• 한국산학기술학회논문지
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• 제13권6호
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• pp.2479-2483
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• 2012

본 논문은 휴대 및 이동이 가능한 개인용 소형 산소발생기 개발에 관한 것이다. 소형 산소발생기는 소형 진공펌프에 의해 진공흡착방식으로 작동된다. 각 구성품을 소형화와 경량화에 맞춰 구성하였으며 토출펌프 회전속도, 노즐 직경, 3-way 밸브 작동시간을 변화시키면서 산소농도와 유량을 최적화하였다. 노즐 직경 0.5mm에서 발생된 산소농도는 약 37%이며 유량은 $1{\ell}$/min이다. 노즐로부터 30cm 떨어진 위치에서 약 0.5%의 농도증가 효과가 나타났다.

• 한국정밀공학회지
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• 제17권4호
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• pp.233-239
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• 2000

Investigation results are presented fur the shaft end displacements due to the elastic deformation of the casing and support in double suction centrifugal pump. Suction and discharge nozzles of the pump are subject to external piping loads and, in API 610, maximum values of their components are specified. This means that each nozzle can be subject to various combinations of loading conditions. Considering upper and lower criteria of each load, we must perform for the 4,096 load cases, and assign the direction and range of the loads. So, this paper develops an efficient procedure(Compliance Coefficient Method) to calculate the shaft end displacements(＠ coupling) to determine whether satisfying the pump's standard. Also, we analyzed the effects of the casing and support thickness on shaft end displacements.

• 한국유체기계학회 논문집
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• 제14권1호
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• pp.18-23
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• 2011

The hydraulic part in reactor coolant pump consists of suction nozzle, impeller, diffuser, and discharge nozzle. Among them, impeller is required to be designed to satisfy performance requirements such as head, NPSHR, and head curve slope at design point. Present study is intended to suggest the preliminary design method sizing the impeller size to satisfy the design requirement particularly including head curve slope at design point. On a basis of preliminary design result, hydraulic components have been designed in detail by CFD and then manufactured in a reduced scale. Experiment in parallel with computational analysis has been executed in order to confirm the hydraulic performance. Comparison results show good agreement with design result, confirming the validity of design method suggested in this study.

• Design & Manufacturing
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• 제16권2호
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• pp.26-32
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• 2022

It is known that the fluidized bed incinerator, which is the subject of analysis, shows excellent performance in heat and mass transfer due to excellent mixing and contact performance between fluidized sand and fuel, and also shows relatively good combustion characteristics thanks to good mixing and long residence time for low-grade fuels. have. In this study, air flow analysis is performed to understand the characteristics of co-firing of sludge, waste oil and solid waste in the fluidized bed incinerator, flow characteristics of flue gas, and discharge characteristics of pollutants.The fluidized bed incinerator subject to analysis is a facility that incinerates factory waste and general household waste together with sludge, with a processing capacity of 32 tons/day. to be. In addition, the operation method was designed for continuous operation for 24 hours. As a result, it can be seen that the lower combustion air and the introduced secondary air are changed to a strong turbulence and swirl flow form and exit through the outlet while rotating inside the freeboard layer. The homogeneous one-way flow form before reaching the secondary air nozzle has very high diffusivity with the high-speed jet flow of the nozzle.

• 소성∙가공
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• 제21권5호
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• pp.312-318
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• 2012

With an increasing trend toward miniaturization, electrical discharge machining(EDM) has been receiving a lot of attention as a suitable production technology for micro-parts, since it enables the machining of hard conductive materials with a high degree of repeatability and without alteration to the material. When a micro-hole is fabricated by EDM, however, the diameter of the inlet hole is larger than that of the outlet region due to the additional discharge effect caused by the eroded particles. In this paper, a shot blasting surface treatment, in which an abrasive material is accelerated through a pressurized nozzle and directed at the surface of a part, is suggested as an effective method to reduce the tapered shape of EDM micro-hole. In addition, the influence of process parameters such as spark-on time and electrode diameter on the machining performance was investigated. It is shown quantitatively that the difference in diameter between the inlet and outlet holes decreases with the shot blasting treatment and with decreasing spark-on time.

• 농업과학연구
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• 제11권2호
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• pp.284-294
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• 1984

동력분무기용(動力噴霧機用) 3분두(噴頭) 분공(噴孔)의 크기, 살포각도(撒布角度) 및 와실(渦室)의 간격을 변화(變化)시키면서 최대(最大) 분무유효거리(噴霧有效距離)의 구명(究明)과 살포도(撒布度)의 개선(改善)을 위(爲)한 분두배열(噴頭配列) 방법(方法)의 분석결과(分析結果)는 다음과 같다. 1. 분공(噴孔) 직경(直徑)이 커짐에 따라 분무량(噴霧量)은 증가(增加)하였고 1번구(番口)는 2차(次) 곡선(曲線)으로 II번구(番口), III번구(番口)는 1차(次) 함수관계(關係)를 나타냈다. 2. 최대(最大) 유효거리(有效距離)는 살포각도(撒布角度)가 $15^{\circ}$일때 최대(最大) 값을 나타냈고 분공(噴孔)의 크기가 3.0mm일때 약17m, 2.5mm 및 2.0mm 일때 각각 약 14m, 약 13m로 나타났다. 3. 살포도(撒布度)의 균등개선(均等改善)을 위(爲)한 분두배열(噴頭配列)(表 6참조(參照))은 I번구(番口)의 분공(噴孔)크기에 따라 다르지만 균등계수(均等係數)는 약 6%정도(程度) 개선(改善)시킬 수 있었다. 4. 살포거리(撒布距離) 6m의 최저(最低) 살포량(撒布量)을 II번구(番口)의 와실(渦室) 간격 조절(調節)로서 개선(改善)시킬 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2002년도 제18회 학술발표대회 논문초록집
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• pp.31-32
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• 2002

임계노즐(critical nozzle)은 유동을 유로 최소단면부에서 초크시켜, 질량유량을 계측하기 위한 일종의 유체기구로, 최근 다양한 분야에서 널리 활용되고 있다. 압축성 기체역학의 관계식에 의하면, 임계노즐을 통하는 기체유동의 이론적인 질량유량은 노즐 목의 직경, 노즐 상류의 온도와 압력 그리고 기체의 비열비 등의 함수로 주어진다 그러나 실제 유동에서는 점성과 열전달 등의 초과로 인하여, 이론적 질량 유량과 실제유량의 비 즉 유출계수(discharge coefficient)의 값은 1.0으로 되지 않는다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.678-682
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• 1996

Acoustic emission(AE) is monitored during end milling with a sensor attached to the cutting fluid discharge nozzle. Cutting forces are also measured and compared with the AE signals to examine the reliability of the AE signals. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Moreover, edge chipping and fracture of tools can be successfully detected using both the AE signals and cutting forces.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1993-1996
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• 2011

The vibronically well-resolved emission spectrum was recorded from the corona discharge of precursor 2,3,4-trifluorotoluene in a corona excited supersonic expansion with a pinhole-type glass nozzle using a long-path monochromator in the visible region. From the analysis of the observed spectrum, we found the evidence of the presence of the difluorobenzyl radicals in the corona discharge of the precursor. A possible mechanism is proposed for the formation of difluorobenzyl radicals in the gas phase on the basis of the observed emission intensity of the difluorobenzyl radicals produced.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3389-3394
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• 2011

Isomeric trimethylbenzyl radicals were generated and vibronically excited from precursor 1,2,3,5-tetramethylbenzene, isodurene, with a large amount inert carrier gas helium in a corona excited supersonic expansion (CESE) using a pinhole-type glass nozzle. A long-path monochromator was used to record the visible vibronic emission spectra of the jet-cooled benzyl-type radicals in the $D_1{\rightarrow}D_0$ electronic transition. From the analysis of the spectra, we identified the evidence of the presence of three isomeric trimethylbenzyl radicals in the corona discharge, and obtained the electronic energy and a few vibrational mode frequencies in the ground electronic state for each isomer.