• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.2 s.344
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• pp.7-15
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• 2006

Recently, Ultra-wideband (UWB) Communication systems have become a popular research topic. UWB system is characterized by the fact that the digital information represented by a subnanosecond pulses is transmitted through the air. In this paper, we consider the PPSM scheme that combine PPM and PSM. We provide the performance in AWGN and SV multipath channel which consists of $CM1\~CM4$. The optimal symbol set for M-ary system in multipath channel which shows good performance is also presented. The simulation results show that the performance in CM4 is worse than that in CMI due to long delay spread, many multipath components, 4-ary system outperforms binary system in Low$E_b/N_0$ but not in high $E_b/N_0$. We find system have the optimal symbol set in multipath channel.

• Journal of Internet Computing and Services
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• v.4 no.3
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• pp.47-55
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• 2003

Multicast protocols ore developed in order to support group communications efficiently, However. there still exist some issues to be solved for deploy multicast protocol in the public internet. This paper refers problem of existing Reliable Multicast Protocols and redesigns component function, and proposes enhanced reliable multicast transport protocol, This paper proposed a improved multicast transport scheme in NACK based reliable multicast. This scheme is much faster than by sender-initiated or receiver-initiated recovery and latency is smaller. Designed components are implemented in UNIX environment using C programming longuage. Then the protocol was evaluated performance through simulation. As the result, proposed protocol is better than existing protocols in both of transmission delay and packet loss. Especially, proposed protocol in this paper con be used in multicast services needed high reliability.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1627-1627
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M^{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima t and the variation of full width at half maximum w were strongly dependent on the detection position and the wavelength of the laser beam. At, t and w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1626-1626
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• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M_{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima $\Delta$t and the variation of full width at half maximum Δw were strongly dependent on the detection position and the wavelength of the laser beam. At, $\Delta$t and $\Delta$w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• The KIPS Transactions:PartB
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• v.15B no.2
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• pp.87-94
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• 2008

In this paper, we propose a new vision-based fire detection method for a real-life application. Most previous vision-based methods using color information and temporal variation of pixel produce frequent false alarms because they used a lot of heuristic features. Furthermore there is also computation delay for accurate fire detection. To overcome these problems, we first detected candidated fire regions by using background modeling and color model of fire. Then we made probabilistic models of fire by using a fact that fire pixel values of consecutive frames are changed constantly and applied them to a Bayesian Network. In this paper we used two level Bayesian network, which contains the intermediate nodes and uses four skewnesses for evidence at each node. Skewness of R normalized with intensity and skewnesses of three high frequency components obtained through wavelet transform. The proposed system has been successfully applied to many fire detection tasks in real world environment and distinguishes fire from moving objects having fire color.

• Current Research on Agriculture and Life Sciences
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• v.23
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• pp.1-8
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• 2005

The purpose of this study was carried out to determine the optimum sowing date and days after sowing (DAS) in automatic facility located at Uiseong of Gyeoungbuk province. The seedling height was rapidly increased with a delay of sowing time from April to May. The 10-day old seedlings with suitable plant height (> l0cm) for machine transplanting in the facility were obtained when the seeds sowed after May 20 at Uiseong in Gyeoungbuk province. The dry weight-height ratio of 10-day old seedlings was significantly decreased when the seeds sowed after June 20, and 15-days old seedlings did after May 10. No. of panicles/hill was reduced with increasing of days after seeding. But there were no significant difference among other yield components such as no. of grains/panicle, ratio of ripened grains, and 1,000 grain weight. The highest grain yield, 748kg/10a, was attained from the 10-day old seedlings transplanted at May 27 in comparision with those of 15-day and 20-day old seedlings. The grain yield of 10-day old seedlings transplanted at June 26 was also higher than that of 15-day old seedlings.

• Journal of the Korea Computer Industry Society
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• v.5 no.3
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• pp.345-354
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• 2004

In these days, such services are popularized as E-commerce, E-government, multimedia services, and home networking applications. Most web traffics generated contemporarily basically use the Hyper Text Transfer Protocol(HTTP). Unfortunately, the HTTP is improper for these applications that comprise significant components of the web traffics. In this paper, we introduce a real-time contents compression architecture that maximizes the web service performance as well as reduces the response time. This architecture is built into the linux kernel-based web accelerating module. It guarantees not only the freshness of compressed contents but also the minimum time delay using an server-state adaptive algorithm, which can determine whether the server sends the compressed message considering the consumption of server resources when heavy requests reach the web server Also, We minimize the CPU overhead of the web server by exclusively implementing the compression kernel-thread. The testing results validates that this architecture saves the bandwidth of the web server and that elapsed time improvement is dramatic.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5003-5011
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• 2013

This paper measured whether neural and behavior responses to attention-emotion task were reflected to emotion regulation capacities. For this purpose, Nineteen healthy right-handed graduates participated in the emotion-attention task three times for three days. Before and after the negative and positive video clips were shown, the participants performed emotion-attention task. EEG and response time were recorded during emotion-attention task. There was positive correlation between ERP P100 and P300 component. The larger the P100 amplitudes at the specific positions, the longer the P300 latencies at these same positions during attention-emotion task. The longer the P300 latencies at the specific positions, the longer the delay in response time. Also, there is and individual differences in ERP components and response time during attention-emotion integration task. Individuals who had lower amplitude and shorter latency of ERP showed faster response time during attention-emotion task, regardless of the type of video clips. This characteristic was interpreted to the lower emotional controls due to premature response for target identification.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1795-1805
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• 1999

In an OFDM (Orthogonal Frequency-Division Multiplexing) system, the sampling frequency offset between the transmitter and receiver is known to cause the interchannel interference (ICI), resulting in performance degradation. In this paper, we propose two time-domain techniques to estimate the sampling frequency offset, especially for a high data-rate OFDM system. The first technique estimates the sampling frequency offset by using the phase difference between two received samples with a fixed amount of time interval, corresponding to the transmitted training symbol, under the assumption of perfect symbol and carrier offset synchronization. The second technique estimates the sampling frequency offset and carrier frequency offset jointly, when the two offsets exist together, by using two training symbols with different frequency components and using a sample algebraic calculation. The proposed estimation techniques for sampling frequency offset cause no time delay due to all time-domain processing, and have a good performance due to no ICI effect. The performances of the proposed techniques are demonstrated by various simulations.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.781-786
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• 2004

In these days, such services are popularized as E-commerce, E- government, multimedia services, and home networking applications. Most web traffics generated contemporarily basically use the Hyper Text Transfer Protocol(HTTP). Unfortunately, the HTTP is improper for these applications that comprise significant components of the web traffics. In this paper, we introduce a real-time contents compression architecture that maximizes the web service performance as well as reduces the response time. This architecture is built into the linux kernel-based web accelerating module. It guarantees not only the freshness of compressed contents but also the minimum time delay using an server-state adaptive algorithm, which can determine whether the server sends the compressed message considering the consumption of sewer resources when heavy requests reach the web server. Also, We minimize the CPU overhead of the web server by exclusively implementing the compression kernel-thread. The testing results validates that this architecture saves the bandwidth of the web server and that elapsed time improvement is dramatic.