• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.415-423
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• 1990

In a laboratory model the response of the boundary layer flow over topography is studied in a rotating sliced cylinder by employing the source-sink analogy with Ekman layer dynamics. The boundary layer flow is produced by two different fluid. In the first experiment homogeneous fluid is used both for the source and the working fluid of the container. In the second experiment a denser fluid is used for the source with the same working fluid. For the homogeneous western boundary layer flow both the northward and the southward flow were affected by the topography(ridge) to produce a cyclonic motion near the ridge. When woughward moving heavy boundary flow of slower speed and the northward moving faster flow were present at the same time, the splitting of southward flow and the separating of the northward flow were observed with a cyclonic motion at the ridge. The most important factor that influence production of the cyclonic motion has been turned out to be the presence of the topography in the western boundary layer. In particular the role of the southward moving heavy flow over the interior flow pattern was found to be very significant.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1054-1056
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• 1999

It is necessary to install the arc generation facility to obtain the important technology for the design of breakers and switches, and the improvement of their performance and reliability. With this facility it is possible to study the characteristics of Arc in air/gas/vacuum insulation environment. The arc generation facility briefly consists of capacitor bank which can charge enormous energy, an air-core reactor, and several measurement equipments. This facility can simulates the arc phenomena in breakers and switches by means of generating high currents. In order to the protect electrode damage during the arcing time in arc extinguishing chamber, we installed auxiliary current source in addition to main capacitor bank, This auxiliary current source produces relatively small arc between electrodes before high current generation by main capacitor bank. Therefore it is possible to observe and measure the arcing phenomenon without damage of electrodes.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.304-317
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• 2016

An accelerator-driven system consists of a subcritical reactor and a controllable external neutron source. The reactor in an accelerator-driven system can sustain fission reactions in a subcritical state using an external neutron source, which is an intrinsic safety feature of the system. The system can provide efficient transmutations of nuclear wastes such as minor actinides and long-lived fission products and generate electricity. Recently at Kyoto University Research Reactor Institute (KURRI; Kyoto, Japan), a series of reactor physics experiments was conducted with the Kyoto University Critical Assembly and a Cockcrofte-Walton type accelerator, which generates the external neutron source by deuteriu-metritium reactions. In this paper, neutronic analyses of a series of experiments have been re-estimated by using the latest Monte Carlo code and nuclear data libraries. This feasibility study is presented through the comparison of Monte Carlo simulation results with measurements.

• Journal of the Korean Society of Food Culture
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• v.36 no.3
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• pp.265-273
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• 2021

The Chinese Sigyeong records the foods of the Primitive Pickling Period, pickling being a universal vegetable storage method, but does not indicate the origin of the pickled vegetables or the location of the source of transmission. Kimchi mainly used salt and sauce-based soaking materials at the beginning of the Fermented Pickling Period (beginning in the 1st to 3rd centuries A.D.), and it differed from the Chinese method, which used alcohol and vinegar. In the Umami-Flavored Pickling Period (beginning in the 14th and 15th centuries A.D.), jeotgal, fermented seafoods, were added, and pickles with a completely new identity were created, one different from any other pickles in the world. Lastly, entering the Complex Fermentation and Pickling Period (beginning in the 17th and 18th centuries), the technical process evolved using a separate special seasoning containing red pepper as the secondary immersion source after pickling in brine, the primary immersion source. As a result of this, kimchi was transformed into a food with a unique form and taste not found anywhere else. The unique characteristic of kimchi is that the composition of original materials, a combination of salted marine life and vegetable ingredients, is its core identity, and there is a methodological difference in that it is completed through a second process called saesaengchae (生菜)-chimchae (沈菜).

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2395-2403
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• 2024

With the rapid development of DC high voltage accelerator, higher requirements have been raised for the design of DC high voltage power supply, requiring more stable high voltage with lower output ripple. Therefore, it also puts forward higher requirements for the parameter design of the voltage doubling rectifier circuit, which is the core component of the DC high voltage power supply. In order to obtain output voltage with better performance, the effects of the working frequency, the stage capacitance and the load resistance on the output voltage of the voltage doubling rectifier circuit are studied in detail by simulation. It can be concluded that the higher the working frequency of the transformer, the larger the stage capacitance, the larger the load resistance and the better the output voltage performance in a certain range. Based on this, a 2.5 MV voltage doubling rectifier circuit driven by a 120 kHz frequency transformer is designed, developed and tested for the power supply of the neutron source device towards BNCT. Experimental results show that this voltage doubling rectifier circuit can satisfy the design requirements, laying a certain foundation for the engineering design of DC high voltage power supply of neutron source device.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.9-22
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• 2006

When the legacy multicast routing protocols are adopted in If-based mobile core networks, there are some problems such as traffic injection from unnecessary sources, traffic overhead by group management and router performance degradation by large amount of multicast session information. In this paper, we propose a stateless multicast mechanism which has no need to maintain multicast information for session status and reduces redundant network overhead for maintaining multicast tree. In addition interworking with IGMPv3 gets rid of traffic from unnecessary sources which have no registration from receivers. The operations of essential components including a gateway node for interworking with the legacy Internet multicast network, a gateway node for transparency to radio access network and a intermediate node in mobile core networks, are definitely defined and the proposed communication architecture is completed. Finally we evaluate and approve the performance of the proposed architecture by means of well-designed network simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4145-4164
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• 2016

Energy harvesting is an increasingly attractive source of power for cellular networks, and can be a promising solution for green networks. In this paper, we consider a cellular network with power beacons powering multiple mobile terminals with microwave power transfer in energy beamforming. In this network, the power beacons are powered by grid and renewable energy jointly. We adopt a dual-level control architecture, in which controllers collect information for a core controller, and the core controller has a real-time global view of the network. By implementing the water filling optimized power allocation strategy, the core controller optimizes the energy allocation among mobile terminals within the same cluster. In the proposed green energy cooperation paradigm, power beacons dynamically share their renewable energy by locally injecting/drawing renewable energy into/from other power beacons via the core controller. Then, we propose a new water filling optimized green energy cooperation management strategy, which jointly exploits water filling optimized power allocation strategy and green energy cooperation in cellular networks. Finally, we validate our works by simulations and show that the proposed water filling optimized green energy cooperation management strategy can achieve about 10% gains of MT's average rate and about 20% reduction of on-grid energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4411-4431
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• 2014

Mobile ad hoc networks (MANETs) have recently gained increased interest due to the widespread use of smart mobile devices. Group communication applications, serving for better cooperation between subsets of business members, become more significant in the context of MANETs. Multicast routing mechanisms are very useful communication techniques for such group-oriented applications. This paper deals with multicast routing problems in terms of stability and scalability, using the concept of stable core. We propose LMRSC (Lightweight Multicast Routing Based on Stable Core), a lightweight multicast routing technique for MANETs, in order to avoid periodic flooding of the source messages throughout the network, and to increase the duration of multicast routes. LMRSC establishes and maintains mesh architecture for each multicast group member by dividing the network into several zones, where each zone elects the most stable node as its core. Node residual energy and node velocity are used to calculate the node stability factor. The proposed algorithm is simulated by using NS-2 simulation, and is compared with other multicast routing mechanisms: ODMRP and PUMA. Packet delivery ratio, multicast route lifetime, and control packet overhead are used as performance metrics. These metrics are measured by gradual increase of the node mobility, the number of sources, the group size and the number of groups. The simulation performance results indicate that the proposed algorithm outperforms other mechanisms in terms of routes stability and network density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.56-59
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• 2004

HgTe and HgTe/CdTe core-shell structured nanocrystals(NCs) were synthesized in aqueous solution by colloidal method. HgTe and HgTe/CdTe NCs structure showed very similar XRD patterns because of the same lattice constant and crystal structure of both samples. The absorption and photoluminescence(PL) spectrum of the synthesized HgTe NCs revealed the strong exitonic peak in the IR region. The PL spectrum of HgTe/CdTe NCs have the intense peak in about 700nm shorter than that of HgTe by 400nm. The photocurrent measurement of colloidal NCs are performed using He-Ne laser for light source. The photocurrent of HgTe NCs shows the instant increased current response to light, but HgTe/CdTe NCs revealed a decreased current when lighted to the sample. In the vacuum condition, it shows reverse result that current increased under the illumination of light and it is thought that the molecules like the hydro-oxygen gas in the air give an important effect on the current mechanism.

• Korean Journal of Remote Sensing
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• v.21 no.1
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• pp.91-98
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• 2005

On board satellite magnetometer measures all possible magnetic components, such as the core and crustal components from the inner Earth, and magnetospheric, ionospheric and' its coupled components from the outer Earth. Due to its dipole and non-dipole features, separation of the respective component from the measurements is most difficult unless the comprehensive knowledge of each field characteristics and the consequent modeling methods are solidly constructed. Especially, regional long wavelength magnetic signals of the crust are strongly masked by the main field and dynamic external field and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar region relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects that are closely related to the geomagnetic storms affecting ionospheric current disturbances. To help isolate regional lithospheric anomalies from core field components, the correlations between CHAMP magnetic anomalies and the pseudo-magnetic effects inferred from satellite gravity-derived crustal thickness variations can also be exploited, Isolation of long wavelengths resulted from the respective source is the key to understand and improve the models of the external magnetic components as well as of the lower crustal structures. We expect to model the external field variations that might also be affected by a sudden upheaval like tsunami by using our algorithm after isolating any internal field components.