• 전기의세계
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• v.19 no.4
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• pp.1-11
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• 1970

It is well known that solid-state devices like inverter and converter made by transistor and other semi-conductors are widely used for the purpose of motor speed control in industrial fields. This paper is devoted primarily to a study of Trial Manufacturing of Solid-state Frequency Converter by means of single-phase bridge-type SCR inverter. The principle of the trial product belongs to AC-DC-AC conversion system. The voltage to be impressed to the motor in case of speed control by frequency conversion method is necessary to be proportional to frequency. It also requires the frequency and voltage are independent to hte load variation. In order to meet above requests required to motor speed control., the trial product introduced the open loop system in the frequency setting and closed loop system in the voltage setting. The trial product showed the favorable performance characteristics in speed control of singlephase fractional horsepower motor from 45HZ through 80HZ.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.117-127
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• 2019

Vessel's ice speed performances will be verified in ice sea trial but environmental conditions of ice fields are changeable according to the weather condition of ice trial area. Speed performance has to correct in the no wind, wave and current etc. after sea trial. Especially finding ice fields which is exact the same as owner's ice thickness and strength requirements is not easy. Therefore speed correction according to environment condition has to be done after sea trial measurements. Correction methods for ice thickness, ice strength, wave, wind and ship draft, trim, ice drift etc. are checked in ice sea trial based on literature review such as ISO standard, ITTC recommendation, journal papers and proceedings of conferences. Possibility of application for current and ice drift correction in ice field are discussed and measuring schemes and procedures of correction methods are described in this paper. All of correction schemes are calculated for 'Araon' which is ice breaking research vessel with Arctic and Antarctic ice field test results. Analyzed results shows that Araon is satisfied with her official ice speed performance of 3 knots with 10MW power at 1m ice thickness, 570kPa ice flexural strength.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.474-481
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• 2019

The speed trial of a ship is one of the important elements guaranteeing its performance under the contract between the ship owner and shipbuilding company. A speed trial at sea, where the tidal current and waves are suppressed to the maximum, can prevent measurement errors due to external force conditions. On the other hand, it is difficult to maintain a calm sea state in most sea areas determined by the influence of the tidal current, wave, wind, etc. Therefore, this study evaluated a method of simulating a tidal current, which is one of the external force conditions, at the speed test operation of a ship, and applied the simulation result to the plan of a speed trial.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.478-483
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• 2012

The speed performances of ice sea trial on the Arctic(2010 & 2011) area were shown different results depend on the ice floe size. Penetration phenomena of level ice was not happened on medium ice floe and tore up by the impact force because the mass of medium ice floe is similar to the mass of Araon which is Korean ice breaking research vessel and did not shut up by the ice ridge or iceberg. The sea trial on the Amundsen sea was performed at the big floe which is classified by WMO(World Meteorological Organization). Three measurements of ice properties and five results of speed trial were obtained with different ice thicknesses and engine powers. To evaluate speed of level ice trial and model test results at the same ice thickness and engine power, the correction method of HSVA(Hamburg Ship Model Basin) was used. The thickness, snow effect, flexural strength and friction coefficient were corrected to compare the speed of sea trial. The analyzed speed at 1.03m thickness of big floe was 5.85 knots at 10MW power and it's 6.10 knots at 1.0m ice thickness and the same power. It's bigger than the results of level ice because big floe was also slightly tore up by the impact force of vessel based on the observation of recorded video.

• 한국기계연구소 소보
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• s.9
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• pp.183-191
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• 1982

This report describes the analysis method of the full-scale propulsive performance by using the data of model test and the full-scale speed trial. The model test data were analyzed by the computer program "PPTT" based on "1978 ITTC Performance Prediction Method for Single Screw Ships." Also the full-scale speed trial data were analyzed by the computer program "SSTT" based on the newly proposed “SRS-KIMM Standard Method of Speed Trial Analysis." An analysis of model and full-scale test data was carried out for a 60.000 DWT Bulk Carrier and the correlation between model and full-scale ship was stuied.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.242-250
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• 2019

The speed and power performance of a ship is not only a guarantee issue between the ship owner and the ship-yard, but also is related with the Energy Efficiency Design Index (EEDI) regulation. Recently, International Organization for Standardization (ISO) published the procedure of the measurement and assessment for ship speed and power at sea trial. The results of speed and power performance measured in actual sea condition must inevitably include various uncertainty factors. In this study, the influence for systematic error of shaft power measurement system was examined using the Monte Carlo simulation. It is found that the expanded uncertainty of speed and power performance is approximately ${\pm}1.2%$ at the 95% confidence level(k=2) and most of the uncertainty factor is attributed to shaft torque measurement system.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.366-374
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• 2021

This paper presents the analysis of the speed-power performance in the real sea using a large container vessel data provided as a test bed from a shipping company. To perform a speed trial of the vessel during a commercial voyage, the on-board measuring device and various operation data acquisition systems were mounted on the vessel for long-term performance monitoring and the voyage operated under the container loading condition close to the design draft was adopted. The content of this paper consists of Part I and Part II. Part I, such as this paper, contains the speed trial method and analysis results of the operating vessel. Part II contains the analysis of the speed-power characteristics change over time and before and after hull cleaning using operation data measured from the voyage operated under a condition similar to the speed trial.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.73-74
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• 2005

Shipping company and operators have to manage well to keep shipping schedules without problems in main engine. Specially operators have to operate main engine within the limit of operation point, and adjust related parameters to be operated safely and continuously. Also operators have ability to analyze fouling condition of hull through comparing data gotten from P-V curve and performance results of new building ships in trial with service ships. In this study, not only compared main engine performance results in shop trial and sea trial, but also investigated performance trend in accordance with the time elapsed for the service ship's diesel engine. They were confirmed as follows. First, shop trial load is higher than sea trial load but ship's speed is satisfied with owner's contract speed. Second as time goes by, load of service ship increases steadily and other parameters related with main engine shows variable change depend on main engine load increasing.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.124-129
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• 2001

Recently, life cycle and lead-time of products have been shortened with the demand of customers. Therefore, it is important to reduce time and cost at the step of manufacturing trial molds. High speed machining can be applied for this kind of purpose with a lot of practical advantages. In our research, several fundamental experiments are carried out to obtain machining parameters such as cutting force, machining time and surface characteristics for tool paths that are appropriate to high-speed machining. Moreover, a trial mold for an automatic transmission knob is fabricated with aluminum-7075 material. Using automatic set-up equipments, an ABS rapid prototype of a trial product of an AT knob is also manufactured with a filling process.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1724-1726
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• 2003

Korean High-Speed Train (350km/h), composed of 2 power cars, 2 motorized car and 3 trailer cars, has been developed and is under trial test. To verify the design requirements for the functions and traction performances of the train, KRRI (Korea Railroad Research Institute) decided to evaluate traction performances of the train during trial test. For this purpose, torque, velocity, voltage and current must be measured. KRRI has developed a measurement system that can measure vast and various signals effectively. In this paper, we introduce traction performances of Korean High-Speed Train. The traction measurement items are focused on the verification of motor block performances. Motor block consists of 2 motors. By this test, we verified traction performances of Korean High-Speed Train.