콘크리트 포장의 평탄성과 내구성은 환경 조건에 크게 영향을 받으며, 슬래브 상하부 간의 온습도 차이는 부등건조수축 및 와핑 (Warping) 현상을 유발하여 포장의 장기 성능 저하를 초래할 수 있다. 이는 주행성 저하, 균열 발생, 유지보수 비용 증가의 원인이 되 며, 특히 터널과 같은 특수 환경에서는 상하부 간의 습도 차이가 더욱 크게 나타나 부등건조수축이 심화될 가능성이 높다. 터널 내부 는 직사광선의 영향을 받지 않지만, 통풍이 잘 이루어져 건조한 환경이 조성되며, 이러한 조건에서는 슬래브 상부에서 수분 손실이 가 속화되고 하부는 습윤 상태를 유지하여 상하부 간의 큰 습도 차이를 발생시킨다. 이는 슬래브의 비균일한 수분 이동을 유발하여 부등 건조수축을 더욱 크게 발생하게 한다. 국내에서는 터널 길이가 500m 이상인 장대 터널에서 콘크리트 포장 적용이 증가하고 있으며, 아스팔트 포장 대비 화재 시 유독가스 발생 위험이 낮다는 이유로 국토교통부에서 콘크리트 포장을 권장하고 있다. 이로 인해 터널 내 콘크리트 포장의 사용이 증가하고 있 으나, 기상환경 변화 및 습도 관리 미흡으로 인해 콘크리트 포장 줄눈부에서의 평탄성 불량 문제가 빈번하게 발생하고 있다. 이러한 문제는 주행성 저하, 도로 이용자의 민원 증가 및 유지보수 비용 상승을 초래하고 있어, 구체적인 원인 분석과 대책 마련이 필요한 실 정이다. 따라서 본 연구는 터널과 같은 특수 환경에서 습도 조건이 콘크리트 슬래브의 부등건조수축에 미치는 영향을 실험적으로 분석하고, 슬래브의 수평 변형률 및 수직 변위를 측정하여 건조 수축에 따른 변형 거동을 정량적으로 평가하고자 하였다. 다양한 습도 조건에서 슬래브의 변형 양상을 비교 분석함으로써, 터널 환경에 적합한 콘크리트 포장 설계 및 유지관리 기준을 제시하고, 콘크리트 포장의 장 기 성능을 개선하기 위한 대책을 마련하고자 한다.

In this study, in order to develop an foaming tablet product using yuzu powder, yuzu powder was manufactured using different drying methods such as freeze-drying, 60℃ drying, and 40℃ drying, and then quality characteristics and functionality were analyzed. The naringin content per g of yuzu powder was 8.9 mg for freeze-drying and 8.8 mg for 60℃ drying, and the hesperidin content per g of yuzu powder was highest at 53.6 mg for freeze-drying and 46.2 mg for 60℃ drying. followed by 40℃ drying (41.7 mg). The tyrosinase inhibitory activity of 60℃ dried powder was found to be twice as high as that of freeze dried powder. Accordingly, in order to develop an inner beauty product, foaming tablets were manufactured using hot air dried powder, and the quality characteristics and functional ingredients of the final foaming tablets were investigated. The foaming tablet prepared with yuzu powder content of 10 and 15% showed an inhibitory activity of tyrosinase of 73.7 %, which was 1.6 times higher than that of ascorbic acid (1 mM), which was a positive control, confirming its melanin production inhibition effect.

This study explored a method to enhance the drying process usability of local mangoes by producing foam-mat dried powder under varying drying temperatures (50, 60, 70°C) and foam thicknesses (3, 6, 9 mm). The drying process period ranged from 60 to 390 minutes based on the set conditions, with higher temperatures and thinner foams accelerating drying. Powder chromaticity (L*, a*, and b*) demonstrated a declining trend with increasing drying temperature and foam thickness, exhibiting notable variance in chroma values. The water absorption index varied significantly, between 3.08 to 4.24, under different drying conditions, although the water solubility index remained consistent across foam-dried samples. Powder moisture content ranged from 2.53% to 3.83%, with hygroscopicity escalating with temperature and foam thickness. Vitamin C structure was compromised during the hot air drying process, especially at temperatures above 60°C. Electronic nose analysis distinguished foam-dried powder from freeze-dried powder; however, a thicker foam yielded a scent profile closer to that of freeze-dried powder. The findings provide fundamental data on mango foam drying, which is expected to improve processing and storage tech for local mangoes.

This study investigated the antioxidant characteristics of sweet potato according to different plant parts and drying methods. The sweet potato plant parts were divided into root tubers, stems, stalks, leaves, and tips, and the drying methods were freeze-drying and hot air drying. Total polyphenol and flavonoid contents and radical scavenging activity of the sweet potato plant parts were significantly different depending on the plant parts and drying methods. The total polyphenol content of freeze-dried sweet potato leaves and tips were 52.76 and 46.19 mg chlorogenic acid equivalents/g sample, and the total flavonoid contents were 222.47 and 214.12 mg quercetin equivalents/g sample, respectively, and decreased with hot air drying. DPPH radical scavenging activity was higher in freeze-drying than hot air drying and was significantly different depending on the plant parts. The ABTS radical scavenging activity of freeze-dried sweet potato leaves and tips were 43.48 and 44.68 mg Trolox equivalents/g sample, respectively, and decreased with hot air drying. Therefore, additional studies on the functionality of using by-products from sweet potato cultivation are needed.

Black Soldier Fly Larvae (Hermetia illucens, BSFL) is an environmental purification insect utilized as an animal feed source due to its high protein content. BSFL need to be dried to preserve quality, and the optimal drying method should be cost-effective. In this study, various drying methods (hot air (HD), freeze (FD), vacuum (VD), and combined-drying (CD)) were applied to BSFL, and then BSFL powders were characterized. Crude protein content was highest in HD and lowest in CD, and there was no significant difference in crude fat content (p>0.05). In the measurement of the total amino acid content of BSFL, glutamic acid and aspartic acid were the highest regardless of the drying method. The total amino acid content was the highest in HD and the lowest in CD. Total polyphenol content was higher in VD and FD than in HD and CD. Also, hydrogen peroxide and DPPH radical scavenging showed similar results. In the antioxidant measurement results, VD and FD showed higher antioxidant capacity, but considering cost-effectiveness, HD was the most available method for drying BSFL.

This study aims to investigate the effect of drying temperatures on the quality characteristics and physicochemical properties of vegetables. Lettuce and napa cabbage were dried at 40, 50, and 60oC and analyzed for various quality indexes. Higher drying temperature induced the lower L* and higher a* and b* values of samples. Also, it resulted in lowering the rehydration ratio, pH, and total free amino acid content of dried vegetables. The outcome might be due to the damage to the internal structure of vegetables and the decomposition of free amino acids during thermal treatment. Higher drying temperatures led to higher soluble solid and total polyphenol contents due to the conversion of phenolic compounds from combined to free form during the drying process, which changed phenolic compounds from combined to free form. Consequently, samples dried at higher temperatures had higher DPPH radical scavenging ability. The final moisture content and drying time decreased as the drying temperature increased; moreover, the antioxidant activity increased. A lower drying temperature is beneficial to maintaining the chemical characteristics of crops.

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.

본 연구에서는 지방 산화를 억제하고 품질이 우수한 부세 굴비의 가공법을 개발하기 위해 대두와 멸치의 복합 발효소재를 첨가한 염지제 처리 및 건조 시간에 따른 부세 굴비를 제조하여 품질 특성을 비교하였다. 발효소재 첨가에 따른 염지제와 부세 굴비의 DPPH 및 ABTS 라디칼 소거능은 발효소재의 함량에 따라 증가하였으나, 발효소재 1% 이상에서 부세 굴비의 라디칼 소거능은 유의적인 차이를 보이지 않았다. 발효소재의 함량이 증가할수록 부세 굴비의 아미노태질소 함량은 증가하고 VBN, TBARS, 산가는 감소하는 결과를 나타내나, 발효소재 1% 이상에서 품질의 유의적인 차이가 크지 않으므로 염지제의 발효소재 함량은 1%로 선정하였다. 염지제의 염도에 따른 부세 굴비의 품질을 분석한 결과 염도가 증가할수록 아미노태질소 함량은 증가하고 히스타민, VBN, TBARS, 산가는 감소하는 결과는 나타내며, 염지제의 염도는 품질 개선 효과가 가장 우수한 7% 조건을 선정하였다. 염지 처리 후 건조 시간에 따른 부세 굴비의 품질을 분석한 결 과 건조 시간이 증가할수록 수분은 감소하고 염도, pH, 아미노태질소, 히스타민, VBN, TBARS, 산가는 증가하였다. 그러나 건조 48시간 이하는 수분이 많아 저장성이 낮으며, 건조 96시간에서 히스타민과 산패도의 증가율이 높아지므로 부세 굴비의 건조 시간은 72시간이 적합한 것으 로 판단되었다.

This study was conducted to develop a high-moisture food waste dryer that uses steam as a direct heat source to improve the drying speed. Another objective was to verify its performance through experiments. A dryer with a drying capacity of 10,000 kg/hr, which uses steam from an incineration plant as a drying heat source, was fabricated. The performance and applicability of the dryer were verified through drying experiments, in which the food waste collected from large restaurants near the incineration plant was used as the experimental material. The drying experiment results showed that the input steam temperature increased by 21℃ from approximately 145℃ to 166℃ compared to the case in which drying was performed by converting steam into heated air. The drying speed increased by 1.5 times from approximately 0.63 to 0.94 %/hr, and drying up to approximately 20%(wb) moisture content was possible. The drying energy rate, which represents the ratio of the energy consumed for drying to the input energy, increased by approximately ten times from 7.17% to 70.87%. The total drying time still remained approximately 100 hr due to the re-condensation of moisture. When steam was directly used as a drying heat source to improve the drying speed of food waste containing high moisture, the drying speed, water content after drying, and drying energy rate were clearly improved compared to the case in which steam was converted into heated air for use. Therefore, it was deemed necessary to develop a dryer that directly uses steam from an incineration plant for drying. To shorten the total drying time, it is necessary to develop a device that solves the problem of moisture condensation in the dryer.

The effect of sublimable vehicles on the pore structure of Cu fabricated by freeze drying is investigated. The 5 vol% CuO-dispersed slurries with camphene and various camphor-naphthalene compositions are frozen in a Teflon mold at -25oC, followed by sublimation at room temperature. After hydrogen reduction at 300oC and sintering at 600 °C, the green bodies of CuO are completely converted to Cu with various pore structures. The sintered samples prepared using CuO/camphene slurries show large pores that are aligned parallel to the sublimable vehicle growth direction. In addition, a dense microstructure is observed in the bottom section of the specimen where the solidification heat was released, owing to the difference in the solidification behavior of the camphene crystals. The porous Cu shows different pore structures, such as dendritic, rod-like, and plate shaped, depending on the composition of the camphornaphthalene system. The change in pore structure is explained by the crystal growth behavior of primary camphor and eutectic and primary naphthalene. Keywords: Porous Cu, Pore structure

건조방법을 달리한 늙은 호박의 품질 특성 및 항산화를 비교하기 위하여 건조하지 않은 늙은 호박을 대조군으로 하였고, 자연건조, 열풍건조, 동결건조의 조건에서 늙은 호박을 제조하였다. 건조한 늙은 호박의 수분함량은 건조한 늙은 호박 중 동결건조에서 가장 높았고, 자연건조와 열풍건조는 유의적 차이를 나타내지 않았다. 가용성 고형분은 대조군에서 가장 낮았으며, 건조 방법을 달리한 늙은 호박 간의 유의적 차이가 없었다. pH의 결과는 동결건조에서 가장 높았으며, 자연건조에서 낮았다. 적정산도는 열풍건조에서 가장 높았고, 자연건조에서도 높은 경향을 보였으나, 동결건조에서 낮은 경향을 나타냈다. 색도 측정 결과, 명도는 동결건조에서 증가했고, 적색도와 황색도는 열풍건조에서 높은 결과를 보였으며, 갈변도 또한 열풍건조에서 높은 값을 나타냈다. 총당의 분석한 결과, 동결건조에서의 함량이 가장 높았으며, 대조군에서 낮은 함량을 나타냈다. Texture를 측정한 결과, 경도, 응집력, 검성, 씹힘성은 대조군에 비해 건조한 시료에서 높은 수치를 보였으며, 건조방법을 달리한 시료 간의 유의적 차이는 나타나지 않았다. DPPH 및 ABTS 라디칼 소거능 측정 결과는 열풍건조와 동결건조가 높은 수치를 보여 열풍건조와 동결건조시킨 늙은 호박이 기능성에 좋은 영향을 나타낼 것으로 판단된다. 본 연구 결과, 열풍건조와 동결건조시킨 늙은 호박이 품질 특성과 기능성이 전반적으로 우수하다고 판단되나, 경제적 측면을 고려했을 때, 열풍건조 방법이 건조 늙은 호박의 제조 방법으로 적합할 것으로 생각된다.

The aim of this study is to investigate the effects of combined drying conditions on the quality characteristics of lotus root chips. A combined drying was conducted using the superheated steam (SHS) at 220°C for 6 min, then subsequent contact drying at 150°C for specified times (2, 4 or 6 min) and finally hot air at specified temperatures (50, 60 or 70°C) for 1 hr. Changes in appearance of lotus root chips such as surface color, shrinkage and deformed shape were resulted from the extent of time and temperature of post-drying conditions. Moisture content of lotus root chips decreased with increasing the time and temperature of post-drying process. Surface color of lotus root chips was determined mainly by the contact drying step of a combined drying process. Polyphenol content was influenced by the temperature of hot air rather than the duration of contact drying. Meanwhile hardness of lotus root chips decreased significantly with increasing the duration of contact drying. These results suggested that a combined drying process with appropriate processing conditions could be applicable successfully for the manufacturing of un-fried lotus root chips.

A. auricular-judae cultivars, ‘Yong-a’ was cultivated in JARES on 2015. Ear mushroom have been consumed the form of dried mushrooms imported from china, but the production and consumption of domestic ear mushroom have been increasing recently. However, how the different drying methods affect the quality of domestic varieties is not clear. Therefore, we examined the effects of drying methods to improve the competitiveness of dried ear mushrooms using domestic cultivar, ‘Yong-a’. Ear mushroom samples were dried using sun-drying and hot air drying(50, 60°C) and combined of two methods(hot air drying at 50, 60°C after 3,6 and 9 hours sun drying) and drying time, rehydration ratio, color and hardness, vitamin D2 contents were evaluated. Drying time was the fastest at 60°C hot air drying(11.5h) and the slowest at 50°C hot air drying(16h) and drying time was shorter as the sun drying time was longer. The rehydration ratio was the highest at 60°C hot air drying(18.6%) and increased as the drying time decreased. After drying and rehydration, the color showed no significant difference between drying methods. The hardness of rehydrated mushroom was highest at sun drying and 60°C hot air drying. The contents of ergosterol were not significantly different by drying methods. However, vitamin D2 was lowest at 50 °C and 60°C hot air drying (4.22mg%, 3.87mg%) and highest at sun drying and 50°C hot air drying after 6 hours sun drying (12.52mg%, 12.99mg%). vitamin D2 contents was higher at 50°C hot air drying than 60°C. According to the results of color, hardness, vitamin D2 contents of dried ear mushroom, sun drying is the best method. When the sun drying is not possible, hot air drying at 60°C is suitable, but it is better to use sun drying method to increase the vitamin D2 contents.

This experiment was carried out to enhance the availability of blackberry. Since it is difficult to use blackberry as a fresh fruit, we investigated the quality characteristics of blackberry powder obtained by various drying methods (freeze drying and hot-air drying at 40~80℃). The L- and b-values of freeze-dried powder was higher than hot-air dried powder. The pH (3.2) was lowest and the acidity (14.4%) was highest in freeze-dried powder. In freeze drying, the brix degree was 65.7 °Bx, but it increased from 54.7 °Bx to 68.5 °Bx with increasing temperature during hot air drying. The total polyphenol and flavonoids contents were the highest in freeze-dried powder, at 9.3 and 6.2 mg/g, respectively. The levels increased as temperature increased in hot air drying. Anthocyanin content in freeze-dried powder was 8.51 mg/g, while it sharply decreased to 1.17~2.45 mg/g in hot-air drying. Vitamin C content in freeze drying (979.4 μg/g) was higher than that in hot-air drying (48.3~303.2 μg/g). The sample concentration required for 50% reduction of DPPH free radical scavenging (RC50) was 79.7 μg/mL in freeze drying, and showed high antioxidant activity. Also it decreased from 122.4 μg/mL to 87.7 μg/mL with temperature increase during hot air drying. We therefore conclude from the above results that freeze drying is more suitable for the production of blackberry powder, because this method showed high value of chromaticity, total polyphenol, flavonoid, anthocyanin content, vitamin C and antioxidant activity.

The purpose of this study was to verify the drying characteristics of steamed sweet potato and to establish optimal drying conditions for far-infrared drying of steamed sweet potato. 4 kg of steamed sweet potato was sliced to thicknesses of 8 and 10 mm, and dried by a far-infrared dryer until a final moisture content of 25±0.5%. The far-infrared dryer conditions were an air velocity of 0.6, 0.8 m/s and drying temperature of 60, 70, and 80oC. The results can be summarized as follows. The drying time tended to be reduced as temperature and air velocity for drying increased. The Lewis and Modified Wang and Singh models were found to be suitable for drying of steamed sweet potato by a far-infrared dryer. The color difference was 35.09 on the following conditions: Thickness of 8 mm, temperature of 80oC, and air velocity of 0.8 m/s. The highest sugar content (59.11 oBrix) was observed on the conditions of a thickness of 8 mm, temperature of 80, and air velocity of 0.8 m/s. Energy consumption decreased on the conditions of higher temperature, slower air velocity, and thinner steamed sweet potato.

In this study, we investigated the effects of pre-soaking in salt and sugar solution prior to air drying at 50℃ on the characteristics of dried apples. Pre-soaking solutions included single solutions of salt 2% and sugar 2%; and combined solutions of salt 2%+sugar 2% and salt 2%+sugar 5%, respectively. The effects of pre-soaking condition and drying were evaluated in terms of moisture content (MC), water activity, color, antioxidant activity determined by DPPH radical scavenging activity, shear force, microbial contents, and sensory evaluation of apple slices. The control sample without pre-soaking showed the most rapid drying rate; in addition, the single solutions showed higher MC and water activity after drying time of 120 min, as compared to combined solutions. In all samples, MC and water activity showed high correlation coefficients of 0.91 to 0.97; whereas, shear force was negatively correlated with MC and water activity. The single solution of salt 2% showed decrease in change of color, including L, a, and b values, and the number of aerobic bacteria during drying. In addition, highest antioxidant activity and values of sensory preferences were observed in the dried apple pre-soaked in single solution of salt 2%.

The effects of drying temperature on the drying characteristics of soybeans at the different position in the dryer with 28.1% (±0.8) of initial moisture content were studied. Drying temperatures varied at 35, 45 and 55ºC, with a constant inlet air velocity (3 m/s). The local air velocities at a position 1, 5, and 9 were 0.150 m/s (±0.012), 0.247 m/ s (±0.018) and 0.795 m/s (±0.036), respectively. The drying rate increased as the local air velocity increased from 0.150 m/s to 0.795 m/s. The cracked grain ratio increased as the drying rate increased. To prevent quality degradation of soybeans during hot-air drying, the local air velocity should be considered. Thin-layer drying models were applied to describe the drying process of soybeans. The Midilli-Kucuk model showed the best fit (R2>0.99). Based on the model parameters, the drying time to achieve the target moisture content (15%) was successfully estimated. The drying time was strongly dependent on the position in the dryer and the drying temperature.