• Title/Summary/Keyword: Loss load factor

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Development of Time Lag Considered (TLC) Crowd Load Model Based on Probabilistic Approach (개인별 시간지연효과를 고려한 확률론적 군중 하중모형 개발)

  • Kim, Sung-Yong;Lee, Cheol-Ho
    • Journal of Korean Society of Steel Construction
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    • v.24 no.1
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    • pp.1-11
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    • 2012
  • To overcome the limitations of current evaluation procedures for floor vibration under crowd loading, two kinds of uncertainties associated with individual time lag differences and the complex behavior of crowd should be taken into account. The complex behavior of crowds has yet to be fully described, even though individual differences can be dealt with statistically. This paper proposes time lag considered (TLC) crowd model based on a probabilistic approach. The load reduction factor, which reflects the effect of a general degree of synchronization among crowd, is proposed. Extensive Monte Carlo simulations were carried out to determine various crowd behaviors by using the TLC crowd model proposed. The TLC crowd model can rationally treat the energy loss of various crowd patterns. This indicates that it may be used as a theoretical basis in refining dynamic load factor of crowd loading.

Characteristics of Runoff Load from Nonpoint Source Pollutants in the Lake Doam Watershed (도암호 유역에서 비점오염물질의 유출부하 특성)

  • Kwak, Sungjin;Bhattrai, Bal Dev;Gim, Giyoung;Kang, Phil-Goo;Heo, Woomyung
    • Korean Journal of Ecology and Environment
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    • v.51 no.1
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    • pp.135-147
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    • 2018
  • In order to investigate the runoff characteristics of nonpoint source pollutants in the Lake Doam watershed, water quality and flow rate were monitored for 38-rainfall events from 2009 to 2016. The EMC values of SS, COD, TN and TP were in the range of 33~2,169, 3.5~56.9, 0.09~7.65 and $0.06{\sim}2.21mg\;L^{-1}$, respectively. As a result of analyzing the effect of rainfall factor on the nonpoint source pollutant load, EMCs of SS, COD and TP showed a statistically significant correlation with rainfall (RA) (p<0.01) and SS showed highly significant correlation with maximum rainfall intensity (MRI, R=0.48). The load ranges of SS, COD, TN and TP were 10.4~11,984.6, 1.1~724.4, 0.6~51.6 and $0.03{\sim}22.85ton\;event^{-1}$, respectively, showing large variation depending on the characteristics of rainfall events. The effect of rainfall on the load was analyzed. SS, COD and TP showed a positive correlation, but TN did not show any significant correlation. The annual load of SS was the highest with $88,645tons\;year^{-1}$ in 2011 when rainfall was the highest with 1,669 mm. The result of impact analysis of nonpoint source pollution reduction project and land-use change on runoff load showed that pollutant load significantly reduced from 2009 to 2014 but SS and TP loads were increased from 2014 to 2016 due to increase in construction area. Therefore, we suggested that nonpoint source pollution abatement plan should be continued to reduce the soil loss and pollutants during rainfall, and countermeasures to reduce nonpoint source pollution due to construction need to be established.

Feasibility Study on Road Bridge Passed by Heavy Equipment Transporter (HETS 차량의 교량 통과 가능성에 관한 연구)

  • Kang, Young-Chul;Lee, Pil-Jae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.2
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    • pp.236-247
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    • 2009
  • In Korea, the driving system restriction criteria is strictly applied(gross weight 400kN, axial load 100kN). Especially after the Seoungsu Bridge accident, safety factor has been strictly applied. The Safety factor is applied to the cumulative results for each steps like design, construction, maintenance of the Bridge. Because of it, the bridge is undervalued compared to its capacity. So, this generates loss for both private and military sector(eg. logistical delays, structural damage, etc.). But analyzing data from many existing researches we have confirmed that the military heavy vehicle may pass through the first class bridges. In consequence, this study have focused on determining whether HETS vehicles can pass over the first class bridge, without safety issues, using MIDAS structural analysis program. The results have confirmed that the military heavy vehicle may pass over the bridge.

Analysis, Design and Experimental Comparison of 2㎾ Power Factor Corrector Converters With Soft-Switching Methods (소프트 스위칭 방식을 갖는 2㎾ PFC 컨버터의 분석 설계 및 실험 비교)

  • Park, Gyeong-Su;Kim, Yun-Ho
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.9
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    • pp.537-544
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    • 2002
  • This paper describes a comparative analysis of soft switching boost converters through design, production and experiment. Soft switching boost converters are designed to satisfy the condition of input voltage 170-265Vac, output voltage 400Vdc, output current 5A, output power 20W-2000W and unit power factor. In addition, parameter values are designed so that system operation can be compared under this is similar conditions. The efficiency of the combined inductor soft switching boost converter was 97.63% with 1011 load better than that of other boost converter types. The combined inductor soft switching converter has simple circuit construction and low switching loss. EMI resulted by the switching noise, and harmonic distortion.

Effect of Change in Water Content and NCO Index on the Static Comfort of Polyurethane Seat Foam Pad for Automobiles (물 함량과 NCO Index 변화가 자동차용 폴리우레탄 시트 폼 패드의 정적 안락감에 미치는 영향 고찰)

  • Lee, Byoung Jun;Lee, Sung Hoon;Choi, Kwon Yong;Kim, Sang-bum
    • Applied Chemistry for Engineering
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    • v.28 no.1
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    • pp.57-63
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    • 2017
  • In this study, we identified how the water content change in various NCO index affects the static comfort of polyurethane seat foam pad for automobiles. In order to identify factors that affect the static comfort, a static load test was performed using UTM to plot a hysteresis curve. The hardness of the foam when it was modified by 25, 65%, hysteresis loop area, hysteresis loss (%), and Sag factor were also obtained. By measuring the swelling ratio, it was confirmed that, as the water content increased in a fixed NCO index, the hardness and crosslinking density increased while the restoring force decreased due to the increase of urea bond. Also the Sag factor decreased due to the increase of surface hardness. As the NCO index increased in a fixed water content, the urethane and urea bond reacted more with isocyanate, leading to an increase in hardness and decrease in restoring force.

Effect of the Reactive Power Compensation System on Performance Enhancement in a 900 MW Combined Cycle Power Plant (무효전력보상장치 설치가 900 MW 복합화력발전소의 성능향상에 미치는 효과)

  • Lee, Young Ok;Yoo, Hoseon
    • Plant Journal
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    • v.17 no.2
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    • pp.48-53
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    • 2021
  • In the case of a 900 MW combined cycle power plant, most of the load on the site is a rotating device and is operated at a low power factor, and the power factor decrease increases the reactive power, which causes the efficiency of the device to be consumed and unnecessary unnecessary power consumption. This study intends to present the results by installing and operating a reactive power compensation device that absorbs and removes reactive power, which is a solution to this problem, on a 6.9 kV on-board bus. As a result of application of this system, first, it was confirmed that the power factor of the rotating machine was improved to 0.22 and the load power in the house was reduced by 1.4%, and the thermal efficiency of the generator was increased by 0.1% and the power generation power by 810 kW. Next, it was confirmed that the cost of construction and operation can be reduced in the future due to economic feasibility, with a decrease of 200 million won/year in electricity loss compared to 1.5 billion won in investment, an increase of 1 billion won/year in sales, and a one-year capital recovery period.

Evaluation of Characteristics of Ground Anchor Using Large Scale Laboratory Test (실규모 실험을 이용한 그라운드 앵커의 거동 특성 평가)

  • Sangrae Lee;Seunghwan Seol
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.11
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    • pp.19-24
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    • 2023
  • Ground anchor has been widely used specially for maintaining stability on reinforced cut slope in expressway. While the durability of the ground anchors should be ensured over the service life. However, the long-term loss of tensile force has occurred in most of field-installed anchors. Main causes are not clearly identified and very few studies have been made for analyzing long-term behavior of ground anchor in slopes. In this study, full-scale model tests and long-term measurements were made to obtain the load-displacement data and identified the causes of the long-term behaviors of ground anchor. As a result, the bond strength decreases exponentially with increasing water-binder ratio. Especially, groundwater is the most influencing factor to the bond strength. In the long-term behavior, the load decreases sharply until the initial settlement stabilized, and thereafter the tension force decreases constantly.

A study on the analysis of the failure probability based on the concept of loss probability (결손확률모델에 의한 파손확률 해석에 관한 연구)

  • 신효철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.2037-2047
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    • 1991
  • Strength is not simply a single given value but rather is a statistical one with certain distribution functions. This is because it is affected by many unknown factors such as size, shape, stress distribution, and combined stresses. In this study, a model of loss probability is proposed in view of the fact that one of the fundamental configuration of nature is hexagonal, for example, the shapes of lattice unit, grain, and so on. The model sues the concept of loss of certain element in place of Jayatilaka-Trustrum's length and angle of cracks. Using this model, the loss probability due to each loss of certain elements is obtained. Then, the maximum principal stress is calculated by the finite element method at the centroid of the elements under the tensile load for the 4,095 models of analysis. Finally, the failure probability of the brittle materials is obtained by multiplying the loss probability by the ratio of the maximum principal stress to theoretical tensile strength. Comparison of the result of the Jayatilaka-Trustrum's model and the proposed model shows that the failure probabilities by the two methods are in good agreement. Further, it is shown that the parametric relationship of semi-crack lengths for various degrees of birittleness can be determined. Therefore, the analysis of the failure probability suing the proposed model is shown to be promising as a new method for the study of the failure probability of birttle materials.

The Study on Estimation of The Transformer Capacity of Housing and Economic Evaluation Using Case Studies (공동주택 변압기용량 적정 산정을 위한 수용률 개선 및 사례 연구를 통한 경제성 평가)

  • Lee, Yun-Sang;Seo, Jung-Youl;Shin, Hee-Sang;Cho, Sung-Min;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.9
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    • pp.142-149
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    • 2010
  • Interest in energy efficiency and savings have been rising internationally. For this reason, the domestic housing construction in the area of power equipment is being actively studied. Currently approximately 400,000 per year of domestic housing is being built. Applies to housing construction during the current transformer capacity low utilization and load factor has been applied has been designed. In other words, excessively high reserve capacity has been applied. According to this problem, initial facility costs and power losses will cause because transformer low utilization be appropriated. Thus, the energy efficiency drops. In this paper, analysis of past utilization of the housing transformer, and applying an appropriate demand factor has been analyzing the energy loss reduction. this analysis of current domestic conditions for the proper housing transformer scheme is to calculate the capacity.

Effect on Ice Slurry Flowing in the Elbow of Various Angle (다양한 각도의 곡관 내에서 아이스슬러리의 유동에 따른 영향)

  • 김규목;박기원;권일욱
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.2
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    • pp.142-149
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    • 2004
  • Recently, the government introduced the thermal storage system for reducing the electric power load. Especially, the ice slurry type has gained lots of interest due to its good heat transfer and flowing characteristics. This study was peformed to understand the effects of transporting ice slurry through elbows of various angle. Propylene glycol water solution was used and about 2 mm ice particles were circulated. The experiments were carried out under various conditions, such as concentration and velocity of water solution ranging between 0∼20 wt%, 1.5∼2.5 m/s, respectively. And elbows with 4 different angles of 30$^{\circ}$, 45$^{\circ}$, 90$^{\circ}$, 180$^{\circ}$. The differential pressure and IPF (ice packing factor) between the pipe entry and exit were measured. The tendency of pressure loss and outlet IPF in elbow is that the pressure loss was reduced as concentration and flow velocity of water solution is increased, and low value appeared at 10 wt% and 2.5 m/s. The variation of outlet IPF was compared with the inlet IPF in the range of $\pm$20%.