• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.10-17
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• 2005

An experimental study was conducted at a Mach number of 2.0 to investigate the buzz suppression method on an axisymmetric, external compression supersonic inlet. The inlet model has a fixed geometry with no internal contraction. The inlet configuration was altered by changing the cowling. Results show that source of buzz has been related to the existence in the flow field of velocity discontinuity across a vortex sheet which originates from a shock intersection point. With external compression inlet, buzz can be suppressed by positioning the oblique shock slightly inside or outside of the cowl.

• Journal of information and communication convergence engineering
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• v.11 no.1
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• pp.30-44
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• 2013

Traffic congestion has become a serious problem with the recent exponential increase in the number of vehicles. In urban areas, almost all traffic congestion occurs at intersections. One of the ways to solve this problem is road expansion, but it is difficult to realize in urban areas because of the high cost and long construction period. In such cases, traffic signal control is a reasonable method for reducing traffic jams. In an actual situation, the traffic flow changes randomly and its randomness makes the control of traffic signals difficult. A prediction of traffic jams is, therefore, necessary and effective for reducing traffic jams. In addition, an autonomous distributed (stand-alone) point control of each traffic light individually is better than the wide and/or line control of traffic lights from the perspective of real-time control. This paper describes a stochastic optimum control of crossroads and multi-way traffic signals. First, a stochastic model of traffic flows and traffic jams is constructed by using a Bayesian network. Secondly, the probabilistic distributions of the traffic flows are estimated by using a cellular automaton, and then the probabilistic distributions of traffic jams are predicted. Thirdly, optimum traffic signals of crossroads and multi-way intersection are searched by using a modified particle swarm optimization algorithm to realize real-time traffic control. Finally, simulations are carried out to confirm the effectiveness of the real-time stochastic optimum control of traffic signals.

• Journal of the Korean institute of surface engineering
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• v.29 no.2
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• pp.140-145
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• 1996

Silver deposits formed on copper substrates by replacement reactions show poor adhesion, and a silver film plated on such a deposit does not adhere. Silver ion makes a highly stable complex with cyanide ion, so that in a silver cyanide solution, the activity of silver ion is very small. This is one of the reasons for the universal use of cyanide baths in the industrial silver plating. However, the consideration of the difference between the values of the stability constants for bath the silver-iodide complex and the copper-iodide complex suggest that the rate of replacement deposition of silver on the copper substrate in si]ver-potassium iodide solution, could be comparatively low. To confirm this, the rate of replacement deposition of silver in both a silver-potassium iodide solution ($AgNO_3$0.10 mol/L, KI 2.00 mol/L ) and a strike silver plating bath (AgCN 0.028 mol/L, KCN 1.15 mol/L ) was estimated from the current density corresponding to the point of intersection of the anodic and the cathodic polarization curves. These estimated values were almost the same, and it is suggested that the silver-potassium iodide solution is not only a cyanide free silver plating bath capable of employing a copper substrate but a silver plating bath which requires no strike plating.

• Journal of the Korean Institute of Navigation
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• v.20 no.4
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• pp.59-70
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• 1996

A berth assignment problem has a direct impact on assessment of charges made to ships and goods. In this paper, we concerned with of fuzzy mathematical programming models for a berth assignment problem to achieved an efficient berth operation in a fuzzy environment. In this paper, we focus on the berth assignment programming with fuzzy parameters which are based on personal opinions or subjective judgement. From the above point of view, assume that a goal and a constraint are given by fuzzy sets, respectively, which are characterized by membership functions. Let a fuzzy decision be defined as the fuzzy set resulting from the intersection of a goal and constraint. This paper deals with fuzziness in all parameters which are expressed by fuzzy numbers. A fuzzy parameter defined by a fuzzy number means a possibility distribution of the parameters. These fuzzy 0-1 integer programming problems are formulated by fuzzy functions whose concept is also called the extension principle. We deal with a berth assignment problem with triangular fuzzy coefficients and propose a branch and bound algorithm for solving the problem. We suggest three models of berth assignment to minimizing the objective functions such as total port time, total berthing time and maximum berthing time by using a revised Maximum Position Shift(MPS) concept. The berth assignment problem is formulated by min-max and fuzzy 0-1 integer programming. Finally, we gave the numerical solutions of the illustrative examples.

• Water for future
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• v.29 no.1
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• pp.203-212
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• 1996

The subject research attempts to develop a new temporal interpolation scheme for the method of characteristics. The proposed three-point time-line Lagrange interpolation Reachback (3PR) method is a temporal quadratic interpolation scheme using the three grid points near the intersection between a characteristic line and a previous time-line. The accuracy of the 3PR method is compared with those of temporal and spatial interpolation schemes such as Reachback, Upwind, and quandratic spatial interpolation methods for two pure advection problems. The results show that on the aspects of the numerical damping and/or oscillation the temporal interpolation schemes are better than the spatial ones under the same interpolation order conditions. In addition, the spatial ones under the same interpolation order conditions. In addition, the proposed 3PR method improves the accuracy of Reachback method as well as it contains the merits of time-line interpolation schemes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.1-13
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• 2005

Kinematics of grasping and manipulation by a multi-fingered robotic hand where multi-fingertip surfaces are in contact with an object is solved. The surface of the object was represented by B-spline surfaces in order to model the objects of various shapes. The fingers were modeled by cylindrical links and a half ellipsoid fingertip. Geometric equations of contact locations have been solved for all possible contact combinations between the fingertip surface and the object. The simulation system calculated joint displacements and contact locations for a given trajectory of the object. Since there are no closed form solutions for contact or intersection between these surfaces, kinematics of grasping was solved by recursive numerical calculation. The initial estimate of the contact point was obtained by approximating the B-spline surface to a polyhedron. As for the simulation of manipulation, exact contact locations were updated by solving the contact equations according to the given contact states such as pure rolling, twist-rolling or slide-twist-rolling. Several simulation examples of grasping and manipulation are presented.

• Journal of Korea Multimedia Society
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• v.17 no.10
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• pp.1220-1228
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• 2014

Emergency Warning Service will be the most important service of VANET. Transmission delay is the most important performance criteria of the warning service. Most legacy research takes a way to minimize the packet collision. However those approach has a critical weak point on urban environment where there is a blind area of electric wave. So another issue is required in order to provide enhanced warning message propagation technique to overcome the urban environment problem. In this paper, I proposed an enhanced warning message propagation scheme in the poor electric wave environment as the intersection area. Proposed scheme forwards the warning message to the blind area by enhanced forwarding node selection technique. For efficiency of warning message propagation, I suggest forwarding priority for decision of forwarding node. And the node has a direct mode or redirect mode depending on neighbor nodes. The simulation was carried out to evaluate the performance. The simulation results show that proposed scheme has the superior performance compared to legacy warning message technique.

• Cross-Cultural Studies
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• v.26
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• pp.43-71
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• 2012

In this article, we recognize the cross-cultural communication between Greece and Spain through El Greco's pictures. The Greeks of Crete kept to their culture and continued to look to the declining Byzantine Empire for spiritual and political guidance. For two centuries after the conquest, the strength of the Byzantine tradition had become the moral and spiritual sustenance of the conquered in Crete. The basic contribution of Cretan intellectuals or artists such as El Greco of the fifteenth and sixteenth centuries was the forging of connecting links between the Hellenism of the old Byzantine East and the rising, youthful Hellenism of the Renaissance West. In this way, Crete served as an important halfway point between East and West. The saint Mary Magdalene was symbol of Christian penitence, which represents the penitential life personified and became widespread during the Counter Reformation, when new emphasis was put on the value of prayer and repentance in the forgiveness of sin. In Spain, the Penitent Magdalene was popular and El Greco painted many versions, which at the first time, were reflected by Tiziano, on the contrary, at the time of Toledo, were recreated by his own style. Although El Greco was converted to Catholic in Spain, his faith in Greek Orthodox Church influenced on his original painting world. El Greco had never painted a picture whose subject treat with the emphasis of identification between Mary Magdalene and Mary, younger sister of Martha.

• Journal of architectural history
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• v.28 no.4
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• pp.17-26
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• 2019

After opening Suwon railway station in 1905, a new road was constructed between Suwon station and Paldalmun(the South gate). It was the starting point to change urban structures of Suwon and shape the new city scape. In 1914, administrative districts of Suwon were reorganized. Suwon-myeon (township, a subdivision of Suwon-gun) was promoted to Suwon-eup(town) in 1931. Suwon-eup expanded its territory and changed the address system from 'li(里)' system to Japanese address system, 'Jeong(町)' in 1936. From 1920s, road system was changed and transformed Suwon's urban structures. A straight road was built from Jongro intersection to Janganmun(the north gate) in 1928. Another straight road was constructed between Suwon station to Padamun in the early 1930s. Public office buildings used the Hwa Seong HaengGung(華城行宮) and some of building moved to new location with new buildings. Main buildings of most schools in Suwon were reconstructed since 1930s. Commercial buildings and stores were sprung up and had their own characteristics by region. Around Suwon station, there are more hotels and restaurants than other areas. Rearranging administrative areas, developing road system and new buildings transformed Suwon's spatial structures. Constructing new roads formed a straight road passing through Suwon. After reorganizing administrative areas, this road turned to be the central axis of Suwon. Buildings in new style on the axis made the modern cityscape in Suwon.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.601-607
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• 2022

In recent years, monitoring of spent nuclear fuel inside dry cask storage has become an important area of national security. Muon tomography is a useful method for monitoring spent nuclear fuel because it uses high energy muons that penetrate deep into the target material and provides a 3-D structure of the inner materials. We designed a muon tomography system consisting of four 2-D position sensitive detector and characterized and optimized the system parameters. Each detector, measuring 200 × 200 cm², consists of a plastic scintillator, wavelength shifting (WLS) fibers and, SiPMs. The reconstructed image is obtained by extracting the intersection of the incoming and outgoing muon tracks using a Point-of-Closest-Approach (PoCA) algorithm. The Geant4 simulation was used to evaluate the performance of the muon tomography system and to optimize the design parameters including the pixel size of the muon detector, the field of view (FOV), and the distance between detectors. Based on the optimized design parameters, the spent fuel assemblies were modeled and the line profile was analyzed to conduct a feasibility study. Line profile analysis confirmed that muon tomography system can monitor nuclear spent fuel in dry storage container.