• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.72.4-73
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• 2018

북극 스발바르의 사면 지형에는 걸리가 발달되어 있다. 이러한 걸리는, 그 성인에는 여러 의견이 있으나, 화성에도 중고위도를 중심으로 다수 분포한다. 화성의 걸리는 2000년대에 들어 비로소 본격적으로 규명되고 있으나, 지형적 특성으로 인한 탐사의 한계로 지구에 분포하는 유사지형을 통한 비교 연구가 일반적이다(Costard, et al. 2007 등). 이 연구에서는 스발바르의 주도 롱이어비엔에서 UAV을 이용하여 획득한 DEM으로 스발바르 걸리를 측량하고, 이를 화성 중위도의 테라 사이메리아, 테라 시레넘, 노아 키스 테라에 분포하는 걸리와 비교하였다. Longyearbreen 빙하 전방에 위치한 사면을 UAV로 촬영하고, 이를 SfM-MVS(Structure from Motion & MultiView Stereo) 기법으로 3차원 점군 모델과 고해상도 DEM을 제작하여 분석하였다. 화성의 경우 MRO궤도 탐사선이 촬영한 HiRise DTM을 이용하여 분석하였다. 두 걸리는 기후와 지질 조건에 차이가 있음에도 불구하고 유사한 패턴을 보였다. 특히 테라 사이메리아에 위치한 걸리와 롱이어비엔 북사면의 걸리는 기준거리, 단면적, 폭, 경사, 제방 두께 등에서 상당한 정량적 유사관계가 있었다. 이는 두 행성의 걸리가 유사한 성인 및 형성 프로세스를 거쳤을 가능성을 시사한다. 측량 기법과 UAV 의 안정성을 개선시키면 지형 모델의 품질 향상 및 극지에서의 UAV 운용이 용이해질 것으로 기대된다. 또한 스발바르의 기후 요소 및 물리량 적용은 향후 화성 지형연구에도 응용할 수 있을 것으로 사료된다.

• Journal of Astronomy and Space Sciences
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• v.14 no.1
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• pp.24-32
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• 1997

We have calculated the velocity distribution of wind driven by Alfven waves. The assumed initial number density of wind can affect the line profiles because it produces the change in the velocity distribution under the mass conservation. Initial density $N_O=5.5{\times}10^{12}/cm^3$ is chosen for a proper initial density from the observation by Schroder(1986). The wind models for $N_O=10^9,10^{10},10^{11},5.5{\times}10^{12}/cm^3$ are calculated at ${phi}$=0.06 and ${phi}$=0.78. The line profiles for lower initial density show the strong emissions and narrow absorptions because of their steeper velocity gradients.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.1
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• pp.8-14
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• 2015

Transmission of a tracked vehicle designed for multiple functions such as steering, gear-shifting, and braking is a core component of heavy vehicle to which the power is transferred based on combined technology of various gears, bearing, and fluid machineries. Robustness and durability of transmission, however, have been issued due to a large number of driving units and sub-components inside its body. Particularly, transmission housing is important structure which supports the transmission, and is made of aluminum alloy. Thus, structural robustness against such mechanical loading or vibration must be attained. Structural reliability evaluation through FEM analysis can save time and cost of the actual tests. In this study, structural evaluation is conducted on output housing of transmission, which is core component of tracked vehicle, using the simulation program. In addition, transmission dynamo test is performed to evaluate structural robustness of the output housing against the vibration which can be produced during the transmission operation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.183.1-183.1
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• 2013

70 MeV 사이클로트론의 인젝션 빔 라인은 Multi-CUSP 이온원에서 인출된 H- 빔을 펄스 또는 번칭하여 인플렉터를 통해 사이클로트론의 가속영역인 Dee로 전송하는 역할을 한다. 이 때, 빔을 번칭 시킴으로써 가속효율을 높이고, 손실을 줄여 높은 전류의 빔을 공급할 수 있도록 해야한다. 인젝션 시스템은 einzel lens, chopper, buncher, solenoid 등으로 구성된다. Einzel lens는 빔을 buncher의 중심으로 집속시켜 buncher의 번칭 효율을 높이고, buncher는 전기장을 이용하여 빔을 진행방향으로 집속시키는 기능을 갖는다. Chopper는 번칭된 빔을 일정 주기로 편향을 시켜 펄스 빔의 형태로 전송하는 역할을 한다. 솔레노이드는 적절한 자기장을 이용하여 빔을 집속시켜 인플렉터로 전송한다. 본 연구에서는 사이클로트론의 고전류 인젝션 시스템을 구축하고 각각의 구성요소에서 빔 envelope를 계산하고 비교하였다. SIMION code는 user가 지정한 특성을 가진 개별 입자의 궤도를 추적하는 프로그램으로 인젝션 시스템을 구성하는 각각의 컴포넌트에서의 입자의 진행모습과 buncher를 이용하여 빔의 전송 밀도가 향상됨을 확인하였다. 아울러 TRANSPORT 및 TURTLE 프로그램을 이용하여 SIMION을 통해 계산된 빔의 envelope과 비교하였다.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.558-564
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• 1992

Product yields were determined for the reaction of styrene with sodium hypochlorite (NaOCl) in CH$_2$Cl$_2$ with various substituted manganese porphyrin complexes as catalysts. In the presence of the electron withdrawing group and ortho-substituted manganese porphyrin complexes, reaction rate and epoxide selectivity are increased. Also reaction rate and epoxide selectivity are largely increased by the presence of imidazole which behaves as axial ligand of the manganese porphyrin complexes. By the kinetic study with Michealis-Menten equation, the factor significantly affected to catalytic ability is $K_m$ value. A large binding affinity consists with the low $K_m$. With theoretical analysis by EHMO calculation, the results are in good agreement with experimental data.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.826-832
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• 2016

Reduced greenhouse gas effect induced by LID (Low Impact Development) technique application in tramway construction was quantified to increase environmental benefit as part of an overall economic assessment. In addition, by application of penetration type permeable blocks, the effect of the urban water cycle was examined as a special assessment item in the policy analysis. The carbon emission ratios of the permeable turf block, according to the turf coverage rate (100%, 50% granite, and 50% HDPE), against the concrete track construction were -184.7%, -127.3%, and -116.3%, respectively. The carbon emission ratios of permeable blocks with granite and HDPE were 30.1% and 52.5%. In the case of the penetration type permeable block, it was possible to store rainfall in the block until 90mm/hr of rainfall intensity (94.3% of water reserve rate); therefore, this method was effective as part of the urban water cycle system. As a result, an increased environmental benefit from LID technique application is expected in tramway construction; this needs to be considered as a policy factor in AHP analysis.

• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.7-13
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• 2015

The number of mobile terminals equipped with a GPS module is steadily increasing today. However, because they using code pseudorange measurements in positioning, the positioning accuracy of mobile terminals is lower than that of those receivers using carrier phases. Especially, the multipath signal causes more significant errors in code pseudoranges. Therefore, the techniques of multipath detection and elimination is necessary. In this study, as an initial analysis of multipath detection and elimination technique development, we tested the feasibility of multipath signal detection using GPS signal strength information. We found that the GPS signal strength increases as the elevation angle gets higher in the open-sky environment. Also, we found that the signal strength decreases when there were some signal reflectors nearby. We checked the repeatability of the signal strength variation characteristics by reflecting repeat time of GPS satellites. As a result, this characteristics repeats almost perfectly when GPS satellites pass the same orbit. Therefore, we found that it is not a temporary phenomenon and the multipath signal detection should be possible by using GPS signal strength information.

• Korean Journal of Remote Sensing
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• v.37 no.5_3
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• pp.1405-1423
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• 2021

Precipitation is one of the main factors that affect water and energy cycles, and its estimation plays a very important role in securing water resources and timely responding to water disasters. Satellite-based quantitative precipitation estimation (QPE) has the advantage of covering large areas at high spatiotemporal resolution. In this study, machine learning-based rainfall intensity models were developed using Himawari-8 Advanced Himawari Imager (AHI) water vapor channel (6.7 ㎛), infrared channel (10.8 ㎛), and weather radar Column Max (CMAX) composite data based on random forest (RF). The target variables were weather radar reflectivity (dBZ) and rainfall intensity (mm/hr) converted by the Z-R relationship. The results showed that the model which learned CMAX reflectivity produced the Critical Success Index (CSI) of 0.34 and the Mean-Absolute-Error (MAE) of 4.82 mm/hr. When compared to the GeoKompsat-2 and Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN)-Cloud Classification System (CCS) rainfall intensity products, the accuracies improved by 21.73% and 10.81% for CSI, and 31.33% and 23.49% for MAE, respectively. The spatial distribution of the estimated rainfall intensity was much more similar to the radar data than the existing products.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.384-386
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• 2014

As the type of property data of military terrain analysis map is using FACC of DIGEST, there is a limitation in utilizing a domestic thematic map which is in use of other type of property data. However, even though the attempts to utilize the domestic thematic map are made at military sites, the study has not been conducted enough. Therefore, we defined it by matching the property data necessary for the military terrain analysis cartography and property of the domestic thematic map, and analyzed in accordance with the method to analyze the cross-country movement roads specified in FM 5-33. But, there was no data for the diameter of trees in the vegetation map among a terrain analysis map, whereas there being data for the sort of trees. As the diameter of trees can be broken through to the extent of certain diameters by tracked vehicles, they are the factors necessary in analyzing. In this study, the research was conducted focusing on calculating the diameters for some trees described in a stand yield table by using the age-class for trees in a forest floor map with a scale of 1:5000 and calculating the diameters of trees by using the diameter-class for the diameters of other trees.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1615-1627
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• 2020

The purpose of this study is to compare and analyze the performance of KOMPSAT-3 Digital Surface Model (DSM) made in overseas testbed area. To that end, we collected the KOMPSAT-3 in-track stereo image taken in San Francisco, the U.S. The stereo geometry elements (B/H, converse angle, etc.) of the stereo image taken were all found to be in the stable range. By applying precise sensor modeling using Ground Control Point (GCP) and DSM automatic generation technique, DSM with 1 m resolution was produced. Reference materials for evaluation and calibration are ground points with accuracy within 0.01 m from Compass Data Inc., 1 m resolution Elevation 1-DSM produced by Airbus. The precision sensor modeling accuracy of KOMPSAT-3 was within 0.5 m (RMSE) in horizontal and vertical directions. When the difference map was written between the generated DSM and the reference DSM, the mean and standard deviation were 0.61 m and 5.25 m respectively, but in some areas, they showed a large difference of more than 100 m. These areas appeared mainly in closed areas where high-rise buildings were concentrated. If KOMPSAT-3 tri-stereo images are used and various post-processing techniques are developed, it will be possible to produce DSM with more improved quality.