• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.1
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• pp.64-72
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• 1997

An analytical study has been performed to investigate the unsteady ignition characteristics of pulse combustion. In many combustion applications, strain rate of the flow can significantly affect the combustion features; ignition, extinction, and reignition. In the pulse combustion, two jets (hot combustion gases and fresh mixtures) coming from the opposite side of the combustor will collide in the combustor forming a stagnation region where the chemical reaction is suppressed by the strain rate until this becomes below the critical value. In this research, the method of large activation energy asymptotic is adopted with one step irreversible kinetics to examine the ignition response to the periodic variation of the strain rate of flow. The results show the variation of the maximum value of strain rate can determine whether the ignition or extinction occur.

• Journal of Contemporary Eastern Asia
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• v.19 no.1
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• pp.84-96
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• 2020

The Republic of Korea (Korea) and the Russian Federation (Russia) are actualizing the cooperation in the Arctic area. As a result, Korean companies have begun to enjoy real economic benefits. However, since there are some troublesome aspects associated with this cooperation, measures that can lead to sustainable development through the supplementation of relevant norms are critical. Russia is also aware of these problems in obtaining economic benefits in the future; cooperation between the two countries should be extended to sufficiently cover this point. The laws related to the region are vague and do not encompass every field. In addition, when it comes to national interests, many situations arise from areas where international and national laws are not clearly harmonized. Therefore, efforts should be made to reflect the interests of both sides and to maintain economic benefits, in case Korea participates in Russia's development of the area, as well as for the legal foundation to reduce negative issues. The Korea-Russia Free Trade Agreement (FTA) negotiation is on the track for the purpose. The two governments should consider various tasks, such as harmonizing with the former FTAs and dealing with the domestic law in accordance with the new FTA. The two countries also have to conduct researches on the efficient use of the FTA and for the 'Sustainable Arctic Development'.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.81-91
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• 2017

The performances of lifting surfaces are particularly critical in specific flight conditions like takeoff and landing. Different systems can be used to increase the lift and drag coefficients in such conditions like slat, flap or ailerons. Nevertheless they increase the losses and make difficult the mechanical design of wing structures. Morphing surfaces are a compromise between a right increase in lift and a reduction of parts movements involved in the actuation. Furthermore these systems are suitable for more than one flight condition with low inertia problems. So, flap and slats can be easily substituted by the corresponding morphing shapes. This paper deals with a genetic optimization of an airfoil with morphing flap with an already optimized nose. Indeed, two different codes are used to solve the equations, a finite volume code suitable for structured grids named ZEN and the EulerBoundary Layer Drela's code MSES. First a number of different preliminary design tests were done considering a specific set of design variables in order to restrict the design region. Then a RANS optimization with a single design point related to the take-off flight condition has been carried out in order to refine the previous design. Results are shown using the characteristic curves of the best and of the baseline reported to outline the computed performances enhancements. They reveal how the contemporary use of a morphing acting on the nose of the main component and the trailing edge of the flap drive towards a total not negligible increment in lift.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.305-310
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• 2016

The sea-port in Northern Vietnam accounts for around one third of the total country's cargo throughput and for many decades has been playing an important role in the logistics system of the country. 11 container terminals currently operate in Northern Vietnam, concentrating in Haiphong city and Quang Ninh province. Despite the increasing demand, the competition among these container terminals has become increasingly more critical. In recent years, massive investments from both government and operators have been made to improve the capability of the local sea-port's logistics infrastructure. This critically needed comprehensive research evaluates the impact of the current logistics infrastructure condition on the competitiveness of terminals and quantitatively compares the competencies of these terminals. In order to meet such requirements, the paper first summarizes the indicators of the logistics infrastructures of the sea ports before developing and testing hypotheses to reveal the correlation between the given factors and the annual throughput of container terminals in the region. Factor analysis will then be applied to score the logistics infrastructure competency of each container terminal. A significant gap between logistics infrastructures among all container terminals was not observed and the competitiveness between container terminals is mostly driven by traditional activities including cargo handling and storage. According to the results, strategic thinking will be needed to contribute to related organizations for better decisions in investment, management, and operation.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.515-521
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• 1993

Separation of deasphalted oil from atmospheric residue using n-pentane as a solvent was carried out to obtain the valuable heavy hydrocarbon products that can be used lube base oil. After separation experiments, it is shown that the separation yield of oil from atmospheric residue was dependent on n-pentane density and increased in the critical region of n-pentane. Also, the metal content of separated oil was much lowered when compared with that of atmospheric residue. However, there's slight differences in sulfur removal between above two cases.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.201-207
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• 2001

We modeled the liquid film dryout(LFD) process for both tube and annulus which have uniformly heated vertical channels. We set phenomenological initial conditions in the model. The initial void fraction on the onset of the annular flow location is derived from the physical chum-to-annular flow criterion with the help of the drift-flux-model. The initial thermodynamic-equilibrium-quality is calculated by iteration with the flow quality to find the onset of the annular-flow location. Present model tends to predict very well at the lower exit quality but under-estimates at the higher exit quality. We found that the prediction error of the present model is gradually bigger as the inlet subcooling approaches near the saturation. We obtained excellent results for both tube and annulus channels as the mean of 0.97 and root-mean-square error of 11% for the number of 3883 experimental data on tubes, and of 0.96 and of 12% for 593 on annuli. The present model extended the applicable range to the relatively low exit quality region than previous LFD models.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.3-5
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• 2004

Cleft lip is one of the most common congenital deformities in craniofacial region. Despite the many reports on the outcome of various surgical techniques from individual medical centers, the evaluation of the outcome is based on the subjective observation because of lack of the objective evaluation system. Therefore, a new technique of objective and scientific evaluation for the nasal deformity of secondary cleft lip and nose deformity is critical to improve the management of the cleft patients including the decision of optimal age of operation and surgical technique as veil as evaluation of the outcome. In this study, a new method was proposed to evaluate the nasal deformity using nostril angle, distance, and area of patient images. The images were also evaluated by three expert plastic surgeons, and put into scale of 5 percentile. Measurement results were compared between the each category and the surgeon's evaluation, and coefficients of each category were statistically tested. As a result, The normalized overlap area of right and left nostrils and distance ratio between two centers of nostrils showed high coefficient with evaluations of plastic surgeons.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.175-177
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• 1996

This paper is studied on the numerical analysis of temperature distribution on the Nb-foil due to the eddy current under operating a superconducting power supply. The increase of rotating speed and magnetic flux above critical magnetic field lead to the temperature rising in the normal spot, the heat was distributed in the region of 30% distance from the center of the normal spot, but the most of the heat was transferred to LHe. Under operation of the sc power supply, the increase of rotation speed has the more influence on the temperature rising than that of magnetic flux. we can conclude that the totaling speed of normal spot is the main design consideration of the sc power supply, and get the optimal value of rotating speed.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.867-873
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• 2004

It has been known that debonding failures between CFS(Carbon Fiber Sheet) and concrete in the strengthened RC beams are initiated by the peeling of the sheets in the region of combined large moment and shear forces, being accompanied by the large shear deformation after flexural cracks. These shear deformation effects are seldom occurred in small-scale model tests, but debondings due to the large shear deformation effects are often observed in a full-scale model tests. The premature debonding failure of CFS, therefore, must be avoided to confirm the design strength of full-scale RC beam in strengthening designs. The reinforcing details, so- called 'U-Shape fiber wrap at mid-span' which wrapped the RC flexural members around the webs and tension face at critical section with CFS additionally, were proposed in this study to prevent the debonding of CFS. Other reinforcing detail, so called 'U-Shape fiber wrap at beam end' were included in this tests and comparisons were made between them.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.405-409
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• 2003

The effect of substitution of Gd ions for Ca ions in the B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$(C $a_{1-x}$ G $d_{x}$)$_{2.03}$ C $u_{3.06}$ $O_{ 10+{\delta}}$/ (x=0.0~0.06) was investigated by measuring x-ray diffraction patterns, lattice constants, do resistivity and Hall effect. We found the solubility limit of Gd in the 110 K phase to be x < 0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature $T_{c}$ gradually decreased with an increasing the Gd concentration x, corresponding to a small change of the carrier concentration.