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.

Aluminum alloy-based additive manufacturing (AM) has emerged as a popular manufacturing process for the fabrication of complex parts in the automotive and aerospace industries. The addition of an inoculant to aluminum alloy powder has been demonstrated to effectively reduce cracking by promoting the formation of equiaxed grains. However, the optimization of the AM process parameters remains challenging owing to their variability. In this study, the response surface methodology (RSM) was used to predict the crack density of AM-processed Al alloy samples. RSM was performed by setting the process parameters and equiaxed grain ratio, which influence crack propagation, as independent variables and designating crack density as a response variable. The RSM-based quadratic polynomial models for crack-density prediction were found to be highly accurate. The relationship among the process parameters, crack density, and equiaxed grain fraction was also investigated using RSM. The findings of this study highlight the efficacy of RSM as a reliable approach for optimizing the properties of AM-processed parts with limited experimental data. These results can contribute to the development of robust AM processing strategies for the fabrication of highquality Al alloy components for various applications.

The production process of ultra-pure water (UPW) involves dozens of unit processes such as reverse osmosis (RO), pretreatments, membrane degasifier, and several ion exchange processes. Recently, continuous electrodeionization (CEDI) has replaced the 2-bed and 3-tower (2B3T) ion exchange process. As a result, the majority of wastewater in UPW production now comes from the RO concentrate. The important of RO in UPW production is to produce high-quality water with a low ion concentration (around 1 mg/L) for CEDI feed water. Minimizing RO concentrate is essential to reduce the wastewater produced in the UPW production process. This can be achieved by maximizing the recovery of the RO system. However, increasing the recovery is limited by the water quality of the RO permeate. To ensure high-quality permeate water, the RO system is designed with a two-pass configuration. The recovery of each pass in the RO system is limited (e.g., < 85%) due to the expected increase in permeate water concentration at higher RO feed water concentrations. Interestingly, tests using 4-inch RO modules with low concentration feed water (≤ 35 mg/L as NaCl) revealed that the permeate concentration remains almost constant regardless of the feed water concentration. This implies that the recovery of the first RO pass can be increased as long as the average feed/concentrate concentration of the second RO pass is less than 35 mg/L. According to this design criterion for the RO system, the recovery of the first and second RO pass, with a feed water concentration of 250 mg/L as NaCl, can be increased up to 94.8% and 96.0%, respectively. Compared to the conventional RO system design (e.g., 70% and 80% for the first and second RO pass) for UPW production, this maximum recovery design reduces the volume of RO feed and concentrate by up to 38.4% and 89.2%, respectively.

This study investigated the odor emission characteristics of fertilizer manufacturing facilities. The characteristics were evaluated by measuring the odor concentration at the outlet and site boundary of the complex fertilizer and organic fertilizer manufacturing facilities. The evaluation process utilized the air dilution sensory method and PTR-ToF-MS. The complex odor dilution factor ranged from 100 to 120 times at the outlet of the compound fertilizer manufacturing facility. Specifically, the concentrations of Ammonia and Aldehydes were relatively high as designated odor substances. For the organic fertilizer facility, the dilution factor for complex odors was measured up to a maximum of 3,000. And, designated odorants such as Ammonia and Hydrogen sulfide were measured at levels up to parts per million (ppm). The odor contribution assessment of the fertilizer manufacturing facilities showed that the complex fertilizer facility exhibited similar contributions from Aldehydes and Sulfur compounds. On the other hand, the organic fertilizer facility had the highest contribution of over 62% from Sulfur compounds. As odor substances are easily changed and diffused according to weather conditions, it is difficult to obtain representative data according to the measurement time. Therefore, if continuous monitoring of odorous substances is performed using equipment that can be measured in real time without pretreatment, it becomes feasible to identify odor emission sources and regional spatio-temporal distribution. This information would then serve as a basis for analyzing odorant contamination characteristics and establishing appropriate countermeasures.

Recently, the crisis of demographic extinction is rising in Korea more than any other country, and it is difficult for industrial sites to maintain without 'foreign workers'. Industrial accidents and accident deaths of foreign workers account for 7.6% and 12.3% of the total, through an in-depth analysis of fatal accidents in the manufacturing industry, differences and similarities between fatal accidents of foreign workers and all fatal accidents were confirmed in terms of occurrence type, workplace size, length of service, employment type, etc. In this study, customized countermeasures were found.

제조기업의 혁신전략은 기업의 기술경영활동에 있어서 기술의 확보, 연구개발, 제품혁신 등 다양한 방식을 통해 궁극적으로 경쟁우위와 연결되기 때문에 기업의 기술경영을 논하는 데 중요한 역할을 한다. 그동안 국내 제조기업 혁신전략 연구는 기업 규모별·산업별 혁신전략, 혁신 성과, 혁신을 위한 자원 확보 등 다양한 측면에서 연구되어 왔으나, 이들 연구 결과를 종합적⋅체계적으로 분석하는 연구는 거의 이루어지지 않았다. 본 연구는 국내 학계의 제조기업 혁신전략 논의를 종합하고자 2005년부터 2021년까지 한국학술재단 등재 학술지에 게재된 국내 제조기업 혁신전략 연구 51편을 대상으로 체계적 문헌 연구를 실시하였다. 연구 대상 문헌에 대한 분석 결과를 토대로 크게 세 가지 측면(분석대상, 연구초점, 혁신전략 유형) 에서 논의 결과를 종합하고 국내 제조기업 혁신전략 연구의 특징을 도출하였다. 연구 결과, 국내 제조기업 혁신전략 연구는 위 세 가지 측면을 기준으로 보았을 때 일부 분야에 편향된 연구가 이루어져 온 것을 확인할 수 있었으며 이를 바탕으로 국내 제조기업 혁신전략 연구의 미래 연구 방향을 제시하였다.

This study measured the biochemical properties, antioxidants, free sugars, organic acids, trigonelin, chlorogenic acids, and caffeine content of coffee prepared using different extraction methods by adding dried apple powder to develop high-quality functional drinks. Espresso had the highest soluble solids content and brownness at 9.17±0.88oBrix and 1.85±0.57. Its organic acid content was higher in the sample groups than in the control group, whereas the espresso group was highest in citric acid at 2184.11±0.01 mg/mL, malic acid at 2181.35±0.03 mg/mL, fumal acid at 40.42± 0.01 mg/mL, lactic acid at 32.04±0.02 mg/mL, and formic acid at 49890 mg/mL. Additionally, it had the highest sucrose, glucose, fructose, and sorbitol contents (p<0.05). In the trigonelin content, the sample groups showed a higher content than the control group, with the order being espresso > mokapot > water drip > frenchpress > sippon > hand drip (p<0.05). In the content of chlorogenic acid and caffeine, the sample groups showed higher content than the control group, with the order of espresso > mokapot > water drip > siphon > frenchpress > hand drip (p<0.05). As a result, espresso was found to be suitable for developing coffee drinks in manufactured coffee with different extraction methods.

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.

Dongchimi is one of the most representative types of watery kimchi in Korea. Although the scope of application of dongchimi has been expanded, research on the quality of dongchimi is insufficient compared to that of baechu kimchi. This study aimed to find the optimal manufacturing condition of high-acidity dongchimi and investigate the effects of potassium citrate (P) and sugar (S) on quality. Different dongchimi samples (Control, S, P) were prepared and stored at 15oC for 15 days. Among the various sugars, sucrose made the highest acidity of dongchimi. When potassium citrate was added as a pH buffer, the acidity was 2.2 times higher than the control group. In the PS group, where sucrose and potassium citrate were added, the acidity and organic acid content were 3-fold and 3.7-fold higher, respectively, than those in the control group. As a result of the analysis of the free sugar content, the metabolism of lactic acid bacteria was expected to be relatively more activated in the PS group. Therefore, this study could be utilized in the dongchimi manufacturing industry or as primary data for other dongchimi research.