• Journal of the Korea Society of Computer and Information
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• v.29 no.9
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• pp.169-177
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• 2024

Industrial Wireless Sensor Network (IWSN) is a key feature of Industrial IoT that enables industrial automation through process monitoring and control by connecting industrial equipment such as sensors, robots, and machines wirelessly, and must support the strict requirements of modern industrial environments such as real-time, reliability, and energy efficiency. To achieve these goals, IWSN uses reliable communication methods such as multipath routing, fixed redundant resource allocation, and non-contention-based scheduling. However, the issue of wasting redundant resources that are not utilized for communication degrades not only the efficiency of limited radio resources but also the energy efficiency. In this paper, we propose a scheme that utilizes reinforcement learning in communication scheduling to periodically identify unused wireless resources and reallocate them to save energy consumption of the entire industrial network. The experimental performance evaluation shows that the proposed approach achieves about 30% improvement of resource efficiency in scheduling compared to the existing method while supporting high reliability. In addition, the energy efficiency and latency are improbed by more than 21% and 38%, respectively, by reducing unnecessary communication.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.1013-1018
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• 2024

This study developed and evaluated a real-time monitoring system utilizing IoT technology to prevent disasters caused by hazardous gases in industrial settings. The developed system detects harmful gases in real-time and issues prompt alerts, achieving over 98% data accuracy and response times under 3 seconds. The system consists of sensor nodes, a central processing unit, and a user interface, monitoring the work environment and worker status in real-time through a cloud-based remote surveillance and control program. Performance evaluation results show that this system presents a new approach for effectively managing safety in industrial sites. Future developments are expected to include improvements in multi-gas detection capabilities, development of AI-based prediction models, and enhanced security measures, evolving into a more advanced monitoring system.

• Clean Technology
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• v.30 no.3
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• pp.188-194
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• 2024

This study investigates the impact of reduction temperature on the structure and performance of cobalt-manganese (CM) based catalysts in the direct hydrogenation reaction of carbon dioxide (CO₂). It was observed that at a reduction temperature of 350 ℃, these catalysts could successfully facilitate the conversion of CO₂ into long-chain hydrocarbons. This efficiency is attributed to the optimal conditions provided by the core-shell structure of the catalysts, which effectively catalyzes both the reverse water-gas shift (RWGS) and Fischer-Tropsch (FT) reactions. However, as the reduction temperature increased to 600 ℃, the effectiveness of the reaction process was hindered, and there was a shift in selectivity towards methane. This shift is due to the excessive reduction of the catalyst's outer shell, which reduces the number of RWGS sites and subsequently suppresses the production of CO. These findings highlight the importance of carefully controlling the reduction temperature in the design and optimization of cobalt-based catalysts. Maintaining a balance between the RWGS and FT reactions is crucial. This emphasizes that the reduction temperature is a key factor in efficiently generating long-chain hydrocarbons from CO₂.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.93-100
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• 2011

Maintenance of adequate soil water potential during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing the adverse effects of water stress on crop growth and development and the leaching of water below the root zone which can have adverse environmental effects. The objective of this study was to evaluate the feasibility of using a portable irrigation controller with an Watermark sensor for the cultivation of drip-irrigated vegetable crops in a greenhouse. The control capability of the irrigation controller for a soil water potential of -20 kPa was evaluated under summer conditions by cultivating 45-day-old tomato plants grown in three differently textured soils (sandy loam, loam, and loamy sands). Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30 cm depths. Even though a repeatable cycling of soil water potential occurred for the potential treatment, the lower limit of the Watermark (about 0 kPa) obtained in this study presented a limitation of using the Watermark sensor for optimal irrigation of tomato plants where -20 kPa was used as a point for triggering irrigations. This problem might be related to the slow response time and inadequate soil-sensor interface of the Watermark sensor as compared to a porous and ceramic cup-based tensiometer with a sensitive pressure transducer. In addition, the irrigation time of 50 to 60 min at each of the irrigation operation gave a rapid drop of the potential to zero, resulting in over irrigation of tomatoes. There were differences in water content among the three different soil types under the variable rate irrigation, showing a range of water contents of 16 to 24%, 17 to 28%, and 24 to 32% for loamy sand, sandy loam, and loam soils, respectively. The greatest rate increase in water content was observed in the top of 10 cm depth of sandy loam soil within almost 60 min from the start of irrigation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.312-321
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• 2003

In this paper, we implement robot which are ability to recognize obstacles and moving automatically to destination. we present two results in this paper; hardware implementation of image processing board and software implementation of visual feedback algorithm for a self-controlled robot. In the first part, the mobile robot depends on commands from a control board which is doing image processing part. We have studied the self controlled mobile robot system equipped with a CCD camera for a long time. This robot system consists of a image processing board implemented with DSPs, a stepping motor, a CCD camera. We will propose an algorithm in which commands are delivered for the robot to move in the planned path. The distance that the robot is supposed to move is calculated on the basis of the absolute coordinate and the coordinate of the target spot. And the image signal acquired by the CCD camera mounted on the robot is captured at every sampling time in order for the robot to automatically avoid the obstacle and finally to reach the destination. The image processing board consists of DSP (TMS320VC33), ADV611, SAA7111, ADV7l76A, CPLD(EPM7256ATC144), and SRAM memories. In the second part, the visual feedback control has two types of vision algorithms: obstacle avoidance and path planning. The first algorithm is cell, part of the image divided by blob analysis. We will do image preprocessing to improve the input image. This image preprocessing consists of filtering, edge detection, NOR converting, and threshold-ing. This major image processing includes labeling, segmentation, and pixel density calculation. In the second algorithm, after an image frame went through preprocessing (edge detection, converting, thresholding), the histogram is measured vertically (the y-axis direction). Then, the binary histogram of the image shows waveforms with only black and white variations. Here we use the fact that since obstacles appear as sectional diagrams as if they were walls, there is no variation in the histogram. The intensities of the line histogram are measured as vertically at intervals of 20 pixels. So, we can find uniform and nonuniform regions of the waveforms and define the period of uniform waveforms as an obstacle region. We can see that the algorithm is very useful for the robot to move avoiding obstacles.

• Journal of Animal Environmental Science
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• v.7 no.1
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• pp.1-12
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• 2001

This study was conducted to develope an automatic liquid feeder for early weaning piglets and to test the efficacy of the system. The liquid feeder consists of water heating and discharge unit, dry diet storing and discharge unit, mixing and discharge unit, mixed liquid feed-delivering unit, and the central control part which control each unit, feeding frequency and the amount of feeding. For investigating the possibility of practical use, a feeding trial was carried out using eighteen three way crossbred piglets weaned on 19 days of age for the experimental period of six weeks. Experimental diet was provided in liquid form using the automatic liquid feeder for the first three weeks and in dry form for the later three weeks. The water heating and discharge unit exactly supplied warm water by 27 $m\ell$/s, into the mixing unit. The dry diet storing and discharge unit supplied dry feed by 3.7g/s, into the mixing unit. Being compared with the standard growth rate suggested by NRC, average daily gain of the piglets during the first three weeks of liquid feeding was lower by 10%, while it was higher during three weeks of dry feeding and over the whole experimental period by 24 and 17%, respectively. Feed/gain was 1.09, 2.14 and 1.89 for the first 3 weeks, later 3 weeks, and whole period, respectively. Diarrhea was observed for three days from day 3 to day 7 after feeding liquid diet, but no pig died of it. In conclusion, a preliminary test for the newly developed an automatic liquid feeder using 19 days of age weaning piglets showed that the unit was successfully operated without any major problems. Piglets raised on a liquid diet through the unit developed grew less during the first three weeks, but their growth and feed intake were greatly improved thereafter, indicating the developed automatic liquid feeder may be practically used in swine industry.

• Journal of Internet Computing and Services
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• v.16 no.6
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• pp.89-95
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• 2015

Traditional frequent pattern mining discovers valid patterns with no smaller frequency than a user-defined minimum threshold from databases. In this framework, an enormous number of patterns may be extracted by a too low threshold, which makes result analysis difficult, and a too high one may generate no valid pattern. Setting an appropriate threshold is not an easy task since it requires the prior knowledge for its domain. Therefore, a pattern mining approach that is not based on the domain knowledge became needed due to inability of the framework to predict and control mining results precisely according to the given threshold. Top-k frequent pattern mining was proposed to solve the problem, and it mines top-k important patterns without any threshold setting. Through this method, users can find patterns from ones with the highest frequency to ones with the k-th highest frequency regardless of databases. In this paper, we provide knowledge both on frequent and top-k pattern mining. Although top-k frequent pattern mining extracts top-k significant patterns without the setting, it cannot consider both item quantities in transactions and relative importance of items in databases, and this is why the method cannot meet requirements of many real-world applications. That is, patterns with low frequency can be meaningful, and vice versa, in the applications. High utility pattern mining was proposed to reflect the characteristics of non-binary databases and requires a minimum threshold. Recently, top-k high utility pattern mining has been developed, through which users can mine the desired number of high utility patterns without the prior knowledge. In this paper, we analyze two algorithms related to top-k high utility pattern mining in detail. We also conduct various experiments for the algorithms on real datasets and study improvement point and development direction of top-k high utility pattern mining through performance analysis with respect to the experimental results.

• Journal of Intelligence and Information Systems
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• v.12 no.1
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• pp.1-15
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• 2006

In Korea, a resident registration card has various personal information such as a present address, a resident registration number, a face picture and a fingerprint. A plastic-type resident card currently used is easy to forge or alter and tricks of forgery grow to be high-degree as time goes on. So, whether a resident card is forged or not is difficult to judge by only an examination with the naked eye. This paper proposed an automatic recognition method of a resident card which recognizes a resident registration number by using a refined ART2-based RBF network newly proposed and authenticates a face picture by a template image matching method. The proposed method, first, extracts areas including a resident registration number and the date of issue from a resident card image by applying Sobel masking, median filtering and horizontal smearing operations to the image in turn. To improve the extraction of individual codes from extracted areas, the original image is binarized by using a high-frequency passing filter and CDM masking is applied to the binaried image fur making image information of individual codes better. Lastly, individual codes, which are targets of recognition, are extracted by applying 4-directional contour tracking algorithm to extracted areas in the binarized image. And this paper proposed a refined ART2-based RBF network to recognize individual codes, which applies ART2 as the loaming structure of the middle layer and dynamicaly adjusts a teaming rate in the teaming of the middle and the output layers by using a fuzzy control method to improve the performance of teaming. Also, for the precise judgement of forgey of a resident card, the proposed method supports a face authentication by using a face template database and a template image matching method. For performance evaluation of the proposed method, this paper maked metamorphoses of an original image of resident card such as a forgey of face picture, an addition of noise, variations of contrast variations of intensity and image blurring, and applied these images with original images to experiments. The results of experiment showed that the proposed method is excellent in the recognition of individual codes and the face authentication fur the automatic recognition of a resident card.

• Korean Journal of Remote Sensing
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• v.14 no.3
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• pp.213-222
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• 1998

Electro-Optical Camera(EOC) is the main payload of the KOrea Multi-Purpose SATellite(KOMPSAT) with the mission of cartography to build up a digital map of Korean territory including a Digital Terrain Elevation Map(DTEM). This instalment which comprises EOC Sensor Assembly and EOC Electronics Assembly produces the panchromatic images of 6.6 m GSD with a swath wider than 17 km by push-broom scanning and spacecraft body pointing in a visible range of wavelength, 510~730 nm. The high resolution panchromatic image is to be collected for 2 minutes during 98 minutes of orbit cycle covering about 800 km along ground track, over the mission lifetime of 3 years with the functions of programmable gain/offset and on-board image data storage. The image of 8 bit digitization, which is collected by a full reflective type F8.3 triplet without obscuration, is to be transmitted to Ground Station at a rate less than 25 Mbps. EOC was elaborated to have the performance which meets or surpasses its requirements of design phase. The spectral response, the modulation transfer function, and the uniformity of all the 2592 pixel of CCD of EOC are illustrated as they were measured for the convenience of end-user. The spectral response was measured with respect to each gain setup of EOC and this is expected to give the capability of generating more accurate panchromatic image to the users of EOC data. The modulation transfer function of EOC was measured as greater than 16 % at Nyquist frequency over the entire field of view, which exceeds its requirement of larger than 10 %. The uniformity that shows the relative response of each pixel of CCD was measured at every pixel of the Focal Plane Array of EOC and is illustrated for the data processing.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.65-75
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• 2021

Coin cell is a basic testing platform for battery research, discovering new materials and concepts, and contributing to fundamental research on next-generation batteries. Li metal batteries (LMBs) are promising since a high energy density (~500 Wh kg^-1) is deliverable far beyond Li-ion. However, Li dendrite-triggered volume fluctuation and high surface cause severe deterioration of performance. Given that such drawbacks are strongly dependent on the cell parameters and structure, such as the amount of electrolyte, Li thickness, and internal pressure, reliable Li metal coin cell testing is challenging. For the LMB-specialized coin cell testing platform, this study suggests the optimal coin cell structure that secures performance and reproducibility of LMBs under stringent conditions, such as lean electrolyte, high mass loading of NMC cathode, and thinner Li use. By controlling the cathode/anode (C/A) area ratio closer to 1.0, the inactive space was minimized, mitigating the cell degradation. The quantification and imaging of inner cell pressure elucidated that the uniformity of the pressure is a crucial matter to improving performance reliability. The LMB coin cells exhibit better cycling retention and reproducibility under higher (0.6 MPa → 2.13 MPa) and uniform (standard deviation: 0.43 → 0.16) stack pressure through the changes in internal parts and introducing a flexible polymer (PDMS) film.