• 상하수도학회지
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• 제23권5호
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• pp.517-526
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• 2009

This research has been conducted to investigate the characteristics of hydraulic behavior within the PAC contactor, the rectangular shape sedimentation basin without inclined tube and the other one with inclined tube those are parts of demonstration plants(capacity : $2,000m^3/d$) in Korea Institute of Water and Environment. As results of tracer tests, the flow within PAC contactor was evaluated to divided into plug flow and dead space distinctly, and characteristics of dead space was close to that of CSTR(Complete/continuous Stirred Tank Reactor). Also, considering Reynolds number, Froude number, Morill, Modal, NCSTR Inex and plug flow/mixed flow fraction, in the case of the rectangular shape sedimentation basin without inclined tube, the characteristics of flow pattern was close to CSTR. On the other hand, in the case of the basin with inclined tube, the region of CSTR decreased precisely compared with the case of no-tube. Until now we have recognized that the inclined hydraulic structure just reduces the surface loading rate within a sedimentation basin. Actually besides, the inclined structure have an important effect on the hydraulic behavior within the basin.

• 소성∙가공
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• 제26권1호
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• pp.11-17
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• 2017

In this study, process analysis of elbow-shaped tubes using a mandrel has been performed. To reach the final shape within the dimensional tolerance, the process analysis has been performed at various processing parameters such as tube dimensions, the curved cutting surface and the radius of curvature. The area outside the boundary of the target shape was expressed as a quantitative index to analyze the formability. The validation experiments have also been performed in order to increase the reliability of the process analysis. For the processing of elbow-shaped tubes, it is preferable to make the angle of the portion where the punch touches the tube smaller than the opposite angle. And the convex cutting surface is advantageous due to the increased contacts between the punch and the tube ends during the bending process. Elbow tube having larger radius of curvature shows higher dimensional accuracy due to the relatively uniform strain distribution.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.381.2-381
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• 2002

• 한국방사선학회논문지
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• 제11권4호
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• pp.247-252
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• 2017

조영제의 혈관외유출을 한번이라도 경험한 방사선사들은 혈관외유출의 발생에 대한 두려움으로 검사하는 동안 정신적 고통을 수반하게 된다. 환자의 경우 심한 신체적, 정신적 고통과 의료진 및 의료에 대한 불신을 갖게 되므로 미연에 예방할 수 있는 방안의 마련이 무엇보다 필요하다. 따라서 본 연구에서는 조영제 주입 시 압력인 PSI를 낮추어 혈관외유출을 예방하고자 하며 그 방안으로 자동주입기와 환자의 정맥주사바늘에 연결되는 Y자 형태의 연결관(connecting tube)의 직경에 따른 조영제 주입 시 PSI의 변화를 비교 분석하고자 하였다. Y형태의 연결관 직경이 약 2 mm 정도인 A제품의 경우 전체 평균 연령의 PSI는 98.5, 표준편차 9.72로 나타났다. 연결관 직경 약 3 mm 정도인 B제품의 경우 전체 연령의 평균 PSI는 62.0, 표준편차 8.59로 나타났다. 이것은 직경이 더 넓은 B제품의 경우 A제품과 비교했을 때 평균압력이 37.05% 감소한 결과이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.148-151
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• 2003

The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner groove tube. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

• 한국정밀공학회지
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• 제16권7호
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• pp.24-31
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• 1999

Bulging is a forming method to shape of die cavity by using hydraulic pressure in tube or vessel. Bulging machine and die were developed in order to produce vessel for keeping warm. Bulging machine is a double type with two horizontal cylinders for bulging of two pieces at the same time. The developed die system has one bulging die and two drawing dies for necking at the both ends of tube. The diameter of tube expands by hydraulic pressure in tube. at the same time, thrust at the both ends of tube. pushes tube in the direction of expansion to obtain high expanding rate with no crack. In this study, the bulging properties were investigated to solve tube crack and necking in manufacturing vessel by the combination method of bulging and drawing. As a result, high expanding rate of tube radius without crack, precision necking and high productivity were obtained.

• International Journal of Precision Engineering and Manufacturing
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• 제2권4호
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• pp.40-46
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• 2001

Bulging is a forming method to shape die cavity by using hydraulic pressure in tube or vessel. Bulging machine and die were developed in order to produce vessel for keeping warm. Bulging machine is a double type with two horizontal cylinders for bulging of two pieces at the same time. The developed die system has one bulging die and two drawing dies for necking at both ends of the tube. The diameter of tube expands by hydraulic pressure in tube. At the same time, thrust at both ends of the tube pushes tube in the direction of expansion to obtain high expansion rate with no crack. In this study, the bulging properties were investigated to solve tube crack and necking in manufacturing vessel by combining bulging and drawing. As a result, high expanding rate of tube radius without crack, precision necking and high productivity were obtained.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1107-1112
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• 2006

The purpose of this study is a heat transfer coefficient test of evaporator tube in shell and tube heat exchanger by shapes, using R-404A. The experimental apparatus is designed to simulate the real heat transfer rate in one shell and tube heat exchanger. The test section is formed four type tubes that are Inner ridged tube, Corrugated tube, Turbo-C tube, Inner fin tube and shell type is formed by electrical heater. All tests were performed at a fixed refrigerant evaporator temperature at $1.5^{\circ}C,\;-3^{\circ}C$ and with mass fluxes of 29, 25 kg/hr. Heat transfer rate is calculated a enthalpy difference in test section. In experiment, heat transfer coefficient measured one by one and electrical heaters are supplemented by evaporator.

• 설비공학논문집
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• 제24권7호
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• pp.553-559
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• 2012

A plate-fin heat exchanger is a type of heat exchanger widely used in air conditioners, and tubes and fins are tightly assembled by the mechanical expansion process of tubes. The tube expansion process deforms the grooves inside the tube, and the groove shapes also affect the adhesion between tubes and fins. In this study, the adhesion and heat transfer performance affected by the tube expansion of the non-uniform groove shape tube with different heights are investigated by both analysis and experiments. From the analysis method, it was shown that the contact pressure of non-uniform groove tube is higher than that of the uniform groove tube, and the most appropriate high groove number of the non-uniform groove tube is designed for the maximum contact pressure. From the experimental results, the decreasing rate of the condensation heat transfer coefficient is smaller in the non-uniform groove tube with different heights, compared to the conventional uniform groove tube. Also, the air-side heat transfer coefficient of the non-uniform groove tube with different heights is higher than that of the uniform groove tubes.

• 대한토목학회논문집
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• 제36권1호
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• pp.85-96
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• 2016

본 연구에서는 채움모듈 형태에 따른 준설토의 퇴적분포와 튜브 형상 그리고 토목섬유 튜브의 수침조건에 따른 튜브 내 준설토의 콘 관입 저항특성을 규명하고자 일련의 시험을 수행하였다. 채움모듈 형태에 따른 아크릴 토조와 비닐 튜브 준설토의 퇴적분포를 관찰한 결과 I형 채움모듈은 분화구형상을 나타내고 역T형 채움모듈은 수평방향으로 균등하게 준설토가 퇴적되는 것으로 나타났다. 새만금 내부로부터 채취한 준설토의 채움 단계 별 튜브의 변형은 튜브로부터 배수가 종료됨과 거의 동시에 튜브의 변형이 수렴되고, 토목섬유 튜브 내 준설토의 콘 저항치는 배수의 경우가 수침 보다 2~6배정도 크게 나타났다.