• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.540-543
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• 2011

This work is devoted to an experimental investigation on conceptual design of dual consecutive stage micro plasma thruster (${\mu}PT$). Optimization study on the thruster configuration has been performed for various electrode gap distances from 1 mm to 2 mm and the hole diameter from 0.3 mm to 2 mm depending on desired operating conditions and corresponding nozzle design requirement. The operation of ${\mu}PT$ at low pressure from $10^{-1}$ Torr to $10^{-4}$ Torr and at various argon flow rates ranging from 5 sccm to 300 sccm has been studied to understand the physic of plasma and the gas dynamics in details. The specific impulse can reach up to 3000-4000 seconds at low power consumptions from 1 to 5 W. Image of exhaust plume from ${\mu}PT$ will be provided and electrical characteristics is also mentioned in this paper.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.520-527
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• 1988

Liquid ejectors are widely used as marine pumps, inducer stage for the boiler feed water pump, boiler recirculating pump, cooling water recirculating pump in boiling water type nuclear reactor and a deep well pump, because of their high working confidence and simplicity. Furthermore, it requires only a modest net positive suction head for cavitation-free operation and it can be installed in remote location from mechanical power source. It is not easy to presume the friction losses, because it is complicately affected by area ratio, flowrate ratio, nozzle spacing, throat length, shape of liquid ejector and so on. Therefore, the optimization of liquid ejector design is still dependent, to a large extent, on the experimental results and empirical procedures. On the design of the liquid ejector, the area ratio and the nondimensional throat length are the most important design factors among the mentioned above. In this experiment, the effects of the area ratio and the nondimensional throat length to ejector efficiency are carried out systematically by the combination of 4 kinds of motive nozzle and 2 kinds of throat length. In this paper, the present experimental results are compared with the calculated ones by the previous computer aided design program based on one dimensional flow equation. And also, an empirical equation for the working limit of liquid ejector is reported.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.60-69
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• 2013

An optimum configuration of the hybrid/dual swirl jet combustor for a micro-gas turbine was investigated experimentally. Location of pilot nozzle, angle and direction of swirler vane were varied systematically as main parameters under the conditions of constant thermal load. The results showed that the variation in locations of inner fuel nozzle and pilot burner resulted in significant change in flame shape and swirl intensity due to the changes in recirculating flow pattern and minimum flow area near burner exit, in particular, with the significant reduction of CO emission near lean-flammability limit. In addition, it was observed that the co-swirl configuration produced less CO and NOx emissions compared to the counter-swirl configuration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.375-379
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• 2008

In this paper, a 10N class liquid propellant rocket utilizing a dissolving reaction of hydrogen peroxide is constructed and tested. Through a series of designs, seven orifices with a diameter of 200 ${\mu}m$ and a nozzle with a neck of 2.5mm in diameter and area ratio of 2.56 were made. The platinum coated on Isolite was used for catalyst. 90wt% peroxide pressed at 20 bar by nitrogen gas was used for performance evaluation. The length of the catalyst bed and the load of platinum was taken as the parameters for this experiment. For the catalyst support length of 4cm loaded on 5wt% platinum, satisfactory $c^*$ efficiency and stable thrust was observed. The light weight body of the rocket was composed of aluminum. Rocket rose about 10m with relatively constant velocity in launching test.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.60-60
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• 2011

염색폐수의 정화에는 필연적으로 다량의 슬러지 폐기물이 발생한다. 염색폐수 슬러지는 그간 인근 공해 해상에 투기하는 해양 배출로 저렴하게 처리하였으나, 해양오염을 우려하는 국제협약(1972년 런던협약, 1996년 교토의정서)에 의하여 2008년 8월부터 배출기준이 강화되고 2012년 2월부터는 해양배출이 금지 될 예정이다. 염색폐수 슬러지의 해양 배출이 금지되면 대체 처리방법으로는 지정매립장을 통한 매립처리 방법이나 고온 소각시설에서의 소각처리 방법이 거론되고 있다. 그러나 매립처리는 슬러지 내 함유 수분으로 인한 침출수의 문제와 더불어 장기간 안정적으로 저렴하게 사용할 수 있는 대규모 처분장을 확보하기 어려운 실정이며 소각처리는 슬러지의 높은 함수율로 인해 소각 시보조 연료의 투입이 필연적으로 최근 원유가 급등 등 에너지 비용이 지속적으로 상승함을 고려할 때 소각처리비용 또한 상당한 고가가 될 것으로 예측된다. 이와 같이 슬러지 해양배출이 금지되면 섬유 염색업체들은 많은 환경비용 부담을 안을 것이다. 본 연구에서는 대규모 염색산업단지 공동폐수처리장에서 발생하는 염색폐수 슬러지의 효율적인 건조를 위해 산업단지 내의 열병합발전소에서 발생하는 보일러 폐열을 이용하였으며, 조건 특성 및 효율을 파악하기 위해 보일러 폐열의 특성을 고려하여 슬러지 두께 및 체류시간 등 건조공정 운영조건에 따른 변수별 연구를 수행하였다. 열병합발전소 보일러에서 배출되는 폐열은 온도가 $150^{\circ}C$ 정도로 기존의 슬러지 건조에서는 사용되는 $700^{\circ}C$에 비해서는 매우 저온이다. 하지만 보일러 배가스의 경우, 온도에 비해 많은 풍량을 가지고 있으므로 열량으로 환산시 충분히 가치가 있는 것으로 조사되었다. 염색폐수 슬러지의 경우, 함수율 70% 이내의 탈수 Cake 형태이므로 두께가 두꺼울수록 건조효율이 감소하였으며, 체류시간이 길어질수록 건조효율은 증가하나 20mm 이상에서는 건조효율이 급격히감소하였다. 이를 바탕으로 5톤/일 규모 슬러지 건조 Pilot Plant를 제작하여 운영하였는데, 염색폐수슬러지의 투입공정에서 슬러지와 열풍의 접촉면적을 넓혀 건조효율을 높이기 위하여 슬러지를 압출노즐을 이용하여 슬라이스 칩 형태로 제조하여 건조공정에 투입하였으며, 건조실 내에서도 건조효율의 상승을 위하여 내부열풍순환팬을 설치하여 운영하였다. Pilot 운영결과, 체류시간 52분에서 슬러지의 함수율은 70%에서 10%이하로 감소하였다.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.53-63
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• 2024

Adopting an engine igniter with high efficiency and ignition performance is essential for reliable operation of liquid rocket engines. In this study, we developed a spark torch igniter for a 450 N-scale methane-oxygen liquid rocket engine by conducting numerical analyses, igniter manufacturing and validation. Specifically, we conducted a parametric study for maximizing the enthalpy at the igniter exit, specifically by adjusting the mass flow rate, nozzle area ratio, fuel-oxidizer mixture ratio, and the igniter length-to-diameter. The heat transferred via the igniter nozzle exit was computed using 3-dimensional numerical simulations. We also manufactured and tested the igniter based on a deduced design to confirm ignition performance of the designed spark torch igniter. The igniter developed through this study could contribute to the development of practical propulsion systems such as upper-stage engines of small launch vehicles.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.45-51
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• 2001

Catalytic combustion is the environmental-friendly technology, which has been applied to a variety of areas for industrial and domestic use in recent years. Accordingly, this study performed the development of the catalytic manufacturing technology for the high temperature and of the catalytic combustor in priority, which were aimed to be aimed to a commercialized condensing boiler. Palladium(Pd) of a noble meta] was used as a catalyst for the high temperature and supported on $alumina(Al_{2}O_{3})\;and\;zirconia(ZrO_2)$ in constant weight ratio. Activity of Pd catalysts is compared and analysed in the catalytic combustion of natural gas. The ratio of $Pd/Al_{2}O_{3}\;=\;4$ was found to be better than any other weight ratios in activity and durability. The performance examination of catalysts and of combustion through the plate-type combustor made it possible to be developed the cylindrical-type combustor which has increased combustion area. Catalytic combustion condensing boiler of 25,000 kcal/hr class was also developed, which had the optimum combustion condition at the no221e of 5.95mm and the orifice of 21mm. This condition was determined through the performance experiments of catalytic combustion condensing boiler to which the cylindrical-type catalytic combustor was applied.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.122-122
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• 2014

수중방전을 환경분야에 적용하기 위한 플라즈마 부상법이 개발되었다. 플라즈마 부상법은 물 속에서 발생시킨 플라즈마가 가지고 있는 주요특성 중 물리적 특징인 쇼크웨이브, UV조사, 버블생성 등과 화학적 특징인 OH라디칼 및 염소산화물 생성 등을 이용하여 물 속에 존재하는 용존성 및 입자성 물질을 부상분리 기법으로 제거하는 공법이다. 유기물을 제거하는 기작으로는 침전, 여과, 분해 등이 있고, 이를 구현하기 위한 공정으로 중력침강법, 부상분리법, 멤브레인법, 미생물법 등이 있다. 이 중에서 가압공기부상법은 침강법에 비해 부지면적을 적게 소모하고 처리시간이 50% 이상 감소되는 특징이 있다. 가압공기부상법은 물 속에 공기를 과포화시킨 후 노즐을 통해 재분사할 때 발생하는 압력차에 의해 미세기포가 발생함을 이용하여 유기물을 분리하는 공법이다. 그러나, 가압용 장비 및 반송수가 필요하고, 미생물분리는 불가능한 단점이 있다. 이에 본 연구에서는 미생물살균과 유기물 분리가 동시에 일어나는 플라즈마를 이용한 부상분리기법을 개발하였다. 본 연구에서는 난분해성 용존유기물인 휴믹산 100 mg/L의 플라즈마 공기부상법에 의한 제거능을 확인하였다. 용존성 휴믹산을 입자성 물질로 전환하여 플록을 형성시키고자 알루미늄설페이트(Al2(SO4) $3{\cdot}18H2O$)를 100 mg/L 주입하였고, 침출수와 같이 염도가 높은 물을 모사하고자 35 g/L의 염화나트륨을 첨가한 상태에서 방전을 실시하였다. 방전에 사용된 전원은 EESYS사에서 제작한 펄스형 고전압 전원장치를 사용하였고 최대 15 kW의 출력 중 6 kW의 전력을 인가하였다. 전극 한 개는 2 mm 텅스텐봉을 세라믹튜브로 감싼 구조로 총 사용전극은 28개이다. 전극 한 개당 대략 200 Watt의 전력이 소모되며 이 때 최대의 버블이 생성됨을 확인하였다. 전극 1개에서 생성되는 버블의 부피는 14 mL/min 로 측정되었다. 버블의 크기는 평균 70 um이고 가압공기부상법에서 최적공기크기로 제시하고 있는 40~80 um 의 버블은 약 80% 가량 생성된다. 본 연구에서 사용된 반응시스템에서의 물의 높이는 약 500 mm 이고 전체 40 L의 수조가 3개의 벽으로 분리되어 4개의 수조로 분리되었다. 각 수조는 하부에 7개의 전극을 포함하고 있다. 플라즈마 발생시 생성되는 기포는 약 1분 방전 후에 포화농도에 도달하며 방전종료 후 약 4분간 수체 내에 남아있게 된다. 이를 공정에 적용하여 1분 방전 및 4분 휴지의 순서로 플라즈마를 인가하였다. 휴믹산 용액의 유량을 2 lpm 으로 운전하였을 때 최종 처리율은 94% 이고 이때의 대장균 살균능은 99%이다.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.217-225
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• 2004

This study was performed to provide the basic knowledge about the mushroom cultivation facilities. Classified current status of cultivation facilities in Gyeongnam province was investigated by questionnaire. The structure of Pleurotus eryngii cultivation facilities can be classified into the simple and permanent frame type. The simple frame structures were mostly single-span type, on the other hand, the permanent frame structures were more multi-span than simple structures. And the scale of cultivation facilities was very different regardless of structural type. But as a whole, the length, width and ridge height were prevailing approximately 20.0 m, $6.6\~7.0m$ and $4.6\~5.0m$ range, respectively. The floor area was about $132\~160\;m^2$, and floor was built with concrete to protect mushrooms from various harmful infection. The roof slope of the simple and permanent type showed about $41.5^{\circ}\;and\;18.6\~28.6^{\circ}$, respectively. The width and layer number of growing bed for mushroom cultivation were around $1.2\~1.6m$, 4 layers in common, respectively. Most of year round cultivation facilities were equipped with cooler, heater, humidifier, and ventilating fan. Hot water boiler was the most commonly used heating system, the next was electric heater and then steam boiler. The industrial air conditioner has been widely used for cooling. And humidity was controlled mostly by ultra-wave or centrifuging humidifier. But some farmers has been using nozzle system for auxiliary purpose. More then $90\%$ of the mushroom house had the independent environment control system. The inside temperature was usually controlled by sensor, but humidity and $CO_2$ concentration was controlled by timer for each growing stage. The capacity of medium bottle was generally 850 cc and 1100cc, some farms used 800 cc, 950 co and 1,250 cc. Most of mushroom producted has been usually shipped to both circulating company and joint market.