• 한국정밀공학회지
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• 제5권1호
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• pp.63-70
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• 1988

Laser cutting system uses a gas jet to remove the molten or varpozed material from the workpiece. The quality of the laser cut can be strongly influenced by the gas flow charac- teristics formed through the nozzle. Laser cutting experiments were carried out for SS41 and SUS 304 to investigate the relationship between cut quality and cutting pressure. The cutting speed, nozzle pressure and nozzle to workpiece distance were also considered. The cut specimens were inspected by various manners such as dross observation, surface roughness test and kerf width measurement. Based on the data of pressure measurement on workpiece and the results of cut surface inspection, the influence of the considered cutting conditions on cut quality could be evaluated. The results of this study will be valuable in planning the optimal laser cutting process and in designing the laser cutting nozzle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1116-1120
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• 2004

In the nuclear power plant, there are several cylindrical vessels such as reactor vessel, pressuriser and so on. The vessels are usually constructed by welding large rolled plates, forged sections or nozzle pipes together. In order to assure the integrity of the vessel, these welds should be periodically inspected using sensors such as ultrasonic transducer or visual cameras. This inspection is usually conducted under water to minimize exposure to the radioactively contaminated vessel walls. The inspections have been performed by using a conventional inspection machine with a big structural sturdy column, however, it is so huge and heavy that maintenance and handling of the machine are extremely difficult. It requires much effort to transport the system to the site and also requires continuous use of the utility's polar crane to move the manipulator into the building and then onto the vessel. Setup beside the vessel requires a large volume of work preparation area and several shifts to complete. In order to resolve these problems, we have developed an underwater mobile robot guided by the laser pointer, and performed a series of experiments both in the mockup and in the real reactor vessel. This paper introduces our robotic inspection system and the laser guidance of the mobile robot as well as the results of the functional test.

• KSTLE International Journal
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• 제3권2호
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• pp.101-109
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• 2002

This paper presents the fabrication and performance inspection of a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of base plate, mid plate, top plate and connection tubes fur inlet and outlet. In detail, the base plate is composed of two diffuser nozzles and three chambers, the mid plate consists of a glass diaphragm for the volumetric change of the pumping chamber. The inlet and outlet tubes are connected at the top plate and the actuator fur pressing the diaphragm is located beneath the top plate. The micropump is fabricated on the silicon wafer by DRIE (Deep Reactive ion Etching) process. The pumping performances are tested by the pneumatic test rig and compared with the simulated results fur various dimensions of diffuser nozzles. The pumping characteristics of the micropump by the volumetric change at the pumping chamber is modeled and simulated by the commercial software of FLOW-3D. The simulated results shows that reverse flow is the inherent phenomena in the diffuser nozzle type micropump, but it can be reduced at the dual pumping chamber model.

• 한국터널지하공간학회 논문집
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• 제13권1호
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• pp.1-8
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• 2011

장대 도로터널 및 위험도가 높은 도로터널에 설치되고 있는 물분무소화설비는 성능과 관계된 단위면적당 방수밀도에 대한 검증과정이 없이 사용되어 왔다. 본 연구는 도로터널에 물분무소화설비에 노즐을 설치하여 기준압력에서 방수시험을 실시하여 기준을 만족하는지 여부를 확인하였다. 결론적으로 모든 노즐이 기준을 만족하지 못하였다. 이런 결과는 도로터널용 물분무노즐을 검증하는 시험기준이 없고, 실제 시험을 통한 검증 과정이 존재하지 않았기 때문이라고 판단된다. 따라서 물분무노즐의 성능을 시험할 수 있는 기준의 마련과 설치된 시설을 검증하는 제도적인 보완이 필요하다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
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• pp.117-121
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• 1998

The Rapid Expansion of supercritical fluid Solutions (RESS) process was applied to particles coating. Experiments were conducted in a fluidized bed with an internal nozzle in the center of the reaction tube. Microcapsules (mean particle size : 49$\mu\textrm{m}$) prepared by spray drying method were used as the core particles. Supercritical CO2 solutions of paraffin were expanded through the nozzle in to the bed that was fluidized by air. Surface morphology prepared particles was observed by SEM. For the inspection of particle size change, particle size distributions were measured before and after coating. The releasing behavior of Mg2+ ions inspected by AA.

• 한국화재소방학회논문지
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• 제29권2호
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• pp.84-91
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• 2015

본 연구는 소방펌프차에서 사용 중인 라인프로포셔너 방식의 포 소화설비에 대하여 노즐의 구경변화에 따른 포 수용액의 압력, 유량 및 농도의 변화에 대한 실험적 연구로 실험 데이터를 이론적 계산을 수행함으로써 포 소화약제 성능인증기준에 적합한 폼 흡입 노즐의 흡입측 압력 및 폼 흡입 니플의 구경 모델을 제시하고자 한다. 실험 장치는 소방방재청 고시 제2012-81호 제8조(기능시험) 규정을 바탕으로 실험 장치를 구성하였으며, 포 소화약제는 수성막포 3%를 사용하였고, 혼합장치는 현재 소방관서에서 사용 중인 폼 픽업식 라인프로포셔너 혼합장치 구경 40 mm를 사용하였다. 본 연구를 통하여 라인프로포셔너 혼합장치의 인입측 압력 변화 및 폼 흡입 니플 구경의 변화에 대하여 폼 흡입 노즐의 구경이 4 mm일 때 노즐 흡입측 압력은 0.25~0.35MPa 범위 내에서 이론적 포 소화약제 성능 인증 기준에 적합함을 증명할 수 있었다. 또한 폼 흡입 노즐의 구경이 5 mm일 때는 폼 흡입 노즐의 구경이 4 mm일 때 보다 높은 압력 0.45~0.60 MPa 범위 내에서 포 소화약제 성능 인증기준에 적합한 것으로 나타났다.

• 한국염색가공학회지
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• 제20권1호
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• pp.48-56
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• 2008

A real-time inspection system has been developed by combining CCD based image processing algorithm and a standard lighting equipment. The system was tested for defective fabrics showing nozzle contact scratch marks, which are one of the frequently occurring defects. Two algorithms used were compared according to both their processing time and detection rate. First algorithm (algorithm A) was based on morphological image processing such as dilation and opening for effective treatment of defective printing areas while second one (algorithm B) mainly employs well-defined edge detection technique based on canny detector and Zermike moment. It was concluded' that although both algorithms were quite successful, algorithm B showed relatively consistent performance than algorithm A in detecting complex patterns.

• 대한기계학회논문집A
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• 제36권9호
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• pp.1047-1052
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• 2012

가압경수로형 원전의 Alloy 600 원자로압력용기헤드 관통노즐 및 Alloy 82/182 이종금속 맞대기 용접부에서 일차수응력부식균열(PWSCC)이 보고된 이후 전 세계적으로 PWSCC에 의한 용접부 파단을 예방하기 위해 강화검사를 적용하고 있다. 본 이종금속용접부에 대한 가동중검사에서 균열이 발견된 경우 건전성평가 결과가 도출되기까지 발전소가 정지 상태에 있게 됨에 따라 원전 이용율 저하가 발생할 수 있는데, 이를 예방하기 위해서는 균열건전성평가 관련 기술의 정립뿐만 아니라 신속하게 평가 결과를 도출할 수 있는 시스템의 구축이 필요하다. 본 연구에서는 이종금속 맞대기 용접부를 대상으로 진행하고 있는 PWSCC 균열건전성평가 기준 정립 및 전산 시스템 개발 결과를 제시하였다. 본 연구를 통해 이종금속 맞대기 용접부 PWSCC 균열건전성평가 기술이 정립되고 전산 시스템으로 구현되어 원자로압력용기 주변 이종금속 맞대기 용접부에서의 PWSCC 균열에 대한 기술적 건전성평가 수단을 확보하였다.

• 대한기계학회논문집A
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• 제24권2호
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• pp.386-393
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• 2000

Fracture mechanics analysis (FMA) is an essential work for integrity evaluation of nuclear power plant. The flaws inspected by In-Service Inspection(ISI) should be confirmed by FMA for the decision of the operation status of stop or continuance. The basic data for FMA are the stress of the interested area. The purpose of this research is to develop a system which can obtain stress data efficiently based on various database. Mesh generation program generates mesh using MSC/PATRAN and provides input file for finite element analysis according to the databases (shape, dimension, transient and material). The stress data from the finite element analysis are stored to be stress database so that it can be applied to FMA. As an example, the system developed by this study is applied to pressurizer nozzle and confirmed to be a useful tool for efficient FMA.

• International Journal of Aeronautical and Space Sciences
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• 제4권2호
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• pp.51-60
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• 2003

An experimental research program is being undertaken to develop a regeneratively-cooled experimental thrust chamber of liquid rocket engine using liquefied natural gas and liquid oxygen as propellants. Prior to firing test using a regenerative cooling with liquefied natural gas in this program, several firing tests were conducted with water as a coolant. Experimental thrust chambers with a thrust of about 10tf were developed and their firing test facility was built up. Injector used in the thrust chamber was of shear-coaxial type appropriate for propellants of gas and liquid phase and cooling channels are of milled rectangular configuration. Periodical variation of the soot deposition and discoloration was observed through an eyes' inspection on the inner wall of a combustion chamber and a nozzle after each firing test, and an intuitive concept of the periodical variation of mixture ratio near the inner wall of a combustion chamber and a nozzle at once was brought about and analyzed quantitatively. Thermal heat flux to the coolant was calculated and modified with the periodical variation model of mixture ratio, and the increment of coolant temperature at cooling channels was compared with measured one.