• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.77-80
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• 1999

In this paper. We experimentally investigated the magnetic properties of YBCO bulk superconductor using AC magnetization method. The sample is 2.8cm wide in a diameter and 1.4cm long. We applied Ac magnetic field parallel to the direction of length of YBCO bulk. It is observed that YBCO bulk has the diamagnetic properties. AC loss calculation of YBCO bulk superconductor was performed by evaluating the total area of magnetization traces. As depends on the frequency and amplitude of the applied magnetic field.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.743-745
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• 2002

Pyroelectric and dielectric properties of modified PZT thin film and bulk ceramics were studied. In case of bulk specimens were prepared by conventional ceramic process and thin films with same composition and (111) preferred orientation were prepared by the sol-gel process. Their crystal structure, pyroelectric and dielectric properties were investigated after poling at $150^{\circ}C$ for 30 min for bulk ceramics and no poling treatment, respectively. Dielectric constants and losses of bulk and thin film were 600, 875 and 0.028, 0.025, respectively. Pyroelectric coefficients obtained were $50nC/cm^2K$ and $30nC/cm^2K$, respectively.

• 한국연초학회지
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• 제21권2호
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• pp.182-187
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• 1999

A bulk curing experiment was carried out to evaluate the effect of air flow reduction in the bulk barn from color fixing stage in the chemical properties of cured leaves, The air flow was controlled by reducing air velocity of a blower from 0.3m/sec to 0.2m/sec using a boltage regulator(Slidac). The bulk curing before color fixing stage was processed in the conventional curing method. Reduction of air circulation in bulk barn did not affected so much on change of the contents of the main chemical components in cured leaved, such as nicotine, total sugar, total nitrogen, petroleum ether extract, and organic acids. Only a slight increase in essential oil contents, such as solanone, damascenone, damascone, $\beta$-ionone, and megastigmatrienone isomer, could be observed in leaves cured in the reduced air flow.

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.1-10
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• 2003

A computer simulation was carried out to determinate the optimum capacity of bulk type trailer which is used as a tractor attachment. Soil physical properties. such as soil moisture content. bulk density, soil hardness and soil texture were measured in the 10 major rice production area for computer simulation. Mathematical model which include soil physical properties and vehicle factor was used for computer simulation. Most of the soil texture of the investigated area was silty loam. Soil moisture content ranged between 30 and 40% mostly. Soil bulk density was in the range of 1.500 to 1.700 kg/㎥. Soil hardness ranged between 1 to 18 kg/$\textrm{cm}^2$. Soil hardness incorporate the effects of many soil physical properties such as moisture content texture and bulk density, and so the range of soil hardness was greater than any other physical properties. The capacity of bulk type trailer was above 3000 kg$_{f}$ fer the most of the investigated area. and mostly in the range of 4000 to 6000 kg$_{f}$ depending upon the slip. But for the soft soil area such as Andong and Namyang. tractor itself had mobility problem and showed minus trailer capacity for some places. For this area. the capacity of bulk type trailer ranged between 1000 and 2000 kg$_{f}$ mostly so bulk type trailer should be designed as a small capacity compared to the other area.ared to the other area. area.

• 한국초전도ㆍ저온공학회논문지
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• 제10권2호
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• pp.1-11
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• 2008

The application of bulk superconducting materials to electrical power systems is very attractive because bulk high temperature superconductors offer excellent electromagnetic properties. In recent years there has been significant progresses in the research and fabrication of superconducting bulk materials. Numerous efforts have been made worldwide to make bulk YBCO as a replacement of the conventional magnets to produce larger magnetic field and hence to improve the device performance in electrical power applications. This paper gives a comprehensive review of different applications of bulk HTS materials, concentrating in three areas including superconducting bearing, superconducting motors and high field magnets. The advantages of applying superconducting material into each application are analysed. The status of current research in each section is summarized and examples are given to demonstrate how YBCO bulk materials can benefit the design of electrical devices. Several numerical models which calculate the electromagnetic properties of bulk superconductors are introduced and finally the article concludes with a review on the studies of the demagnetisation effect in superconducting bulk magnets which is extremely relevant to applying superconducting technology to rotating machines.

• 대한소아치과학회지
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• 제43권4호
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• pp.365-373
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• 2016

치아우식증을 치료할 때 가장 많이 사용되는 수복재료 중 하나는 레진이다. 하지만 레진은 중합수축, 긴 작업시간, 수분 및 오염에 민감하다는 단점들이 존재하고 어린이를 치료할 때 더 두드러진다. 이러한 단점들을 해결하기 위해 bulk filling이 나타나게 되었고, 이를 가능하게 하는 bulk-fill 복합레진이 개발되었다. 본 연구의 목적은 전통적 복합레진과 bulk-fill 복합레진의 물성을 다양한 방법으로 평가 및 비교하기 위함이다. 전통적 복합레진 3 종류(Filtek Z-350 (Z-350), Unifil Flow (UF), Unifil Loflo Plus (UL)), bulk-fill 복합레진 2종류 (SureFil SDR flow (SDR), Tetric N-Ceram bulk fill (TBF))를 사용하였다. 광중합기는 light-emitting diodes를 사용하였고, 한번 중합할 때 20초간 시행하였다. 재료들의 미세경도는 비커스경도기로 측정하였고, 중합도 측정은 Fourier transform infrared spectroscopy을 사용하였다. 중합수축량은 컴퓨터로 제어되는 linometer를 이용하였다. 굴곡강도 및 굴곡계수는 3점 굽힘 시험법으로 측정하였고, 압축강도 및 압축계수와 함께 Universal testing machine을 이용하여 측정하였다. 통계분석은 ANOVA를 사용하였고, Scheffe의 사후검정을 하였다. 미세경도는 상면에서 Z-350이 가장 높은 값을 나타냈고, 하면은 TBF가 높은 값을 나타냈으나 UL은 상하면 모두에서 가장 낮은 값을 보였다. 상면과 하면의 미세경도 값의 비는 SDR, TBF가 높았다. 중합도는 bulk-fill 복합레진과 유동성 복합레진 상하면 모두에서 높게 나타나고, Z-350는 상하면 모두에서 55% 이하로 나타났다. 압축강도는 Z-350이 가장 높았으며 SDR이 낮게 나타났으나 UL과는 통계학적으로 유의하게 차이는 보이지 않았다. 압축계수는 Z-350이 높게 나타났고, UL이 가장 낮았다. 굴곡강도 및 굴곡계수는 Z-350이 가장 높았다. UL은 굴곡강도 및 굴곡계수 모두 가장 낮게 나타났다. UL이 가장 높은 중합수축을 보였고, Z-350이 가장 낮은 중합수축 값을 나타냈다. 유동성 복합레진이 비유동성 복합레진보다 중합 수축 양이 많았다. 결론적으로 bulk-fill 복합레진의 물성은 전통적 복합레진보다 떨어지지만 bulk filling할 때 중요한 상하면의 미세경도비 및 중합도는 높게 나타나 어린이의 치아우식증 수복치료 시 도움이 될 수 있을 것으로 사료된다.

• 한국연초학회지
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• 제22권2호
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• pp.133-137
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• 2000

The bulk curing experiment to improve the quality of flue-cured leaves were carried out to evaluate relationship between the modified(3 step-up) drying and conventional drying method in bulk curing process. Modified drying method was somewhat higher values in yellowing color index of cured leaves, and less brittle than those in conventional drying program. As to the chemical properties, there was no difference in chemical component levels in cured leaves between the modified and the conventional methods, while the major chemical compounds in relation to aromatic essential oil of cured leaves showed mostly higher level in the modified method than that in conventional drying method. Additionally 3 step-up drying method increased the tobacco quality by 2 % in price per kg compared with conventional drying method.

• 한국연초학회지
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• 제21권1호
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• pp.5-9
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• 1999

In recent years, the line of increase in policy on tobacco production triggered a rise in the loading volume per bulk curing barn, and manufacturers boosted the output of their blowers in order to prevent dirty leaves in the process of curing. for this reason, we studied the effect of the reducing air flow in bulk curing chamber from the color fixing stage to the stem drying stage of flue curing process on physical properties of cured leaves. The control of air flow was composed of the reducing air velocity of blower by means of a voltage regulator (slidac), and condition before color fixing stage was all the same with the conventional curing method. As a result, an effectiveness of improvement in the physical properties of cured leaves were observed. The leaves cured by this method were somewhat orange in color of upper stalk position, better bodied, and less brittle compared with the leaves produced by conventional curing. However, the leaves cured by this method had a little sharpness and harshness. As to the physical properties, there was decreased in occurrence of flat leaves than that of conventional ones. On the other hand, in case of reducing air flow during the curing process, increase of price per kg reached to about 5 % compared with those of conventional curing method.

• 한국연초학회지
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• 제22권1호
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• pp.13-18
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• 2000

All steps of the curing process are automatically controlled by preseted program according to stalk positions in flue-cured tobacco. The bulk curing experiment was carried out to evaluate the effect of the basic and modified curing program in curing time schedule of two bulk models in physical properties of cured leaves in a new flue-cured tobacco variety KF 114(Wicotiano tabacum L.). The curing process of KF 114 was prolonged in yellowing and quicker in browning stage than those of NC 82. There was no significant difference in physical properties and chromatic characteristics of the cured leaves between basic and modified program at two bulk models. The ratio of normal leaf color tended to increase and the greenish leaf decreased in the modified curing program of two models, but no difference in the brownish leaf ratio was olserved between two programs.

• 한국초전도ㆍ저온공학회논문지
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• 제19권3호
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• pp.33-39
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• 2017

This study presents that the orientation and the geometry of seed affect on the growth behavior of melt processed single grain REBCO bulk superconductor and its magnetic properties. The effects of seed geometry have been investigated for thin $30mm{\times}30mm$ rectangular powder compacts. Single grain REBCO bulk superconductors have been grown successfully by a top seed melt growth method for 8-mm thick vertical thin REBCO slab. Asymmetric structures have been developed at the front surface and at the rear surface of the specimen. Higher magnetic properties have been obtained for the specimen that c-axis is normal to the specimen surface. The relationships between microstructure, grain growth and magnetic properties have been discussed.