• 제목/요약/키워드: Sequential initial

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Sequential Extraction을 이용한 Fly ash의 Cd 흡착 양상 평가

  • 이광헌;이승학;이아라;명동일;박준범;김형석
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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    • pp.376-379
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    • 2004
  • pH has been regarded as a master variable governing the heavy metal sorption on fly ash. However, the chemical constituents in the fly ash could also suggest a potential sorption site for heavy metals. So, in this study sequential extraction method is employed to evaluate the sorption behavior of fly ash for cadmium. Two different fly ashes (S-fly ash, T-fly ash) were obtained from different power plants in Korea. First, cadmium is adsorbed under four different initial pHs. And, Cd sorbed in fly ash was sequentially desorbed following the sequential extraction method suggested by Tessier. In test results, the effect of pH increase was differently exerted in two fly ash. In S-fly ash, exchangeable fraction was dominated in low initial pH, however, as increasing initial pH, the fraction bound to carbonate increased. In the T-fly ash, regardless of initial pH the fraction bound to carbonate was major part of sorption estimated. The fraction bound to Fe/Mn oxide was about 10% in T-fly ash, and 5% in S-fly ash at high pH.

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시계열 예측의 변형된 ENSEMBLE ALGORITHM (Time Series Forecasting Based on Modified Ensemble Algorithm)

  • 김연형;김재훈
    • 응용통계연구
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    • 제18권1호
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    • pp.137-146
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    • 2005
  • 신경망은 전통적인 시계열 기법들에 비해 대체적으로 예측성능의 우수함이 입증되었으나 계절성과 추세성을 갖는 시계열자료에 대해 예측력이 떨어지는 단점을 가지고 있다. 최근에는 Ensemble 기법인 Bagging Algorithm과 신경망의 혼합모형인 Bagging Neural Network이 개밭되었다. 이 기법은 분산과 편향을 많이 줄여줌으로써 더 좋은 예측을 할 수 있는 것으로 나타났다. 그러나 Ensemble 기법을 이용한 예측모형은 시계열자료를 적합 시키는데 있어 초기부여확률 및 예측자 선정시의 문제점을 가지고 있다. 이에 본 연구에서는 이러한 문제점을 해결하고 더불어 예측력을 향상시키기 위한 방법으로 초기부여확률이 균일분포가 아닌 순차적인 형태의 분포를 제시하고 신경망을 예측자로 활용한 변형된 Ensemble Algorithm을 제안한다. 또한 예측모형의 평가를 위해 실제자료를 가지고 기존 예측모형들과 제안한 방법을 이용하여 예측하고 각 MSE의 비교를 통하여 예측정확도를 알아보고자 한다.

GMM-TS를 이용한 표적기동분석용 배치구간 및 초기상태 추정 기법 (Batch Time Interval and Initial State Estimation using GMM-TS for Target Motion Analysis)

  • 김우찬;송택렬
    • 제어로봇시스템학회논문지
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    • 제18권3호
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    • pp.285-294
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    • 2012
  • Using bearing measurement only, target motion state is not directly obtained so that TMA (Target Motion Analysis) is needed for this situation. TMA is a nonlinear estimation technique used in passive SONAR systems. Also it is the one of important techniques for underwater combat management systems. TMA can be divided to two parts: batch estimation and sequential estimation. It is preferable to use sequential estimation for reducing computational load as well as adaptively to target maneuvers, batch estimation is still required to attain target initial state vector for convergence of sequential estimation. Selection of batch time interval which depends on observability is critical in TMA performance. Batch estimation in general utilizes predetermined batch time interval. In this paper, we propose a new method called the BTIS (Batch Time Interval and Initial State Estimation). The proposed BTIS estimates target initial status and determines the batch time interval sequentially by using a bank of GMM-TS (Gaussian Mixture Measurement-Track Splitting) filters. The performance of the proposal method is verified by a Monte Carlo simulation study.

이산공간에서 순차적 알고리듬(SOA)을 이용한 전역최적화 (Global Optimization Using a Sequential Algorithm with Orthogonal Arrays in Discrete Space)

  • 조범상;이정욱;박경진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.858-863
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    • 2004
  • In the optimized design of an actual structure, the design variable should be selected among any certain values or corresponds to a discrete design variable that needs to handle the size of a pre-formatted part. Various algorithms have been developed for discrete design. As recently reported, the sequential algorithm with orthogonal arrays(SOA), which is a local minimum search algorithm in discrete space, has excellent local minimum search ability. It reduces the number of function evaluation using orthogonal arrays. However it only finds a local minimum and the final solution depends on the initial value. In this research, the genetic algorithm, which defines an initial population with the potential solution in a global space, is adopted in SOA. The new algorithm, sequential algorithm with orthogonal arrays and genetic algorithm(SOAGA), can find a global solution with the properties of genetic algorithm and the solution is found rapidly with the characteristics of SOA.

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베트남 투자 중소기업의 기업가정신 지향성이 후속투자에 미치는 영향 : 국제시장 지향성과 투자성과의 매개효과를 중심으로 (The Impact of Entrepreneurial Orientation of Korean SME's Sequential Investment in Vietnam : Focusing on the mediating roles of international market orientation and investment performance)

  • 박현용;마성태;한정휴
    • 무역학회지
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    • 제45권6호
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    • pp.1-22
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    • 2020
  • This paper analyzes the influence of entrepreneurial orientation, international market orientation, and investment performance of Korean SMEs in Vietnam on sequential investment. As a result of analyzing the research model using PLS SEM, it was found that Korean SMEs make sequential investments based on investment performance rather than entrepreneurial orientation or international market orientation. In addition, entrepreneurial orientation increased internationa market orientation and had a positive effect on investment performance, which was found to have a positive effect on sequential investment. Through this study, it was clarified that there is a difference between the determinants of initial investment and sequential investment, and it was confirmed that Korean companies show stable and strategic sequential investment tendency rather than proactive and bold investment in Vietnam. In addition, the mediating effect of international market orientation and investment performance in sequential investment was confirmed. In addition, it was confirmed that entrepreneurial orientation was a valid factor in the indirect effect of sequential investment. In the future, for high entrepreneurial orientation Korean companies entered the Vietnamese market, there will be a need for policy support to provide information on Global Value Chain in Vietnam and establish networks on the country.

Multiple, Sequential, Remote Intracranial Hematomas Following Cranioplasty

  • Moon, Hong-Joo;Park, Ju-No;Kim, Sang-Dae;Lim, Dong-Jun;Park, Jung-Yul
    • Journal of Korean Neurosurgical Society
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    • 제42권3호
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    • pp.228-231
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    • 2007
  • The intracranial hemorrhage in regions remote from the site of initial operations is unusual but may present as fatal surgical complication. We report a rare case of multiple, sequential, remote intracranial hematomas after cranioplasty in a patient who did not have any prior risk factors. A 51-years-old man was transferred to the hospital after a head trauma. The brain computed tomography (CT) revealed acute subdural hemorrhage on the right hemisphere with prominent midline shifting. After performing decompressive craniectomy and hematoma removal, the patient recovered without any complications. However, the patient showed neurological deterioration immediately after cranioplasty, which was done three months after the first surgery. There was extensive hemorrhage in the posterior fossa remote from the site of the initial operation site. The brain CT taken soon after removing this hematoma evacuation displayed large epidural hematoma on the left hemisphere. This case represents posterior fossa hemorrhage after supratentorial procedure and sequential delayed hematoma on the contralateral supratentorial region thus seems very rare surgical complications. Despite several possible pathogenetic mechanisms for such remote hematomas, there are usually no clear cut relationships with each case as in our patient. However, for the successful outcome, prompt evaluation and intensive management seem mandatory.

이산공간에서 순차적 알고리듬(SOA)을 이용한 전역최적화 (Global Optimization Using a Sequential Algorithm with Orthogonal Arrays in Discrete Space)

  • 조범상;이정욱;박경진
    • 대한기계학회논문집A
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    • 제29권10호
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    • pp.1369-1376
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    • 2005
  • In structural design, the design variables are frequently selected from certain discrete values. Various optimization algorithms have been developed fDr discrete design. It is well known that many function evaluations are needed in such optimization. Recently, sequential algorithm with orthogonal arrays (SOA), which is a search algorithm for a local minimum in a discrete space, has been developed. It considerably reduces the number of function evaluations. However, it only finds a local minimum and the final solution depends on the initial values of the design variables. A new algorithm is proposed to adopt a genetic algorithm (GA) in SOA. The GA can find a solution in a global sense. The solution from the GA is used as the initial design of SOA. A sequential usage of the GA and SOA is carried out in an iterative manner until the convergence criteria are satisfied. The performance of the algorithm is evaluated by various examples.

Sequential Outage Checkers for Analyzing Cascading Outages and Preventing Large Blackouts

  • Hur, Jin;Joung, Man-Ho;Baldick, Ross
    • Journal of Electrical Engineering and Technology
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    • 제6권5호
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    • pp.585-594
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    • 2011
  • This paper presents the use of sequential outage checkers to identify the potential cascading processes that might lead to large blackouts. In order to analyze cascading outages caused by a combination of thermal overloads, low voltages, and under-frequencies following an initial disturbance, sequential outage checkers are proposed. The proposed sequential outage checkers are verified using the AEP 9-bus system, New England 39-bus system, and IEEE 118-bus system.

표본크기에 제약이 있는 누적 축차관리도 (Cumulative Sequential Control Charts with Sample Size Bound)

  • 장영순;배도선
    • 대한산업공학회지
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    • 제25권4호
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    • pp.448-458
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    • 1999
  • This paper proposes sequential control charts with an upper bound on sample size. Existing sequential control charts have no restriction on the number of observations at a sampling point. For situations where sampling and testing an item is time-consuming or expensive, sequential control charts may not be directly applied. When the number of observations in a sampling point reaches the upper bound and there is no out-of-control signal, the proposed cumulative sequential control chart defers the decision to the next sampling point of which starting value is the value of the current statistic. Two Markov chains, inner and outer chains, are used to derive the formulas for evaluating the performance of the proposed chart. It is compared with $\bar{X}$ and cumulative sum control charts with fixed and variable sample sizes. The fast initial response (FIR) feature is studied. Guidelines for the design of the proposed charts are also given.

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굴착영향을 고려한 지하공동의 구조거동연구 (A Study on the Structural Behavior of Underground Openings Considering the Effect of Excavation)

  • 최규섭;김대홍
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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    • pp.111-117
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    • 1992
  • In order to design and construct a safe and economic underground structure, it is essential to understand the structural behavior of underground openings considering the effect of the sequential excavation. Therefore, this paper includes the study of initial stress distribution before excavation and stress redistribution due to the sequential excavation. And discussion on numerical simulation techniques for the sequential excavation is also included. Then, the underground structure is analyzed using the finite element and distinct element methods of analysis considering the effect of the sequential excavation. Based on the results of the analysis, the followings are discussed: shape of the openings, effect and timing of structural reinforcements. methods and sequence of excavation.

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