• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.7-11
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• 1997

직경 3.5 cm, 길이 1.5 m 의 석영관 내에서 염화제1철 증기를 수소로 환원하여 철 초미립자를 제조하였다. 염화제1철의 증발조건, 염화제1철 증기와 수소의 혼합방법, 반응물의 예비가열온도, 반응온도, 염하제1철의 농도, 반응기내 체류시간이 생성된 철 입자의 크기 및 크기분포에 미치는 영향을 조사하였다. 철 입자의 평균직경은 40-88 cm 이고, 기하표준편차는 1.4 정도로 나타났다. 철 입자들은 자기적 성질에 의해 서로 연결되어 체인을 형성하였으며, 전자회절분석 결과 단결정이었다. 평균입경 55nm 철 입자들의 항자력은 900 Oe, 포화자화값은 130 emu/g 이었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.732-738
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• 2004

One of the main degradation mechanisms in steam generator tubes is stress corrosion cracking induced by residual stress. The resulting damages can cause tube bursting or leakage of the primary water which contains radioactivity. Shot peening technique has been used to prevent stress corrosion crack growth in steam generator tubes. In order to investigate the shot peening effect on stress corrosion cracking stress intensity factors are calculated for the semi-elliptical surface crack which is located in residual stress region. The residual stress distribution in steam generator tubes is obtained from the simple model proposed by Frederick et al.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.828-833
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• 2001

In this study, an analysis tool to assess the susceptibility of steam generator tubes due to the flow-induced vibration was developed. The fluid-elastic instability analysis of the U-tube bundle for CE-type steam generator was accomplished. The effective mass distribution along the U-tube was obtained to calculate the natural frequency and dynamic mode shape. Finally, stability ratios for selected tubes are obtained.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.37-43
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• 2009

This paper is performed to develop a tripple-tube exchanger which can improve the system efficiency. Three different tube diameters are compacted by one body(tripple-tube) to recover waste heat from heat exchanging among the fluids. With this, the tripple-tube shows higher cooling capacity than the double-tube after comparing between those two systems. The results of this paper are basic data to design the optimum tripple-tube heat exchanger.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.921-926
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• 2002

In this study, we investigate the plugging effect on the CE type steam generator tube. The natural frequency and mode shape will be changed due to decrease of the effective mass distribution along the tube. We compared the variation of stability ratio for plugged tube with that for unplugged one. The natural frequency increased because of removing the cooling water inside the steam generator tube, but the stability ratio decreased inversely because of changing the vibrational model shape. We also investigated the turbulent excitation effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.927-932
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• 2002

The stability ratio and vibrational amplitude of each tube inside a steam generator have different values. We estimate the characteristics of flow-induced vibration for CE type steam generator with various column and row number of the tube. To obtain the thermal-hydraulic data and stability ratio we use the ATHOS3-MODI and PIAT-FEI/TE code respectively. It turns out that the steam generator has a bounded central zone with the distributed values of the stability ratio and the vibrational amplitude, and those values across the zone boundary become decreased.

• Tribology and Lubricants
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• v.7 no.2
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• pp.13-21
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• 1991

선박은 사람이나 화물을 수상(水上) 운송수단의 목적으로 오랜 옛날부터 사용하여 왔으며, 금세기에 이르러서는 오랜 옛날부터 사용하여 왔으며, 금세기에 이르러서는 인류문화의 급속한 발전에 따라 주변생활이 가속화(Speed화), 합리화되어 문명의 혜택을 보다 많이 누리게 된 반면에, 국제간에 파생되는 여러가지 교환현상을 바탕으로 지구는 하나의 촌(村)으로 되어 유통경제를 지배하고 이용하는 운송수단으로 발전되어 왔다. 물질문명이 급속히 발전하는 작금, 선용추진 주 기관의 동향을 살펴보면, 1981년 세계에서 건조한 2000톤급 이상의 선박은 940여척으로 이중 13척이 증기 Turbine. 추진(推進), 나머지는 미끄럼 저속 디이젤 또는 중고속 디이젤 추진으로 되어있다. 이와 병행하여 선박에 쓰여지고 있는 각종 윤활제는 주기관으로서 디이젤 engine, Trubine engine, 가솔린 engine, 석유, engine, 선외기, 왕복동 증기기관, Journal계열로서 역전기, 추력베어링, 중간 베어링, 프로펠러베어링, 일반상선으 보조기계로서 발전기, 공기압축기, Boiler, 각종 Pump, 각종 Motor, 냉동기, 조타장치, Side Thrust, 갑판기계, 환기용 송풍기 및 통풍통, Oil 청정기, 수밀로(水蜜爐), 소화설비, 주기 개방용 천정 크레인, elevator, 어선으로서의 주 기관, 보조기기 등에 쓰여지고 있으며 이밖에 수중날개선 등에도 적용되는 등 실로 다양다종한 윤활제가 요구되고 있음에, 본 논고에서는 제목 건을 중심으로 한 선박과 윤활의 중요 Point만을 간추려 기술하고져 한다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.56-63
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• 2014

In this research, burst tests for axial notched steam generator tubes were conducted. To measure the burst pressure of notched tubes, a burst testing system was manufactured. The tests were conducted under internal pressure at room temperature. Part-through-wall and through-wall notches which have various geometries with different depths and lengths were machined by electro-discharged-machined(EDM) method. The burst pressure decreased exponentially with increasing notch length and decreased almost linearly with increasing notch depth. A comparison of the burst pressure with existing burst pressure solutions for cracked tube show that the existing solution agree well with the test results.

• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.33-40
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• 2014

In this study, a new model for calculating the liquid film thickness and condensation heat transfer coefficient in a vertical condenser tube is proposed by considering the effects of gravity, liquid viscosity, and vapor flow in the core region of the flow. In order to introduce the radial velocity profile in the liquid film, the liquid film flow was regarded to be in Couette flow dragged by the interfacial velocity at the liquid-vapor interface. For the calculation of the interfacial velocity, an empirical power-law velocity profile had been introduced. The resulting liquid film thickness and heat transfer coefficient obtained from the proposed model were compared with the experimental data from other experimental study and the results obtained from the other condensation models. In conclusion, the proposed model physically explained the liquid film thinning effect by the vapor shear flow and predicted the condensation heat transfer coefficient from experiments reasonably well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.390.1-390
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• 2002

In this study, we investigate the plugging effect on the CE type steam generator tube. The natural frequency and mode shape will be changed due to decrease of the effective mass distribution along the tube. We compared the variation of stability ratio for plugged tube with that fur unplugged one. The natural frequency increased because of removing the cooling water inside the steam generator tube, but the stability ratio decreased inversely because of changing the vibrational mode shape. We also investigated the turbulent excitation effect.