• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.62-66
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• 2015

Considering for plants and structure under extreme conditions is required for the successful design, especially temperature and pressure. The ductile-brittle transition temperature (DBTT) for the materials under extreme condition needs to be considered. In this study, A-grade mild steel for the LNG carrier and offshore plant was examined by performing low-temperature Charpy V-notch (CVN) impact tests to investigate DBTT and the fracture toughness. The absorbed energy decreased gradually with the experimental temperature, which showed an upper-shelf energy region, lower shelf energy region, and transition temperature indicating DBTT. In addition, the fracture surface morphologies of the mild steels indicated ductile fractures at the upper-shelf energy level, with wide and large-sized dimples, whereas a brittle fracture surface, where was observed at the lower-shelf energy level, with both large and small cleavage facets. Based on the experimental results, ductile brittle transition temperature was estimated in about $-60^{\circ}C$.

• Ocean and Polar Research
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• v.27 no.3
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• pp.277-288
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• 2005

Spatial distribution and vertical structures of water masses around the Antarctic continental margin are described using synthesized hydrographic data. Antarctic Surface Water (AASW) over the shelf regime is distinguished from underlying other water masses by the cut-off salinity, varying from approximately 34.35 to 34.45 around Antarctica. Shelf water, characterized by salinity greater than the cut-off salinity and potential temperature less than $-17^{\circ}C$, is observed on the Ross Sea, off George V Land, off Wilkes Land, the Amery Basin, and the Weddell Sea, but in some shelves AASW occupies the entire shelf. Lower Circumpolar Deep Water is present everywhere around the Antarctic oceanic regime and in some places it mixes with Shelf Water, producing Antarctic Slope Front Water (ASFW). ASFW, characterized by potential temperature less than about $0^{\circ}C$ and greater than $-17^{\circ}C$, and salinity greater than the cut-off salinity, is found everywhere around Antarctica except in the Bellingshausen-Amundsen sector. The presence of different water masses over the Antarctic shelves and shelf edges produces mainly three types of water mass stratifications: no significant meridional property gradient in the Bellingshausen and Amundsen Seas, single property gradient where ASFW presents, and a V-shaped front where Shelf Water exists.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2319-2325
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• 2000

This thesis studied that seven kinds of residual elements(inclusions) had influenced on fracture toughness($K_{IC}$) obtained by Begley-Logsdon and Rolfe-Novak model equation using tensile an d impact test data of I%CrMoV HP(high pressure) rotor steel. $K_{IC}$ design curve of ASME and fracture surface by SEM were also considered, obtained results are summarized as follows $K_{IC}$ was linearly increased with increase of temperature, effect of the inclusions was significantly over FATT. $K_{IC}$ at lower shelf temperature was quantitatively related to yield strength and was agreed well with Begley's equation. It was difficult to determine $K_{IC}$ because of specimen size and tester capacity at upper shelf temperature, but for this view point Rolfe-Novak's equation was useful. The degree of brittle fracture was dependent on FATT fundamentally, adding S, Sb to matrix decreased impact energy and adding Cu, As increased yield(tensile) strength, and the influence of the others minority inclusion was comparatively insignificant.

• Food Science and Preservation
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• v.4 no.2
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• pp.139-146
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• 1997

The influence of packaging methods(0.03mmPE, 0.05mmPE, 0.1mmPVC, VACUUM) and marketing temperatures(2$0^{\circ}C$, 1$0^{\circ}C$) on the shelf-life and quality were investigated in yam(Dioscorea). Respiration, weight-loss and rotting-rate was reduced in polyethylene film packaging in the order of VACUUM, 0.1mmPVC, 0.05mmPE, 0.03mmPE and the effect was more outstanding at 1$0^{\circ}C$ than 2$0^{\circ}C$. The ethylene concentration of PVC packaging group was higher than that of other packaging methods, which was related with sprouting. firmness was higher in low-temperature than in room-temperature. PPO activity was lower in vacuum than in other packaging methods, which was associated with browning. The shelf-life of yam was the longest in vacuum Packaging, 3 weeks at 2$0^{\circ}C$ and more than 4 weeks at 1$0^{\circ}C$.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.1-9
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• 2001

Impact tests are performed on the high strength structural steel that is being developed for the submarine material. Especially, the impact characteristics of this structural steels at low temperatures are investigated by charpy impact testing. Hyperbolic tangent curve fitting method is used to evaluate the LSE(lower shelf energy), USE(upper shelf energy) and DBTT(ductile-brittle transition temperature). Proportional equations between charpy impact energy and lateral expansion are obtained using the test results. Effect of temperature on the fracture appearance is investigated by using SEM.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.247-251
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• 2007

To extend the shelf-life of spinach after harvest, we investigated the effect of various packaging methods and storage temperature. In case of polypropylene film package, there was no weight loss, but in non-package, remarkably weight loss occurred as storage period extended and storage temperature risen. Content of vitamin C was decreased rapidly at early stage of storage, and decrease of vitamin C in low temperature storage was lower than that of room temperature storage, but its large difference according to packaging method was not observed. In hunter's value on spinach, b value in room temperature storage was higher than that of low temperature storage. In terms of freshness, shelf-life of spinach by low temperature storage $(1{\sim}3^{\circ}C)$ after PP film packaging lasted 34 days, and that by room temperature storage $(10{\sim}15^{\circ}C)$ after PP film packaging lasted 8 days, but that by room temperature storage after non-packaging lasted 3 days.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.889-893
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• 2007

The demand of quality green banana chips is increasing in the world snacks market, therefore, the preparation of quality chips and their subsequent shelf life in packaging were evaluated in this study. Banana slices were fried in hot oil to the desired moisture content (2-3%) and oil content (40%) in chips at 3 different temperatures, and the impact of different pretreatments were compared by sensory assessment. A linear relationship between time and temperature was used to achieve the optimal processing conditions. Banana slices fried at the lower temperature of $145^{\circ}C$ took longer to reach the desired chip qualities, but gave the best results in terms of color and texture. Blanching was the most effective pre-treatment for retaining the light yellow color in finished chips. For extending the shelf life of chips, moisture proof packaging in double layer high density polyethylene was more effective than single layer low density polyethylene.

• Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.14-22
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• 2000

The relationship between the distribution of demersal fishes and that of the water masses was examined by using the catches data and hydrographic data in the Yellow Sea and the East China Sea on May 13-19, 1996 and May 10-17, 1997. During the study period, the dominant fish species were Cleisthenes pinetorum herzinsteini, Lophiomus setigerus and Pseudosciaena polyactis. These three low temperature water species accounted for $21-24\%$ of the total catches. The percentage of the low temperature water species was high in the Yellow Sea and the coastal area on the continental shelf of the East China Sea but was low in the vincinity of Kyushu during the study period. In the East China Sea, the isotherm of $15^{\circ}C$ at 50m, mid layer depth, was located more southeast in 1996 than in 1997. The bottom water temperature was about it lower in 1996 than in 1997. The direction of the detided current on the continental shelf of the East China Sea was southward in 1996 and northward in 1997. Yellow Sea Bottom Cold Water (YSBCW) strongly expanded to south in 1996 when the northward current was weak. But, Tsushima Warm Current (TSWC) strongly intruded into the continental shelf of the East China Sea in 1997. As YSBCW expanded strongly to south in 1996, the percentage of the low temperature water species relative to the total catches was high. But, TSWC strongly intruded and the percentage of low temperature water fishes was low in 1997.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.96-100
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• 2008

To extend the shelf-life of kidney bean (Phaseolus vulgaris L.) after harvest, we investigated the effect of packaging material and storage temperature. In case of film package, there was no weight loss during storage, but in paper-box package, remarkable weight loss occurred as storage period extended and storage temperature risen. Firmness of kidney bean was greater in low temperature than ambient temperature storage. Content of vitamin C was decreased rapidly during storage, and in paper package, low temperature storage group had lower decrease of vitamin C than that of room temperature. Total chlorophyll content was not difference among storage temperatures in film package treatments. However, in paper-box package, decrease of chlorophyll in room temperature storage was greater than that of low temperature ($8{\sim}10^{\circ}C$). In terms of freshness of kidney bean, we suggest that shelf-life by low temperature storage ($8{\sim}10^{\circ}C$) after PP film or paper package was 8 days, but that by room temperature storage after paper package was 4 days.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.434-441
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• 2010

'Wonhwang' pear ($Pyrus$ $pyrifolia$ Nakai) often showed physiological disorder and quality deterioration during long-term storage and shelf life although this cultivar has the advantage of a good appearance and better taste for overseas exportation. This study was conducted to investigate the effect of temperature during transportation and continuing market temperature on fruit quality, and the occurrence of physiological disorder to set up the appropriate transportation and distribution temperatures in the fruits harvested at different times. Unripe fruits harvested 120 days after full bloom maintained higher firmness until 21days of shelf life at both 18 and $25^{\circ}C$ than late harvested ones. Otherwise, ripe fruits harvested 130 days after full bloom showed high incidence of mealiness breakdown of flesh tissues in 21 days of shelf-life at $25^{\circ}C$ of market temperature, but not in the fruits stored at $18^{\circ}C$. Late harvested fruits showed much severe physiological disorders when compared with early harvested ones that showed relatively lower respiration rates. Fruit quality parameters were more highly affected by market temperature than transportation temperature. Results showed that unripe fruits harvested at 120 days after full bloom maintains high marketability until 21 days of shelf-life, while the maximum shelf-life of ripe fruits harvested 130 days after full bloom will be considered at within 7 days.