• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.255-261
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• 2002

Recently, traction motors in trains are supplied with single phase a.c. power. After this power is converted to d.c. power, it is inverted to three phase power to operate traction motors. As going through the process of the conversion, harmonic current is generated in train. The method of conventional analysis on harmonics, studied by RTRI, is modeled with equivalent circuit of ac AT-fed electric railroad system using by the distributed constant circuit. However, this circuit as two-port network model has some difference in comparison with real system. The reason why the conventional method is different from the real system is that the conventional method dose not include three conductor groups, that is catenary, rail, and feeder, and admittance between the conductors for line capacitance. Therefore, this method has a little error. This paper proposes new method to more effectively estimate Harmonic current. In this method, numerous components in electric railway are categorized and each component is defined as a four- port network model. The equivalent circuit for the entire power supply system is also described into a four-port network model with connections of these components. In order to evaluate the efficiency and the accuracy of a proposed method, it is compared with values measured in Kyung-Bu high speed line and ones calculated by the conventional method.

• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.657-663
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• 1996

The API STAPH system was compared with conventional methods for identification of 214 strains of Staphylococcus hyicus subsp. hyicus isolated from cases of exudative epidermitis in piglets, skin of healthy pigs, skin of healthy chickens and bovine intramammary infections, and biochemical characteristics among the swine, avian and bovine strains were also compared. All of the swine and bovine strains produced acid within 24 hours from fructose, lactose and trehalose by conventional methods, but some of the avian strains showed a delayed positive reaction in these carbohydrates. These delayed positive strains in conventional methods gave usually negative results for them in the API STAPH system. With the API STAPH system, eighteen different profile numbers were encountered in 214 strains of swine, avian and bovine origin. The swine and bovine strains, respectively, were distributed among 4 profiles, while the avian strains were distributed among 17 profiles. The profile number observed most frequently in the strains of each animal species was uniformly 6 516 153. By conventional methods, approximately 96% of the swine strains were positive for ${\beta}$-glucuronidase, but not in any strains from chickens and cattle. For hyaluronidase production determined by degradation of sodium hyaluronidate in a solid culture medium, all the swine and bovine strains were positive, but only 37.5% of the avian strains were positive for it. From these findings, there were differences in the production of extracellular active substances between swine strains of Staphylococcus hyicus subsp. hyicus and those isolated from chickens and cattle.

• Journal of Power Electronics
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• v.5 no.3
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• pp.233-239
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• 2005

In this paper, a new conceptual circuit configuration of a 3-phase voltage source, soft switching AC-DC-AC converter using an IGBT module, which has one ARCPL circuit and one ARDCL circuit, is presented. In actuality, the ARCPL circuit is applied in the 3-phase voltage source rectifier side, and the ARDCL circuit is in the inverter side. And more, each power semiconductor device has a novel clamp snubber circuit, which can save the power semiconductor device from voltage and current across each power device. The proposed soft switching circuits have only two active power semiconductor devices. These ARCPL and ARDCL circuits consist of fewer parts than the conventional soft switching circuit. Furthermore, the proposed 3-phase voltage source soft switching AC-DC-AC power conversion system needs no additional sensor for complete soft switching as compared with the conventional 3-phase voltage source AC-DC-AC power conversion system. In addition to this, these soft switching circuits operate only once in one sampling term. Therefore, the power conversion efficiency of the proposed AC-DC-AC converter system will get higher than a conventional soft switching converter system because of the reduced ARCPL and ARDCL circuit losses. The operation timing and terms for ARDCL and ARCPL circuits are calculated and controlled by the smoothing DC capacitor voltage and the output AC current. Using this control, the loss of the soft switching circuits are reduced owing to reduced resonant inductor current in ARCPL and ARDCL circuits as compared with the conventional controlled soft switching power conversion system. The operating performances of proposed soft switching AC-DC-AC converter treated here are evaluated on the basis of experimental results in a 50kVA setup in this paper. As a result of experiment on the 50kVA system, it was confirmed that the proposed circuit could reduce conduction noise below 10 MHz and improve the conversion efficiency from 88. 5% to 90.5%, when compared with the hard switching circuit.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.34.1-34.7
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• 2020

Objectives: This study evaluated by using micro-computed tomography (micro-CT) the filling ability and sealer apical extrusion promoted by a new Sealer Injection System (SIS; Angelus) with side openings needle, in comparison with the conventional injection system, associated with a new ready-to-use calcium silicate-based sealer (Bio-C Sealer). Materials and Methods: Acrylic resin models containing a main curved artificial canal and 3 simulated lateral canals in apical, middle and cervical thirds were used. The main root canals were prepared using a rotary system up to size 35.05. The canals were filled with Bio-C sealer by using a single cone technique and the conventional delivery system or SIS. Samples were scanned in micro-CT. The percentage of voids throughout the entire extension of the main root canal and in each third of the lateral canals, besides the apical extrusion of the sealer was calculated. Data were submitted to t-test (p < 0.05). Results: There was no difference between both systems in the main root canals filling. Although the volume percentage of voids was similar in the apical and middle thirds of lateral canals, SIS had the greatest filling ability of the cervical third lateral canal. Moreover, the conventional system showed the highest apical extrusion of the sealer. Conclusions: The conventional and SIS obturation systems had an appropriate filling ability of the main root canal. SIS had the best filling of the cervical third of the lateral canals, besides lower sealer apical extrusion, suggesting its clinical indication.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.843-850
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• 2006

This is devoted to first, to propose a hash chain algorithm that generates more secure key than conventional encryption method. Secondly, we proposes encryption method that is more secure than conventional system using a encryption method that encrypts each block with each key generated by a hash chain algorithm. Thirdly, After identifying the user via wired and wireless network using a user authentication method. We propose a divided session key method so that Although a client key is disclosed, Attackers cannot catch a complete key and method to safely transfer the key using a divided key method. We make an experiment using various size of digital contents files for performance analysis after performing the design and implementation of system. Proposed system can distribute key securely than conventional system and encrypt data to prevent attacker from decrypting complete data although key may be disclosed. The encryption and decryption time that client system takes to replay video data fie is analogous to the conventional method.

• Korean Journal of Poultry Science
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• v.21 no.4
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• pp.257-266
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• 1994

Three protein feeding systems for egg-type pullets involving conventional step-down protein 18-15-12%), step-up protein(12-15-18%) and single-stage low protein (13-13-13%) with an iso-energy level of 2,900 ME kcal /kg were compared to examine the effect on pullet growth and subsequent laying performance. During the growing period, pullets subjected to the step-up and single-stage low protein feeding systems were lighter in body weight and consumed less feed and netabolizable energy than those on the conventional step-down protein feeding system(P<0.05). 3ut the pullets on the step-up protein diet consumed more protein, and those on the single-stage low protein diet consumed less protein than those on the step-down protein diet(P<0.05). Also, he feed cost was less in pullets on the single-stage low protein diet than in those on the other systems(P<0.05). During the laying period, sexual maturity was later in hens reared on the step-up and single-stage low protein diets than in those on the step-down protein diet(P<0.05), however, average hen-day egg production and egg weight were not significantly affected by the protein feeding systems in the growing period. Daily feed intake and feed required per egg were significantly reduced in hens on the single-stage low protein diet compared to those on conventional protein feeding system(P<0.05). It was concluded that the 13% single-stage low protein feeding system produced smaller pullets with less feed, energy, protein, and feed cost during the growing period, and hens reared on that system consumed less feed during the laying period without any impairment of production compared to the conventional rearing system.

• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.279-285
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• 2007

Soil physical properties in organic farming apple orchard were evaluated in relation to conventional farming to better understand the effects of organic farming system on soil quality. Two adjacent apple orchards, matched by soil type, were chosen to ensure the same pedological conditions except management system. Soil samples were collected from middle of two adjacent trees along the tree line at two depths of 5-20 and 20-35 cm in September 2006. Contents of organic matter in organic farming soil were twice as much as those found in soil of conventional farming. The higher level of organic matter in organic farming soil was reflected through a consequent trend in improved soil physical properties. Organic farming produced greater aggregation in >2 mm size and increased aggregate stability. Bulk density was lower by 13% and hence porosity was higher in soils of organic farming as compared with conventional farming. Water holding capacity was significantly greater with organic farming by >17% over conventional farming. The capacity of organic farming to improve soil physical properties can be contributed to the regular application of relatively large amount of organic materials and the sustainable ground-cover managements, mulching with compost and cover crop cultivation.

• Journal of Animal Environmental Science
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• v.20 no.4
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• pp.161-166
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• 2014

We conducted investigations of the information and welfare of cattle in Korea. The livestock housing of conventional cattle farms and organic cattle farms were open side wall type with winch curtain and used litter floor. The stocking density of conventional (ranging from $10head/m^2$ to $12.5head/m^2$) and organic cattle farms (ranging from $10head/m^2$ to $16.7head/m^2$) met the demand for conventional or organic standards, respectively. The galvanized plate and sunlight plate were used as the roof material in all of farms. Especially, additional areas were provided to produce forage or to improve animal welfare in organic cattle farms. Thus we believe that present data contribute to develop the animal welfare certification for cattle and to improve animal welfare in Korea.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.437-439
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• 1996

In this paper, an UPS system using high-frequency link AC to DC converter is Proposed. The AC to DC converter has sinusoidal input current and high power factor. In this UPS system, the waveform of the output voltage has smaller harmonic contents than those of a conventional UPS system. In this paper, an operating principle of the system is presented. This new control technique of the UPS system is capable of providing a wide range regulated output DC voltage compared with the conventional UPS system. Performance of the system carried out through theoretical and experimental means.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.376-379
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• 2001

This paper describes the design and fabrication process of super water-saving toilet bowl system by the theory of inventive problem solving (TRIZ). The physical contradiction in TRIZ is defined to obtain the conceptual design for saving water in toilet bowl system with preventing the bad smell from septic tank. The super water-saving toilet bowl system is obtained by using the separation principle in time for resolving the physical contradiction. The consumption of water in the prototype system fabricated, is estimated about $3{\ell}$ comparing with $13{\ell}$ of that in conventional toilet bowl system. The noise from water in the prototype toilet bowl system is decreased by 1/3 of that in conventional toilet bowl system.