• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.49-59
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• 2019

The field trial was performed to evaluate the rice growth and yield in different direct seeding methods after Italian Ryegrass Harvest The required time for seed emergence was for 7 ~ 8days in the tested direct seeding methods and there was high in seedling establishment in order of wet hill-seeding with iron-coated seeds > water seeding with iron-coated seeds > wet hill-seeding with soil coverage with pregerminated seeds. The rice plant height was shorter in the tested direct seeding methods than that of machine transplanting until 45day after seeding but there was not significant difference in terms of statistical analysis at 63day after seeding. The growth of tiller number in the rice plant was high in water seeding with iron-coated seeds and wet hill-seeding with soil coverage and low in wet hill-seeding with iron-coated seeds compared to machine transplanting. The yield component in the tested direct seeding methods was not significant difference in terms of statistical analysis. The milled rice yield in the tested direct seeding methods was higher 2 ~ 8% being with 4.94 ~ 5.24t/ha than that of machine transplanting but there was not significant difference in terms of statistical analysis. The percentage of head rice was low in the tested direct seeding methods compared to machine transplanting. The weedy rice was not occurred in the tested rice cultivation methods. In conclusion the direct seeding method would be recommended to be a suitable to in following by Italian ryegrass harvesting in southern area of Korea in terms of reduction in production cost and high income basis for rice growing farmers.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.29-40
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• 2019

In Korea kiwifruit growing area is limited to southern coastal region and Jeju island, partly due to the lack of information on their cold hardiness in winter. This study was carried out to investigate cold hardiness of Korean kiwifruit cultivars in a period of dormancy for using it as preliminary data to expand the cultivation area of kiwifruit in Korea. A total of five kiwifruit cultivars in two species and hybrid, Actinidia deliciosa ('Hayward' and 'Garmrok'), A. chinensis ('Goldone') and A. arguta hybrid ('Bangwoori' and 'Skinny Green') were subjected to five freezing treatments of -12℃, -15℃, -18℃, -21℃ and -24℃. Cell membrane damage in all cultivars initiated in -18℃/32h and cell membrane stability was lost in -24℃ in most cultivars, except for 'Skinny Green'. Cold hardiness was estimated by 50% lethal temperature (LT₅₀) which was determined by triphenyl tetrazolium chloride (TTC) reduction. In branches, LT₅₀ was -15℃ in 'Hayward' and 'Garmrok', -18℃ in 'Bangwoori' and -21℃ in 'Goldone.' The LT₅₀ of buds on 'Hayward' and 'Garmrok' was 56 and 42 hours in -15℃ and 4 and 11 hours in -18℃, respectively; however, LT₅₀ of buds on 'Goldone' was 51 hours in -18℃ and that on 'Bangwoori' was 3 hours in -24℃. Cold hardiness results imply that it may be difficult for cultivars in A. deliciosa such as 'Hayward' and 'Garmrok' to be grown in the north of southern coastal region in Korea; however, it can be possible for several cultivars in A. chinensis and A. arguta hybrid to be grown in the northern part of Korean kiwifruit belt if cold tolerance in the thaw is confirmed.

• Journal of The Korean Association For Science Education
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• v.43 no.6
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• pp.495-507
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• 2023

Teachers often encounter challenges in supporting students with question generation and the development of investigation plans in sensemaking activities. A primary challenge stems from the ambiguity surrounding how students apply their conceptual understandings in this process. This study aims to explore how students apply their conceptual understandings to generate questions and design investigation processes in a sensemaking activity. Two types of student group activities were identified and examined for comparison: One focused on designing a process to achieve the goal of sensemaking, and the other focused on following the step-by-step scientific inquiry procedures. The design of investigation process in each group was concretized with epistemic criteria used for evaluating the designs. The students' use of conceptual understandings in discussions around each was then examined. The findings reveal three epistemic criteria employed in generating questions and designing investigation processes. First, the students examined the interestingness of natural phenomena, using their conceptual understandings of the structure and function of entities within natural phenomena to identify a target phenomenon. This process involved verifying their existing knowledge to determine the need for new understanding. The second criterion was the feasibility of investigating specific variables with the given resources. Here, the students relied on their conceptual understandings of the structure and function of entities corresponding to each variable to assess whether each variable could be investigated. The third epistemic criterion involved examining whether the factors of target phenomena expressed in everyday terms could be translated into observable variables capable of explaining the phenomena. Conceptual understandings related to the function of entities were used to translate everyday expressions into observable variables and vice versa. The students' conceptual understanding of a comprehensive mechanism was used to connect the elements of the phenomenon and use the elements as potential factors to explain the target phenomenon. In the case where the students focused on carrying out step-by-step procedures, data collection feasibility was the sole epistemic criterion guiding the design. This study contributes to elucidating how the process of a sensemaking activity can be developed in the science classroom and developing conceptual supports for designing sensemaking activities that align with students' perspectives.

• Journal of Practical Agriculture & Fisheries Research
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• v.25 no.3
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• pp.19-29
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• 2023

This study investigated effect of water temperature change on the formation and release of conchospores of Neopyropia yezoensis. We observed that conchocelis growth and conchospores formation in oyster shell at labolatory during 7 weeks. In order to investigate the amount of conchospore formation in oyster shells, which was being cultured at 28℃, was moved to 10℃, 18℃, 28℃, and culture during 6 weeks. At 10℃, we observed an average of 127 for 1 week, 127 for 2 weeks, 95 for 3 weeks, 90 for 4 weeks, 76 for 5 weeks, and 75 for 6 weeks. At 18℃, we observed an average of 141 for 1 week, 135 for 2 weeks, 94 for 3 weeks, 153 for 4 weeks, 162 for 5 weeks, and 2 for 6 weeks. At 28℃, we observed an average of 167 for 1 week, 102 for 2 weeks, 148 for 3 weeks, 157 for 4 weeks, 270 for 5 weeks, and 138 for 6 weeks. Conchospores released from the shell grew into a young thalli in the culture for 6 weeks, and the number of ones was counted. The number of young thalli were investigated at 10℃, 0 for 1 week, 189 for 2 weeks, 200 for 3 weeks, 89 for 4 weeks, 56 for 5 weeks and 27 for 6 weeks. At 18℃, It observed 0 for 1 week, 26 for 2 weeks, 546 for 3 weeks, 16 for 4 weeks, 17 for 5 weeks and 154 for 6 weeks. It was not observed at 28℃.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.120-129
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• 2023

To evaluate the vertical loads on railway bridges, conventional load tests are typically conducted. However, these tests often entail significant costs and procedural challenges. Railway conditions involve nearly identical load profiles due to standardized rail systems, which may appear straightforward in terms of load conditions. Nevertheless, this study aims to validate load tests conducted under operational train conditions by comparing the results with those obtained from conventional load tests. Additionally, static and dynamic structural behaviors are extracted from the measurement data for evaluation. To ensure the reliability of load testing, this research demonstrates feasibility through comparisons of existing measurement data with sensor attachment locations, train speeds, responses between different rail lines, tendency analysis, selection of impact coefficients, and analysis of natural frequencies. This study applies to the Dongho Railway Bridge and verifies the applicability of the proposed method. Ten operational trains and 44 sensors were deployed on the bridge to measure deformations and deflections during load test intervals, which were then compared with theoretical values. The analysis results indicate good symmetry and overlap of loads, as well as a favorable comparison between static and dynamic load test results. The maximum measured impact coefficient (0.092) was found to be lower than the theoretical impact coefficient (0.327), and the impact influence from live loads was deemed acceptable. The measured natural frequencies approximated the theoretical values, with an average of 2.393Hz compared to the calculated value of 2.415Hz. Based on these results, this paper demonstrates that for evaluating vertical loads, it is possible to measure deformations and deflections of truss railway bridges through load tests under operational train conditions without traffic control, enabling the calculation of response factors for stress adjustments.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1283-1297
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• 2023

Mid-wave infrared (MWIR) imagery, due to its ability to capture the temperature of land cover and objects, serves as a crucial data source in various fields including environmental monitoring and defense. The KOMPSAT-3A satellite acquires MWIR imagery with high spatial resolution compared to other satellites. However, the limited spatial resolution of MWIR imagery, in comparison to electro-optical (EO) imagery, constrains the optimal utilization of the KOMPSAT-3A data. This study aims to create a highly visible MWIR fusion image by leveraging the edge information from the KOMPSAT-3A panchromatic (PAN) image. Preprocessing is implemented to mitigate the relative geometric errors between the PAN and MWIR images. Subsequently, we employ a pre-trained pixel difference network (PiDiNet), a deep learning-based edge information extraction technique, to extract the boundaries of objects from the preprocessed PAN images. The MWIR fusion imagery is then generated by emphasizing the brightness value corresponding to the edge information of the PAN image. To evaluate the proposed method, the MWIR fusion images were generated in three different sites. As a result, the boundaries of terrain and objects in the MWIR fusion images were emphasized to provide detailed thermal information of the interest area. Especially, the MWIR fusion image provided the thermal information of objects such as airplanes and ships which are hard to detect in the original MWIR images. This study demonstrated that the proposed method could generate a single image that combines visible details from an EO image and thermal information from an MWIR image, which contributes to increasing the usage of MWIR imagery.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.933-948
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• 2023

Atmospheric aerosols not only have adverse effects on human health but also exert direct and indirect impacts on the climate system. Consequently, it is imperative to comprehend the characteristics and spatiotemporal distribution of aerosols. Numerous research endeavors have been undertaken to monitor aerosols, predominantly through the retrieval of aerosol optical depth (AOD) via satellite-based observations. Nonetheless, this approach primarily relies on a look-up table-based inversion algorithm, characterized by computationally intensive operations and associated uncertainties. In this study, a novel high-resolution AOD direct retrieval algorithm, leveraging machine learning, was developed using top-of-atmosphere reflectance data derived from the Geostationary Ocean Color Imager-II (GOCI-II), in conjunction with their differences from the past 30-day minimum reflectance, and meteorological variables from numerical models. The Light Gradient Boosting Machine (LGBM) technique was harnessed, and the resultant estimates underwent rigorous validation encompassing random, temporal, and spatial N-fold cross-validation (CV) using ground-based observation data from Aerosol Robotic Network (AERONET) AOD. The three CV results consistently demonstrated robust performance, yielding R²=0.70-0.80, RMSE=0.08-0.09, and within the expected error (EE) of 75.2-85.1%. The Shapley Additive exPlanations(SHAP) analysis confirmed the substantial influence of reflectance-related variables on AOD estimation. A comprehensive examination of the spatiotemporal distribution of AOD in Seoul and Ulsan revealed that the developed LGBM model yielded results that are in close concordance with AERONET AOD over time, thereby confirming its suitability for AOD retrieval at high spatiotemporal resolution (i.e., hourly, 250 m). Furthermore, upon comparing data coverage, it was ascertained that the LGBM model enhanced data retrieval frequency by approximately 8.8% in comparison to the GOCI-II L2 AOD products, ameliorating issues associated with excessive masking over very illuminated surfaces that are often encountered in physics-based AOD retrieval processes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.69-79
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• 2009

Major and trace elements were analyzed in three core sediments to investigate geochemical characteristics of East Sea sediments and provenance changes during late Quaternary in Ulleung Basin. Comparing with Yellow and South Sea sediments, contents of major elements were generally similar while contents of trace elements were significantly different. Furthermore, within this basin, there were some variabilities in trace element compositions. In the western slope sediments (WS), Mo was enriched over 6 times as much as other sites. On the other hand, Zr, Nb, Hf and Ta were enriched in basin sediments (Basin), and Ca and Cs were enriched in southern slope sediments (SS). After excluding elements derived from biogenic, authigenic and diagenetic origins, the lithogenic elements (K, Ti, Cs, Zr, Nb, Hf and Ta) could be classified into three groups from the comparison of element/Al ratios among cores. The first group consisted of elements (K and Ti) that showed the nearly similar element/Al ratios among three cores. The second group contained Cs which showed significant difference between two slope sediments. The third group elements (Zr, Nb, Hf and Ta) showed highly enriched in basin relative to both slope areas. The depth profiles of metal/Al ratios in basin sediments provided the following interpretation for the compositions of sediment and their variation. From 10,000 yr B.P. to 7,000 yr B.P. two lithogenic components (volcanic ashes and western slope sediments) were mixed and deposited in the basin. After 7,000 yr B.P., however, southern slope sediments were mixed with volcanic ashes and deposited in basin area. This event of source change is nearly close to inflow period of the Tsushima Warm Current to Ulleung Basin. Thus, it might be suggested that element geochemistry in Ulleung basin sediment indicate the change of current system in the study area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.14-27
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• 2024

Unlike the shelf sand ridges moribund in motion, nearshore sand ridges are highly mobile, sensitive to changes in ocean environments, thereby becoming of particular interest with respect to morphological changes. About 5 km off the Daesan port, the Jangan Sand Ridge has been undergoing severe subsea morphological change over the past two decades. Understanding the nature of sand ridges is critical to elucidate the causes of morphological changes. In this context, this study aims at understanding the characteristics and distribution patterns of surface sediments of the ridge and its vicinity. For this purpose, 227 sediment samples were acquired using a grab-sampler, the grain sizes being analysed by the sieve-pipette method. In addition, comparison of grain sizes in sediments between 1997 and 2021 was made in order to investigate the 25-years change in sediment composition. Surface sediments along the ridge axis are fine to medium sands with 2-3 phi in mean grain size, whereas, in the trough of ridge, the sediments are composed of gravels and muddy sandy gravels with mean sizes of -2 to -6 phi. Sediments in the crest of the ridge are well-sorted with normal distribution, on the other hand, the basal sediments are poorly-sorted and positively skewed. Along the ridge crest, the sediments are negatively skewed. From 1997 to 2021, the ridge sediments became largely coarser about 0.5 phi. Such coarsening trend in mean grain size can be explained either by elimination of fine sediments during high waves in winter or elimination of fines suspended during sand mining activities in the past. Spatial distribution pattern of surface sediments shows that ca. 30 m thick of the sand ridge itself overlies the thin relict gravels. The strong asymmetry of sand ridge, the exposure of ridge base, and reworked gravel lags suggest that Jangan sand ridge is probably sediment-deficit and hence erosive in nature at present.

• Journal of Practical Agriculture & Fisheries Research
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• v.25 no.4
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• pp.138-147
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• 2024

Agrobacterium-mediated transformation (AMT) is a method that allows for the stable integration of DNA fragments into the plant genome. Transgenic plants generated through AMT typically exhibit a lower copy number of the transgene compared to those induced by particle bombardment. Furthermore, AMT offers a straightforward and efficient approach for generating transgenic plants. While the transformation efficiency of wheat is comparatively lower than that of other monocot plants such as Rice (Oryza sativa L.) and Maize (Zea mays L.), the cultivars 'Bobwhites' and 'Fielder' are commonly employed for wheat transformation. To date, there have been no reported instances of successful development of transgenic plants using Korean wheat varieties through AMT. This study aims to assess the transformation efficiency of 43 Korean wheat cultivars using the GUS assay, with the goal of identifying suitable Korean wheat cultivars for AMT. The pCAMBIA1301 vector, carrying the β-glucuronidase (GUS) gene, was incorporated into Agrobacterium strain EH105. Following the inoculation of Agrobacterium into immature embryos, GUS assays were conducted 'Saeol', 'Jopum', and 'Jonong' showed 100% (the number of embryos showing GUS spots/the number of embryos used for AMT) among 43 cultivars. In addition, cultivars with more than 70% were 'Saekeumgang', 'Jojung', 'Tapdong', 'Anbaek', 'Dabun', 'Sugang', 'Keumgang', 'Jeokjung', 'Seodun', 'Joeun', 'Dajung', and 'Baekjung'. It seems that the 15 cultivars above showed the possibility of using AMT. On the other hand, 'Yeonbaek', 'Goso', 'Baekgang', and 'Johan' showed less than 20% and GUS spots were not observed in 'Gru', 'Gobun', 'Milseong', and 'Shinmichal-1'. This study explores transient GUS expression in Korean wheat cultivars seven days after AMT. The observed initial high efficiency of transient transformation suggests the potential for subsequent stable transformation efficiency. Korean wheat cultivars demonstrating elevated transient transformation efficiency could serve as promising candidates for the development of stable transgenic wheat.