• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.244-249
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• 2015

High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.227-229
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• 1997

A new phased-array quadrature RF coil for one or two RF acquisition channels is developed for spine MR imaging. Quadrature RF coils for MRI have been useful to improve the signal-to-noise ratio (SNR) by $"\sqrt{2}"$ using two orthogonal RF coils in combination [1]. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of RF coil elements with a reduced size and coverage for each element. Two new schemes are proposed for the new phased-array quadrature RF coil as follows : (1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive- only mode. It has been tested through phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.5
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• pp.93-103
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• 2000

This research is to propose a rational criterion of the selection and the management f the roadside trees, and to establish the planting design and system with the objective of improving the roadside environment. All of the roadside trees in each objective courses in Kangnung, and the soil disposition, hardness of the soil in the planting areas have been investigated. Also, we have surveyed the kinds of the trees which kandgnung inhabitants want. The conclusion is as follows Most of roadsides have trees, but they need the introduction of shrubs or ground covering plants according to the locations and the environmental conditions. We have selected nineteen species in regard to the roadside tree criterion and the growing conditions living in Kangnung. It is desirable that we make banding style planting space between each roadside tree to improve the low ratio of green coverage. We have found out that Ligustrum obtusifolium, Buxus micropnylla, Euonymus japonica, Rhododendron schlippenbachii, Phyllostachys nigro and Rosa rugosa, ect. are suitable. In order to soften and weaken the rigidity of the hard substances on a paved roadside, the climbers such as the perennial herbaceous flowering and hedera rhombea should be preferred rather than annual herbaceous flowering because of curtailment of expenditure. To posses a systematical greenery frame in kangnung, we have planned a planting design system that would expand the greenery space every year. Moreover, we have to make a plan to overcome space restrictions. We have established a flexible plan considering the roadside conditions and the improved standard planting methods with an ultimate aim to create a special roadside view.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1C
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• pp.1-7
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• 2011

Recently, multi-hop relay transmission has drawn much attention owing to its advantage of coverage extension at low power consumption. In this paper, we derive a performance bound of multi-hop communication systems with multiple amplify-and-forward relays when the optimal path is selected. The bound is derived in generalized Nakagami fading channels with different parameters for each hop by applying the geometric mean bound to the path signal-to-noise ratio (SNR) and obtaining the moment generation function of the bound. It is shown that the bound based on the geometric mean is closer to the actual performance of optimal path selection when the fading effect is small.

• ETRI Journal
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• v.42 no.3
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• pp.351-365
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• 2020

Directional sensor networks (DSNs) can significantly improve the performance of a network by employing energy efficient communication protocols. Neighbor discovery is a vital part of medium access control (MAC) and routing protocol, which influences the establishment of communication between neighboring nodes. Neighbor discovery is a challenging task in DSNs due to the limited coverage provided by directional antennas. Furthermore, in these networks, communication can only take place when the beams of the directional antennas are pointed toward each other. In this article, we propose a novel multiple token-based neighbor discovery (MuND) protocol, in which multiple tokens are transmitted based on an area exploration algorithm. The performance of the protocol is evaluated using the Cooja simulator. The simulation results reveal that the proposed MuND protocol achieves lower neighbor discovery latency, with a 100% neighbor discovery ratio, and has a relatively low communication overhead and low energy consumption.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.1-7
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• 2007

In WCDMA systems the down-link power allocation directly affects the cell deployment capacity, coverage, and system performances. Down-link power should be controlled at minimum but still satisfy the mobile stations' required signal to noise ratio. This paper mathematically proves that the down-link power allocation depends on the number of active mobile stations accessed to the base station. Therefore this paper proposes the dynamic down-link power allocation should be implemented to the WCDMA cellular systems.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1776-1783
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• 2002

A population segregating for the naked neck (Na) gene was used to evaluate its effect on fast growing broilers at heat stress. An experimental stock comparable to those of modern broilers was established by backcrossing to colour synthetic male and female lines. Matings between heterozygous (Na/na) males and females produced normally feathered (na/na), heterozygous (Na/na) and homozygous (Na/Na) chicks for the present study. Day old to seven week old coloured broilers of three genotypes viz. normally feathered (na/na), heterozygous naked neck (Na/na) and homozygous naked neck (Na/Na) were compared for heat dissipation, growth performance, body conformation traits, blood biochemical parameters and carcass traits in tropical climate. In hot climate, naked neck broilers had significantly less body temperature and better heat dissipation capabilities as compared to normal broilers. The naked neck broilers had significantly higher body weight and better feed conversion ratio than na/na broilers. The Na/Na or Na/na broilers exhibited higher giblet yield, blood loss and lower feather mass compared to na/na broilers. The results indicated that the reduction in feather coverage in Na/Na and Na/na broilers facilitates better heat dissipation with lower body temperature, more body weight gain, better FCR and carcass traits compared to normal broilers.

• Journal of Korean Academy of Nursing Administration
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• v.17 no.2
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• pp.147-157
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• 2011

Purpose: This study was done to investigate factors affecting perceived financial burden of medical expenditures. Method: The participants were 2,024 inpatients who were enrolled in a survey on the benefit coverage rate of the National Health Insurance in 2006. The collected data were analyzed using t-test, ANOVA-test, Mann-Whitney-test, Kruskal-Wallis-test, Chi-square test and logistic regression. Results: The crucial factors for perceived financial burden were age, job, equivalence scale, ratio of annual family income vs medical expenditure, and private health insurance. Perceived financial burden was higher for people who were older, who were unemployed, whose medical expenditures were high compared to annual family income, whose index of family equalization was low and for those who had no private health insurance. Conclusion: The results of the study indicate a demand for system reform that will enable management of no-pay hospital bills in the National Health Insurance to decrease the medical expense of people in the low-income bracket.

• KIEAE Journal
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• v.13 no.1
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• pp.101-108
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• 2013

The purpose of this research was to analyze the correlation of residential satisfaction and the size of housing unit in apartment housing through the case study of 1,619 samples of 36 housing estates. The contents of this research consisted of two main parts. The first part was to identify the differences of residential satisfaction of dwellers, based on the size of housing unit, in apartment housing. The second part was to analyze the characteristics of residential environment, which might have an influence on the differences of residential satisfaction. the findings of this study were that the residential satisfaction of dwellers was proportional to the size of housing unit except $39m^2$ under housing unit, and the size of housing unit was not proportional to the residential satisfaction of outdoor openness exactly, but the size of housing unit was proportional to increase of the distance between building and building, and decrease of the building surface coverage ratio to outdoor area. This research will contribute to the establishment of the site planning methods which increase residential satisfaction in apartment housing, while promoting the quality of residential environment in Korea.

• Asia-Pacific Journal of Business
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• v.2 no.1
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• pp.49-73
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• 2011

With the market evaluation of economic globalization exchanges between different cultures, cultural trade has been developing at an accelerated speed, and also playing an important role in East Asian intra-regional trade. In this research the author used gravity trade model to explain the causal relationship between dependent variable trade flows and several independent variables applying with five categories cultural goods which classified in HS codes. Firstly for cultural heritage trade flow, the results indicated that economic masses of bilateral countries have no significant influences on it; GDP per capita of host country and adjacency factor with partner country have significant negative influences on it; Internet coverage ratio has improved cultural heritages exchanges in East Asian regions. Secondly for printed matter cultural goods trade flow, the distance factor has significant negative influence but common language has significant positive influence on it. Thirdly for recorded media cultural goods, only economic masses and GDP per capita of bilateral countries can improved their trade flows. Fourthly for visual arts cultural products trade flows, almost all variables we tested have significant influences on it. Fifthly for cinema photography cultural goods trade flow, the influenced factor are same with cultural heritage products except they have strong positive interaction relationship with economic masses and common language. At last, the paper figured out some important and potential sectors for cultural goods trade in East Asia and gave some suggestions to government and cultural goods product enterprises.