• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.132-137
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• 2000

Recently, a severe noise problem was encountered during a shop test of large scale vertical motor. In order to identify the noise characteristics and propose the countermeasure, a variety of experiments such as sound excitation test and contribution analysis was earned out in addition to ordinary noise and vibration measurements. The results showed that the severe noise level was dominated by an acoustic resonance phenonmenon in the cooler housing and higher sound power of outer fan. Through proper treatments, the noise level could be acceptable.

• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.387-396
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• 2004

본 연구에서는 강교량의 강상판에서 많이 사용되는 U리브 현장이음부에 대해 시공오차로 인한 단차의 영향을 조사하기 위해 실물 대모형에 대해 응력해석을 실시하였다. 또한 실물대모형 시험체를 제작하여 3점 휨 피로실험을 실시하였으며, 주사형전자현미경(SEM) 및 비치마크를 이용하여 피로균열 발생점 및 피로균열전파방향을 조사하였다. 실물대모형 모델에 대한 응력해석 결과, U리브의 하면 우각부에 응력이 크게 나타났으며, 단차가 커질수록 응력이 현저히 증가하는 것을 확인할 수 있었다. 실물대모형 시험체에 대한 정하중 및 피로실험에서도 U리브 하면의 우각부에 응력이 크게 나타났으며, 단차가 크면 피로수명은 단축되고 단차가 적으면 피로수명은 길어졌다. 또한 파단면 조사결과, 피로균열은 모재측 루트부에서 발생하여 용접비드 표면측으로 전파되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권4호
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• pp.1100-1122
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• 2023

Scheduling user-submitted cloud tasks to the appropriate virtual machine (VM) in cloud computing is critical for cloud providers. However, as the demand for cloud resources from user tasks continues to grow, current evolutionary algorithms (EAs) cannot satisfy the optimal solution of large-scale cloud task scheduling problems. In this paper, we first construct a large- scale multi-objective cloud task problem considering the time and cost functions. Second, a multi-objective optimization algorithm based on multi-factor optimization (MFO) is proposed to solve the established problem. This algorithm solves by decomposing the large-scale optimization problem into multiple optimization subproblems. This reduces the computational burden of the algorithm. Later, the introduction of the MFO strategy provides the algorithm with a parallel evolutionary paradigm for multiple subpopulations of implicit knowledge transfer. Finally, simulation experiments and comparisons are performed on a large-scale task scheduling test set on the CloudSim platform. Experimental results show that our algorithm can obtain the best scheduling solution while maintaining good results of the objective function compared with other optimization algorithms.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1115-1122
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• 2011

Reinforced-Roadbed materials are usually composed of crushed stones. Repeated load application can induce deformation in the reinforced-roadbed layer so that it causes irregularity of track. Thus it is important to develop a prediction model of elastic modulus based on stress-strain relation under repeatitive load in order to investigate behavior of reinforced roadbed. The prediction model of elastic modulus of the material can be obtained from repeated triaxial test. However, a proper size of the sample for the test must be used. In this study, a large repeatitive triaxial test apparatus with the sample size of diameter of 30 cm and height of 60cm was adapted for performing test of the crushed stone reinforced-roadbed considering large particle size to get resilient modulus Mr. The obtained resilient modulus was compared to shear modulus obtained from mid size resonant column test. The sample size effect is somewhat large enough so that it is required to design a scale factor based on similarity law in order to use smaller samples for getting elastic modulus of the crushed stone reinforced-roadbed material. A scale factor could be obtained from this study.

• Asia pacific journal of information systems
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• 제11권2호
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• pp.79-98
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• 2001

As the average size of web sites gets larger, users tend to experience more severe problems while navigating through the sites. In order to alleviate the navigation-related problems, this paper proposes two new navigation systems based on the spatial metaphor to the navigation in the real world. Prototypes of the two system, Complete Route Navigation(CRN) and Complete Survey Navigation(CSN), were developed and applied to four versions of test bed web sites, which were then used in an experiment to test the effectiveness of the two navigation systems. Results from the experiment indicate that the two systems are indeed effective in aiding users to navigate in a large scale web site, and have more positive impacts when provided together. This paper ends with the limits of the study results and their implications to the development of large-scale web sites.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 토목섬유기술위원회 학술세미나 논문집
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• pp.45-54
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• 2001

In this study, slope stability analysis of LCRS(Leachate Collection Removel System) in waste landfill was peformed by large scale field test. Geocomat is new type of geocomposite product. Gecomat is a sort of Geocomposite product. It is composed of nonwoven geotextiles, woven geotextile, and geonet. Large scale field tests were performed on the slope of different two LCRSsections with static loading condition. One is LCRS section witch consist of GCL, HDPE and Geocomat, another is GCL, HDPE, and woven type geocomposite. The behavior of geosynthetics lined slope was monitored by incorporating instrumentation including vertical soil pressure meter, settlement plate, strain gauges, potential meter, displacement pin.. Based on the field monitoring, the Geocomat LCRS section is less sliding than the conventional geocomposite LCRS section.

• 한국지반공학회논문집
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• 제18권4호
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• pp.239-248
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• 2002

안정액(bentonite slurry)을 이용한 지하연속벽의 건설은 굴착된 trench 내에서 안정액이 침투케익과 표면케익을 포함한 불투수막을 형성함으로서 trench 의 안정성을 유지할 수가 있다. 그러므로 구조용 지하연속벽 건설이나 폐기물 매립장의 차수용 연속벽 건설시 지반조건 및 주변여건의 변화에 의하여 여러 가지 문제가 발생 될 수 있다. 본 논문은 안정액 유출과 불투수케익 형성과정을 대형실험으로 모델링하여 그 결과가 slurry trench 안정성에 미치는 영향을 평가하고, 현장조건에 적합한 설계절차를 제시하였다.

• Geomechanics and Engineering
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• 제37권4호
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• pp.359-370
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• 2024

The primary goal of this study is to evaluate the migration of fine granular materials into overlying layers under cyclic loading using a modified large-scale triaxial system as a physical model test. Samples prepared for the modified large-scale triaxial system comprised a 60 mm thick gravel layer overlying a 120 mm thick subgrade layer, which could be either tailings or railway sand. A quantitative analysis of the migration of fine granular materials was based on the mass percentage and grain size of migrated materials collected in the gravel. In addition, the cyclic characteristics, i.e., accumulated axial strain and excess pore water pressure, were evaluated. As a result, the total migration rate of the railway sand sample was found to be small. However, the total migration rate of the sample containing tailings in the subgrade layer was much higher than that of the railway sand sample. In addition, the migration analysis revealed that finer tailings particles tended to be migrated into the upper gravel layer easier than coarser tailings particles under cyclic loading. This could be involved in significant increases in excess pore water pressure at the last cycles of the physical model test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 3차
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• pp.55-60
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• 2010

Rockfill zones in CFRD consist typically of large granular materials, usually the maximum particle size up to several meters, which makes laboratory testing to determine the mechanical properties of rockfill difficult. Commonly, the design strength of the rockfills is obtained by scaling down the original rockfill materials and performing laboratory strength tests for the reduced size materials. The objective of the present study is to investigate the effect of particle size on the shear behavior and the strength for granular materials. A series of large-scale triaxial tests was conducted on large granular materials with the maximum particle size varying from 20 to 50mm. The test results showed that overall shear behaviors were similar between the samples with different particle sizes while there were slight differences in the magnitudes of the peak shear stress between the samples. In addition, a simulation of the granular material with the max. particle size of 20mm was performed using DEM code, $PFC^{2D}$, and compared with the test results. The deviatoric stress versus strain behaviors of experimental and numerical tests were found to be matched well up to the peak stress state.

• 전기학회논문지
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• 제60권5호
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• pp.971-976
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• 2011

This paper proposes a test system for a valve and poles building blocks used for large scale inverters such as STATCOM, SSSC, UPFC and VSC HVDC. Power semiconductors in the valve are normally connected in series to withstand switching voltage much larger than the voltage rating of a single power semiconductor. Therefore, there is a need to verify if the dynamic voltage sharing during switching in a valve is satisfactory. In this paper, we propose a test system that provides the necessary test condition: voltage and current in the valve using resonant circuits. A test scheme for a single phase inverter consisting two poles is also proposed. The performance of the inverter pole has to be verified at the factory test, before the system is installed at the site to secure the reliability of the system. The proposed scheme makes it possible to confirm if the pole can withstand voltage and current switching condition and handle loss.