• 동력기계공학회지
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• 제15권3호
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• pp.38-45
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• 2011

The computational flow numerical analysis was introduced to predict thc turbulent characteristics in the mixing flow structure of $45^{\circ}$ impinging round jet. This analysis has been carried out through the commercial fluent software. Realizable(RLZ) k-${\varepsilon}$ was used as a turbulent model. It can be known that mean velocities analysed through RLZ k-${\varepsilon}$ turbulent model comparatively predict well the experiments and show well the elliptic shape of mixing flow structure in the Y-Z plane, but analysed turbulent kinetic energies show somewhat differently from the experiments in certain regions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2612-2615
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• 2008

Diaphragm seals have great effects on the performance of large power-generation steam turbines. Hence, it is important to decrease the leakage flow through the diaphragm seals and understand the flow characteristics within the diaphragm seals. In this study, numerical analysis was carried-out with the seals of large one-body type diaphragms developed by a domestic company. CFX, which is a commercial CFD code, was used to analyze the performance and flow characteristics of the diaphragm seals for three difference clearance cases. The results of numerical analysis show variations in the performance and flow characteristics according to the changes of labyrinth seal clearance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.901-904
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• 2007

The power flow analysis (PFA) can be effectively used to predict structural vibration in medium-to-high frequency ranges. In this paper, vibration experiments have been performed to observe the analytical characteristics of the power flow analysis of the vibration of various coupled plates. Those plates include two plates coupled with angles of $90^{\circ}$\;and\;30^{\circ}$, respectively. In the experiment, the loss factor and the input mobility at a source point on each coupled plate have been measured. The data for the loss factors have been used as the input data to predict the vibration of the coupled plates with PFA. The frequency response functions have been measured over the surface of the coupled plates. The comparison between the experimental results and the predicted PFA results for the frequency response functions has been performed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.517-520
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• 2004

The power flow analysis(PFA) can be effectively used to predict structural vibration in medium-to-high frequency ranges. In this paper, vibration experiment has been performed to observe the analytical characteristics of the power flow analysis of the vibration of a plate. In the experiment, the loss factor of the plate and the input mobility at a source point have been measured. The data for the loss factor has been used as the input data to predict the vibration of the plate with PFA. The frequency response functions have been measured over the surface of the plate. The comparison between the experimental results and the predicted results for the frequency response functions showed that PFA can be an effective tool to predict structural vibration in medium-to-high frequency ranges.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1854-1862
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• 2001

In this paper, power flow characteristics of a hydromechanical transmission(HMT) are investigated using network analysis. The HMT used in this study consist of a hydrostatic unit(HSU), planetary gear sets, clutches and brakes providing forward 4 speeds and backward 2 speeds. Since the HMT power flows showing a closed loop and the HSU efficiency varies depending on the pressure and speed, a systematic approach is required to analyze the power transmission characteristics of the HMT. In order to analyze the closed loop power flow and the HSU power loss which changes depending on the pressure and speed, network model is constructed fur each speed range. In addition, an algorithm is proposed to calculate an accurate HSU loss corresponding to the experimental results. It is found from the network analysis that the torque and speed of each transmission element including the HSU can be obtained as well as direction of the power flow by the proposed algorithm. It is expected that the network analysis can be used in the design of relatively complicated transmission system such as HMT.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.113-115
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• 2004

This year korea power system had recorded highest peak load for 6 times and finally it made new peak load 51,264MW at July 29th 3:00 PM. The new peak load is increased 8.2% from the last year peak load 47,385MW and korea power system entered 50,000MW load era. The Korea Power Exchange (KPX) snapped power system data at the peak load time using state estimation function in the EMS. And authors converted the power system data at peak load to PSS/E power flow format. Using this PSS/E peak load power flow data, this paper explains demand analysis result shun capacitor operation, voltage distribution at the peak load. And the paper shows the simulation result of 2 contingency analysis using the snapped PSS/E peak load data.

• Corrosion Science and Technology
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• 제12권2호
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• pp.79-84
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• 2013

In general, pipelines at nuclear power plants are affected by various types of degradation mechanisms and may be ruptured after gradually thinning. FAC (Flow-Accelerated Corrosion) is typical aging mechanism affecting the secondary side piping system. In Korea nuclear power plants, CHECWORKS program have been used for management of wall thinning damages. However, sometimes, CHECWORKS program shows wrong results at the stage of NFA (Network Flow Analysis) in case of complex pipelines. This paper describes the calculation results of pressure drop in a complex pipeline and single line by using the CHECWORKS program and the analysis results are compared with those of engineering calculation results including errors between them.

• 신재생에너지
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• 제4권4호
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• pp.30-36
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• 2008

The possibility of whether the induced wind from a vehicle traveling on highway can be used in wind power generation has been verified through computational flow analysis. The bus which is presumed to accompany relatively strong and wide range of induced wind compared to passenger vehicles because of its wide frontal area has been set as the subject of research. In order to ensure the reliability of research, the flow analysis surrounding the bus on a flat road where median strip is not installed has been compared with a preceding research while the validity of grid system and interpretation method used in this research have been assured by a qualitative method. In case of the median strip type wind power generator system, because it has been verified that a strong streamwise wind speed (5 m/s) is derived from the contraction effect of flow passage between the bus and the median strip while maintaining a relatively consistent upwind wind speed (1.4 m/s) in vertical direction in the wake area after the bus passes by although the change of wind speed is intense, it was decided as having some possibility of wind power generation. In case of the traffic sign panel type wind power generator system installed at the upper top of highway, because the wind speed of 2 m/s level has been derived for a limited time only at a section equal to the length of the bus and a faint induced wind speed less than 0.5 m/s was shown at other regions, it was decided as having almost no possibility of wind power generation.

• 대한전기학회논문지
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• 제45권3호
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• pp.329-334
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• 1996

Power system is becoming more and more complex and large Existing procedural programming technique can't cope with software flexibility and maintenance problems. So, Object-Oriented Programming (OOP) is increasingly used to solve these problems. OOP in power system analysis field has been greatly developed. This paper applies OOP in power flow analysis, and presents new algorithm which uses only a Jacobian to solve mismatch equations, and introduces a new sparse matrix storage method which is different from existing method. (author). 11 refs., 12 figs., 3 tabs.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1149-1158
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• 2002

An improved hydrostatic unit(HSU) model is proposed by considering the flow loss in order to analyze the power flow characteristics of a hydromechanical transmission(HMT) and a network analysis algorithm is presented to determine the torque and speed of each element of the HMT. To calculate the torque and flow loss of a pump and a motor in HSU, an effort and flow concept is introduced, which can be used to establish a torque and speed matrix in the network analysis. It is found from the network analysis that magnitude of the HSU stroke increases to maintain the same output speed in order to compensate the flow Boss in the HSU and the efficiency of the HMT shows the lowest value in the 1st speed since the HSU has the largest flow loss in the 1st speed and the flow loss decreases as the speed ratio upshifts.