• 전기학회논문지P
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• 제54권4호
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• pp.163-170
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• 2005

This paper deals with an improved fault location algorithm with compensation ground capacitance through distributed parameter for a long parallel T/L. For the purpose of fault locating algorithm non-influenced by source impedance and fault resistance, the loop method was used in the system modeling analysis. This algorithm uses a positive and negative sequence of the fault current for high accuracy of fault locating calculation. Power system model of 160km and 300km long parallel T/L was simulated using EMTP software. To evaluate of the proposed algorithm, we used the several different cases 64 sampled data per cycle. The test results show that the proposed algorithm was minimized the error factor and speed of fault location estimation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.145-147
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• 2002

In this paper, the improved fault locating method using distributed parameter which calculating the reduced voltage and current according to the ground capacitance in long transmission line was proposed. For the purpose of the fault locating algorithm non influenced source impedance, the loop method was used in the system modeling analysis. To enhance the fault locating, zero sequence of the fault current which is variable according to ground capacitance was not used but positive and negative sequence. System model was simulated using EMTP software. To verify the accuracy of proposed method, in different cases 64 sampled data per cycle was used and 160km and 300km long transmission line has fault resistance $0{\Omega}\;and\;100{\Omega}$ respectively was compared.

• 대한조선학회논문집
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• 제60권5호
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• pp.305-319
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• 2023

This study focuses on measuring the relative wave elevation around the KSUPRAMAX-O ship and comparing it with numerical analysis results (potential and computational fluid dynamics). The relative wave elevation is a good indicator of the pressure distribution on the ship's surface, which is affected by the ship's motion, incident waves, and distributed waves. Prior to measuring the relative wave elevation, a comparative test was conducted on resistance type, capacitance type, and ultrasonic type wave probe to measure the relative wave elevation, and it was confirmed that the resistance type wave probe was suitable for measuring the relative wave elevation. A model test was performed at low speed and design speed using resistance type wave probe and compared with the results of numerical analysis result. As for the motion response, it was confirmed that the result of experiments and the result of the numerical analysis were in good agreement. The relative wave elevation showed a similar trend between the experiment and the computational fluid dynamics, but the potential analysis result showed a difference from the experiment in design speed.

• 대한전자공학회논문지TC
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• 제37권11호
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• pp.17-22
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• 2000

HBT의 하이브리드 파이 등가회로모델에 대한 새롭고 안정적인 파라메터 추출방법을 제안한다. 측정된 S-파라메터로부터 베이스 내부 저항을 정확히 계산 할 수 있는 식이 유도 되었으며 이 식은 외부 접근 인덕턴스의 값에 크게 민감하지 않다. 이를 기반으로 다른 파라메터를 위한 6 개의 해석적 표현식이 개발되었고 하이브리드 파이 등가회로 모델링을 위한 이 식들은 안정적이고 빠르며 신뢰성 있는 파라메터 추출을 가능케한다.

• 대한토목학회논문집
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• 제38권1호
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• pp.51-61
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• 2018

풍력발전기, 송전탑, 굴뚝 등과 같은 타워 구조물의 기초는 기초에서부터 하중 작용점까지의 거리가 멀고 큰 수평하중이 작용하여 매우 큰 전도모멘트에 저항해야 한다. 이러한 구조물을 경제적으로 지지하기 위해서는 암반층이라도 인발력을 받는 말뚝기초를 시공해야 한다. 따라서, 본 연구에서는 암반매입 강관말뚝에 사용되는 주면고정액의 배합비가 주면지지력에 미치는 영향을 평가하기 위하여 물/시멘트비와 잔골재의 배합비를 실험변수로 삼아 모형실험을 수행하였다. 잔골재를 배합하지 않은 시멘트풀의 경우 물/시멘트비의 변화에 관계없이 최대 주면지지력과 잔류 주면지지력은 일정한 범위에 분포하였고, 잔골재가 배합된 경우는 물/시멘트비의 증가에 따라서는 감소하였고 잔골재 배합비의 증가에 따라서는 증가하다 감소하는 경향을 나타내었다. 잔골재가 없는 경우 최대주면지지력은 물/시멘트비에 상관없이 약 540~560kPa을 나타내었고, 잔골재비가 40%인 경우 물/시멘트비에 따라 약 770~870kPa을 보여 잔골재가 없는 경우에 비하여 약 40~55% 증가되었다. 본 실험에서 찾은 최적배합은 잔골재비가 40% 정도, 물/시멘트비가 80~100% 이었다.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.1-7
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• 2011

This paper proposes an enhanced noise robust algorithm for fault location on double-circuit transmission line for the case of single line-to-ground (SLG) fault, which uses distributed parameter line model that also considers the mutual coupling effect. The proposed algorithm requires the voltages and currents from single-terminal data only and does not require adjacent circuit current data. The fault distance can be simply determined by solving a second-order polynomial equation, which is achieved directly through the analysis of the circuit. The algorithm, which employs the faulted phase network and zero-sequence network with source impedance involved, effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The proposed algorithm is tested using MATLAB/Simulink under different fault locations and shows high accuracy. The uncertainty of source impedance and the measurement errors are also included in the simulation and shows that the algorithm has high robustness.

• Clinical and Experimental Pediatrics
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• 제59권6호
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• pp.262-270
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• 2016

Purpose: Pulmonary arterial hypertension (PAH) leads to right ventricular failure (RVF) as well as an increase in pulmonary vascular resistance. Our purpose was to study the effect of sildenafil on right ventricular remodeling in a rat model of monocrotaline (MCT)-induced RVF. Methods: The rats were distributed randomly into 3 groups. The control (C) group, the monocrotaline (M) group (MCT 60 mg/kg) and the sildenafil (S) group (MCT 60 mg/kg+ sildenafil 30 mg/kg/day for 28 days). Masson Trichrome staining was used for heart tissues. Western blot analysis and immunohistochemical staining were performed. Results: The mean right ventricular pressure (RVP) was significantly lower in the S group at weeks 1, 2, and 4. The number of intra-acinar arteries and the medial wall thickness of the pulmonary arterioles significantly lessened in the S group at week 4. The collagen content also decreased in heart tissues in the S group at week 4. Protein expression levels of B-cell lymphoma-2 (Bcl-2)-associated X, caspase-3, Bcl-2, interleukin (IL)-6, matrix metalloproteinase (MMP)-2, endothelial nitric oxide synthase (eNOS), endothelin (ET)-1 and ET receptor A (ERA) in lung tissues greatly decreased in the S group at week 4 according to immunohistochemical staining. According to Western blotting, protein expression levels of troponin I, brain natriuretic peptide, caspase-3, Bcl-2, tumor necrosis factor-${\alpha}$, IL-6, MMP-2, eNOS, ET-1, and ERA in heart tissues greatly diminished in the S group at week 4. Conclusion: Sildenafil alleviated right ventricular hypertrophy and mean RVP. These data suggest that sildenafil improves right ventricular function.

• 대한기계학회논문집B
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• 제29권12호
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• pp.1291-1298
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• 2005

Since the interior shape of a pressure regulator is complex and the change of fluid resistance at each operation condition is rapid and big, the pressure regulator can become the major factor that causes big loss in pipelines. So the suitable pressure regulator modeling by each operation condition is important to obtain reliable results especially in small scale pipeline network analysis. And in order to prevent the condensation and freezing problems, it is needed to confirm both whether temperature recovery is achieved after passing by the pressure regulator's narrow neck and how much amount of low temperature area that can cause condensate accumulation is distributed by various PCV models at every inlet-outlet pressure ratio. In this research, the numerical model resembling P company pressure regulator that is used widely for high pressure range in commercial, is adopted as the base model of CFD analysis to investigate pressure regulator's flow characteristics at each pressure ratio. Additionally it is also introduced to examine pressure regulator's critical flow characteristics and possibility of condensation or freezing at each pressure ratio. Furthermore, the comparison between the results of CFD analysis and the results of analytic solution obtained by compressible fluid-dynamics theory is attempted to validate the results of CFD modeling in this study and to estimate the accuracy of theoretical approach at each pressure ratio too.

• Structural Engineering and Mechanics
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• 제75권1호
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• pp.49-57
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• 2020

This paper presents a full-scale experimental test to investigate the flexural behavior of an innovative dovetail ultra-high performance concrete (UHPC) joint designed for the 5^th Nanjing Yangtze River Bridge. The test specimen had a dimension of 3600 × 1600 × 170 mm, in accordance with the real bridge. The failure mode, crack pattern and structural response were presented. The ductility and stiffness degradation of the tested specimens were explicitly discussed. Test results indicated that different from conventional reinforced concrete slabs, well-distributed cracks with small spacing were observed for UHPC joint slabs at failure. The average nominal flexural cracking strength of the test specimens was 7.7 MPa, signifying good crack resistance of the proposed dovetail UHPC joint. It is recommended that high grade reinforcement be cooperatively used to take full advantage of the superior mechanical property of UHPC. A new ductility index, expressed by dividing the ultimate deflection by flexural cracking deflection, was introduced to evaluate the post-cracking ductility capacity. Finally, a strut-and-tie (STM) model was developed to predict the ultimate strength of the proposed UHPC joint.

• 대한금속재료학회지
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• 제46권7호
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• pp.412-419
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• 2008

Creep behavior of the squeeze infiltrated AS52 Mg matrix composites reinforced with 15 vol% of aluminum borate whiskers($Al_{18}B_4O_{33}w$) fabricated squeeze infiltration method was investigated. Microstructure of the composites was observed as uniformly distributed reinforcement in the matrix without any particular defects of casting pores etc.. Creep test was carried out at the temperature of 150 and $200^{\circ}C$ under the applied stress range of 60~120 MPa. The creep resistance of the composite was significantly improved comparing with the unreinforced AS52 Mg alloy. The creep behavior of composites might be interpreted with the substructure invariant model successfully for the composite. Threshold stress of the composite exist for the creep deformation of the composite. The analysis of the creep behavior of the composite with threshold stress indicated that creep deformation was controlled by the lattice diffusion process of AS52 Mg matrix at given effective stresses and temperatures. Activation energy was also calculated to check lattice diffusion controlled creep behavior of the composite.