• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.118-124
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• 2017

To investigate and analyze the cause of the failure of the connecting rod bolt and the crank pin bearing bolt of the diesel engine of this study, the following results were obtained through site surveying, the investigation of literature referring to similar failures, testing and inspection of the fracture surface, and the experience of the researchers. The fractured crank pin bearing bolt of the diesel engine is estimated to be damaged later than the connecting rod bolt. From the shape of fracture surface, it is evident that the failed connecting rod bolt is fractured by fatigue failure due to abnormally repeated loads (e.g. loosening of the connecting bolt, etc.), and is not failed by brittle fractures due to the impact load. The surface of the U-nut on the fractured connecting rod bolt has been worsening due to the improper use of lubricant (agent for prevention of thread fixing) and no usage of separating the each connecting rod on each cylinder. Moreover, there is the possibility that those poor surface conditions of the fractured connecting rod bolt have affected the failure of the connecting rod bolt of the main engine. And it could be assumed that the mechanical characteristic and manufacturing process of the failed connecting rod bolt and crank pin bearing bolt, which were made by a domestic company, conform to the design requirements for those bolts.

• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.147-152
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• 1979

Nitrite, one of the precursors of dimethylnitrosamine, distributes widely in natural foods and is also used as a color fixing agent in meat products. This experiment was carried out to determine the contents of nitrite and nitrate of Korean foods and suman saliva. Nitrite content was measured by use of the diazotization-coupling reaction, while cadmium reduction method by use of metallic cadmium was applied to determine nitrate. The objects are about 150 of female students who are $19{\sim}22$ years old ands standard analytical values of nitrate contents of $10{\sim}20$ samples produced in various places. The results showed that contents of nitrite and nitrate of Korean foods and saliva were relatively high levels.