• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.362-365
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• 1994

This paper deals with the disturbance attenuation problem for linear systems with real parametric uncertainties. When there are time invariant parameter uncertainties whose sizes are bounded, a less conservative output feedback controller is constructed such that the closed loop system is asymptotically stable and achieves the prescribed disturbance attenuation level for all allowable parameter uncertainties. In order to demonstrate efficacy of the design method a numerical example is presented.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.789-796
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• 2003

A reliability analysis is performed to investigate the influence of the uncertainty from the limited in-situ samples and the inherent heterogeneity of the ground on the probability of piping for the marine embankment near shore. The result are compared with those of the deterministic piping stability analysis performed using the fininte element flow analysis. The random variables used are hydraulic conductivity of the ground subsurface and embankment, and the water level of both internal and external side of the embankment. The probability of piping is most sensitive to the mean and standard deviation of internal water level of the embankment among the random variables included in the reliability analysis. It is found that the lower limits of internal water level which satisfies the allowable proability of piping failure for the embankment studied were E.L(-) 1.83m and E.L(-) 1.48m during and after the construction of the embankment, respectively.

• 전기학회논문지
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• 제58권7호
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• pp.1263-1269
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• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• 터널과지하공간
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• 제7권3호
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• pp.208-220
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• 1997

To asses the stability of structure around shaft during the excavation of -300 ml hopper room at 2nd shaft in Jangsung mine, some measurements were made with blast monitoring, stressmeter, extensometer and inclinometers. Instrumentations proved to be reliable and data were montiored over six month period. Stressmeters were set at the points of wall and arch of inset gang(level). Induced stresses were measured with the magnitude of 2.81 kgf/$\textrm{cm}^2$(tensile stress) and -4.45kgf/$\textrm{cm}^2$(compressive stress) respectively. These values were converged after two months. The magnitude of axial force in rock bolt was measured with 1.98 ton between the points of M2(2.25m) and M3(1.5 m) but this value was assumed within allowable level. Maximum displacement was also measured with 2 mm at the dephs of 12m from surface. But this value belongs within guide level.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.411-418
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• 2004

Using a level set method we develop a shape optimization method applied to energy flow problems in steady state. The boundaries are implicitly represented by the level set function obtainable from the 'Hamilton-Jacobi type' equation with the 'Up-wind scheme.' The developed method defines a Lagrangian function for the constrained optimization. It minimizes a generalized compliance, satisfying the constraint of allowable volume through the variations of implicit boundary. During the optimization, the boundary velocity to integrate the Hamilton-Jacobi equation is obtained from the optimality condition for the Lagrangian function. Compared with the established topology optimization method, the developed one has no numerical instability such as checkerboard problems and easy representation of topological shape variations.

• 한국정밀공학회지
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• 제30권9호
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• pp.983-990
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• 2013

Evaluation of the structural analysis for a 70/15 ton${\times}$105 m LLC (Level Luffing Crane) was conducted with an FEM Tool. Due to a discordance of the modeling and element type, the LLC was progressively analyzed after dividing it into the boom, main structure and rocker. All loads such as slewing, traveling and wind load, etc., that are indicated in the reference standards, were inputted as various severe conditions of the LLC. The deformation, equivalent stress(Von Mises stress), buckling characteristics were evaluated for the LLC structures. The stress concentrated areas over the allowable stress were identified, and reinforcement work was performed with a stiffener.

• 화약ㆍ발파
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• 제18권1호
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• pp.59-70
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• 2000

The blasting work to construct a subway in seoul, korea have often cased increased neighbor＇s complaints because of ground vibration. In order to prevent the demage to the stucture it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weigh per delay with an allowable vibration level. The effect of blasting pattem, rock strength and different explosive on the blast-induced ground vibration was studied to determine the maximum charage weight per delay within a given vibration level. The blasting vibration equation from over 100 test data was obtained, V= K(D/W(equation omitted), where the values for n and K are estimated to be 1.7 to 1.5 and 48 to 138 respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.790-795
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• 2004

The characteristics of refrigerator noise recorded in anechoic chamber was investigated in condition of a the real living room and a kitchen. To predict the noise propagation in an apartment unit, room acoustic simulation software was used. It was found that the noise level in the real living room was $4\sim8dB$ higher than in the anechoic chamber. When a noise barrier and absorption materials were used on the rear wall and floor, the noise level reduced up to $3\sim4dB$. In addition, when the subjective evaluation of auralized refrigerator noise was undertaken using headphone, it was revealed that 21dB (A) is the allowable sound pressure level of 95% satisfaction.

• 한국기계가공학회지
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• 제14권6호
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• pp.35-40
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• 2015

An IP-2 type container is used for the transport of low-level radioactive materials. An IP-2 type metal container was modeled and analyzed for the dropping conditions in normal transport conditions required by NSSC Notice 2014-50, "Regulations on the packaging and transport of radioactive materials." Structural analyses were performed by finite element method, and the acceptability was reviewed by comparing the results with technical standards and maximum allowable stresses of each material. Structural members of the container were modeled as 3D solid elements, and the possible dropping directions were considered in these analyses. Results show that maximum stresses, maximum deformed gaps in the cover, and maximum estimated thickness reduction in structural members were well below the allowable limits; thus, the structural integrity of the container was confirmed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.264-269
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• 2008

This paper presents the summary of control of abnormal vibration found in the COP motors of a nuclear power plant. All six identical units of COP pump-motor assemblies showed unstable vibration pattern of which one or two showed higher vibration enough to exceed the allowable level from the installation stage. Many trials of test, measurement, overhaul and replacement had been repeated to investigate and solve the problem but only to reach unsatisfactory settlement. Recently several times of site tests are made and followed by significant diagnostic actions in which the authors group participated. It was found that the coupled shafting system of motor and pump is in close resonance with the $1^{st}$ shaft rotating speed. Redesign of topside motor bearing clearance is made to increase bearing stiffness and hence to avoid the resonance which consequently led to reduce the troubled vibration to allowable and stable status.