• Journal of Communications and Networks
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• v.18 no.3
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• pp.333-339
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• 2016

A multi-stage turbo equalization scheme based on the bit-level combining (BLC) is proposed for multiple-input multiple-output (MIMO) systems with hybrid automatic repeat request (HARQ). In the proposed multi-stage turbo equalization scheme, the minimum mean-square-error equalizer at each iteration calculates the extrinsic log-likelihood ratios for the transmitted bits in a subpacket and the subpackets are sequentially replaced at each iteration according to the HARQ rounds of received subpackets. Therefore, a number of iterations are executed for different subpackets received at several HARQ rounds, and the transmitted bits received at the previous HARQ rounds as well as the current HARQ round can be estimated from the combined information up to the current HARQ round. In addition, the proposed multi-stage turbo equalization scheme has the same computational complexity as the conventional bit-level combining based turbo equalization scheme. Simulation results show that the proposed multi-stage turbo equalization scheme outperforms the conventional BLC based turbo equalization scheme for MIMO systems with HARQ.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.187-193
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• 2021

In order to solve the problem of false terrains caused by environmental interferences and tunneling effect in the conventional multi-beam seafloor terrain detection, this paper proposed a seafloor topography detection method based on fast two-dimensional (2D) Censored Mean Level Detector-statistics Constant False Alarm Rate (CMLD-CFAR) method. The proposed method uses s cross-sliding window. The target occlusion phenomenon that occurs in multi-target environments can be eliminated by censoring some of the large cells of the reference cells, while the remaining reference cells are used to calculate the local threshold. The conventional 2D CMLD-CFAR methods need to estimate the background clutter power level for every pixel, thus increasing the computational burden significantly. In order to overcome this limitation, the proposed method uses a fast algorithm to select the Regions of Interest (ROI) based on a global threshold, while the rest pixels are distinguished as clutter directly. The proposed method is verified by experiments with real multi-beam data. The results show that the proposed method can effectively solve the problem of false terrain in a multi-beam terrain survey and achieve a high detection accuracy.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.745-746
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• 2006

This lecture introduces new press, adapter and control concepts to size multi-level sintered components. The essential thing here is that the advantages of the multi-plate technology have been applied to the sizing adapter concept. Thus, the new concept meets the demands for a modern P/M manufacture and offers sufficient potential to size any future, complex sintered components such as synchronizer hubs, oil pump wheels and VCT parts with highest precision. Furthermore, it outlines a new flexible concept for the parts transfer, including feeding, orientation and lubrication while responding to the high demands on process stability and short change-over times.

• The Korean Journal of Applied Statistics
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• v.14 no.1
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• pp.81-90
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• 2001

One of the Repeated survey which estimates variability of population, we can be consider rotation sample survey. There are two kinds of rotation sample survey - onelevel rotation sample survey and multi-level rotation sample survey. In rotation sample survey, Composite estimator is used to measure level or level change of the population. This study suggests Generalized Composite estimator as considering intraclass correlation in multi-level rotation sample survey, and optimal weight minimizing variance of estimator. Numerical example shows efficiency of Generalized Composite estimator as considering intraclass correlation according to the sample unit and change degree of intraclass correlation in the rotation group.

• Explosives and Blasting
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• v.34 no.4
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• pp.35-39
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• 2016

Influence of rock fall from upper-level roofs to lower-level roofs and pillars at a multi layered room and pillar mine was numerically simulated by using AUTODYN. The analysis results showed that the maximum displacement and stress in the roof of the lower-level stope are respectively 0.001 mm and 36 MPa, and those in the pillars of the lower-level stope are 0.0003 mm and 3 MPa. The maximum damage levels in the roof and pillar of the lower-level stope were evaluated to be about 0.03 when a half of the roof rock of the upper-level stope was assumed to be fallen to the floor.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.429-441
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• 2011

In large-scale problem, a huge size of computational resources is needed for a reliable solution which represents the detailed description of dynamic behavior. Recently, eigenvalue reduction schemes have been considered as important technique to resolve computational resource problems. In addition, the efforts to advance an efficiency of reduction scheme leads to the development of the multi-level system condensation (MLSC) which is initially based on the two-level condensation scheme (TLCS). This scheme was proposed for approximating the lower eigenmodes which represent the global behavior of the structures through the element-level energy estimation. The MLSC combines the multi-level sub-structuring scheme with the previous TLCS for enhancement of efficiency which is related to computer memory and computing time. The present study focuses on the implementation of the MLSC on the direct time response analysis and the frequency response analysis of structural dynamic problems. For the transient time response analysis, the MLSC is combined with the Newmark's time integration scheme. Numerical examples demonstrate the efficiency of the proposed method.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.375-384
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• 2005

General purpose operating systems are Increasingly being used for serving time-sensitive applications. These applications require soft real-time characteristics from the kernel and from other system-level services. In this paper, we explore various operating systems techniques needed to support time-sensitive applications and describe the design of MUSMA(Multi-level Scheduler for Multimedia Application). MUSMA is a framework that combination of user-level top scheduler and kernel-level bottom scheduler. We develope MUSMA in linux environment and it's performance is evaluated. Experiment result shows that it is possible to satisfy the constraints of multimedia in a general purpose operating system without significantly compromising the performance of non-realtime applications.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.05a
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• pp.429-434
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• 2002

For companies assembling end products from sub assemblies or components, MRP (Material Requirement Planning) logic is frequently used to synchronize and pace the production activities for the required parts. However, in MRP, the planning of operational-level activities is left to short term scheduling. So, we need a good scheduling algorithm to generate feasible schedules taking into account shop floor characteristics and multi-level job structures used in MRP. In this paper, we present a GA (Genetic Algorithm) solution for this complex scheduling problem based on a new gene to reflect the machine assignment, operation sequences and the levels of the operations relative to final operation. The relative operation level is the control parameter that paces the completion timing of the components belonging to the same branch in the multi-level job hierarchy. In order to revise the fixed relative level which solutions are confined to, we apply large step transition in the first step and GA in the second step. We compare the genetic algorithm and 2-phase optimization with several dispatching rules in terms of tardiness for about forty modified standard job-shop problem instances.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.704-715
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• 2016

In this paper, we explore a low-complex bandwidth allocation (BA) scheme with multi-level service guarantees in VLC-OFDM systems. Effective capacity theory, which evaluates wireless channel capacity from a novel view, is utilized to model the system capacity under delay QoS constraints of the link layer. Since intensity modulation of light is used in the system, problems caused by frequency selectivity can be neglected. Then, the BA problem can be formulated as an integer programming problem and it is further relaxed and transformed into a concave one. Lagrangian formulation is used to reformulate the concave problem. Considering the inefficiency of traditional gradient-based schemes and the demand for distributed implementation in local area networks, we localize the global parameters and propose a quasi-distributed quadratic allocation algorithm to provide two-level service guarantees, the first level is QoS oriented, and the second level is QoE oriented. Simulations have shown the efficient performance of the proposed algorithm. The users with more stringent QoS requirements require more subcarriers to guarantee their statistical delay QoS requirements. We also analyze the effect of subcarrier granularity on the aggregate effective capacity via simulations.

• Journal of Families and Better Life
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• v.28 no.4
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• pp.89-101
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• 2010

Increased multi-cultural families over the recent decade have led to more studies on the current situations and problems they face. Fathers in multi-cultural families are supporters who can help their migrant wives adapt their new surroundings; however, it is difficult to find studies on them as their roles as fathers in multi-cultural families have been overlooked. This study develops educational programs for fathers in multi-cultural families and analyzes the effect of the educational programs. The educational program development for fathers in multi-cultural families was based on consideration of related articles, studies, and reports. The effect analysis for the educational program for fathers in multi-cultural families was performed through the investigation of 'self-esteem' and 'parent self-confidence' about educated fathers in multi-cultural families. The educational program for fathers in multi-cultural families was composed of 5 themes which can improve their self-esteem, understand the father's role and function, learn the skills of playing and conversation with their children and express the father's thoughts for his own family using positive methods. We educated 12 fathers in multi-cultural families through the development of the program over 5 weeks to verify the effect of educational programs for fathers in multi-cultural families. The results showed the following : The level of father's self-esteem in multi-cultural family increased 124% and the level of parent self-confidence increased 141%. In conclusion, the educational effect for fathers in multi-cultural family exists and their desire for a successful multi-cultural family increased through the educational programs.