• Title/Summary/Keyword: 오차 확산

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Numerical Simulation of Lithium-Ion Batteries for Electric Vehicles (전기 자동차용 리튬이온전지 개발을 위한 수치해석)

  • You, Suk-Beom;Jung, Joo-Sik;Cheong, Kyeong-Beom;Go, Joo-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.6
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    • pp.649-656
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    • 2011
  • A model for the numerical simulation of lithium-ion batteries (LIBs) is developed for use in battery cell design, with a view to improving the performances of such batteries. The model uses Newman-type electrochemical and transfer $theories^{(1,2)}$ to describe the behavior of the lithium-ion cell, together with the Levenberg-Marquardt optimization scheme to estimate the performance or design parameters in nonlinear problems. The mathematical model can provide an insight into the mechanism of LIB behavior during the charging/discharging process, and can therefore help to predict cell performance. Furthermore, by means of least-squares fitting to experimental discharge curves measured at room temperature, we were able to obtain the values of transport and kinetic parameters that are usually difficult to measure. By comparing the calculated data with the life-test discharge curves (SB LiMotive cell), we found that the capacity fade is strongly dependent on the decrease in the reaction area of active materials in the anode and cathode, as well as on the electrolyte diffusivity.

An Analysis on the Influence of the Financial Market Fluctuations on the Housing Market before and after the Global Financial Crisis (글로벌 금융위기 전후 금융시장 변동이 주택시장에 미치는 영향 분석)

  • Kim, Sang-Hyeon;Kim, Jae-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.4
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    • pp.480-488
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    • 2016
  • As the subprime mortgage crisis spread globally, it depressed not only the financial market, but also the construction business in Korea. In fact, according to CERIK, the BSI of the construction businesses plunged from 80 points in December 2006 to 14.6 points in November 2008, and the extent of the depression in the housing sector was particularly serious. In this respect, this paper analyzes the influence of the financial market fluctuation on the housing market before and after the Global Financial Crisis using VECM. The periods from January 2000 to December 2007 and January 2008 to October 2015, before and after the financial crisis, were set as Models 1 and 2, respectively. The results are as follows. First, when the economy is good, the Gangnam housing market is an attractive one for investment. However, when it is depressed, the Gangnam housing market changes in response to the macroeconomic fluctuations. Second, the Gangbuk and Gangnam housing markets showed different responses to fluctuations in the financial market. Third, when the economy is bad, the effect of low interest rates is limited, due to the housing market risk.

Business Model of Data Service in Broadcasting and Communication Convergence (유비쿼터스시대 방송과 통신의 컨버전스 데이터 서비스 비즈니스 모델)

  • Jung, Chang-Duk;Lee, Ji-Eun
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2006.11a
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    • pp.245-249
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    • 2006
  • 디지털 컨버전스와 유비쿼터스 시대의 시작은 디지털 미디어 기술의 발전과 방송 통신 사업의 컨버전스를 가속화 시켰으며, 그 결과로DMB, WCDHA, Wibro, IP-TV, HSDPA 등의 새로운 형태의 차세대 제품과 서비스들이 뉴미디어 매체의 핵심으로 등장하고 있다. 국내에서 방송 통신의 컨버전스의 빠른 진행은 세계 최초로 디지털 멀티미디어 방송(DMB) 서비스 시작을 가능하게 하였다. DMB 서비스는 멀티미디어 서비스가 핵심이다. DMB 데이터 서비스인 Broadcasting Website Service(BWS)는 현재 지상파 DMB방송 사업자인 KBS, MBC, SBS, YTNDMB가 본방송 준비 막바지 단계이며, 삼성 전자와 LG전자를 비롯한 단말기 개발사들도 데이터 서비스를 위한 제품 출시에 서두르고 있는 등 DMB 산업의 활성화의 주역이 될 것으로 예상된다. DMB의 데이터 서비스는 뉴스, 날씨, 프로그램 정보 등의 단순 정보보기 수준에 그치지 않고, 리턴 채널을 이용한 양방향 서비스와, SMS, 전화걸기 등 휴대전화 단말의 고유기능과의 연계를 통한 다양한 서비스도 선보일 것이다. 더 나아가 향후 T-Commerce와 개인 광고 등 새로운 비즈니스 모델과 사업영역으로 확산시켜 나갈 수 있을 것이다. 그러나, 아직까지 DMB와 데이터 서비스는 초기단계로서, 표준 기술의 규격 작업, 이론적 논의들, 관련 사업자들의 비즈니스 준비 등에서 검토되어, 실제 사용자들을 대상으로한 연구 분석이 이루어 지지 않았다는 연구의 한계를 가지고 있다. 본격적으로 방송, 통신 컨버전스 데이터 서비스가 시작되면서, 사용자들에 초점을 맞춘 많은 연구가 이루어지길 바라며, 이러한 연구의 분석를 통해 또 다른 새로운 서비스와 비즈니스 기회의 창출을 기대해 본다.여 RD(Rate Distortion) 최적화 기반 모드 결정을 빨리 완료함으로써 고속 프레임간 모드 결정을 가능하게 한다. 제안된 방법은 프레임 간 모드 결정을 고속화함으로써 스케일러블 비디오 부호화기의 연산량과 복잡도를 최대 57%감소시킨다. 그러나 연산량 감소에 따른 비트율의 증가나 화질의 열화는 최대 1.74% 비트율 증가 및 0.08dB PSNR 감소로 무시할 정도로 작다., 반드시 이에 대한 검증이 필요함을 알 수 있었다. 현지관측에 비해 막대한 비용과 시간을 절약할 수 있는 위성영상해석방법을 이용한 방법은 해양수질파악이 가능할 것으로 판단되며, GIS를 이용하여 다양하고 복잡한 자료를 데이터베이스화함으로써 가시화하고, 이를 기초로 공간분석을 실시함으로써 환경요소별 공간분포에 대한 파악을 통해 수치모형실험을 이용한 각종 환경영향의 평가 및 예측을 위한 기초자료로 이용이 가능할 것으로 사료된다.염총량관리 기본계획 시 구축된 모형 매개변수를 바탕으로 분석을 수행하였다. 일차오차분석을 이용하여 수리매개변수와 수질매개변수의 수질항목별 상대적 기여도를 파악해 본 결과, 수리매개변수는 DO, BOD, 유기질소, 유기인 모든 항목에 일정 정도의 상대적 기여도를 가지고 있는 것을 알 수 있었다. 이로부터 수질 모형의 적용 시 수리 매개변수 또한 수질 매개변수의 추정 시와 같이 보다 세심한 주의를 기울여 추정할 필요가 있을 것으로 판단된다.변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을 발견하였다. 이상의 행태적 측면과 투자성과측면의 실증결과를 통하여 한국주식시장에

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Allometric Equations for Crown Fuel Biomass of Pinus koraiensis Stands in Korea (잣나무림의 수관연료량 추정을 위한 상대생장식 개발)

  • Kim, Sungyong;Jang, Mina;Lee, Byungdoo;Lee, Youngjin
    • Journal of Korean Society of Forest Science
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    • v.104 no.1
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    • pp.104-110
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    • 2015
  • The objective of this study was to develop allometric equations for the estimation of crown fuel biomass of Pinus koraiensis in Korea. A total of twenty four representative sample trees were destructively sampled in Gapyeong, Hongcheon, and Jeongseon. Crown fuels were weighed separately for each fuel category by size class and by living and dead. The results of this study showed that the needles contributed the largest biomass (16.6 kg, 34.7%), followed by live branches with size ranging from 2~4 cm (9.0 kg, 18.9%), 1~2 cm (6.6 kg, 13.8%), <0.5 cm (5.1 kg, 10.6%), 0.5~1 cm (4.9 kg, 10.3%), and dead branches (3.2 kg, 6.8%), while the live branches with 4 cm (2.4 kg, 4.9%) as the lowest. The adjusted coefficient of determination values were the highest ($R^2_{adj}=0.6021{\sim}9742$) and standard error of estimate were the lowest (S.E.E.=0.2018~0.7271) in allometric equation $lnWt={\beta}_0+{\beta}_1lnD$. The available fuels that are consumed during crown fires (i.e., needles and twigs with diameter less than 1 cm) comprised 55.6% of the total crown fuel biomass.

Simulation of Circulation and Water Qualities on a Partly Opened Estuarine Lake Through Sluice Gate (배수갑문을 통해 부분 개방된 하구호에서의 순환과 수질모의)

  • 서승원;김정훈;유시흥
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.2
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    • pp.136-150
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    • 2002
  • To improve the water quality of the recently constructed Siwhaho, sluice gates were operated to allow free exchange of water with the sea. This estuarine lake connected to the outer sea through narrow gates is affected mainly by flushing by gate operation and river flows and wind forcing sometimes. As a predicting tool far the water qualities, a three-dimensional finite volume model CE-QUAL-ICM is incorporated into a finite element hydrodynamic model, TIDE3D. In coupling these two different modules, a new error minimization technique is applied by considering conservation of mass. Model tests for one year after calibration and validation using field observation show that eutrophication and other biological changes reach quasi-steady state after initial 60 days of simulation, thus it would be necessary to consider moderate ramp up option to remove initial uncertainties due to cold start option. Sediment-water interaction might not be a concern in the long-term simulation, since its effect is negligible. Simulated results show the newly applied scheme can be applied with satisfaction not only fur lessening of eutrophic processes in an estuarine lake but also looking for some active circulation to improve water quality.

Development and validation of analytical methods for pyrifluquinazon residues determination on agricultural commodities by HPLC-UVD (HPLC-UVD를 이용한 농산물 중 pyrifluquinazon 잔류시험법 개발 및 검증)

  • Do, Jung-Ah;Kwon, Ji-Eun;Kim, Mi-Ra;Lee, Eun-Mi;Kuk, Ju-Hee;Cho, Yoon-Jae;Chang, Moon-Ik;Kwon, Kisung;Oh, Jae-Ho
    • Analytical Science and Technology
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    • v.26 no.3
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    • pp.174-181
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    • 2013
  • Pyrifluquinazon is classified with a quinazoline insecticide that regulates food intake by controling the feeding behavior acting on the endocrine or nervous system of pests such as aphids and white fly. To keep safety on pyrifluquinazon residues in agricultural commodities a simple, accurate and rapid analytical method was developed and validated using high performance liquid chromatograph (HPLC-UVD). The pyrifluquinazon residues acidified with 1% formic acid in samples were extracted with acetonitrile and partitioned with hexane subsequently to dichloromethane then purified with silica solid phase extraction (SPE) cartridge. The purified samples were detected using HPLC-UVD. The method was validated using apple and pear spiked with pyrifluquinazon at 0.02, 0.05 and 0.1 mg/kg and hulled rice, pepper, soybean at 0.05 and 0.1 mg/kg. Average recoveries were 70.5~107.9% with relative standard deviation less than 10%. The result of recoveries and overall coefficient of variation of a laboratory results in Gwangju regional FDA and Daejeon regional FDA was followed with Codex guideline (CODEX CAC/GL 40). This method is appropriated at pyrifluquinazon residues determination and will be used as official method of analysis.

Interpretation of Migration of Radionuclides in a Rock Fracture Using a Particle Tracking Method (입자추적법을 사용한 암반균열에서 핵종이동 해석)

  • Chung Kyun Park;Pil Soo Hahn;Douglas J. Drew
    • Nuclear Engineering and Technology
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    • v.27 no.2
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    • pp.176-188
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    • 1995
  • A particle tracking scheme was developed in order to model radionuclide transport through a tortuous flow Held in a rock fracture. The particle tacking method may be used effectively in a heterogeneous flow field such as rock fracture. The parallel plate representation of the single fracture fails to recognize the spatial heterogeneity in the fracture aperture and thus seems inadequate in describing fluid movement through a real fracture. The heterogeneous flow field une modeled by a variable aperture channel model after characterizing aperture distribution by a hydraulic test. To support the validation of radionuclide transport models, a radionuclide migration experiment was performed in a natural fracture of granite. $^3$$H_2O$ and $^{131}$ I are used as tracers. Simulated results were in agreement with experimental result and therefore support the validity of the transport model. Residence time distributions display multipeak curves caused by the fast arrival of solutes traveling along preferential fracture channels and by the much slower arrival of solutes following tortous routes through the fracture. Results from the modelling of the transport of nonsorbing tracer through the fracture show that diffusion into the interconnected pore space in the rock mass has a significant effect on retardation.

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A Study on the Estimation of Multi-Object Social Distancing Using Stereo Vision and AlphaPose (Stereo Vision과 AlphaPose를 이용한 다중 객체 거리 추정 방법에 관한 연구)

  • Lee, Ju-Min;Bae, Hyeon-Jae;Jang, Gyu-Jin;Kim, Jin-Pyeong
    • KIPS Transactions on Software and Data Engineering
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    • v.10 no.7
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    • pp.279-286
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    • 2021
  • Recently, We are carrying out a policy of physical distancing of at least 1m from each other to prevent the spreading of COVID-19 disease in public places. In this paper, we propose a method for measuring distances between people in real time and an automation system that recognizes objects that are within 1 meter of each other from stereo images acquired by drones or CCTVs according to the estimated distance. A problem with existing methods used to estimate distances between multiple objects is that they do not obtain three-dimensional information of objects using only one CCTV. his is because three-dimensional information is necessary to measure distances between people when they are right next to each other or overlap in two dimensional image. Furthermore, they use only the Bounding Box information to obtain the exact coordinates of human existence. Therefore, in this paper, to obtain the exact two-dimensional coordinate value in which a person exists, we extract a person's key point to detect the location, convert it to a three-dimensional coordinate value using Stereo Vision and Camera Calibration, and estimate the Euclidean distance between people. As a result of performing an experiment for estimating the accuracy of 3D coordinates and the distance between objects (persons), the average error within 0.098m was shown in the estimation of the distance between multiple people within 1m.

Characteristics of Equilibrium, Kinetics, and Thermodynamics for Adsorption of Acid Black 1 Dye by Coal-based Activated Carbon (석탄계 활성탄에 의한 Acid Black 1 염료의 흡착에 있어서 평형, 동력학, 및 열역학적 특성)

  • Lee, Jong-Jib
    • Clean Technology
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    • v.27 no.3
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    • pp.261-268
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    • 2021
  • Equilibrium, kinetics, and thermodynamics of adsorption of acid black 1 (AB1) by coal-based granular activated carbon (CGAC) were investigated with the adsorption variables of initial concentration of dye, contact time, temperature, and pH. The adsorption reaction of AB1 by activated carbon was caused by electrostatic attraction between the surface (H+) of activated carbon and the sulfite ions (SO3-) and nitrite ions (NO2-) possessed by AB1, and the degree of reaction was highest at pH 3 (97.7%). The isothermal data of AB1 were best fitted with Freundlich isotherm model. From the calculated separation factor (1/n) of Freundlich, it was confirmed that adsorption of AB1 by activated carbon could be very effective. The heat of adsorption in the Temkin model suggested a physical adsorption process (< 20 J mol-1). The kinetic experiment favored the pseudo second order model, and the equilibrium adsorption amount estimated from the model agreed to that given by the experiments (error < 9.73% ). Intraparticle diffusion was a rate controlling step in this adsorption process. From the activation energy and enthalpy change, it was confirmed that the adsorption reaction is an endothermic reaction proceeding with physical adsorption. The entropy change was positive because of an active reaction at the solid-liquid interface during adsorption of AB1 on the activated carbon surface. The free energy change indicated that the spontaneity of the adsorption reaction increased as the temperature increased.

Study of Riverline Change around Sannam Wetland in the Hangang River Estuaty using LANDSAT Image Processing (LANDSAT 위성사진을 활용한 한강하구 산남습지 인근 하안선 변화 연구)

  • Youn, Sukzun;Lee, Samhee;Jang, Changhwan
    • Journal of Wetlands Research
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    • v.23 no.2
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    • pp.154-162
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    • 2021
  • The naturally opened Han river estuary is a place where the flows of the Han river, Imjin river, Yaesung river meet with West Sea of Korea, so the hydrodynamic mechanism(Impact-Response) structure of Han river estuary is complex. Continuous observation and measurement due to the morphological characteristics at the estuary are required to maintain the estuary environment and river management facilities. However, the Sannam wetland(the study area) is in the military operation area. Therefore, Sannam wetland has the limited access under the control from military office. In 2020, there had a natural disaster due to flooding in August and COVID-19, and it made a survey hard. The noncontact survey technique, the analysis of LANDSAT images at Sannam wetland, was applied to analyze riverbed fluctuation and morphological transformation around Sannam wetland. LANDSAT images obtained from EarthExplorer, USGS and analyzed by QGIS. The analysis was performed based on the area and the distance near Sannam wetland. As a result, an erosion was happened on the downstream of the study area, and the upstream of the study area did not have any serious sediment transport. Considering the resolution of LANDSAT images, this noncontect survey technique is applicable to manage the study area. From the analysis of LANDSAT images, it is assumed that the tidal effect is greater than the inflow from the upstream. The pattern change of tidal response causes the damage of the river facilities near the Hangang river estuary.