• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1802-1807
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• 2015

The cloud computing service provides physical IT resources to VM instances to users using virtual technique and the users pay cost of VM instances to service provider. The auction model based on cloud computing provides available resources of service provider to users through auction mechanism. The users bid spot instances to process their a job until its deadline time. If the bidding price of users is higher than the spot price, the user will be provided the spot instances by service provider. In this paper, we propose a new bidding strategy to minimize the total cost for job completion. Typically, the users propose bidding price as high as possible to get the spot instances and the spot price get high. we lower the spot price using proposed strategy and minimize the total cost for job completion. To evaluate the performance of our strategy, we compare the spot price and the total cost for job completion with real workload data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.942-949
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• 2016

Efficient routing protocols designed for Wireless Sensor Networks (WSN) can be extended and applied to Internet of Things (IoT) data routing, as IoT can be considered to be an extension from WSN. When the size of the data in IoT is often bigger than in conventional WSNs, existing cluster routing protocol such as LEACH may cause high data loss rate due to its incomplete load balancing. We present an enhanced LEACH-based protocol which can minimize the data loss which is an important performance measure in IoT. In our proposed protocol, the base station estimates the location of nodes by the trilateration technique to make sure optimal number of cluster heads and members in a deterministic manner. We evaluate our proposed protocol via computer simulations in terms of data loss rate and average network lifetime.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8274-8283
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• 2015

Gas springs of the television is to control the piston speed when operating under along stroke(200~300 mm, television elevation)is possible. User by this principle is capable of elevation adjustment. First carried out a flow analysis of the piston. A piston speed adjustment technique for precise pipe type cross-section was examined. The piston structure for flow rate control and elevation action is proposed. This study is the development of a gas spring of more than 50 inch television with a large television stand. Hollow piston rod for optimal control(the outer diameter 19.9 mm, the inner diameter 13.9 mm) was injected into the nitrogen gas(0.3 mm/s) in. As a result, the flow rate the pressure drop of the piston rod as the increase was increased without any change of the external force. As a result, control of the displacement via the gas spring is possible.

• Journal of Applied Biological Chemistry
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• v.52 no.3
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• pp.109-115
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• 2009

The gene encoding a putative aspartate aminotransferase in Xanthomonas oryzae pv. oryzae (Xoo) was cloned using PCR technique. The gene was ligated with pET-21(a) vector containing His6 tag and expressed in E. coli BL21(DE3). Affinity purification of the recombinant aspartate aminotransferase with Ni-NTA resin resulted in one band by SDS-PAGE analysis. The purified enzyme showed a molecular weight of 43 kDa, as expected. The enzyme was the most active toward L-aspartate as an amino donor, indicating that the purified enzyme is one of aspartate aminotrans-ferases exist in Xoo. Optimal activity of the enzyme was observed at around pH 7.5 and stability was much higher at alkaline pH rather than acidic pH values. The enzyme was considerably activated by the presence of manganese ion, showing about 157% of control activity at 1.0 mM.

• Journal of the Korean Applied Science and Technology
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• v.26 no.1
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• pp.1-9
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• 2009

Nowadays, Tra catfish fat is given attention as an appropriate material for biodiesel production in Vietnam. The aim of this work is to investigate the optimal conditions of refining biodiesel and recovering glycerin by the transesterification from Tra catfish fat using KOH catalyst. As our results, the yield of transesterification was achieved to 94.17% at $50^{\circ}C$ for 45 min with 6:1 molar ratio of methanol to fat in the presence of 0.8% KOH catalyst, and wherein the biodiesel was refined by washing with distilled water at $70^{\circ}C$ and dried in a microwave oven. The yield of raw glycerin recoveries from the transesterification process was 78.58%. The purity of raw glycerin was 84.14% by the conditions of neutralization state with $H_{3}PO_{4}$ solution (pH = 5), $70^{\circ}C$, and 60 min. Activated carbon (3.0 wt.%) was used for the bleaching process at $80^{\circ}C$ for 20 min. The biodiesel was obtained in accordance with for ASTM D 6751 (biodiesel standard). The ash and water of raw glycerins were 7.32 and 8.01%, respectively, and implied that the raw glycerin is very promising candidate to be used as a raw material for textile and cosmetic industries.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.68-79
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• 2006

Electrical capacitance tomography (ECT) is a non-invasive imaging reconstruction technique that aims at visualization of cross sectional permittivity distribution of dielectric object based on the measured capacitance. There are lots of iterative image reconstruction methods to accelerate convergence rate and enhance quality of reconstructed image, Among them iterative Landweber method is one of the widely used reconstruction algorithm in En. In this paper, modified generalized Landweber method is proposed to accelerate convergence rate. In doing so, acceleration term is considered to the generalized Landweber method with shaping matrix and an optimal step length is determined analytically. Extensive computer simulations are provided to illustrate the reconstruction performance of the proposed algorithm.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.32-40
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• 1989

Dynamic ship positioning(DP) system is used to keep the position and heading of a ship, or a floating platform, above a pre-selected site on the seabed by using thrusters. This paper presents a control system based on filtering technique and optimal control theory. The planar motions of a vessel are assumed to consist of low frequency(LF) component and high frequency(HF) one. The former is mainly due to thrusters, current, wind and second order wave forces, while the latter is mainly due to first order oscillatory component of the wave force. Furthermore position measurement signals include the noise. By means of self-tuning filter and Kalman filter techniques, LF motion estimates and HF ones are seperately achieved from the position measurements of the vessel. The estimated LF motions are used as input to the feedback loops. The total thruster power is minimized using the Linear Quadratic Gaussian control theory. The performance of the vessel with the DP system is investigated by computer simulation.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.3
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• pp.127-143
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• 2016

This study explored the variability in the accuracy of dasymetric population estimation with different grid cell sizes. Dasymetric population maps for Fulton County, Georgia in the US were generated from 30m to 420m at intervals of 30m using an automated intelligent dasymetric mapping technique, population data, and original and simulated land use and cover data. The accuracies of dasymetric population maps were evaluated using RMSE and adjusted RMSE statistics. Lumped fractal dimension values were calculated for the dasymetric population maps generated from resolutions of 30m to 420m using the triangular prism surface area (TPSA) method. The results show that a grid cell size of 210m or smaller is required to estimate population more accurately in terms of thematic accuracy, but a grid cell size of 30m is required to meet an acceptable spatial accuracy of dasymetric population estimation in the study area. The fractal analysis also indicates that a grid cell size of 120m is the optimal resolution for dasymetric population estimation in the study area.

• Journal of Environmental Science International
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• v.6 no.2
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• pp.153-163
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• 1997

In order to fad the most fitted biodegradation model, biodegradation kinetics model to the initial phenol and p-cresot concentrations were investigated and had been fitted by the linear regression. Bacteria capable of degrading p-cresol were isolated from soil by enrichment culture technique. Among them, strain Ml capable of degradillg p.rcresol has also degraded phenal and was identified as the genus Micrococcus from the results from of taxonomical studies. The optimal tonditlons for the biodegradation of phenal and p-cresol by Micrococcus sp. Ml were $NH_4NO_3$ 0.05%, pH 7.0, 3$0^{\circ}C$, respectively, and medium volume 100m1/250m1 shaking flask. iwicrococcus sp. Ml was able to grow on phenal concentration up to 14mM and p-cresol concelltration up to 0.8mM. With increasing substrate concentraction, the lag period increased, but the maximum specific growth rates decreased. The yield coefficient decreased with increasing substrate concentation. The biodegradation kinetics of phenol and p-cresol were best described by Monod with growth model for every experimented concentration. In cultivation of mixed substrate, p-cresol was degraded first and phenol was second. This result implies that p-cresol and phenol was not degraded simultaneously.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.553-563
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• 2010

This paper presents a tapered slot-antenna(TSA) for optimal impulse-signal transmission in ultra-wide band(UWB). The proposed TSA provides radiates in end-fire direction, which meets an impulse-radio UWB(IR-UWB) system demands(e.g., low loss, thus less error throughout the UWB band). In order to minimize the pulse distortion, we used an wideband impedance transformer and a microstrip slotline. The pulse fidelity characteristics was evaluated with finite-difference time-domain(FDTD) analysis technique and pulse fidelity correlation equation. Approximately 93.89 % pulse fidelity was obtained between the two antennas in 0.5 m range. Additionally, derived chirp Z-transform algorithm enables us to utilize the zoom-in option on the pulse signal in few nano-seconds below. Thus, it is possible to analyze the pulse signal distortion, delay or dispersion characteristics.