• 한국추진공학회지
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• 제21권6호
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• pp.103-109
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• 2017

연소화염 열에너지와 결합된 음향에너지 증가는 연소 불안정성을 유발할 수 있다. 연소 안정성 예측을 위해서는 연소실 내부 유동 경계에서 음향특성을 파악해서 궁극적으로 음향에너지의 증가 여부를 파악하는 것이 필요하다. 본 논문에서는 연소기 헤드와 같은 유동 경계 형상에 대한 음향 특성을 연구한 기존의 주요 분석적 결과를 정리하여, Strouhal 수로 표현되는 경계면 음향 임피던스 특성을 알아보았다. 또한 이중 마이크로폰을 활용한 실험적 방법을 통해 경계 음향 임피던스 특성에 대한 이론적/해석적 결과를 검증하기 위한 기법을 조사 정리하였다.

• 한국컴퓨터정보학회논문지
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• 제21권11호
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• pp.103-111
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• 2016

Traditionally, in the hospital the doctors saw the TRUS images by their eyes and manually segmented the boundary between the prostate and nonprostate. But the manually segmenting process not only needed too much time but also had different boundaries according to the doctor. To cope the problems, some automatic segmentations of the prostate have been studied to generate the constant segmentation results and get the belief from patients. Besides, on detecting the boundary, the ones in the middle of all images are easy to find the boundary but the base and apex of the images are hard to do it since there are lots of uncertain boundary. Accurate detection of prostate boundaries is a challenging and difficult task due to weak prostate boundaries, speckle noises and the short range of gray levels. In this paper, we propose the method that extracts a prostate boundary using features of its directions on prostate image. As a result of our experiments, it shows that the boundary never falls short of the existing methods or human expert's segmentation. And also, its searching speed is too fast because the method searches a smaller area that other methods.

• 디지털융복합연구
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• 제11권1호
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• pp.191-198
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• 2013

최근 스마트폰, 태블릿PC, 와이브로(WiBro), LTE 등 정보기술의 발전과 함께 스마트워크에 대한 관심이 증대되고 있다. 본 연구에서는 스마트워크를 도입함으로써 나타나는 업무 비업무 경계 모호성의 근본 문제를 경계 이론에 통해 이해하고자 하였다. 국내 K사의 재택근무와 스마트워크센터근무 이용자를 대상으로 경계 이론에서 제시하는 핵심 개념인 침투가능성, 경계 강도, 간섭 등을 포괄적으로 고려한 실증 연구를 수행하였다. 연구 결과를 통해 스마트워크 이용자는 업무와 비업무 영역 간의 비대칭성을 지각하고 있다는 사실을 확인하였다. 본 연구는 스마트워크와 관련된 향후 연구에서 업무와 비업무 영역 간 양방향성을 전제하여 경계 관리 전략을 고려할 필요성을 제시하고 있다.

• 한국지능시스템학회논문지
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• 제25권6호
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• pp.585-591
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• 2015

구어 연구를 위한 전사 과정에서 문자로 표현된 발화를 녹음 음성에 연결해주는 작업을 레이블링이라고 한다. 기존 레이블링 도구들은 대부분 수동으로 작업이 이루어진다. 제안하는 반자동 레이블링은 자동화 모듈과 수동 조정 모듈로 구성된다. 자동화 모듈은 G.Saha 알고리즘을 활용하여 음성구간을 추출하고, 기구축된 발화텍스트의 발화 수와 발화의 길이 정보를 이용하여 발화구간을 예측한다. 본 논문에서는 기존 수동 도구의 정확성을 유지하기 위하여 자동 레이블링된 발화구간을 보정하기 위한 수동 조정 사용자 인터페이스를 제공한다. 제안하는 반자동 레이블링 알고리즘으로 구현한 도구는 기존 수동 레이블링 도구와 비교하여 작업 속도가 평균 27% 향상되었다.

• 한국통신학회논문지
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• 제14권3호
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• pp.249-262
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• 1989

본 논문에서는 이동에지와 휴리스틱 탐색을 이용하여 움직이는 물체의 경계를 추출하는 간단한 방법을 제안한다. 실제 연속 영상에서 효율적으로 이동에지를 검출하는 방법을 제안하였으며, 그 결과 나타난 이동에지를 따라 간단한 휴리스틱 탐색을 수행하게 된다. 이상의 과정에서 나타나지 않은 움직이는 물체의 경계를 앞서 찾아간 신들의 끝점들로부터 휴리스틱하게 추출한다. 세 종류의 실제 연속영상에 제안한 방법을 적용하여 본 결과 적은 계산량으로 움직이는 물체의 경계검출이 가능함을 보였다.

• 한국세라믹학회지
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• 제37권1호
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• pp.102-109
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• 2000

When PbZrO3 (PZ) and PbTiO3 (PT) particles were scattered on polished surfaces of sintered Pb(Zr0.52Ti0.48)O3 (PZT; Zr/Ti=1.08) and then annealed, the PZT grain boundaries migrated. Near the scattered particles, grain boundaries were corrugated and thus the grain shape changed from a normal one to irregular ones. Especially, near the scattered PZ particles, fast grain growth occurred. In the regions swept by moving grain boundaries, the Zr/Tiratio was measured to be about 1.35 for of PZ scattering and about 0.8 for PT scattering, respectively. This result indicates that the grain boundary migration was induced by alloying of Zr and Ti ions in PZT grains, as in usual diffusion induced grain boundary migration(DIGM). A calculation showed that higher coherency strain energy was induced for PT scattering because of higher alloying of Ti than of Zr.

• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.659-667
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• 1997

The influence of SiO$_2$on the microstructure and electrical properties of zinc oxide varistor was investigated. Zn$_2$SiO$_4$third phase in the sintered body was found at grain boundaries, multiple grain junctions, and occasionally within ZnO grains. This phase acted as a grain growth inhibitor, which retard the grain growth of the ZnO matrix by impeding migration on the grain boundaries. As SiO$_2$ addition increases, average grain size decreased from 40.6${\mu}{\textrm}{m}$ to 26.9${\mu}{\textrm}{m}$ due to the pinning effect by Zn$_2$SiO$_4$ and drag effect by Si segregation at grain boundaries, the breakdown voltage consequently increased. When SiO$_2$ addition is increased, interface state density decreased, however, the barrier height increased by decrease of donor concentration, as a result, the nonlinear exponent increased and leakage current decreased. While, as SiO$_2$ addition increase, it was found that the apparent dielectric loss factor shows a tendency of decrease. Wholly, electrical properties of zinc oxide varistor can be said to be improved by SiO$_2$addition.

• 한국분말재료학회지
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• 제17권1호
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• pp.52-58
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• 2010

Bulk nanostructured metallic materials are generally synthesized by bottom-up processing which starts from powders for assembling bulk materials. In this study, the bottom-up powder metallurgy and High Pressure Torsion (HPT) approaches were combined to achieve both full density and grain refinement at the same time. After the HPT process at 473K, the disk samples reached a steady state condition when the microstructure and properties no longer evolve, and equilibrium boundaries with high angle grain boundaries (HAGBs) were dominant. The well dispersed alumina particles played important role of obstacles to dislocation glide and to grain growth, and thus, reduced the grain size at elevated temperature. The small grain size with HAGBs resulted in high strength and good ductility.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.375-375
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• 2007

In the conventional crystallization method, thepoly-Si TFTs show poor device-to-device uniformity because of the random location of the grain boundaries. However, our new crystallization method introduced in this paper employed substrate-embedded seeds on the highly ordered anodic alumina template to control both the location of seeds and the number of grain boundaries intentionally. In the process of excimer laser crystallization (ELC), a-Si film deposited on the anodic alumina by low pressure chemical vapor deposition (LPCVD) is transformed into fine poly-Si grains by explosive crystallization (XC) prior to primary melting. At the higher energy density, the film is nearly completely melted and laterally grown by super lateral growth (SLG) from remained small part of the fine poly-Si grains as seeds at the Si/anodic alumina interface. Resultant grain boundaries have almost linear functions of the number of seeds in concavities of anodic alumina which have a constant spacing. It reveals the uniformity of. device can be enhanced prominently by controlling location and size of pores which contains fine poly~Si seeds under artificial anodizing condition.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4052-4059
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• 2021

The microstructure of the fuel pellet plays an essential role in fission gas buildup and release and is critical for the safe and continued operation of nuclear power stations. Structural analysis of uranium dioxide (UO₂)-molybdenum (Mo) composite fuel pellets prepared at a range of sintering temperatures from 1300 to 1800 ℃ was performed. Mo micro and nanoparticles were used in making the composite pellets. A systematic investigation into the influence of processing parameters during Spark Plasma Sintering (SPS) of the pellets on the microstructure, texture, grain size, and grain boundary characters of UO₂-Mo is presented. UO₂-Mo composite show significant differences in the fraction of general boundaries and also special/coincident site lattice (CSL) boundaries. EBSD orientation maps demonstrated that <111> texturing was observed in the pellets fabricated at 1500 ℃. The experimental investigations suggest that UO₂-Mo composite pellets have favorable microstructural features compared to the UO₂ pellet.