• Title/Summary/Keyword: Loss Factor

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Analysis of Effect of Ditch Restoration on Soil Loss Reduction in Highland Agricultural Fields (고랭지밭의 구거복원에 따른 토양유실저감 효과분석)

  • Sung, Yunsoo;Kim, Dong Jin;Lee, Suin;Ryu, Jichul;Kim, Jonggun;Lim, Kyoung Jae;Kim, Ki Sung
    • Journal of Korean Society on Water Environment
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    • v.36 no.5
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    • pp.385-391
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    • 2020
  • Soil loss is a serious problem frequently caused by local torrential rainfalls due to climate change. In particular, soil loss is occurring in agricultural areas rather than urban areas, and many pollutants are introduced into rivers, causing environmental problems. To reduce soil loss, the Ministry of Environment has designated and managed non-point source management areas. The Jaun-district in Hongcheon-gun, which was designed as a non-point pollution source management area in Gangwon-do, is located in the upper stream of Soyang Lake. Most of the agricultural fields are composed of highland agriculture fields. The highland agricultural fields in the Jaun-district are also composed of large-scale farming areas, and the ditches located near the agricultural fields have been illegally used for farmland. Therefore, the local government in Hongcheon-gun is conducting a project to restore the ditches occupied by agricultural fields. However, an analysis of the amount of soil loss that can be reduced by the restoration of the ditches has not been conducted yet. Thus, the purpose of this study was to analyze the effect of reducing the soil loss from the restoration of the ditches used as agricultural fields in the Jaun-district. The SATEEC L Module was used to analyze the reduction in soil loss by ditch restoration. The SATEEC L Module was constructed to estimate the LS factor using Moore and Burch's method after calculating the slope length using the digital elevation model and the maximum allowable slope length. The LS factor and the USLE formula were used to estimate the amount of soil loss that could be reduced by ditch restoration. The analysis showed that the ditch restoration could reduce about 16.6% of the soil loss in the Jaun-district. The results of this study will contribute to the study of methods to reduce soil loss in non-point pollution management areas.

A Generalized Loss Analysis Algorithm of Power Semiconductor Devices in Multilevel NPC Inverters

  • Alemi, Payam;Lee, Dong-Choon
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.2168-2180
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    • 2014
  • In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

Analysis on Characteristics of Transmission Loss using Marginal Loss Factors Based on the KEPCO's Expected Peak Load Data of Year 2000 (한계손실계수에 의한 한전 예상첨두계통 송전손실 특성 분석)

  • NamKung, Jae-Yong;Choe, Heung-Gwan;Mun, Yeong-Hwan;O, Tae-Gyu;Im, Seong-Hwang;Han, Yong-Hui
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.7
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    • pp.333-339
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    • 2001
  • The transmission networks are not perfect conductors and a percentage of the power generated is therefore lost before it reaches the loads. This network loss effects to the cost of suppling power to consumers, and must be considered if the most efficient dispatch and location of generators and loads is to be achieved. In this paper, we propose an approximate calculation of marginal loss factors to analyze characteristics of transmission loss of KEPCO power system. These static marginal loss factors are approximately calculated based on the KEPCO's expected summer peak load data of year 2000.

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Estimation of R-factor for Universal Soil Loss Equation with Monthly Precipitation Data in North Korea (북한 지역의 월 강수량으로부터 토양 유실 예측 공식 적용을 위한 강수 인자 산출)

  • Jeong, Yeong-Sang;Park, Cheol-Soo;Jeong, Pil-Kyun;Im, Jung-Nam;Shin, Jae-Sung
    • Korean Journal of Soil Science and Fertilizer
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    • v.35 no.2
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    • pp.87-92
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    • 2002
  • Soil erosion is detrimental to sustain soil productivity in north Korea, since agriculture of this country depends largely upon the slope land in mountainous area. Taking any measure for protection from erosion should be based on prediction of soil loss. Estimation of rainfall factor, R, in north Korea for the Universal Soil Loss Equation was attempted. The monthly precipitation data of the twenty six locations provided by the Korean Meteorological Adminstration were used. From the relationship between II_30 and the July-August precipitation concentration percents, the regional adjustment factor was obtained. The rainfall factor was calculated with the monthly precipitation data and the regional adjustment factor. The annual precipitation in north Korea ranged from 606 to 1,520mm, and the July-August precipitation concentration percents were 34.4 to 53.8. The regional adjustment factor ranged from 0.53 to 1.33 showing lower value in the highland and east coastal region than in the mid mountainous inland and west region. The R-factor value estimated from the monthly precipitation and the regional adjustment factor ranged from 107 to 483, which was lower than average value in south Korea.

Effects of Alkaline Earth Oxides on Electrical Characteristics of Steatite Porcelain (Steatite 자기의 전기적 특성에 미치는 알칼리 토금속 산화물의 영향)

  • 이종근;이병하;전승관
    • Journal of the Korean Ceramic Society
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    • v.16 no.1
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    • pp.31-37
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    • 1979
  • The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.

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Risk assessment for clinical attachment loss of periodontal tissue in Korean adults

  • Rheu, Gun-Bak;Ji, Suk;Ryu, Jae-Jun;Lee, Jung-Bok;Shin, Chol;Lee, Jeong-Yol;Huh, Jung-Bo;Shin, Sang-Wan
    • The Journal of Advanced Prosthodontics
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    • v.3 no.1
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    • pp.25-32
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    • 2011
  • PURPOSE. The purpose of this study was to assess the prevalence and extent of clinical attachment loss of periodontal tissue and to find out variables related to clinical attachment loss (CAL) in Korean adults older than 40 years of age. MATERIALS AND METHODS. Data were collected from 2,519 subjects who were part of a cohort study conducted in Ansan city by Korea University Medical School for Korean Genome project. Age, sex, smoking, drinking, fast glucose, blood pressure, obesity and total cholesterol levels were examined. The oral examination included probing pocket depth, gingival recession and CAL of Ramford's teeth. The severity of periodontitis was classified based on the mean value of CAL. The relationship between each risk factor and the severity of CAL was independently estimated using the chi-square test, the test or one-way ANOVA. Multiple regression analysis was used to determine the significance of each factor in the periodontal disease. RESULTS. The prevalences of clinical attachment between 1 and 3 mm, between 3 and < 5 mm, and ${\geq}$ 5 mm were 80.27%, 16.75% and < 1%, respectively. Although the univariate analysis showed age, gender, smoking, fasting glucose, blood pressure and total cholesterol levels were significantly related to the severity of CAL, multiple regression analysis indicated that age (P < .0001), gender (P < .0001) and smoking (P < .05) were only significantly related. CONCLUSION. Older age, male gender and smoking were significant risk factor for the increase of CAL, and these may be useful indicators of periodontitis high-risk groups.

Damping and vibration response of viscoelastic smart sandwich plate reinforced with non-uniform Graphene platelet with magnetorheological fluid core

  • Eyvazian, Arameh;Hamouda, Abdel Magid;Tarlochan, Faris;Mohsenizadeh, Saeid;Dastjerdi, Ali Ahmadi
    • Steel and Composite Structures
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    • v.33 no.6
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    • pp.891-906
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    • 2019
  • This study considers the instability behavior of sandwich plates considering magnetorheological (MR) fluid core and piezoelectric reinforced facesheets. As facesheets at the top and bottom of structure have piezoelectric properties they are subjected to 3D electric field therefore they can be used as actuator and sensor, respectively and in order to control the vibration responses and loss factor of the structure a proportional-derivative (PD) controller is applied. Furthermore, Halpin-Tsai model is used to determine the material properties of facesheets which are reinforced by graphene platelets (GPLs). Moreover, because the core has magnetic property, it is exposed to magnetic field. In addition, Kelvin-Voigt theory is applied to calculate the structural damping of the piezoelectric layers. In order to consider environmental forces applied to structure, the visco-Pasternak model is assumed. In order to consider the mechanical behavior of structure, sinusoidal shear deformation theory (SSDT) is assumed and Hamilton's principle according to piezoelasticity theory is employed to calculate motion equations and these equations are solved based on differential cubature method (DCM) to obtain the vibration and modal loss factor of the structure subsequently. The effect of different factors such as GPLs distribution, dimensions of structure, electro-magnetic field, damping of structure, viscoelastic environment and boundary conditions of the structure on the vibration and loss factor of the system are considered. In order to indicate the accuracy of the obtained results, the results are validated with other published work. It is concluded from results that exposing magnetic field to the MR fluid core has positive effect on the behavior of the system.

A Study on the Curing Properties of Kevlar/Epoxy Prepreg (케블라/에폭시 프리프레그의 경화특성에 관한 연구)

  • 제갈영순;이원철;권오혁;윤남균;임길수;안종기;박경준
    • Composites Research
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    • v.14 no.2
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    • pp.1-7
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    • 2001
  • The studies on the formulation and curing behaviors of Kevlar/Epoxy prepreg for NOSE CONE of aircraft were presented in this paper. Dielectrometer and differential scanning calorimeter were used in order to check the curing behaviors. This prepreg showed the lowest ionic viscosity around $120^{\circ}C$, and then the ionic viscosity was gradually increased up to $200^{\circ}C$. This indicated that the curing reaction of this prepreg started at $120^{\circ}C$ and the molecular weight was increased by the accelerated thermal cross-linking reaction. The loss factor and tan $\delta$ values were also measured and discussed. The loss factor behaviors of Kevlar/Epoxy prepreg, which is related to the fluidity of matrix, were fecund to be similar with that of ionic viscosity. The thermal reaction properties of this prepreg were also studied by differential scanning calorimeter.

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The Effect of motives and benefits and loss factors of social commerce on the product purchase satisfaction (소셜커머스의 이용동기와 혜택 및 손실요인이 제품 구매만족도에 미치는 영향)

  • Lee, Sang-Min
    • Journal of Digital Convergence
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    • v.14 no.9
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    • pp.149-158
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    • 2016
  • Recently social commerce has become an issue in E-commerce. It was made in purpose to seek the satisfaction of consumers plan to shop attempts to boost use of social commerce. Social commerce motives and benefits and loss factors are examined the impact of purchase satisfaction. Statistical analysis was performed using the multiple regression analysis. The results were as follows. First, economic incentives and hedonic motivations and opportunistic motivation factor had a significant effect on purchase satisfaction. Second, the benefits are psychological factors and price benefits had a significant effect on purchase satisfaction. Third, the more it feels less sense when using social commerce and economic losses, as used to feel less discomfort were higher purchase satisfaction. Finally, it was confirmed that the greater the relative benefit factors influence than the loss factor. This study is significant in that it provided meaningful data from the viewpoint of a consumer who uses social commerce sites.

Loss Minimization Control of Interior Permanent Magnet Synchronous Motors Considering Self-Saturation and Cross-Saturation

  • Pairo, Hamidreza;Khanzade, Mohammad;Shoulaie, Abbas
    • Journal of Power Electronics
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    • v.18 no.4
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    • pp.1099-1110
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    • 2018
  • In this paper, a loss minimization control method for interior permanent magnet synchronous motors is presented with considering self-saturation and cross saturation. According to variation of the d-axis and q-axis inductances by different values of the d-axis and q-axis components of currents, it is necessary to consider self-saturation and cross saturation in the loss minimization control method. In addition, the iron loss resistance variation due to frequency variation is considered in the condition of loss minimization. Furthermore, the loss minimization control method is compared with maximum torque per ampere (MTPA), unity power factor (UPF) and $i_d=0$ control methods. Experimental results verify the performance and proper dynamic response of the loss minimization control method with considering self-saturation and cross saturation.