• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.329-337
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• 1999

In this dissertation, the characteristics of W-CDMA(Wideband CDMA) are studied and required specifications of IMT-2000 transceiver using W-CDMA method are proposed. Also, in order to design the RF circuits satisfied the proposed specifications, theoretical models are expanded and real circuits are made. Then the RF circuits of the mobile stations are implemented in the three parts, transmitter, receiver and frequency synthesizer and are evaluated. The frequency synthesizer is designed using techniques of swallow counter and passive 3rd loop filter. For improving characteristics of the loop, a LPF was added to the 2nd loop filter. So although the locking times are loosed, the spurious are reduced. The output power of transmitter is over 50mW, the spurious output is -40dB/30kHz at 5MHz offset and power control range is -20dB at 2.5V. The proposed specifications are considered in highly practical environment and the theoretical designs and the experiments are expressed as simply as possible in order to facilitate understanding. It stands to reason that the results of this study can be used to design the wider CDMA(25MHz Bandwidth) mobile communication systems.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.5
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• pp.58-72
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• 2003

Rooftop greenery has been used as a way to solve urban environmental problems by creating green space in densely populated cities. This study was carried out to suggest more effective designs for roof-garden at hospitals through a post-occupancy evaluation. The roofgarden of Asan Medical Center was evaluated with regards to setting, proximate environmental context, users, and design activity by a multi-method including plan investigations, observations, in-depth interviews and questionnaires. The results are summarized as follows; the users' main activities included resting, walking, and talking. A number of users were observed at shaded spaces sitting on such things as benches, pergolas, and shelters. The satisfaction of the users showed high satisfaction level except in the amount of shade, facilities, and shelter. The variables affecting a overall satisfaction were ‘accessibility’, ‘safety’, ‘quality of surroundings’, and ‘suitability for speculation’. By comparing the design concept with using pattern, designer's intention was not reflected sufficiently in several aspects such as ‘event deck for therapy programs’, ‘grove and path’, and ‘low planters’. This study suggests some design implications; it is necessary to furnish shaded sitting places for passive behaviors and pathways for walking or a light exercise. A wind-break wall with glass windows could widen the users' views in a limited space. Natural shade like tree shade or pergola are more desirable than artificial shades. As for the vertical location of the roofgarden, the middle floor could be better than top area for accessibility. Characteristics of building and users should be considered in detail to provide distinct spaces. Proper technical standards for the greening of artificial ground should be established.

• Journal of Internet Computing and Services
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• v.14 no.6
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• pp.9-18
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• 2013

In this paper, we design and implement an intelligent system for finding objects with RFID(Radio Frequency IDentification) tag in which an mobile robot can do. The system we developed is a learning system of artificial neural network that uses RSSI(Received Signal Strength Indicator) value as input and absolute coordination value as target. Although a passive RFID is used for location estimation, we consider an active RFID for expansion of recognition distance. We design the proposed system and construct the environment for indoor location estimation. The designed system is implemented with software and the result related learning is shown at test bed. We show various experiment results with similar environment of real one from earning data generation to real time location estimation. The accuracy of location estimation is verified by simulating the proposed method with allowable error. We prepare local test bed for indoor experiments and build a mobile robot that can find the objects user want.

• Journal of Fashion Business
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• v.8 no.5
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• pp.41-59
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• 2004

The purpose of this study is to analyze consumers' purchase behavior for the counterfeits of fashion luxury brands. The research method of the study used a naturalistic approach. The first participant observation was carried out in the internet sites in order to collect the data on the purchase behavior for counterfeits; and the second participant observation was applied in the Dongdaemun shopping mall, Namdaemun shopping mall and Itaewon shopping mall; finally 6 informants were selected and then an interview was held with them. The results of the study are as follows; 1. The reasons for the first purchase of counterfeits are variously shown according to life stages, and the repetitive purchase behavior is influenced by the degree of satisfaction for the first purchase. The information collection for counterfeits is widely made through various media, and especially the information collection is active and positive in the case of planned purchase but it is passive and negative in the case of unplanned purchase. 2. The most important criteria in purchasing counterfeits is the degree of similarity with luxury brands and other criteria include price, design, utility etc. The majority of purchase items is not clothing but miscellaneous goods which are more similar in terms of design and quality. The purchase of counterfeits is made by impulse purchase but the purchase of luxury brands is made by planned purchase. 3. The rationalization mechanism for the purchase of counterfeits is observed in all informants, which is a sort of defence mechanism for avoiding a guilty conscience to buy illegal goods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.814-821
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• 2015

The STEP Cube Lab. classified as a pico-class satellite has been successfully developed as a flight model(FM) to be launched in 2015. Its mission objective is to perform the on-orbit verification of fundamental space core-technologies. In this study, a thermal design concept based on the passive method to achieve the mission objective is introduced. The effectiveness of the thermal design and performance of the satellite has been verified through the acceptance level thermal vacuum test. In addition, to improve the reliability of thermal mathematical model, correlation was performed using the results of thermal balance test. This paper describes a series of process for the thermal vacuum test on the STEP Cube Lab. FM.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.1-6
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• 2016

The Internet of Things (IoT) is a new technology paradigm demanding one packaged system of various semiconductor and MEMS devices. Therefore, the development of electronic packaging technology with very high connectivity is essential for successful IoT applications. This paper discusses both fan-out wafer level packaging (FOWLP) and 3D stacking technologies to achieve the integrattion of heterogeneous devices for IoT. FOWLP has great advantages of high I/O density, high integration, and design flexibility, but ultra-fine pitch redistribution layer (RDL) and molding processes still remain as main challenges to resolve. 3D stacking is an emerging technology solving conventional packaging limits such as size, performance, cost, and scalability. Among various 3D stacking sequences wafer level via after bonding method will provide the highest connectivity with low cost. In addition substrates with ultra-thin thickness, ultra-fine pitch line/space, and low cost are required to improve system performance. The key substrate technologies are embedded trace, passive, and active substrates or ultra-thin coreless substrates.

• Korean Institute of Interior Design Journal
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• v.21 no.3
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• pp.103-110
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• 2012

Interior Coordination is the activity of making characteristic living space by planning and harmonizing various interior elements. In modern society, the taste and needs of the residents are getting varied and segmented, and the role of interior coordination is getting more important because that reflects cultural codes and trends and satisfies residents' needs. This study aims to investigate awareness and needs about interior coordination targeting apartment residents, and to provide fundamental data that could attribute to the planning of unique and diverse residential spaces. Methods of study include the literature research and the empirical study. Elements of interior coordination were extracted through the literature review, and the questionnaire was developed using these elements. And then a survey was carried out targeting apartment residents of Busan. The result shows that most of the residents were much interested in interior coordination, and they recognized it's importance. They wanted to plan and select the elements by themselves, but were passive in actual execution because of the difficulties in execution methods and economical conditions. There were certain differences between the styles of their own houses and the preferred styles, but they did not try actively to reconcile the differences. Therefore, various methods of interior coordination should be developed and proposed which are easy and effective for actual execution, and various media should be provided by which residents could easily get informations on design elements. Also, the concept and method of interior coordination should be considered from the very first stage of residential planning, and the replacement and modification of interior coordination could be easily done according to the change of life cycle and life styles.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.765-779
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• 2019

Most of the existing evaluation criteria of vibration serviceability rely on the peak acceleration of the structure rather than that of the people keeping their own body unmoved on the structure who is the real receiver of structural vibrations. In order to accurately assess the vibration serviceability, therefore, a full path assessment approach of vibration serviceability based on vibration source, path and receiver is not only tentatively proposed in this paper, taking the peak acceleration of receiver into account, but also introduce a probability procedure to provide more instructive information instead of a single value. In fact, semi-rigid supported on both sides of the structure is more consistent with the actual situation than simply supported or clamped due to the application of the prefabricated footbridge structures. So, the footbridge is regarded as a beam with semi-rigid supported on both sides in this paper. The differential quadrature-integral quadrature coupled method is not only to handle different type of boundary conditions, but also after being further modified via the introduction of an approximation procedure in this work, the time-varying system problem caused by human-structure interaction can be solved well. The analytical results of numerical simulations demonstrate that the modified differential quadrature-integral quadrature coupled method has higher reliability and accuracy compared with the mode superposition method. What's more, both of the two different passive control measures, the tuned mass damper and semi-rigid supported, have good performance for reducing vibrations. Most importantly, semi-rigid supported is easier to achieve the objective of reducing vibration compared with tuned mass damper in design stage of structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.145-152
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• 2015

In the study, the effects of damping devices on damping ratio increase and wind-load reduction were investigated based on the computational platform, which is one of the parametric modeling methods. The computational platform helps the designers or engineers to evaluate the efficacy of the numerous alternative structural systems for irregular Super-Tall building, which is crucial in determining the capacity and the number of the supplemental damping devices for adding the required damping ratios to the building. The inherent damping ratio was estimated based on the related domestic and foreign researches conducted by using real wind-load records. Two types of damping devices were considered: One is inter-story installation type passive control devices and the other is mass type active control devices. The supplemental damping ratio due to the damping devices was calculated by means of equivalent static analysis using an equation suggested by FEMA. The optimal design of the damping devices was conducted by using the computational platform. The structural element quantity reduction effect resulting from the installation of the damping devices could be simply assessed by proposing a wind-load reduction factor, and the effectiveness of the proposed method was verified by a numerical example of a 455m high-rise building. The comparison between roof displacement and the story shear forces by the nonlinear time history analysis and the proposed method indicated that the proposed method could simply but approximately estimate the effects of the supplemental damping devices on the roof displacement and the member force reduction.

• Wind and Structures
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• v.38 no.1
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• pp.15-42
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• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.