• 조명전기설비학회논문지
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• 제19권3호
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• pp.44-50
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• 2005

본 논문에서는 산화아연(이하 ZnO) 피뢰기 열화진행의 한 요인으로 예측되는 전극과 ZnO소자 사이에서 발생하는 방전광 현상에 관한 연구를 수행하였다. 이를 위해 $8/20[{\mu}s]$, 최대 10[kA]의 뇌임펄스전류를 발생시키는 뇌임펄스전류 발생장치를 설계${\cdot} $제작하였다. 실험결과, 상${\cdot}$하부의 전극 부근에서 발생하는 방전광의 형상은 인가되는 뇌임펄스의 극성에 따라 다르게 나타났으며 상대적으로 (-)극의 전극부근에서 방전광이 더 강하고 활발하게 발생하는 것으로 관찰되었다. 또한 전극의 면적에 따른 방전광의 세기는 전극의 면적이 증가할수록 감소하는 것으로 관측되었다. 동시에 전극과 소자의 접촉상태도 방전광의 발생과 매우 밀접한 관계가 있는 것으로 확인되었다. 따라서 배전급 ZnO피뢰기의 기존 전극구조는 보완이 필요하며 ZnO피뢰기 제품의 성능향상 및 지속적인 성능유지를 위해서는 환형구조 대신 내부면적이 있는 원판구조로 교체하는 것이 바람직하다고 판단된다.

• 한국생산제조학회지
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• 제24권1호
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• pp.87-93
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• 2015

The dynamic responses of a telescope loaded on an STSAT-3 satellite were analyzed, and environmental tests were conducted to verify the reliability of the design. The space use telescope COMIS (compact imaging spectrometer) is a major payload of the STSAT-3 launched on November 21, 2013. Vibration responses such as the acceleration, displacement, and velocity with respect to random vibration and shock impulse inputs were obtained based on theoretical fundamentals in conjunction with finite element analysis. The main focus of this study was on developing technology for accurate and/or favorable modeling and analysis of the structure and fitting the results to that of experiments. Cutting-edge technology for manipulating the vibrations of a space use telescope is suggested.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권2호
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• pp.104-115
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• 2005

Median filters in the signal processing have been most widely used and have demonstrated the strongest effects. This paper proposes the adaptive median filters with noise detection. The proposed basic algorithm of the filters is to judge whether or not the noises exist on the ground of The Noise Judgment Standards. Just in case the existence of the noises is verified by the algorithm, it takes the median filter. In order to judge the existence of the noises by the algorithm, this paper introduced the noise detection method by local central variance. As a result of comparing and analyzing the features and performance of the proposed filters and the existing [5]-[10] filters on the same conditions, it was verified that the former proved to be better than the latter, Observed even by naked eyes, it was similar, too. Accordingly, it's proved that the adaptive median filters by local central variance are useful in removing the impulse noise of the median filter and reinforce the edge preservation ability.

• 한국실내디자인학회논문집
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• 제21권2호
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• pp.174-185
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• 2012

The purpose of this study is to suggest planning strategy of tenant mix for UEC based on the final result of tenant mix analysis of five different research cases. The following is the comprehensive explanation about the result of tenant mix planning strategy for UEC currently in operation and when planning a new facility. First, overall research cases in this study show the tendency of following an old tradition, which stresses direct sales focusing on retail and dining adaptation. In order to compensate the defect, it is suggested to adopt new type of tenants with the functional mix of retail and dining with entertainment rather than decreasing the proportion of retail and dining tenant and increasing it of entertainment tenant. Second, the floorplan of UEC should adopt racetrack or circuit form that can stimulate shoppers' circular movement so to expose them to as much tenants as possible. Service consumption mode related tenants are required to place on the side or the edge of UEC, while retail consumption mode related tenants should be planned in the center. Among dining consumption mode related tenants, impulse dining tenants like a coffee shop should be placed at the turning point or at the end of the pathway, destination tenants like a restaurant and a food court, on the other hand, is needed to be placed in the center of the space. In case of Entertainment related tenants, destination tenants like bookstore or multiplex should also be placed at the end of the pathway, and on the way to those tenants, it is required to place general tenants that can share target customers with them. On the contrary, game center or record shop like tenants that can stimulate impulse sales should be placed on the visitor's main move or near the other destination tenants. Third, anchor tenants play an important role in gathering people to the UEC, and then induce them to visit the other tenants that are located near the anchors. Thus it is suggested to plan to place general tenants on the same floor as anchor tenants are placed so they can share the characteristics of target customers which create synergy effect.

• Coupled systems mechanics
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• 제8권4호
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• pp.315-338
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• 2019

The numerical investigations have been carried out on reinforced concrete slab against blast loading to demonstrate the accuracy and effectiveness of the finite element based numerical models using commercial package ABAQUS. The response of reinforced concrete slab have been studied against the influence of weight of TNT, standoff distance, boundary conditions, influence of air blast and surface blast. The results thus obtained from simulations were compared with the experiments available in literature. The inelastic behavior of concrete and steel reinforcement bar has been incorporated through concrete damage plasticity model and Johnson-cook models available in ABAQUS were presented. The predicted results through numerical simulations of the present study were found in close agreement with the experimental results. The damage mechanism and stress response of target were assessed based on the intensity of deformations, impulse velocity, von-Mises stresses and damage index in concrete. The results indicate that the standoff distance has great influence on the survivability of RC slab against blast loading. It is concluded that the velocity of impulse wave was found to be decreased from 17 to 11 m/s when the mass of TNT is reduced from 12 to 6 kg. It is observed that the maximum stress in the concrete was found to be in the range of 15 to $20N/mm^2$ and is almost constant for given charge weight. The slab with two short edge discontinuous end condition was found better and it may be utilised in designing important structures. Also it is observed that the deflection in slab by air blast was found decreased by 60% as compared to surface blast.

• 한국콘텐츠학회논문지
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• 제8권11호
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• pp.1-9
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• 2008

현재 멀티미디어 기술의 발달로 인하여 영상의 전처리 및 후처리 과정을 이용한 수정 작업으로 고품질의 영상 표현 및 다양한 영상 처리가 가능하다. 영상 처리 기법 중에서 이방성 확산의 경우 영상의 스페클 노이즈 제거, 에지 검출, 영상 분할 등에 응용할 수 있는 효과적인 확산 필터링으로 활용되고 있다. 하지만 전통적인 이방성 확산은 십자형 커널을 기반으로 하고 있기 때문에 확산 필터링을 반복 적용하면 영상의 에지가 수평 및 수직 방향으로 집중되는 문제점이 있다. 본 논문에서는 기존의 십자형 커널 기반의 이방성 확산 문제점을 해결하기 위하여 기울기의 방향성에 기반한 새로운 이방성 확산 방식을 제안한다. 제안된 방식은 십자형 커널을 확장하여 대각선 방향 정보를 포함한 8방향의 정방형 커널을 기반으로 작은 기울기를 갖는 방향으로 이방성 확산을 적용한다. 제안된 방식의 실험 결과 에지가 수평 및 수직 방향으로 집중되는 문제점을 해결하면서 임펄스성 노이즈를 제거하여 고품질의 영상을 획득할 수 있었다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2011년도 자성 및 자성재료 국제학술대회
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• pp.7-8
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• 2011

Although yttrium iron garnet (YIG) has provided a great vehicle for the study of spin waves in the past, associated difficulties in film deposition and device fabrication using YIG had limited the applicability of spin waves to practical devices. However, microfabrication techniques have made it possible to characterize both the resonant as well as the travelling characteristics of spin waves in permalloy (Py). A variety of methods have been used for measuring spin waves, including Brillouin light scattering (BLS), magneto-optic Kerr effect (MOKE), vector network analyzer ferromagnetic resonance (VNA-FMR), and pulse inductive microwave magnetometry (PIMM). PIMM is one of the most preferred methodologies of measuring travelling spin waves. In this method, an electrical impulse is applied at one of two coplanar waveguides patterned on top of oxide-insulated Py, producing a local disturbance in the magnetization of the Py. The resulting disturbance travels down the Py in the form of waves, and is inductively picked up by the other coplanar waveguide. We investigate the effect of the pulse width of excitation pulses on the generated spin wave packets using both experimental results and micromagnetic simulations. We show that spin wave packets generated from electrical pulses are a superposition of two separate spin wave packets, one generated from the rising edge and the other from the falling edge, which interfere either constructively or destructively with one another, depending upon the magnitude and direction of the field bias conditions. A method of spin wave amplitude modulation is also presented by the linear superposition of spin waves. We use interfering spin waves resulting from two closely spaced voltage impulses for the modulation of the magnitude of the resultant spin wave packets.

• 한국정보통신학회논문지
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• 제18권3호
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• pp.727-734
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• 2014

디지털 영상처리 기술은 영상의 압축, 인식 그리고 복원 등 많은 분야에서 연구가 진행되고 있다. 그러나 여전히 영상의 획득, 저장 및 전송하는 과정에서 잡음에 의해 영상의 열화가 발생하고 있다. 일반적으로 영상에 첨가되는 대표적인 잡음으로는 가우시안 잡음, 임펄스 잡음, 가우시안 및 임펄스 잡음이 중첩된 복합잡음 등이 있으며, 이러한 복합잡음을 제거하기 위해 다양한 연구가 진행되고 있다. 본 논문에서는 에지를 보존하고 복합잡음을 제거하기 위하여, 잡음 판단을 거친 후, 화소집합의 메디안값 및 평균값에 의해 적응 가중치를 설정하여 처리하는 영상복원 필터 알고리즘을 제안하였다. 그리고 시뮬레이션을 통해 기존의 방법들과 비교하였으며, 판단의 기준으로 PSNR(peak signal to noise ratio)을 사용하였다.

• 대한전자공학회논문지
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• 제15권6호
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• pp.8-22
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• 1978

근래에 발전하고 있는 Artificial Intelligence 또는 Synthetic Image 등 넓은 의미에서의 영상처리에 관하여 해석학적인 설명을 시도하였다. 일반적으로 얻어지는 "영상" 또는 "사진"에 반하여 간접적으로 얻어진 Synthetic Image의 대표적인 예로서 3차원 영상 재 구성 (3-Dimensional Image Reconstruction)을 들 수 있으며, 이의 최근 의학 및 생명 과학 분야는 물론 공학 및 물리학 분야의 비파괴 검사(NDT)등 많은 분야에의 응용에 급격한 발전을 보고 있다. 본 논문은 3차원 CT (Computerized Topography)의 기본을 이루는 3차원 영상 재구성 처리에 관한 기본적인 문제를 two-dimensional signal processing의 관점에서 다루었다.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.711-722
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• 2020

In this study, on-site testing was carried out to investigate the vibration serviceability of a composite steel-bar truss slab with steel girder system. Impulse excitations (heel-drop and jumping) and steady-state motion (walking and running) were performed to capture the primary vibration parameters (natural frequency and damping ratio) and distribution of peak acceleration. The composite floor possesses low frequency (<8.3Hz) and damping ratio (<2.47%). Based on experimental, theoretical, and numerical analyses on fundamental natural frequency, the boundary condition of SCSS (i.e., three edges simply supported and one edge clamped) is deemed more comparable substitutive for the investigated composite floor. Walking and running excitations by one person (single excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor β_rp describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking and running excitations is proposed. The comparisons of the modal parameters determined by walking and running tests reveal the interaction effect between the human excitation and the composite floor.