• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.54-54
• /
• 2004

집속체의 드래프트 공정(롤러 인발 공정)의 경우, 선밀도의 변동성(irregularity)은 드래프트 비, 롤러 간격 등의 공정조건과 집속체, 응집도, 엉킴 등으로 대표되는 openness 애 큰 영향을 받는다. 본 연구에서는 유동계 내에서의 집속체 동적거동을 묘사하는 기본 방정식을 바탕으로 openness 와 직접적인 관련이 있는 구성모델의 주요 파라메타($\mu$)의 변동을 auto-covariance function 으로 묘사되는 확률과정 신호(stochastic signal)로 생각하여, 이 신호를 생성하고, 모델 시뮬레이션을 통하여 출력 집속체의 선밀도 변동을 살펴 보았으며, 출력 집속체의 선밀도가 거의 일정하게 유지되는 출력구간 근처에서 선밀도 불균제 특성을 해석하였다.(중략)

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.626-628
• /
• 2001

고 기록 밀도의 HDD를 위해서는 HDD Media의 선 기록 밀도와 트랙 밀도를 높여야 한다. 선기록 밀도를 높이기 위해서는 HDD Write Head의 Field Gradient가 커야하고, 트랙 밀도를 높이기 위해서는 Write Head의 Aspect Ratio가 작아져야 한다. 본 연구에서는 3차원 유한 요소법을 이용하여 Write Head의 재료의 자기적 성질과 형상에 따른 고 기록 밀도용 Pole Tip Write Head를 설계하였다.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1451-1452
• /
• 2011

ZnO 나노선을 수열합성법을 이용하여 합성 하였다. ZnO 나노선을 이용하여 고효울 소자 제작하기 위해 반듯이 필요한 조건인 밀도 조절을 위해 PDOT:PSS를 에어브로쉬를 이용하여 분사하여 Dot의 형태로 열처리 한후 나노선을 합성 하였고 SEM 이미지를 통하여 밀도가 조절된 것을 확인 하였다.

• Proceedings of the Korean Fiber Society Conference
• /
• 1998.04a
• /
• pp.209-213
• /
• 1998

방적공정중에서 섬유속의 선밀도 감소와 평행화도 증가를 위해서 행해지는 드래프트 공정은 섬유속의 선밀도를 감소시킴과 동시에 불균제도를 증가시키게 된다. 실제의 생산설비는 드래프트로 인해 발생되는 불균제를 최소화하기 위해 여러 가지 다양한 기구를 사용한다. 드래프트 공정에서의 불균제도 증가는 드래프트 공정의 조건에 따라 그 정도를 달리하게 되는데, 최적의 공정조건은 공급되는 섬유속의 특성에 따라 변화시켜주어야 한다.(중략)

• Journal of Astronomy and Space Sciences
• /
• v.14 no.1
• /
• pp.24-32
• /
• 1997

We have calculated the velocity distribution of wind driven by Alfven waves. The assumed initial number density of wind can affect the line profiles because it produces the change in the velocity distribution under the mass conservation. Initial density $N_O=5.5{\times}10^{12}/cm^3$ is chosen for a proper initial density from the observation by Schroder(1986). The wind models for $N_O=10^9,10^{10},10^{11},5.5{\times}10^{12}/cm^3$ are calculated at ${phi}$=0.06 and ${phi}$=0.78. The line profiles for lower initial density show the strong emissions and narrow absorptions because of their steeper velocity gradients.

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.4
• /
• pp.105-112
• /
• 2023

In this paper, we propose a new method for displaying colored defects by measuring the relative density with the wide-area and local densities of X-ray. The relative density of one pixel represents a relative difference from the surrounding pixels, and we also suggest a colorization of X-ray images representing these pixels as normal and defective. The traditional method mainly inspects materials such as plastics and metals, which have large differences in transmittance to the object. Our proposed method can be used to detect defects such as sprouts or holes in images obtained by an inspection machine that detects X-rays. In the experiment, the products that could not be seen with the naked eye were colored with pests or sprouts in a specific color so that they could be used in the agricultural product selection system. Products that are uniformly filled with a single ingredient inside, such as potatoes, carrots, and apples, can be detected effectively. However, it does not work well with bumpy products, such as peppers and paprika. The advantage of this method is that, unlike machine learning, it doesn't require large amounts of data. The proposed method could be applied to a screening system using X-rays and used not only in agricultural product screening systems but also in manufacturing processes such as processed food and parts manufacturing, so that it can be actively used to select defective products.

• Geophysics and Geophysical Exploration
• /
• v.15 no.4
• /
• pp.190-198
• /
• 2012

A series of density log data were obtained from the standoff experiments made in the four physical model boreholes of different densities, and the properties of spine and rib curves have been derived by the analysis of the gamma-gamma data. Particularly, the shape of gamma ray propagation path between source and detector, the geometrical property of spine and rib curves, the influence of borehole density and the detector combination on the properties of the curves, and the adequate detector combination for standoff compensation could be discussed. It was also confirmed that spine and rib slopes can be expressed as proportional to source-to-detector distance ratio between far and near detectors. The result of this experiment was also effectively applied for understanding the basic concept of spine and rib slopes.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.04a
• /
• pp.369-372
• /
• 2012

대사성 골 질환인 골다공증(Osteoporosis)의 조기 진단을 위한 골 밀도를 측정하는 방법이 최근 연구되고 있다. 골 밀도 영상은 이중 에너지 X 선 흡수법에 의해 측정되는데, 영상에 존재하는 잡음은 뼈 영역 추출과 골 밀도 계산에 어려움을 주고 있다. 따라서 본 논문에서는 최근 신호처리 분야에서 폭넓게 사용되고 있는 sparse 표현을 도입하여 X 선 영상의 잡음을 제거하는 방법을 제안한다. 실험을 통해 제안한 잡음 제거 방법의 결과가 기존의 방법에 비해 개선됨을 MSR(Mean to Standard deviation Ratio)과 CNR(Contrast to Noise Ratio)을 통해 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.2
• /
• pp.453-459
• /
• 2017

Users tend to check in and post their statuses in location-based social networks (LBSNs) to describe that their interests are related to a point-of-interest (POI). While previous studies on discovering area-of-interests (AOIs) were conducted mostly on the basis of density-based clustering methods with the collection of geo-tagged photos from LBSNs, we focus on estimating a POI boundary, which corresponds to only one cluster containing its POI center. Using geo-tagged tweets recorded from Twitter users, this paper introduces a density-based low-complexity two-phase method to estimate a POI boundary by finding a suitable radius reachable from the POI center. We estimate a boundary of the POI as the convex hull of selected geo-tags through our two-phase density-based estimation, where each phase proceeds with different sizes of radius increment. It is shown that our method outperforms the conventional density-based clustering method in terms of computational complexity.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.10a
• /
• pp.48-49
• /
• 2009

This study predicts and compares the evacuation times of a training ship, which is easily influenced by gathering patterns of crews' onboard life style. As the results, the evacuation times of the high density, like meal time, take 1.5 times longer than the low density, like normal time. And it is also evaluated that the evacuation times of high density affected by evacuation speeds show 4 times higher than the low density.