Universitas Diponegoro
  • Semarang, Jawa Tengah, Indonesia
Recent publications
Introduction: To develop an in-house acrylic-based step-wedge phantom with several thickness configurations for calibrating computed tomography (CT) localizer radiographs in order to measure the water-equivalent diameter (D w ) and the size-specific dose estimate (SSDE). Method: We developed an in-house step-wedge phantom using 3 mm thick acrylic, filled with water. The phantom had five steps with thicknesses of 6, 12, 18, 24, and 30 cm. The phantom was scanned using a 64-slice Siemens Definition AS CT scanner with tube currents of 50, 100, 150, 200, and 250 mA. The relationship between pixel value (PV) and water-equivalent thickness (t w ) was obtained for the different step thicknesses. This was used to calibrate the CT localizer radiographs in order to measure D w and SSDE. The results of D w and SSDE from the radiographs were compared with those calculated from axial CT images. Results: The relationship between PV and t w from CT localizer radiographs of the phantom step-wedge produced a linear relationship with R ² > 0.990. The linear relationships of the D w and SSDE values obtained from CT localizer radiographs and axial CT images had R ² values > 0.94 with a statistical test of p -value > 0.05. The D w difference between those from CT localizer radiographs and axial CT images was 3.7% and the SSDE difference between both was 4.3%. Conclusion: We have successfully developed a step-wedge phantom to calibrate the relationship between PV and t w . Our phantom can be easily used to calibrate CT localizer radiographs in order to measure D w and SSDE.
As a crucial ingredient for human and animal survival, clean water also contributes significantly to a nation's ever-expanding economy. However, the availability of clean water has deteriorated as contaminants, such as dyes, have a significant detrimental effect on the pure and clean main waters. Coffee residue with micro-and macropores is a potential biosorbent for the removal of synthetic dyes from aqueous solutions. This study aims to determine the efficacy of adsorption of synthetic colors by coffee dregs. Using the Central Composite Design (CCD), the impacts of four adsorption factors (contact time, pH, starting concentration, and adsorbent dosage) were investigated (CCD). For the percent elimination of Remazol brilliant blue R (RBBR) and Remazol brilliant violet 5R, quadratic models were created (RBV-5R). The ideal adsorption conditions consisted of a pH of 3, a dosage of 5 g of adsorbent, an initial concentration of 10 mg/L, and a contact period of 30 min for RBBR and 60 min for RBV-5R, resulting in a removal of 49.98% and 93.8%, respectively. The experimental and projected values for RBBR were 96.57% and 95.2% for RBV-5R, respectively, demonstrating high agreement with minimal errors. The Langmuir isotherm model fit the equilibrium adsorption data of the two selected dyes the best. In addition, the pseudo-second-order kinetic model was able to better characterize the experimental data with good respective regression coefficients.
Piracy may be defined as an offense that consists of acts of pillage and violence upon the high seas which, on land, would amount to a felony. Whereas a pirate has generally been described as a rover and robber upon the sea there has, however, been much more (scholarly) attention in research and writing the history of piracy in Indonesia. It has been known that the fact of piracy has been conducted since the pre-colonial times on a very large scale. However, there is also the interrelation between the phenomenon of piracy and the tradition, religion, politics, and economy. This article elucidates the activity of piracy in Indonesia since precolonial times and identifies the records of pirates who had performed their activities which amounted to both cooperation and antagonism of the European expansion.
Lower or upper limb prosthetics are a solution for people who have a limited ability to walk due to amputation. One of the most crucial parts of these prosthetics is a prosthetic foot which is usually made of elastomeric materials. The prosthetic foot is a replaceable part that has to be replaced at a particular time due to wear or other damages. Therefore, the mechanical properties of the elastomeric materials in the prosthetic feet are critical to determine the product's lifetime. In this study, the mechanical properties of elastomeric materials in prosthetic feet are investigated. Three types of prosthetic feet products are used, namely import A, import B, and local C. Five tests are carried out, i.e., density, hardness, tensile, tear, and compression set tests. The results show that the density of the local C is two times higher than those of imported products A and B. The hardness of the imported product A is the highest, while the hardness of the local C and import B are similar. The tensile strength and elongation at break of the local C show the highest results. All elastomers have no significant difference in tear resistance. The compression set tests show that the local product C has the smallest result compared to the other imported products, meaning that it has a good ability to prevent permanent deformation.
Smartphone sensors have been widely researched and published in literature by experts to be used in physics learning. This paper presents the use of smartphone sensors and applications as a measuring instrument in the classical sound wave experiment adapted from physics textbooks at school or university. Tone generator, sound meter, and audio autocorrelation were used in the experiment to visualize sound as a propagating vibration, sound waves as mechanical waves, characteristics of sound waves (loud and soft or high-pitched or low-pitched), sound range, and sound power. The experimental results presented are expected to help students understand the concept of sound waves.
Pollution in Pekalongan waters is one of the environmental problems caused by the industrial city. Batik industry, the most common activity at Pekalongan, uses a lot of water and generates a lot of effluent because it involves an aqueous process when dyeing fabric. This wastewater, contains heavy metal contaminants like hexavalent chromium (Cr+6), copper (Cu), and lead (Pb), generally finds its way to rivers that run across Pekalongan. The contamination level, spatial distribution, and transport simulation of copper (Cu) and chromium (Cr) in water were investigated in the Loji and Banger rivers in Pekalongan, Indonesia. A two‐dimensional hydrodynamic model was constructed to simulate heavy metal concentrations in marine environment of Pekalongan City, Indonesia. The model's kinetic processes comprised air exchange, transportation, and deposition. Thus, Cu concentrations were below Indonesia's threshold, but Cr, especially in the river and outlet river, exceeded it. Both rivers have 0.002 mg/L Cu. Since water freely flows at Banger River Estuary, Cr concentration reach the highest in both rivers, 0.1056 mg/L. The evaluation findings and the numerical Cu and Cr calculation model created in this work have important research ramifications for preventing and controlling heavy metal pollution. Heavy metals in the marine environment of Pekalongan2
This research aimed at identifying stakeholders' participation in the appropriate strategy of small-scale fishermen governance in the waters of Karang Jeruk Conservation Area in facing vulnerability along with actor typology and analyzing the strategy of how small-scale fishermen survive with their vulnerability based on stakeholder. This research used a qualitative research paradigm. The data were collected using an in-depth interview method and were analyzed using stakeholder analysis with MACTOR (Matrix of Alliances and Conflicts Tactics, Objectives and Recommendations) to identify the stakeholders' power, relationship and actor alliance pattern and using ATLAS.ti to identify small-scale fisherman governance strategies by stakeholders. The research results show that most actors were the key players and had low divergence. Small-scale fishermen's governance strategy requires facilities, infrastructure, institution preparation, and community empowerment. Such development needs various parties' involvement, including the regulator, executor, supporting institution, target and community as the main actors.
We developed and provided initial validation for a 15-item scale for use with academics. In Phase 1, we utilized a review of the literature, focus groups, and expert feedback to generate 36 items. In Phase 2, we conducted item and exploratory factor analyses to reduce the number of items and assess the factor structure (N = 212; 51.4% female; mean age 48.93 years, SD = 9.45). In Phase 3, we conducted confirmatory factor analyses to verify the initial structure (hold-out sample: N = 210; 56.7% female; mean age 49.20 years, SD = 9.98). In Phase 4, we provided construct validity.
This research is a case study on the ability of children with intellectual disabilities in morphosyntax abilities. It is well-known that the language skills of children with intellectual disabilities do not compare with those of other normal children, where they will have language delays and even language disorders. The subject of this study was KH, a 12-year-old child with mild intellectual disability, before doing speech therapy was only able to say one or two words. After 30 speech therapy sessions, the researcher wanted to know the morphological ability in the use of affixes when speaking and the syntax abilities in the use of phrases and the use of sentence types. The methods used in collecting data were observation and interview. Researchers also used fishing techniques with flashcards and were asked to tell the daily activities of KH. The results of this study show that after 30 times of speech therapy, KH is able to use affixation and is able to use simple sentences and complex sentences when communicating
Theories and practices related to preventing radicalism, extremism that leads to terrorism offer different intangible measures to combat such acts. The National Action Plan to Prevent and Combat Extremism (RAN-PE) as part of achieving national goals; of protecting the homeland of Indonesia’s, and participating in the achievement of world order. The purpose of this study is to determine public views on violent extremism (VE) as well as public perception and public trust toward the RAN-PE policy. In addition, this study also identifies the empirical relationship between the public perception of the VE variable and public trust under the RAN-PE policy. We conducted a survey to examine the influence of perception on the level of trust toward the government in relation to the RAN-PE policy and used Spearman’s rho in the non-parametric analysis to determine the correlation between variables. The findings showed that public perception can predict the level of trust toward the government’s implementation of policies to combat extremism, radicalism, and terrorism.
Large-bodied Panulirus ornatus lobsters are economically important because they are an aquatic biota. It is one of the most important commodities in the city of Tarakan. The aim is to analyze the growth patterns and mortality of P. ornatus from the West Waters of Tarakan City. Method using a quantitative descriptive. The purposive sampling method was used by dragging the gill net fishing gear to the P. ornatus lobster ground area, and the collection was carried out 16 times in 7 months (December 2021-July 2022). The results of P. ornatus showed that the male sex ratio was higher than the female. The growth model was allometrically negative, and the criteria for the condition index were fat and thin. The growth pattern of Model Von Bertalanffy males is slower than females. However, the growth rate to achieve asymptotic growth for males is faster than for females. The total mortality, catch mortality, and exploitation rate of males was higher than females. However, the mortality of the female nature was higher than that of males. P. ornatus should be managed in the waters of West Tarakan using the domestication and restocking technique to increase sustainability.
Radiation of thoracic computed tomography (CT) involves the breast although it is not considered an organ of interest. According to the International Commission on Radiological Protection (ICRP) No. 103, the breast is an organ with a high level of sensitivity when interacting with x-rays, increasing the potential risk of breast cancer. Therefore, the radiation dose must be optimized while maintaining image quality. The dose optimization can be accomplished using a radiation shield. This study aims to determine the effect of silicone rubber(SR)-lead (Pb)in various thicknesses as an alternative protective material limiting dose and preserving the image quality of the breast in thoracic CT. SR-Pb was made from SR and Pb by a simple method. The SR-Pb had thicknesses of 3, 6, 9, and 12 mm. The breast dose was measured using a CT dose profiler on the surface of the breast phantom. The CT number and the noise level of the resulting image were determined quantitatively. The dose without the radiation shield was 5.4 mGy. The doses measured using shielding with thicknesses of 3, 6, 9, and 12 mm were 5.2, 4.5, 4.3, and 3.3 mGy, respectively. Radiation shielding with a thickness of 12 mm reduced breast surface dose by up to 38%. The CT numbers and noise levels for the left and right breast phantom images were almost the same as those without radiation shields indicating there were only slight artifacts in the image. Therefore, SR-Pb is considered a good shielding material which can be applied in a clinical setting by placing it directly on the breast surface for dose optimization.
One of the environmental factors that can influence the onset of fatigue is noise exposure. Besides noise has a negative impact on everything from cognitive processes to mental and physical health. Noise's impact can be measured using brain activity and the waves it generates. The main goal of this article is to review how electroencephalography can be used to determine the impact of noise on cognitive performance. The method is based on bibliometric analysis stages, including literature study from the Scopus database and the snowball search method. The findings revealed that of the 30 articles examined, 28 used the experimental design method with continuous noise, and 10 used the time-frequency domain for feature extraction. According to the results of the study, there seems to be an increase in the use of EEG for performance measurement, such as mental fatigue, mental workload, working memory, attention, stress, and the presence of noise factors that influence cognitive performance.
Governance has been widely discussed by scientists and practitioners. There have been many opinions about the concept of good governance, especially good university governance (GUG) for higher education. Governments should act according to all the criteria of good governance (de Vries, 2013). The purpose of this study is to figure out how the implementation of GUG affects the performance of the university. The study applies combine qualitative and quantitative research methods by using structured questionnaires. GUG has not become a culture, as a result, universities are unable to provide the manpower needed by industry. The university needs to reconsider its mission, not only as a social and educational function but also as an entrepreneurial one, by developing strategies and programs and involving stakeholders. The level of trust of the stakeholders will be determined by how well GUG in the university is implemented. The first step to becoming entrepreneurial universities is to change them from education universities to research ones. This can be interpreted that every university has the same view of the importance of implementing GUG. The implementation of GUG is a sign of gaining the university’s success.
Hip joint prostheses are used to replace hip joint function in the human body. The latest dual-mobility hip joint prosthesis has an additional component of an outer liner that acts as a cover for the liner component. Research on the contact pressure generated on the latest model of a dual-mobility hip joint prosthesis under a gait cycle has never been done before. The model is made of ultrahigh molecular weight polyethylene (UHMWPE) on the inner liner and 316L stainless steel (SS 316L) on the outer liner and acetabular cup. Simulation modeling using the finite element method is considered static loading with an implicit solver for studying the geometric parameter design of dual-mobility hip joint prostheses. In this study, simulation modeling was carried out by applying varying inclination angles of 30°, 40°, 45°, 50°, 60°, and 70° to the acetabular cup component. Three-dimensional loads were placed on femoral head reference points with variations of femoral head diameter used at 22 mm, 28 mm, and 32 mm. The results in the inner surface of the inner liner, the outer surface of the outer liner, and the inner surface of the acetabular cup showed that the variations in inclination angle do not have a major effect on the maximum contact pressure value on the liner component, where the acetabular cup with an inclination angle of 45° can reduce contact pressure more than the other studied inclination angle variations. In addition, it was found that the 22 mm diameter of the femoral head increases the contact pressure. The use of a larger diameter femoral head with an acetabular cup configuration at a 45° inclination can minimize the risk of implant failure due to wear.
Lockdown is one of the policies taken by many countries to prevent the spread of covid 19. In contrast to other countries, Indonesia does not adopt a lockdown policy but prefers Restrictions on Community Activities (PKM). Restrictions on community activities such as referring to lockdown but not in full, the existing policies include four restrictions: cessation of the implementation of activities in schools and educational institutions, restrictions on activities at work, restrictions on religious activities, and restrictions in public places. This paper tries to investigate the effect of restrictions on Community Activities on air quality, especially on the concentration of Carbon Monoxide in one city and partially based on core activity. This study measures the column concentration of total Carbon Monoxide (CO) from the Tropospheric Monitoring Instrument (TROPOMI) on the Sentinel-5 Precursor satellite. In this study, we analyze the average CO concentration of Semarang City before and during COVID-19 from January 1, 2019, to August 30, 2021. The results show that the policy of restrictions on Community Activities can reduce the value of CO concentration to remain stable at < 30 mol/m² in core activities with the dominance of local internal transportation within the city (education, settlements, trading center, and industry), while activities with the dominance of transportation outside the city (transportation nodes) produce different things with an average concentration of > 32 mol/m², but with a downward trend.
The main objective of this research is to study the effect of the chemical composition and grain size of pit sand on the permeability of concrete. The sand was taken from three locations in the Merauke area, which is located in Papua Province, Indonesia. To test the permeability of concrete, an equivalent method was employed that measured the depth of water penetration in the concrete. The results of this study indicate that the grain size and chemical properties of the sand affect concrete permeability. The weight percentage of sand grains larger than 2.36 mm is found to be proportional to the permeability of the concrete. The greater the percentage of gravel, the greater the depth of water penetration. In contrast, concrete permeability is found to be inversely proportional to the percentage of fine sand, which is sand with a grain size of less than 0.5 mm. In addition, two chemical compounds are found to affect the permeability of concrete, namely calcium oxide (CaO) and aluminium oxide (Al2O3).
Permanent magnetic bearing applies the principle of electromagnetic levitation that makes it able to support various forces and loads in HAWT operational conditions without friction. The design of PMB in this study uses permanent magnet Nd2Fe14B material that a Coulombian model radially magnetized. The finite element analysis was used to model the radial magnetic force from radial displacement between rotor-stator magnets. Modeling was also used to obtain magnetic flux density at magnet geometry (BMax), magnetic flux density at air gap magnet (Bairmax), radial magnetic force (Fr), and radial displacement (dX). The PMB models were designed on the magnets thickness (0.9 m; 1.35 m; and 1.8 m) and the radial air gaps (0.02 m; 0.03 m; and 0.04 m). The lower radial air gap of the PMB model produces a greater radial magnetic force (Fr). Furthermore, the thicker the PMB magnet increases the magnetic flux density and radial magnetic force. The PMB model V3 yields a radial magnetic force of 254 kN with the shortest radial displacement (15.3 mm).
External shear reinforcement of reinforced concrete beams, generally using carbon fiber reinforced polymer in the form of a wrap. So that the maximum existing beam reinforcement can only be installed on 3 faces. In this study, shear reinforcement was tried using strings whose installation was similar to stirrups. So that when used to strengthen existing beams, it can be assisted by making holes in the floor plate with a drill. The formulation of the string shear reinforcement is approached with a 4 face wrap shear reinforcement formulation. The research was conducted on 3 beams, 1 beam without shear reinforcement, 2 beams shear reinforced with strings with the same in area per unit length of distribution. The string distribution distance of 2 beams are different. The test results show that the increase in shear strength of the two shear reinforcement beams is the same only differs in ductility. The real increase in shear strength is much smaller than the increase in the shear strength of the approach formulation.
This article contains the discussion of the history and the preservation of The Old City of Semarang. The Old City was founded at the end of 17th century after an agreement was approved by the Mataram Kingdom and the Vereeniging van Oost-Indische Compagnië (VOC) in 1678. Later on, the colony of VOC developed into a little city surrounded by a fortress in which VOC leaders, its officers, VOC soldiers, European traders resided. Here, some town facilities were built such as municipality house (stadshuis), shops, roads, soldier barracks, warehouses, schools, hospital, church, court, prison, and municipality park. Around the third decade of the 19th century, the fortress of VOC colony was demolished since this city was massively developed. Today, this little city built by VOC is called “Semarang Old City” or “De Oude Stad” (in Dutch), and the municipal government of Semarang is eager to protect and develop this cultural heritage site as a tourism cultural asset due to its unique values and typical cultural attractions. The purpose of this study is to support the Semarang City Government’s plan to propose The Old City of Semarang to UNESCO in order to get recognition as a World Heritage.
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11,673 members
Muhamad Thohar
  • Department of Medicine
Dwi Hudiyanti
  • Department of Chemistry
Mateus Sakundarno
  • Department of Epidemiology and Tropical Diseases
Pratama Jujur Wibawa
  • Department of Chemistry
Jl. Prof. Soedarto, S.H., 50275, Semarang, Jawa Tengah, Indonesia
Head of institution
Prof. Dr. Yos Johan Utama, S.H., M.Hum.