• Title/Summary/Keyword: Core saturation

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Analysis of Hysteresis Characteristics of Flux-Lock Reactor (자속구속 리액터의 히스테리시스 특성 분석)

  • Lim, Sung-Hun;Choi, Hyo-Sang;Kang, Hyeong-Gon;Ko, Seok-Cheol;Lee, Jong-Hwa;Han, Byoung-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.255-258
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    • 2003
  • The hysteresis characteristics of flux-lock reactor, which is an essential component of flux-lock type superconducting fault current limiter (SFCL), was investigated. The hysteresis loss of iron core in flux-lock type SFCL does not happen due to its winding's structure especially in the normal state. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. Through the hysteresis curves together with the fault current level due to the inductance ratio for the 1st and 2nd winding, the increase of the number of turns in the 2nd winding of the flux-lock type SFCL had a role to prevent the iron core from saturation.

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Loss of coolant accident analysis under restriction of reverse flow

  • Radaideh, Majdi I.;Kozlowski, Tomasz;Farawila, Yousef M.
    • Nuclear Engineering and Technology
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    • v.51 no.6
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    • pp.1532-1539
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    • 2019
  • This paper analyzes a new method for reducing boiling water reactor fuel temperature during a Loss of Coolant Accident (LOCA). The method uses a device called Reverse Flow Restriction Device (RFRD) at the inlet of fuel bundles in the core to prevent coolant loss from the bundle inlet due to the reverse flow after a large break in the recirculation loop. The device allows for flow in the forward direction which occurs during normal operation, while after the break, the RFRD device changes its status to prevent reverse flow. In this paper, a detailed simulation of LOCA has been carried out using the U.S. NRC's TRACE code to investigate the effect of RFRD on the flow rate as well as peak clad temperature of BWR fuel bundles during three different LOCA scenarios: small break LOCA (25% LOCA), large break LOCA (100% LOCA), and double-ended guillotine break (200% LOCA). The results demonstrated that the device could substantially block flow reversal in fuel bundles during LOCA, allowing for coolant to remain in the core during the coolant blowdown phase. The device can retain additional cooling water after activating the emergency systems, which maintains the peak clad temperature at lower levels. Moreover, the RFRD achieved the reflood phase (when the saturation temperature of the clad is restored) earlier than without the RFRD.

A Case Study on Business Continuity following the Establishment of a Soho Fashion Shopping Mall: Longitudinal Research (소호패션쇼핑몰 창업 후 사업지속에 대한 사례연구: 종단적 연구를 중심으로)

  • Mi Young Son
    • Human Ecology Research
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    • v.62 no.1
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    • pp.1-13
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    • 2024
  • This study analyzed the current operational status, business continuity, and business continuity strategies of 11 Soho fashion shopping malls through a longitudinal case study (2019/2020 and 2022/2023). The aim was to determine how Soho fashion shopping malls are continuing their business having been successfully established in the fiercely competitive current online fashion market. Regarding changes in shopping mall operation status, all cases displayed changes in items, distribution channels, marketing channels, core values, and profit structures. After establishing the businesses, a crisis arose due to the COVID-19 pandemic, leading to difficulties in creating new customers. Moreover, there was excessive business expansion, resulting in saturation of the online platform store market. This meant companies were experiencing reduced sales (5) or difficulties in maintaining their business (3). However, there were differences in the direction of overcoming the crisis and continuing or converting the business. These revealed that to continue the business after successful establishment of an online fashion shopping mall, it is essential to have the expertise of entrepreneurs, work performance, and marketing ability, as well as differentiation capabilities such as product power and management strategy and core competitiveness that provides a relative advantage over other shopping malls. Customized government support at the level of the start-up ecosystem is also essential for the survival and business continuity of a SOHO online fashion shopping mall with poor human and material resources.

Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.381-386
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    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

Color Images Utilizing the Properties Emotional Quantification Algorithm (이미지 색채 속성을 활용한 감성 정량화 알고리즘)

  • Lee, Yean-Ran
    • The Journal of the Korea Contents Association
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    • v.15 no.11
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    • pp.1-9
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    • 2015
  • Emotion recognition and regular controls are concentrated interest in computer studies to emotional changes. Thus, the quantified by objective assessment methods are essential for application of color sensibility computing situations. In this paper, it is applied to a digital color image emotion emotional computing calculations numbered recognized as one representation. Emotional computing research approach consists of a color attribute to the image recognition focused sensibility and emotional attributes of color is the color, brightness and saturation separated by. Computes the sensitivity weighted according to the score and the percentage increase or decrease in the sensitivity property tone applied to emotional expression. Sensitivity calculation is free-degree (X), and calculates the tension (Y-axis). And free-level (X-axis) coordinate of emotion, which is located the intersection of the tension (Y-axis) as a sensitivity point. The emotional effect of the Russell coordinates are utilizing the core (Core Affect). Tue numbers represent the size and sensitivity in the emotional relationship between emotional point location and quantified by computing the color sensibility.

Magnetic Properties of NixFe100-x(x=40~50) Permalloy Powders and Dust Cores Prepared by Gas-Atomization (가스 분무법으로 제조된 NixFe100-x(x=40~50) 퍼멀로이 분말 및 압분 코아의 자기적 특성)

  • Noh, T.H.;Kim, G.H.;Choi, G.B.;Kim, K.Y.
    • Journal of the Korean Magnetics Society
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    • v.12 no.6
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    • pp.218-223
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    • 2002
  • We investigated the magnetic properties of High Flux-type $Ni_{x}Fe_{100-x}$(x=40∼50, wt.%) permalloy powders and dust cores. The powder was prepared by conventional gas atomization in mass production scale. At the composition of $Ni_{x}Fe_{55}$, saturation magnetization was maximum. In case of lower Ni content than X=45, the $M_{s}$, decreased largely with the decrease in Ni content, which is due to the invar effect. The permeability of compressed powder cores increased with the decrease in Ni content, which was considered to be due to the decrease in the magnetostriction. In addition, the dust core with Ni=45% showed the lowest core loss because of the increase in electrical resistivity leading to the low eddy current loss. From the better frequency dependence of permeability, larger Q value and superior DC bias characteristics of Ni=45% than those of Ni=50% core, it was confirmed that the 45%Ni-55%Fe powder alloy was better material for the dust core than commercial High Flux core materials.

A Study of Current Transformer for High Power Testing Facility (대전력 시험설비용 변류기 특성에 관한 연구)

  • Jung, Heung-Soo;La, Dae-Ryeol;Kim, Sun-Koo;Roh, Chang-Il;Kim, Won-Man;Lee, Dong-Jun
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.735-737
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    • 2002
  • A current transformer for measuring current in high power testing laboratory is exactly proportional to the current including D.C component due to electrical transient. But, current transformer isn't designed to consider D.C component, therefore when data acquisition system measure that current. the error is increased because of saturation of core. This paper describe the concept of transient factor and how to design the current transformer.

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Study on Calculation of Mutual and Self-inductance in SRM with Full-pitched winding (Full-pitched winding SRM에서의 상호(相互) 및 자기(自己) 인덕턴스의 산정에 관한 연구)

  • Baik, Seung-Kyu;Lee, Chi-Woo;Jung, Tae-Uk;Lee, Il-Chun;Hwang, Young-Moon
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.31-33
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    • 1996
  • A SRM develops its torque according to the inductance variation as the rotor position and the phase current. The variation of the inductance and the phase current plays an important role in output characteristics. Predicting and calculating the inductance is invaluable in the study of SRM. This paper suggests the estimation method of inductance as variation of phase current and rotor position considering magnetic saturation of motor core. This method is also applied to full-pitched winding SRM.

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The Variation of Sedimentary Rock Strength due to Weathering (풍화에 따른 퇴적암의 강도 변화)

  • 배우석;이봉직;오세욱;이종규
    • Journal of the Korean Society of Safety
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    • v.18 no.1
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    • pp.89-93
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    • 2003
  • The failure of rock slopes were influenced by weathering, which causes change in the shear strength. The weathering is also directly related to slaking and swelling characteristics. In the paper, the core of diameter loom was obtained by digging on rock slope of Kong-ju in Korea and then EDX(Energy Dispersive X-ray spectrometer) analysis was carried out to verified element of chief rock-forming minerals. Uniaxial compression tests, slaking tests, and point load test are performed to study engineering characteristics of conglomerate and red shale. As a results of slaking test, slaking index of conglomerate indicate range of 85.11-99.58 and shale indicate 58.37-99.23. Therefore, it is recognized that the resistance of shale to weathering decreases in shallow depth and it greatly influences the strength of rock. The result of uniaxial compression test and Point load test show that the strength of sedimentary such as conglomerate and red shale has an influence on both weathering and saturation.

Effect of Carrier Gas on the Microstructure and Magnetic Properties of Co Nanoparticles Synthesized by Chemical Vapor Condensation (화학기상응축공정(Chemical Vapor Condensation)으로 제조된 Co 나노분말의 미세구조 및 자기적 성질에 미치는 운송기체의 영향)

  • ;X. L. Dong
    • Journal of Powder Materials
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    • v.11 no.1
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    • pp.16-21
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    • 2004
  • The nano-sized Co particles were successfully synthesized by chemical vapor condensation (CVC) process using the precursor of cobalt carbonyl ($Co_2(CO)_8$). The influence of carrier gases on the microstructure and magnetic properties of nanoparticles was investigated by means of XRD, TEM, XPS and VSM. The Co nano-particles with different phases and shapes were synthesized with a change of carrier gas : long string morphologies with coexistence of fcc and hcp structure in Ar carrier gas condition; finer Co core in a mass of cobalt oxide with only fcc structure in He; rod type cobalt oxide phase in Ar+6vol%$O_2$. The saturation magnetization and coercivity was lower in Co nanoparticles synthesized in He carrier gas, due to their finer size.