• 융합신호처리학회논문지
• /
• 제22권3호
• /
• pp.91-98
• /
• 2021

기초과학연구원 중이온가속기구축사업단에서는 희귀동위원소(Rare Isotopes, RI) 빔의 생성 및 분리를 위한 ISOL(Isotope Separation On Line) 시스템의 설치 및 성능시험이 진행 중에 있다. ISOL 표적/이온원에서 생성된 다양한 RI 빔은 빔 전송장치 및 분리 장치를 거쳐 사용자가 원하는 RI 빔만 선별되어 ISOL 후단의 초전도 선형가속기로 전송된다. ISOL 시스템에서는 특정 RI 빔을 분리하기 위해 두 개의 분리 장치가 설치되어 있으며 EPICS(Experimental Physics and Industrial Control System)에 의해 제어가 이루어진다. 본 연구에서는 ISOL RI 빔 분리 장치 중 하나인 A/Q 분리기에서 다가(n+) RI 빔의 질량선별을 위해 이극자석의 자기장을 측정하기 위한 EPICS IOC(Input-Output Control)를 개발하였으며, 홀 프로브(Hall Probe)를 이용한 자기장 측정 실험을 통해 A/Q 분리기의 운전 안정성에 대해 평가하였다.

• 한국콘텐츠학회논문지
• /
• 제21권12호
• /
• pp.95-106
• /
• 2021

본 연구의 목적은 한국콘텐츠학회 논문지에 게재된 9,858건의 논문을 대상으로 토픽 모델링을 활용하여 지난 20년간 연구동향을 탐색함으로써 콘텐츠 연구개발에서의 주요 토픽을 도출하고 학술적 발전방향을 제공하는데 있다. 추출된 토픽의 신뢰성과 타당성을 확보하기 위해 양적 평가기법 뿐만 아니라 정성적 기법을 단계적으로 적용하여 연구자들이 합의한 수준의 말뭉치가 생성될 때까지 이를 반복적으로 수행하였으며 이에 따른 구체적인 분석 절차를 제시하였다. 분석 결과 8개의 핵심 토픽이 추출되었다. 이는 한국콘텐츠학회가 특정 학문 분야를 한정하지 않고 다양한 분야의 융·복합 연구 논문을 발간하고 있음을 보여준다. 또한 2012년 이전 상반기에는 공학기술 분야 토픽 비중이 상대적으로 높게 나타난 반면, 2012년 이후 하반기에는 사회과학 분야 토픽 출현 비중이 상대적으로 높게 나타났다. 구체적으로 '사회복지' 토픽은 상반기 대비 하반기에 약 4배수 증가세가 나타났다. 토픽별 추세분석을 통해 추세선의 변곡점이 나타난 특정 시점에 주목하여 해당 토픽의 연구동향에 영향을 미친 외적 변인을 탐색하였고 토픽과 외적 변인 간 관련성을 파악하였다. 본 연구결과가 국내 콘텐츠 관련 연구 개발 및 산업 분야에서 진행되고 있는 활발한 논의를 진행하는데 시사점을 제공할 수 있기를 기대한다.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2935-2940
• /
• 2023

A polystyrene phantom was developed following the guidance of the International Atomic Energy Association (IAEA) for gamma knife (GK) quality assurance. Its performance was assessed by measuring the absorbed dose rate to water and dose distributions. The phantom was made of polystyrene, which has an electron density (1.0156) similar to that of water. The phantom included one outer phantom and four inner phantoms. Two inner phantoms held PTW T31010 and Exradin A16 ion chambers. One inner phantom held a film in the XY plane of the Leksell coordinate system, and another inner phantom held a film in the YZ or ZX planes. The absorbed dose rate to water and beam profiles of the machine-specific reference (msr) field, namely, the 16 mm collimator field of a GK Perfexion^TM or Icon^TM, were measured at seven GK sites. The measured results were compared to those of an IAEA-recommended solid water (SW) phantom. The radius of the polystyrene phantom was determined to be 7.88 cm by converting the electron density of the plastic, considering a water depth of 8 g/cm². The absorbed dose rates to water measured in both phantoms differed from the treatment planning program by less than 1.1%. Before msr correction, the PTW T31010 dose rates (PTW Freiberg GmbH, New York, NY, USA) in the polystyrene phantom were 0.70 (0.29)% higher on average than those in the SW phantom. The Exradin A16 (Standard Imaging, Middleton, WI, USA) dose rates were 0.76 (0.32)% higher in the polystyrene phantom. After msr correction factors were applied, there were no statistically significant differences in the A16 dose rates measured in the two phantoms; however, the T31010 dose rates were 0.72 (0.29)% higher in the polystyrene phantom. When the full widths at half maximum and penumbras of the msr field were compared, no significant differences between the two phantoms were observed, except for the penumbra in the Y-axis. However, the difference in the penumbra was smaller than variations among different sites. A polystyrene phantom developed for gamma knife dosimetry showed dosimetric performance comparable to that of a commercial SW phantom. In addition to its cost effectiveness, the polystyrene phantom removes air space around the detector. Additional simulations of the msr correction factors of the polystyrene phantom should be performed.

• 에너지공학
• /
• 제17권3호
• /
• pp.125-138
• /
• 2008

에너지원의 다양화와 효율적인 이용을 위하여 광역지역의 통합에너지관리 시스템 구축이 요구되고 있다. 본 보문에서는 이러한 필요성에 부응하여 광역에너지 네트워크 구축에 필요한 핵심기술을 발굴하여 이를 종합적으로 현장에 적용하는 기술개발 을 수행하고 있다. 이를 위해 IT기술과 접목한 광역 네트워크 열공급 최적화 통합시스템 구축 기술, 발생되는 배열을 이용한 열펌프와 같은 미활용에너지 이용기술, 다양한 열원을 이용한 열수송 및 축열 기술 등 새로운 시스템을 개발하고 이를 현장적용을 통해 경제성을 평가하여 최종적으로 실용화할 수 있는 사업화 모델에 대하여 기술하였다.

• ALGAE
• /
• 제26권3호
• /
• pp.237-241
• /
• 2011

The toxic dinoflagellate Karlodinium veneficum has been implicated in numerous fish kill events around the world. Since this species commonly co-occurs with other morphologically similar dinoflagellates, field monitoring of this species in natural waters via light microscopy only has been problematic. In this study, we investigated temporal changes in K. veneficum's abundance in the waters of Obido, Tongyeong, using a species-specific real-time polymerase chain reaction (PCR) assay. The field survey, from April to December 2010, revealed K. veneficum occurred at low densities (12 to 425 cells $L^{-1}$) during this time and that cell numbers peaked in June (early summer in Korea), indicating this species generally occurs in the warmer season (mostly at $16.9-22.3^{\circ}C$ and 33.4-34.5‰) in the Obido area.

• 한국게임학회 논문지
• /
• 제12권1호
• /
• pp.123-132
• /
• 2012

스마트 디바이스를 이용한 다양한 게임들이 증가하고 있는데, 음소인식은 스마트 디바이스를 사용한 효율적인 입력 방법은 음성이 될 수 있다. 게임에서 음성인식은 매우 빠르게 인식되면서 구동 되어야하는데, 본 연구에서는 게임 분야에서 유용하게 활용할 수 있는 최적화된 음소 인식 방법을 개발하였다. 본 논문에서 제안하는 음소 인식 방법은 음성 파장을 FFT로 전환하고, 해당 값을 Z평면에 도시한 후, 영역 데이터를 추출한 후 데이터베이스에 저장한다. 그리고 해당 값을 가중치 있는 두 갈래 그래프 최대 흐름 정합을 사용하여 음소 인식을 한다. 제안된 방법은 게임 또는 로봇과 같은 분야에서 빠른 음소 인식을 하고자 할 때 매우 유용한 방법이다.

• 한국정보시스템학회:학술대회논문집
• /
• 한국정보시스템학회 1996년도 추계학술발표회 발표논문집
• /
• pp.217-227
• /
• 1996

The new field of learning control develops controllers that learn to improve their performance at executing a given task, based on experience performin this specific task. In a previous work［6］, the authors presented a theory of indirect learning control based on use of indirect adaptive control concepts employing simultaneous identification ad control. This paper develops improved indirect learning control algorithms, and studies the use of such controllers in decentralized systems. The original motivation of the learning control field was learning in robots doing repetitive tasks such as on an assembly line. This paper starts with decentralized discrete time systems, and progresses to the robot application, modeling the robot as a time varying linear system in the neighborhood of the nominal trajectory, and using the usual robot controllers that are decentralized, treating each link as if it is independent of any coupling with other links. The basic result of the paper is to show that stability of the indirect learning controllers for all subsystems when the coupling between subsystems is turned off, assures convergence to zero tracking error of the decentralized indirect learning control of the coupled system, provided that the sample time in the digital learning controller is sufficiently short.

• Bulletin of the Korean Chemical Society
• /
• 제34권9호
• /
• pp.2725-2730
• /
• 2013

Single C-reactive protein (CRP) molecules, which are non-specific acute phase markers and products of the innate immune system, were quantitatively detected on a gold-nanopatterned biochip using evanescent field-enhanced fluorescence imaging. The $4{\times}5$ gold-nanopatterned biochip (spot diameter of 500 nm) was fabricated by electron beam nanolithography. Unlabeled CRP molecules in human serum were identified with single-molecule sandwich immunoassay by detecting secondary fluorescence generated by total internal reflection fluorescence (TIRF) microscopy. With decreased standard CRP concentrations, relative fluorescence intensities reduced in the range of 33.3 zM-800 pM. To enhance fluorescence intensities in TIRF images, the distance between biochip surface and CRP molecules was optimally adjusted by considering the quenching effect of gold and the evanescent field intensity. As a result, TIRF only detected one single-CRP molecule on the biochip the first time.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권5호
• /
• pp.588-593
• /
• 2014

Current crowding problem can worsen the internal quantum efficiency and the negative-voltage ESD of InGaN-based LEDs. In this paper, by using photon emission microscope and thermal emission microscope measurement, we confirmed that the electric field and the current of the InGaN-based LED sample are crowded in specific regions where the distance between p-type metal contact and n-type metal contact is shorter than other regions. To improve this crowding problem of electric field and current, modified metal contact geometry having uniform distance between the two contacts is proposed and verified by a numerical simulation. It is confirmed that the proposed structure shows better current spreading, resulting in higher internal quantum efficiency and reduced reverse leakage current.

• Smart Structures and Systems
• /
• 제15권2호
• /
• pp.469-488
• /
• 2015

Thermal loads, especially thermal gradients, have a considerable effect on the behaviors of large-scale bridges throughout their lifecycles. Bridge design specifications provide minimal guidance regarding thermal gradients for simple bridge girders and do not consider transversal thermal gradients in wide girder cross-sections. This paper investigates the three-dimensional thermal gradients of arch bridge girders by integrating long-term field monitoring data recorded by a structural health monitoring system, with emphasis on the vertical and transversal thermal gradients of wide concrete-steel composite girders. Based on field monitoring data for one year, the time-dependent characteristics of temperature and three-dimensional thermal gradients in girder cross-sections are explored. A statistical analysis of thermal gradients is conducted, and the probability density functions of transversal and vertical thermal gradients are estimated. The extreme thermal gradients are predicted with a specific return period by employing an extreme value analysis, and the profiles of the vertical thermal gradient are established for bridge design. The transversal and vertical thermal gradients are developed to help engineers understand the thermal behaviors of concrete-steel composite girders during their service periods.