• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.102-109
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• 2005

In this study, a prototype model of earthquake loss estimation method will be proposed for the quantitative and qualitative damage evaluation of buried pipeline subjected to Permanent Ground Deformation(PGD) due to liquefaction. With this objective, domestic and foreign status of the arts related with earthquake loss estimation method is summarized at first. Domestic development of computer aided earthquake loss estimation method seems to be difficult for the time being. Thus, referring to HAZUS : Earthquake Loss Estimation Methodology which is developed by FEMA (Federal Emergency Management Agency) and NIBS (National Institute of Building Sciences), earthquake loss estimation procedure of buried pipeline subjected to PGD due to liquefaction are proposed, and then exemplary loss estimation are executed. Considering that there have been no practical earthquake loss estimation method and procedure in Korea, the research accomplishments such as above are considered to be helpful for the substantial development of earthquake loss estimation method of buried pipeline subjected to PGD due to liquefaction.

• Communications for Statistical Applications and Methods
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• 제12권2호
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• pp.285-294
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• 2005

This paper deals with the comparison of parameter estimation methods in a 3-parameter Kappa distribution which is sometimes used in flood frequency analysis. Method of moment estimation(MME), L-moment estimation(L-ME), and maximum likelihood estimation(MLE) are applied to estimate three parameters. The performance of these methods are compared by Monte-carlo simulations. Especially for computing MME and L-ME, three dimensional nonlinear equations are simplified to one dimensional equation which is calculated by the Newton-Raphson iteration under constraint. Based on the criterion of the mean squared error, L-ME (or MME) is recommended to use for small sample size( n$\le$100) while MLE is good for large sample size.

• International Journal of Computer Science & Network Security
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• 제24권6호
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• pp.17-22
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• 2024

Software cost and schedule estimation is usually based on the estimated size of the software. Advanced estimation techniques also make use of the diverse factors viz, nature of the project, staff skills available, time constraints, performance constraints, technology required and so on. Usually, estimation is based on an estimation model prepared with the help of experienced project managers. Estimation of software cost is predominantly a crucial activity as it incurs huge economic and strategic investment. However accurate estimation still remains a challenge as the algorithmic models used for Software Project planning and Estimation doesn't address the true dynamic nature of Software Development. This paper presents an efficient approach using the contemporary Constructive Cost Model (COCOMO) augmented with the desirable feature of fuzzy logic to address the uncertainty and flexibility associated with the cost drivers (Effort Multiplier Factor). The approach has been validated and interpreted by project experts and shows convincing results as compared to simple algorithmic models.

• 한국군사과학기술학회지
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• 제14권4호
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• pp.590-597
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• 2011

The IDRS provides detection, classification and bearing/range estimation by performing wavefront curvature analysis on an intercepted active transmission from target. Especially, a estimate of the target bearing/range that significantly affects the optimal operation of own submarine is required. Target bearing/range can be estimated by wavefront curvature ranging which use the difference of time arrival at sensors. But estimation ambiguity occur in bearing/range estimation due to a number of peaks caused by high center frequency and limited bandwidth of the intercepted active transmission and distortion caused by noise. As a result the bearing/range estimation performance is degraded. To estimate target bearing/range correctly, bearing/range estimation method that eliminate estimation ambiguity is required. In this paper, therefore, for wavefront curvature ranging, NLS cost function with curve fitting method is proposed, which provide robust bearing/range estimation performance by eliminating estimation ambiguity. Through simulation the performance of the proposed bearing/range estimation methods are verified.

• 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.

• Journal of Astronomy and Space Sciences
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• 제35권4호
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• pp.263-277
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• 2018

This paper presents a vision-based relative pose estimation algorithm and its validation through both numerical and hardware experiments. The algorithm and the hardware system were simultaneously designed considering actual experimental conditions. Two estimation techniques were utilized to estimate relative pose; one was a nonlinear least square method for initial estimation, and the other was an extended Kalman Filter for subsequent on-line estimation. A measurement model of the vision sensor and equations of motion including nonlinear perturbations were utilized in the estimation process. Numerical simulations were performed and analyzed for both the autonomous docking and formation flying scenarios. A configuration of LED-based beacons was designed to avoid measurement singularity, and its structural information was implemented in the estimation algorithm. The proposed algorithm was verified again in the experimental environment by using the Autonomous Spacecraft Test Environment for Rendezvous In proXimity (ASTERIX) facility. Additionally, a laser distance meter was added to the estimation algorithm to improve the relative position estimation accuracy. Throughout this study, the performance required for autonomous docking could be presented by confirming the change in estimation accuracy with respect to the level of measurement error. In addition, hardware experiments confirmed the effectiveness of the suggested algorithm and its applicability to actual tasks in the real world.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.309-323
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• 2002

This paper studies the parameter estimation problem for a steady state flow in an inhomogeneous medium. Our approximation scheme could be used when the diffusion coefficient is singular. The function space parameter estimation convergence(FSPEC) is considered and numerical simulations are performed.

• 한국음향학회지
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• 제19권6호
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• pp.53-61
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• 2000

잡음환경에서의 음성인식 성능향상을 위해서는 서로 다른 잡음환경으로 인한 mismatch를 줄이는 것이 중요하다. 이를 위해 계산이 간단하고 잡음환경에서 비교적 우수한 성능을 내고 있는 스펙트럼 차감법이 널리 사용되고 있다. 본 논문에서는 스펙트럼 차감법을 적용하기 위한 잡음 스펙트럼 추정방법으로 히스토그램 처리방법을 도입한다. 히스토그램 처리방법은 음성이 아닌 구간의 검출이 필요없으며 시간에 따라 변화하는 시변잡음에도 적용 가능한 장점이 있다. 그러나 히스토그램 처리방법으로 신뢰도 높은 잡음 스펙트럼의 평균값을 추정하더라도 스펙트럼 차감법을 적용했을 때의 잔여 잡음의 문제가 발생한다. 이를 해결하기 위하여 잡음추정 과정에 사용되었던 히스토그램의 분포특성을 고려한 새로운 over-estimation 적용방식을 제안한다. 제안된 방식은 측정된 잡음의 분포에 따라 적응적으로 over-estimation의 정도를 결정함으로써 SNR 변화에 따른 영향이 적은 장점이 있다. 자동차 소음 환경에서의 화자독립 고립단어 인식실험 결과, 기존의 over-estimation factor를 적용한 경우보다 제안된 방식의 인식성능이 개선되었다.

• 한국수학교육학회지시리즈A:수학교육
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• 제29권1호
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• pp.21-34
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• 1990

This is a study on an instruction of estimation for error correction in the calculation with a computer or a calculator. The aim of this study is to survey a new aspect of calaulation teaching and the teaching strategy of estimation and finally to frame a new curriculum model of estimation instruction. This research required a year and the outcomes of the research can be listed as follows: 1. Social utilities of estimation were made clear, and a new trend of calculation teaching related to estimation instruction was shown. 2. The definition of estimation was given and actual examples of conducting an estimation among pupils in lower grades were given for them to have abundant experiences. 3. The ways of finding estimating values in fraction and decimal fraction were presented for the pupils to be able to conduct an estimation. 4. The following contents were given as a basic strategy for estimation. 1) Front-end strategy 2) Clustering strategy 3) Rounding strategy 4) Compatible numbers strategy 5) Special numbers strategy 5. In an instuction of estimation the meaning, method. and process of calculation and calculating algorithm were reviewed for the cultivation of children's creativity through promoting their basic skill, mathematical thinking and problem-solving ability. 6. The following contents were also covered as an estimation strategy for measurement 1) Calculating the sense of quantity on the size of unit. 2) Estimating the total quantity by frequent repetition of unit quantity. 3) Estimating the length and the volume by weighing. 4) Estimating unknown quantity based on the quatity already known. 5) Estimating the area by means of equivalent area transformation. 7. The ways of instructing mental computation were presented. 8. Reviews were made on the curricular and the textbook contents concerning estimation instructions both in Korea and Japan. and a new model of curriculum was devised with reference to estimation instruction data of the United States.

• 대한수학교육학회지:수학교육학연구
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• 제16권4호
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• pp.273-295
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• 2006

본 연구는 수학학습 능력이 서로 다른 3학년 6명의 학생을 대상으로 총 6회의 실생활 문제 상황을 활용한 어림수업을 실시하여 어림에 어떤 변화가 보이는지 분석하고 어림학습 전과 후에 실생활 문제 상황 학습지를 투입하여 그에 대한 변화를 비교해 보았다. 실생활 문제 상황을 활용하여 역할극으로 진행된 어림수업에서 학생들은 자신의 생활과 친숙한 문제 상황 속에서 어림을 사용하였으며, 문제 상황에 따라 적절한 자리 수를 결정할 수 있음을 확인하였다.