• Journal of Positioning, Navigation, and Timing
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• 제9권4호
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• pp.357-366
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• 2020

This paper addressed a relative navigation method for autonomous rendezvous and docking of cube-satellites using single frequency Differential GPS (DGPS) under the intermittent communication between satellites. Since the ionospheric error of GPS measurement is variable depending on the visible satellites, a few meters error of relative navigation is occurred in the Low-Earth Orbit (LEO) environment. Therefore, it is essential to remove the ionospheric error to perform relative navigation. Besides, an intermittent communication period for receiving GPS measurements of the target satellite is limited for getting information every sampling time. To solve this problem, a method combining range domain DGPS and orbit propagation is proposed in this paper. The proposed method improves the performance of DGPS by using Hatch filter and solves an intermittent communication problem by estimating the relative position and velocity using Hill-Clohessy-Wiltshire Equation. Through the simulation, it is verified that the suggested algorithm provides the relative position error within RMS 0.5 m and the relative velocity error within RMS 3 cm/s. Furthermore, it has the advantage that it is suitable for real-time implementation using single-frequency GPS measurements and is computationally efficient.

• 제어로봇시스템학회논문지
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• 제13권8호
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• pp.810-816
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• 2007

A security robot system named EGIS-SR is a mobile security robot through one of the new growth engine project in robotic industries. It allows home surveillance through an autonomous mobile platform using onboard cameras and wireless security sensors. EGIS-SR has many sensors to allow autonomous navigation, hierarchical control architecture to handle lots of situations in monitoring home surveillance and mighty networks to achieve unmanned security services. EGIS-SR is tightly coupled with a networked security environment, where the information of the robot is remotely connected with the remote cockpit and patrol man. It achieved an intelligent unmanned security service. The robot is a two-wheeled mobile robot and has casters and suspension to overcome a doorsill. The dynamic motion is verified through $ADAMS^{TM}$ simulation. For the main controller, PXA270 based hardware platform based on linux kernel 2.6 is developed. In the linux platform, data handling for various sensors and the localization algorithm are performed. Also, a local path planning algorithm for object avoidance with ultrasonic sensors and localization using $StarGazer^{TM}$ is developed. Finally, for the automatic charging, a docking algorithm with infrared ray system is implemented.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.249-256
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• 2004

KRISO/KORDI is currently developing a deep-sea unmanned underwater vehicle (UUV) system which is composed of a launcher, an ROV, and an AUV. Two USBL acoustic positioning systems will be used for UUV's navigation. One is for the deep sea positioning of all three vehicles and the other is for AUV's guidance to the docking device on the launcher. In order to increase the position accuracy MFSK(Multiple Frequency Shift Keying) broadband signal will be used. As the first step to the implementation of a USBL system, this paper studies USBL positioning algorithm using MFSK signals. Firstly, the characteristics of MFSK signal is described with various MFSK parameters: number of frequencies, frequency step, center frequency, and pulse length. Time and phase delays between two received signals are estimated by using cross-correlation and cross-spectrum methods. Finally an USBL positioning algorithm is derived by converting the delays to difference of distances and applying trigonometry. The simulation results show that the position accuracy is improved highly when both cross-correlation and cross-spectrum of MFSK signals are used simultaneously.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.770-774
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• 2012

Protein loops are often involved in diverse biological functions, and some functional loops show conformational changes upon ligand binding. Since this conformational change is directly related to ligand binding pose and protein function, there have been numerous attempts to predict this change accurately. In this study, we show that it is plausible to obtain meaningful ensembles of loop conformations for flexible, ligand-binding protein loops efficiently by applying a loop modeling method. The loop modeling method employs triaxial loop closure algorithm for trial conformation generation and conformational space annealing for global energy optimization. When loop modeling was performed on the framework of ligand-free structure, loop structures within $3\AA$ RMSD from the crystal loop structure for the ligand-bound state were sampled in 4 out of 6 cases. This result is encouraging considering that no information on the ligand-bound state was used during the loop modeling process. We therefore expect that the present loop modeling method will be useful for future developments of flexible protein-ligand docking methods.

• 한국산학기술학회논문지
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• 제12권8호
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• pp.3626-3635
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• 2011

모듈러 로봇은 기존 바퀴 혹은 다리를 가지고 있는 이동용 로봇이 가지는 공간 이동의 제한성을 극복하기 위해 개발된 로봇이다. 이는 다리형 로봇의 경우 이동 속도나 지형 등에 있어 균형 잡기 등에 어려움이 존재하며, 바퀴 이동형 로봇의 경우 요철과 둔턱 등을 극복하는데 한계를 지니게 된다. 이에 비해 모듈러 로봇의 경우 형상의 변경이 용이하며 이를 통해 자유로운 이동이 가능하여 이동성능에 제약을 극복할 수 있는 로봇이다. 하지만 모듈러 로봇의 경우 구동메커니즘 뿐만 아니라 형상 변경에 따른 결합 분리 메카니즘에 대한 연구도 진행되어야 한다. 이에 본 논문에서는 네 종류의 모듈러 로봇 결합 메커니즘을 제안하였다. 또한 각 모듈러 로봇 결합 메커니즘에 따른 결합 알고리즘을 제시하였다. 그리고 제안된 구조를 실제 구현하여 구조의 유용성을 검증하였다.

• 정보처리학회논문지A
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• 제19A권2호
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• pp.73-76
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• 2012

본 논문에서는 단백질 분자로부터 표면 원자를 효율적으로 발견하는 알고리즘을 제안한다. 표면 원자란, 주어진 probe solvent $P$가 단백질 분자와 충돌하지 않고 접한다고 가정할 때, $P$와 접할 수 있는 원자의 집합을 의미한다. 단백질 분자를 구성하는 원자들은 반데르바스 반경을 갖는 구의 집합으로 표현되며, probe solvent 역시 구로 대응된다. $P$의 반경에 대해 분자의 오프셋 곡면을 구하여 표면 원자를 발견하는 알고리즘을 제안한다. 제안된 알고리즘은 각 구의 오프셋 곡면에 대해 복셀 맵(voxel map)을 구성하여 효율적으로 분자의 오프셋 곡면을 구하며, GPU (graphic processor unit)를 활용한 병렬처리를 수행하여 최대 6,412개의 원자를 갖는 분자에 대해 42.87 millisecond 내에 표면 원자를 발견한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.203-208
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• 2006

The main research conducted previously on GPS ionosphere in China is first introduced. Besides, the current investigations include as follows: (1) GPS-based spatial environmental, especially the ionosphere, monitoring, modeling and analysis, including ground/space-based GPS ionosphere electron density (IED) through occultation/tomography technologies with GPS data from global/regional network, development of a GNSS-based platform for imaging ionosphere and atmosphere (GPFIIA), and preliminary test results through performing the first 3D imaging for the IED over China, (2) The atmospheric and ionospheric modeling for GPS-based surveying, navigation and orbit determination, involving high precisely ionospheric TEC modeling for phase-based long/median range network RTK system for achieving CM-level real time positioning, next generation GNSS broadcast ionospheric time-delay algorithm required for higher correction accuracy, and orbit determination for Low-Earth-orbiter satellites using single frequency GPS receivers, and (3) Research products in applications for national significant projects: GPS-based ionospheric effects modeling for precise positioning and orbit determination applied to China's manned space-engineering, including spatial robot navigation and control and international space station intersection and docking required for related national significant projects.

• 컴퓨터교육학회논문지
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• 제12권4호
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• pp.57-64
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• 2009

단백질 구조 비교는 각 단백질에 존재하는 수많은 원자들을 처리해야 하므로 많은 컴퓨팅 자원을 요구하는 작업이다. 이러한 작업을 처리하기 위한 접근법으로써 그리드 환경에서 시간 소모가 큰 계산 작업을 분산 처리하는 것이 널리 사용되어 왔다. 그러나 이러한 그리드 환경을 통제하는 것은 비전문가들에게 쉽지 않을 수 있다. 본 논문에서는 비전문가들도 쉽게 그리드 환경을 통제할 수 있는 JXTA 기반의 단백질 구조 비교 시스템을 제안한다. 쿼리 단백질과 비슷한 단백질들을 찾기 위해 사전처리 단계 와 인식단계로 구성된 기하학적 해싱 알고리즘이 사용되었다. 실험 결과에 의하면 주어진 쿼리 단백질 구조와 일치하는 단백질 구조를 시스템이 정확히 찾고 또한 제안된 시스템은 쉽게 단백질 다킹 문제를 해결하도록 확장될 수도 있다. 본 논문에서 제안하는 시스템은 비전문가들, 특히 생물학이나 화학을 전공하는 대학생들처럼 일반적으로 분산 시스템에 대한 숙련된 지식이 없는 사용자들에게 도움이 되리라 기대된다.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2004년도 The 3rd Annual Conference for The Korean Society for Bioinformatics Association of Asian Societies for Bioinformatics 2004 Symposium
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• pp.181-190
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• 2004

The docking and in silico ligand screening procedures can select small sets of lead -like candidates from large libraries of either commercially or synthetically available compounds; however, the vast number of such molecules make the potential size of this task enormous. To accelerate the discovery of drugs to inhibit several targets, we have exploited massively distributed computing to screen compound libraries virtually. The Korea@HOME project was launched in Feb. 2002, and one year later, more than 1200 PC's have been recruited. This has created a 31 -gigaflop machine that has already provided more than 1400 hours of CPU time. It has all owed databases of millions of compounds to be screened against protein targets in a matter of days. Now, the virtual screening software suitable for distributed environments is developed by BMD. It has been evaluated in terms of the accuracy of the scoring function and the search algorithm for the correct binding mode.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3759-3765
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• 2015

Background: Approaches in disruption of MDM2-p53 interactions have now emerged as an important therapeutic strategy in resurrecting wild type p53 functional status. The present study highlights virtual screening strategies in identification of high affinity small molecule non-peptidic inhibitors. Nutlin3A and RG7112 belonging to compound class of Cis-imidazoline, MI219 of Spiro-oxindole class and Benzodiazepine derived TDP 665759 served as query small molecules for similarity search with a threshold of 95%. The query molecules and the similar molecules corresponding to each query were docked at the transactivation binding cleft of MDM2 protein. Aided by MolDock algorithm, high affinity compound against MDM2 was retrieved. Patch Dock supervised Protein-Protein interactions were established between MDM2 and ligand (query and similar) bound and free states of p53. Compounds with PubCid 68870345, 77819398, 71132874, and 11952782 respectively structurally similar to Nutlin3A, RG7112, Mi219 and TDP 665759 demonstrated higher affinity to MDM2 in comparison to their parent compounds. Evident from the protein-protein interaction studies, all the similar compounds except for 77819398 (similar to RG 7112) showed appreciable inhibitory potential. Of particular relevance, compound 68870345 akin to Nutlin 3A had highest inhibitory potential that respectively showed 1.3, 1.2, 1.16 and 1.26 folds higher inhibitory potential than Nutilin 3A, MI 219, RG 7112 and TDP 1665759. Compound 68870345 was further mapped for structure based pharamacophoric features. In the study, we report Cis-imidazoline derivative compound; Pubcid: 68870345 to have highest inhibitory potential in blocking MDM2-p53 interactions hitherto discovered.