• The KIPS Transactions:PartD
• /
• v.14D no.2
• /
• pp.249-264
• /
• 2007

As the need for telematics contents services due to the frequent traveling of people is increasing, it is necessary to provide various telematics contents by connecting and integrating current telematics contents which are collected and provided by each individual data provider. However, it is difficult to integrate or exchange the current telematics contents, because the data providers use different telematics contents models. Therefore, we propose a 'telematics contents gateway(TCG); system, which enables to integrate different telematics contents, so that the contents can be interoperable. The TCG can be a solution for several problems in the current telematics contents providing system. First of all, it has been impossible to search the contents without any information about data providers, because of the absence of metadata in the current systems. For this problem, TCG supports a search function based on a web-service technology. Second, TCG provides a common road network model for interoperability, and the model can be a solution to integrate different road network models into the common model. Moreover, integration algorithm for enhancing the correctness of integration will be proposed. In addition, it is designed by multi threads and multi queue structure. The TCG developed with C# on a windows system has been running and we verified that there was no information loss in the integration process. In addition, the speed of content integration and transfer satisfied the requirement of telematics services providers.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.12
• /
• pp.149-158
• /
• 2005

This paper proposes a congestion avoidance algorithm which provides stable throughput and transmission rate regardless of buffer size by limiting the TCP congestion window in fixed bandwidth networks. Additive Increase, Multiplicative Decrease (AIMD) is the most commonly used congestion control algorithm. But, the AIMD-based TCP congestion control method causes unnecessary packet losses and retransmissions from the congestion window increment for available bandwidth verification when used in fixed bandwidth networks. In addition, the saw tooth variation of TCP throughput is inappropriate to be adopted for the applications that require low bandwidth variation. We present an algorithm in which congestion window can be limited under appropriate circumstances to avoid congestion losses while still addressing fairness issues. The maximum congestion window is determined from delay information to avoid queueing at the bottleneck node, hence stabilizes the throughput and the transmission rate of the connection without buffer and window control process. Simulations have performed to verify compatibility, steady state throughput, steady state packet loss count, and the variance of congestion window. The proposed algorithm can be easily adopted to the sender and is easy to deploy avoiding changes in network routers and user programs. The proposed algorithm can be applied to enhance the performance of the high-speed access network which is one of the fixed bandwidth networks.

• Journal of the Korean Vacuum Society
• /
• v.20 no.2
• /
• pp.77-85
• /
• 2011

The silicon-germanium (SiGe) alloy, which is compatible with silicon semiconductor technology and has a smaller band gap and a lower thermal conductivity than silicon, has been used to fabricate electronic devices such as transistors, photodetectors, solar cells, and thermoelectric devices. This paper reviews the application of SiGe alloys to electronic devices and related technical issues. Since the SiGe alloy comprises germanium whose band gap is smaller than silicon, its band gap is also smaller than that of silicon irrespective of the ratio of silicon to germanium. This narrow band gap of SiGe enables the base thickness of bipolar transistors to decrease without a loss in current gain so that it is possible to improve the speed of bipolar transistors by adopting the SiGe-base. In addition, the conversion efficiency of solar cells is enhanced by the absorption of long-wavelength light in the SiGe absorption layer. Phonon scattering caused by the irregular distribution of alloying elements induces the lower thermal conductivity of SiGe than those of pure silicon and germanium. Because a thin film layer with a low thermal conductivity suppresses thermal conduction through a thermal sink, the SiGe alloy is considered to be a promising material for silicon-based thermoelectric systems.

• Food Science and Preservation
• /
• v.24 no.1
• /
• pp.60-67
• /
• 2017

In this study, we tried to establish the best method for fresh blueberry beverage production using enzyme treatment as well as low temperature extraction. During extraction of physiologically functional materials, we used low temperature to prevent nutritional loss by heat. In addition, we investigated optimal blueberry extraction conditions using various enzyme treatments (cellulase, pectinase, cellulase:pectinase (1:1) mixture) to increase extraction efficiency and reduce turbidity. A variety and ratio of enzymes, extraction temperature, extraction time, and shaking speed were considered for the best extraction efficiency rate. We observed high extraction efficiency rates of 85.72-86.55% and 87.06-87.93%, respectively, upon cellulase or pectinase treatment. In addition, a mixture of cellulase:pectinase (1:1) showed an extraction efficiency rate of 86.84-88.14%. The best extraction efficiency rate was observed when crude blueberry was treated at $45^{\circ}C$ (87.91%), for 3 h (87.88%), in a 90 rpm shaker (89.19%). Sugar content and acidity of blueberry extract were not affected by the various treatments. However, total phenolic compounds were detected upon pectinase treatment (18.62 mg/g). Only fructose and glucose as free sugars were found in all samples regardless of treatments and extraction conditions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1C
• /
• pp.103-112
• /
• 2010

In this paper, we propose a coarse and fine frequency synchronization method which is suitable for the 3GPP(3rd Generation Partnership Project) LTE(Long Term Evolution) FDD(Frequency Division Duplexing) / TDD(Time Division Duplexing) dual mode system. In general, PSS(Primary Synchronization Signal) correlation based estimation method and CP(Cyclic Prefix) correlation based tracking loop are applied for coarse and fine frequency synchronization in 3GPP LTE OFDMA(Orthogonal Frequency Division Multiple Access) system, respectively. However, the conventional coarse frequency synchronization method has performance degradation caused by fading channel and squaring loss. Also, the conventional fine frequency synchronization method cannot guarantee stable operation in TDD mode because of signal power difference between uplink and downlink subframe. Therefore, in this paper, we propose enhanced coarse and fine frequency synchronization methods which can estimate more accurately in multi-path fading channel and high speed channel environments and has stable operation for TDD frame structure, respectively. By computer simulation, we show that the proposed methods outperform the conventional methods, and verify that the proposed frequency synchronization method can guarantee stable operation in 3GPP LTE FDD/TDD dual mode downlink receiver.

• Journal of the Institute of Convergence Signal Processing
• /
• v.18 no.2
• /
• pp.55-61
• /
• 2017

In radio astronomy, high-capacity HDDs are being used to save huge amounts of HDDs in order to record the observational data. For VLBI observations, observational speeds increase and huge amounts of observational data must be stored as they expand to broadband. As the HDD is frequently used, the number of failures occurred, and then it takes a lot of time to recover it. In addition, if a failed HDD is continuously used, observational data loss occurs. And it costs a lot of money to buy a new HDD. In this study, we developed the integrity verification system of the Serial ATA HDD using FirmOS. The FirmOS is an OS that has been developed to function exclusively for specific purposes on a system having a general server board and CPU. The developed system performs the process of writing and reading specific patterns of data in a physical area of the SATA HDD based on a FirmOS. In addition, we introduced a method to investigate the integrity of HDD integrity by comparing it with the stored pattern data from the HDD controller. Using the developed system, it was easy to determine whether the disk pack used in VLBI observations has error or not, and it is very useful to improve the observation efficiency. This paper introduces the detail for the design, configuration, testing, etc. of the SATA HDD integrity verification system developed.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.1
• /
• pp.54-59
• /
• 2011

This test established the bioavailability and sample input by mixing the maintaining the microbial machine parts and food waste leachates in weight of 2:1 as advanced experiment, maintaining the constant temperature, agitating and observing its weight and property change for 60 hours. And, I injected daily the established microbial machine parts and food waste leachates rate, maintained the temperature in the reactor with $55{\sim}65^{\circ}C$, and agitated with constant speed. I studied the recycling possibility of food waste leachates by extracting the sample after 24 hours, verifying its characteristics, and repeating the food waste leachates input and sample extraction for about 40 days. Considering all about the results of this study, I saw that 87.32% of food waste leachates was reduced, and the solid of bluebug or food included in the food waste leachates was decomposed within 24 hrs. pH for 43 days after 9 days of stabilization period was maintained from 3.7~3.9 and the ignition loss from 88.67~87.3%, and the quantity of organic matter from 77.6~80.88%. With the similar result daily maintained, it is considered to progress more the minimization by inputting the future food waste leachates. C/N rate satisfies the less than 25 that is the composting basis within 8 days, maintaining between 13~15, with 2% of salt not exceeded, it is able to recycle as the compost of food waste leachates as based on the composting with no extracted heavy metal content.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.5
• /
• pp.688-696
• /
• 2016

This paper evaluates the effect of hot weather conditions on the fresh concrete characteristics of 80-MPa high-strength concrete. The slump flow, packing ability, setting time, hydration heat, and compressive strength were evaluated under exterior temperatures of $20^{\circ}C$, $30^{\circ}C$, and $40^{\circ}C$. The slump flow, arrival speed of 500 mm, and their changes with the elapsed time were found to bring the occurrence of rapid slump loss forward by about 30 minutes when increasing the temperature by $10^{\circ}C$ from $20^{\circ}C$. The initial and final setting times of the concrete at $20^{\circ}C$ were 7 hours and 12 hours, which were reduced by 1 hour and 3 hours at $30^{\circ}C$ and by 2 hours and 5 hours at $40^{\circ}C$, respectively. The hydration heat characteristics at $20^{\circ}C$ and $30^{\circ}C$ were similar in terms of the highest temperature of the concrete casting depth and the time when the maximum temperature occurred. However, at $40^{\circ}C$, the maximum temperature occurred about 4 hours earlier, and the highest temperature per the concrete casting depth increased by about $12^{\circ}C$. Therefore, it is concluded that the characteristics can vary according to the exterior temperature. Thus, quality assurance should consider workability, temperature cracks due to hydration heat, the properties of strength development, and other characteristics.

• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.2
• /
• pp.133-138
• /
• 2011

In IP-based wireless sensor networks (WSNs), it might be necessary to distribute application updates to the sensor nodes in order to fix bugs or add new functionality. However, physical access to nodes is in many cases extremely limited following deployment. Therefore, network reprogramming protocols have recently emerged as a way to distribute application updates without requiring physical access to sensor nodes. In order to solve the network reprogramming problem over the air interface, this thesis presents a new scheme for new update code propagation using fragmentation scheme and network coding. The proposed code propagation method roughly shows reduced performance improvement in terms of the number of data exchange compared with the previously proposed pipelining scheme. Further, It is shows enhanced reliability for update code propagation and reduced overhead in terms of the number of data exchange. As a result, we can efficiently perform the software update from the viewpoint of speed, energy, and network congestion when the proposed code propagation system is applied. In addition, the proposed system solves overhearing problems of network coding such as the loss of original messages and decoding error using the predefined message. Therefore, our system allows a software update system to exchange reliable data in wireless sensor networks.

• Proceedings of KOSOMES biannual meeting
• /
• 2008.05a
• /
• pp.185-189
• /
• 2008

This study was conducted to find out the effects of relationship between ocean conditions and snowfall when cold and dry continental air mass passes through the West Sea of Korea. Route of continental high atmospheric pressure can cause effect on snowfall at the west regions (Inchoen, Gunsan, Mokpo) of the Korean Peninsula. The continental high atmospheric pressure extend from the southern China to western coastal region of the Korean Peninsula during the December, and it extend from the north side of China through Bohai Sea and Yodong Peninsula to central area of the Korean Peninsula during the February. Therefore, more snowfall recorded in Incheon is higher during Feb. than Dec.. whereas Gunsan and Mokpo is the opposite. The heavy snowfall at the western coastal region of Korea was caused by loss of the heat from the ocean to air when it's higher than $100W/m^2$. the heavy snowfall was also observed when the arrangement of continental high atmospheric pressure and low pressure was high at the West and low at the East, which formed a front in West and when the wind blow from the North or North West at the speed of $4\sim8m/sec$. There were not much relation between salinity in the western sea and snowfall in the western coastal region of Korea.