• Title/Summary/Keyword: Effective efficiency

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A Study on the Improvement of Spectrum Utilization Efficiency by Narrowing the Channel Spacing in Domestic FM Broadcasting (국내 FM 방송에서 채널 간격의 축소에 따른 스펙트럼 이용효율의 개선에 관한 연구)

  • 최연자;장은영;조성준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.16 no.9
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    • pp.819-827
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    • 1991
  • In this study, the efficiency of spectrum utilization has compared in case of channel spacking 100 KHz and 200 KHz by application of technical specifications of domestic FM broadcasting varing with effective radiated power, terrain irregularity factor and effective height of thrnsmit antenna. The results show that if arranging by 100 KHz channel total number of available channel will increase twice and the efficiency of spectrum unilization will be better 1.36 to 2.0 times than that of 200 KHz channel spacing.

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Comparison of Reprogramming Methods for Generation of Induced-Oligodendrocyte Precursor Cells

  • Lee, Eun-Hye;Park, Chang-Hwan
    • Biomolecules & Therapeutics
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    • v.25 no.4
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    • pp.362-366
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    • 2017
  • Direct conversion by trans-differentiation is of growing interest in cell therapy for incurable diseases. The efficiency of cell reprogramming and functionality of converted cells are important considerations in cell transplantation therapy. Here, we compared two representative protocols for the generation of induced-oligodendrocyte progenitor cells (iOPCs) from mouse and rat fibroblasts. Then, we showed that induction of Nkx6.2, Olig2, and Sox10 (NOS) was more effective in mouse fibroblasts and that induction of Olig2, Sox10, and Zfp536 (OSZ) was more effective at reprogramming iOPCs from rat fibroblasts. However, OSZ-iOPCs did not show greater proliferation than NOS-induced cells. Because the efficiency of iOPCs generation appears to differ between cell species depending on transcription factors and culture conditions, it is important to select appropriate methods for efficient reprogramming.

Comparative Study on Disinfection Efficiency of Chlorine and Chloramine in the Distribution Systems (배·급수계통에서 유리염소와 클로라민의 소독효과에 관한 비교연구)

  • Choi, Yong-Il;Nam, Sang-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.13 no.2
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    • pp.82-88
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    • 1999
  • This study was to evaluate disinfection efficiency of chlorine and chloramine as secondary disinfectants in the distribution systems. Indicator organism, HPC in the suspended and attached were measured for copper, galvanized steel, PVC, and carbon steel pipes. For suspended microorganism, the PVC pipe was markedly dense among the assessed pipe materials. The attached microorganism was markedly equivalent roughness of pipe materials. In copper and galvanized pipes, chloramine was more effective that free chlorine to disinfect suspended microorganism in the contact time of 2 hours. The contact time for the 99% inactivation of suspended microorganism by chloramine was longer than that of free chlorine. Regardless of pipe materials, chloramine was effective on both disinfection efficiency and 99% inactivation time for attached microorganism. In conclusion, chloramine which is good disinfectant for long contact time was recommended as secondary disinfectant in distribution system.

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Separation of Lipases Using Reversed Micelles (역미셀을 이용한 리파아제의 분리)

  • 최평호;류희욱이태호장용근
    • KSBB Journal
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    • v.6 no.4
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    • pp.337-344
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    • 1991
  • The liquid-liquid extraction of lipase A from Candide cylindracea and lipase B from porcine pancrease was carried out using reversed micellar organic solvents. Effects of various factors such as ionic strength, pH, and species and concentration of surfactant, on lipase solubilization were studied. A cationic surfactant cetyl-trimethyl ammonium bromide (CTAB) in isooctane/nhexanol(1:1) was found to be an effective solvent and its optimum concentration was 50 mM. KCl among various salts tested was the most effective and the efficiency of solubilization of lipase increased with decreasing the ionic strength of salts. The maximum activity and solubiliz ation of protein were obtained at pH 8. The stripping efficiency has a maximum value at pH 4 and increases with KCl concentration in the range of 0.2∼1.0 M. After the solubilization and stripping, the overall recovery efficiency of mass and specific activity of lipases was 62% and 66%, respectively.

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Evaluation of Ventilation Efficiency for Various Gravity Ventilators (자연환기 벤틸레이터 형태에 따른 환기효율 평가)

  • 하현철;김태형
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.7
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    • pp.543-551
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    • 2002
  • Gravity ventilators allow the escape of the warm air and air contaminants due to both (either) buoyancy and (or) convection. As a natural ventilation strategy, various gravity ventilators can be installed on the roof. Ventilation efficiency could be affected by various parameters, such as, area of openings, wind velocity and incidence angle, temperature difference between inside and outside, and shape of ventilator. Especially, the shape of roof gravity ventilator might be one of influencing factors for the effective ventilation. The window type gravity ventilators are frequently installed instead of general (standard) gravity ventilator. However, the ventilation efficiencies of them were not proved yet. To compare the ventilation efficiency, general type ventilator and two window type ventilators were numerically tested. Mean age of air, temperature and CO concentration were predicted by using commercial CFD code, AIRPAK (Ver. 2.0) with various conditions. The predicted result showed that general type ventilator is more effective for natural ventilation than window type ventilators.

A minimum energy control of a load-sensing hydraulic servo system

  • Kim, S.D.;Cho, H.S.
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10a
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    • pp.747-752
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    • 1987
  • The dynamic characteristics of a load-sensing hydraulic servo system are complex and highly unstable. Another property of the system is that the setting value of pump compensator is closely related to energy efficiency as well as control performance of the system. This necessitates the development of an effective control algorithm which guarantees good control performance, stability and energy efficiency. This paper considers a suboptimal PID control for the velocity control problem of the load-sensing hydraulic servo system. The results of simulations studies and experiments show that the proposed suboptimal controller can produce much better control performance than nonoptimal controllers and give effective energy efficiency.

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A Study on the Evaluation of the Building Energy Efficiency in Accordance with the Shapes of the Apartment Unit Plans (아파트 단위세대 평면 형태에 따른 건물에너지효율 평가)

  • Kim, Chang Sung;Seo, Kyung Wook
    • KIEAE Journal
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    • v.13 no.4
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    • pp.55-62
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    • 2013
  • Korea Government have carried out various policies to reduce the energy consumption that cause the global warming and environmental pollution. Energy consumption of buildings in Korea has reached 24% of total energy quantities and energy consumption of apartment has been continuously increasing. It has executed the building energy efficiency rating system and energy performance assessments and certification systems have been in force to save energy consumption of buildings. Therefore, this study tried to asset the energy performance of apartment according to the shapes of unit plan, and then to evaluate the energy performance of apartment according to altering balcony area into living area in the unit plan of apartment and thus, to present the effective unit plan to reduce the energy consumption. According to the results, in case of standard unit plan, the 3Bay and 4Bay unit plans showed more effective energy consumption than the 2Bay unit plan, respectively, 5%, 6%, and in case of extended unit plan, respectively, 2%, 5%. Compared the energy efficiencies of the standard unit plan to the extended unit plan, the standard one showed more effective energy consumption than the extended one, respectively, 2% in case of the 2Bay and 4Bay unit, 5% of the 3Bay unit.

Fundamental study on combustion characteristics of methanol fuel in a constant volume chamber (정적연소기를 사용한 메탄올의 연소특성에 관한 연구)

  • 이태원;이중순;정성식;하종률
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.2
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    • pp.389-396
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    • 1994
  • It is very important to clarify the ignition and flame propagation processes of methanol fuel in the Spark-ignition engine. High speed Schlieren photography and pressure trace analyses were used to study on combustion characteristics of methanol fuel in a constant volume chamber. Methanol-air mixtures equivalence rations from lean limit to 1.4 were ignited at initial pressure (0.1, 0.3, 0.5 MPa), temperature (313 343, 373 K) and ignition energy (40, 180 mJ). As the result of this study, we verified the characteristics such as ignition delay, effective thermal efficiency, flame propagation velocity, lean limit, ignitability and combustion duration. Obatained results are as follows. (1) The time to 10% reach of maximum pressure was 40-50% of the total combustion duration for this experimental condition hardly affected by equivalence ratio. (2) The Effective thermal efficiency, as calculated from maximum pressure was the highest when the mixture was slightly lean $({\phi} 0.8-0.9)$ and maximum pressure was the highest when the mixiture was slightly rich $({\phi} 1.2-1.2).$

A Study on the Problem-Solving Method and Thermal Efficiency Properties at the Time of High Expansion Realization in a 4-Cycle Diesel Engine (4사이클 디젤기관에서 고팽창 실현 시 문제점 해결방안과 열효율 특성에 대한 연구)

  • Jang, Tae-Ik
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.6
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    • pp.835-842
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    • 2009
  • The present thesis carried out a research on a compression pressure's reduction phenomenon and its countermeasure according to the thermal efficiency improvement method by a Miller method in 4-cycle low speed diesel engine. In case of retardation of intake valve closing time in a engine, the theoretical heat efficiency shows a remarkably reducing trend when a compression ratio is not compensated. Accordingly, the thermal efficiency showed an increasing trend in case of compensating the compression ratio. Especially, it could be understood that the theoretical heat efficiency at near ABDC $100^{\circ}$ of intake valve closing time in case of compensation of the compression ratio was improved by around 25.1%, and the mean effective pressure was also increased by around 18.6%. Also, as the retardation of intake valve closing time increases, air quantity becomes insufficient due to a backflow phenomenon of intake air and thus thermal efficiency was decreased in a high load operation domain. The solving method of this problem is possible by supercharge. Therefore, in order to improve thermal efficiency by retardation of ntake valve closing time, the thermal efficiency improvement according to low compression is possible when there are a compensation device of a compression ratio and a supercharge device. This is a problem-solving method of low compression and high expansion cycle.

Compare Efficiency and Characteristics according to the WGT and VGT Application on the Off-road Engines (Off-road 엔진에서 WGT와 VGT장착에 따른 효율 및 특성 비교)

  • Shin, Jaesik;kang, Jungho;Ha, Hyeongsoo;Jung, Haksup;Pyo, Sukang
    • Journal of the Korean Society of Combustion
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    • v.21 no.4
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    • pp.1-5
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    • 2016
  • The aim of this study is to compare the effectiveness of turbo chargers on engines for off-road use when combined with WGT and VGT technologies. The effectiveness of turbo chargers was measured and performance was compared using a functional model. Exhaust characteristics were compared using WGT and VGT technologies through a gas analyzer. Results showed VGT technology was more effective at high RPM compared to WGT technology. When it came to maximising turbo performance, VGT was more effective than WGT in every test. WGT and VGT produced similar exhaust NOx levels, whereas the VGT was more effective on the PM.