• 대한기계학회논문집B
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• 제39권12호
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• pp.921-925
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• 2015

매년마다 신장질환으로 고통 받는 사람들이 증가하는 추세이다. 가장 흔한 치료법 중 하나는 혈액 투석인데, 이 방법은 많은 시간이 걸리고, 비용이 많이 드는 방법이다. 이러한 이유 때문에, 인공신장 연구의 중요성이 대두되고 있다. 혈액에서 크레아티닌을 여과하는 것은 신장의 주요 기능 중 하나이다. 우리는 이 기능에 초점을 맞춘 새로운 2 채널 마이크로 플루이딕 칩을 고안하였다. 두 개의 PDMS 층을 결합하기 위하여, 아크릴을 가공한 하우징 시스템이 개발하였으며, 이 방법은 여과막을 쉽게 바꿀 수 있다는 이점이 있다. 우리는 알루미늄 양극 산화물(AAO)을 여과막으로 사용하였다. 여과된 용액은 자페반응(Jaffe reation)을 이용하여, 크레아티닌 농도별 흡광도 차이를 분석하였다. 크레아티닌의 양에 대한 표준식을 만들어, 측정한 데이터를 보간하여 여과된 용액의 농도를 확인하였다. 실험을 통하여 유량 및 크레아티닌 농도에 따른 여과율을 얻을 수 있었다.

• Structural Engineering and Mechanics
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• 제75권4호
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• pp.477-485
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• 2020

Finite element (FE) model based structural damage detection (SDD) methods play vital roles in effectively locating and quantifying structural damages. Among these methods, structural model updating should be conducted before SDD to obtain benchmark models of real structures. However, the characteristics of updating parameters are not reasonably considered in existing studies. Inspired by the l_∞ norm regularization, a novel anti-sparse representation method is proposed for structural model updating in this study. Based on sensitivity analysis, both frequencies and mode shapes are used to define an objective function at first. Then, by adding l_∞ norm penalty, an optimization problem is established for structural model updating. As a result, the optimization problem can be solved by the fast iterative shrinkage thresholding algorithm (FISTA). Moreover, comparative studies with classical regularization strategy, i.e. the l₂ norm regularization method, are conducted as well. To intuitively illustrate the effectiveness of the proposed method, a 2-DOF spring-mass model is taken as an example in numerical simulations. The updating results show that the proposed method has a good robustness to measurement noises. Finally, to further verify the applicability of the proposed method, a six-storey aluminum alloy frame is designed and fabricated in laboratory. The added mass on each storey is taken as updating parameter. The updating results provide a good agreement with the true values, which indicates that the proposed method can effectively update the model parameters with a high accuracy.

• Structural Engineering and Mechanics
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• 제75권4호
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• pp.415-424
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• 2020

Recently, many structural damage detection (SDD) methods have been proposed to monitor the safety of structures. As an important modal parameter, mode shape has been widely used in SDD, and the difference of vectors was adopted based on sensitivity analysis and mode shapes in the existing studies. However, amplitudes of mode shapes in different measured points are relative values. Therefore, the difference of mode shapes will be influenced by their amplitudes, and the SDD results may be inaccurate. Focus on this deficiency, a multi-strategy SDD method is proposed based on the included angle of vectors and sparse regularization in this study. Firstly, inspired by modal assurance criterion (MAC), a relationship between mode shapes and changes in damage coefficients is established based on the included angle of vectors. Then, frequencies are introduced for multi-strategy SDD by a weighted coefficient. Meanwhile, sparse regularization is applied to improve the ill-posedness of the SDD problem. As a result, a novel convex optimization problem is proposed for effective SDD. To evaluate the effectiveness of the proposed method, numerical simulations in a planar truss and experimental studies in a six-story aluminum alloy frame in laboratory are conducted. The identified results indicate that the proposed method can effectively reduce the influence of noises, and it has good ability in locating structural damages and quantifying damage degrees.

• BMB Reports
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• 제34권4호
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• pp.379-384
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• 2001

The cDNA encoding ribosomal protein was identified from a cDNA library of Schizosaccharomyces pombe. The nucleotide sequence of the 548 by cDNA clone reveals an open reading frame, which encodes a putative protein of 166 amino acids with a molecular mass of 18.3 kDa. The amino acid sequence of the S. pombe L11 protein is highly homologous with those of rat and fruit, while it is clearly less similar to those of prokaryotic counterparts. The 1,044 by upstream sequence, and the region encoding N-terminal 7 amino acids of the genomic DNA were fused into the promoterless $\beta$-galactosidase gene of the shuttle vector YEp357 in order to generate the fusion plasmid pHY L11. Synthesis of $\beta$-galactosidase from the fusion plasmid varied according to the growth curve. It decreased significantly in the growth-arrested yeast cells that were treated with aluminum chloride and mercuric chloride. However, it was enhanced by treatments with cadmium chloride ($2.5\;{\mu}M$), zinc chloride ($2.5\;{\mu}M$), and hydrogen peroxide (0.5 mM). This indicates that the expression of the L,11 gene could be induced by oxidative stress.

• 한국태양에너지학회 논문집
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• 제40권1호
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• pp.49-60
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• 2020

This study reviewed selected specific windows and reviewed the window performance certification criteria including KS F 2278 and KS L 9107 and analyzed the change in performance based on the change of area. This study also compared the heating and cooling loads of an apartment house applied with window performance reviewed in consideration of insulation and SHGC performance and actual size based on KS F 2278. The analyzed window was a double window composed of aluminum and PVC and the building was the apartment house model of 141 ㎡. The analysis results were as follows. First, as the window glass's thermal performance is superior to frame, the performance degraded in reduced area. In case of selected window, the 1 m × 1m window's thermal performance and SHGC decreased by 35% and 37% respectively compared to 2 m × 2 m window. Secondly, in the comparison of performance for increasing area with 2 m × 2 m and 3 m × 3 m windows, the 3 m × 3 m window's thermal performance and SHCG increased about 14%. Third, in the comparison of heating and cooling loads of the analyzed model considering the apartment house model applied with window performance derived from KS F 2278 and actual figures, the model's total heating and cooling loads increased by 33% with cooling decreasing by 36% and heating increasing by 77%. Above analysis results show that evaluation of window performance based on criteria such as KS F 2278 and KS L 9107 may lead to distortion of performances different from actual products. Thus, it is necessary to suggest new evaluation criteria.

• 수산해양교육연구
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• 제19권1호
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• pp.129-136
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• 2007

The component parts of the shell plate of a ship are steel. but the screw propeller or the bow thruster is a compound of bronze, nickel and aluminum. On account of the these different components between metals of the shell plate, the screw propeller and the bow thruster, which are underwater, the shell plate of a ship is corroded by the action of ionization. Authors investigated the corrosion loss of the zinc anodes which were attached to the bottom shell of the training ship Kaya for about two years. The obtained results were as follows:1. In case of the shell plate the difference of the corrosion loss according to port and starboard was almost nothing. But the corrosion loss of the forward part was more than that of the aftward part.2. There was little difference in the corrosion loss between the forward and the aftward part on the bilge keel.3. The corrosion loss of the fore, midship and aft part on the false keel were 24.7%, 22.4% and 23.9% respectively.4. The corrosion loss of the fore and the aft part on the false keel was more than that of the midship part.5. The corrosion loss of the bow thruster was greater than any other parts.6. The nearer the zinc anode to the screw propeller the more the corrosion loss on the stern frame, and the situation was also same as on the rudder.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.570-573
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• 2022

본 논문에서는 신경망 모델을 적용한 몰드변압기의 보이드 결함 크기 판별에 관한 연구를 수행하였다. PCB 기반의 로고우스키 코일형 부분방전 센서를 제작하여 부분방전 신호를 측정하였고, 보이드에 의한 부분방전 결함을 모의하기 위한 PD 전극계를 제작하였다. 또한 보이드는 원통형 모양의 알루미늄 틀을 제작하여 에폭시가 경화되는 과정에서 실린지를 삽입하고 공기를 주입하여 서로다른 직경을 가지는 4개의 시편을 제작하였다. 보이드 결함 크기 판별을 위해 부분방전 전하량, 방전 펄스 수, 위상 분포의 부분방전 특성 파라미터를 추출하여 Labview 기반의 VI (Virtual Instrument)로 역전파 알고리즘을 설계하였다. 실험 결과로부터 제작된 알고리즘은 90%이상의 판별률로 결함의 직경크기를 구분할 수 있었다. 본 연구의 결과는 현장에서 PD 측정 시 몰드변압기의 유지보수 및 절연물 교체의 근거 자료로 활용될 수 있을 것으로 판단된다.

• 환경영향평가
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• 제22권2호
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• pp.135-145
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• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• 한국가스학회지
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• 제9권4호
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• pp.17-25
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• 2005

탈알루미늄 및 알칼리/알칼리토금속 양이온을 교환한 Y형 제올라이트 촉매를 제조하였다. 제조한 촉매물질의 원소조성 및 구조 변화를 ICP-AES, XRF 및 XRD와 같은 각종 분광학적 방법으로 분석하였으며, NO-TPD 실험을 통한 표면흡착종의 탈착 거동을 조사하였다. 탈알루미늄 처리 후 출발물질인 NaY보다 촉매물질의 Si/Al비는 증가하였으며, 탈알루미늄 후 Cs및 Ba양이온으로 교환한 Y형 제올라이트의 경우 Si/Al비가 부가적으로 조금 더 감소하였다. 탈알루미늄 처리한 촉매는 Al원자의 탈리로 기본골격의 파괴가 심화되어 framework (tetrahedral)구조가 감소하고 non-framework (octahedral) 구조가 증가하였다. 이러한 현상은 스팀처리시간이 많아질수록 증가하였으며 양이온을 교환한 후에는 더 크게 나타났다. NO-TPD 실험에서 탈알루미늄 및 양이온 교환 후 촉매의 활성점을 나타내는 탈착 봉우리들은 저온으로 이동하였으며, 스팀처리시간이 많아질수록 탈착 봉우리가 상대적으로 저온에서 나타났다. 탈알루미늄 및 양이온 교환을 한 Y형 제올라이트는 교환된 양이온과 탈알루미늄으로 인한 non-framework (octahedral) 구조의 생성이 촉매의 활성에 미치는 영향이 더 큰 것으로 나타났다.

• 자원리싸이클링
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• 제29권4호
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• pp.15-30
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• 2020

최근에 태양광 발전 시설이 급격히 증가됨에 따라 사용 후 태양광 모듈의 발생량이 급증할 것으로 예상된다. 태양광 폐 모듈의 리싸이클링은 일부 국가에서 시도하고 있지만, 경제성이 확보된 실용화 기술의 부재로 폐 모듈이 방치 및 폐기되어, 환경오염은 물론 유가자원 회수 측면에서도 많은 문제를 야기시키고 있으므로 대책 마련이 시급하다. 이와 같은 현실에 비추어 본 기술개발에서는 폐 모듈의 성능검사, 알루미늄 프레임 해체, 강화유리의 파분쇄 및 박리, back sheet 및 EVA의 분리 제거, 유가금속의 침출과 침전 회수 및 폐액 처리의 기반 기술을 확립한 다음, 이를 기초로 대단위 처리 시설을 설계 제작 및 운전함으로써 실용화기술을 확립하였다. 본 연구에서는 대단위 시험을 통하여 1 ton/day 규모의 폐 모듈 처리의 최적 조건을 확립한 다음, 얻어진 자료를 근거로 경제성 검토를 실시하였다. 프레임 해체 및 강화유리 박리 공정까지는 경제성이 있었으나, 유가금속 회수를 포함한 전체 공정을 포함하면 생산자 책임(EPR) 제도의 시행에 따른 재활용 분담금의 지원이 이루어지지 않는 한 경제성이 박약하였다. 향후 태양광 폐 모듈의 수거, 재사용 인증기준, 철거비 부담, 효율적인 처리 기술 확보, 관련 법규제정 및 EPR 제도 등의 문제가 해결된다면, 경제성 확보가 용이하여 상용화가 가능할 것이다.