• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1553-1560
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• 2021

We have confirmed that optimized transmittance and surface resistance by electrospinning time, also the fabricated transparent electrode composed of silver nanofiber with excellent electrical, optical and mechanical performances is showed applicability to next generation flexible displays such as solar cells, displays, and touch screens. → We have confirmed the optimized transmittance and surface resistance by electrospinning time Also the fabricated transparent electrode composed of silver nanofiber with excellent electrical, optical and mechanical performances showed applicability to next generation flexible displays such as solar cells, displays, and touch screens.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.9-14
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• 2002

A surface plasmon sensor has been fabricated for detection of concentration and refractive-index of a mixed solution. Based on the Kretschmann-Raether attenuated-total-reflection configuration, the sensor consists of 54 nm-thick Ag metal layer under a prism and a cell containing the mixed solution. We have observed a nonlinear refractive-index change as the ethanol-water concentration increased. The experimental results show us that the detection limit of the SPR sensor is 3$\times$10$^{-2}$ % in ethanol mass ratio. The concentration-to-index curve shows a linear increase in the range of ethanol concentration from 0% to 50%, but a nonlinearity is observed beyond 50%. We have modeled the nonlinearity and compared it with the experimental results.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.136-136
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• 2017

화학제염 기술은 산화제, 환원제, 금속이온, 무기산등이 혼합되어 있는 화학용액을 사용하여 원전기기 계통 내부에 생성된 고방사능 준위의 산화막과 오염물질을 제거하는 기술이다. 원전의 해체 및 유지보수에 있어 방사능 피복저감을 위한 필수적인 기술이다. 현재 원전 해체 산업은 잠재성이 높은 고부가가치 창출 산업으로 주목을 받고 있다. 원전 보유국의 경우, 기존 상용 제염기술과는 차별성 있는 제염기술을 확보하고자 노력하고 있다. 기존의 공정과 비교하여 공정비용 및 시간을 감소시킬 수 있어야 할 뿐만 아니라, 화학용액에 의한 원전 계통 금속 부품의 부식 및 손상을 최소화해야 한다. 금속 부품이 화학약품에 의한 부식손상을 받는다면 금속 부품의 수명 및 재활용 가치가 감소하기 때문에, 화학제염 기술 적용에 있어 용액에 대한 재료의 건전성 평가가 사전에 필히 이루어져야 한다. 본 연구에서는 원전 냉각재 펌프용 재료로 주로 사용되는 Stainless 304강을 시험편으로 선정하여, 화학제염 시험공정 3가지에 대한 부식손상 특성을 규명하였다. 산화공정은 과망간산($HMnO_4$) 용액을 공통으로 사용하였으며, 산화공정 종료 후 환원공정은 각 시험공정에 따라 시험공정 1은 옥살산($H_2C_2O_4$) 2000ppm, 시험공정 2는 옥살산($H_2C_2O_4$)1500ppm + 시트르산($H_8C_6O_7$)500ppm, 그리고 시험공정 3은 옥살산($H_2C_2O_4$) 3000ppm 용액을 각각 투입하여 수행하였다. 산화, 환원공정을 1Cycle로 하여, 각 시험공정 별로 총 5Cycle을 실시하였다. 각 시험공정 Cycle종료 후 시험편을 취외하여 무게감량측정, SEM(Scanning electron microscope) 분석, 3D현미경분석 그리고 타펠분극 실험을 실시하였다. 각 분석결과를 토대로 하여, Stainless 304강에 대한 화학제염 시 모델별 시험공정에 따른 부식특성을 규명하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1991.04a
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• pp.27-30
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• 1991

역삼투공정은 선택적 투과성을 가진 막을 이용하여 혼합용액으로부터 특정물질을 분리, 농축 또는 정제하기 위하여 널리 응용되는 분리막기술중의 하나이며, 연속공정이 용이하고 단순히 압력만을 가하는 물리적 조작이므로 원리 및 장치가 간단하여 해수 담수화, 폐수처리, 유용물질 회수, 초순수제조, 식품 및 의약품의 분리, 농축 등 여러 산업분야에서 응용되고 있다. 그러나 매우 큰 삼투압을 나타내는 용액의 농축을 위해서는 삼투압보다 큰 적용압력을 가해주어야 하나 사용된 막은 일정압력 이상에서는 수축되어 제기능을 발휘하지 못하게 되므로 일반적인 역삼투공정으로써는 큰 삼투압을 나타내는 용액의 농축에는 사용될 수 없다. 이는 용액의 삼투압이 씨스템에서 가해줄 수 있는 압력보다 커지기 때문으로, 이 삼투압차를 줄여줄 수 있다면 같은 압력에서도 더 큰 농축효과를 얻을 수 있다.

• Journal of The Korean Association For Science Education
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• v.36 no.2
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• pp.295-302
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• 2016

In this study, we investigated a learning progression focusing on $5^{th}$ to $9^{th}$ graders' performances with dissolution and solution concepts using the construct modeling approach. We designed a construct map describing hypothetical pathways of the concept development of dissolution and solution by analyzing both National Science Curricula and related studies. A conceptions test consisting of ordered multiple-choice items was developed and administered to 826 students. A revised construct map was derived from analyses of the results based on the partial credit model, a branch of polytomous item response theory. The sequence of dissolution and solution concepts presented in the current science curriculum was found to correspond with the learning progression of the students. However, the lower anchor, the concept of the homogeneity of particles in solution, and the factors affecting solubility were not consistent with the expected levels of the construct map. After revising the construct map, we proposed a learning progression for dissolution and solution concepts with five levels: Students of level 1 (the lower anchor) recognize the particles in the solution but misunderstand various concepts; Students of level 2 understand the homogeneity of particles in solution; Students of level 3 understand solubility and the conservation of particles during dissolution; Students of level 4 partially understand the interaction between particles; and Students of level 5 (the upper anchor) understand the interaction between particles and the factors affecting solubility.

• Journal of Food Hygiene and Safety
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• v.33 no.3
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• pp.168-175
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• 2018

The use of microwave-assisted extraction and an acid-base clean-up process to determine the amount of methylmercury (MeHg) in marine products was suggested in order to improve the complicated sample preparation process. The optimal conditions for microwave-assisted extraction was developed by using a 10% NaCl solution as an extraction solution, setting the extraction temperature at $50^{\circ}C$, and holding for 15 minutes to extract the MeHg in marine products. A NaOH solution was selected as a clean-up substitute instead of L-cysteine solution. Overall, 670 samples of marine products were analyzed for total mercury (Hg). Detection levels were in the range of $0.0006{\sim}0.3801{\mu}g/kg$. MeHg was analyzed and compared using the current food code and the proposed method for 49 samples which contained above 0.1 mg/kg of Hg. Detection ranges of methylmercury followed by the Korea Food Code and the proposed method were $75.25(ND{\sim}516.93){\mu}g/kg$ and $142.07(100.14{\sim}244.55){\mu}g/kg$, respectively. The total analytical time of proposed method was reduced by more than 25% compared with the current food code method.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.255-262
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• 1996

The donor pool for heart transplants is severely limited and there is still a legal problem of brain death. This study assessed the function of hearts "absolute anoxic" for ten minutes after asphyxia by perfusing the hearts on a Langendorfr apparatus for 45 minutes with Krebs-Henseleit buffier at 37 t at 80 cm H2O. Forty isolated rat hearts were divided into four groups. Ten control hearts (group 1) were perfused on the circuit without intervening ischemia. Ten hearts (group 2) were harvested, quickly flushed with 5cc of cold University of Wisconsin solution, and stored in the same cold solution for 4 hours. Ten hearts (group 3) were excised, quickly flushed with 5 u of cold Stanford cardioplegic solution and stored in cold saline solution for 4 hours. Ten asphyxiated hearts (group 4) had warm ischemia for ten minutes and were perfused with 5u of cold Stanford cardioplegia containing 7,500 units of urokinase to dissolve intravascular clots, and stored in cold saline solution for 1.5 hours. Time of spontaneous defibrillation (TSD) after perfusion was significantly longer in group 2, group 3 and group 4 than in group 1. TSD in group 3 and group 4 was significantly longer in comparison to that of group 2. Left ventricular developed pressure(LVDP) at 15 minutes was significantly lower in group 3 and group 4 than in group 1 and group 2. In group 4, LVDP at 30 minutes and 45 minutes was significantly lower compared with that in group 1 . In conclusion, asphyxiated rat hear;ts which had absolute anoxia for 10 minutes after as hyxia showed relatively satisfactory cardiac function. function.

• Resources Recycling
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• v.7 no.3
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• pp.17-26
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• 1998

A study on the recovery of silver and nitric acid in the liquid waste resulted from the mediated electrochemical oxidation(MEO) process was conducted. The removal of silver in the concentrated nitric acid solutions was carried out by the electrodeposition. The removal efficiency more than 98% could be obtained in nitric acid concentrations less than 3 M with the current efficiency of nearly 100%. The experimonts on the evaporation for the recovery of nitric acid were performed as well. At the evaporation factor of 25., the degree of nitric acid recovery in 3.5 M nitric acid solution containing 0.5 to 1.0 mol% NaNO, was 80~90% resulting in 2.8~3.1 M nitric acid. The design factors and operating conditions of the distillation tower were analyzed by using MEH model derived by Maphtali-Sandholm with the throughput of 4 kg/hr for the enrichment of dilute nitric acid solution recovered by evaporation to reuse in the MEO process. The distillation column composed of eleven theoretical stages having the overall tray efficiency of 70% are needed to obtain 1.03 kg/h of 12M nitric acid and 2.97 kg/h of water with feed being introduced to the column at tray 6 from the bottom at the reflux ratio of 0.25, the reboiler with the heat load of 2.7 kW, and the condenser with the cooling load of 0.5 kW.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.10a
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• pp.65-66
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• 2008

은나노 콜로이드를 플라즈마 처리 한 PET 직물과 플라즈마 처리를 하지 않은 PET 직물에 적용시킨 후 항균성을 측정하였다. 플라즈마 처리 PET에 은나노가 잘 부착되었으며, 항균성 또한 우수하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.117-118
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• 2013

증기발생기 화학세정 모사 장치를 이용하여 고농도 화학세정(EPRI/SGOG) 용액인 EDTA(20%)가 인위적으로 제작한 결합 시편에 미치는 영향 평가를 수행하였다. 평가 방법은 세정 전 후 표면 산화막 성분, ECT 분석값 비교, 증기발생기 구성 재료 부식률를 이용하였다. 화학세정 전후 부식률은 A508은 $8.023{\mu}m$, Alloy 600(HTMA)은 $0.007{\mu}m$이며 갈바닉 시편의 경우 $63.193{\mu}m$로 모두 부식 허용치 이내이다. 표면 산화막 성분 및 ECT 분석값 역시 변함이 없었다. 이와 같은 결과로 화학세정 용액인 EDTA는 결함 튜브에 미치는 영향이 없는 것으로 판단된다.