• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.82-97
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• 2009

In this study, a linearlized model of liquid rocket engine specifically for the gasgenerator cycle one was developed to serve as a basic control model. A commercial software Simulink was used for the modeling. Using this tool we studied the throttling characteristic of engine around its nominal mode. To obtain the effect of the throttle valve design on the engine's control characteristic, we included mathematical model of the control valve with driving motor and the pressure stabilizer which installed on the gas-generator fed line to sustain the mixture ratio of the gas-generator.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.4
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• pp.53-61
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• 1988

Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.513-518
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• 2008

In the air-conditioning and refrigeration industry, the efforts to protect the environment have been made. One of them is to use carbon dioxide as an alternative refrigerant, however, several researches have shown that the transcritical heat pump system using $CO_2$ has relatively lower efficiency resulting in a degraded steady-state system performance. Capacity control with fuzzy controller was carried out for $CO_2$ heat pump system. Evaporator secondary fluid outlet temperature was suggested for the control variable of compressor speed modulation.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1852-1854
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• 2003

In manufacturing processes, various and suitable pulse shapes are required for the purpose of material processing. In order to make various pulse shapes with variable pulse length and high duty cycle, We have fabricated the power supply consisting 6 SCRs and the Pulse Forming Network(PFN) with the precise delay time control. So our control system has three switching circuits, 3 mesh PFN, and simmer circuit. In addition, we have designed and fabricated the PIC one-chip microprocessor(16F877) to control the delay time of sequential switching.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.3 no.2
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• pp.63-68
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• 1989

This paper discussed the Multi-PAM inverter for static power supply design. The controller part composed of one-chip microcomputer obtained control pattern simply. The configuration of termination part was composed of double bridge inverter and three-phase, three-winding transformer. The output waveforms using a controller and transformers synthesized the multi-PAM wave form by a voltage level of 22 steps per one-cycle. The output waveforms using the Low Pass Filter approximated to the sine wave.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.569-576
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• 2013

The Airworthiness Certification from the government has an increasingly important role due to the dramatic growth of military aircraft development industry. It is a mandatory process of qualifying the flight safety within the aircraft's operational boundaries throughout its life cycle. The introduction of airworthiness certification has resulted in development paradigm shift from one requirement for one consumer need to the common requirement for many needs. This research paper provide the refinement of airworthiness certification criteria related to the flight control law and the verification methods which comply with its criteria.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.90-96
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• 2014

This paper presents a practical linearization technique for a wide-band bang-bang digital phase locked-loop(BBDPLL) by selecting optimal loop gains. In this paper, limitation of the theoretical design method for BBDPLL is explained, and introduced how to implement practical BBDPLLs with CMOS process. In the proposed BBDPLL, the limited cycle noise is removed by reducing the proportional gain while increasing the integer array and dither gain. Comparing to the conventional BBDPLL, the proposed one shows a small area, low power, linear characteristic. Moreover, the proposed design technique can control a loop bandwidth of the BBDPLL. Performance of the proposed BBDPLL is verified using CppSim simulator.

• Korean Journal of Animal Reproduction
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• v.22 no.2
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• pp.153-161
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• 1998

This study was conducted to examine the viability of nuclear transfer bovine embryos following embryo transfer. Donor embryos were treated with nocodazole to arrest their cell-cycle-stage at mitotic(M) phase. After releasing from nocodazole blastomeres were separated and transferred into the enucleated oocytes(BC), or cultured in medium with aphidicolin. Freshly cleaved blastomeres within 1.5h after cleavage(AC) and non-cleaved ones up to 3h after releasing from nocodazole(NC) were transferred into the enucleated oocytes. Blastocysts derived from nuclear transfer were transferred to Day 7~8 recipient cows. Some blastocysts were vitrified and thawed before embryo transfer. Developmental rates to the blastocyst stage were higher in AC(18.1%, P<0.05) than BC(8.6%) and NC(5.1%). Blastocyst development slightly enhanced with aphidicolin(1~2$\mu\textrm{g}$/ml) treatment(16.9~22.6%) compared to non treated control(11.1%). Survival rate fo vitrified nuclear transfer embryos after thawing was 75%(24/32). Twnety-three vitrified nuclear transfer embryos and 3 fresh ones were transferred to 23 recipients, 6 heads were pregnant and 1 male calf(24 kg) was born from a recipient cow recevied one vitrifiedthawed nuclear transfer embryo at 277 days after embryo transfer. This result suggests that the nuclear transfer embryos can developed to term after vitrification andembryo transfer.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.186-186
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• 2000

In the GPS/DR integrated system, the GPS position(or velocity) is used to compensate the DR output and to calibrate errors in the DR sensor. This synergistic relationship ensures that the calibrated DR accuracy can be maintained even when the GPS signal is blocked. Because of the observability problem, however, the DR sensors are not sufficiently calibrated when the vehicle speed is low. This problem can be solved if we use a multi-antenna GPS receiver for attitude determination instead of conventional one. This paper designs a two-antenna GPS receiver integrated with DR sensors. The proposed integration system has three remarkable features. First, the DR sensor can be calibrated regardless of the vehicle speed with the aid of two-antenna GPS receiver. Secondly, the search space of integer ambiguities in GPS carrier-phase measurements is reduced to a part of the surface of the sphere using DR heading. Thirdly, the detection resolution of cycle-slips in GPS carrier-phase measurements is improved with the aid of DR heading. From the experimental result, it is shown that the search grace is drastically reduced to about 3120 of the non-aided case and the cycle-slips of 1 or half cycle can be detected.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1473-1483
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• 2014

Reports of herbicide resistance events are proliferating worldwide, leading to new cultivation strategies using combinations of pre-emergence and post-emergence herbicides. We analyzed the impact during a one-year cultivation cycle of several herbicide combinations on the rhizobacterial community of glyphosate-tolerant Bt-maize and compared them to those of the untreated or glyphosate-treated soils. Samples were analyzed using pyrosequencing of the V6 hypervariable region of the 16S rRNA gene. The sequences obtained were subjected to taxonomic, taxonomy-independent, and phylogeny-based diversity studies, followed by a statistical analysis using principal components analysis and hierarchical clustering with jackknife statistical validation. The resilience of the microbial communities was analyzed by comparing their relative composition at the end of the cultivation cycle. The bacterial communites from soil subjected to a combined treatment with mesotrione plus s-metolachlor followed by glyphosate were not statistically different from those treated with glyphosate or the untreated ones. The use of acetochlor plus terbuthylazine followed by glyphosate, and the use of aclonifen plus isoxaflutole followed by mesotrione clearly affected the resilience of their corresponding bacterial communities. The treatment with pethoxamid followed by glyphosate resulted in an intermediate effect. The use of glyphosate alone seems to be the less aggressive one for bacterial communities. Should a combined treatment be needed, the combination of mesotrione and s-metolachlor shows the next best final resilience. Our results show the relevance of comparative rhizobacterial community studies when novel combined herbicide treatments are deemed necessary to control weed growth.