• Journal of Advanced Marine Engineering and Technology
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• 제16권5호
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• pp.85-96
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• 1992

Engine enclosures are widely adopted to reduce the noise emission in various fields of application. The radiated noise, which is due to the vibration of enclosure's outer surface, is composed of two kinds of sound power with different path of propagation. One is the 'structure-borne sound power' which stems from the engine's vibratory force applied to the structure of enclosure through the mounting parts of engine etc., while the other is the 'air-borne sound power' which is originated by the sound power radiated from the engine surface to the inner space of enclosure that should excite the vibration of enclosure from inside. In order to get a most efficient engine enclosure is required a profound consideration upon the above structure-borne and air-borne noise, since the guiding principle of countermeasure for each noise is quite different. The controlling of input vibration and its isolation are major subject for the structure-borne sound power and the specifications of absorbing member and damping panels are the major interests for the air-borne sound power. Hence it seems very efficient to separate the total sound power into two categories with a great accuracy when one think of further reduction of engine noise from the exciting enclosure, however, its separating methods have not been made clear for many years. Then author proposes a new practical separation method of two propagation path's contribution to the total radiation sound power for the enclosure under the engine operating condition.

• Journal of Power Electronics
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• 제16권2호
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• pp.480-489
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• 2016

A novel hybrid carrier-based pulse width modulation (CBPWM) scheme that combines unipolar and dipolar modulations is proposed for single-phase three-level rectifiers, which are widely applied in railway traction drive systems. The proposed CBPWM method can satisfy the volt-second balancing principle in the complete modulation index region through overmodulation compensation. The modulation scheme features two modulation modes: unipolar and dipolar. The operation range limits of these modulation modes can be modified by changing the separation coefficient. In comparison with the traditional unipolar CBPWM, the proposed hybrid CBPWM scheme can provide advantageous features, such as lower high-order harmonic distortion of the line current and better utilization of switching frequency. The separation coefficient value is optimized to achieve the maximum utilization of these advantages. The experimental results verify the feasibility and effectiveness of the proposed hybrid CBPWM scheme.

• 한국주조공학회지
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• 제22권3호
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• pp.130-136
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• 2002

The growing use of aluminum for castings over the past decade has brought with it the increased scrutiny of component properties. One area that has received much attention is the effect of in inclusions - or impurities particles held in the metal - on casting properties. A new method of electromagnetic separation for removal of inclusions in aluminum alloy melts is proposed. The principle is that as the electromagnetic force induced in metal acts on inclusions due to low electric conductivity, they are moved to the direction opposite to electromagnetic force and can be separated and removed from the melt. Experiments were carried out on A356 melt mixed alumina particles and commercial Al alloys of ADC 10 and 12. In the experiment using A356, it was proved that $Al_2O_3$ particles was separated and removed continuously from matrix melt by electromagnetic force. Based on these results, the continuous separation experiment that used ADC 10, 12 was carried and the cleanliness of melt was assessed by the amount of porosity, hydrogen contents, PoDFA and mechanical properties through tensile test. As the results of analyses, the amount of porosity and hydrogen contents decreased without variation of chemical composition in the specimen that passed the electromagnetic continuous separator. In addition, tensile strength and elongation of this specimen increased by $20{\sim}30%$ because of reduction of inclusions.

• Steel and Composite Structures
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• 제39권5호
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• pp.543-564
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• 2021

In this study free vibration analysis of a cracked Goland composite wing is investigated. The wing is modelled as a cantilevered beam based on Euler- Bernoulli equations. Also, composite material is modelled based on lamina fiber-reinforced. Edge crack is modelled by additional boundary conditions and local flexibility matrix in crack location, Castigliano's theorem and energy release rate formulation. Governing differential equations are extracted by Hamilton's principle. Using the separation of variables method, general solution in the normalized form for bending and torsion deflection is achieved then expressions for the cross-sectional rotation, the bending moment, the shear force and the torsional moment for the cantilevered beam are obtained. The cracked beam is modelled by separation of beam into two interconnected intact beams. Free vibration analysis of the beam is performed by applying boundary conditions at the fixed end, the free end, continuity conditions in the crack location of the beam and dynamic stiffness matrix determinant. Also, the effects of various parameters such as length and location of crack and fiber angle on natural frequencies and mode shapes are studied. Modal analysis results illustrate that natural frequencies and mode shapes are affected by depth and location of edge crack and coupling parameter.

• 과학기술학연구
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• 제15권1호
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• pp.281-325
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• 2015

이 글은 시민참여를 주장하는 STS 연구들이 각기 다른 이론적 관심과 방법론에 의해 상이한 입장을 취하게 되었음을 보인 필자들의 선행연구를 심화하여, 이상이한 입장들이 위험 거버넌스의 두 가지 큰 방법론인 위험분석(또는 위험평가/위험관리의 구분)과 사전주의 원칙에 대한 서로의 해석과 평가에 반영됨을 보일것이다. 이를 통해, 이 글은 STS 영역 밖에서 발전한 위험분석(위험평가/위험관리)이나 사전주의 원칙에 대한 STS의 입장이 단일한 것이 아님을 드러내고, 나아가 STS의 시민참여 거버넌스와 위험 거버넌스 연구 사이의 이론적이고 실천적인 접점을 확인하면서 일부 STS 연구자가 제시한 참여적 거버넌스 모델의 문제를 지적할 것이다.

• 벤처혁신연구
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• 제6권3호
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• pp.61-72
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• 2023

2020년 12월, 한국의 금산분리 원칙과 관련한 공정거래법이 개정되고 이를 1년 뒤인 2021년 12월 30일부터 시행한다는 정부의 발표가 있었다. 개정의 내용은 과거 금산분리의 대원칙이었던 산업자본의 금융시장 침투 금지 기조를 깨고 '일반지주회사의 중소기업창업투자회사와 신기술사업금융전문회사 주식의 소유 가능'이었다. 이 개정 법의 전제는 발행주식 총수의 소유이었지만, 법 개정 전후로 CVC(Corporate Venture Capital; 기업주도형 벤처캐피탈)의 연간 설립 건수와 투자 건수, 전략적 투자 건수 등의 추이에 변동이 있었다. CVC와 IVC(Independent Venture Capital; 독립 벤처캐피탈)는 투자 목적, 펀드 운용 유형, 투자 유형에 따라 그 특징이 구분되는데, 이 부분에서 금산분리법의 완화는 향후 벤처투자생태계와 혁신생태계의 활성화에 긍정적인 영향을 줄 수 있다고 기대된다. 본 연구에서는 법 개정 전인 2018년부터 법 개정 이후 2023년 5월까지 국내 CVC의 설립 건수, 투자 건수, 전략적 투자건수의 추이를 분석하여, 개정 금산분리법이 시행되었던 2021년을 기준으로 추이의 변화를 살펴보았다. 분석의 결과, 국내 CVC는 2021년에 전년대비 큰 폭으로 증가했으며, 투자건수와 전략적 투자건수, 전략적 투자의 투자금액 또한 과거에 비해 증가했음을 확인할 수 있었다. 본 연구는 이러한 결과를 토대로 향후 국내 CVC 투자와 전략적 투자, 벤처투자시장 활성화 등과 관련한 추가적인 연구의 방향을 제시한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1979년도 하계 전자.전기연합학술발표회논문집
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• pp.80-82
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• 1979

While the standard linear-quadratic-Gaussian problem has fixed horizons, this paper considers the LQG problem with moving horizons. By the separation principle the solution will be given by the kalman filter with the approaching horizon and the LQ regulator with the receding horizon. Sufficient conditions on weighting matrices are derived under which the filter and regulator are asymptotically stable. It wall be shown that the computation method of the moving-horizon LQG regulators is better than that of the standard LQG regulator. The performance measure between the two optimal controls will be compared. A simulation result is given in order to show the usefulness of the moving-horizon LQG regulator.s

• 한국멀티미디어학회논문지
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• 제15권12호
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• pp.1442-1448
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• 2012

The problem of Metal Area Segmentation (MAS) in X-ray CT images is a very hard task because of metal artifacts. This research features a practical yet effective method for MAS in X-ray CT images that exploits both projection image and reconstructed image spaces. We employ the Relevant Neighbor Area (RNA) idea [1] originally developed for projection image inpainting in order to create a novel feature in the projection image space that distinctively represents metal and near-metal pixels with opposite signs. In the reconstructed result of the feature image, application of a simple thresholding technique provides accurate segmentation of metal areas due to nice separation of near-metal areas from metal areas in its histogram.

• 한국IT서비스학회지
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• 제12권4호
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• pp.125-143
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• 2013

This paper intends to explore the social and cultural implications of convergence media, based on Goffman's situational approach. The situational segregation of regions makes us to re-interpret the current private and public spheres and helps us to reveal the principle and structure hidden in the new middle region. An environment of convergence media is nullifying the separation of private and public spheres, while letting a new middle region appear.

• 상하수도학회지
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• 제18권5호
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• pp.573-579
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• 2004

Electroflotation, which is used as an alternative to sedimentation, is a separation treatment process that uses small bubbles to remove low-density particulates. Making allowances for recent collision efficiency diagram based on trajectory analysis, it is necessary to tailor zeta potential of bubbles that collide with negatively charged particles. In this paper, the study was performed to investigate the effects of magnesium and aluminium ions on zeta potential of bubbles. And, it was studied to find out factors which could affect the positively charged bubbles. Consequently, zeta potential of bubbles increased both with higher concentration of metal ions and in the acidic pH value. And, a probable principle that explained the procedure of charge reversal could be a combined mechanism with both specific adsorption of hydroxylated species and laying down of hydroxide precipitate. It also depended on the metal ion concentration in the solution to display its capacity to control the bubble surface.