• Title/Summary/Keyword: load ratio

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A Detailed Analysis of the Part Load Ratio and Cooling Energy Characteristics of Chiller Operation in an Office Building (사무소 건물에서 냉동기의 부분부하율 및 냉방 에너지 성능 특성 분석)

  • Seo, Byeong-Mo;Yu, Byeong-Ho;Lee, Kwang-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.11
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    • pp.567-573
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    • 2015
  • Commercial buildings account for significant portions of the total building energy in Korea, and thus, a variety of research on chiller operation has been carried out. However, most of the studies were carried out on the chiller itself, i.e., the part load ratio characteristics and the corresponding electricity energy consumption patterns were not analyzed in existing studies. In this study, the part load ratio and the operating characteristics of the vapor compression chiller were analyzed within an office building equipped with the conventional variable air volume system. As a result, significant portions of total operating hours, cooling load, and energy consumption turned out to be in the part load ratio range of 0 through 50%. Thus, energy consumption was significantly affected by the chiller COP at low part load conditions, indicating that chiller operation at the part load is an important factor in commercial buildings.

A Study on the Fire Resistance Performance of Reinforced Concrete Columns according to Axial Load Ratio (축력비 조건에 따른 철근콘크리트기둥의 내화성능에 관한 연구)

  • Hwang, Kyu-Jae;Cho, Bum-Yean;Yeo, In-Hwan
    • Fire Science and Engineering
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    • v.27 no.6
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    • pp.26-31
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    • 2013
  • This study, to evaluate the technology of the fire resistance design of Reinforced Concrete columns based on fire resistance performance design, was suppose to use as basic data for performance design through a measure of temperature and deformation using heat transfer analysis and Heat-load test of the Reinforced Concrete columns as parameter is the axial load ratio. In accordance with axial load without eccentricity, the load ratio of 0.30, 0.35, 0.40 and 0.47 were imposed on columns. As a result of this study, 0.40 or more of axial load ratio can be ensured that the fire resistance performance was considered satisfactory.

A Study on the Fatigue Crack Propagation Behavior in the SB41 Welding Material (SB41용접재의 피로크랙 진전거동에 관한 연구)

  • 최병기;장경천
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.2
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    • pp.43-49
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    • 2002
  • SB41 material is welded automatically and is investigated some effects of the welding residual stress in the growth and propagation of fatigue crack, so as to study the fatigue behaviour in the welding residual stress field. The summarized results are as follows; 1) In case of the load amplitude is constant, as the stress ratio is changing to 0.1, 0.33 and 0.5 the propagation life is constant but the growth life decreases. And than, when maximum load or minimum load is constant as the stress ratio increases the growth life and propagation life. 2) It was shown that fatigue crack propagation ratio da/dN was almost constant regardless of the stress ratio change at constant load amplitude and that the larger stress ratio, the slower was the fatigue crack propagation ratio. 3) The opening ratio U is influenced by $K_max$ but it isn't only the function of $K_max$ because data range is very large. 4) The fatigue life of the specimens on tensile compressive residual stress field was decreased and increased respectably more than that of the base metal.

Analysis of Drawbar Load Acting on Tractor Engine at Maximum Drawbar Power (최대 견인 출력시 트랙터 엔진의 견인 부하 분석)

  • Kim, S.C.;Kim, K.U.;Kim, D.C.
    • Journal of Biosystems Engineering
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    • v.34 no.2
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    • pp.71-76
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    • 2009
  • This study was conducted to investigate the load acting on a tractor engine when it delivers the maximum power at drawbar. The results of the drawbar tests on the 5 locally-made and 14 imported tractors conducted at NIAE in 2004, and the 15 tractors tested at OECD test stations in foreign countries were analyzed and presented by the torque load ratio, defined as a ratio of the engine torque load caused by drawbar pull to its full-load capacity, as a function of pull speed. The NIAE test results showed that the torque load ratio increased from 20 to 80% with pull speed less than 5 km/h. At speeds faster than 5 km/h, it was 80${\sim}$110% regardless of the pull speed. However, the OECD test results showed that the torque load ratio was evaluated mostly to be 70${\sim}$90% in the entire pull speed range. The same trend was also shown for the maximum drawbar load. The difference in the torque load ratio may be attributable to bias-ply tires for locally-made and some imported tractors. It is also suggested that the input torque load may be increased safely up to 120% of the full load capacity of the tractor engine for an accelerated life test of tractor transmissions.

Emission characteristics of diesel engine by mixing LPG (디젤기관의 LPG 혼합에 의한 오염배출물 저감특성)

  • 장영준;전충환;이춘우
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.44-52
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    • 1993
  • In this study, the characteristics of decreasing exhaust gas of diesel engine was examined in dual fuel method by using commertial LPG for automotive. LPG was supplied to engine intake port by fumigation method and flow rate was controlled by using the needle valve. LPG supply ratios were 0, 20, 30% of total fuel amount to be supplied to engine by mass base. We investigated the effect of LPG supply ratio on exhaust gas concentrations related to excess air ratio and engine load at 1600, 1800, 2000 rpm. Soot concentration decreased about 30% in proportion to the increase of the LPG supply ratio. NOx concentration decreased in proportion to the increase of the LPG than diesel only and the increase rate was higher at low engine load. BSFC(Brake specific fuel consumption) was lower in proportion to the increase of the LPG supply ratio at high engine load and to the decrease of LPG supply ratio at low engine load.

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Effect of Diaphragm Ratio by Load Condition and Behavior in Composite Structures of Sandwich System (샌드위치식 복합구조체에서 하중조건.거동특성에 따른 격벽간격비의 영향)

  • 정연주;정광회;김병석;박성수;황일선
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10a
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    • pp.297-302
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    • 2000
  • This paper presents the effect of diaphragm spacing ratio(depth to span) on behavior and capacity of composite steel-concrete structures of sandwich system. Numerical analysis has been performed variety diaphragm ratio, behavior and load condition. As a results of this study, in case of shear behavior and concentrated load, the capacity of structure such as yielding and ultimate load improve according to diaphragm ratio because of concrete confining effect by steel plate and stress redistribution by diaphragm. But in case of bending behavior or uniform load, it proved that diaphragm ratio don't influence on behavior and capacity of composite structures of sandwich system.

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Short-term Peak Power Demand Forecasting using Model in Consideration of Weather Variable (기상 변수를 고려한 모델에 의한 단기 최대전력수요예측)

  • 고희석;이충식;최종규;지봉호
    • Journal of the Institute of Convergence Signal Processing
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    • v.2 no.3
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    • pp.73-78
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    • 2001
  • BP neural network model and multiple-regression model were composed for forecasting the special-days load. Special-days load was forecasted using that neural network model made use of pattern conversion ratio and multiple-regression made use of weekday-change ratio. This methods identified the suitable as that special-days load of short and long term was forecasted with the weekly average percentage error of 1∼2[%] in the weekly peak load forecasting model using pattern conversion ratio. But this methods were hard with special-days load forecasting of summertime. therefore it was forecasted with the multiple-regression models. This models were used to the weekday-change ratio, and the temperature-humidity and discomfort-index as explanatory variable. This methods identified the suitable as that compared forecasting result of weekday load with forecasting result of special-days load because months average percentage error was alike. And, the fit of the presented forecast models using statistical tests had been proved. Big difficult problem of peak load forecasting had been solved that because identified the fit of the methods of special-days load forecasting in the paper presented.

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The Ultimate Load Capacity of the Parabolic Arches by Elasto-Plastic Model (탄소성 모델에 의한 포물선 아치의 극한 내하력 평가)

  • 조진구;박근수
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.3
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    • pp.92-100
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    • 2002
  • The advent or high-strength steel has enabled the arch structures to be relatively light, durable and long-spanned by reducing the cross sectional area. On the other hand, the possibility of collapse may be increased due to the slender members which may cause the stability problems. The limit analysis to estimate the ultimate load is based on the concept of collapse mechanism that forms the plastic zone through the full transverse sections. So, it is not appropriate to apply it directly to the instability analysis of arch structures that are composed with compressive members. The objective of this study is to evaluate the ultimate load carrying capacity of the parabolic arch by using the elasto-plastic finite element model. As the rise to span ratio (h/L) varies from 0.0 to 0.5 with the increment of 0.05, the ultimate load has been calculated fur arch structures subjected to uniformly distributed vertical loads. Also, the disco-elasto-plastic analysis has been carried out to find the duration time until the behavior of arch begins to show the stable state when the estimated ultimate load is applied. It may be noted that the maximum ultimate lead of the parabolic arch occurs at h/L=0.2, and the appropriate ratio can be recommended between 0.2 and 0.3. Moreover, it is shown that the circular arch may be more suitable when the h/L ratio is less than 0.2, however, the parabolic arch can be suggested when the h/L ratio is greater than 0.3. The ultimate load carrying capacity of parabolic arch can be estimated by the well-known formula of kEI/L$^3$where the values of k have been reported in this study. In addition, there is no general tendency to obtain the duration time of arch structures subjected to the ultimate load in order to reach the steady state. Merely, it is observed that the duration time is the shortest when the h/L ratio is 0.1, and the longest when the h/L ratio is 0.2.

Study on the Characteristics of Consolidation(II) -The Effects of Load Increment Ratio Consolidation Characteristics- (압밀(壓密) 특성(特性)에 관(關)한 연구(硏究)(II) -하중(荷重) 증가율(增加率)이 압밀특성(壓密特性)에 미치는 영향(影響)-)

  • Kang, Yea-Mook;Ryu, Neung-Hwan
    • Korean Journal of Agricultural Science
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    • v.4 no.1
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    • pp.88-93
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    • 1977
  • The following is the result of experiment on consolidation test under various load increment ratios by alternation of standard load increment ratio. The more load increment ratio was, the more settlement was resulted. But expansions were not associated with load increment ratios. Primary consolidation took longer period to complete as load increment ratio was decreased. And under the condition of over-consolidated range, the completion of primary consolidation took longer period as the load was incremented. Under the condition of normal consolidated range, there was no change in time of completing primary consolidation. The coefficient of consolidation was decreased with increment of consolidation load, and the coefficient of consolidation had high values as the load increment ratio was increased. The values of ratio of secondary consolidation was highest near the transition point of consolidation curve.

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A Study on Design Parameters to Improve Load Capacity of Spiral Grooved Thrust Bearing (스파이럴 그루브 스러스트 베어링의 부하용량 향상을 위한 설계 변수에 대한 연구)

  • 강지훈;김경웅
    • Tribology and Lubricants
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    • v.18 no.3
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    • pp.181-186
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    • 2002
  • A numerical analysis is undertaken to show the influence of bearing design parameters on the load capacity of air lubricated spiral grooved thrust bearing. The governing equation derived from the mass balance is solved by the finite difference method. Optimal values for various design parameters are obtained to maximize the load capacity. The design parameters are the groove angle, the groove width ratio, the groove height ratio, and the seal ratio.