• 한국농공학회논문집
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• 제52권3호
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• pp.89-95
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• 2010

There is the freezing method as one of the ground improvement methods for excavating an underground tunnel, and due to its improved reliability, recently construction cases of applying this method into sandy soil grounds as well as cohesive soil grounds of cities have been reported. But, applying the freezing method into cohesive soil grounds could bring concerns of the expansion of the whole ground and the settlements from thawing of ground. In this study, the deformation strength characteristics of cohesive soil which received freezing and thawing hysteresis were examined using the sample collected from the site of cohesive soil ground applied with the freezing method and its structural characteristics were analyzed using an electronic microscope. And, the test with cohesive soil reconstituted from cohesive soil which received freezing and thawing hysteresis was carried out and its result was analyzed comparatively. The result of this test showed that the structure of natural clay was significantly changed due to freezing and thawing hysteresis.

• 한국식품과학회지
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• 제31권1호
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• pp.54-61
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• 1999

본 연구는 해동 중 발생하는 drip 손실, 미생물의 오염, 표면의 과열 등을 방지하면서 급속 해동 방법을 찾기 위해 동결 돈육에 여러 가지 해동 방법을 적용하였다. 4, 28, $50^{\circ}C$에서의 해동과 2,450, 915 MHz의 microwave를 이용하여 해동을 실시하였고, 915 MHz microwave 해동은 출력을 5, 10, 15 kW로 변화시키면서 단일 조사와 $120^{\circ}C$의 열풍을 함께 조사한 경우를 해동시간, 온도분포, drip 손실, 보수력, 표면색도, 총세균수를 측정하였다. 915 MHz microwave를 이용한 해동은 열전도에 의한 해동보다 2백배 이상 시간이 단축되었고, 2,450 MHz microwave를 이용한 해동 방법의 침투깊이의 제한에서 발생되는 문제를 개선시킬 수 있었으며 drip 손실, 보수력, 총세균수에 있어서 효과가 컸다. 저주파수(915 MHz), 저출력(5 kW)의 microwave와 대류 가열을 병용하여 품질 저하를 최소한으로 방지하면서 급속해동을 위한 산업적 이용이 가능한 것으로 기대할 수 있었다.

• 한국식품과학회지
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• 제22권2호
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• pp.123-128
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• 1990

여러 가지 해동방법 중에서 비교적 급속해동을 할 수 있는 열풍해동방법과 microwave 해동방법으로 냉동 돈육을 해동하여 해동육의 이화학적 성질을 조사하였으며, $4^{\circ}C$ 냉장해동육의 이화학적 성질을 비교하여 최적 해동방법을 모색하고자 하였다. 열풍온도를 높이고 해동육 표면온도를 낮출수록 열풍해동속도는 빨랐으며, microwave 해동시에는 출력이 크고 해동육심부온도가 낮을수록 해동속도가 빨랐다. 이 때 microwave 해동방법은 열풍해동방법보다 유의적으로 빠른 해동속도를 보였다. $4^{\circ}C$ 냉장해동육의 TBA가와 microwave 해동육의 TBA가는 유사하였으나 열풍해동육인 경우에는 열풍온도가 높아질수록 TBA가는 유의적으로 높았다. Microwave해동육의 가용성단백질추출성은 $4^{\circ}C$ 냉장해동육과 유사하였지만 열풍해동육보다는 높았다. 해동육의 보수성과 조리손실과의 관계는 고도의 상관성을 나타냈으며, microwave 해동육이 열풍 해동육보다 보수성이 좋았고 조리손실은 줄었다. 육표면에 존재하는 세균수는 $4^{\circ}C$ 냉장해동육에서보다 열풍 해동육과 microwave 해동육에서 적었다. 이상의 결과에서, 냉동육을 해동할 때, 육량감소를 줄이고 해동육의 기능성을 좋게 유지할 수 있는 해동조건으로서는 열풍해동에서는 $50^{\circ}C$ 열풍으로 육표면온도를 $25^{\circ}C$까지 해동시킬 때가, microwave로 해동하면 195W의 출력으로 육심부온도를 $-2^{\circ}C$까지 해동시키는 것이 가장 좋은 것으로 나타났다.

• 대한가정학회지
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• 제35권2호
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• pp.147-157
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• 1997

It attempted to determine the effect of various thawing methods, such as pressure cooking, conventional cooking, microwave heating and thawing at room temperature, on the quality of frozen cooked rice using Nongan variety of rice. These effects were analysed at three different periods-after 10 days, 30 days and 90 days. It conducted a physico-chemical analysis(moisture content, dehydration rates, color value and texture) and sensory evaluation o the frozen-thawed cooked rice. The study showed that there were no significant differences on the frozen-thawed cooked rice. The study showed that there were no significant differences on the quality characteristics of frozen-thawed cooked rice during the storage of 90 days. However, the thawing method of pressure cooking caused high moisture content and decrease in hardness on the cooked rice, the desirability for the rice didn't diminish compared with the cooked rice just after cooking. the quality characteristics of the cooked rice after frozen-thawing by conventional cooking and microwave heating were similar with that of the cooked rice just after cooking. thawing at room temperature caused a significant decrease in quality characteristics.

• 지질공학
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• 제11권1호
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• pp.13-23
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• 2001

도로나 철도 변에 나타나는 암반사면은 외부 기온에 영향을 받아 동절기부터 이른봄에 걸쳐 동결융해작용을 반복해서 받는다. 본 연구의 목적은 불연속성 암반이 동결융해작용을 반복하여 받을 경우 열화현상을 겪게 되고 이에 따른 암반의 안정성이 어떻게 변화되는가를 해석한다. 해석방법으로는 균질화법을 이용하여 불연속성 암반의 강도특성을 밝히고 파괴기준으로는 드러커-플래커 기준을 이용한다. 또한 실제 암석의 열화특성은 응회암을 채취하여 실내 동결융해실험에 의하여 열화특성을 정량화 하여 암반의 안정성 해석의 기초 자료로 이용한다. 현장사면에서 동결융해에 의한 열화의 깊이를 추정하기 위하여 일차원 열전도 방정식을 이용하여 온도에 영향을 받는 깊이를 구한다. 모델 사면의 동결융해 깊이를 결정한 후 모델 암반사면에서 암반의 강도 값의 변화양상을 해석한다. 암반의 작용하는 외력은 자중에 의한 중력만이 작용한다고 가정하고 안전율 해석을 실시한다. 그 결과 암반의 안정성 변화양상을 정량적으로 분석한다. 대상으로 하는 두 도시의 경우 동결융해 영향을 받는 깊이는 1.0m 내외 였으며 10년 경과 후에는 암반의 붕괴 조짐을 나타나는 것을 추측할 수 있다.

• 한국가축번식학회지
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• 제8권2호
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• pp.79-86
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• 1984

This cepseiment was carried out to cerify the effect of thawing methods and preservative temperature on the sperm motility and fertility after thawing semen with plastic straws in fresh and warm water. Sperm motility in vitro stored at room temperature after thawing were conducted by the various storage hours. A field trial after thawing semen with warmed water in straws from Cheju native cows involving 4 technicians and 800 cows first (or second) services gave the following results. The thawing methods of warmed water for one minute in semen motility were considerably higher than that in iced water during 12 hours after thawing semen, however, the sperm survival index of ice-water shwed a better results according as the time passed away, but not significant differences. Preservative temperaure at 5$^{\circ}C$ (iced water) after thawing gave significantly better results than that of thawed at 3$0^{\circ}C$ (warmed water). The N R rate to 175 inseminations with semen thawed at 15-2$0^{\circ}C$ (fresh water) was 82.8%, 80.9% for 610 inseminations thawed in warm water. Conception rate ofthe semen thawed in warm water for 10-60 secs gave no significant difference among storage hours, because the semen used to be inseminated within one hour almost, but in decreased when semen thawed at the period of one minute over.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.48-53
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• 2003

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.

• Preventive Nutrition and Food Science
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• 제3권3호
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• pp.234-240
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• 1998

This study attempted to determine the effect of various thawing methods and storage periods on the quality of froen cooked rice. Frozen cooked rice was thawed at four different methods, such as pressure cooking, conventional cooking, microwave heating and thawing at room temperature after 10 days, 30days and 90 days frozen storage. We conducted a physico-chemical analysis (moisture content, dehydration rates, degree of gelatinization, color value and texture) and sensory evalution on the frozen-thawed cooked rice. The study showed that there were no significant differences on the quality characteristics of frozen-thawed cooked rice during the storage period of 90 days. However, the thawing method of pressure cooking caused high moisture content, rapid dehydration rates, and a high degree of gelatinization on the cooked rice. Thus, the desirabililty for the rice diminished becaused of the excess moisture content and the change of appearance and testure in the rice due to the high temperature. There were similiar quality characteristics to the cooked rice after forzen-thawing whether by conventional cooking or by microwave heating and just after cooking. Thawing at room temperature also caused a significant decrease in quality characteristics.

• 유기물자원화
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• 제18권2호
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• pp.93-100
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• 2010

본 연구는 하수슬러지 전처리 방법으로 분쇄, 동결 해동, 동결 분쇄 조작을 한 후, 각각의 슬러지 특성의 변화를 고찰하였다. 분쇄 슬러지, 동결 해동 슬러지, 동결 분쇄 슬러지는 하수슬러지 부피에 비해 각각 2.08배, 3.37배, 3.54배 감소하여 동결 분쇄한 경우가 가장 슬러지 감소량이 컸으며 그 다음으로 동결 후 해동한 경우, 분쇄만 한 경우 순이었다. 또한 하수슬러지의 SCOD 농도, SBOD 농도, protein 농도는 동결하지 않은 것보다 동결 하는 것이 높았고, 그 중에서도 동결 후 분쇄하는 것이 가장 높은 경향을 보였다. TS, VS의 제거율은 동결한 것이 높았지만, 동결 분쇄보다 동결 해동이 높은 경향을 보였다. 이상의 결과로부터 동결 분쇄 방법이 슬러지 전처리 방법으로 매우 효과적이며 2012년부터 발효되는 슬러지 해양 투기 전면 금지에 대한 대안이 될 수 있을 것으로 기대된다.

• 한국동물생명공학회지
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• 제36권2호
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• pp.82-90
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• 2021

In the present study, we examined if deep uterine artificial insemination (DUAI) can improve the pregnancy rate of artificial insemination (AI) using epididymal spermatozoa (ES) in Hanwoo cattle. The estrus cycles of 88 Hanwoo cows were synchronized, and 17 cows were artificially inseminated using the DUAI method with ES, 20 cows were artificially inseminated via the uterine body (BUAI) method with ES, and as a control, 51 cows were inseminated by using the BUAI method with ejaculated spermatozoa from 1 proven bull after frozen thawing. The pregnancy rate of the DUAI method (58.8%) was higher than that of the BUAI method (25.0%, p = 0.0498). The motility of ES was examined immediately after thawing and after 3 and 6 h of incubation. The rapid progressive sperm motility of the control group was significantly higher than that of the ES group immediately after thawing and after 3 and 6 h of incubation (p < 0.05). The straight line velocity and average path velocity of the ES group after 6 h of incubation were significantly lower than those in the control group (p < 0.05). The linearity and amplitude of lateral head of ES were lower than those at 6 h (p < 0.05). The flagellar beat cross frequency and hyperactivation of ES were lower than the control spermatozoa immediately after thawing and at 3 h (p < 0.05). These motility parameters suggested that ES had a low motility and fertilization ability compared to the control spermatozoa. After frozen-thawing and 3 h of incubation, the percentage of live spermatozoa with intact acrosomes in the ES was significantly lower than that in ejaculated spermatozoa (p < 0.05). Our findings suggested that the DUAI method can overcome the low pregnancy rate of ES, despite the low motility, viability, and fertilization ability of ES.