• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.98-104
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• 1999

As the accuracy of manufactured goods needed high accuracy processing has made the efficiency of NC and measurement technology development, the innovation of machine tools has influence the development of the semi-conductor and optical technology. The movement errors can be expressed in terms of yaw, roll an pitch etc. In the case of expanding the error range, static, dynamic and servo gain errors can be included. Machining center might have twenty-one movement errs including three types of joint errors. Those errors have been measured on the condition of just loading of standard table. Regarding these measuring methods, the mechanical compliance of the structure has not been considered. In this paper, therefor, the influences of the additional load on the positioning accuracy are investigated. The results and the techniques proposed in this study can be considered very effective and useful to compensate more correctly the positioning motion.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.8
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• pp.419-428
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• 2017

In this study, energy loss due to ventilation load in the dock system was analyzed through simulation. Also, flow generated in the dock system of the warehouse was measured using manufactured measuring devices. Numerical simulation was conducted by simulating the most common picking tasks by examining the actual working environment. Incompressible and unsteady turbulent flows were assumed, and the turbulence model was the k-e standard model. Proper grid was selected through grid dependency test. Measurement was conducted using Honeywell and Vaisala sensors, and flow and temperature inside the warehouse were measured and compared with simulation results to validate simulation. When comparing amount of loss occurring in two hours and amount of loss occurring in 15 minutes, docking time of the former was eight times longer but energy loss was 3.8 times lower. Ventilation load occurring during the initial period after opening docking system accounted for a large proportion of total ventilation load. Also, comparing the load when the dock was closed and the load when the truck was parked, ventilation load was significantly higher than load due to heat conduction from the wall. Therefore, in improving the docking system, it is effective to reduce the gap by improving compatibility of the docking system and truck, rather than wall material.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.155-165
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• 2023

Hurricane Katrina swept New Orleans, Louisiana, USA, in 2005, causing more than 1,000 fatalities and severe damage to the flood protection system. Recovery activities are complete, however, clarifying failure mechanisms and devising resilient and cost-effective retrofitting techniques for the flood protection system are still of utmost importance to enhance the general structural integrity of water retaining structures. This study presents extensive centrifuge test results to find various failure mechanisms and effective retrofitting techniques for a levee system. The result confirmed the rotational failure and translational failure mechanisms for the London Ave. Canal levee and 17^th St. Canal levee, respectively. In addition, it found that the floodwalls with fresh waterstop in their joints perform better than those with old/weathered waterstop by decreasing pore water pressure build-up in the levee. Structural caps placed on the top of the joints between I-walls could also prevent local failure by spreading the load to surrounding walls. At the same time, the self-sealing bentonite-sand mixture installed along the riverside of floodwalls could mitigate the failure of floodwalls by blocking the infiltration of seepage water into the gap formed between levee soils and floodwalls.

• Journal of Korean Society of Forest Science
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• v.106 no.3
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• pp.300-309
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• 2017

The productivity, cost, and optimal forest road network density for tree-length yarding with K301-4 and HAM300 tower yarders were analyzed. The results showed that productivity decreased as the yarding distance increased. The productivity of the K301-4 was greater than that of the HAM300 as the maximum yarding distance was longer than 34 m. This difference increased as the load volume increased. As the K301-4 yarder had a higher purchase price and it took more time to set up compared to the HAM300, the HAM300 was cost effective. Therefore, in oder to introduce tower yarders to reduce operational cost, it is effective to increase the load volume during operations and to utilize the road network repeatedly for a long period.

• Journal of Environmental Science International
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• v.19 no.7
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• pp.907-915
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• 2010

Agriculture nonpoint pollution source is a significant contributor to water quality degradation. To establish effective water quality control policy, environpolitics establishment person must be able to estimate nonpoint source loads to lakes and streams. To meet this need for orchard area, we investigated a real rainfall runoff phenomena about it. We developed nonpoint source runoff estimation models for vineyard area that has lots of fertilizer, compost specially between agricultural areas. Data used in nonpoint source estimation model gained from real measuring runoff loads and it surveyed for two years(2008-2009 year) about vineyard. Nonpoint source runoff loads estimation models were composed of using independent variables(rainfall, storm duration time(SDT), antecedent dry weather period(ADWP), total runoff depth(TRD), average storm intensity(ASI), average runoff intensity(ARI)). Rainfall, total runoff depth and average runoff intensity among six independent variables were specially high related to nonpoint source runoff loads such as BOD, COD, TN, TP, TOC and SS. The best regression model to predict nonpoint source runoff load was Model 6 and regression factor of all water quality items except for was $R^2=0.85$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.415-420
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated king roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• Advances in nano research
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• v.13 no.4
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• pp.369-378
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• 2022

Dynamic study of concrete plates under impact load is presented in this article. The main objective of this work is presenting a mathematical model for the concrete plates under the impact load. The concrete plate is reinforced by carbon nanoparticles which the effective material proprieties are obtained by mixture's rule. Impacts are assumed to occur normally over the top layer of the plate and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The structure is assumed viscoelastic based on Kelvin-Voigt model. Based on the classical plate theory (CPT), energy method and Hamilton's principle, the motion equations are derived. Applying DQM, the dynamic deflection and contact force of the structure are calculated numerically so that the effects of mass, velocity and height of the impactor, volume percent of nanoparticles, structural damping and geometrical parameters of structure are shown on the dynamic deflection and contact force. Results show that considering structural damping leads to lower dynamic deflection and contact force. In addition, increasing the volume percent of nanoparticles yields to decreases in the deflection.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.6 no.1
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• pp.30-37
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• 2003

This paper describes vibration control of a suspended system using wave absorption method. A moving multiple-pendulum system and a moving wire-and-load system are treated. The wire-and-load system is extended to a model crane system that has a motor system to roll up and down the suspended mass like a real crane. The same program with different parameter values controls these three systems. Both numerical simulation and experiment have been conducted, and the present control method has shown to be quite effective.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.96-104
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• 2006

This study is to find out how the sawdust-mixed RC beam with holes acts compared to two case of normal one with sawdust without hole, without sawdust. variables are ED3H1, ED3H2, ED3H1UB, ED3H2L, ED5H1, ED5H1UB, ED5H2, ED5H2L, Normal with sawdust PLA without sawdust. All sand, aggregate, cement are in accordance with KS. mixing design is also in accordance with KS and done at D remicon company in order to decrease any error in mixing manually. ED3H1 showed 7tone of maximum load capacity having only minor tensile deformation around hole, compared to the center of the beam. ED5H2L showed almost same shape of tensile strain between hole area and center of two beam length, while having 9.5 tone load capacity, incase of two holes being in the longitudinal axis. But ED5H2 in case of two holes being in same forcing direction showed 8.4tone of load capacity while having minor tensile chape around hole and normal tensile shape in the center of beam length. Two diameter 3cm hole in longitudinal axis give more effective behavior than the other case, practically. Capacity decrease between 5cm and 3cm in eccentric position form the longitudinal axis is less than percents. There is minor capacity difference between hole diameter 3cm hole, but 13tone difference of load capacity between hole diameter 5cm.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.865-868
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• 2003

ESP는 Effective System Performance의 약자로 NERSC에서 개발한 HPC 시스템에 대한 새로운 성능 측정 기준이다. 기존 HPC 시스템에서는 주로 성능 측정의 대상으로 시스템[프로세서]의 계산 성능에 주안점을 두었지만 시스템의 효율성은 무시되는 경향이 있었다. ESP는 실제 운영환경에서 배치 작업 스케줄러 및 병렬 작업 환경에 영향을 받는 시스템 효율성(ESP:Effective System Performance)을 측정하는 데 주안점을 두고 있다. KISTI 슈퍼컴퓨팅센터는 2003년 7월 국내 최고 성능의 슈퍼컴퓨터인 IBM p690+ 시스템의 도입을 완료하고 ESP를 사용하여 배치 작업 스케줄러인 LoadLeveler의 스케줄링 알고리즘에 따른 시스템 효율성 벤치마크를 수행하였다. 이 벤치마크를 통해서 효율적인 시스템 자원 활용을 위한 작업 스케줄링 알고리즘의 적용 근거를 마련하게 되었다.