• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.221-223
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• 1999

In this work, samples were manufactured variously by changing conventional calcining and sintering conditions and we tried the utilization by making the heat treatment time, which is demanded to high-Tc phase formation, much shorter. We found out optimal heat treatment conditions with the analysis on formation process at superconducting phase in term of the change of calcining and sintering time and then, examined X-ray diffraction(XRD) patterns, scanning electron microscope(SEM) measurement and energy dispersive X-ray spectrometer(EDX) of the samples manufactured under heat treatment conditions which we suggest here. As a result, 2223 high-$T_c$, phase of (Bi,Pb)SrCaCuO superconductor starting with ($Bi_l$ xPbx,)$_2$$Sr_2$$Ca_2$$Cu_3$$O_y$, composition was formed from 1 hr sintering sample at temperature nearby melting point and also the completed sample with calcining and sintering time of 9 hr was formed high-$T_c$.low-$T_c$ phase appearing in sight above the critical temperature of liquid $N_2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.254-258
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• 2000

Current leads of high $T_{c}$ superconductor were fabricated with Bi excess B $i_{2.2}$/S $r_{1.8}$/C $a_{1}$/C $u_{2}$/ $O_{x}$ composition by rapid cooling method. The dimensions of final samples were fixed 3 mm and 8 mm diameter with 50 mm length each To control uniform density the samples were preformed by CIP(Cold Isostatic Press) process and followed by partial or full melting process after raising up to 90$0^{\circ}C$ for 30min. Plate shaped microstructure was clearly observed adjacent to the Ag tube wall and the size of plate was about 100$\mu$m. However the severe destruction of growth orientation was shown in the inner growth part. critical temperature ( $T_{c}$) was about 53~71K after directional growth while Tc was decreased about 77~80 K before directional growth. After directional growth critical current( $I_{c}$) and critical current density( $J_{c}$) in the specimen of 8 mm diameter at 50 K were about 110 A and 280 A/c $m^2$ respectively.pectively.ely.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.50-55
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• 2001

A new type of flywheel energy storage system that has a horizontal axle with High $T_c$, superconductor bearings using Y123 single-domained crystals was developed.The dynamic Properties, stiffness and damping of the high $T_c$, superconductor radial bearings were experimentally estimated using a imbalance excitation method. The imbalance excitation method applied to this rotor- bearing system identified the identified stiffness and damping of the high temperature superconductor beatings to be 2.8 $3.3 {\times} 10^5 N/m and 775 204$ Nsec/m respectively.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.501-506
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• 2001

The creep crack growth properties in 3.5NiCrMoV steel were investigated at $550^{\circ}C$ by using CT specimen under constant $C_t$ condition that was held during crack growth of 1mm distance. $C_t$ lely on load line displacement rate and $C^*$ usually increase with crack length though load is reduced in order to maintain constant $C_t$ value as crack growth. Fully coalesced area(FCA) ahead of crack tip tend to increase as $C_t$ increase to the critical value, and after that value FCA decrease. For the tertiary creep stage of crack growth test, the most of displacement is due to the steady state creep, except only small part due to the primary creep and other effects. Therefore, tests were mainly interrupted in the tertiary stage to obtain high value of $C_t$. At constant load and $C_t$ region, crack growth slope was 0.900 and 0.844 each, on the other hand $C^*$ slope was 0.480.

• The Journal of the Petrological Society of Korea
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• v.2 no.1
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• pp.9-18
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• 1993

The high-P metamorphic belt in central China, between the Sino-Korean and the Yangtze continental plates, is composed of the low-T and high-P metamorphic belt on the south and the high-T and high-P metamorphic belt on the north. The low-T and high-P metamorphic belt consists predominantly of bimodal metamorphic volcano-sedimentary sequences of Middle to Upper Proterozoic, characterized by the occurrences of blueschists, which have undergone a progressive metamorphism from blueschist through greenschist to epidote amphibolite facies with metamorphic conditions of 7~14 kb and 350~$560^{\circ}C$. The high-T and high-P and high-P metamorphic belt mainly consists of the Upper Archean to Lower Proterozoic crystalline basement characterized by the aboundant occurrences of eclogites formed at 12~28 kb and 620~$840^{\circ}C$. The formation of high-P metamorphic belt is related to the collision between the Sino-Korean and the Yangtze continental plates during Indosinian orogeny. The two belts may extend to central Korean Peninsula correlating respectively to the Okchon belt and the Kyonggi massif based on comparative studies of geography, tectonics and petrology. Therefore, much attention should be paid to search for such high-P metamorphic rocks as blueschists or eclogites in those two areas, which can play a key role for understanding the tectonic evolution of the Korean Peninsula.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.399-405
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• 2016

The objective of this study was to determine the effect of sakso 2 corn kernels and cobs extracts on antioxidant activity in rats fed a high fat-cholesterol diet (HFC) for 2 weeks. 48 male Sprague-Dawley (4-weeks-old) were randomly divided into 6 groups: normal diet (N), HFC (C), HFC and 0.05% kernel extracts of Saekso 2 (T1), HFC and 0.25% kernel extracts of Saekso 2 (T2), HFC and 0.05% cob extracts of Saekso 2 (T3), HFC and 0.25% cob extracts of Saekso 2 (T4). The weight gain in all treatment groups were significantly lower and the food efficiency ratio (FER) in all treatment groups except T3 were lower than C group. Liver index (liver weight/100 g body weight) in N group and T2 were significantly lower than C group. The level of total cholesterol in plasma of N group and T2 were significantly lower than C group and HDL-cholesterol in plasma of N group and T2 were significantly lower than C group. Malondialdehyde (MDA) concentration of thiobarbituric acid reactive substances in N group, T3 and T4 were significantly lower than C group. Activity of catalase (CAT) in all treatment groups were lower than C group. These result suggest that saekso 2 corn kernels and cobs extracts may reduce oxidative damage through the activation of antioxidative defense systems in rats fed high fat-cholesterol diets.

• Progress in Superconductivity
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• v.11 no.2
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• pp.147-151
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• 2010

We have developed a high-$T_c$ SQUID magnetocardiogram (MCG) system for small laboratory animals. White noise of the measurement system was about 30 fT/$Hz^{1/2}$ when measured in a magnetically shielded room. We optimized the measurement position to obtain clear MCG wave from rat's small heart by using grid measurements. With the optimization, the MCG signal was successfully detected with the peak amplitude of about 30 pT. We could observe well defined P-, QRS-, and T-waves from the rat MCG. The results suggest that the developed system has a strong potential to monitor the progress of the heart disease model by using a laboratory rat.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.800-806
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• 2012

Reactive oxygen species (ROS) are produced by oxidative stresses which cause various chronic diseases such as diabetes and obesity. Ginseng (Panax ginseng C.A. Mayer) has been reported to contain various biological activities such as anti-cancer, anti-diabetic, neuroprotective, radioprotective, anti-amnestic and anti-aging effects. In this study, we investigated the effects of Panax ginseng, treated with high temperatures and high pressures, on oxidative stress in C2C12 myoblasts and 3T3-L1 adipocytes. Oxidative stress was induced in the C2C12 cells through the introduction of $H_2O_2$ (1 mM), and cells were then treated with various ginseng preparations: dried white ginseng (DG), steamed ginseng (SG) and high temperature and high pressure treated ginseng (HG). In addition, 3T3-L1 preadipocytes were treated with various ginsengs for up to 8 days following standard induction of differentiation. Our results show that HG treatment significantly protected oxidative stress in both cell lines and enhanced gene expression of antioxidant enzymes. Therefore, in this study, we investigated the protective effects of ginseng on the oxidative stress of adipocytes and muscle cells.

• Korean journal of food and cookery science
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• v.10 no.4
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• pp.412-419
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• 1994

The Contents of proximate compositions, vitamin C and minerals(Ca, P, Fe and Zn) of five Korean wild vegetables were analyzed. Twenty four cooking recipes with three of the vegetables were developed and their taste characteristics were evaluated by 12-trained panels. The five Korean wild vegetables are Cassia tora(C.t.), Lycium chinese Mill(L.c.), Trichosanthes quadricirra MIQ(T.q.), Polygonatum japonicum MORR et DECAIS(P.j.) and Articum lappa L.(A.l.). They have been known as the efficacious plants agaginst diabetes mellitus. In our previous work, their hypoglycemic effects have been studied through streptozotocin-induced diabetic rats and fed on the wild vegetables. Contents of moisture were 14~86% in the samples and L.c. showed relatively higher content of crude protein(16.4%). High level of crude fat was seen in C.t.(9.4%). Contents of vitamin C were also relatively high in the wild vegetables(14.2~42.0 mg%). Analysis of minerals revealed the high level of Ca in L.c. leaves, P in A.l. and Fe in C.t. and L.c. leaves. All of the samples contained Zn in 5.0~14.6 mg%. Twelvetrained taste panels indicated that the 24-preparations of L.c. leaves, fruites and P.j. were well accepted in taste, color and odor. Although L.c. fruit gruel, L.c. cream soup and P.j. saute were evalulated as less acceptable, their sensory scores were in 3.6~5.4 which were not undesirable. The newly developed cooking recipes of L.c. fruits and leaves showed better scores in color and texture, P.j. in texture and odor.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.1
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• pp.47-53
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• 1995

In this paper, the characteristics of breakdown voltage($\textrm{V}_{Brms}$) -temperature(T) for air insulated power installation in flowing air with variation of T(30[$^{\circ}C$] -180[$^{\circ}C$]) are presented. To study these subjects, needle-to-needle gap in the circular pipe(inner diameter 5[cm]) are used. Also, theories of gas discharge and hydrodynamics in pipe were used to analysis for the characteristics. The $\textrm{V}_{Brms}$ is proportional to flow velocity. At high velocity, $\textrm{V}_{Brms}$ is described the saturation. At high T(180[$^{\circ}C$]), $\textrm{V}_{Brms}$ is about 4.7(kV] lower than low T(30[$^{\circ}C$]). The empirical equation obtained from this study is $\textrm{V}_{Brms}=A\times{Log[Re}+B$. Where A, B : Constant.