• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.189-198
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• 2009

The traditional interrupt-based protocol processing at end hosts has two priority-inversion problems. First, low-priority packets may interrupt and delay high-priority process executionssince interrupts have the highest priority in most operating systems. Second, low-priority packet may delay high priority packets when they arrive almost simultaneously since interrupt processing is performed in a FCFS (first come, first served) order. These problems can be solved by a priority-based protocol processing policy and implementation. However, general priority-based schemes commonly have the problem of starvation and cannot support the each network flow requiring the mutually exclusive QoS since the packets are processed in the FCFS order. Therefore, the priority-based schemes are not appropriate for different QoS-demanding applications. In this paper, we present a bottom-half-based approach that relies on priority- and budget-based processing. The proposed approach allows us to solve both the starvation and priority-inversion problems, and further enables effective QoS isolation between different network connections. This feature also enables bounding the protocol processing time at an end host. We finally show through experiments that the proposed approach achieves QoS isolation and control.

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.108-109
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• 2001

• Journal of Digital Convergence
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• v.15 no.6
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• pp.51-59
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• 2017

The role of government is to defend its lands and people from enemies. The range of that defense has now extended into the cyber domain, regarded as the fourth domain of the conventional defense domains (i.e., land, sea, sky, and universe). Traditionally, a government's intelligence power overrides that of its civilians, and government is exclusively responsible for defense. However, it is difficult for government to take the initiative to defend in the cyber domain because civilians already have a greater means for collecting information, which is known as being "intelligence inverse" in the cyber domain. To this end, we first define the intelligence inverse phenomenon and then analyze its main features. Then we investigate foreign countries' efforts to overcome the phenomenon and look at the current domestic situation. Based on these results, we describe the appropriate role of the National Intelligence Agency to handle cyber threats and offer a cyber threat intelligence model to share with civilians to help protect against these threats. Using the proposed model, we propose that the National Intelligence Agency should establish a base system that will respond to cyber threats more effectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1265-1271
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• 2009

본 연구에서는 강우의 시 공간적 분포의 불규칙한 변동성을 고려한 강우-유출예측모형을 위해 인공신경망(Artificial Neural Networks: ANNs)의 기법의 일종인 자기조직화(Self Organizing Map: SOM) 이론과 역전파 학습 알고리즘(Back Propagation Algorithm: BPA) 이론을 복합적으로 이용하였다. 기존의 인공신경망 연구에서 야기된 저 갈수기의 유출량에 대한 과대평가, 홍수기의 유출량에 대한 과소평가, 예측값이 연속적으로 선행 유출량을 나타내는 Persistence 현상을 해결하기 위하여 패턴분류 성능을 지닌 SOM 이론을 예측모형의 전처리 과정으로 이용하였다. 먼저, 본 연구에서 제안한 방법은 SOM에 의해 강우-유출 관계를 분류하고, SOM에 의한 분류에 따라 각각의 모형을 구성한다. 개별적으로 구축된 모형은 유출량의 예측을 위해 각각의 양상에 따라 분류된 자료를 이용한다. 결과적으로 본 연구에서 제안한 방법은 과거의 인공신경망의 일반적인 적용에 의한 결과보다 더 나은 예측능력을 보여주었으며, 더불어 유출량의 과소 및 과대추정과 Persistence 현상과 같은 문제점이 나타나지 않았다. 또한 강우량 및 유출량의 범위에 제한을 받지 않는 강우-유출예측 모형의 개발 및 홍수기로부터 갈수기까지의 보다 넓은 범위의 유출량의 예측에 기여할 것으로 기대된다.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.5
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• pp.490-495
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• 1999

In this paper. a learning method VoD-EBP for neural networks is proposed, which learn patterns by error back propagation. Based on Voronoi diagram, the method initializes the weights of the neural networks systematically, wh~ch results in faster learning speed and alleviated local optimum problem. The method also shows better the reliability of the design of neural network because proper number of hidden nodes are determined from the analysis of Voronoi diagram. For testing the performance, this paper shows the results of solving the XOR problem and the parity problem. The results were showed faster learning speed than ordinary error back propagation algorithm. In solving the problem, local optimum problems have not been observed.

• Journal of Korea Water Resources Association
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• v.45 no.9
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• pp.853-860
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• 2012

It is well-known that loop effect of the stage-discharge relationship is formulated based on many field observations especially for the sand rivers. Theoretical understandings of the loop effect for the sand rivers have been widely provided, based on the facts that it is driven by the flood wave propagation and bed form changes over the given flood period. However, very few theoretical studies or field observations associated with loop-rating curves in the gravel or rock-bed mountain streams have been attempted so far, due particularly to the difficulties in the accurate discharge measurement during the flood in such field conditions. The present paper aims to report a unique loop-rating curve measured at a gravel and rock-bed mountain stream based on the flood discharge observation acquired during the typhoon, Muifa that passed nearby Jeju Island in summer of 2011. As velocity instrumentation, a non-intrusive Surface Velocity Doppler Radar to be suitable for the flood discharge measurement was utilized, and discharges were consecutively measured for every hour. Interestingly, the authors found that the hysteresis of the loop-rating curve was adverse compared to the typical trend of the sand bed streams, which means that the discharge of the rising limb is smaller than the falling limb at the same stage. We carefully speculate that the adverse trend of the loop-rating curve in the gravel bed was caused by the bed resistance change that works differently from the sand bed case.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.5
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• pp.498-504
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• 1984

가열된 곡면에 의한 자연대류에서는 유동의 박리현상이 존재하지 않음이 알려져 있다. 이에 반해 날카로운 모서리를 갖는 가열된 정방형 수평실린더에 의한 자연대류에서는 그라소프 수가 4.66*$10^{4}$ 전후로 부착 혹은 박리현상이 윗쪽 양 모서리 부근에서 일어남을 광학간섭 계(Mach Zehnder Inter-ferometer)를 이용하여 온도장을 가시화하고 이를 이용하여 좌우 대칭 선상에서의 속도분포를 간단한 대수적인 방법으로 구하여 수평정방형 윗쪽 수평면 위에 유동의 박리현상을 시사하는 "쌍동이 소용돌이"의 존재를 입증하였고, 이에 의해 온도역전현상과 평균 열전달량의 급격한 증가를 설명 할 수 있다.설명 할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.479-484
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• 2005

본 논문에서는 오류 역전파 알고리즘에서 은닉층의 노드 수를 설정하는 문제와 ART1의 경계 변수의 설정에 따른 인식률이 저하되는 문제점을 개선하기 위해 ART1 알고리즘과 퍼지 단층 지도 학습 알고리즘을 결합한 ART1 기반 퍼지 지도 학습 알고리즘을 제안한다. 제안된 알고리즘은 가중치 조정에 승자 뉴런 방식을 도입하여 은닉층에 해당하는 클래스에 영향을 끼친 패턴들의 정보만 저장하게 하여 은닉층 노드로의 책임 분담에 의한 정체 현상이 일어날 가능성을 줄인다. 그리고 학습시간과 학습의 수렴성도 개선한다. 제안된 알고리즘의 학습 성능을 분석하기 위하여 주민등록번호 분류를 대상으로 실험한 결과, 제안된 방법이 기존의 신경망보다 경계 변수나 모멘트에 민감하지 않으며 학습 시간도 적게 소요되고 수렴성도 우수한 성능이 있음을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.6
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• pp.64-74
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• 2010

This paper proposes a new TR-based baseline-free SHM technique in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM technique has two distinct features when compared with the other TR-based SHM techniques: (1) The backward TR process commonly conducted by the measurement is replaced by the computation-based process; (2) In place of the comparison method, the TOF information of the damage signal extracted from the reconstructed signal is used for the damage diagnosis in conjunction with the imaging method which enables us to represent the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1397-1402
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• 2008

In this paper, damage detection method by using the time reversal is developed to detect damage on composit structures. The time reversal was investigated for direct root between PZT and PZT, but in case of a circular PZT, lamb wave moves not only along the direct root but also another roots. The center frequency of lamb wave is kept when the lamb waves are reflected from damage. This paper presents experimental and theoretical results for the new structural health monitoring method by above features of lamb wave, and we can increase accuracy of the new structural health monitoring method by using STFT(Short Time Fourier Transform).