• Journal of the Korean earth science society
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• v.45 no.4
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• pp.349-362
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• 2024

We aimed to evaluate the effectiveness of ensemble optimal interpolation (EnOI) in improving the analysis of significant wave height (SWH) within wave models using satellite-derived SWH data. Satellite observations revealed higher SWH in mid-latitude regions (30° to 60° in both hemispheres) due to stronger winds, whereas equatorial and coastal areas exhibited lower wave heights, attributed to calmer winds and land interactions. Root mean square error (RMSE) analysis of the control experiment without data assimilation revealed significant discrepancies in high-latitude areas, underscoring the need for enhanced analysis techniques. Data assimilation experiments demonstrated substantial RMSE reductions, particularly in high-latitude regions, underscoring the effectiveness of the technique in enhancing the quality of analysis fields. Sensitivity experiments with varying ensemble sizes showed modest global improvements in analysis fields with larger ensembles. Sensitivity experiments based on different decorrelation length scales demonstrated significant RMSE improvements at larger scales, particularly in the Southern Ocean and Northwest Pacific. However, some areas exhibited slight RMSE increases, suggesting the need for region-specific tuning of assimilation parameters. Reducing the observation error covariance improved analysis quality in certain regions, including the equator, but generally degraded it in others. Rescaling background error covariance (BEC) resulted in overall improvements in analysis fields, though sensitivity to regional variability persisted. These findings underscore the importance of data assimilation, parameter tuning, and BEC rescaling in enhancing the quality and reliability of wave analysis fields, emphasizing the necessity of region-specific adjustments to optimize assimilation performance. These insights are valuable for understanding ocean dynamics, improving navigation, and supporting coastal management practices.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.5
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• pp.233-247
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• 2024

The damage to structures during an earthquake can be varied depending on the frequency characteristics of seismic waves and the geological properties of the ground. Therefore, considering such attributes in the design ground motions is crucial. The Korean seismic design standard (KDS 17 10 00) provides design response spectra for various ground classifications. If required for time-domain analysis, ground motion time series can be either selected and adjusted from motions recorded at rock sites in intraplate regions or artificially synthesized. Ground motion time series at soil sites should be obtained from site response analysis. However, in practice, selecting suitable ground motion records is challenging due to the overall lack of large earthquakes in intraplate regions, and artificially synthesized time series often leads to unrealistic responses of structures. As an alternative approach, this study provides a case study of generating ground motion time series based on the hybrid broadband ground motion simulation of selected scenario earthquakes at sites in the Nakdonggang delta region. This research is significant as it provides a novel method for generating ground motion time series that can be used in seismic design and response analysis. For large-magnitude earthquake scenarios close to the epicenter, the simulated response spectra surpassed the 1000-year design response spectra in some specific frequency ranges. Subsequently, the acceleration time series at each location were used as input motions to perform nonlinear 1D site response analysis through the PySeismoSoil Package to account for the site response characteristics at each location. The results of the study revealed a tendency to amplify ground motion in the mid to long-period range in most places within the study area. Additionally, significant amplification in the short-period range was observed in some locations characterized by a thin soil layer and relatively high shear wave velocity soil near the upper bedrock.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.153-166
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• 2015

Production of high quality pigmented rice contained with high content of anthocyanin, and polyphenol was significantly influenced by cultivation environments like transplanting date and cultivation location. This study was carried out to establish an optimum transplanting date and cultivation region to produce maximum content of anthocyanin, polyphenol and antioxidant activity of pigmented rice varieties (black, red colored). Three transplanting times (May 20, June 5, June 20) and four different sites (Miryang, Uiseong, Sangju, Bonghwa) were evaluated with five pigmented rice cultivars. Anthocyanin and total polyphenol index to average temperature during 30 days after heading (DAH) of black, red pigmented rice varieties showed that anthocyanin and total polyphenol contents were decreased by 10% and 9%, respectively, with increasing average temperature of $1^{\circ}C$. The optimum ripening temperature of the 30 DAH for the production of high anthocyanin and total polyphenol was 22 to $23^{\circ}C$ for early maturity black rice, 21 to $22^{\circ}C$ for mid-late maturity of black and red rices, respectively. On the other hand, an estimated heading date of pigmented rices in return according to the optimum ripening temperature of the 30 DAH was ranged Aug. 11 to 17 for early maturity black rice, Aug. 25 for mid-late maturity black, red rice variety in Jecheon, Aug. 27 to Sep. 2 for early maturity type, Sep. 3 to 6 for mid-late type in Daegu. It seemed that Jecheon, Boeun, Mungyeong, and Yeongju were optimum regions for cultivation of pigmented rices. The estimated sowing date of pigmented rices for high anthocyanin and total polyphenol production based on the optimum heading date was May 18 to 26 for early maturity black rice variety, April 11 for mid-late black, red variety in Jecheon, May 23 to 28 for early type, April 9 to 26 for mid-late type in Boeun, respectively.

• 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 Ginseng Culture
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• v.2
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• pp.17-26
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• 2020

Ginseng, also known as Insam, has solidified its status as one of the supreme drugs classified as life time expansion drug since ancient times and was used as a panacea based on its pharmaceutical effectiveness. The demand for ginseng rapidly increased as the demand for ginseng, which targeted only noble class people, expanded to other social class people. Accordingly, the wild ginseng supply reached its limit due to the extinction caused by indiscriminate harvesting and the difficulty of harvesting, and thus the ginseng supply method shifted to the cultivation of high-priced ginseng rather than complicated wild ginseng foraging. Although the timing of ginseng cultivation (also called gasam) in Korea has been studied, the research on the first cultivation area has not been reported yet. In this study, we critically reviewed Korea's first ginseng cultivation site by arranging data related to ginseng cultivation, and the historical data cited here include Joseon Wangjo Sillog (The Annals of Joseon Dynasty), Imwon Gyeongjeji (The Mid-19 Century Encyclopedia Koreana on Rural Living, Edible plants and Herb Volumes), Oju Yeonmun Jangjeon Sango (An Encyclopedic Writing during the Latter Half Period of the Joseon Dynasty), Junggyeongji (The Junggyeong Town Chronicle), Jeungbo Munheon Bigo (The largest encyclopedia of Joseon Dynasty), Insamsa (The Ginseng History) and etc. As a result of data assortment and critical review, the first ginseng plantation in the Joseon Dynasty resulted in the Yeongnam region, and in Yeongnam region, I have no choice but to conclude that it is Punggi-myeon (currently Punggi-eup, Yeongju-si, Gyeongbuk).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.264-273
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• 2020

'Ilpum', a Korean short-grain mid-late maturing rice cultivar, was developed in 1990, more than 30 years ago. Despite its age, it has been the most widely grown cultivar in the Gyeongbuk province of South Korea for more than 25 years, making it the most important rice cultivar for the people of the Gyeongbuk province. The aim of this study was to analyze the relationship between the rice yield of "Ilpum', the main rice cultivar in the Gyeongbuk province, and climate elements in the Daegu (southern plain area) and the Andong (inland mountainous area) regions in Gyeongbuk, South Korea. The rice yield over the past five years increased by about 13% and 24%, compared to that produced in the late 1990s in Daegu and the early 2000s in the Andong region, respectively. The number of panicles per hill and the grain ripening rate significantly affected rice yield in the 'Ilpum' cultivars in the Daegu region. The faster heading was a factor in the increase in 'Ilpum' rice yield in the Andong region. The air temperature has been rising and sunshine duration has been increasing from the late 1990s to present in both regions. Rice yield was evaluated to understand the effect of climate factors. The rice yields increased owing to the long sunshine duration during the grain-filling stage in both regions. In Andong, increasing the maximum temperature during the vegetative stage increased rice yield. Rising air temperature during the reproductive stage also increased rice yield. In particular, long sunshine hours throughout the whole rice growing period increased the rice yield of this cultivar in the Andong region.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.473-478
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• 2009

The purpose of this study is to evaluate the behaviour of the plastic deformed zone at crack tip on the standard Charpy specimens which were taken from the multi-passed weld block of the pressure vessel steel. Notch was machined on the standard Charpy test specimens and pre-crack which was located around the fusion line was made under the repeat load. Four point bend and acoustic emission tests were carried out simultaneously. The size of plastic region at crack tip was calculated using stress intensity factor. Relationships between characteristics of acoustic emission and plastic zone size at crack tip were discussed through the cumulative AE energy. Regardless of the specimens, AE signals were absent within the elastic region almost and most of AE signals were produced at the plastic deformation region from yield point to the mid-point between yield and maximum load. More AE signals for the weldment were produced compared with the base-metal and PWHT specimen. Relations between plastic deformed zones at crack tip and cumulative AE energy for the weldment and PWHT specimen were different quietly from the base-metal. Besides, number of AE counts for the weldment was the larger than those of the base-metal and PWHT specimen.

• Journal of the Korean association of regional geographers
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• v.20 no.4
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• pp.357-378
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• 2014

The concern on new regional geography in Korea has emerged in the 1990s under the influence of paradigm shift of Western geography, that is, the withering of positivist geography and the introduction of grand social theories into geography. New regional geography in Korea also seems to have developed in the rapidly changing process of glocalization of capitalism which has accompanied with the transformation toward post-Fordism with high-tech innovation, development of transportation and communication technology with time-space compression, and increasing social and cultural mobility with change of identity. But it can be pointed out that discussion on methodology for regional geography in Korea has been shrunken since the mid 2000s, and there has been relatively little empirical research with synthetic approach to region. But more concern on methodology in terms of place, territory, network, scale, etc. rather than the concept of region itself has increased, and empirical researches on regions in specific fields of human geography have been promoted. It is argued that the traditional distinction between synthetic and analytic approaches seems no longer significant. But geographers need to extend the concept of region in relation to other diverse spatial concepts, and to purse simultaneously structural analysis on glocalization process and practical strategies responding positively to the process.

• Journal of Trauma and Injury
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• v.30 no.4
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• pp.158-165
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• 2017

Purpose: The purpose of this study was to evaluate the diagnostic accuracy of X-rays in patients with acute traumatic vertebral fractures visiting the emergency department and to analyze the diagnostic value of X-rays for each spine level. Methods: We retrospectively analyzed basal characteristics by reviewing medical records of 363 patients with adult traumatic vertebral fractures, admitted to the emergency center from March 1, 2014 to February 28, 2017. We analyzed spine X-rays and magnetic resonance imaging (MRI) scans to determine distribution according to the vertebral level, and we evaluated the efficacy of X-rays by comparing discrepancies between X-rays and MRI scans. Results: For a total of 363 patients, the mean age was 56.65 (20-93) and 214 (59%) were males. On the basis of X-rays, 67 cases (15.1%) were of the cervical spine, 133 cases (30.0%) were of the thoracic spine, and 243 cases (54.9%) were of the lumbar spine. In particular, the thoracolumbar region (T11-L2) was the most common, with 260 cases (58.7%). In X-rays, fractures were the least in the upper thoracic region (T1-T3), whereas MRI scans revealed fairly uniform distribution across the thoracic spine. Sensitivity of X-rays was lowest in the upper thoracic spine and specificity was almost always greater than 98%, except for 94.7% in L1. Positive predictive value was lower in the mid-thoracic region (T4-T9) and negative predictive value was slightly lower in C6, T2, and T3 than at other sites. Diagnostic accuracy of X-rays by vertebral body, transverse process, and spinous process according to fractured vertebral structures was significantly different according to vertebral level. Conclusions: Diagnostic accuracy of X-rays was lower in the upper thoracic region than in other parts. Further studies are needed to identify better methods for diagnosis considering cost and neurological prognosis.

• Journal of the Korean association of regional geographers
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• v.15 no.6
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• pp.752-762
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• 2009

This paper aims to investigate the characteristics of location and business-services networks of venture firms in Daegu region. The regional venture firms are small scale and consist of mainly R&D investment and license new-technology in the category of soft-ware. Since the mid-1990's the firms that were founded by people with higher education and career experience seek diverse growth strategies. those firms concentrate in some regions of dalseo-gu and buk-gu. There are a few difference by types of firm-business, but, on the whole, the princepal location factors of venture firms are accessibility of research institute and university, easy information availability, and use of moderate land. In regard to networks with client firms, the venture firms determine whether to transfer. The result of the characteristics of networks between regional venture firms and business-service enterprises is as follows; the regional venture firms utilize small number of business-service enterprises and use mainly information processing and other computer operation related services and professional, scientific and technical services. In business-service be used by regional venture firms, the frequency of information processing and other computer operation related services, research and development, business support services is much, while the frequency of professional, scientific and technical services is little. Business-service enterprises are distributed mostly in Daegu region and are used owing to lack of technology and knowledge.