• 공업화학
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• 제7권3호
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• pp.543-553
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• 1996

산소전극 촉매로서 페롭스카이트형 산화물을 사용하여 알칼리형 연료전지에서의 산소환원반응에 관하여 연구하였다. 능금산(malic acid)을 사용하여 고표면적의 페롭스카이트형 $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$(x=0.00, 0.01, 0.10, 0.20, 0.35 및 0.50) 산화물을 제조하였으며, Fe 치환량과 암모니아수 첨가량에 따른 XRD 구조와 비표면적의 변화를 고찰하여 Fe와 암모니아간에 생성되어지는 착화합물이 페롭스카이트로의 구조안정화와 비표면적 증대의 주요임을 알았다. 그리고 페롭스카이트 단일상을 얻기 위해서는 다단계 승온처리가 필요했으며, XRD 실험결과 단순 정입방체상이 형성됨을 확인하였다. $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ 산화물을 촉매로 사용한 알칼리형 연료전지용 산소전극의 산소환원반응활성을 측정하기 위하여 순환 전압-전류법, 정전압-전류법, 전류단절법 등을 이용하였다. $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ 산화물에서 Fe의 치환비가 증가함에 따라, x=0.01에서 최소, x=0.20와 0.35 사이에서 최대의 산소환원활성(전류밀도)을 보였으며, 이와 같은 경향은 표면적의 변화와 무관하였다.

• 디지털산업정보학회논문지
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• 제15권4호
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• pp.63-70
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• 2019

The subject of the simultaneous measuring system of base pattern and deposition pattern is a new research topic on a defect inspection of OLED. In this paper, we propose a new OLED inspection method that simultaneously measures standard and deposition pattern images. This method reduces unnecessary processes and tac time during OLED inspection. For an additional reduction of the tac time during pattern measurement, the ROI was configured to measure only in the designated ROI area instead of measuring the entire area of an image. During the ROI set-up, the value of effective deposition pattern area is included so that if the deposition pattern is out of the ROI zone, it would be treated as a defect before measuring the size and center point of the pattern. As a result, the tac time and inspection process could be shortened. The proposed method also could be applied to the OLED manufacturing process. Production of OLED could be increased by reducing tac time and inspection process.

• 대한원격탐사학회지
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• 제38권4호
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• pp.421-434
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• 2022

Fine particulate matter (PM2.5) has been the biggest environmental problem in Korea since the 2010s. The present study considers the value of urban forests and green infrastructure as an ecosystem service (ES) concept for PM2.5 reduction based on satellite and spatial data, with a focus on Seoul, Korea A method for the spatial ES assessment that considers social demand variables such as population and land price is suggested. First, an ES assessment based on natural environment information confirms that, while the vitality of vegetation is relatively low, the ES is high in the city center and residential areas, where the concentration of PM2.5 is high. Then, the ES assessment considering social demand (i.e., the ESS) confirms the existence of higher PM2.5 values in residential areas with high population density, and in main downtown areas. This is because the ESS of urban green infrastructure is high in areas with high land prices, high population density, and above-average PM2.5 concentrations. Further, when a future green infrastructure improvement scenario that considers the urban forest management plan is applied, the area of very high ESS is increased by 74% when the vegetation greenness of the green infrastructure in the residential area is increased by only 20%. This result suggests that green infrastructure and urban forests in the residential area should be continuously expanded and managed in order to maximize the PM2.5 reduction ES.

• 한국수자원학회논문집
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• 제54권12호
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• pp.1215-1222
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• 2021

본 연구에서는 상수관망 수리해석을 통한 폭염 저감 시설로써의 소화전 활용방안연구를 수행하였다. 소화전 설치 지점을 폭염저감을 위해 개방한다고 가정하고, 지점별 수압에 따른 살수반경을 도출하고 전체 대상구역의 살수면적에 따른 도심지 온도의 저감비율을 살수차운영에 따른 살수면적과 비교하였다. 소화전 개방에 따른 살수면적은, 상수관망 수리해석을 통해 소화전이 설치된 절점에서의 압력값을 도출한후, 압력값에 따른 살수반경 관계식을 통해 산정하였다. 제안된 방법론을 2개의 지역에 적용한 결과, 소화전에 의한 살수방법의 온도저감 효과는 절대적인 살수면적의 차이에 따라, 살수차에 의한 살수방법 대비 낮게 도출될 수 있다는 한계점을 보였다. 그러나, 소화전은 살수차와 달리 물공급양에 대한 상대적 제한이 없고 동일한 지역에 대한 지속적인 분할살수가 가능하므로 일정 구역의 살수면적이 확보될 경우 살수차 대비 상대적으로 효과성 있는 폭염저감 효과를 도출할 수 있을것으로 기대된다.

• 한국기계기술학회지
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• 제13권1호
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• pp.105-112
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• 2011

Increasing needs for light weight and high safety in modern automobiles induced the wide application of high strength steels in automotive body structures- The main difficulty in the forming of sheet metal parts with high strength steel is the large amount of springback including sidewall curl and twist in channel shaped member parts- Among these shape defects, twist occurs frequently and requires numerous reworks on the dies to compensate the shape deviation- But until now, it seems to be no effective method to reduce the twist in the forming processes- In this study, a new forming process to reduce the twist deformation during the forming of automotive structural member was suggested- This method consists of forming and restriking of embosses on the sidewall around the stretch flanging area of the part- and was applied in the forming process design of an automotive front side inner member with high strength steel- To evaluate the effectiveness of the method, springback analysis using $Pamstampa^{tm}$ was done- Through the analysis results, the suggested method was proven to be effective in twist reduction of channel shaped parts with stretch flanging area.

• 상하수도학회지
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• 제37권6호
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• pp.335-345
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• 2023

In Korea, as part of the Green New Deal project toward a carbon-neutral society, it is necessary to build a climate-resilient urban environment to green the city, space, and living infrastructure. To this end, SWMM-ING was improved and the model was modified to analyze the carbon reduction effect. In addition, I plan to select target watersheds where urbanization is rapidly progressing and evaluate runoff, non-point pollution, and carbon reduction effects to conduct cost estimation and optimal design review for domestic rainwater circulation green infrastructure. In this study, green infrastructure facilities were selected using SWMM-ING. Various scenarios were presented considering the surface area and annual cost of each green infrastructure facility, and The results show that the scenario derived through the APL2 method was selected as the optimal scenario. In this optimal scenario, a total facility area of 190,517.5 m² was applied to 7 out of 30 subwatersheds to achieve the target reduction. The target reduction amount was calculated a 23.50 % reduction in runoff and a 26.99 % reduction in pollutant load. Additionally, the annual carbon absorption was analyzed and found to be 385,521 kg/year. I aim to achieve additional carbon reduction effects by achieving the goal of reducing runoff and non-point pollution sources and analyzing annual carbon absorption. Moreover, considering the scale-up of these interventions across the basin, it is believed that an objective assessment of economic viability can be conducted.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2399-2405
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• 2014

조립식지그재그 형태의 단일거더시스템이 적용되는 경골형 교량은 비틀림에 취약한 구조이다. 특히 거더와 PHC(Pretensioned spun High strength Concrete) 말뚝의 고정 연결부는 비틀림 하중에 의한 과도한 응력이 집중되는 취약부이므로 이를 저감시키기 위한 방안이 요구된다. 본 연구에서는 연결부에 발생하는 과도한 응력을 저감시키기 위한 다양한 보강재 형식의 효율성을 수치해석적으로 평가하였다.

• KIEAE Journal
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• 제16권1호
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• pp.73-79
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• 2016

This study aimed to investigate the flood prevention effect expected from the afforestation of a large area metal roof of an industrial complex located in an area prone to floods in the rainwater outflow reduction aspect through computer simulation based on soil, which is a key element of the system. In order to conduct a more realistic simulation, the properties of the surveyed soil were generated through substantive analysis, soil texture analysis, and saxton method. A comparative performance evaluation was conducted by using soil depth and ponding depth, which are key elements of the system, as variables. The study result showed that during the heavy rainfall period, the bottom ash artificial soil had 61% rainwater outflow reduction effect, which was 11% higher than the SWMM standard sand.

• 물과 미래
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• 제10권1호
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• pp.95-100
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• 1977

The empirical area-reduction method by W.M. Borland and C.R. Miller and its revised procedure by W.T. Moody were made of fitting the area and storage curves to the Van't Hul distributions. It should be noted that the reservoir is classified into one of the four standard types on the basis of the topographical feature of the reservoir in application of the method. In other words, this method did not take into account several considerafble factors affecting the mode of sediment deposition, but only the shape of the reservoir as a governign factor. This is why the method occasionally creates ambiguity in classification and accordingly leads to unexpected mode of deposition. This paper describes a generating an formula to decide the standard classification of four types Van's Hul distributions, taking into consideration quantitatively sediment-loss percent and capacity-inflow ratio as well as the shape of the reservoirs by multiple regression analysis using the least square method to get a better fit to the design curves. The result is expressed as $Y=-1.95+55.8X_1+0.14X_2+0.12X_3$ in which the the values of Y locate the standard type I through type IV in the range from ten to forty with the interval of ten. The regression analysis was correlated well with the standard errors of estimate of around two except for the case of the type IV. This formula does not give big difference from the Borland's work in general sityation, but it demonstrates acceptable results, giving somewhat precise replys for the specific reservoirs. Its application to the Soyang Lake, one of the largest reservoirs in the country, defined clearly the type II, while the original method located it in the boundary of the type II and type III.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.591-596
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• 2000

Flow through compliant tubes with linear taper in wall thickness is numerically simulated by finite element analysis. Two models are examined: a planar two-dimensional channel, and an axisymmetric tube. For verification of the numerical method, flow through a compliant stenotic vessel is simulated and compared to existing experimental data. Computational results for an axisymmetric tube show that as cross-sectional area falls with a reduction in downstream pressure, flow rate increases and reaches a maximum when the speed index (mean velocity divided by wave speed) is near unity at the point of minimum cross-section area, indicative of wave speed flow limitation or "choking" (flow speed equals wave speed) in previous one-dimensional studies. For further reductions in downstream pressure, flow rate decreases. Cross-sectional narrowing is significant but localized. When the ratio of downstream-to-upstream wall thickness is ${\le}$ 2 the area throat is located near the downstream end; as wall taper is increased to ${\ge}$ 3 the constriction moves to the upstream end of the tube. In the planar two-dimensional channel, area reduction and flow limitation are also observed when outlet pressure is decreased. In contrast to the axisymmetric case, however, the elastic wall in the two-dimensional channel forms a smooth concave surface with the area throat located near the mid-point of the elastic wall. Though flow rate reaches a maximum and then falls, the flow does not appear to be choked.