• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.414-421
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• 2024

In this paper, we design and verify a system that can detect piping leakage noise in an environment with significant reverberation and reflection using a multi-channel acoustic sensor module as a technology to prevent major plant accidents caused by leakage. Four-channel microphones arranged in a tetrahedron are designed as a single sensor module to measure three-dimensional sound intensity vectors. In an environment with large effects of reverberation and reflection, the measurement error of each sensor module increases on average, so after placing multiple sensor modules in the field, measurement results showing locations with large errors due to effects such as reflection are excluded. Using the intersection between three-dimensional vectors obtained from several pairs of sensor modules, the coordinates where the sound source is located are estimated, and outliers (e.g., positions estimated to be outside the site, positions estimated to be far from the average position) are detected and excluded among the points. For achieving aforementioned goal, an excluding algorithm by deciding the outliers among the estimated positions was proposed. By visualizing the estimated location coordinates of the leakage sound on the site drawing within 1 second, we construct and verify a system that can detect the location of the leakage sound in real time and enable immediate response. This study is expected to contribute to improving accident response capabilities and ensuring safety in large plants.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.54-60
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• 2007

This paper proposes a built-in-self-repair (BISR) structure using 2-dimensional spare memory to effectively self-repair faults of an embedded memory. In case of multiple faults in the same row (column) of an embedded memory, the previous method using 1-D spare column (row) memory needs the same number of spare memory columns (rows) as the number of faults to self-repair them. while the new method using 2-D spare memory needs only one spare row (column) to self-repair them. Also, the virtual divided memory is adopted to be able to self-repair using not a full spare column memory but the only partial spare column memory corresponding to the faults. A self-repair circuit with $64\times1-bit$ core memory and $2\times8$ 2-D spare memory is designed. And the circuit includes a built-in-self-test block using the 13N March algorithm. The circuit has been implemented using the $0.25{\mu}m$ MagnaChip CMOS process and has $1.1\times0.7mm^2$ chip area with 10,658 transistors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• Journal of the Korean Society for information Management
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• v.33 no.1
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• pp.33-52
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• 2016

This study was to find the display considerations of RDA resource type - content type, media type, and carrier type. The Literature review, the case study, and the survey were used as the research method. 5 display strategies were suggested in this study. First, content and carrier types were better displayed than all 3 types of RDA resources. Second, two kinds of algorithm should be considered for RDA resource icon display. One was the combination of the terms of carrier types plus content types icon. The other was the combination of carrier types icon and content types icon in which the terms reflecting types must be included. Third, the subfield of 33x must be used for the paired display of content type and carrier type of multi-types resources. Fourth, in brief display, resource type icon was better positioned on the left and upper side and in detailed display, resource types were better located in description area. Fifth, 'format' was used as display indication phrase. This study would contribute to the design for the resource display by suggesting the practical display considerations of RDA resource type.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.12-19
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• 2020

The clustered heterogeneous wireless sensor network is comprised of sensor nodes and cluster heads, which are hierarchically organized for different objectives. In the network, we should especially take care of managing node resources to enhance network performance based on memory and battery capacity constraints. For instances, if some interesting events occur frequently in the vicinity of particular sensor nodes, those nodes might receive massive amounts of data. Data congestion can happen due to a memory bottleneck or link disconnection at cluster heads because the remaining memory space is filled with those data. In this paper, we utilize drones as mobile sinks to resolve data congestion and model the network, sensor nodes, and cluster heads. We also design a cost function and a congestion indicator to calculate the degree of congestion. Then we propose a data congestion map index and a data congestion mapping scheme to deploy drones at optimal points. Using control variable, we explore the relationship between the degree of congestion and the number of drones to be deployed, as well as the number of drones that must be below a certain degree of congestion and within communication range. Furthermore, we show that our algorithm outperforms previous work by a minimum of 20% in terms of memory overflow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.232-241
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• 2017

This paper presents an automated cow-feeding system based on an AGV and screw conveyor for domestic livestock farms, which are becoming larger and more commercialized. The system includes a hopper module for loading pellet-type mixed feed at the top of the system, a transfer module mounted with a screw conveyor to transfer feed from the hopper module to the outlet module, an outlet module composed of belt conveyors, and an electromagnetic guided driving-type AGV. The weight of the loaded feed is measured by a load cell located under the transfer module. The system reads the feed discharge information stored in RFID tags installed in each cowshed cell, and a predetermined amount of feed is discharged while the AGV is moving. A cow-feed test system was constructed to determine the design parameters of the screw conveyor in the transfer module that determine the feeding capacity. These parameters include the screw's outer diameter, the screw shaft outer diameter, and screw pitch. The parameters were applied to the finalized cow-feed system construction. A DSP-based main controller and cow-feeding algorithm for different scenarios were also developed to control the system. Experimental results confirmed that the system could supply a total of 21 kg of feed uniformly at 420 g/s for a cowshed cell which has 7 cows. The driving distance was 5 m and the speed was 0.1 m/s. Thus, the proposed system could be applied to standardized domestic livestock farms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.61-74
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• 2005

Digital Multimedia Broadcasting(DMB) is a reliable multi-service system for reception by mobile and portable receivers. DMB system allows interference-free reception under the conditions of multipath propagation and transmission errors using COFDM modulation scheme, simultaneously, needs powerful channel error's correction ability. Viterbi Decoder for DMB receiver uses punctured convolutional code and needs lots of computations for real-time operation. So, it is desired to design a high speed and low-power hardware scheme for Viterbi decoder. This paper proposes a combined add-compare-select(ACS) and path metric normalization(PMN) unit for computation power. The proposed PMN architecture reduces the problem of the critical path by applying fixed value for selection algorithm due to the comparison tree which has a weak point from structure with the high-speed operation. The proposed ACS uses the decomposition and the pre-computation technique for reducing the complicated degree of the adder, the comparator and multiplexer. According to a simulation result, reduction of area $3.78\%$, power consumption $12.22\%$, maximum gate delay $23.80\%$ occurred from punctured viterbi decoder for DMB system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.39-47
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• 2005

The range of hardware implementation increases in communication systems as high-speed processing is required for high data rate. In the broadband wireless access (BWA) system based on IEEE standard 802.16 the functions of higher part in the MAC layer to Provide data needed for generating MAC PDU are implemented in software, and the tasks from formatting MAC PDUs by using those data to transmitting the messages in a modem are implemented in hardware. In this paper, the interface hardware for efficient message exchange between MAC and PHY layers in the BWA system is designed. The hardware performs the following functions including those of the transmission convergence(TC) sublayer; (1) formatting TC PDU(Protocol data unit) from/to MAC PDU, (2) Reed-solomon(RS) encoding/decoding, and (3) resolving DL MAP and UL MAP, so that it controls transmission slot and uplink and downlink traffic according to the modulation scheme of burst profile. Also, it provides various control signal for PHY modem. In addition, the truncated binary exponential backoff (TBEB) algorithm is implemented in a subscriber station to avoid collision on contention-based transmission of messages. The VLSI architecture performing all these functions is implemented and verified in VHDL.

• Journal of Astronomy and Space Sciences
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• v.13 no.2
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• pp.173-180
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• 1996

This paper briefly describes the KITSAT-1 and KITSAT-2 spacecrafts and presents the functions, calibration procedures and in-orbit results of the KITSAT-2 analog sun sensors have been flown as an experimental payload for the future mission. We have two constraints in their design: small size and very low power consumption due to the tight mass and power budget of the spacecraft. Two one-dimensional analog sun sensors are mounted on the top facet of the KITSAT-2 spaceraft. Each has $\pm$60 degrees of view angle and they cover 210 degree field of view in total as the 30 degree view angles are overlapped. Only the relative sun angle around the Z-axis (yaw-axis) and the spin rate of the spacecraft can be achieved as the one dimensional sun sensors are used and they are aligned with the Z-axis. The calibration formulae are obtained using the fifth order line fitting algorithm for each sun sensor on the ground and they are applied to the obtained in-orbit data. ASS-1 with silicon solar cells has maximum error of 1.5 degree and ASS-2 with silicon photocells manufactured at KAIST has maximum error of 0.5 degree except near 0 degree of sun ray incident anagle where random reflection of incident sun ray is maximum in orbit. The results are presented in chapter 4. The performance of each sun sensor and the possible mounting errors are stated in chapter 5.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.134-140
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• 2007

The purpose of this study is to investigate the landscape image and visual preference for ridges of the Seongpanak district at Mt. Hallasan. For this, the evaluation of the artificial and natural landscape is compared through the medium of color slides. Data is analyzed through the descriptive statistics and spatial image is analyzed by factor analysis algorithm. Principle component analysis and Varimax Method are applied to extraction and factor rotation respectively. The results of this study can be summarized as follows : General visual imagesthe Seongpanak district at Mt. Hallasan are clean, beautiful and attractive. The degree of visual preference increased commensurately with the lower rate of artificial factors. Landscape Factors covering the spatial image are found to be 'aesthetic value', 'spatial scale', 'natural quality', and 'topography' factor, which account for 57.6% of the total variants. The aesthetic value variable is the most important factor in visual preference and the unnatural factors are found to present negative elements with visual preference.