• Title/Summary/Keyword: SON structure

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Damage Detection in Cable-Stayed Bridges Using Vibration Modes (진동모드를 이용한 사장교의 손상 검색)

  • Kong, Min-Sik;Ka, Hoon;Son, Seok-Ho;Yhim, Sung-Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.6
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    • pp.113-123
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    • 2006
  • As Cable-stayed bridges were constructed to the long span, they have become bigger and had weaknesses to vibration induced by earthquake, wind and vehicle loads. Structural damages induced by these loads affect the characteristic of vibration modes of structure. Damage detection of cable-stayed bridges by using existing safety diagnosis is difficult to detect the characteristic change of overall structural action. Also it requires very much time and cost. So in this study, the investigation of characteristic change of structural action and the detection of structural damages is analyzed by using characteristic properties of vibration mode before and after structural damage.

Dynamic Recrystallization Effect on the Fracture Toughness of Al7050 Extruded Components (동적 재결정에 따른 Al7050 압출재의 파괴인성 변화)

  • J. W. Choi;Y. H. Jung;J. I. Son;B. G. Cheon;J. G. Kim
    • Transactions of Materials Processing
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    • v.33 no.5
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    • pp.315-321
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    • 2024
  • Although achieving a high fracture toughness is essential for designing reliable aircraft components using aluminum alloys, only a limited number of studies have discussed the relationship between microstructure and fracture toughness. Therefore, in this study, the effects of dynamic recrystallization on the fracture toughness of Al7050 extruded alloy were investigated. Because of the temperature deviation in the extruded large component, incomplete dynamic recrystallization (DRX) occurred that results into the higher Kernel average misorientation (KAM) and sub-grain structure fraction compare with the complete DRX region. Although incomplete DRX changes KAM and sub-grain fraction, the strength and ductility difference between complete and incomplete DRX regions are not in big difference. The accumulated KAM reduces the plastic zone size, and both cleavage and a lower micro-void fraction are observed in the incomplete DRX region. Based on the different fracture behavior from different DRX behavior, the fracture toughness of the incomplete DRX is lower than that of the complete DRX region. This result implies how a different DRX behavior from temperature variation affects to the fracture toughness of high-strength aluminum alloys.

Analysis of the operation status and opinion on the improvement of fishing vessel structure in coastal improved stow net fishery by the questionnaire survey (설문조사를 통한 연안개량안강망어업의 조업 실태 및 어선 구조 개선에 관한 의견 분석)

  • CHANG, Ho-Young;KIM, Min-Son;HWANG, Bo-Kyu;OH, Jong Chul
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.57 no.4
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    • pp.316-333
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    • 2021
  • In order to understand basic data for improving the fishing system and fishing vessel structure in coastal improved stow net fishery, a questionnaire survey and on-site hearing were conducted from May 10 to June 11, 2019 to analyze opinions on the improvement of operation status and fishing vessel structure. The questionnaire survey consisted of ten questions on the operation status of coastal improved stow net fishery and six questions on the improvement of fishing vessel structure, and the results of each question were analyzed by the region, the captain's age, the captain's career and the age of fishing vessel. As a result of analyzing opinions on the operation status of the coastal improved stow net fishery, it was found that the average time required for casting net was 32.8 to 33.0 minutes and that the average time required for hauling net was 41.0 to 42.2 minutes which took 10 to 12 minutes more than for casting net. The most important work requiring improvement during fishing operation (the first priority) were 'hauling net operation,' 'readjustment and storage of fishing gear,' and 'fish handling' and the hardest factor in fishing management were in the order of 'reduction of catch,' 'labor shortage' and 'rising labor costs.' The most institutional improvement that is most needed in coastal improved stow net fishery was an 'using fine mesh nets.' Most of the respondent to the questions on the experience in hiring foreign crews was 'either hiring or willing to hire foreign crews,' and the average number of foreign crews employed was found to be 2.3 to 2.4 persons. The most important reason for hiring (or considering employment) foreign crews was 'high labor costs.' The degree of communication with foreign crews during fishing operation were 'moderate' or 'difficult to direct work.' The most important problem in hiring foreign crews (the first priority) was an 'illegal departure.' As the survey results on the opinion of structural improvement of coastal improved stow net fishing vessel, the degree of satisfaction with fishing vessel structure related to fishing operation was found to be somewhat unsatisfactory, with an average of 3.3 points on a five-point scale. The inconvenient structure of fishing vessel in possession (the first priority), the space needed most for the construction of new fishing vessel (the first priority) and the space considered important for the construction of new fishing vessel (the first prioprity) was a 'fish warehouse.' The most preferred equipment for the construction of new fishing vessel were 'engine operation monitoring' and 'navigation safety devices.' The average size (tonnage class), the average horse power and the average total length of fishing vessel for proper profit and safety fishing operation was between 13.8 and 14.0 tonnes, 808.3 to 819.5 H.P. and 23.4 to 23.5 meters, respectively. The results of the operation status of coastal improved stow net fishery and the requirement for improving the fishing vessel structure are expected to be provided as basic data for reference when we build or improve the fishing vessel.

The Stratigraphy and Geologic Structure of the Great Limestone Series in South Korea (남한(南韓) 대석회암통(大石灰岩統)의 층서(層序)와 지질구조(地質構造))

  • Kim, Ok Joon;Lee, Ha Young;Lee, Dai Sung;Yun, Suckew
    • Economic and Environmental Geology
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    • v.6 no.2
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    • pp.81-114
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    • 1973
  • The purpose of the present study is to clarify the stratigraphy and geologic structure of the Great Limestone Series by means of study on fossil conodonts and detail investigation of geologic structure. In recent years very few geologists in Korea argue without confident evidences against the age and stratigraphy of the Great Limestone Series which have been rather well established previously in most parts of the regions although it is ambiguous and has not been studied in other areas. Five type localities in the Kangweon basin where the Great Limestone Series is well cropped out were chosen for the study. Total 26 genus and 66 species of conodont were identified from 290 samples collected and treated. From the study on conodonts the age of each formations of the Great Limestone Series has been determined as follows: The Great Limestone Series of Duwibong type Duwibong limestone: Caradocian (mid-Ord.) Jikunsan shale: Landeilian (mid-Ord.) Maggol limestone: Llanvirn-Llandeilian (mid-Ord.) Dumugol: Arenigian (Ord.) Hwajeol: Upper Cambrian The Great Limestone Series of Yeongweol type Mungok (Samtaesan) : Ordovician Machari: upper Cambrian The Great Limestone Series of Jeongseon type Erstwhile Jeongseon limestone: mid-Ord. The erstwhile Jongseon Limestone formation in Jeongseon district is separated into Hwajeol, Dongjeom, Dumudong, and Maggol formations which were cropped out repeatedly by folding and faulting, but Maggol is predominant in areal distribution. Yemi Limestone Breccia bed is not a single bed but distributed in several horizons so that it bears no stratigraphic significance. The limestone bed above Yemi Limestone Breccia, which was believed by some geologists to be much younger than Ordovician, is identified to be Maggol and its age is determined to be mid-Ordovician. Sambangsan formation in Yeongweol district was believed to be Cambrian age and lower horizon than Machari formation by Kobayashi, but C. M. Son believed that it might belong to later than Ordovician and lies above the Great Limestone Series of Yeongweol type. It was identified to be upper Cambrian and lies beneath the Machari formation and above the Daeki formation, the lower most horizon of the Great Limestone Series. The age of Yeongweol type Choseon system is contemporaneous with that of Duwibong type Choseon system. The difference in lithofacies is not due to lateral facies change, but due to the difference in its depositional environment. The Yeongweol type Choseon system is believed to be deposited in the small Yeongweol basin which was separated from the main Kangweon sedimentary basin. Judging from these facts it is definitely concluded that there exists no Gotlandian formation in the regions studied. Structurally the Kangweon basin comprises five basins and two uplifted areas. These structures were originated by at least two crustal movements, that is, Songrim disturbance of Triassic and Daebo orogeny of Jurasic age.

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Community Structure, Productivity, and Nutrient Uptake of the Vascular Plants in the Wetlands of the Asan-Lake (아산호 습지에서 관속식물의 군집 구조와 생산성 및 영양염류의 흡수)

  • Kim, Cheol-Soo;Son, Sung-Gon;Lee, Jeong-Hwan;Oh, Kyung-Hwan
    • The Korean Journal of Ecology
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    • v.23 no.3
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    • pp.201-209
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    • 2000
  • The flora, distribution area, vegetation structure, annual net primary production, and nutrient uptake of the vascular hydrophytes, hygrophytes and mesophytes were investigated in the wetlands of the Asan-Lake, Chungchongnam-do and Kyonggi-do, Korea from March to October in 1997 to reveal the correlation between the plant community and the lake environment. The flora was composed of 38 families, 89 genera, 106 species, 14 varieties or total 120 kinds of the vascular plants. The life from of the hydrophytes were classified as 14 kinds of emergent plants, 5 kinds of submerged plants, and 4 kinds of free-floating plants, respectively. The number of species was various to 4 ∼85 kinds in each site. The dominant species was Zizania latifolia, and the importance values of Zizania latifolia, Typha orientalis, Phragmites communis, and Spirodela polyrhiza were 39.58, 14.90, 13.97, and 7.64, respectively. The distribution area of the emergent hydrophytes, hygrophytes, and mesophytes was 49.3 ㏊ (90.5%), and free-floating plants was 5.2 ㏊ (9.5%), whereas the floating-leaved and submersed plants were rare. Annual net production of the emergent hydrophytes, hygrophytes, and mesophytes was 547.9 ton D.W./yr (98%), and those of the free-floating plants was 10.5 ton D.W./yr (2%), and 558.4 ton D.W./yr in the whole lake ecosystem. The total uptake of nitrogen and phosphorus by the vascular plants was 7,099 and 1,891 ㎏/yr in the whole lake ecosystem.

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Design of a Low Phase Noise Vt-DRO Based on Improvement of Dielectric Resonator Coupling Structure (유전체 공진기 결합 구조 개선을 통한 저위상 잡음 전압 제어 유전체 공진기 발진기 설계)

  • Son, Beom-Ik;Jeong, Hae-Chang;Lee, Seok-Jeong;Yeom, Kyung-Whan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.6
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    • pp.691-699
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    • 2012
  • In this paper, we present a Vt-DRO with a low phase noise, which is achieved by improving the coupling structure between the dielectric resonator and microstrip line. The Vt-DRO is a closed-loop type and is composed of 3 blocks; dielectric resonator, phase shifter, and amplifier. We propose a mathematical estimation method of phase noise, using the group delay of the resonator. By modifying the coupling structure between the dielectric resonator and microstrip line, we achieved a group delay of 53 nsec. For convenience of measurement, wafer probes were inserted at each stage to measure the S-parameters of each block. The measured S-parameter of the Vt-DRO satisfies the open-loop oscillation condition. The Vt-DRO was implemented by connecting the input and output of the designed open-loop to form a closed-loop. As a result, the phase noise of the Vt-DRO was measured as -132.7 dBc/Hz(@ 100 kHz offset frequency), which approximates the predicted result at the center frequency of 5.3 GHz. The tuning-range of the Vt-DRO is about 5 MHz for tuning voltage of 0~10 V and the power is 4.5 dBm. PFTN-FOM is -31 dBm.

Differences in Habitat Structure and Herpetofauna Populations Caused by Thinning (간벌에 의한 서식지 구조와 양서·파충류 개체군의 특성 차이)

  • Park, Chang-Deuk;Jung, Ji-Hwa;Son, Seung-Hun;Hwang, Hyun-Su;Lee, Woo-Shin
    • Journal of Korean Society of Forest Science
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    • v.105 no.2
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    • pp.268-273
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    • 2016
  • This study was conducted to clarify the differences in habitat structure and amphibian and reptile (herpetofauna) populations between before and after thinning in the coniferous and deciduous forests from June to September 2014 and 2015 at the Mt. Maewha of Hongcheon, Gangwon province, Korea. Forest structure was dramatically changed after thinning. Coverage of understory and mid-story were decreased while volume and number of downed trees were increased after thinning. We used line transect sampling method on a total of 4 transect lines, 2 lines in each forest type. 119 individuals of 5 amphibian species and 5 individuals of 3 reptile species were recorded. Mean number of amphibian species were decreased after thiining in the coniferous forest. There was no observed reptiles after thinning in the coniferous and deciduous forests. Detailed monitoring with different area, frequency and intensity might be needed to clarify more precise differences characterisitics of herpetofauna by thinning.

Distribution patterns of macrobenthos in the sandy shore of Hakampo, Korea (학암포 사질조간대 대형저서동물의 분포양상)

  • Nam, Ki-Ung;Ma, Chae-Woo;Son, Dae-Sun;Kim, Jong-Chun
    • Korean Journal of Environment and Ecology
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    • v.29 no.5
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    • pp.729-735
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    • 2015
  • This study was carried out to analyze the community structure and distribution of macrobenthos in Hakampo sandy shore. As for the environmental factors of sampling stations, the average grain size of the sediments from the sampling stations was $2.37{\phi}$ with the range of $1.90{\phi}{\sim}2.52{\phi}$, which represents the typical medium sand sedimentary facies of sandy beach. The average sediment organic content was 1.15% with the range of 0.90%~1.46%. Most stations had low sediment organic content which is typical of sandy beach. The number of species were total 59 from 6 taxa and the individuals was $668inds./m^2$ in the 10 stations of the study area. Based on the Bray-Curtis similarity analysis, the 10 stations of the study area were broadly divided into 3 groups. The highest part of intertidal zone was St. 2~St. 4, the middle part of intertidal zone was St. 5~St. 8, and the lower part of intertidal zone was St. 9~St. 10. A spatial community structure was observed which is divided into the highest, middle, and lower parts.

Design of a Miniaturized 5.3 GHz 360° Analog Phase Shifter (소형화된 5.3 GHz 대역 360° 아날로그 위상천이기 설계)

  • Jeong, Hae-Chang;Son, Bon-Ik;Lee, Dong-Hyun;Ahmed, Abdul-Rahman;Yeom, Kyung-Whan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.6
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    • pp.602-612
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    • 2013
  • In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type $360^{\circ}$ analog phase shifter with branch line coupler and $360^{\circ}$ variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and ${\pi}$ type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, $360^{\circ}$ variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with $15{\times}15mm^2$ shows wide phase shift of above $480^{\circ}$, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

The Conceptual Structure of Intellectual Capital in Fashion Companies (패션기업의 지적자본 개념구조)

  • Son, Jin Ah
    • The Journal of the Convergence on Culture Technology
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    • v.1 no.4
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    • pp.27-43
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    • 2015
  • The objective of this study is to find out the construct of intellectual capital in a fashion company. To this end, the mixed research methods that combined qualitative and quantitative approaches were conducted. Qualitative research was first conducted by in-depth interviews with 16 experts working in the fashion industry, and a questionnaire was then given to 121 fashion companies in order to fulfill the quantitative research portion of this study. The findings of this study are as follows: First, the conceptual structure of intellectual capital in a fashion company was revealed. A fashion company's intellectual capital is composed of 'human capital', 'structural capital', and 'relational capital'. Human capital has three components: a chief executive officer (CEO), members, and a human resource management capability. Structural capital has four components: organizational culture, information management capability, merchandising capability, and product innovation capability. Relational capital has three components: customer equity, marketing capability, and relationship management capability. Second, the conceptual structure of intellectual capital was confirmed via quantitative research analysis. All of the components of intellectual capital have internal consistency, convergent validity, construct validity, and discriminant validity.