• Wind and Structures
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• 제26권1호
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• pp.11-24
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• 2018

Full-scale measurements of wind action on the open roof structure of the WuXi grand theater, which is composed of eight large-span free-form leaf-shaped space trusses with the largest span of 76.79 m, were conducted during the passage of Typhoons HaiKui and SuLi. The wind pressure field data were continuously and simultaneously monitored using a wind pressure monitoring system installed on the roof structure during the typhoons. A detailed analysis of the field data was performed to investigate the characteristics of the fluctuating wind pressure on the open roof, such as the wind pressure spectrum, spatial correlation coefficients, peak wind pressures and non-Gaussian wind pressure characteristics, under typhoon conditions. Three classical methods were used to calculate the peak factors of the wind pressure on the open roof, and the suggested design method and peak factors were given. The non-Gaussianity of the wind pressure was discussed in terms of the third and fourth statistical moments of the measured wind pressure, and the corresponding indication of the non-Gaussianity on the open roof was proposed. The result shows that there were large pulses in the time-histories of the measured wind pressure on Roof A2 in the field. The spatial correlation of the wind pressures on roof A2 between the upper surface and lower surface is very weak. When the skewness is larger than 0.3 and the kurtosis is larger than 3.7, the wind pressure time series on roof A2 can be taken as a non-Gaussian distribution, and the other series can be taken as a Gaussian distribution.

• 한국소음진동공학회논문집
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• 제19권4호
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• pp.355-362
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• 2009

Sound source localization method based on the time delay of arrival(TDOA) is applied to many research fields such as a robot auditory system, teleconferencing and so on. When multi-microphones are utilized to localize the source in 3 dimensional space, the conventional localization methods based on TDOA decide the actual source position using the TDOAs from all microphone arrays and the detection measure, which represents the errors between the actual source position and the estimated ones. Performance of these methods usually depends on the number of microphones because it determines the resolution of an estimated position. In this paper, we proposed the localization method using spatially mapped GCC functions. The proposed method does not use just TDOA for localization such as previous ones but it uses spatially mapped GCC functions which is the cross correlation function mapped by an appropriate mapping function over the spatial coordinate. A number of the spatially mapped GCC functions are summed to a single function over the global coordinate and then the actual source position is determined based on the summed GCC function. Performance of the proposed method for the noise effect and estimation resolution is verified with the real environmental experiment. The mean value of estimation error of the proposed method is much smaller than the one based on the conventional ones and the percentage of correct estimation is improved by 30% when the error bound is ${\pm}20^{\circ}$.

• 가족자원경영과 정책
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• 제18권1호
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• pp.1-28
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• 2014

The purpose of this study is to suggest how the first birthday rite, a practice in Korean culture, has changed over the time. A survey of 250 mothers was undertaken from October 11th to November 6th, 2012. The research questions asked in this study are as follows. What general and expert views are held about the first birthday rite? What type of awareness and knowledge do mothers have about the first birthday rite? Is there any correlation between mothers' awareness and knowledge about first birthday rite? What is the importance of the components of the baby's first birthday rite and the importance of choosing first birthday rite goods? The data were analyzed using SPSS 17.0. Frequency, F-test, correlation were also employed. The results of this study are as follows: The first birthday rite shows a clear link to socializing. It is a family event, but is also seen as an opportunity to enhance relationships with relatives, colleagues, and friends. A banquet hall is chosen as preferred first birthday rite location, and participants are served a meal and receive gifts. The banquet information on first birthday rites was initially collected from the internet, blog cafes, and an experienced. However, it has become gradually more common to hire a consultant to organize the first birthday rite. Awareness of the first birthday rite is high, but knowledge is relatively low. In addition, there is a positive relationship between awareness and knowledge about the first birthday rite. When mothers are preparing for their baby's first birthday, they consider food for the guests' banquet, space and time. Finally, individual positive relationships were found between choosing first birthday rite goods and employee services, contract pricing for goods, and food for guests.

• 한국조경학회지
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• 제40권2호
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• pp.15-23
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• 2012

본 연구는 우리나라 초고층 건축물 15개소를 선정하여 토지피복특성과 변화경향을 살펴보고자 하였다. 초고층 건축물 외부공간은 건폐지와 비건폐포장지가 차지하는 비중이 평균 79.7%로 높았으며, 상대적으로 녹지 및 수면이 차지하는 비중은 낮았다. 또한 대부분 지역은 지하개발이 이루어져 조사대상지 평균 생태면적률은 15.90%로 매우 낮은 수준이었다. 준공시기에 따른 피복유형 현황분석 결과, 시간이 지나면서 건폐율이 낮아지고 있었으며, 생태면적률이 증가하고 있었다. 반면, 가장 높은 비중을 차지하고 있는 비건폐포장지의 비율은 통계적으로 차이가 없었다. 초고층 건축물 외부공간의 생태적 기능 개선을 위해서는 포장공간을 줄이는 방안을 강구하는 것이 효과적인 것으로 판단된다.

• 대한인간공학회지
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• 제34권6호
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• pp.609-622
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• 2015

Objective: This study aims to investigate the correlation between office and work environment satisfaction levels and workers' musculoskeletal symptoms by conducting surveys asking office workers to state their musculoskeletal symptoms and office and work environment satisfaction levels. Background: The increased number of office workers and their indoor work hours using computers have led to new understandings of the importance of office environment including its temperature, humidity, noise levels, lighting and quality of air, and work environment including monitor arrangement, space arrangement and the functions of desks and chairs. Method: Specific details on office work, office environment satisfaction levels, work environment satisfaction levels, musculoskeletal symptoms, absence from work and treatment due to musculoskeletal related symptoms were analyzed based on the survey answers given by 397 office workers who were the subjects of this research. Results: Office workers showed different characteristics of musculoskeletal symptoms depending on their gender, age, work experience, office hours, break time and time spent on computers. Also, differences in symptoms were found for workers'with different satisfaction levels for office environment (temperature, humidity, noise levels, quality of air, lighting) and work environment (location of monitors, area and display of office space, chairs and desks). ANOVA shows the differences between groups of subjects classified by the experience of work-absences and treatments or pain complaints. Conclusion and Application: Relationship between workers' satisfaction levels with the office and work environment and their musculoskeletal symptoms is expected to be served as essential data for systematic management of the workplace.

• Journal of Astronomy and Space Sciences
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• 제31권2호
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• pp.145-148
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• 2014

There was a research on the prolongation of solar cycle 23 by the solar cyclic variation of solar, interplanetary geomagnetic parameters by Oh & Kim (2013). They also suggested that the sunspot number cannot typically explain the variation of total solar irradiance any more. Instead of the sunspot number, a new index is introduced to explain the degree of solar activity. We have analyzed the frequency of sunspot appearance, the length of solar cycle, and the rise time to a solar maximum as the characteristics of solar cycle. Then, we have examined the predictability of solar activity by the characteristics of preceding solar cycle. We have also investigated the hemispheric variation of flare index for the periods that the leading sunspot has the same magnetic polarity. As a result, it was found that there was a good correlation between the length of preceding solar cycle and spotless days. When the length of preceding solar cycle gets longer, the spotless days increase. It is also shown that the shorter rise time to a solar maximum is highly correlated with the increase of sunspots at a solar maximum. Therefore, the appearance frequency of spotless days and the length of solar cycle are more significant than the general sunspot number as an index of declining solar activity. Additionally, the activity of flares leads in the northern hemisphere and is stronger in the hemisphere with leading sunspots in positive polarity than in the hemisphere with leading sunspots in negative polarity. This result suggests that it is necessary to analyze the magnetic polarity's effect on the flares and to interpret the period from the solar maximum to solar maximum as the definition of solar cycle.

• Journal of Astronomy and Space Sciences
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• 제30권2호
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• pp.79-82
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• 2013

We present the Hilbert-Huang transform (HHT) analysis on the quasi-periodic modulation of SMC X-1. SMC X-1, consisting of a neutron star and a massive companion, exhibits superorbital modulation with a period varying between ~40 d and ~65 d. We applied the HHT on the light curve observed by the All-Sky Monitor onboard Rossi X-ray Timing Explorer (RXTE) to obtain the instantaneous frequency of the superorbital modulation of SMC X-1. The resultant Hilbert spectrum is consistent with the dynamic power spectrum while it shows more detailed information in both the time and frequency domains. According to the instantaneous frequency, we found a correlation between the superorbital period and the modulation amplitude. Combining the spectral observation made by the Proportional Counter Array onboard RXTE and the superorbital phase derived in the HHT, we performed a superorbital phase-resolved spectral analysis of SMC X-1. An analysis of the spectral parameters versus the orbital phase for different superorbital states revealed that the diversity of $n_H$ has an orbital dependence. Furthermore, we obtained the variation in the eclipse profiles by folding the All Sky Monitor light curve with orbital period for different superorbital states. A dip feature, similar to the pre-eclipse dip of Her X-1, can be observed only in the superorbital ascending and descending states, while the width is anti-correlated with the X-ray flux.

• 한국해양학회지
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• 제26권2호
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• pp.155-168
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• 1991

만경, 동진강 하구 표영 생태계에서 일차생산자의 군집 구조와 분포 양상 그리고 이들과 무생물 환경과의 관계를 파악하기 위하여 1989년 10월부터 1990년 7월까지 5회 에 걸쳐 시료를 채집, 분석 하였다. 그 결과 식물플랑크톤은 159종이 동정되었으며 규 조류가 70.4%로 가장 우세하였다. 생태특성으로는 연안종이 52%로 가장 우세하였고 담 수종 18%, 외상양 12% 순으로 나타나 담수와 외양의 해수에 의해 영향을 받는 하구역 의 특성이 뚜렷하다. 식물플랑크톤의 종 조성은 염분 변화에 좌우되는 것으로 사료된 다. 연구해역에서 일차생산자의 현존량은 시, 공간에 따라 크게 변하는데 투명도와 밀 접한 관계가 것으로 보이며 서해의 다른 해역에 비해 높은 수준이다. 종 다양성 지수 역시, 시, 공간적으로 변화가 컸으며 10월에 최대, 5월에 최소치를 보였다. 연구해역 은 가을과 겨울에는 외양수에 의한 영향으로, 봄과 여름에는 강으로부터 유입되는 담 수에 의한 영향으로 크게 두 개의 해역으로 구분되어 진다.

• 한국통신학회논문지
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• 제29권2C호
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• pp.247-254
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• 2004

본 논문에서는 송신 다이버시티 기술과 송신 빔형성 기술을 모두 사용하는 코드 분할 다중 접속(CDMA) 시스템을 위한 새로운 시공간 신호 처리 구조를 소개한다. 소개된 구조는 복소 가우시안 레일리 페이딩 채널에서 송신다이버시티 효과에 의해 다이버시티 이득을 얻을 뿐만 아니라, 송신 빔형성 효과에 의해 신호대 잡음비(SNR)이득을 얻는다. 본 논문에서는 송신 다이버시티, 송신 빔형성, 그리고 송신 다이버시티와 송신 빔형성 기술을 결합한 구조에 대해 천천히 변하는 레일리 주파수 비선택적 페이딩 채널 환경에서 비트 오류율(BER) 해석을 하고 몬테카를로 모의 실험을 통해 해석적인 결과가 모의 실험 결과와 잘 일치한다는 것을 보여준다. 또한 원거리 안테나간 채널이 서로 독립적일 때 해석적인 결과를 통해 소개된 구조가 목표 BER $10^{-6}$ 을 달성하는데 있어 가장 낮은 $E_{b/}$ $N_{0}$ 를 달성할 수 있음을 보인다. 원거리 안테나간 채널이 서로 상관되어 있을 때 해석적인 결과와 모의 실험 결과를 통해 결합된 구조가 채널 상관도의 변화에 강인하다는 것을 보여준다.다.

• 한국전자파학회논문지
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• 제26권1호
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• pp.94-100
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• 2015

태양흑점폭발로 인해 방출되는 코로나 물질은 지자기 교란을 일으킨다. 대규모 지자기 교란으로 인한 유도전류는 변압기 손상을 일으킬 수 있다. 이러한 유도전류를 산출하기 위해 먼저 유도전기장을 산출해야 한다. 푸리에 변환 방법을 적용한 유도전기장 산출방법은 정확도가 높으나, 1일 24시간 동안의 관측 데이터가 필요하다. 반면, 적분 공식을 적용한 유도전기장 산출방법은 실시간 데이터로 산출이 가능하나, 정확도 확인이 요구된다. 이 논문에서 적분 구간을 조정하여 푸리에 변환 방법의 결과값과 오차를 줄이고자 하였다. 그 결과, 적분 공식을 적용한 유도전기장 예상값은 푸리에 변환방법의 예상값과 상관성이 높았으며, 적분 공식으로 산출한 유도전류 예상값은 유도전류 관측값과 시간 동기 및 방향이 일치하고, 그 크기가 오차 범위 1 A 이하에서 92 % 이상 일치함을 확인하였다.