• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.277-278
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• 2009

The building that supply tidal and splash zone was constructed near Seamangeum Gate Bridge. The specimens that will be tested for maintenance of gate bridge were exposed on the tidal and splash zone, totally about 650(Fig. 1). The characteristics of strength, salt penetration profile, field application of surface repair material and section recover material will be acquired by periodical test. The program was developed to obtain optimal maintenance strategy of gate bridge as a marine concrete structure and to deposit experimental data, lab. test result, field test result, on its D/B. On this paper, we hope to introduce two years exposure data as compressive strength, the modulus of elasticity, the modulus of dynamic elasticity, field adoption of repair and recover materials. As briefly speaking the results, possion's ratio, elasticity, strength was general, but the recover materials have some problems. There was crack between concrete and recover material and delamination figures.

• Geomechanics and Engineering
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• v.9 no.3
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• pp.275-286
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• 2015

A new method is presented to recover missing deformation data of lateral walls of foundation pit when the monitoring is interrupted; the method is called Dynamic Mathematical Model - Parameter Interpolation. The deformation of lateral walls of foundation pit is mainly affected by the type of supporting structure and the situation of constraints, therefore, this paper mainly studies the two different kinds of variation law of deep horizontal displacement when the lateral walls are constrained or not, proposes two dynamic curve models of normal distribution type and logarithmic type, deals with model parameters by interpolating and obtains the parameters of missing data, then missing monitoring data could be Figured out by these parameters. Compared with the result from the common average method which is used to recover missing data, in the upper 2/3 of the inclinometer tube, the result by using this method is closer to the actual monitoring data, in the lower 1/3 part of the inclinometer tube, the result from the common average method is closer to the actual monitoring data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.472-482
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• 2019

This paper describes the stabilization of underwater TAS winch system Deploy/Recover operation performance. TAS winch installed on the stern of submarine performs to deploy/recover sensor, towing cable and rope tail which is deployed from the stern and separated from submarine itself. Also TAS winch provides transmission path of power to the sensor and data transmitting/receiving path which data are acquired from underwater environment like sound, depth and temperature. At the step of TAS winch evaluation test, sporadic standstill and rotating speed oscillation phenomenon were occurred. Winch motor provides the available torque to deploy/recover TAS and root cause analysis to the winch motor was done to find exact reason to sporadic malfunction. When winch motor was disassembled, eccentricity of rotor, slip-ring and the other composition part for winch motor were found. These might cause magnetic field distortion. To make TAS winch system more stable and block magnetic field distortion, this paper suggests methods to enhance fixing status installed in winch motor. For reliable data acquisition for TAS winch operation, the deploy/recover function of the improved type of TAS winch was verified in LBTS making similar condition with sea status. At the end of stage, improved type of TAS winch was tested on some functions not only deploy/recover function, but sustainability of TAS operation on specific velocity, steering angle of submarine in the sea trial. Improved type of TAS winch was verified in accordance with design requirement. Also, validity of suggested methods were verified by the sea trial.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.287-292
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• 2002

This paper presents a reverse engineering method for compound surfaces using vision system. A CNC machining center is used as a measuring station, which is equipped with slit beam generator and vision probe. Since obtained data using slit beam or laser scanner may have much data loss along the edge of compound surfaces, an algorithm is presented in this study to recover missing geometric data at such region. First, b-spline interpolation is applied to extract edge information of the surface, and as a next step, b-spline approximation is applied to recover the missing geometric data. Finally, b-spline skinning method is applied to regenerate the surface information. Appropriate simulation and experimental works are preformed to very the effectiveness of the proposed methods.

• Structural Monitoring and Maintenance
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• v.7 no.2
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• pp.109-124
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• 2020

Benefiting from the massive monitoring data collected by the Structural health monitoring (SHM) system, scholars can grasp the complex environmental effects and structural state during structure operation. However, the monitoring data is often missing due to sensor faults and other reasons. It is necessary to study the recovery method of missing monitoring data. Taking the structural temperature monitoring data of Nanjing Dashengguan Yangtze River Bridge as an example, the long short-term memory (LSTM) network-based recovery method for missing structural temperature data is proposed in this paper. Firstly, the prediction results of temperature data using LSTM network, support vector machine (SVM), and wavelet neural network (WNN) are compared to verify the accuracy advantage of LSTM network in predicting time series data (such as structural temperature). Secondly, the application of LSTM network in the recovery of missing structural temperature data is discussed in detail. The results show that: the LSTM network can effectively recover the missing structural temperature data; incorporating more intact sensor data as input will further improve the recovery effect of missing data; selecting the sensor data which has a higher correlation coefficient with the data we want to recover as the input can achieve higher accuracy.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.612-614
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• 1999

In order to improve the operational reliability, it is necessary to validate the measured sensor data, isolate any failed sensor and recover the failed critical measurement. This paper describes the use of estimating equation to identify failed sensors and to recover the feedback signal for control purpose when the sensor measurement is determined to be erroneous Simulation results show that the proposed sensor validation scheme can adequately identify the failed sensor and provide reasonable estimates for control purposes.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.7
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• pp.1-5
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• 1998

In this paper, recovery method with high-bitrate and low-bitrate coder was implemented in order to recover consecutive packet loss over the Internet. LPC was used as redundant audio data for recover of lost packets and RTP parcket format was modified for accommodation of redundant data. In measuring results using random packet loss rate with three redundant datra in every packet, it has shown that recovery rate was 80% in los rate of 50%. Since the processing delay for recovery of the lost packet was 200ms, this recovery method can be applied to real-time Internet sevice such as Internet phone.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.189-193
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• 1999

For a video data terminal (VDT) operator, visual strain was caused by continuous VDT operations was found id be recovered by watching the picture of virtual far point with the background of the complementary color when the treatment to recover from visual strain was carried out. When the VDT operator watches the picture of virtual far point with the condition of the complementary color stimuli on the CRT display in 60 or 120 minutes after the start of the VDT operation, the visual strain is recovered and the VDT operator is kept healthy.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.2
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• pp.93-102
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• 2013

These days digital data have become essential for digital investigation because most of the crime was occurred by using the digital devices. However, digital data is very easier to falsify or delete. If digital data was deleted, it is necessary to recover the deleted data for obtain digital evidence. Even though file carving is the most important thing to gather. digital evidence in digital forensic investigation, most of popular carving tools don't contemplate methods of selection or restoration for digital forensic investigation. The goal of this research is suggested files which can obtain useful information for digital forensic investigation and proposed new record file carving technique to be able to recover data effectively than before it.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.4
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• pp.123-128
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• 2020

As the use of digital devices is becoming more commonplace, digital forensics techniques recover data to collect physical evidence during the investigation. Among them, the file forensics technique recovers deleted files, therefore, it can recover the database by recovering all files which compose the database itself. However, if the record is deleted from the database, the modified record contents will not be restored even if the file is recovered. For this reason, the database forensics technique is required to recover deleted records. Database forensics obtains metadata from database configuration files and recovers deleted records from data files. However, record recovery is difficult if database metadata such as block size cannot be obtained from the database. In this paper, we propose three methods for obtaining block size, which is database metadata. The first method uses the maximum size of free space in the block, and the second method uses the location where the block appears. The third method improves the second method to find the block size faster. The experimental results show that three methods can correctly find the block size of three DBMSes.