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Evaluating the Mechanical Properties of Fiber Yarns for Developing Synthetic Fiber Chains
Kyeongsoo Kim,Taewan Kim,Namhun Kim,Dokyoun Kim,Yongjun Kang,Seonjin Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.6
In this study, three types of synthetic fiber materials were evaluated, namely, DM20, SK78, and T147, to replace steel chains in shipbuilding and offshore fields with fiber chains as there is increasing demand for chains with lighter weights and improved usabilities. The strength and quasi-static stiffness were analyzed to select suitable yarns for the fiber chains. The durability of the yarn was evaluated by performing a 3-T (time to rupture) test as a specific tension level. The results of the experiment revealed excellent dynamic stiffness in DM20 and highest values of the windward and leeward stiffness in T147. 3-T linear design characteristic curves for a specific tension level were derived for the three types of fiber materials. The findings of this study can provide insights for improving strength and durability in fiber chain design.
Phase Analysis of Uranium Oxides by XRD After Heat Treatment
Seonjin Kim,Joohyung Kim,Hyejin Son,Wonpyo Jeong,Seungyeon Choi,Sangjoon Ahn,Jaehak Cheong,Kwangheon Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Once discharged, spent nuclear fuel undergoes an initial cooling process within deactivation pools situated at the reactor site. This cooling step is crucial for reducing the fuel’s temperature. Once the heat has sufficiently diminished, two viable options emerge: reprocessing or interim storage. A method known as PUREX, for aqueous nuclear reprocessing, involves a chemical procedure aimed at separating uranium and plutonium from the spent nuclear fuel. This separation not only minimizes waste volume but also facilitates the reuse of the extracted materials as fuel for nuclear reactors. The transformation of uranium oxides through dissolution in nitric acid followed by drying results in uranium taking the form of UO2(NO3)2 + 6H2O, which can then be converted into various solid-state configurations through different heat treatments. This study specifically focuses on investigating the phase transitions of artificially synthesized UO2(NO3)2 + 6H2O subjected to heat treatment at various temperatures (450, 500, 550, 600°C) using X-ray Diffraction (XRD) analysis. Heat treatments were also conducted on UO2 to analyze its phase transformations. Additionally, the study utilized XRD analysis on an unidentified oxidized uranium oxide, UO2+X, and employed lattice parameters and Bragg’s law to ascertain the oxidation state of the unknown sample. To synthesize UO2(NO3)2 + 6H2O, U3O8 powder is first dissolved in a 20% HNO3 solution. The solid UO2(NO3)2 + 6H2O is obtained after drying on a hotplate and is subsequently subjected to heat treatment at temperatures of 450, 500, 550, and 600°C. As the heat treatment temperature increases, the color of the samples transitions from orange to dark green, indicating the formation of different phases at different temperatures. XRD analysis confirms that uranyl nitrate, when heattreated at 500 and 550°C, oxidizes to UO3, while the sample subjected to 600°C heat treatment transforms into U3O8 due to the higher temperature. All samples exhibit sharp crystal peaks in their XRD spectra, except for the one heat-treated at 450°C. In the second experiment, the XRD spectra of the heat-treated UO2 consistently indicate the presence of U3O8 rather than UO3, regardless of the temperature. Under an oxidizing atmosphere within a temperature range of 300 to 700°C, UO2 can be oxidized to form U3O8. In the final experiment, the oxidation state of the unknown UO2+X was determined using Bragg’s law and lattice parameters, revealing that it was a material in which UO2 had been oxidized, resulting in an oxidation state of UO2.24.
Storage Stability of Vacuum-packaged Dry-aged Beef during Refrigeration at 4℃
Seonjin Kim,Hyun Jung Lee,Minsu Kim,Ji Won Yoon,Dong Jin Shin,Cheorun Jo 한국축산식품학회 2019 한국축산식품학회지 Vol.39 No.2
Although the production of dry-aged beef has been increasing, most purveyors are unaware of the changes in quality that ensue after completion of the aging period and do not adhere to specific guidelines for its packaging and storage. The objective of this study was to investigate the storage stability of vacuum-packaged dry-aged beef based on changes in microbial, physicochemical, and sensory properties during refrigeration at 4°C for 21 d. The total aerobic bacterial count exceeded 6 Log CFU/g at approximately day 11 and significantly increased after day 14. Freshness indicators such as pH and volatile basic nitrogen content were acceptable until day 14 and 21, respectively. Based on the evaluation of overall sensory acceptability, the dry-aged beef was acceptable until 14 d without any sensory deterioration. Therefore, vacuum-packaged dry-aged beef could be stored for 11 d at 4°C without any adverse effect on its microbial and sensory quality.
윤선진 ( Seonjin Yoon ),정명상 ( Myeongsang Jeong ),송해종 ( Haejong Song ),나은경 ( Eunkyung Na ),김나영 ( Nayoung Kim ),김경아 ( Kyongah Kim ),권순복 ( Soonbok Kwon ),이인숙 ( Insook Lee ),김재식 ( Jaesik Kim ) 한국환경분석학회 2020 환경분석과 독성보건 Vol.23 No.4
ThepurposeofthisstudywastodocumentgroundwaterqualityinChungcheongnam-do.SamplesweretakenfromTaean,Dangjin,Seocheon,Boryeong,Seosan,andNonsanareas,and48waterqualityvariableswereanalyzedinrelationtoapplicablestandards,includingtheamountsofnaturallyoccurringradioactivematerials(UandRn).Theresultsfromtesting179locationsindicatedthat128weresuitableand51wereofunacceptablequality,intermsofdrinkingwaterqualitystandards.Thenonconformityratefornitratenitrogenwas47.0%,whilethatfortotalcoliformswas24.2%.Heavymetals-suchasPb,Hg,Cd,andCr-weredetectedinlowconcentrationsatallpoints.AnalysisofnaturallyoccurringradioactivematerialsshowedthatUconcentrationswerewithinthewaterqualitystandard(0.03mg/L)atallpoints.RnconcentrationswerelowinNW?ㅤregionssuchasTaean,Dangjin,Seocheon,andBoryeong,whereProterozoicsedimentaryrocksweredistributed,butitsconcentrationsintheSeosanandNonsanareas,wheregraniterockswerewidelydistributed,requiredcloserinvestigation,anditwasfoundthatthealternativemaximumcontaminantlevel(148Bq/L)wasexceededingranitesoilswhichoriginatedfromtheMesozoicEra.