• Management Science and Financial Engineering
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• v.10 no.1
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• pp.53-75
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• 2004

Most existing studies on time-dependent networks have been focused on finding a minimum delay path given a departure time at the origin. There, however, frequently happens a situation where users can select any departure time in a certain time interval and want to spend as little time as possible on traveling the networks. In that case. the delay spent on traveling networks depends on not only paths but also the actual departure time at the origin. In this paper, we propose a new problem in time-dependent networks whose objective is to find an optimal departure time given possible departure time interval at the origin. From the optimal departure time, we can obtain a path with minimum delay among all paths for possible departure times at the origin. In addition, we present an algorithm for finding an optimal departure time by enumerating trees which remain shortest path tree for a certain time interval.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.148-153
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• 1998

In order to control thermal deformation of machine origin of machine tools due to internal and external heat sources, the real-time compensation system has been developed. First, GMDH models were constructed to estimate thermal deformation of machine origin for a vertical machining center through the measurement of deformation data and temperature data of specific points on the machine tool. Thermocouples and gap sensors are used respectively for measurement. These models are nonlinear equations with high-order polynomials and implemented in a multilayered perceptron type network structure. Secondly, work origin shift method were developed by implementing digital I/O interface board between CNC controller and IBM-PC. The work origin shift method is to shift the work origin by the compensation amounts which is calculated by pre-established GMDH model. From the experimental result, thermal deformation of machine origin was reduced to below $\pm$5${\mu}{\textrm}{m}$.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.7
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• pp.1020-1027
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• 2015

The combined effect of tumbling marination methods (vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) and effective tumbling time (4, 6, 8, and 10 h) on the water status and protein properties of prepared pork chops was investigated. Results showed that regardless of tumbling time, CT method significantly decreased the muscle fiber diameter (MD) and significantly increased the total moisture content, product yield, salt soluble proteins (SSP) solubility, immobilized water component (p<0.05) compared with IT method. With the effective tumbling time increased from 4 h to 10 h, the fat content and the MD were significantly decreased (p<0.05), whereas the SSP solubility of prepared pork chops increased firstly and then decreased. Besides, an interactive effect between CT method and effective tumbling time was also observed for the chemical composition and proportion of immobilized water (p<0.05). These results demonstrated that CT method of 8 h was the most beneficial for improving the muscle structure and water distribution status, increasing the water-binding capacity and accelerating the marinade efficiency of pork chops; and thus, it should be chosen as the most optimal treatment method for the processing production of prepared pork chops.

• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.7-26
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• 1996

The estimation of real-time Origin-Destination(O-D) parameters, which gives travel demand between combinations of origin and destination points on a urban freeway network, from on-line surveillance traffic data is essential in developing an efficient ATMS strategy. On this need a real-time O-D parameter estimation model is formulated as a parameter adaptive filtering model based on the extended Kalman Filter. A Monte Carlo test have shown that the estimation of time-varying O-D parameter is possible using only traffic counts. Tests with field data produced the interesting finding that off-ramp volume predictions generated using a constant freeway O-D matrix was replaced by real-time estimates generated using the parameter adaptive filter.

• Journal of Environmental Health Sciences
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• v.37 no.4
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• pp.258-266
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• 2011

Objectives: The aim of this study is to examine the possible changes over the past ten years in the estimated daily dietary lead intake (Pb-D) stemming from the variation of daily intake amounts for each food group. The following factors were considered; 1. time trends in Pb-D as the estimated values, 2. the time trend in Pb-D by food groups 3. the most influential food groups for dietary Pb intake. Methods: Estimated Pb-D was drawn from food consumption according to food groups reported in the Korean National Health and Nutrition Survey and the lead contents of each food group as reported in 23 prior publications. Results: The estimated Pb-D in a 2009 survey was 40.8 ${\mu}g/day$, of which 22.5 ${\mu}g/day$ (55.1%) was of plant origin and 18.3 ${\mu}g/day$ (44.9%) was of animal origin. Meats and poultry, fish and shellfish among foods of animal origin and beverages of plant origin had the largest contribution in Pb-D among the food groups. Conclusion: Over past ten years, daily lead intakes have slightly increased among men. Otherwise, no clear variation is apparent among women.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.41
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• pp.267-292
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• 2009

It is a right time to improve the Korea Foreign Trade Act(KFTA) as a fundamental law on Rules of Origin(RoO) in the global trade circumstances which are summarized FTA and WTO. The KFTA's RoO constitutes the labelling system of the Country of Origin, the criterion of it, the issuing of certificate of origin and the punishing offender mainly around the importing goods. This study has focused on the problems of KFTA's RoO at the macro and practical level, and proposed the programs to improve the KFTA's RoO about importing, exporting and domestic production goods. KFTA need to create a purpose clause to protect consumers and industries also, and has to be located a general and top position in the RoO of Korea. In the concrete, the labelling system of the Country of Origin has to set limited in the point of minimum necessity view. The criterion of the Country of Origin also has to improve the wholly obtained criterion, the changing in tariff classification criterion, value added criterion and processing operation criterion to harmonize WTO Rules of Origin and FTA Rules of Origin. The punishment ceiling against offender has to raise to guarantee the effectiveness of RoO.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.31.1-31
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• 2001

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.138-143
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• 1993

A well-defined relative degree, which is one of the basic assumptions in adaptive control or nonlinear synthesis problems, is addressed. It is shown that this is essentially a necessary condition for asymptotic tracking in discrete-time nonlinear systems. To show this, tracking problems are defined, and a local linear input-output behavior of a discrete-time system is introduced in relation to a well-defined relative degree. It is then shown that if a plant is invertible and accessible from the origin and a compensator solves the local asymptotic tracking problem, then the plant necessarily has a well-defined relative degree at the origin.

• Journal of Information Technology Applications and Management
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• v.20 no.1
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• pp.87-106
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• 2013

This study is to explore the airline network patterns of Incheon and Narita International Airports using passenger flight departure and arrival data of the two airports. The so-called Origin-Destination data is collected from the airports' websites and some of the important data items are flight number, city of origin, destination city, departure/arrival time, number of flights, and delay time. A snowflake schema dimensional model is proposed and implemented. Tableau Public, a well-known visual analytic tool, is used to connect the dimensional model and played an important role in navigating the data space to find interesting and visual patterns among corresponding airports and airlines. For the efficiency of analyzing this spacious data mart, data visualization method was used. Four types of visualization method proposed by Yau was used; visualizing patterns over time, visualizing proportions, visualizing relationships, and visualizing spatial relationships. The strength of connectivity of each flight segments is calculated to evaluate the degree of globalization of Seoul and Tokyo. We anticipate that various patterns and new findings produced by the data mart would provide airline managers, airport authorities, and policy makers in the field of travel and transportation with insightful information.

• The Korean Journal of Applied Statistics
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• v.36 no.6
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• pp.561-571
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• 2023

Volatility of a time series is defined as the conditional variance on the past information. In particular, for financial time series, volatility is regarded as a time-varying measure of risk for the financial series. To capture the intrinsic asymmetry in the risk of financial series, various asymmetric volatility processes including threshold-ARCH (TARCH, for short) have been proposed in the literature (see, for instance, Choi et al., 2012). This paper proposes a volatility function featuring non-zero origin in which the origin of the volatility is shifted from the zero and therefore the resulting volatility function is certainly asymmetric around zero and achieves the minimum at a non-zero (rather than zero) point. To validate the proposed volatility function, we analyze the Korea stock prices index (KOSPI) time series during the Covid-19 pandemic period for which origin shift to the left of the zero in volatility is shown to be apparent using the minimum AIC as well as via parametric bootstrap verification.