• Journal of Korean Institute of Industrial Engineers
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• v.34 no.1
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• pp.79-89
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• 2008

An end-of-life strategy is concerned with how to disassemble a product and what to do with each of the resultingdisassembled parts. A sound understanding of the end-of-life strategy at the early design stage could improve theease of disassembly and recycling in an efficient and effective manner. Therefore, the end-of-life decisionmaking for environmental conscious design has become a great concern to product manufacturers.We introduce a novel concept ofeco-architecture which represents a scheme by which the physical componentsare allocated to end-of-life modules. An end-of-life module is a physical chunk of connected components or afeasible subassembly which can be simultaneously processed by the same end-of-life option without furtherdisassembly. In this paper, a method for analyzing the eco-architecture of a product at the configuration designstage is proposed. It produces an optimal eco-architecture under the given environmental regulations. To dealwith the case ofa complex product, the method is extended for analyzing hierarchical eco-architecture.

• Composites Research
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• v.15 no.6
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• pp.24-29
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• 2002

For the development of all composite unmanned aerial vehicle(UAV), the consideration for manufacturing in design phase and events in composite parts fabrication, subassembly and final assembly are summarized. In design phase, to maximize the advantages of composite material such as cocuring, cobonding and secondary bonding for manufacturing, the advanced structural concept is introduced. For the curing of designed parts, the manufacturing tools for composite parts are designed and manufactured. The assembly jigs are designed to meet dimensional tolerance requirements of the vehicle structure. And the inspection criteria are established and applied for the manufacturing. Technical data for inspection items and methodologies are summarized to utilize for the exclusive specifications of the manufacturing sequence.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2000.11a
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• pp.227-245
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• 2000

Korean firms have attempted to catch up in the aircraft industry during last quarter century. Korean firms have built up their capabilities by moving from parts manufacturing through subassembly to system integration. The number of projects carried out and the intensity of technological effort undertaken by firms strongly influences market position and firm performance. However, successful catching up is not simply dependent on capability building within the firm. The national environment (Porter, 1990) in which firms are located plays a pivotal role. The Korean government has been effective in creating a favorable environ-ment in many areas, but has not been able to replicate this success in the aircraft industry. Opportunities for learning in the aircraft industry have been hampered by the small size of the Korean civilian aircraft market and the sophisticated requirements of military systems. A policy of domestic rivalry in airframe manufacture has created too many firms for such a small market. The ability of Korean firms to catch up in the aircraft industry depends on both the internal capabilities of firms as well as appropriate government policies and the involve- ment of government research institutions and universities over an extended period of time. There have been many studies about the catching up of developing countries in mass production (such as automobile, consumer electronics, and recently DRAM), but few in complex systems, such as aircraft.

• Steel and Composite Structures
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• v.1 no.1
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• pp.145-158
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• 2001

An experimental study was conducted to evaluate the effects of loading sequence and lateral bracing on the behavior of reduced beam section (RBS) steel moment frame connections. Four full-scale moment connections were cyclically tested-two with a standard loading history and the other two with a near-fault loading history. All specimens reached at least 0.03 radian of plastic rotation without brittle fracture of the beam flange groove welds. Two specimens tested with the nearfault loading protocol reached at least 0.05 radian of plastic rotation, and both experienced smaller buckling amplitudes at comparable drift levels. Energy dissipation capacities were insensitive to the types of loading protocol used. Adding a lateral bracing near the RBS region produced a higher plastic rotation; the strength degradation and buckling amplitude were reduced. A non-linear finite element analysis of a one-and-a-half-bay beam-column subassembly was also conducted to study the system restraint effect. The study showed that the axial restraint of the beam could significantly reduce the strength degradation and buckling amplitude at higher deformation levels.

• ETRI Journal
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• v.38 no.1
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• pp.9-17
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• 2016

We demonstrate a time- and wavelength-division multiplexed passive optical network system employing a vertical-cavity surface-emitting laser array-based optical line terminal transceiver and a tunable bidirectional optical subassembly-based optical network terminal transceiver. A packet error-free operation is achieved after a 40 km single-mode fiber bidirectional transmission. We also discuss an arrayed waveguide grating, a photo detector array based on complementary metal-oxide-semiconductor photonics technologies, and low-cost key devices for deployment in access networks.

• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.81-90
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• 2019

The data rate for transmission through fiber-optic cables has increased to 400 Gbps in single-wavelength channels. However, speeds up to 1 Tbps are required now to meet the ever-increasing bandwidth demand driven by the diverse requirements of contemporary applications for high-quality on-demand video streaming, cloud services, various social media, and emerging 5G-enabled applications. Because the data rates of the per-channel optical interfaces depend strongly on the operational speed of the optoelectronic devices used in optical transceivers, ultrahigh-speed photonic devices and components, and eventually, chip-level transmitter and receiver technologies, are essentially required to realize futuristic optical transceivers with data rates of 1 Tbps and beyond. In this paper, we review the recent progress achieved in high-speed optoelectronic devices, such as laser diodes, optical modulators, photodiodes, and the transmitter-receiver optical subassembly for optical transceivers in data centers and in metro/long-haul transmission.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3888-3896
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• 2022

Nuclear data is the basis of reactor physics analysis. This paper aim at studying the influence of major evaluated nuclear data libraries, CENDL-3.2, ENDF/B-VIII.0, JEFF-3.3, and JENDL-4.0u, on the neutronics modelling of CEFR start-up tests. Results show these four libraries have a good performance and consistency in the modelling CEFR start-up tests. The JEFF-3.3 results exhibit only an 8 pcm k_eff difference with the measurement. The difference in criticality is decomposed by nuclide, which shows the large overestimation of CENDL-3.2 is mainly from the cross-section of ⁵²Cr. Except for few cases, the calculation results are within 1σ of measurement uncertainty in control rod worth, sodium void reactivity, temperature reactivity, and subassembly swap reactivity. In the evaluation of axial and radial reaction distribution, there are about 65% of relative errors that are less than 5% and 82% of relative errors that are less than 10%.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3897-3908
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• 2022

High-fidelity nuclear data libraries and neutronics simulation tools are essential for the development of fast reactors. The IAEA coordinated research project on "Neutronics Benchmark of CEFR Start-Up Tests" offers valuable data for the qualification of nuclear data libraries and neutronics codes. This paper focuses on the verification and validation of the CEFR start-up modelling using OpenMC Monte-Carlo code against the experimental measurements. The OpenMC simulation results agree well with the measurements in criticality, control rod worth, sodium void reactivity, temperature reactivity, subassembly swap reactivity, and reaction distribution. In feedback coefficient evaluations, an additional state method shows high consistency with lower uncertainty. Among 122 relative errors in the benchmark of the distribution of nuclear reaction, 104 errors are less than 10% and 84 errors are less than 5%. The results demonstrate the high reliability of OpenMC for its application in fast reactor simulations. In the companion paper, the influence of cross-section libraries is investigated using neutronics modelling in this paper.

• Steel and Composite Structures
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• v.51 no.2
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• pp.173-183
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• 2024

This study investigates a new seismic retrofit system that utilizes rotational friction dampers and axial springs. The retrofit system involves a steel frame with rotational friction dampers (RFD) at beam-column joints and linear springs at the corners, providing energy dissipation and self-centering capabilities to existing structures. The axial spring acts as a self-centering mechanism that eliminates residual deformations, while the friction damper mitigates seismic damage. To evaluate the seismic performance of the proposed retrofit system, a series of cyclic loading tests were carried out on a steel beam-column subassembly equipped with the proposed devices. An analytical model was then developed to validate the experimental results. A performance point ratio (PPR) was presented to optimize the design parameters of the retrofit system, and a performance-based seismic design strategy was developed based on the PPR. The retrofit system's effectiveness and the presented performance-based design approach were evaluated through case study models, and the analysis results demonstrated that the developed retrofit system and the performance-based design procedure were effective in retrofitting structures for multi-level design objectives.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.29-36
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• 2010

To investigate the cyclic characteristics of exterior joints in RC frame buildings which are typically used after 1988, 70% scaled T-shaped beam-column subassemblies were designed and tested with a displacement control that is composed of 9 steps, until 3.5% story drift was reached. Axial forces are applied to columns during the experiment to simulate a real situation. The results show that the non-seismic detailed specimens failed before reaching 0.85% story drift, and their strengths are less than 0.85 times the nominal flexural strength which beam or columns should reach. The relationship of principal stress and story drift of exterior joints is similar to the one that Priestly proposed.