• Title/Summary/Keyword: G-power

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FINITE GROUPS WITH SOME SEMI-p-COVER-AVOIDING OR ss-QUASINORMAL SUBGROUPS

  • Kong, Qingjun;Guo, Xiuyun
    • Bulletin of the Korean Mathematical Society
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    • v.51 no.4
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    • pp.943-948
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    • 2014
  • Suppose that G is a finite group and H is a subgroup of G. H is said to be an ss-quasinormal subgroup of G if there is a subgroup B of G such that G = HB and H permutes with every Sylow subgroup of B; H is said to be semi-p-cover-avoiding in G if there is a chief series 1 = $G_0$ < $G_1$ < ${\cdots}$ < $G_t=G$ of G such that, for every i = 1, 2, ${\ldots}$, t, if $G_i/G_{i-1}$ is a p-chief factor, then H either covers or avoids $G_i/G_{i-1}$. We give the structure of a finite group G in which some subgroups of G with prime-power order are either semi-p-cover-avoiding or ss-quasinormal in G. Some known results are generalized.

Seismic Performance Evaluation and a Comparative Study on the Design Wind and Earthquake Loads for Power Transmission Towers (송전철탑의 내진성능평가 및 설계 풍하중과 지진하중의 비교 연구)

  • Hwang, Kyeong-min;Chun, Nak-hyun;Jang, Jung-bum;Yun, Kwan-hee;Kim, Tae-kyun
    • KEPCO Journal on Electric Power and Energy
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    • v.5 no.2
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    • pp.75-81
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    • 2019
  • In this study 24 power transmission towers were selected by considering various variables such as power transmission capacity, height and structural type to evaluate their seismic performance using the standard design response spectrum recently announced by the government. In addition, the stresses and sectional forces generated by the current design wind loads and revised seismic ones were compared to review the effects on the design of power transmission towers when the government-required seismic standards were raised. The results of seismic performance evaluation for the target power transmission towers showed that they had seismic capacity of 0.31~0.91g, and that they met the level of the earthquake-resistant special grade, which is the 2,400-year earthquake return periods and secured seismic safety. Further, the sectional forces caused by earthquakes in the towers were 33~82.5% of the ones due to wind loads, and it was also confirmed that the design wind loads were more dominant than design earthquake ones under the elevated seismic standards.

Optimization of microwave-assisted extraction process for blue honeysuckle (Lonicera coerulea L.) using response surface methodology (반응표면분석법을 이용한 댕댕이 기능성성분의 마이크로웨이브추출조건 최적화)

  • Park, Daehee;Lee, Jae-Jun;Park, Jongjin;Park, Sanghwan;Lee, Wonyoung
    • Food Science and Preservation
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    • v.24 no.5
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    • pp.623-630
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    • 2017
  • Functional compounds including flavonoids, anthocyanins, polyphneols and antioxidants were extracted from blue honeysuckle (Lonicera caerulea L.) using highly efficient microwave-assisted extraction. And extraction process was modeled and optimized according to response surface methodology (RSM). The independent variables ($X_n$) were ethanol concentration ($X_1$: 0, 25, 50, 75, 100%), irradiation time ($X_2$: 1, 3, 5, 7, 9 min), and microwave power ($X_3$: 60, 120, 180, 240, 300 W). Dependent variables ($Y_n$) were total flavonoid contents ($Y_1$), total anthocyanin contents ($Y_2$), total polyphenol contents ($Y_3$) and antioxidant activity ($Y_4$). Four-dimensional response surface plots were generated based on the fitted second-order polynomial models to get optimal conditions. Estimated optimal conditions for 4 responses were ethanol concentration of 54-72%, irradiation time of 7.1-7.6 min, and microwave power of 243-251 W. Ridge analysis predicted the maximal responses of total flavonoid content, total anthocyanin content, total polyphenol content and antioxidant activity were 38.00 mg RE/g, 6.80 mg CGE/g, 14.90 mg GAE/g, 89.10%, respectively. Verification experiment was carried out at predicted optimal conditions and experimental values for total flavonoid content, total anthocyanin content, total polyphenol content and antioxidant activity were 38.10 mg RE/g, 6.72 mg CGE/g, 14.91 mg GAE/g and 89.13%, respectively. No significant difference was observed between predicted and experimental values, indicating good fitness of fitted model and successful application of RSM.

A Study of Light Weight of Tie Rod End in Auto Supplies (자동차 타이로드 엔드 부품의 경량화에 관한 연구)

  • Kim, Y.S.;Kim, I.K.;Tark, J.H.;Kim, D.S.
    • Journal of Power System Engineering
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    • v.3 no.3
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    • pp.70-75
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    • 1999
  • This study is for the development of tie rod end, a parts of steering system, that would be changed with plastic material. The position of weld line is founded by the analysis of Mold Flow, computer software with FEM(Finite Element Method). Then new mold is designed by consideration with the locations of weld line. PA66(G/F 35%), PA6(G/F 45%), PET(G/F 45%) and PET(G/F 55%) are tested two types loading conditions for selecting suitable material, the requirement tensile load(more 19600N). PA6(G/F 45%) showed high mechanical properties in this study. And then, tensile strength was compared between conventional metal products and the injection molded products which were reinforced with 33%, 34%, 45%. 60% of glass fiber in matrix material. In the case of, the measured two types of tensile load values are 24500N (Method-1), 21560N (Method-2) and weight is decreased by 50% of conventional one.

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Novel Zero-Voltage and Zero-Current-Switching (ZVZCS) Full Bridge PWM Converter with a Low Output Current Ripple (낮은 인덕터 맥동전류를 가지는 새로운 영전압 영전류 스위칭 풀 브릿지 DC/DC 컨버터)

  • Baek, J.W.;Cho, J.G.;Yoo, D.W.;Song, D.I.;Rim, G.H.
    • Proceedings of the KIEE Conference
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    • 1997.07f
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    • pp.2204-2206
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    • 1997
  • A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter with a low output current ripple is proposed. The proposed circuit improve the demerits of the previously presented ZVBCS-FB-PWM converters[5-8] such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. In addition, this proposed circuit reduces a output current ripple considerably. Many advantages including simple circuit topology, high efficiency, low cost and low current ripple make the new converter attractive far high power (> 1kW) applications.

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