• Ocean and Polar Research
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• 제27권2호
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• pp.189-195
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• 2005

Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.82-84
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• 2003

Watershed boundaries and flow paths within the watershed are the most important factors required in watershed analysis. Most often the derivation of watershed boundaries and stream network and flow paths is based on topographical maps but spatial variation of flow direction is not clearly understandable using this method. Water resources projects currently use 1: 50, 000-scale ground survey or aerial photography-based topographical maps to derive watershed boundary and stream network. In basins, where these maps are not available or not accessible it creates a real barrier to watershed geo-spatial analysis. Such situations require the use of global datasets, like GTOPO30. Global data sets like ETOPO5, GTOPO30 are the only data sets, which can be used to derive basin boundaries and stream network and other terrain variations like slope aspects and flow direction and flow accumulation of the watershed in the absence of topographic maps. Approximately 1-km grid-based GTOPO 30 data sets can derive better outputs for larger basins, but they fail in flat areas like the Karkheh basin in Iran and the Amudarya in Uzbekistan. A new window in geo-spatial hydrology has opened after the launching of the space-borne satellite stereo pair of the Terra ASTER sensor. ASTER data sets are available at very low cost for most areas of the world and global coverage is expected within the next four years. The DEM generated from ASTER data has a reasonably good accuracy, which can be used effectively for hydrology application, even in small basins. This paper demonstrates the use of stereo pairs in the generation of ASTER DEMs, the application of ASTER DEM for watershed boundary delineation, sub-watershed delineation and explores the possibility of understanding the drainage flow paths in irrigation command areas. All the ASTER derived products were compared with GTOPO and 1:50,000-based topographic map products and this comparison showed that ASTER stereo pairs can derive very good data sets for all the basins with good spatial variation, which are equal in quality to 1:50,000 scale maps-based products.

• 대한원격탐사학회지
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• 제40권1호
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• pp.1-8
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• 2024

Busan is the 6th largest port city in the world, where nitrogen dioxide (NO₂) emissions from transportation and port industries are significant. This study aims to assess the NO₂ products of the Geostationary Environment Monitoring Spectrometer (GEMS) over Busan using ground-based instruments (i.e., surface in-situ network and Pandora). The GEMS vertical column densities of NO₂ showed reasonable consistency in the spatiotemporal variations, comparable to the previous studies. The GEMS data showed a consistent seasonal trend of NO₂ with the Korea Ministry of Environment network and Pandora in 2022, which is higher in winter and lower in summer. These agreements prove the capability of the GEMS data to monitor the air quality in Busan. The correlation coefficient and the mean bias error between the GEMS and Pandora NO₂ over Busan in 2022 were 0.53 and 0.023 DU, respectively. The GEMS NO₂ data were also positively correlated with the ground-based in-situ network with a correlation coefficient of 0.42. However, due to the significant spatiotemporal variabilities of the NO₂, the GEMS footprint size can hardly resolve small-scale variabilities such as the emissions from the road and point sources. In addition, relative biases of the GEMS NO₂ retrievals to the Pandora data showed seasonal variabilities, which is attributable to the air mass factor estimation of the GEMS. Further studies with more measurement locations for longer periods of data can better contribute to assessing the GEMS NO₂ data. Reliable GEMS data can further help us understand the Asian air quality with the diurnal variabilities.

• 한국정보과학회논문지:소프트웨어및응용
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• 제34권1호
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• pp.79-94
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• 2007

언제, 어디서, 누구나 대용량 네트워크를 사용할 수 있는 유비쿼터스(ubiquitous) 시대가 다가오면서, 카메라가 장착되어 있고 무선 통신이 가능한 PDA, 웨어러블(wearable) 컴퓨터와 같은 휴대용 장치가 가까운 미래에는 일상의 한 부분이 될 것이다. 이런 상황을 반영하듯, 휴대용 장치를 이용한 실감형 게임(augmented game)에 관한 다양한 연구가 진행되어 왔다. 기존의 실감형 게임들은 전통적으로 'backpack' 시스템이나 패턴마커(pattern marker)를 이용하였다. 'backpack' 시스템은 비싸고, 거추장스러우며, 사용하기 불편한 단점이 있으며, 패턴마커를 사용하면 미리 정한 장소에서만 게임을 해야 하는 단점을 가지고 있다. 본 논문에서 소개하는 게임 Flying Cake는 거추장스러운 장비 대신, 가볍고 휴대 가능한 PDA를 이용하며, 실제 세계에서 가상의 물체를 접목(overlay)하기 위해, 수동적인 패턴마커 대신 얼굴 영역을 이용한다. Flying Cake는 PDA만을 이용하여 실제 세계를 돌아다니며 카메라에 의해 입력된 영상에 접목된 가상의 캐릭터를 공격하는 일인용과 무선 랜을 통해 전송되는 상대방의 영상에 접목된 가상의 캐릭터를 공격하는 이인용을 제공하는 실감형 슈팅 게임이다. 얼굴 추출 기술을 이용하여 입력 영상의 얼굴영역에 가상의 캐릭터를 접목하며, 사용자는 가상의 캐릭터를 공격하며 게임을 즐긴다. Flying Cake는 얼굴 추출 기술을 이용하여 PDA카메라를 통해 입력된 실제 세계와 가상의 물체 사이의 상호작용을 제공하는 새로운 패러다임(paradigm)을 제공함으로써 사용자에게 새로운 즐거움을 제공할 것이다.

• 직업교육연구
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• 제35권6호
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• pp.85-112
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• 2016

이 연구는 2000년부터 2015년까지 평생 직업교육훈련 분야에 게재된 학술논문을 바탕으로 연구자 간의 협력관계 및 네트워크 구조를 살펴보는 데 목적이 있다. 이를 위해 평생 직업교육훈련 분야의 대표적인 학술지인 "평생교육학연구", "직업교육연구", "고용직업능력개발연구"의 연구자 간 사회적 관계와 학술적 영향력의 특성에 대해 파악하고자 NetMiner 4.0을 활용하여 공저자 네트워크 분석을 실시하였다. 분석 결과, 평생 직업교육훈련 분야의 연구 생산성은 멱함수의 형태를 나타내고, 세부 연구 집단이라고 할 수 있는 컴포넌트들이 존재하며 이 네트워크 구조는 좁은 세상의 특성을 나타내고 있었다. 또한 중심성 분석을 통해 연결정도 중심성이 높은 저자는 공동저자로서 다른 연구자들과의 정보 획득과 교류가 활발하여 네트워크상에서 중추적인 역할을 수행하고, 매개 중심성이 높은 저자는 구성원들 사이를 매개해주는 브로커 역할을 하여 여러 집단의 지식과 정보를 전달해주는 통로의 역할을 하고 있음을 알 수 있었다. 과거에 비해 공저자 활동의 증가는 평생 직업교육훈련 분야 연구자 간의 연구협력 기회 및 발전에 긍정적인 영향을 미치는 것으로 해석된다. 그러나 소수의 저자를 중심으로 한 네트워크를 넘어서 다양한 연구자들이 지속적인 연구 생태계를 구성하여 공동연구를 수행하는 성과로 이어지기를 기대한다.

• 대기
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• 제25권4호
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• pp.719-734
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• 2015

Korea is one of the country with the world's oldest meteorological observation records. Starting with first meteorological record of fog in Goguryeo in the year of 34 BC, Korea had left a great deal of quantitative observation records, from the Three Kingdoms Period to Goryeo to Joseon. During the Joseon Dynasty, with a great attention by kings, efforts were particularly made to measure rainfall in a systematic and scientific manner. In the 23rd year of King Sejong (1441), the world's first rain gauge called "Chugugi" was invented; in the following year (1442), a nationwide rainfall observation network was established. The King Sejong distributed Chugugi to 350 observation stations throughout the state, even to small towns and villages, for measuring and recording rainfall. The rainfall observation using Chugugi, initiated by King Sejong, had been in place for about 150 years, but halted during national disturbances such as Japanese invasion of Korea in 1592. Since then, the observation had been forgotten for a long time until the rainfall observation by Chugugi was resumed in the 48th year of King Yeongjo (1770). King Yeongjo adopted most of the existing observation system established by King Sejong, including the size of Chugugi and observation rules. He, however, significantly reduced the number of Chugugi observation stations to 14, and commanded the 352 local authorities such as Bu, Gun, Hyeon to conduct "Wootaek", a method of measuring how far the moisture had absorbed into the soil when it rains. Later on, six more Chugugi stations were established. If the number of stations of Chugugi and Wootaek are combined together, the total number of rainfall observation station in the late period of Joseon Dynasty was 372. The rainfall observation with Chugugi during the Joseon Dynasty is of significance and excellence in three aspects: 1) the standard size of Chugugi was so scientifically designed that it is as great as today's modern rain gauge; 2) rainfall was precisely measured, even with unit of Bun (2 mm); and 3) the observation network was distributed on a nationwide basis.

• 한국경제지리학회지
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• 제17권4호
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• pp.743-758
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• 2014

우리나라에서 두 번째로 개최된 2012여수세계박람회는 해양을 주제로 2012년 5월부터 8월까지 전남 여수시에서 열렸고, 여러 측면에서 성공적인 메가 이벤트로 평가를 받고 있다. 이 연구의 목적은 여수세계박람회 유치 및 개최를 전후로 해외 언론은 여수를 어떻게 보도해 왔는가를 시기별로, 동 서양으로 구분하여 비교 분석하는 것이다. 분석 결과, 해외 언론들은 여수세계박람회를 기술적 첨단성과 문화적 독창성을 접목시켜 주제를 효율적으로 구현한 엑스포로 평가하였다. 특히 엑스포 유치 전 단계에서는 여수를 한국의 남쪽 끝에 위치한 작은 항구로 보도하였지만, 엑스포 유치 이후 및 개최과정에서는 여수를 엑스포를 개최한 발전 잠재력을 아름다운 항구 도시이자 아시아 무역항로의 중심이며 해양생태 복원의 중심도시로 보도하였다. 이런 해외 언론의 보도 내용과 태도는 엑스포 개최가 여수의 국제적인 도시이미지 변화에 일정한 기여를 하였다고 평가할 수 있다.

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.159-179
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• 2022

Often a network becomes complex, and multiple entities would get in charge of managing part of the whole network. An example is a utility grid. While the entire grid would go under a single utility company's responsibility, the network is often split into multiple subsections. Subsequently, each subsection would be given as the responsibility area to the corresponding sub-organization in the utility company. The issue of how to make subsystems of adequate size and minimum number of interconnections between subsystems becomes more critical, especially in real-time simulations. Because the computation capability limit of a single computation unit, regardless of whether it is a high-speed conventional CPU core or an FPGA computational engine, it comes with a maximum limit that can be completed within a given amount of execution time. The issue becomes worsened in real time simulation, in which the computation needs to be in precise synchronization with the real-world clock. When the subject of the computation allows for a longer execution time, i.e., a larger time step size, a larger portion of the network can be put on a computation unit. This translates into a larger margin of the difference between the worst and the best. In other words, even though the worst (or the largest) computational burden is orders of magnitude larger than the best (or the smallest) computational burden, all the necessary computation can still be completed within the given amount of time. However, the requirement of real-time makes the margin much smaller. In other words, the difference between the worst and the best should be as small as possible in order to ensure the even distribution of the computational load. Besides, data exchange/communication is essential in parallel computation, affecting the overall performance. However, the exchange of data takes time. Therefore, the corresponding consideration needs to be with the computational load distribution among multiple calculation units. If it turns out in a satisfactory way, such distribution will raise the possibility of completing the necessary computation in a given amount of time, which might come down in the level of microsecond order. This paper presents an effective way to split a given electrical network, according to multiple criteria, for the purpose of distributing the entire computational load into a set of even (or close to even) sized computational loads. Based on the proposed system splitting method, heavy computation burdens of large-scale electrical networks can be distributed to multiple calculation units, such as an RTDS real time simulator, achieving either more efficient usage of the calculation units, a reduction of the necessary size of the simulation time step, or both.

• Molecules and Cells
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• 제39권5호
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• pp.367-374
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• 2016

Since the RNA world hypothesis was proposed, a large number of regulatory noncoding RNAs (ncRNAs) have been identified in many species, ranging from microorganisms to mammals. During the characterization of these newly discovered RNAs, RNAs having both coding and noncoding functions were discovered, and these were considered bifunctional RNAs. The recent use of computational and high-throughput experimental approaches has revealed increasing evidence of various sources of bifunctional RNAs, such as protein-coding mRNAs with a noncoding isoform and long ncRNAs bearing a small open reading frame. Therefore, the genomic diversity of Janusfaced RNA molecules that have dual characteristics of coding and noncoding indicates that the functional roles of RNAs have to be revisited in cells on a genome-wide scale. Such studies would allow us to further understand the complex gene-regulatory network in cells. In this review, we discuss three major genomic sources of bifunctional RNAs and present a handful of examples of bifunctional RNA along with their functional roles.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.618-629
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• 2017

Mobile nodes can't always connect each other in DTNs (delay tolerant networks). Many DTN routing protocols that favor the "multi-hop forwarding" are proposed to solve these network problems. But they also lead to intolerant delivery cost so that designing a overhead-efficient routing protocol which is able to perform well in delivery ratio with lower delivery cost at the same time is valuable. Therefore, we utilize the small-world property and propose a new delivery metric called multi-probability to design our relay node selection principles that nodes with lower delivery predictability can also be selected to be the relay nodes if one of their history nodes has higher delivery predictability. So, we can find more potential relay nodes to reduce the forwarding overhead of successfully delivered messages through our proposed algorithm called HESnW. We also apply our new messages copies allocation scheme to optimize the routing performance. Comparing to existing routing algorithms, simulation results show that HESnW can reduce the delivery cost while it can also obtain a rather high delivery ratio.