Fitting acyclic phase-type distributions by orthogonal distance

Pulungan, Reza,Hermanns, Holger Techno-Press 2022 Advances in computational design Vol.7 No.1

Phase-type distributions are the distributions of the time to absorption in finite and absorbing Markov chains. They generalize, while at the same time, retain the tractability of the exponential distributions and their family. They are widely used as stochastic models from queuing theory, reliability, dependability, and forecasting, to computer networks, security, and computational design. The ability to fit phase-type distributions to intractable or empirical distributions is, therefore, highly desirable for many practical purposes. Many methods and tools currently exist for this fitting problem. In this paper, we present the results of our investigation on using orthogonal-distance fitting as a method for fitting phase-type distributions, together with a comparison to the currently existing fitting methods and tools.

Vitamin D insufficiency and its contributing factors in primary school-aged children in Indonesia, a sun-rich country

Pulungan Aman,Soesanti Frida,Tridjaja Bambang,Batubara Jose 대한소아내분비학회 2021 Annals of Pediatirc Endocrinology & Metabolism Vol.26 No.2

Purpose: The prevalence of rickets is increasing worldwide in association with an increase in vitamin D deficiency. This study aimed to investigate the vitamin D profile of healthy school-aged children in a sun-rich country and its contributing factors. Methods: This cross-sectional study was conducted in 120 healthy children from 7–12 years of age who live in Jakarta, Indonesia. Their demographic status, sun exposure duration time, and lifestyle were recorded using a structured questionnaire. Serum calcium, phosphate, bone-alkaline phosphatase (B-ALP), and 25-hydroxy vitamin D (25(OH)2D3) levels were measured. The participants were categorized into vitamin D sufficient and non-vitamin D sufficient groups, and we analyzed variables that contributed to the 25(OH)2D3 level. Results: Of the participants, 73 (60.8%) were vitamin D sufficient, 45 (37.5%) were vitamin D insufficient, and 2 (1.7%) were vitamin D deficient. Sex, age, body mass index, Fitzpatrick skin type, daily milk intake, and clothing type were not different between the vitamin D sufficient and non-vitamin D sufficient groups. There were no differences in serum calcium, phosphate, and B-ALP between the 2 groups. Sun exposure time was significantly longer in the vitamin D sufficient group compared with that in the non-vitamin D sufficient group (511.4 min/wk vs. 318.7 min/wk, P=0.004), and this effect remained consistent on multivariate analysis after adjustment for covariates (adjusted odds ratio, 1.002; 95% confidence interval, 1.000–1.003). More participants in the vitamin D sufficient group did not use sunscreen (59 vs. 27, P=0.02), but this finding was inconsistent with our multivariate analysis. Conclusion: Despite year-round sun exposure, approximately 1 in 3 primary school-aged children had insufficient vitamin D level. Sun exposure duration was a major contributing factor.

Type 2 diabetes mellitus in children and adolescent: an Indonesian perspective

Aman Bhakti Pulungan,Ireska Tsaniya Afifa,Diadra Annisa 대한소아내분비학회 2018 Annals of Pediatirc Endocrinology & Metabolism Vol.23 No.3

The prevalence of type 2 diabetes mellitus (T2DM) in children and adolescents has increased globally over the past 2 decades. Metabolic syndrome, including obesity and overweight at a young age, increases the occurrence of T2DM. Studies in Indonesia have found that obese children and adolescents are more likely to have insulin resistance, a risk factor for T2DM. There are no data on the current incidence of T2DM in youth in Indonesia, but there has been a significant rise in the prevalence of overweight in adolescents. The diagnosis of T2DM in youth is similar to that in adults, with special consideration of when to test asymptomatic children. Management of T2DM in Indonesia follows the recommendations of the Indonesian Pediatric Society, which include lifestyle modifications, such as improving dietary habits and exercise, as well as appropriate medications. Metformin is the drug of choice for young T2DM patients; if marked hyperglycemia is present, basal insulin is given with metformin. Monitoring of T2DM is generally done through selfmonitoring of blood glucose and glycosylated hemoglobin.

The Effect of Innovation on Price to Book Value: The Role of Managerial Ownership in Indonesian Companies

BASUKI, Basuki,PULUNGAN, Nur Aisyah F.,UDIN, Udin Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.5

This study examines and analyzes the effect of innovation on the price to book value mediated by managerial ownership in Indonesian companies. In order to achieve the goals and objectives, the company increases its value by increasing shareholders. Improving the welfare of shareholders can be done through investment and financial policies, and is reflected in share prices in the capital market. The higher the share price, the better the owner's welfare, and the company's value will also increase. The population of this study is the manufacturing companies - as many as 162 - listed on the Indonesia Stock Exchange in 2012-2017. By using a purposive sampling method, 25 companies met the criteria for the sample. The data comes from the companies' annual report taken from the Indonesia Stock Exchange website. The data is further analyzed using partial least square (PLS). The results of the study showed that innovation has a significant effect on price to book value. The companies with high marketing innovation produce high company performance as well. The companies get a commensurate reward from marketing innovation activities to carry out continuous marketing innovations. In addition, managerial ownership does not mediate the relationship between innovation and price to book value.

Method for Automated Selection of the Trabecular Area in Digital Periapical Radiographic Images Using Morphological Operations

Enny Itje Sela,Reza Pulungan,Rini Widyaningrum,Rurie Ratna Shantiningsih 대한의료정보학회 2019 Healthcare Informatics Research Vol.25 No.3

Objectives: The aim of this study is to propose a method that automatically select the trabecular bone area in digital periapical radiographic images using a sequence of morphological operations. Methods: The study involved 50 digital periapical radiographic images of women aged from 36 to 58 years old. The proposed method consists of three stages: teeth detection, trabecular identification, and validation. A series of morphological operations—top-hat and bottom-hat filtering, automatic thresholding, closing, labeling, global thresholding, and image subtraction—are performed to automatically obtain the trabecular bone area in images. For validation, the results of the proposed method were compared with those of two dentists pixel by pixel. Three parameters were used in the validation: trabecular area, percentage of agreed area, and percentage of disagreed area. Results: The proposed method obtains the trabecular bone area in a polygon. The obtained trabecular bone area is usually larger than that of previous studies, but is usually smaller than the dentists’. On average over all images, the trabecular area produced by the proposed method is 5.83% smaller than that identified by dentists. Furthermore, the average percentage of agreed area and the average percentage of disagreed area of the proposed method against the dentists’ results were 75.22% and 8.75%, respectively. Conclusions: The shape of the trabecular bone area produced by the proposed method is similar and closer to that identified by dentists. The method, which consists of only simple morphological operations on digital periapical radiographic images, can be considered for selecting the trabecular bone area automatically.

The Relationships between Abnormal Return, Trading Volume Activity and Trading Frequency Activity during the COVID-19 in Indonesia

SAPUTRA G, Enrico Fernanda,PULUNGAN, Nur Aisyah Febrianti,SUBIYANTO, Bambang Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2

This study aims to determine whether there are differences in the average abnormal return, trading volume activity, and trading frequency activity in pharmaceutical stocks before and after the announcement of the first case of the coronavirus (COVID-19) in Indonesia. The sample was selected using a purposive sampling method and collected as many as nine pharmaceutical companies listed on the Indonesia Stock Exchange during 2019-2020. The data used in this study were secondary data in the form of daily data on stock closing prices, Composite Stock Price Index (IHSG), stock volume trading, number of shares outstanding, and stock trading frequency. This study was an event study with an observation period of 14 days, namely seven days before and seven days after the announcement of the coronavirus's first positive case in Indonesia. Hypothesis testing employed the paired sample t-test method. Based on the results, it was found that there was no difference in the average abnormal return of pharmaceutical stocks before and after the announcement of the first case of COVID-19. However, there was a difference in the average trading volume activity and the average trading frequency activity in pharmaceutical stocks before and after the announcement of the first case of COVID-19.

GOVERNMENT, STATE-OWNED ENTERPRISE, and LIBERALIZATION of UNIVERSAL POSTAL OBLIGATION SERVICES

Andriati Fitriningrum,Andrey Hasiholan Pulungan,Putu Darusidhi 서울대학교행정대학원 2023 Journal of Policy Studies Vol.38 No.3

This study aimed to examine the extent to which the relationship between the government and state-owned enterprise (SOE) hinders the achievement of the liberalization of universal postal obligation (UPO) services. This study motivated the failure of postal industry reforms and the performance improvement of PT Pos Indonesia (the Indonesian postal SOE). A case study method is selected to expand the existing path dependency theory. The development of postal services was reconstructed using path dependence, which also revealed the nature of relationships between the government and SOEs, and the barriers to the success of liberalization and performance improvement. Through this method, the theoretical approach is expanded. This study demonstrates how the historical need to perform socio-political functions has produced high dependence, reciprocal dependence, and mutual advantages between the government and SOE, which have hindered the company’s ability to be lucrative and effective. The cause of SOE’s poor performance and inefficiency occurs when the company is required to execute UPO services. This study added to the body of knowledge and improved government policy. These study implications are anticipated to offer border knowledge and comprehension of the vital responsibilities that USOs and subsidies play in the community.

Automated Detection of Retinal Nerve Fiber Layer by Texture-Based Analysis for Glaucoma Evaluation

Anindita Septiarini,Agus Harjoko,Reza Pulungan,Retno Ekantini 대한의료정보학회 2018 Healthcare Informatics Research Vol.24 No.4

Objectives: The retinal nerve fiber layer (RNFL) is a site of glaucomatous optic neuropathy whose early changes need to be detected because glaucoma is one of the most common causes of blindness. This paper proposes an automated RNFL detection method based on the texture feature by forming a co-occurrence matrix and a backpropagation neural network as the classifier. Methods: We propose two texture features, namely, correlation and autocorrelation based on a co-occurrence matrix. Those features are selected by using a correlation feature selection method. Then the backpropagation neural network is applied as the classifier to implement RNFL detection in a retinal fundus image. Results: We used 40 retinal fundus images as testing data and 160 sub-images (80 showing a normal RNFL and 80 showing RNFL loss) as training data to evaluate the performance of our proposed method. Overall, this work achieved an accuracy of 94.52%. Conclusions: Our results demonstrated that the proposed method achieved a high accuracy, which indicates good performance.

Effect of Tree Age and Active Alkali on Kraft Pulping of White Jabon

Nyoman J Wistara,Anne Carolina,Widya S Pulungan,Nadrah Emil,Seung Hwan Lee,Nam Hun Kim 한국목재공학회 2015 목재공학 Vol.43 No.5

White Jabon (Anthocephalus cadamba Miq.) is one of the fast growing species in Indonesia and has the potential as the raw material for pulp and paper. In this research, 3, 5, and 7 years old White Jabon woods were pulped under different active alkali charge of 15%, 18%, 21%, 24%, and 27%, and its effect on delignification degree, kappa number, pulp yield, pulp viscosity, brightness, unbeaten freeness, and delignification selectivity was investigated. The results showed that tree age and active alkali concentration influenced the quality of pulp and pulping properties, except for that of unbeaten freeness. Delignification degree increased with increasing active alkali charge, and this brought about the decrease of pulp kappa number. The pulping yield tended to decrease below the Klason lignin of approximately 4%. Even though the 3 years old wood resulted in the highest brightness and highest delignification selectivity, the highest pulp viscosity was obtained with the 5 years old wood. The dominant fiber length of all wood ages was in the range of 1.2 - 2.0 mm. The 3 years old wood was considered to be the most promising raw material for kraft pulping in the view point of pulping properties, pulp quality and harvesting rotation.