• 한국초전도학회:학술대회논문집
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• v.10
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• pp.7-7
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• 2000

A high $T_c$ SQUID system is developed for the application to biological immunoassay. In this application, magnetic nanoparticles are used as magnetic markers to perform immunoassay, i.e., to detect binding reaction between an antigen and its antibody. The antibody is labeled with ${\gamma}-Fe_2O_3\;(or\;Fe_3O_4)$ nanoparticles, and the binding reaction can be magnetically detected by measuring the magnetic field from the nanoparticles. Design and set up of the system is described. The system consists of (1) SQUID magnetometer or gradiometer made of 30-deg. bicrystal junctions, (2) field and compensation coils to apply the magnetic field of about 1 mT, (3) special Dewar to realize a 2 mm-distance between the SQUID and the sample, (4) two layers of cylindrical shielding to reduce the extemal magnetic noise to about 1/100, and (5) an electric slider to move the sample with a speed of 10 mm/sec. The sensitivity of the system is studied in terms of detectable magnetic flux. For the measurement bandwidth from 0.2 Hz to 10 Hz, minimum-detectable amplitude of the magnetic flux is $0.8\;m\;{\Phi}_o$ and $0.25\;m{\Phi}_o$ for the magnetometer and the gradiometer, respectively, when the magnetic field of 1 mT is applied. The difference between them is due to the residual environmental noise, and the applied magnetic field does not increase the system noise. The corresponding weight of the magnetic markers is 1 ng and 310 pg, respectively. An experiment is also conducted to measure antigen-antibody reaction with the present system. It is shown that the sensitivity of the present system is 10 times better than that of the conventional method using an optical marker. A one order of magnitude improvement of sensitivity will be realized by the sophistication of the present system.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.380-388
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• 2000

In computing the optical flow, Horn and Schunck's method which is a representative algorithm is based on differentiation. Therefore it is difficult to estimate the velocity for a large displacement by this algorithm. In this paper, we propose a method for estimating nonuniform motion from sequential images which is based on integral brightness constancy constraints. The equations which transform a source image to a target image are expressed as a function of the displacement field. If marginal effects can be neglected, the form of the transformation integral transform or orthogonal expansion can be determined from the expansion coefficients of the two images. The apparent displacement field is then computed iteratively by a projection method which utilities the functional derivatives of the linearized moment equations. We demonstrate that the performance of the orthogonal function transform on the data set of large motion.

• Journal of Energy Engineering
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• v.16 no.3
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• pp.120-127
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• 2007

The purpose of this study is experimentally to analyze that the fuel mass fractions of multi-component mixed fuels have an effect on the characteristics of spray ignition and combustion under the ambient conditions of diesel combustion fields. The characteristics of ignition and combustion were investigated by chemiluminescence images and direct photography. The experiments were conducted in the RCEM(rapid compression expansion machine) with optical access. Multi-component fuels mixed with i-octane, n-dodecane and n-hexadecane are injected in RCEM by the electronic control of common rail injector. Experimental conditions set up 42, 72 and 112 MPa in injection pressure, 700, 800 and 900 K in ambient gas temperature. The results show that the ignition delay was dependent on high cetane number. In case of low ambient temperature, the more low boiling point fuels were mixed, the lower luminance regime had a remarkable effect and also shortened diffusion combustion by increasing heat release rate.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.3
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• pp.20-27
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• 2014

Nowadays, the bleaching techniques of thermomechanical pulp(TMP) are fast developing on the strength of some benefits, mainly on low production cost and good fiber property. In this study, the optimum concentration of bleaching chemicals and the environmental load of bleaching wastes were considered to improve the bleaching efficiency of thermomechanical pulp using Korean redpine(Pinus densiflora) under the peroxide-based bleaching system. The optical property of TMP after bleaching was planned to use higher grade of paper, like printing & writting paper, not general newspaper. The concentration of bleaching chemicals, NaOH, $Na_2SiO_3$ and EDTA, in hydrogen peroxide bleaching system, on the basis of O.D. pulp was closely influenced on the improvement of TMP brightness. Final target of bleaching efficiency was set up to above 76%-ISO brightness. The optimal target brightness of Korean redpine TMP was reached to 76.45%-ISO under the conditions of $H_2O_2$ 7% with NaOH 2.20%, $Na_2SiO_3$ 0.63% and EDTA 0.02%. The concentration of NaOH, $Na_2SiO_3$ and EDTA was correlated functional to the residual peroxide content of wastewater, pH value and electric conductivity of TMP fibers after bleaching treatment. The optimal bleaching conditions by controlling the addition amount of chemicals were positively contributed to the brightness stabilization and environmental load of TMP.

• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.123-129
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• 2000

We set up a loss measurement apparatus using cavity ring-down method to get the losses in mirror having a small absorption and scattering. The measured errors could be explained by the loss inhomogeneity of the position of the mirror included in the cavity, and we knew that the long~period measurement limit of apparatus is three days, the minimum error limit of Lhe term is 4 ppm, which were gotten by measuring the long-period and short-period decay time in both reference and test cavity. Also we determined the losses m various mirrors fabricated at our laboratory using the apparatus and we found that the losses in mirrors are quite different at their spatial positions. tions.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.304-304
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• 2011

We investigated the effect of different spin direction of anti-ferromagnetic layer on the magnetic properties of ferromagnetic layer in Fe-NiO and Fe-CoO bi-layer systems. For Fe-NiO system, we prepared the clean MgO(001) surface half-covered with 20 nm Ag films as a substrate for magnetic layers. Then we grew NiO wedge layers on the substrate, and added 8 monolayer(ML) Fe layers on the wedge layer. We examined magnetic properties of the bi-layer system using the surface magnetic optical Kerr effect(SMOKE) and X-ray magnetic linear dichroism(XMLD). From SMOKE measurement we observed the coercivity enhancement due to the set-up of anti-ferromagnetic order of NiO films in both of the Fe/NiO/MgO(001) and Fe/NiO/Ag/MgO(001) system. The most remarkable results in our observation is that the coercivity enhancement of Fe/NiO/Ag/MgO(001) is much larger than that of Fe/NiO/MgO(001). XMLD experiments confirmed the out-of-plane spin direction of NiO layers in Fe/NiO/MgO(001) and in-plane spin-direction of NiO layers in Fe/NiO/Ag/MgO(001), and we concluded that the origin of large enhancement of coercivity is due to the strong parallel coupling between Fe layers and NiO layers. We also confirmed that this strong parallel coupling maintained across the thin Ag layer inserted between Fe and NiO layers. For Fe-CoO system, we prepared Fe/CoO/Ag(001) and Fe/CoO/MnO(001) systems and observed much larger coercivity enhancement in Fe/CoO/Ag(001).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.89-96
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• 2005

This paper discusses the daytime atmospheric conditions and the possibility of daytime star detection with the purpose of practical use of the star sensor for daylight navigation. In order to estimate the daytime atmospheric data, we use the standard atmospheric model (LOWTRAN 7), from which atmospheric transmittance and radiance from background sky are calculated. Assuming the star sensor with an optical filter to reduce background radiation, different separation angles between the star sensor and the sun are set up to express the effect of the solar radiation. As considerations of field of view (FOV) of the star sensor, the variation of the sky background radiation and the star density of the detectable star are analyzed. In addition, the integration time to achieve a required signal-to-noise ratio and the number of the radiation-caused electrons of the charge coupled detector(CCD) working as the limit to daylight application of the star sensor are calculated.

• Journal of Biomedical Engineering Research
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• v.32 no.3
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• pp.185-190
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• 2011

The purpose of this study is to investigate the influence of organism vigor information solution(OVIS) on the animal cell growth and to set up a condition for cell culture. We investigated the reactions on the MG-63 and MCF-7 cell line in mixture culture media with various amount of REVIEW solution, which is an example among various OVIS. DMEM-HG was used as basic media. The concentration range of the mixture was limited from 0% to 15%. MTT assay is used for cell viability test. The cell was incubated for 14days and the MTT assay was performed on day 1, 3, 7, 10 and 14 throughout the experiment. We used the ELISA reader to measure the Optical Density(O.D) at 595 nm wavelength filter. MCF-7 was linearly proliferated according to culture time and concentrations of OVIS. On the other hand, MG-63 cells were measured the highest O.D value at 12%. The growth rates of both cells cultured in mixed culture media with OVIS are much higher than those in only basic media, DMEMHG, after 14days. It was confirmed that cell cultured at OVIS grows rapidly at certain period although cells showed a negative effect in initial stage.

• Journal of Korean Association for Spatial Structures
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• v.9 no.3
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• pp.67-74
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• 2009

Presently means of utilizing sensors such as Piezoelectric(PZT) Element for evaluating the affect of oscillator, strain gauge for analyzing physical changes and use of Fiber Bragg Grating(FBG) Sensor are widely practiced in the field. In this study, PZT and FBG sensors were used to tearing damage of cable systems in these sensors. Cable systems are a construction of elements carrying only tension and no compression or bending in membrane structure. But damage detection of cable systems by using existing safety diagnosis is difficult to detect the characteristic change of overall structural action. If cable snaps are occurred to cable release and tear in tension structures, these are set up a vibration. So, we used piezo-electric materials and result of experiment using this was compared with result of experiment using FBG sensors The purpose of this research is to develop of damage detection method of cable system in tensile stress.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.75-78
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• 2004

Various jet engines (Turbine engine family and RAM Jet engine) have been developed for high speed aircrafts. but their application to hypersonic flight is restricted by principle problems such as increase of total pressure loss and thermal stress. Therefore, the development of next generation propulsion system for hypersonic aircraft is a very important subject in the aerospace engineering field, SCRAM Jet engine based on a key technology, Supersonic Combustion. is supposed as the best choice for the hypersonic flight. Since Supersonic Combustion requires both rapid ignition and stable flame holding within supersonic air stream, much attention have to be given on the mixing state between air stream and fuel flow. However. the wider diffusion of fuel is expected with less total pressure loss in the supersonic air stream. So. in this study the direction of fuel injection is inclined 30 degree to downstream and the total pressure of jet is controlled for lower penetration height than thickness of boundary layer. Under these flow configuration both streams, fuel and supersonic air stream, would not mix enough. To spread fuel wider into supersonic air an aerodynamic force, baroclinic torque, is adopted. Baroclinic torque is generated by a spatial misalignment between pressure gradient (shock wave plane) and density gradient (mixing layer). A wedge is installed in downstream of injector orifice to induce an oblique shock. The schlieren optical visualization from side transparent wall and the total pressure measurement at exit cross section of combustor estimate how mixing is enhanced by the incidence of shock wave into supersonic boundary layer composed by fuel and air. In this study non-combustionable helium gas is injected with total pressure 0.66㎫ instead of flammable fuel to clarify mixing process. Mach number 1.8. total pressure O.5㎫, total temperature 288K are set up for supersonic air stream.