• Annals of Clinical Neurophysiology
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• v.20 no.2
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• pp.57-65
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• 2018

Near-infrared spectroscopy (NIRS) monitoring has been used mainly to detect reduced perfusion of the brain during orthostatic stress in order to assess orthostatic intolerance (OI). Many studies have investigated the use of NIRS to reveal the pathophysiology of patients with OI. Research using NIRS in other neurological diseases (e.g., stroke, epilepsy, and migraine) is continuing. NIRS may play an important role in monitoring the regional distribution of the hemodynamic flow in real time and thereby reveal the underlying pathophysiology and facilitate the management of not only patients with OI symptoms but also those with various neurological diseases.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.365-368
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• 2000

This paper proposes a new heuristic method of constructing process capability indices (PCIs) for skewed populations. It is based on weighted standard deviation (WSD) method which decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts the value of PCI using decomposed deviations in accordance with the skewness estimated from sample data. For symmetric populations, the proposed PCIs reduce to standard PCIs. Asymptotic distributions of the estimators of the PCIs are obtained. The performances of the proposed methods are compared with those of the standard and other methods. Numerical comparisons indicate that considerable improvements over existing methods can be achieved by the use of WSD method when the underlying distribution is skewed.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.33-51
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• 1998

The industrial operation is one of the three basic modes of shipping operation with liner and Tramp operations. Industrial operators usually control vessels of their own or on a time charter to minimize the cost of shipping their cargoes. Such operations abound in shipping of bulk commodities, such as oil, chemicals and ores. This work is concerned with an operational optimization analysis of the fleet owned by a major oil company. a typical industrial operator. The operational optimization problem of the fleet of a major oil company is divided Into two phase problem. The front end corresponds to the optimization problem of the transportation of crude oil. product mix. and the distribution of product oil to comply with the demand of the market. The back end tackles the scheduling optimization problem of the fleet to meet the seaborne transportation demand derived from the front end. A case study reflecting the practices of an international major oil company is demonstrated to make clear the underlying ideas.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.435-444
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• 1995

We propose a new approach to the calculation of the exact cells loss probability in a shared buffer ATM multiplexer, which is loaded with homogeneous discrete-time ON-OFF sources. Renewal cycles are identified in regard to the state of input sources and the buffer state on each renewal circle is modelled as a K(shared buffer size)-state Markov chain. We also analyze the behavior of queue build-up at the shared buffer whose distribution together with the steady-state probabilities of the Markov chain leads to the exact cell loss probability. Our approach to obtaining the exact cell loss probability seems to be more efficient than most of other existing ones since our underlying Markov chain has less number of states.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.165-168
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• 2006

Exponential smoothing methods do not adapt well to unexpected changes in underlying process. Over the past few decades a number of adaptive smoothing models have been proposed which allow for the continuous adjustment of the smoothing constant value in order to provide a much earlier detection of unexpected changes. However, most of previous studies presented ad hoc procedure of adaptive forecasting without any theoretical background. In this paper, we propose a detection-adaptation procedure applied to simple and Holt's linear method. We derive level and slope change detection statistics based on Bayesian statistical theory and present distribution of the statistics by simulation method. The proposed procedure is compared with previous adaptive forecasting models using simulated data and economic time series data.

• Asian Journal of Business Environment
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• v.2 no.2
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• pp.5-11
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• 2012

Purpose - This research examined the relationship between business orientation and business goals and satisfaction of Korean-American business owners. Research design/data/methodology - Entrepreneurial Orientation (EO) and Small Business Orientation (SBO) were the theoretical constructs underlying this research. The responses from 200 Korean-American business owners who participated in the 2005 National Minority Business Owner Surveys were used for data analysis. Results - Noneconomic business goal was positively related to business owners' SBO tendency, and those with a SBO tendency had the higher business satisfaction than those with EO. Conclusions - The findings suggest that policy makers should develop business assistance programs that correspond with owners' business orientation.

• Journal of Korean Society of Transportation
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• v.8 no.1
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• pp.55-71
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• 1990

The behavioral mechanism underlying the traffic assignment model is a choice, or decision-making process of traveling paths between origins and destinations. The deterministic approach to traffic assignment assumes that travelers choose shortest path from their origin-destination pair. Although this assumption seems reasonable, it presumes that all travelers have perfect information regarding travel time, that they make consistently correct decision, and that they all behave in identical fashion. Stochastic user equilibrium assignment relaxes these presumptions by including a random component in traveler's perception of travel time. The objective of this study is to compare "A Model of Deterministic User Equilibrium Assignment" with "Models of Stochastic User Equilibrium Assignment" in the theoretical and practical aspects. Specifically, SUE models are developed to logit and probit based models according to discrete choice functions. The models were applied to sioux Falls net ork consisting of 24 zones, 24 nodes and 76 links. The distribution of perceived travel time was obtained by using the relationship between speed and traffic flow.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.73.2-73.2
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• 2014

We investigate the rotation measure (RM) of the nearby low luminosity AGN M87 by using archival polarimetric VLA data at 8, 15, 22 and 43 GHz. For the first time, the RM properties of its jet are resolved at at arc-second scales. The distribution of the RM appears to be a gaussian with a mean value of ~200rad/m2 and the power spectrum follows a power law with index -2.5. A simple Kolmogorov model assuming a random turbulent magnetic fields extrinsic to the jet appears not to be adequate to explain the observed RM power spectra. On the other hand, underlying RM gradients possibly connected with the jet could be a possible interpretation.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.41.1-41.1
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• 2017

We present weak-lensing analysis of the merging galaxy cluster Abell 115 at z=0.197 based on Subaru i and V band images. As merging clusters often show, Abell 115's merging signatures include radio relics, double X-ray peaks, and large offsets between the cluster member galaxies and the X-ray distributions. A weak-lensing study provides underlying dark matter distribution, the key information to determine the complex merging scenario of the cluster. In this work, we present 2D mass reconstruction of the cluster, which reveals two distinct mass peaks consistent with galaxy distributions. We measure the first weak-lensing mass of each subcluster. Our weak-lensing total mass estimate is a few factors lower than the published dynamical mass obtained from velocity dispersion. This large mass discrepancy may be attributed to a significant departure from dynamical equilibrium. We also re-analyze the archival chandra data and find that the result is consistent with weak-lensing mass.

• Journal of the Korean Statistical Society
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• v.6 no.1
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• pp.65-76
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• 1977

The relative importance of single-shot kill probabilities, rates of fire, weapon allocation strategies, and the size of initial force in warfare between two force with heterogeneous multiple weapon systems are considered by examining their effect on a natural measure of effectiveness, the expected number of survivors. Attrition equations are derived via stochastic formulation to represent the mean course of battle having an underlying probability distribution. It is assumed that each side uses indirect area fires. Level of intelligence activities are reflected in the availability of spontaneous information on the current enemy status. Depending on the availability of the information on the current enemy status, each participatory unit may follow 1) a prescribed attack pattern (fraction of the available units assigned to various enemy targets) or 2) an adaptive attack pattern depending on the enemy status at that time. Conditions for possible stalemate are discussed.