행위자 기반 시뮬레이션을 이용한 확률형 아이템 시장에서 확률 조작의 영향 분석

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 협동과정 기술경영·경제·정책전공, 2020. 8. 욘 알트만.게임 시장의 주 수입원 중 하나인 확률형 아이템의 당첨 확률 조작이 게임 서비스 제공자의 수익에 미치는 영향과 이에 따른 정책적 제언을 놓고 사회적, 학술적인 논쟁이 있다. 이를 두고 여러 연구가 있었으나, 이들 연구는 장기적 관점에서 매출을 예상해 수명 주기가 짧은 게임 시장에 적절치 않고, 사회연결망 하에서의 정보 확산을 고려하지 않았다는 한계가 있다. 이를 극복하기 위해 본 연구는 행위자 기반 모형의 모의 실험으로 확률형 아이템 판매자의 확률 조작을 통한 이익을 추산하고, 소비자의 확률 추산 등의 변수가 이에 미치는 영향을 분석하고자 한다. 이를 위해 사회연결망으로 연결된 다수의 소비자와 독점 판매자로 구성된 행위자 모형을 세우고, NetLogo 상에서 모의실험을 진행할 것이다. 이를 통해 확률 조작이 단기적으로 안겨주는 매출을 계산할 수 있고, 집단으로 확률형 아이템 시행 자료를 수집했을 때 소비자가 더 빠르게 확률 조작을 인지할 수 있다는 사실을 확인할 수 있을 것이다. 이러한 결과는 확률 조작을 통한 게임 서비스 제공자의 부당이익을 추산하고, 확률형 아이템 관련 정책을 수립하는데 도움을 줄 수 있을 것이다.Loot boxes, which are in-game products, comprise various random in-game items. They have become the main source of revenue for the video games industry. There are debates on the effects of probability manipulation by providers and the policy implications thereof. Previous research attempted to analyze this issue; however there were some limitations: a long-term perspective does not fit the video game market as it has a short product life cycle, and information diffusion on social networks was ignored. In this study, additional revenues of producers are estimated by fixing the odds of loot boxes and analyzing the effects of the information generation process using agent-based simulations. The agent-based model consists of a monopolist loot box provider and a plurality of consumers, who are connected through a social network. The results suggest a method for estimating the short-term profit gained by a loot box producer from probability distortions and show that the collective inspection of consumers detects the manipulation faster. These results will help regulators design better loot box regulation policies.1. Introduction 7 1.1 Overview of loot box 7 1.1.1 Definition of loot box 7 1.1.2 Terminology of loot box 8 1.1.3 History of loot box 10 1.1.4 Taxonomy of loot boxes 11 1.1.5 Regulation 12 1.1.6 Controversies around loot box 14 1.2 Problem description 18 1.3 Research objectives and research questions 19 1.4 Methodology 19 1.5 Outline of paper 20 2. State-of-the-art 20 2.1 Loot box 20 2.1.1 Studies on loot box 20 2.1.2 Studies from an economic perspective 21 2.1.3 Studies from the legal perspective 24 2.1.4 Studies from an administrative perspective 25 2.1.5 Studies from a managerial perspective, case study, and survey 26 2.2 Agent-based model simulation of diffusion. 26 3. Model 27 3.1 Game users 28 3.2 Provider 30 3.3 Structure of network 32 3.4 Diffusion process 32 3.5 Reliability of distortion information 33 3.6 Production of information 36 4. Experimental setup 36 4.1 Simulation environment 36 4.2 Parameters and settings in the simulation 37 4.3 Scenario description 40 4.4 UI 41 4.5 Validation of simulation setup 43 5. Results and analysis 44 5.1 Simulation of exogenous disclosure scenario 44 5.2 Personal information analysis scenario simulation 48 5.3 Collective information analysis scenario simulation 50 5.4 Comparison among scenarios 53 6. Conclusion 55 6.1 Policy implications 56 6.2 Limitations and future studies 57 Bibliography 59 초록 69Maste

Effect of Vitamin D Supplementation on Bone Mineral Density in Rheumatoid Arthritis Patients With Osteoporosis

Objectives: To assess the effect of vitamin D supplementation on bone mineral density (BMD) in rheumatoid arthritis (RA) patients with osteoporosis and determine whether supplementation of more than 800 IU/day, which is the currently recommended dose, is beneficial. Methods: RA patients with osteoporosis who received bisphosphonate were included. Patients were classified into four groups according to the dose of vitamin D supplementation (0, 400, 800, and ≥1,000 IU/day). Multivariable linear regression models were performed to evaluate the effect of each dose of vitamin D supplementation on 1-year% change of BMD. Results: In total, 187 RA patients with osteoporosis were included. In the multivariate model adjusted for potential confounders, patients receiving vitamin D supplementation had a significantly higher increase in 1-year % change in lumbar spine BMD (400 IU/day: β = 2.51 [95% CI: 0.04–4.99], 800 IU/day: β = 2.90 [95% CI: 0.47–5.33], and ≥1,000 IU/day: β = 6.01 [95% CI: 3.71–8.32]) and femoral neck BMD (400 IU/day: β = 3.88 [95% CI: 1.83–5.94], 800 IU/day: β =4.30 [95% CI: 2.25–6.35], and ≥1,000 IU/day: β = 6.79 [95% CI: 4.87–8.71]) than those not receiving the supplementation. Notably, the ≥1,000-IU/day group had a significantly higher increase in 1-year % change in lumbar spine BMD (β = 3.11 [95% CI: 0.86–5.37]) and femoral neck BMD (β = 2.50 [95% CI: 0.63–4.36]) than the 800-IU/day group. Conclusion: In RA patients with osteoporosis receiving bisphosphonates, vitamin D supplementation was associated with a higher increase in BMD. This effect was higher in the vitamin D supplementation dose of ≥1,000 IU/day than in 800 IU/day.ope

Correlation between serologic parameters and disease activity of IgG4-related disease: Differences between patients with normal and elevated serum IgG4 concentrations

Objective: We aimed to identify serologic parameters that correlate with the disease activity of IgG4-related disease (IgG4-RD) in patients with normal and elevated serum IgG4 concentrations, respectively. Methods: This retrospective cohort study included 148 patients with IgG4-RD. Patients were categorized into normal (≤201 mg/dL) and elevated (>201 mg/dL) serum IgG4 concentration groups. Disease activity was assessed using the IgG4-RD responder index (RI). The correlations between IgG4-RD RI and serologic parameters (erythrocyte sedimentation rate [ESR], C-reactive protein, C3, C4, IgG4 concentration, IgG concentration, and IgG4/IgG ratio) were evaluated in each group, using Spearman's correlation coefficient. Results: Of the 148 patients with IgG4-RD, 38 (25.7%) and 110 (74.3%) patients were categorized into the normal and elevated serum IgG4 concentration groups, respectively. In the normal serum IgG4 concentration group, IgG concentration was the only serologic parameter that showed a significant correlation with IgG4-RD RI (rho=0.411, p=0.013). However, in the elevated serum IgG4 concentration group, ESR (rho=0.196, p=0.041), C3 (rho=-0.432, p<0.001), C4 (rho=-0.363, p=0.001), IgG4 concentration (rho=0.423, p<0.001), IgG concentration (rho=0.224, p=0.020), and IgG4/IgG ratio (rho=0.328, p=0.001) correlated with IgG4-RD RI. The combination of C3 and IgG4 concentration (rho=0.509, p<0.001) had the strongest correlation with IgG4-RD RI in this group. Conclusion: Among the serologic parameters tested, IgG concentration was the only parameter that correlated with IgG4-RD RI in patients with normal serum IgG4 concentrations, whereas multiple parameters correlated with IgG4-RD RI in those with elevated serum IgG4 concentrations. The combination of C3 and IgG4 concentration had the strongest correlation coefficient in the latter group.ope

Vascular Uptake on 18 F-FDG PET/CT During the Clinically Inactive State of Takayasu Arteritis Is Associated with a Higher Risk of Relapse

Purpose: To evaluate whether vascular uptake on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) during the clinically inactive state of Takayasu arteritis (TAK) is associated with disease relapse. Materials and methods: Patients with TAK who underwent 18F-FDG PET/CT during the clinically inactive state of the disease between 2006 and 2019 were included. Clinically inactive disease was defined as a status not fulfilling the National Institutes of Health (NIH) criteria for active disease in TAK. Relapse was defined as recurrence of clinically active disease after a clinically inactive period, requiring change in the treatment regimen. Vascular uptake on 18F-FDG PET/CT was assessed using target/background ratio (TBR), calculated as arterial maximum standardized uptake value (SUV)/mean SUV in venous blood pool. Multivariable Cox regression analysis was performed to identify factors associated with relapse. Results: A total of 33 patients with clinically inactive TAK were included. During a median observation period of 4.5 (0.9-8.1) years, relapse occurred in 9 (27.3%) patients at median 1.3 (0.7-6.9) years. Notably, TBR [1.5 (1.3-1.8) vs. 1.3 (1.1-1.4), p=0.044] was significantly higher in patients who relapsed than in those who did not. On multivariable Cox regression analysis, the presence of NIH criterion 2 [adjusted hazard ratio (HR): 7.044 (1.424-34.855), p=0.017] and TBR [adjusted HR: 11.533 (1.053-126.282), p=0.045] were significantly associated with an increased risk of relapse. Conclusion: Vascular uptake on 18F-FDG PET/CT and the presence of NIH criterion 2 are associated with future relapse in patients with clinically inactive TAK.ope

Interleukin-32 as a biomarker in rheumatic diseases: A narrative review

Interleukin-32 (IL-32) is an important cytokine involved in the innate and adaptive immune responses. The role of IL-32 has been studied in the context of various diseases. A growing body of research has investigated the role of IL-32 in rheumatic diseases including inflammatory arthritides (rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis) and connective tissue diseases (systemic lupus erythematosus, systemic sclerosis, granulomatosis and polyangiitis, and giant cell arteritis). IL-32 has been shown to play different roles according to the type of rheumatic diseases. Hence, the putative role of IL-32 as a biomarker is also different in each rheumatic disease: IL-32 could serve as a biomarker for disease activity in some diseases, whereas in other diseases it could be a biomarker for certain disease manifestations. In this narrative review, we summarize the associations between IL-32 and various rheumatic diseases and discuss the putative role of IL-32 as a biomarker in each disease.ope

Risk of systemic lupus erythematosus flares according to autoantibody positivity at the time of diagnosis

To estimate the risk of systemic lupus erythematosus (SLE) flares based on the autoantibody positivity at the time of SLE diagnosis. This retrospective cohort study included 228 patients with newly diagnosed SLE. Clinical characteristics including autoantibody positivity at the time of diagnosis of SLE were reviewed. Flares were defined as a new British Isles Lupus Assessment Group (BILAG) A score or BILAG B score for at least one organ system. Multivariable Cox regression analyses were performed to estimate the risk of flares according to autoantibody positivity. Anti-dsDNA, anti-Sm, anti-U1RNP, anti-Ro, and anti-La antibodies (Abs) were positive in 50.0%, 30.7%, 42.5%, 54.8%, and 22.4% of the patients, respectively. The incidence rate of flares was 28.2/100 person-years. Multivariable Cox regression analysis, adjusted for potential confounders, revealed that anti-dsDNA Ab positivity (adjusted hazard ratio [HR]: 1.46, p = 0.037) and anti-Sm Ab positivity (adjusted HR: 1.81, p = 0.004) at the time of diagnosis of SLE were associated with higher risk of flares. To better delineate the flare risk, patients were categorized as double-negative, single-positive, double-positive for anti-dsDNA and anti-Sm Abs. Compared with double-negativity, double-positivity (adjusted HR: 3.34, p < 0.001) was associated with higher risk of flares, while anti-dsDNA Ab single-positivity (adjusted HR: 1.11, p = 0.620) or anti-Sm Ab single-positivity (adjusted HR: 1.32, p = 0.270) was not associated with higher risk of flares. Patients who are double-positive for anti-dsDNA and anti-Sm Abs at the time of the diagnosis of SLE are at higher risk of flares and may benefit from stringent monitoring and early preventive treatment. © 2023, The Author(s).ope

Effect of tumor necrosis factor inhibitors on risk of cardiovascular disease in patients with axial spondyloarthritis

Background: Axial spondyloarthritis (axSpA) is associated with an increased risk of cardiovascular disease. We aimed to evaluate the effect of tumor necrosis factor inhibitors (TNFis) on the risk of cardiovascular disease in patients with axSpA. Methods: This retrospective study included 450 patients with axSpA without pre-existing cardiovascular disease. The outcome was incident cardiovascular disease (myocardial infarction or stroke) after the diagnosis of axSpA. The effect of TNFis on cardiovascular risk was analyzed in the total study population and in an inverse probability of treatment weighting (IPTW)-adjusted population. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) for cardiovascular disease, according to exposure to TNFis. Results: Of the 450 patients, 233 (51.8%) and 217 (48.2%) patients were and were not exposed to TNFis, respectively. Twenty cardiovascular diseases occurred during 2868 person-years of follow-up (incidence rate: 6.97/1000 person-years). In the total study population, exposure to TNFis was associated with a reduced cardiovascular risk when adjusted for traditional cardiovascular risk factors (HR 0.30, 95% CI 0.10-0.85, p = 0.024). However, when time-averaged erythrocyte sedimentation rate and C-reactive protein were additionally adjusted, this association was attenuated and lost statistical significance (HR 0.37, 95% CI 0.12-1.12, p = 0.077). Furthermore, in the IPTW-adjusted population, exposure to TNFis showed no significant reduction in cardiovascular risk (HR 0.60, 95% CI 0.23-1.54, p = 0.287). Conclusions: Although controlling inflammation through TNFis could be beneficial in cardiovascular risk reduction, our data indicate no TNFi-specific reduction in cardiovascular risk in patients with axSpA.ope

Discovery of urine biomarkers for lupus nephritis via quantitative and comparative proteome analysis

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Selection of X-ray versus magnetic resonance imaging as a first-line imaging modality for diagnosing axial spondyloarthritis

Introduction: To determine the cut-off values for age and symptom duration that could be used in selecting preferential first-line imaging modality of sacroiliac joints [X-ray versus magnetic resonance imaging (MRI)] for diagnosing axial spondyloarthritis (axSpA). Methods: This retrospective cohort study included 388 patients newly diagnosed with axSpA. Patients were classified into radiographic axSpA (n = 322) and non-radiographic axSpA (n = 66) groups according to the fulfilment of modified New York criteria by X-ray. Patient characteristics of the two groups were compared. Receiver operating characteristic (ROC) curve analysis was conducted to determine the cut-off values for age and symptom duration that best distinguish non-radiographic axSpA from radiographic axSpA. Results: Compared with patients with radiographic axSpA, those with non-radiographic axSpA were younger at diagnosis (35.7 ± 11.3 years versus 26.8 ± 7.8 years, p 33.5 years at diagnosis [area under the curve (AUC): 0.734] and symptom duration > 4.1 years (AUC: 0.787) were the cut-off values that best discriminate radiographic axSpA from non-radiographic axSpA. Conclusion: The best cut-off values for age and symptom duration for predicting radiographic sacroiliitis are 33.5 and 4.1 years, respectively. It is reasonable to use X-ray as a first-line imaging modality in patients older than 33.5 years with a symptom duration longer than 4.1 years, and use MRI as a first-line imaging in patients younger than 33.5 years with a symptom duration less than 4.1 years.ope

Disease-specific factors associated with cardiovascular events in patients with Takayasu arteritis

Background: To identify disease-specific factors associated with cardiovascular events in patients with Takayasu arteritis (TAK). Methods: Patients with TAK who fulfilled the American College of Rheumatology 1990 criteria for the classification of TAK and were followed up between 2006 and 2019 were included. Traditional cardiovascular risk factors and TAK disease-specific factors at the index date and incident cardiovascular events during the follow-up were retrospectively assessed. To estimate the risk of cardiovascular events according to TAK disease-specific factors, Cox regression analysis with adjustment for traditional cardiovascular risk factors was performed. Results: Of the total 207 patients with TAK, cardiovascular events occurred in 41 (19.8%) patients. Compared with patients who did not develop cardiovascular events, patients who developed cardiovascular events were older (38.5 ± 13.4 years vs. 43.6 ± 11.8 years, p = 0.028), more commonly had diabetes mellitus (6.6% vs. 19.5%, p = 0.029), had lower high-density lipoprotein cholesterol (57.3 ± 17.1 mg/dl vs. 51.2 ± 15.7 mg/dl, p = 0.040), more commonly had type V vascular involvement (33.1% vs. 63.4%, p 0.001), and less commonly received methotrexate (65.1% vs. 43.9%, p = 0.013). In Cox regression analysis, type V vascular involvement was significantly associated with increased risk of cardiovascular events (adjusted HR 2.852, 95% CI 1.474-5.518, p = 0.002), whereas the use of methotrexate was associated with reduced risk of cardiovascular events (adjusted HR 0.515, 95% CI 0.268-0.993, p = 0.047). Conclusion: Type V vascular involvement was associated with increased risk of cardiovascular events, while the use of methotrexate was associated with reduced risk of cardiovascular events, in patients with TAK.ope