• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.7-14
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• 2002

In order to achieve high precision machine tools, the research for performance enhancement of feed drive systems is required. Development of the high speed feed drive system has been a major issue for the past few decades in machine tool indestries. Because table levitation system decrease the table weight, an effect of reaction by weight is minimized and lost motion can be removed at maximum. In case fled system is designed with drive motor, ball screw and support bearing load capacity selection, an effect of decrease of the table weight exist. So, the table weight through an effect of decrease call it into the realization of cost down. Stick-slip friction has a great influence on the contouring accuracy of CNC machine tools. In this paper table levitation system has been developed for the stick-slip in a fled drive systems.

• International Commerce and Information Review
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• v.6 no.1
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• pp.3-23
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• 2004

Since the mid-1980's, strategic alliances are dominantly hailed as an effective growth and survival strategy in the era of international market and multinational corporation. There are a number of reasons for this phenomenon. there is an increasing globalization of markets in an ever-widening band of industries, together with the development of global technologies that makes production cycles shorten and the ever-increasing demand for investment resources and information to cope with the changing environment. The purpose of this study is to investigate the determinants of corporation information system in strategic alliance mode, and to analyze the main factors which are affecting the choice of strategic alliance mode by Korean firms. This study can also contribute theoretical and practical suggestive points in relation to strategic alliance operations. However, it also has limits as an exploratory study due to lacks of prior studies and proper methodologies and so on. Accordingly, the phenomenon of international strategic alliances call for further studies on casual relationships between main factors and variables in this field.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.35-45
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• 2000

this paper presents the concept of "mobile ATM', a proposal for third-generation (3G) mobile communication network infrastructure capable of supporting flexible evolution of radio technologies from today's cellular and data services towards future wireless multimedia services. Mobile ATM provides generic mobility management and QoS-based transport capabilities suitable for integration of multiple radio access technologies including cellular voice. wireless data, and future broadband wireless services. The architecture of a mobile ATM network is outlined in terms of the newly-defined "W-UNI" interface at the radio link and "M-UNI"and "M-UNI" interface which supports unified access for WATM and non-ATM mobile terminals through corresponding interworking functions (IWF) is explained. leading to an understanding of how different radio access technologies are supported by the same ATM-based core network infrastructure. Generic mechanisms for handoff and location management within the core mobile network are discussed. and related protocol extensions over the "W-UNI" and "M-UNI/NNI"interfaces are proposed. the issue of "crossover switch (COS)" selection in mobile ATM is considered, and a unified handoff signaling syntax which supports flexibility in COS selection is described. Typical signaling sequences for call connection and handoff using the proposed protocols are outlined. Experimental results form a proof-of-concept mobile ATM network prototype are presented in conclusion.

• Asia-Pacific Journal of Business
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• v.14 no.2
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• pp.33-49
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• 2023

Purpose - The purpose of this study is to examine the option selection and optimal trading of informed traders in KOSPI 200 options market based on the PIN (probability of informed trading) model of Easley et al.(2002). Design/methodology/approach - This study uses TAQ (trade and quote) data provided by Korean Exchanges (KRX) which contains all the bids and trades recorded during the continuous auction trading hours for the KOSPI 200 options between May 2019 and September 2020. Findings - First, there was no difference in the PIN between call and put options in the 2019 data, but the PIN of put options was slightly higher in 2020. Second, regardless of the type of option, the PIN was higher for in-the-money (ITM) options, and the PIN of out-of-the-money (OTM) options was the same as or slightly higher than that of at-the-money (ATM) options. Third, we found that the PIN decreases as trading liquidity increases, and fourth, the PIN increased sharply as the expiration date approached, especially for OTM options, while ITM and ATM options showed relatively weak effects. Fifth, for foreign and institutional investors, the periodicity of orders was observed in milliseconds, especially for foreign investors, where the periodicity of orders was clear and frequent in OTM options. The results suggest that the purpose of option trading varies depending on the moneyness from the perspective of the informed trader.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.268-275
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• 2005

Early predictions of crop yields call provide information to producers to take advantages of opportunities into market places, to assess national food security, and to provide early food shortage warning. The objectives of this study were to identify the most useful parameters for estimating yields and to compare two model selection methods for finding the 'best' model developed by multiple linear regression. This research was conducted in two 65ha corn/soybean rotation fields located in east central South Dakota. Data used to develop models were small temporal variability information (STVI: elevation, apparent electrical conductivity $(EC_a)$, slope), large temporal variability information (LTVI : inorganic N, Olsen P, soil moisture), and remote sensing information (green, red, and NIR bands and normalized difference vegetation index (NDVI), green normalized difference vegetation index (GDVI)). Second order Akaike's Information Criterion (AICc) and Stepwise multiple regression were used to develop the best-fitting equations in each system (information groups). The models with $\Delta_i\leq2$ were selected and 22 and 37 models were selected at Moody and Brookings, respectively. Based on the results, the most useful variables to estimate corn yield were different in each field. Elevation and $EC_a$ were consistently the most useful variables in both fields and most of the systems. Model selection was different in each field. Different number of variables were selected in different fields. These results might be contributed to different landscapes and management histories of the study fields. The most common variables selected by AICc and Stepwise were different. In validation, Stepwise was slightly better than AICc at Moody and at Brookings AICc was slightly better than Stepwise. Results suggest that the Alec approach can be used to identify the most useful information and select the 'best' yield models for production fields.

• Journal of the Korean Home Economics Association
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• v.45 no.6
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• pp.21-33
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• 2007

In present study, using longitudinal data of 161 families from Durham Child and Development Study, we examine the characteristics of infant child care chosen by families of different income levels and ethnicity in the U.S. Time-related changes in child care selection for the first year of the child's life were also investigated. Infants from high-income families were more likely to be cared for by someone other than the mother, compared to infant from lower-income families. African-American families were more likely to use non-maternal care for their infant compared to European-American families. Although the effects of income on type of care were not significant, descriptively, more low-income families used relative care while high-income families used more formal arrangements such as daycare center. Infants from low-income families began care earlier and low-income families paid less for care than other families. The findings call for attention to the importance of child care policy for low-income families as well as further research examining the function of cultural differences in selection of infant child care.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1055-1063
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• 2002

In this paper, we have studied path selection problem using multiple metric. Current Internet selects a path using only one metric. The path selected by one metric is a best-effort service that can satisfy one requirements. In order to satisfy a call with various Qualify-of-Service(QoS) requirements, the path must satisfy multiple constraints. In many cases, path selection is NP-complete. The proposed algorithm is widest-least cost routing algorithm that selects a path based on cost metric which is basically a delay metric influenced by the network status. The proposed algorithm is a multiple metric path selection algorithm that has traffic distribution ability to select shortest path when network load is light and move traffic to other alternate path when the link load is high. We have compared the results with other routing algorithms.

• Hwankyungkyoyuk
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• v.13 no.2
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• pp.38-50
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• 2000

We are evidently Home Economicus, egoistic rational utility maximiger, and all the capitalism economic situation make us adapt to such life, and recognize that it is rational to act like that. This can be demonstrated in Prisoner′s Dilemma(PD) which always select the non-cooperative choice for free rider in rational selection process of public goods. This paper notice the "what is problem\ulcorner"The problem is not in free rider itself but in free rider egoism. The practical behavior of free rider egoism can be explained by way of Prisoner′s Dilemma. In PD situation, the prisoner makes a rational choice, non-cooperative alternative, but he doesn′arrive at preto-optimality. It is dilemma. Why can′t he arrive \ulcorner Because he is isolated from other prisoner. So we call it prisoner′s dilemma. The PD situation can be compared with our real economic life, which, we think, have kept by rational choice of the public goods. We actually have made our life as an individual one although we organized communities of capitalism. Of course, we know each others as members of same society, but each individual being can′t secure the belief, which has composed basis of community. So, it is very similar and common between PD situation and our real economic life in the production of public goods. We conclude that this non-cooperative process of PD situation can be utilized as instrument of EE. So this non-cooperative process can show us the effectiveness of EE as follows. \circled1 Game situation life PD can be used as good instrument for explaining the rational selection dilemma(error) to Homo-Economicus, the rational agent, with the optimal and rational language. \circled2 We can show that the selection result is dilemma, not arrive pareto - optimality. \circled3 The dilemma can be resolved with accomplishing the good communal life based on the belief, not on the isolation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1268-1278
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• 1999

In this paper, we propose an analytic method for dimensioning of traffic descriptors at the leaky bucket-based UPC for VBR MPEG video traffic on ATM networks. We analytically derive cell violation probabilities at the UPC by using the proposed scene-based video traffic model, and then we show that it is possible to select sets of traffic descriptors that have the same required violation probability. For two example video traces, numerical results show that our proposed traffic descriptors dimensioning method can approximate well the simulation-based traffic control results of the real video traces. When the effective bandwidth allocation method of an ON/OFF model is used for the call admission control in the networks, we present an efficient traffic descriptor selection method by studying the allocated bandwidth to each possible traffic descriptor set.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.195-200
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• 2012

We present a new algorithm which can improve the tracking performance of the double-talk robust algorithm. A detection method of the echo path change and a modification method for the update equation of the conventional adaptive filter are proposed. A duration of the high error signal to scale parameter ratio varies according to the call status and this property is used to detect the echo path change. The proposed update equation of the adaptive filter improves the tracking performance by prohibiting wrong selection of the error signal. Simulations using real speech signals and echo paths of the ITU-T G.168 standard confirmed that as compared to the conventional algorithm, the proposed algorithm improved the tracking performance by more than 4 dB.