• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.3
• /
• pp.403-410
• /
• 2020

Continuous industrial development has led to a better quality of life for everyone, even further accelerating industrial growth. Industrial development, however, has also caused environmental degradation, which is posing a serious threat to humanity. It has also encouraged the indiscriminate use of limited resources, causing resource depletion. Efficient resource management based on resource circulation is critical to saving resources. Resource circulation methods are as follows: reducing the use of resources in the manufacturing process, recycling used or reprocessed products and reusing used resources without being reprocessed, remanufacturing with end-of-life products with disassembled parts. Furthermore, remanufacturing process including cleaning, inspection, repairing, and reassembling facilitate performance level as well as new typical products. It is noteworthy that the remanufacturing of machine tools can significantly save resources because their structural parts are substantially large in size. Machine tools have served as a foundation for the manufacturing industry, which has driven Korea's industrial development. Nevertheless, a few research has been reported for remanufacturing technology with used machine tools. Relevant research of developing a remanufacturing process chart and method is prerequisite for saving the resource and environments.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.2
• /
• pp.305-313
• /
• 2002

The genetic algorithm(GA), an optimization technique based on the theory of natural selection, has proven to be relatively robust means to search for global optimum. It is converged near to the global optimum point without auxiliary information such as differentiation of function. When studying some optimization problems with continuous variables, it was found that premature saturation was reached that is no further improvement in the object function could be found over a set of iterations. Also, the general GA oscillates in the region of the new global optimum point so that the speed of convergence is decreased. This paper is to propose the concept of restarting and elitist preserving strategy as a measure to overcome this difficulty. Some benchmark examples are studied involving 3-bar truss and cantilever beam with plane stress elements. The modifications to GA improve the speed of convergence.

• Convergence Security Journal
• /
• v.20 no.2
• /
• pp.53-58
• /
• 2020

In this study, it suggests the High Availability (HA) implementation plan of building a continuous service infrastructure as a strategy ensuring availability, as the importance of availability securing corporate business continuity emerges in the knowledge and information society. However, if the reliability of the criticality assessment of information asset is not ensured, it requires assessment measures for availability that can be managed by mapping with service maintenance assessment items, which are availability criteria based on the asset criticality evaluated through the asset value matrix because it is difficult to maintain security in conjunction with the value of real assets. Therefore, this study suggests the assessment measures for availability of information assets.

• Carbon letters
• /
• v.15 no.3
• /
• pp.203-209
• /
• 2014

The adsorption of volatile organic compounds (VOCs) was carried out using an activated carbon fiber (ACF) filter in an automobile. The adsorption capacities of formaldehyde, toluene, and benzene on an ACF filter were far better than those of a polypropylene (PP) mat filter and combined (PP+activated carbon) mat filter by batch adsorption in a gas bag. In a continuous flow of air containing toluene vapor through an ACF packed bed, the breakpoint time was very long, the length of the unused bed was short, and sharp "S" -type breakthrough curve was plotted soon after breakpoint, showing a narrow mass transfer zone of toluene on the ACF. The adsorption amount of toluene on the ACF filter was proportional to the specific surface area of the ACF; however, the development of mesopores 2-5 nm in size on the ACF was very effective with regard to the adsorption of toluene. The ACF air clarifier filter is strongly recommended to remove VOCs in newly produced automobiles.

• Smart Structures and Systems
• /
• v.22 no.2
• /
• pp.231-237
• /
• 2018

A significant data problem is encountered with condition monitoring because the sensors need to measure vibration data at a continuous and sometimes high sampling rate. In this study, compressive sensing approaches for condition monitoring are proposed to demonstrate their efficiency in handling a large amount of data and to improve the damage detection capability of the current condition monitoring process. Compressive sensing is a novel sensing/sampling paradigm that takes much fewer data than traditional data sampling methods. This sensing paradigm is applied to condition monitoring with an improved machine learning algorithm in this study. For the experiments, a built-in rotating system was used, and all data were compressively sampled to obtain compressed data. The optimal signal features were then selected without the signal reconstruction process. For damage classification, we used the Variance Considered Machine, utilizing only the compressed data. The experimental results show that the proposed compressive sensing method could effectively improve the data processing speed and the accuracy of condition monitoring of rotating systems.

• Korean Journal of Ecology and Environment
• /
• v.53 no.2
• /
• pp.138-147
• /
• 2020

The Singil Stream, flowing into an artificial lake, Lake Shihwa (South Korea), experiences a strong anthropogenic pressure with continuous organic matter (OM) inputs from rural, urban, and industrial areas. In this study, we investigated suspended particulate matter (SPM) and streambed sediments collected along the Singil Stream in 2014 and 2016, by applying a dual element approach (δ¹³C and δ¹⁵N) to identify OM sources. The SPM and streambed sediment samples from the indusrial area showed higher organic carbon and nitrogen concentrations (or contents) than those from the other areas, with distinctively lower δ¹⁵N values. Accordingly, our dual element approach indicates that the industrial area was the predominant OM source influencing OM quality and thus water quality of the Singil Stream flowing into Lake Shihwa during the study periods. However, further studies are necessary to better constrain OM sources in the Singil Stream since OM sources from the industrial area appear to be complex.

• The Korean Journal of Food And Nutrition
• /
• v.31 no.4
• /
• pp.471-477
• /
• 2018

The antioxidant properties of mushroom and sea tangle extracts and mustard leaf added to Kimchi were investigated by total phenolic content, DPPH radical scavenging, ABTS anion scavenging, FRAP reducing power, and ORAC value. Total phenolic content of functional Kimchi (FK) was significantly higher than that of control Kimchi (CK). DPPH radical and ABTS anion scavenging activities of functional Kimchi were significantly higher than those of control Kimchi by 2.7 and 1.7 fold, respectively (p<0.05). Also, the FRAP reducing power and ORAC value of functional Kimchi increased compared to those of the control Kimchi by 1.6 and 1.1 fold, respectively (p<0.05). Our results suggest that functional Kimchi made by mushroom and sea tangle extracts and mustard leaf may be a potent antioxidant source and could be developed as a antioxidant functional food that may be for the effective treatment of oxidant conditions. Through continuous research and development of functional Kimchi by the use of mushroom and sea tangle extracts, it will be necessary to try to identify other functions that could be useful for preventing various diseases.

• Journal of Environmental Science International
• /
• v.23 no.1
• /
• pp.61-68
• /
• 2014

This study attempted to utilize various groundcover plants in phytoremediation, using shade plants, which often have a high shade tolerance for shade urban space. Liriope platyphylla was grown in soil containing three of heavy metals, Zn, Cd, and Pb under four different concentrations (0, 100, 250 and 500 mg/kg) to determine the heavy metal accumulation characteristics and removing from soil. Total amounts of accumulated Zn in L. platyphylla were increased in accordance with increasing elevated Zn concentrations in soil, but the difference was not significant between Zn250 and Zn500. Cd accumulation, sharply increased in Cd100 and Cd250, but was reduced in Cd500. Increased Pb concentration in soil resulted a continuous increase in the total amounts of Pb accumulated in L. platyphylla. The total content of Zn in soil decreased by almost 50% in Zn100, almost 33% in Zn250 and 20% in Zn500 through growth of L. platyphylla over a period of 7 months. In the case of Cd, the concentration in soil, was decreased with 10% in Cd100, 10% in Cd250 and 33% in Cd500 through growth of L. platyphylla over a period of 7 months. This results indicate that more Cd was removed by planting L. platyphylla, compared to Zn or Pb.

• Convergence Security Journal
• /
• v.6 no.2
• /
• pp.31-42
• /
• 2006

In this paper, we proposed an integrated infrastructure for optimal information security to resolve these kinds of problems and to implement more powerful protection. The proposed infrastructure presents a security framework, provides a functional mechanism, and implements a scheme for information security based on the design concept of integrated structures. In order to ensure effective malicious traffic blocking, this paper emphasizes that a comprehensive approach through infrastructure improvement and combination of scanning tool is the only measure for preparing against today's environment of virus infiltration. The proposed model is a measure developed at a time when a permanent technological solution to virus is yet to be developed. A performance analysis model is developed and the performance is evaluated through the case studies for the proposed methodology. The effectiveness of the infrastructure for optimal information security needs the continuous diagnostic evaluation and tuning through the users or the organizations.

• Journal of the Institute of Convergence Signal Processing
• /
• v.2 no.2
• /
• pp.68-74
• /
• 2001

A design and implementation method for the UHF-band(800MHz) variable attenuator using the 3dB coupler is proposed. The 90 degree, 3-dB Coupler is used for the variable attenuator. The principal theory for the 3-dB coupler is introduced. The 3-dB Coupler is designed by the mathematical analysis and a computer simulation tool. A PIN diode is used for the variable resistor at UHF-band. The variable attenuator using the 3-dB coupler and the PIN diode is designed and implemented. The measured results for the variable attenuator by a network analyzer show that the insertion loss is below -l0dB, and the continuous variable attenuation range is about 10dB.