• The KIPS Transactions:PartC
• /
• v.19C no.4
• /
• pp.239-246
• /
• 2012

The function of location estimation in WPAN has been studied and specified on the ultra wide band optionally. But the devices based on CSS(Chirp Spread Spectrum) specification has been used widely in the market because of its functionality, cheapness and support of development. As the CSS device uses 2.4GHz for a carrier frequency and the sampling frequency is lower than that of the UWB, the resolution of a timestamp is very coarse. Then actually the error of a measured distance is very large about 30cm~1m at 10 m depart. And the location error in ($10m{\times}10m$) environment is known as about 1m~2m. So for some applications which require more accurate location information, it is very natural and important to develop a sophisticated post processing algorithm after distance measurements. In this paper, we have studied extended Kalman filter with the frequency offsets of anchor nodes, and proposed a novel algorithm frequency offset compensated extended Kalman filter. The frequency offsets are composed with a variable as a common frequency offset and constants as individual frequency offsets. The proposed algorithm shows that the accurate location estimation, less than 10cm distance error, with CSS WPAN nodes is possible practically.

• KIPS Transactions on Computer and Communication Systems
• /
• v.9 no.3
• /
• pp.67-76
• /
• 2020

With the fast development in wireless communications and vehicular technologies, vehicular ad hoc networks (VANETs) have enabled to deliver data between vehicles. Recently, VANETs introduce a Vehicular Cloud (VC) model for collaborating to share and use resources of vehicles to create value-added services. To construct a VC, a vehicle should search vehicles that intend to provide their own resource. The single-hop search cannot search enough provider vehicles due to a small coverage and non-line-of-sights of communications. On the other hand, the multi-hop search causes very high traffics for large coverage searching and frequent connection breakages. Recently, many Roadside Units (RSUs) have been deployed on roads to collect the information of vehicles in their own coverages and to connect them to Internet. Thus, we propose a RSU-aided vehicular resource search and cloud construction mechanism in VANETS. In the proposed mechanism, a RSU collects the information of location and mobility of vehicles and selects provider vehicles enabled to provide resources needed for constructing a VC of a requester vehicle based on the collected information. In the proposed mechanism, the criteria for determining provider vehicles to provide resources are the connection duration between each candidate vehicle and the requester vehicle, the resource size of each candidate vehicle, and its connection starting time to the requester vehicle. Simulation results verify that the proposed mechanism achieves better performance than the existing mechanism.

• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.73-78
• /
• 2002

In WATM networks, in order to perform dynamic slot allocation required slots of mobile terminals are estimated based on DP (Dynamic Parameter) reflecting characteristics of traffic. In VBR (Variable Bit Rate) traffic, slot allocation is done at MT considering both time-dependent characteristics and QoS (Quality of Service) requirements. In this paper, DPs-buffer state information and buffer state change-are transmitted through in-band signaling. BS (Base Station) performs dynamic slot allocation considering traffic characteristics of each MT (Mobile Terminal), in other words, buffer state information informs the potentiality of 'buffer full state'to BS if MT buffer is over the specific threshold value and buffer state change notifies change in buffer state of incoming cells to MT. If buffer state information is equal to 'low (more than threshold)' and 'abrupt increase' it generates 'buffer full' state cell transmission delay or cell loss might occur. At this time BS should assign additional slots to MT, and then MT consumes cells in its buffer. In simulation, the proposed scheme shows better performance in cell delay and loss than EPSA (Estimation-Prorated Slot Assignment) in-band scheme.

• The KIPS Transactions:PartC
• /
• v.9C no.6
• /
• pp.935-944
• /
• 2002

It is the Mobile Ad Hoc Networks that constituted with serveral mobile node that can communicate with other mobile nodes. Until now, there were no routing protocols considering such as Multimediadata, VOD (Video On Demand), which is required of lots of bandwidth in Mobile Ad Hoc Network, io we are in the need of QoS (Quality of Service)routing protocol to transmit the data packets faster and more accurate. Also, there are an unidirectional links due to asymmetric property of mobile terminals or current wireless environments on practical mobile ad hoc networks. However, at present, the existing mobile ad hoc routing protocols are implemented to support only bidirectional links. In this paper, we propose the Advanced Routing routing protocol in order to implement a new routing protocol, which is fit to mobile ad hoc networks containing unidirectional links and to support QoS service. For the performance evaluation, we use NS-2 simulator of U.C. Berkeley. We could get not only increased received data rate and decreased average route discovery time, but also network load decreases with compared Best effort service.

• The KIPS Transactions:PartD
• /
• v.11D no.6
• /
• pp.1221-1230
• /
• 2004

In mobile environments, the locations of moving objects such as vehicles, airplanes and users of wireless devices continuously change over time. For efficiently processing moving object information, the database system should be able to deal with large volume of data, and manage indexing efficiently. However, previous research on indexing method mainly focused on query performance, and did not pay attention to update operation for moving objects. In this paper, we propose a novel moving object indexing method, named ACAR-Tree. For processing efficiently frequently updating of moving object location information as well as query performance, the proposed method is based on fixed grid structure with auxiliary R-Tree. This hybrid structure is able to overcome the poor update performance of R-Tree which is caused by reorganizing of R-Tree. Also, the proposed method is able to efficiently deal with skewed-. or gaussian distribution of data using auxiliary R-Tree. The experimental results using various data size and distribution of data show that the proposed method has reduced the size of index and improve the update and query performance compared with R-Tree indexing method.

• The KIPS Transactions:PartD
• /
• v.11D no.6
• /
• pp.1247-1258
• /
• 2004

The LBS(Location-Based Service), which is based on individual's mobility, is required increasingly as mobile telecommunication and various infrastructures have developed rapidly. The technologies for LBS are location determination technology, service platform technology, contents provider technology and moving object database technology generally. Among these, service platform must be interoperable with location gate-way server and provide common function of billing, authentification, protect location information, privacy control, location trigger and intelligent acquisition and so on. The TTA(Telecommunications Technology Association) published specification that defines a standard protocol for safe and simple interface between LBS client and LBS platform and the OpenLS(Open Location Service) in OGC (Open GIS Consortium) released implementation specifications for providing Location based core services. In this paper, we implemented service platform for LBS which is able to interoperable with location gateway server and contents provider and is caracterized as follows. First, it could require and response location information from different types of location gateway server with same interface. Second, it complies with the standard interfaces with OpenLS 4 contents providers for core LBS. Third, it could provide location of wired phone as well as wireless mobile terminal compling with the standard protocol. Last, it could provide trajectorH information based past location as well as current location, because it is able to interoperable with moving object DBMS. This paper contributes to the construction and practical use of LBS by providing the method of implementation of service platform for LBS.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.10
• /
• pp.2587-2596
• /
• 1999

Recently, by the extension of skills like LAN, the wireless telecommunication network and the satelite services make it possible for the mobile computer users to access a database. A method to use the replicated database on a server to get new data without missing any information has been being studied. So far we have used the Static Replica Allocation(SRA) for the replication which is the method of the replication on the server. This method is to replicate the data on the replica server after a moving host is transferred to a cell. Since the network of the SRA is very good, and if there are few moving users, no trouble will happen. But if there is no moving users in a cell, the data will not be shared. Therefore, this paper is about the study of the method of relocation after replicating the data to the cells for the users(User Select Replica Allocation : USRA). We also analyze the access rate and the possibility which are closely related to the moving frequency of the mobile hosts and the numbers of the cells. As a result, We show that the 120% lower access cost and the 40%∼50% gains are achieved from the low mobility

• Journal of Sensor Science and Technology
• /
• v.17 no.5
• /
• pp.350-360
• /
• 2008

In every large hospital, nurses must perform simple repetitive tasks such as measuring body temperature. Such tedious work reduces nurses' motivation to provide quality medical care, which is an important element of the medical services provided by a hospital. If a device were available to measure body temperature, nurses could focus on the more important aspects of providing quality medical care to the patients. However, body temperature is generally measured from the throat, anus, tympanum or armpit, where it is difficult to affix a patch type device. In addition, general body temperature measuring points shows moving artifact error; therefore, it is not good point to continually measure the temperature. In this paper, a patch type skin temperature measuring system was developed. To appropriately measure the skin temperature, a thermal transducer was implemented with a thin (0.5 mm) temperature sensor. The system is small and thin ($H6.6{\sim}5.3{\times}L35{\times}W24\;mm$), and weighs only 5 g including a battery, case and circuit; therefore, it is small and light enough to function as a patch type device. Moreover, the system worked for 5 days. To investigate differences between the experimental and conventional thermometer, simple clinical experiments were performed with 17 volunteers, and the result showed some correlation between the implemented system and conventional thermometer (Correlation coefficient = 0.647, P<0.1).

• Science of Emotion and Sensibility
• /
• v.12 no.2
• /
• pp.161-168
• /
• 2009

In this study, we have developed the patch type HAMS (Heart Activity Monitoring System) which is non-restricted, non-awarable and non-invasive. The module using wireless telecommunication to receive the ECG (electrocardiogram) signal at the computer has mobility which it easily monitors the heart activity of subjects in no time for long term at any time and places. We developed the small patch type electrode which can be attached on the chest. Also the reliability and moving artifact of ECG signal measured by this electrode have been verified. Using HAMS, we measured the HRV (Heart Rate Variability) parameters, the questionnaire evaluation for anxiety and stress and the amount of stress hormone (cotisol) to evaluate the stress effect in HRV on the same subject. As a result of comparing the values under non stressed and stressed condition, there was significant difference on many parameters. And the parameter highly related with stress on Pearson's Correlation Coefficient has been examined. These show that using HAMS is able to evaluate the function of autonomic nervous system. Therefore, we can predict heart problem in daily life by using HAMS. Also we expect that this module can be applied for more application as health monitoring system.

• Journal of Animal Science and Technology
• /
• v.60 no.11
• /
• pp.27.1-27.8
• /
• 2018

Background: Enteric methane ($CH_4$) accounts for about 70% of total $CH_4$ emissions from the ruminant animals. Researchers are exploring ways to mitigate enteric $CH_4$ emissions from ruminants. Recently, nano zinc oxide (nZnO) has shown potential in reducing $CH_4$ and hydrogen sulfide ($H_2S$) production from the liquid manure under anaerobic storage conditions. Four different levels of nZnO and two types of feed were mixed with rumen fluid to investigate the efficacy of nZnO in mitigating gaseous production. Methods: All experiments with four replicates were conducted in batches in 250 mL glass bottles paired with the ANKOM$^{RF}$ wireless gas production monitoring system. Gas production was monitored continuously for 72 h at a constant temperature of $39{\pm}1^{\circ}C$ in a water bath. Headspace gas samples were collected using gas-tight syringes from the Tedlar bags connected to the glass bottles and analyzed for greenhouse gases ($CH_4$ and carbon dioxide-$CO_2$) and $H_2S$ concentrations. $CH_4$ and $CO_2$ gas concentrations were analyzed using an SRI-8610 Gas Chromatograph and $H_2S$ concentrations were measured using a Jerome 631X meter. At the same time, substrate (i.e. mixed rumen fluid+ NP treatment+ feed composite) samples were collected from the glass bottles at the beginning and at the end of an experiment for bacterial counts, and volatile fatty acids (VFAs) analysis. Results: Compared to the control treatment the $H_2S$ and GHGs concentration reduction after 72 h of the tested nZnO levels varied between 4.89 to 53.65%. Additionally, 0.47 to 22.21% microbial population reduction was observed from the applied nZnO treatments. Application of nZnO at a rate of $1000{\mu}g\;g^{-1}$ have exhibited the highest amount of concentration reductions for all three gases and microbial population. Conclusion: Results suggest that both 500 and $1000{\mu}g\;g^{-1}$ nZnO application levels have the potential to reduce GHG and $H_2S$ concentrations.