Kebijakan Pengendalian Persediaan Bahan Baku Kertas Menggunakan Model P Berdasarkan Peramalan Kebutuhan Produksi, Studi Kasus: Penerbit X

Raw materials are important for a company, but the stockpile of raw materials that accumulates too many and too long adds to the inventory costs. Therefore, an appropriate inventory policy is needed to meet uncertain needs. This study discusses the uncertain need for paper raw materials at the Publisher X using the Additive Decomposition Forecasting method to determine the paper needs in the future. The Additive Decomposition Forecasting Method is used since the demand for paper raw materials is seasonal and tends to increase. Furthermore, after knowing the need of paper raw materials, inventory control planning is carried out by using P Model with the back order case because of the constant order period. The results of this study indicate that by implementing an inventory control policy with P Model with the case of back order, the Publisher X is able to save as 0.9067% of total inventory cost compared to the total cost using the company’s policy that have been used before

Kajian Matematis Mengenai Strategi Pengembangbiakan Sapi Potong Lokal Guna Meningkatkan Kualitas Daging Sapi

Beef is one of the most demanded food products in Indonesia compared to other meat commodities. The high demand of this commodity causes a shortage of its supply so that the government has to import it from other countries. As the consequences, people in Indonesia prefer to consume imported beef rather than local beef, especially those in the food industry, since imported beef has better quality. Thus, government may establish a program that is able to increase the local beef quality thereby increasing its competitiveness, for instant by cross-breeding of local and imported cattle. This paper is to discuss a cross-breeding simulation to predict the distribution of offspring produced in the next few generations through mathematical approach. Simulations are conducted by following the X-Linked Inheritance concept and algebra. Simulations are carried out by three different scenarios which consider gender of the imported cattle. The simulations show that all scenarios are able to produce local cattle offspring with imported quality. However, the offspring from the cross-breeding still preserve cattle with original local genetic with a different ratio between the first and the second scenario

The dynamics of prisoner population model in Indonesia with a rehabilitation regulation for drug users to overcome prison overcapacity issue

This paper discusses about a mathematical model of the prisoner population with a new regulation regarding punishments to the drug users in an effort to overcome the prison overcapacity issue in Indonesia. This new regulation is launched by the Indonesia government after a fact about overcapacity of prison in Indonesia is revealed through a fire incident in a prison on 8 September 2021 that causes 41 people died and a number of people were injured. Besides, prisons in Indonesia are mostly occupied by the drug user. The model is constructed by using a compartmental model approach. The stability analysis of the equilibrium points is carried out along with its existence conditions. The analytical studies are equipped by calculate the basic reproduction number. Furthermore, this study is also equipped by numerical simulations with some scenarios. The results of this study confirm that the effect of the new regulation is able to reduce overcrowded issue in prisons in Indonesia. However, if it compare to recent prison capacity, this new regulation has not been able to suppress the number of prisoner below to its capacity limit in the short time so that it is needed to consider other solutions as the additional regulation and polic

On The Study of Covid-19 Transmission Using Deterministic and Stochastic Models with Vaccination Treatment and Quarantine

In this study, we propose deterministic and stochastic models of the spread of Covid-19 with vaccination and quarantine programs. The model considers the facts that vaccines do not provide full protection, the efficacy of current vaccines only lasts for a limited time, and recovered people could be reinfected. The routine analysis was carried out for the deterministic model, including calculating an expression for the basic reproduction number. The stochastic formulation makes use of a Continuous-Time Markov Chain (CTMC) model. The basic reproduction number from the deterministic model relates to the stochastic model's analysis in producing a formula for the probability of extinction of Covid-19. Furthermore, numerical simulations are carried out to analyze the sensitivity of the dynamical states and the basic reproduction number to the model parameters. An expression for the probability of disease extinction in terms of the model parameters and initial conditions is given. The results of this study suggest that current conditions in Indonesia will lead to a longterm Covid-19 epidemic. One of the efforts to overcome the Covid-19 epidemic is by increasing the provision of vaccines to the susceptible population. However, the number of vaccinated people in the population is not always an ideal control for dealing with the spread of the disease. The vaccine efficacy is also important to reduce the infection. As long as the efficacy is not sufficient to give a good protection to the human population and it lasts only for a short period of time, quarantine is still needed

HUBUNGAN ASUPAN CAIRAN, STATUS GIZI DENGAN STATUS HIDRASI PADA PEKERJA DI BENGKEL DIVISI GENERAL ENGINEERING PT PAL INDONESIA

Water is an essential nutrient needed by the body. Dehydration is a condition when body loses more water than it takes. The content of water in human body depend on the proportion of muscle tissue and fat tissue. This cross sectional study was to analyze relation between fl uid intake, and nutrition status with hydration status of worker in division of general engineering at PT PAL INDONESIA. Subjects were all workers in all division general engineering at PT PAL INDONESIA. Data were collected by questionnaire which consist of 2 × 24 hours food recall, anthropometry measurement and urine collection. Spearman correlation test was applied to analyze the data. The result showed that most of the workers were ≤ 40 years old (58,8%) and all workers are male. Most of the workers had total fl uid intake less than 3700 L per day (85,3%) with average 2797,3 ± 673,30 L per day, nutritional status were obese (67,6%) and medium dehydrated (41.2%). The result of statistic test showed a strong positive relationship between fluid intake and hydration status. Meanwhile there was a weak negative relationship between nutritional status and hydration status. It can be concluded that fl uid intake more contribute to hydration status than nutrition status in general engineering division workers

Pyramid population prediction using age structure model

Population composition in a country by sex and age-structure often illustrated through the Population Pyramid. In this study, an age-structure model will be constructed to predict the population pyramid shape in the coming year. It is assumed that changes in population are affected by natality and mortality number in each age group, ignoring migration rates. The proposed age structure model formulated as a first-order partial differential equation with the non-negative initial condition. The boundary condition is given by the number of births which is proportional to the number of women at childbearing age. Then, this age structure model implemented utilizing United Nations Data to predict population pyramids of Indonesia, Brazil, Japan, the USA, and Russia. The population pyramid prediction of the five countries shows different characteristics, according to whether it is a developing or developed country. The results of this study indicate that the age structure model can be used to predict the composition of the population in a country in the next few years. Indonesia is predicted to be the highest populated country in 2066, compared to the other four countries. This result can be used as a reference for the government to plan policies and strategies according to age groups to control population explosion in the future

Analisis Manajemen Pengelolaan Pohon Gmelina arborea Roxb. pada Hutan Rakyat di Tasikmalaya dan Banjar, Jawa Barat

Forests are natural resources which if it is managed properly can provide the economic benefits to the surrounding. Woods from trees in the forest are one of the economic benefits that can be gained from the forest. However, trees must be logged under a precise calculation and controlled continuously so that they are not extinct. Logging time in a forest is generally determined by the needs of farmers, which may not necessarily provide maximum benefits. Therefore, harvesting management is needed to obtain optimal benefits while still maintaining the forest sustainability. This paper discusses a basic model of the tree harvesting using Linear Algebra which is applied to one of economically valuable trees, i.e., Gmelina arborea Roxb. on the community forest in Tasikmalaya and Banjar, West Java. Initially, the tree population is divided into 16 class intervals based on their diameter. Analysis of the harvesting model implies that the optimal results will be obtained by logging all of trees in one class with the highest selling value. By applying this scenario, all of the Gmelina arborea Roxb. on the community forest in Tasikmalaya and Banjar, West Java must be logged at the 9th class which will provide a maximum profit of IDR 12,491,843.889 for every 1,000 trees harvested

The maternal referral mobile application system for minimizing the risk of childbirth

Background: The maternal mortality rate in Surabaya is still quite high due to ineffectice referral health systems. Primary Health Care (PHC) has difficulty referring patients to hospitals which have available resources. The purpose of this study is to develop a mobile app system framework for the maternal referral system. Design and Methods: This study was developed based on the results of the Focus Group Discussion (FGD) with midwives, doctors and primary health care heads about the referral system regulation in Surabaya City. Results: A mobile app system can be used to communicate patients’ conditions to the hospital. The hospital then will refer back to the PHC as a home care service after the birth. This mobile app has gone through a trial and a development process; it is currently in the process of structuring the mobile app based on the bugs that occur in the system. Conclusions: This mobile app still needs development, especially in minimizing system bugs, and providing faster, more accurate communication

Analisis Angka Reproduksi Dasar Model Matematika Penyebaran HIV Melalui Jarum Suntik pada Populasi Pengguna Narkoba

Penyebaran HIV memiliki kompleksitasnya sendiri, diantarannya masa inkubasi yang lama. Penelitian-penelitian sebelumnya laju penginfeksian diasumsikan konstan, sedangkan laju penginfeksian akan berbeda sesuai dengan strutur populasinya, seperti pada populasi homoseksual, heteroseksual, pengguna narkoba atau populasi dengan kombinasi aktivitas beresiko. Makalah ini membahas tentang model penyebaran HIV melalui jarum suntik pada pengguna narkoba. Fokus utama pada studi ini adalah menentukan laju penginfeksian (force of infection) penyebaran HIV melalui jarum suntik yang tidak konstan pada populasi pengguna narkoba sehingga diperoleh model yang lebih realistis. Dilanjutkan dengan menentukan angka reproduksi dasar sebagai ambang batas terjadinya suatu wabah penyakit. Angka reproduksi dasar tersebut kemudian disimulasikan untuk mendapatkan parameter yang dapat dikontrol agar dapat menekan angka reproduksi dasar tetap berada dibawah ambang batas. Penelitian dilakukan melalui model SIR yang dimodifikasi menjadi model SIA dan analisis matematika sebagai salah satu langkah untuk memahami sebuah fenomena alam. Laju penginfeksian dan angka reproduksi dasar yang diperoleh membawa pada kesimpulan bahwa agar angka reproduksi dasar tetap berada pada ambang batasnya maka populasi pengguna narkoba dibagi pada grup-grup yang cukup banyak. Kata kunci: model matematika HIV, laju penginfeksian, angka reproduksi dasa