• Title/Summary/Keyword: Rpm

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A Study on the Performance Characteristics of Turbocharged Engine for the Stable Control (터보차저 엔진의 안정적 제어를 위한 성능 특성에 관한 연구)

  • Chun, Dong-Joon
    • Journal of Advanced Navigation Technology
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    • v.14 no.1
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    • pp.93-101
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    • 2010
  • In this study, the performance characteristics of turbocharged engine is analyzed. The methods of engine performance improvements are suggested not only for full load characteristics of the engine but also for partial load characteristics of the engine, which is more frequently used in actual driving conditions. The compression ratio of the compressor is increased rapidly in a straight line pattern until 1260 engine rpm, and after that it is increased slowly to 2.5 ratio. Also the brake mean effective pressure increased until 1260 engine rpm and decreased rapidly after 1600 engine rpm. The higher the pressure ratio, the better the fuel consumption, air excess ratio and brake mean effective pressure. But those are higher in the rated revolution range than in the mid-low revolution range. The turbocharger is operated in a stable condition from 1260 rpm and its efficiency is low in the low speed range for the reason of its characteristics. The results of this study can be applied in the fundamental control methods of turbocharged engine for stable load and speed.

Influence of Agitation Speed on Cell Growth in the Aerobic Yeast Fermentation of Pulverized Liquid Food Wastes for Probiotic Feed Production (남은 음식물로 호기적 액상효모발효를 이용한 생균사료를 생산할 때 생균수에 대한 교반 속도의 영향)

  • Yu, Sung-Jin;Yu, Seung-Yeung;Lee, Ki-Young
    • Journal of the Korea Organic Resources Recycling Association
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    • v.9 no.4
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    • pp.99-104
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    • 2001
  • The influence of agitation speed on the yeast growth was investigated in the production of probiotic feed from pulverized liquified food wastes by aerobic fermentation. A yeast Kluyvermyces marxianus was selected through a preliminary screening. The yeast was cultured by 2liter jar fermenter. in 10% solid(w/v) substrate of liquified food waste at $35^{\circ}C$ with each different agitation speed of 500, 900 and 1200 rpm. For the acceleration of enzyme excretion mixed culture with Aspergillus oryzae was also attempted and the results were compared to those of single culture. As results the viable cell number was increased by increasing agitation speed. But it showed highest value in 900rpm and then decreased in 1200rpm. The mixed culture increased amylase activity and growth rate, but did not seem to enhance the highest viable cell count in the final fermentation stage.

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Effect of TiCl4 Concentration and Mixing Intensity on Phosphorus Removal in Synthetic Wastewater (TiCl4 농도와 교반강도가 수중 인 제거에 미치는 영향)

  • Seo, Wan-Woo;Lee, Bong-Hee;Park, Hwa-Soo;Kim, Jong-Ho;Ahn, Johng-Hwa
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.3
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    • pp.150-153
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    • 2016
  • This study evaluates the efficacy of titanium tetrachloride ($TiCl_4$) on phosphorus (P) removal in synthetic wastewater. Jar test experiments were performed at various $TiCl_4$ concentration (0.25-0.59 mM), and intensities of slow (30-60 rpm) and rapid (100-250 rpm) mixings to determine the conditions at which P removal was most efficient. The P-removal efficiency was highest (about 99%) at $TiCl_4$ concentration $([TiCl_4])=0.39mM$ with rapid-mixing intensity=100 rpm and slow-mixing intensity=30 rpm. The slow-mixing intensity was more sensitive than the rapid-mixing intensity to the P removal efficiency when [$TiCl_4$] was low ($0.25{\leq}[TiCl_4]{\leq}0.27mM$).

A Feasibility Study on the RPM and Engine Power Estimation Based on the Combination of AIS and ECMWF Database to Replace the Full-scale Measurement (실선계측 데이터 대체를 위한 AIS 및 ECMWF 데이터베이스 조합을 이용한 LNGC의 분당 회전수 및 동력 추정에 관한 타당성 연구)

  • You, Youngjun;Kim, Jaehan;Seo, Min-Guk
    • Journal of the Society of Naval Architects of Korea
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    • v.54 no.6
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    • pp.501-514
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    • 2017
  • In the previous research, a study was carried out to estimate the actual performance such as the propeller Revolution Per Minute (RPM) and engine power of a Liquefied Natural Gas Carrier (LNGC) using the full-scale measurement data. After the predicted RPM and engine power were verified by comparing those with the measured values, the suggested method was regarded to be acceptable. However, there was a limitation to apply the method on the prediction of the RPM and engine power of a ship. Since the information of route, speed, and environmental conditions required for estimating the RPM and engine power is generally regarded as the intellectual property of a shipping company, it is difficult to secure the information on a shipyard. In this paper, the RPM and engine power of the 151K LNGC was estimated using the combination of Automatic Identification System (AIS) and European Centre for Medium-Range Weather Forecasts (ECMWF) database in order to replace the full-scale measurement. The simulation approach, which was suggested in the previous research, was identically applied to the prediction of RPM and engine power. After the results based on the AIS and ECMWF database were compared with those obtained from the full-scale measurement data, the feasibility was briefly reviewed.

The Effect of Hydrogen Added into In-let Air on Industrial Diesel Engine Performance (흡기중의 수소첨가가 산업용 디젤기관의 성능에 미치는 영향)

  • Park, Kweon-Ha;Lee, Jin-A;Lee, Wha-Soon
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.8
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    • pp.1050-1056
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    • 2010
  • Diesel engines introduce only air into the cylinder, and the air is high lycompressed. Fuel is directly injected into the combustion chamber in high temperature and pressure. Therefore diesel engines have high thermal efficiency because of the high compression ratio, while having high level of particulate matter and nitrogen oxide emissions because of the direct fuel injection. Many technologies have been developed to reduce particulate matter and nitrogen oxide emissions from diesel engines. One of the technologies is hydrogen fuel introduced into the combustion chamber with diesel fuel. In this thesis tiny amount of hydrogen is supplied into the combustion chamber in order to enhance the combustion performance. The engine, in which hydrogen is introduced, is tested. There are 20 test conditions given as 5 torque values of 100%, 75%, 50%, 25%, 0%, and 4 engine speeds of 700rpm, 1000rpm, 1500rpm and 2000rpm for the two cases with or without hydrogen addition. Maximum torques and Idle torques at each engine speed are measured, then the torque values are divided into 4 levels with 25% increasing step. The result shows that the fuel consumption, smoke, CO are reduced while the NOx emission is slightly increased, and the hydrogen addition has not a great effect on the performance at low loads but a great effect at a maximum load.

Characteristics of Glutinous Rice Fractions and Improvement of Yoogwa Processing by Microparticulation/Air-classification (찹쌀의 초미세분쇄/공기분급 특성과 유과제조공정 개선)

  • Park, Dong-June;Ku, Kyung-Hyung;Mok, Chul-Kyoon
    • Korean Journal of Food Science and Technology
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    • v.27 no.6
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    • pp.1008-1012
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    • 1995
  • Glutinous rice was microparticulated and air-classified at different air classifying wheel speeds (ACWS) of 20,000 rpm and 15,000 rpm in a Turboplex classifier. The starch was concentrated to a coarse fraction and the protein was shifted to a fine fraction. The degree of starch damage of the coarse fraction was comparable to that of traditionally soaked glutinous rice. Yoogwa(Korean cracker) made from the fractions of $ACWS\;15,000{\sim}20,000\;rpm$ and below ACWS 15,000 rpm was very comparable to that made by the traditional method in degree of puffing, hardness and internal structure. It was also confirmed by the sensory evaluation, indicating that the microparticulation/air classification technology could be applied to produce raw material of Yoogwa. The developed noble process could exclude the long soaking step in the traditional Yoogwa process and reduce the pretest time remarkably.

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Analysis of Axial Capacity and Constructability of Helical Pile with Inner Cone Penetration (내부 콘 항타를 적용한 헬리컬 파일의 지지력 및 시공성 분석)

  • Lee, Jun-Ho;Lee, Kicheol;Kim, Dongwook
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.4
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    • pp.1-11
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    • 2017
  • In this study, 1/6 small-scale model tests of helical piles were conducted to evaluate their installation time and ultimate capacities. Model sand layers were constructed using sand pluviating method to produce uniform soil relative density. For installation of different helical piles varying locations (vertical center-to-center spacings of 50 mm and 150 mm) of helix plates, two different rotation speeds of 15 rpm and 30 rpm were implemented. Cone penetration equipment was installed within the hallow section of the helical pile to increase ultimate capacity of helical pile and to evaluate soil properties of plugged soils and soils below pile tip after installation of the piles. Based on the test results, the most fasted installation was possible under the condition of "rotation speed of 30 rpm and center-to-center spacing of 50 mm", and the highest ultimate capacity was mobilized under the condition of "rotation speed of 30 rpm and center-to-center spacing of 150 mm with cone penetration implementation."

Milling characteristics of cutting-type rice milling machine according to the rotating speed of the main shaft

  • Cho, Byeong-Hyo;Han, Chung-Su;Kang, Tae-Hwan;Lee, Dong-Il;Won, Jin-Ho;Lee, Hee-Sook
    • Korean Journal of Agricultural Science
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    • v.44 no.3
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    • pp.416-423
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    • 2017
  • This study aimed to identify milling characteristics depending on the rotating speed of the main shaft of the cutting-type rice milling machine which can minimize the conventional milling process. Brown rice, which was produced in Gunsan-si, Jeollabuk-do, Republic of Korea, in 2016, was used as the experimental material. The milling characteristics of white rice were measured under four different rotating speeds of main shaft: 950 - 1,050 rpm, 1,000 - 1,100 rpm, 1,050 - 1,150 rpm, and 1,100 - 1,160 rpm. For each shaft speed, 300 kg of brown rice was processed, and the milling characteristics were measured according to the whiteness, grain temperature, cracked rice ratio, broken rice ratio, turbidity, and energy consumption. The whiteness of rice grain was found to be consistent at around $40{\pm}0.5$ only when milled at the shaft speed of 950 - 1,050 or 1,000 - 1,100 rpm. The grain temperature during the milling process increased by 11.35 to $11.85^{\circ}C$, showing little differences amongst shaft speeds. The cracked rice ratio increased by 8.2 to 10.4% at all conditions. The broken rice ratio ranged from 0.58 to 0.76%, reflecting a low level. The turbidity after milling was 54.8 ppm when milled at 1,000 - 1,100 rpm. Energy consumption of 12.98 and 12.18 kWh/ton were recorded at the shaft speed of 1,000 - 1,100 and 1,050 - 1,150 rpm, respectively. The result of this study indicates that the optimal rotating speed of main shaft would be 1,000 - 1,100 rpm for a cutting-type rice milling machine.

A Study on the Optimization of Sedimentation Efficiency through Controlling Stirring Speed and Baffle Angle (교반속도 및 Baffle 각도 조절에 따른 침전지 효율 최적화 연구)

  • Kwak, Sung-Keun;Kim, Choong-Gon
    • Journal of the Korea Organic Resources Recycling Association
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    • v.28 no.4
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    • pp.69-75
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    • 2020
  • This study was conducted to improve the solid-liquid separation efficiency of clarifiers. To do so, the study did a bio-flocculation experiment simply by controlling the stirring speed (rpm) and baffle angle of a clarifier on a lab scale, but without using a coagulant. For the purpose of the experiment, the feed wall of a clarifier was so improved that a baffle could be installed on the clarifier. Then, it was ensured to change its stirring speed (to 0.0rpm, 0.6rpm, and 1.2rpm), with the angle fixed at 10°. As a result, it was found that concentration efficiency increased by 2.0%, and effluent removal efficiency (SS concentration) by 7.8%, at a stirring speed of 0.6ppm. This indicates the bio-coagulation efficiency of sludge increased with changing stirring speeds. Then, the baffle angle of the sedimentation unit was changed to analyze how the changed baffle angle would affect the sedimentation of sludge. As a result, it was found that the compression of sludge interface was very effective at a baffle angle of 20°. It is hoped that these experimental findings will be useful in improving the sedimentation efficiency of circular clarifiers.