• 한국연초학회지
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• 제28권1호
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• pp.23-30
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• 2006

In order to improve the final product quality, tobacco industry has gradually decreased the size and number of steams in the cigarette. Especially, steams bigger than $3{\times}3$ mm($length{\times}thickness$) and $2{\times}10$ mm($width{\times}length$) are not acceptable in the process as objectionable stems. A total number of 12 samples where the $length{\times}tickness$ samples were prepared by decreasing the present sample ($3{\times}3$ mm) with 1 mm up to $1{\times}1$ mm, and the $width{\times}length$ samples were prepared by decreasing the present sample ($2{\times}10$ mm) with 2 mm up to $2{\times}6$ mm for the stems in leaf and stems in expanded cut-tobacco were prepared to apply a fire ball drop test using stems. In addition, cigarettes were produced for these stems in order to analyze the forced fire ball drop including the burning, encapsulation and unencapsulation pressure drop and a single or unspecified direction combustion. Based on the results of the test, it was evident that the fire ball drop in the stems in expanded cut-tobacco presented a lower level than that of the stems in leaf. Also, the stems in expanded cut-tobacco presented a larger swelling and higher burning for a single direction than that of the stem in leaf. In addition, it was considered that the management criteria for objectionable stems should be changed as $3{\times}3$ mm and $2{\times}8$ mm for the $length{\times}thickness$ and $width{\times}length$ sample, respectively, in both steams in leaf and expanded cut-tobacco.

• Advances in materials Research
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• 제2권2호
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• pp.77-91
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• 2013

High quality nanoparticles of neodymium barium niobium ($NdBa_2NbO_6$) perovskites have been synthesized using an auto ignition combustion technique for the first time. The nanoparticles thus obtained have been characterized by powder X-ray diffraction, thermo gravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscopy. UV-Visible absorption and photoluminescence spectra of the samples are also recorded. The structural analysis shows that the nano powder is phase pure with the average particle size of 35 nm. The band gap determined for $NdBa_2NbO_6$ is 3.9 eV which corresponds to UV-radiation for optical inter band transition with a wavelength of 370nm. The nanopowder could be sintered to 96% of the theoretical density at $1325^{\circ}C$ for 2h. The ultrafine cuboidal nature of nanopowders with fewer degree of agglomeration improved the sinterability for compactness at relatively lower temperature and time. During the sintering process the wide band gap semiconducting behavior diminishes and the material turns to a high permittivity dielectric. The microstructure of the sintered surface was examined using scanning electron microscopy. The striking value of dielectric constant ${\varepsilon}_r=43$, loss factor tan ${\delta}=1.97{\times}10^{-4}$ and the observed band gap value make it suitable for many dielectric devices.

• 한국전자통신학회논문지
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• 제17권4호
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• pp.625-632
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• 2022

국내 전력계통에 부하추종운전 중인 가스터빈 발전기들은 정격 주파수 유지에 큰 역할을 하고 있지만 종종 주파수 제어가 불량한 경우도 발생한다. 이에 가스터빈 속도제어 장치인 조속기의 제어 특성을 살펴보고 고장 유형을 분석한 후 사안 별로 대책을 제시하였다. 그리고, 가스터빈은 연료제어의 빠르기에 따라 주파수 회복에는 도움을 되지만 연소실 온도가 급격하게 변동하고 연소진동이 발생하는 등 안정운전을 저해하는 요소로 작용하기도 한다는 것을 조속기 응동시험을 통해 확인하였다. 따라서, 안정적인 전력품질을 유지하기 위해서는 철저한 설비관리를 수행하고 비례 적분 미분 제어방식에 4차산업의 핵심분야인 기계학습 알고리즘이 융합된 조속기 제어방식의 연구 필요성이 대두되었다.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.51-59
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• 2012

Piezoelectric langasite crystals have superior properties such as high temperature performance and high quality Q and can be applied in combustion pressure sensors and surface acoustic wave (SAW) filters. Crystal growth, crystal structure and properties of langasite group are reviewed, and the mechanism of piezoelectricity of langasite is presented based on the crystal structure and deformation under high pressure. Finally, for the discovery of new piezoelectric materials, this paper presents the role of the framework, and recommends the search of framework crystal structure, because the characteristic of the mechanism exists on the framework of the crystal structure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.293-298
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• 2002

Recycling of coal combustion by-product(Ash) are becoming more improtant in the utilization business as a result of the increased use of NOx reduction technologies at coal-fired power plants. current disposal methods of these by-products create not only a loss of profit for the power industry, but also environmental concerns that breed negative public opinion. This research made concrete crecast block using coal ash artificial aggregate for environmental-friendly products and compared strength special quality of this block with existent common use brick and analyzed application possibility in situ with a reserve experiment that measured strength property and manufactured method to handle coal ash produced in Bo-ryung thermoelectric power plant.

• 오토저널
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• 제11권6호
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• pp.89-96
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• 1989

Engine analyzer is developed with the aids of personal computer, A/D converter, interfacing signal transducer and data processing computer programs. The objective of this development are that it should firstly be produced at the resonable low price compared with imported one taking advantage of using existing personal computer and printer, and it should also give good quality of performance. For the attainment of this objective, A/D converter should have been developed to meet the price limit of the equipment. The experiment is performed in a 4 cycle 4 cylinder gasoline engine by this analyzer, and all the information which are necessary for the combustion analysis can be obtained through the processing of the pressure data that are stored in the computer. These are pressure-volume curve, pressure-crank angle curve, the rate of pressure rise and heat release versus crank angle curve etc. With this developed experimental system of resonable price, it will be considered that more easy way of engine data pick-up and processing is possible.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.1015-1020
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• 2002

Recycling of coal combustion by-product(Ash) are becoming more improtant in the utilization business as a result of the increased use of NOx reduction technologies at coal-fired power plants. Current disposal methods of these by-products create not only a loss of profit for the power industry, but also environmental concerns that breed negative public opinion. This research made Precast block for environment-friendly secondary product and compare strength special quality of this block with existent common use brick and analyze application possibility in situ with a reserve experiment that measure strength property and manufacture method to handle coal ash produced in Bo-ryung thermoelectric power plant.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.178.1-178.1
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• 2011

DME is generally expected to be used as a promising clean alternative fuel to diesel fuel. DME is not natural product but a synthetic product that is produced either through the dehydration of methanol or a direct synthetic from syngas. As DME has no carbon-carbon bond in its molecular structure and is an oxygenate fuel, it's combustion essentially generates no soot. DME has such cetane number of 55~60 that it can be used as a diesel engine fuel. However, DME has low lubricity but a proven method to solve the poor lubricity is by adding lubricity improver. Therefore, the aim of this study is to develop lubricity improver of DME as a transport fuel in Korea. In this study, we investigated a possibility of fatty acid ester compounds as a candidate to improve DME lubricity as compared with current lubricity improver of diesel. We also evaluated quality characteristics, storage stability of DME with lubricity additives.

• Tribology and Lubricants
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• 제21권2호
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• pp.83-92
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• 2005

A piston assembly is very important because it directly receives the energy generated during combustion process. Surely, the friction and lubrication of piston-ring pack do an important role in the performance and fuel economy of an engine. In fact, the friction loss in piston-ring pack is the biggest portion to the whole engine friction. Therefore, the improvement of lubrication quality and friction loss in piston-ring pack will be directly related with the improvement in the performance and fuel economy of an engine. Meanwhile, the oil consumption and blow-by gas through piston-cylinder-ring crevices have to be controlled as less as possible. In these two aspects, the study on the optimized design of piston-ring pack has to be carried out. In this study, for the efficient design of piston-ring pack, it is focused to develop a basic computer program that predicts the inter-ring pressure, the motion of ring and the blow-by gas through a crevice volume model between adjacent rings, and the oil film thickness and the friction computed by lubrication theories.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.136-148
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• 1999

Detailed mathematical models of hybrid drivertrain components are presented and numerical simulations are carried out to analyze the shift characteristics and to improve the driving comfortability when the hybrid drivetrain is applied at the vehicle . Theoretical results are compared with experimental ones from the dynamometer as same condition in order to prove the appropriateness of modeling . Adding the vehicle body modeling, included in the suspension and the engine mount, it is possible to predict the dynamic behavior and shift characteristics more actually when shifts are occurred by automated manual transmission(AMT). these additional results are also compared with the same simulation ones of internal combustion engined vehicle equipped conventional manual transmission. Hence, it can be expected that the hybrid vehicle with AMT has a good shift quality.