최근 몇 년 전부터 우리나라의 양봉농가에는 전에 경험하지 못했던 이상기후 악재와 초비극 상황인 꿀벌 군집 붕괴현상(Colony collapse disorder, CCD)으로 인하여 최대 60% 이상의 꿀벌이 폐사하거나 사라지는 등 양봉산업 의 막대한 손실을 초래하였다. 본 연구는 복잡하고 다양한 원인으로 약해진 꿀벌의 면역력과 봉군 세력을 향상시 키기 위하여 농업부산물 홍삼박을 활용한 화분떡을 자가제조하여 꿀벌 사양 먹이를 통한 봉군 세력에 어떠한 영향을 미치는지를 구명하고자 수행하였다. 가공부산물 홍삼박을 건조하여 130 mesh 이상 초미립자로 분쇄하 였으며, 조사포닌 725 mg 100-1을 함유하였고 화분떡 총중량의 0.5, 1.0, 2.5, 5.0, 10.0%로 첨가하여 완전하게 혼합 배합하여 화분떡을 제조하였다. 분봉벌은 4월 분봉한 봉군으로 이용하였으며, 2달 동안 1주일 간격으로 대조구 화분떡과 제조한 홍삼박 화분떡 5처리구에 급이하여 봉군의 세력을 조사하였다. 사양 먹이로 급이한 화분떡은 30일간 달관조사에서 대조구와 처리구 모두 꿀벌 먹이로 거부반응은 없었다. 봉군 세력 조사로 4월 분봉벌의 봉군은 1매 2갈로 시작하여 약 한 달 후에 6매 봉판으로 증소되었으며, 이때 조사된 봉군별 봉개율은 대조구 55%(100 기준) 대비 홍삼박 0.5~1.0% 처리구는 58~60%로 +(5~9)% 향상되었던 반면, 홍삼박 2.5% 이상 첨가한 처리구에서는 봉개율이 -(9~20)% 감소하는 경향을 보였다. 그리고 화분떡 먹이 소모량을 조사한 결과, 대조구 평균 96.9%(100) 소모율 대비 홍삼박 0.5% 처리구는 97.7%로 다소 높았으나 홍삼박 2.5% 이상 처리구에서는 점점 감소하는 경향을 보였다.

Golden apple snails(GAS) are native to warm regions such as Central and South America and Southeast Asia, and were first introduced as a high-protein food. GAS are omnivorous and have a habit of eating plants submerged in water, so they have been used for eco-friendly weed control in rice fields since 1992. When the GAS was first introduced, it was thought that it would be impossible to overwinter in Korea. However after 2000, overwintering individuals were founded and damage to rice occurred and the development of means to control GAS has been required. In this study, we tested the effectiveness of an eco-friendly pest control agent using Styrax japonicus that grow naturally in Korea. As a result of exposing GAS to S. japonicus fruit powder, a 100% molluscicidal effect was confirmed at 66.7ppm. To investigate the duration of effect, treatment was performed at the same concentration and molluscicidal effect of more than 90% was up to 3 days after treatment. The killing effect of each part of the S. japonicus was compared, and the seed extracts showed no killing effect at all concentrations, while the sarcocarp extracts showed a 100% killing effect up to 33.3ppm, and the fruit extracts showed a 100% killing effect up to 200ppm.

This study investigates the melting point and brazing properties of the aluminum (Al)-copper (Cu)-silicon (Si)-tin (Sn) alloy fabricated for low-temperature brazing based on the alloy design. Specifically, the Al-20Cu-10Si-Sn alloy is examined and confirmed to possess a melting point of approximately 520oC. Analysis of the melting point of the alloy based on composition reveals that the melting temperature tends to decrease with increasing Cu and Si content, along with a corresponding decrease as the Sn content rises. This study verifies that the Al-20Cu-10Si-5Sn alloy exhibits high liquidity and favorable mechanical properties for brazing through the joint gap filling test and Vickers hardness measurements. Additionally, a powder fabricated using the Al-20Cu-10Si-5Sn alloy demonstrates a melting point of around 515oC following melting point analysis. Consequently, it is deemed highly suitable for use as a low-temperature Al brazing material.

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals) ceramics have excellent mechanical properties including high fracture toughness, good abrasion resistance as well as chemical and biological stability. As a result, they are widely used in mechanical and medical components such as bearings, grinding balls, and hip implants. In addition, they provide excellent light transmittance, biocompatibility, and can match tooth color when used as a dental implant. Recently, given the materials’ resemblance to human teeth, these ceramics have emerged as an alternative to titanium implants. Since the introduction of CAD/CAM in the manufacture of ceramic implants, they’ve been increasingly used for prosthetic restoration where aesthetics and strength are required. In this study, to improve the surface roughness of zirconia implants, we modified the 3YTZP surface with a biocomposite of hydroxyapatite and forsterite using room temperature spray coating methods, and investigated the mixed effect of the two powders on the evolution of surface microstructure, i.e., coating thickness and roughness, and biological interaction during the in vitro test in SBF solution. We compared improvement in bioactivity by observing dissolution and re-precipitation on the specimen surface. From the results of in vitro testing in SBF solution, we confirmed improvement in the bioactivity of the 3Y-TZP substrate after surface modification with a biocomposite of hydroxyapatite and forsterite. Surface dissolution of the coating layer and the precipitation of new hydroxyapatite particles was observed on the modified surface, indicating the improvement in bioactivity of the zirconia substrate.

Thermite welding is an exceptional process that does not require additional energy supplies, resulting in welded joints that exhibit mechanical properties and conductivity equivalent to those of the parent materials. The global adoption of thermite welding is growing across various industries. However, in Korea, limited research is being conducted on the core technology of thermite welding. Currently, domestic production of thermite powder in Korea involves recycling copper oxide (CuO). Unfortunately, controlling the particle size of waste CuO poses challenges, leading to the unwanted formation of pores and cracks during thermite welding. In this study, we investigate the influence of powder particle size on thermite welding in the production of Cu-thermite powder using waste CuO. We conduct the ball milling process for 0.5–24 h using recycled CuO. The evolution of the powder shape and size is analyzed using particle size analysis and scanning electron microscopy (SEM). Furthermore, we examine the thermal reaction characteristics through differential scanning calorimetry. Additionally, the microstructures of the welded samples are observed using optical microscopy and SEM to evaluate the impact of powder particle size on weldability. Lastly, hardness measurements are performed to assess the strengths of the welded materials.

Lithium (Li) is a key resource driving the rapid growth of the electric vehicle industry globally, with demand and prices continually on the rise. To address the limited reserves of major lithium sources such as rock and brine, research is underway on seawater Li extraction using electrodialysis and Li-ion selective membranes. Lithium lanthanum titanate (LLTO), an oxide solid electrolyte for all-solid-state batteries, is a promising Li-ion selective membrane. An important factor in enhancing its performance is employing the powder synthesis process. In this study, the LLTO powder is prepared using two synthesis methods: sol-gel reaction (SGR) and solid-state reaction (SSR). Additionally, the powder size and uniformity are compared, which are indices related to membrane performance. X-ray diffraction and scanning electron microscopy are employed for determining characterization, with crystallite size analysis through the full width at half maximum parameter for the powders prepared using the two synthetic methods. The findings reveal that the powder SGR-synthesized powder exhibits smaller and more uniform characteristics (0.68 times smaller crystal size) than its SSR counterpart. This discovery lays the groundwork for optimizing the powder manufacturing process of LLTO membranes, making them more suitable for various applications, including manufacturing high-performance membranes or mass production of membranes.

Physicochemical properties and storage stability of plant-based alternative meat prepared with low-fat soybean powder (LPAM) treated by supercritical-CO2 and those of full-fat soybean powder (FPAM) were compared. Ash and crude protein contents were higher in LPAM than in FRAM. Water absorption capacity and oil absorption capacity were significantly higher in LPAM than in FPAM. Water binding capacity was higher in LPAM than in FPAM during a 20 days storage period at 5℃ and pH was significantly lower in LPAM than in FPAM after a 5~10 days storage period. Hardness, gumminess and chewiness significantly increased with the increase in the storage period, and the three were significantly higher in LPAM than in FPAM after 10 days and 20 days of storage. The acid value showed no remarkable difference according to the storage period in LPAM; however, it was significantly higher in FPAM than in LPAM after 20 days of storage. The peroxide value and TBA value were significantly increased according to the storage period, and were significantly lower iin LPAM than in FPAM during all the storage periods. Therefore, the use of low-fat soybean powder may be effective in improving oxidative stability during storage in the production of plant-based alternative meat.

In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

In this study, machine learning models are proposed to predict the Vickers hardness of AlSi10Mg alloys fabricated by laser powder bed fusion (LPBF). A total of 113 utilizable datasets were collected from the literature. The hyperparameters of the machine-learning models were adjusted to select an accurate predictive model. The random forest regression (RFR) model showed the best performance compared to support vector regression, artificial neural networks, and k-nearest neighbors. The variable importance and prediction mechanisms of the RFR were discussed by Shapley additive explanation (SHAP). Aging time had the greatest influence on the Vickers hardness, followed by solution time, solution temperature, layer thickness, scan speed, power, aging temperature, average particle size, and hatching distance. Detailed prediction mechanisms for RFR are analyzed using SHAP dependence plots.

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.

The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06–0.12 mm), laser power (225–325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress–strain data from the compression test and analysis are compared.

Although the Ti–6Al–4V alloy has been used in the aircraft industry owing to its excellent mechanical properties and low density, the low formability of the alloy hinders broadening its applications. Recently, laser-powder bed fusion (L-PBF) has become a novel process for overcoming the limitations of the alloy (i.e., low formability), owing to the high degree of design freedom for the geometry of products having outstanding performance used in hightech applications. In this study, to investigate the effect of bulk shape on the microstructure and mechanical properties of L-PBFed Ti-6Al-4V alloys, two types of samples are fabricated using L-PBF: thick and thin samples. The thick sample exhibits lower strength and higher ductility than the thin sample owing to the larger grain size and lower residual dislocation density of the thick sample because of the heat input during the L-PBF process.

In this study, we analyzed the effect of storage conditions on the survival of fungi in red pepper powder. Red pepper powder was inoculated with a total of six fungal species, namely Aspergillus terreus, Aspergillus flavus, Rhizopus microsporus, Aspergillus fumigatus, Aspergillus niger, and Aspergillus ochraceus at a final cell count of 4–6 log CFU/g. After inoculating the sterilized red pepper powder with fungi, we dried the powder on a clean bench and packaged it in zipper bags. Following drying, the water activity was 0.502±0.001. Subsequently, the red pepper powder inoculated with fungi was stored at -20oC, 5oC, 15oC, and 25oC. All six species of fungi perished the quickest at 25oC and survived for the longest (168 days) at -20oC. In summary, this study showed that fungi survive for an extended period in red pepper powder at -20oC and 5oC compared to 15oC and 25oC. Therefore, to prevent fungal contamination, red pepper powder should have a water activity below 0.6 and be stored in a zipper bag at room temperature.

This study aimed to investigate the effect of a coating agent on pork storage. Pork was coated with a coating agent containing sodium carboxymethyl cellulose (CMC) and mandarin peel powder (M). The treatments were divided into control, a 0.1% CMC treatment, and a 0.1% CMC +5% M treatment, and pH, color, 2-thiobarbituric acid reactive substances (TBARS), volatile basic nitrogen (VBN), and the number of viable cell counts were measured. In the case of redness (a), it was found that the reduction over the storage period was less in the 0.1% CMC + 5% M treatment than in the control and the 1% CMC treatment. When stored at 4oC and 25oC, TBARS of pork tended to increase during the storage period, followed by control, 0.1% CMC treatment, and 0.1% CMC + 5% M treatment, indicating that lipid oxidation was most suppressed in pork coated with mandarin peel powder. As a result of measuring the VBN of pork stored at 4oC and 25oC, the 0.1% CMC + 5% M treatment showed lower values than the control and 0.1% CMC treatment. When the film-coated pork was stored at 4oC, the number of viable cell counts in the 0.1% CMC +5% M treatment area was 7.13±0.96 log CFU/g on the 12th day of storage, delaying the growth of viable cell counts for approximately 3 d more than other treatments. Therefore, coating pork with a film containing CMC and mandarin peel powder has been confirmed to delay the increase in the number of viable cell counts while reducing the quality change during pork storage, which is an effective alternative to improving the storage of fresh food as an edible film.