• Journal of the Korean Wood Science and Technology
• /
• 제22권1호
• /
• pp.66-71
• /
• 1994

To increase drying rate and reduce drying degradation, pretreatments such as prefreezing and presteaming have been widely used in wood industries. Presteaming lumbers prior to kiln drying is known positively to improve its permeability, to increase diffusion coefficient and to reduce discoloration, but negatively to increase collapse. Prefreezing lumbers prior to kiln drying is also known to reduce significantly its drying defects and its shrinkages. Thus it is no doubt that the pretreated lumbers shrink diversely from the untreated. In this study the shrinkage behaviors of the pretreated specimens are investigated by drying two tropical hardwoods (Apitong and Taun) in three different dying conditions: high temperature and slow drying rate (drying in a closed cylinder), high temperature and rapid drying rate (drying in an oven) and low temperature and slow drying rate(drying at room temperature). The prefrozen specimens show the least volumetric shrinkages in most drying conditions. The specimens dried in cylinders shrink most among all drying conditions. In general the pretreated specimens reached the 30 % moisture content faster than the untreated by about 30 %.

• Journal of the Korean Wood Science and Technology
• /
• 제23권3호
• /
• pp.28-32
• /
• 1995

The presteamed or prefrozen persimmon blocks of 10cm ${\times}$ 10cm ${\times}$ 15cm were air-dried at room temperature until about 30% moisture content, and then were dried in a MW oven. During drying their internal temperatures were monitored with thermo-couple probes. The presteamed and prefrozen blocks didn't show any improvement in drying rate and moisture gradient when compared with the controls. Checks appeared on the surfaces of most presteamed blocks during air-drying. It has been clearly revealed that the maximum weight, loss must, be less than 2g/min during MW drying to prevent internal checking and that MW drying reduced moisture gradients inside blocks. MW dried the persimmon blocks 440 times faster than conventional kiln.

• 한국자원식물학회지
• /
• 제15권2호
• /
• pp.89-95
• /
• 2002

자작나무 식물유전자원의 효과적인 장기보존 방안을 구명하기 위해 동결전처리 된 겨울철 동아를 건조처리에 의해 초저온보존 시험하여 다음과 같은 결과를 얻었다. 자작나무 동아는 내동성이 최고조에 달한 1월 20일경의 함수율이 42.43%로 가장 낮게 나타났다. 1월 20일에 채취한 동아를 10분간의 건조처리 와 5~-2$0^{\circ}C$까지 1분당 1$^{\circ}C$ 하강조건으로 완속동결 전처리하여 -196$^{\circ}C$의 액체질소에 초저온 보존한 경우의 세포생존율은 83.33%로 가장 이상적인 처리조건으로 조사되었다. 자작나무 동아의 시료조제는 동아에 약간의 목질부 조직을 붙여 초저온 보존하는 경우에 86.7%로 세포생존율이 높게 나타났다. 24시간 이상 액 체질소에 초저온 보존한 자작나무 동아는 40$\pm$5$^{\circ}C$의 온수 중에서 급속 해동하는 경우가 86.6%의 세포생존율을 비롯하여 60%의 식물체 재생율을 나타내어 본 실험에서 가장 효과가 좋은 것으로 조사되었다.

• Journal of the Korean Wood Science and Technology
• /
• 제25권3호
• /
• pp.66-74
• /
• 1997

Liquid permeabilities of red oak and several softwoods were measured by the pressure bomb method and a modified liquid permeability method in order to investigate their efficacy. The effect of preboiling and prefreezing on wood permeability were also examined for both green and resaturated specimens. Regardless of some disadvantages these two methods were revealed as a handy tool for quick evaluation of the permeability of an unknown species. The permeabilities of the resaturated specimens increased when preboiled. but decreased when prefrozen. For green specimens, however, pre freezing increased permeability. The discrepancy of the pre freezing effect on two specimens partially attributes to their difference of initial permeabilities. For all species except radiata pine heartwood, the radii of the effective capillary pores, derived from the water potential equation, distribute from $0.42{\mu}m$ to $7.2{\mu}m$. Those of radiata pine heartwood are below $0.46{\mu}m$.

• 대한수의학회지
• /
• 제24권2호
• /
• pp.245-266
• /
• 1984

As a fundamental study to increase the reproductive efficiency in cattle, highly motile sperm were separated and collected from raw semen, extended semen and frozen semen by different methods using various concentrations of bovine serum albumin or Tyrode's solution. Various characteristics and light microscopic and electron-microscopic morphology of sperm separated by different methods were compared. The results obtained were as follows; 1. The sperm separated from raw semen using bovine serum albumin showed significantly high value in motility, motile sperm count, percent of normal sperm and progressive motility, as compared with control sperm and revealed the highest sperm recovery rate when separated with 6% bovine serum albumin. 2. The sperm motility, percent of normal sperm and progressive motility of the highly motile sperm frozen after being separated from raw semen with bovine serum albumin, showed significantly high value than those of a control sperm and especially found the highest value when separated with 20% bovine serum albumin. 3. Light-microscopic percent of abnormality was significantly low in the prefrozen and postfrozen highly motile sperm separated with bovine serum albumin, as compared with control sperm. 4. Electron-microscopic finding of the highly motile sperm separated with bovine serum albumin showed low percent of deformity in the dilatation and vesiculation of cell membrane, in dilatation and density loss of acrosome than in those of control sperm. 5. It was impossible to separate the highly motile sperm from frozen semen with bovine serum albumin, but it was possible with Tyrode's solution. 6. Recovery rate of highly motile sperm from raw semen extended semen and frozen semen was the highest when the sperm pellet stood in Tyrde's solution for 80 minutes. 7. The highly motile sperm separated from raw semen, extended semen and frozen semen with Tyrode's solution showed significantly high value in motility, progressive motility and percent of normal sperm, as compared with control sperm. 8. Highly motile sperm, when separated from raw semen, extended semen and frozen semen with Tyrode's solution, showed significantly low percent of microscopic abnormality as compared with control sperm.