• Journal of the Korean Mathematical Society
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• v.52 no.6
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• pp.1123-1137
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• 2015

We study colorings of regular trees using subball complexity b(n), which is the number of colored n-balls up to color-preserving isomorphisms. We show that for any k-regular tree, for k > 1, there are colorings of intermediate complexity. We then construct colorings of linear complexity b(n) = 2n + 2. We also construct colorings induced from sequences of linear subword complexity which has exponential subball complexity.

• Journal of the Korean Mathematical Society
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• v.48 no.2
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• pp.383-395
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• 2011

We present two constructions of Toeplitz sequences with an intermediate complexity function by using the generalized Oxtoby sequence. In the first one, we use the blocks from the infinite sequence, which has entropy dimension $\frac{1}{2}$. The second construction provides the Toeplitz sequences which have various entropy dimensions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.17-24
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• 2006

Hydrodynamic ram of aircraft fuel tanks is one of main ballistic battle damages of an aircraft and has great importance to airframe survivability design. Basic concept, physics and research history of hydrodynamic ram are investigated. The penetration and internal detonation of a simple fuel tank and ICW(Intermediate Complexity Wing) are analyzed by computational method. Structural rupture and fluid burst are analytically realized using general coupling and coupling surface interaction. The results such as fluid pressure, tank stress and displacement are shown and future research chances are suggested based on the study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9C
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• pp.914-920
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• 2006

In this paper, we introduce a new partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. In the proposed scheme, $2^n$-point inverse fast Fourier transform (IFFT) is divided into two parts. An input symbol sequence is partially transformed using the first l stages of IFFT into an intermediate signal sequence and the intermediate signal sequence is partitioned into a number of intermediate signal subsequences. Then, the remaining n - l stages of IFFT are applied to each of the intermediate signal subsequences and the resulting signal subsequences are summed after being multiplied by each member of a set of W rotating vectors to yield W distinct OFDM signal sequences. The one with the lowest peak to average power ratio (PAPR) among these OFDM signal sequences is selected for transmission. The new PTS OFDM scheme reduces the computational complexity while it shows almost the same performance of PAPR reduction as that of the conventional PTS OFDM scheme.

• English Language & Literature Teaching
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• v.17 no.4
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• pp.207-227
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• 2011

This paper investigates how two different modes of feedback (selective vs. comprehensive) affect selected students' writing development in terms of three different types of measurement (accuracy, fluency, and complexity). 139 university students participated in the study, and 278 writing samples were analyzed. The results of the study indicate that participants who received selective feedback wrote more accurately and fluently than their counterparts. However, in terms of complexity, both selective and comprehensive groups showed no sign of improvement in semester-based investigations. The results of this study support Skehan's (2009) theory of trade-off effects, suggesting that 'natural' tension exists between accuracy and complexity when resources are limited. Moreover, this finding contrasts with the theory of Cognition Hypothesis, which proposes that task complexity will be associated with increases in complexity and accuracy. In the study, selected participants (N=21) strongly nominated their error sources as unfamiliarity toward using key words, usage, transition, and sentence types. This study not only contributes to the accumulation of our current knowledge in the related area of theory, but offers educational implications for those who are dealing with intermediate-level students when deciding what particular teaching content should constitute a priority within a limited instructional period.

• ETRI Journal
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• v.32 no.2
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• pp.273-280
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• 2010

The overall channel capacity of a multihop wireless path drops progressively over each hop due to the cascading effect of noise and interference. Hence, without optimal rate adaptation, the video quality is expected to degrade significantly at any client located at a far-edge of an ad-hoc network. To overcome this limitation, decoding and forwarding (DF), which fully decodes codewords at each intermediate node, can be employed to provide the best video quality. However, complexity and memory usage for DF are significantly high. Consequently, we propose syndrome-based partial decoding (SPD). In the SPD framework an intermediate node partially decodes a codeword and relays the packet along with its syndromes if the packet is corrupted. We demonstrate the efficacy of the proposed scheme by simulations using actual 802.11b wireless traces. The trace-driven simulations show that the proposed SPD framework, which reduces the overall processing requirements of intermediate nodes, provides reasonably high goodput when compared to simple forwarding and less complexity and memory requirements when compared to DF.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.412-425
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• 2003

According to the results of related studies, one of the typical factors related to procedure related human errors is the complexity of procedures. This means that comparing the change of the operators' behavior with respect to the complexity of procedures may be meaningful in clarifying the reasons for the operators' non-compliance behavior. In this study, to obtain data related to the operators' non-compliance behavior, emergency training records were collected using a full scope simulator. And three types of the operators' behavior (such as strict adherence, skipping redundant actions and modifying action sequences) observed from the collected emergency training records were compared with the complexity of the procedural steps. As the results, two remarkable relationships are obtained. They are: 1) the operators seem to frequently adopt non-compliance behavior to conduct the procedural steps that have an intermediate procedural complexity, 2) the operators seems to accommodate their non-compliance behavior to the complexity of the procedural steps. Therefore, it is expected that these relationships can be used as meaningful clues not only to scrutinize the reason for non-compliance behavior but also to suggest appropriate remedies for the reduction of non-compliance behavior that can result in procedure related human error.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1015-1018
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• 2003

As increasing the size and complexity of hard-ware and software system, more efficient design methodology has been developed. Especially design-reuse technique enables fast system development via integrating existing hardware and software. For this technique available hardware/software should be prepared as component-based parts, adaptable to various systems. This paper introduces a component-based VHDL analyzer allowing to be embedded in other applications, such as simulator, synthesis tool, or smart editor. VHDL analyzer parses VHDL description input, and performs lexical, syntactic, semantic checking, and finally generates intermediate-form data as the result. VHDL has full-features of object-oriented language such as data abstraction, inheritance, and polymorphism. To support these features special analysis algorithm and intermediate form is required. This paper summarizes practical issues on implementing high-performance/quality VHDL analyzer and provides its solution that is based on the intensive experience of VHDL analyzer development.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.473-481
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• 2015

In this study, we propose a clustering algorithm to enhance the performance of wireless sensor and actuator networks (WSANs). In each cluster, a multi-level hierarchical structure can be applied to reduce energy consumption. In addition to the cluster head, some nodes can be selected as intermediate nodes (INs). Each IN manages a subcluster that includes its neighbors. INs aggregate data from members in its subcluster, then send them to the cluster head. The selection of intermediate nodes aiming to optimize energy consumption can be considered high computational complexity mixed-integer linear programming. Therefore, a heuristic lowest energy path searching algorithm is proposed to reduce computational time. Moreover, a channel assignment scheme for subclusters is proposed to minimize interference between neighboring subclusters, thereby increasing aggregated throughput. Simulation results confirm that the proposed scheme can prolong network lifetime in WSANs.

• The Journal of the Korea Contents Association
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• v.16 no.12
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• pp.373-382
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• 2016

Carbon dioxide Capture and Storage/Sequestration (CCS) technology has attracted attention as an ideal method for most carbon dioxide reduction needs. When the collected carbon dioxide is transported to storage via pipelines, the direct transport is made if the storage is close, otherwise it can also be transported via an intermediate storage hub. Determining the number and the location of the intermediate storage hubs is an important problem. A decision-making algorithm using a mathematical model for solving the problem requires considerably more variables and constraints to describe the multi-objective decision, but the computational complexity of the problem increases and it also does not guarantee the optimality. This research proposes an algorithm to determine the location and the number of the intermediate storage hub and develop a simulator for the connection network of the carbon dioxide emission site. The simulator also provides the course of transportation of the carbon dioxide. As a case study, this model is applied to Korea.