• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.232-232
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• 2009

• 디지털융복합연구
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• 제12권12호
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• pp.37-47
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• 2014

이동통신 서비스 제공을 위한 필수적인 요소자원인 주파수는 그 대역의 특성에 따라 사업자의 서비스 제공 경쟁력을 크게 좌우할 수 있다. 이에 본 연구에서는 주파수 자원에서도 상대적으로 우수한 특성을 가져 서비스 제공 상 우위를 가지며 경쟁정책적인 관리가 필요한 이동통신 주파수 대역을 핵심 우량대역이라고 정의한다. 이를 위해서 기술적 특성이 아닌 시장상황을 고려한 주파수의 활용성 및 경제적 효율성 측면의 4가지 기준(글로벌소싱 및 호환성, 비용-효율성, 주파수 활용 경험, 현재의 활용가능성)을 수립하였다. 이러한 기준들을 순차적으로 적용하여, 우량 주파수 대역 후보들을 추출하고 단계적인 평가기준을 통해서 현재시점에서의 최종적인 핵심 우량대역을 식별하였다. 또한 이러한 결과는 기술의 발전과 시간의 흐름에 따라 변화하는 특성을 보여준다. 본 연구의 분석결과는 이동통신 주파수에 대한 경쟁관리정책뿐만 아니라 할당정책에도 논리적 근거로 활용될 수 있는 실용적 의의를 지닌다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.213-215
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• 2003

Multimedia has to carry data of heterogeous types. Multicast communication techniques can supply the most appropriate infrastructures to such multimedia. Of many multicast protocols, the core based tree (CBT) protocol is the most concentrative studies are conducted on. The CBT places a core router at center of the shared tree and transfers data through the tore router. However, the CBT has two problems due to centralizing all network traffics into a core router. First it can raise bottleneck effect at a core router. Second, it is possible to make an additive processing overhead when core router is distant from receivers. To cope with the problems, this paper proposes an intelligent anycast routing protocol. The anycast routing attempts to distribute the centralized traffic into plural core routers by using a knowledge-based algorithm. The anycast routing estimates the traffic characteristics of multimedia data far each multicast source, and achieves effectively the distributing that places an appropriate core router to process the incoming traffic based on the traffic information in the event that request of receivers are raised. This method prevent the additional overhead to distribute traffic because an individual core router uses the information estimated to multicast sources connected to oneself and the traffic processing statistics shared with other core neuters.

• 한국정보과학회논문지:정보통신
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• 제28권4호
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• pp.586-601
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• 2001

본 논문에서는 에드 혹 망을 위한 메쉬 기반의 새로운 멀티캐스트 라우팅 프로토콜인 HMMRP (Hierarchical Mesh-based Multicast Routing Protocol)를 제안한다. HMMRP는 송신원 중 일부를 코어 송신원으로 두고 타 송신원들이 코어 송신원 중 하나에 반드시 연결되도록 한다. 그리고 송신원별 트리의 합집합으로 구성되는 메쉬에 의해 송신원과 수신원이 연결되도록 한다. HMMRP는 이들 연결 경로 상의 노드들로써 데이타 전달 메쉬를 형성하고 이를 정기적으로 재구성한다. 특히, 일반 송신원으로부터 코어 송신원에 이르는 경로와 코어 송신원으로부터 수신원에 이르는 트리에 해당하는 메쉬에 대해서는 정기적인 재구성 기간보다 훨씬 짧은 기간마다 국부적으로 메쉬 단절 가능성을 감시하고 복구하도록 함으로써, 임의의 송신원 수신원간에 최소한 송신원 코어 수신원을 경유하는 메쉬를 통해 데이타를 전달할 수 있도록 한다. 이렇게 함으로써 이동성이 높은 에드 혹 네트워크일지라도 정기적인 메쉬 재구성 기간을 짧게 잡지 않고 높은 데이타 전달율을 제공할 수 있다. 시뮬레이션을 통한 성능 분석 결과，HMMRP는 이동성에 대한 성능저하가 상대적으로 적으며, 특히 멀티캐스트 그룹의 규모가 커질수록 이동성에 대한 성능저하가 더욱 경미해짐을 알 수 있었다.

• IEIE Transactions on Smart Processing and Computing
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• 제5권3호
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• pp.169-177
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• 2016

To realize high-speed intrusion detection by accommodating many regular expression (regex)-based signatures and growing network link capacities, we propose the Service TimE-Aware Load-balancing (STEAL) algorithm. This work is motivated from the observation that utilization of a many-core network intrusion detection system (NIDS) is influenced by unfair computational distribution among many-core NIDS nodes. To avoid such unfair computational distribution, STEAL is designed to dynamically distribute a large volume of traffic among many-core NIDS nodes based on packet service time, which is represented by the deep packet time in many-core NIDS nodes. From experiments, we show that compared to the commonly used load-balancing algorithm based on arrival rate, STEAL increases the number of received packets (i.e., decreases the number of dropped packets) in many-core NIDS. Specifically, by integrating an open source NIDS (i.e. Bro) with STEAL, we show that even under attack-dominant traffic and with many signatures, STEAL can rapidly improve the performance of many-core NIDS to realize high-speed intrusion detection.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.673-682
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• 2018

One of the most widely used methods to estimate core damage during a nuclear power plant accident is containment radiation measurement. The evolution of severe accidents is extremely complex, leading to uncertainty in the containment dose rate (CDR). Therefore, it is difficult to accurately determine core damage. This study proposes to conduct uncertainty analysis of CDR for core damage assessment. First, based on source term estimation, the Monte Carlo (MC) and point-kernel integration methods were used to estimate the probability density function of the CDR under different extents of core damage in accident scenarios with late containment failure. Second, the results were verified by comparing the results of both methods. The point-kernel integration method results were more dispersed than the MC results, and the MC method was used for both quantitative and qualitative analyses. Quantitative analysis indicated a linear relationship, rather than the expected proportional relationship, between the CDR and core damage fraction. The CDR distribution obeyed a logarithmic normal distribution in accidents with a small break in containment, but not in accidents with a large break in containment. A possible application of our analysis is a real-time core damage estimation program based on the CDR.

• 천문학논총
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• 제29권2호
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• pp.29-34
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• 2014

We have observed the deuterated methanol, $CH_3OD$, toward the hot core MM1 in the massive star-forming region DR21 (OH) using the Submillimeter Array with a high angular resolution of about 1 arcsecond. The position of the hot core associated with the sub-core MM1a was confirmed to coincide with the continuum peak where an embedded young stellar object is located. The column density of $CH_3OD$ was found to be about $(2{\pm}1){\times}10^{16}cm^{-2}$ toward the MM1a center. The abundance ratio $CH_3OD/CH_3OH$ was measured to be ~ 0.45, which is about the median value for low mass star-forming cores but much larger than those of the massive star-forming cores. The ratio is believed to change depending on, for example, the chemical condition, the temperature and the density of the source. This ratio may further depend on the evolutionary phase especially in the massive-star-forming cores. The sub-core MM1a is thought to be in the very early phase of star formation. This large abundance ratio found in this source indicates that even the massive star-forming cores, during a relatively short period in the very early stage of star formation, may also show a chemical state resulted from the cold and dense pre-collapsing phase, the enhanced deuteration as found in low mass star-forming cores.

• 한국분말재료학회지
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• 제14권2호
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• pp.132-139
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• 2007

In the Ti(CN)-Co/Ni cermet, WC is an effective additive for increasing sinterability and mechanical properties such as toughness and hardness. In this work, WC, (WTi)C and (WTi)(CN) were used as the source of WC and their effects were investigated in the respect of microstructural evolution and mechanical properties. Regardless of the kinds of WC sources, the hard phase with dark core and bright rim structure was observed in the Ti(CN)-Co/Ni cermet under the incorporation of relatively small amount of WC. However, hard phases with bright core began to appear and their frequency increased with the increase of all kinds of WC source addition. The ratio of bright core to dark one in the (TiW)(CN)-Co/Ni cermet was greatest under the incorporation of (WTi)C compared at the same equivalent amount of WC. The mechanical properties were improved with the addition of WC irrespective of the kinds of sources, but the addition of (WTi)(CN) was less effective for the increase of fracture toughness.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.245-256
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• 2014

I-core sandwich panel that has been used more widely is assembled using high power $CO_2$ laser welding. Kim et al. (2013) proposed a circular cone type heat source model for the T-joint laser welding between face plate and core. It can cover the negative defocus which is commonly adopted in T-joint laser welding to provide deeper penetration. In part I, a volumetric heat source model is proposed and it is verified thorough a comparison of melting zone on the cross section with experiment results. The proposed model can be used for heat transfer analysis and thermal elasto-plastic analysis to predict welding deformation that occurs during laser welding. In terms of computational time, since the thermal elasto-plastic analysis using 3D solid elements is quite time consuming, shell element model with multi-layers have been employed instead. However, the conventional layered approach is not appropriate for the application of heat load at T-Joint. This paper, Part II, suggests a new method to arrange different number of layers for face plate and core in order to impose heat load only to the face plate.

• 천문학회지
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• 제27권1호
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• pp.1-11
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• 1994

We have observed the emission of $HC_3N$ J=4-3, 5-4,10-9 and 12-11 transitions toward the Sgr B2 central region in an area of $150'\times150'$ with resolutions of 16'-48'. The intensities and central velocities of line profiles show significant variations with positions. In contrast to the intensities of the low J-level transitions which gradually increase from the central source toward the outside region, the $HC_3N$ emission of the high J-level transition become stronger toward 'the central radio continuum source MD5. Systematic change in the radial velocity of each line profile occurs along north-south direction. There are a few peaks in most line profiles, and these indicate that there are multiple velocity components along the line of sight. Distributions of excitation temperature and column density which were estimated from the excitation calculations show the existence of a small $(1\times2pc),\;hot\;(T_{ex}>50K)$ core which contains two temperature peaks at-15' east and north of MD5. The column density of $HC_3N\;is\;(1-3)\times10^{14}cm^{-2}$ Column density at distant position from MD5 is larger than that in the central region. We have deduced that this 'hot-core' has a mass of 105M 0, which is about an order of magnitude larger than those obtained by previous studies.