• 한국항행학회논문지
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• 제16권1호
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• pp.96-102
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• 2012

모바일 인터넷 시스템의 목표는 고속 데이터 율, 낮은 지연 그리고 유연한 대역폭 진화를 제공할 수 있는 최적화된 패킷 무선접속기술을 제공하는 것이다. 따라서 연속적인 이동성과 서비스 품질 그리고 최소지연을 갖는 패킷 스위치 트래픽 목표를 제공하는 LTE 네트워크 구조가 설계되었다. LTE 시스템에서의 중요한 요구조건은 셀 경계에서의 BER 성능과 데이터 처리율을 개선하는 것이다. 이것은 통신 지역에서 지리적 영역과 데이터 처리율 측면에서 서비스의 일관성을 제공한다. 하지만 셀룰러 시스템에서 셀의 중앙과 경계지역 사용자 사이의 SINR 차이는 20 [dB] 정도가 된다. 이러한 차이는 통신 영역이 제한된 셀룰러 시스템에서 더욱 크다. 이 현상은 셀 중앙의 사용자에 비하여 셀 경계의 사용자에게 대단히 낮은 데이터 처리율 유발하고 큰 QoS 차이를 발생시킨다. 본 논문에서 인접 셀 간섭을 감소하기 위한 분석적인 방법을 제시하고 모바일 인터넷 환경에서 OFDM 시스템 파라미터에 따른 SIR 및 BER 성능을 보였다.

• 지역연구
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• 제36권3호
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• pp.3-16
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• 2020

도시 내 공간적 불평등은 꾸준한 관심을 받고 있는 연구주제다. 그러나 공간적 불평등이 주민에게 미치는 세부적인 영향과 공간적 불평등이 지속되고 재생산되는 방식에 대한 실증연구는 제한적이다. 본 연구는 공간적 수준에서의 박탈을 나타내는 개념인 지역박탈이 주민의 계층상승 가능성에 대한 인식에 미치는 영향을 확인하고자 하였다. 2015년 서울서베이 자료를 순서형 로지스틱 다층모형을 활용하여 분석한 결과, 지역박탈 수준이 높은 지역에 거주하는 주민일수록 자신의 계층상승 가능성을 부정적으로 인식하는 것으로 나타났다. 본 연구결과는 지역박탈이 주민의 계층상승에 대한 믿음을 저해함으로써 삶의 만족도와 기회 실현을 저해하는 것은 물론 지역 격차가 지속되는 데에 영향을 미칠 수 있음을 시사한다. 이와 같은 분석결과는 공간적 불평등을 해소하기 위한 도시정책에 함의를 제공할 수 있을 것으로 기대된다.

• 보건행정학회지
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• 제16권4호
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• pp.24-47
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• 2006

Based on the findings of a study focused on medical institutions(Fama & French, 2002), this study determined possible causality between determinants of capital structure and liability level, while estimating targeted debt ratio. Moreover, it also examined hypotheses about the adjustment of targeted debt ratio and the of fundraising patterns, so that it verified the relative priority of trade-off theory and pecking order theory. First, profitability had positive(+) relationships with liability level, while investment opportunities had negative(-) relationships with liability level. This finding supported pecking order theory, and non-liability tax shield effects had negative(-) relationships with liability level as estimated in both trade-off theory and pecking order theory. Next, this study verified trade-off and pecking order theory at once by means of regression analysis about the variation of liability level in associations with disparity from targeted debt ratio and short-term fluctuation of profit and investment. As a result, it was noted that liability level became mean-reversed to targeted liability ratio but slowly, SO it was difficult to assert that such mean reverse may support trade-off theory. However, the finding that most of short-term fluctuations of profit and investment are absorbed into liabilities supported pecking order theory. On the other hand, it was found that the larger scale of medical institutions is more supportive of pecking order theory in the associations between liability level and profitability and the fundraising patterns than trade-off theory.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1999년도 제13회 학술강연논문집
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• pp.27-27
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• 1999

To illustrate the global variation of the droplet mean diameters and the turbulent flow characteristics in counterflowing internal mixing pneumatic nozzle, the experimental measurements at five axial downstream locations(i.e., at Z=30, 50, 80, 120, and 170mm) were made using a PDPA(Phase Doppler Particle Analyzer) under the different air injection pressures ranging from 40 ㎪ to 120 ㎪. A nozzle with axi-symmetric tangential-drilled four holes at an angle of 15$^{\circ}$ has been designed and manufactured. The distributions of velocities, turbulence intensities, turbulence kinetic energy, turbulent correlation coefficients, spray angle, droplet mean diameters, volume flux, number density are quantitatively analyzed. It is possible to discern the effects of increasing air pressure. It indicates that the strong axial momentum in spite of more or less disparity between the velocity components means more reluctant to disperse radially, and that axial fluctuating velocities are substantially higher than those of radial and tangential ones, suggesting that the disintegration process is enhanced under higher air assist. The larger droplets are detected in the spray centerline at the near stations and smaller ones are generated due to further subsequent breakup at farther axial locations are attributed to the internal mixing type nozzle characteristics. Despite of the strong axial momentum, the poor atomization around the centre close to the nozzle exit is attributed to the lower rates of spherical particles which are not subject to instantaneous breakup. As it goes downstream, however, substantial increases in SMD(Sauter Mean Diameter) from the central part toward spray periphery are understandable because the droplet relative velocity is too low to bring about any subsequent disintegration.

• 한국환경과학회지
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• 제25권10호
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• pp.1369-1379
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• 2016

This research assessed the disparity in anion generation according to the vertical structure of a Zelkova Serrata tree for the purpose of creating a pleasant and green city environment. Measurements for the study were conducted between July and August of 2014 in Chung-ju in the central region of the Republic of Korea. The average anion generation of vertical structure trees during active photosynthesis periods was: L Section ($839.0ea/cm^3$) > M Section ($664.6ea/cm^3$) > U Section ($472.0ea/cm^3$). According to DMRT analysis, significant difference was found in the average between the L, or M Locations and the U Locations. During dormant photosynthesis periods, records showed that the anion production at the M Location ($1,212.5ea/cm^3$) > L Location ($1,050.4ea/cm^3$) > H Location ($844.1ea/cm^3$), According to DMRT analysis, the difference within each location was significant for ${\alpha}=0.05$. In a comprehensive analysis of the weather factors in each vertical structure, anion generation during active photosynthesis periods showed a positive correlation with solar radiation and a negative correlation with wind speed. Dormant photosynthesis periods showed negative correlations with both solar radiation and temperature, and positive correlations with relative humidity and wind speed. Predictions from a multicenter retrospective study showed that during active photosynthesis periods, $Y_1=282.443X_1+512.07$, and $Y_2=314.337X_1+16.913X_2$, while during dormant photosynthesis periods, $Y_1=391.009X_1+840.043$, and $Y_2=351.412X_1+32.765X_2$.

• 농업과학연구
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• 제47권2호
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• pp.315-326
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• 2020

In this study, a real-time crop recognition system was developed for an unmanned farm machine for upland farming. The crop recognition system was developed based on a stereo camera, and an image processing framework was proposed that consists of disparity matching, localization of crop area, and estimation of crop height with coordinate transformations. The performance was evaluated by attaching the crop recognition system to a tractor for five representative crops (cabbage, potato, sesame, radish, and soybean). The test condition was set at 3 levels of distances to the crop (100, 150, and 200 cm) and 5 levels of camera height (42, 44, 46, 48, and 50 cm). The mean relative error (MRE) was used to compare the height between the measured and estimated results. As a result, the MRE of Chinese cabbage was the lowest at 1.70%, and the MRE of soybean was the highest at 4.97%. It is considered that the MRE of the crop which has more similar distribution lower. the results showed that all crop height was estimated with less than 5% MRE. The developed crop recognition system can be applied to various agricultural machinery which enhances the accuracy of crop detection and its performance in various illumination conditions.

• 한국항만경제학회지
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• 제25권1호
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• pp.47-62
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• 2009

본 연구는 SERVQUAL 모형을 근간으로 광양항 컨테이너터미널 운영사의 물류서비스 품질을 평가하기 위해 모형을 설정하고, AHP를 이용하여 상대적 중요도를 도출하였으며, 이를 바탕으로 FUZZY 기법을 이용하여 광양항 터미널 운영사의 경쟁력을 평가하였다. 연구결과, 물류서비스 품질요인 중에서는 확신성이, 하위수준에서는 안전설비가 가장 중요한 요인으로 추출되었다. 또한 이용자 집단(선사 및 운송사)과 운영자 집단(터미널 운영사)간 물류서비스 품질 속성 중요도 평가에 차이가 있음을 밝혔으며, 광양항 터미널 운영사의 물류서비스 품질 경쟁력을 비교 평가한 후, 향후 컨테이너터미널 운영사에 대한 개선 방안과 시사점을 제시하였다.

• 비교문화연구
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• 제45권
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• pp.145-166
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• 2016

본 논문은 파라과이 군부독재정권의 등장에 있어 반공주의의 역할을 살펴보는데 목적이 있다. 제 2차 세계대전 이후 라틴아메리카의 각 국가들은 냉전의 소용돌이 속에서 군부독재정권의 무대가 되었다. 이는 본 연구의 사례 국가인 파라과이도 마찬가지인데, 특히 파라과이는 지리적으로 남미의 중앙부에 위치하고 있어 미국의 반공주의를 위한 전략적 요충지였다. 그 결과로 인해 파라과이에서는 전 세계적으로 유래를 찾아보기 힘든 35년간의 군부독재정권이 집권하였고, 그 정권이 수립되는데 미국이 적극적으로 개입하였다. 이 연구는 군부독재정권의 성립이 냉전시기의 반공주의와 밀접한 관계가 있음을 살펴보는 것도 일차적인 목적이지만, 현재 파라과이를 관통하고 있는 사회적 대립과 갈등, 모순이 냉전이라는 미명하게 미국 주도로 탄생된 반공주의와 군부독재정권의 잔재임을 밝히는 것도 겸하고 있다.

• 신재생에너지
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• 제18권4호
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• pp.70-78
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• 2022

To respond to global warming, there is an increasing interest in eco-friendly alternative energy sources. Therefore, unused forest biomass that has been neglected due to a lack of marketability is attracting attention. With the introduction of the "unused forest biomass certification system" in 2019, ways of determining quantity of unused forest biomass have steadily increased. However, there have been reported cases whereby unused forest biomass weighed more than the amount of harvested trees. It was found that it was possible that forest resources that can be used as round wood were mixed with unused forest biomass. In this context, this study aimed to estimate the amount of mixed round wood in the unused forest biomass supply. The relative expression of growing stock/ha versus the amount of final clearing/ha collected was modeled (y=1.490x-94.341, R²=0.861). As a result, it was found that round wood was mixed into the unused forest biomass, contributing to the disparity observed between the weighted forest biomass and the amount of trees harvested. In conclusion, proper declaration and certification procedures should be carried out for the use of forest resources and promoting unused forest biomass usage.

• 한국IT서비스학회지
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• 제22권5호
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• pp.1-16
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• 2023

This study aimed to provide fundamental insights into the digital customer experience by identifying its components and analyzing their importance and satisfaction levels among youths. To achieve this objective, the components of digital customer experience were identified through a review of prior research and consultation with experts. Subsequently, a survey was conducted with 200 youths in Seoul and Gyeonggi-do. The main findings of the study are as follows: First, The components of the digital customer experience consisted of 12 items grouped into three categories. Second, an analysis of the disparity between the importance and satisfaction levels of digital customer experience revealed statistically significant differences across all items. Third, By utilizing IPA (Importance-Performance Analysis), the digital customer experience was categorized into four quadrant, each with its own characteristics and recommendations for management: The first quadrant, the "current level maintenance area," encompassed items related to "entertainment" and "recommended service." This area is currently functioning well but necessitates continuous attention and management. The second quadrant, the "area to be supported first," included items such as "personalization," "security," "inducing participation," "privacy," and "individuality expression." Intensive management and improvements are imperative in this quadrant. The third quadrant, the "long-term improvement area," consisted of items like 'consistency,' 'information quality,' and 'convenience.' These items require focus on long-term enhancement efforts. The fourth quadrant, the "areas where efforts have already been invested," encompassed items like 'accessibility' and 'deliberation.' It appears that excessive investment has been made in these areas relative to their importance, calling for selective investments while considering the specific issues associated with each factor. These research findings serve as essential data for managing the digital customer experiences of youths.