EPI International Journal of Engineering

The Impact of Viral Stealth Marketing on Consumers' Buying Interest on Cosmetic Products

Andi Dian Sry Rezki natsir — 2024-08-20

The concept of viral stealth marketing has been actively used by marketers to make products well received in society. Stealth marketing is one of the digital marketing strategies that advertises a product or service to someone, without them realizing that they are becoming a marketing object. Stealth Marketing is more commonly found on social media platforms today such as Facebook or Instagram compared to traditional advertising media such as newspaper, TV and radio broadcasts. Influencer as a service provider is becoming more general in this method of marketing. Cosmetic products are products that are often marketed with the viral stealth marketing method. Recommendations of cosmetic products from people we know will be easier to accept. Data collection was carried out by conducting a survey on the age group of Gen Z. Data processing using paired t-test and F-test. The results of the paired t-test found that there was a difference in the buying interest of consumers who received product promotion treatment (B1) with the group of consumers who received agent recognition treatment (B2) with a significance value of 0.000. Meanwhile, the results of the F-test show that the presence of agent recognition treatment affects consumers' buying interest in indicators of seeking information, trying products, knowing more, and the desire to own products. This result indicates a change in the buying interest of consumers to cosmetic products when they are aware of the use of viral stealth marketing promotion methods.

Slope Stability Analysis of Pit X on Nickel Mining Based on Comparison between Design and Actual Mining Condition

Purwanto Purwanto — 2025-01-09

The nickel laterite mining on the slopes of pit X uses the open-cast mining method with material strength conditions similar to soil. Slope stability considerations under temporary conditions such as earthquakes and increased groundwater levels due to rain need to be reviewed as a precaution against landslides. Limonite and saprolite materials have varying cohesion and phi values that affect the safety factor value. The probability function describes the distribution of a random variable to estimate the probability value of a parameter. The limit equilibrium method can indicate the probability of failure. The pit X slope is designed with a bench height of 10 meters, a bench width of 7 meters, and a single slope inclination of 45˚, but after mining, the slope geometry and material distribution conditions change. Stability analysis of the pit X by comparing design and actual conditions after mining is conducted to determine the safety factor comparison under various soil conditions in both design and actual states. The analysis is performed using the Unified Soil Classification System (USCS) classification method and the Morgenstern-Price (MP) limit equilibrium method. All sections meet the slope stability criteria based on the minimum safety factor standards of 1.30 for static conditions, 1.10 for dynamic conditions, 1.0 for saturated soil conditions, and a probability of failure of <5%. However, based on the results of physical property tests, slope stability needs to be reviewed periodically due to the potential for landslides. Sections A-A' and D-D' have steeper overall slopes in the actual condition, resulting in lower safety factors than in the design condition. Sections B-B' and C-C' have gentler overall slopes in the actual condition, resulting in higher safety factors than in the design condition.

Vibration Analysis of Simply Supported Rectangular Plates Constrained by Rotational Edge Springs

Yoshihiro Narita — 2025-01-15

Comprehensive and accurate numerical results are presented for natural frequencies of thin isotropic, simply supported rectangular plates additionally constrained by rotational elastic springs on the edges. For complete coverage of combination, the number of all the combinations in boundary conditions of simply supported, rotationally constrained and clamped is calculated by Polya counting theory, and all sets of frequency parameters are tabulated for the lowest five modes. The Ritz method, along with displacements assumed in special polynomial form with boundary index, is used to include the strain energy stored in the rotational springs. Convergence and comparison studies are made to demonstrate accuracy of tabulated results, and the frequency parameters are listed for the fifteen sets of boundary conditions and various spring stiffness of the square plates. Some results are also presented for rectangular plates.

Bearing Capacity and Deformation of Timber Pile-Raft Foundation on Soft Soil Deposits

Muhammad Yunus — 2025-02-19

A pile-raft foundation is a type of foundation that combines two different types of foundations, a raft base and a pile foundation. These raft bases are one of the most practical economic solutions for buildings because both the support capacity of the raft and the support capability of the pile both work. The paper presents results of the test bearing capacity of piled-raft foundations made from timber in the laboratory and analyzes numerically the deformations that occur in piled raft foundations made of timber. The results of the loading test on the Bakau piled raft foundations in the laboratory obtained the maximum load that can be held by the foundation before experiencing a failure of 85.00 kN with a deformation value of 21.50 mm. Whereas from the load vs. deformation curve, the ultimate bearing capacity is obtained by the Bakau piled raft foundations at 59.00 kN with an ultimate settlement of 6.00 mm. From the results of the validation between the loading test results of the foundation model in the laboratory and the results of numerical analysis, which compared the results of laboratory tests and the results of plaque analysis, the soil with reinforcement of Timber piled raft foundations gave results that were not much different.

Performance and Capabilities of Small Qualification Contractors on the Sustainable Construction Regulations Implementation

Mochamad Choir — 2025-02-19

The construction sector is important in Indonesia's economic and social development. With the increasing awareness of the importance of sustainability, implementing sustainable construction principles has become necessary. On the other hand, construction service businesses with small qualifications face various challenges in meeting strict regulations and adapting to sustainable practices. This study aims to analyse the performance and capabilities of sustainable construction services businesses in small qualification contractors in East Java on implementing sustainable construction services business regulations. The research method used is mixed methods, as well as qualitative and quantitative methods. As many as 100 respondents are members of the Gapeksindo East Java association with small qualifications. The results showed that construction service businesses with good management (high managerial ability) tend to be more able to comply with sustainable construction regulations. In addition, the descriptive analysis results show recommendations and strategies to improve the implementation of construction services regulations among small businesses, such as training and education, financial support, Simplification of Regulations, technology and innovation, Increased Market Awareness, and technical assistance. With these strategies, it is expected that small construction service businesses in East Java can be more effective in implementing sustainable construction regulations to improve their performance and contribution to sustainable development.

Analysis of the Performance of a Solar Water Heating System Utilizing a Flat-Plate Absorber with Integrated Thermal Storage

Muhammad Anis IR — 2025-02-19

Solar water heaters (SWHs) are widely used all over the world since they use solar energy to power themselves. Solar water heaters that use aluminum-alumina (AL₂O₃) thermal storage at the collector base are the focus of this experimental evaluation. To maximize the efficiency of the heat transfer process and the water heating system, it is essential to incorporate thermal storage within the collector. An investigation of the efficiency of a solar water heater with AL₂O₃ thermal storage has been conducted. Tests are conducted on two different types of absorber plates: the standard flat-plate (SFP) collector and the SFP with AL2O3 as thermal storage. The tests are carried out over the course of a period of 180 minutes and under conditions of constant solar intensity. When the SFP and SFP-TS models are compared, the results indicate that the SFP-TS type has a greater outlet temperature than the traditional SFP. The SFP-TS model delivers a thermal efficiency boost of around 6% when compared to the SFP model with the same specifications. Adding AL₂O₃ to the absorber plate as a thermal storage material improves the thermal efficiency of the plate collector, increases the duration that heat is stored in the collector, and improves the absorption of radiant heat energy.

Keywords: Solar Water Heater (SWH), Aluminum-alumina (AL₂O₃), Standard Flat Plate (SFP), Standard Flat Plate with Thermal Storage (SFP-TS)