국내 건축물에서는 노후한 철근콘크리트 구조물의 안전성이 중요한 문제로 대두되고 있다. 구조물 부분이나 전체의 무너짐으로 인해 경제적 손실을 초래할 수 있으며, 이는 주로 구성 재료의 내구성 결 함으로 인해 발생한다. 여러 노후화 인자 중 동결융해와 부식은 주요한 열화 요인으로 작용한다. 동결 지역의 구조물은 동결융해가 위험 요소로 작용할 수 있으며, 해양 구조물은 해수에 존재하는 염소이온 에 의해 부식될 수 있다. 이러한 문제를 해결하기 위해서는 복합 열화 작용과 철근콘크리트 부재의 성 능 저하 관계를 이해하는 것이 필요하다. 본 연구는 동결융해와 부식의 복합적 피해가 RC 보의 거동 에 미치는 영향을 실험적으로 조사하였다. 7개의 RC 보를 제작하여 각각 다른 수준의 열화 조건을 부여한 후 휨 시험을 실시하였다.

Silkworms have been developed for food and medicinal purposes, and several silkworm products are commercially available. However, there has been no research on their shelf stability. This study investigated the shelf stability of freeze-dried silkworms during storage at various temperature and humidity conditions, using three lipid oxidation indicators: peroxide, acid, and TBA value. The higher the temperature and relative humidity are, the more significant the three lipid oxidation indicators increase. Among these indicators, the TBA and peroxide values show the highest temperature dependence and humidity dependence, respectively. This study could contribute to the standardization of the shelf life of products made from freeze-dried silkworms.

Due to the growing concern on the adverse effects on human and environment, more attention in the non-chemical pest control methods is gaining. One of the so-called ‘sustainable’ control practice is to physically freeze the insect and arthropod pests. Aerosol formulation uses propellant gas which is liquefied by pressure, and it lowers the temperature when sprayed by the volume expansion. Using this phenomenon, several ‘freeze spray’ products in South Korea and Japan are commercialized. Nonetheless, unlike other traditional aerosol insecticides, the lack of insecticidal substances in these freeze products allowed them to circumvent legal inspection and registration, no efficacy test result is required in commercialization. In the present study, we examined the insecticidal activity of the freeze spray products against German cockroaches and the housefly in the laboratory condition as well as semi-field tests. The temperature of discharged center mass was –40-45℃, but it had relatively small active range (about 3 cm) which required pinpoint application of the product. Moreover, at least 30 sec and 12 sec of direct contact at 30 cm was required to exhibit >90% of mortality in the cockroaches and houseflies in the lab-based tests, respectively. Semi-field tests indicated an average of 15.8 g and 22.0 g were required to spray to knock down the freely-moving cockroaches and houseflies, respectively. Further utility of the freezing products is discussed.

In order to investigate the optimal UVB (ultraviolet B) treatment conditions for vitamin D2 enhancement of freeze-dried ear mushroom, sample size (below 300 μm~whole), UV treatment temperature (30~60℃), treatment density (6.25~50.0 mg/cm2) and the samples mixing frequency (1~32 times) were treated differently. After that, chromaticity, vitamin D2 and ergosterol (vitamin D2 precursor) contents were investigated. As a result of the investigating, effective UVB treatment conditions for vitamin D2 enhancement are as follows. The sample sizes were 2~4 mm and finely crushed pieces. The treatment temperatures were 50℃ and 60℃. The treatment density was 12.5 to 25.0 mg/cm2, and the number of sample mixing was 8 times or more. As the amount of vitamin D2 increased by UVB treatment, the ergosterol content generally tended to decrease. However, under some UVB treatment conditions, the vitamin D2 content was not high despite the decrease of ergosterol content. Under the conditions set in this experiment, it was possible to obtain ear mushrooms with enhanced vitamin D2 up to 26,968.7 μg/100 g. Therefore, it is thought that the ear mushroom is highly likely to be used as a vitamin D source and nutritionally fortified food ingredient.

소비자에게 판매하기 위해 비육을 하여 길러지는 돼지가 아닌 새끼를 낳기 위해 장기간 사육되는 돼지를 모돈이라 한다. 모돈은 규격돈보다 육색이 붉은 것이 특징이며 단단한 조직감으로 인해 잘 소비되지 않는다. 본 연구는 모돈을 가공 원료육으로 활용하기 위해 품질 및 가공특성을 평가하였다. 먼저, 냉동-해동된 모돈과 규격돈의 뒷다리를 이용하여 품질특성을 비교하였으며 가공특성은 유화형소시지를 제조하여 수행하였다. 원료육의 품질특성은 일반성분, pH, 육색, 콜라겐 함량, 조직감, 보수력을 측정하였고 가공특성은 유화형소시지를 제조하여 조직감 및 유화 안정성을 측정하였다. 모돈의 육색은 규격돈보다 붉고(p<0.05), 조직감은 단단하였다(p<0.05). 그러나 pH, 보수력, 콜라겐 함량, 유화 안정성, 소시지의 조직감은 유의적인 차이가 없었다. 결론적으로 모돈의 단단한 조직감은 분쇄를 통해 해결하였으며 대부분의 품질 및 가공특성은 모돈과 규격돈에서 동일하였다. 따라서 모돈을 가공 원료육으로 활용하면 규격돈과 가공특성의 차이가 없음을 확인하였으며, 규격돈에 비해 높은 수율은 제품 원가를 절감할 수 있을 것으로 판단된다.

In this study, the authors investigated the quality characteristics of convenient rice porridge made from powder (PR) and half-rice (HR) sized freeze-dried cooked rice using Samgwang and Jinsumi rice. The hydration properties of the freeze-dried cooked rice and the color, viscosity, spreadability, and sensory evaluation of porridge were measured. PR showed significantly higher water-binding capacity, solubility, and swelling power than HR for both varieties (p<0.05). As a result of the quality characteristic of the porridge, PR showed significantly higher lightness, redness, yellowness, viscosity, and spreadability than HR (p<0.05). Acceptance testing showed that HR had significantly better results for all acceptance attributes than PR (p<0.05). Jinsumi HR showed better consumer acceptance for taste, texture, and overall acceptability than Samgwang HR (p<0.05). Intensity evaluations of sensory properties revealed that the Samgwang PR was more spreadable but was less chewy than Samgwang HR. Furthermore, Jinsumi HR had higher transparency, greater spreadability, and a better cooked-rice odor and savory taste than Samgwang HR (p<0.05). These results confirm that convenient porridges can be produced using freezedried cooked rice.

PURPOSES : The aim of this study is to review freeze-and-thaw testing apparatuses, develop a freeze-and-thaw testing setup with a test protocol, test the freeze-and-thaw properties of soils collected from different parts of South Korea, and suggest an index for frost susceptibility criteria for soils found in South Korea. METHODS : Based on a literature review, a new freeze-thaw testing setup was developed. In addition, a test protocol was developed for freeze-thaw testing. Soils collected from different parts of South Korea and bedding sand used for block pavements were tested to determine whether the measurements from the newly developed test setup could capture important freeze-thaw characteristics of the soils. Finally, to develop local frost susceptibility criteria, a parameter including both the vertical deformation and thermal conductivity characteristics of the soils was suggested. RESULTS : The results from the laboratory experiments indicate that the newly developed freeze-and-thaw setup captures the required parameters to quantify the responses of soils subjected to cyclic freeze-and-thaw testing. In addition, a vertical deformation of up to 2.437 mm is measured. Moreover, seven soils out of the nine tested soils are classified as having a medium frost susceptibility, whereas the remaining two show low frost susceptibility. The bedding sand experiment also shows that there is a possibility of having a frost susceptible condition based on the moisture content. When submerged, the bedding sand is classified as having a medium frost susceptibility. CONCLUSIONS : The "HEART" freeze-thaw testing setup was able to capture the parameters required for evaluating the frost susceptibility of soils. This setup and testing procedure could be further used to test and prepare criteria for classifying the frost susceptibility of soils found in South Korea.

This study introduces the Three-Memory-Model (Cherry, 2019) in education into Maritime Simulator- based training in Sri Lanka and conducts empirical research. In simulator-based education what is disseminated as knowledge during the Briefing, Scenario and Debriefing phases must be transferred from short-term, across working memory to long-term-memory. Working memory gained during the scenario phase, could be encoded into long-term-memory through rehearsal probes. But the number of probes which could be tolerated by the participants of simulator-based training has not undergone empirical investigation. Thus, selecting the Open Sea scenario phase as its setting the research questions aim to identify tolerance limits in the participants for the number of freezes and the number of probes introduced during each freeze. The methodology selects a population of seafarers (n = 60). Through stratified random sampling this population was subdivided based on experience at sea as Group A (n = 30): Mean of 2 years and Group B (n = 30): Mean of 13.6 years of sea experience. The duration of the open sea scenario phase is 35 minutes with freezes at 10-minute intervals. The number of probes were given a range of 7 to. Data analysis utilized SPSS. The highest percentage mean value was obtained for three freezes for the Open Sea scenario phase while two freezes had the next highest percentage mean value. The mean value of the tolerance limits for questions during one freeze is approximately 9 and 6 probes for Group A and B respectively. Citing prior research on working memory, visuo-spatial vs. verbal working memory, reaction time and age this study raises a counter argument against the findings: the self-declared tolerance limits of the number of questions the participants feel comfortable to answer during each freeze. The findings of this research are valuable to maritime Simulator-based instructional designers outside and within Sri Lanka.

The synthesis of porous W by freeze-casting and vacuum drying is investigated. Ball-milled WO3 powders and tert-butyl alcohol were used as the starting materials. The tert-butyl alcohol slurry is frozen at –25oC and dried under vacuum at –25 and –10oC. The dried bodies are hydrogen-reduced at 800oC and sintered at 1000oC. The XRD analysis shows that WO3 is completely reduced to W without any reaction phases. SEM observations reveal that the struts and pores aligned in the tert-butyl alcohol growth direction, and the change in the powder content and drying temperature affects the pore structure. Furthermore, the struts of the porous body fabricated under vacuum are thinner than those fabricated under atmospheric pressure. This behavior is explained by the growth mechanism of tert-butyl alcohol and rearrangement of the powders during solidification. These results suggest that the pore structure of a porous body can be controlled by the powder content, drying temperature, and pressure.

In the present study, we examined the effect of different lecithin concentrations on spermatozoa characteristics after freeze-thawing. Hanwoo semen was collected from one bull and divided into five groups (tris-citric acid semen extender with 0, 0.1, 0.25, and 0.5% lecithin groups as well as a 20% egg yolk group). Semen extender with 20% egg yolk was used as control treatment. After the freeze-thawing of semen, spermatozoa motility, motility parameters, viability, acrosomal membrane integrity, mitochondrial membrane potential, and plasma membrane integrity were examined. In experiment 1, the effect of different lecithin concentrations on spermatozoa motility and associated parameters was examined. The 0.1% lecithin-treated spermatozoa showed greater fast progressive motility (%) in addition to higher VCL (μm/s), VSL (μm/s), and VAP (μm/s) when compared to other lecithin concentration groups and controls. In experiment 2, the effect of different lecithin concentrations on spermatozoa viability was examined. The 0.1% and 0.25% lecithin addition groups (55.4±7.3 and 51.7±11.2%) exhibited similar viability compared to the control group (54.1±12.6%). In experiment 3, the effects of different lecithin concentrations on viability, acrosomal membrane integrity, and mitochondrial membrane integrity of spermatozoa were examined. The percentage of live spermatozoa with an intact acrosome and high mitochondrial membrane potential in the 0.1% lecithin group was not significantly different compared to the control group (31.2±13.3 vs. 30.5±10.9%). In experiment 4, the effect of different lecithin concentrations on the plasma membrane integrity of spermatozoa was examined. The percentage of spermatozoa with a normal plasma membrane was similar between the 0.1% lecithin and control groups (31.2±13.3 vs. 30.5±10.9%). In conclusion, we suggest that semen extender supplemented with 0.1% lecithin can replace 20% egg yolk without reducing spermatozoa quality.

The effects of drying temperature on the microstructure of porous W fabricated by the freeze-casting process of tert-butyl alcohol slurry with WO3 powder was investigated. Green bodies were hydrogen-reduced at 800oC for 1 h and sintered at 1000oC for 6 h. X-ray diffraction analysis revealed that WO3 powders were completely converted to W without any reaction phases by hydrogen reduction. The sintered body showed pores aligned in the direction of tertbutyl alcohol growth, and the porosity and pore size decreased as the amount of WO3 increased from 5 to 10v ol%. As the drying temperature of the frozen body increased from -25oC to -10oC, the pore size and thickness of the struts increased. The change in microstructural characteristics based on the amount of powder added and the drying temperature was explained by the growth behavior of the freezing agent and the degree of rearrangement of the solid powder during the solidification of the slurry.

Fresh Omija (Schisandra chinensis) has good marketability, but its quality is difficult to maintain during storage and distribution. Freezing and freeze-thawing treatments can be utilized for the quality maintenance and processing of cold press juice. In this study, the color, antioxidant properties, and the major components of soaked liquor from Omija with freeze-thawing treatment were analyzed during the extraction periods. Each of the frozen and freeze-thawed Omija samples was soaked in 35% ethanol, extracted for 15 days, and used for analysis. The frozen and freeze-thawed samples showed a tendency toward better color and higher antioxidant activity and major component levels than the controls, and freeze-thawing was the best. The results of this study showed that freeze-thawing treatment improved the color, antioxidant properties, and level of the major components of Omija soaked liquor, and freeze storage is suitable for making soaked liquor.

The effect of tert-butyl alcohol (TBA) as a freezing solvent on the pore structure of a porous tungsten body prepared by freeze-drying is analyzed. TBA slurries with a WO3 content of 10 vol% are prepared by mixing with a small amount of dispersant and binder at 30oC. The slurries are frozen at -25oC, and pores are formed in the frozen specimens by the sublimation of TBA during drying in air. After hydrogen reduction at 800oC and sintering at 1000oC, the green body of WO3 is completely converted to porous W with various pore structures. Directional pores from the center of the specimen to the outside are observed in the sintered bodies because of the columnar growth of TBA. A decrease in pore directionality and porosity is observed in the specimens prepared by long-duration drying and sintering. The change in pore structure is explained by the growth of the freezing solvent and densification.

The feasibility of infrared assisted freeze drying (IRAFD) was evaluated for shelf stable sea cucumber to improve the traditional drying methods such as freeze drying (FD), vacuum drying (VD) and hot air drying (AD, 60, 80, 100oC). Infrared (IR) radiant energy was provided to accelerate the drying rate of freeze drying (FD). IRAFD had the most rapid drying rate among IRAFD, FD and VD. IRAFD showed drying time of 13.7 h followed by VD (18.7 h) and FD (24.3 h). In the final moisture content of sea cucumber, it decreased down to 3.25% at IRAFD. However, FD and VD could not reduce down the moisture content of sea cucumber below 7%. Quality attributes of AD sea cucumber were not acceptable with very low restoration rate and excessive hardness. For example, AD 100 had very low weight restoration rate of 23% and hardness of 22 N. IRAFD showed quite high restoration rates (weight: 50%, width: 82%, length: 91%) and acceptable hardness of 3.1 N. IRAFD consumed the minimal electrical energy of 120 kJ as compared to 209 kJ of FD. This study showed the potential application of IRAFD to produce the shelf stable dried sea cucumber with microbial safety.