
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• 2014

최근에 불투수층의 증가로 인하여 표면의 저류량이 감소하고 첨두유출과 전체 유출량은 증가한다. 첨두유출과 첨두유출 도달시간이 빨라지게 되면 홍수 발생률이 증가하여 도시유역의 피해를 증가시키며, 토양으로 침투되는 우수량이 감소하여 지하수위가 하강하게 되고 도시하천이 마르는 건천화가 진행되어 유역의 물 순환이 악화된다. 또한 하천 수질 오염의 원인은 점오염원과 비점오염원 등이 있는데, 비점오염원에 의한 오염이 점점 커져가는 양상이다. 이러한 이유는 도시유역이 지속적인 개발로 인해 불투수율이 증가하게 되어 초기강우에 오염물질이 하천으로 유입되고 있기 때문이다. 따라서 본 연구에서는 도시유역의 물순환 회복을 위한 투수성 포장 효과를 분석하며, 투수성 포장의 비점저감 효과 및 첨두유량 감소 효과를 분석하고자 한다. 도시유역 유출 모델인 SWMM을 이용하여 단기 유출 모의를 통하여 투수성 포장의 효과 분석하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.241-244
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• 2009

This study is focused on the improving effectiveness of a photovoltaic system. The characteristic of crystalline silicon solar cells, that 0.5% reduction in generating power is occurred by increasing temperature $1^{\circ}C$ of module. Typically, average solar generating power is higher spring and fall than summer. Degradation phenomena shall shorten the life of the module when the temperature of modules is $70^{\circ}C$. Decreasing temperature 40degree of the module and increasing the solar power 20% was presented using the water impinging jet method on the surface of photovoltaic cells. It is shown that Impinging jet have an effected on heat and deliver effective substance from the area in which the injection is effective.

• Journal of Animal Science and Technology
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• 제44권1호
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• pp.105-112
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• 2002

동물성 부산물 사료(우모분, 우지박, 내장분)단백질의 반추위내 분해특성과 하부장기내 이용성에 대한 열처리 효과를 구명하기 위하여 반추위와 십이지장에 누관이 장착된 Holstein 건유우 3두를 공시하였다. 시험사료에 대한 열처리는 149$^{\circ}C$가 유지되는 oven에서 4시간동안 처리한 후, 1 mm체를 통과시켰다. 시험사료의 반추위내 분해특성은 발효시간별 분해율에서 비선형회귀식을 유도하여 구하였고, 사료단백질의 하부장기내 이용성은 mobile nylon bag기법으로 추정되었다. 농후사료와 orchard grass를 60:40의 비율로 급여하였으며, 물과 mineral block은 자유섭취토록 하였다. 조단백질의 반추위내 유효분해도(k=0.05) 및 하부장기내 소실율에 있어서 우모분은 각각 30.2% 및 56.2%, 우지박은 75.0% 및 18.6% 그리고 내장분은 56.4% 및 37.9%였다. 시험사료에 대한 열처리효과에 있어서 조단백질의 반추위내 유효분해도는 우모분과 내장분은 증가하였으나 우지박은 감소되었고(P$<$0.05), 하부장기내 조단백질 소실율에서는 우지박은 증가된 반면, 우모분과 내장분은 감소되어(P$<$0.05) 상반되는 결과를 나타내었다. 반추위 미분해 사료단백질의 하부장기내 이용율은 우모분, 우지박 및 내장분에 대해서 각각 80.4%, 83.8% 및 86.9%였으며, 열처리를 함으로써 우모분과 우지박은 각각 94.0% 및 91.3%로 향상되었으나, 내장분은 76.5%로 낮아졌다(P$<$0.05).

• 해양환경안전학회지
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• 제7권1호
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• pp.7-14
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• 2001

The amount of petroleum consumption has been Increased according to the industrialization and It leads to the increase of the possibility of marine oil pollution. In Korea, some countermeasures including oil skimmer, gelling agent and herding agent of oil have been used for the remediation of the pollution. However, most of them have lets of shortcomings in the application under in-situ condition, because they are sensitive to the situation such as geographical feature, the wind and the tide. In reported literature, the natural powdered oil absorbent which is made of peat moss is an effective mean to clean spilled oil from lake or coast. However, the peat moss is a natural resource which is only Produced from a specific cold weather are like Canada. This indicates that the alternative materials which is readily obtained from everywhere are needed for powdered oil absorbent. Therefore. in the study, same natural materials including pine leaves and straw are tested as the alternative materials for the absorbent. The raw materials were dried and treated by heat at various temperature during several Periods and then. shattered by a grain cracking machine. The oil sorption capacity of the prepared materials was compared according to the methods of heat treatment and their sizes. The proportion of hydrogen cyanide to combustion of the absorbents was measured to confirm their final disposal methods. The biodegradability test of the absorbents was carried our to evaluate possibility of a side pollution in the coast. In was found that the heat treatment of pine leaves enhanced the capacity of oil sorption and decreased the water sorption. The maximum oil sorption was observed for the material treated at 18$0^{\circ}C$for 60 min. The amount of hydrogen cyanide from the combustion were 0.09ml/g, 0.07ml/g for pine leaves and straw respectively meaning that the final disposal by combustion might be feasible. The amount or organic carbon extracted from pine leaves during 7 days was up to 0.015g organic carbon from one gram of pine leaves. but the degradation was as fast as for glucose. It is concluded that the pine leaves can be served as a good raw material for the powdered oil absorbent like peat moss.

• 한국전산유체공학회지
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• 제18권4호
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• pp.25-34
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• 2013

A numerical study of a laminar natural convection of the CuO-water nanofluid in a square cavity using the Buongiorno's nonhomogeneous model is presented. All the governing equations including the volume fraction equation are discretized on a cell-centered, non-uniform grid employing the finite-volume method with a primitive variable formulation. Calculations are performed over a range of Rayleigh numbers and volume fractions of the nanopartile. From the computed results, it is shown that both the homogeneous and nonhomogeneous models predict the deterioration of the natural convection heat transfer well with an increase of the volume fraction of nanoparticle at the same Rayleigh number, which was observed in the previous experimental studies. It is also shown that the differences in the computed results of the average Nusselt number at the wall between the homogeneous and nonhomogeneous models are very small, and this indicates that the slip mechanism of the Brown diffusion and thermophoresis effects are negligible in the laminar natural convection of the nanofluid. The degradation of the heat transfer with an increase of the volume fraction of the nanoparticle in the natural convection of nanofluid is due to the increase of the viscosity and the decrease of the thermal expansion coefficient and the specific heat. It is clarified in the present study that the previous controversies between the numerical and experimental studies are owing to the different definitions of the Nusselt number.