• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.134-136
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• 1986

In this paper, a new power spectral estimation technique is presented. At first, by transforming the original data with the Karhunen-Loeve Transform(KLT), we can reduce the amount of the redundant information. Next, by modeling the transformed data by means of the autoregressive(AR) model and then applying the least-squares parameter estimation algorithm to this model, even more accurate spectrum estimates can be obtained. The KLT is the optimum transform for signal representation with respect to the mean-square error criterion. And the least-squares method is used to overcome the inherent shortcomings of popular burg algorithm.

• Journal of Applied Reliability
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• v.15 no.2
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• pp.84-89
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• 2015

Accelerated life tests are widely used to evaluate the product reliability within a resonable amount of time and cost. This article provides literature review about accelerated life test plans between 2006~2015. The literature on planning accelerated life tests are reviewed with respect to the test scenario, assumed accelerated model and estimation method and optimization criteria. Finally, recommendations for the future research are presented.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.2
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• pp.165-172
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• 1985

Since energy consumption of developing countries is expected to grow rapidly over the coming decades, the oil-importing developing countries are likely to encounter chronic balance-of-payments difficulties. To analyze the quantitative impacts of this problem, we develop a computable model of international trade. This paper presents four alternative cases - varying the assumptions with respect to energy supplies. This shows that relatively small difference in supplies can lead to 100% differences in the energy prices projected for 1990.

• Korean Management Science Review
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• v.12 no.3
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• pp.61-75
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• 1995

Developing a midrange computer system in a country like Korea is a difficult task. It is because of the lack of computer related technologies, appropriate manpower and the sufficient domestic market. Thus, only a few country except the United States has succeeded in developing her own model of computer systems. Fortunately, Korea became one of them. In this paper, we will present some special features of TICOM and how we successfully developed our own model of a midrange computer system with respect to system engineering point of view. The Difficulties and suggestions from the experience of the development of TICOM will also be described.

• Communications for Statistical Applications and Methods
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• v.7 no.1
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• pp.119-128
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• 2000

This paper proposes a method for detecting interactions in a two-way layout with one observation per cell. The identification of interactions in the model is not clear for they are confounding with error terms. The $L_1$-Estimation is robust with respect to a y-direction outlier in linear model so we are able to estimate main effects without affection of interactions, If an observation is classified as an outlier we conclude it contains an interaction. An empirical study compared with a classical method is performed.

• Journal of the Korean Statistical Society
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• v.9 no.1
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• pp.97-108
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• 1980

Variance components model appears often in designing experiments including time series data analysis. This paper is investigating the properties of the various procedures in estimating variance components for the two-way random model without interaction under normality. In this age of computer-oriented computations, MINQUE is found to be quite practicla because of the robustness with respect to the design configurations and parameters. Also adjusted AOV type estimation procedure is found to yield superior results over the unadjusted one.

• Journal of Industrial Technology
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• v.18
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• pp.233-240
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• 1998

In this study, ride sensitivity analysis of train with non-linear suspension elements is performed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train is parameterized. Equation of motion of the train model is derived, and using the direct differentiation method, sensitivity equations are obtained. For a nominal ride quality performance index, sensitivity analysis with respect to various design parameters regarding non-linear suspension parameters is carried out.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.857-860
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• 2006

In the present study, the method and procedure for analysis of impact damage behavior for concrete under penetration and perforation of projectile is investigated. Conservation law, equation of motion, initial and boundary conditions, and FEM formulation are introduced and derived respectively. Specially, the constitutive equation which rate-dependent damage combined with rate-dependent plasticity within the appropriate framework of theory of thermodynamics is examined. This paper aimed at the review with respect to impact damage models for concrete to develop that model. This paper is a basis research for the development of impact damage model for concrete.

• Communications of the Korean Mathematical Society
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• v.33 no.1
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• pp.53-71
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• 2018

In this paper, we provide two different descriptions for a relative derived category with respect to a subcategory ${\mathcal{X}}$ of an abelian category ${\mathcal{A}}$. First, we construct an exact model structure on certain exact category which has as its homotopy category the relative derived category of ${\mathcal{A}}$. We also show that a relative derived category is equivalent to homotopy category of certain complexes. Moreover, we investigate the existence of certain recollements in such categories.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.47-57
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• 2010

Granular soils having a large particle size have been used as a filling material in the construction of foundation, harbor, dam, and so on. Consequently, the shear behavior of this granular soil plays a key role in respect of stability of structures. For example, soil particle crushing occurring at the interface between structure and soil and/or within soil mass can cause a disturbance of ground characteristics and consequently induce issues in respect of stability of structures. In order to investigate the shear behavior according to an existence and nonexistence of particle crushing, numerical analyses were conducted by using the DEM (Discrete Element Method)-based software program PFC2D (Particle Flow Code). By dividing soil particle bonding model into crushing model and noncrushing model, total four particle bonding models were simulated and their results were compared. Noncrushing model included one ball model and clump model, and crushing model included cluster model and Lobo-crushing model. The combinations of soil particle followed the research results of Lobo-Guerrero and Vallejo (2005) which were composed of eight circles. The results showed that the friction angle was in order of clump model > cluster model > one ball model. The particle bonding model compared to one ball model and noncrushing model compared to crushing model showed higher shear strength. It was also concluded that the model suggested by Lobo-Guerrero and Vallejo (2005) is not appropriate to simulate the soil particle crushing.