• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.1-7
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• 2011

In this paper, CDD(Cyclic Delay Diversity)-DF(Decode-and-Forward)-Relay scheme is proposed for MC-CDMA(Multicarrier-Code Division Multiple Access) systems over multipath Rayleigh fading channels. The advantages of general DF schemes come at the expense of the spectral efficiency since the source and all the relays must transmit on orthogonal channels. In order to mitigate this disadvantage of general DF schemes, we have applied CDD techniques to each relays so that all the relays can transmit on single channel. It means that all R-D link channels can be considered as a single channel which is widely delay spread. Namely, it causes the increasing the number of multipath so that the frequency diversity gain can be achieved in MC-CDMA systems. By simulations, we have compared proposed one with general DF scheme. Therefore, it is confirmed that the proposed one can be a possible solution to achieve cooperative diversity gain without a reduction of spectral efficiency.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.286-294
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• 2011

Cable modems typically are implemented by a forward error correction(FEC) scheme. The ITU-T Recommendation J-38 Annex B specifies using 64- and 256- quadrature amplitude modulation (QAM) and extended RS coding scheme. In implementing the cable modem, there are some problems to fabricate and fitting on FPGA chip. First, many clocks are needed in implementing cable modem because of different code rate and different modulation types. To reduce the number of clocks, we use the two memories, which are different clock speed for reading and writing data. Second, this system lost the bit-synchronization and frame-synchronization in decoder, the system recognize that all data is error. This paper solves the problems by using simple 5-stage registers and unique sync-word. Based on solutions for about problems, the cable modem is fabricated on FPGA chip name as Vertex II pro xc2vp30-5 by Xilinx, and we confirmed the effectiveness of the results.

• Journal of Communications and Networks
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• v.10 no.4
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• pp.412-421
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• 2008

We observe simultaneous transmission of relay stations (RSs) allowed in current IEEE 802.16j draft standard for multi-hop relay networks may involve severe interference among the RSs, hence leading to throughput degradation. Allowing only 1/3 of the RSs to simultaneously transmit instead of 1/2 RSs as in the current draft standard reduces the interference but results in reduced throughput. To remedy this problem, we devise schemes to incorporate network coding at link-layer level (decode-and-forward) into the simultaneous transmission of RSs. Data movement is rearranged to maximize coding gain. Formula is derived to dictate exact movement of packets traveling between base station (BS) and mobile stations (MSs) via intermediate RSs. The frame structure in the current IEEE 802.16j draft standard does not allow broadcast needed for network coding. We devise a new frame structure which supports the broadcast. A new R-MAP (pointers to the burst data) is introduced to implement the broadcast. Since our new frame structure is used only for BS to RS or RS to RS communication, our schemes retain backward compatibility with legacy MSs based on IEEE 802.16e standard. Simulation based on simple configuration of RSs shows considerable improvement in terms of system throughput and round trip delay. For a 4-hop relay network with 1 BS and 4 RSs with symmetric traffic in uplink (UL) and downlink (DL), throughput is improved by 49% in DL and by 84% in UL traffic compared with IEEE 802.16j draft standard under the assumption that omni-directional antennae are used in BS and RSs.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.20-25
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• 2011

The authors have proposed novel TDD-CDMA systems with Pre-Rake transmit diversity schemes (system 1 and system 2) using multiple transmit antennas in [2] and have also evaluated the system performance through the theoretical analysis and computer simulation. However, the performance of system 2 which transmit a signal using all antennas has not been evaluated for multi-user environment. Therefore in this paper, we analyze the performance of system 2 for multi-user environment and compare the performance with that of the already proposed system 1 which chooses only one antenna. From the numerical results, it is found that system 2 outperforms system 1 as the number of users increases while system 1 outperforms system 2 at a small number of users. Therefore in order to achieve the best system performance, the Pre-Rake transmit diversity type should be selected at the base station according to the number of users.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.65-74
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• 2012

The QoS guarantee for the forward link in satellite communication networks is very important because there are a variety of packets with multiplexing. Especially, the packets are processed depending on the available bandwidth in satellite network changing the wireless channel state in accordance with weather condition. The DVB-S2 increases the transmission efficiency by applying the adaptive coding and modulation (ACM) techniques as a countermeasure of rain attenuations. However, the channel estimation algorithm is required to support the ACM techniques that select the MODCOD values depending on the feedback data transmitted by RCSTs(Return Channel via Satellite Terminal) because satellite communication networks have a long propagation delay. In this paper, we proposed the channel estimation algorithm using rain attenuation values and reference data and the packet scheduling scheme to support the QoS and fairness. As a result of performance evaluation, we showed that proposed algorithm exactly predicts the channel conditions and supports bandwidth fairness to the individual RCST and guarantees QoS for user traffics.

• Safety and Health at Work
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• v.8 no.4
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• pp.398-401
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• 2017

Background: Organizational ostracism is defined as a violation of norms that we are suggested to acknowledge at the workplace. It results in the exclusion of one person or multiple persons, and causes damage to our innate need to belong. This kind of behaviorism can be engaged through a hierarchical or nonhierarchical relationship. Three elements interact in the framework of organizational ostracism: the actor, the target, and the institution. Our aim was to describe the different factors interacting with every element in order to produce recommendations targeting to prevent the occurrence of such behaviorism in an institution and to help targets of such a violence in order to handle this situation and go forward. As psychological impact of ostracism has frequently been studied in the literature, we focused on its impact on professional tasks. Methods: We performed a questionnaire-based study about organizational ostracism. This questionnaire was established through an online platform (https://www.sondageonline.com) and made available through the following link: https://goo.gl/forms/KrkVXe3bMEc79cau2. A keyword was sent to all participants. We created a 23-interrogation questionnaire with open and short questions. Nonwritten consent was obtained from all participants. Results: The actor of ostracism engaged in ostracism, in most of the cases, with other persons without a real purpose. The actor of ostracism had an antecedent of problematic relationship at work in 82.9% of the cases. Of the participants, 58.5% were of the view that ostracism aimed to cause hurt and isolate them. Professional isolation was observed in 58.5% of the cases; 51.2% of the participants tried to improve their work potential and explained their reaction by an intrinsic motivation. The organization atmosphere was judged to be bad in most of the cases. Conclusion: Our study showed that ostracism was mainly observed in public practice.

• Journal of the Korea Fashion and Costume Design Association
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• v.21 no.1
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• pp.131-148
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• 2019

In this study, the purpose of the research is to present a cooperative convergence education Capstone design operational model that can promote community relations by spreading excellent practices through governmental, academic, and civil cooperation, ultimately contributing to the development of systematic plans among cooperative groups for successful promotion, and the production high effects in the fashion sector. The case study presented a new model that combines convergence in interdisciplinary studies, focusing on the case study of the "Fashion Capstone Design" textbook. The characteristics of the proposed model suggested three types of convergence- the convergence of government, academia and private cooperation, and the convergence of academic and civil organizations, depending on their role. The proposed educational model has the advantage of complementing and dealing with the difficulties presented by interdisciplinary education. It also has the effect of activating community linkages with colleges in the community. In addition, the effectiveness of community colleges and community links can be optimized. Through the example of this study, we look forward to being used as a references for a variety of cooperative convergence education capstone design projects.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.456-465
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• 2021

A recent report cited environmental issues, including climate change, as the most likely threat to Earth in the 2020s. Therefore, it is necessary to recognize that environmental problems today are not just problems of any particular region or country, but also problems of the future, and problems of the present day in which we live. Various interests and research on environmental issues have been conducted within Christianity based on the Christian worldview based on creation, degradation, and restraint. This interest began mainly in the Catholic camp in the early days, but gradually efforts have been made to link global care to Christian responsibility in evangelical Christian camps, including the World Council of Churches (WCC). At a time when interest in earth care is growing, the study suggested as follows for the Christian community: First, it is necessary to change from environmental protection and ecological preservation to life theology. Second, there is a need for a change of understanding of ecology that looks at nature. Third, at the Christian level, there should be a genuine recovery movement that is differentiated from secular environmentalism. Fourth, the church should be able to realize a society that can realize a true community with the world of creation while looking forward to the kingdom of God.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.184-191
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• 2022

Unity Painting is a concept that the researcher put forward to locate his own creative style in his creation. Unity Painting, with a clue of reflecting the characteristics of contemporary oriental visual culture, combines the contemporary painting features of a variety of western painting languages. It aims to link the painting system formed in the context of oriental culture with the world's contemporary art and try to present a new contemporary painting with oriental genes. According to the Chinese literature, the researcher sorted out the five main colors (五正色), ten colors for Heavenly Stems (十天干色彩), five intermediate colors (五间色), and five colors as the expression of the Chi of Thriving and Fading and the Chi of Birth and Death, and deduced the summary and stipulation of the color of yin-yang and five elements under the concept of Unity Painting. Based on this, the researcher drew the color-phase and its variation stipulation diagram of ten colors for Heavenly Stems, the orientation of Heavenly Stems (天干方位), color-phase variation diagram (色相变化图), as well as the stipulation system diagram of the five elements (五行), Heavenly Stems and Earthly Branches (干支), energy, time and colors. Through the research and collation of the literature, the researcher took the stipulated five elements color (五行色彩) as the basis of the color concept of creation to complete the work. This paper discusses how to find the starting point of contemporary art creation in the context of traditional oriental culture, sorts out the practical creation logic, and provides ideas for subsequent researchers, with a view to better establishing the identity of the creator and providing research significance and value in the context of the study of oriental art.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.45-55
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• 2023

This study conducted aeromechanics modeling and structural load analyses of Tilt Rotor Aeroacoustic Model (TRAM), a 25% scaled V-22 tiltrotor model used in wind tunnel tests. A rotorcraft comprehensive analysis code, CAMRAD II, was used. Analysis results of this study in low-speed forward flights were compared with DNW test and previous analysis results. Blade flap bending moments were in good agreement with measured data. Mean values and oscillatory loads for lead-lag bending and torsion moments were slightly different from measured data. However, when mean values were removed, results of structural loads for one rotor revolution were moderately compared with wind tunnel tests and previous analyses. Total forces and half peak-to-peak forces of the pitch link reasonably well matched with previous analysis results and measured data. Finally, harmonic magnitudes of blade structural loads were investigated.