• Biomedical Science Letters
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• v.25 no.4
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• pp.302-312
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• 2019

The aim of this work was to investigate the effect of black tea extract (BTE) on collagen -induced platelet aggregation. In this study, BTE (10~500 ㎍/mL) was shown to inhibit platelet aggregation via thromboxane A₂ (TXA₂) down-regulation by blocking cyclooxygenase-1 (COX-1) activity. Also, BTE decreased intracellular Ca²⁺ mobilization ([Ca²⁺]_i). Additionally, BTE enhanced the levels of both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are aggregation-inhibiting molecules. BTE inhibited the phosphorylation of phospholipase C (PLC) γ2 and syk activated by collagen. BTE regulated platelet aggregation via cAMP-dependent phosphorylation of vasodilator-stimulated phosphoprotein (VASP) Ser¹⁵⁷. The anti-platelet effects of BTE in high fat diet (HFD)-induced obese rats were evaluated. After eight weeks of BTE treatment (300 and 600 mg/kg), the platelet aggregation rate in the treated groups was significantly less than that in the HFD-fed control group. Also, BTE exhibited a hepatoprotective effect and did not exert hepatotoxicity. Therefore, these data suggest that BTE has anti-platelet effects on collagen-stimulated platelet aggregation and may have therapeutic potential for the prevention of platelet-mediated thrombotic diseases.

• Journal of the Korean Geographical Society
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• v.46 no.2
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• pp.197-211
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• 2011

Due to the complexity of spatial interaction and the necessity of spatial representation and modeling, aggregation of spatial interaction data is indispensible. Given this, the purpose of this paper is to evaluate the effects of modifiable areal unit problem (MAUP) on a spatial interaction model. Four aggregation schemes are utilized at eight different scales: 1) randomly select seeds of district and then allocate basic spatial units to them, 2) minimize the sum of population weighted distance within a district, 3) maximize the proportion of flow within a district, and 4) minimize the proportion of flow within a district. A simple Poisson regression model with origin and destination constraints is utilized. Analysis results demonstrate that spatial characteristics of residuals, parameter values, and goodness-of-fit of the model were influenced by aggregation scale and schemes. Overall, the model responded more sensitively to aggregation scale than aggregation schemes and the scale effect on the model was varied according to aggregation schemes.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.331-334
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• 2005

This paper suggests the Ethernet aggregation to XGMII framing procedure (EAXFP) mechanism to economically combine the traffic adaptation technology with the link aggregation method in designing 10 Gigabit Ethernet (10 GbE) interfaces. This design sidesteps the data-loss issues that can result from designing an interface with only one link. The most critical issue in relation to the link aggregation interface is the algorithm used to control frame distribution between the ten ports. The proposed EAXFP mechanism offers an efficient link aggregation method as well as an efficient frame distribution algorithm, which maximize the throughout of the 10 GbE interface. In the experiment and analysis of the proposed mechanism, it was also discovered that the 10 GbE interface that uses the proposed EAXFP mechanism significantly reduced the packet loss rate. When there will be heavy traffic loads come about in the future, the proposed EAXFP mechanism assures an efficient and economical transmission performance on the router system.

• Toxicological Research
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• v.16 no.4
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• pp.311-315
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• 2000

Previous studies showed that benzoquinone derivatives inhibited platelet aggregation. but there is no information available on their cytotoxicity to platelets. 1n the present study. washed platelets isolated from rats were treated with 1.4-benzoquinone. a representative benzoquinone derivative. to examine its antiaggregating effect and cytotoxicity. 1.4-Benzoquinone significantly inhibited thrombin-induced platelet aggregation. Consistent with this finding. 1.4-benzoquinone suppressed cytosolic calcium increase induced by thrombin. To examine the cytotoxicity by 1 A-benzoquinone in platelets. turbidometry and lactate dehydrogenase release were measured. Treatment with 1.4-benzoquinone resulted in slight cytotoxicity (30% release at 60 min) to platelets. However. the cytotoxicity was not correlated with increase of cytosolic calcium levels in platelets. All these data suggested that 1.4-benzoquinone inhibited thrombin-induced platelet aggregation mediated by inhibition elf calcium level increase and that 1.4-benzoquinone reveals cytotoxicity to some extent without alteration of calcium level in platelets.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.467-469
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• 2006

In wireless network environments, as users' demands on high-speed data communications due to increase of multi-media services, the necessity of new high-speed WLAN technologies has appeared. Nowaday, IEEE is standardizing a new WLAN protocol caned as IEEE 802.11n. To effectively use wireless resources, IEEE 802.11n introduces MAC aggregation function which is similar to that in IEEE 802.11e. In case of transmitting several frames without MAC aggregation, the frames include individual frame header and trailer, and their corresponding acknowledgement frames can appear on wireless link. However, if they are aggregated into single MAC frame, we can reduce the number of used bits due to frame headers/trailers and also remove redundant acknowledgement frames. In this paper, we explain two different MAC frame aggregation methods for IEEE 802.11e and IEEE 802.11n and evaluate their throughput by simulations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.129-140
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• 2004

In this paper, we conduct the research about optimal aggregation interval of travel time data on interrupted traffic flow and verify the reliability of AVI collected data by using car plate matching method in RTMS for systematic collection and analysis of link travel time data on interrupted traffic flow rural arterial. We perform Kolmosorov-Smirnov test on AVT collected sample data and on entire population data, and conclude that the sample data does not represent pure random sampling and hence includes sample collection error. We suggest that additional review is necessary to investigate the effectiveness of AVI collected sample data as link representative data. We also develop statistical model by applying two estimation techniques namely point estimation and interval estimation for calculating optimal aggregation interval. We have implemented our model and determine that point estimate is preferable over interval estimate for exactly selecting and deciding optimal aggregation interval. Our final conclusion is that 5-minute aggregation interval is optimal to estimate travel time in RTMS, as is currently being used our investigation is based on AVI data collected from Yang-ji to Yong-in $42^{nd}$ National road.

• Journal of the Korea Society of Computer and Information
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• v.22 no.3
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• pp.115-122
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• 2017

In this paper, we propose an adaptive data aggregation and compression scheme for wireless sensor networks with energy-harvesting nodes, which increases the amount of data arrived at the sink node by efficient use of the harvested energy. In energy-harvesting wireless sensor networks, sensor nodes can have more than necessary energy because they harvest energy from environments continuously. In the proposed scheme, when a node judges that there is surplus energy by estimating its residual energy, the node compresses and transmits the aggregated data so far. Conversely, if the residual energy is estimated to be depleted, the node turns off its transceiver and collects only its own sensory data to reduce its energy consumption. As a result, this scheme increases the amount of data collected at the sink node by preventing the blackout of relay nodes and facilitating data transmission. Through simulation, we show that the proposed scheme suppresses the occurrence of blackout nodes and collect the largest amount of data at the sink node compared to previous schemes.

• Database Research
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• v.34 no.3
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• pp.14-27
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• 2018

Recently, to alleviate the memory bottleneck problme occurred in Symmetric Multiprocessing (SMP) architecture, Non-Uniform Memory Access (NUMA) architecture was proposed. In addition, since an aggregation operator is an important operator providing properties and summary of data, the efficiency of the aggregation operator is crucial to overall performance of a system. Thus, in this paper, we propose an efficient aggregation processing technique on NUMA architecture. Our proposed technique consists of partition phase and merge phase. In the partition phase, the target relation is partitioned into several partial relations according to grouping attribute. Thus, since each thread can process aggregation operator on partial relation independently, we prevent the remote memory access during the merge phase. Furthermore, at the merge phase, we improve the performance of the aggregation processing by letting each thread compute aggregation with a local hash table as well as avoiding lock contention to merge aggregation results generated by all threads into one.

• Biomedical Science Letters
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• v.15 no.4
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• pp.273-279
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• 2009

Cordycepin (3'-deoxyadenosine) is an adenosine analogue isolated from Cordyceps militaris, and it has been used as an anti-cancer and anti-inflammation ingredient in traditional Chinese medicine. We investigated the effects of cordycepin on human platelet aggregation induced by thapsigargin, and determined the cytosolic free $Ca^{2+}$ levels ($[Ca^{2+}]_i$), an aggregation-stimulating factor. Cordycepin significantly inhibited thapsigargin-induced platelet aggregation. Its inhibitory effect was continually sustained at the maximal aggregation concentration of thapsigargin. The thapsigargin-induced $[Ca^{2+}]_i$ were clearly reduced by cordycepin in the presence of exogenous $CaCl_2$ or extracellular $Ca^{2+}$-chelator (EDTA). These results suggest that cordycepin inhibited thapsigargin-induced $Ca^{2+}$-influx from extracellular domain and thapsigargin-induced $Ca^{2+}$-mobilization from intracellular $Ca^{2+}$ storage. Accordingly, our data demonstrated that cordycepin may have a beneficial effect on platelet aggregation-mediated thrombotic diseases by inhibiting a $[Ca^{2+}]_i$-elevation.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.109-123
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• 2005

The goals of this paper are two folds: i) to evaluate whether the data collected by a license plate matching AVI equipment being operated on some segment of a national highway are suitable or not for use in travel time estimation of interrupted traffic flows; ii) to study the statistical methodologies to be used for the determination of the optimal aggregation interval for travel time estimation. In this study it was found that the AVI data are not representative because the data are collected on some selected lanes of a roadway where main traffic is thru-traffic and, thus the AVI data are different from those collected from all lanes in traffic characteristics. For the determination of the optimal aggregation interval for travel time estimation. two statistical methods. namely point estimation and interval estimation. were tested. The test shows that the point estimation method is more sensitive and gives more desirable results in determing the optimal aggregation interval than the interval estimation method. And it turned out that the optimal aggregation interval on interrupted traffic flows has been calculated as 5 minute and thus the existing aggregation interval. 5 minute is proper.