• Title/Summary/Keyword: 이중차분

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Electrokinetically Flow-Induced Streaming Potential Across the Charged Membrane Micropores: for the Case of Nonlinear Poisson-Boltzmann Electric Field (하전된 멤브레인 미세기공에서의 계면동전기적 유동에 의한 흐름전위: 비선형 Poisson-Boltzmann 전기장을 갖는 경우)

  • Myung-Suk Chun
    • Membrane Journal
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    • v.13 no.1
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    • pp.37-46
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    • 2003
  • The electrokinetic effect can be found in cases of the fluid flowing across the charged membrane micropores. The externally applied body force originated from the electrostatic interaction between the nonlinear Poisson-Boltzmann field and the flow-induced electrical field is taken into the equation of motion. The electrostatic potential profile is computed a priori by applying the finite difference scheme, and an analytical solution to the Navier-Stokes equation of motion for slit-like pore is obtained via the Green's function. An explicit analytical expression for the flow-induced streaming potential is derived as functions of relevant physicochemical parameters. The influences of the electric double layer, the surface potential of the wall, and the charge condition of the pore wall upon the velocity profile as well as the streaming potential are examined. With increasing of either the electric double layer thickness or the surface potential, the average fluid velocity is entirely reduced, while the streaming potential increases.

Impact of Tropospheric Modeling Schemes into Accuracy of Estimated Ellipsoidal Heights by GPS Baseline Processing: Experimental Analysis and Results (GPS 기선해석에 의한 타원체고 추정에서 대류권 오차 보정기법이 정확도에 미치는 영향에 관한 실험적 분석)

  • Lee, Hungkyu
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.36 no.4
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    • pp.245-254
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    • 2018
  • Impact of tropospheric correction techniques on accuracy of the GPS (Global Positioning System) derived ellipsoidal heights has been experimentally assessed in this paper. To this end, 247 baselines were constructed from a total of 88 CORS (Continuously Operating Reference Stations) in Korea. The GPS measurements for seven days, acquired from the so-called integrated GNSS (Global Navigation Satellite Systems) data center via internet connection, have been processed by two baseline processing software packages with an application of the empirical models, such as Hopfield, modified Hopfield and Saastamoinen, and the estimation techniques based on the DD (Double-Differenced) measurements and the PPP (Precise Point Positioning) technique; hence a total number of the baseline processed and tested was 8,645. Accuracy and precision of the estimated heights from the various correction schemes were analyzed about baseline lengths and height differences of the testing baselines. Details of these results are summarized with a view to hopefully providing an overall guideline of a suitable selection of the modeling scheme with respect to processing conditions, such as the baseline length and the height differences.

Design of Double Bond Down Converting Mixer Using Embeded Balun Type (발룬 내장형 이중대역 하향 변환 믹서 설계 및 제작)

  • Lee, Byung-Sun;Roh, Hee-Jung;Seo, Choon-Weon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.6
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    • pp.141-147
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    • 2008
  • This paper describes the design of frequency down converting Mixer in the receiver to use compound semiconductor and CMOS product process. The basic theory and structure of frequency down converting Mixer is surveyed, and we design mixer circuit with active balun which use the compound semiconductor and CMOS process. This mixer convert a single ended signal to differential signal at input port of RF and LO instead of matching circuit to get dual band balanced mixer structure and characteristic broadband. This designed mixer has a conversion gain $-1{\sim}-6[dB]$ at $2{\sim}6[GHz]$ bandwidths. However, the simulation of the designed mixer with active balun has the result of a 7[dB] conversion gain for -2[dBm] LO input power and -10[dBm] input P1[dB] at 5.8[GHz].

The Effect of Marriage Subsidy on Marriages: Focusing on Marriage Immigrants in South Korea 2004-2018 (결혼보조금이 결혼에 미친 영향: 2004-2018 한국의 결혼이민자를 중심으로)

  • PARK, Jihyun
    • Journal of Labour Economics
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    • v.43 no.2
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    • pp.1-39
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    • 2020
  • This paper analyzes the effect of marriage subsidy, which was provided by some municipalities of South Korea from 2006, on marriage. Marriage subsidy, targeted for international marriage between Korean men and foreign women, increases the economic incentive for international marriage. Using the Korean marriage record during 2004-2018 and exploiting the variation in marriage subsidy across regions(administrative level 2, si/gun/gu) and years with difference-in-differences method, I find that marriage subsidy significantly increases the probability of a single Korean man marrying a foreign woman. I found no evidence on crowd out effect on marrying a Korean woman, and the effect of subsidy on total marriage was significantly positive. Subgroup analysis shows that the effect of marriage subsidy on international marriage was strongest for the older and high school graduated men.

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A Numerical Model for Nuclide Migration in the Far-field of the Repository (처분장 Far-field에서의 핵종이동 수치 모델)

  • Lee, Youn-Myoung;Lee, Han-Soo;Park, Heui-Joo;Cho, Won-Jin;Han, Kyong-Won;Park, Hun-Hwee
    • Nuclear Engineering and Technology
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    • v.21 no.4
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    • pp.267-276
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    • 1989
  • A numerical model for nuclide migration through fractured rock media has been developed. Nuclide transport with groundwater in rock fissures and the diffusion of nuclides into rock matrix are considered one-dimensionally . In the safety assessment of the repository for radioactive waste, this one-dimensional model by the finite-difference scheme, which enables us not only to use more realistic boundary conditions but also to model the nonhomogeneous rock medium as the multilayered media, can be used effectively with the analytical mode. The solution by the numerical model will be verified analytically, and then extended to the double-layered rock medium transport model.

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Information Security Investment and Security Breach: Empirical Study on the Reverse Causality (정보보호 투자와 침해사고의 인과관계에 대한 실증분석)

  • Shin, Ilsoon;Jang, Wonchang;Park, Heeyoung
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.23 no.6
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    • pp.1207-1217
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    • 2013
  • This study utilizes raw data from "Research on the actual condition of firms' information security" of KISA (2010) and constructs panel dataset to analyze a causal relationship between information security investment and security breach. Using Difference in Difference estimation method we find the following results. First, while the usual causality that information security investment reduces security breach is not supported, the reverse causality that security breach increases information security investment is well explained. Second, contrary to the conventional wisdom, firms in the finance/insurance business sector show the most significant reverse causality pattern.

Detecting Foreground Objects Under Sudden Illumination Change Using Double Background Models (이중 배경 모델을 이용한 급격한 조명 변화에서의 전경 객체 검출)

  • Saeed, Mahmoudpour;Kim, Manbae
    • Journal of Broadcast Engineering
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    • v.21 no.2
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    • pp.268-271
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    • 2016
  • In video sequences, foreground object detection being composed of a background model and a background subtraction is an important part of diverse computer vision applications. However, object detection might fail in sudden illumination changes. In this letter, an illumination-robust background detection is proposed to address this problem. The method can provide quick adaption to current illumination condition using two background models with different adaption rates. Since the proposed method is a non-parametric approach, experimental results show that the proposed algorithm outperforms several state-of-art non-parametric approaches and provides low computational cost.

Novel Quadrature Branch-line Coupler Using CPW-to-Microstrip Transitions (마이크로스트립 전이를 이용하는 CPW Branch-line 커플러)

  • Lee, Jung-Ho;Lee, Hae-Yeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.5
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    • pp.10-16
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    • 2000
  • This paper presents new double-sided 3-dB branch-line coupler using CPW-to-Microstrip via-hole transitions for the multi-layer applications. The characteristic impedance is obtained using the even-odd mode method, and the circuit performance Is accurately estimated by the Finite Difference Time Domain(FDTD) method. The fabricated double-sided 3-dB branch-line coupler has less than 0.3 dB power dividing imbalance and 1。 phase imbalance, greater than 30 dB isolation, and 25 dB return loss over a 20% bandwidth centered at 2 GHz. Calculated and fabricated results show that this coupler provides better performance as compared to the conventional microstrip branch-line couplers.

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Study on the Improvement of the Positioning Accuracy for Inverted RTK Using FARA (FARA를 이용한 Inverted RTK 측위 정확도 향상에 대한 연구)

  • Choi Byung Kygu;Lim Sam Sung
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.22 no.3
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    • pp.217-223
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    • 2004
  • In order to improve real-time positioning accuracy, a number of methods have been tested and one of those is the inverted RTK(Real-time kinematic) that gives a precise positioning by handling carrier phase measurements. For the inverted RTK positioning, it needs the L1 phase measurement at least for 1~2 minutes and the additional reference stations/communication system and a data processing server are required. The L1 code and carrier phase measurements for real-time application are used simultaneously and then Kalman filter is applied to estimate integer ambiguities. Double differenced integer ambiguities are resolved by utilizing the FARA(Fast Ambiguity Resolution Approach). In this paper, we propose the method to improve the positioning accuracy and performed the field tests for several baselines from DAEJ reference station in KAO(Korea Astronomy Observatory).

A Study on Interaction of Estuarial Water and Sediment Transport (하구수와 표사의 상호작용에 관한 연구)

  • Lee, H.;Lee, J.W.
    • Journal of Korean Port Research
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    • v.14 no.4
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    • pp.451-461
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    • 2000
  • The design and maintenance of navigation channel and water facilities of an harbor which is located at the mouth of river or at the estuary area are difficult due to the complexity of estuarial water and sediment circulation. Effects of deepening navigable waterways, of changing coastline configurations, or of discharging dredged material to the open sea are necessary to be investigated and predicted in terms of water quality and possible physical changes to the coastal environment. A borad analysis of the transport mechanism in the estuary area was made in terms of sediment property, falling velocity, concentration and flow characteristics. In order to simulate the transport processes, a two-dimensional finite element model is developed, which includes erosion, transport and deposition mechanism of suspended sediments. Galerkin’s weighted residual method is used to solve the transient convection-diffusion equation. The fluid domain is subdivided into a series of triangular elements in which a quadratic approximation is made for suspended sediment concentration. Model could deal with a continuous aggregation by stipulating the settling velocity of the flocs in each element. The model provides suspended sediment concentration, bed shear stress, erosion versus deposition rate and bed profile at the given time step.

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