• 한국가스학회지
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• 제19권6호
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• pp.62-66
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• 2015

LNG선이나 해양플랜트 같은 설비나 구조물은 작동 조건을 고려할 때, 특히 부재마다 가지는 고유한 연성 취성천이온도(Ductile to Brittle Transition Temperature, DBTT)를 고려하여 설계되어야 한다. 본 연구에서는 해양플랜트 및 LNG선에 hull plate로 쓰이는 A-grade 연강(mild steel)에 대해 DBTT를 샤르피 V-노치(CVN) 실험을 통해 알아보았고 파괴형상을 통한 파괴거동을 살펴보았다. 그 결과 온도가 감소함에 따라 충격 흡수에너지는 감소함을 보였다. Upper shelf energy region과 lower shelf energy region이 나타나고 그 사이 구간의 천이점을 통해 DBTT가 결정되었다. 파괴형상에서는 upper shelf energy region에서 수많은 딤플이 연성파괴 형상으로 관찰되고 lower shelf energy region에서는 전형적인 취성파단형상이 관찰되었다. 이를 통해 BCC 구조를 가지는 A-grade 연강은 upper shelf energy 구역과 lower shelf energy구역을 보이고 그 사이 구간의 천이점에서 급격하게 온도가 떨어지는 DBTT구간을 뚜렷하게 보이는 특성을 알 수 있었다.

• Ocean and Polar Research
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• 제27권3호
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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.

• 대한기계학회논문집A
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• 제24권9호
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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.

• 한국식품저장유통학회지
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• 제4권2호
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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$0^{\circ}C$.

• 한국추진공학회지
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• 제5권3호
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• pp.1-9
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• 2001

잠수함용 재료로 개발된 고강도 구조용강의 충격 시험이 수행되었다. 특히 샤르피 충격시험기를 이용하여 저온에서 구조용 강의 충격특성을 평가하였다. 최소흡수에너지, 최대흡수에너지, 연성 취성 천이온도를 결정하기 위하여 hyperbolic tangent curve fitting법을 이용하였다. 시험결과로부터 샤르피 충격에너지와 횡팽창량 사이의 비례 관계식을 산출하였다. 시험온도 변화에 따른 파단면 특성을 평가하기 위하여 SEM을 이용하여 파단면을 관찰하였다.

• 생물환경조절학회지
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• 제16권3호
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• pp.247-251
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• 2007

신선 엽채류인 시금치의 수확 후 포장, 저장유통온도별 품질보존 및 상품성에 미치는 영향을 조사하였다. 저장 중 중량의 변화에서 포장 후 저장 시는 중량감소가 거의 없었으나, 무포장은 저장기간이 길어질수록 그리고 저장온도가 높을수록 감소율이 현저하였다. 비타민 C함량은 저장 초기에 감소가 컸으며, 저장온도가 낮을수록 감소가 적었고, 비닐포장 간에는 큰 차이가 없었다. 시금치에서 Hunter's value는 저장온도가 높을수록 b값이 높아지는 경향이었다. 시금치 저장 중 외관 신선도에서 polypropylene 비닐포장 후 저온$(1{\sim}3^{\circ}C)$ 저장은 최고 34일, 상온$(10{\sim}15^{\circ}C)$ 저장은 8일까지 상품성이 유지되었으나, 무포장 상온보관은 3일 밖에 유지되지 않았다.

• Food Science and Biotechnology
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• 제16권6호
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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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• 제3권1호
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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.

• 생물환경조절학회지
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• 제17권2호
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• pp.96-100
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• 2008

꼬투리째 먹는 채소인 풋꼬투리 강낭콩의 수확후 포장 및 저장 유통온도별 품질보존 및 상품성에 미치는 영향을 조사하였다. 저장중 중량의 변화에서 PP필름 포장시는 변화가 없었으나 골판지박스 포장시는 저장 온도가 높고, 저장기간이 길어질수록 중량 감소율이 현저하였다. 저장중 경도는 저온저장이 상온저장보다 높게 유지되었다. 비타민 C함량은 저장중 모든 처리에서 감소되었고, 그 감소의 폭은 상온저장보다는 저온저장 시 적었다. 엽록소함량은 비닐필름 포장시는 저장온도간에 차이가 없었으나, 박스포장시는 상온저장시 엽록소함량의 감소가 저온저장보다 컸다. 외관 상품성을 표시하는 신선도는 비닐포장이나 골판지박스에 속비닐 넣은 후 산물을 포장하여 $8{\sim}10^{\circ}C$정도에서 저장 유통시는 상품유지기간이 8일 정도로 상온보관대비 4일정도 연장되었다.

• 원예과학기술지
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• 제28권3호
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• pp.434-441
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• 2010

본 실험은 만개후 120일, 130일에 수확 후 과실의 숙도별 적정수송온도 및 유통온도의 설정을 위하여 유통기간 중 과실의 품질과 생리장해 발생을 조사하여 상온보구력을 측정하였다. 미숙과는 유통 21일까지 처리구에서 경도를 유지하였으나 적숙과는 $25^{\circ}C$ 유통온도에서 과육이 분질되어 상품성을 상실하였다. 생리장해 발생은 적기수확과가 조기수확과에 비해 장해발생이 심하였고 이는 호흡과 밀접한 관계가 있었다. 유통기간 중 수송온도 보다 유통온도가 상온보구력에 큰 영향을 주었고 수송온도 또한 낮은 온도가 유리하였다. 과실의 품질과 생리장해 발생을 고려한 결과 조기수확과는 유통 21일까지 상품성을 유지하였으나 적기수확과는 7일 이내로 판단되었다.