• 한국가축번식학회지
• /
• 제18권1호
• /
• pp.15-23
• /
• 1994

This study was carried out to investigate the effects of concentration, kinds of cryoprotectants, equilibration time, optimum thawing temperature on the survival rate of rapidly frozen porcine embryos. The porcine embryos following dehydration by cryoprotectants containing sucrose were directly plunged into liquid nitrogen and thawed in 30, 35 or 37$^{\circ}C$ water bath, Survival rate was defined as development rate on in vitro culture or FDA-test. The results are summarized as follows : 1. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was attained 2.0M DMSO, 2.0M glycerol, 2.0M propanediol, 1.5M ethyleneglycol. 2. The high survival rate of porcine frozen embryos after rapidly thawed in freezing medium was obtained using single cryoprotectant(16.6~40.0%) than mixed cryoprotectants(12.5~33.3%). 3. The eqilibration time on the survival rate of rapidly thawed porcine frozen embryos was attained after short period of time(15.0~33.3%) in the freezing medium higher than long period of time(9.10~30.0%). 4. The thawing temperature on the survival rate of rapidly thawed porcine frozen embryos was attained at 3$0^{\circ}C$ of thawing temperature(33.3~40.6%) in the freezing medium higher than 25 or 37$^{\circ}C$ of thawing temperature.

• Journal of Biosystems Engineering
• /
• 제26권4호
• /
• pp.331-336
• /
• 2001

This study was to develop a kerosene flame weeder. An air compressor was driven though the PTO of a tractor to provide necessary air for fuel combustion and proper pressure to supply fuel from fuel tank to the nozzle. It was found that the flame was extinguished very easily by wind and vibration of the tractor. This trouble could be solved by attaching a burner cap, which is a modified venturi tube, at the end of the nozzle. The constructed flame weeder was tested for the weeding capability in the prepared field. Weed extinction rate and weight decrease rate were analysed. Measured maximum flame temperature was 1,121$\^{C}$ when the fuel consumption was 13.41 kg/h and fuel supply pressure was 88.2 kPa. The maximum temperature occurred at 20cm from the front end the burner, and it decreased to 46$\^{C}$ as the distance increased to 110cm. The flame length of up to 70cm, where the flame temperature was higher than 372$\^{C}$, would be used for weeding purpose. Weed extinction rate and weight decreasing rate increased as the fuel consumption increased. The flame weeder was evaluated to be a practical weeder through improvement as the weed extinction rate and weight decrease rate were analysed to be 75% and 85%, respectively when the fuel consumption was 116.87kg/ha.

• Nuclear Engineering and Technology
• /
• 제48권6호
• /
• pp.1376-1386
• /
• 2016

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to understand clearly the fracture behavior of piping materials under seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature and the operating temperature of nuclear power plants (i.e., $316^{\circ}C$). SA508 Gr.1a low-alloy steel and SA312 TP316 stainless steel piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 stainless steel was independent of the loading rate at both room temperature and $316^{\circ}C$. For SA508 Gr.1a lowalloy steel, the loading rate effect on the fracture behavior was appreciable at $316^{\circ}C$ under cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio of the load (R) was -1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = -1 at a quasistatic loading rate.

• Current Research on Agriculture and Life Sciences
• /
• 제32권3호
• /
• pp.165-169
• /
• 2014

계란 세척기 평가 금액 추정 결과는 다음과 같다. 계란 세척기 총수입(인건비 절감으로부터의 조수입 증대)에서 산정하였으며, 계란 세척기 총비용은 구입가격, 고정비용 및 유동비용의 합계로 나타내었다. 계란 세척기 평가액은 할인율 수준에 따라 최소 44,778천원(할인율 10%)에서 최대 45,778천원(할인율 5%), 평균 45,278천원으로 추정된다(Table 7). 계란세척기의 경제적 타당성을 살펴보면, 내부수익율 IRR의 값은 가정했던 할인율(5%~10%)보다 훨씬 높고, 순현재가치(NPV)는 0보다 훨씬 크며, B/C 비율도 1.0 이상으로 나타나 계란 세척기 개발사업의 경제적 타당성은 있는 것으로 판단된다(Table 8).

• 한국육종학회지
• /
• 제40권3호
• /
• pp.228-233
• /
• 2008

This study was carried out to get the genetic information on the germination rate and fat acidity after 12 weeks' storage at $35^{\circ}C$. Germination rate decreased with longer storage period, while fat acidity increased. Germination rate was higher in the order of Koshihikari, Hanmaeum and Unkwangbyeo after 12 weeks' storage at $35^{\circ}C$. Fat acidity of Koshihikari and Hanmaeum was gradually increased, but that of Unkwangbyeo was dramatically increased after 4 weeks' storage at $35^{\circ}C$. The genetic mode on germination rate and fat acidity using the joint scaling test was shown to be additive-dominance gene effects. Additive([d]) effect was higher than dominance effect([h]) in all crosses. The average degree of dominance, [h]/[d], was less than 1, indicating that germination rate and fat acidity was partially dominant. Germination rate and fat acidity based on frequency distribution of 2 crosses were quantitative characters expressed by polygenes.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집E
• /
• pp.456-462
• /
• 2001

Comprehensive numerical computations are made of a homogenous spin-up in a cylindrical cavity with a time-dependent rotation rate. Numerical solutions are acquired to the governing axisymmetric cylindrical Navier-Stokes equation. A rotation rate formula is ${\Omega}_f={\Omega}_i+{\Delta}{\Omega}(1-{\exp}(-t/t_c))$. If $t_c$ is large, it implies that a rotation change rate is small. The Ekman number, E, is set to $10^{-4}$ and the aspect ratio, R/H, fixed to I. For a linear spin-up(${\epsilon}<<$), the major contributor to spin-up in the interior is not viscous-diffusion term but inviscid term, especially Coriolis term, though $t_c$ is very large. The viscous-diffusion term only works near sidewall. But for spin-up from rest, when $t_c$ is very large, viscous-diffusion term affects interior area as well as sidewall, initially. So azimuthal velocity of interior for large $t_c$ appears faster than that of interior for relatively small $t_c$. However, the viscous-diffusion term of interior decreases as time increases. Instead, inviscid term appears in the interior.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
• /
• pp.346-353
• /
• 2001

Zirconia powder containing 3 mol% yttria(3Y-PSZ) with and with out Fe$_2$O$_3$ addition was coated on tile cast iron substrate by plasma spraying method. The erosion experiments were performed at temperatures from $25^{\circ}C$ to $600^{\circ}C$. A gas blast type erosion tester was used to examine erosion behavior of the specimens. The results of 3Y-PSZ coatings showed that tile erosion rate had maximum value at 40$0^{\circ}C$. It coincided with tile results of phase transformation tetragonal phase to monoclinic phase caused by low temperature thermal degradation. The tensile stress relaxation and the micro-hardness improvement significantly influenced on the erosion rate at $600^{\circ}C$. In the case of Fe$_2$O$_3$ added 3Y-PSZ coatings, the erosion rate of tested at $25^{\circ}C$ showed maximum value at 5.0 mol% Fe$_2$O$_3$ added coating. This tendency is caused by the improvement of mechanical properties and the tensile residual stress. The erosion rate at 200'c and 400'L showed significantly decrease by Fe203 addition. This decrease is believed to be the stabilization of the tetragonal phase and the increase of micro-hardness.

• 유기물자원화
• /
• 제15권4호
• /
• pp.131-137
• /
• 2007

황산염 환원조건에서의 리그노셀룰로오스의 분해에 대하여 고찰하였다. 특히, 리그닌에 대한 셀룰로오스의 비(C/L 비)를 각각 42.15, 4.59, 2.51, 1.14, 0.7로 하여 리그닌과 셀룰로오스의 상호작용에 대하여 고찰하였다. 셀룰로오스의 분해율은 1차 반응식에 의해 계산되어져, C/L 비가 감소할수록 반응상수는 감소하여 셀룰로오스의 분해에 대한 리그닌의 저해작용을 보여 주였다. 1차 반응식에 의한 반응상수와 리그닌의 함량의 증가에 대한 셀룰로오스의 분해율은 0.97의 $R^2$ 값을 가지며 로그힘수에 의해 표현할 수 있었다. 리그노셀룰로오스의 분해율 또한 C/L 비와 로그함수의 관계를 가지며 리그닌의 함량이 많을수록 감소하였다. 리그닌의 분해율은 C/L 비가 2.51 및 1.14인 조건에서 4.59 및 0.7의 조건보다 높게 나타나, 공동기질로서의 과도한 탄소원은 리그닌분해에 장애가 됨을 보여 주였다.

• 한국발생생물학회지:발생과생식
• /
• 제20권2호
• /
• pp.81-90
• /
• 2016

The effect of sudden changes of water temperature (WT) on the survival rate and physiological responses of the red spotted grouper (Epinephelus akaara) were examined by manipulating WT control system for 9 days. Experimental condition was divided in two different regimes at low (from $10^{\circ}C$ to $4^{\circ}C$, decreased $1^{\circ}C/d$) and high (from $28^{\circ}C$ to $34^{\circ}C$, increased $1^{\circ}C/d$) WT. Survival rate of experimental fishes were observed, and determined the changes of hematological characteristics by analyzing plasma levels of cortisol, glucose, total protein, and electrolytes ($Na^+$, $Cl^-$, $K^+$). No mortality was observed until low WT $6^{\circ}C$ (144 h) and high WT $32^{\circ}C$ (96 h), and 100% mortality was observed at low WT $4^{\circ}C$ (216 h) and high WT $35^{\circ}C$ (171 h). Plasma levels of cortisol and glucose increased rapidly as decreasing WT, and the loss of swimming ability and respiration response was observed at low WT $7^{\circ}C$ and high WT $34^{\circ}C$ conditions.

• 생태와환경
• /
• 제42권1호
• /
• pp.32-38
• /
• 2009

긴꼬리투구새우 알의 온도별 부화율을 파악하기 위하여 여러 온도조건 (10, 15, 20, 25, 30, 35, 40, 45, $50^{\circ}C$)으로 설정된 인큐베이터에서 실험을 수행하였다. 실험재료로 사용된 긴꼬리투구새우의 알은 2006년 7월 경상북도 안동시 일대의 농경지에서 포획한 것이다. 부화 성공률은 $35^{\circ}C$에서 80.0 (${\pm}9.43$)%로 가장 높게 나타났다. 온도조건 중 $10^{\circ}C$와 $50^{\circ}C$에서는 부화 현상이 일어나지 않았다. 본 연구 결과 긴꼬리투구새우의 부화 최저임계온도는 $6.66^{\circ}C$, 최적 부화 온도는 $35^{\circ}C$로 나타났으며, 부화 가능 온도 범위는 $15{\sim}45^{\circ}C$로 비교적 넓은 것으로 확인되었다.