• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.30-36
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• 1984

An ultrastructural study on the mature spermatoBoa oi Cloptorchis sineitsis was carried out. For this study, the liver cukes were collected from the livers of rabbits and rats artificially infected with the metacercariae obtained from the fresh water fish, Pseudorasbora parve. Six-month old worms were used. The collected liver fiukes were washed with 0.85% saline solution and then immediately moved to cold 2% glutaraldehyde buffered with 0.1M Millonig's phosphate buffier (pH 7.4) . The materials were dissected into appropriate pieces in the fixative about 30 minutes after beginning of the fixation. Two hours later the materials containing the seminal receptacle were rinsed several times with the buffier and were secondarily fixed with cold, bugeyed 1% osmium tetroxide(OsO4) for 2 hours. The fully mixed tissue blocks Ivere dehydrated in a series of graded concentrations of acetone and were embedded in Epon 812 mixture. Thin sections obtained from LKB-5 ultramicrotome were stained with uranyl acetate and Reynold's lead citrate. Observations of the sections were carried out with JEM-100CX II electron microscope, In general, the mature sperm was long thread-like form with a sickle-shaped head. According to the longitudinal sectioned view of the sperm tail, the nucleus seemed to be spirally coiled and run a little far along the tail. The acrosome was not observed. The cytoplasm of the tail was biflagellated as usual in trematodes. Unlike other platyhelminth spermatozoa, the sperm tail of Clenorchis sinensis showed the ${\ulcorner}9+2{\lrcorner}$ in the microtubular arrangement. The mitochondria with poorly developed cristae were observed throughout the middle piece. The middle piece of the tail showed dull ladder or triangular shapes with the two flagella at the bottom. But, the principal piece of the tail was slightly flattened cylindrical shape with two aagella within the cytoplasm. The end piece was uniflagellated. It was not clearly identised whether the end piece was subdivided into two by aagellum or the lengths of the two aagella were different. The glycogen granules were rich in the cytoplasm throughout the lenght of the spermatozoa. These granules might be the energy source for the movement of the spermatosoa.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.1
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• pp.1-11
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• 2002

In this paper, new simple method for the calculation of depletion region under complex geometry and general purpose numerical simulator that could handle this were developed and applied in the analysis of SCM with nanoscale tip, which is a promising tool for high resolution dopant profiling. Our simple depletion region seeking algorithm alternatively switches material of elements to align ionized element boundary with contour of zero potential. To prove the validity of our method we examined whether our results satisfy the definition of depletion region and compared those with known values of un junction and MOS structure. By modeling of capacitance based on the shape of depletion region and potential distribution, we could calculate the CV curve and dC/dV curve between silicon substrate and nanoscale SCM tip.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1606-1611
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• 2008

Recently, The diagnosis techniques of electric facilities are developed on live line. This paper describes the discharge characteristics of polymer insulator(EPDM A type). Keeping the facilities in good working order, the goal of this paper will provide the information to enable user to easily judge conditions of facilities on the spot. The performance of polymer insulator is assessed from the KS C IEC 60270 and CEA LWIWG-01(96)(Tracking Wheel Test). As the results, UV generation patterns of polymer insulator grow like a jellyfish shape follow the ramping voltage. Discharging UVs are detected at about 31.25% of breakdown voltage. Just then, dimension of UV image is about $0.84cm^{2}$. The dimension of max. UV image is about $297.4cm^{2}$ at $160kV(V_{bd})$. The position of UV generation due to surface discharge of polymer insulator is the center of insulator in the early, then moved the ground side and the last, UV image moved through the junction part of source side. Surface of aged polymer insulator is cracked and faded due to arc. UV absorption spectrum of polymer insulator are appeared the C-H bond of scissoring vib. at $1014cm^{-1}$ and C=O bond of recombination structure. Also, recombined UV absorption peak such as C-H, N-H, and O-H is detected at the $3321cm^{-1}$. Through the paper, there are inspection data which are the relations between surface discharge of polymer insulator and UV detecting image.

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.107-113
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• 2011

This paper describes a development of a loop filter design in a physical modeling of the plucked string instrument. The conventional method proposed by V$\"{a}$lim$\"{a}$ki cannot estimate right parameters if a sound has either very short sustain or no sustain. In order to overcome this drawback, we propose the use of the decay region and 5 to 20 harmonics of the sound in the estimation of loop filter parameters. The most appropriate filter coefficient is chosen by frequency signal to noise ratio. To verify the performance of the proposed method, the guitar, gayageum and geomungo were selected as the target because they have different shape, structure, and material of strings. Regardless of the duration of harmonics, the proposed method was able to estimate the loop filter parameters representing frequency-dependent damping of harmonics.

• Journal of the Korean institute of surface engineering
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• v.53 no.1
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• pp.9-14
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• 2020

CuS (copper sulfide) thin films having the same thickness of 100nm were deposited on the glass substrates using by radio frequency (RF) magnetron sputtering method. RF powers were applied as a process variable for the growth of CuS thin films. The structural and optical properties of CuS thin films deposited under different power conditions (40-100W) were studied. XRD analysis revealed that all CuS thin films had hexagonal crystal structure with the preferential growth of (110) planes. As the sputtering power increased, the relative intensity of the peak with respect to the (110) planes decreased. The peaks of the two bands (264cm^-1 and 474cm^-1) indicated in the Raman spectrum exactly matched the typical spectral values of the covellite (CuS). The size and shape of the grains constituting the surface of the CuS thin films deposited under the power condition ranging from 40W to 80W hardly changed. However, the spacing between crystal grains tended to increase in proportion to the increase in sputtering power. The maximum transmittance of CuS thin films grown at 40W to 80W ranged from 50 % to 51 % based on 580nm wavelength, and showed a relatively small decrease of 48% at 100W. The band gap energy of the CuS thin films decreased from 2.62eV (at 40W) to 2.56eV (at 100W) as the sputtering power increased.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.698-702
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• 2000

The characteristics of optical absorption in $Al_{0.24}Ga_{0.76}As/GaAs$ multi-quantum wells(MQWs) structure were investigated by using the surface photovoltage(SPV). The Spy features near 1.42 eV showed two overlapping signals. By chemical etching, we found associated with the GaAs substrate and the GaAs cap layer. The Al composition(x=24 %) was determined by Kuech's composition formula. In order to identify the transition energies. the experimentally observed energies were compared with results of the envelope function approximation for a rectangular quantum wells An amplitude variation of the relative Spy intensity from the GaAs substrate, llH, and llL was observed at different light intensities. A variation in the SPY line shape of the transition energies were observed with decreasing tempera­t ture.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.159-159
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• 2011

Among the semiconductor ternary compounds in the I-III-$VI_2$ series, $CulnS_2$ ($CulnSe_2$) are one of the promising materials for photovoltaic applications because of the suitability of their electrical and optical properties. The $CuInS_2$ thin film is one of I-III-$VI_2$ type semiconductors, which crystallizes in the chalcopyrite structure. Its direct band gap of 1.5 eV, high absorption coefficient and environmental viewpoint that $CuInS_2$ does not contain any toxic constituents make it suitable for terrestrial photovoltaic applications. A variety of techniques have been applied to deposit $CuInS_2$ thin films, such as single/double source evaporation, coevaporation, rf sputtering, chemical vapor deposition and chemical spray pyrolysis. This is the first report that $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) technique which is a novel and attractive method because thin films with high deposition rate can be grown at very low cost. In this study, $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) method which employs a nozzle expansion. The mixed fluid is expanded through the nozzle into the chamber evacuated in a lower pressure to deposit $CuInS_2$ films on Mo coated glass substrate. In this AJD system, the characteristics of $CuInS_2$ films are dependent on various deposition parameters, such as compositional ratio of precursor solution, flow rate of carrier gas, stagnation pressure, substrate temperature, nozzle shape, nozzle size and chamber pressure, etc. In this report, $CuInS_2$ thin films are deposited using the deposition parameters such as the compositional ratio of the precursor solution and the substrate temperature. The deposited $CuInS_2$ thin films will be analyzed in terms of deposition rate, crystal structure, and optical properties.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.380-387
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• 2015

A lead slowing-down spectrometer (LSDS) system is a promising nondestructive assay technique that enables a quantitative measurement of the isotopic contents of major fissile isotopes in spent nuclear fuel and its pyroprocessing counterparts, such as $^{235}U$, $^{239}Pu$, $^{241}Pu$, and, potentially, minor actinides. The LSDS system currently under development at the Korea Atomic Energy Research Institute (Daejeon, Korea) is planned to utilize a high-flux ($>10^{12}n/cm^2{\cdot}s$) neutron source comprised of a high-energy (30 MeV)/high-current (~2 A) electron beam and a heavy metal target, which results in a very intense and complex radiation field for the facility, thus demanding structural shielding to guarantee the safety. Optimization of the structural shielding design was conducted using MCNPX for neutron dose rate evaluation of several representative hypothetical designs. In order to satisfy the construction cost and neutron attenuation capability of the facility, while simultaneously achieving the aimed dose rate limit (< $0.06{\mu}Sv/h$), a few shielding materials [high-density polyethylene (HDPE)eBorax, $B_4C$, and $Li_2CO_3$] were considered for the main neutron absorber layer, which is encapsulated within the double-sided concrete wall. The MCNP simulation indicated that HDPE-Borax is the most efficient among the aforementioned candidate materials, and the combined thickness of the shielding layers should exceed 100 cm to satisfy the dose limit on the outside surface of the shielding wall of the facility when limiting the thickness of the HDPE-Borax intermediate layer to below 5 cm. However, the shielding wall must include the instrumentation and installation holes for the LSDS system. The radiation leakage through the holes was substantially mitigated by adopting a zigzag-shape with concrete covers on both sides. The suggested optimized design of the shielding structure satisfies the dose rate limit and can be used for the construction of a facility in the near future.

• Korean journal of food and cookery science
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• v.21 no.6 s.90
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• pp.942-949
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• 2005

To improve the textural properties and stabilize the structure and gel matrix of non-waxy rice starch gels, non-waxy rice starch/gum mixture gels were prepared from various food gums, gum arabic, guar, algin, deacyl gellan, xanthan and gellan gums. The morphological and textural properties and freeze-thaw stability of their gels were compared. Rice starch/gum mixture gels with various gums formed a more homogeneous gel matrix with smaller particle size than rice starch gel without Em, but the trends differed depending on the gum types. The textural properties of rice starch/gum mixture gels were changed with the gum types. The shape of the rice starch/gum mixture gel matrix was desirable when mixed with gellan and algin. The textural properties of gels hardened in the rice starch/algin mixture gel and softened in the rice starch/algin mixture gel. The rice starch gels showed V-type crystallinity by x-ray diffractometer, but the peak at $2\theta$ = $20^{o}$ was decreased with increasing gum addition. The freeze-thaw stability increased with increasing gum addition. Gellan and algin were especially effective.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.508-514
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• 2022

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO₃ nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO₃ particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO₃ particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency.