In this paper, a low-noise CMOS Image Sensor (CIS) based on a 14-bit Two-Step Single-Slope ADC (TS SS ADC) and a column self-calibration technique is proposed. The TS SS ADC is good for the video system which requires fast operation because its conversion speed is faster than the Single Slope ADC (SS ADC) by more than 10 times. However, there are a lot of errors in the circuit operation on the connection point between the coarse block and the fine block due to the 2-step composition of the TS SS ADC. This makes it difficult to implement the TS SS ADC into the high resolution more than 10-bit and the product. In order to improve the drawbacks of TS SS ADC, a new 4-input comparator is discussed. Further, a column self-calibration technique to reduce the Fixed Pattern Noise (FPN) is also described. The chip has been fabricated by Samsung 0.13μm CIS technology. The measured conversion time of the ADC is 17μs and the high frame rate of 120 frames/s (fps) is achieved at the VGA resolution. The measured column FPN is 0.38LSB, and it is much lower than the other reported ones.

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For the construction of ecofriendly ships, fuels such as liquefied natural gas (LNG), ammonia, and hydrogen are being discussed as alternatives. LNG fuel has recently been applied to shipbuilding. The most important aspect of an LNG propulsion ship is the LNG storage tank, because LNG is stored at a high pressure and low temperature. Cryogenic steels are needed to evaluate safety in weld joints, especially the LNG storage tank which has a dissimilar weld joint with a STS pipe. The dissimilar weld joint has a complex welding residual stress distribution. It is necessary to evaluate the effects of temperature changes that occur during the loading–unloading process of LNG. In this study, the residual stress distribution characteristics of heterogeneous welding parts welded to STS pipes using 9% Ni steel, STS, and high-manganese austenitic steel in an LNG storage tank were investigated through experimental and analytical methods. The thermal stress due to the difference in thermal expansion coefficient between cryogenic steel and the STS pipe occurred with a small amount in loading–unloading of LNG. When high-manganese austenitic steels and the STS pipe were joined, tensile stress was generated at the dissimilar weld joint owing to the temperature difference generated during the LNG loading–unloading process. STS has a homogenous weld joint and identical thermal expansion coefficients; therefore, the shrinkage and expansion were not affected by the temperature change. The welding residual stress at the dissimilar weld joints was measured via an experimental cutting method, and the results indicated that the tensile residual stress had distribution similar to the yield stress of the material. The stress generated by the temperature change and the welding residual stress overlapped and occurred during the loading–unloading process of the LNG tank; however, the final tensile stress below the tensile stress was distributed in the storage tank.

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