• 한국안전학회지
• /
• 제25권6호
• /
• pp.161-168
• /
• 2010

A series of fatigue tests have been performed on the non-load carrying fillet welded joints in order to quantitatively assess the fatigue characteristics due to the grindings and TIG(Tungsten Inert Gas) welding treatments. From the results of fatigue tests, it has been shown that the fatigue strengths at $2{\times}106$ load cycles were improved in the case of the grinding sand TIG welding treatments, and we could know that it is satisfying fatigue strength prescribed in fatigue design standard in general. Besides, from the results of fracture mechanics approaches, the geometric shape correction factors were the most dominant factors in the initial fatigue crack growth, but as the fatigue crack develops, the finite plate correction factor were became the most dominant factor, and the fatigue life on non-load carrying fillet welded joints could be relatively exactly estimated by using the relations between fatigue crack growth rate and stress intensity factor obtained from finite element analysis and existing proposed formulae.

• 한국강구조학회 논문집
• /
• 제11권3호통권40호
• /
• pp.319-327
• /
• 1999

본 연구는 필렛용접 이음으로 된 종리브 십자 시험체를 대상으로 용접토우의 후처리에 의한 피로강도 향상의 메커니즘을 밝히고, 적절한 후처리법을 제안하고자 한다. 인장피로시험 결과, 용접 그대로의 시험체 보다는 후처리된 시험체들에서 피로강도 향상이 보였다. 특히, 피로균열 발생수명 $N_c$는 해머피닝(Hammer-Peening)후 그라인더 처리를 한 시험체에서, 그리고 피로균열 진전수명 $N_p$는 해머피닝 시험체 들에서 각각 증가현상을 보였다. 여기서, $N_c$는 용접토우의 기하학적 형상, 즉 응력집중의 완화때문에, 또한 $N_p$는 해머피닝에 의해 표면에 도입된 큰 압축잔류응력이 피로균열의 진전을 억제하고 있기 때문이라고 생각된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1521-1524
• /
• 2003

Currently the plates used for the various structures has a tendency to being slim to the degree of the sheet metal vis-a-vis the overall measurements of the structure, and the conditions of their usage and load have been getting diverse. As the structure material has been used more and more under the various conditions, the necessity of the strength analysis is to be required. While most of these methods are simply based on the strain gaging method; that is, directly attaching most of the material to the gage, using the non-contact method is still in the early stage. One of the non-contact methods is by the use of the laser that has high-level of the accuracy for the measurement, and this laser also has excellent characteristics on which many studies for its applications are focused throughout the many fields. Therefore, this dissertation is on the measurement of the strain caused by the characteristics of the TIG welded zone which is used with 3D ESPI system that is functionally modified through the laser ESPI system.

• 한국독어학회지:독어학
• /
• 제10집
• /
• pp.155-174
• /
• 2004

Wir $k\"{o}nnen$ die $Ged\"{a}chtnisforschungen$ mit Fremdsprachenlernen $verkn\"{u}pfen$. Ein Lernprozess ist gerade einer vom $Ged\"{a}chtnisprozess$. $F\"{u}r$ einen erfolgreichen Fremdsprachenunterricht ist es $n\"{o}tig$, dass beim Lernprozess ein Sprachwissen vom deklarativen $Ged\"{a}chtnis$ ins prozeduale $Ged\"{a}chtnis$ $\"{u}bertragen$ wird. Aber ein Lernerfolg ist je nach dem Individiuum anders. d.h. der unterschiedliche Lerneffekt zwischen Lemenden $h\"{a}ngt$ eventuelle von $pers\"{o}nlichen$ Erfahrung und von dem episodischen $Ged\"{a}chtnis$. Beim Lernprozess muss Sprachwissen vom deklarativen $Ged\"{a}chtnis$ zum prozedualen $Ged\"{a}chtnis$ $\"{u}bertragen$ werden, um Fremdsprachen zu beherrschen. Inzwischen spielen implizites $Ged\"{a}chtnis$ und episodisches $Ged\"{a}chnis$ wichtig Rolle beim $\"{U}bertragungsprozess$. $Daf\"{u}r$ zeigen wir Lernstrategie der Tempusverwendung in Bezug auf die $Ged\"{a}chtnisforschung$. Mit welchem Tempus will man seine Intention im Text $ausdr\"{u}cken$? $Daf\"{u}r$ zeigen wir ein einfaches Spiel $f\"{u}r$ den Fremdsprachenunterricht. Das ist das Spiel zur Strategie der Tempusverwendung bei der Textproduktion $f\"{u}r$ das reportiv-orientierte Thema. Unsere Untersuchung der Tempera kann besonders im Fremdsprachenunterricht dizu beitragen, dass der Lernende als Produzent einerseits unter Berucksichtigung der Textsorte, der zeitlichen Orientierung des Theams und der Sprecherabsicht bei der Textproduktion die Tempera ohne $Z\"{o}gern$ $ausw\"{a}hlen$ und benutzen kann und dass der Lernende als Rezipient auch durch das Erlernen der verschiedenen Funktionen der Tempera versteckte Absichten des Produzenten richtig verstehen kann. Unsere Untersuchung kann in diesem Sinne hinsichtlich der Tempusfunktion bei der erfolgreichen Erweiterung der kommunikativen $F\"{a}higkeiten$ im Unterricht behilflich sein.

• 열처리공학회지
• /
• 제35권3호
• /
• pp.121-129
• /
• 2022

Recently the growth of the renewable energy production has caused the flexible operation in LNG combined cycle power plant. Due to the rapid start and stop operations, large CrMoV castings used for turbine casings and valve bodies could be distorted and lead to replacement or welding repair. This study was performed to find out the characteristics of the repair welding for a damaged CrMoV casting steel. A typical field repair method (arc & TIG welding) was applied to making specimens. The degraded N2 packing head sample from the steam turbine was used. The evaluations of weldments were carried out in terms of microstructural characterization, microhardness measurements, tensile, creep-rupture and fatigue tests. Color etching was also applied for better understanding of welding microstructures. As the boundary between HAZ and base material was deteriorated by welding, it caused microstructural changes formed during PWHT and the shortening of the remaining residual life. By comparing the properties according to repair welding method, it was possible to derive what important welding factors were. As a result, arc welding method is more suitable for repair welding on CrMoV castings.