• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.455-460
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• 2008

The flammable gas monitoring system is to be provided in cargo pump rooms of tankers in accordance with the requirements of SOLAS regulations, and flammable gas detectors are to be arranged in a proper position. In this paper, simulation tests and CFD analysis are carried out under the actual ventilation conditions of pump rooms in the ship in service. Based on the results, a new guidelines for an arrangement of flammable gas detectors are suggested.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.1
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• pp.40-49
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• 2002

Floating fixed scroll adopted for tip sealing enhancement in a scroll compressor is always under the influence of tipping moment produced by internal gas forces. Unless the tipping moment is property compensated by some restoring moment, the fired scroll would suffer tipping movement, degrading the compressor performance. The condition on which the tipping movement of the fixed scroll can be suppressed has been investigated analytically. For no tipping movement, the floating fixed scroll should be suspended on the main frame at proper level. The upper limit of the stable suspension is the axial location of the o-rings adopted for a back pressure chamber sealing on the rear side of the fixed scroll, and the lower limit is the mid-height of the scroll wrap.

• Journal of the Korean Data and Information Science Society
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• v.16 no.4
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• pp.943-949
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• 2005

An economic design of specification limits for production process of ham is considered for a given process mean in a complete inspection plan. Each ham is inspected, and if it meets the specification, it is accepted. The ham less than the lower specification limit are changed another products or at a discounted price, and those greater than the upper specification limit are reworked. A profit model is developed which involves selling price, production cost, rework cost and the cost which is incurred by imperfect quality. Methods for finding the optimal specification limits are derived for the case of piecewise linear loss function with an industrial case study.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.654-658
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• 2003

In this study a control system with variable gain schedule using real speed and moving direction is proposed to control a Permanent Magnet Linear Synchronous Motor (PMLSM) with Z-axis operation structure. The implementation of the controller is designed on the DSP TMS320C32 board. PMLSM is operated by using 4-point absolute positions profile with each velocity, acceleration and deceleration. The direction of the initial angle action for starting is set from the lower limit point to the upper limit point on PMLSM operation stroke. The effectiveness of a control system with variable gain schedule is demonstrated by some experimental results.

• Fire Science and Engineering
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• v.24 no.3
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• pp.66-71
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• 2010

In order to evaluate the fire and explosion involved and to ensure the safe and optimized operation of chemical processes, it is necessary to know combustion properties. Explosion limit is one of the major combustion properties used to determine the fire and explosion hazards of the flammable substances. In this study, the lower explosion and upper explosion limits of esters were predicted by using the heat of combustion. The values calculated by the proposed equations agreed with literature data within a few percent. From the given results, using the proposed methodology, it is possible to predict the explosion limits of the other ester flammable substances.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1444-1451
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• 2001

The evolutionary structural optimization(ESO) method has been under continuous development since 1992. The bidirectional evolutionary structural optimization(BESO) method is made of additive and removal procedure. The BESO method is very useful to search the global optimum and to reduce the computational time. This paper presents the ranked bidirectional evolutionary structural optimization(R-BESO) method which adds elements based on a rank, and the performance indicator which can estimate a fully stressed model. The R-BESO method can obtain the optimum design using less iteration number than iteration number of the BESO.

• Membrane and Water Treatment
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• v.11 no.5
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• pp.345-351
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• 2020

Eutrophication of surface waters is commonly caused by excessive inputs of nutrients such as nitrogen and phosphorus. Nakdong River basin was chosen as the study area to investigate the effect of point and non-point source pollution of nitrogen on eutrophication in water body. Non-point source inputs of nitrogen accounted for approximately 84% in the total nitrogen input of the upper Nakdong river watershed, which mainly consists of agricultural land and forests. However, point source inputs of nitrogen accounted for 58~85% in the total nitrogen input of the middle and lower watersheds, including urban area. Therefore, for watershed near urban area, control of point source inputs of nitrogen may be an optimal method to control eutrophication. In this respect, the enforcing reduction of nitrogen in the final effluent of wastewater treatment facilities is needed. On the other hand, to enact more stringent nitrogen regulations, the LOT (limit of technology) and environmental impact should be considered. In this study nitrogen data were analyzed to propose new nitrogen regulations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.319-328
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• 1998

In this paper, the design of ALT(Accelerated Life Test) requires a sampling plan based on failure-censored(Type II censored) ALT with lognormal life distribution. Specially the environmental effect of products has been emphasized, so we considered the upper life limit as well as lower life limit in the ALT sampling plan. The optimal plan with a high stress and a low stress is used as test plan, and the total sample size for test and lot acceptability constant which minimize an asymptotic variance of maximum likelihood estimator of assumed model parameters and satisfy the given producer's risk and customer's risk are drawn out. These values can be acquired by means of the computer program that we coded for resolving the difficulty and complexity of calculation.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.39.1-39.1
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• 2011

Coronal mass ejection (CME) plasmas have been observed in EUV and X-ray passbands as well as in white light. Mass of CME has been determined using polarized brightness observed by the Large Angle and Spectrometric Coronagraph Experiment (LASCO) on board Solar and Heliospheric Observatory (SOHO). Therefore, this mass obtained from the LASCO observation indicates the total CME mass. However, the mass of CME plasma in different temperatures can be determined in EUV and X-ray passbands using observations by SOHO/EIT, STEREO/EUVI, and Hinode/XRT. Prominence/CME plasmas have been observed as absorption or emission features in EUV and X-ray passbands. The absorption features provide a lower limit to cold mass. In addition, the emission features provide an upper limit to the mass of plasmas in temperature ranges of EUV and X-ray. We determine the mass constraints using the emission measure obtained by assuming the prominence/CME structures. This work will address the mass constraints of hot and cold plasmas in CMEs, comparing to total CME mass.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.159-165
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• 2008

The purpose of this paper is to study the impact of concentrated nonlinearities, freeplays, on the aeroelastic behaviors of single- and double-folded control fins. The nonlinearities may cause limit cycle oscillation(LCO) below the linear flutter boundary. The effects of nonlinear hinges on LCO characteristics of the fins are examined as flight condition changes. Nonlinear time-domain flutter analyses are performed, using ZAERO. The results show that the aeroelastic stability boundaries of double-folded fin(DF) are higher than those of the single-folded fin(SF) and the lower hinge freeplay impact more critically on the stability than the upper hinge freeplay of the DF.