• Title, Summary, Keyword: Loss

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Bottom Loss Variation of Low-Frequency Sound Wave in the Yellow Sea (황해에서 저주파 음파의 해저손실 변동)

  • Kim, Bong-Chae
    • Ocean and Polar Research
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    • v.29 no.2
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    • pp.113-121
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    • 2007
  • The sound wave in the sea propagates under the effect of water depth, sound speed structure, sea surface roughness, bottom roughness, and acoustic properties of bottom sediment. In shallow water, the bottom sediments are distributed very variously with place and the sound speed structure varying with time and space. In order to investigate the seasonal propagation characteristics of low-frequency sound wave in the Yellow Sea, propagation experiments were conducted along a track in the middle part of the Yellow Sea in spring, summer, and autumn. In this paper we consider seasonal variations of the sound speed profile and propagation loss based on the measurement results. Also we quantitatively investigate variation of bottom loss by dividing the propagation loss into three components: spreading loss, absorption loss, and bottom loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn, and the propagation losses measured in autumn were smaller than the losses in spring. The spreading loss and the absorption loss did not show seasonal variations, but the bottom loss showed seasonal variations. So it was thought that the seasonal variation of the propagation loss was due to the seasonal change of the bottom loss and the seasonal variation of the bottom loss was due to the change of the sound speed profile by season.

Coupling loss factor evaluation using loss factor based on the SEA (SEA에 기초를 둔 손실계수를 이용한 결합계수의 평가)

  • 안병하;황선웅;김영종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.568-571
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    • 1997
  • The overall aim of this paper is to determine coupling loss factor using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represent characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one directional power flow between two sub structures. Using these conditions, it is possible to find the coupling loss factor equation. The comparison between theory of power transmission on conjunction and above equation, show a good agreement in simple beam structure. To check the effectiveness of above equation, it was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure.

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Study on the Power Loss of High Frequency Mn-Zn ferrites (고주파 Mn-Zn ferrites 전력손실에 대한 고찰)

  • 서정주
    • Journal of the Korean Institute of Resources Recycling
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    • v.11 no.5
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    • pp.34-38
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    • 2002
  • To minimize the size of transformer volume, the operating frequency of ferrites cores increasing. The power loss of Mn-Zn ferrites comprises hysteresis loss, eddy current loss and residual loss. In the range more then 500 KHz, the total power loss is mainly due to the residual loss. The power loss increase with the frequency 3rd power. To minimize residual loss as well as eddy current loss, the microstructure should have small grain and high density, It should be noted that as the product of resonance frequency and static permeability increase, the power loss decrease at high frequency region.

Off-Design Performance Prediction of an Axial Flow Compressor Stage Using Simple Loss Correlations (간단한 손실모델을 이용한 단단축류압축기 탈설계점 성능예측)

  • 김병남;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3357-3368
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    • 1994
  • Total pressure losses required to calculate the total-to-total efficiency are estimated by integrating empirical loss coefficients of four loss mechanisms along the mean-line of blades as follows; blade profile loss, secondary flow loss, end wall loss and tip clearance loss. The off-design points are obtained on the basis of Howell's off-design performance of a compressor cascade. Also, inlet-outlet air angles and camber angle are obtained from semi-empirical relations of transonic airfoils' minimum loss incidence and deviation angles. And nominal point is replaced by the design point. It is concluded that relatively simple loss models and Howell's off-design data permit us to calculate the off-design performance with satisfactory accuracy. And this method can be easily extended for off-design performance prediction of multi-stage compressors.

Estimation Iron Loss Coefficients and Iron Loss Calculation of IPMSM According to Core Material (철심 재질에 따른 철손 계수 산정 및 IPMSM의 철손 계산)

  • Kang, Bo-Han;Kim, Yong-Tae;Cho, Gyu-Won;Lee, Jung-Gyu;Jang, Ki-Bong;Kim, Gyu-Tak
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.9
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    • pp.1269-1274
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    • 2012
  • In this paper, the iron loss was calculated using estimated iron loss coefficient at 650W Interior Permanent Magnet Synchronous Motor(IPMSM) and 250W IPMSM. The iron loss coefficients was estimated different according to electrical steel material used to stator and rotor core in motor. Aspect of The rotating flux field and alternating flux field was confirmed by magnetic field behavior and harmonic analysis in stator core, the iron loss was calculated using flux density by Finite Element Method(FEM) and estimated coefficients by iron loss coefficient estimation proposed in this paper. The iron loss experiment was performed for verified to iron loss calculation, and the iron loss coefficients were verified by comparison of iron loss calculation value and experimental value.

A Study on Factors Associated with Weight Loss by 'Gamitaeeumjowee-Tang' (가미태음조위탕의 체중감량 효과에 영향을 미치는 요인 연구)

  • Kang, Eun-Yeong;Park, Young-Bae;Kim, Min-Yong;Park, Young-Jae
    • Journal of Korean Medicine for Obesity Research
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    • v.17 no.2
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    • pp.68-76
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    • 2017
  • Objectives: The purpose of this study was to analyze the factors affecting weight loss effect of Gamitaeumjowee-tang and to see if weight loss could be predicted using influence factors and weight loss progress. Methods: From September 2016 to March 2017, we retrospectively reviewed the medical records of 139 patients who were visited to the Korean Oriental Clinic for 3 months. We conducted a regression analysis to determine whether age, gender, initial weight, patient health questionnaire-9, heart rate variability (HRV), sleep quality, drinking habit and the medication history of weight loss affect weight loss. We found weight loss prediction equations using multiple regression analysis applying significant factors and weight loss progress. Results: Gender and initial weight had a significant effect on weight loss in all periods (P<0.001). HRV had a significant effect on primary weight loss (P<0.01). Other factors did not have any significant effect on weight loss. Using the significant factors, weight loss of each period could be predicted from 23.9% to 44.6%, and tertiary weight loss could be predicted with 76.6% using factors, primary weight loss and secondary weight loss (P<0.001). Conclusions: This study suggests that weight loss effect of Gamitaeumjowee-tang maybe be affected by influence factors and that weight loss prediction equations using them can be used for obesity treatment.

A survey of the status of hair loss product use, hair loss treatment and satisfaction level (탈모(脫毛) 고객(顧客)의 제품이용실태와(製品使用實態) 관리(管理) 및 만족도(滿足度) 조사(調査))

  • Lee, Ji-Suk;Kim, Sung-Nam
    • Journal of Fashion Business
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    • v.11 no.2
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    • pp.76-91
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    • 2007
  • The domestic market for scalp care and hair loss management reached 1 trillion won. The market for hair loss management is expected to expand further. Systematic scalp and hair care services, such as scalp scaling, scalp massage, equipment maintenance, scalp care products sale, and care program based on scalp and trichology are provided. This study examined the status of hair loss management and use of hair care products by people experiencing hair loss and the level of their satisfaction. In addition, this study presents basic data for the effective hair loss management and marketing strategies for scalp and hair loss clinics. The results are as follows. 41.2% of the study subjects were in their 20s, and 66.6% of the study subjects were women. As for the hair loss symptoms, 45.2%, the largest percentage, had thin and wispy hair and more women had thin hair than men. 80.0% of men had oily hair. As for the scalp condition, 39,3% had oily scalp. As more women experience hair loss, 39.6% had female pattern hair loss and 31.0% had male pattern hair loss. As the largest percentage of people experiencing hair loss was in their 20s, 33.4%, the largest percentage, had the onset of hair loss in their early 20s. 34.1%, the largest percentage, reported having used the clinic for less than 1 month. The older the subject, the longer the length of hair clinic use. As for the average number of monthly hair loss clinic visits, 28.2%, the largest percentage, said 3 times. As for the hair loss management product use, 61.9%, said they do not use it and 38.1% said they use it. 5.6%, the largest percentage, used Davines at home and 9.6%, the largest percentage, used Kerastase at the clinic. As for the experience of hair loss product previously, 84.5% said they had no experience and 15.5% said they had eThe following are related to the satisfaction level of hair loss management. xperience. 5.0%, the largest percentage, reported having used Daenggimeori. The following are related to the satisfaction level of hair loss management. 32.8%, the largest percentage, said the effect of hair loss management lasted less than 6 monthas. As for the satisfaction levels on hair loss management program, service, skill of the hair specialist, hygiene, and hair loss management products, most people indicated between average and somewhat satisfactory levels. As for the satisfaction level on the cost of hair loss management, most people indicated average satisfaction level. As for the element essential to hair loss management, 39.0%, the largest percentage, indicated development of effective and specialized programs, 28.2%, indicated low price, 25.1%, indicated systematic and professional education of the hair specialist, 4.6%, indicated marketing and promotion, 2.5%, indicated service quality, and 0.6% indicated others.

Transport Loss Characteristics of a Bi-2223 Tape in External AC Magnetic Fields (외부 교류지장에 대한 Bi-2223테이프의 통전손실 특성)

  • Ryu, Kyung-Woo;Kim, Chang-Wan;Cha, Guee-Soo
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.6
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    • pp.290-295
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    • 2001
  • The transport loss of a Bi-2223 tape exposed to external magnetic fields was investigated. The results show that the transport loss is independent on voltage lead arrangements in case the magnetization loss is compensated. A serous increase of the transport loss due to external AC magnetic field is observed. The loss is described well by dynamic resistance loss in relatively high fields, but another mechanism than the dynamic resistance must be responsible for the increase of the loss in low fields. The transport loss is also dependent strongly on the orientation of the external fields.

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Remote Sensing Monitoring and Loss Estimated System of Flood Disaster based on GIS

  • Wenqiu, Wei
    • Proceedings of the KSRS Conference
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    • pp.507-515
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    • 2002
  • Remote Sensing Monitoring and Loss Estimated System of Flood Disaster based on GIS is an integrated system comprised flood disaster information receiving and collection, flood disaster simulation, and flood disaster estimation. When the system receives and collects remote sensing monitoring and conventional investigation information, the distributional features of flood disaster on space and time is obtained by means of image processing and information fusion. The economic loss of flood disaster can be classified into two pus: direct economic loss and indirect economic loss. The estimation of direct economic loss applies macroscopic economic analysis methods, i.e. applying Product (Industry and Agriculture Gross Product or Gross Domestic Product - GDP) or Unit Synthetic Economic Loss Index, direct economic loss can be estimated. Estimating indirect economic loss applies reduction coefficient methods with direct economic loss. The system can real-timely ascertains flood disaster and estimates flood Loss, so that the science basis fur decision-making of flood control and relieving disaster may be provided.

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Optimal Calculation Method of Distribution Loss in Distribution Systems

  • Rho Dae-Seok
    • KIEE International Transactions on Power Engineering
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    • v.5A no.2
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    • pp.109-115
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    • 2005
  • Recently, the needs and concerns regarding power loss have been increasing according to energy conservation at the level of the national policies and the business strategies of power utilities. In particular, the issue of power loss is the main factor for determining rates for electrical consumption in the deregulation of the electrical industry. However, because of the lack of management for power loss load factors (LLF) it is difficult to make a calculation for power loss and to make a decision concerning the electric rates. Furthermore, loss factor (k-factor) in Korea, which is of primary significance in the calculation of distribution power loss, has been used as a fixed value of 0.32 since the fiscal year 1973. Therefore, this study presents the statistical calculation methods of the loss factors classified by load types and seasons by using the practical data of 65 primary feeders that have been selected by appropriate procedures. Based on the above, the algorithms and methods, as well as the optimal method of the distribution loss management classified by facilities such as primary feeders, distribution transformers and secondary feeders is presented. The simulation results demonstrate the effectiveness and usefulness of the proposed methods.