• The Korean Journal of Malacology
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• v.28 no.2
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• pp.165-174
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• 2012

The morphology and taxonomic values of the sperm in male Chlamys (Swiftopecten) swiftii were investigated by transmission electron microscope observations. The morphologies and ultrastructures of the sperm nucleus and the acrosome of this species are the vase type and long cone shape, respectively. Spermatozoa are approximately $45-50{\mu}m$ long including a sperm nucleus (approximately $2.60{\mu}m$ long), an acrosome (about $0.63{\mu}m$ long), and a tail flagellum (approximately $44-47{\mu}m$ in long). The axoneme of the sperm tail shows a 9+2 structure. In this study, the right and left basal rings in the acrosomal vesicle of this species show electron opaque part (region), and also the anterior apex part of the acrosomal vesicle shows electron opaque part (region). These characteristics of the acrosomal vesicle were found in Pectinidae and other several families in subclass Pteriomorphia. The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appear in most species in Pectinidae in subclass Pteriomorphia. In addition, the satellite fibres are found near the distal centriole of this species, as have been reported in other species of Pectinidae in subclass Pteriomorphia. Accordingly, structutral characteristics which are found in the acrosomal vesicle, four mitochondria in the sperm midpiece and the appearance of the satellite fibers near the distal centriole of C. (S.) swiftii in Pectinidae (subclass Pteriomorphia), can be employed for phylogenetic and taxonomic analyses as taxonomic key or a significant tool.

• Tribology and Lubricants
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• v.25 no.5
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• pp.311-317
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• 2009

To satisfy the more severe emission regulation and the demand of higher fuel economy in near future, the combustion pressure and power output of engines is going to be higher. In order to get the reduction of engine emission and the higher power, it is needed the reduction of the tension and width of ring pack. The lower tension ring and the thinner width ring can bring not only the friction reduction between the ring and liner during engine running, but also the adjustment of the blow-by gas and oil consumption by changing in the pressure in the crevice volume and the axial motion of rings togethe with the adjustment of the inter-ring crevice volumes. In this study, by using a developed basic computer proglram that predicts the blow-by gas and oil consumption of engines, it is to be examined how satisfying the level of the blow-by gas and oil consumption as being installed the piston ring pack with thinner width ring and lower tension ring.

• Journal of environmental and Sanitary engineering
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• v.17 no.2
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• pp.79-84
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• 2002

This study investigated possibility of the nitrification and denitrification in one counter-current column with the growth of biofilm attached to its media. This experiment was performed through use of the lab scale reactor composed of the column and settler. The column used was packed with the small size of plastic rings called PALL($1.5{\times}1.5{\;}cm$) with a cylindrical shape. Synthetic wastewater was used in the experiment. The loading rates of carbon (C) and total nitrogen (TN) furnished to the reactor were 0.23 to 1.0 kg COD/m3.d and 0.023 to 1.0 kg N/m3.d, respectively. Major factors controlling the removal efficiencies of COD and TN were the different air flux and volumetric loading rates of COD and TN. The experimental results obtained from this study demonstrated that the removal efficiencies of COD ranged from 90 to 95% and those of TN were from 80 to 83% under the N loading rate of 0.035 and $0.058{\;}kg{\;}N/m^3{\cdot}d$, respectively. The patterns of TN removed were distinctively different on the limit of 50cm of column in depth. This indicated that the nitrification and denitrification occurred near the surface zone of and inside the biofilm respectively, upto the 50cm of the column in depth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.543-549
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• 2011

An underwater speaker was developed for use as an acoustic deterrent device that transmits acoustic energy through the water omnidirectionally over a broadband frequency range to eliminate marine mammal attacks and to prevent physical damage to the inshore and coastal fishing grounds of Korea. The underwater speaker was constructed of two vibration caps machined from 6061-T6 aluminum alloy and a stack of PZ 26 piezoelectric ceramic rings (Ferroperm Piezoceramics A/S) connected mechanically in series and electrically in parallel. The performance characteristics of the underwater speaker were measured and analyzed in an experimental water tank of $5\;m{\times}5\;m{\times}6\;m$. The peak transmitting voltage response (TVR) was measured at 11.16 kHz with 163.45 dB re $1\;{\mu}Pa$/V at 1m. The underwater speaker showed a near omnidirectional beam pattern at the peak TVR resonance frequency. The usable frequency range was 4-25 kHz with a lower TVR limit of approximately 140 dB. We conclude that this underwater speaker could be satisfactorily used as an acoustic deterrent device against marine mammals, particularly the bottlenose dolphin, to protect catches and fishing grounds as well as the mammals themselves, for example, by keeping them away from fishing gear and/or vessels.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.419-422
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• 2002

We have studied dielectric properties in the smectic phases of 4-(6-ethoxy-1-trifluoromethyl-hexyloxycarbonyl)-phenyl-4-Nonyloxybiphenyl-4-carboxylat ( TFMEOHPNBC ) having fluorine attached to one of its benzene rings. Homogeneous and homeotropic 1.5 and 5${\mu}m$ thick test cells were prepared to analyze molecular dynamic property. We measured capacitance as a function of temperature in the frequency range between 20 Hz and 100 kHz by using HP4284A LCR meter. We observed that the homogeneous cell has high dielectric constant causing dipole moment in smectic $C^{\ast}$ phase, but we can see the dipole moments are canceled out in antiferroelectric phase. It is found that there are two kind of the relaxation director fluctuation below 100 kHz. The first is ionic or space charge contribution below 10 Hz, and the second is Goldstone mode near 1-2 kHz. We will discuss molecular dynamics in smectic phase from extra information such as x-ray and electrooptic data.

• Korean Journal of Materials Research
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• v.24 no.7
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• pp.344-350
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• 2014

Metal films (i.e., Ti, Al and SUH310S) were prepared in a magnetron sputtering apparatus, and their cross-sectional structures were investigated using scanning electron microscopy. The apparatus used consisted of a cylindrical metal target which was electrically grounded, and two anode rings attached to the top and to the bottom of the target. A wire was placed along the center-line of the cylindrical target to provide a substrate. When the electrical potential of the substrate was varied, the metal-film formation rate depended on both the discharge voltage and the electrical potential of the substrate. As we made the magnetic field stronger, the plasma which appeared near the target collected on the plasma wall surface and thereby decreased the bias current. The bias current on the conducting wire was different from that for cation collection. The bias current decreased because the collection of cations decreased when we increased the magnetic-coil current. When the substrate was electrically isolated, the films deposited showed a slightly coarse columnar structure with thin voids between adjacent columns. In contrast, in the case of the grounded substrate, the deposited film did not show any clear columns but instead, showed a densely-packed granular structure. No peeling region was observed between the film and substrate, indicating good adhesion.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.2
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• pp.87-91
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• 2013

The crystal structure of partially dehydrated fully $Zn^{2+}$-exchanged zeolite Y was determined by X-ray diffraction techniques in the cubic space group $Fd\bar{3}m$ at 294(1) K and refined to the final error indices $R_1/wR_2$ = 0.035/0.119 for $|Zn_{35.5}(H_2O)_{13}|[Si_{121}Al_{71}O_{384}]$-FAU. About 35.5 $Zn^{2+}$ ions per unit cell are found at six distinct positions; sites I, I', a second I', II', II, and a second II. In sodalite cavities, the 11 water molecules coordinate to Zn(I'b) and/or Zn(II') ions; each of two $H_2O$ bonds to a Zn(IIb) in supercages. Two different $Zn^{2+}$ positions near 6-oxygen ring are due to their Si-Al ordering in tetrahedral site by Si/Al ratio leading to the different kinds of 6-rings.

• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.303-308
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• 1988

Four crystal structures of dehydrated Ag(I) and Tl(I) exchanged zeolite A, $Ag_{12-x}Tl_x$-A, x = 2, 3, 4, and 5, have been determined by single-crystal x-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at $21(1)^{\circ}C$. All crystals were ion exchanged in flowing streams of mixed $AgNO_3\;and\;TlNO_3$ aqueous solution, followed by dehydration at $350^{\circ}C$ and $2{\times}10^{-6}$ Torr for 2 days. In all of these structures, one-sixth of the sodalite units contain octahedral hexasilver clusters at their centers and eight $Ag^+$ ions are found on threefold axes, each nearly at the center of a 6-oxygen ring. The hexasilver cluster is stabilized by coordination to eight $Ag^+$ ions. The Ag-Ag distance in the cluster, ca. 2.92 ${\AA}$, is near the 2.89 ${\AA}$ bond length in silver metal. The remaining five-sixths of the sodalite units are empty of silver species. The first three $Tl^+$ ions per unit cell preferentially associate with 8-oxygen rings, and additional $Tl^+$ ions, if present, are found on threefold axes in the large cavity.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.23-32
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• 2008

Anatomical and physical characteristics of seven cultivars of chestnut wood (Castanea crenata Sieb. et Zucc.), Tanzawa, Ibuki, Mansung, Arima, Ginyose, Tsukuba, and Riheiguri, were investigated to obtain some valuable information for their possibilities to be used for high quality furnitures and woodcrafts. Solitary pore and figured-porous or ring-porous wood types were observed in wide growth rings, and ring-porous in narrow growth rings. Procumbent type was prevalent in ray cells although upright and square types were scarcely existed. Uniseriate, biseriate, and multiseriate rays were observed in tangential section. Uniseriate ray was abundant near the pith, and biseriate and multiseriate rays were frequently existed near the bark. The occurrence rate of biseriate and multiseriate rays was significantly high in Tanzawa, Ibuki, Mansung and Tsukuba, but was somewhat low in Arima, Ginyose and Riheiguri. The inner region showed larger vessel diameter, more vessel number, fewer ray number and higher ray height than the outer region. Growth-ring width in inner region was larger than that in outer region. Growth-rings in inner region of Mansung and Arima were wide while that of Ibuki was narrow. Outer region in all cultivars showed higher latewood percentage than inner region. Especially, Mansung and Tsukuba showed significantly high latewood percentage in their outer region. Green moisture content and density of heartwood were higher than those of sapwood. Tsukuba and Riheiguri had higher green moisture content, and Ibuki and Riheiguri had higher green density than the other chestnut cultivars.

• Journal of radiological science and technology
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• v.29 no.3
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• pp.147-155
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• 2006

The crystal structures of fully dehydrated $K_3Na_8H-A(R_1=0.0478,\;R_2=0.0458\;and\;a=12.257(1){\AA})$ have been studied by single-crystal x-ray diffraction methods in the cubic space group. Pm3m in order to understand the structure of the zeolite as a gas storage medium and the mechanisms based on the encapsulation and decapsulation processes of gas molecules. In the crystal structures of dehydrated $K_3Na_8H-A$, three $K^+$ ions per unit cell are located on the 8-oxygen ring(0.0, 0.4531, 0.4531) and eight $Na^+$ ions per unit cell are located near the centers of 6-oxygen rings. Each $K^+$ ions on the 8-ring is $2.87(2){\AA}$ and $2.79(1){\AA}$ away from two kinds of framework oxygen atoms. These values are more realistic than previously known values in $K_{12}Na-A$. The exact positions of $K^+$ ions are ca. $0.8{\AA}$ away from the centers of the 8-rings which are previously reported as the preferred location of $K^+$ ions. Because the zeolites frameworks are stabilized as the results, more effective controls of gas molecules at encapsulation, decapsulation, and storage are achieved. Additionally, the available storage volumes are also maximized and more volume of gases can be stored in the materials. Therefore, oxygen storage bottles in hospital can be minimized and portable oxygen bottles for patients in emergency can be developed by using the materials.