• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.386-387
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• 2012

Environmental management and design based on the coastal characteristics are highly recommended because it is highly required to provide pleasant and safe environment in Marina. The coastal environment have a large spatial and temporal variations. Thus, the systematic survey monitoring should be planned and the practical management level should be determined based on the practically achievable level and minimum requirement not a standardized single criteria. It aimed to suggest the basic essential steps and related techniques needed in each step.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1489-1496
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• 2010

A feed forward differential architecture of analog PRML decoder is investigated to implement on analog parallel processing circuits. The conventional PRML decoder performs the trellis processing with the implementation of single stage in digital and its repeated use. The analog parallel processing-based PRML comes from the idea that the decoding of PRML is done mainly with the information of the first several number of stages. Shortening the trellis processing stages but implementing it with analog parallel circuits, several benefits including higher speed, no memory requirement and no A/D converter requirement are obtained. Most of the conventional analog parallel processing-based PRML decoders are differential architecture with the feedback of the previous decoded data. The architecture used in this paper is without feedback, where error metric accumulation is allowed to start from all the states of the decoding stage, which enables to be decoded without feedback. The circuit of the proposed architecture is simpler than that of the conventional analog parallel processing structure with the similar decoding performance. Characteristics of the feed forward differential architecture are investigated through various simulation studies.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1043-1052
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• 1993

Field experiments were conducted to determine the optimum combination of performance parameters of a single-shank, tractor-mounted oscillating subsoiler. Tests were conducted at frequencies of oscillation of 3.7 , 5.67, 7.58, 9.48 and 11.456Hz ; amplitudes of 18, 21, 23.5, 34 and 36.5 mm ; and forward speeds of 1.84, 2.19 and 3.42 kmph at moisture content close to the plastic limit of the soil. It was observed that there was a reduction in average draft but an a increase in average total power requirement for oscillating than non-oscillating subsoiling. The draft and power ratios were significantly affected by the forward speed, frequency and amplitude. Their combined interaction expressed in terms of the velocity ratio parameter( the ratio of peak tool velocity and forward speed) however has the strongest influence. At the same velocity ratio, the draft reduction and power increase were less at higher amplitude of oscillation . As the oscillating frequency is increased toward the soil resonance the draft requirement becomes less. For the field conditions tested. the optimum operation was obtained at an amplitude of 36.5mm, frequency of 9.48Hz and speed of 2.19 kmph with a draft ratio of 0.33 and a power ratio of only 1.24.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.744-750
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• 2009

In this paper, the unified Markov modeling of hardware and software for AVTMR(AlI Voting Triple Modular Redundancy) system is proposed and the dependability is analyzed. In hardware case, a failure rate is fixed to no time varying parameter. But, in software case, failure rate is applied with time varying parameter. Especially, the dependability(Reliability, Availability, Maintainability, Safety) of software is analyzed with G-O/NHPP for Markov modeling. The dependability of single and AVTMR system is analyzed and simulated with a unified Markov modeling method, and the characteristic of each system is compared accroding to failure rate. This kind of fault tolerat system can be applied to an airplane and life critical system to meet the requirement for a specific requirement.

• Steel and Composite Structures
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• v.20 no.2
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• pp.267-293
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• 2016

It is well known that, in order to accurately predict the behaviour of steel structures a requirement the definition of the mechanical behaviour of beam-to column joints is of primary importance. This goal can be achieved by means of the so-called component method, which, in order to obtain the whole behaviour of connections, provides to break up joints in basic components of deformability and resistance. One of the main joint components used to model bolted connections is the so-called equivalent T-stub in tension, which is normally used to predict the behaviour of bolted plates in bending starting from the behaviour of the single bolt rows. In past decades, significant research efforts have been devoted to the prediction of the behaviour of bolted T-stubs but, to date, no particular attention has been devoted to the characterization of their plastic deformation capacity. To this scope, the work presented in this paper, taking into account the existing technical literature, proposes a new theoretical model for predicting the whole behaviour up to failure of bolted T-stubs under monotonic loading conditions, including some complexities, such as the bolt/plate compatibility requirement and the bolt fracture, which are necessary to accurately evaluate the ultimate displacement. After presenting the advances of the proposed approach, a comparison between theoretical and experimental results is provided in order to verify its accuracy.

• Nuclear Engineering and Technology
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• v.39 no.1
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• pp.51-62
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• 2007

To efficiently design safety-critical systems such as nuclear power plants, with the requirement of high reliability, methodologies allowing for rigorous interactions between the synthesis and analysis processes have been proposed. This paper attempts to develop a reliability-centered design framework through an interactive process between Axiomatic Design (AD) and Fault Tree Analysis (FTA). Integrating AD and FTA into a single framework appears to be a viable solution, as they compliment each other with their unique advantages. AD provides a systematic synthesis tool while FTA is commonly used as a safety analysis tool. These methodologies build a design process that is less subjective, and they enable designers to develop insights that lead to solutions with improved reliability. Due to the nature of the two methodologies, the information involved in each process is complementary: a success tree versus a fault tree. Thus, at each step a system using AD is synthesized, and its reliability is then quantified using the FT derived from the AD synthesis process. The converted FT provides an opportunity to examine the completeness of the outcome from the synthesis process. This study presents an example of the design of a Containment Heat Removal System (CHRS). A case study illustrates the process of designing the CHRS with an interactive design framework focusing on the conversion of the AD process to FTA.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2589-2609
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• 2021

Segment routing (SR) is a highly implementable approach for traffic engineering (TE) with high flexibility, high scalability, and high stability, which can be established upon existing network infrastructure. Thus, when a network failure occurs, it can leverage the existing rerouting methods, such as rerouting based on Interior Gateway Protocol (IGP) and fast rerouting with loop-free alternates. To better exploit these features, we propose a high-performance and easy-to-deploy method SRUF (Segment Routing under Uncertain Failures). The method is inspired by the Value-at-Risk (VaR) theory in finance. Just as each investment risk is considered in financial investment, SRUF also considers each traffic distribution scheme's risk when forwarding traffic to achieve optimal traffic distribution. Specifically, SRUF takes into account that every link may fail and therefore has inherent robustness and high availability. Also, SRUF considers that a single link failure is a low-probability event; hence it can achieve high performance. We perform experiments on real topologies to validate the flexibility, high-availability, and load balancing of SRUF. The results show that when given an availability requirement, SRUF has greater load balancing performance under uncertain failures and that when given a demand requirement, SRUF can achieve higher availability.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.57-63
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• 2021

The launch vehicle (LV) separation detection interface of the satellite, which is designed to initiate the launch and early operation phase (LEOP) for S-band data transmission and the solar array deployment after the LV separation, is one of the hazard items at the launch site. Therefore, this interface should satisfy the single-fault tolerance requirement for the range safety. In this paper, we discuss the LV separation detection interfaces for two different satellite launch configurations and propose a method to guarantee for the satellite to start the LEOP even under the emergency case such as a partial separation from the LV. Furthermore, the proposed method meets the range safety requirement of the launch site. As this method only changes the external harness configuration of the satellite, it increases the reliability of the satellite early operation without any modification of the existing internal logics to detect the separation event.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.1
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• pp.165-173
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• 2023

Various linear system solvers with multi-physics analysis schemes are compared focusing on the near-field region considering thermal-hydraulic-chemical (THC) coupled multi-physics phenomena. APro, developed at KAERI for total system performance assessment (TSPA), performs a finite element analysis with COMSOL, for which the various combinations of linear system solvers and multi-physics analysis schemes should to be compared. The KBS-3 type disposal system proposed by Sweden is set as the target system and the near-field region, which accounts for most of the computational burden is considered. For comparison of numerical analysis methods, the computing time and memory requirement are the main concerns and thus the simulation time is set up to one year. With a single deposition hole problem, PARDISO and GMRES-SSOR are selected as representative direct and iterative solvers respectively. The performance of representative linear system solvers is then examined through a problem with an increasing number of deposition holes and the GMRES-SSOR solver with a segregated scheme shows the best performance with respect to the computing time and memory requirement. The results of the comparative analysis are expected to provide a good guideline to choose better numerical analysis methods for TSPA.

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.1-13
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• 2010

KC-100 is a 4 seats, single piston engine, civil aircraft whose type certificate is applied for KAS 23 (FAR 23) for the first time in Korea. Its system safety assessment and analysis have been conducted to meet the minimum safety requirement in KAS 23 and to verify the safety of equipment, system, and installation in accordance with the requirement of ${\S}$23.1309 and the guidelines in FAA AC 23.1309-1D and SAE ARP 4761. This safety assessment begins with the FHA (Functional Hazard Assessment) at aircraft and system level in preliminary design phase, and all of the safety assessment and analysis reports including the preliminary version of SSA (System Safety Assessment) have been prepared during detail design phase. The revised version of these safety reports will be approved by Airworthiness Authority through the ground and flight test phases. In this paper, the safety assessment requirement in ${\S}$23.1309, safety assessment guideline in AC 23.1309-1D, and safety assessment and analysis methods in ARP 4761 will be explained based on the application example for KC-100 development. The experience and knowledge of this system safety assessment for civil aircraft can be applied to commuter aircraft of FAR 23 class or large transport airplane of FAR 25 class.