• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.71-78
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• 2023

In general, electric submersible pumps (ESPs), which have an average life of 1.0 to 1.5 years, experience a decrease in performance and a reduction in life of the pump depending on oil and gas reservoir characteristics and operating conditions in wells. As the result, the failure of ESP causes high well workover costs due to retrieval and installation, and additional costs due to shut down. In this study, a flow loop system was designed and established to predict the life of ESP in long­term operation of oil and gas wells, and the life cycle data of ESP from the time of installation to the time of failure was acquired and analyzed. Among the data acquired from the system, flow rate, inlet and outlet temperature and pressure, and the data of the vibrator installed on the outside of ESP were analyzed, and then the performance status according to long-term operation was classified into five stages: normal, advice I, advice II, maintenance, and failed. Through the experiments, it was found that there was a difference in the data trend by stage during the long­term operation of the ESP, and then the condition of the ESP was diagnosed and the failure of the pump was predicted according to the operating time. The results derived from this study can be used to develop a failure prediction program and data analysis algorithm for monitoring the condition of ESPs operated in oil and gas wells.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.749-755
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• 2021

The objective of this study was to investigate the physicochemical properties of rice starch extracted from stale rice using alkaline steeping (AKL) and improved enzymatic digestion (iENZ) methods. The crude protein content (0.5-0.7%) of stale rice starch (SRS) was less than 1% by iENZ, but not so when measured by the existing ENZ methods. SRS is an intermediate amylose rice starch. AKL-SRS and iENZ-SRS exhibited typical A-type crystal packing arrangements with similar relative crystallinities. iENZ-SRS showed higher gelatinization onset and peak temperatures with a narrower gelatinization temperature range, compared to those of AKL-SRS, indicating that iENZ annealed SRS. Thus, iENZ-SRS exhibited lower swelling power and solubility, and higher pasting viscosities with delayed viscosity development. Overall, the use of stale rice as a rice starch source could make economical production of rice starch possible, and iENZ may diversify rice starch characteristics, which expands the utilization of rice starch in food and non-food industries.

• Development and Reproduction
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• v.2 no.2
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• pp.213-221
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• 1998

Intracytoplasmic sperm injection (ICSI) has been widely used to treat couples with infertility due to severely impaired sperm charateristics and for whom conventional in-vitro fertilization (IVF) had failed. The extent to which the morphology of the oocyte at the light microscopy level is related to the results of ICSI vis controversial. In this study, oocytes from 44 patients were reviewed. The ICSI procedure was recorded through CCD camera. The oocytes were divided into five groups according to the presence of cytoplasmic inclusions, the width of perivitelline space (PVS), the presence of cell debris in PVS, the status of first polar body and the flexibility of oolemma. The results showed that the fertilization rate and embryonic development were not associated with the morphological criteria of oocyte. The degeneraton rate of oocytes after ICSI was significantly higher (P<0.001) in the oocytes whose membranes were broken at the moment of insertion (17.7%) than the oocytes whose membranes were broken by aspiration of cytoplasm (1.6%). More oocytes with cytoplasmic inclusions (48.4% vs. 25.1%, p<0.001), wide PVS (35.2% vs. 19.0%, p<0.001), or cell debris in PVS (53.3% vs. 38.4%, p<0.05) were observed in patients with female factor infertility compared to patients with male factor infertility. These results .suggest that the fertilization rate and embryonic development after ICSI are not correlated with oocyte morphology based on the presence of cytoplasmic inclusions, size of PVS, the presence of cell debris in PVS and the status of polar body. And the degeneration rate of oocytes after ICSI was associated with the flexibility of oolemma.