• Title/Summary/Keyword: spatial assimilation

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A study on spatial onset characteristics of flash drought based on GLDAS evaporative stress in the Korean Peninsula (GLDAS 증발 스트레스 기반 한반도 돌발가뭄의 공간적 발생 특성 연구)

  • Kang, Minsun;Jeong, Jaehwan;Lee, Seulchan;Choi, Minha
    • Journal of Korea Water Resources Association
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    • v.56 no.10
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    • pp.631-639
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    • 2023
  • Flash drought (FD), characterized by the rapid onset and intensification, can significantly impact ecosystems and induce immediate water stress. A more comprehensive understanding of the causes and characteristics of FD events is required to enhance drought monitoring. Therefore, we investigated the FD events took place over the Korean peninsula using Global Land Data Assimilation System (GLDAS) data from 2012 to 2022. We first detected FD events using the stress-based method (Standardized Evaporative Stress Ratio, SESR), and analyzed the frequency and duration of FDs. The FD events were classified into three cases based on the variations in Actual Evapotranspiration (AET) and potential Evapotranspiration (PET), and spatially analyzed. Results revealed that there are regional disparities in frequency and duration of FDs, with a mean frequency of 6.4 and duration of 31 days. When classified into Case 1 (normal condition), Case 2 (AET-driven), and Case 3 (PET-driven), we found that Case 2 FDs emerged approximately 1.5 times more frequently than those driven by PET (Case 3) across the Korean peninsula. Case 2 FDs were found to be induced under water-limited conditions, and led both AET and PET to be decreased. Conversely, Case 3 FDs occurred under energy-limited conditions, with increase in both. Case 2 FDs predominantly affected the northwestern and central-southern agricultural regions, while Case 3 occurred in the eastern region, characterized by forested land cover. These findings offers insights into our understanding of FDs over the Korean peninsula, considering climate factors, land cover, and water availability.

A Development of Generalized Coupled Markov Chain Model for Stochastic Prediction on Two-Dimensional Space (수정 연쇄 말콥체인을 이용한 2차원 공간의 추계론적 예측기법의 개발)

  • Park Eun-Gyu
    • Journal of Soil and Groundwater Environment
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    • v.10 no.5
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    • pp.52-60
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    • 2005
  • The conceptual model of under-sampled study area will include a great amount of uncertainty. In this study, we investigate the applicability of Markov chain model in a spatial domain as a tool for minimizing the uncertainty arose from the lack of data. A new formulation is developed to generalize the previous two-dimensional coupled Markov chain model, which has more versatility to fit any computational sequence. Furthermore, the computational algorithm is improved to utilize more conditioning information and reduce the artifacts, such as the artificial parcel inclination, caused by sequential computation. A generalized 20 coupled Markov chain (GCMC) is tested through applying a hypothetical soil map to evaluate the appropriateness as a substituting model for conventional geostatistical models. Comparing to sequential indicator model (SIS), the simulation results from GCMC shows lower entropy at the boundaries of indicators which is closer to real soil maps. For under-sampled indicators, however, GCMC under-estimates the presence of the indicators, which is a common aspect of all other geostatistical models. To improve this under-estimation, further study on data fusion (or assimilation) inclusion in the GCMC is required.

A Study on Compensation of Land according to the Spatial Properties -In case Compensation of Public Housing District- (공간정보 속성에 따른 토지보상액 결정에 관한 연구 -공공주택지구 보상사례를 중심으로-)

  • Moon, Jae-Hyeok;Lee, Myeong-Hun
    • The Journal of the Korea Contents Association
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    • v.16 no.11
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    • pp.188-198
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    • 2016
  • In order to supply the residential land for the promotion of public welfare, it must take a land of city suburb. That land have the difference in thinking is large for the determination of land prices to a variety of development pressure and land use regulations. In the process of executing a public project, the difference of these ideas has become a cause of conflict. Therefore, through objective study for the determination of land prices, to reduce the difference of ideas is going to be a clue of conflict resolution. This study selected the case area that is typical public district of many conflict, and then fix a compensation unit price like fair price as dependent variable. The selected variables through previous studies and expert consultation was an independent variable. To analyze the impact factors of land prices in the hedonic price model. The results were analyzed by distinguishing the group on the basis of the zoning and using, whether or not the site of the building in part that there is influence variable, the aspects of accessibility and regulation in part degree of influence variable came out different results for each group. It is analyzed that it reasonable results. Add selected site assimilation of the building that have not been presented in previous studies as a variable and which was applied at a rate to a variable of road have improved in more expliction of the influence of variables.

A Study on the Quantitative Analysis for the Forest Landscape (삼림경관에 관한 계량적 분석에 관한 연구)

  • 서주환
    • Journal of the Korean Institute of Landscape Architecture
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    • v.15 no.1
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    • pp.39-67
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    • 1987
  • The purpose of this thesis is to suggest objective basic data for the environmental design through the quantitative analysis of the visual quality included in the physical environment of forest landscape. For this, landscape values of forest landscape have been evaluated by using the Iverson method, the images structure of forest landscape's main utilizing space have been analysed by the factor analysis algorithm, degree of visual preferences have been pleasured mainly by questionnaries and SBE method, and finally these thesis can be summarized as fallow LCP with high values of Iverson factors I and IV yield high landscape value. Specifically, Iverson factor IV has been found to play the dominant. For all experimental points, significant seasonal variations in S.D. scale values have been observed. In natural parks, where artificial structures are complementary to the natural landscape, main factors of image are S.D. scales such as the visual sequence, the formal simplicity of structures, the emphasis, the unification of heterogeneous factors and the assimilation. Factors covering the spatial image of natural parks have been found to be the overall evaluation, the individual characteristics, the tidiness, the potentiality, the dignity, the intimacy and the space volume. For all seasons, factors such as the individual characteristics, the dignity, the tidiness, the potentiality, yield high factor scores. As for factors determining the degree of visual preference, variables such as the summit, the skyline, rocks, the water and the degree of natural destruction by artificial structures yield high values for all seasons.

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Study on the Local Weather Characteristics using Observation Data at the Boseong Tall Tower (보성 종합기상탑 자료를 활용한 국지기상 특성 연구)

  • Hwang, Sung Eun;Lee, Young Tae;Shin, Seung Sook;Kim, Ki Hoon
    • Journal of the Korean earth science society
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    • v.41 no.5
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    • pp.459-468
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    • 2020
  • In this study, the selection criteria for the occurrence of sea breezes in the Boseong area during the spring season (March-May) of 2016-2017 were prepared for the analysis of vertical weather characteristics. For this purpose, wind speed values were determined using the measured precipitation, cloud volume, wind direction, the difference between the ground and sea temperature, a wind Profiler at an altitude of 1 km, and numerical model data. The dates of the sea breezes in Boseong were classified according to the selection criteria, and the spatial and temporal characteristics of the sea breezes were identified by analyzing the time and altitude of the sea breeze and the size of the wind speed. Sea breezes occurred 23 out of 183 days (12%), and in Boseong, at least 1.2 out of 10 spring days exhibited sea breezes. Sea winds ranged from 1200 to 1800 LST, mainly from ground to 700 m altitude during the day. In addition, the maximum wind speed averaged 4.9 m s-1, at an altitude of 40 m at 1600 LST, showing relatively lower values than those in a preceding study. This seems to be owing to the reduction in wind speed due to the complexity of the coastal terrain.

The Role of Korean Ethnic Networks in the Settlement Process of Korean Immigrants and Their Utilization Measures : A Case Study of Korean Immigrants in Los Angeles (한인 이주민의 정착과정에서 한인네트워크 역할 및 활용 방안 - 미국 LA지역 한인 이주민 사례를 중심으로 -)

  • Park, Wonseok
    • Journal of the Korean association of regional geographers
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    • v.21 no.2
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    • pp.286-303
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    • 2015
  • This paper aims at analyzing the role of Korean ethnic network in the settlement process of Korean immigrants, and elucidating their utilization measures, through the case Study of Korean Immigrants in LA. The main results of this study are as follows. Firstly, the majority of respondents used Korean ethnic networks and Korean town in the immigration process. According to the results of ANOVA test, Korean ethnic network are more importantly considered by the groups such as elderly, livers in Korean town, and people who the first settlement was LA. Secondly, respondents more frequently use Korean ethnic network in the activities such as church, shopping and business. Especially, the groups such as short immigration term, elderly, poor English ability are more frequently use Korean ethnic network. Thirdly, Viewing the cognition of respondents about the necessity of Korean ethnic networks, respondents want to use them for strengthening the ties of domination society. Finally, utilization of Korean ethnic churches, Korean ethnic business organizations and Korean ethnic web-site portal are proposed for activating Korean ethnic networks.

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Climate Change Impact on the Flowering Season of Japanese Cherry (Prunus serrulata var. spontanea) in Korea during 1941-2100 (기후변화에 따른 벚꽃 개화일의 시공간 변이)

  • Yun Jin-I.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.8 no.2
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    • pp.68-76
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    • 2006
  • A thermal time-based two-step phenological model was used to project flowering dates of Japanese cherry in South Korea from 1941 to 2100. The model consists of two sequential periods: the rest period described by chilling requirement and the forcing period described by heating requirement. Daily maximum and minimum temperature are used to calculate daily chill units until a pre-determined chilling requirement for rest release is met. After the projected rest release date, daily heat units (growing degree days) are accumulated until a pre-determined heating requirement for flowering is achieved. Model calculations using daily temperature data at 18 synoptic stations during 1955-2004 were compared with the observed blooming dates and resulted in 3.9 days mean absolute error, 5.1 days root mean squared error, and a correlation coefficient of 0.86. Considering that the phonology observation has never been fully standardized in Korea, this result seems reasonable. Gridded data sets of daily maximum and minimum temperature with a 270 m grid spacing were prepared for the climatological years 1941-1970 and 1971-2000 from observations at 56 synoptic stations by using a spatial interpolation scheme for correcting urban heat island effect as well as elevation effect. A 25km-resolution temperature data set covering the Korean Peninsula, prepared by the Meteorological Research Institute of Korea Meteorological Administration under the condition of Inter-governmental Panel on Climate Change-Special Report on Emission Scenarios A2, was converted to 270 m gridded data for the climatological years 2011-2040, 2041-2070 and 2071-2100. The model was run by the gridded daily maximum and minimum temperature data sets, each representing a climatological normal year for 1941-1970, 1971-2000, 2011-2040, 2041-2070, and 2071-2100. According to the model calculation, the spatially averaged flowering date for the 1971-2000 normal is shorter than that for 1941-1970 by 5.2 days. Compared with the current normal (1971-2000), flowering of Japanese cherry is expected to be earlier by 9, 21, and 29 days in the future normal years 2011-2040, 2041-2070, and 2071-2100, respectively. Southern coastal areas might experience springs with incomplete or even no Japanese cherry flowering caused by insufficient chilling for breaking bud dormancy.

Generation of Sea Surface Temperature Products Considering Cloud Effects Using NOAA/AVHRR Data in the TeraScan System: Case Study for May Data (TeraScan시스템에서 NOAA/AVHRR 해수면온도 산출시 구름 영향에 따른 신뢰도 부여 기법: 5월 자료 적용)

  • Yang, Sung-Soo;Yang, Chan-Su;Park, Kwang-Soon
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.13 no.3
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    • pp.165-173
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    • 2010
  • A cloud detection method is introduced to improve the reliability of NOAA/AVHRR Sea Surface Temperature (SST) data processed during the daytime and nighttime in the TeraScan System. In daytime, the channels 2 and 4 are used to detect a cloud using the three tests, which are spatial uniformity tests of brightness temperature (infrared channel 4) and channel 2 albedo, and reflectivity threshold test for visible channel 2. Meanwhile, the nighttime cloud detection tests are performed by using the channels 3 and 4, because the channel 2 data are not available in nighttime. This process include the dual channel brightness temperature difference (ch3 - ch4) and infrared channel brightness temperature threshold tests. For a comparison of daytime and nighttime SST images, two data used here are obtained at 0:28 (UTC) and 21:00 (UTC) on May 13, 2009. 6 parameters was tested to understand the factors that affect a cloud masking in and around Korean Peninsula. In daytime, the thresholds for ch2_max cover a range 3 through 8, and ch4_delta and ch2_delta are fixed on 5 and 2, respectively. In nighttime, the threshold range of ch3_minus_ch4 is from -1 to 0, and ch4_delta and min_ch4_temp have the fixed thresholds with 3.5 and 0, respectively. It is acceptable that the resulted images represent a reliability of SST according to the change of cloud masking area by each level. In the future, the accuracy of SST will be verified, and an assimilation method for SST data should be tested for a reliability improvement considering an atmospheric characteristic of research area around Korean Peninsula.

A Study on Proposal of Landscape Management Improvement on the Quantitative Analysis of National Parks (국립공원(國立公園) 자연경관(自然景觀)의 계량적(計量的) 분석(分析)을 통(通)한 경관관리(景觀管理) 개선방안(改善方案)에 관(關)한 연구)

  • Kim, Sei Cheon
    • Journal of Korean Society of Forest Science
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    • v.80 no.1
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    • pp.32-41
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    • 1991
  • This study is focusted to the national park of Korean typical mountain Chi-ri, its visual resources of forests, and practiced inspectind course by way of hypothesis and tests, to show visual resource management objectively, and that of quantitative basic data. spatial image structure measured by Semantic Differential(S.D.) Scale was shown through factor analysis algorithm for the analyzing psychological amount and examined the flowing out of decisive factor and the objective importance related mutual factors by appling the measurement of visual quality. Also, it has been investigated the differences between the degrees of expectation which is used before and of satisfaction which is used, by appling instrumental expectation theory. And showed patterns of investigation area through factor analyzing algorithm. As a national Park, visual factors that have natural landscape harmonized forest, sky, surface of the water, curious stones and rocks, temples should be escalate their values affirmatively so as to be the scenery of pointed direction and enjoyable, and it is needs the techniques visual resource management and its controlling technique to make artificial structures more intentional planning and systemical setting. Manmade distinctive quality in the spatials that affect complementally or harmonizingly, should be received considering relations between the distifution and joining which in line with various visual presenting massive factors. More than that, it is needed united basic standard to the beauty of arrangements which contain visual continuity considered balance between nature and human work, simplicity of structural types, assimilation, emphasis, unification of different factors and pro rata.

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