• 상하수도학회지
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• 제26권5호
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• pp.685-692
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• 2012

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

• 한국환경과학회지
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• 제21권7호
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• pp.845-853
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• 2012

Diethyl phthalate (DEP) is widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including various applied power density (10-40 W/L), UV wavelengths (365 nm, 254 nm and 185 nm) and frequencies (283 kHz, 935 kHz) were applied to a DEP contaminated solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}\;min^{-1}$ depending on the processes. Photolytic and sonophotolytic DEP degradation rate also were high at shortest UV wavelength (VUV) due to the higher energy of photons, higher molar absorption coefficient of DEP and increased hydroxyl radical generation from homolysis of water. Sonolytic DEP degradation rate increased with increase of applied input power and the dominant reaction mechanism of DEP in sonolysis was estimated as hydroxyl radical reaction by the addition of t-BuOH, which is a common hydroxyl radical scavenger. Moreover, synergistic effect of were also observed for sonophotolytic degradation with various UV irradiation.

• 한국물환경학회지
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• 제28권1호
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• pp.57-62
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• 2012

In this study, the inactivation efficiency of Mycobacterium marinum was evaluated in buffered water (pH 7) using a low pressure ultraviolet (LP-UV) lamp, ultrasonic (US), and UV/US sequential processes. In the UV alone process, 3 log inactivation of the M. marinum was achieved with a UV dose of $120mJ/cm^2$. However, a tailing phase was later observed because M. marinum has a high tendency for cell aggregation. Even though the M. marinum was not inactivated in the US alone process, the hydrophobicity decreased and turbidity increased due to the crumbling of the cell aggregation. Among the candidate processes which were UV alone, US-UV sequential process and UV-US-UV sequential process, the US-UV sequential process showed the highest synergistic effects for M. marinum inactivation. Consequently, US is a very useful process as a UV irradiation pre-treatment to inactivate M. marinum in water.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1416-1425
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• 2002

In this study, the effects of combined environmental factors on mechanical and thermal analysis properties of graphite/epoxy composites were evaluated by the use of an accelerated aging test. Environmental factors such as temperature, moisture. and ultraviolet were considered. A xenon-arc lamp was utilized for ultraviolet light. and exposure times of up to 3000 hours were applied. Several types of specimens - tensile. bending, and shear specimens those are transverse to the fiber direction, and bending specimens those are parallel to the tiber direction - were used to investigate the effects of environmental factors on mechanical properties of the composites. Also, glass transition temperature, storage shear modulus, loss shear modulus, and tan ${\delta}$ were measured as a function of exposure times through a dynamic mechanical analyzer. In addition. a suitable testing method for determining the effect of environmental factors on mechanical properties is suggested by comparing the results from using two different types of strain measuring sensors. Finally, composite surfaces exposed to environmental factors were examined using a scanning electron microscope.

• 상하수도학회지
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• 제20권5호
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• pp.755-761
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• 2006

Recently, there is growing interest in ultraviolet (UV) irradiation as a disinfection technic in drinking water production due to its effectiveness to inactivate microorganisms such as Crytosporidium parvum without forming disinfection byproducts. However, UV disinfection is known for its drawback such as photoreactivation. Despite many works concerning the photoreactivation, most of works were focused on indicator or non pathogenic microorganisms. The objective of this study is to examine the photoreactivation of Pseudomonas aeruginosa which is an opportunistic pathogen as UV radiation by LP and MP UV lamp was applied. The result showed that P. aeruginosa had high photo repair efficiency regardless of the type of UV irradiation. Both of the effective log repair values of LP and MP UV irradiation were found approximately 2.6 log. In addition, photo repaired P. aeruginosa was not significantly different in forming biofilm in comparison with non treated P. aeruginosa.

• 대한기계학회논문집B
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• 제24권6호
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• pp.753-759
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• 2000

Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.

• 한국대기환경학회지
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• 제33권2호
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• pp.87-96
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• 2017

In this study, 4 gases containing typical chlorinated volatile organic compounds (VOCs) were treated by ultraviolet (UV) irradiation. The typical chlorinated VOCs are dichloromethane (DCM), trichloromethane (TCM), carbon tetrachloride (CTC) and trichloroethylene (TCE). The removal efficiency (RE) and the products of chlorinated VOCs by UV irradiation are investigated. At this time, 2 types of background gas (air and nitrogen) were used to figure out the RE by photooxidation and photolysis. The specification of UV-lamp used in this study was low-pressure mercury lamp emitting wavelength of 185~254 nm. The experimental conditions were set as initial VOC concentration of $180{\pm}10ppm$, empty bed retention time (EBRT) of 53 s, temperature of $23{\pm}2^{\circ}C$ and relative humidity of $65{\pm}5%$. In the photolysis condition with nitrogen ($N_2$) as background gas, the averaged RE of the 4 types of chlorinated VOCs was about 24% higher than that with photooxidation; and the REs of VOCs except CTC were confirmed as >99%. The composition of off-gases after UV photooxidation in air was investigated and several intermediates from DCM, TCM and TCE were detected by GC/MS. Among them, phosgene which is a toxics was detected as an intermediate of TCM. In addition, the concentration of carbon dioxide ($CO_2$) in the off-gases was measured to calculate the mineralization rate (MR). With the photooxidation, TCE showed the highest RE (>99%) while MR was the lowest (17%); and the MR of DCM was the highest (86%). In addition, particulate matters (PM) in the off-gases was also detected and high concentrated $PM_{10}$ ($21,580{\mu}g{\cdot}m^{-3}$) and $PM_{2.5}$ ($6,346{\mu}g{\cdot}m^{-3}$) were detected in TCE off-gas. More than 99% of the chlorinated VOCs could be removed using UV254-185 nm lamp, while it is necessary to conduct further studies on the production and treatment of secondary pollutants.

• 한국건설순환자원학회논문집
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• 제8권3호
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• pp.356-364
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• 2020

본 연구에서는 광촉매를 혼입한 모르타르의 방오성능을 평가하기 위해 메틸렌 블루를 이용한 실험 연구를 수행하였다. 실험 시편은 시멘트 중량대비 2.5%, 5.0%, 7.5% 및 10.0%의 광촉매를 혼입하여 모르타르 시편을 제작하였고, 시편 표면에 스크래치 형태로 조도를 설정하였다. 표면 조도는 3가지로 조도가 없는 경우, 조도가 작은 경우(중간 조도), 조도가 큰 경우(거친 조도)로 설정하였다. 모르타르 시편 제작 후 24시간 동안 자외선램프 조사와 12시간 동안 메틸렌 블루 컨디셔닝 용액에 침지 하는 전처리 과정을 진행하였다. 실험챔버에 전처리가 완료된 모르타르 시편을 배치 후 48시간 동안 자외선램프를 조사하였고 시간에 따라 메틸렌 블루 수용액의 색 변화를 분광측색계를 이용하여 측정하였다. 광촉매의 혼입량이 증가할수록 메틸렌 블루 색 변화는 증가하는 경향을 나타내며 이는 방오성능이 증가하는 것을 의미한다. 반면에 표면조도가 증가할수록 메틸렌 블루 용액의 색 변화는 뚜렷한 경향은 나타내지 않으며 표면의 광촉매 분포가 일정하지 않기 때문이다.

• 대한약리학회지
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• 제31권3호
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• pp.285-290
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• 1995

이 실험은 여러 파장$(240{\sim}520\;nm)$의 자외선 또는 가시광선(이후 '광선'이라 표기함)을 흰쥐흉부대동맥에 조사하여 이때의 혈관장력의 변화 및 조직내 cyclic GMP농도의 변화를 관찰하기위하여 시행하였다. 돼지관상동맥 또는 흰쥐 흉부대동맥의 환상표본에 spectrofluorometer의 xenon lamp를 이용하여 여러 파장의 광선을 조사하고 이때의 장력변동을 polygraph상에 기록하였다. Cyclic GMP농도변화는 표본에 광선을 조사한 직후 조직을 얼리고 homogenization 및 원침시킨 후 상청액을 ether로 추출하여 RIA kit로 측정하였다. Phenylephrine으로 수축된 내피존재 흰쥐 흉부 대동맥에서는 광선조사로 수축반응을 보였고 320 nm에서 최대수축반응을 일으켰다. 그 이상의 파장에서는 점차 수축반응이 감소되어 420 nm에서는 최대 이완반응을 일으킨 후 점차 기본장력으로 회복되었다. 그러나 내피제거 표본에서는 전파장에서 이완반응만을 일으켰고 이때 최대 이완반응은 370 nm에서 관찰되었다. 내피존재 표본에서 320, 380 및 420 nm의 광선을 30초간 조사한 결과 380과 420nm에서 현저한 cyclic GMP의 증가가 관찰되었으나 320 nm에서는 유의한 변동이 없었다. 한편, 내피제거 표본에서는370 nm의 광선조사로 cyclic GMP함량이 약 4배 증가하였다. 이상의 성적으로부터 흰쥐 흉부대동맥은 광선조사에 의하여 내피존재 표본에서는 수축-이완의 이상성반응을, 제거표본에서는 이완반응만을 일으키고 양 표본의 이완반응은 nitric oxide-cyclic GMP계의 활성화에 기인하나 수축반응은 cyclic GMP계와 직접 관련성이 없는 것으로 추론하였다.

• 식물병연구
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• 제28권2호
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• pp.61-68
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• 2022

딸기에 발생하는 흰가루병과 점박이응애는 수확기 문제되는 주요 병해충이다. 딸기 수확기 병해충방제를 위해 적용 약제를 처리하지만 최근에는 소비자의 요구에 따라 친환경적 병해충 방제 방법이 요구되고 있다. 딸기 정식 후 자외선 램프(ultraviolet B, UV-B)를 이용한 친환경 병해충 방제효과를 조사하기 위해 수확기 토경과 수경재배로 2년 동안 시험을 수행하였다. 설향, 킹스베리, 두리향 품종을 정식하였으며 UV-B 램프+멀칭 종류(흑색, 녹색, 빛반사시트[light reflection sheet, LRS])별 4처리로 시험을 수행하였다. 처리는 UV-B+흑색 또는 녹색 멀칭, UV-B+흑색 또는 녹색+LRS, 무처리로 하였다. UV-B 램프 처리에 의한 흰가루병은 모든 품종에서 65% 이상의 방제효과를 보였다. 점박이응애 성충밀도는 UV-B+흑색 또는 녹색+LRS 멀칭 처리가 다른 처리보다 가장 낮았다. 따라서 딸기 수확기에 UV-B 램프 처리는 식물체에 미치는 영향도 적으며 흰가루병과 점박이응애 밀도를 낮추는 데 효과적인방제방법이될수있다.