• Journal of Ecology and Environment
• /
• v.47 no.4
• /
• pp.264-271
• /
• 2023

Environmental crises caused by climate change and human-induced disturbances have become urgent challenges to the sustainability of human beings. These issues can be addressed based on a data-driven understanding and forecasting of ecosystem responses to environmental changes. In this study, we introduce a long-term ecological monitoring system in Korean Long-Term Ecological Research (KLTER), and a plan for the Korean Ecological Observatory Network (KEON). KLTER has been conducted since 2004 and has yielded valuable scientific results. However, the KLTER approach has limitations in data integration and coordinated observations. To overcome these limitations, we developed a KEON plan focused on multidisciplinary monitoring of the physiochemical, meteorological, and biological components of ecosystems to deepen process-based understanding of ecosystem functions and detect changes. KEON aims to answer nationwide and long-term ecological questions by using a standardized monitoring approach. We are preparing three types of observatories: two supersites depending on the climate-vegetation zones, three local sites depending on the ecosystem types, and two mobile deployment platforms to act on urgent ecological issues. The main observation topics were species diversity, population dynamics, biogeochemistry (carbon, methane, and water cycles), phenology, and remote sensing. We believe that KEON can address environmental challenges and play an important role in ecological observations through partnerships with international observatories.

• Journal of The Korean Astronomical Society
• /
• v.52 no.6
• /
• pp.227-233
• /
• 2019

We report the performance of the 13.7-meter Taeduk Radio Astronomy Observatory (TRAO) radio telescope. The telescope has been equipped with a new receiver, SEQUOIA-TRAO, a new backend system, FFT2G, and a new VxWorks operating system. The receiver system features a 16-pixel focal plane array using high-performance MMIC preamplifiers; it shows very low system noise levels, with system noise temperatures from 150 K to 450 K at frequencies from 86 to 115 GHz. With the new backend system, we can simultaneously obtain 32 spectra, each with a velocity coverage of 163 km s^-1 and a resolution of 0.04 km s^-1 at 115 GHz. The new operating system, VxWorks, has successfully handled the LMTMC-TRAO observing software. The main observing method is the on-the-fly (OTF) mapping mode; a position-switching mode is available for small-area observations. Remote observing is provided. The antenna surface has been newly adjusted using digital photogrammetry, achieving a rms surface accuracy better than 130 ㎛. The pointing uncertainty is found to be less than 5" over the entire sky. We tested the new receiver system with multi-frequency observations in OTF mode. The aperture efficiencies are 43±1%, 42±1%, 37±1%, and 33±1%, the beam efficiencies are 45±2%, 48±2%, 46±2%, and 41±2% at 86, 98, 110, and 115 GHz, respectively.

• Publications of The Korean Astronomical Society
• /
• v.20 no.1 s.24
• /
• pp.21-27
• /
• 2005

We have been performing a wide-field photometric monitoring program, named SPVS (Short-Period Variability Survey), at the Bohyunsan Optical Astronomy Observatory (BOAO). The observation system consists of a small refracting telescope (D = 155 mm, f = 1050 mm) and a $2k{\times}3k$ CCD Camera. The field of view is $1.0^{\circ}{\times}1.5^{\circ}$. Detection limit is about V = 13 for short-period small amplitude variables such as ${\delta}$ Scuti-type pulsating stars, and about V = 15 for long-period large amplitude variables such as eclipsing binaries and RR Lyrae stars. The instrument is designed to be remote-controlled through internet. The primary purpose of this project is to search for variable objects in bright Galactic open clusters. We present results of test observations conducted towards NGC 7092.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.6
• /
• pp.1045-1054
• /
• 2020

In this paper, we designed a TCP/IP based ring buffer system that can stably transfer bulk data streams in the unstable network environments. In the scheme we proposed, The observation data stream generated and output by each radio observatory's backend system as a UDP frame is stored as a UDP packet in a large capacity ring buffer via a socket buffer in the client system. Thereafter, for stable transmission to the remote destination, the packets are processed in TCP and transmitted to the socket buffer of server system in the correlation center, which packets are stored in a large capacity ring buffer if there is no problem with the packets. In case of errors such as loss, duplication, and out of order delivery, the packets are retransmitted through TCP flow control, and we guaranteed that the reliability of data arriving at the correlation center. When congestion avoidance occurs due to network performance instability, we also suggest that performance degradation can be minimized by applying parallel streams.

• Korean Journal of Remote Sensing
• /
• v.29 no.5
• /
• pp.545-554
• /
• 2013

Augustine is an active stratovolcano located in southwest of Cook Inlet, about 290 kilometers southwest of Anchorage, Alaska. Between January 11 and 28, 2006, the volcano erupted explosively 14 times. We collected twelve permanent GPS stations operating by Plate Boundary Observatory (PBO) from 2005 to 2011. All data processing was carried out using Bernese GPS Software V5.0 with IGS precise orbit. Static baseline processing by fixing AC59 station was applied for the volcano activity monitoring. AC59 is the nearest (about 24.5 km) station to Augustine volcano, and located on North America Plate including Augustine Island. The test results show inflation (9.7 cm/yr) and deflation (-9.2 cm/yr) of volcano before and after eruption around crater clearly. After volcano activity has reached a plateau, some of the GPS stations installed north of the volcano show ground subsidence phenomenon caused by compaction of pyroclastic flows. These results indicate the possibility of using surface deformation observed by GPS for monitoring and prediction of volcano activity.

• Journal of the Korean earth science society
• /
• v.45 no.2
• /
• pp.111-120
• /
• 2024

Cloud coverage is a key factor in determining whether to proceed with observations. In the past, human judgment played an important role in weather evaluation for observations. However, the development of remote and robotic observation has diminished the role of human judgment. Moreover, it is not easy to evaluate weather conditions automatically because of the diverse cloud shapes and their rapid movement. In this paper, we present the development of a cloud monitoring program by applying a machine learning-based Python module "cloudynight" on all-sky camera images obtained at Miryang Arirang Astronomical Observatory (MAAO). The machine learning model was built by training 39,996 subregions divided from 1,212 images with altitude/azimuth angles and extracting 16 feature spaces. For our training model, the F1-score from the validation samples was 0.97, indicating good performance in identifying clouds in the all-sky image. As a result, this program calculates "Cloudiness" as the ratio of the number of total subregions to the number of subregions predicted to be covered by clouds. In the robotic observation, we set a policy that allows the telescope system to halt the observation when the "Cloudiness" exceeds 0.6 during the last 30 minutes. Following this policy, we found that there were no improper halts in the telescope system due to incorrect program decisions. We expect that robotic observation with the 0.7 m telescope at MAAO can be successfully operated using the cloud monitoring program.

• Journal of The Korean Astronomical Society
• /
• v.54 no.3
• /
• pp.89-102
• /
• 2021

Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4-1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scientific scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.

• Korean Journal of Remote Sensing
• /
• v.38 no.5_1
• /
• pp.627-646
• /
• 2022

Recently, the seriousness of climate change-related problems caused by global warming is growing, and the average temperature is also rising. As a result, it is affecting the environment in which various temperature-sensitive creatures and creatures live, and changes in the ecosystem are also being detected. Seasons are one of the important factors influencing the types, distribution, and growth characteristics of creatures living in the area. Among the most popular and easily recognized plant seasonal phenomena among the indicators of the climate change impact evaluation, the blooming day of flower and the peak day of autumn leaves were modeled. The types of plants used in the modeling were forsythia and cherry trees, which can be seen as representative plants of spring, and maple and ginkgo, which can be seen as representative plants of autumn. Weather data used to perform modeling were temperature, precipitation, and solar radiation observed through the ASOS Observatory of the Korea Meteorological Administration. As satellite data, MODIS NDVI was used for modeling, and it has a correlation coefficient of about -0.2 for the flowering date and 0.3 for the autumn leaves peak date. As the model used, the model was established using multiple regression models, which are linear models, and Random Forest, which are nonlinear models. In addition, the predicted values estimated by each model were expressed as isopleth maps using spatial interpolation techniques to express the trend of plant seasonal changes from 2003 to 2020. It is believed that using NDVI with high spatio-temporal resolution in the future will increase the accuracy of plant phenology modeling.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.1
• /
• pp.1-14
• /
• 2006

Tropospheric aerosols are highly variant in time and space due to non-uniform source distribution and strong influence of meteorological conditions. Backscatter lidar measurement is useful to understand vertical distribution of aerosol. However, the backscatter lidar equation is undetermined due to its dependence on the two unknowns, extinction and backscattering coefficient. This dependence necessitates the exact value of the ratio between two parameters, that is, the lidar ratio. Also, Iidar ratio itself is useful optical parameter to understand properties of aerosols. Tropospheric aerosols were observed to understand variance of lidar ratio at Anmyeon island ($36.32^{/circ}N$, $126.19^{/circ}E$), Korea using a multi-wavelength raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST), Korea during measurement periods; March 15$\sim$April $16^{th}$, 2004 and May 24$\sim$ $8^{th}$ 2005. Extinction coefficient, backscattering coefficient, and lidar ratio were measured at 355 and 532 nm by the Raman method. Different types of aerosol layers were distinguished by the differences in the optical properties such as Angstrom exponent, and lidar ratio. The average value of lidar ratio during two observation periods was found to be $50.85\pm4.88$ sr at 355 nm and $52.43\pm15.15$ sr at 532 nm at 2004 and $57.94\pm10.29$ sr at 355 nm and $82.24\pm15.90$ sr at 532 nm at 2005. We conduct hysplit back-trajectory to know the pathway of airmass during the observation periods. We also calculate lidar ratio of different type of aerosol, urban, maritime, dust, continental aerosols using OPAC (Optical Properties of Aerosols and Clouds), Remote sensing of atmospheric aerosol using a multi-wavelengh lidar system with Raman channels is quite and powerful tool to characterize the optical propertises of troposheric aerosols.

• Korean Journal of Remote Sensing
• /
• v.39 no.2
• /
• pp.233-246
• /
• 2023

In terms of understanding the water cycle and efficient water resource management, the importance of soil moisture has been highlighted. However, in Korea, the lack of qualified in-situ soil moisture data results in very limited utility. Even if satellite-based data are applied, the absence of ground reference data makes objective evaluation and correction difficult. The cosmic-ray neutron probe (CRNP) can play a key role in producing data for satellite data calibration. The installation of CRNP is non-invasive, minimizing damage to the soil and vegetation environment, and has the advantage of having a spatial representative for the intermediate scale. These characteristics are advantageous to establish an observation network in Korea which has lots of mountainous areas with dense vegetation. Therefore, this study was conducted to evaluate the applicability of the CRNP soil moisture observatory in Korea as part of the establishment of a Korean cOsmic-ray Soil Moisture Observing System (KOSMOS). The CRNP observation station was installed with the Gunup-ri observation station, considering the ease of securing power and installation sites and the efficient use of other hydro-meteorological factors. In order to evaluate the CRNP soil moisture data, 12 additional in-situ soil moisture sensors were installed, and spatial representativeness was evaluated through a temporal stability analysis. The neutrons generated by CRNP were found to be about 1,087 counts per hour on average, which was lower than that of the Solmacheon observation station, indicating that the Hongcheon observation station has a more humid environment. Soil moisture was estimated through neutron correction and early-stage calibration of the observed neutron data. The CRNP soil moisture data showed a high correlation with r=0.82 and high accuracy with root mean square error=0.02 m³/m³ in validation with in-situ data, even in a short calibration period. It is expected that higher quality soil moisture data production with greater accuracy will be possible after recalibration with the accumulation of annual data reflecting seasonal patterns. These results, together with previous studies that verified the excellence of CRNP soil moisture data, suggest that high-quality soil moisture data can be produced when constructing KOSMOS.