• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.624-627
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• 2014

In vehicular network, the basic goal is to provide vehicle safety service and commercial service such as ITS(Intelligent Transportation System) or video, etc on the road. And most research concentrated on transportation of safety message in congestion situation. It is important to allocate channel for safety message in congestion situation, but providing suitable service is also important problem in vehicular network. For this reason, IEEE 1609.4 allocate 4 multiple service channels (SCHs) for non-safety data transfer. But, in congestion situation with many vehicles, the contention for channel acquisition between services becomes more severe. So services are provided improperly because of lack of service channel. This paper suggests dynamic channel allocation algorithm. The proposed algorithm is that RSU(RaodSide Unit) maintain and manage the information about service and status of channels. On based of the SJF(Shortest Job First) scheduling using those information, RSU selects the most appropriate channel among the 4 SCHs allocated by IEEE 1609.4 in network congestion situation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.694-700
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• 2013

Urban area is a representative environment of wireless channels in the mobile communication, building density has a different distribution depending on the location. Building density has affect to propagation prediction For this reason, building density is expected to affect to the channel characteristics, we need to analyze it. We measured channel characteristics in urban areas of Jeju island by channel sounder and $4{\times}4$ antenna. Channel characteristics considering the building density were derived based on the measured data in the urban area. In this paper, the measurement data is analyzed and channel characteristics are derived through MIMO Channel measurements at 700 MHz considering the building density in the urban area.

• Knowledge Management Research
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• v.16 no.4
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• pp.109-132
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• 2015

We examine offline and online channel sales of experience goods, and compare and contrast the sales patterns of existing products and new products between channels. To this end, we obtain the channel-specific time-series sales data from the leading company selling beauty products, both offline and online. By applying the Vector Autoregressive Model, we empirically find out how the relationship between existing products and new products changes between the shopping channels. Our empirical findings are as follows. First, the sales effects from existing products to new products are significantly positive at both offline and online channels, and this positive effect is greater in the offline channel than in the online channel. Second, the influence of new products on existing products is more positive in the offline channel than in the online channel. Third, the impact of existing products sales on new products sales is greater than that of new products on existing products. Lastly, the inertia effect, the effect within the same shopping channel and the same selling product, is significantly positive in the offline channel but not in the online channel, and this asymmetric inertia effect emerges as we focus on experience goods. Moreover, the impulse response function analysis provides the three important implications. First, companies should pay attention to the same channel but different types of products. Second, the offline channel is more vulnerable to market shock than the online channel. Third, new products sales vary by existing products sales to the greater extent, compared to the opposite relationship. We believe our study contributes theoretically and practically to the fields of marketing and knowledge management.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.4
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• pp.33-42
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• 2019

In this study, the channel and floodplain widths are indirectly measured for three different watersheds using satellite images to reflect the shape of Korean channels in the Soil and Water Assessment Tool (SWAT) model. For measuring the channel and floodplain widths, multiple satellite images were referred to ensure the widest width of certain points. In the single channel, the widths at the multiple points were measured. Based on the measured data, the regression equations were derived to estimate the channel and floodplain widths according to watershed areas. Applying these developed equations, this study evaluated the effect of the change of channel and floodplain widths on the SWAT simulation by comparing to the measured streamflow data. The developed equations estimated larger channel width and smaller floodplain compared with those calculated in the current SWAT model. As shown in the results, there was no considerable changes in the predicted streamflow using the current and developed equations. However, the flow velocity and channel depth calculated from the developed equations were smaller than those of the current equations. The differences were caused by the effect of different channel geometries used for calculating the hydraulic characteristics. The channel geometries also affected the water quality simulation in channels because the hydraulic characteristics calculated by the channel geometries are directly related to the water quality simulation. Therefore, application of the river cross-sectional regression equation reflecting the domestic stream shape is necessary for accurate water quantity / quality and water ecosystem simulation using hydrological model.

• Journal of Haehwa Medicine
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• v.13 no.1
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• pp.61-69
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• 2004

I have come to next conclusions in consequence of documentary study about medical books of many generations regarding acupuncture and moxibustion therapy of arthalgia syndrome. 1. Jing point of regular channels is most used. Next there are extraordinary point, ashi point in the acupuncture and moxibustion therapy of arthalgia syndrome. 2. The gall baldder channel of foot-shaoyang is most used. Next there are the urinary bladder channel of foot-taiyang, the large intestine channel of hand-yangming, the stomach channel of foot-yangming, the small intestine channel of hand-taiyang, the spleen channel of foot-taiyin, the liver channel of foot-jueyin, the triple-warmer channel of hand-shaoyang, the du channel, the lung channel of hand-taiyin, the kidney channel of foot-shaoyin, the pericardium channel of hand-jueyin, the heart channel of hand-shaoyin, the ren channel in the order of frequency in used channel among the twelve channels. 3. Three yang channels of foot is most used. Next there are three yang channels of hand, three yin channels of hand, three yin channels of foot in the order of frequency in use among the twelve channels. 4. The gall baldder channel of foot-shaoyang is most used. Next there are the urinary bladder channel of foot-taiyang, the large intestine channel of hand-yangming, the triple-warmer channel of hand-shaoyang, the stomach channel of foot-yangming, the small intestine channel of hand-taiyang, the liver channel of foot-jueyin, the lung channel of hand-taiyin, the spleen channel of foot-taiyin, the kidney channel of foot-shaoyin, the du channel, the pericardium channel of hand-jueyin, the ren channel the heart channel of hand-shaoyin in the order of frequency in used point among the twelve channels. 5. Huantiao is most used. Next there are Weizhong, Quchi, Yangfu, Chize Feiyang Xiyangguan Xiguan Tianjing, Sanli Xiaoluo in the order of frequency in use. 6. Jing point in the order of frequency of use, expel wind-evil and remove wetness-evil on the Acupuncture and Moxibustion Therapy of Arthalgia Syndrome.

• Journal of Broadcast Engineering
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• v.21 no.4
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• pp.552-561
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• 2016

In OFDM system, frequency-domain sub-carriers of a symbol generally consist of data sub-carriers and scattered pilot sub-carriers and in the receiver, channel is estimated through time-axis interpolating pilot sub-carriers of several OFDM symbols. However, time-axis interpolation fails to keep track of rapid channel variation caused by fast moving receiver. Although symbol by symbol channel estimation without time-axis interpolation enables fast estimation, the performance is severely degraded for a long delay spread channel in a single frequency networks (SFNs) because of insufficient pilot sub-carriers. In this paper, a channel estimation scheme for OFDM receiver in a fast mobile SFN channel is proposed. The proposed scheme is applied to DVB-T receiver to improve the Doppler mobile performance in SFN channel.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.503-512
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• 2012

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan New Port including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. In addition, Yongwon channel is approximately 100 m wide on average and 3,600 m long, and has the highest slenderness ratio (length/width = 36). So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. In this study, the bottom sediment were collected from the 48 points of the Yongwon channel and the long-term leaching characteristics were analyzed. Thus, changes in sediment and water quality were analyzed through the sediment release test to investigate the degree of contamination. The sediment release from the inside region was higher than the outer region, which is due to the pollutant that comes form the downtown area. The results of this study can be used to predict the water quality in the future and prepare the economically optimized countermeasures to improve the water quality of Yongwon channel, Busan New Port.

• Journal of ILASS-Korea
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• v.28 no.4
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• pp.198-206
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• 2023

In this study, visualization of in-cylinder spray behavior and spark channel stretching by air flow characteristics depending on engine operating conditions were investigated. For in-cylinder spray behavior, increase in engine rpm did not alter the counter-clockwise air flow direction and location of in-cylinder dominant air flow but increased average air flow velocity, which hindered spray propagation parallel to the piston surface. When injection timing was retarded, direction of in-cylinder dominant air flow was changed, and average air flow velocity was reduced resulting in an increase in spray penetration length and change in direction. For spark channel stretching, increase in air flow speed did not affect spark channel stretch direction but affected length due to increase in spark channel resistance and limitation of energy ignition coil can handle. Change in air flow direction affected spark channel stretch direction where the air flow was obstructed by ground electrode which caused spark channel direction to occur in the opposing direction of air flow. It also affected spark channel stretch length due to change in air flow speed around the spark plug electrode from the interaction between the air flow and ground electrode.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.12-19
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• 2016

The monitoring system in railway is under study to forecast any derailment and accident by defect of train. Because the monitoring system is composed of wireless sensor network based on ZigBee-communication between inside and outside of train, the study for wireless channel analysis is required. Especially, if multipath delay profile exist in the channel, the equalizer and channel estimator can be required for preventing receiver performance degradation. Therefore, we analyzed the wireless channel in train environment using measured data and, proposed the channel estimation method through the characterisitic of chip code, under the consideration of the channel characteristics in train. To show the performance of proposed method, we demonstrate the performance by mean square error(MSE), computational complexity and bit error rate(BER).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.139-142
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• 2009

RFID(Radio Frequency IDentification) technology is an automatic identification method using radio frequencies between RFID reader which collects the information and tag which transmits the information. RFID technology develops passive RFID which transmit the only ID to active RFID which transmit the additional information such as sensing information. However, ISO/IEC 18000-7 as active RFID standard has a problem which cannot use multiple channel. To solve this problem, we use the 2.4GHz bandwidth technology and we propose the dynamic channel allocation method which can efficiently allot a channel. we show the operation of the dynamic channel allocation method through design and implement with CC2500DK of Taxas Instrument.