Unfortunately leaks occur in heat exchangers periodically, usually at the tube to tubeplate joint. The usual method of repair is to plug off the defective area and isolate the tubes of concern from the circuit. If the leaks continua the thermal capacity of the units is progressively reduced and for this reason the alternative of using an internal bridging sleeve has been examined. This paper discusses the overall development activities that has been found necessary to bring this repair procedure to a successful conclusion for use on the nuclear steam generator. In this work we have investigated optimum explosives and explosive quality, explosive sleeving's thickness, the design of sheath stress relieving heat treatment pull-out load, hydraulic leakage, stress corrosion cracking properties. The results obtain are as follows : (1) The optimum explosives and explosive qualities are PETN and about 15~40 gr/ft of explosive sleeving in nuclear steam generator. (2) Explosive sleeving's thickness is 1.1~l.4mm, If groove of 0.35mm formed in sleeve outside existed, For the hydraulic leakage is go up, explosive sleeving of formed groove are applicate tube and turnplate. (3) If the stress relieving heat treatment are experiment in $750^\circ{C}$, $850^\circ{C}$, 15 minutes Pull-out strength of sleeving 1,500~2,300kg, hydraulic leakage is $250kg/cm^2$.

The explosive forming has been used for many year to expand tubes into tubesheets. this process has demonstrated ability to direct carefully the energy of an explosive to expand tubes into tubesheet holes without damaging the tubesheet and without causing the excessive cold work at the tube I.D. that is normally associated with mechanical expansion. The success of explosive tube expansion provided the background for the development of the explosive tube plug. The main results are as follows : (1) The optimum explosives and explosive qualities are PETN, RDX, HMS and about 18~31gr/ft of explosive plugging in nuclear steam generator. (2) Explosive plugging's thickness is 0.9~1.8mm. If groove of 0.4 mm formed in plug outside, For the hydraulic leakage is go up, explosive plugging of formed groove are applicate tube and tubrplate. (3) Sheath is designed on the polyethylene of low density, In thermal impact test of the $430^\circ{C}$, hydraulic leakage is $300kg/cm^2$. (4) About 10~60mm oxide inclusions are existed on the space of explosive plug and tube protect to the leakage.

This study deals with interface charactristics of tube and tubesheet of the nuclear steam generator by the explosive expansion in order to take advantage of optimum expansion ratio, pull-out strength and leakage tightness and improvement of the resisitance on the stress corrosion cracking for low residual stress. The paper also show the relationship between roll, hydraulic and explosive expansion. The results obtain are as follows (1) Because of the explosive bonding is to use the high speed pressure and energy by the explosive, workability is good, bonding region is homogenous (2) Expansion ratio is 2.7%, Pull-out strength 850kg, Leakage strength $500kg/cm^2$. Clearance gap is 10~30mm in case of explosive expansion and interface structure of the tube and tubesheet is optimum condition. (3) As the transition region of the explosive expansion is inactive, the resistance of the stress corrosion cracking is increases 30~40% compare to the roll and hydraulic expansion.

터널굴착으로 발생되는 지반침하는 지상구조물의 변형을 유발할 수도 있으므로 터널굴착전에 지상구조물의 안전성 평가가 선행되어야 한다. 이러하여 본 연구에서는 전문가의 포함된 터널현장의 지표침하를 예측하고, 이를 기반으로 지상구조물의 안전성 평가를 수행하는 전문가 시스템 NESSS(Neural network Export System for Adjacent Structure Safety Analysis)를 개발하였다. NESASS는 인공신경망을 이용하여 기존 터널현장의 지표침하 계측자료로 작성된 데이터베이스 자료를 학습자료로 하여 학습을 수행하고, 이를 기반으로 터널현장의 지표침하 트라프를 추론한다. 또한 추론된 지상구조물 기초부 변형을 기반으로 계산된 평가 매개변수(angular distortion 등)의 혀용 한계치를 이용하여 건물의 안전성을 평가하고 Dulacska의 균열평가 모델을 이용하여 지상구조물의 균열양상을 예측한다. 따라서, 본 연구에서는 지표침하의 주 영향인자들을 선정하고 이를 분류항목으로 이용, 서울지하철 일부구간의 지표침하 계측자료를 수집, 정리하여 데이터베이스화를 추진하였다. 그리고 인공신경망 구조에 관련된 매개변수 연구를 수행하여 개발된 NESASS의 인공신경망 구조의 신뢰도를 확인하였으며 기수행된 침하계측 결과치와 비교하여 지표침하 예측능력도 조사하였다. 또한 NESASS를 이용하여 실제 터널현장을 모델로 설정, 지상구보물의 안전성 평가를 수행해 봄으로써 NESASS의 실무적용성을 아울러 확인하였다.