• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.674-682
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• 2018

Large industrial motors require a large area because of the high risk of shutdown accidents and large industrial accidents due to the lowering of the dielectric strength of the armature windings and overheating problems. Therefore, there is a demand for a large-capacity motor that has small size, light weight, and excellent dielectric strength compared with conventional motors. Superconducting motors have advantages of high efficiency and output power, low size, low weight, and improved stability. This results from greatly increasing the magnetic field generation by using superconductive field coils in rotating machines such as generators and motors. It is very important to design and analyze the cooling system to lower the critical temperature of the wires to achieve superconducting performance. In this study, a field loss analysis and low-temperature heat transfer analysis of the cooling system were performed through the conceptual design of a 100-HP high-temperature superconducting synchronous motor. The field loss analysis shows that a uniform pore magnetic flux density appears when high-temperature superconducting wire is used. The low-temperature heat transfer analysis for gaseous neon and liquid neon showed that a flow rate of 1 kg/min of liquid neon is suitable for maintaining low-temperature stability of the high-temperature superconducting wire.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.1-7
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• 2002

Characteristics (salt concentration, weight loss, soluble solid content, moisture content, and textural properties) of radish cube $(2{\times}2{\times}2\;cm)$ were evaluated during salting. Three different summer radish cultivars harvested in high land were immersed into 15% brine solution (radish : brine solution = 1 : 2) at $15^{\circ}C$ for 4 h. The time required to reach the optimum salt concentration (3%) was different among cultivars; 3 h for 'Bakbong', 4 h for 'Kwandong' and '92343'. Similar weight loss (about 24-26%) of salted radish cubes was found among cultivars. While the highest value of weight loss of salted radish cubes was observed with '92343', the lowest, 'Bakbong'. Hardness decreased during salting; the highest value of hardness was observer with 'Kwandong', the lowest, 'Bankbong'. The sample of '92343' has the lowest moisture content but has the highest soluble solid content and hardness, while 'Bakbong' has the highest moisture content, but has the lowest soluble solid content and '92343'. In separate experiments, seasonal variations in characteristics of salted radish cubes at optimum salt concentration (3%) were observed: for 'Bakbong', salt concentration, weight loss, soluble solid content, and hardness, and for 'Bakwang', salt concentration, weight loss, and hardness were higher in autumn cultivars than in spring or summer one, while moisture contents of both cultivars were higher in spring or summer cultivars than in autumn one.

• Food Science and Preservation
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• v.11 no.4
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• pp.508-515
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• 2004

In this study, salting conditions and dehydration methods were investigated. Salting time, concentration and temperature could be considered to variables in salting conditions. The diffused salt amounts to beef jerky depending on time are sharply increased in two hours. This result is caused by the difference decrease of concentration gradient between bulk solution and beef jerky. The increase of salting concentration and temperature resulted also in the increase of a diffused salt. The deeper bulk concentration made diffusion to beef easily with the bigger driving force and the movement of molecules is more active according to temperature increase. Dehydration is conducted with various methods such as natural drying, cold air drying and hot air drying. Comparing with color and texture among the drying methods, cold air drying showed superior quality in color and texture. Beef jerky by cold air drying colored more reddish than other drying methods and good cutting shear stress and tensile strength. In case of hardness and chewiness, hot air drying method showed the highest value, which means the worst texture.

• Korean Journal of Food Science and Technology
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• v.13 no.3
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• pp.227-232
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• 1981

To obtain several basic data which can be applied to preparations of intermediate moisture food (IMF) with cooked rice, various model IMF were prepared by infusing humectants such as glycerol, sorbitol. sodium chloride and sucrose into freeze-dried cooked rice and resulting water activities were measured by vacuum pressure manometer, Characteristics and composition of various humectants were studied on the basis of greatest lowering of water activities at the same w/w% concentration. Glycerol and sorbitol were more efficient in lowering water activity than other humectants. Mixture of humectants, however, were more effective than single solutes at the same concentration for lowering water activity. The measured values of water activity were compared to the predicted values by several known equations. Of those, the Ross equation was the most accurate means of predicting the water activity of the model IMF containing glycerol, and the Norrish equation, of the model IMF containing sorbitol, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.169-169
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• 2012

현재 디스플레이 시장은 LCD (Liquid Crystal Display), PDP (Plasma Display Panel) 등과 같이 평판 디스플레이가 주류를 이루고 있으며 현재에는 기존의 디스플레이와는 달리 잘 휘어지고 높은 투과성을 가지는 플렉시블 디스플레이에 대한 연구가 활발히 진행 중이다. 하지만 이러한 플렉시블 디스플레이에 사용되는 플라스틱 기판의 경우 용제에 대한 화학적 저항성 및 기계적인 안정성이 취약한 점과 대기중의 수분이나 산소가 플라스틱 기판을 통하여 소자내로 침투하게 되어 금속전극을 산화시키거나 기포 또는 흑점 등과 같은 비 발광 영역이 확산되어 소자의 수명을 단축시키는 치명적인 단점을 가진다. 이에 본 실험에서는 고밀도 플라즈마 형성이 가능하고 저온공정이 가능한 FTS (Facing Target Sputtering) 장비를 이용하여 Polyethylene terephthalate (PET) 기판위에 낮은 수분 투과율 또는 산소 투과율을 갖는 양질의 무기 산화막을 적층하기 위해 저 투습도 및 기계적인 경도 향상을 위한 비 반응성 박막으로 $Al_20_3$층을 Ar분위기에서 증착하였고 그 위에 박막의 stress 감소, 유연성 향상을 위한 반응성 박막으로 Al을 Ar과 $O_2$를 비율별로 증착하여 비교 실험하였다. 이와 같이 제작된 무기산화막들을 Uv- spectrophotometer를 이용하여 광학적 특성을 조사한 결과 가시광 영역에서 모두 80% 이상의 높은 투과율을 나타내었으며, 그 외 XRD (X-ray Diffraction)를 사용하여 결정성을 확인, SEM (Scanning Electron Microscope), AFM (Atomic Force Microscope)을 이용하여 박막의 구조와 표면향상 및 표면조도를 측정한 결과 모든 박막에서 밀집도가 좋으며 거칠기가 작은 것으로 확인되었다. 마지막으로 수분 투과율(WVTR)을 알아보기 위해 Mocon (Permatran W3/31)장비를 이용하여 측정한 결과 $1.0{\sim}3.0{\times}10^{-3}g/m{\cdot}day$의 낮은 수분 투과율을 볼 수 있었다. 이러한 측정 결과로 볼 때 향후 FTS 장비를 이용하여 양질의 플라즈마를 형성하여 알루미늄 무기산화막을 이용한 고밀도 다층막을 형성하면 더욱 낮은 수분투과율을 갖는 가스차단막을 제작할 수 있을 것으로 보여지며 반도체 소자 및 디바이스의 Pachaging으로도 사용가능 할 것이라 사료된다. 본 연구는 한국산업기술진흥원에서 지원하는 2011년도 지역산업기술개발사업의 연구수행으로 인한 결과물임을 밝힙니다.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.272-279
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• 2017

This study aimed to evaluate the microleakage and penetration of two hydrophilic sealants, Embrace $Wetbond^{TM}$ and Ultraseal $XT^{(R)}$ $hydro^{TM}$, when applied on dry and moist enamel, as compared to a conventionally used hydrophobic sealant, $Clinpro^{TM}$. A total of 60 sound human third molars were randomly divided into 5 groups according to the enamel moisture control and the sealant material used. After sealant application, the teeth were thermocycled and immersed in 1% methylene blue dye. Subsequently, the teeth were sectioned twice and the sections were examined using an optical microscope and image analysis software. Application of Embrace $Wetbond^{TM}$ on either dry or moist enamel resulted in more microleakage than $Clinpro^{TM}$. Application of Ultraseal $XT^{(R)}$ $hydro^{TM}$ on dry enamel showed a similar level of microleakage to $Clinpro^{TM}$, but application on moist enamel resulted in more microleakage. There were no significant differences between the groups in penetration. In conclusion, application of hydrophilic sealants on moist enamel did not improve the sealing ability and showed lower sealing ability than that of $Clinpro^{TM}$ applied on dry enamel.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.5
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• pp.47-54
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• 1996

본 연구에서는 지표면유출과 중간유출의 수문학적과정을 함께 모의발생 시키는 합성 유역모델이 제시되었다. 본 모델은 디지털지형모델과 상호 연결되도록 하였으며 지형이 복잡한 지역에서도 유출이 시간과 공간적으로 누가계산되어 이 분야의 조사연구에 필요한 정보를 제공할 수 있다. 본모델을 이용 유역의 불투수층 위에 분포해있는 토양의 중간계층과 토양수분의 계산 및 침투/용탈의 과정을 모의 발생시킬 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.66-74
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• 2016

The objective of this study is the investigation of the influence of carbonation on the penetration of chloride ions in reinforced concrete sections for different mix proportions and environmental conditions. A comprehensive numerical model based on the change of the pore structure and the chemical equilibrium was used for this combined action of carbonation and chloride ingress. The empirical formulae of some parameters in this model are estimated according to numerous experimental data. And, a set of data analysis is carried out to simplify the estimation of model variables to reduce the computational cost. A coupled simulation of the transports of carbon dioxide, chloride ions, heat and moisture is carried out. Then, the parametric analysis is given and the numerical results show that the effect of carbonation of the free chloride ingress is significant and depends on the binder types and concrete mix proportion.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.117-126
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• 2011

Based on thermodynamics, the mathematical framework governing the hydro-mechanical behavior of partially saturated soil is derived by using balance equations, and the numerical analysis through implementation of various effective stress definitions is performed. Effective stress on partially saturated soil describes the soil strength which is presented by the relationship between water content and soil suction. For the estimation of hydro-mechanical behavior on partially saturated soil, effective stress parameter ${\chi}$ defined from various literatures is especially analyzed to understand the conditions of constitutive equations regarding residual saturation and displacement of soil. As a result, effective stress parameter ${\chi}$ has an influence on the variation of matric suction in soil with an external load and seepage. However it was found that the effect of each parameter ${\chi}$ varies with residual degree of saturation, and that of each parameter ${\chi}$ decreased with decrease in displacement of soil caused by an external load.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.823-827
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• 2010

This study was conducted to assess the propriety of models for soil water characteristics estimation in anthropogenic soil through the measurement of soil water content and soil water matric potential. Soil profile was characterized with four different soil layers. Soil texture was loamy sand for the first soil layer (from soil surface to 30 cm soil depth), sand for the second (30~70 cm soil depth) and the third soil layers (70~120 cm soil depth), and sandy loam for the fourth soil layer (120 cm < soil depth). Soil water retention curve (SWRC), the relation between soil water content and soil water matric potential, took a similar trend between different layers except the layer of below 120 cm soil depth. The estimation of SWRC and air entry value was better in van Genuchten model by analytical method than in Brooks-Corey model with power function. Therefore, it could be concluded that van Genuchten model is more desirable than Brook-Corey model for estimating soil water characteristics of anthropogenic soil accumulated with saprolite.