• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.69-84
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• 2009

In this paper, a real-time web-casting framework for many individuals or small organizations imploring internet broadcasting, is designed and implemented. It is the purpose of the proposed framework that any individual can easily construct his own broadcast station if he has minimum facility for the content transmission to the framework. This type of system should have a flexible architecture to be applicable in wide variation of operational environment. Since the proposed framework follows a component-based hierarchical structure consisting of 3 types of components, it can effectively cope with change of internal or external operational environment by simple modification of the associated component with the change. Also, various types of target application systems in the aspects of cost and performance can be constructed in accordance with how to associate upper layer components with hardware platforms. A real prototype system based on the proposed framework is implemented, and then the response delay time is measured under varying number of content productions and content receivers. The results show that the response delay time follows M/M/1 model, which is one of the well-known performance models, and the implemented system may accommodate from 16 to 20 productions.

• Korean journal of food and cookery science
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• v.30 no.4
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• pp.454-462
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• 2014

This study aimed at the optimization and development of rice snack by response surface methodology (RSM). The effect of rice soaking time and additional ratio of soybean milk on physicochemical properties and sensory evaluation of dried rice flour for non-fried snack was studied. After soaking for 0 to 12 days, Baekjinju rice was milled and then air-dried. A quadratic model was selected for weight, volume, hardness, taste and appearance. Two-factor interaction model was selected for expansibility, color and overall preference. A linear model was selected for yellowness and flavor. Weight, hardness and appearance were increased and decreased thereafter as rice soaking time increased, but the volume was reversed. Expansibility, color, taste and flavor were decreased as rice soaking time increased, but yellowness was reversed. Weight and overall preference decreased as additional ratio of soybean milk increased, but volume, expansibility and yellowness were reversed. Hardness, taste and appearance were increased after initial decrease as additional ratio of soybean milk increased, color and flavor were not changed by additional ratio of soybean milk. The optimum conditions of each factor were set to where the rice soaking time and additional ratio of soybean milk were at their minimum. Weight, volume, expansibility, yellowness, hardness, color, taste, flavor, appearance and overall preference were established at maximum level where the objective of the optimum was in level. Our data indicated the statistically predicted values of the highest desirability was 1.24 day of rice soaking time and 15.80% of additional ratio of soybean milk.

• Journal of Drive and Control
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• v.11 no.4
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• pp.53-60
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• 2014

This paper proposes a control scheme to reduce the power consumption of a variable displacement swash-plate type piston pump supplying oil to a valve-controlled hydraulic cylinder at constant pressure. Whenever flow rate demand was absent, the swash plate angle and the pump speed were changed to the minimum values required to compensate for the internal leakage flow. In response to command signals, the pump speed was changed in proportion to the absolute mean value of the speed component for position commands. At the same time, a pressure regulator was activated to maintain constant system pressure by precisely adjusting the pump speed with the swash plate angle fixed at the maximum. The conventional system consisting of a pressure-compensated variable displacement type pump is driven at a constant speed of 1,800rpm. By comparison, computer simulation and experimental results showed that idling power at stand-by status could be reduced by up to 70% by reducing the pump speed from 1,800rpm to 300rpm and the swash plate angle to the minimum.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.3
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• pp.43-50
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• 1984

A body form, which experiences minimum vertical wave-exciting forces in the vicinity of a prescribed wave frequency in water of finite depth, is obtained by an approximate method. Its configuration has the symmetry with respect to the vertical axis, expressed in terms of exponential functions. By distributing three-dimensional pulsating sources and dipoles on the immersed surface of the body, a velocity potential is determined and subsequently hydrodynamic forces including the 2nd-order time-mean drift forces are calculated. The dynamic behavior of the body moored in irregular waves is investigated numerically by using central difference method. Hereby irregular wave trains are simulated with examining its repeatability by comparing the resulting spectrum with original one. Numerical results indicated that the body form obtained from the present analysis possesses in general a favorable hydrodynamic characteristics in comparison with a spherical buoy and that the maximum excursion of the body can be significantly reduced by setting pre-tension of an appropriate amount in the mooring cable.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.375-382
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• 2011

There is no system to obtain the basic data and proceed data and user input interface is complex, thus there are some limitation to utilize the oil spill prediction model. It is difficult to build the scientific response strategy in order to respond oil spill accident rapidly because it is impossible to operate the oil spill prediction model any time. In this study, the optimum operational system for oil spil prediction model has been developed considering the present system. External real time data has been linked because of impossibility of building all basic data and minimum database has been build in this study. Through this data system, real time oil spill prediction model can be utilized. And the user interface has been designed to reduce the error of the interface between user and model and the output interface has been proposed to analyze the result of modeling at multidimensional aspect. While the system for oil spill prediction model as the result of this study has some uncertainties because of depending on external data, the thing that we can predict oil spill using operate the model rapidly as soon as the accident occurred can be meaning in the response field.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.491-498
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• 2017

GPS (global positioning system) is a popular system that provides location information by measuring arrival time difference at the receiver between several GPS satellite signals. GPS is widely used in commercial area as well as military systems. Reliable GPS signal reception is more important in the military applications such as guided missiles. However, since the carrier frequencies of the GPS signals are well known and the received power is extremely low, the GPS systems are vulnerable to intentional jamming attacks. To remove jammers while maintaining GPS signals at the received signals, a popular technique is an adaptive beam steering method based on array antenna. Among adaptive beam steering techniques, this paper considers MVDR (minimum variance distortionless response) algorithm, and proposes a new adaptive technique that preserves the received signals at desired directions, but removes the unknown jamming signals adaptively. The performance of the proposed method is verified through computer simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2917-2923
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• 2015

The three dimensional inelastic response characteristics of the standard school buildings depending on hysteresis models are reviewed. Three artificial earthquake records in accordance with KBC(Korea Building Code) are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with four hysteresis models. As results, story shear force is increased by maximum 27% and story drift ratio is increased by maximum 30% according to hysteresis models. Modified Takeda Model shows maximum story shear and story drift raio in longitudinal and short direction, expecting higher safety. Story shear shows minimum value with Clough Model in both directions and story drift ratio shows minimum with Takeda model in longitudinal and with Clough model in short direction, so these models are expected to decrease the safety ratio.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1539-1545
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• 2015

GPS (global positioning system) is a popular system that provides location information by measuring arrival time difference at the receiver between several GPS satellite signals. GPS is widely used in commercial area as well as military systems. Reliable GPS signal reception is more important in the military systems. However, since the carrier frequencies of the GPS signals are well known, the GPS receivers are vulnerable to intentional jamming attacks. To remove jammers but maintain GPS signals at the received signals, a popular technique is an adaptive beam steering method based on array antenna. Among adaptive beam steering techniques, this paper considers MVDR (minimum variance distortionless response) algorithm, and proposes a new adaptive technique that preserves the received signals at desired direction, but removes the jamming signals adaptively. The performance of the proposed method is verified through computer simulation.

• Geomechanics and Engineering
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• v.18 no.2
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• pp.141-151
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• 2019

In this paper, it is aimed to present a detail investigation about the comparison of static and dynamic behavior of historical masonry arch bridges considering different arch curvature. $G{\ddot{o}}derni$ historical masonry two-span arch bridge which is located in Kulp town, Diyarbakir, Turkey is selected as a numerical application. The bridge takes part in bowless bridge group and built in large measures than the others. The restoration projects were approved and rehabilitation studies have still continued. Finite element model of the bridge is constituted with special software to determine the static and dynamic behavior. To demonstrate the arch curvature effect, the finite element model are reconstructed considering different arch curvature between 2.86 m-3.76 m for first arch and 2.64 m-3.54 m for second arch with the increment of 0.10 m, respectively. Dead and live vehicle loads are taken into account during static analyses. 1999 Kocaeli earthquake ground motion record is considered for time history analyses. The maximum displacements, principal stresses and elastic strains are compared with each other using contour diagrams. It is seen that the arch curvature has more influence on the structural response of historical masonry arch bridges. At the end of the study, it is seen that with the increasing of the arch heights, the maximum displacements, minimum principal stresses and minimum elastic strains have a decreasing trend in all analyses, in addition maximum principal stresses and maximum elastic strains have unchanging trend up to optimum geometry.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.503-509
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• 2018

In this study, we used the ultrasonic extraction process as a method to extract antioxidant substances from kudzu, and measured the content of iso-flavonoids puerarin, daidzein, daidzin contained in kudzu. The response surface methodology which is a statistical analysis method for optimizing the extraction amount of iso-flavonoids from the kudzu and the process condition for maximizing the yield was applied. It is the final objective of this study to effectively derive the condition of the process that matches the target response with a minimum number of experiments and analyze the effect of each process condition on the response. In the response surface methodology, the central composite design was applied and the optimum condition was analyzed, and the three independent variables were set to ultrasonic irradiation time, volume ratio of ethanol/ultrapure water, ultrasonic irradiation power. Using the response surface methodology, the optimum conditions with the maximum extraction yield and the content of iso-flavonoids were evaluated as ultrasonic irradiation time (24.75 min), ethanol / ultrapure water volume ratio (39.75 vol%), ultrasonic irradiation power (592.36 W). The overall satisfaction level appears as high as 0.8938, which is recognized at a significance level within 5%. As a result of analyzing the optimization process, it was confirmed that the ultrasonic irradiation time is the factor that most affects the responses.