• Title/Summary/Keyword: 고연소도

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가전기기의 저진동, 저소음 기술 - 저소음화 기술

  • 임무생
    • 전기의세계
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    • v.44 no.10
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    • pp.23-27
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    • 1995
  • 가전기기의 진동과 소음은 제품의 고품질화에 상당히 저해되고 진동에 의한 소음이나 소음에 의한 진동을 해석하기 위하여 부단하게 노력하고 있다. 소리를 음이라 하며 음의 발생을 매질의 움직임에 의한 에너지 전달로 이해하고 있다. 따라서 음은 파동을 가지게 되어 음파(sound wave)로 불리우는 파에 의해 이동되며 이동시 주위의 매질에 압력 파동을 유발시킨다. 따라서 실내에서 발생하는 소리와 목욕탕등에서 나는 소리는 매질의 다른 성질(공기밀도)에 의해 다르게 느껴진다. 일반적으로 음의 주파수라하면 1초동안 음의 고저가 몇번 발생하였는가를 의미하며 사람이 소리로서 느끼는 주파수 범위를 20Hz에서 20kHz로 나타내어 가청 주파수라 한다. 그러나, 소리중에서도 사람에게 불쾌감을 일으키거나 심하면 고통까지 유발시키는 원하지 않는 소리가 있는데 이를 소음(noise)이라 부른다. 가전기기의 중요 소음 발생원이 유체소음, 전자기소음, 기계적소음, 연소소음등 소음원의 종류에 따라 저소음기술을 해석하는데 상당한 차이가 있다. 따라서 사용조건별 설정기준을 정하고 설정기준에 따른 현상소음 lavel보다 약 10dBA보다 낮은 소음 목표치로 설계되어야 한다.

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국내 여과집진막 시장 및 기술현황

  • 김병채
    • Proceedings of the Membrane Society of Korea Conference
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    • 1995.03a
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    • pp.1-45
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    • 1995
  • 대기오염 문제가 국가적인 사회문제로 대두되면서 대기오염 방지장치의 수요가 급증하고, 점차 강화되는 환경오염 규제로 인하여 고효율의 오염방지 장치의 설치가 요구된다. 대기오염방지장치에서 대표적인 집진장치 기술은 대기 및 실내오염제어 뿐만아니라, 정확성이 높은 첨단 클린룸 수요의 증가 등으로 인하여 산업체의 각 분야에서 필수적이면서도 기본적인 기술이다. 대기중의 분진은 분자의 응축 및 핵생성등에 의하여 발생되는 매우 미소한 입자(0.05 $\mu$m)와 일반공장 및 작업장등에서 발생되는 분진 (0.1 - 10 $\mu$m) 그리고 바람에 의한 지표면의 흙, 모래등에 의한 비교적 큰 분진등의 광범위한 조성과 입경분포를 가진다. 이 가운데, 특히 산업발달에 따라 불가피하게 생성되며, 대기오\ulcorner의 주종을 이루면서 인체에 가장 유해한 분진입자는 산업체의 오일 및 석탄연소 보일러, 자동차, 제철/제강 및 시멘트 플랜트등으로 배출되는 미세입자들이며, 앞으로 이들의 제어에 과한 연구가 지속적인 관심의 대상이 될 것이다.

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표준형 원전을 위한 장주기용 개량연료 노심 해석

  • 이국종;최기용;이해찬;정선교
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05a
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    • pp.73-79
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    • 1996
  • 현재의 원전 운용은 연료주기 비용을 최소화하여 경제성을 향상시키는 것이 세계적인 추세이다. 따라서 영광 3, 4호기 이후의 국내 원전 건설의 대부분이 될 한국 표준형 원전을 대상으로 하여, 현재 개발 중이거나 이미 실용화된 개량 원전 연료의 특성을 적용하여 실제 노심해석을 수행하고. 이에 따른 경제성 분석을 수행하였다. 노심해석은 현재의 영광 3, 4호기에 장전된 CE형 연료 및 장주기용 개량연료를 초기노심 및 평형 노심에 각각 장전하는 경우에 대하여 수행하였다. 가연성 흡수체는 현재 사용중인 Gadolinia 및 Integral Fuel Burnable Absorber(IFBA) 가연성 흡수체를 사용하여 분석하였다. 그 결과 현재의 CE형 연료에서 사용하는 0.382" 연료봉보다 0.374"의 연료봉이 중성자 경제성 측면에서 유리하며, Gadolinia보다 IFBA가 반경방향 첨두출력 계수의 제어를 쉽게할 수 있슴이 밝혀졌다. 그 외에 열적 여유도 증진을 위한 유량 혼합 날개의 채용과 고연소도를 위한 새로운 피복관 재료의 사용이 요청된다. 이상과 같은 결과는 향후 표준형 원전의 장주기용 개량연료를 위한 개발 방향으로 제시될 수 있다. 제시될 수 있다.

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Analysis of Flight Data in SpaceX's Falcon 9 (스페이스X사의 팔컨 9 비행데이터 분석)

  • Kim, Hyeonjun;Ryu, Chulsung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.12
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    • pp.997-1010
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    • 2021
  • This study collected and analyzed flight data of SpaceX's Falcon 9 launch vehicle. All missions were classified by orbital types, such as Polar, SSO, ISS, LEO and GTO missions. In characteristic maneuvers of main engine cutoff, boostback, reentry and landing burn at each stage of 1st stage launch vehicle, changes of the physical parameters like speed, altitude, dynamic pressure and acceleration were investigated. The guidelines derived from detailed maneuver analysis were suggested, which can be used as design and evaluation references for developing reusable launch vehicle.

Studies on the Breeding of the Response to short photoperiod, Fiber weight, and Qualitative characters and of the Associations Among these characters in Kenaf (섬유용양마의 육종에 관한 연구 -단일반응성과 섬유종의 유전 및 연소)

  • Johng-Moon Park
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.4 no.1
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    • pp.115-124
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    • 1968
  • It was shown that the most desirable characters for kenaf are high-fiber weight and moderately early maturity. Therefore, the objectives of this research on this crop is to find varieties possessing these characteristics. The experiments covered in this report provided new information relative to segregation, mode of inheritance, estimate of the number of genes involved in fiber weight and their response to short day length of 10 hours and the qualitative characters, such as, color of stem, capsule, petiole and shape of leaves. The associations which exist among these characters are also indicated. Fiber weight per plant, days to flowering, Stem color, Petiole color, Capsule color, and shape of leaves were studied in parental, $F_1$.$F_2$and backcross populations of a cross between Dashkent, a low-fiber weight but early maturing kenaf variety, and G 38 F-1, a high-fiber weight but late maturing kenaf variety. Crosses were made using the varieties, Dashkent and G 38 F-1 as parents. The Dashkent parent had the following characteristics: green stems, capsules and petioles and lobed shaped leaves; 105.8234 mean-days to flowering in the field, and 106.9222 mean-days under 10 hours short day treatment. The other parent, G 38 F-1 had red stems yellow capsules and red petioles and unlobed shaped leaves; 149.8921 mean-days to flowering in the field, and 62.3684 mean-days under 10 hours short day treatment. Both of the parents, $F_1$, $F_2$, $BC_1$ ($F_1$ X Dashkent, ) and $BC_2$($F_1$ ${\times}$ G38F-1) of the kenaf cross were grown at the Crops Experiment Station, Suwon, Korea in 1965. Color of stems, petioles and capsules, and shape of leaves were noted to be simply inherited as a single factor. Red stem color was dominant over green stem color, red petiole color was dominant over green petiole, lobed shaped leaves were dominant over unlobed shaped leaves and yellow capsules were dominant over green capsule. It was, also, noted that the factor for color of petiole was linked with the factor for shape of leaf with a 11.9587 percent recombination value, however no interaction or linkage were found among the color of stem and capsule color. Using Powers partitioning method, theoretical means and frequency distributions for each population, the days to flowering were calculated with the assumption that two gene pairs were involved. The values obtained fitted the theoretical values. In general this would indicate that Dashkent and G 38 F -1 were differentiated by two gene pairs. Heritability values were calculated as the percent of additive genetic variance. Heritability value of days to flowering, 89.5% in the broad sense and 79.91% in the narrow sense, indicated that the selection for this character would be effective in relatively early generations. Particularly, high positive correlations were found between days to flowering and the color of petioles and shape of leaves. However, there was no relation between days to flowering and capsule color nor between these and stem color. On the basis of the results of this experiment there is evidence that the hereditary factor for shape of leaves and the color of petioles is linked with an effective factor or factors for the characters of days to flowering. The association was sufficiently close to offer a possible simple and efficient means of selection for moderately early mat. uring plants by leaf shape and petiole color selection. Again using Powers partitioning method the frequency distribution for each population to the fiber weight were calculated with the assumption that two gene pairs, AaBb, were involved. Both phenotypic and genotypic dominance were complete. The obtained value did not agree with the theoretical value for $F_2$ and $BC_1$ ($F_1$ ${\times}$ Dashkent.) It seems that Dashkent and G 38 F-1 were differentiated by two major gene pairs but some the other minor genes are necessary. It is certain that the hereditary factor for shape of leaves and color of petioles is linked with an effective factor or factors for fiber weight. Also, high. yielding plants with moderately early maturity were found in the $F_2$ population. Thus, simultaneous selection for high-fiber yield and moderately early maturing plants should be possible in these populations. Phenotypic and genotypic correlation coefficients between fiber weight per plant and days to flowering, stem height and stem diameter were calculated. In general, genotypic correlations are higher than the phenotypic correlation. The highest correlation is found between stem height and fiber weight per plant (0.7852 in genotypic and 0.4103 in phenotypic) and between days to flowering and fiber weight per plant (0.7398 in genotypic and 0.3983 in phenotypic.) It was also expected that the selection of high stem height and moderately early maturing plants were given the efficient means of selection for high fiber weight.

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Performance Analysis of Methane Fueled Marine Solid Oxide Fuel Cell and Steam Turbine Hybrid Power System (선박동력용 SOFC/ST 하이브리드시스템의 성능 평가)

  • Lee, Kyung-Jin;Oh, Jin-Suk;Kim, Sun-Hee;Oh, Sae-Gin;Lim, Tae-Woo;Kim, Jong-Su;Park, Sang-Kyun;Kim, Mann-Eung;Kim, Myoung-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.5
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    • pp.590-599
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    • 2011
  • The electrification of the waste heat of fuel cell is necessary to enhance the efficiency of fuel cell system. For this purpose, the SOFC/ST(Solid oxide fuel cell/Steam turbine) hybrid system is suitable. The purpose of this work is to predict the performance of methane fueled SOFC/ST hybrid power system and to analyze the influence of operating temperature of stack, current density of stack, combustor outlet gas temperature, and boiler outlet gas temperature. According to the analysis, it is proved that making the best use of the waste heat of stack and minimizing the fuel consumption of combustor are essential for the high-efficiency of SOFC/ST hybrid system.

Effect of Swirl Injector with Multi-Stage Tangential Entry on Acoustic Damping in Liquid Rocket Engine (액체로켓에서 다단 접선 유입구를 갖는 스월인젝터의 음향학적 감쇠기능)

  • ;;;;Bazarov, V. G.
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.10
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    • pp.71-79
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    • 2006
  • Swirl injector with multi-stage tangential entry was analyzed to suppress high-frequency combustion instability in Liquid Rocket Engines. In order to analyze the effect of swirl injector as an acoustic absorber, swirl injector was regarded as a quarter-wave resonator and it's damping capacity is verified in atmospheric temperature. It has a finite mode of vibration and natural frequencies which can be tuned to the natural frequencies of a model combustion chamber. The interior air core shape of injector is more stable in the case of using the swirl injector with multi-stage entry than with single-stage entry. Also, when the swirl injector with multi-stage entry is used, tuned-injector length for unstable mode is well agreed with the calculated length. From the experimental data, it is proved that if the interior air core shape of swirl injector is stable, the fine tuned swirl injector can decrease the unstable mode of model chamber effectively and increase the damping rate.

The Characteristics of Exhaust Gas in Diesel Engine by Corana Discharge-EGR System (코로나 방전-EGR 조합시스템에 의한 디젤기관의 배기 가스 특성)

  • Park, Jae-Yoon;Jung, Jang-Gun;Kim, Jong-Suk;Ha, Hyun-Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.7
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    • pp.39-44
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    • 2005
  • A great part of flint fuel is Hydrogen and carbon's combination, they should be generated steam and carbon gas when combine with oxygen for perfect combustion in the inside of engine but, the pollutive material are discharged, even though perfect combustion condition especially $NO_x$ and Smoke. they are really harmful for health. In this paper was shown the result of discharging gas' reduction quality. which used combination of corona discharge using the high voltage source of common frequency with EGR. $NO_x$ is increased in entire load erea in proportion to increasing of EGR rate and impression voltage. Smoke is increased slowly under 75[%] in load rate but it is increased rapidly in entire load erea and the reduction rate of Smoke is increased in proportion to increasing of impression voltage.

A Study on Quantification of Damping Efficiency of Acoustic Cavities by Absorption Coefficient (흡음 계수를 이용한 연소불안정 제어용 음향공의 감쇠 정량화)

  • Cha, Jung-Phil;Song, Jae-Gang;Hong-Jip Kim;Ko, Young-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.5
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    • pp.438-445
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    • 2007
  • A Helmholtz resonator as a stabilization device to control high-frequency combustion instabilities in liquid rocket engine is adopted and its damping capacity is verified by linear acoustic analysis and atmospheric acoustic tests. To compare the results of acoustic attenuation effect in accordance with uni-resonator's geometry, quantitative analyses were made in the cases of various orifice diameters and lengths. Next, in the experiments to compare the results of acoustic attenuation effect by a difference in the number of resonators, damping capacity of harmful resonant frequency was improved by the increase of the number of resonators. On the other hand, attenuation efficiency of the frequency tended rather to lower due to over damping from the point of view of absorption coefficient. As the result, tuning the suitable geometry for the resonator to the resonant frequency is required for the control using the resonator. Also, the design of resonator's geometry and the choice of its number are important to put up the optimal efficiency in consideration of restriction of its volume.

The Effect of Hydrogen Added into In-let Air on Industrial Diesel Engine Performance (흡기중의 수소첨가가 산업용 디젤기관의 성능에 미치는 영향)

  • Park, Kweon-Ha;Lee, Jin-A;Lee, Wha-Soon
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.8
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    • pp.1050-1056
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    • 2010
  • Diesel engines introduce only air into the cylinder, and the air is high lycompressed. Fuel is directly injected into the combustion chamber in high temperature and pressure. Therefore diesel engines have high thermal efficiency because of the high compression ratio, while having high level of particulate matter and nitrogen oxide emissions because of the direct fuel injection. Many technologies have been developed to reduce particulate matter and nitrogen oxide emissions from diesel engines. One of the technologies is hydrogen fuel introduced into the combustion chamber with diesel fuel. In this thesis tiny amount of hydrogen is supplied into the combustion chamber in order to enhance the combustion performance. The engine, in which hydrogen is introduced, is tested. There are 20 test conditions given as 5 torque values of 100%, 75%, 50%, 25%, 0%, and 4 engine speeds of 700rpm, 1000rpm, 1500rpm and 2000rpm for the two cases with or without hydrogen addition. Maximum torques and Idle torques at each engine speed are measured, then the torque values are divided into 4 levels with 25% increasing step. The result shows that the fuel consumption, smoke, CO are reduced while the NOx emission is slightly increased, and the hydrogen addition has not a great effect on the performance at low loads but a great effect at a maximum load.