• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.135-144
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• 1998

High speed machining is a key issue in die and mold manufacturing recently. Even though this technology has great potential of high productivity. tool wear accelerated by high cutting speed to the hardened materials is other barrier. In this research, we attempted to reduce tool wear by considering tool inclination angle between tool and workpiece. The boundary lines describing machined sculptured surfaces were represented by both of cutting envelop condition and the geometric relationship of successive tool paths. Chip cross section, and cutting length could be obtained from the calculated cutting edge and the rotational engagement angle. From the simulation results, machining inclination angle of tool of $15^\circ$ was good enough from the point of tool wear and cutting force, and this value was verified through the cutting experiment of high speed ball end milling.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.69-76
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• 2016

In this paper, we investigate the system performance of a cooperative relaying system of Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), which is considered promising application in fifth generation (5G) cellular networks. Previous studies have focused on the selected relays, however we include the maxmin relay selection and derive analytical outage probability of opportunistic incremental relaying systems. For the realistic mobile environment, the distributions of relays are modeled as a homogeneous Poisson point process (PPP). And maximal ratio combining (MRC) is adapted to improve the system performance at the destination node. Analytical results demonstrate the outage probability improves with the near/far user power ratio, and the cooperative relaying scheme can achieve low outage probability in comparison to the no relaying scheme. It is also conformed that the increase of the intensity of PPP cause higher gains of the spacial diversity and hence the performance improves.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.59-66
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• 2015

In this paper, we propose a method of improving the light-load efficiency of DC-DC buck converter using 4bit SAR-ADC (Successive Approximation ADC) for a LDO or a power transistor size selection technique. The proposed circuit selects power transistor sizes depending on load current so that improves the light-load efficiency of the DC-DC buck converter. For this, we select the power transistor size with a cross point of the switching loss and the conduction loss. Also, when the IC operates in standby mode or sleep mode, a LDO mode is selected for improving the efficiency. The proposed circuit selects power transistor sizes(X1, X2, X4, X8) with 4 bits and its efficiency is higher about the maximum of 25% at the light-load than that of a single transistor size. Input voltage and output voltage are 5V and 3.3V for maximum load currents of 500mA.

• Korean journal of applied entomology
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• v.31 no.1
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• pp.1-6
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• 1992

These studies were carried out to compare toxicological test methods of two spotted spider mite, Tetranychus urticae Koch,; and to investigate relationship between in vivo resistant level of highly acaricide-selected population, and in vitro insensitivity of the AChE in the same population to carbophenothion and ethion. The slide dip method (CV = 8.7%) was of more accuracy and suitability than that of the leaf dip method(CV=12.2%) and leaf disc method (CV= 13.6 %) in determination of the resistant levels of twospotted spider mite to acaricides. The slide dip method also had the advantages of simple treatment with different populations on a slide at the same time, standardization of post-treatement conditions and living plants exclud¬ed from the test. Even though the topical application method(CV =8.1 %) showed high accuracy, it had the demerits of the much time consuming, need of expensive equipment and difficulty of test manipulation. For a limited time, the 22nd successive carbophenothion-selected population of two-spotted spider mite showed 156- and 128-fold resistant levels to carbophenothion and ethion(both alPs), respectively. However, the 24th successive ethion-selected population revealed 64.1- and 65-fold resistant levels to ethion and carbophenothion, respectively. In the inhibition of AChE activity, the carbophenothion-selected population showed 3.3- and 2.7-fold insensitivity in AChE activity to carbophenothion and ethion, respectively. Likewise, the ethion -selected population exhibited 3- and 2.6-fold insensitivity in AChE activity to carbophenothion and ethion, respectively, as compared with that of susceptible population. As a result, a good relation was recognized between in vivo resistance to organophosphorous acaricides and in vitro insensitivity of the AChE to corresponding inhibitors.

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.6-20
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• 2023

The World Heritage Subcommittee of the Cultural Heritage Administration which examine The World Heritage Subcommittee of the Cultural Heritage Administration which The World Heri The World Heritage Subcommittee of the Cultural Heritage Administration which examined the Placenta Chamber of King Sejong's Princes applied for the world heritage priority list in 2020 recommended expanding it to the royal placenta chambers of Joseon distributed nationwide for successive registration instead of registering the Seongju placenta chamber only. On account of that, the issue of selecting items has become one of the important topics to be discussed in the registration of world heritages. Accordingly, this researcher investigated the subjects of successive registration based on such conditions as excellent universal value, heritage protection and management, authenticity, and completeness among the real estate cultural properties demanded by the UNESCO World Heritage Committee. First, 22 placenta chambers, the real estate cultural properties designated as cultural properties and protected and managed by the state and local governments, are subject to it. Second, it seems that placenta chambers that can be restored through research and historical investigation and become designated as cultural properties can additionally be added. Third, items such as the Seosamneung Royal Tombs built by Lee Wang-jik in the Japanese colonial era or Seongjong Placenta Chamber relocated as an example to realize the completeness of Joseon's Royal Placenta Chambers can be included as well. Meanwhile, many of the items designated as cultural properties are not in the original location, and they can be divided into those that were relocated for the intentions of the Japanese Empire and those that were not. Therefore, the researcher insists that it is necessary to select and add items with which we can understand the historicity in the relocation of placenta chambers during the Japanese colonial era and also to quickly designate those that have not been designated as cultural properties yet. Therefore, regardless of designation as cultural heritage, local governments must promote both restoration and designation and strive to include them in the list of successive registration of world heritages grounded on thorough historical investigation. Moreover, to add them to the list of successive registration of world heritages, the Cultural Heritage Administration and local governments should promote continuous research and genuine restoration of individual placenta chambers.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.19-24
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• 2007

Covariance components and genetic parameters of weekly live body weight from hatching to six weeks of age and age of sexual maturation were estimated in a laying type Japanese quail line. The univariate and bivariate animal model analysis included hatching group and sex as fixed effects. Each trait was analysed with animal as random effect to fit the additive direct effect. Additional random effects incorporated in the models were changed according to the trait examined. The best model for a trait was chosen based on a likelihood ratio test, comparing the models with and without maternal additive genetic and maternal permanent environmental effects. Heritability estimates of live-weight at hatch and one to six weeks of age with their standard errors were 0.22${\pm}$0.088, 0.39${\pm}$0.099, 0.31${\pm}$0.086, 0.38${\pm}$0.056, 0.46${\pm}$0.055, 0.50${\pm}$0.059, and 0.56${\pm}$0.062, respectively. Direct heritability value of age of sexual maturation was moderate (0.24${\pm}$0.055). The variances due to permanent environmental effect of dam after one week of age and maternal genetic effect after two weeks of age were not important sources of variation. The correlations between direct and maternal genetic effects were negative and ranged from high to moderate values (-0.21 to -0.83). Among the weekly live weights, genetic correlations were generally high between not only successive but also early and late weightings. It suggests that selection for final weight may be based on early weight records. Genetic correlations between age of sexual maturation and live weights were low, favourable but had high standard errors. These results indicate that selection for high weight will potentially result in lower age of sexual maturation only with accurate determination of breeding values.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.768-775
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• 2011

Since error compensation schemes guaranteeing high reliability are required in wireless communication systems for the transmission of the large amount of data, as an efficient error compensation scheme the turbo HARQ scheme combining automatic repeat request and turbo coding has been studied in many places in the literature. In the case of conventional turbo HARQ schemes, the transmitter recognizing NAK signals repetitively sends the whole unit packet to the receiver although the received packet can be partially correctable. Through two successive processes, selection of uncorrectable error data and retransmission of only the relevant parts of the information data, transmission efficiency can be improved. In this paper, we present an error data selection criterion for retransmission using the sign transitions of A Posteriori values and propose a tubo HARQ scheme based on the partial retransmission technique. Through a computer simulation, we show and analyze the performance of the proposed scheme with transmission efficiency.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.347-352
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• 2004

This thesis deals with a task scheduling on a message-passing system. Scheduling and allocation are very important issues since the inappropriate scheduling of tasks cannot exploit the true potential of the system and it can offset the grain from parallelization. It is difficult to apply previous schemes to message-passing system, because previous schemes assume the shared memory system. This thesis proposes an modified priority function and processor selection technique that consider the problems caused by the difference between previous models and message-passing environments. The priority function includes the cumulative communication cost which causes task execution to be delayed. The processor selection technique avoids the situation that a child task is assigned to the same Processor allocated to its parent task that has other unscheduled child tasks. We showed by some simulations that our modified features of task scheduling algorithm can make the better scheduling results than the previous algorithms.

• International Journal of CAD/CAM
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• v.4 no.1
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• pp.33-45
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• 2004

In this work, a rational procedure has been formulated for the selection of points approximating slice contours cut in LOM (Laminated Object manufacturing) with first order approximation. It is suggested that the number of points representing a slice contour can be 'minimised' or 'optmised' by equating the horizontal chordal deviation (HCD) to the user-defined surface form tolerance. It has been shown that such optimization leads to substantial reduction in slice height calculations and NC codes file size for cutting out the slices. Due to optimization, the number of contour points varies from layer to layer, so that points on successive layer contours have to be matched by four sided ruled surface patches and triangular patches. The technological problems associated with the cutting out of triangular patches have been addressed. A robust algorithm has been developed for the determination of slice height for optimum and arbitrary numbers of contour points with different strategies for error calculations. It has been shown that optimisation may even lead to detection and appropriate representation of elusive surface features. An index of optimisation has been defined and calculations of the same have been tabulated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1837-1860
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• 2020

We propose a general framework for studying resource allocation problem and the tradeoff between spectral efficiency (SE) and energy efficiency (EE) for downlink traffic in power domain-non-orthogonal multiple access (PD-NOMA) and device to device (D2D) based heterogeneous cloud radio access networks (H-CRANs) under imperfect channel state information (CSI). The aim is jointly optimize radio remote head (RRH) selection, spectrum allocation and power control, which is formulated as a multi-objective optimization (MOO) problem that can be solved with weighted Tchebycheff method. We propose a low-complexity algorithm to solve user association, spectrum allocation and power coordination separately. We first compute the CSI for RRHs. Then we study allocating the cell users (CUs) and D2D groups to different subchannels by constructing a bipartite graph and Hungrarian algorithm. To solve the power control and EE-SE tradeoff problems, we decompose the target function into two subproblems. Then, we utilize successive convex program approach to lower the computational complexity. Moreover, we use Lagrangian method and KKT conditions to find the global optimum with low complexity, and get a fast convergence by subgradient method. Numerical simulation results demonstrate that by using PD-NOMA technique and H-CRAN with D2D communications, the system gets good EE-SE tradeoff performance.