• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.377-386
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• 1996

Austenitic stainless steel type 304L has been nitrided under the low pressure of high nitrogen environment for 5 hours by the square-wave-pulse-d.c. plasma as a function of temperature 400~$600^{\circ}C$ and of pulsation. At the temperature range lower than $500^{\circ}C$ and at the relatively high ratio of pulse duration to pulse period, nonstoichiometric stainless steel nitride has been developed in the form of a thin layer which has many cracks. At the temperature range higher than $500^{\circ}C$, with the increasing temperature or with the increasing ratio of the pulse duration to pulse period up to 50s/100s, the nitrided layer was composed mainly of CrN and Fe4N phases and became thick, uniform, columnar and nearly crack-free. The nitrided layer at $500^{\circ}C$ was mixed with the low-temperature layer and the high temperature layer and was very brittle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.432-437
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• 2010

A new device injecting secondary fuel behind flameholder was invented and tested in order to reduce low frequency combustion instability of combustor using V-gutter flameholder. Specially designed combustion device could make large combustion instability up to 180 dB successfully, and newly invented device made a success to reduce 110~120Hz low frequency pressure pulsation up to 84%. It was found that the fuel flow rate of secondary fuel supplying behind flameholder was the only parameter which dominates reduction of instability. It is considered that stabilized flame with sufficient secondary fuel can lead to break the connection between combustion system and acoustic system due to independence of flame from fluctuation of main fuel resulted from synchronization with acoustic wave.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.109-117
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• 2011

Assuming that photons absorbed by a vessel do not have acute variations, DC component reflect the basal blood volume (or diameter) before blood pulsation. Vascular stiffness and reflection is influenced by changes in basal blood volume (or diameter). This paper describes analysis of the characteristic variations of vascular stiffness, according to relative variations in DC components of the PPG signal (25-75%). For quantitative analysis, we have used parameters that were proposed previously, reflection and stiffness index, and the second derivative of PPG waveform, b/a and d/a. Significantly, the vascular stiffness and reflections were increased according to increase in DC component of the PPG signal for more than about 3% of baseline values. The systolic blood pressure were increased from $113.1{\times}13.18$ to $116.2{\times}13.319$ mmHg, about 2.76% (r = 0.991, P < 0.001) and the AC component of the PPG signal were decreased from $2.073{\times}2.287$ to $1.973{\times}2.2038$ arbitrary unit, about 5.09% (r = -0.993, P < 0.001). It is separated by DC median and correlation analysis was performed for analyzing vascular characteristics according to instantaneous DC variations. There are significant differences between two correlation coefficients in separated data.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2491-2509
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• 2022

As an important device in the nuclear island, the nuclear coolant pump can continuously provide power for medium circulation. The vane is one of the stationary parts in the nuclear coolant pump, which is installed between the impeller and the casing. The shape of the vane plays a significant role in the pump's overall performance and stability which are the important indicators during the safety serve process. Hence, the bionic concept is firstly applied into the design process of the vane to improve the performance of the nuclear coolant pump. Taking the scaled high-performance hydraulic model (on a scale of 1:2.5) of the coolant pump as the reference, a united bionic design approach is proposed for the unique structure of the guide vane of the nuclear coolant pump. Then, a new optimization design platform is established to output the optimal bionic vane. Finally, the comparative results and the corresponding mechanism are analyzed. The conclusions can be gotten as: (1) four parameters are introduced to configure the shape of the bionic blade, the significance of each parameter is herein demonstrated; (2) the optimal bionic vane is successfully obtained by the optimization design platform, the efficiency performance and the head performance of which can be improved by 1.6% and 1.27% respectively; (3) when compared to the original vane, the optimized bionic vane can improve the inner flow characteristics, namely, it can reduce the flow loss and decrease the pressure pulsation amplitude; (4) through the mechanism analysis, it can be found out that the bionic structure can induce the spanwise velocity and the vortices, which can reduce drag and suppress the boundary layer separation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.278-283
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• 2000

As information communication technology developed we could check our blood pressure, pulsation electrocardiogram, SpO2 and blood test easily at home. To check our health at ordinary times is able though interlocking the house medical instrument with the wireless public data network This service will help the inconvenience to visit the hospital everytime and will save the individual's time and cost. In each house an organism data which is detected from the human body will be transmitted to the distance hospital and will be essentially applied through wireless public data network The medical information transmit system is utilized by wireless close range network It would transmit the obtained organism signal wirelessly from the personal device to the main center system in the hospital. Remote telemetry system is embodied by utilizing wireless media access protocol. The protocol is embodied by grafting CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) protocol falling mode which is standards from IEEE 802.11. Among the house care telemetry system which could measure blood pressure, pulsation, electrocardiogram, SpO2 the study embodies the ECC(electrocardiograph) measure part. It within the ECC function into the movable device and add 900㎒ band wireless public data interface. Then the aged, the patients even anyone in the house could obtain ECG and keep, record the data. It would be essential to control those who had a health-examination heart diseases or more complicated heart diseases and to observe the latent heart disease patient continuously. To embody the medical information transmit system which is based on wireless network. It would transmit the ECG data among the organism signal data which would be utilized by wireless network modem and NCL(Native Control Language) protocol to contact through wireless network Through the SCR(Standard Context Routing) protocol in the network it will be connected to the wired host computer. The computer will check the recorded individual information and the obtained ECC data then send the correspond examination to the movable device. The study suggests the medical transmit system model utilized by the wireless public data network.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.238-243
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• 2011

In this study, we attempted a structural analysis in order to design a balloon type extracorporeal membrane oxygenator that can induce blood flow without using blood pumps for the purpose of complementing the weakness in the existing extracorporeal membrane oxygenator. To analyze the flow characteristic of the blood flow within the virtual model of extracorporeal membrane oxygenator, computational fluid dynamics(CFD) modeling method was used. The operating principle of this system is to make the surface of the extracorporeal membrane oxygenator keep contracting and dilating regularly by applying pressure load using a balloon, and the 'ime Function Value'that changes according to the time was applied by calculating a half cycle of sine waveform and a cycle of sine.waveform Under the assumption that the uni-directional blood flow could be induced if the balloon type extracorporeal membrane oxygenator was designed as per the method described above, we conducted a structural analysis accordingly. We measured and analyzed the velocity and pressure of blood flow at both inlet and outlet of the extracorporeal membrane oxygenator through CFD simulation. As a result of the modeling, it was confirmed that there was a flow in accord with the direction of the blood by the contraction/dilation. With CFD simulation, the characteristics of blood flow can be predicted in advance, so it is judged that this will be able to provide the most optimized design in producing an extracorporeal membrane oxygenator.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.338-347
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• 1997

Apo E polymorphism(e2, e3, e4) was among the first reported genetic polymorphism that explained part of the normal vairation in plasma cholesterol concentrations. Both alleles E2 and E4 are significantly more frequent in patients with mixed forms of hyperlipidemia and contribute on the observed differences in CHD risk among different populations. Effects of apo E polymorphism on the distribution of plasma lipid profiles were studied in 89 normolipidemic healthy females, aged 19 up to 22 years. The relative frequencies of E3/3 was 0.787, E3/2 was 0.101, E3/4 allele was 0.112 and no E2/2, E2/4 and E4/4 were found. Weight, height and %LBM were elevated in E2 than those in E3&E4. No differences in the blood pressure among apo E isomers were found, otherwise the pulsation was higher in E4 than that in the others. There were no differences in plasma total-, total DL-, HDL$_3$-, HDL$_2$ cholesterol, apo B-100 and apo A-I, However, phenotype means rank E3/2>E3/3>E3/4 in average TG levels(p<0.0001) significantly, and rank E3/4>E3/3>E3/2 in LDL cholesterol levels. These results were related to the correlation between atherogenic indiced (AI) such as LDL/HDL, (TC-HDL)/HDL, HDL$_3$/HDL$_2$. The ratio of HDL$_3$& HDL$_2$was significantly increased in E2 & E4 than that in E3(P=0.043). LCAT activity was not different between E2 and E3 but was highly increased in E4 (p<0.0001 among apo E isomers), but CETP was not different. Since the negative correlation between LCAT and CETP in apo E2(r=-0.491) was stronger than that in apo E3, E2 allele impacts the clearance of plasma apo E mediated lipoproteins. In conclusion firstly, E4 mediated alteration through LDL or E receptors results in lower TG or higher $\beta$-lipoprotein levels and E2 shows reciprocal effects of E4, respectively. Second, E4 allele was more atherogenic than E2 allele because the higher levels of AI such as HDL$_3$/HDL$_2$ were criticized.

• Journal of the Korean Magnetics Society
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• v.13 no.2
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• pp.64-69
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• 2003

Ba-ferrite thin films were prepared on Si substrate with ${\alpha}$-Fe$_2$O$_3$ underlayer by a pulsed laser deposition system and characterized by X-ray, SEM, Mossbauer spectroscopy and VSM. The appropriate conditions of pulsation in ${\alpha}$-Fe$_2$O$_3$ and Ba-ferrite were the oxygen pressure of 0.1 Torr at a substrate temperature of 400$^{\circ}C$. Ba-ferrite crystals had the forms of ellipsoidal or needle and the grains shaped the more lumps with increasing the film thickness. Mossbauer spectroscopy assured that the direction of atomic spin in Fe ion was not random but had the tendency of arrangement normal to the substrate. The coercive force and squareness of hysteresis were larger in normal than in plane to the substrate but, the magnetic saturation moment was contrary to them. The spin arrangement was strongly affected by ${\alpha}$-Fe$_2$O$_3$ underlayer and the high coercive force and squareness were influenced by this. The crystal structure was conformed to be a Magntoplumbite symmetry with the hexagonal unit cell and the lattice constant of a increased with increasing film thickness, while c decreased

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.21-25
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• 2001

$\alpha$-Fe$_2$O$_3$ thin films were prepared on Si substrate by a pulsed laser deposition system and characterized by X-ray and Mossbauer spectroscopy. The appropriate conditions of pulsation was the power of 5.128 W/cm2 at on oxygen pressure of 0.1 Torr at a substrate temperature of 30$0^{\circ}C$. After that the film was heated at 80$0^{\circ}C$ for 1 day. The particles shape deposited on the film was ellipsoidal and the average length and width were 200~300 nm, 70~150 am respectively. The crystal structure was conformed to be of corundums symmetry with the hexagonal unit cell having a lattice constant of u = 5.03$\pm$0.05 $\AA$, c = 13.735$\pm$0.05 $\AA$. The average angles between the atomic spin and the magnetic hyperfine field of Fe ion were 38$^{\circ}$and 48$^{\circ}$ at above and blow the Morin transition temperature respectively. The Morin transition was found to occur at the temperature ranges from 200 K to room temperature and atomic spin direction was assumed to change from 48$^{\circ}$ to 80$^{\circ}$in respect to the c-axis.