• 한국분말재료학회지
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• 제21권2호
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• pp.119-123
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• 2014

Pt has been widely used as catalyst for fuel cell and exhausted gas clean systems due to its high catalytic activity. Recently, there have been researches on fabricating composite materials of Pt as a method of reducing the amount of Pt due to its high price. One of the approaches for saving Pt used as catalyst is a core shell structure consisting of Pt layer on the core of the non-noble metal. In this study, the synthesis of Pt shell was conducted on the surface of $TiO_2$ particle, a non-noble material, by applying ultraviolet (UV) irradiation. Anatase $TiO_2$ particles with the average size of 20~30 nm were immersed in the ethanol dissolved with Pt precursor of $H_2PtCl_6{\cdot}6H_2O$ and exposed to UV irradiation with the wavelength of 365 nm. It was confirmed that Pt nano-particles were formed on the surface of $TiO_2$ particles by photochemical reduction of Pt ion from the solution. The morphology of the synthesized Pt@$TiO_2$ nano-composite was examined by TEM (Transmission Electron Microscopy).

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권4호
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• pp.210-220
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• 2002

We analysised the effect of harmonics on electric machines of substation power system barred on quantitatively measured harmonics and proposed the methods for prevention of harmonics through checking on transformer, rectifier and cable's capacities against harmonics with reference to KEPCO's electricity service standard. In order to analysis harmoninics of silicon rectifier that is power source in DC substation, computer simulations for a substation with TR of high voltage distribution switchboard are performed. Simulation results show that the total harmonic distortion factor becomes smaller for TR primary and receiving points in order rather than silicon rectifier which is harmonic generation source so that the harmonics generated frets each rectifier are outflowed to power supply and high voltage distribution switchboard The result of higher distortion factors of voltage and current for rectifier with 100% load than those with 50 % and 30% indicates that the waveform of voltage and current for the real substation power system at the office-going and the closing hours with heavy loads might be more distorted. As proposed methods for harmonic reduction, the conventional 6 pulse-type for substation is required to be replaced by 12 pulse-type for reduction of 5th and 7th harmonics. The active filter rather than the passive filter is more effective due to severe variance of rectifier loads, but the high cost is price to be paid. In view of installation area and costs, the use of 12 pulse-type transformer is desirable and then the parallel transformer and the rectifier within the substation must be replaced at the same time. Other substations with parallel feeder can use 6 pulse-type transformer.

• 한국식품영양학회지
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• 제31권5호
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• pp.729-736
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• 2018

This study was performed to facilitate development of new food materials by comparing general components, functional components and antioxidant activity of cherry, aronia, and maquiberry. Cherry revealed higher content of water (6.71%), crude protein (4.61%) and crude protein (5.33%) than aronia and maquiberry. Crude fat content of cherry fruits was the lowest at 1.46%. Content of iron per 100 g was 0.96 mg in cherry, significantly higher than other berries. Total phenolic content of cherry, aronia and maquiberry was 31.32~95.05 GAE mg/g. Total flavonoid content in water extract was 2.07 QE mg/g in cherry, compared with aronia and maquiberry. FRAP reduction power of cherry, aronia and maquiberry was $86.94{\sim}331.83TEAC\;{\mu}mol/g$. FRAP reduction power ($156.50TEAC\;{\mu}mol/g$) of cherry was higher than that of aronia ($121.72TEAC\;{\mu}mol/g$) at $95^{\circ}C$ deionized water extract. In the case of water extract, $117.00TEAC\;{\mu}mol/g$, and cherry was higher in ABTS radical scavenging ability than aronia ($86.55{\mu}mol/g$). DPPH radical scavenging activity of cherry, aronia and maquiberry was $26.34{\sim}493.53TEAC\;{\mu}mol/g$. DPPH radical scavenging activity was lowest in cherry. In conclusion, in place of foreign expensive aronia and maquiberry, the price of cherry is low and use of cherry widely distributed has increased and is used as a material of functional food.

• 한국도로학회논문집
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• 제3권4호
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• pp.137-146
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• 2001

포장유지관리시스템에 있어서 포장표면 정보는 가장 중요한 인자 중의 하나이다. 따라서 일찍부터 선진국들은 자국의 현실에 알맞은 포장표면 조사장비와 프로그램을 개발하여 사용하고 있다. 국내의 경우 고가의 외국장비와 프로그램을 수입하여 사용하고 있으나 많은 문제점으로 인해 국산 장비와 포장표면 분석 프로그램 개발의 필요성이 대두되고 있다. 본 연구는 아스팔트 포장표면 분석 프로그램 개발을 위한 선행연구이다. 본 연구의 초점은 이미지프로세싱 기술을 이용한 포장표면 분석 원리를 규명하고 포장이미지의 특성 및 포장이미지의 노이즈를 효과적으로 제거하기 위한 알고리즘을 실험하는 것이다. ARAN(Automatic Road Analyser)의 균열맵을 분석 샘플로 이용하였으며, 포장이미지의 통계적인 특성, 히스토그램, FFT(Fast Fourier Transform)영상을 분석하여 일반적인 이미지에 비해 노이즈와 고주파 성분이 많고, 배경과 균열 분리가 어려운 특성을 규명하였다. 또한 노이즈 제거를 위해 다양한 필터를 적용하여 실험한 결과 마스크 크기가 3X3인 중간값 필터가 가장 효과가 좋은 것으로 나타났다.

• 한국분무공학회지
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• 제19권3호
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• pp.115-122
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• 2014

As a demand for an automobile increases, air pollution and a problem of the energy resources come to the fore in the world. Consequently, governments of every country established ordinances for green-house gas reduction and improvement of air pollution problem. Especially, as international oil price increases, engine using clean energy are being developed competitively with alternative transportation energy sources development policy as the center. Bio ethanol, one of the renewable energy produced from biomass, gained spotlight for transportation energy sources. Studies are in progress to improve fuel supply methods and combustion methods which are key features, one of the engine technologies. DI(Direct Injection), which can reduce fuel consumption rate by injecting fuel directly into the cylinder, is being studied for Green-house gas reduction and fuel economy enhancement at SI(Spark Ignition). GDI(Galoine Direct Injection) has an advantage to meet the regulations for fuel efficiency and $CO_2$ emissions. However it produces increased number of ultrafine particles, that yet received attention in the existing port-injection system, and NOX. As fuel is injected into the cylinder with high-pressure, a proper injection strategy is required by characteristics of a fuel. Especially, when alcohol type fuel is considered. In this study, we tried to get a base data bio-ethanol mixture in GDI, and combustion for optimization. We set fuel mixture rate and fuel injection pressure as parameters and took a picture with a high speed camera after gasoline-ethanol mixture fuel was injected into a constant volume combustion chamber. We figured out spraying characteristic according to parameters. Also, we determine combustion characteristics by measuring emissions and analyzing combustion.

• 산업경영시스템학회지
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• 제40권3호
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• pp.76-82
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• 2017

Recently, the material industry in the world has started appreciating the value of new materials that can overcome the limitation of steel material. In particular, new materials are expected to play a very important role in the future industry, demonstrating superior performance compared to steel in lightweight materials and ability to maintain in high temperature environments. Carbon materials have recently increased in value due to excellent physical properties such as high strength and ultra lightweight compared to steel. However, they have not overcome the limitation of productivity and price. The carbon materials are classified into various composites depending on the purpose of use and the performance required. Typical composites include carbon-glass, carbon-carbon, and carbon-plastic composites. Among them, carbon-carbon composite technology is a necessary technology in aviation and space, and can be manufactured with high investment cost and technology. In this paper, in order to find the optimal conditions to achieve productivity improvement and cost reduction of carbon material densification process, the correlation between each process parameters and results of densification is first analyzed. The main process parameters of the densification process are selected by analyzing the correlation results. And then a certain linear relationship between major process variables and density of carbon materials is derived by performing a regression analysis based on the historical production result data. Using the derived casualty, the optimal management range of major process variables is suggested. Effective process operation through optimal management of variables will have a great effect on productivity improvement and manufacturing cost reduction by shortening the lead time.

• 전기학회논문지
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• 제65권2호
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• pp.360-364
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• 2016

The rare earth output is concentrated in limited number of countries including China. Also the necessity for development of non-rare earth motor is getting signified due to the rapid increase of rare earth price and resource weaponizing policies. Non-rare earth motor is generally designed as spoke type PMSM (Permanent Magnet Synchronous Motor) in order to maximize the power density. Such spoke type PMSM has advantage in concentrating the flux but demonstrates lower efficiency compared to permanent magnet using Nd (Neodymium) permanent magnet. Therefore, applications with strong necessity for efficiency need rotor structure having improved efficiency compared to spoke type PMSM. Hence, this study suggested fan-shape type PMSM with somewhat lower power density but maximized efficiency. Fan-shape type PMSM is a rotor shape demonstrating outstanding reduction of iron loss compared to existing spoke type. Thus, this study analyzed the improvement of efficiency and reduction of loss arising from the suggested shape through parameter calculation.

• 지질동맥경화학회지
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• 제5권1호
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• pp.61-77
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• 2016

Objective: This study aims to analyze cost-effectiveness of two most-commonly used statins from the perspective of the Korean national health system. Methods: The scope of the analysis included rosuvastatin (5 mg, 10 mg, and 20 mg) and atorvastatin (10 mg, 20 mg, 40 mg, and 80 mg). Effectiveness was defined as percentage (%) and absolute (mg/dL) reductions of low-density lipoprotein cholesterol (LDL-C) from the baseline. They were derived from published randomized controlled studies for rosuvastatin and atorvastatin. Effectiveness was defined as reductions in LDL-C levels per mg dose of the drugs. The annual direct medical costs including drug acquisition costs and monitoring costs over the one-year time horizon were calculated for each alternative. The average cost-effectiveness ratios (ACERs) and incremental cost-effectiveness ratios (ICERs) for each statin dose were calculated. Results: The ACERs for all doses of rosuvastatin (5 mg, 10 mg, and 20 mg) were lower than those for all doses of atorvastatin (10 mg, 20 mg, 40 mg, and 80 mg). Rosuvastatin 10 mg was the most cost-effective statin for LDL-C reduction. In cost-effectiveness analyses for corresponding doses of rosuvastatin and atorvastatin, rosuvastatin was the superior strategy which suggests both higher effectiveness and lower costs than atorvastatin. However, we have to consider this analysis is highly influenced by current price of statins in each market. Conclusion: For reduction of LDL-C levels in Korean patients with dyslipidemia, rosuvastatin 10mg is the most cost-effective statin in the current Korean market.

• 국토계획
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• 제54권5호
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• pp.129-138
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• 2019

This study aims to empirically examine the relationship between building energy consumption and building and local factors in Seoul. Building energy issue is an important topic for low carbon and eco-friendly city development. Building physical, socio-economic and environmental factors effect to increasing or decreasing energy consumption. However, there are different characteristic in each area, and this kind of variable has a hierarchical structure. The multi-level model was used to consider the hierarchical structure of the variables. In this study, a multi-level model was applied to confirm the difference between areas. Spatial area is Seoul, Korea and the temporal scope is August, summer season. As the result, in Model 1 (Null Model), ICC is 0.817. This shows that the energy consumption differs by 8.174% due to factors at the Dong level. Model 2 (Random Intercept Model) suggests that building's physical factors and Average age, Household size and Land price in Dong level have significant effects on Building energy consumption. In Model 3 (Random Coefficient Model), random effect variables have intercepts and slopes to vary across groups. This study provides a perspective for policy makers that the building energy reduction policies to be applied for buildings should be differently applied on area. Furthermore, not only physical factors but also socio-economic and environmental factors are important when making energy reduction policy.

• 한국가금학회지
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• 제49권1호
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• pp.33-43
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• 2022

The present study was conducted to determine the effect of reduced dietary crude protein (CP) with a synthetic indispensable amino acids (AA) supplement on the growth performance, economics, and breast meat quality. A total of 450 male broilers (Ross 308) were used from the age of 7 to 28 days. On d 7, the birds were individually weighed and randomly assigned to three treatment diets with six replicate pens for each treatment in a randomized complete block design. The experimental diets were: (1) a control diet, (2) a diet with a reduction of 1% of the dietary CP with synthetic AA supplements to meet the indispensable AA requirement (OAA) of broiler chickens, and (3) a diet with a reduction of 1% of the dietary CP with synthetic Lys, Met, and Thr supplementation to exceed 5% of the indispensable AA requirement (HAA). There were no differences among the treatments on the final body weight, weight gain, and feed intake. However, the HAA diet impaired the feed conversion ratio at d 21 and during the overall feeding periods (P<0.05). The predicted total feed intake and feed price required to reached 1.5 kg BW was higher than for the birds fed the HAA diet (P<0.05). The breast meat muscle fiber cross sectional area and fiber density varied between the treatments (P<0.05). However, there were no differences in breast meat weight. In conclusion, reducing 1% of dietary CP had no adverse effects on the growth performance or breast meat yields.