• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.377-387
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• 2014

This study mainly treats a new type of the bracing friction damper system, which is able to minimize structural damage under earthquake loads. The slotted bolt holes are placed on the shear faying surfaces with an intention to dissipate considerable amount of friction energy. The superelastic shape memory alloy (SMA) wire strands are installed crossly between two plates for the purpose of enhancing recentering force that are able to reduce permanent deformation occurring at the friction damper system. The smart recentering friction damper system proposed in this study can be expected to reduce repair cost as compared to the conventional damper system because the proposed system mitigates the inter-story drift of the entire frame structure. The response mechanism of the proposed damper system is firstly investigated in this study, and then numerical analyses are performed on the component spring models calibrated to the experimental results. Based on the numerical analysis results, the seismic performance of the recentering friction damper system with respect to recentering capability and energy dissipation are investigated before suggesting optimal design methodology. Finally, nonlinear dynamic analyses are conducted by using the frame models designed with the proposed damper systems so as to verify superior performance to the existing damper systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.239-245
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• 2016

In this study, a 12 V PWM boost converter was designed with the optimal values of the external components of the power stage was well as the compensation stage for smart electronic applications powered by a battery device. The 12 V boost PWM converter consisted of several passive elements, such as a resistor, inductor and capacitor with a diode, power MOS switch and control IC chip for the control PWM signal. The devices of the power stage and compensation stage were designed to maintain stable operation under a range of load conditions as well as achieving the highest power efficiency. The results of this study were first verified by a simulation in SPICE from calculations of the values of major external elements comprising the converter. The design was also implemented on the prototype PCBboard using commercial IC LM3481 from Texas Instruments, which has a nominal output voltage of 12 V. The output voltage, ripple voltage, and load regulation with the line regulation were measured using a digital oscilloscope, DMM tester, and DC power supply. By configuring the converter under the same conditions as in the circuit simulation, the experimental results matched the simulation results.

• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.28-34
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• 2002

Purpose : The minimum stimulus onset asynchronoy(SOAmin) is one of important experimental parameters for an event-related fMRI experiment designed with the stochastic stimulus. In this study, the most efficient SOAmin is explored for the stronger activation in motor and language tasks with the stimulus designed stochastically. Materials and methods : The event-related fMRI during motor and language tasks were obtained in four normal right-handed subjects. EPI-BOLD sequence is used at 1.5Tesla MR system for the acquisition of event-related fMRI. For each task the subjects are responded for the stimulus' with 2, 3, 4, and 6 seconds SOAmin. The obtained images are processed with SPM99, and the p value is set as 0.05 for the significant activation detection. The Z value and the number of activated pixels are compared for each task. Results : For the motor task, the primary and supplementary motor areas are activated, and for the language task the consistent activated signals are detected in the Broca's. The activated signal is to be stronger for the shorter SOAmin for both motor and language tasks. At primary motor area, the activated signals is the strongest for 3 seconds SOAmin and for the supplementary motor area the result with 2 seconds SOAmin shows the strongest activation. And the result of language task shows the strongest activation at the 2 seconds SOAmin. Conclusion : In the event-related fMRI of motor and language tasks with the stochastically designed stimulus, the 2 or 3 seconds SOAmin is efficient for more activated and clustered activation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.270-276
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• 2020

3D printing is an additive manufacturing technology that can produce complex shapes in a single process for a range of materials, such as polymers, ceramics, and metals. Recent 3D printing technology has developed to a level that enables the mass-production through an improvement of the printing speed and the continuous development of applicable materials. In this study, 3D printing technology using a laser was applied to manufacture a heat exchanger for an air compressor in a railway vehicle. First, the optimal design of the heat exchanger was carried out by focusing on weight reduction and compactness as a shape suitable for 3D printing. Based on the design derived, heat exchanger prototypes were made of AlSi10Mg alloy material by applying the SLM technique. Moreover, the manufactured prototypes were attached to an existing air compressor, and the heat exchange performance of the compressed air was tested. The test results of the 3D printed prototypes showed a heat exchange performance of approximately 80% and 85% at low and high-pressure, respectively, compared to the existing heat exchanger. From the 𝓔-NTU method results with an external cooling air condition similar to that of the existing heat exchanger, the calculated heat transfer amount of 3D printed parts showed similar performance compared to the existing heat exchanger. As a result, the 3D printed heat exchanger is lightweight with good performance.

• Korean Journal of Cognitive Science
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• v.10 no.1
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• pp.25-43
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• 1999

The focus of this study is on the elements of structure design that facilitate u user interaction with applications within cyberspace Structure design entails decisions regarding the optimal classification and hierarchical organization of information into s successively higher units. i.e .. the grouping of highly related information in the form of nodes of a site and the subsequent connection of nodes that are inter-related. The decisions are based on the designer's subjective classification framework. which is not always compatible with that of the user. We propose that the ensuing cognitive dissonance can be reduced via the employment of multiple hierarchies and cross-referencing links. Multiple hierarchies represent a single information space in terms of a number of single hierarchies. each of which represent a different perspective Cross-referencing refers to the inter-connection between the constituent hierarchies by providing a link to the alternate hierarchy for information that is most likely to be categorized in diverse manners by users with differing perspectives. In this study we conducted two empirical studies to gauge the effectiveness of multiple hierarchies and Cross-referencing links in the domain of cyber shopping malls. In the first phase. an experiment was conducted to determine how subjects classified given products with respect to two different perspectives for categorization. Experimental cyber malls were developed based on the results from the first phase to test the effectiveness of multiple hierarchies and cross-referencing links. Results show that the ease of navigation was higher for cyber malls that had implemented cross-referencing links are of greater value when used in conjunction with single hierarchical designs rather than multiple hierarchies. Users satisfaction with and ease of navigation was higher for cyber malls that had not implemented multiple hierarchies. This paper concludes with discussion of these results and their implications for designers of cyber malls.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.568-574
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• 2017

The purpose of this study was to optimize experimental conditions (time ($X_1$) (ranging of 26.36 - 93.64 min), concentration of sulfuric acid ($X_2$) (ranging of 0-2.5%) and temperature ($X_3$) (ranging of $136.4-203.6^{\circ}C$) for an organosolv pretreatment process to extract lignin from waste wood. The resulting quadratic model equation using RSM (response surface methodology) represented y (lignin yield) = $-79.89+0.91X_1+9.8X_2-2.54{\times}10^{-3}X_1{^2}-2.11X_2{^2}$. The $R^2$ (coefficient of determination) value of 0.8531 for a model indicates this model has statistically significant predictors at the 10% levels. The predictive results optimized by quadratic model produced a lignin yield of 12.46 g/100 g of dry wood under conditions of $178.2^{\circ}C$ and 2.32% $H_2SO_4$. The lignin yield was more affected by the acid catalyst concentrations than the reaction temperature, but the reaction time was not an influential factor for improving lignin extraction from waste wood in this organosolv pretreatment. According to ANOVA (analysis of variance), the significance probability (p-value) of model was smaller than 0.001 and simulation of obtained model equations showed a good reproducibility based on actual organosolv tests under optimal conditions.

• Resources Recycling
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• v.24 no.5
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• pp.15-21
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• 2015

Waste plastic differs in its speed of combustion owing to its variety in composition as well as kinds of plastic. This study is aimed at examining the thermal weight analysis and determination of its kinetics in order to derive the design element in pyrolysis of RPF (Refused Plastic Fuel) as the plastic solid fuel. Based on the result of TGA (Thermogravimetric analysis), kinetic characteristics were analyzed by using Kissinger method which are the most common method for obtaining activation energy, and experimental conditions of TGA were set as follows: in a nitrogen atmosphere, gas flow rate of 20 ml/min, heating rate of $5{\sim}50^{\circ}C/min$, and maximum hottest temperature of $800^{\circ}C$. The method used for determining the property of waste plastic when thermally decomposed was thought feasible as the basic data in deciding the performance, design, and optimal operating condition of the reactor in the actual reactor.

• Journal of Digital Contents Society
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• v.19 no.3
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• pp.505-512
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• 2018

Internet demand has increased rapidly, and Internet Protocol Version 4, the main Internet protocol, can not cope with various types of network demand in the future. Therefore, it is urgent to spread IPv6-based stable network to solve the shortage of Internet address resources. Due to the proliferation of IoT and the increase in mobile devices, efficient and optimal IPv6 routing design is indispensable. In this paper, we have studied about characteristics of IPv6, address system of IPv6, structure analysis and efficient routing technology among IPv6 terminals. Furthermore, experimental results on routing packet analysis and convergence time are presented in network - based IPv6 routing implementation environment. In addition, we show the results of the experiment analysis by dividing the implementation of IPv6 routing, operation test, and fail over performance into three kinds of routing protocol methods. As a result, this study can be applied to the introduction of IPv6 system, test bed environment construction, and network design.

• Journal of the Korea Fashion and Costume Design Association
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• v.5 no.2
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• pp.75-91
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• 2003

This study analyzed descriptions about dots, lines, and sides which are used as a basic elements to express geometric figures as followings: -In the aspect of formative art, dots form images and feelings through their concurrence when make a slight move to coordinates. The concurrence can bring out either positive or negative images; -Lines have unlimited variation as a core measure in body art. They can make optimal effects with different lines such as straight and curved lines of human body; -Sides express not only effects of texture and perspective but also of space and solid by color effects. Expressive characteristics and geometric shapes can be classified by tattoo, henna and body painting: First, colorful tattoos are favored by Caucasian and original tattoos are mostly used by yellow and colored races in the way of scarification to get decorative effects. Recently, a rapid cycle of fashion change in tattoo figures has developed a tentative method of tattooing and a variety of decoration methods. It has made it a lot easier to change a pattern of a tattoo. Tattoos are now popular among people because they no longer have to suffer from pains when they get their body tattooed for a long time. Since tattoos boast their unique beauty which consists of most dynamic and attractive images among the types of body art. It will be one of the most favored make-up methods in the nearest future. Second, geometric designs used in henna include crosses, dots, straight lines, triangles, date palms, and so on. Henna has been particularly loved as an instant decoration by the public since it gradually disappears as time goes on. Third, body painting enables to draw a three-dimensional effect because of its close relation with body movements in a limited space. Each individual will have a different feeling appealed in their body painting. Body painting has been applied to many different areas, especially to theatrical art using lights, music and performance altogether producing impromptu and experimental works. Unlike other arts such as painting, sculpture, visual and industrial arts, body painting has mobility. Since it is painted on a three-dimensional human body, it can bear originality expressing realistic objects or animals and strengthen creative functions using body lines. Moreover, geometric designs can be diversified by the sexes. As a result of analysis, geometric designs expressed in body art seemed to transcend expressions of beauty and turned out to be another way of decoration. Body art has also been used as a way to express visual integration and consolidation dynamically not by human instinct but by social changes. The needs for body art will grow as the future comes nearer and be recognized as a new and fresh value. Formative elements of geometric figures deliver visual impressions combined with human body and finally create more various types of body art in harmony of body lines.

• The KIPS Transactions:PartD
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• v.12D no.7 s.103
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• pp.1049-1064
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• 2005

The demands of increasingly complicated software have led to the proliferation of object-oriented design methodologies in embedded systems. To execute a system designed with objects in target hardware, a task set should be derived from the objects, representing how many tasks reside in the system and which task processes which event arriving at an object. The derived task set greatly influences the responsiveness of the system. Nevertheless, it is very difficult to derive an optimal task set due to the discrepancy between objects and tasks. Therefore, the common method currently used by developers is to repetitively try various task sets. This paper proposes Scenario-based Implementation Synthesis Architecture (SISA) to solve this problem. SISA encompasses a method for deriving a task set from a system designed with objects as well as its supporting development tools and run-time system architecture. A system designed with SISA not only consists of the smallest possible number of tasks, but also guarantees that the response time for each event in the system is minimized. We have fully implemented SISA by extending the ResoRT development tool and applied it to an existing industrial PBX system. The experimental results show that maximum response times were reduced $30.3\%$ on average compared to when the task set was derived by the best known existing methods.