• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.4
• /
• pp.115-121
• /
• 2017

A wireless sensor network is a network in which nodes equipped with sensors capable of collecting data from the real world are configured wirelessly. Because the sensor nodes are configured wirelessly, they have limited power such as batteries. If the battery of the sensor node is exhausted, the node is no longer usable. If more than a certain number of nodes die, the network will not function. There are many wireless sensor network protocols to improve energy efficiency, among which LEACH Protocol is a typical example. The LEACH protocol is a cluster-based protocol that divides sensor space into clusters and transmits and receives data between nodes. Therefore, depending on how the cluster is structured, the shape of the energy cow may decrease or increase. We compare the network lifetimes of the existing LEACH protocols and the three types of protocols that have been improved using fuzzy methods for cluster selection.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.12
• /
• pp.54-61
• /
• 2011

We propose a surveillance-alert system based on optimal placements of PDR(Pulsed Doppler Radar) sensors in USN. By using the detection information of moving target from PDR sensor and by considering the covered detection region and geographical property of the strategic area, three optimal placements of sensors are proposed. The proposed placement are named as the grid type, the linear type and the zigzag type. Also, the surveillance alert system based on three sensor placements are developed. The alert level of the proposed surveillance-alert system are 'Perception', 'Caution', 'Warning' and 'Danger' which are decided by the distance change between the moving targets and the command post. The performace of the developed system is verified via outdoor experiments.

• Journal of Sensor Science and Technology
• /
• v.9 no.6
• /
• pp.424-429
• /
• 2000

A novel differential pressure sensor has been developed with silicon beams embedded in a silicone rubber membrane. The transducer is usable for most applications involving exposure to harsh media. A piezoresistive differential pressure sensor using silicone rubber membrane has been fabricated on the selectively diffused (100)-oriented n/n+/n silicon substrates by a unique silicon micro-machining technique using porous silicon etching. The pressure sensitivity is about $0.66\;{\mu}V/mmHg$ and the non-linearity is less than 0.1%.

• Fire Science and Engineering
• /
• v.28 no.2
• /
• pp.54-63
• /
• 2014

The purpose of this study is to test the adaptability of the CO sensor as a fire detector by analyzing its sensing characteristics on fire. In order to test the applicability, we designed and made a fire testing ground whose size is similar to that regulated by UL 268, carried out real fire tests suggested by UL 268, and conducted a comparison analysis on the sensing characteristics between the CO sensor and a photoelectric smoke detector by different types of fire source. The experiment result to the sensing characteristics of the CO sensor is about twice to three times faster than that of the photoelectric smoke detector, proceeding with incomplete combustion such as paper and wood fire source in the initial fire. Especially in case of wood smoldering fire, sensing characteristics of the CO sensor is very excellent.

• Journal of the Korea Society for Simulation
• /
• v.29 no.2
• /
• pp.73-81
• /
• 2020

HCCL stands for Heterogenous Container Class Library. HCCL is a library that allows heterogeneous types of data to be stored in a container as a single record and to be constructed as a list of the records to be stored in database. With HCCL, encryption/decryption can be done based on the unified data type. Recently, IoT sensor which is embedded in smartphone enables developers to provide various convenient services to users. However, it is also true that infringement of personal information may occur in the process of transmitting sensor information to API and users need to be prepared for this situation in some sense. In this study, we developed a data model that enhances existing security using SEED cryptographic algorithms while managing information of sensors based on HCCL. Due to the fact that the Android environment does not provide permission management function for sensors, this study decided whether or not to encrypt sensor information based on the user's choice so that the user can determine the creation and storage of safe data. For verification of this work, we have presented the performance evaluation by comparing with the situation of storing the sensor data in plaintext.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3421-3425
• /
• 2015

In sensor networks, sensor nodes are usually distributed to manage the networks in continuous unique area, however as by the network property nodes can be located in several areas. The data gathering of distributed nodes to several areas can be different with current continuous area. Hence, the distributed networks can be differently managed to the current continuous networks. In this paper, we describe the data gathering of sensor nodes in distributed sensor areas. It is possible that sensor nodes cannot instantly connect the mobile sink, and the node operation should be considered. The real time data sending to the instant connection scheme of mobile sink can be implemented, but the property of mobile sink should be considered for the sink connection of distributed areas. In this paper, we analyze the proposed scheme by the simulation results. The simulation results show that the overall lifetime to the periodic data gathering method is longer than the threshold method.

• Journal of the Korean Institute of Gas
• /
• v.14 no.4
• /
• pp.56-62
• /
• 2010

The purpose of this paper analyzes and investigates the failure case studies of electronic control sensors for a LP gas engine. The malfunction of crank angle sensor, which controls a fuel injection volume of LP gas, displays an irregular and non-uniform pulse wave form. The pulse form, which is related to the noise of the crank angle sensor, displays at the rectangular peak with a saw-toothed shape and is intermittently generated with a level of 2.46V noise signal. The malfunction of No. 1 TDC sensor in which is caused from the internal disorder affects to the reduction of engine power and engine stop suddenly. If the malfunction of oxygen sensor is occurred due to a wiring problem of a sensor connector, the LP gas vehicle may produce a shaking and disharmony of an engine because of no signal supply from the oxygen sensor. The air cleaner replica produces the clogging of continuous supply of fresh air. This may cause the retardation of vehicle acceleration and engine disharmony intermittently.

• Journal of Sensor Science and Technology
• /
• v.4 no.1
• /
• pp.3-8
• /
• 1995

n-ITO/p-PSL heterojunction photodetector have been fabricated on the Si wafer by using ITO(indium tin oxide) and PSL(porous silicon layer). They were anodized selectively by using silicon nitride and Ni-Cr/Au and were passivated by using ITO as well as being isolated by using mesa structure. With white light from 0 to 3000 Lux, the photocurrent varied linearly with incident light intensity. The reverse characteristics of fabricated devices were very stable up to a bias voltage of -40V and dark current density was about $40nA/mm^{2}$. When the device was exposed by Xe lamp whose wavelength range from 400nm to 1100nm, the maximum photo responsivity was about 0.6A/W between 600 and 700nm. Variation of the characteristics of fabricated devices after 5 weeks was negligible.

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.1
• /
• pp.33-41
• /
• 2011

To substitute TLS in the hybrid system which is combined with Sagnac interferometer and fiber bragg grating (FBG) it is necessary to investigate how the laser source (TLS and CW) and sensor material variate the response of fiber optic sensor. Two different hollow cylinder type mandrel materials are proposed which are PTFE and PTFE+carbon and 18 m optical fiber is wounded at the mandrel surface. CW laser source experiments had been done in the oil tank which is filled with transformer oil in the 1 kHz~20 kHz frequency range. Also Sagnac interferometer fiber optic sensor is combined with FBG called hybrid system and TLS used as a light source. Based on the experimental results PTFE sensor showed more higher magnitude of detection signal rather than carbon sensor and this result is agreement with the McMahon's theoretical results. Phase variation is inversely proportional to the elastic modulus of the mandrel material. In PTFE fiber sensor, tunable laser source showed more higher performance rather than CW case. Therefore, TLS fiber optic sensor can be applied to the hybrid system which is combined with Sagnac and FBG.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.6
• /
• pp.143-153
• /
• 2011

The goal of Ubiquitous Sensor Network(USN) environments is to provide users high quality services based on a variety of sensors. In this environment, sensor devices, sensor nodes and sensor networks are heterogeneous and have various characteristics. Therefore it is important for interoperability to define a metadata for describing USN resources. The OGC(Open Geospatial Consortium) proposes SensorML(Sensor Model Language) as a standard language for modeling sensors. However, SensorML provides a framework for describing a processing model among sensors rather than describing information of sensors. Therefore, to describe a USN metadata is not main purposes of SensorML. This paper defines a USN metadata which describes information about sensor device, sensor node, and sensor network. Also the paper proposes a method for efficiently storing and searching the USN metadata and implements a USN metadata management system based on our method. We show that our metadata management system is reasonable for managing the USN metadata through performance evaluation. Our USN metadata keeps the interoperability in USN environments because the metadata is designed on SensorML. The USN metadata management system can be used directly for a USN middleware or USN application.