• 한국산학기술학회논문지
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• 제15권5호
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• pp.3336-3344
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• 2014

본 연구의 목적은 소규모 응집침전모듈의 개발 및 lab-scale 테스트를 통한 실증이다. 최근 하수처리율이 높아짐에 따라 비점오염원 관리에 대한 관심이 높아지고 있어 소규모 처리장치 개발의 필요성이 증대되고 있다. 본 연구의 응집침전모듈은 응집공정 이후 외부 영역에서 선회류를 통한 플럭(floc)의 추가 성장 및 미세 플럭 수의 감소, 내부 침전 영역에서 수직 수평류 복합침전방식을 통한 침전효율 증대로 효과적인 고액분리가 가능토록 하였다. 응집침전모듈은 수직 수평류 복합침전 방식을 통해 재래식침전조에 비해 같은 체적에서 침전면적 및 표면부하율을 4.4배 증가시킬 수 있었다. 본 연구에서 외부 및 내부 침전 영역에서의 선회류 형성 유지와 내부 침전영역에서의 균등한 유량분배를 본 공정의 중요한 설계인자로 선정하였고, 이의 도출을 위해 유체유동해석 모델인 FLUENT를 이용하였다. 선회류 유동경향 모사를 통해 유입속도, 외부조의 규격, 하부콘호퍼 깊이 등을 결정하였고 속도분포 및 유량분배 해석을 통해 유출공 직경과 개수, 유출홀 직경 등 내부 침전영역의 세부 규격을 도출하였다. $60{\ell}/hr$규모의 파일럿 테스트 결과 20분의 체류시간 동안(표면부하율은 $37.3m^3/m^2$일)탁도 300~800 NTU의 폐수를 고분자응집제 주입 없이 10 NTU 이하로 처리할 수 있었으며, 유체유동해석 모델을 활용한 설계인자 도출의 가능성을 확인하였다.

• 한국비블리아학회지
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• 제23권1호
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• pp.317-340
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• 2012

본 연구는 지역사회의 도서관 접근성 향상을 위한 지역 개방형 학교도서관에 대한 연구로서 기존의 학교도서관으로 이용하던 시설일부를 개방하여 지역주민에게 공공도서관의 소분관으로 제공함으로써 도서관접근성 향상 및 지역주민의 평생교육 제공에 목적을 갖는다. 또한 공공도서관의 이용활성화를 통해 국민생활의 정보이용 복지향상에도 기여할 것으로 기대하고 있다. 이에 대한 논의로 교육과학기술부와 대통령소속 도서관정보정책위원회에서는 도서관 접근성 향상 및 활성화를 위한 대책으로 공공도서관의 분관에 속하는 소규모도서관과 작은 도서관 확충에 노력을 기울이고 있다. 지역에 거점도서관의 소분관 설치 증가도 의미는 있겠지만 지역주민의 접근이 용이한 학교도서관에 같은 기능을 접목시켜 설치할 경우 도서관 조성시 대지 및 공간확보에 대한 예산을 절약할 수 있음은 물론 학교도서관 자체의 질적 향상 또한 기대할 수 있을 것이다. 그러나 학교도서관은 기능과 성격이 공공도서관과는 차이가 있으므로 학교도서관을 지역개방하여 활용할 경우에 대한 공간에 대한 연구가 필요하다. 따라서, 본 연구를 통하여 학교도서관을 지역사회에 개방하기 위한 배치와 규모 그리고 공간구성에 지향방안을 모색함으로써 향후 조성될 개방형 학교도서관이 본연의 기능을 수행할 수 있도록 하고자 한다.

• 동력기계공학회지
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• 제19권5호
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• pp.80-85
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• 2015

The unsteady-state, incompressible and three-dimensional large eddy simulation(LES) was carried out to analyze the structure of turbulent flow fields according to the operating loads of three-dimensional small-size axial fan(SSAF). LES shows the best prediction performance in comparison with any other Reynolds averaged Navier-Stokes(RANS) method because static pressure coefficients analysed by LES show a little bit larger than measurements including all flow coefficients. Also, it can be known that the wake of SSAF is divided into from axial flow to radial flow before and behind stall region according to the increase of static pressure through LES analysis.

• 동력기계공학회지
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• 제20권6호
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• pp.64-70
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• 2016

The unsteady-state, incompressible and three-dimensional large-eddy simulation(LES) was carried out to evaluate the vorticity distribution of a small-size axial fan(SSAF). The X-component vorticity profiles developed around blade tips turn from axial to radial, and diminish the density of distribution according to the increase of static pressure. Otherwise, the Z-component vorticity profiles evenly develop at the region larger than the half radial distance of blade at the operating points of A and B, partly at the trailing-edge region of blade and radially over bellmouth according to the increase of static pressure.

• 동력기계공학회지
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• 제21권2호
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• pp.57-63
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• 2017

The large-eddy simulation(LES) was carried out to evaluate the drag and static pressure acting on the blade surface of a small-size axial fan(SSAF) under the condition of unsteady-state, incompressible fluid and three-dimensional coordination. The axial component of drag coefficient increases with the increase of operating load, but the radial components have negligible sizes regardless of operating loads. Otherwise, the static pressures acting on the blade surfaces of SSAF show different distributions around the operating point of D equivalent to the stall. Also, with the increase of operating load, the static pressures acting on the pressure and suction surfaces of blade concentrate at the tips and leading-edges as a whole.

• 농촌계획
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• 제4권2호
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• pp.20-28
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• 1998

A small wastewater collection system for rural area was reviewed and the small diameter gravity (SDG) was thought to be the most appropriate. The pilot-scale field experiment was performed for 15 months and the result is presented. The wastewater used for experiment was the effluent of septic tank in Kon-Kuk University, and components are similar to normal domestic wastewater. The SDG experimental system included 2" PVC pipe and reverse-sloped lower section is included. No clogging problem by solids was experienced at the points where flow direction changed. The pipe-breaking by freezing was experienced during the cold weather, thus proper protection may be required where severe weather is expected.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1230-1239
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• 2018

We derive a factorization theorem for the jet mass distribution with a given $p^J_T$ for the inclusive production, where $p^J_T$ is a large jet transverse momentum. Considering the small jet radius limit ($R{\ll}1$), we factorize the scattering cross section into a partonic cross section, the fragmentation function to a jet, and the jet mass distribution function. The decoupled jet mass distributions for quark and gluon jets are well-normalized and scale invariant, and they can be extracted from the ratio of two scattering cross sections such as $d{\sigma}/(dp^J_TdM^2_J)$ and $d{\sigma}/dp^J_T $. When $M_J{\sim}p^J_TR$, the perturbative series expansion for the jet mass distributions works well. As the jet mass becomes small, large logarithms of $M_J/(p^J_TR)$ appear, and they can be systematically resummed through a more refined factorization theorem for the jet mass distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권12호
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• pp.4795-4815
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• 2020

Drone detection can be considered as a specific sort of small object detection, which has always been a challenge because of its small size and few features. For improving the detection rate of drones, we design a Deeper SSD network, which uses large-scale input image and deeper convolutional network to obtain more features that benefit small object classification. At the same time, in order to improve object classification performance, we implemented the up-sampling modules to increase the number of features for the low-level feature map. In addition, in order to improve object location performance, we adopted the down-sampling modules so that the context information can be used by the high-level feature map directly. Our proposed Deeper SSD and its variants are successfully applied to the self-designed drone datasets. Our experiments demonstrate the effectiveness of the Deeper SSD and its variants, which are useful to small drone's detection and recognition. These proposed methods can also detect small and large objects simultaneously.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.388-394
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• 2010

In this paper the object recognition performance of a photon counting integral imaging system is quantitatively compared with that of a conventional gray scale imaging system. For 3D imaging of objects with a small number of photons, the elemental image set of a 3D scene is obtained using the integral imaging set up. We assume that the elemental image detection follows a Poisson distribution. Computational geometrical ray back propagation algorithm and parametric maximum likelihood estimator are applied to the photon counting elemental image set in order to reconstruct the original 3D scene. To evaluate the photon counting object recognition performance, the normalized correlation peaks between the reconstructed 3D scenes are calculated for the varied and fixed total number of photons in the reconstructed sectional image changing the total number of image channels in the integral imaging system. It is quantitatively illustrated that the recognition performance of the photon counting integral imaging system can be similar to that of a conventional gray scale imaging system as the number of image viewing channels in the photon counting integral imaging (PCII) system is increased up to the threshold point. Also, we present experiments to find the threshold point on the total number of image channels in the PCII system which can guarantee a comparable recognition performance with a gray scale imaging system. To the best of our knowledge, this is the first report on comparisons of object recognition performance with 3D photon counting & gray scale images.

• 교육시설 논문지
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• 제21권4호
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• pp.21-30
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• 2014

In general, teachers' perceptions on the physical environment of elementary school are related on the quality of education and school life. But, we don't have study what teachers think of their enviroment of school. This study analyzed elementary school teachers' satisfaction with overall physical environment and their assessment of spaces with specific functions in order to understand teachers' perception of the physical environment of elementary schools. A survey questionnaire was administered to 982 homeroom teachers working at 67 elementary schools located in Seoul and Busan. Teachers' satisfaction with physical environment of school and their assessment were analyzed comparatively according to the teachers' personal attributes and school conditions. 1) Most of the surveyed teachers were satisfied with overall physical environment of the school, and assessed high the substantiality of functional spaces indoor and outdoor. By sub-factor, however, their satisfaction with work environment was lower than that with education and living environment. 2) The teachers perceived that the optimal number of classes was 30~36, and this is probably because they were relatively accustomed to large scale schools. 3) As might be expected, negative assessments were more frequent among teachers working at a large-scale school, an old school, or a school with small outdoor spaces. The results of this study show that, though partially different according to region, gender, teaching experience and school condition, teachers' satisfaction with school environment was relatively high. This suggests that elementary school teachers perceive their current school environment positively. Because they are accustomed to traditional education methods that have been maintained.