• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.141-145
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• 2005

In this paper, UWB system did research about effect that interference effect with neighborhood single equipment or nearby group equipment gets In DMB service. 2.6425GHz satellite digital multimedia broadcasting service(SDMB) that electric wave interference special quality is contiguity frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect degree that get in service did comparative analysis. SDMB system was BER $1{\times}10^{-4}$ that interference effect happens from 6.5m point and broadcasting signal reception is possible at 4m point. Also, it was BER $1{\times}10^{-4}$ that interference effect begins to happen from 5.0m point about center frequency 3.4126GHz and broadcasting signal reception is possible at 2m point. And, confirmed that UWB system of impulse method is less interference effect about 2 dB than UWB system of OFDM method, to electric wave of UWB system that is small output

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.55-57
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• 2007

A Power control and Distribution Unit (PCDU) plays roles of protection of battery against overcharge by active control of solar array generated power, distribution of unregulated electrical power via controlled outlets to bus and instrument units, distribution of regulated electrical power to selected bus and instrument units, and provision of status monitoring and telecommand interface allowing the system and ground operate the power system, evaluate its performance and initiate appropriate countermeasures in case of abnormal conditions. In this work, we perform the preliminary design of a PCDU for the small Low Earth Orbit (LEO) Satellite applications. The main constitutes of the PCDU are the battery interface module, solar array regulators with maximum power point tracking (MPPT) technology, heater power distribution modules, internal converter modules for regulated bus voltage generation, power distribution modules of unregulated and regulated primary bus, and instrument power distribution modules.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.323-328
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• 2007

A direct application of liquefied gas propellants to a typical small satellite cold gas propulsion system was analyzed. Performance of systems using liquefied gas propellant under consideration was compared to that of a nitrogen cold gas propulsion system. Liquefied gas propellant propulsion system's performance, required tank volume, and required propulsion system mass has been calculated at the same mass, volume, and total impulse condition of a typical nitrogen cold gas propulsion system. It was found that the liquefied gas propulsion system has advantages in performance, volume, and mass, compared to a typical nitrogen cold gas system, and can be directly applied to a cold gas propulsion system.

• Korean Journal of Remote Sensing
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• v.17 no.3
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• pp.189-197
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• 2001

Generally, remote sensing is useful to obtain the quantitative and qualitative information of a wide area. For monitoring earth resources and environment, land cover classification of remotely sensed data are needed over increasingly larger area. The objective this study is to propose the process for land cover classification method over a wide area using multi-scene satellite data. Land cover of Korean peninsula was extracted from a Landsat TM and ETM+ mosaic created from 23 scenes at 100-meter resolution. Well-known techniques that used to general image processing and classification are applied to this wide area classification. It is expected that these process is very useful to promptly and efficiently grasp of small scale spatial information such as national territorial information.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.445-452
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• 2008

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images, In the next step, we examine the technique when the dual-polarization data are split into two multi-look images, It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking, It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

• ETRI Journal
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• v.43 no.2
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• pp.221-231
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• 2021

To resolve energy depletion issues in massive Internet of Things sensor networks, we developed a set of distributed energy beamforming methods with one-bit feedback and clustering for multi-node wireless energy transfer, where multiple singleantenna distributed energy transmitters (Txs) transfer their energy to multiple nodes wirelessly. Unlike previous works focusing on distributed information beamforming using a single energy receiver (Rx) node, we developed a distributed energy beamforming method for multiple Rx nodes. Additionally, we propose two clustering methods in which each Tx node chooses a suitable Rx node. Furthermore, we propose a fast distributed beamforming method based on Tx sub-clustering. Through computer simulations, we demonstrate that the proposed distributed beamforming method makes it possible to transfer wireless energy to massive numbers of sensors effectively and rapidly with small implementation complexity. We also analyze the energy harvesting outage probability of the proposed beamforming method, which provides insights into the design of wireless energy transfer networks with distributed beamforming.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.195-207
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• 2021

In recent years, with the rapid growth of China's animation industry, the two-dimensional culture and consumption have been immersed in the daily lives of young people. The two-dimensional culture that mainly exists on young people is gradually entering the public's field of vision, making the two-dimensional culture not It is only restricted to the fixed fan circle, but is known to more people outside the circle. At the same time, the "barrage" (screen text) cultures in video websites has become popular with some film and television works, Internet terms, etc., and has attracted the attention on mainstream culture. On the one hand, its cultural products have appeared on traditional mainstream video websites and advertisements on provincial satellite TV. And in the program, on the other hand, a small part of the screen text and cultural terms are also used by some celebrities and other ordinary people who don't understand the meaning of the terms at all, and have caused widespread dissemination. Sometimes the video website itself is also mentioned, which obviously shows a difference. The tendency towards a kind of screen texts subculture to penetrate the mainstream culture.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.4
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• pp.77-85
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• 2018

Rapid urbanization has fostered development of modern cities. Although Conventional zoning played its role to control urban development, it also segregated land uses and created homogeneous development pattern. Mega cities with satellite bed towns has not shown their unique identity and characters. In order to develop comprehensive approach which may bring social and physical enhancement can be difficult to achieve by considering city as a two dimensions. On contrary, extensive analysis and proposals require an approach which can perceive city with three dimensions. Form-Based Codes (FBCs) are appeared as an alternative to conventional zoning with different design process and principles. FBCs approach urban place with three dimension and giving priority to form rather than land use. The purpose of this study was to analyze the necessity of FBCs and its concept, components and how this would change urban characteristics in the aspects of architectural design through analysis on 4 case studies for zoning codes of US cities. Through comparison of components in Form-Based Codes of 4 different cases, this study can show the reasons for differences in application of Form-Based Codes and how detailed components would play a role to establish better urban environments.

• Journal of Astronomy and Space Sciences
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• v.37 no.4
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• pp.249-255
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• 2020

We develop the tissue-equivalent proportional counter (TEPC) type's space radiation dosimeter to measure in-situ aviation radiation. That was originally developed as a payload of small satellite in the low-earth orbit. This dosimeter is based on a TEPC. It is made of an A-150 tissue-equivalent plastic shell of an internal diameter of 6 cm and a thickness of 0.3 cm. TEPC is filled with pure propane at 13.9 torrs to simulate a cell diameter of 2 ㎛. And the associated portable and low power electronics are also implemented. The verification experiments have been performed by the calibration experiments at ground level and compared with Liulin observation at aircraft altitude during the flight between Incheon airport (ICN) and John F. Kennedy airport (JFK). We found that the TEPC dosimeter can be used as a monitor for space radiation dosimeter at aviation altitude based on the verification with Liulin observation.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.26-26
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• 2022

본 연구는 하천중심선을 활용하여 Sentinel-1 위성영상기반 중소규모 하천 수체(水體) 추출 방법을 제안한다. 한강 유역의 한탄강 일부를 연구지역으로 선정하였으며, 이 지역을 촬영한 Sentinel-1 위성영상자료를 수집하였다. 여기에 개발한 방법의 검증을 위하여 유사시간대의 고해상도 광학위성 PlanetScope을 함께 수집하였다. 본 연구에서는 하천의 수체를 효과적으로 추출하기 위하여 국토지리정보원에서 제공하는 하천중심선 자료를 활용하였다. 하천중심선을 따라 유클리드 거리를 가중치로 산정한 자료(DST)와 Sentinel-1의 VH, VV 편광을 조합한 k-means 방법을 통해 위성영상의 픽셀을 군집화하였고, 최적의 매개변수 값을 산출하였다. 이 매개변수를 활용하여 Sentinel-1의 VV편광, VH편광 그리고 DST의 상관관계에 따른 타원방정식 형태의 계산식을 도출할 수 있었다. 수집한 자료의 검증결과 평균적으로 정확도는 0.65~0.75, kappa 계수는 0.8 내외를 보여 상당히 일치함을 확인할 수 있었다. 또한, 추가 확보한 30여 개의 Sentinel-1 위성영상을 제안 방법으로 추출한 수체의 면적과 유량 값을 비교해 본 결과, 유사한 변화 양상을 보였다. 본 연구는 하천 중심선자료를 활용하여 참값이 없더라도 수체 면적 추정이 가능함을 확인하였다. 제안한 방법은 현존하는 수체추출 방법보다 간단하고 신속하게 수체를 추출할 수 있을 것으로 보인다. 추후, 딥러닝을 통한 수체 식별을 추가 진행을 통해. 정확도를 높일 수 있을 것으로 기대한다.