• Journal of Integrative Natural Science
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• v.10 no.1
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• pp.1-6
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• 2017

Demand for a new anti-malarial drug has been dramatically increasing in the recent years. Plasmodium falciparum enoyl-acyl carrier protein reductase (PfENR) plays a vital role in fatty acid elongation process, which now emerged as a new important target for the development of anti-microbial and anti-parasitic molecules. In the present study, 19 compounds namely alginic acid, atropine, chlorogenic acid, chrotacumine A & B, coenzyme $Q_1$, 4-coumaric acid, curcumin, ellagic acid, embelin, 5-O-methyl embelin, eugenyl glucoside, glabridin, hyoscyamine, nordihydroguaiaretic acid, rohitukine, scopolamine, tlatlancuayin and ursolic acid were evaluated on their docking behaviour on P. falciparum enoyl-acyl carrier protein reductase (PfENR) using Auto dock 4.2. The docking studies and binding free energy calculations exhibited that glabridin gave the highest binding energy (-8.07 kcal/mol) and 4-coumaric acid in contrast showed the least binding energy (-4.83 kcal/mol). All ligands except alginic acid, ellagic acid, hyoscyamine and glabridin interacted with Gln409 amino acid residue. Interestingly four ligands namely coenzyme $Q_1$, 4-coumaric acid, embelin and 5-O-methyl embelin interacted with Gln409 amino acid residue present in both chains (A & B) of PfENR protein. Thus, the results of this present study exhibited the potential of these 19 ligands as P. falciparum enoyl-acyl carrier protein reductase (PfENR) inhibitory agents and also as anti-malarial agents.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.14-14
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• 2011

AlInN has been studied extensively over the past few years due to its interesting material properties that are not present in other ternary nitrides. However, basic material study of AlInN has not been reported as much compared to device applications due to the difficulty in the growth. We have performed the material studies from various aspects. A secondary ion mass spectrometry (SIMS) has shown high oxygen content above $1{\times}10^{18}\;cm^{-3}$ with its insensitivity to the growth conditions. While the free carrier concentration observed by the capacitance-voltage (C-V) measurements was about $3{\times}10^{17}\;cm^{-3}$, the activation energy measured by temperature dependent C-V was only about 4 meV. Si doped AlInN (Si level ${\sim}2{\times}10^{18}\;cm^{-3}$) showed almost no carrier freeze-out at carrier density of $1{\times}10^{18}\;cm^{-3}$. More studies were carried out with a transmission electron microscopy, time-resolved photoluminescence and other analytical techniques to understand the results from SIMS and C-V studies. In this report, we will discuss the possible correlations between the abnormal characteristics in AlInN.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.107-107
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• 2011

오늘 날 transparent conductive oxide는 다양한 분야에서 활용되고 있다. 최근에는 태양전지 분야에서도 많이 활용되고 있으며, 초기에는 transmittance 및 낮은 sheet resistance 특성을 가지는 ITO가 많이 활용되었지만 thin film solar cell와 같이 hydrogenation 공정에 약한 ITO보다는 Al-doped ZnO가 사용되기 시작하면서 많은 연구가 진행되고 있다. 본 연구에서는 thin film solar cell 및 silicon heterojunction solar cell에 적용 가능한 Al-doped ZnO에 관한 연구로써 a-Si:H의 Si-H bonds에 영향을 주지 않는 낮은 영역의 substrate temperature와 power로 Al-doped ZnO를 형성하고 상기 parameter에 따른 Al-doped ZnO의 특성 변화에 대해서 분석하였다. 특히 substrate temperature가 변화할수록 carrier concentration 및 sheet resistance가 많은 변화를 보였으며 이로 인하여 transmittance 특성이 온도에 따라 좋아지다가 너무 높은 온도에서는 오히려 좋지 않게 되었다. 이는 너무 높은 carrier concentration은 free carrier absorption에 의해 transmittance 특성을 오히려 좋지 않게 한다. 우리는 본 연구를 통해 92.677% (450 nm), 90.309% (545 nm), 94.333% (800 nm)의 transmittance를 얻을 수 있었다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.112-118
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• 2013

Air travel demand has recently been growing and establishment and operation of low-cost carriers have been increased. Against this backdrop, low-cost carriers need to figure out diversified customer demand for low-cost carriers and ways to maximize marketing efficiency before applying it to the field so that they can attain superiority to large carriers in increased intensified competition. Low-cost carriers need to be differentiated from other carriers for the purpose of improving profits. Toward this end, this study conducted analysis on importance and satisfaction with carrier choice using IPA with regard to low-cost carrier customers. In conclusion, the paper accurately examined advantages and disadvantages of low-cost carriers compared to general carriers based on results of IPA analysis and suggested managerial strategies to enhance competitiveness based on division into four parts including maintenance and enforcement (1st quadrant, Delay compensation, Booking rapidity, Check rapidity, Crew service, refund service, baggage service, punctuality, transit services, airlines images), concentrated improvement (2nd quadrant, price, Convenience of seat), passive administration (3rd quadrant, Boarding service, cabin cleanliness, flight schedule, whether local crew on board, meal service, in-flight entertainment service), and enhanced satisfaction (4th quadrant, duty-free service, Variety of routes), so that practical suggestions could be presented to employees working in the field.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.22-30
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• 2005

Sloshing loads, produced by the violent liquid free-surface motions inside the cargo tank have become an important design parameter in ship building industry since there have been demands for the increased sizes of the cargo containment system of LNG carriers. In this study, sloshing impact pressure acting on the shell of the spherical cargo tank of an LNG carrier as well as dynamic pressure and flow behavior around the pump tower located at the center of the tank have been calculated. Comparative numerical sloshing simulations for a spherical LNG tank using 2-D LR.FLUIDS which is based on the finite difference method and 3-D MSC.DYTRAN which is capable of calculating nonlinear fluid-structure interaction have been carried out. A method of calculating sloshing-induced dynamic loads and the subsequent structural strength analysis for pump tower of a spherical LNG carrier using MSC. DYTRAN and MSC.NASTRAN have been presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.12
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• pp.4024-4041
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• 2022

Robust reversible watermarking has attracted widespread attention in the field of information hiding in recent years. It should not only have robustness against attacks in transmission but also meet the reversibility of distortion-free transmission. According to our best knowledge, the most recent robust reversible watermarking methods adopt a single image as the carrier, which might lead to low efficiency in terms of carrier utilization. To address the issue, a novel dual-image robust reversible watermarking framework is proposed in this paper to effectively utilize the correlation between both carriers (namely dual images) and thus improve the efficiency of carrier utilization. In the dual-image robust reversible watermarking framework, a two-layer robust watermarking mechanism is designed to further improve the algorithm performances, i.e., embedding capacity and robustness. In addition, an optimization model is built to determine the parameters. Finally, the proposed framework is applied in different domains (namely domain-independent), i.e., Slantlet Transform and Singular Value Decomposition domain, and Zernike moments, respectively to demonstrate its effectiveness and generality. Experimental results demonstrate the superiority of the proposed dual-image robust reversible watermarking framework.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.66-67
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• 2003

Bismuth (Bi) has been an attractive materials for studying spin dependent transport properties because it shows very large magnetoresistance (MR) resulting from its highly anisotropic Fermi surface, low carrier concentrations, long carrier mean free path 1 and small effective carrier mass m*[1-3]. With all the intriguing properties, difficulty in fabrication of high quality Bi thin films may have prevented extensive application of Bi in magnetic field sensing and spin-injection devices. Previous works found that the surface roughness and small grain size in 100-200 nm of Bi thin film made by evaporation and sputtering are major causes of low MR. Although relatively higher MR in electrodeposited Bi followed by annealing was reported, it still suffers from rough sulfate roughness which is so severs that it is hardly able to make a field sensing and spin-injection device using conventional photolithography process.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.2
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• pp.736-749
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• 2019

This paper employs computational tools to investigate the diffraction effects in regular head waves on the added resistance and wake on the propeller plane. The objective ships are a 66,000 DWT bulk carrier and a 3,600 TEU container ship. Fixed and free to heave and pitch conditions at design speed have been taken into account. Two-phase unsteady Reynolds averaged Navier-Stokes equations have been solved using the finite volume method; and a realizable k-ε model has been applied for the turbulent closure. The free surface is obtained by solving a VOF equation. The computations are carried out at the same scale of the model tests. Grid and numerical wave damping zones are applied to remove unwanted wave reflection at the boundaries. The computational results are analyzed using the Fourier series. The added resistances in waves at the free condition are higher than those at the fixed condition, which are nearly constant for all wavelengths. The wake velocity in waves is higher than that in calm water, and is accelerated where the wave crest locates on the propeller plane. When the vertical motion at the stern goes upward, the wake velocity also accelerated.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.3
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• pp.135-145
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• 2018

This paper deals with the added resistance of a ship in waves using computational fluid dynamics (CFD). The ship added resistance is one of the key considerations in the design of energy-efficient ship. In this study, the added resistance of a LNG carrier in head waves is computed using a CFD code to consider the nonlinearity and the viscous effects. The unsteady Reynolds Averaged Navier-Stokes equation (RANS) is numerically solved and the volume of fluid (VOF) approach is used to simulate the free surface flows. The length of incident wave varies from half the ship length to twice the ship length. To investigate the nonlinearity effect, both the linear wave condition and the nonlinear wave condition are considered. The heave and pitch motions are calculated along with the added resistance, and the wave contours are obtained. Grid convergence test is conducted thoroughly to achieve the converged motion and resistance values. The calculated results are compared and validated with experimental data.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.478-489
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• 2015

In the present study, a hydrodynamic hull-form optimization algorithm for a container ship was presented in terms of the minimum wave-making resistance. Bell-shaped modification functions were developed to modify the original hull-form and a sequential quadratic programming algorithm was used as an optimizer. The wave-making resistance as an objective function was obtained by the Rankine source panel method in which non-linear free surface conditions and the trim and sinkage of the ship were fully taken into account. Numerical computation was performed to investigate the validity and effectiveness of the proposed hull-form modification algorithm for the container carrier. The computational results were validated by comparing them with the experimental data.