• Asian-Australasian Journal of Animal Sciences
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• 제20권2호
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• pp.257-262
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• 2007

The current study was conducted to investigate the optimum stunning voltage and chilling regime with emphasis on reduction in pale, soft and exudative (PSE) pork. The experiments were conducted at seven Korean major pig abattoirs using a total of 91,082 industrial population. Frequencies of PSE meat was found to be significantly (p<0.05) increased as stunning voltage was elevated from 220-240 (13.14%), 250-280 (29.32%) to 430 volts (36.74%). Chilling methods after slaughter, either with cold water showing or rapid chilling reduced PSE meat by 22% compared to a classic chiller-based slow chilling regime. The current study also revealed that chiller temperature during the first 90 minutes had a significant (p<0.001) effect on PSE incidences. Pigs chilled between -5 to $7^{\circ}C$ resulted in the lowest PSE meat (17.8%), followed by higher than $7^{\circ}C$ (21.3%) and lower than $-5^{\circ}C$ (37.5%). The current data implies that low voltage stunning method (eg., 220-240 volts), followed by rapid chilling regime, maintaining chiller temperature between approximately -5 to $7^{\circ}C$ could reduce PSE incidences.

• 대한기계학회논문집
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• 제9권6호
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• pp.750-756
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• 1985

본 연구에서는 종횡비 0.1이고 상.하 수평경계면이 단열된 직각밀폐용기내에 서 Pr수가 1보다 큰 물(Pr=6.97, 20.deg. C) 및 실리콘 오일(Pr=1086.42, 20.deg. C)의 양단의 온도차에 의한 자연대류에서 아직 충분히 연구되지 않은 코어형상에 주안점을 두고 실 험적으로 관찰, 조사하였으며 그 결과를 Lee의 이론적인 예측과도 비교, 검토해 보았 다.

• The Korean Journal of Ecology
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• 제25권2호
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• pp.93-100
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• 2002

돼지풀(Ambrosia artemisiifolia var. elatior D/sub ESCOURTILS/)종자의 발아를 유발시키는 몇가지 환경요인의 영향을 조사한 결과는 다음과 같다. 종자의 휴면은 온도와 토양함수량이 적절하면 채종직후에도 일부분 타파되었고, 주야의 변온(30/20℃)이 휴면타파에 효과적이었다. 온도에 따른 발아율은 12℃∼32℃의 온도처리구에서 모두 발아가 이루어졌고, 발아에 필요한 최적온도는 24℃였다. (P<0.01). 토양함수량의 영향은 30% 처리구에서 증가하기 시작하여 60% 처리구에서 최대치를 나타내고 (P<0.05) 80% 처리구에서 다시 감소하는 경향을 나타내었으며, 토양함수량 7% 처리구에서는 전혀 발아가 이루어지지 않았다. 온도에 대한 광의 영향은 24℃의 온도 처리구에서 광처리시와 암처리시 가장 높은 발아율을 나타내었고, 광의 존재유무에 따른 발아율의 차이는 뚜렷하지 않았다. (P>0.05). 채종시기간에는 9개월 저장기간의 어떤 시기에도 종자의 발아에 특별한 영향을 나타내지 않았다. (P>0.05). 온도상승구(IT)에서 돼지풀종자는 16℃에서 발아하기 시작하였고 온도가 상승함에 따라 발아율이 점차 증가하여 최종발아율은 99.34%에 이르렀다. 반면에 온도하강구(DT)에서는 20℃에서 처음발아가 시작되었으며(1.34℃)에서 5.34%의 최종발아율을 나타내었고, 온도가 하강함에 따라 2차 휴면이 유도되었다. 저온에 의한 종자의 휴면타파가 고온에 의한 휴면타파보다 더 많이 유도되어, 돼지풀 종자는 늦가을에도 발아가 이루어지나 그 다음해 봄에 대부분의 종자발아가 이루어질 것으로 생각되어진다. 이와 같은 돼지풀종자들 내의 발아습성의 변이가 다양한 환경변화에 대해 자신의 생존과 자손의 번식을 위한 생리적·생태적 전략임을 알 수 있었다.

• 대한기계학회논문집B
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• 제27권5호
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• pp.612-619
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• 2003

This work experimentally studies the fundamental mechanisms by which the ultrasonic vibration enhances convection and pool boiling heat transfer. A thin platinum wire is used as both a heat source and a temperature sensor. A high speed video imaging system is employed to observe the behavior of cavitation and thermal bubbles. It is found that when the liquid temperature is below its boiling point, cavitation takes place due to ultrasonic vibration while cavitation disappears when the liquid reaches the boiling point. Moreover, when the gas dissolved in liquid is removed by pre-degassing, the cavitation arises only locally. Depending on the liquid temperature, heat transfer rates in convection, subcooled boiling and saturated boiling regimes are examined. In convection heat transfer regime, fully agitated cavitation is the most efficient heat transfer enhancement mechanism. Subcooled boiling is most enhanced when tile local cavitation is induced after degassing. In saturated boiling regime, acoustic pressure is shown to be a dominant heat transfer enhancement mechanism.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.147-149
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• 2003

The wetness, a function of precipitation and temperature etc, and the warmth, a function of temperature, are the dominant factor for global vegetation distribution. This paper employs the normalized difference vegetation index (NDVI), warmth index (WAI), and wetness index (WEI), and focuses on an essential climate-vegetation relationship at global scale. The NDVI was acquired from ‘Twenty-year global 4-minute AVHRR NDVI dataset.’ The WEI is defined as the fraction of the precipitation to the potential evaporation. The WAI was calculated by accumulating the monthly mean temperature of the portion exceeded 5$^{\circ}C$ throughout the year. Meteorological data for the WEI and WAI calculation were obtained from the ISLSCP CD-ROM. All analyses were conducted for 1 ${\times}$ 1 degree grid box on the terrestrial area of the Earth, and on annual value basis averaged in 1987 and 1988. The result of analyses demonstrated that there are two regimes in their relations, that is, a regime in which NDVIs vary depending on the WEI, and a regime in which NDVIs vary depending on the WAI. These two regimes appeared to correspond to the wetness dominant and warmth dominant vegetation, respectively. The geographical distributions of two regimes were mapped. Most of the world vegetation is categorized into wetness dominant, while warmth dominant vegetation is seen in the high-latitude area mainly to the north of 60$^{\circ}$N in the Northern Hemisphere and high-altitude areas.

• 소성∙가공
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• 제13권5호
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• pp.435-440
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• 2004

The temperature in hot forming of metallic materials, such as hot extrusion and hot forging, ranges from $300^{\circ}C$ to $900^{\circ}C$. Correspondingly, the die also exhibits high temperatures close to that of a work piece and its life is limited generally by high temperature fatigue. Thus, the analysis of high temperature fatigue would need the mechanical properties over the wide ranges of temperature. However, very few studies on the high temperature fatigue of brittle materials have been reported. Especially, the study on the fatigue behavior over such transition temperature regime is very rare. In this paper, the stress-strain curves and stress-life curves of a die steel such as STD61 are experimentally obtained. The wide ranges of temperature from $300^{\circ}C$ to $900^{\circ}C$ are considered in experiments and the transition temperature zone is carefully examined.

• 한국응용곤충학회지
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• 제26권1호
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• pp.43-47
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• 1987

도열병병반형성(稻熱病病斑形成)에 미치는 침입률(侵入率)과 균사신전도(菌絲伸展度)의 효과(效果)를 알기 위(爲)하여 23/15C(주/야(晝/夜)), 29/21C 및 온실조건(溫室條件)($33{\sim}23C$)에서 처리(處理)한 Aichi-asahi, Toyotama, Yamabiko에 6개의 도열병균(稻熱病菌) 균주(菌株)를 접종(接種)한 결과(結果), 접종후(接種後) 72,96시간(時間)째의 침입률(侵入率)은 어느 온도조건(溫度條件)에서도 병반형성(病斑形成)과 고도(高度)의 유의성(有意性)이 있었다. 또한 균사신전도(菌絲伸展度) 11이상(以上)을 나타내는 부착기수(付着器數)도 병반수(病斑數)와 고도(高度)의 유의성(有意性)이 인정(認定)되었다. 그러나 균사신전도(菌絲伸展度) 30이상(以上)을 나타내는 부착기수(付着器數)는 29/21C조건(條件)의 접종후(接種後) 72시간(時間)째에만 유의성(有意性)이 인정(認定)되었다. 이들 상관관계(相關關係)의 통계적(統計的)인 적중도(的中度)는 29/21C나 온실(溫室)보다는 23/15C에서 더 높았으며 이런 현상(現象)은 이병성품종(罹病性品種)인 Aichi-asahi에서 더욱 뚜렷하였다.

• 한국추진공학회지
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• 제1권2호
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• pp.22-31
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• 1997

비직교 일반좌표계를 사용하는 범용 연소유동해석 프로그램을 개발하여 재순환영역을 가지는 연소유동 등을 해석하였다. 본 프로그램은 유한체적법에 근간을 둔 비엇갈림격자계를 사용하며 직교좌표 속도성분을 종속변수로 하였다. 연소모델은 무한반응속도의 1단계 비가역 반응을 고려하였으며, 밀도가중평균된 지배방정식을 고려하였다. Conserved Scalar의 확률밀도함수를 clipped gauss 분포로 가정하였다 본 프로그램을 사용하여 재순환영역을 가지는 난류확산화염을 계산하였다. 계산결과는 실험결과와 마찬가지로 두개의 재순환영역을 보였으며, 속도, 난류운동에너지, 온도 및 농도 등이 실험결과와 양호하게 일치하는 결과를 얻을 수 있었다.

• 한국분무공학회지
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• 제16권3호
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• pp.119-125
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• 2011

Due to the oxygen contents in biodiesel, application of the fuel to compression ignition engines has significant advantages in terms of lowering PM formation in the combustion chamber. In recent days, considerable studies have been performed to extend the low temperature combustion regime in diesel engines by applying biodiesel fuel. In this work, low temperature combustion characteristics of biodiesel blends in dilution controlled regime were investigated at a fixed engine operating condition in a single cylinder diesel engine, and the comparisons of engine performances and emission characteristics between biodiesel and conventional diesel fuel were carried out. Results show that low temperature combustion can be achieved at $O_2$ concentration of around 7~8% for both biodiesel and diesel fuels. Especially, by use of biodiesel, noticeable reduction (maximum 50% of smoke was observed at low and middle loads compared to conventional diesel fuel. In addition, THC(total hydrocarbon) and CO(Carbon monoxide) emissions decreased by substantial amounts for biodiesel fuel. Results also indicate that even though about 10% loss of engine power as well as 14% increase of fuel consumption rate was observed due to lower LHV(lower heating value) of biodiesel, thermal efficiencies for biodiesel fuel were slightly elevated because of power recovery phenomenon.

• 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.