• 한국음향학회지
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• 제15권6호
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• pp.52-58
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• 1996

음파와 진동에너지를 활용하는 음파기술의 응용 연구분야로 음향공진 및 맥진동 현상을 이용하여 기액상에서 산소절달효율을 극대화 할 수 있는 폐수처리용 음향공진 산기관의 개념을 제안하였으며 원리와 성능시험을 수행하였다. 또한 저압용 헬름흘쯔 공진기, 실린더형 및 고리형 반사공진기 그리고 복합 공진시스템의 설계개념과 원리를 구현하였다. 물질전달 과정을 촉진하는 음향공진 에너지는 산소전달효율을 높여주며, 노즐에서 분출하는 공기 제트의 불평형에 의해 발생하는 주기적인 맥진동 현상은 미세한 공기방울을 만들어 내는데, 이 두가지 원리가 가장 잘 적용되는 고리형 반사공진기(AJR)의 성능이 가장 우수한 것으로 평가되었으며 기존의 산기관 보다도 $20{\sim}30%$ 정도 높은 효율을 실험으로 확인하였다.

• Environmental Engineering Research
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• 제15권2호
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• pp.63-70
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• 2010

In this study, the response surface method and experimental design were applied as an alternative to conventional methods for the optimization of coagulation tests. A central composite design, with 4 axial points, 4 factorial points and 5 replicates at the center point were used to build a model for predicting and optimizing the coagulation process. Mathematical model equations were derived by computer simulation programming with a least squares method using the Minitab 15 software. In these equations, the removal efficiencies of turbidity and total organic carbon (TOC) were expressed as second-order functions of two factors, such as alum dose and coagulation pH. Statistical checks (ANOVA table, $R^2$ and $R^2_{adj}$ value, model lack of fit test, and p value) indicated that the model was adequate for representing the experimental data. The p values showed that the quadratic effects of alum dose and coagulation pH were highly significant. In other words, these two factors had an important impact on the turbidity and TOC of treated water. To gain a better understanding of the two variables for optimal coagulation performance, the model was presented as both 3-D response surface and 2-D contour graphs. As a compromise for the simultaneously removal of maximum amounts of 92.5% turbidity and 39.5% TOC, the optimum conditions were found with 44 mg/L alum at pH 7.6. The predicted response from the model showed close agreement with the experimental data ($R^2$ values of 90.63% and 91.43% for turbidity removal and TOC removal, respectively), which demonstrates the effectiveness of this approach in achieving good predictions, while minimizing the number of experiments required.

• 한국환경과학회지
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• 제19권2호
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• pp.247-254
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• 2010

Ultrasound and Surfactant aided soil washing process has been shown to be an effective method to remove diesel from soils. The use of surfactants can improve the mobility of diesel in soil-water systems by increasing solubility of adsorbed diesel into surfactant micelles. However, a large amount of surfactant is required for treatment. In addition, synthetic surfactants, specially anionic, are more toxic and the surfactant wastewater is hard to treat by conventional wastewater treatments even by AOPs. Ultrasound improves desorption of the diesel adsorbed on to soil. The mechanisms are based on physical breakage of bonds by hot spot, directly impact onto soil particle surface, the fragmentation of long-chain hydrocarbons by micro-jet and microstreaming in the soil pores. The use of ultrasound as an enhancement method in both anionic and nonionic surfactant aided soil-washing processes were studied. And all experiments were examined proceeded under CMC surfactant concentration, frequency 35 khz, power 400 W, Soil-water ratio 1:3(wt%), particle size 0.24 ~ 2mm and initial diesel concentration. 20,000 mg/kg. Combination with ultrasound showed significant enhancements on all the processes. Especially, nonionic surfactant Triton-X100 with ultrasound showed remarkable enhancements and diesel removal rate enhanced by ultrasound helps desorpting of surfactant adsorbed onto soils which prevented decreasing surfactant activity.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.150-153
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• 2002

High dose rate (HDR) brachytherapy in the treatment of cervix carcinoma has become popular, because it eliminated many of the problems with conventional brachytherapy. In order to improve clinical effectiveness with HDR brachytherapy, dose calculation algorithm, optimization procedures, and image registrations should be verified by comparing the dose distributions from a planning computer and those from a humanoid phantom irradiated. Therefore, the humanoid phantom should be designed such that the dose distributions could be quantitatively evaluated by utilizing the dosimeters with high spatial resolution. Therefore, the small size of thermoluminescent dosimeter (TLD) chips with the dimension of 1/8" and film dosimetry with spatial resolution of <1mm used to measure the radiation dosages in the phantom. The humanoid phantom called a pelvic phantom is made of water and tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators are inserted into the grooves of the applicator supporters. The dose distributions around the applicators, such as Point A and B, can be measured by placing a series of TLD chips (TLD-to- TLD distance: 5mm) in three TLD holders, and placing three verification films in orthogonal planes.

• 상하수도학회지
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• 제29권1호
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• pp.33-38
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• 2015

In this study, flat-type photocatalytic reaction system is applied to reduce toxic hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in aqueous solution under UV irradiation. To overcome the limitation of conventional photocatalysis, a novel approach toward photocatalytic system for reduction of hexavalent chromium including nanotubular $TiO_2$ (NTT) on two kinds of titanium substrates (foil and mesh) were established. In addition, modified Ti substrates were prepared by bending treatment to increase reaction efficiency of Cr(VI) in the flat-type photocatalytic reactor. For the fabrication of NTT on Ti substrates, Ti foil and mesh was anodized with mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and then annealed in ambient oxygen. The prepared NTT arrays were uniformly grown on two Ti substrates and surface property measurements were performed through SEM and XRD. Hydraulic retention time(HRT) and substrate type were significantly affected the Cr(VI) reduction. Hence, the photocatalytic Cr(VI) reduction was observed to be highest up to 95% at bended(modified) Ti mesh and lowest HRT. Especially, Ti mesh was more effective as NTT substrate in this research.

• Membrane and Water Treatment
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• 제6권3호
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• pp.205-224
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• 2015

A novel hydrophilic poly (vinylidene fluoride)/poly (p-phenylene terephthalamide) (PVDF/PPTA) blend membrane was prepared by in situ polycondensation of p-phenylene diamine (PPD) and terephthaloyl chloride (TPC) in PVDF solution with subsequent nonsolvent induced phase separation (NIPS) process. For comparison, conventional solution blend membrane was prepared directly by adding PVDF powder into PPTA polycondensation solution. Blend membranes were characterized by means of viscometry, X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM). The effects of different blending methods on membrane performance including water contact angle (WCA), mechanical strength, anti-fouling and anti-compression properties were investigated and compared. Stronger interactions between PVDF and PPTA in in situ blend membranes were verified by viscosity and XPS analysis. The incorporation of PPTA accelerated the demixing rate and caused the formation of a more porous structure in blend membranes. In situ blend membranes exhibited better hydrophilicity and higher tensile strength. The optimal values of WCA and tensile strength were $65^{\circ}$ and 34.1 MPa, which were reduced by 26.1% and increased by 26.3% compared with pure PVDF membrane. Additionally, antifouling properties of in situ blend membranes were greatly improved than pure PVDF membrane with an increasing of flux recovery ratio by 25%. Excellent anti-compression properties were obtained in in situ blend membranes with a stable pore morphology. The correlations among membrane formation mechanism, structure and performance were also discussed.

• 상하수도학회지
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• 제12권4호
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• pp.86-96
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• 1998

In this study, an intermittently aerated activated sludge process, modified process from conventional activated sludge process, was developed to treat high strength swine wastewater, which has been blamed as major pollutant for stream pollution. Therefore, the optimum cycle for oxic and anoxic period, SRT, and OLR were studied as design parameters. The effects of different time interval for oxic and anoxic period on nitrification and denitrification were examined by operating two reactors with 60/60min and 60/90min as oxic/anoxic period. Although the reactor with 60/60min showed complete denitrification of $NO_x-N$ generated during oxic period, the reactor with 60/90min showed incomplete nitrification due to the inactivity of nitrifier by accumulated $NH_3-N$ toxicity during anoxic period. Therefore, it is recommended to operate same interval for oxic and anoxic period. In order to determine the optimum cycle for oxic/anoxic period, four different reactors with 30/30, 60/60, 90/90 and 120/120min were examined. The reactor operation with 90/90min was optimum to get the most stable results in this study. However, the optimum cycle for oxic and anoxic period should be changed with characteristics of influent wastewater and operating conditions. According to lie operation results of three reactors with SRT of 15, 20 and 30days. The reactor with 2Odays SRT showed best removal efficiency of T-N. The optimum OLR would be $2.5Kg\;COD/m^3/day$ which showed the most stable nitrification and denitrification. Since characteristics of influent wastewater in the real system has a severe fluctuation, so it is very difficult to determine each interval for oxic and anoxic period. Therefore, ORP curves, describing the change of oxidation/reduction potential in reactor, can be used as a control parameter for automatic control of oxic and anoxic period. In other words, bending point (Nitrate Knee) of ORP curve during anoxic period could be used as a starting point of oxic period.

• 한국토양비료학회지
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• 제44권3호
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• pp.371-374
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• 2011

벼 유기농업을 실천하기 위하여 무경운 논에서 피복작물로 자운영, 볏짚, 헤어리베치, 유채 및 호밀 등을 처리하고 논물의 미소동물 개체수의 변화를 검토코자 수행하였다. 이앙전 5월 30일 논물의 미소동물 개체수는 무경운 헤어리 배치 처리구가 관행, 무경운 자운영 처리, 무경운 유채 처리, 무경운 호밀 처리 및 무경운 녹비 무처리에 비해 유의적으로 많았다 (p<0.05). 이앙후 6월 20일 논물의 물벼룩과 모기유충 개체수는 관행이 무경운 처리구에 비해 유의적으로 낮았다 (p<0.05). 주성분 분석결과 관행은 무경운 처리구와 유의적으로 차이가 있었으며 무경운 처리에서는 무경운 자운영 처리와 무경운 헤어리베치 처리가 무경운 녹비 무처리, 무경운 유채 처리 및 무경운 호밀 처리구와 유의적인 차이가 있었다. 무경운 논에서 유기물 투입이 논물의 미소동물 개체수 증가에 기여하였으며 분해가 느린 호밀과 유채 보다 분해가 빠른 두과작물이 미소동물 개체수 증가에 유리하였고 벼 유기농업의 지표로 물벼룩의 개체수를 적용할 수 있을 것으로 판단된다.

• 대한환경공학회지
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• 제31권9호
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• pp.765-774
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• 2009

섬유염색 및 가공산업은 용수요구량이 매우 높은 편이며 다양한 난분해성 염료의 사용으로 인해 폐수발생량의 기여도가 높은 전형적인 오염 유발 산업이다. 본 연구는 낙동강 수계에서 산업폐수 발생업체 중 섬유염색 및 가공 산업시설을 중심으로 SS, $BOD_5,\;COD_{Mn},\;COD_{Cr}$, TN 그리고 TP와 같은 수질 항목에 대해서 발생원 단위 오염물질 배출 특성을 파악하고 발생원단위 부하량을 산출하기 위해 수행되었다. 각 산업을 대표하는 오염원 발생원단위의 산정을 위해 낙동강 수계에 산재한 섬유염색 및 가공업체 중 세 개 업체를 선정하였다. BOD 기준 유입수와 유출수에서의 원단위 값은 90%이상 감소하였지만 원수에서의 높은 유기물 부하량으로 인해 원단위값 자체는 섬유제조시설에서 얻어진 값과 유사하였다. 유수의 생분해도는 유출수에 비해 세배 가량 높게 나타났다. 건평, 제품생산량 및 원료사용량을 기준으로 한 주요 수질 항목 (SS, $BOD_5$, COD, TN and TP)에서 단위공정(본 연구에서 산정한 값)의 오염원 발생원단위 결과값이 통합공정(국립환 경과학원에서 산정한 값)의 오염원 발생원단위 결과 값과 유사하였지만 다른 인자를 기준으로 한 경우에는 커다란 차이를 보여주었다. 섬유염색 및 가공업체에서 도출된 오염원 발생원단위 인자는 낙동강 수질 오염총량제 도입과 함께 수질오염 부하량 처리비용을 산정 할 때 유용한 자료로 활용될 수 있으리라 기대된다. 이러한 오염원 발생부하량 도출과 함께 낙동강 수계에서의 효과적인 수질오염제어와 관리를 위해서는 각 산업별 폐수처리시설의 유출수로부터 다양한 형태의 수질오염항목을 특성화시킬 필요가 있다.

• 한국식품영양과학회지
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• 제30권5호
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• pp.796-801
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• 2001

최근에 음용이 증가하고 있는 강원도지역 먹는 샘물로부터 Yersinia spp.의 부포현황을 조사하기 위하여 1999년과 2000년에 강원지역 18개 시군 전역에 산재한 공동샘터수 277건을 수거한 후 미국 FDA방법과 Bergey’s manual을 참조하여 형태학적, 배양학적, 생화학적방법으로 균을 분리동정하였으며 분리균의 생물형, 혈청형, 항균제 감수성조사 및 효율적인 균리방법에 대한 조사를 실시하였다. 샘터수 277건 중에 40건(14.4%)에서 Yersinia spp.가 분리되었으며, 균종별 분리빈도는 40건중에서 Y. enterocolitica 33주(82.5%)로 가장 많이 분리되었으며, Y. frederiksenii 4주(10%), Y. in-termedia 2주(5%), Y.sakazaki 1주(2.5%)순으로 분리되었다. 지역별로 Y. enterocolitica 분리실태를 보면 철원군(5주), 인제군(5주) 등 11개 군지역에서 평균 2.6주가 분리되었고, 태백시(2주), 춘천시(1주) 등 3개 시지역에서 평균 1.3주가 분리되어 군소재 먹는 샘물이 도시지역 먹는 샘물에 비해 2배 정도 높은 균검출율을 나타내었다. 배양방법에 따른 Y. enterocolitica 분리율을 비교하면 시료를 KOH처리하여 직접 CIN 배지에 분리한 직접배양법에서는 분리율이 6.1%이었고, 시료를 PSBB배지에 1$0^{\circ}C$, 10일간 저온배양 후 KOH로 처리하여 CIN배지에 분리한 저온증균배양법에서 18.5%의 분리율을 나타내어 저온증균법이 직접법에 비해 3배 높은 균검출 효과를 나타내었다. 한편, Y. enterocolitica 33주에 대한 아형(subtype) 조사 결과 생물형 분포는 1A형이 22주(71.0%)로 가장 많았고 3A형 4주(12.9%), 3B형 3주(9.7%), 1B형과 5형이 각각 1주(3.2%)씩이었으며, 혈철형 분포는 O : 5형이 4주(12.9%)로서 가장 많았으며 O : 3형 3주(9.7%), O : 8형 2주(6.5%) 및 O : 9형 1주(3.2%)이었고 나머지 21주(67.7%)는 혈청형을 확인할 수 없었다. 또한, 분리된 Y. enterocolitica의 12종 항생제에 대한 감수성 시험결과는 ampicillin, cephalothin, carbenicillin에 각각 70%, 70%, 52%의 저항성을 보였고 나머지 nalidixic acid, streptomycin, tetracycline, tobramycin, chloramphenicol, kanamycin gentamycin, trimethoprim, ciprofloxacin에 대하여는 대부분 감수성을 나타내었으며, ampicillin, cephalothin, carbenicillin 등 3종 항생제에 다제내성을 보인 경우는 39%이었다.