• Molecules and Cells
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• v.22 no.3
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• pp.328-335
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• 2006

Imperatoxin A ($IpTx_a$), a 3.7 kDa peptide from the African scorpion Pandinus imperator, is an agonist of the skeletal muscle ryanodine receptor (RyR1). In order to study the structure of the toxin and its effect on RyR1, $IpTx_a$ cDNA was PCR-amplified using 3 pairs of primers, and the toxin was expressed in E. coli. The toxin was further purified by chromatography, and various point mutants in which basic amino acids were substituted by alanine were prepared by site-directed mutagenesis. Studies of single channel properties by the planar lipid bilayer method showed that the recombinant $IpTx_a$ was identical to the synthetic $IpTx_a$ with respect to high-performance liquid chromatography mobility, amino acid composition and specific effects on RyR1. Mutations of certain basic amino acids ($Lys^{19}$, $Arg^{23}$, and $Arg^{33}$) dramatically reduced the capacity of the peptide to activate RyRs. A subconductance state predominated when $Lys^8$ was substituted with alanine. These results suggest that some basic amino acid residues in $IpTx_a$ are important for activation of RyR1, and that $Lys^8$ plays an important role in regulating the gating mode of RyR1.

• Ecology and Resilient Infrastructure
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• v.1 no.2
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• pp.82-93
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• 2014

In recent years, "ecological river restoration" taking into account the flood control, water utilization and environmental aspects of rivers is actively being investigated. However, it is hard to understand the inhabitation conditions of living organisms that live on the river with distinct characteristics have been fully reflected, and with the use of limited methods, it ends in uniformed composition of artificial rivers and a mere customary stream channel maintenance, resulting in frequently disturbed stream channel habitats As a fundamental study for investigating the habitats of living organisms that live on rivers, this study intends to examine each habitat type by dividing domestic rivers into sand rivers and gravel rivers depending on the nature of rivers and dividing sections of each river into central river sections and natural river sections. As a result, more diverse habitat types of organisms were found in the gravel rivers rather than in the sand rivers, and the habitat types of organisms in the central river sections where the river restoration project have been already conducted reached approximately 56.3 % of those that appeared in the natural river sections.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1654-1659
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• 2014

Tunneling field-effect transistors (TFETs) are very applicable to low standby-power application by their virtues of low off-current ($I_{off}$) and small subthreshold swing (S). However, low on-current ($I_{on}$) of silicon-based TFETs has been pointed out as a drawback. To improve $I_{on}$ of TFET, a gate-all-around (GAA) TFET based on III-V compound semiconductor with InAs/InGaAs/InP multiple-heterojunction structure is proposed and investigated. Its performances have been evaluated with the gallium (Ga) composition (x) for $In_{1-x}Ga_xAs$ in the channel region. According to the simulation results for $I_{on}$, $I_{off}$, S, and on/off current ratio ($I_{on}/I_{off}$), the device adopting $In_{0.53}Ga_{0.47}As$ channel showed the optimum direct-current (DC) performance, as a result of controlling the Ga fraction. By introducing an n-type InGaAs thin layer near the source end, improved DC characteristics and radio-frequency (RF) performances were obtained due to boosted band-to-band (BTB) tunneling efficiency.

• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.217-225
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• 1999

Through the ISODATA method of unsupervised classification, the micro-landform of Julpo-Bay tidal flat was classified into mudflat, mixedflat, and sandflat using Landsat TM image. Each showed an apparent differences in its topographical characteristics and grain size composition. Mudflat occupied innermost part of the tidal flat, sandflat located closest to the entrance of the bay and mixed flat in the center is. For example, mudlflats are formed with flat faces and tidal channel. Topographically, mudflat consist of tidal channels and flat intermediate surface. Its average relief of them is about 2 meter. Meanwhile, sandflat comprised very flat landform with well-developed ripple marks of less than 10cm average relief. And Mixed flat stood in between. In addition, Out of 7 bands of Landsat TM images, band 5 and 7 provided the highest power level for discrimination between micro-landforms of the tidal flat. Band 4 showed a clear boundary between the land and tidal flat, and band 3 did its share by showing well a boundary between the sea surface and the tidal flat.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.3
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• pp.182-189
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• 2011

In this work, a tunneling field-effect transistor (TFET) based on heterojunctions of compound and Group IV semiconductors is introduced and simulated. TFETs based on either silicon or compound semiconductors have been intensively researched due to their merits of robustness against short channel effects (SCEs) and excellent subthreshold swing (SS) characteristics. However, silicon TFETs have the drawback of low on-current and compound ones are difficult to integrate with silicon CMOS circuits. In order to combine the high tunneling efficiency of narrow bandgap material TFETs and the high mobility of III-V TFETs, a Type-I heterojunction tunneling field-effect transistor (I-HTFET) adopting $Ge-Al_xGa_{1-x}As-Ge$ system has been optimized by simulation in terms of aluminum (Al) composition. To maximize device performance, we considered a nanowire structure, and it was shown that high performance (HP) logic technology can be achieved by the proposed device. The optimum Al composition turned out to be around 20% (x=0.2).

• Journal of Ecology and Environment
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• v.40 no.1
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• pp.12-19
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• 2016

Background: Direct impact of inorganic carbon (i.e., carbon dioxide ($CO_2$)) on the periphyton community is important to understand how and to what extent atmospheric conditions can affect the structure and dynamics of these communities in lotic systems. We investigated the influence of elevated $CO_2$ concentration on the periphyton community in the artificially constructed channels during the winter period. The channels made of acrylic paneling were continuously supplied with surface water discharged from a small reservoir, which was supported with ground water, at a flow rate of 5 L/min, and water temperature ranging $4-5^{\circ}C$. The effects of elevated $CO_2$ concentrations (790 ppm) were evaluated in comparison with the control (395 ppm $CO_2$) by analyzing pH, water carbon content and nutrients in water, periphyton composition and biomass, chlorophyll-a, ash-free dry-matter at 2-day intervals for 10 days. Results: After the addition of $CO_2$, significant decreases of pH, $NH_3-N$, and $PO_4-P$ (p < 0.05) and increases of chlorophyll-a, ash-free dry-matter, and the cell density of periphyton (p < 0.01) were observed, whereas the species composition of periphyton and water carbon content did not change. Conclusions: These results suggest that elevated $CO_2$ in flowing water system with low temperature could facilitate the growth of periphyton resulting in biomass increase, which could further influence water quality and the consumers throughout the food web.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1467-1474
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• 2016

In response to the water shortage problem, continued attempts are being made to secure consistent and reliable water sources. Among various solutions to this problem, wastewater effluent is an easy way to secure the necessary supply, since its annual output is consistent. Furthermore, wastewater effluent has the advantage of being able to serve various purposes, such as cleaning, sprinkling, landscaping, river management, irrigation, and industrial applications. Therefore, this study presents the possible use of reclaimed industrial wastewater treated with Birm filters and a UF membrane, along with an analysis on membrane fouling. The preprocessing stage, part of the reclamation process, used Birm filters to minimize membrane fouling. Since this study did not consider heavy metal levels in the treated water, the analyses did not include the criterion for irrigation water quality. However, the wastewater reclaimed by using Birm filters and a UF membrane met every other requirement for reclaimed water quality standards. This indicated that the treated water could be used for cleaning, channel flow for maintenance, recreational purposes, and industrial applications. The analysis on the fouling of the Birm filter and UF membrane required the study of the composition and recovery rate of the membrane. According to SEM and EDX analyses of the UF membrane, carbon and oxygen ion composition amounted to approximately 57%, whereas inorganic matter was not detected. Furthermore, the difference in the recovery rates of the distressed membrane between acidic and alkaline cleaning was more than ~78%, which indicated that organic rather than inorganic matter contributed to membrane fouling.

• Journal of Internet Computing and Services
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• v.15 no.1
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• pp.45-53
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• 2014

UI-Mashup is widely used as a service method to add value, which is composed of distributed various contents on the internet and has turned out to be one of the latest trends in web application program development. Previous UI-Mashup-related studies have focused primarily on the dynamic service composition and have not been able to adapt to a rapidly changing Web Standard, thusthe end users conclude that UI-Mashups are slow, incompatible and poor security services. In this study, We propose an architecture for the performance improvements of UI-Mashup.In order to provide fast services and security enhancements, the proposed architecture collects UI fragments on the server in parallel, and sends layouts and contents of Mashups UI to the client through a special delivery channel supporting fast reaction and response time. In this study, the implementation and performance tests were proceeded to verify the proposed architecture experimentally. As a result of the performance testing, the proposed architecture has two to three times faster response time and more than four times throughput compared to the previous UI-Mashup technology.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.3
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• pp.101-104
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• 2004

It was realized that MC-XRD is useful for phase analyzing of inclusions in crystals because it can focus the X-Ray beam to the small particles sized dozens of $\mu\textrm{m}$ with high S/N ratio. By using this MC-XRD, needle-like inclusions which are seen generally in corundum crystals known as rutile was found to be the iron titanium oxide and iron oxide which has the chemical composition of $Fe_2TiO_4,\; Fe_2TiO_5,\; Fe_2O_3$respectively

• Journal of the Korean Professional Engineers Association
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• v.34 no.4
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• pp.41-47
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• 2001

The paper describes SR3 (Synchronous Round Robin with Reservations), a collision-free medium access control protocol for all-optical slotted packet networks based on WDM multi-channel ring topologies where nodes are equipped with one fixed-wavelength receiver and one wavelength-tunable transmitter SR3 is derived from the SRR and MMR protocols previously proposed by the same authors for the same class of all-optical networks. SRR and MMR already achieve an efficient exploitation of the available bandwidth, while guaranteeing a throughput-fair access to each node. SR3, In addition, allows nodes to reserve slots. thereby achieving a stronger control on access delays; it is thus well suited to meet tight delay requirements, as it is the case for multimedia applications. Simulation results show that SR3 provides very good performance to guaranteed qualify traffic, but also brings signigicant performance improvements for best-effort traffic. Energy effciency is an important issue for optical network since they must rely on their batteries. We present a novel MAC protocol that achieves a good energy efficiency of optical interface of the network and provides support for diverse traffic types and QoS. The scheduler of the base station is responsible to provide the required QoS to connections on the optical link and to minimise the amount of energy spend by the High speed Network. The main principles of the MaC protocol are to avoid unsuccessful actions, minimise the number of transitions , and synchronise the mobile and the base-station. We will show that considerable amounts of energy can be saved using these principles.