• 한국구조물진단유지관리공학회 논문집
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• 제19권3호
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• pp.30-38
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• 2015

적설한랭지의 경우, 동절기의 동해 및 적설에 의한 교통통행의 원활을 기하기 위하여 제설제를 사용한다. 이와 같은 제설염의 사용은 동결융해 및 염화물에 의해 콘크리트의 급속한 스케일링 피해를 야기시킨다. 이에 대한 피해로 인하여 콘크리트 포장은 콘크리트의 피복두께 감소에 따른 조기 열화 및 사용자의 안정성 등 여러 가지 문제를 발생시킨다. 이에 따라 국외적으로 이와 같은 현상에 대하여 평가를 하기 위해 다양한 시험 및 평가 방법이 제시되고 있다. 하지만 국내에서는 아직 평가방법에 대한 규정은 없으며, 관련 연구 또한 미미한 수준이다. 따라서 본 논문에서는 각 기관 및 나라에서 제시되고 있는 평가방법을 조사하고, 각각의 규정에 따라 실험을 수행하여 결과를 도출하여 비교 분석하였다. 나아가 이와 같은 실험방법과 실험결과의 고찰을 통하여 국내현장에 맞는 실험법을 제안하고자 한다.

• 한국결정학회지
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• 제16권2호
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• pp.89-101
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• 2005

Among many material processing related issues for successful scaling down of devices for the next 10 years or so, the advanced gate stack and interconnect technology are two most critical research areas, which need technical innovation. The introduction of new metallic films and appropriate processing technologies are required more than ever. Especially, as the device downscaling continues well into sub 50 nm regime, the paradigm for metal nano film deposition technique research has been shifted to high conformality, low growth temperature, high quality with uniformity at large area wafers. Regarding these, ALD has sparked a lot of interests for a number of reasons. The process is intrinsically atomic in nature, resulting in the controlled deposition of films in sub-monolayer units with excellent conformality. In this paper, the overview on the current issues and the future trends in device processing technologies related to metal nano films as well as the R&D trends in these applications will be discussed. The focus will be on the applications for metal gate, capacitor electrode for DRAM, and diffusion barriers/seed layers for Cu interconnect technology.

• 한국정보통신학회논문지
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• 제10권12호
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• pp.2271-2282
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• 2006

본 논문은 총 변화량 최소화와 같은 편 미분방정식을 기본으로 한 영상 복원에 제기된 이슈에 관련된다. 총 변화량 최소화방법과 같은 평활화 연산자의 과도한 분산과 계단화와 같은 문제점들에 대하여 특별히 연구한다. 계단화와 과도한 분산을 방지하기 위하여 대수시스템에서의 축척과 비 오목형 최소화 기법이 각각 고려된다. 더군다나 에지를 좀더 잘 보존하기 위한 다양한 제약 매개변수가 소개된다. 제안된 알고리즘이 소음제거에 있어서 효율적이고 합리적임이 수학적으로 증명되며 다양한 실험 결과가 보여진다.

• Journal of Power Electronics
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• 제9권2호
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• pp.180-187
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• 2009

When converters operate in megahertz range, the passive components and magnetic devices generate high losses. However, the eddy current issues and choices of magnetic cores significantly affect on the design stage. Apart from that, the components' reduction, miniaturization technique and frequency scaling are required as well as improvement in thermal capability, integration technique, circuit topologies and PCB layout optimization. In transformer design, the winding and core losses give great attention to the design stage. From simulation work, it is found that E-25066 material manufactured by AVX could be the most suitable core for high frequency transformer design. By employing planar geometry topology, the material can generate significant power loss savings of more than 67% compared to other materials studied in this work. Furthermore, young researchers can use this information to develop new approaches based on concepts, issues and methodology in the design of magnetic components for high frequency applications.

• 전자통신동향분석
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• 제38권6호
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• pp.52-61
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• 2023

With semiconductor scaling approaching the physical limits, devices including CMOS (complementary metal-oxide-semiconductor) components have managed to overcome yet are currently struggling with several technical issues like short-channel effects. Evolving from the process node of 22 nm with FinFET (fin field effect transistor), state-of-the-art semiconductor technology has reached the 3 nm node with the GAA-FET (gate-all-around FET), which appropriately addresses the main issues of power, performance, and cost. Technical problems remain regarding the foundry of GAA-FET, and next-generation devices called post-GAA transistors have not yet been devised, except for the CFET (complementary FET). We introduce a CFET that spatially stacks p- and n-channel FETs on the same footprint and describe its structure and fabrication. Technical details like stacking of nanosheets, special spacers, hetero-epitaxy, and selective recess are more thoroughly reviewed than in similar articles on CFET fabrication.

• 정보처리학회논문지A
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• 제16A권1호
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• pp.27-34
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• 2009

최근 디지털 시스템 응용의 복잡성이 증가하면서, 고성능화와 전력 소모 절감은 중요한 문제로 대두되고 있다. 전력 소모를 줄이기 위한 방법으로, 프로세서의 저 전력화 또한 미세 공정의 개발과 함께 다양하게 접근되고 있으며, 이러한 결과 모바일 시스템의 시장 확대가 이루어지고 있다. 본 논문은 이러한 프로세서에서 소모되는 전력 중 데이터 캐시의 전력 손실을 줄이기 위하여 데이터 캐시의 웨이 중 필요로 하는 부분을 예측하여 선택적으로 프리자치 하도록 하는 전력 소모 개선 방법을 제안하였으며, 접근하는 웨이에 대한 예측이 성공했을 경우에는 에너지를 절감하면서 지연이 발생하지 않는 빠른 접근이 이루어지게 하고, 실패하였을 경우에도 최소한의 시간 지연으로 해당되는 웨이의 접근이 이루어지게 하였다. 시뮬레이션을 통한 검증 결과 웨이 예측 기법만을 사용한 경우에 대비하여 평균 10.2% 의 전력을 절감할 수 있었으며, 일반적 캐시에 비하여는 평균 56.4%의 전력을 절감할 수 있었다.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1310-1317
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• 2017

GASFLOW-MPI is a widely used scalable computational fluid dynamics numerical tool to simulate the fluid turbulence behavior, combustion dynamics, and other related thermal-hydraulic phenomena in nuclear power plant containment. An efficient scalable linear solver for the large-scale pressure equation is one of the key issues to ensure the computational efficiency of GASFLOW-MPI. Several advanced Krylov subspace methods and scalable preconditioning methods are compared and analyzed to improve the computational performance. With the help of the powerful computational capability, the large eddy simulation turbulent model is used to resolve more detailed turbulent behaviors. A backward-facing step flow is performed to study the free shear layer, the recirculation region, and the boundary layer, which is widespread in many scientific and engineering applications. Numerical results are compared with the experimental data in the literature and the direct numerical simulation results by GASFLOW-MPI. Both time-averaged velocity profile and turbulent intensity are well consistent with the experimental data and direct numerical simulation result. Furthermore, the frequency spectrum is presented and a -5/3 energy decay is observed for a wide range of frequencies, satisfying the turbulent energy spectrum theory. Parallel scaling tests are also implemented on the KIT/IKET cluster and a linear scaling is realized for GASFLOW-MPI.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.147-147
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• 2019

The Numerical Weather Prediction (NWP) models determine the future state of the weather by forcing current weather conditions into the atmospheric models. The NWP models approximate mathematically the physical dynamics by nonlinear differential equations; however these approximations include uncertainties. The errors of the NWP estimations can be related to the initial and boundary conditions and model parameterization. Development in the meteorological forecast models did not solve the issues related to the inevitable biases. In spite of the efforts to incorporate all sources of uncertainty into the forecast, and regardless of the methodologies applied to generate the forecast ensembles, they are still subject to errors and systematic biases. The statistical post-processing increases the accuracy of the forecast data by decreasing the errors. Error prediction of the NWP models which is updating the NWP model outputs or model output statistics is one of the ways to improve the model forecast. The regression methods (including linear, polynomial and scaling regression) are applied to the present study to improve the real time forecast skill. Such post-processing consists of two main steps. Firstly, regression is built between forecast and measurement, available during a certain training period, and secondly, the regression is applied to new forecasts. In this study, the WRF real-time forecast data, in comparison with the observed data, had systematic biases; the errors related to the NWP model forecasts were reflected in the underestimation of the meteorological data forecast by the WRF model. The promising results will indicate that the post-processing techniques applied in this study improved the meteorological forecast data provided by WRF model. A comparison between various bias correction methods will show the strength and weakness of the each methods.

• 한국표면공학회지
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• 제55권5호
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• pp.247-260
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• 2022

Since the first report on ferroelectricity in Si-doped hafnia (HfO2), this emerging ferroelectrics have been considered promising for the next-generation semiconductor devices with their characteristic nonvolatile data storage. The robust ferroelectricity in the sub-10-nm thickness regime has been proven by numerous research groups. However, extending their scalability below the 5 nm thickness with low temperature processes compatible with the back-end-of-line technology. In this review, therefore, the current status, technical issues, and their potential solutions of atomic layer deposition (ALD) of HfO₂-based ferroelectrics are comprehensively reviewed. Several technical issues in the physical scaling of the ferroelectric thin films and potential solutions including advanced ALD techniques including discrete feeding ALD, atomic layer etching, and area selective ALD are introduced.

• 대한임베디드공학회논문지
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• 제2권3호
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• pp.194-201
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• 2007

As the performance of the mobile terminal becomes higher, the power consumption gradually increases. As a result, power management is one of the most important issues in mobile system with battery. In this paper, we describe an DPM(Dynamic Power Management) using DVS(Dynamic Power Management) as a power management mechanism in Qplus operating system. DVS generally considers a specific device such as CPU, whereas we consider the relations with other hardware components as well as each component. We specially focus on the relation between CPU, memory and LCD devices. We also designs a kernel monitor to collect information to decide the policy for power management. According to the experimental results, the proposed method enables to save much power.