• Journal of Energy Engineering
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• v.26 no.3
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• pp.131-136
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• 2017

Automobile engine oil is the most important lubricant for operating as the engine is started. Recently, manufacturers of the automotive industry and lubricants are considerably improving the quality of oil with additive to extend change cycle period. Most customers are recommended genuine oil among different types from shop expert. Through this report we suggest another reference point for consumer to pick highly efficient lubricant. This report is investigated oil compounds to compare with 6 different automotive considering actual running condition for 7 months. we conducted experiment from physical and chemical perspectives. In the field, through various experiments oil compounds between mineral oil and synthetic oil are largely distinguished in oxidation, viscosity, fluid and TBN. These are influenced by engine part wear as piston, bearing etc. Comparing various investigation with different oil the performance of synthetic oil is shown better condition in flash point, oxidation stability and also found less in change pollutant iron, Al compounds. Additives of oil show clear difference Ca level in detergent-dispersant both mineral oil and synthetic oil. And Zn in extreme pressure additives and P in Lubricity improver make no difference to both.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.514-519
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• 2020

Graphite materials for lithium ion battery anode materials are the most commercially available due to their structural stability and low price. Recently, research efforts have been conducted on carbon coatings by improving side reactions at the edge site of carbon materials. The carbon coating process has classified into a CVD by chemical reaction, wet coating process with solvent and dry coating by mechanical impact. In this paper, the rapid crush/coating process was used to solve the problem of which only few parts of the carbon precursor (pitch) can be used and also environmental problems caused by solvent removal in the wet coating process. When the ratio of needle coke to pitch was 8 : 2 wt%, and the rapid crush/coating process was carried out, it was confirmed that the fracture surface was coated by pitch. The pitch-coated sample was treated at 2400 ℃ and 41.8% improvement in 10C/0.1C rate characteristic was observed. It is considered that the material simply manufactured through the simple crush/coating process can be used as an anode electrode material for a lithium ion battery.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.4
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• pp.162-168
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• 2014

The OFDM system have been widely studied for the purpose of increasing data rate with more reliable communications in underwater channel environments. And it is possible only when the sub-carrier's bandwidth is smaller than the coherence bandwidth of channel in the underwater OFDM communication system. However, the size of the FFT for the OFDM system will be increased because the coherence bandwidth is as small as several tens of Hz in real underwater channel environments. Also, It is necessary to add a CP having a length longer than the rms delay spread of a channel. So the complexity of the system is increased and the data efficiency is reduced. Therefore, in this paper, we have studied the increase of the coherence bandwidth by adapting the beamforming technologies. To do this, we have collected data from real underwater channel environments and analyzed the coherence bandwidth when adapting the beamforming technologies. Analyzing the experimental data show that the coherence bandwidth by the beamforming technologies in underwater channel environments was greatly increased compared to that of a single sensor.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.4
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• pp.27-35
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• 2011

Multicarrier-Direct Sequence/Code Division Multiple Access(MC-DS/ CDMA) which is a combination of Orthogonal Frequency Division Multiplexing(OFDM) and DS/CDMA has been of significant interest as a means to take such advantages as bandwidth efficiency, high bit rate and robustness against multipath fading. In this paper we study a reduced-complexity multiuser detection aided multirate MC-DS/CDMA with time(T)-domain and frequency(F)-domain spreading. The one- dimensional orthogonal variable spreading factor(1D OVSF) code extracted from 2D OVSF code are used as a spreading code in T/F-domain. The proposed system will use code grouping interference cancellation(CGIC) receiver to reduce Multiuser Interference(MUI). The CGIC receiver uses code grouping by the correlation properties of 1D OVSF code and dose not requires the code information and activity of other user. The multiuser detector with CGIC receiver will be analyzed in Time- and Frequency-domain separately(jointly). The system performance is analytically derived in Additive White Gaussian Noise(AWGN) channel and we also compare the system performance between proposed system and T/F spreaded single(multi) rate multiuser MC-DS/CDMA system. In the computer simulation results, the proposed receiver of demonstrated huge performance improvement over conventional matched filter receiver.

• KSBB Journal
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• v.20 no.3
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• pp.238-243
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• 2005

Succinic acid has recently been drawing much interest as a raw material for biodegradable polymer. In this study acetic acid was removed by reactive extraction with various amines dissolved in various diluents. Distribution coefficients were determined as the kind of amines, diluents, and pHs of continuous phase. The extraction capacity increased with the polarity of diluent and the decrease of pH from the artificial binary solution. Based on the different extractability for succinic acid and acetic acid from the artificial binary solution, the removal of acetic acid from fermentation broth was investigated using various amines and diluents. In addition, the extractability and selectivity of CLA for succinic acid and acetic acid from fermentation broth were higher than that of straight solvent extraction.

• Korean Journal of Construction Engineering and Management
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• v.10 no.3
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• pp.111-121
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• 2009

Value Engineering(VE) at design phase(so-called Design-VE) becomes quite a compulsory solution for better customer satisfaction, cost reduction, higher product performance, and, eventually, insured predominance in the competition. Unlike intended, however, the customer requirement on Design-VE has not been fully reflected in reality. Furthermore, the Design-VE occasionally does not progress in regular sequence; Preparation for measuring customer requirement - Function analysis - Idea creation. Therefore, this study suggests Axiomatic Design Theory to be adopted in Design-VE process expecting that the functions required by the customer could systematically reflected in VE process. Post-occupancy Evaluation(POE) is also represented as a method to measure and arrange the customer requirements. The customer satisfaction Design-VE process creates ideas defining functions in more detailed, to reflect the concrete user requirement. This approach helps function analysis and idea creation linked closely because function and idea are developed zigzag (i.e. function - idea - function...) in being decomposed into level down. The application of the process proposed by this study will be helpful to improve the customer requirement measurement and clarify a link between functions and ideas.

• Journal of Korea Port Economic Association
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• v.35 no.4
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• pp.187-206
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• 2019

After reviewing the concept and previous studies related to green ports, this study analyzes the implications of green port policy of advanced ports in foreign countries and analyzes problems in terms of environmentally-friendly green port policy for Ulsan port, and to present sustainable green logistics establishment measures. The literature survey and Benchmarking methods are adopted as research methodology and the results are as follows. First, the pan-government climate change response management system, legislation of relevant laws, implementation of fiscal support policies, and roadmaps should be established. Second, the foundation for eco-friendly green growth should be established through the discovery of business models in conjunction with leading industries in the Southeastern Metropolitan Economic Area. Third, the Ulsan Port Greenport, such as AMP, in-port LNG propulsion ship, and ESI vessel incentive, should be built. Fourth, a low-carbon, high-efficiency sea-shuttle service shall be established through the introduction of the sea-shuttle service along the sea route. Fifth, energy self-reliant ports, including all institutions in the metropolitan Ulsan port area that have exceeded the level of Ulsan port Authority, should be built. Finally, water-type ports need to be built through the creation of coastal forests, the purification of marine water quality, and the introduction of colors to port.

• Journal of the Korean Society for Railway
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• v.17 no.2
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• pp.94-99
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• 2014

Recently, trends in new transportation system development have been primarily focused on sustainable and ecofriendly mobility solutions. The personal rapid transit (PRT) system has been considered a promising candidate in this category; its competitiveness is being improved through convergence with cutting-edge electric vehicle (EV) technologies. However, battery-powered vehicles pose difficult technical challenges in attempts to achieve reliable and efficient operation. In this study, a design approach for a solar-power assisted PRT system is presented with small-scale demonstrations aimed at circumventing challenges facing its adoption, as well as helping speed the transition to electric-powered ground transportation. From the results, it is expected that flexible photovoltaic (PV) cells will be able to supply 11% of the power required by the service equipment installed in a prototype vehicle. In particular, flexible photovoltaic (PV) cells are advantageous in terms of cost, weight, and design considerations. Most importantly, the cells' flexibility and attach-ability are expected to give them great potential for extended application in various areas.

• Geophysics and Geophysical Exploration
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• v.20 no.2
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• pp.78-87
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• 2017

For efficient data processing, trace interpolation and regularization techniques should be antecedently applied to the seismic data which were irregularly sampled with missing traces. Among many interpolation techniques, MWNI (Minimum Weighted Norm Interpolation) technique is one of the most versatile techniques and widely used to regularize seismic data because of easy extension to the high-order module and low computational cost. However, since it is difficult to interpolate spatially aliased data using this technique, model-constrained MWNI was suggested to compensate for this problem. In this paper, conventional MWNI and model-constrained MWNI modules have been developed in order to analyze their performance using synthetic data and validate the applicability to the field data. The result by using model-constrained MWNI was better in spatially aliased data. In order to verify the applicability to the field data, interpolation and regularization were performed for two field data sets, respectively. Firstly, the seismic data acquired in Ulleung Basin gas hydrate field was interpolated. Even though the data has very chaotic feature and complex structure due to the chimney, the developed module showed fairly good interpolation result. Secondly, very irregularly sampled and widely missing seismic data was regularized and the connectivity of events was quite improved. According to these experiments, we can confirm that the developed module can successfully interpolate and regularize the irregularly sampled field data.

• Journal of Korea Water Resources Association
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• v.46 no.8
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• pp.873-884
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• 2013

In Korea, the rainfall is concentrated in summer under the influence of monsoon climate. Thus, even a small climate change can be significant problems in water resources. As a result, a lot of attention has been focused on climate changes and a number of researches have been conducted in a manner commensurate with the attention to the climate change. This study is intended to forecast the changes in the flow and water quality of the Nam river resulting from the future climate changes in the Nam river basin using a watershed and water quality model. An SWAT model, as a watershed hydrologic model, was established after estimating a climate scenario using an artificial neural network method, and the established model was verified and adjusted using date from the Ministry of Environment to evaluate the applicability of the model. As a consequence, $R^2$ showed more than 0.7 in the simulation test, which satisfies the minimum required level. Results from the SWAT model and the future Namgang dam discharge calculated by HEC-ResSIM is used as input date for QUALKO. The results showed a huge variation in BOD depending on the annual flow of the river, which recorded a maximum difference of 2 mg/L between a rainy season and a dry season. It can be deduced that because rainfall and the runoff of a basin significantly account for the water quality of a river, higher water concentrations are recorded in a dry season in which the flow is not as much as that in a rainy season. It also can be said that water should be reserved in advance to secure water in the Nam river downstream for a dry season and be controlled in an effective and efficient manner to provide better water quality.