• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.2 s.302
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• pp.49-58
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• 2005

A new soft switching three-phase PWM rectifier with simple circuit configuration and high efficiency has been developed. The proposed circuit is a kind of the auxiliary resonant commutated Pole(ARCP)converter The conventional ARCP converter requires three-auxiliary reactors and six-auxiliary switches for the soft switching auxiliary circuit and for these switching elements, a gate drive circuit and a control circuit are required, resulting in high part as a disadvantage. In the main circuit proposed in this paper, the auxiliary soft switching circuit is composed of two-auxiliary reactors, two-auxiliary switches and several diodes. In addition, common use of the PWM control circuit for two-switches will make the control circuit of the auxiliary switches simple. By means of function of the soft switching auxiliary circuit, the main switching element performs zero voltage switching operation and the auxiliary switches perform the zero current switching. In this paper, the circuit configuration and the operational analysis of the proposed circuit are described at first and then, experimental results will be reported. By using a prototype with 5[kW] capacity, the conversion efficiency of maximum $98.8[\%]$ and the power factor of $99[\%]$ or higher were obtained.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.2
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• pp.58-67
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• 1995

The paper describes the variation of magnetic fields caused by the operation of induction motors. The measuring system consists of the self-integrating magnetic field sensor, amplifier, and active integrator. From the calibration experiments, the frequency bandwidth of the magnetic field measuring system ranges from 20[Hz] to 300[kHz] and sensitivity is 0.234(mV/$\mu\textrm{T}$]. The magnetic fields generated under steady state and starting operations of duction motor are recorded by the proposed measuring system, and the fast Fourier transformation(FFT) of the measured data is performed to analyze the harmonic components. A single pulsed magnetic field is strongly caused by direct starting the induction motor, and its peak value is greater than 5 times as compared with the steady state value. The long transient duration and high intensity originates from the large inductance and dynamic characteristic of the induction motor, During the steady state operation of induction motor, subharmonics of magnetic field components, which depend on the pole number of induction motor, are observed. The lower order power-line harmonics can be inferred from the voltage flicker and current ripple which are derived from the torque fluctuation of induction motor. In the case of the induction motor drived by inverter, the harmonics of magnetic field are much more than those caused by direct starting method and are found generally to increase with decreasing the driving frequency.

• Resources Recycling
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• v.11 no.6
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• pp.3-11
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• 2002

Recently, waste printed circuit board (PCB) has significantly increased in its amount due to the rapid development of electronic industries. Since several kinds of noxious materials and also valuable metals are contained in it, the waste PCB is in an urgent need of recycling for the dual purposes for the prevention of environmental pollution and recovery of valuable resources. Also, the catalyst which equipped in the exhaust pipes of automobiles to reduce emission of air pollutants contains precious met-als so that their recovery from the waste auto-catalysts is required. In this study, the recovery of valuable metals from waste PCB and auto-catalyst by arc furnace melting process has been investigated, which is known to be very stable and suitable f3r less production of pollutants due to its high operating temperature. The effect of the kind of flux on the recovery of precious metals was examined by using quicklime, converter slag, and copper slag as the flux. In addition, the influence of direct and alternating current and the applying direction of direct current has been investigated. It was observed that using converter or copper slag as a flux was more desirable for a higher efficiency in the precious metal recovery compared with quicklime. For the effect of current, application of direct current taking the bottom as a negative pole generally showed a better efficiency for the extraction of valuable metals from waste PCB, which was also observed for the case of waste auto-catalyst. The average recovery of precious metals from both wastes by arc furnace melting process was very high, which was up to in the range of 95～97%.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.902-909
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• 1995

Detection limit as well as calibration curves on organophosphorus pesticide(dimethoate, diazinon, parathion-methyl, fenitrothion, malathion) and BHCs were measured for evaluation of utility on qualitative or quantitative analysis of pesticides with ion Trap mass spectrometer and quadrupole mass spectrometer. As ionization source, EI and CI were adopted for qualitative analysis of pesticides by comparison of each fragmentation pattern. At the same time, the utility as trace analysis techniques through scan or selected ion monitoring(SIM) mode was evaluated. With ion trap for all pesticides, detection limit(DL, 1 ${\mu}L$ injection) on scan mode was ranged 0.008∼0.225 ng at signal to noise ratio 3. With quadrupole DL on scan mode was ranged 0.23∼3.1 ng over 0.032∼0.68 ng on SIM mode. The calibration curve with ion trap generated good linearity over 0.99 as correlation coefficient. As clean up procedure, Bio Beads S-X3 was used for the separation of oils from five organophosphorous pesticides in flour extractant showing more than 80% as recovery at most cases. In case of BHCs in jinseng with Florisil column, the recovery of pesticides has been 60% to 90%.

• Korean Journal of Biological Psychiatry
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• v.14 no.2
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• pp.129-141
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• 2007

Objectives : Empathy has been conceptualized as the ability of emotional resonance and perspective-taking. Emotional awareness has been proposed as the basis of empathy. In this study we examined the relationship between empathy and mood awareness and their neural correlates in resting-state activity in normal controls and patients with schizophrenia. Methods : Empathy and mood awareness scale scores were compared between 29 patients with schizophrenia and 21 normal controls by voxel-based t-tests and voxel-based correlation analyses of resting-state $^{18}F$-FDG PET images. Results : Empathy and mood labeling scale scores were significantly decreased in schizophrenic patients. Mood monitoring was positively correlated with empathy score in normal controls, but not in schizophrenic patients. In normal controls, empathy was positively correlated with resting-state activities in the intraparietal sulcus and mood monitoring was positively correlated with the temporal pole, frontopolar cortex, inferior temporal gyrus, entorhinal cortex and the subgenual prefrontal cortex resting activities. The orbitofrontal cortex resting activity was positively correlated with mood monitoring-related subgenual prefrontal cortex activity in the normal controls. Patients with schizophrenia showed decreased orbitofrontal resting activity and loss of its correlations with mood monitoring-related regional activities. Conclusion : This study showed that alteration in the resting-state activity in schizophrenia may reflect dysfunctional empathy and distorted characteristic of emotional awareness. However, the resting-state activity may not reflect the relationship between emotional awareness and empathy.

• Korean Journal of Plant Taxonomy
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• v.38 no.2
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• pp.163-177
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• 2008

Pollen grains of 17 taxa (14 species with two additional subspecies and one variety) of genera Patrinia Juss. and Nardostachys DC. in tribe Patrinieae (Valerianaceae) were studied using light microscope, scanning electron microscope, and transmission electron microscope. Pollen grains are medium ($37.41{\times}43.60{\mu}m$ - $45.65{\times}48.50{\mu}m$) to large ($54.88{\times}59.41{\mu}m$ - $61.70{\times}71.00{\mu}m$) in size, tricolpate (rarely tetracolpate) with the characteristic halo surrounding the aperture. In equatorial view, the pollen is oblate to subprolate, and in polar view, it is mostly circular or rarely 3-lobed. Two major pollen types are recognized on the basis of exine sculpturing patterns; Type I: Exine is composed of echinae together with sparse or dense microechinae, and verrucae shallow or rarely absent (Nardostachys and sections Paleopatrinia, and Monanadropatrinia of Patirinia). - Type II: Exine is composed of massive echinae together with dense microechinae, and prominent verrucae (section Centrotrinia of Patrinia). In TEM sections, columellae are extended from the footlayer into verrucae, and exine thickness is uniform at the pole and equator. Additionally, the infrageneric classification systems of the Patrinieae were evaluated on the basis of the present data.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.3
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• pp.301-309
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• 1997

The objective of this study was to determine the microtubule assembly and chromatin configuration during the first cell cycle in bovine oocytes following injection of spermatozoon, sperm head and tail. The microtubule and chromatin configuration was imaged with fluorescent labeled monoclonal ${\alpha}$-tubulin antibody and propidium iodide under laser scanning confocal microscope. Microtubule and chromatin dynamics in bovine oocytes following intracytoplasmic sperm injection (ICSI) were not different from those observed during in vitro fertilization (IVF). Following ICSI, the microtubular aster was observed around sperm midpiece. During pronuclear formation, the sperm aster was enlarged and seen around male and female pronuclei. At mitotic metaphase, the microtubular spindle assemble astral poles and chromosomes were aligned on the spindle equator. At mitosis, asters were concentrated to each spindle pole and they filled the cytoplasm. After injection of the isolated sperm head, the microtubular aster was not seen around sperm head in any cases (0/18). Instead, microtubules were organized from the cytoplasm, which filled the whole cytoplasm during pronuclear apposition. These microtubules seem to move male and female pronuclei. These results suggest that isolated sperm head can develop into normal pronucleus in mature bovine oocytes, and competent to participate syngamy with the ootid chromatin. The functional microtubules following isolated sperm head injection in bovine oocytes appeared to be organized solely from maternal stores.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.819-826
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• 2002

In this paper, the performance of Au / $Ba_{0.5}Sr_{0.5}TiO_3$ (BST) / Magnesium oxide (MgO) two-layered electrically tunable band-pass Filters (BPFs) is demonstrated. The devices consist of microstrip, coplanar waveguide (CPW), and conductor-backed coplanar waveguide (CBCPW) structures. These BST thin film band-pass filters have been designed by the 2.5 D field simulator, IE3D, Zeland Inc., and fabricated by thin film process. The simulation results, using the 2-pole microstrip, CPW, and CBCPW band-pass filters, show the center frequencies of 5.89 GHz, 5.88 GHz, and 5.69 GHz, and the corresponding insertion losses are 2.67 dB, 1.14 dB, and 1.60 dB, with 3 %, 9 %, and 7 % bandwidth, respectively. The measurement results show the center frequencies of 6.4 GHz, 6.14 GHz, and 6.04 GHz, and their corresponding insertion losses are 6 dB, 4.41 dB, and 5.41 dB, respectively, without any bias voltage. With the bias voltage of 40 V, the center frequencies for the band-pass filters are measured to be 6.61 GHz, 6.31 GHz, and 6.21 GHz, and their insertion losses are observed to be 7.33 dB, 5.83 dB, and 6.83 dB, respectively. From the experiment, the tuning range for the band-pass filters are determined as about 3 % ~ 8 %.

• Journal of Conservation Science
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• v.6 no.1 s.7
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• pp.31-60
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• 1997

Stone-cultural-properties, distributed in Naju, Hwasun and a part of Jangheung, have been investigated and studied on the characteristics, rock weathering and phases in the geological and conservational points of view. The properities involve pagoda and twelve stupas, four stone-buddha, three stone monuments, two stone-lantern, four stone-Jangseung, one and flag-pole. The rocks used are mainly pebble-bearing tuffaceous rocks of the Cretaceous age which are widely distributed in the area. However, granites are also used in some properties. These rocks are strongly influenced by weathering and pervasive moss. The mottled rock surfaces in some properties are in colors due to pervasive moss different. Parts of some cultural properties are broken which results in structurally unstable. Cultural properties in the area are relatively well conserved at the earth consolidated by ramming and by iron fence. However some cultural properties are partly repaired by using other hinds of rock phases which results in different colors in weathered rock surface. For conservation, rock phases, weathered surface colors, and relationships with original parts must be scientifically considered in repairment forward.

• Applied Microscopy
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• v.29 no.2
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• pp.177-187
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• 1999

Ultrastructure of gametes in the three-spine stickleback, Gasterosteus aculeatus aculeatus was observed, utilizing light, scanning and transmission electron microscopes. The egg of three-spine stickleback is spherical and demersal type. The eggs are highly adhesived to each other but not to substrates. There are many oil droplets in vitelline membrane. The outer surface of egg envelope is arranged by mushroom-like structures and pore canals. The egg have a micropyle, sperm entry site, in the area of the animal pole. The egg envelope consists of three layers, an outer layer with high electron density, a middle layer consisting two layers and an inner layer consisting of 16 to 20 layers. In the fertilized egg envelope, the molecular weights of these components ranged from 14 kDa to 205 kDa. The molecular weights of nam protein bands are 19.4 kDa, 36.7 KDa, 39.4 kDa, 42.9 kDa, 46.1 kDa and 53.0 kDa. The head of spermatozoa is spherical shape and the acrosome is absent. The mitochondria in midpiece are arranged from one to three layers and separated from the axoneme by the cytoplasmic canal. The tail has two lateral fins and the axoneme is of the 9+2 structure.