• Atmosphere
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• v.22 no.4
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• pp.455-464
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• 2012

This study investigates a 12 month-lead predictability of PNU Coupled General Circulation Model (CGCM) V1.1 hindcast, for which an oceanic data assimilated initialization is used to generate ocean initial condition. The CGCM, a participant model of APEC Climate Center (APCC) long-lead multi-model ensemble system, has been initialized at each and every month and performed 12-month-lead hindcast for each month during 1980 to 2011. The 12-month-lead hindcast consisted of 2-5 ensembles and this study verified the ensemble averaged hindcast. As for the sea-surface temperature concerns, it remained high level of confidence especially over the tropical Pacific and the mid-latitude central Pacific with slight declining of temporal correlation coefficients (TCC) as lead month increased. The CGCM revealed trustworthy ENSO prediction skills in most of hindcasts, in particular. For atmospheric variables, like air temperature, precipitation, and geopotential height at 500hPa, reliable prediction results have been shown during entire lead time in most of domain, particularly over the equatorial region. Though the TCCs of hindcasted precipitation are lower than other variables, a skillful precipitation forecasts is also shown over highly variable regions such as ITCZ. This study also revealed that there are seasonal and regional dependencies on predictability for each variable and lead.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.177-179
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• 2019

Pseudomonas kribbensis CHA-19 was isolated from a temperate forest soil (mid latitude) in New Jersey, USA, for its ability to degrade humic acids, a main component of humic substances (HS), and subsequently confirmed to be able to decolorize lignin (a surrogate for HS) and catabolize lignin-derived ferulic and vanillic acids. The draft genome sequence of CHA-19 was analyzed to discover the putative genes for depolymerization of polymeric HS (e.g., dye-decolorizing peroxidases and laccase-like multicopper oxidases) and catabolic degradation of HS-derived small aromatics (e.g., vanillate O-demethylase and biphenyl 2,3-dioxygenase). The genes for degradative activity were used to propose a HS degradation pathway of soil bacteria.

• Atmosphere
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• v.32 no.2
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• pp.87-101
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• 2022

In this paper, the performance improvement for the new KMA's Climate Prediction System (GloSea6), which has been built and tested in 2021, is presented by assessing the bias distribution of basic variables from 24 years of GloSea6 hindcasts. Along with the upgrade from GloSea5 to GloSea6, the performance of GloSea6 can be regarded as notable in many respects: improvements in (i) negative bias of geopotential height over the tropical and mid-latitude troposphere and over polar stratosphere in boreal summer; (ii) cold bias of tropospheric temperature; (iii) underestimation of mid-latitude jets; (iv) dry bias in the lower troposphere; (v) cold tongue bias in the equatorial SST and the warm bias of Southern Ocean, suggesting the potential of improvements to the major climate variability in GloSea6. The warm surface temperature in the northern hemisphere continent in summer is eliminated by using CDF-matched soil-moisture initials. However, the cold bias in high latitude snow-covered area in winter still needs to be improved in the future. The intensification of the westerly winds of the summer Asian monsoon and the weakening of the northwest Pacific high, which are considered to be major errors in the GloSea system, had not been significantly improved. However, both the use of increased number of ensembles and the initial conditions at the closest initial dates reveals possibility to improve these biases. It is also noted that the effect of ensemble expansion mainly contributes to the improvement of annual variability over high latitudes and polar regions.

• Ocean and Polar Research
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• v.33 no.3
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• pp.211-221
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• 2011

Contents of biogenic components [opal, $CaCO_3$, TOC (total organic carbon)] were measured in Core LHB-3PC sediments collected off Lutzow-Holm Bay, in order to understand glacial-interglacial cyclic variation of the high-latitude surface-water paleoproductivity, in the Indian Sector of the Southern Ocean. An age model was established from the correlation of ARM/IRM ratios of Core LHB-3PC with LR04 stack benthic ${\delta}^{18}O$ records, in complement with radiocarbon isotope ages and biostratigraphic Last Appearance Datum (LAD). The core-bottom age was estimated to be about 700 ka. Although the $CaCO_3$ content is very low less than 1.0% throughout the core, the opal and TOC contents show clear glacial-interglacial cyclic variation such that they are high during the interglacial periods (7.2-50.3% and 0.05-1.00%, respectively) and low during the glacial periods (5.2-25.2% and 0.01-0.68%, respectively). According to the spectral analysis, the variation of opal content is controlled mainly by eccentricity forcing and subsequently by obliquity forcing during the last 700 kyrs. The opal contents of Core LHB-3PC also represent the apparent Mid-Pleistocene Transition (MPT)-related climatic variation in the glacial-interglacial cycles. In particular, the orbital variation of the opal contents shows increasing amplitudes since marine isotope stage (MIS) 11, which defines one of the important paleoclimatic events during the late Quaternary, called the "Mid-Brunhes Event". Based on the variation of the opal contents in Core LHB-3PC, we suggest that the surface-water paleoproductivity in the Indian Sector of the Southern Ocean followed the orbital (glacial-interglacial) cycles, and was controlled mainly by the extent of sea ice distribution during the last 700 kyrs.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.335-347
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• 2022

We investigated the emergence patterns of Chilo suppressalis (Lepidoptera: Crambidae) adults using sex pheromone traps in the three northeastern areas, Dandong (40°07'N 124°23'E) (Liaoning province), and Gongzhuling (43°30'N 124°49') and Longjing (42°46'N 129°26'E) (Jilin province), China, in 2020 and 2021. Two times of adult flight seasons were isolated clearly during the rice growing periods in the all areas, in which the first season from mid May to late July, and the second season from mid July to mid September were observed. The adult emergence seasons in the areas at higher latitude were later than that at lower latitude. Using the adult emergence data during the first flight seasons, the second flight seasons were estimated through insect phenology modelling, and compared with the observed data. Temperature-dependent life history models (developmental rate, development completion, survival rate, adult aging rate, total fecundity, oviposition completion, and adult survival completion) were collected or constructed for each life stage of C. suppressalis, in which the data from the four previous studies were used. Those models were combined in an insect phenology estimation software, PopModel, and operated for the observed areas. In the results, the phenology modelling operated with the models based on the data of shorter larval periods in the previous studies estimated more accurately the second flight seasons. In 2021, we investigated the change of damaged hill ratios of rice with observing the adult emergence at Dandong and Longjing, 2021. The increase periods of damaged hill ratios of rice were observed two times during the total rice cultivation season, which may be caused by different generations of C. suppressalis larvae.

• Journal of Astronomy and Space Sciences
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• v.31 no.1
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• pp.15-23
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• 2014

We present preliminary observations of the field-aligned-irregularities (FAIs) in the E and F regions during the solar minimum (2009 - 2010) using the 40.8 MHz coherent backscatter radar at Daejeon ($36.18^{\circ}N$, $127.14^{\circ}E$, $26.7^{\circ}N$ dip latitude) in South Korea. The radar, which consists of 24 Yagi antennas, observes the FAIs using a single beam with a peak power of 24 kW. The radar has been continuously operated since December 2009. Depending on the manner of occurrence of the backscatter echoes, the E-region echoes are largely divided into two types: quasi-periodic (QP) and continuous echoes. Our observations show that the QP echoes occur frequently above an altitude of 105 km in the post-sunset period and continuous echoes occur preferentially around an altitude of 105 km in the post-sunrise period. QP echoes appear as striated discrete echoes for a period of about 10 - 20 min. The QP-type echoes occur more frequently than the continuous-type echoes do and the echo intensity of the QP type is stronger than that of the continuous type. In the F region, the FAIs occur at night at an altitude interval of 250 - 450 km. As time proceeds, the occurrence height of the FAIs gradually increases until early in the morning and then decreases. The duration of the F-region FAIs is typically a few hours at night, although, in rare cases, FAIs persist throughout the night or appear even after sunrise. We discuss the similarities and differences of the FAIs observed by the Daejeon radar in comparison with other radar observations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.324-331
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• 2018

The thermal environment on lunar surface is more severe than that of earth's surface or low earth orbit because of the long daytime and nighttime due to 28 days of rotation cycle of moon. Thus, analyzing heat flux on lunar lander at potential landing sites is important to determine the landing site in its initial design phase. In this study, thermal model of lunar regolith that can simulate lunar surface temperature was constructed for analyzing thermal characteristics according to the potential landing sites of lunar lander. The heat flux analyses were performed various latitudes of equator, mid-latitude, polar regions, lunar mare and highland. In addition, we also investigated the heat flux of lunar lander when it is landed on adjacent area to hill.

• Journal of Radiation Protection and Research
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• v.21 no.2
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• pp.107-115
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• 1996

An electrolytic enrichment technique was used to measure low levels of tritium in seawater around the Korean peninsula. Tritium concentrations were determined for surface seawater samples collected from the East Sea, the South Sea, and the Yellow Sea. The tritium concentrations in surface seawater samples from the study area ranged from $0.12 BqL^{-1}\;to\;1.50BqL^{-1}$ with a mean value of $0.60{\pm}0.35 BqL^{-1}$. The means of the tritium concentration were $0.54{\pm}0.30 BqL^{-1}$ for the East Sea, $0.48{\pm}0.35 BqL^{-1}$ for the South Sea, and $0.77{\pm}0.32 BqL^{-1}$ for the Yellow Sea. The tritium concentrations in the sea areas did not show much difference no matter where the samples were taken. Due to the limited number and distribution of sampling points, no systematic change in tritium levels with latitude was observed. Measured tritium levels were similar to those observed in other data collected near Japan, but higher than mid-Pacific Ocean measurements.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.63-65
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• 2017

The zodiacal light emission is the thermal emission from the interplanetary dust and the dominant diffuse radiation in the mid- to far-infrared wavelength region. Even in the far-infrared, the contribution of the zodiacal emission is not negligible at the region near the ecliptic plane. The AKARI far-infrared all-sky survey covered 97% of the whole sky in four photometric bands with band central wavelengths of 65, 90, 140, and $160{\mu}m$. AKARI detected the small-scale structure of the zodiacal dust cloud, such as the asteroidal dust bands and the circumsolar ring, in far-infrared wavelength region. Although the most part of the zodiacal light structure in the AKARI far-infrared all-sky image can be well reproduced with the DIRBE zodiacal light model, there are discrepancies in the small-scale structures. In particular, the intensity and the ecliptic latitude of the peak position of the asteroidal dust bands cannot be reproduced precisely with the DIRBE models. The AKARI observational data during more than one year has advantages over the 10-month DIRBE data in modeling the full-sky zodiacal dust cloud. The resulting small-scale zodiacal light structure template has been used to subtract the zodiacal light from the AKARI all-sky maps.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.1
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• pp.45-58
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• 1992

A three-dimensional hydrodynamic numerical model is used to compute the annual and seasonal meteorologically-induced residual circulation on the Yellow Sea and the East China Sea continental shelf. The model is formulated having irregular coastal boundaires and non-uniform depth distribution representative of nature. The previous three-dimensional model of the East China Sea (Choi. 19U) has been further refined to resolve the flow over the continental shelf in more detail. The mesh resolution of the present finite difference grid system used is 4 minutes latitude by 5 minutes longitude over the entire shelf. The circulation pattern showing depth and spatial distribution of currents over the Yellow Sea and the East China Sea is presented. Meteorologically-induced currents are subsequently used to compute turn-over times for the three depths (surface. mid-depth. bottom) and the total water column of various regions of the Yellow Sea and the East China Sea.