• 한국지하수토양환경학회지:지하수토양환경
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• 제12권3호
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• pp.75-80
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• 2007

본 연구에서는 W시에 있는 비위생매립지 주변의 지하수질 약 2년간 관측하고 그 결과를 평가하였다. 주요관심 인자는 산화환원조건에 민감한 pH, 용존산소, 전기전도도, 산화환원전위, 용존 유기탄소, 암모니아, 질산성질소 및 황산이온 등이다. 본 매립지는 생활쓰레기 매립지로 매립종료 약 10년이 경과하였다. 매립지 침출수는 COD 136${\sim}$263 mg/L, T-N 121${\sim}$186 mg/L, NH3-N 14${\sim}$369 mg/L이며, 계절적 변동이 크게 나타났다. 매립지 직하부 지하수는 약산성을 띄나 전기전도도가 매우 높아 침출수 누출의 영향을 나타내었다. 염소이온의 경우 200 mg/L 이상으로 높으나 거리가 멀어짐에 따라 점차 감소하였는데 확산 및 희석 등의 자연저감효과가 큰 것으로 사료된다. 매립지 내부에서는 산화 환원전위가 음의 값을 보이나 하부에서는 350 mV까지 증가하여 혐기성환경에서 산화환경으로의 전이를 나타내었다. 암모니아는 가장 우려되는 지하수질 인자인데 대부분의 관측정에서 크게 부화되어 있으며, 먹는물 수질기준을 상회하였다. 본 매립지 하부의 오염지하수질은 시공간적으로 자연저감 현상이 뚜렷하나 지속적인 수질모니터링이 필요한 것으로 판단된다.

• 환경생물
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• 제26권4호
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• pp.292-302
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• 2008

본 연구는 Ecopath 모델을 이용하여 유수생태계인 낙동강 하류 생태계의 영양구조와 에너지 흐름을 알아보고자 하였다. 이를 위해 2007년 갈수기(5월)와 풍수기(8월)에 낙동강 하류 삼랑진 일대의 6개 지점에서 조사를 실시하였으며, 어류의 각 어종별 밀도와 자원량 자료를 위해 2007년 3월에서 11월까지 매달 2회씩 조사를 실시하였다. 낙동강 하류 생태계는 수온이 $20.9\sim31.4^{\circ}C$, 전기전도도 $135\sim364{\mu}s\;cm^{-1}$, 용존산소 $9.0\sim10.5mg\;L^{-1}$, pH는 10.4$\sim$10.7, TOC 2.3$\sim$2.7 mg L$^{-1}$, DOC 2.2$\sim$2.6 mg L$^{-1}$, 수심 0.5$\sim$9.0 m, 투명도 0.3$\sim$0.5 m등의 범위를 보이는 것으로 조사되었다. 낙동강 하류 생태계는 크게 3단계 즉, 생산자와 1차 소비자, 2차 소비자로 나누어지는 영양단계를 보였다. 생산자에 해당하는 생물군은 유기패설물, 식물플랑크톤, 대형수생식물이었고, 1차 소비자는 동물플랑크톤, 저서동물, 잉어, 누치, 기타어류 등이었으며, 2차 소비자는 배스였다. 낙동강 하류 생태계의 총에너지량은 2.7 kg m$^{-2}$로 나타났으며, 52.0%는 섭식으로, 9.1%는 이출, 18.0%는 호흡, 20.9%는 유기쇄설물로 전환되는 것으로 나타났다. 또한, 혼합영양영향(MTI)결과 최고포식자로 추정된 배스의 생체량 증감은 배스와 기타 어류에게는 음의 효과를, 누치와 잉어, 저서동물, 동물플랑크톤, 식물플랑크톤 등에게는 양의 효과를 직 간접적으로 미치는 것으로 나타났으며, 각 그룹의 생체량증가는 각 생물그룹별 생체량을 감소시키는 음의 효과를 보이는 것으로 나타났다.

• 폴리머
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• 제32권4호
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• pp.359-365
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• 2008

전기방사법에 의해 미생물 유래의 나노섬유 부직포를 제조하였고, 전자선조사에 의해 나노섬유상에 poly(N-isopropylacrylamide)(PIPAAm)을 그래프트함으로써 온도응답성 나노섬유표면을 제조하였다. 얻어진 나노섬유는 랜덤하게 배열되었으며 평균직경이 400 nm이었다. ATR-FTIR 및 ESCA 분석에 의해서 PIPAAm이 나노섬유 표면에 성공적으로 그래프트되었음을 확인하였다. PIPAAm을 그래프트 하지 않은 표면에서는 물접촉각의 변화가 없었으나, PIPAAm이 그래프트된 나노섬유 표면에서는 온도가 $37^{\circ}C$에서 $20^{\circ}C$로 바뀜에 따라 물접촉각이 감소하였다. 이러한 결과는 PIPAAm이 그래프트된 표면에서 높은 온도에서는 소수성의 특성을 가지다가, 낮은 온도에서는 PIPAAm 사슬이 수화되면서 친수성으로 바뀌었기 때문이다. 제조한 온도응답성 나노섬유는 조직적합성이 우수하였으며, 저온처리에 의해 배양세포가 원활히 탈착 회수됨을 알 수 있었다.

• 한국전문물리치료학회지
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• 제13권3호
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• pp.33-40
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• 2006

The purpose of this study was to assess the effects of High-Voltage Pulsed Current (HVPC) and ultrasound on adjuvant-induced arthritis in rats. Adjuvant arthritis was induced in female Sprauge-Dawley rats by the subcutaneous injection of a single dose of $.1m{\ell}$ of Complete Freund's Adjuvant (CFA) (1 mg of Mycobacterium Butyricum suspended in $.1m{\ell}$ paraffin oil) into the right hind paw. A randomized, parallel-groups design of 24 subjects was used. All rats were randomly assigned to control (n=8), ultrasound (n=8), and HVPC (n=8) were compared with those of injured rats. The rats in the pulsed ultrasound group were treated at 1 MHz frequency with $.5W/cm^2$ intensity in 1:4 mode for 5 minutes per day. The rats in the HVPC group were treated at 120 pulses per second and $50{\mu}s$ phase duration, 20 mA intensity for 30 min per day. Treatment was done in the left and right hind limb for 2 weeks. We evaluated clinical, radiographic, hematologic and histopathologic findings before and after treatment and obtained the following results. 1. Edema of the right hind paw was more significantly reduced in the ultrasound and HVPC groups than the control group on days 9, 12, and 14 (p<.05). Edema of the left hind paw was more significantly reduced in ultrasound and HVPC groups than the control group on days 12, 14 (p<.05). 2. WBC counts of the ultrasound and HVPC groups as compared with the control group were becoming remarkably decreased after the treatment. 3. In radiologic findings, arthritis formation was seen according to the score of arthritis, which was the highest in the control group, upon the observation of radiographs of the left and right hind paws. However, no statistically significant difference was present in the score within three groups. 4. In the histopathologic findings, ultrasound and HVPC groups had effectively suppressed erosions of articular cartilage and inflammatory cell infiltrations. Therefore, the results of the study show that rats that were treated with the ultrasound and HVPC effectively suppressed adjuvant arthritis. However, no statistically significant difference was present between the ultrasound group and the HVPC group.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.64.1-64.1
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• 2010

The morphology of mesoporous $TiO_2$ films plays an important role in the operation of a DSSC. For example, the energy conversion efficiency of DSSCs with well-organized mesoporous $TiO_2$ films is much higher than those with traditional films possessing a random morphology. In previous research, well-organized mesoporous $TiO_2$ films have mainly been synthesized using an amphiphilic block copolymer, e.g., a poly(ethylene oxide) (PEO)-based template. A graft copolymer is more attractive than a block copolymer due to its low cost and the ease with which it can be synthesized. In this work, we provide the first report on the successful synthesis of well-organized mesoporous $TiO_2$ films templated by an organized graft copolymer as a structure directing agent. Well-organized mesoporous $TiO_2$ films with excellent channel connectivities were developed via the sol gel processusing an organized PVC-g-POEM graft copolymer synthesized by one-pot ATRP. The careful adjustment of copolymer composition and solvent affinity using a THF/$H_2O$/HCl mixture was used to systematically vary the material structure. The influence of the material structure on solar cell performance was then investigated. A solid-state DSSC employing both the graft copolymer templated organized 700 nm-thick $TiO_2$ films and graft copolymer electrolytes exhibited a solar conversion efficiency of 2.2% at 100 $mW/cm^2$. This value was approximately two-fold higher than that attained from a DSSC employing a random mesoporous $TiO_2$ film. The solar cell performance was maximized at 4.6% when the film thickness was increased to $2.5{\mu}m$. We believe that this graft copolymer-directed approach introduces a new and simple route toward the synthesis of well-organized metal oxide films as an alternative to a conventional block copolymer-based template.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.278-278
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• 2009

A photovoltaic device consisting of arrays of radial p-n junction wires enables a decoupling of the requirements for light absorption and carrier extraction into orthogonal spatial directions. Each individual p-n junction wire in the cell is long in the direction of incident light, allowing for effective light absorption, but thin in orthogonal direction, allowing for effective carrier collection. To fabricate radial p-n junction solar cells, p or n-type vertical Si wire cores need to be produced. The majority of Si wires are produced by the vapor-liquid-solid (VLS) method. But contamination of the Si wires by metallic impurities such as Au, which is used for metal catalyst in the VLS technique, results in reduction of conversion efficiency of solar cells. To overcome impurity issue, top-down methods like noble metal catalytic etching is an excellent candidate. We used noble metal catalytic etching methods to make Si wire arrays. The used noble metal is two; Au and Pt. The method is noble metal deposition on photolithographycally defined Si surface by sputtering and then etching in various BOE and $H_2O_2$ solutions. The Si substrates were p-type ($10{\sim}20ohm{\cdot}cm$). The areas that noble metal was not deposited due to photo resist covering were not etched in noble metal catalytic etching. The Si wires of several tens of ${\mu}m$ in height were formed in uncovered areas by photo resist. The side surface of Si wires was very rough. When the distance of Si wires is longer than diameter of that Si nanowires are formed between Si wires. Theses Si nanowires can be removed by immersing the specimen in KOH solution. The optimum noble metal thickness exists for Si wires fabrication. The thicker or the thinner noble metal than the optimum thickness could not show well defined Si wire arrays. The solution composition observed in the highest etching rate was BOE(16.3ml)/$H_2O_2$(0.44M) in Au assisted chemical etching method. The morphology difference was compared between Au and Pt metal assisted chemical etching. The efficiencies of radial p-n junction solar Cells made of the Si wire arrays were also measured.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.321-323
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• 2012

유기 발광 다이오우드는(OLEDs) 자체 발광 소자로써 높은 시야각, 높은 효율, 그리고 빠른 응답속도 등의 장점을 가지고 있어 차세대 디스플레이 및 조명 소자로서 많은 연구가 진행되고 있다. 특히 유기 발광 다이오우드는 차세대 반도체 조명 소자로서 조명의 패러다임을 바꿀 수 있는 기술로 인식되고 있다. 하지만, 유기 발광 다이오우드 조명의 상용화를 위해서는 가격 경쟁력을 갖추는 것이 시급하며, 이를 위해 저가 공정 개발이 필요하다. 본 연구에서는 유기발광 다이오우드 조명 제작에 필수적인 전면 전극 및 절연막 증착 공정을 기존의 노광 공정이 아닌 shadow mask 기술을 적용하여 형성하였다. 먼저 유리 기판 상에 150 nm 두께의 ITO 막을 shadow mask를 이용하여 증착하였다. 기존 공정에서는 노광 및 식각 공정을 이용하여 증착하는 것이 일반적이며, 광학적, 전기적 특성 또한 타 공정 방법에 비해 우수하다. 하지만 일련의 복잡한 공정으로 인해 제조 원가를 상승 시키는 단점이 있다. Fig. 1은 shadow mask를 이용하여 ITO를 증착을 수행한 공정의 모식도이다. ITO 박막 증착 후 표면 거칠기 제어 및 면저항 제어를 위해 O2 plasma 처리와 RTA 공정을 추가 수행하였다. Fig. 2(a)는 플라즈마 처리 및 열처리 공정 수행 후에 측정한 표면 AFM 사진이다. 열처리 및 플라즈마 처리 후에 ITO 박막의 표면 거칠기는 10배 이상 향상되었으며, 이는 유기 발광 다이오우드 조명 소자의 전면 투명 전극으로 사용되기에 적합한 값이다. 또한 전기적 특성 중 하나인 면저항 값은 열처리 및 플라즈마 처리 전/후의 값에서 많은 차이를 보인다. 표면 거칠기가 향상됨에 따라 면저항 값 역시 향상되는 결과를 보여주는데, 표면 처리전후의 면저항 값은 각각 28.17, 13.18 ${\Omega}/{\Box}$이다. 일반적으로 유기 발광 다이오우드의 전면 투명 전극으로 사용되기 위해서는 15 ${\Omega}/{\Box}$이하의 면저항 값이 필요한데, 표면 처리 후의 면저항값들은 이로한 조건을 만족한다. Fig. 3은 shadow mask 기술을 이용하여 절연막까지 형성한 유기 발광 다이오우드 소자의 전자 현미경 사진으로, 기존의 공정을 이용한 경우와 큰 차이는 없으며, 다만 shadow tail이 약 $30{\mu}m$ 정도 발생함을 확인할 수 있다. 절연막의 특성 평가 기준인 누설 전류 밀도는 $10-5A/cm^2$으로 기존의 공정을 이용한 경우에 비해 95% 수준으로서 shadow mask를 이용한 공정이 기존의 노광 및 식각 공정을 이용한 경우에 비해 공정 수는 9개가 단축됨에도 불구하고, 각 증착 박막의 특성에는 큰 차이가 없음을 알 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.193-193
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• 2012

In thin film silicon solar cells, p-i-n structure is adopted instead of p/n junction structure as in wafer-based Si solar cells. PECVD is the most widely used thin film deposition process for a-Si:H or ${\mu}c$-Si:H solar cells. Single-chamber PECVD system for a-Si:H solar cell manufacturing has the advantage of lower initial investment and maintenance cost for the equipment. However, in single-chamber PECVD system, doped and intrinsic layers are deposited in one plasma chamber, which inevitably impedes sharp dopant profiles at the interfaces due to the contamination from previous deposition process. The cross-contamination between layers is a serious drawback of single-chamber PECVD system. In this study, a new plasma process to solve the cross-contamination problem in a single-chamber PECVD system was suggested. In order to remove the deposited B inside of the plasma chamber during p-layer deposition, a high RF power was applied right after p-layer deposition with SiH4 gas off, which is then followed by i-layer, n-layer, and Ag top-electrode deposition without vacuum break. In addition to the p-i interface control, various interface control techniques such as FTO-glass pre-annealing in O2 environment to further reduce sheet resistance of FTO-glass, thin layer of TiO2 deposition to prevent H2 plasma reduction of FTO layer, and hydrogen plasma treatment prior to n-layer deposition, etc. were developed. The best initial solar cell efficiency using single-chamber PECVD system of 10.5% for test cell area of 0.2 $cm^2$ could be achieved by adopting various interface control methods.

• Asian-Australasian Journal of Animal Sciences
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• 제18권12호
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• pp.1752-1760
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• 2005

In this experiment, the effects of cage density (CD) and probiotic supplementation (PS) on laying performance, metabolic profile, and egg quality in peak-producing hens were evaluated. After blocking according to the cage location, Lohman layers (n = 180, 46 wks of age) were allocated randomly to two levels of CD (540 vs. 360 $cm^2$/hen) and three levels of PS (0, 0.15, and 0.30%). Probiotic contained Enterococcus faecium culture (10${\times}$10$^9$ cfu/g). Egg production (EP) and feed consumption (FC) were measured daily; egg weight (EW) was measured bi-weekly; BW was measured before and after the experiment; and blood samples were obtained at the end of the experiment. The data were analyzed using two-way ANOVA. Increasing CD decreased FC (125.0 vs. 120.8 g/d, p<0.0001) and FCR (1.93 vs. 1.87, p<0.0001) and did not alter EP, EW, and BW. Increasing level of PS linearly decreased FC (p<0.02) and FCR (p<0.006). Averages were 123.9, 123.2, and 121.6 g/d for FC and 1.91, 1.92, and 1.86 for FCR in hens supplemented with 0, 0.15, and 0.30% probiotic, respectively. Hens placed in high-density cages had greater serum corticosterone concentration than hens placed in normal-density cages (12.8 vs. 11.3 $\mu$g/dL, p<0.04); CD did not affect concentrations of other metabolites. Increasing level of PS linearly increased serum glucose, albumin, and creatine concentrations and quadratically increased total protein, globulin, Ca, and P concentrations. Average concentrations (mg/dL) were 260, 297, and 305 for glucose; 6.28, 8.09, and 7.58 for total protein; 1.98, 2.48, and 2.38 for albumin; 4.30, 5.62, and 5.19 for globulin; 0.40, 0.52, and 0.54 for creatine; 16.0, 16.5, and 16.3 for Ca; and 6.27, 8.14, and 7.17 for P in hens supplemented with 0, 0.15, and 0.30% probiotic, respectively. There was no effect of CD on egg quality. Increasing level of PS linearly improved yolk color (YC) and quadratically increased albumen index (AI) and Haugh unit (HU). The mean values were 9.67, 9.75, and 10.58 for YC; 8.94, 6.93, and 8.72% for AI; and 85.6, 74.9, and 82.9 for HU for hens supplemented with 0, 0.15, and 0.30% probiotic, respectively. There was also CD by PS effect on FC, EP, and serum glucose, total protein, albumin, globulin, creatine, Ca and P concentrations. In conclusion, increased CD partially depressed laying performance and caused stress. Probiotic supplementation improved laying performance and metabolic profile. It also partially alleviated the adverse effects of stress resulting from increased caging density.

• Toxicological Research
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• 제33권1호
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• pp.43-48
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• 2017

With ultraviolet and visible light exposure, some pharmaceutical substances applied systemically or topically may cause phototoxic skin irritation. The major factor in phototoxicity is the generation of reactive oxygen species (ROS) such as singlet oxygen and superoxide anion that cause oxidative damage to DNA, lipids and proteins. Thus, measuring the generation of ROS can predict the phototoxic potential of a given substance indirectly. For this reason, a standard ROS assay (ROS assay) was developed and validated and provides an alternative method for phototoxicity evaluation. However, negative substances are over-predicted by the assay. Except for ultraviolet A (UVA), other UV ranges are not a major factor in causing phototoxicity and may lead to incorrect labeling of some non-phototoxic substances as being phototoxic in the ROS assay when using a solar simulator. A UVA stimulator is also widely used to evaluate phototoxicity in various test substances. Consequently, we identified the applicability of a UVA simulator to the ROS assay for photoreactivity. In this study, we tested 60 pharmaceutical substances including 50 phototoxins and 10 non-phototoxins to predict their phototoxic potential via the ROS assay with a UVA simulator. Following the ROS protocol, all test substances were dissolved in dimethyl sulfoxide or sodium phosphate buffer. The final concentration of the test solutions in the reaction mixture was 20 to $200{\mu}M$. The exposure was with $2.0{\sim}2.2mW/cm^2$ irradiance and optimization for a relevant dose of UVA was performed. The generation of ROS was compared before and after UVA exposure and was measured by a microplate spectrophotometer. Sensitivity and specificity values were 85.7% and 100.0% respectively, and the accuracy was 88.1%. From this analysis, the ROS assay with a UVA simulator is suitable for testing the photoreactivity and estimating the phototoxic potential of various test pharmaceutical substances.