• Title/Summary/Keyword: dynamic characteristics

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The effect of tunnel ovality on the dynamic behavior of segment lining (Ovality가 세그먼트 라이닝의 동적 거동 특성에 미치는 영향)

  • Gyeong-Ju Yi;Ki-Il Song
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.6
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    • pp.423-446
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    • 2023
  • Shield TBM tunnel linings are segmented into segments and rings. This study investigates the response characteristics of the stress and displacement of the segment lining under seismic waves through modeling that considers the interface behavior between segments by applying a shell interface element to the contact surface between segments and rings. And there is no management criteria for ovaling deformation of segment linings in Korea. So, this study the ovality criteria and meaning of segment lining. The results of study showed that the distribution patterns of stress and displacement under seismic waves were similar between continuous linings and segment linings. However, the maximum values of stress and displacement showed differences from segment linings. The stress distribution of the continuous lining modeled as a shell type has a stress distribution that has continuity in the 3D cylindrical shape, but the segment lining is concentrated outside the segment, and the largest stress occurs at the location where the contact surface between the segment and the ring is concentrated. This intermittent and localized stress distribution shows an increasing as the ovality of the lining increases at seismic waves. The ovality at which the increase in stress distribution begins to show irregularity and localization is about 150‰. Ovality of 150‰ is an unrealistic value that cannot represent actual lining deformation. Therefore, the ovality of the segment lining increase with depth, but it does not have a significant impact on the stability caused by seismic load.

Investigation of fish community structure and species diversity in two river estuary ecosystems, the Taehwa River and Changwon Stream, based on conventional survey and eDNA metabarcoding (어구조사 및 환경 DNA 메타바코딩을 이용한 태화강, 창원천 하구 생태계의 어류 군집 구조 및 종 다양성 평가)

  • Hee-kyu Choi;Yu Rim Kim;Soon Young Hwang;Yeounsu Chu;Pyoungbeom Kim;Hyuk Je Lee
    • Korean Journal of Environmental Biology
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    • v.41 no.4
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    • pp.637-656
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    • 2023
  • River estuaries are dynamic and productive ecosystems with high regional biodiversity. Environmental DNA (eDNA) has become a useful approach to assessing biodiversity in aquatic ecosystems. This study was conducted to investigate fish community characteristics and species diversity in two river estuary ecosystems, the Taehwa River and Changwon Stream. We further compared conventional and eDNA metabarcoding analyses of the fish communities. The conventional survey was performed in May, July, and October 2022, while the eDNA analysis was conducted only in May. We observed various fish species with different life histories, including carp, goby, and marine fish. We also found that migratory fish, such as dace Tribolodon hakonensis, sweetfish Plecoglossus altivelis, and eel Auguilla japonica, occurred in the Taehwa River, suggesting high river connectivity. Marine fish species were predominant in the Changwon Stream, as this river is located close to the sea. The diversity indices showed that the Taehwa River generally had higher species richness, evenness, and diversity values than the Changwon Stream. A total of 9-19 species were detected in the conventional survey for the three sites, whereas 11-18 species were found from eDNA analysis. The findings indicate that the sensitivity of eDNA was similar to or higher than that of the conventional method. Our study findings suggest the efficiency and efficacy of eDNA-based fish community monitoring, although with some shortcomings in applying the genetic marker to Korean fish, including no clear-cut distinction for Korean endemic species and/or genetically closely related species groups.

The Development and Validation of a Core Competency Scale for Startup Talent : Focusing on ICT Sector Employees (스타트업 핵심인재 역량 척도 개발 및 타당화 : 정보통신기술(ICT)분야 종사자를 대상으로)

  • Han, Chae-yeon;Ha, Gyu-young
    • Journal of Venture Innovation
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    • v.7 no.3
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    • pp.183-228
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    • 2024
  • This study aimed to develop a competency evaluation scale tailored to the specific needs of key talent in the ICT startup sector. Existing competency assessment tools are mostly designed for environments in large corporations or traditional small and medium-sized enterprises, failing to adequately reflect the dynamic requirements of rapidly evolving startups. For startups, where a small number of individuals directly impact company success, key talent is a critical asset. Accordingly, this study sought to create a scale that measures the competencies suited to the challenges and opportunities faced by startups, helping domestic startups establish more effective talent management strategies. The research initially selected 71 items through a literature review and in-depth interviews. Based on expert feedback that emphasized the need for more precise and clear descriptions, the item descriptions were revised, and a total of 65 items were developed through four rounds of content validation. Following preliminary and main surveys, a final set of 58 items was developed. The main survey conducted further factor analysis based on the three broad competency factors?knowledge, skills, and attitude?identified in the preliminary survey. As a result, 10 latent factors emerged: 6 items for task comprehension, 6 items for practical experience (tacit knowledge), 6 items for collaboration, 9 items for management and problem-solving, 9 items for practical skills, 4 items for self-direction, 5 items for goal orientation, 5 items for adaptability, 5 items for relationship orientation, and 3 items for organizational loyalty. The developed scale comprehensively covers the multifaceted nature of competencies, allowing for a thorough evaluation of essential skills such as technical ability, teamwork, innovation, and leadership, which are critical for startups. Therefore, the scale provides a tool that helps startup managers objectively and accurately assess candidates' competencies. It also supports the growth of employees within startups, maximizing the overall organizational performance. By utilizing this tool, startups can build a strong internal talent pool and continuously enhance employees' competencies, thereby strengthening organizational competitiveness. In conclusion, the competency evaluation scale developed in this study is a customized tool that aligns with the characteristics of startups and plays a crucial role in securing sustainable competitiveness in rapidly changing market environments. Additionally, it offers practical guidance to support the successful growth of domestic startups and help them maintain their competitive edge in the market, contributing to the development of the startup ecosystem and the growth of the national economy.

Phytoplankton Diversity and Community Structure Driven by the Dynamics of the Changjiang Diluted Water Plume Extension around the Ieodo Ocean Research Station in the Summer of 2020 (2020년 하계 장강 저염수가 이어도 해양과학기지 주변 해역의 식물플랑크톤 다양성 및 개체수 변화에 미치는 영향)

  • Kim, Jihoon;Choi, Dong Han;Lee, Ha Eun;Jeong, Jin-Yong;Jeong, Jongmin;Noh, Jae Hoon
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.7
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    • pp.924-942
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    • 2021
  • The expansion of the Changjiang Diluted Water (CDW) plume during summer is known to be a major factor influencing phytoplankton diversity, community structure, and the regional marine environment of the northern East China Sea (ECS). The discharge of the CDW plume was very high in the summer of 2020, and cruise surveys and stationary monitoring were conducted to understand the dynamics of changes in environmental characteristics and the impact on phytoplankton diversity and community structure. A cruise survey was conducted from August 16 to 17, 2020, using R/V Eardo, and a stay survey at the Ieodo Ocean Research Station (IORS) from August 15 to 21, 2020, to analyze phytoplankton diversity and community structure. The southwestern part of the survey area exhibited low salinity and high chlorophyll a fluorescence under the influence of the CDW plume, whereas the southeastern part of the survey area presented high salinity and low chlorophyll a fluorescence under the influence of the Tsushima Warm Current (TWC). The total chlorophyll a concentrations of surface water samples from 12 sampling stations indicated that nano-phytoplankton (20-3 ㎛) and micro-phytoplankton (> 20 ㎛) were the dominant groups during the survey period. Only stations strongly influenced by the TWC presented approximately 50% of the biomass contributed by pico-phytoplankton (< 3 ㎛). The size distribution of phytoplankton in the surface water samples is related to nutrient supplies, and areas where high nutrient (nitrate) supplies were provided by the CDW plume displayed higher biomass contribution by micro-phytoplankton groups. A total of 45 genera of nano- and micro-phytoplankton groups were classified using morphological analysis. Among them, the dominant taxa were the diatoms Guinardia flaccida and Nitzschia spp. and the dinoflagellates Gonyaulax monacantha, Noctiluca scintillans, Gymnodinium spirale, Heterocapsa spp., Prorocentrum micans, and Tripos furca. The sampling stations affected by the TWC and low in nitrate concentrations presented high concentrations of photosynthetic pico-eukaryotes (PPE) and photosynthetic pico-prokaryotes (PPP). Most sampling stations had phosphate-limited conditions. Higher Synechococcus concentrations were enumerated for the sampling stations influenced by low-nutrient water of the TWC using flow cytometry. The NGS analysis revealed 29 clades of Synechococcus among PPP, and 11 clades displayed a dominance rate of 1% or more at least once in one sample. Clade II was the dominant group in the surface water, whereas various clades (Clades I, IV, etc.) were found to be the next dominant groups in the SCM layers. The Prochlorococcus group, belonging to the PPP, observed in the warm water region, presented a high-light-adapted ecotype and did not appear in the northern part of the survey region. PPE analysis resulted in 163 operational taxonomic units (OTUs), indicating very high diversity. Among them, 11 major taxa showed dominant OTUs with more than 5% in at least one sample, while Amphidinium testudo was the dominant taxon in the surface water in the low-salinity region affected by the CDW plume, and the chlorophyta was dominant in the SCM layer. In the warm water region affected by the TWC, various groups of haptophytes were dominant. Observations from the IORS also presented similar results to the cruise survey results for biomass, size distribution, and diversity of phytoplankton. The results revealed the various dynamic responses of phytoplankton influenced by the CDW plume. By comparing the results from the IORS and research cruise studies, the study confirmed that the IORS is an important observational station to monitor the dynamic impact of the CDW plume. In future research, it is necessary to establish an effective use of IORS in preparation for changes in the ECS summer environment and ecosystem due to climate change.

An Essay on the Change of Jinju Sword Dance after being designated as an Important Intangible Cultural Asset (<진주검무> 중요무형문화재 지정 이후의 변화에 관한 소고)

  • Lee, Jong Sook
    • Korean Journal of Heritage: History & Science
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    • v.49 no.1
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    • pp.4-21
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    • 2016
  • The purpose of this study is to investigate changes of Jinju Sword Dance, characteristics of the changes, and the current condition of its preservation and succession after the designation as the important intangible cultural property no. 12 in January 16th, 1967. In other words, this study understands the situation which has established the present state of after changes over generations. As of now. the year of 2015, the 3 generation holders have been approved since 1967. In 1967, 8 members of $1^{st}$ generation holders were selected from gisaengs of Gwonbeon. However, the succession training was incomplete due to conflicts among the holders, the deaths of some holders, and economic activities of the individuals. As the need of a pivot for succession training and activities was rising, Seong, Gye-Ok was additionally approved as the $2^{nd}$ generation holder on June $21^{st}$, 1978. Seong, Gye-Ok who had never been a gisaeng had dramatically changed with a lot of new attempts. After the death of Seong, Gye-Ok in 2009, Kim, Tae-Yeon and Yu, Yeong-Hee were approved as the $3^{rd}$ generation holders in February, 2010. Based on the resources including the "Cultural Research Reports of Important Intangible Cultural Properties" in 1966 and videos up to 2014, the changes of the dance and surroundings are as follow. 1. The formation of musical accompaniment has been changed during the 3 generations. In the video of the $1^{st}$ generation(in 1970), the performance lasted about 15 minutes, whereas the performance lasted 25 minutes in the video of the $2^{nd}$ generation. Yumbuldoduri rhythm was considered as Ginyumbul(Sangryeongsan) and played more slowly. The original dance requiring only 15 rhythms was extended to 39 rhythms to provide longer performance time. In the $3^{rd}$ generation, the dance recovered 15 rhythms using the term Ginyumbul. The facts that Yumbul was played for 3 minutes in the $1^{st}$ generation but for 5 minutes in the 3rd generation shows that there was tendency pursuing the slowness from the $2^{nd}$ generation. 2. For the composition of the Dance, the performance included additional 20 rhythms of Ginyumbul and Ah(亞)-shaped formation from the $2^{nd}$ generation. From the $3^{rd}$ generation, the performance excluded the formation which had no traditional base. For the movement of the Dance, the bridge poses of Ggakjittegi and Bangsukdoli have been visibly inflexible. Also, the extention of time value in 1 beat led the Dance less vibrant. 3. At the designation as an important intangible cultural property (in 1967), the swords with rotatable necks were used, whereas the dancers had been using the swords with non-rotatable necks since late 1970s when the $2^{nd}$ generation holder began to used them. The swords in the "Research Reports" (in 1966) was pointy and semilunar, whereas the straight swords are being used currently. The use of the straight swords can be confirmed from the videos after 1970. 4. There is no change in wearing Jeonlib, Jeonbok, and Hansam, whereas the arrangement of Saekdong of Hansam was different from the arrangement shown in the "Research Reports". Also, dancers were considered to begin wearing the navy skirts when the swords with non-rotatable necks began to be used. Those results showed that has been actively changed for 50 years after the designation. The $2^{nd}$ generation holder, Seong, Gye-Ok, was the pivot of the changes. However, , which was already designated as an important intangible cultural property, is considered to be only a victim of the change experiment from the project to restore Gyobang culture in Jinju, and it is a priority to conduct studies with historical legitimacy. First of all, the slowing beat should be emphasized as the main fact to reduce both the liveliness and dynamic beauty of the Dance.

A Study on Plant Symbolism Expressed in Korean Sokwha (Folk Painting) (한국 속화(俗畵)(민화(民畵))에 표현된 식물의 상징성에 관한 연구)

  • Gil, Geum-Sun;Kim, Jae-Sik
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.29 no.2
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    • pp.81-89
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    • 2011
  • The results of tracking the symbolism of plants in the introduction factors of Sokhwa(folk painting) are as the following. 1. The term Sokhwa(俗畵) is not only a type of painting with a strong local customs, but also carries a symbolic meaning and was discovered in "Donggukisanggukjip" of Lee, Gyu-Bo(1268~1241) in the Goryo era as well as the various usage in the "Sok Dongmunseon" in the early Chosun era, "Sasukjaejip" of Gang, Hee-mang(1424~1483), "Ilseongrok(1786)" in the late Chosun era, "Jajeo(自著)" of Yoo, Han-joon(1732~1811), and "Ojuyeonmunjangjeonsango(五洲衍文長箋散稿)" of Lee, Gyu-gyung(1788~?). Especially, according to the Jebyungjoksokhwa allegation〈題屛簇俗畵辯證說〉in the Seohwa of the Insa Edition of Ojuyeonmunjangjeonsango, there is a record that the "people called them Sokhwa." 2. Contemporarily, the Korean Sokhwa underwent the prehistoric age that primitively reflected the natural perspective on agricultural culture, the period of Three States that expressed the philosophy of the eternal spirits and reflected the view on the universe in colored pictures, the Goryo Era that religiously expressed the abstract shapes and supernatural patterns in spacein symbolism, and the Chosun Era that established the traditional Korean identity of natural perspective, aesthetic values and symbolism in a complex integration in the popular culture over time. 3. The materials that were analyzed in 1,009 pieces of Korean Sokhwa showed 35 species of plants, 37 species of animals, 6 types of natural objects and other 5 types with a total of 83 types. 4. The shape aesthetics according to the aesthetic analysis of the plants in Sokhwa reflect the primitive world view of Yin/yang and the Five Elements in the peony paintings and dynamic refinement and biological harmonies in the maehwado; the composition aesthetics show complex multi-perspective composition with a strong noteworthiness in the bookshelf paintings, a strong contrast of colors with reverse perspective drawing in the battlefield paintings, and the symmetric beauty of simple orderly patterns in nature and artificial objects with straight and oblique lines are shown in the leisurely reading paintings. In terms of color aesthetics, the five colors of directions - east, west, south, north and the center - or the five basic colors - red, blue, yellow, white and black - are often utilized in ritual or religious manners or symbolically substitute the relative relationships with natural laws. 5. The introduction methods in the Korean Sokhwa exceed the simple imitation of the natural shapes and have been sublimated to the symbolism that is related to nature based on the colloquial artistic characteristics with the suspicion of the essence in the universe. Therefore, the symbolism of the plants and animals in the Korean Sokhwas is a symbolic recognition system, not a scientific recognition system with a free and unique expression with a complex interaction among religious, philosophical, ecological and ideological aspects, as a identity of the group culture of Koreans where the past and the future coexist in the present. This is why the Koran Sokhwa or the folk paintings can be called a cultural identity and can also be interpreted as a natural and folk meaningful scenic factor that has naturally integrated into our cultural lifestyle. However, the Sokhwa(folk paintings) that had been closely related to our lifestyle drastically lost its meaning and emotions through the transitions over time. As the living lifestyle predominantly became the apartment culture and in the historical situations where the confusion of the identity has deepened, the aesthetic and the symbolic values of the Sokhwa folk paintings have the appropriateness to be transmitted as the symbolic assets that protect our spiritual affluence and establish our identity.