• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.243-249
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• 2013

In waste repository environment, we can process the waste history efficiently for reuse by recording the history trajectory of the vehicle which loaded waste and the dumping position of the waste vehicle. By mapping the unloaded waste to 3D and by extracting the dumping point, a new method was implemented so as to record the final dumping position and the waste content under various experiments. In this paper, we developed the algorithm which tracking the vehicle and deciding the moment of dumping in landfills. We first trace the position of vehicle using the difference image between current image and background image and then we decide the stop point from the shape of vehicle route and detect the dumping point by comparing the dumping image with the image that vehicle is stopping. From the camera parameters, The transform method between screen coordinate and real coordinate of landfills is proposed.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.227-233
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• 2005

Carbon nanotubes (CNT) which were grown, on the alumina substrate with a pair of comb-type Au electrodes, by plasma enhanced chemical vapor deposition have been investigated for $NO_2$ gas sensor. The electrical resistance of CNT film decreased with temperature, indicating a semiconductor type of CNT, and also the resistance of CNT sensor decreased with increasing $NO_2$ concentration. Upon exposure to $NO_2$ gas, the electrical resistance of CNT film sensor rapidly decreased within 3 minutes, and then showed a constant value after $20\~30$ minutes. It is found that the sensitivity of CNT sensor has been improved by air oxidation. The CNT sensor oxidized at $450^{\circ}C$ for 30 minutes showed higher sensitivity value than that without oxidation by $27\%$, even for a low 250 ppb $NO_2$ concentration at operating temperature of $200^{\circ}C$. But it needs a recovery time more than 20 minutes for reuse after detection of $NO_2$ gas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.506-514
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• 2008

At coverage boundaries of cellular systems including the recent WiBro standard which operate with full frequency reuse for increased spectral efficiency, interference signals from the base stations(BS) of adjacent cells degrade the receiver performance. In this paper, a detection method for multiple-antenna mobile stations(MS) is proposed for downlink performance improvement at coverage boundaries of cellular systems. For the performance verification, we obtain the probability density function(pdf) of the effective signal-to-interference and noise ratio(SINR) according to the variation of the interference signals from adjacent cells as well as the number of MS antennas, and calculate the transmission efficiency. We also verify the performance of proposed method with simulation results, to demonstrate a significant performance improvement is achieved over the maximal ratio combining(MRC) and spatial demultiplexing(SD) methods in terms of the effective SINR and the spectral efficiency.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.297-306
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• 2012

In this paper, we propose a Time Delay Traceback Scheme for the TDOA location estimation performance enhancement in NLOS environment and analyze the performance in various conditions. We place multiple readers in a square($300m{\times}300m$) searching area for reuse of received signal. Also, we use more active NLOS reader detection methode for NLOS error mitigation. when NLOS time delay 70 m, the number of the NLOS reader is 3 and the received sub-blinks number 3, proposed time delay trace-back scheme improve the RMSE about 16 m. From these results, we confirm that the proposed time delay traceback scheme is well-suited for the high precision location estimation to offer the location based service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1208-1222
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• 2014

Due to the low utilization and scarcity of frequency spectrum in current spectrum allocation methodology, cognitive radio networks (CRNs) have been proposed as a promising method to solve the problem, of which spectrum sensing is an important technology to utilize the precious spectrum resources. In order to protect the primary user from being interfered, most of the related works focus only on the restriction of the missed detection probability, which may causes over-protection of the primary user. Thus the interference probability is defined and the interference-aware sensing model is introduced in this paper. The interference-aware sensing model takes the spatial conditions into consideration, and can further improve the network performance with good spectrum reuse opportunity. Meanwhile, as so many fading factors affect the spectrum channel, errors are inevitably exist in the reporting channel in cooperative sensing, which is improper to be ignored. Motivated by the above, in this paper, we study the throughput tradeoff for interference-aware cognitive radio networks over imperfect reporting channel. For the cooperative spectrum sensing, the K-out-of-N fusion rule is used. By jointly optimizing the sensing time and the parameter K value, the maximum throughput can be achieved. Theoretical analysis is given to prove the feasibility of the optimization and computer simulations also shows that the maximum throughput can be achieved when the sensing time and the parameter of K value are both optimized.

• Resources Recycling
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• v.17 no.3
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• pp.3-9
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• 2008

The measurement of physicochemical properties and chemical composition of SSA(sewage sludge ash) has been carried out and the preparation of lightweight material has also been performed using SSA for reuse as building or construction materials. For this aim, lightweight material has been prepared by forming the mixture of SSA, lightweight filler and inorganic binder followed by calcination at elevated temperature and characterized in terms of density and compressive strength. The pH of fly ash was found to be slightly alkaline, pH 8.69, due to the addition of caustic soda in order to neutralize the acidic gas while the pH of bottom ash was 6.48 Heavy metal leachability based on the standard leach test was also found to be below the detection limit for Cd, Cu, Pb, As and Cr of SSA. As far as the compressive strength of lightweight material was concerned, the compressive strength of lightweight material using fly ash was higher than that of lightweight material using bottom ash.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.357-362
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• 2016

A social network or bio network is one of the complex networks that are formed by connecting specific relationships between interacting objects. Usually, these networks consist of community structures. Automatically detecting the structures is an important technique to understand and control the interaction objects. However, the topologies and structures of the networks change by interactions of the objects, with respect to time. Conventional techniques for finding the community structure have a high computational complexity. Additionally, the methods inefficiently deal with repeated computation concerning graph operation. In this paper, we propose an incremental technique for detecting interaction-based communities in dynamic networks. The proposed technique is able to efficiently find the communities, since there is an awareness of changed objects from the previous network, and it can incrementally reuse the previous community structure.

• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.11-19
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• 2024

This paper was studied abouta technology for detecting damage to temporary works equipment used in construction sites with explainable artificial intelligence (XAI). Temporary works equipment is mostly composed of steel or aluminum, and it is reused several times due to the characters of the materials in temporary works equipment. However, it sometimes causes accidents at construction sites by using low or decreased quality of temporary works equipment because the regulation and restriction of reuse in them is not strict. Currently, safety rules such as related government laws, standards, and regulations for quality control of temporary works equipment have not been established. Additionally, the inspection results were often different according to the inspector's level of training. To overcome these limitations, a method based with AI and image processing technology was developed. In addition, it was devised by applying explainableartificial intelligence (XAI) technology so that the inspector makes more exact decision with resultsin damage detect with image analysis by the XAI which is a developed AI model for analysis of temporary works equipment. In the experiments, temporary works equipment was photographed with a 4k-quality camera, and the learned artificial intelligence model was trained with 610 labelingdata, and the accuracy was tested by analyzing the image recording data of temporary works equipment. As a result, the accuracy of damage detect by the XAI was 95.0% for the training dataset, 92.0% for the validation dataset, and 90.0% for the test dataset. This was shown aboutthe reliability of the performance of the developed artificial intelligence. It was verified for usability of explainable artificial intelligence to detect damage in temporary works equipment by the experiments. However, to improve the level of commercial software, the XAI need to be trained more by real data set and the ability to detect damage has to be kept or increased when the real data set is applied.

• Journal of Environmental Impact Assessment
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• v.22 no.2
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• pp.135-145
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• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.545-552
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• 1991

A mercury ion-sensitive carbon-paste electrode (CPE) was constructed with l-sparteine. Mercury (II) ion was chemically deposited by the complexation with l-sparteine onto the CPE. The surface of CPEs was characterized by cyclic voltammetry and anodic stripping voltammetry in an acetate buffer solution, separately. Exposure of CPEs to acid solution could regenerate surface and reuse it for deposition. In 5 deposition/measurement/regeneration cycle, the response was reproducible and in licnear up to $2.0\;{\times}\;10^{-6}$ M with linear sweep voltammetry. In case of using the differential pulse technique, we have obtained the linear response up to $7.0 {\times}10^{-7}$ M with relative standard deviation of ${\pm}5.1$%. The detection limit was $5.0{\times}10^{-7}$ M for 20 minutes of the deposition. We have investigated the interference effect of various metal ions, which are expected to form the complex with ligand. Silver (I) ion of these has interfered with the analysis of Hg (II) ions. However, pretreatment of the silver (I) ion with potassium chloride led to no interference on the analysis of mercury ions in aqueous solution.