• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.17-20
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• 2017

실시간 마이그레이션은 데이터 센터 내에서 자원을 효율적으로 관리할 수 있도록 하는 기술이다. 그러나 대부분의 연구는 마이그레이션 Metric간 Trade-off를 고려하고 있지 않아 Qos저하의 우려가 있기 때문에 서비스 목적에 따라 다수의 Metric을 고려해야한다. 마이그레이션 시 고려되는 요소들을 분류하고 이를 복합적으로 고려할 수 있는 퍼지이론 기반의 마이그레이션 기법을 제시하고자 한다. 또한 향후 연구에 대해서도 논의한다.

• Maritime Security
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• v.1 no.1
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• pp.119-148
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• 2020

The purpose of this study is to examine the perceptions of neighboring countries on the gray zone and to explore Korea's maritime strategy. The concept of gray zones appears in various ways from country to country. In international relations, the gray zone is a comprehensive space between war and peace. The gray zone in the ocean is an unstable space in which competition between the US and China is represented and proxy wars are possible, and the gray zone needs strategic management. This study summarizes the concept of gray zones in the maritime security field, examines the gray zone strategies of neighboring countries, and suggests Korea's gray zone strategies. In particular, the recognition of the gray zone itself is the core of the problem, and it is necessary to strengthen information sharing to clarify the problem about the gray zone and accurately recognize the gray zone situation. The CMG(Complex Maritime Geostrategy) framework attempted in this study is expected to be helpful in understanding the nature of various gray zone issues around Korea and preparing for a geostrategy based on the analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.686-689
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• 2004

As the demands of X-Y linear motors increase, it becomes very important to measure flatness errors and to compensate them. In this study, in order to investigate flatness errors, a laser interferometer is used for measurement. To improve the measurement efficiency, a Union Jack method is adopted instead of a square method. The square method is frequently used because of its accuracy, but it requires many measurement points. In this study, the Union Jack method with Grey Theory is used. By using the Grey Theory, unmeasured data are predicted, and these are compared with results of the square method. The results show that the Union Jack method with Grey Theory is accurate enough to replace the square method.

• The Journal of the Acoustical Society of Korea
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• v.5 no.1
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• pp.41-48
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• 1986

본 논문에서는 그레이디드 인덱스 다중모드 광섬유에 압력을 가함으로써 발생되는 마이크로벤딩 을 모드결합 이론으로 서술하였다. 그 이론에 의하여 모드결합이 최적으로 일어나는 정적벤딩을 통한 주기성을 얻어 시제품 광섬유 음향 트랜스듀서를 설계 및 제작하였다. 제작된 트랜스듀서의탐지 가능한 최소검출압력을 정적벤딩 실험을 통하여 계산하였으며, 아울러 제작된 광섬유 음향 트랜스듀서의 특성 을 실험하였다.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.452-465
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• 2016

In this study, the structure of a concave annular array transducer was optimized to generate high intensity focused ultrasound for medical therapeutic application. The transducer has a phased array structure composed of several concentric channels that have 40 mm as the radius of curvature. We derived theoretical equations to analyze the sound field of the transducer and verified the validity of the equations by comparing the results calculated by the equations with those from finite element analyses. We also checked the possibility of dynamic focusing at around the geometric focal point. Further, the level of a grating lobe occurring at an unwanted position in the transducer sound field was confirmed to be reducible through the relation between the number of channels and the frequency of the transducer. Hence, the structure of the transducer was optimized to place the main lobe within a specific range from the zenith while systematically reducing the level of the maximum sidelobe including the grating lobe. The designed structure showed the performance better than that targeted at all the focal points.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2558-2560
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• 2003

본 논문은 퍼지논리를 통해 얻어지는 경계값을 이용한 영상분할법에 관한 연구이다. 영상분할은 퍼지인식의 핵심기술 및 많은 응용분야에서의 전처리과정에 사용되고 있어 그 중요성이 강조되고 있는 추세이다. 본 논문의 주요 관점은 영상의 그레이레블(gary level)에 관련된 불분명한 정보들을 퍼지논리를 기반으로 하여 자동적으로 경계값을 획득하는 새로운 영상 분할법을 제안함에 있다. 본 논문에서 제안된 영상분할법은 영상의 히스토그램을 이용하여 계산된 경계값과 불분명한 정도인 퍼지정보를 영상분할에 적용한 것이다. 제안된 알고리즘은 이론 및 실험을 통하여 증명하였다.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.419-430
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• 2002

In this paper. we propose an efficient method for implementing hi-directional pixel-based focusing(BiPBF) based on a sparse array imaging technique. The proposed method can improve spatial resolution and frame rate of ultrasound imaging with reduced hardware complexity by synthesizing transmit apertures with a small number of sparsely distributed subapertures. As the distance between adjacent subapertures increases, however. the image resolution tends to decrease due to the elevation of grating lobes. Such grating lobes can be eliminated in conventional synthetic aperture imaging techniques. On the contrary, grating lobes arisen from employing sparse synthetic transmit apertures can not be eliminated, which has been shown analytically in this paper. We also propose the condition and method for suppressing the grating lobes below -40dB, which is generally required in practical imaging. by placing the transmit focal depth at a near depth and properly selecting the subaperture distance in Proportion to receive aperture size. The results of both the Phantom and in vivo experiments show that the proposed method implements two-wav dynamic focusing using a smaller number of subapertures, resulting in reduced system complexity and increased frame rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.49-49
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• 2004

고도화로 정밀해진 현대 과학기기에는 여러 가지 전자 팩키징 제품들이 쓰이고 있으나 이 제품들은 여러 가지 파손인자들의 영향 때문에 고유의 수명을 다하지 못하고 고장이 발생하게 된다. 전자부품 실장에 이용되는 솔더 조인트의 열화에 관련되는 열 피로와 이온 마이그레이션(Migration) 현상이 솔더 조인트의 신뢰성에 영향을 미치는 가장 중요한 인자로 알려져 있고 이러한 인자 이외에도 여러 가지 요인들이 복합적으로 작용하여 솔더의 접합부분에 피로파괴를 일으킨다.(중략)

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.6
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• pp.525-532
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• 2000

본 논문은 영상에서 형태적 정보를 추출하는데 사용되는 수학적 형태학(mathematical morphology)에 퍼지 집합 이론을 적용하여 새로운 퍼지 수학적 형태학을 제안한다. 일반적인 수학적 형태학은 이진 영상에만 적용되는 한계를 가지고 있었다. 이를 그레이 스케일 영상에도 적용 가능하도록 한 Sinha와 Dougherty[8]이 제안한 방법도 기하학적 형태 변환을 보장하지 못하는 결점이 있었는데 본 논문에서는 그 결점을 제거하는 새로운 수축(erosion)과 확장(dilation) 연산을 정의하고 그 특성을 연구하였다. 본 논문이 제안한 방법과 [8]의 방법을 실제 영상에 대한 실험으로 비교하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.806-812
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• 2000

In this paper, we theoretically studied on the large antenna array whose element had wider than one wavelength. And we also verified the adaptedness through the experiments. Using grating lobes, we could make antenna have sharp HPBW. Not only HPBW but also SLL could be controlled by giving optimal space for antenna array. In order to verify this method, we designed 4 horn antenna array and measured the radiation patterns at 9 GHz. Each horn antenna has the dimension of 64.3$\times$82.5$\textrm{mm}^2$ and HPBW of 27$^{\circ}$. The space between antennas is longer than one wavelength so that it may have the grating lobes in visible region. As a result of experiments, we could get HPBW of 4.3$^{\circ}$, 3.3$^{\circ}$ and 1.7$^{\circ}$when giving 2.5λ, 2.7λ and 3.0λ of the spacing respectively. We concluded this could be useful making the antenna with narrow HPBW.