• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1704-1710
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• 2010

The structure of a 2D grid-like copper(II) complex [Cu$(NCO)_2$(pyz)](pyz=pyrazine) (1) consists of 1D chains of Cu-pyz units connected by double end-on (EO) cyanato bridges. Each Cu(II) ion has a distorted octahedral coordination, completed by the four EO cyanato and two pyrazine ligands. Magnetic interactions through EO cyanato and pyrazine bridges in 1 are discussed on the basis of DFT broken-symmetry calculations at the B3LYP level. For model dicopper(II) complexes I (bridged by cyanato) and II (bridged by pyrazine), electronic structure calculations reproduce very well the experimental couplings for the S = 1/2 ferromagnetic and antiferromagnetic exchange-coupled 2D system: the calculated exchange parameters J are +1.25 $cm^{-1}$ and -3.07 $cm^{-1}$ for I and II, respectively. The $\sigma$ orbital interactions between the Cu $x^2-y^2$ magnetic orbitals and the nitrogen lone-pair orbitals of pyrazine are analyzed from the viewpoint of through-bond interaction. The energy splitting of 0.106 eV between two SOMOs indicates that the superexchange interaction should be antiferromagnetic in II. On the other hand, there are no bridging orbitals that efficiently connect the two copper(II) magnetic orbitals in I because the HOMOs of the basal-apical NCO bridge do not play a role in the formation of overlap interaction pathway. The energy separation in the pair of SOMOs of I is calculated to be very small (0.054 eV). This result is consistent with the occurrence of weakly ferromagnetic properties in I.

• 수산해양기술연구
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• 제53권3호
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• pp.286-292
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• 2017

The Coastal VTS will be continuously constructed to prevent marine traffic accidents in the coastal waters of the Republic of Korea. In order to provide the best traffic information service to the ship operator, it is important to understand the navigation risk factor. In this study, we analyzed the navigational hazards of Gunsan coastal area where the coastal VTS will be constructed until 2020. For this purpose, major traffic flows of merchant ships and density of vessels engaged in fishing were analyzed. This study was conducted by Automatic Identification System (AIS) and Vessel Pass (V-PASS) data. The grid intervals are 10 minute ${\times}$ 10 minute (latitude ${\times}$ longitude) based on the section of the sea. A total of 30 sections were analyzed by constructing a grid. As a result of the analysis, the major traffic flows of the merchant vessels in the coastal area of Gunsan were surveyed from north to south toward Incheon, Pyeongtaek, Daesan, Yeosu, Pusan and Ulsan, and from east to west in the port of Gunsan Port, 173-3, 173-6, 173-8, 183-2, 183-5, 183-8, 183-3, 184-1 and 184-2. As a result of the study, the fishing boats in Gunsan coastal area mainly operated in spring and autumn. On the other hand, the main traffic flow of merchant ships and the distribution of fishing vessels continue to overlap from March to June, so special attention should be paid to the control during this period.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.706-713
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• 2014

An enhanced 360-degree integral-floating three-dimensional display system using a hexagonal lens array and a hidden point removal operator is proposed. Only the visible points of the chosen three-dimensional point cloud model are detected by the hidden point removal operator for each rotating step of the anamorphic optics system, and elemental image arrays are generated for the detected visible points from the corresponding viewpoint. Each elemental image of the elemental image array is generated by a hexagonal grid, due to being captured through a hexagonal lens array. The hidden point removal operator eliminates the overlap problem of points in front and behind, and the hexagonal lens array captures the elemental image arrays with more accurate approximation, so in the end the quality of the displayed image is improved. In an experiment, an anamorphic-optics-system-based 360-degree integral-floating display with improved image quality is demonstrated.

• 대한건축학회논문집:계획계
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• 제36권5호
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• pp.59-70
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• 2020

The purpose of this study is to derive the environmental factors affecting child loss through correlation analysis between child loss and pedestrian density. The status of lost children was identified through the lost child records and interviews in large parks. In addition, the behavior survey was conducted by photographing the entire outdoor of each park, and visitors was marked on the behavioral maps. Also, the pedestrian density was analyzed by GIS as 100㎡ and 1㎡ grid. As a result, child loss was related to the pedestrian density rather than the number of visitors or the area. Especially, 'Dynamic pedestrian density' and 'Ratio of pedestrian in high density to area' was related to child loss. In other words, the more dynamic behaviors such as play and movement appear, and the more the local area of high density, the higher the probability of child loss. In addition, environmental factors that induce such high density include bottlenecks, overlap of circulation due to multi-functionality of space, concentration of rides, and concentration of guardians due to visual obstacles.

• Smart Structures and Systems
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• 제29권1호
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• pp.1-16
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• 2022

Despite recent breakthroughs in deep learning and computer vision fields, the pixel-wise identification of tiny objects in high-resolution images with complex disturbances remains challenging. This study proposes a modified U-net for tiny crack segmentation in real-world steel-box-girder bridges. The modified U-net adopts the common U-net framework and a novel Self-Attention-Self-Adaption (SASA) neuron as the fundamental computing element. The Self-Attention module applies softmax and gate operations to obtain the attention vector. It enables the neuron to focus on the most significant receptive fields when processing large-scale feature maps. The Self-Adaption module consists of a multiplayer perceptron subnet and achieves deeper feature extraction inside a single neuron. For data augmentation, a grid-based crack random elastic deformation (CRED) algorithm is designed to enrich the diversities and irregular shapes of distributed cracks. Grid-based uniform control nodes are first set on both input images and binary labels, random offsets are then employed on these control nodes, and bilinear interpolation is performed for the rest pixels. The proposed SASA neuron and CRED algorithm are simultaneously deployed to train the modified U-net. 200 raw images with a high resolution of 4928 × 3264 are collected, 160 for training and the rest 40 for the test. 512 × 512 patches are generated from the original images by a sliding window with an overlap of 256 as inputs. Results show that the average IoU between the recognized and ground-truth cracks reaches 0.409, which is 29.8% higher than the regular U-net. A five-fold cross-validation study is performed to verify that the proposed method is robust to different training and test images. Ablation experiments further demonstrate the effectiveness of the proposed SASA neuron and CRED algorithm. Promotions of the average IoU individually utilizing the SASA and CRED module add up to the final promotion of the full model, indicating that the SASA and CRED modules contribute to the different stages of model and data in the training process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.1890-1910
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• 2013

Routing overlay offers an ideal methodology to improve the end-to-end communication performance by deriving a backup path for any node pair. This paper focuses on a challenging issue of selecting a proper backup path to bypass the failures on the default path with high probability for any node pair. For existing backup path selection approaches, our trace-driven evaluation results demonstrate that the backup and default paths for any node pair overlap with high probability and hence usually fail simultaneously. Consequently, such approaches fail to derive a robust backup path that can take over in the presence of failure on the default path. In this paper, we propose a three-phase RBPS approach to identify a proper and robust backup path. It utilizes the traceroute probing approach to obtain the fine-grained topology information, and systematically employs the grid quorum system and the Bloom filter to reduce the resulting communication overhead. Two criteria, delay and fault-tolerant ability on average, of the backup path are proposed to evaluate the performance of our RBPS approach. Extensive trace-driven evaluations show that the fault-tolerant ability of the backup path can be improved by about 60%, while the delay gain ratio concentrated at 14% after replacing existing approaches with ours. Consequently, our approach can derive a more robust and available backup path for any node pair than existing approaches. This is more important than finding a backup path with the lowest delay compared to the default path for any node pair.

• 한국컴퓨터그래픽스학회논문지
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• 제16권4호
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• pp.35-40
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• 2010

최근 디지털 사진의 보급으로 인해, 일반 사람들 또한 한번에 수백장의 사진을 촬영하는 일이 많아졌고 최근에 사진 관리에 대한 많은 연구가 진행되고 있다. 대부분의 사진 관리에 사용되는 썸네일 기반의 순차적인 격자 인터페이스는 사진의 한가지 특성에 따라 각 사진을 정렬하는 방식을 사용한다. 이러한 방식은 사용자가 많은 수의 사진을 관리하기에는 많은 스크롤링과 클릭을 요구하게 되므로 많은 시간과 집중력이 요구된다. 본 논문에서는, 색상 유사도와 촬영 시각을 이용하여, 각 사진을 클러스터링하고 촬영 시각의 흐름에 따라 배열하는 인터페이스를 제안한다. 제안한 인터페이스는 사진의 촬영시각에 따라 먼저 각 사진들을 클러스터링하고 한번 분류된 클러스터 사진들은 서로 유사한 색상의 사진들끼리 2차로 재분류한다. 이 때 사용한 2차 클러스터링 방법은 구간 그래프의 최대 클리크 찾기 찾기 알고리즘을 이용한 방법으로 25가지 색상의 히스토그램을 비교한다. 분류된 사진들은 클러스터의 순서에 따라 연속적으로 각 클러스터들을 배치한다. 제안한 클러스터링 기능과 사진 배치 인터페이스를 평가하기 위해서, 설문조사 기반의 사용자 평가를 수행하였다.

• Computers and Concrete
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• 제23권3호
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• pp.161-170
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• 2019

This paper aims at presenting a numerical method for estimating the elastic modulus of recycled concrete with crushed aggregates. In the method, polygonal aggregates following a given sieve curve are generated, and placed into a square simulation element with the aid of the periodic boundary condition and the overlap criterion of two polygonal aggregates. The mesostructure of recycled concrete is reconstructed by embedding an old interfacial transition zone (ITZ) layer inside each recycled aggregate and by coating all the aggregates with a new ITZ layer. The square simulation element is discretized into a regular grid and a representative point is selected from each sub-element. The iterative method is combined with the fast Fourier transform to evaluate the elastic modulus of recycled concrete. After the validity of the numerical method is verified with experimental results, a sensitivity analysis is conducted to evaluate the effects of key factors on the elastic modulus of recycled concrete. Numerical results show that the elastic modulus of recycled concrete increases with the increase of the total aggregate content and the elastic moduli of old and new ITZ but decreases with increasing the replacement ratio of recycled aggregate and the thicknesses of old and new ITZ. It is also shown that, for a replacement ratio of recycled aggregate smaller than 0.3, the elastic modulus of recycled concrete is reduced by no more than 10%.

• 생명과학회지
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• 제28권3호
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• pp.307-313
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• 2018

탈모증상은 겉으로 보이는 모습으로 인해 정신적인 스트레스로 작용한다. 그래서 탈모 방지관련 제품의 글로벌 시장 규모는 지속적으로 성장하고 있다. Timosaponin A III는 지모 추출물에서 발견되는 대표적인 saponin 계열의 생리 활성 효능 성분이다. 본 연구에서는 5-beta reductase 단백질 길항제(antagonist) finasteride, androgen receptor 단백질 길항제 minoxidil, 그리고 지모 추출물의 효능 성분 timosaponin A III의 각각의 타깃 단백질 활성 부위에 대한 친화도 분석 실험을 in silico 컴퓨터 분자결합 분석 방법을 통해 비교하였다. 5-beta reductase 및 androgen receptor 의 3차원 구조 정보는 PDB database (5-beta reductase PDB ID: 3G1R / androgen receptor PDB ID:4K7A)를 활용하였다. In silico 결합 분석을 수행하기 위해 PyRx, Autodock Vina, Discovery Studio Version 4.5, and NX-QuickPharm 프로그램을 각 분석 조건에 따라 활용하였다. 5-beta reductase 활성 부위에 대한 timosaponin A III의 최대 결합친화도는 -12.20 kcal/mol으로 나왔으며 이는 -11.70 kcal/mol으로 분석된 finasteride의 5-beta reductase 활성부위에 대한 결합 친화도 보다 훨씬 더 높고 효율적인 것으로 분석되었다. Androgen receptor 활성 부위에 대한 timosaponin A III의 최대결합친화도 또한 -9.00 kcal/mol으로 -7.40 kcal/mol의 minoxidil에 비하여 훨씬 우수한 결합친화도 값을 나타내었다. Finasteride와 timosaponin A III의 5-beta reductase 단백질 활성 부위에 대한 X,Y,Z Grid 값은 유사한 좌표로 분석되었으나 minoxidil과 timosaponin A III의 androgen receptor 활성 부위에 대한 X,Y,Z centroid grid 좌표는 상당한 거리를 두고 떨어져 있음이 확인 되었다. 즉, timosaponin A III는 minoxidil이 androgen receptor에 결합하는 부위와는 다른 부위에 결합하여 단백질 활성에 영향을 주는 것으로 사료되었다. 이상의 연구 결과들을 바탕으로 분석해 볼 때, 5-beta reductase 길항제 finasteride와 androgen receptor 길항제 minoxidil보다 지모 추출물 생리 활성 물질인 timosaponin A III가 보다 더 효율적인 길항제로 작용할 수 있음을 확인하였다. 결론적으로 지모 추출물 또는 timosaponin 계열이 함유된 효능 성분은 탈모 방지 효능 및 모발 건강 개선을 위한 의약품, 의약외품 및 신물질 연구 개발 분야에 효율적으로 활용할 수 있을 것으로 사료된다.

• 전자공학회논문지
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• 제49권12호
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• pp.56-63
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• 2012

WBAN은 인체 내부 및 외부에 부착한 디바이스를 무선으로 연결하여 통신하는 근거리 무선통신 기술로 IEEE 802.15.6 TG BAN을 중심으로 물리, 데이터 링크, 네트워크, 응용계층에서 표준화가 진행되고 있다. WBAN 기술은 전력제한 및 생체특성을 반영하여 센서와 지그비 디바이스를 사용하여 에너지 효율적으로 구성한다. 무선 센서 네트워크는 다수의 센서노드와 센서노드가 전송하는 센싱 데이터를 수집하는 싱크노드로 구성된다. 센서노드는 넓은 지역에 정해진 형태 없이 배치되어 프로토콜에 의해 자가구성 능력을 가진다. 싱크노드는 고정 싱크노드와 모바일 싱크노드로 구분되고 모바일 싱크노드는 전체 네트워크의 에너지 소모를 분산시켜 고정싱크 노드보다 네트워크의 라이프 타임이 증가하는 장점이 있다. 센서노드의 제한된 에너지 자원은 WBAN의 에너지 효율측면에서 중요한 문제이다. 본 논문에서는 모바일 싱크노드 기반의 WBAN 환경에서 효율적인 데이터 전송을 위한 클러스터 토폴로지 알고리즘을 제안한다. 제안한 알고리즘은 그리드 기반의 라우팅 프로토콜 및 TDMA 기반의 스케줄링 알고리즘의 장점을 바탕으로 인접한 클러스터의 중첩영역을 최소화하고 클러스터 헤더의 데이터 부담을 감소시켜 수집지연 및 오버헤드가 빈번하게 발생하는 WBAN 환경의 무선 센서 네트워크에서 우수한 성능을 보였다.