• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.560-565
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• 2003

M-doped (M=Al, Ni) ZnO thermoelectric materials were fully densified at low temperatures of 800∼1,000$^{\circ}C$ and their sintering characteristics and microstructural features were investigated. Electron microscopic analysis showed that the addition of NiO promoted tile formation of solid solution and caused actively grain growth. The addition of A1$_2$O$_3$ prevented the evaporation of pure ZnO at grain boundaries and suppressed the grain growth by the formation of secondary phase. In case of the addition of A1$_2$O$_3$ together with NiO, the specimen showed an excellent microstructure and also the SEM-EBSP (Electron Back-scattered Diffraction Pattern) analysis confirmed that it shows a superior grain boundary distribution to the others specimens. These microstructural characteristics induced by the addition of A1$_2$O$_3$ together with NiO may increase the electrical conductivity by the increase in carrier concentration and decrease the thermal conductivity by the phonon scattering effect and, consequently, improve the thermoelectric property.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.120-127
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• 2015

Morphological properties of dark banded rockfish (Sebastes inermis) were analysed to investigate its acoustic scattering characteristics. Total of 18 live samples was prepared for X-ray photos and collected morphological coordinates of their body and swim bladder shapes. Kirchhoff-ray mode model was used to calculate acoustic scattering pattern for broad-band frequency range. Inclination of swim bladder ranged from 17 to 30 and the averaged value was about $25.2^{\circ}$ (S.D.(standard deviation)=3.15). There were no any tendency of increase or decrease in volume and area ratio of swim bladder to fish body and ranged from 2.2 % to 4.43 % and 14.85 % to 21.31 %, respectively. The averaged value of volume and area ratio was 3.13 % (S.D.=0.52) and 17.6 % (S.D.=1.5). $b_{20}$ values were -69.01 for 38 kHz, -69.83 for 70 kHz, -70.17 for 120 kHz and -70.93 for 200 kHz, recpectively. Broadband acoustic patterns of dark banded rockfish for 20 ~ 200 kHz were similar among samples and they reflected size and morphological properties of fish species.

• The Journal of the Acoustical Society of Korea
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• v.7 no.4
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• pp.117-126
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• 1988

The pressure waves scattered by an infinite cylindrical cavity filled with air in a h0mogeneous medium have been calculated for the incident plane pressure waves. For ka = 1/2, 1, 2, 4, 10 and 20, the scattered pressure waves are plotted., where k is the wave number and a is the radius of the cylindrical hole. As an indicator of the directivity of the scattering pattern, we have defined the angle at which the magnitude of the scattered pressure wave decreases by a half(6 dB) with respect to that of the forward peak scattered pressure wave. This angle depends strongly on the values of ka and the distance r, and the angle can be used for the detection of the location and the size of the cavity in a homogeneous medium.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.147-151
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• 2000

Symbiotic stars, believed to be binary systems of a mass-losing giant and a white dwarf with an emission nebula, are known to exhibit very broad wings around Hex that extend to $\~10^3km\;s^{-1}$. The wing formation mechanism is not a settled matter and recently Lee (2000) proposed that Raman scattering of Ly$\beta$ by neutral hydrogen is responsible for the broad H$\alpha$ wings. In this model, it is predicted that. the Hex wings will be polarized depending on the geometric and kinematic distribution of the scatterers relative to the UV emission region. In this paper, we investigate the polarization of Hex wings in symbiotic stars. Noting that many symbiotic stars possess bipolar nebular morphology, we assume that the distribution of neutral scatterers follows the similar pattern with a receding velocity of several tens of km $s^{-1}$ that mimics the expansion of the neutral envelope of the nebula. It is found that the red wing is more strongly polarized than the blue and main part and that the polarization direction is along the equatorial plane. We obtain a typical degree of polarization $\~10$ percent, however, it varies depending on the detailed distribution of H I scatterers We conclude that spectropolarimetry will provide very important information on the origin of the Hex wings.

• Journal of the Korean Institute of Navigation
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• v.17 no.1
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• pp.61-78
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• 1993

Large offshore structure are to be considered for oil storage facilities , marine terminals, power plants, offshore airports, industrial complexes and recreational facilities. Some of them have already been constructed. Some of the envisioned structures will be of the artificial-island type, in which the bulk of structures may act as significant barriers to normal waves and the prediction of the wave intensity will be of importance for design of structure. The present study deals wave scattering problem combining reflection and diffraction of waves due to the shape of the impermeable rigid upright structure, subject to the excitation of a plane simple harmonic wave coming from infinity. In this study, a finite difference technique for the numerical solution is applied to the boundary integral equation obtained for wave potential. The numerical solution is verified with the analytic solution. The model is applied to various structures, such as the detached breakwater (3L${\times}$0.1L), bird-type breakwater(318L${\times}$0.17L), cylinder-type and crescent -type structure (2.89L${\times}$0.6L, 0.8L${\times}$0.26L).The result are presented in wave height amplification factors and wave height diagram. Also, the amplification factors across the structure or 1 or 2 wavelengths away from the structure are compared with each given case. From the numerical simulation for the various boundary types of structure, we could figure out the transformation pattern of waves and predict the waves and predict the wave intensity in the vicinity of large artificial structures.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1246-1249
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• 1994

Thin amorphous film of $a-Se_{75}Ge_{25}$ acts as a positive resist in ion beam lithography. Previously, we reported the optical characteristics of amorphous $Se_{75}Ge_{25}$ thin film by the low-energy ion beam exposure and presented analytically calculated values such as ion range, ion concentration and ion transmission coefficient, etc. As the calculated results of analytical calculation, the energy loss per unit distance by $Ga^+$ ion is about $10^3[keV/{\mu}m]$ and nearly constant for all energy range. Especially, the projected range and struggling for 80 [KeV] $Ga^+$ ion energy are 0.0425[${\mu}m$] and 0.020[${\mu}m$], respectively. Hear, we present the results of Monte-Carlo computer simulation of Ga ion scattering, exposure and development in $a-Se_{75}Ge_{25}$ resist film for focused ion beam(FIB) lithography. Monte-Carlo method is based on the simulation of individual particles through their successive collisions with resist atoms. By the summation of the scattering events occurring in a large number N(N>10000) of simulated trajectories within the resist, the distribution for the range parameters is obtained. Also, the deposited energy density and the development pattern by a Gaussian or a rectangular ion beam exposure can be obtained.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.57-62
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• 2002

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown TiO layers on a MgO(001) surface. The hetero-epitaxial TiO layer was deposited by thermal evaporation of titanium onto the MgO(001) surface and subsequent exposure to oxygen at 400℃. The well-ordered TiO structure was confirmed with the 1×1 RHEED pattern. TOF-ICISS results revealed that the TiO layer was formed at the on-top sites of the MgO(001) substrate and that the lateral lattice constant of TiO layer was the same as that of the MgO substrate. The surface of the deposited epitaxial TiO layer was smooth without the three dimensional islands.

• International Journal of Knowledge Content Development & Technology
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• v.12 no.2
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• pp.41-56
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• 2022

This research paper presents the use of different forms of literature by the PhD researchers of the Department of Political Science and the Department of Public Administration, Punjabi University, Patiala. It is assessed by analyzing the resources cited in the PhD theses awarded by Punjabi University, Patiala during 2015-2019. The different bibliographic forms of the references have been analyzed in order to find out the year-wise submission, average citations per thesis, authorship pattern, chronology, use of electronic resources, and format of citations in both the subjects under study. It has been found in this study that average citations per thesis in Political Science is more (200.53) than Public Administration (160.6). Books are most preferred form in both the subjects. Majority of the citations in both the subjects are from the period 2000-2009. Ranked list of journals for both the subjects have been prepared to identify core journals. The core journals in both the subjects are 9. Bradford Multipliers have been calculated and application of Bradford Law of Scattering has also been tested for both the subjects. It is expected that the present study will help librarians in selecting, retaining and cancelling the existing journals in Political Science and Public Administration.

• Polymer(Korea)
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• v.26 no.2
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• pp.227-236
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• 2002

The structure of pregel state in thermoreversible poly(vinylidene fluoride)(PVDF) /propylene carbonate(PC) system was investigated by laser light scattering. It was found that the PVDF chain did not exist as a separate chain even in a very dilute concentration(i.e. 100 times more dilute than the gel formation concentration) but as a large spherical aggregate with the radius of gyration $R_G$, of 232 nm and the effective hydrodynamic radius $R_H$= of 407 nm at $40^{\circ}C$. Based upon experimental results such as $R_H/R_G$=ratio of 1.75 and the pattern of scattering intensity with a minimum, a core-shell type sphere model was suggested as a structure of the aggregate. According to this model, the radius of core part was estimated as 215 nm, the shell thickness as 192 nm, and the ratio of monomer density of the shell part to that of the core part as about 0.075.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.749-756
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• 2003

Hydroacoustic and open-closing zooplankton net survey were conducted to understand the characteristics of the sound scattering layer (SSL) and to estimate the density of an euphausiid (Euphausia pacifica) in the SSL, in the northwestern part of the East China Sea. The survey was carried out during July 6-9 2002 at 8 sampling stations for zooplankton. The virtual echogram technique was used to identify E. pacifica from all acoustic scatters. Mean volume backscattering strength difference $(MVBS_{120kHz-38kHz})$ and target strength equation for E. pacifica were derived from the Distorted-wave Born Approximation (DWBA) model. Although vertical migration of the SSL is similar to the general pattern, dispersion at night shows some differences. Estimated mean density using acoustic data ranged from $20.4-221.4\;mg/m^3$ over the whole depth, and $87.1-553.5\;mg/m^3$ in the SSL. The density using the zooplankton net ranged from $0.2-362.4\;mg/m^3$ and was not related to net deploying method. The results from the acoustic and net survey suggest that E. pacifica might be an important zooplankton community in the northwestern part of the East China Sea.