• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.189-197
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• 2007

Concrete tunnel lining must be designed to having the fireproof performance because the lining are sometimes exposed to very high temperature due to traffic accident. Such fire temperature may cause explosion of concrete, or collapse of tunnel structure. The purpose of this study is to obtain the fundamental fireproof behavior of fire resistance-engineered cementitious composites(FR-ECC) under fire temperature in order to use the fire protection material in tunnel lining system. The present study conducted the experiment to simulate fire temperature by employing 2 types of FR-ECC and investigated experimentally the explosion and cracks in heated surface of these FR-ECC. Employed temperature curve were hydro carbon(HC, ECl) criterion, which are severe in various criterion of fire temperature. The numerical analysis is carried out the nonlinear transient heat flow analysis and verified against the experimental data. The complex features of behavior in fire conditions, such as thermal expansion, plasticity, cracking or crushing, and material properties changing with temperature are considered. By the use of analytical model, the concrete tunnel subjected to fire loads were analyzed and discussed. With comparison of current concrete materials and FR-ECC, the experimental and analytical results of FR-ECC shows the better fire resistance performance than the other.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.26-35
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• 2009

OFDM (Orthogonal Frequency Division Multiplexing) system is robust to frequency selective fading and narrowband interference in high-speed data communications. However, an OFDM signal consists of a number of independently modulated subcarriers and the superposition of these subcarriers causes a problem that can give a large PAPR(Peak-to-Average Power Ratio). Phase rotation method can reduce the PAPR without nonlinear distortion by multiplying phase weighting factors. But computational complexity of searching phase weighting factors is increased exponentially with the number of subblocks and considered phase factor. Therefore, a new method, which can reduce computational complexity and detect phase weighting factors efficiently, should be developed. In this paper, a modeling process is introduced, which apply metaheuristic algerian in phase rotation method and optimize in PTS (Particle Swarm Optimization) scheme. Proposed algorithm can solve the computational complexity and guarantee to reduce PAPR We analyzed the efficiency of the PAPR reduction through a simulation when we applied the proposed method to telecommunication systems.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.104-113
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• 2011

While converging USN Services, a single physical infrastructure can be used in several services and in several physical infrastructures can make up a single service. Therefore the physical infrastructure and service have to manage separately for effective convergence of USN Services. However, established Identification Scheme is not suitable to distinguish various services that USN provides. This paper suggests USN Service Identification Scheme that can be separated and managed. Through USN Service Identification Scheme suggested, firstly, it is possible to obtain Service Identification Scheme utilizing various technology such as RFID TAG, QR Code, radio broadcasting, etc. because it is possible to process USN Service Identification Scheme. Secondly, it is easy to mange the service, develope the user application program and interlock with established USN Standard technique as view from service provider. Thirdly, it is possible to manage systematically USN Service. Fourthly, users can search USN Service easily, so it can contribute actively for invigoration of USN service. This thesis, firstly, has analyzed about standard related USN Service and USN Identification Scheme. Secondly, this has suggested brand-new USN Service Identification Scheme based on established USN Identification Scheme.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.88-96
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• 2011

Underwater acoustic communication is applicable in various areas, such as ocean data collection, undersea exploration and development, tactical surveillance, etc. Thus, robot control system construction used for underwater-robot like AUV or ROV is essential in these areas. In this paper, we propose the Message Merging MAC($M^2$-MAC) protocol, which is suitable for real time robot control system, considering energy efficiency in important parts of underwater acoustic sensor network constitution. In this proposed MAC protocol, gateway node receives the data from robot nodes according to the time slots that were allotted previously. And messages delivered from base-station are generated to one MAC frame by buffering process. Finally, generated MAC frames are broadcasted to all robot nodes in the cluster. Our suggested MAC protocol can also be hybrid MAC protocol, which is successful blend of contention based and contention-free based protocol through relevant procedure with Maintenance&Sleep (M&S) period, when new nodes join and leave as an orphan. We propose mathematical analysis model concerned about End-to-End delay and energy consumption, which is important factor in constructing real-time robot control system. We also verify the excellence of performance according to comparison of existing MAC protocols with our scheme.

• Industry Promotion Research
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• v.5 no.2
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• pp.33-40
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• 2020

When most middle-aged women live in a time when they have to take responsibility for their lives, they feel lonely when they realize that their experience of not expressing their feelings properly has ended up being left alone due to their own existence and loss. As the first step in conscious awareness of unconsciousness of middle-aged women through analytical psychology, we performed "Mandara" and "Nanhwa Mandara," which meet me inside. The intermediate stage can be divided into transition and work phase. The working phase, develops one's own advantages and unique strengths that meet the inner world of promoting and acting values, correctly looks at reality, corrects emotion perception and balance, and is self-contained, seed mandala, associative mandala. They performed the strong points of mandala, the free mandala, and the Western mandala. The results of the study showed that mandala art therapy was found in middle-aged women. First, Mandarin art therapy experience affects the physical, psychological and human relations aspects of middle-aged women. Second, middle-aged women's experience of individualization through mandala art therapy shows psychological reversals and affects positive thinking and self-effectiveness. This study was suitable for qualitative research that approached the essence through practical understanding and direct exploration of research participants, and it is meaningful to suggest that it is necessary to develop an art therapy program through various mediums considering the lack of art therapy research in middle-aged women and problems experienced by the physician.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.253-258
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• 2005

Characteristics of electroplated Ni films such as grain size, resistivity, solder wetting angle, and growth rate of intermetallic compound were evaluated as a function of electroplating current density. With increasing the electroplating current density from $5\;mA/cm^2 $ to $40\;mA/cm^2 $, the nodule size on the Ni film surface decreased, grain refinement occurred, and resistivity increased from $7.37\mu\Omega-cm$ to $9.13\mu\Omega-cm$. Compared with Ni film processed at $40\;mA/cm^2 $, Ni films electroplated at $5\;mA/cm^2 $ and $10\;mA/cm^2 $ exhibited low resistivity, dense microstructure, and slow growth rate of intermetallic compound. Ni films electroplated at $5\;mA/cm^2 $ and $10\;mA/cm^2 $ are more suitable for Ni UBM application than that fabricated at $40\;mA/cm^2 $.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.31-39
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• 2014

For mobile application, semiconductor packages are increasingly moving toward high density, miniaturization, lighter and multi-functions. Typical wafer level packages (WLP) is fan-in design, it can not meet high I/O requirement. The fan-out wafer level packages (FOWLPs) with reconfiguration technology have recently emerged as a new WLP technology. In FOWLP, warpage is one of the most critical issues since the thickness of FOWLP is thinner than traditional IC package and warpage of WLP is much larger than the die level package. Warpage affects the throughput and yield of the next manufacturing process as well as wafer handling and fabrication processability. In this study, we investigated the characteristics of warpage and main parameters which affect the warpage deformation of FOWLP using the finite element numerical simulation. In order to minimize the warpage, the characteristics of warpage for various epoxy mold compounds (EMCs) and carrier materials are investigated, and DOE optimization is also performed. In particular, warpage after EMC molding and after carrier detachment process were analyzed respectively. The simulation results indicate that the most influential factor on warpage is CTE of EMC after molding process. EMC material of low CTE and high Tg (glass transition temperature) will reduce the warpage. For carrier material, Alloy42 shows the lowest warpage. Therefore, considering the cost, oxidation and thermal conductivity, Alloy42 or SUS304 is recommend for a carrier material.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.15-21
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• 2015

Recently, attempts of replacing some of natural aggregate with mix of low quality aggregate are carried out for stable supply of aggregate. However, low quality aggregate such as recycled aggregate produced during the disposal process of construction wastes and by-product aggregate produced by industrial activities has problem of failing to comply to KS Standards. Therefore, we have compared fundamental properties of concrete by using granite crushed aggregate, recycled aggregate, blast furnace and electric arc furnace slag aggregate for effective utilization of lacking aggregate resources. As the result, slump in case of mixed use of aggregate was increased 0~10% compared to single use. Therefore, it is judged to be economically advantageous as it can expect effects in unit quantity or reduction of SP agent. Compressive strength in case of mixed use of aggregate was increased 0~10% compared to single use as it filled internal crevice of concrete with continuous particle size distribution. Accordingly, if we utilize by satisfying standard particle scope through mix of aggregate with different cause of formation in proper ratio, it was possible to confirm utility of mixed aggregate with demonstration of effects of increases of fluidity and compressive strength of concrete.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.60-67
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• 2013

A diffusion coefficient is an important parameter in the prediction of atmospheric dispersion using a Gaussian plume model, and its modelling approach varies. In this study, dispersion coefficients recommended by the U. S. Nuclear Regulatory Commission's (U. S. NRC's) regulatory guide and the Canadian Nuclear Safety Commission's (CNSC's) regulatory guide, and used in probabilistic accident consequence analysis codes MACCS and MACCS2 have been investigated. Based on the atmospheric dispersion model for a hypothetical accidental release recommended by the U. S. NRC, its influence to atmospheric dispersion factor was discussed. It was found that diffusion coefficients are basically predicted from a Pasquill- Gifford curve, but various curve fitting equations are recommended or used. A lateral dispersion coefficient is corrected with consideration for the additional spread due to plume meandering in all models, however its modelling approach showed a distinctive difference. Moreover, a vertical dispersion coefficient is corrected with consideration for the additional plume spread due to surface roughness in all models, except for the U. S. NRC's recommendation. For a specified surface roughness, the atmospheric dispersion factors showed differences up to approximately 4 times depending on the modelling approach of a dispersion coefficient. For the same model, the atmospheric dispersion factors showed differences by 2 to 3 times depending on surface roughness.

• Journal of The Korean Association For Science Education
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• v.35 no.6
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• pp.961-970
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• 2015

This study aims to develop the NABI program, which can be applied to science education in school, to realize 'Science Education through Nature' for today's students. The first NABI program was developed based on the viewpoints of education and teaching methods of Nature-Study, and it was revised as the second NABI program through experts' workshop. The second NABI program was applied to 24 third-grade students of an elementary school. The possibility of applying the program to school science education was explored through the analysis of students' qualitative data, along with surveys that were completed by 24 students and 79 current teachers. As a result of applying the program, students were curious about and communed with nature. The program could also realize the learner-centered education and integration of subjects, science with literature and art. The students were interested and wanted to continually participate in the NABI program. The teachers' evaluation of the program deduced that the relationship between the program presenting Nature-Study ideologies could be applied to science education in school. In conclusion, it was found that the NABI program was well reflected in the scope of the Nature-Study, and it can be applied to science education in school. The NABI program proceeds in nine steps: 'Accepting - Choosing - Selecting the common subject - Ice Breaking - Making relationship - Observing - Scaffolding - Expressing - Sharing'. The NABI program is a good way to realize the essence of science education, 'Science Education through Nature', for today's students.