• Fire Science and Engineering
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• v.34 no.1
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• pp.26-36
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• 2020

It is very difficult to suppress fire by rapid flame spread through flue space between flammable commodities on the rack when a fire occurs in the rack storage. At present, the fire protection system for rack storage in Korea has many issues, and the new fire protection system was designed and developed by it. A smart system using the sensor network and artificial intelligence was designed to detect fire very rapidly and track the location of a fire. In the very early stages, the system was constructed using vertical open sprinkler pipes, wet pipes, and solenoid valves to allow water to spray near fire locations. Based on the design results, the system was installed and tested, and the full-scale test was successfully completed.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.47-53
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• 2007

In this paper, a thermo-piezoelectric mechanism with integrated heaters and piezoelectric sensors has been studied for low power probe-based data storage. Silicon nitride cantilever integrated with silicon heater and piezoelectric sensor has been developed to improve the uniformity of cantilevers. Data bits of 40 nm in diameter were recorded on PMMA film. The sensitivity of the piezoelectric sensor was 0.615 fC/nm after poling the PZT layer. And, the $34\times34$ probe array integrated with CMOS circuits has been successfully developed by simple one-step bonding process. The process can simplify the process step and reduce tip wear using silicon nitride tip.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.93-99
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• 2015

Economic burden of work-related musculoskeletal disorder(WMDs) is increasing. Known causes of WMDs include improper posture, repetition, load, and temperature of workplace. Among them, improper postures play an important role. A smart sensor called SensorTag is employed to estimate the trunk postures including flexion-extension, lateral bend, and the trunk rotational speeds. Measuring gravitational acceleration vector in the smart sensor along the tri-orthogonal axes offers an orientation of the object with the smart sensor attached to. The smart sensor is light in weight and has small form factor, making it an ideal wearable sensor for body posture measurement. Measured data from the smart senor is wirelessly transferred for analysis to a smartphone which has enough computing power, data storage and internet-connectivity, removing need for additional hardware for data post-processing. Based on the estimated body postures, WMDs risks can be conviently gauged by using existing WMDs risk assesment methods such as OWAS, RULA, REBA, etc.

• Journal of information and communication convergence engineering
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• v.11 no.1
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• pp.12-16
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• 2013

Sensor network is one of the strongest technologies for various applications including home automation, surveillance system and monitoring system. To ensure secure and robust network communication between sensor nodes, plain-text should be encrypted using encryption methods. However due to their limited computation power and storage, it is difficult to implement public key cryptography, including elliptic curve cryptography, RSA and pairing cryptography, on sensor networks. However, recent works have shown the possibility that public key cryptography could be made available in a sensor network environment by introducing the efficient multi-precision multiplication method. The previous method suggested a broad rule of multiplication to enhance performance. However, various features of sensor motes have not been considered. For optimized implementation, unique features should be handled. In this paper, we propose a fully optimized multiplication method depending on a different specification for sensor motes. The method improves performance by using more efficient instructions and general purpose registers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3184-3189
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• 2010

To develop gasoline engine fuel pump, it is needed to measure the rotational speed of the pump. In general, because gasoline fuel pump is submerged in the fuel tank, it is difficult to measure the rotational speed directly. Currently, there are two popular methods measuring the rotational speed. One of them is using a piezoelectric accelerometer, and the other is using a current sensor. Originally, a piezoelectric accelerometer had been applied to measure the frequency of the motor vibration. A current sensor is measuring current frequency of the commutator slot. In this study, both the piezoelectric accelerometer and the current sensor have been applied on the fuel pump to calculate the rotational speed at the same time. As a result, the current sensor delivered highly accurate rotational speed information compared with that of the piezoelectric accelerometer. Especially, low rotational speed region, the current sensor shows very robust measuring characteristics. To measure the rotational speed within 1% error, the piezoelectric accelerometer needs to be set with less then 0.5Hz datum storage interval, and the current sensor needs to be set with less then 2.0Hz datum storage interval.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.816-823
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• 2010

Recently research efforts for ubiquitous technology that includes RFID(Radio Frequency Deification and sensor networks are conducted very actively The architectural framework of the USN sensor network discovery service. The survey of the USN technology is conducted on four technological visions that contain USN system technology USN networking technology and USN middleware along with the service platform, With respect to each technological division domestic and worldwide leading research projects are primarily explored with their technical features and research projects are primarily explored with their technical features and research outputs. Boasted on the result of the survey we establish a USN software model that includes data sensing, sensor data storage sensor data storage sensor data naming and sensor feed name service. This main objective of this model is to provide a reference model for the facilitation of USN application developments.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.6
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• pp.616-625
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• 2011

Ensuring the designed prestress force is very important for the safety of prestressed concrete bridge. The loss of prestress force in tendon could significantly reduce load carrying capacity of the structure. In this study, an automated prestress-loss monitoring system for prestressed concrete girder using PZT-interface and wireless impedance sensor node is presented. The following approaches are carried out to achieve the objective. Firstly, wireless impedance sensor nodes are designed for automated impedance-based monitoring technique. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Secondly, a smart PZT-interface designed for monitoring prestress force is described. A linear regression model is established to predict prestress-loss. Finally, a system of the PZT-interface interacted with the wireless sensor node is evaluated from a lab-scale tendon-anchorage connection of a prestressed concrete girder.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.843-845
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• 2011

Due to the short lifetime of the battery-based sensor network, study on the environmental energy-harvesting sensor network is being performed widely. In this paper, we analyze the system-level requirements on the sensor node which is needed for the efficient solar-powered wireless sensor network for the target application. In addition, we explain how the HW/SW components of our real solar-powered sensor node can satisfy the requirements mentioned above.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1087-1090
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• 2003

In this study, experimental procedures were suggested to investigate the sloshing behavior of a liquid storage tank subjected to inevitably external vibrating conditions. For this purpose. liquid storage tank with rectangular cross section was made of an acrylic resin for the visualization of liquid fluctuation. A specially designed vibrator was used to provide a specified vibrating condition to the liquid storage tank. Extrapolation technique was applied to determine sloshing natural frequency by using various sloshing frequencies at each vibrating displacement and liquid contents at a fixed vibrating frequency. Sloshing mode was also determined from continuous images or liquid fluctuation captured from a video camera. In addition, change in the height of the liquid free surface was measured by using a floating target and a laser displacement sensor. It is found that the suggested method can be applicable to identify the sloshing behavior of liquid storage tank with rectangular cross section.

• Korean Journal of Organic Agriculture
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• v.30 no.2
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• pp.291-302
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• 2022

Food safety is a fundamental requirement for consumers. Therefore, this study was aimed to determine the freshness of pork fillets based on freshness index (Ki value) analysis during storage. This study obtained a total of 24 pork fillets. This study was divided into 4℃ and -20℃ temperatures. Again, each temperature was divided into 4 different groups based on storage durations (15d). Each group was obtained in triplicate. The level of malondialdehyde (MDA) value was significantly increased at 4℃ than the -20℃ storage with the duration of storage days. The levels of inosine-5'-phosphate (IMP) in pork fillets were significantly decreased at 4℃ and -20℃. Hypoxanthine (Hx) levels were significantly increased at 15 days than those at 0 days during storage at both temperatures (4℃ and -20℃). Subsequent freezing increased more inosine levels at -20℃ than storage at 4℃. The Ki values were increased during storage days at both temperatures, although after 15d storage, its values at 4℃ were significantly higher than those at -20℃. These results demonstrated that storage period and temperature might affect the freshness of pork fillets via lipid oxidation and nucleotide degradation. This study suggested that the Ki value will be the crucial indicator of measurement of freshness of stored pork fillets.