• Nuclear Engineering and Technology
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• 제55권2호
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• pp.749-755
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• 2023

A new approximation method was proposed for treating the non-resonant spatial self-shielding effects of double heterogeneous region such as the double heterogeneous effect of VHTR fuel compact in the thermal energy range and that of BP compact with BISO. The method was developed based on the effective homogenization method and a spherical unit cell model with explicit coated layers and a matrix layer. The self-shielding factor was derived from the relation between the collision probabilities for a double heterogeneous compact and the effective cross section for the homogenized compact. First, the collision probabilities and transmission probabilities for all layers of the spherical model were calculated using conventional collision probability solver. Then, the effective cross section for the homogenized sphere cell representing the homogenized compact was obtained from the transmission probability calculated using the probability density function of a chord length. The verification calculations revealed that the proposed method can predict the self-shielding factor with a maximum error of 2.3% and the double heterogeneous effect with a maximum error of 200 pcm in the typical VHTR problems with various packing fractions and BP compact sizes.

• Journal of Astronomy and Space Sciences
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• 제41권1호
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• pp.35-42
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• 2024

Sungrazing comets, known for their proximity to the Sun, are traditionally classified into broad groups like Kreutz, Marsden, Kracht, Meyer, and non-group comets. While existing methods successfully categorize these groups, finer distinctions within the Kreutz subgroup remain a challenge. In this study, we introduce an automated classification technique using the densitybased spatial clustering of applications with noise (DBSCAN) algorithm to categorize sungrazing comets. Our method extends traditional classifications by finely categorizing the Kreutz subgroup into four distinct subgroups based on a comprehensive range of orbital parameters, providing critical insights into the origins and dynamics of these comets. Corroborative analyses validate the accuracy and effectiveness of our method, offering a more efficient framework for understanding the categorization of sungrazing comets.

• Steel and Composite Structures
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• 제18권4호
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• pp.853-871
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• 2015

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.

• 한국실내디자인학회논문집
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• 제26권5호
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• pp.83-92
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• 2017

This research is about the characteristics of the saccades that occurring in the process of observing the spatial. The size of the saccades is the visual activity for acquiring the information, and the search trace that left by the spatial visitor. Reviewed over the saccade through the analysis of observation process that appeared in the eye-tracking experiment of sports store from the department store, the saccade is defined as the sight movement in the process of finding a component to view in the spatial. If some spatial component induces saccade, and able to know which specific component acquired through the saccade, then the designer will have a clue which able to provide the spatial desired by the consumer. The results of analyzing the process in the deriving the spatial component and saccade characteristic from industrial space, can be summarised as follows. The first, the average fixed number of [IN].[OUT] zone appeared similarly, and it leads to knowing that the time used for attention with one frequency is about 0.3 seconds. Second, there were more saccades toward [$IN{\rightarrow}OUT$] (13 persons, 76.5%) than [$OUT{\rightarrow}IN$] (4 persons, 23.5%). The Los Angeles area has lots of interesting things to watch, so it able to thinks to begins with small saccade and then occur to bigger saccade activity to find new interests shortly after [OUT] saccade. Third, according to time range changes, keep eyes on the characteristics of saccade, [IN].[OUT] frequency has slightly decreased the changes of viewing time, but there was no significant change in an average number of observations. This means that the frequency and the number of observations are decreased together. Therefore, it can be seen that the amount of information to be acquired (frequency) is decreased (count) as the observation time elapses.

• 한국공간구조학회논문집
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• 제20권3호
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• pp.107-116
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• 2020

In this paper, the displacement response to seismic loads was analyzed after installing TMD in spatial structures and high-rise buildings. In the case of a spatial structures, since it exhibits complex dynamic behavior under the influence of various vibration modes, it is not possible to effectively control the seismic response by installing only one TMD, unlike ordinary structures. Therefore, after installing eight TMDs in the structure, the correlation between displacement response and mass ratio was examined while changing the mass. The TMD must be designed to have the same frequency as the structure frequency so that the maximum response reduction effect can be exhibited. It can be confirmed that the most important variable is to select the optimal TMD mass in order to install the TMD on the structure and secure excellent control performance against the earthquake load. As a result of analyzing the TMD mass ratio, in the case of high-rise buildings, a mass ratio of 0.4% to 0.6% is preferable. In spatial structures, it is desirable to select a mass ratio of 0.1% to 0.2%. Because this study is based on the theoretical study based on numerical analysis, in order to design a TMD for a real structure, it is necessary to select within a range that does not affect the safety of the structure.

• 수산해양교육연구
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• 제23권3호
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• pp.477-485
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• 2011

For the identifying of spatial distribution pattern, Moran's Index(I) which has the range of values from -1 to +1 is common method for the spatial autocorrelation measurement. When I is close to 1, all neighboring features have close to the same value, indicating clustered pattern. Conversely, if the spatial pattern is dispersed, I is close to -1. And I closing to 0 means spatially random pattern. However, this index equation is influenced by how defining the neighboring features for target feature. To compare and understand the difference of neighborhood definition methods, fixed distance neighboring method and Gabriel Network method were used for I. In this study, these two methods were applied to two marine environments with water quality data. One is Gwangyang Bay which has complex geometric coastal structure located in South Sea of Korea. Another is Uljin area adjacent to open sea located in east coast of Korea. The distances between water quality observed locations were relatively regular in Gwangyang Bay, however, irregular in Uljin area. And for the fixed distance method popular Arc GIS tool was used, but, for the Gabriel Network, Visual Basic program was developed to produce Gabriel Network and calculate Moran's I and its Z-score automatically. According to this experimental results, different spatial pattern was showed differently for some data with using of neighboring definition methods. Therefore there is need to choose neighboring definition method carefully for spatial pattern analysis.

• Spatial Information Research
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• 제19권6호
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• pp.1-10
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• 2011

국가지리정보체계의 구축 및 활용 등에 관한 법률(구법/NGIS Act, 2000)이 폐지되고 국가공간정보에 관한 법률(신법/NSDI Act, 2009)이 제정되면서 국가 공간정보 정책 평가시스템에는 많은 변화가 발생되었다. 구법과 비교할 경우 신법은 국가 공간정보 정책의 추진체계가 일원화되었다는 장점은 있으나 예산 요구권의 약화로 공간정보 정책의 법적 실현가능성은 약화되었다는 논의가 있다. 이러한 문제의식 하에 구법에서 신법으로 법률이 새롭게 제 개정되면서 나타난 평가체계의 변화를 분석하는 것은 매우 중요한 의미를 갖는다고 할 것이다. 따라서 본 연구의 목적은 구법과 신법에서 규정한 국가공간정보 정책 평가체계를 비교 분석하여 평가 제도에서 나타난 변화가 무엇인지를 분석하는데 있다. 주된 연구방법은 구법과 신법의 비교분석 방법을 활용하였다. 비교 분석대상은 평가추진체계, 평가주체, 평가대상 및 범위, 평가결과의 활용, 평가전담기관 등이다. 분석결과를 토대로 할 경우 국가 공간정보 정책 평가시스템의 개선방안으로는 평가목적의 명확화, 평가 전담기관 제도의 활성화, 평가결과와 인센티브 및 예산 연계성의 강화, 공간정보정책의 사전 사후 연계성 강화 방법론 모색, 상향식과 하향식 접근이 결합된 평가지표의 개발 방안 등이 필요하다는 것을 제안하였다.

• 로봇학회논문지
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• 제11권3호
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• pp.140-145
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• 2016

In this paper, we fabricate arrayed-type flexible capacitive touch sensor using liquid metal (LM) droplets (4 mm spatial resolution). Poly-4-vinylphenol (PVP) layer is used as a dielectric layer on the electrode patterned Polyethylene naphthalate (PEN) film. Bonding tests between hydroxyl group (-OH) on the PVP film and polydimethylsiloxane (PDMS) are conducted in a various $O_2$ plasma treatment conditions. Through the tests, we can confirm that non-$O_2$ plasma treated PVP layer and $O_2$ plasma treated PDMS can make a chemical bond. To measure dynamic range of the device, one-cell experiments are conducted and we confirmed that the fabricated device has a large dynamic range (~60 pF).

• ETRI Journal
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• 제40권5호
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• pp.592-603
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• 2018

In order to obtain better target identification performance, an efficient waveform design method with high range resolution and low sidelobe level for orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) radar is proposed in this paper. First, the wideband CP-based OFDM signal is transmitted on each antenna to guarantee large bandwidth and high range resolution. Next, a complex orthogonal design (COD) is utilized to achieve code domain orthogonality among antennas, so that the spatial diversity can be obtained in MIMO radar, and only the range sidelobe on the first antenna needs suppressing. Furthermore, sidelobe suppression is expressed as an optimization problem. The integrated sidelobe level (ISL) is adopted to construct the objective function, which is solved using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The numerical results demonstrate the superiority in performance (high resolution, strict orthogonality, and low sidelobe level) of the proposed method compared to existing algorithms.

• 제어로봇시스템학회논문지
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• 제11권4호
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• pp.378-384
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• 2005

This paper proposes a theoretically rigorous analysis procedure that compares the position domain and range domain carrier-smoothed-code filters for differential GNSS positioning. Utilizing consistent error covariance formulation, it is shown that filtering in the position domain is, in theory, more advantageous than range domain carrier-smoothed-code filtering. It is also shown that if the visible satellite set does not change during a sufficiently long time interval the performances of position and range domain filters are similar.