• Communications for Statistical Applications and Methods
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• 제30권2호
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• pp.179-189
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• 2023

Hybrid sufficient dimension reduction (SDR) methods to a weighted mean of kernel matrices of two different SDR methods by Ye and Weiss (2003) require heavy computation and time consumption due to bootstrapping. To avoid this, Park et al. (2022) recently develop the so-called cross-distance selection (CDS) algorithm. In this paper, two variations of the original CDS algorithm are proposed depending on how well and equally the covk-SAVE is treated in the selection procedure. In one variation, which is called the larger CDS algorithm, the covk-SAVE is equally and fairly utilized with the other two candiates of SIR-SAVE and covk-DR. But, for the final selection, a random selection should be necessary. On the other hand, SIR-SAVE and covk-DR are utilized with completely ruling covk-SAVE out, which is called the smaller CDS algorithm. Numerical studies confirm that the original CDS algorithm is better than or compete quite well to the two proposed variations. A real data example is presented to compare and interpret the decisions by the three CDS algorithms in practice.

• Journal of the Korean Data and Information Science Society
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• 제28권2호
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• pp.371-381
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• 2017

국내에서 부동산 경매 낙찰가율 데이터를 활용한 Chaos 분석 연구는 전무하다. 부동산 경매분야의 데이터가 충분히 누적됨에 따라 부동산 경매 낙찰가율 시계열 분석의 의미가 커지게 되었다. 본 연구에서는 Hurst 지수, 상관차원, maximum Lyapunov 지수, 이 3가지 Chaos 분석기법을 활용하여 낙찰가율의 비선형 결정론적 동역학계적 특성을 확인하고, Chaos 분석을 통하여 얻은 결과와 실무 데이터를 비교하여, 함의를 도출한다. 높은 Hurst 지수에 따르는 추세와, maximum Lyapunov 지수의 측정을 통한 지속성, 그리고 상관차원 분석의 결과에 따라 time lag가 개시결정일에서 낙찰일, 배당요구종기일에서 낙찰일까지와 일치하는 점으로부터, Chaos 분석이 낙찰가율의 움직임을 예측하는데 유용함을 확인할 수 있었다.

• Journal of Mechanical Science and Technology
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• 제15권8호
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• pp.1090-1096
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• 2001

In this paper, new methods for efficiently solving linear acceleration equations of multibody dynamic simulation exploiting sparsity for real-time simulation are presented. The coefficient matrix of the equations tends to have a large number of zero entries according to the relative joint coordinate numbering. By adequate joint coordinate numbering, the matrix has minimum off-diagonal terms and a block pattern of non-zero entries and can be solved efficiently. The proposed methods, using sparse Cholesky method and recursive block mass matrix method, take advantages of both the special structure and the sparsity of the coefficient matrix to reduce computation time. The first method solves the η$\times$η sparse coefficient matrix for the accelerations, where η denotes the number of relative coordinates. In the second method, for vehicle dynamic simulation, simple manipulations bring the original problem of dimension η$\times$η to an equivalent problem of dimension 6$\times$6 to be solved for the accelerations of a vehicle chassis. For vehicle dynamic simulation, the proposed solution methods are proved to be more efficient than the classical approaches using reduced Lagrangian multiplier method. With the methods computation time for real-time vehicle dynamic simulation can be reduced up to 14 per cent compared to the classical approach.

• 한국안전학회지
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• 제22권3호
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• pp.81-87
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• 2007

In this study digital human models of ship construction tasks using modeling & simulation were constructed and human models' activities through human activity analysis were evaluated. Human Factors experts analyzed the actual workers' tasks using the same technique used in human activity analysis at the same time. The main objective of this study is to check a possibility of applying digital human modeling technique to ship construction tasks that are mostly non-standardized(not uniformed) whereas most applications of digital human modeling technique have been applied to standardized tasks. We evaluated postures of both real workers and digital humans by RULA. It turned out that the final scores of RULA evaluation on real workers are the same as the RULA scores for digital humans. However, there were differences of RULA detail scores between real workers and digital humans in the several processes related with the wrist twist and deviations. Those differences are considered to be resulted from the error in the on-site measuring worker's body dimension which could be reduced by accurate tools to correct data for body dimension and digital real drawings for facilities. The results showed possibility of application of digital human modeling and ergonomic analysis on informal work operations as well as formal operations in the shipbuilding industry.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제7권1호
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• pp.7-18
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• 2000

Let M be an n-dimensional CR submanifold CR dimension n - l of a complex projective space M. We characterize M of $\bar{M}$ in terms of an estimations of the length of the derivative of Ricci tensor of the length of Ricci tensor.

• 한국의류학회지
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• 제32권3호
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• pp.443-453
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• 2008

The purpose of this study was to identify the perception between real and ideal body shapes of college students and to investigate the preferred body shape of college students. The research subjects numbered one hundred forty five male and female students, aged 20 to 29, who lived in Gwangju and Chonnam province. The anthropometric data was collected including both direct and indirect measurements. The data was analyzed by mean and standard deviation, t-test, and factor analysis. The results of t-test showed the significant difference($p{\leq}.001$) between real body size and ideal body size. The result showed that male students want to have bigger chest circumference and a taller height than their real body, the research also showed that the female students want to have a narrow bust and hip width along with a taller height than real body. Regarding ideal body shape, male students pursued bigger height and want an inverted-triangle body shape. On the other hand, female students pursued bigger height and slim body shape. This study established the factors(dimension of torso, height, the side shape of torso, and shoulder shape) as the perception between real and ideal body shapes. In terms of real body, the factor analysis shows two contrasting results in which the height is the most important factor for female students, while the torso dimension is the most important factor for male students. In terms of ideal body, the height factor is the most important for both the male and female students.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.166-169
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• 2006

Our country's coast is vulnerable area to natural disaster which the repetitive damages occur every year including a loss of lives, the damage of facilities and erosion mostly except for the east coast because of a typhoon, tidal waves, sea water overflowing by topographic structure of low-lying gentle slope and shallow sea. However, as for prevention of natural disaster occurring every year, the situation is that it's centered on the restorationcentered measures and the general disaster prevention research to minimize damages at the time of disaster occurrence is insufficient. This study intendedlop t to devehe techniques possible for real time sampling of damage prediction areas on Web in order to support decision making for damage prevention and establishment of disaster prevention policy. For this, the thematic map was produced related to disaster based on high-resolution satellite picture, and the environmental DB similar to real world was constructed through topographic construction of three-dimension integrating the parts of land and the sea. In addition, the system was developed possible for the expression of damageable regions by real time grasp of dangerous regions at the time of disaster occurrence through over flowing simulation of three-dimension, and it's intended to prepare a basis to minimize damages to disaster situations through it.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.399-404
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• 2001

In CNC machining, a 3D(3-dimension) linear segment and a 2D(2-dimension) circular arc are general forms given by CAD/CAM system. Generally, the 2D circular arc machining is processed using dividing into some linear segments. A 3D circular arc also don't exist in the standard form of NC data. This paper present a algorithm and method for real-time machining of a circular arc(not only the 2D one, but also the 3D one). The 3D circular arc machining is based on the 2D circular arc machining. It only needs making a new coordinate system, converting given 3D points(a start point, a end point, and a center point of a 3D circular arc) into points of the new coordinate system, and processing a inverse transformation about a interpolated point. The proposed algorithm was implemented and simulated on PC system. It was confirmed to give a gcod result.

• 한국멀티미디어학회논문지
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• 제19권8호
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• pp.1587-1596
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• 2016

This paper presents an interactive locomotion controller using motion capture data and inverted pendulum model. Most of the data-driven character controller using motion capture data have two kinds of limitation. First, it needs many example motion capture data to generate realistic motion. Second, it is difficult to make natural-looking motion when characters navigate dynamic terrain. In this paper, we present a technique that uses dimension reduction technique to motion capture data together with the Gaussian process dynamical model (GPDM), and interpolates the low-dimensional data to make final motion. With the low-dimensional data, we can make realistic walking motion with few example motion capture data. In addition, we apply the inverted pendulum model (IPM) to calculate the root trajectory considering the real-time user input upon the dynamic terrain. Our method can be used in game, virtual training, and many real-time applications.

• Communications for Statistical Applications and Methods
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• 제22권3호
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• pp.305-312
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• 2015

We extend a generalized partially linear single-index model and newly define a generalized partially double-index model (GPDIM). The philosophy of sufficient dimension reduction is adopted in GPDIM to estimate unknown coefficient vectors in the model. Subsequently, various combinations of popular sufficient dimension reduction methods are constructed with the best combination among many candidates determined through a bootstrapping procedure that measures distances between subspaces. Distinguishing values are newly defined to match the estimates to the corresponding population coefficient vectors. One of the strengths of the proposed model is that it can investigate the appropriateness of GPDIM over a single-index model. Various numerical studies confirm the proposed approach, and real data application are presented for illustration purposes.