• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.27-32
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• 1984

In SAW filters with a small aperture, diffraction effect is not negligible and degrades the frequency response near the trap. A computer simulation program for diffraction analysis is developed, and an effective diffraction compensation method is proposed to compensate the diffraction effect. A TV-lF SAW filter was designed with the diffraction taken account by the proposed method, which satisfies given frequency specifications.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.75-80
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• 2006

Since air pollution has become a globally critical issue and exhaust emissions from automobiles cause a major source of air pollution, many countries including advanced countries have stipulated stringent emission regulations. Particularly in diesel vehicles, NOx and particulate matters exhaust in significant amounts even though diesel vehicles provide merits in aspects of higher thermal efficiency and lower $CO_2$. To reduce Particulate matters and NOx, after-treatment technology such as filter trap, oxidation catalysts and EGR has been applied. This test was conducted on the effect of continuous regeneration diesel particulate filter and cooled-EGR, and 15ppm low sulfur diesel was used as a test fuel. Exhaust emissions, PM, NOx, CO, HC and Soots were measured and compared under D-13 and D-3 modes.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.802-806
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• 2001

Diesel particulate trap is the most reliable system to reduce the particulate matters from diesel engine. Filter is the core component of DPF and ceramic monolith type is dominantly used, which is expensive and fragile relatively at thermal shock. Porous metal filter, which has superior thermal characteristics and low cost, was tested in order to analyze the regeneration performance by using with ferrocene additive. This filter showed the 72% filtration efficiency, additives itself diminished 48% of PM from engine out emission, and final PM reduction ratio of 89% was achieved by DPF system with D-13 test mode.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.659-667
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• 1995

파골세포는 조혈기관 단핵의 세포로부터 생성되어 골 홉수에 중요한 역할올 담당하며, 지질다당류는 그람음성균의 세포벽을 이루는 성분으로서 치주질환시 치조골 홉수에 관여한다고 알려져 왔다. 활성화된 림프구, 대식세포와 단핵세포로부터 생성되는 당단백질인 인터페론 감마는 파골세포에 의한 골홉수를 억제한다고 밝혀졌다. 이 연구 논문의 목적은 지질다당류와 인터페론 감마가 닭 골수의 미분화세포가 파골양세포로 전환되는데 어떠한 영향올 주는지를 알아보기 위함이다. 16${\sim}$18 일째의 닭의 배 (chick embryo) 에서 경골을 분리하고 횡절개하여 혈청없는 M-199 배양액에 보관했다. 이것을 9${\mu}m$ filter로 여과시켜서 이미 분화된 파골세포와 기타 다른 분화 세포를 분리했다. 여기에서 파골세포의 전구세포를 얻어 LPS와 IFN-${\gamma}$를 단독 또는 복합처리 하고나서 4일 후에 tartrate resistant acid phosphatase (TRAP) Stain을 시행하고 TRAP 양성이며 핵이 세개 이상인 다핵의 세포형성을 관찰하여 세포를 계수하여 다음과 같은 결과를 얻었다. 1. 닭에서 분리해낸 미분화세포에 0.1. 0.5. 1.0 ${\mu}/ml$ 의 LPS 농도를 처리하고 1 주일간 배양한 결과. 0.1 ${\mu}/ml$ 의 농도에서는 대조군에 비해 TRAP 양성인 파골양세포가 증가하는 경향을 보였으며, 반면에 LPS는 0.5 와 1.0 ${\mu}/ml$ 의 농도에서 세포독성을 보였다.(P<0.05) 2. IFN-${\gamma}$는 50. 500U/ml 의 농도에서 대조군에 비해 TRAP 양성인 파골양세포의 수가 감소하는 경향올 보였다 .3. INF-${\gamma}$는 LPS 에의해 유도된 TRAP 양성인 파골양세포의 형성을 감소시켰고 특히 . 250.500U/ml 의 농도에서 유의 성 있는 감소를 보였다. 위의 결과로부터 LPS는 닭의 골수세포로부터 파골양세포의 형성을 증가시키며 IFN-${\gamma}$는 LPS에의해 유도된 파골양세포수를 감소시킨다는 결론을 얻었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.124-129
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• 2010

The direct injection (DI) diesel engine has become a prime candidate for future transportation needs because of its high thermal efficiency. However, nitrogen oxides (NOx) increase in the local high temperature regions and particulate matter (PM) increases in the diffusion flame region within diesel combustion. Therefore, the demand for developing hybrid system consist of exhaust gas recirculation (EGR) and aftertreatment system as well as diesel particulate filter (DPF) or lean NOx trap (LNT) should be applied. The variation of EGR rate due to the malfunction of EGR valve can affect not only the combustion stability of engine but also the performance of aftertreatment system. In this research, 2.0 liter 4-cylinder turbocharged diesel engine was used to investigate the combustion and emission characteristics for various operating conditions with EGR. While the fuel consumption was increased with increase of EGR rate, NOx emission was improved by maximum 90% at low speed, low load operating condition. To achieve combustion stability and reliability of aftertrearment system with minimum penalty in fuel consumption and emissions, the fault diagnosis of EGR malfunction must be employed.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.168-177
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• 1998

The effects of the regeneration parameters such as inlet gas temperature, space velocity, oxygen concentration of the exhaust gas, and initial particulate loading on the oxidation of the particulate inside ceramic cordierite filter have been investigated through an engine experiment. As the inlet gas temperature increases, the remarkable filter temperature occurs owing to the rapid combustion rate. Though the higher space velocity affirms the safe regeneration, it also requires much fuel consumption of the burner. For that reason, the space velocity should be compromised considering the fuel economy. The excessive accumulation of the particulate may cause undesirable regeneration temperatures inside filer even under the optimized regeneration condition. The inlet gas temperature should be selected to overcome the variation of the oxygen concentration which is inherent feature of the diesel engine. It is the most important factor in the regeneration control techniques.

• Journal of the Korean Society of Tobacco Science
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• v.26 no.2 s.52
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• pp.179-185
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• 2004

This study was conducted to investigate the delivery pattern of volatile organic compounds(VOCs) in mainstream smoke generated by the combustion of a different ventilated cigarette. To compare the delivery pattern and the concentration of VOCs in mainstream smoke, the six different ventilated cigarette was manufactured and analyzed VOCs using the GC/MS. As a result of this experiments, cambridge filter used to trap the particulate matter in mainstream smoke did not affect on the trapping of VOCs components, and two impinger method among the trapping methods was the best condition to trap VOCs from mainstream smoke. As the slope of the delivery of VOCs such as isoprene, acrylonitrile and toluene were higher than 1, but that of benzene was lower than other VOCs.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.264-268
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• 2007

The filtration performance of micron-sized metal fibrous filter was improved by synthesizing carbon nanotubes grown on the surface of metal fibers. The carbon nanotubes are grown with bush-like nanostructures covered around the micron-fibers or web-like nanostructures crossing between the fibers at different synthetic conditions. Filtration efficiency of CNT-metal-filter was measured and compared with the efficiency of the raw metal filter without CNTs. The developed CNT-metal-filter has higher filtration efficiency without significant difference in pressure drop compared with the conventional metal filter, which is because the carbon nanotubes function as the trap of pollutant nanoparticles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.67-79
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• 1996

This paper presents a composite luminance signal processing system for NTSC, PAL and SECAM standards. Eaxh of the three standards employs its own specifications of subcarmier bandwidth and luminance signal waveform. The proposed system, compatible to the specifications of the three standard and B/W TV, implements variable freqneucy characteristics by controlling filter coefficients. The major features of the system are a luminance/chroma separation unit and an aperture compensation unit. The luminance/chroma separation unit employes a notch filter selection a trap freqneyc to atenuate unwanted color signals in luminance signal bands. The aperture compensation unit comprises two subunits, to provide clear color definition for each of the three standards: a primary compensation circuit and a variable compensation circuits. The proposed system yields a 40 dB gain from the chroma/luminance separation and a 10 dB gain from the aperture compensation unit.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.82-92
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• 2011

This paper presents a PFC(Power Factor Correction) system to control the power factor of input current of the converter system which is working in the propulsion system of KTX high speed train. In the KTX train system, initially introduced from ALSTOM, the thyristor converter with phase controlling technique is adopted in the current fed type powering system. The input current induces harmonic losses highly because the waveform becomes rectangular shapes according to the filter inductor current increased as the train speed increasing gradually. Especially the interference with the signalling systems is severe concerned due to high current harmonics on the catenary line. To protect this problem, a frequency trap filter(notch filter) is operating with the input converter system. In this paper, an analysis work and PC simulation have been done on the PFC system to upgrade its performance and maintenance efficiency.