• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.40-46
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• 2015

Stoichiometric combustion engine with Three-way catalyst had an advantage that can reduce the harmful emissions effectively. Fuel equivalence ratio controlled from engine is very important because Fuel equivalence ratio with high conversion efficiency was narrow. This study analyzed the conversion efficiency under whole range of operating area for to evaluate the performance of three-way catalyst. In order to identify the Optimum conversion efficiency, the conversion efficiency due to change the control value of fuel equivalence ratio was investigated. The result show that conversion efficiency of emissions(more than 95%) has discovered by means of fuel equivalence ratio control at each test condition. As engine power increases, optimal fuel equivalence ratio tended to increase linearly under operating conditions of similar exhaust gas temperature.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.440-454
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• 2020

To prevent pollution from ships, the Energy Efficiency Design Index (EEDI) is a mandatory guideline for all new ships. The Ship Energy Efficiency Management Plan (SEEMP) has also been applied by MARPOL to all existing ships. SEEMP provides the Energy Efficiency Operational Indicator (EEOI) for monitoring the operational efficiency of a ship. By monitoring the EEOI, the shipowner or operator can establish strategic plans, such as routing, hull cleaning, decommissioning, new building, etc. The key parameter in calculating EEOI is Fuel Oil Consumption (FOC). It can be measured on board while a ship is operating. This means that only the shipowner or operator can calculate the EEOI of their own ships. If the EEOI can be calculated without the actual FOC, however, then the other stakeholders, such as the shipbuilding company and Class, or others who don't have the measured FOC, can check how efficiently their ships are operating compared to other ships. In this study, we propose a method to estimate the EEOI without requiring the actual FOC. The Automatic Identification System (AIS) data, ship static data, and environment data that can be publicly obtained are used to calculate the EEOI. Since the public data are of large capacity, big data technologies, specifically Hadoop and Spark, are used. We verify the proposed method using actual data, and the result shows that the proposed method can estimate EEOI from public data without actual FOC.

• Journal of Digital Convergence
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• v.20 no.5
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• pp.375-381
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• 2022

The DEA-BCC model. And the Malmquist index have been used, from static and dynamic perspectives, to measure the eco-efficiency of 30 cities and provinces in China from 2011 to 2020. The results shows that: the average static eco-efficiency of 30 cities and provinces in China is 0.643. Differences exists all over China. While Shanghai and Beijing are ecologically efficient, other 28 cities and provinces are faced with different extents of inefficiency. There are also differences among regions, which generally show the spatial distribution pattern with high efficiency in the eastern regions while low in the western regions. The Malmquist index of eco-efficiency in total 30 cities and provinces shows a healthy growth trend, and the technological progress. Acts as its main driving force. Therefore, eastern regions should enhance the. radiation capacity, strengthen the synergy among regions, give full play to. The advantages of each regions. It is sensible to improve the eco-efficiency by means of optimizing the industrial structure, enhancing the technological level and improving eco-efficiency of China and realizing green development.

• Journal of the Korea Society of Computer and Information
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• v.28 no.9
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• pp.159-165
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• 2023

This study aims to analyze the changes in the management efficiency of public institutions in time series, and to examine the relationship with financial performance based on the results of time series changes. Specifically, we classified into upper and lower groups of financial performance based on the government's management evaluation results, and analyze how the management efficiency of each group changed in the period before the evaluation year. Based on public institutions published in public business information system, DEA(Data Envelopment Analysis) was performed for estimating management efficiency. The results are summarized as follows; First, we find that DEA of the upper group changed in the direction of increasing, but DEA of the lower group changed in the direction of decreasing. Second, we find that there is a significant positive relation between DEA and financial performance. This result means that the higher financial performance, the higher management efficiency. These findings imply that management efficiency can be a factor that improve financial performance in public institutions. The results also suggest that government's innovation strategies to improve financial stability by enhancing management efficiency were effective.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1096-1103
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• 1999

A study was conducted to clarify the impact of recombinant porcine somatotropin (pST) on the efficiency of absorbed nitrogen use for protein deposition in growing pigs. Three levels of dietary crude protein (9.0, 11.5, 14.0% CP) were used. Each had either a sub-optimum or near optimum lysine: CP concentration (Low-lysine, 3.8 g/100 g CP and High-lysine, 5.5 g/100g CP) in order to achieve different metabolic efficiencies for nitrogen deposition (ca. 45 vs. 60%). Twelve crossbred female pigs $(59{\pm}4kg\;BW)$ were placed in metabolism cages and fitted with bladder catheters. Each pig received an excipient injection daily for the first 10-d, a pST (5 mg/d) injection for the second 10-d, and then excipient for the last 10-d. Pigs were randomly assigned to one of six dietary treatments (2 pigs/diet) and fed 4 times per d at $92g/kg\;BW^{0.75}$ $(3{\times}maintenance)$. Means for the excipient period were compared to means for the pST period. Urinary nitrogen (N) output declined in pST-treated pigs (p<0.01) irrespective of dietary protein content or lysine level. Nitrogen retention increased by an average of 11% (p<0.01) with pST treatment (726 vs. $803mg\;N/kg^{0.75}\;BW/d$). Forty-eight percent of the absorbed N was retained with Low-lysine diets, but this increased to 53% with pST injection (+11%, p<0.01). Pigs fed High-lysine diets retained 62% of absorbed N which increased to 69% with pST (+11% p<0.01). the addition of lysine improved N use by 27% (High vs. Low, p<0.01), but the effect of lysine and pST was additive (+40%). Therefore, pST improves N retention and the efficiency of apparently absorbed N use in growing pigs (>60kg). It does so with diets having the potential for either low or high efficiencies of N use (48% and 62%). More work is needed to determine if the partial efficiency of N use improves in direct proportion to pST dose since the improvement in protein deposition is a function of pST dose.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.11
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• pp.537-542
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• 2017

Aggressive driving is a major cause of car accidents. Previous studies have mainly analyzed young driver's aggressive driving tendency, yet they were only done through pure clustering or classification technique of machine learning. However, since elderly people have different driving habits due to their fragile physical conditions, it is necessary to develop a new method such as enhancing the characteristics of driving data to properly analyze aggressive driving of elderly drivers. In this study, acceleration data collected from a smartphone of a driving vehicle is analyzed by a newly proposed ECA(Enhanced Clustering method for Acceleration data) technique, coupled with a conventional clustering technique (K-means Clustering, Expectation-maximization algorithm). ECA selects high-intensity data among the data of the cluster group detected through K-means and EM in all of the subjects' data and models the characteristic data through the scaled value. Using this method, the aggressive driving data of all youth and elderly experiment participants were collected, unlike the pure clustering method. We further found that the K-means clustering has higher detection efficiency than EM method. Also, the results of K-means clustering demonstrate that a young driver has a driving strength 1.29 times higher than that of an elderly driver. In conclusion, the proposed method of our research is able to detect aggressive driving maneuvers from data of the elderly having low operating intensity. The proposed method is able to construct a customized safe driving system for the elderly driver. In the future, it will be possible to detect abnormal driving conditions and to use the collected data for early warning to drivers.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.750-757
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• 2005

The objective of this study is an understanding of the effect of inlet flow angle on the output power performance of a Francis hydraulic turbine, An optimum induced angle at the inlet of the turbine is one of the most important design parameters to have the best performance of the turbine at a given operating condition, In general. rotating speed of the turbine is varied with the change of water mass flowrate in a volute, The induced angle of the inlet water should be properly adjusted to the operating condition to have maximum energy conversion efficiency of the turbine, In this study. a numerical simulation was conducted to have detail understanding of the flow phenomenon in the flow path and output power of the model Francis turbine. The indicated power produced by the model turbine at a given operating condition was found numerically and compared to the brake power of the turbine measured by experiment at KIER. From comparison of two results, turbine efficiency or energy conversion efficiency of the model turbine was estimated. From the study, it was found that the rotating power of the turbine linearly increased with the rotating speed. It means that the higher volume flow rate supplied. the bigger torque on the turbine shaft generated. The maximum brake efficiency of the turbine is around 46$\%$ at 35 degree of induced angle. The difference between numerical and experimental output of the model turbine is defined as mechanical efficiency. The maximum mechanical efficiency of the turbine is around 93$\%$ at 25$\∼$30 degree of induced angle.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.56-59
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• 2011

The process conditions for high efficiency industrial crystalline Si solar cells with selective emitter were optimized. In the screen printed solar cells, the sheet resistance must be 50-60V/sq. because of metal contact resistance. But the low sheet resistance causes the increase of the recombination and blue response at the short wavelength. Therefore, the screen printed solar cells with homogeneous emitter have limitations of efficiency, and this means that the selective emitter must be used to improve cell efficiency. This work demonstrates the feasibility of a commercially available selective emitter process, based on screen printing and conventional diffusion process. Now, we improved cell efficiency from 18.29% to18.45% by transition of heavy emitter pattern and shallow emitter doping condition.

• Journal of Sensor Science and Technology
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• v.31 no.5
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• pp.343-347
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• 2022

Recently, the problem of global warming caused by greenhouse gases is getting serious due to the development of industry and the increase in transportation means. Accordingly, the need for a technology to reduce carbon dioxide, which accounts for most of the greenhouse gas, is increasing. Among them, a catalyst for converting carbon dioxide into fuel is being actively studied. Catalysts for reducing carbon dioxide are classified into thermal catalysts and photocatalysts. In particular, the photocatalyst has the advantage that carbon dioxide can be reduced only by irradiating ultraviolet rays at room temperature without high temperature or additional gas. TiO₂ is widely used as a photocatalyst because it is non-toxic and has high stability, but has a disadvantage of low carbon dioxide reduction efficiency. To increase the reduction efficiency, 1-propanol was used in the synthesis process. This prevents agglomeration of the catalyst and increases the specific surface area and pores of TiO₂, thereby increasing the surface area in contact with carbon dioxide. As a result of measuring the CO₂ reduction efficiency, it was confirmed that the efficiency of TiO₂ with 1-propanol and TiO₂ without 1-propanol was 19% and 12.3%, respectively, and the former showed a 1.5 times improved efficiency.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1754-1759
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• 2011

The purpose of this paper is to provide basic information on how to make better policies that improves efficiencies of urban railways and to derive policy directions using DEA (data envelopment analysis) model. Through this paper, I can identify whether or not the urban railway service has an excellent performance, if there are any structural problems. I analyzed the efficiency by means of measuring the technical efficiencies of Korean urban railways, these were estimated with data envelopment analysis. The inputs considered are the length of urban railway lines, the number of staff, the operating cost, the number of cars, the number of stations, and the outputs are the cars movement, the traffic of passenger, and the revenue.