• 한국항공우주학회지
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• 제40권9호
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• pp.752-759
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• 2012

본 논문에서는 태양동기성 유지 및 지상궤적 반복이 요구되는 위성의 궤도 설계 방법에 대한 연구를 수행하였다. 특히, 위성 궤도 해석 및 공학 문제에서 빈번하게 사용되는 상용소프트웨어 (STK, MATLAB)를 활용한 "비선형 시뮬레이션 기반 수치 최적화" 기법을 제안하고자 한다. 설계 과정에서 위성에 미치는 다양한 교란력을 고려함으로써, 태양 동기성과 지상궤적 반복과 같은 임무 요구 사항을 더 정확하게 만족할 뿐만 아니라, 위성 지방시 변화 최소화, 특정 지상국과 접촉 시간 최대화와 같이 실제 위성 운용시 현실적으로 요구되는 사항을 설계에 반영할 수 있다. 저궤도 태양동기궤도 위성을 대상으로 설계 예제를 제시하였고, 본 연구의 타당성을 검증하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1197-1199
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• 2003

ROCSAT-2 mission is to daily image over Taiwan and the surrounding area for disaster monitoring, land use, and ocean surveillance during the 5-year mission lifetime. The satellite will be launched in December 2003 into its mission orbit, which is selected as a 14 rev/day repetitive Sun-synchronous orbit descending over (120 deg E, 24 deg N) and 9:45 a.m. over the equator with the minimum eccentricity. National Space Program Office (NSPO) is developing a ROCSAT-2 Image Processing System (IPS), which aims to provide real-time high quality image data for ROCSAT-2 mission. A simulated ROCSAT-2 image, based on Level 1B QuickBird Data, is generated for IPS verification. The test image is comprised of one panchromatic data and four multispectral data. The qualification process consists of four procedures: (a) QuickBird image processing, (b) generation of simulated ROCSAT-2 image in Generic Raw Level Data (GERALD) format, (c) ROCSAT-2 image processing, and (d) geometric error analysis. QuickBird standard photogrammetric parameters of a camera that models the imaging and optical system is used to calculate the latitude and longitude of each line and sample. The backward (inverse model) approach is applied to find the relationship between geodetic coordinate system (latitude, longitude) and image coordinate system (line, sample). The bilinear resampling method is used to generate the test image. Ground control points are used to evaluate the error for data processing. The data processing contains various coordinate system transformations using attitude quaternion and orbit elements. Through the qualification test process, it is verified that the IPS is capable of handling high-resolution image data with the accuracy of Level 2 processing within 500 m.

• 항공우주시스템공학회지
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• 제16권5호
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• pp.49-56
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• 2022

S-STEP 은 관심 지역의 시한성 긴급 표적 및 군사적 이상 징후를 감시하기 위한 초소형 SAR 위성 임무로, 고도 510 km의 저궤도에 32 대의 위성군을 배치하여 관심 지역에 대해 평균 재방문 주기를 30 분 이하로 달성한다. S-STEP의 임무 운용 모드는 표준 모드, 관측 모드, 통신 모드, 궤도유지 모드 등으로 구분되며, 이에 따라 자세 기동 모드 역시 초기 각속도 안정화, 태양 지향, 목표지점 및 지상국 지향, 추력 방향 유지 등으로 세분화된다. 이 연구에서는 S-STEP 임무 운용 시나리오의 예비 설계 결과와 위성체의 특성을 바탕으로 초기 각속도 안정화 및 태양 지향 모드와 관측 궤도 운용 모드에서의 자세 성능을 분석하였다. 분석 결과, 할당된 시간 이내에 필요한 자세 제어를 완료하여 각 모드에서 요구되는 자세 제어 정확도를 달성함을 확인하였다.

• Advances in nano research
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• 제13권4호
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• pp.325-339
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• 2022

Endophytes ascertain a symbiotic relationship with plants as promoters of growth, defense mechanism etc. This study is a first report to screen the endophytic population in Waltheria indica, a tropical medicinal plant. 5 bacterial and 3 fungal strains in leaves, 3 bacterial and 1 yeast species in stems were differentiated morphologically and identified by biochemical and molecular methods. The phylogenetic tree of the isolated endophytes was constructed using MEGA X. Silver nanoparticles were biosynthesized from a rare endophytic bacterium Cupriavidus metallidurans isolated from the leaf of W. indica. The formation of silver nanoparticles was confirmed by UV-Visible spectrophotometer that evidenced a strong absorption band at 408.5 nm of UV-Visible range with crystalline nature and average particle size of 16.4 nm by Particle size analyzer. The Fourier Transform Infra-Red spectrum displayed the presence of various functional groups that stabilized the nanoparticles. X-ray diffraction peaks were conferred to face centered cubic structure. Transmission Electron Microscope and Scanning Electron Microscope revealed the spherical-shaped, polycrystalline nature with the presence of elemental silver analyzed by Energy Dispersive of X-Ray spectrum. Selected area electron diffraction also confirmed the orientation of AgNPs at 111, 200, 220, 311 planes similar to X-ray diffraction analysis. The synthesized nanoparticles are evaluated for antimicrobial activity against 7 bacterial and 3 fungal pathogens. A good zone of inhibition was observed against pathogenic bacteria than fungal pathogens. Thus the study could hold a key aspect in drug discovery research and other pharmacological conducts of human clinical conditions.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.367-377
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• 2015

Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK$^{(R)}$) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK$^{(R)}$ Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

• 한국융합학회논문지
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• 제11권1호
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• pp.359-367
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• 2020

본 연구는 간호창업 관련 문헌에서 나타난 간호창업의 관심 주제 및 간호창업 경험의 속성, 간호창업의 방향성을 탐색하기 위해 시행되었다. MEDLINE, Embase, Cochrane Library DB를 통해 55편의 간호창업 관련 문헌을 선정하여 덱스트 네트워크 분석 방법을 적용하여 분석하였다. 분석결과 단순출현 빈도와 연결중심성에서 공통적인 핵심키워드는 'business', 'care', 'nursing', 'healthcare', 'service'으로 나타났다. 연결중심성에서 높은 순위를 보이는 키워드는 'mission', 'vision', 'team'으로 나타났다. 이에 본 연구결과가 체계적인 간호창업 교육프로그램과 간호창업 이론 개발의 기초 자료로 활용 될 수 있을 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.48-53
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• 2014

Rocket, held using the CCA for the mission, a plurality of recording devices, and navigation equipment. In case of a projectile which is entered the water after fired into the air, after performing stages and fairing separated in flight to enter the underwater. It is caused by the explosion of gunpowder mainly, vibration phenomenon of a large transition is induced structurally very, also on entering the water, have a significant shock structurally separated. If shock is transmitted directly to the CCA through the body, it can be caused malfunction of payloads, resulting in failure of the mission of the projectile. In order to ensure the stability against shock, in this paper, Calculating a target resonacne frequency of the CCA, and verified through modal test and analysis. Maximum acceleration position of CCA is checked by SRS analysis. In addition, effectiveness of shock isolation system through shock analysis.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.51-60
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• 2017

In this study to develop disaster response robot in complex disaster site, we present the design of hydraulic manipulators for armored robot systems. To this end, we performed voice of customer researches with firefighters and rescue personnel. We created and analyzed the mission scenario of firefighters and rescue personnel in complex disaster situations, and derived the required functions of the robot to successfully perform missions. A heavy-duty, heat resistant, dexterous hydraulic robot manipulators is designed to realize the required functions. The designed robot has been verified through simulations and analysis in terms of the working area of the robot, actuating torques, and temperature analysis.

• 항공우주시스템공학회지
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• 제15권1호
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• pp.40-46
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• 2021

본 연구에서는 재난치안무인기 MC-1,2,3 대비 임무능력이 대폭 향상된 임무확장형 무인기 후보인 틸트로터 무인기의 공력형상설계와 성능향상을 위한 연구를 수행하였다. 기존 운영 중인 TR60 틸트로터 무인기의 형상을 근간으로 성능향상을 위하여 동체 및 꼬리날개 형상을 개선하고 나셀에 확장날개를 장착한 새로운 TR5X 개념형상을 설계하고 전산유체해석을 통해 기존 TR60과 공력성능을 비교하였다. 또한 TR5X 전기체 공력데이터를 구축하고 전기체 비행성능해석을 수행하여 목표로 설정된 주요 성능요구도가 만족됨을 확인하였다.

• 공학교육연구
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• 제27권2호
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• pp.3-12
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• 2024

The purpose of this study was to evaluate how well the 2020 vision presented by the Accreditation Board for Engineering Education of Korea(ABEEK) had been achieved, and to objectively examine the social status. It was very necessary for the development of engineering education in Korea to provide room for improvement by diagnosing how well the ABEEK, one of the major engineering education communities, was achieving its own vision. In order to achieve the objectives of the study, research methods such as literature review, survey research, and expert advisory committee were used. To evaluate the level of achievement of the Vision 2020 of the ABEEK, the analysis was based on the response results of 61 people who had experience as a member of the steering committe. In addition, the vision and mission of the 23 countries that are currently signatory members of the Washington Accord were surveyed, and the social responsibility and financial independence of the 20 countries that joined the signatory member countries before 2020 were compared with each other. As a result of the analysis, the item of securing international equivalence in engineering education received the most positive evaluation, and the social compensation efforts for accreditied graduates received the least evaluation. The ABEEK was evaluated as having a medium level of social responsibility and a low level of financial independence. Based on the results of this research, we proposed ways the ABEEK to contribute to the improvement of Korean engineering education.