• Design & Manufacturing
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• v.13 no.4
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• pp.28-33
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• 2019

In this study, the flow analysis of fermentation tank, digester and dryer, which are the main equipment in environmental energy facilities, was carried out. Numerical analysis was carried out with the size of the actual plant, and 3D modeling program CATIA V5 R16, grid generation program Gambit, and general purpose flow analysis package ANSYS-FLUENT (v13) were used. Simulation results of the carrier gas flow analysis in the STD dryer using the computational fluid dynamics program showed that the carrier gas smoothly circulated between the shells of the dryer and the flow was uniformly distributed without stagnation or flow. It is also predicted that rotational flow due to shell rotation is active. The average flow velocity of carrier gas in the STD dryer was estimated to be about 0.196m / s, and the average temperature of the carrier gas was calculated to be 424K. Due to the relatively slow carrier gas velocity and high average temperature, the water content of the sludge can be effectively lowered.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.986-996
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• 1994

Insulation system of LNG carrier has made important roles such as maintaining a proper Boil off Ratio(BOR) for the cargo and avoiding the excessive low temperature of the adjacent inner hull beyond the permissible limit. At the same time, safety and economy of the LNG transportation by the ship are connected with the performance of the insulation system. Also, thermal insulation system of LNG carrier is one of the most advanced technique with the structure analysis of tank, welding and assembling. In this study a computer program is developed to calculate the hull temperature distribution and BOR, which are important factors in thermal design for the Moss Rosenberg Verft spherical tank type LNG carrier. Detailed results for hhull temperature distribution close to LNG tank, BOR and the thickness effect of insulation material are reported in this paper in the range of standare design sea condition.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.7
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• pp.23-29
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• 1997

The performance degradation of CMOS differential amplifiers due to hot carrier effect has been measured and analyzed. Two-state CMOS amplifiers whose input transistors are PMOSFETs were designed and fabriacted using the ISRC CMOS 1.5.mu.m process. It was observed after the amplifier was hot-carrier stressed that the small-signal voltage gain and the input offset voltage increased and the phase margin decreased. The performance variation results from the increase of the transconductances and gate capacitances of the PMOSFETs used as input transistors in the differential input stage and the output stage and also resulted from the decrease of their output conductances. After long-term stress, the amplifier became unstable. The reason might be that its phase margin was reduced due to hot carrier effect.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.1-10
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• 1993

This paper introduces the outline of hull structure to the sorts of LNG carrier briefly. Especially, explains in detail for the insulation system of Moss Rosenberg Verft spherical tank type LNG carrier. It is not easy task to calculate exactly the temperature distribution of hull because of very complicated structure of hull. Therefore, in this paper by the adequate modeling of the Moss Rosengerg spherical tank type LNG carrier, a program is developed which calculate the temperature distribution of every hull and estimate the heat influx from every hull and output the BOR according to the variation of atmospheric conditions on boyage.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.3
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• pp.33-49
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• 2014

The object of this study is to verify the effects of job stress on burnout and job satisfaction of flight attendants and to confirm the difference in the effect on the consciousness of full service carrier and low cost carriers' flight attendants. In order to confirm, the study examines the relationship between job stress, burnout, and job satisfaction of airline cabin attendant. A survey was done for 55days from January 5th 2014 on flight attendants and total 200 valid samples were analysed. The results of the study demonstrated significant relationship and difference in job stress, burnout and job satisfaction of flight attendants between full service carrier and low cost carrier. As a result, the study is significant as it satisfaction between divergent airline work environment.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.489-500
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• 2014

This paper presents a simple modified unipolar carrier-based pulsewidth modulation (CB-PWM) strategy for the three-level neutral-point-clamped (NPC) voltage source inverter (VSI). Analytical expressions for the relationship between modulation reference signals and output voltages are derived. The proposed modulation technique for the three-level NPC VSI includes the maximum and minimum of the three-phase sinusoidal reference voltages with zero-sequence voltage injection concept. The proposed modified CB-PWM strategy incorporates a novel method that requires only of one triangular carrier wave for generate the gating pulses in three-level NPC VSI. It has the advantages of being simplifying the algorithm with no need of complex two/multi-carrier pulsewidth modulation or space vector modulation (SVM) and it's also simple to implement. The possibility of the proposed CB-PWM technique has been verified though computer simulation and experimental results.

• The KSFM Journal of Fluid Machinery
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• v.4 no.4 s.13
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• pp.43-52
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• 2001

Pumps arre used extensively for transporting fluid in many ships. However, the present state of pumps used in the large merchant ships has not been studied. In this paper, we have reported the general description of the operating pumps according to the different ship types(Bulk, Container, Car-Carrier, Tanker, LNG). Moreover, the pump total powers are compared with the main engine Normal Continuous Rating power and the pump total weights are also compared with the ship deadweight.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.114.1-114
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• 2001

GPS Receiver gives pseudorange Doppler and integrated carrier phase for measurements to compute navigation information. Thought the integrated carrier phase can be transfer to the equal domain as pseudorange by multiplying the wave length of the received signal, in order to get position information from the carrier phase measurements the integer ambiguity should be resolved. And differencing technique is generally used to eliminate the common error terms of the integrated carrier phase measurements between robber and server. In short baseline double-differencing operation has effect on elimination the common biases for both stations and thus ambiguity resolution are to be reliable. But the baseline increases, the integer ambiguity resolution is hardly, due to the correlated common error is increase ...

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.742-745
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• 2005

This paper describes a simple pseudo-random carrier modulation technique for the acoustic noise reduction of the three phase multi-level inverter based motor drives. The proposed method generates a new pseudo-random carrier by randomly synthesizing a carrier with fixed frequency and a carrier with opposition phase. To confirm the validity of the proposed method, a 130v three-phase multi-level inverter was Implemented and tested. The experimental results show that the output line voltage and acoustic noise harmonics spectra of an inverter have broadening effect of harmonics, as only simple synthesis of fixed frequency carries.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.2
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• pp.19-21
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• 1978

The electrical drift mobility of charge carrier of Cholesteryl Benzoate was measured by Polarity inversion method in the temperature range 140~ 185$^{\circ}C$. with a view to revealing the mechanism of charge carrier transport. The electrical drift mobility of charge carrier of that increased from 2.5$\times$10-7$\textrm{cm}^2$/V.sec to 2.0$\times$10-6$\textrm{cm}^2$/v.sec as the temperature increased. As a result of the experiment, the mechanism of current transport is believed to be ionic mechanism.