• Title/Summary/Keyword: low-loss

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Newborn heating screening (신생아 청력장애의 선별검사와 의의)

  • Kim, Lee-Suk
    • Clinical and Experimental Pediatrics
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    • v.50 no.1
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    • pp.7-13
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    • 2007
  • Hearing loss in newborns is the most frequently occurring birth defect. If hearing impaired children are not identified and managed early, it is difficult for many of them to acquire the fundamental language, social and cognitive skills that provide the foundation for later schooling and success in society. All newborns, both high and low risk, should be screened for hearing loss in the birth hospital prior discharge (Universal Newborn Heaing Screening, UNHS). Objective physiologic measures must be used to detect newborns and very young infants with hearing loss. Recent technological developments have produced screening methods and both evoked otoacoustic emission (EOAE) and auditory brainstem response (ABR) have been successfully implemented for UNHS. Audiologic evaluation should be carried out before 3 months of age and infants with confirmed hearing loss should receive intervention before 6 months of age. All infants who pass newborn hearing screening but who have risk indicators for other auditory disorders and/or speech and language delay receive ongoing audiologic surveillance and monitoring for communication development. Infants with sensorineural hearing loss are managed with hearing aids and receive auditory and speech-language rehabilitation therapies. Cochlear implants can be an outstanding option for certain children aged 12 months and older with severe to profound hearing loss who show limited benefit from conventional amplifications.

Body Satisfaction and Weight Loss in Women College Students (여대생의 신체만족도와 체중조절)

  • Chaung, Seung-Kyo;Min, So-Young
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.13 no.3
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    • pp.485-492
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    • 2006
  • Purpose: The purpose of this study was to identify body satisfaction and weight loss experience according to individual's discrepancy between obesity by BMI (body mass index) and self-assessment. Method: The data were obtained by measuring height, weight and using a questionnaire to obtain data on self-assessment of obesity, body satisfaction and weight loss experience. The participants were 286 women college students in J city, Chungbuk. Results: The mean BMI of the women college student was $21.4{\pm}2.93kg/m^2$ which is within the normal range. The concordance rates between obesity by BMI and self-assessment were 54.1%, 39.9%, 61.5%, 78.6% (Kappa=.29) in underweight, normal, overweight, obese students respectively. Forty seven percent of students who were not obese (BMI $<23kg/m^2$) assessed themselves as obese. The mean body satisfaction of college students was very low and 64.3% of the students had a weight loss experience. The students who perceived themselves to be 'obese' even when their BMI was under $23kg/m^2$ reported lower body satisfaction and higher weight loss experience than other students. Conclusion: There were significant discrepancies between obesity by BMI and self-assessment in women college students. The self-assessment of obesity had a greater effect on body satisfaction and weight loss experience than actual BMI in women college students.

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Characteristics of AC loss of Hybrid Multi-Stacking with HTS Wires in External Magnetic Field (고온초전도 혼합적층선재의 외부자장 변화에 따른 손실 특설)

  • Lim, Hyoung-Woo;Lee, Dong-Min;Yun, Ki-Hyun;Cha, Guee-Soo;Lee, Hee-Joon
    • Proceedings of the KIEE Conference
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    • 2006.10d
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    • pp.71-73
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    • 2006
  • AC loss on variation of external magnetic field is a very important factor in development of power applications. In this paper, we measured and compared AC loss of hybrid-multi stacked wire made of the combination of 1G wires and 2G wires and uniform-multi-stacked wire made of one type of wires, 1G wires or 2G wires. Measurement was performed using by the linked-picked coil method. As results, as the number of wires increase, AC loss per unit volume of both stacked wires in low external magnetic field is reduced. Also AC loss of 2G slacked wire is higher than that of 1G wire. AC loss per unit length of 2G stacked wire is less than that of 1G stacked wire. And AC loss of hybrid-multi stacked wire made of the combination of 1G wires and 2G wires was between uniform-multi-stacked wire made of 1G wires and 2G wires.

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Numerical Study of Combustion Characteristics Inside a Micro-Tube Combustor (마이크로 튜브 연소기의 연소특성에 대한 수치해석 연구)

  • Oh Chang Bo;Choi Byung Il;Han Yong Shik;Kim Myung Bae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.12 s.243
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    • pp.1352-1359
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    • 2005
  • Unsteady simulations were performed to investigate the flame structure and the dynamic behavior of a premixed flame exposed to the wall heat loss. A 3-step global reaction mechanism was adopted in this study. Simulations were performed for two tube combustors with inner diameters($d_i$) of 1mm and 4mm. The material of tube combustor was assumed to be a Silicon Nitride($Si_{3}N_4$). The heat loss from the outer tube wall was controlled by adjusting the amount of convective and radiative heat loss. A conical premixed flame could be stabilized inside a tube of $d_i=4mm$. The flame stability inside a tube of $d_i=4mm$ combustor was not much sensitive to the amount of heat loss. In case of a tube of $d_i=1mm$, an oscillating flame was observed in very low heat loss condition and a flame could not be sustained in realistic heat loss condition.

Partial O-state Clamping PWM Method for Three-Level NPC Inverter with a SiC Clamp Diode

  • Ku, Nam-Joon;Kim, Rae-Young;Hyun, Dong-Seok
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1066-1074
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    • 2015
  • This paper presents the reverse recovery characteristic according to the change of switching states when Si diode and SiC diode are used as clamp diode and proposes a method to minimize the switching loss containing the reverse recovery loss in the neutral-point-clamped inverter at low modulation index. The previous papers introduce many multiple circuits replacing Si diode with SiC diode to reduce the switching loss. In the neutral-point-clamped inverter, the switching loss can be also reduced by replacing device in the clamp diode. However, the switching loss in IGBT is large and the reduced switching loss cannot be still neglected. It is expected that the reverse recovery effect can be infrequent and the switching loss can be considerably reduced by the proposed method. Therefore, it is also possible to operate the inverter at the higher frequency with the better system efficiency and reduce the volume, weight and cost of filters and heatsink. The effectiveness of the proposed method is verified by numerical analysis and experiment results.

Effect of Carbon Addition and Influence of Heat-treatment Temperature on Electromagnetic Wave Absorbing Properties of $Ni_{0.5}Cu_{0.1}Zn_{0.4}Fe_2O_4$-Rubber Composite ($Ni_{0.5}Cu_{0.1}Zn_{0.4}Fe_2O_4$ Ferrite-Rubber Composite의 전파흡수특성에 미치는 열처리 온도의 영향 및 Carbon 첨가효과)

  • 윤국태;이찬규;박연준
    • Journal of the Korean Magnetics Society
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    • v.11 no.1
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    • pp.14-20
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    • 2001
  • The structure, shape, size, and magnetic properties of Ni$_{0.5}$Cu$_{0.1}$Zn$_{0.4}$Fe$_2$O$_4$ have been investigated as a function of annealing temperatures. In order to control the microwave absorbing properties of ferrite-rubber composite and the complex losses (magnetic loss and conduction loss), the effect of carbon addition was also studied. It was found that the coercive force decreased with increasing heat-treatment temperatures. Relative complex permeability and reflection loss were measured by the network analyzer. As a result, the natural resonance occurred in the low frequency tinge, and the matching frequency of the ferrite-rubber composite prepared at 130$0^{\circ}C$ was found to be lower. As heat-treatment temperatures were increased, the magnetic loss ($\mu$$_{r}$", $\mu$$_{r}$′) and the dielectric loss ($\varepsilon$$_{r}$"/$\varepsilon$$_{r}$′) were increased. It was caused that the absorption characteristics of the absorber were improved. The conduction loss and magnetic loss were expected to be occurred together because two matching frequencies were shown with carbon addition. It was confirmed that the matching frequency of the microwave absorber could be controlled by controlling heat-treatment temperatures and carbon additions.ons.tions.

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STEAM GENERATOR TUBE INTEGRITY ANALYSIS OF A TOTAL LOSS OF ALL HEAT SINKS ACCIDENT FOR WOLSONG NPP UNIT 1

  • Lim, Heok-Soon;Song, Tae-Young;Chi, Moon-Goo;Kim, Seoung-Rae
    • Nuclear Engineering and Technology
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    • v.46 no.1
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    • pp.39-46
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    • 2014
  • A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

A Study A on Internal Loss Characteristics and Efficiency Improvement of Low Power Flyback Converter Using WBG Switch (WBG 스위치를 적용한 소용량 플라이백 컨버터의 내부손실 특성과 효율 개선에 관한 연구)

  • Ahn, Tae Young;Yoo, Jeong Sang
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.4
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    • pp.99-104
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    • 2020
  • In this paper, efficiency and loss characteristics of GaN FET were reported by applying it into the QR flyback converter. In particular, for the comparison of efficiency characteristics, QR flyback converter experimental circuits with Si FET and with GaN FET were separately produced in 12W class. As a result of the experiment, the experimental circuit of the QR flyback converter using GaN FET reached a high efficiency of 90% or more when the load power was 2W or more, and the maximum efficiency was observed to be about 92%, and the maximum loss power was about 1.1W. Meanwhile, the efficiency of the experimental circuit with Si FET increased as the input voltage increased, and the maximum efficiency was observed to be about 82% when the load power was 9W or higher, and the maximum loss power was about 2.8W. From the results, it is estimated that that in the case of the experimental circuit applying the GaN FET switch, the power conversion efficiency was improved as the switching loss and conduction loss due to on-resistance were reduced, and the internal loss due to the synchronous rectifier was minimized. Consequently, it is concluded that the GaN FET is suitable for under 20W class power supply unit as a high efficiency power switch.

Effects of cold and room temperature storage on the sprouting and marketability of early-grown spring potatoes

  • Heon-Seop Won;Kyusuk Han;Young Hun Lee
    • Food Science and Preservation
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    • v.31 no.1
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    • pp.33-45
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    • 2024
  • Three spring potato varieties (Atlantic, Chubaek, and Superior) were cultivated for 80, 90, and 100 days and compared in terms of their total and marketable yields and specific gravities. Subsequently, changes in the quality parameters (weight loss, sprouting rate, disease incidence, dry weight, and specific gravity) of potatoes cultivated for 100 days were monitored during two-month storage in improved and semi-underground warehouses at 4℃ and room temterature. The productivities of Atlantic, Superior, and Chubaek were maximized at cultivation periods of 100, 100, and >90 days, respectively. In all cases, cold storage resulted in <5.3% weight loss and no marketability loss. However, two-month room temperature storage resulted in pronounced marketability loss due to weight loss (6.2, 7.3% and 10.9% for Atlantic, Superior, and Chubaek, respectively) and sprouting (in ~13%, >75%, and 99% of Atlantic, Superior, and Chubaek tubers, respectively). The marketability of Atlantic, Superior, and Chubaek during cold storage was maintained for >2, ~2, and <2 months, respectively. All varieties were characterized by rapid sprouting, low dry weight and specific gravity, and rapid marketability loss during storage.

Transparent Sol-Gel Hybrid Dielectric Material Coatings for Low k Passivation Layer

  • Yang, Seung-Cheol;Oh, Ji-Hoon;Kwak, Seung-Yeon;Bae, Byeong-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.1453-1456
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    • 2009
  • Transparent sol-gel hybrid dielectric material (hybrimer) coating films were fabricated by spin coating and photo or thermal curing of sol-gel derived oligosiloxane resins. Hybrimer coating films are suitable as the passivation layer of TFT in AMLCD due to low dielectric constant, small loss tangent, low leakage current density, high transmittance and thermal stability.

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