• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.109-116
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• 2012

A vent-relief valve performs as a safety-valve assembly for liquid propellant feeding system of space launch vehicle, which relives pressurant propellant tanks during the filling and the flight. At vent mode, valve is opened and closed by driving pneumatic pressure, and at relief mode, valve is automatically operated to set relief pressure. In this study, we have analyzed a basic layout of vent-relief valve which is designed using foreign LVs(Saturn) to satisfy requirements of Korean Space Launch Vehicle. The simulation model of vent-relief valve is designed by using the AMESim code to verify design parameters and evaluate pneumatic behaviors of valve. In this study, we performed dynamic characteristic simulations on design parameters. And we could predict opening/closing time and pressures, operating performances on design parameters. Using this results, we could suggest detail design and boundary conditions of design.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.47-52
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• 2013

Gold wire has long been used as a proven method of connecting a silicon die to a substrate in wide variety of package types, delivering high yield and productivity. However, with the high price of gold, the semiconductor packaging industry has been implementing an alternate wire material. These materials may include silver (Ag) or copper (Cu) alloys as an alternative to save material cost and maintain electrical performance. This paper will analyze and compare the electrical characteristics of several wire types. For the study, typical 0.6 mil, 0.8 mil and 1.0 mil diameter wires were selected from various alloy types (2N gold, Palladium (Pd) coated/doped copper, 88% and 96% silver) as well as respective pure metallic wires for comparison. Each wire model was validated by comparing it to electromagnetic simulation results and measurement data. Measurements from the implemented test boards were done using a vector network analyzer (VNA) and probe station setup. The test board layout consisted of three parts: 1. Analysis of the diameter, length and material characteristic of each wire; 2. Comparison between a microstrip line and the wire to microstrip line transition; and 3. Analysis of the wire's cross-talk. These areas will be discussed in detail along with all the extracted results from each type the wire.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.497-503
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• 2016

In this study, we formulate an acoustical topology optimization problem to optimally design a partition layout inside the expansion chamber of a muffler. The lower-limit insertion loss value at a target frequency is constrained, and the partition volume is selected as an object function. In this study, we calculate the insertion loss outside the duct, while to determine the noise-attenuation performance, we use the insertion loss value calculated inside the duct or transmission loss value obtained in a previous study. We employ the finite-element model for acoustical analysis, and we determine the transmission of an incident acoustic wave through each finite element using the functions of design variables that change continuously between "0" and "1." The rigid body elements, which totally reflect incident waves, build up partitions. Finally, we compare optimal topologies that depend on the target frequency and the allowed lower-limit value of insertion loss.

• Earthquakes and Structures
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• v.17 no.6
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• pp.545-556
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• 2019

Bridge piers with bending failure mode are seriously damaged only in the area of plastic hinge length in earthquakes. For this situation, a modified method for the layout of longitudinal reinforcement is presented, i.e., the number of longitudinal reinforcement is increased in the area of plastic hinge length at the bottom of piers. The quasi-static test of three scaled model piers is carried out to investigate the local longitudinal reinforcement at the bottom of the pier on the seismic performance of the pier. One of the piers is modified by increased longitudinal reinforcement at the bottom of the pier and the other two are comparative piers. The results show that the pier failure with increased longitudinal bars at the bottom is mainly concentrated at the bottom of the pier, and the vulnerable position does not transfer. The hysteretic loop curve of the pier is fuller. The bearing capacity and energy dissipation capacity is obviously improved. The bond-slip displacement between steel bar and concrete decreases slightly. The finite element simulations have been carried out by using ANSYS, and the results indicate that the seismic performance of piers with only increasing the number of steel bars (less than65%) in the plastic hinge zone can be basically equivalent to that of piers that the number of steel bars in all sections is the same as that in plastic hinge zone.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.1-9
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• 2011

Memristor is a portmanteau of "memory resistor". The resistance of memristor is changed depends on the history of electric charge that passed through the device and it is able to memorize the last resistance after turning off the power supply. This paper presents this device that has a high chance to be the next generation of commercial non-volatile memory and its behavior modeling using SPICE simulation. The memristor MOS content addressable memory (M_CAM) is also designed and simulated using the proposed behavioral model. The proposed M_CAM unit cell area and power consumption show an improvement around 40% and 96%, respectively, compare to the conventional SRAM based CAMs. The M_CAM layout is also implemented using 0.13${\mu}m$ mixed-signal CMOS process under 1.2 V supply voltage.

• Smart Structures and Systems
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• v.19 no.4
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• pp.341-350
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• 2017

Based on the super elastic properties of the shape memory alloy (SMA) and the inverse piezoelectric effect of piezoelectric (PZT) ceramics, a kind of hybrid semi-active control device was designed and made, its mechanical properties test was done under different frequency and different voltage. The local search ability of genetic algorithm is poor, which would fall into the defect of prematurity easily. A kind of adaptive immune memory cloning algorithm(AIMCA) was proposed based on the simulation of clone selection and immune memory process. It can adjust the mutation probability and clone scale adaptively through the way of introducing memory cell and antibody incentive degrees. And performance indicator based on the modal controllable degree was taken as antigen-antibody affinity function, the optimization analysis of damper layout in a space truss structure was done. The structural seismic response was analyzed by applying the neural network prediction model and T-S fuzzy logic. Results show that SMA and PZT friction composite damper has a good energy dissipation capacity and stable performance, the bigger voltage, the better energy dissipation ability. Compared with genetic algorithm, the adaptive immune memory clone algorithm overcomes the problem of prematurity effectively. Besides, it has stronger global searching ability, better population diversity and faster convergence speed, makes the damper has a better arrangement position in structural dampers optimization leading to the better damping effect.

• Archives of design research
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• v.19 no.4 s.66
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• pp.101-110
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• 2006

In this study, I suggested a new model of universal web navigation design which can enhance users' web usability. I would like to prove that when users enjoy web navigation design, they access information much more effectively. Using a survey, I suggest some types of web navigation design for users. After that, I conducted an experiment with 4 types of web navigation designs, which have been developed to reflect varying stages of comprehensibility. My survey focused on three points. First I measured the time they spent to search for information. Second, I tested whether they lost their way while searching for information and if they did lose their way, I checked whether they could recover from their errors and find their way back. Third, I investigated whether layout, location and size of the web navigation design factors affected usability. The results of my survey indicated that users spend the shortest time, have the easiest interface, and have least error incidence under the web navigation design to enhance old-aged users' web usability. Thus, developing a universal web navigation design can encourage people to be more involved with the internet.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.75-79
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• 2013

Demands for semiconductor devices are dramatically increasing, and advancements in fabrication technology are allowing a step-up in the number of devices per unit area. As a result, semiconductor devices require higher heat dissipation, and thus, cooling solutions have become important for guaranteeing their operational reliability. In particular, in chip-in-board packages, in which chips and passives are embedded in the substrates for efficient device layout, heat dissipation is of greater importance. In this study, a thermal model for layers of different materials has been proposed, and then, the heat transfer has been simulated by imposing a set of appropriate boundary conditions. Heat generation can be predicted based on the results, which will be utilized as practical data for actual package design.

• Archives of design research
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• v.16 no.1
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• pp.73-82
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• 2003

This paper presents a case study of designing the stroller and its renting system for department stores in order to verify the feasibility of the participatory design approach, in particular the concept generation toolkits and the participatory design workshops, in the product development process. As the concept generation toolkits to draw active user participation, a Velcro Covered stroller model and a Block Layout System were developed and used in a series of the participatory design workshops. The results suggest that the participatory design approach provides better understanding of what the users want and allows designers to avoid false expectation about the design context. It was also found that the experience of design team with the users in the workshop was a good source of design ideation. The study also suggests that participatory design approach can become more effective by developing the concept generation toolkits which are more appropriate for design problems and the methods to smoothly transform the concepts from users into synthesized design solutions.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.4
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• pp.716-732
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• 2016

Focusing on the communication effects of fast fashion visual merchandising (VM), this paper examines the effects of a fast fashion store's VM attributes on consumer's perceptions of store image towards newness and prestige that influence the time spent at stores as well as the frequency of visits. This study was conducted by collecting data online using males and females in their twenties to forties; subsequently, a total of 382 samples were analyzed. The VM communication effect model utilized in fast fashion stores was developed and tested on structural equation modeling. The findings of the study were as follows. First, the show window presentation and ancillary facilities of VM elements have a positive effect on the perception of newness, while merchandise display, layout, and signage have a positive influence on the perception of prestige. Therefore, the VM elements in the fast fashion stores that affect the perception of newness and prestige are unique. Second, the perceptions of newness and prestige have a positive impact on time spent in fast fashion stores; however, only the perception of store's newness has a significant effect on the frequency of visits. Third, show window presentation and facilities are VM elements that directly influence the time spent and frequency of visits. Finally, we confirm that store image partially mediate between VM elements and shopping behavior at a fast fashion store.