• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.23-30
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• 2018

Recently, there are highly interests on structural damping to improve resistance of seismic and wind. It has been frequently used hysteresis damping devices made of steel because of economic efficiency, construction, and maintenance. This paper presents the effective reduction of seismic response by using Kagome damping system(SKDS) in rahmen system apartment building. The proposed system is designed to be activated by the relative displacement between the building and the stairs. It is performed nonlinear dynamic analysis to review the effects of earthquake response reduction for the 20-stories rahmen framed apartment building. In the analysis of the SKDS system, the reduction of maximum response displacement, maximum response acceleration and layer shear force are compared with the seismic design, and the result show that allowable story displacement is satisfied with Korean Building Code (KBC 2016).

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.612-621
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• 2008

Due to the various constraints such as feasible size of data payload and low transmission power, no technical specifications on the voice communication are included in the Zigbee standard. In this paper, a voice coding technique for application to the IEEE 802.15.4 standard, which is the basis of Zigbee communication, is presented. Here, both high compression and good waveform recovery are essential. To meet those requirements, a multi-stage discrete wavelet transform (DWT) block and a binary coding block consisting of two different pulse-code modulations are exploited. Theoretical analysis and simulation results in an indoor wireless channel show that the voice coder with 2-stage DWT is most appropriate from the viewpoint of compression and waveform recovery. When the line-of-sight component is dominant, the voice coding scheme has good recovery capability even in the moderate signal-to-noise power ratios. Hence, it is considered that the presented scheme will be a technical reference for the future recommendation of voice communication exploiting Zigbee.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.31-40
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• 2013

For the matter of elevator, one of the multi-use facilities for unspecified public, the JIS has re-established and reformed to apply to the environment in South Korea for the past 20 years. In the aspect of safety assurance, it was inevitable to suggest improved measures. The government, Ministry of Public Administration and Security has secured the safety by enhancing the safety management functions in the elevator inspection standards and expanding its safety device measures. Further, the international inspection standard has been introduced, which is about unifying inspection standard system into the international standard code. In March 14th 2012, the international standard (EN) has been amended and fully announced. Escalator and passenger conveyor among lift devices have several common danger factor that cause safety accident. First, the accident caused by decreased braking power of brake. Second, the accident caused by the rate difference between handrail and tread-board. Third, the accident caused by defects of contraflow preventing device or carelessness inspection. Fourth, the accident caused by wet tread-board or wet floor of platform which makes passenger slip and fall. As the improvements to prevent and reduce these negligent accidents, the inspection list to check and methods should be subdivided and applied for each accident likelihood cause for safety management enhancement and safety assurance of existing escalator and passenger conveyors. The escalators and passenger conveyors without safety devices in existence should be obliged to modify the part of the system or install additional safety device. With making these measures obligations, it requires to improve the system to be suitable for the international inspection standard and to have measures to prevent safety accidents. It also needs to arrange improvements for skid accident of tread-board by the external environment factors such as snow and rain.

• The KSFM Journal of Fluid Machinery
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• v.15 no.5
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• pp.60-66
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• 2012

One of commonly physical phenomena encountered in pump sump systems in which its significant influence to the hydraulic performance of pump system plays an important role in the field of fluid engineering, is the appearance of free surface and submerged vortices. In this paper, a study of the vortices behavior and their formative mechanism of asymmetry is considered in this paper by using numerical approach. The Reynolds-Averaged Navier-Stokes (RANS) equations and k-omega Shear Stress Transport turbulence model used to describe the properties of turbulent flows, in company with VOF multiphase model, are implemented by Fluent code with multi-block structured grid system. In the numerical simulation, the calculated elevation of air-water interface and vortex core contours are used to classify visually surface vortices as well as submerged vortices. It is shown that the free surface vortex is identified by the concavity of liquid region from the free surface and swirling flow at that own plane. To investigate the distinctive behavior of these vortices corresponding to each given flow rate at the same water level, some numerical testing of them are considered here in such a manner that the flow pattern of surface vortex are obtained similarly to the obtained results from experiment. Furthermore, the influence due to the change of grid refinement and the variation of depth of the concavity are also considered in this paper. From that, these influential factors will be implemented to design a good pump sump with higher performance in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.1
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• pp.42-48
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• 2010

In this paper, we proposed analysis performance improvement technique for T-DMB watermarking based on MBOK spread spectrum. By applying the proposed scheme to T-DMB system, it allows additional data transmission and improves spectral efficiency of data transmission through watermarking spreading code. Using MBOK spread spectrum technique, data rate improved 2m-times existing direct sequence spread spectrum. However, since hardware complexity increase as the value of m becomes large, the method should be used with optimal situation. We analyze T-DMB watermarking techniques performance with MBOK spread spectrum and averaging. As a result, we confirm DER performance of MBOK spread spectrum scheme and it is shown system performance is improved as the number of averaging increases. The results of the paper can be applied to wireless multimedia digital broadcasting system.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.55.2-56
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• 2016

The spin states of asteroids is regarded as an important clue to understand not only the physical property of an individual object but also the dynamical evolution of the of the population as a whole. Single asteroids can be broadly classified into two separate groups according to their rotational states; Principal Axis (PA) and Non-Principal Axis (NPA) rotators. To date, lightcurve observations have been carried out mostly for PA asteroids. However, discovery of NPA objects has recently been increased due to new observing techniques, and this is the reason why rotational properties of NPA rotators became an issue. As a DEEP-South pilot study for NPA, we selected two targets, 5247 Krolv (1982 UP6) and 14764 Kilauea (7072 P-L) considering their Principal Axis Rotation (PAR) code and visibility. Observations were made between Jan. and Feb. 2016 for 17 nights employing Korea Microlensing Telescope Network (KMTNet) 1.6 m telescopes installed at SSO and SAAO using DEEP-South TO (Target of Opportunity) mode. To obtain lightcurves, we conducted time-series photometry using Johnson-Cousins R-filter. Multi-band photometry was also made with BVRI filters at the same time, for taxonomy. Their preliminary lightcurves and approximate mineralogy will be presented.

• Journal of the Korean housing association
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• v.20 no.6
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• pp.111-118
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• 2009

In modern Asia major cities had same problem with lack of affordable housing for families. So they had to concentrate to the mass supply of housing and made some physical counter effects like high density of cities, limitation of parking space. Also people who lived in those cities could suffer from broken traditional community culture. To rebuild traditional community and increase land usage, Block housing is suggested as a new kind of multi-family housing for old town redevelopment. Now some governments are trying to make urban code to give some initiative for new block housing development in old city blocks. They expect this new housing type can help to solve serious problems like lack of parking area, green space and context of block. Also they hope that block housing development can help to increase safety of town and reduce cost of development. The purpose of this study is to review the establishment and development process of Block Housing and to confirm the aspect which has been changed with urban organization together. Also this study tried to find out the intentional characteristics of similarities and differences with comparison of Korea and Japan. And as a result we could find critical physical viewpoint, and provide considerations for future study and plan. Several cases of block housing in Korea and Japan were reviewed for comparative study and Post Occupancy Evaluation (POE) survey was examined to find satisfaction factors and problems which were expected to improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.209-214
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• 2003

Multi-mode coding method is a reliable DC-suppression method. There are two ways to improve the DC-suppression performance. One is improving scrambler's performance, and the other is improving selection criteria. The latter uses the MRDS(minimum running digital sum) criterion. It is easy to calculate, but its performance goes down when the length of codeword is getting longer. The MSW(mean squared weight) criterion that is known as the best so far regardless of the length of codeword has the high complexity. In this paper, we present the new selection criteria, MPRDS(minimum peak RDS) and A BSRDS(absolute RDS). Their performance are close to the MSW, implementation is simple. And also we present the SC(sign change) that has a subsidiary role with the original selection criteria and improve the capacity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.62-70
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• 2010

In this paper, we evaluate the performance of various diversity techniques which can contribute to provide efficient multimedia broadcasting services via hybrid/integrated satellite and terrestrial network. Space-time coding (STC) can achieve the diversity gain in a multi-path environment without additional bandwidth requirement. Recent study results reported that satellite systems can achieve high diversity gains by appropriate utilization of STC and/or forward error correction schemes. Based on these previous study results, we present various cooperative diversity techniques by combining STC and rate compatible turbo codes in order to realize the transmit diversity for the mobile satellite system. The satellite and several terrestrial repeaters operate in unison to send the encoded signals, so that receiver may realize diversity gain. The results demonstrated in this paper can be utilized in future system implementation.

• Journal of Digital Contents Society
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• v.15 no.5
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• pp.587-594
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• 2014

Owing to supply of smart phones and the diffusion of SNS, the number of peoples who are living, linked with us, is incomparably more than in the past. The continuous communication is essential in maintaining good relationship, so peoples have no choice but to seek for most efficient communication method in order to maintain good relationship. This thesis intended to advise how to construct next generation immersive multi-media system, using augmented reality and MPEG-V that have come to the fore recently. In addition, the SNS platform service of new type was suggested in this thesis, in connection with the pairing service. Now, we can create a town in a specific space like the real world, if we utilize the augmented reality that became possible by SNS service and we can talk and exchange informations in that space. This system would provide various services peoples wish to have, interlocking experiences through five senses like sense of vision, sense of hearing, sense of touch and etc..