• Title/Summary/Keyword: 구주

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KOEMA 소식

  • Korea Electrical Manufacturers Association
    • NEWSLETTER 전기공업
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    • no.96-9 s.154
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    • pp.6-7
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    • 1996
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A Study on the Modal Parameters for Cable System of Bridge (교량 케이블시스템의 모드변수에 관한 연구)

  • Lee, Hyunchol;Jo, Yeong-hoon;Kim, Jinsoo;Park, Kyoungho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.5
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    • pp.48-59
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    • 2019
  • In recent years, the type of bridge where cables such as suspension bridge and cable-stayed bridge are the main factors in the construction of long-range bridges has been soaring. The effects of cables on these structures are very large, and for structural analysis, it is necessary to study the cable and the structural changes according to the mode characteristics of the cables. In particular, cables are directly connected to camber adjustment, which conveys load effects on girders to tower, and are important components in the overall structure, and since the initial tension on the construction is compared with the tension over time, this study was conducted to help identify the condition of the bridge's aging and abnormalities. Therefore, in this study, the characteristics of the mode from the mode analysis through the impact hammer to the mass of the cable and the change in the length of the cable are analyzed.

Analysis of the Frequency for Cable of Cable-Stayed Bridges to Temperature Variation (온도변화에 따른 사장교 케이블 고유진동수 분석)

  • Lee, Hyun-Chol;Kim, Jin-Soo;Park, Kyoung-Ho;Lee, Jong-Jae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.2
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    • pp.23-34
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    • 2021
  • Cable was targeted for cable, which is a main material of cable-stayed bridges that have high frequency of use at home and abroad and many future construction plans. First of all, experiments were conducted on temperature loads that were permanently used due to changes in temperature of cables and changes in air temperature, taking into account changes in normal fat. The dynamic characteristics of cables were compared and analyzed by applying various systems to change dynamic characteristics by applying temperature change of cables. Comparing and analyzing the dynamic characteristics of cables, the acceleration, frequency and tension of cables due to temperature rise tended to decrease, the degree of influence of displacement of cables was analyzed, and the results of the mode characteristics of cables were analyzed. In particular, the correlation of cable acceleration, natural frequency, and tension due to changes in cable temperature showed that the cable tension is highly sensitive to acceleration and natural frequency.

Adaptation Test of Scotch Pine (Pinus sylvestris L.) in Korea -Thirty-six-year-old Growth Performance of Twenty-two Provenances- (구주소나무 적응성검정 시험 -22개 산지 36년생 결과-)

  • Ryu, Keun Ok;Han, Mu Seok;Kim, In Sik;Lee, Ju Hwan;Lee, Jae Cheon
    • Korean Journal of Plant Resources
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    • v.26 no.1
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    • pp.26-35
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    • 2013
  • This study was conducted to select superior provenances of Scots pine (Pinus sylvestris L.) well adapted to Korean environment for timber production. In 1976, twenty-two provenances of Scots pine were introduced from Sweden and the seeds were sown in seed beds in March. After one year, the seedlings were transplanted to nursery beds. The resulting 1-1 seedlings of 22 provenances were planted at Whaseong in 1978. Randomized complete block design with 3 replications were used for test plantation. Each provenance was planted with 20-tree row plot in each block and at a spacing of $1.8{\times}1.8m$. The growth performance of each provenance was monitored up to 33-years after planting. There were significant differences among provenances in volume growth. F3001 provenance showed the best volume growth of 33-years after planting ($0.160m^3$), which was 2.2 times greater than that of the lowest provenance W2027 ($0.072m^3$). The ranking of provenances was stabilized after 14 years. Comparing to reference tree species, Japanese red pine (Pinus densiflora), all Scots pine provenances showed poor growth performance. In other words, volume growth of Japanese red pine at age 28 and 33 were 2.1 and 3.3 times greater than that of Scots pine, respectively. Moreover, survival rate of Scots pine was lower than that of Japanese red pine. Based on these results, it was suggested that Scots pine was not suitable to Korean environments. The cause of maladaptation of Scots pine and the implications of introduction breeding were discussed.

해외속보

  • Korea Electronics Association
    • Journal of Korean Electronics
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    • v.6 no.8
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    • pp.39-40
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    • 1986
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