• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1195-1211
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• 2016

The emerging video coding standard High Efficiency Video Coding (HEVC) has shown almost 40% bit-rate reduction over the state-of-the-art Advanced Video Coding (AVC) standard but at about 40% computational complexity overhead. The main reason for HEVC computational complexity is the inter prediction that accounts for 60%-70% of the whole encoding time. In this paper, we propose several fast coding unit (CU) encoding schemes based on the Merge mode and motion estimation information to reduce the computational complexity caused by the HEVC inter prediction. Firstly, an early Merge mode decision method based on motion estimation (EMD) is proposed for each CU size. Then, a Merge mode based early termination method (MET) is developed to determine the CU size at an early stage. To provide a better balance between computational complexity and coding efficiency, several fast CU encoding schemes are surveyed according to the rate-distortion-complexity characteristics of EMD and MET methods as a function of CU sizes. These fast CU encoding schemes can be seamlessly incorporated in the existing control structures of the HEVC encoder without limiting its potential parallelization and hardware acceleration. Experimental results demonstrate that the proposed schemes achieve 19%-46% computational complexity reduction over the HEVC test model reference software, HM 16.4, at a cost of 0.2%-2.4% bit-rate increases under the random access coding configuration. The respective values under the low-delay B coding configuration are 17%-43% and 0.1%-1.2%.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.5
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• pp.737-748
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• 1995

In this paper, we studyed the variables in the design of multichip memory modules with 4M$\times$1bit DRAM chips to construct high capacity and high speed memory modules. The configuration of the module was 8 bit, 16 bit, and 32 bit DRAM modules with employing 0.6 W, 70 nsec 4M$\times$1 bit DRAM chips. We optimized routing area and wiring density by performing the routing experiment with the variables of the chip allocation, module I/O terminal, the number of wiring, and the number of mounting side of the chips. The multichip module was designed to be able to accept MCM-L techiques and low cost PCB materials. The module routing experiment showed that it was an efficient way to align chip I/O terminals and module I/O terminals in parallel when mounting bare chips, and in perpendicular when mounting packaged chips, to set module I/O terminals in two sides, to use double sided substrates, and to allocate chips in a row. The efficient number of wiring layer was 4 layers when designing single sided bare chip mounting modules and 6 layers when constructing double sided bare chip mounting modules whereas the number of wiring layer was 3 layers when using single sided packaged chip mounting substrates and 5 layers when constructing double sided packaged chip mounting substrates. The most efficient configuration was to mount bare chips on doubled substrates and also to increase the number of mounting chips. The fabrication of memory multichip module showed that the modules with bare chips can be reduced to a half in volume and one third in weight comparing to the module with packaged chips. The signal propagation delay time on module substrate was reduced to 0.5-1 nsec.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.523-528
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• 2006

The management of construction materials is one of the important administration factor to perform construction projects. If it is not flexible to supply necessary materials to a workplace at a proper time, some problems such as a construction cost increase, an operation delay, a lowering of work efficiency and etc. could occur during the progress of work. Therefore, tracking the precise location of materials is important and necessary to input materials in the accurate place. Although Location sensing techniques comprise GPS, Active Badge, EasyLing and so forth, there are technical limitations to apply these techniques on construction site. Accordingly, in this paper, we propose the technically feasible method to automatically locate materials on site using recent RFID and wireless network technologies.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.3
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• pp.260-265
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• 2005

Patient-controlled analgesia (PCA) has been widely used for postoperative pain control in medical surgery parts. Conventional intramuscular analgesia (IMA) is also effective in postoperative pain control, but it has some disadvantages that depend on patients' perception of pain and the anxiety that they endure caused by the delay of the injection time. This study was conducted to assess the efficacy and postoperative outcomes of intravenous PCA compared to IMA injections in 36 patients (BSSRO). Three factors were compared: amount of pain in PCA and IMA group ; amount of pain according to the sex in PCA and IMA group and the amount of pain according to the analgesia use. Results of this study did not demonstrate a statistically significant difference in any of these, using a p value of 0.05. The results of this study were as follows. : 1. There was no statistically significant difference in VAS pain score between IMA group and PCA group. 2. There was no statistically significant difference according to the sex. 3. There was no statistically significant difference according to the amount of PCA. The history of PCA is about 30 years and many literatures have reported about its effects, complications, methods, advantages and disadvantages. So, this study has some limitations of small sample size to conclude the effects of PCA. But when the decision about the method for postoperative pain control has to be made, it should be made based on patient or physician preference and cost factors rather than on the trend.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.567-577
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• 2019

Due to the depletion of fossil fuels and environmental pollution, demand for alternative energy is gradually increasing. Among the various methods, a method to convert biomass into alternative fuel has been proposed. The bio-fuel obtained from biomass through pyrolysis process is called pyrolysis oil (PO) or bio-oil. Because PO is difficult to use directly in conventional engines due to its poor fuel properties, various methods have been proposed to upgrade pyrolysis-oil. The simplest approach is to mix it with conventional fossil fuels. However, due to their different polarity of PO and fossil fuel, direct mixing is impossible. To resolve this problem, emulsification of two fuels with a proper surfactant was proposed, but it costs additional time and cost. Alternatively, the use of alcohol fuels as an organic solvent significantly improve the fuel properties such as fuel stability, calorific value and viscosity. In this study, blends of diesel, n-butanol, and coffee ground pyrolysis oil (CGPO) which is one of the promising PO, was applied to diesel generator. Combustion and emissions characteristics of blended fuels were investigated under the entire load range. Experimental results show that ignition delay is similar to that of diesel at high load. Although, hydrocarbon and carbon monoxide emissions are comparable to diesel, significant reduction of nitrogen oxides and particulate matter emissions were observed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.181-184
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• 2006

Knowledge of the ionospheric peak parameter foF2 (the critical frequency of F2 layer) is one of key essential factors for predicting ionospheric characteristics and delay correction of satellite positioning. However, the foF2 was almost estimated using an empirical model of International Reference Ionosphere (IRI) or other expensive observing techniques, such as ionosondes and scatter radar. In this paper, the ionospheric peak parameter foF2 is the first observed by ground-based GPS with all weather, low-cost and near real time properties. Compared with the IRI-2001 and independent ionosondes at or near the GPS receiver stations, the foF2 obtained from ground-based GPS is in better agreement, but closer to the ionosonde. However, during nighttime, the IRI model overestimated the GPS observed values during winter and equinox months.Furthermore, seasonal variation trend of the foF2 in 2003 is studied using foF2 monthly median hourly data measured over South Korea. It has shown that the systematic diurnal changes of foF2 are apparent in each season and the higher values of foF2 are observed during the equinoxes (semiannual anomaly) as well as in mid-daytime of each season.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3542-3547
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• 2015

There is commonly used the full depth excavation method of sewer pipeline maintenance in Korea. This induces couple of technical and social problems like increase of construction cost and time for excavation and backfill, increase of public complains and delay of traffic, and so force. In order to overcome these problems, lots of laboratory tests were carried out for sewer pipeline of maintenance materials with trenchless methods. The testing materials are liquid and hardened polyurethane, and polyurethane CIPP. The lab tests were followed by Korean Standard. There are no side effects, like harmless to the human body and air pollution with stink. Judging from the limited test results, all the items tested were satisfied the KS criteria.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.517-520
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• 2009

Healthcare application system has been actively researched to apply WSN technology to healthcare area with a mobile sensor node of low cost, low power, and small size. Sensor node has the problem for transmission range of RF power and time delay of the wireless routing connectivity between sensor nodes. In this paper, we proposes a new method utilizing mobile sensor nodes with relay sensor nodes for quick network routing changing using query technique in healthcare system. A query processor to control and manage the routing changing of sensor nodes in a wireless sensor network was designed and implemented. The user's PC transmits the beacon message which will change the quick link routing according to activity status of patient in wireless sensor network. We describe the implementation for query protocol that is very effective of power saving between sensor nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.188-210
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• 2022

As a promising technique to support tremendous numbers of Internet of Things devices and a variety of applications efficiently, mobile edge computing (MEC) has attracted extensive studies recently. In this paper, we consider a MEC-assisted peer-to-peer (P2P) mobile communication system where MEC servers are deployed at access points to accelerate the communication process between mobile terminals. To capture the tradeoff between the time delay and the energy consumption of the system, a cost function is introduced to facilitate the optimization of the computation and communication resources. The formulated optimization problem is non-convex and is tackled by an iterative block coordinate descent algorithm that decouples the original optimization problem into two subproblems and alternately optimizes the computation and communication resources. Moreover, the MEC-assisted P2P communication system is compared with the conventional P2P communication system, then a condition is provided in closed-form expression when the MEC-assisted P2P communication system performs better. Simulation results show that the advantage of this system is enhanced when the computing capability of the receiver increases whereas it is reduced when the computing capability of the transmitter increases. In addition, the performance of this system is significantly improved when the signal-to-noise ratio of hop-1 exceeds that of hop-2.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.8
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• pp.2140-2156
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• 2023

The Wireless Sensor Network (WSN), is constructed out of teeny-tiny sensor nodes that are very low-cost, have a low impact on the environment in terms of the amount of power they consume, and are able to successfully transmit data to the base station. The primary challenges that are presented by WSN are those that are posed by the distance between nodes, the amount of energy that is consumed, and the delay in time. The sensor node's source of power supply is a battery, and this particular battery is not capable of being recharged. In this scenario, the amount of energy that is consumed rises in direct proportion to the distance that separates the nodes. Here, we present a Hybrid Firefly Glow-Worm Swarm Optimization (HF-GSO) guided routing strategy for preserving WSNs' low power footprint. An efficient fitness function based on firefly optimization is used to select the Cluster Head (CH) in this procedure. It aids in minimising power consumption and the occurrence of dead sensor nodes. After a cluster head (CH) has been chosen, the Glow-Worm Swarm Optimization (GSO) algorithm is used to figure out the best path for sending data to the sink node. Power consumption, throughput, packet delivery ratio, and network lifetime are just some of the metrics measured and compared between the proposed method and methods that are conceptually similar to those already in use. Simulation results showed that the proposed method significantly reduced energy consumption compared to the state-of-the-art methods, while simultaneously increasing the number of functioning sensor nodes by 2.4%. Proposed method produces superior outcomes compared to alternative optimization-based methods.