• Smart Media Journal
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• v.11 no.3
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• pp.39-53
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• 2022

Cloud of Things (CoT) can provide IoT applications with unlimited storage functions and processing power supported by cloud services. However, in a centralized cloud of things, it can create a single point of failure that can lead to bottleneck problems, outages of the CoT network. In this paper, to solve the problem of centralized cloud of things and interoperate between different service domains, we propose an IoT service interoperability system using distributed fog computing and blockchain technology. Distributed fog is used to provide real-time data processing and services in fog systems located at a geographically close distance to IoT devices, and to enable service interoperability between each fog using smart contracts and distributed ledgers of the blockchain. The proposed system provides services within a region close to the distributed fog entrusted with the service from the cloud, and it is possible to access the services of other fogs without going through the cloud even between fogs. In addition, by sharing a service right token issuance information between the cloud and fog nodes using a blockchain network, the integrity of the token can be guaranteed and reliable service interoperability between fog nodes can be performed.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.97-105
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• 2017

An air-burst munition is limited in space, so there is a limit on the size of the fuze and the amount of ammunition. In order to increase a firepower to a target with limited ammunition, it is necessary to concentrate the firepower on the ground instead of the omnidirectional explosion after flying to the target. This paper explores the design and verification of a ground-detection sensor that detects the direction of the ground and determines the flight-distance of an air-burst munition using a single axis geomagnetic sensor. Prior to the design of the ground detection sensor, a geomagnetic sensor model mounted on the spinning air-burst munition is analyzed and a ground-detection algorithm by simplifying this model is designed. A high speed rotating device to simulate a rotation environment is designed and a geomagnetic sensor and a remote-recording system are fabricated to obtain geomagnetic data. The ground detection algorithm is verified by post-processing the acquired geomagnetic data. Taking miniaturization and low-power into consideration, the ground detection sensor is implemented with analog devices and the processor. The output signal of the ground detection sensor rotating at an arbitrary rotation speed of 200 Hz is connected to the LED (Light Emitting Diode) in the high speed rotating device and the ground detection sensor is verified using a high-speed camera.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.493-499
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• 2016

In this study, C-Arm equipment is being used as we intend to verify the exposure dose on the operator by the scattering rays during the operation of the C-Arm equipment and to provide an effective method of reducing the exposure dose. Exposure dose is less than the Over Tube method utilizes the C-arm equipment Under Tube the scheme, The result showed that the exposure dose on the operator decreased with a thicker shield, and as the operator moved away from the center line. Moreover, as the research time prolongated, the exposure dose increased, and among the three affixed location of the dosimeter, the most exposure dose was measured at gonadal, then followed by chest and thyroid. However, in consideration of the relationship between the operator and the patient, the distance cannot be increased infinitely and the research time cannot be decreased infinitely in order to reduce the exposure dose. Therefore, by changing the thickness of the radiation shield, the exposure dose on the operator was able to be reduced. If you are using a C-Arm equipment discomfort during surgery because the grounds that the procedure is neglected and close to the dose of radiation shielding made can only increase. Because a separate control room cannot be used for the C-Arm equipment due to its characteristic, the exposure dose on the operator needs to be reduced by reinforcing the shield through an appropriate thickness of radiation shield devices, such as apron, etc. during a treatment.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.10
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• pp.473-478
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• 2017

Drones require altitude holding in order to achieve flight objectives. The altitude holding of the drone is to repeat the operation of raising or lowering the drone according to the altitude information being measured in real-time. When the drones are maintained altitude, the drone's altitude will continue to change due to external factors such as imbalance in thrust due to difference in motor speed or wind. Therefore, in order to maintain the altitude of drone, we have to exactly measure the continuously changing altitude of the drone. Generally, the acceleration sensor is used for measuring the height of the drones. In this method, there is a problem that the measured value due to the integration error accumulates, and the drone's vibration is recognized by the altitude change. To solve the difficulty of the altitude measurement, commercial drones and existing studies are used for altitude measurement together with acceleration sensors by adding other sensors. However, most of the additional sensors have a limitation on the measurement distance and when the sensors are used together, the calculation processing of the sensor values increases and the altitude measurement speed is delayed. Therefore, it is necessary to accurately measure the altitude of the drone without considering additional sensors or devices. In this paper, we propose a measurement algorithm that improves general altitude measurement method using acceleration sensor and show that accuracy of altitude holding and altitude measurement is improved as a result of applying this algorithm.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.185-192
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• 2019

The introduction of smart technology provides accuracy, safety, and efficiency to both physicians and patients. Although interest in a clear aligner is increasing among users worldwide, the current clear aligner requires a visit to the hospital every one or two weeks for replacement, which is a very cumbersome process. There is also confusion among dentists and patients because about 40 to 80 devices are made, and calibration is done based on the order and duration of the clear aligner. Therefore, this study designed and developed a clear aligner management system so that communication between the patient and dentist can be smoothly performed by inserting the QR code into the transparent correction device. As a result, the size of the QR code was recognized as $6{\ast}6mm^2$ which can be used in the oral and the recognition distance was 100% within 12 cm. Since the dentist can remotely manage the patient with the proposed system and improve the correction effect, it is possible to manage patients abroad, as well as domestically.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.576-579
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• 2011

Wireless sensor network are widely all over different fields. Because of its distinguished characteristics, we must take account of the factor of energy consumed when designing routing protocol. Wireless sensor networks consist of small battery powered devices with limited energy resources. Once deployed, the small sensor nodes are usually inaccessible to the user, and thus replacement of the energy source is not feasible. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the network. In BCDCP, all sensors sends data from the CH (Cluster Head) and then to the BS (Base Station). BCDCP works well in a smallscale network however is not preferred in a large scale network since it uses much energy for long distance wireless communication. TBRP can be used for large scale network, but it weakness lies on the fact that the nodedry out of energy easily since it uses multi-hops transmission data to the Base Station. Here, we proposed a routing protocol. A Cluster Based Energy Efficient Tree Routing Protocol (CETRP) in Wireless Sensor Networks (WSNs) to prolong network life time through the balanced energy consumption. CETRP selects Cluster Head of cluster tree shape and uses maximum two hops data transmission to the Cluster Head in every level. We show CETRP outperforms BCDCP and TBRP with several experiments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.453-459
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• 2006

This paper presents an experimental evaluation of wandering effect on asphalt concrete pavement responses. A laser-based wandering system has been developed and its performance is verified under various field conditions. The portable wandering system composed of two laser sensors with Position Sensitive Devices can allow one to measure the distance between laser sensors and tire edges of moving vehicle. Therefore, lateral position of each wheel on the pavement can be determined in a real time manner. Pavement responses due to different loading paths are investigated using a roll over test which is carried out on one of asphalt surfaced pavements in the Korea Highway Corporation test road. The pavement section (A5) consists of 5 cm thick surface course; 7 cm intermediate course; and 18 mm base course, and is heavily instrumented with strain gauges, vertical soil pressure cells and thermo-couples. From the center of wheel paths, seven equally-spaced lateral loading paths are carefully selected over an 140 cm wandering zone. Test results show that lateral horizontal strains in both surface and intermediate courses are mostly compressive right under the loading path and tensile strains start to develop as the loading offset becomes 40 cm from the wheel path. The development of the vertical stresses in the top layers of subbase and anti-frost is found to be minimal once the loading offset becomes 50 cm.

• Journal of the Korean Society for Railway
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• v.15 no.4
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• pp.364-369
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• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.2 no.1
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• pp.27-33
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• 2009

Generally, implantable microphone has been implanted in the temporal bone for implantable middle ear hearing devices (IMEHDs). In this case, the microphone's membrane can be damaged and can be generated biological noise. In order to overcome the these problems, the location of implanted microphone should be changed. As an alternative, the microphone can be implanted in the external auditory canal. However, the sound emission can be produced because of vibration transducer toward reverse direction from the tympanic membrane to the external auditory canal. In this paper, an amount of the emitted sound is measured using a probe microphone as the changing the position of microphone in the external auditory canal of a physical ear model, which is similar to acoustical and vibratory properties of the human ear. Through the measured value, the location of the microphone was assumed in the external auditory canal. According to the analysis, the microphone input sound can be decreased when microphone position become more distance from the tympanic membrane in the auditory canal. However, the external auditory canal is not appropriated to implantable microphone position, because sound emission is not completely eliminated.

• Korean Security Journal
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• no.14
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• pp.311-336
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• 2007

This study examines the concepts of counter-act against the Bio-terrorism and the reaction system in advanced countries, thereby to find out reaction system necessary to Korea. Acts on anti-Bio-terrorism is divided to detection stage, protection stage, diagnosis stage and detoxication and neutralization stage according to flow of event occurrence. As for detection stage, Korea is developing it as contact type, while advanced countries are under development of the devices that may detect the terrorism from the remote distance. It is necessary for Korea to develop the remote-distant detection system as well as the contact type of device that may promptly operate. Among the protection gears, the quality of Korea's gas mask is recognized worldwide, but that of other outfits should be improved by applying the state-of-art science technology. The diagnosis device also should be developed to the extent that the dispatched initial action team may make immediate decisions necessary in the field. As the current trends for detoxication materials worldwide require the improvement to new materials harmless to human body and equipment, Korea is also required to acquire those materials. The technology for neutralization means the development of vaccine and antibiotics and it requires the development made by shared efforts worldwide. For this purpose, it is necessary to further develop Korea's medical technology. In addition, the further efforts are required in terms of reaction manual, training model, public communication efforts and preparation for trauma syndrome.