• 방송공학회논문지
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• 제16권1호
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• pp.178-181
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• 2011

최근, 모바일 기기의 발전, 팬/틸트 카메라를 사용한 지능형 감시 시스템 등이 발전하면서 비정적 환경에서의 추적알고리즘에 대한 연구가 활발하게 이루어지고 있다. 비정적 환경에서는 배경에 대한 모델링이 어렵기 때문에 주로 컬러, 텍스쳐 등의 피쳐를 이용한 객체 추적이 이루어진다. 이 경우 배경에 나타나는 객체의 컬러와 유사한 컬러들로 인해 추적이 불안정해진다. 본 논문에서는 컬러에 기반한 객체추적 방법들 중에 상대적으로 안정적이고 속도가 빠른 중심 이동 (Centroid Shifting) 기반의 추적 알고리즘을 더욱 안정화하기 위해 배경에 대한 영향을 줄이고, 시간 필터링을 접목하는 방법에 대하여 제안하고자 한다.

• 대한기계학회논문집
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• 제18권4호
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• pp.920-932
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• 1994

The combustion phenomena of a reciprocating engine is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design, because the flame speed is mainly determined by the turbulence at compression(TDC) process in S.I. engine. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of their relationship is not well known. This paper describes cycle resolved LDV measurement of turbulent flow inside the cylinder of a 4-valve engine under motoring(non-firing) conditions, and studies the effect of intake port configurations on the turbulence characteristics using following parameters ; Eulerian temporal autocorrelation coefficient, turbulence energy spectral density function, Taylor micro time scale, integral time scale, and integral length scale.

• Asian-Australasian Journal of Animal Sciences
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• 제12권7호
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• pp.1162-1169
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• 1999

Modern livestock production facilities face both challenges and opportunities with respect to sustainable manure management practices. Nutrient recycling is constrained by the size of modern livestock operations, the low nutrient density of liquid manures, and the spatial and temporal variability of manure nutrient concentrations. These constraints can and must be addressed or farmers will be increasingly drawn to nutrient wasting strategies such as anaerobic lagoons, wetlands, and other systems designed to treat and discharge nutrients to the environment. Intentional discharge of nutrients is difficult to justify in a sustainable agricultural production system, since replacing those nutrients through chemical fertilization requires considerable expenditure of energy. In contrast, there are several currently viable technologies which provide the homogenization and stabilization needed to successfully compete against chemical fertilizers, including composting, pelletization, and anaerobic digestion. Some of these technologies, particularly anaerobic digestion and composting, also open up increased opportunities to market the energy and nutrients in manure to non-agricultural uses. Future advances in biotechnology are likely to demonstrate additional options to transform manure into fuels, chemicals, and other non-agricultural products.

• 대한임베디드공학회논문지
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• 제11권2호
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• pp.67-78
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• 2016

The emerging Spin-Transfer Torque RAM (STT-RAM) is a promising component that can be used to improve the efficiency as a result of its high storage density and low leakage power. However, the state-of-the-art STT-RAM is not ready to replace SRAM technology due to the negative effect of its write operations. The write operations require longer latency and more power than the same operations in SRAM. Therefore, a hybrid cache with SRAM and STT-RAM technologies is proposed to obtain the benefits of STT-RAM while minimizing its negative effects by using SRAM. To efficiently use of the hybrid cache, it is important to place write intensive data onto the cache. Such data should be placed on SRAM to minimize the negative effect. Thus, we propose a technique that optimizes placement of data in main memory. It drives the proper combination of advantages and disadvantages for SRAM and STT-RAM in the hybrid cache. As a result of the proposed technique, write intensive data are loaded to SRAM and read intensive data are loaded to STT-RAM. In addition, our technique also optimizes temporal locality to minimize conflict misses. Therefore, it improves performance and energy consumption of the hybrid cache architecture in a certain range.

• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.145-150
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• 2008

This thesis explores the problem of reconstructing a three-dimensional(3D) scene given a set of images or image sequences of the scene. It describes efficient methods for the 3D reconstruction of static and dynamic scenes from stereo images, stereo image sequences, and images captured from multiple viewpoints. Novel methods for image-based and volumetric modelling approaches to 3D reconstruction are presented, with an emphasis on the development of efficient algorithm which produce high quality and accurate reconstructions. For image-based 3D reconstruction a novel energy minimisation scheme, Iterated Dynamic Programming, is presented for the efficient computation of strong local minima of discontinuity preserving energyy functions. Coupled with a novel morphological decomposition method and subregioning schemes for the efficient computation of a narrowband matching cost volume. the minimisation framework is applied to solve problems in stereo matching, stereo-temporal reconstruction, motion estimation, 2D image registration and 3D image registration. This thesis establishes Iterated Dynamic Programming as an efficient and effective energy minimisation scheme suitable for computer vision problems which involve finding correspondences across images. For 3D reconstruction from multiple view images with arbitrary camera placement, a novel volumetric modelling technique, Embedded Voxel Colouring, is presented that efficiently embeds all reconstructions of a 3D scene into a single output in a single scan of the volumetric space under exact visibility. An adaptive thresholding framework is also introduced for the computation of the optimal set of thresholds to obtain high quality 3D reconstructions. This thesis establishes the Embedded Voxel Colouring framework as a fast, efficient and effective method for 3D reconstruction from multiple view images.

• 한국대기환경학회지
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• 제21권1호
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• pp.63-72
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• 2005

In order to understand regional wind characteristics and to estimate offshore wind resources, a wind map of the Korean Peninsula was established using remote-sensing data from the satellite, U.S. NASA Quik SCAT which has been deployed for the Sea Winds Project since 1999. According to the linear regression result between the wind map data and in-situ marine-buoy data, the correlation factor was greatly improved up to 0.87 by blending the remote-sensing data of Quik SCAT with U.S. NCEP/NCAR CDAS reanalysis data to eliminate precipitation interference and to increase temporal resolution. It is found from the established wind map that the wind speed in winter is prominent temporally and the South Sea shows spatially high energy density over the wind class 6. The reason is deduced that the north-west winds through the Yellow Sea and the north-east winds through the East Sea derived by the low pressure developed in Japan are accelerated passing through the Korea Channel and formed high wind energy region in the South Sea; the same trends are confirmed from the statistical analysis of the meteorological observation data of KMA.

• 천문학회보
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• 제39권1호
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• pp.29-29
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• 2014

A fundamental problem in space physics is to explain the origin of energetic charged particles in space close to the Earth and the significant temporal variations of their flux. The particles are primarily electrons and protons although energetic heavy ions such as O+ are sometimes non-negligible. By "energetic" we mean a rather broad energy range of particles from a few tens of keV to well above MeV. Drastic variations of the particle fluxes (by >3 orders of magnitude) occur over both a short time scale like a few minutes and a long time scale like the 11-year sunspot cycle. In this talk I will focus on relativistic energy electrons (~MeV) trapped within the Earth's magnetosphere. They are a primary element of the space weather since they can cause damage to satellites, so often called "killer electrons". Considering that the source particles in both the solar wind and the ionosphere are relatively cold (~eV), the quasi-permanent existence of these very energetic particles close to the Earth has been a surprise to space physicists for decades. Complex electromagnetic processes such as wave-particle interactions within the magnetosphere are believed to play a major role in generating these killer electrons. While detailed physics remains an active research area, for this lecture I will introduce a synthesized picture of how solar activities are related to wave-particle interaction physics inside the magnetosphere. This can be applied to other astrophysical systems.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.191-202
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• 2013

A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (~300 seconds). However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy may be due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1318-1325
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• 2017

Direct Numerical Simulation (DNS) serves as an irreplaceable tool to probe the complexities of multiphase flow and identify turbulent mechanisms that elude conventional experimental measurement techniques. The insights unlocked via its careful analysis can be used to guide the formulation and development of turbulence models used in multiphase computational fluid dynamics simulations of nuclear reactor applications. Here, we perform statistical analyses of DNS bubbly flow data generated by Bolotnov ($Re_{\tau}=400$) and LueTryggvason ($Re_{\tau}=150$), examining single-point statistics of mean and turbulent liquid properties, turbulent kinetic energy budgets, and two-point correlations in space and time. Deformability of the bubble interface is shown to have a dramatic impact on the liquid turbulent stresses and energy budgets. A reduction in temporal and spatial correlations for the streamwise turbulent stress (uu) is also observed at wall-normal distances of $y^+=15$, $y/{\delta}=0.5$, and $y/{\delta}=1.0$. These observations motivate the need for adaptation of length and time scales for bubble-induced turbulence models and serve as guidelines for future analyses of DNS bubbly flow data.

• 분석과학
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• 제23권4호
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• pp.347-356
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• 2010

도심 지역의 하수관거에서 발생하는 주요 악취성분들의 발생특성 및 배출경향을 평가하였다. 하수관거에서 발생하는 총 6 가지의 지정 악취물질들($H_2S$, $CH_3SH$, DMS, DMDS, $CH_3CHO$, $NH_3$)을 주 대상으로 선정하여 조사를 실시하였다. 건조한 조건과 습한 조건을 유지하는 2개의 비교대상 하수관거에서 악취시료를 채취하였다. 측정한 악취물질들을 농도기준의 절대값과 이를 경험식에 주입하여 산출한악취지수(OI, SOI)를 동시에 활용하는 방식으로 비교분석을 하였다. 실험 결과, 전체 분석 성분 중 $CH_3SH$, $H_2S$, DMS 등의 환원황화합물(reduced sulfur compounds: RSC) 성분들이 악취세기에 큰 영향을 미치는 것으로 나타났다. 또 연구결과들을 전체적으로 종합해 보면, 주요 악취성분들의 일간 발생경향은 식생활 및 배수 등의 인간활동과 어느 정도 연관성을 띄고 있음을 알 수 있었다.