Digital allies : preserving national security through signals intelligence cooperation within the UKUSA agreement

이진솔 Seoul National University 2016 국내석사

The disclosure of the global surveillance practices of five democratic nations shook the world in June 2013. Though some were content with official justification as a matter of national security, many more were concerned with the implications these oversight abilities had on individual privacy and the possibility of a surveillance state. Using information released on the document disclosures from 2013 to 2015, the following thesis researches the impact mass surveillance practices and signals intelligence have had on the concept of national security and analyzes how democracies utilize signals intelligence data to fulfill their national security goals. This thesis focuses on the current national security strategies of the United States and United Kingdom, comparing each nation’s usage of signals intelligence, post-Snowden actions, and subsequent domestic response. Based off of these findings, this thesis analyzes and critiques the current strategy of mass surveillance practices as utilized by democratic states, proposes policies to promote better practices, and discusses the concept of individual privacy in the context of national security.

(The) roles of government in incubating internationally competitive industrial clusters : the case studies of Newly Industrialized Economies (NIEs) and implications for Cambodia

Pichnorak, Siem Seoul National University 2018 국내석사

Abstract The Roles of Government in Incubating Internationally Competitive Clusters: The Cases of Newly Industrialized Economies (NIEs) and Implications for Cambodia Siem Pichnorak Graduate School of International Studies Seoul National University The importance of cluster effects on improving national competitiveness has been widely acknowledged and thus attracted a great deal of attention from researchers and policy makers. Amongst different actors, government has been recognized as one of the most important actor in the development of cluster, at least at the early stage of cluster evolution. In line with this argument, this thesis seeks to examine the important roles government could play in incubating internationally competitive industrial clusters and draw implications for the future development of industrial cluster in Cambodia. This thesis will be organized into three important discussions. The first discussion revolves around the necessary roles of government in incubating internationally competitive industrial clusters. Second, some implications in terms of the roles of government in incubating Daedeok Innopolis in South Korea and Hsinchu Science Park in Taiwan (China) will be discussed. Drawing from the discussion on the roles of government in incubating competitive industrial clusters and the two case studies, the last part will discuss potential lessons from which Cambodian government could learn in terms of cluster development along with some policy suggestions. Keywords: industrial clusters, government, public policy, Newly Industrialized Economies (NIEs), national competitiveness, industrialization

Elemental analysis of caries-affected root dentin and artificially demineralized dentin

성영혜 Seoul National University 2016 국내박사

Elemental analysis of caries-affected root dentin and artificially demineralized dentin Younghye Sung Program in Conservative Dentistry Department of Dental Science Graduate School, Seoul National University (Directed by Professor Ho-Hyun Son, D.D.S., M.S.D., Ph.D.) Objectives This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin. Materials and methods Box-formed cavities were prepared on buccal and lingual root surfaces of extracted sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dying technique and restored with RMGI (Fuji Ⅱ LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and statistically analyzed using ANOVA and Tukey’s post hoc test (α = 0.05). Results Demineralized surface was observed under SEM in all samples. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI. Conclusions Both the microbial and the chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, within the limitation of this study, the artificial lesions had a relatively larger extent of demineralization than the natural lesions. Sr from RMGI was incorporated into the superficial layer of the caries-affected dentin.

Associations between hourly PM2.5 chemical constituents and emergency department visits for cardiovascular and respiratory disease

엄희상 Seoul National University 2016 국내석사

Introduction : Several epidemiological studies have investigated fine particulate matter (≤ 2.5 μm in aerodynamic diameter, PM2.5) has a risk for adverse effects on human health. Previous studies have focused on the risk associated with the total mass of particles, without considering the chemical constituents of them. In this study, the hourly differences between PM2.5 chemical constituents and emergency visits for cardiovascular disease and respiratory disease were estimated using time-stratified case-crossover design. Methods: The study periods were from January 1 to December 31, 2013 in Seoul, Korea. Hourly health outcome data on emergency department visits for cardiovascular disease and respiratory disease were provided by National Emergency Department Information System (NEDIS). Emergency department visits data were classified according to the discharge diagnosis for cardiovascular disease and respiratory disease (ICD-10, cardiovascular, I00-I99 and respiratory, J00-J99). Hourly data for PM2.5 mass and chemical constituents were measured by real-time monitoring at one sampling site located at Bulgwang-dong, Seoul (37.36° N, 126.56° E). In this study, PM2.5 mass and only 13 chemical constituents (OC, EC, Cl-, Mg2+, Na+, NH4+, NO3-, SO42-, Ca, Fe, K, Pb, and Zn), were selected after QA/QC procedure. The meteorological data such as hourly mean temperature (℃), relative humidity (%), and air pressure (hPa) were adjusted as confounding variable. Time-stratified case-crossover analysis and conditional logistic regression analysis were used to estimate the adverse health effects of fine air particles and to estimate and adjusted odds ratio (ORs) and 95% confidence intervals (CIs), respectively. The short-term effects were estimated using moving averages in six periods (1-6(h), 7-12(h), 13-18(h), 19-24(h), 25-48(h), 49-72(h)) and adjustments of this association by age (≥ 65 years) and season. Results and Discussion : The strongest adverse effects for cardiovascular disease exacerbations were associated with PM2.5 mass, OC, EC, Cl-, Ca, Fe and Zn after 19-24h lag period and NH4+, NO3-, and SO42- after 25-48h lag period were estimated. The strongest adverse effects for respiratory disease exacerbations were associted with NO3-, K and Pb after short lag periods (0-6h and 7-12h) and PM2.5, OC, EC, Cl-, NH4+, SO42-, Ca, Fe, and Zn after longer lag periods (19-24h and 25-48h). For those older than ≥ 65 years, the strongest adverse effects for cardiovascular disease exacerbations were shown with PM2.5 mass, OC, EC, Cl-, Ca, Fe, and Zn after 19-24h lag period and NO3- after 25-48 h lag period and respiratory disease exacerbations of OC, EC, Fe and Zn after 19-24h lag period were observed. Especially, among PM2.5 chemical constituents, EC showed the strongest association with cardiovascular disease and respiratory disease exacerbations. For all of seasons, significant positive associations for PM2.5 mass and chemical constituents excluding Mg2+ were observed for cardiovascular and respiratory disease. Conclusion : This study found major differences of associations between PM2.5 constituents and emergency visits for cardiovascular and respiratory disease in Seoul. This study will provide robust evidences for the health impacts of PM2.5 chemical constituents.

Comparative research on copyright protection of reality television programs in China and Korea

치신 Seoul National University 2017 국내석사

ABSTRACT Comparative Research on Copyright Protection of Reality Television Programs in China and Korea Qi Xin College of law, law The Graduate School Seoul National University With the fast development of Television broadcast and Internet technologies, there are various ways provided for people to enjoy interesting TV programs. Nowadays, it shows an increasing demand of people for high-quality TV shows. Both China and Korea governments are encouraging and promoting culture and entertainment industries by setting political strategies and legislation. On one hand, highly developed contents industry can bring a thriving and happy mental life for people and make a country identical and reputable in international societies. On the other hand, compared to manufacture industry, with a comparatively low invest, a highly developed contents industry brings out huge monetary benefits for one country in a very environmental-friendly way. It’s said by a research institute that contents industry is one of the most promising industry in near future days. As a country which has a relatively strong and developed contents industry, Korea manufactures and exports to other countries movies, dramas and TV programs every year. The legislators and policy makers paid attention to and made related laws and policies to support entertainment industry of Korea. The main laws are as below: Copyright Law(저작권법); Contents Industry Promotion Law(콘텐츠산업 진흥법); Culture Industry Promotion Basic Law(문화산업진흥 기본법) and so on. China is really a huge market for TV broadcasting operators with a large number of population and a wide land. But in the aspect of protection of TV programs, the law is vague and uncertain. Copyright Law or Unfair Competition Law is the main tool for TV program producers to seek protection for their works. In recent years, especially from 2013, china TV broadcasting stations begin to buy the license of copyright of Korean TV programs. In 2014, Chinese TV stations imported nearly 70 foreign TV shows, among which Korean TV shows charge 10, nearly 15% of the total amount. <Running man><I’m a singer><Where are you going, dad> and other TV programs made great success and became the hottest TV shows in China. As the show is getting more and more popular, the copyright license royalty is also increasing. As reported, before 2014, the license fee to Korean stations is usually between 10 to 30 thousands US dollars per episode. After a big success, some TV programs even cost as expensive as 10 times. China has the condition to buy copyrights, whereas Korea aims at the huge market of China, both of which contribute to the explosive growth of copyright transaction. In this thesis, I will concentrate on arguing the following things. Firstly, I will analysis the definition and legal character of format. Should it be protected by copyright law? Secondly, I introduce the situation of legal protection of format in China, Korea and U.S. Lastly I will provide some practice strategy for format holders to protect the format besides the Copyright Law.

Observation of energy and baseline dependent reactor neutrino disappearance in the RENO experiment

최원국 Seoul National University 2016 국내박사

The Reactor Experiment for Neutrino Oscillation (RENO) began gathering data in August, 2011. The RENO is designed to measure the neutrino mixing angle Theta13 and mass squared difference |Delta m^2_ee| which is the electron neutrino weighted average mass square difference |Delta m^2_31| and |Delta m^2_32|. The experimental site of RENO is the Hanbit nuclear power plant, which is 280 km away from the capital city of Koera, Seoul. There are 6 reactors in the Hanbit nuclear power plant, equally spaced in a single line. The Experiment used two identical detectors. The near detector (far detector) is located at 294 m (1384 m) from the cen- ter of this six reactor array. and the flux-weighted average distance between the reactors and the far (near) detector is 408.6 m (1444.0 m). The experimental has analyzed about 500 live days of data in the period between August 2011 and January 2013. In this period, the far (near) detector observed 31541 (290775) electron antineu- trino candidate events with a background fraction of 4.9% (2.8%). The measured prompt spectra has an excess of reactor e of approx- imately 5 MeV relative to the prediction from the most commonly used model. The excess is proportional to reactor thermal output power, therefore the excess is the neutrino signal coming from reac- tor cores and not a background. To aviod this problem, the data are analysed based on the measured far-to-near ratio of prompt spectra. A clear energy and baseline dependent disappearance of reactor e is observed in the decit of the observed amount of e. From this decit, we can determine sin^2 2theta_13 = 0.082 +- 0.009(stat.) +- 0.006(syst.) and |Delta m^2_ee| = 2.62+0.21-0.23(stat.) +0.12 - 0.13(syst.) (X10^-3eV^2) based on a rate and spectra analysis. The precise measurement of Theta_13 would be a important milestone in determination of the leptonic CP phase if combined with a result of an accelerator neutrino beam experiment.

Effects of tannic acid on Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels in peripheral sensory neurons

김성아 Seoul National University 2019 국내석사

말초 감각신경세포에서 탄닌산이 과분극과 고리형 뉴클레오티드에 의해 활성화되는 이온통로에 미치는 영향 탄닌산 (tannic acid)은 떫은맛을 가지며 수용성인 식물성 폴리페놀 화합물의 일종이다. 탄닌산의 생의학적 효과는 비신경세포에서 연구된 바는 있으나, 말초 감각신경세포에 대한 탄닌산의 영향에 대해서는 알려진 바가 거의 없다. 과분극과 고리형 뉴클레오티드에 의해 활성화되는 이온통로 (HCN 이온통로)는 심장 리듬을 결정하고 신경세포의 전기적 흥분성 조절에 관여한다고 알려져 있으며, 최근 연구에서 HCN 이온통로가 신경병증성 통증에도 중요한 역할을 한다는 것이 밝혀졌다. 본 연구는, 탄닌산이 마우스 척수 후근 신경절 신경세포의 HCN 이온통로 전류(Ih)에 미치는 영향을 확인하여 탄닌산의 신경병증성 통증을 조절할 수 있는 가능성을 확인하고자 하였다. 마우스(Adult C57BL/6)의 척수 후근 신경절 신경세포를 단일 세포로 분리한 후, 전-세포 패치 클램프 레코딩(whole-cell patch clamp recording) 기법을 이용하여, 탄닌산 (Tannic acid, T0200, Sigma-Aldrich, m.w. 1701.20)이 HCN 이온통로에 미치는 전기생리학적영향을 관찰하였다. 5 μM 탄닌산은 Ih 전류 크기를 58.9 ± 4.2 %로 감소시켰으며, 전압 sag를 현저히 줄어들게 하였다. 탄닌산 (0.05 ~ 50 μM)은 –120 ~ -50 mV 사이의 모든 전압 범위에서 Ih 전류를 농도 의존적으로 억제시켰다. 억제 중간값 (IC50)은 0.9 μM이었으며, 최대 억제 효과는 78 %까지 보였다. 이러한 TA의 억제 효과는 cAMP 비의존적이었다. 여기서 흥미롭게도, 탄닌산은 작은 크기의 세포에서 Ih 전류를 더 강력하게 억제하는 효과를 보였다. HCN 이온통로 네 가지 아형 중 HCN2는 주로 작은 크기의 통각 수용성 척수 후근 신경절 신경세포에서 가장 높은 발현을 보인다. 그러므로, 탄닌산의 억제 효과는 HCN2에 주로 작용하였을 것으로 보이나, 특정 아형에 대한 특이적 효과가 있는지 확인을 하는 추가적인 연구가 필요하다. 이 연구는 척수 후근 신경절 신경세포에 분포하는 HCN 이온통로를 표적으로 작용하는 새로운 약물의 발견으로, 탄닌산이 신경병증성 통증을 차단할 수 있는 새로운 가능성을 확인하였다는 점에서 매우 의미가 있다. ---------------------------------------------------------- 주요어 : 탄닌산(tannic acid), 과분극과 고리형 뉴클레오티드에 의해 활성화되는 이온통로 (HCN channel), Ih, 척수 후근 신경절 신경세포 (DRG neuron) 학 번 : 2000-22805 Effects of tannic acid on hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in peripheral sensory neurons Kim, Seong Ah Major in Neurobiology, Department of Dentistry, The Graduate School, Seoul National University Tannic acid (TA) is an astringent and a type of water-soluble plant polyphenolic compound. The biomedical effects of TA have been demonstrated in non-neuronal cells, however, little is known about its effects on peripheral sensory neurons. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play an important role in regulating neuronal excitability by generating a pace-making current, Ih. In this study, I examined the effect of TA on Ih in mouse dorsal root ganglion (DRG) neurons using whole-cell patch clamp recordings. TA (5 µM) significantly reduced the amplitude of Ih to 58.9 ± 4.2 % and alleviated the voltage sag mediated by HCN channels following hyperpolarization in DRG neurons. In addition, TA (0.05 to 50 µM) inhibited Ih in a concentration-dependent manner over the entire voltage ranges (-120 to –50 mV), with a half maximal inhibitory concentration (IC50) of 0.9 µM and a maximal inhibitory effect of 78 %. Interestingly, TA had a stronger inhibitory effect on Ih in small-sized DRG neurons through a cyclic AMP (cAMP)-independent pathways. Together, these results suggest that TA could directly block HCN channels in DRG neurons, independent of cAMP signals. These new findings highlight a potential novel drug for targeting HCN channels in DRG neurons. -------------------------------------------------------- Keywords : Tannic acid, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, Ih, dorsal root ganglion (DRG) neurons Student Number : 2000-22805

Ensuring energy security beyond conventional boundaries : three essays on energy security with geopolitics, bargaining power and market structure

류하늬 Seoul National University 2016 국내박사

This study seeks to introduce a methodology for analyzing the fundamental cause of fossil fuel procurement in order to accurately explain the current phenomenon beyond traditional interdisciplinary boundaries. The concept of “non-traditional security” has gained increasing importance as the international community has begun to recognize that the promotion of security requires not only maintenance of territorial and military security of state but also safeguarding of human communities from all threats, including unconventional, non-military risks at the supra-, inter-, and intra-state levels. It can be emphasized that energy security through the lens of human security focuses on spreading loss deeply and widely. In order to avoid energy insecurity, inter-state cooperation or supra-state actors are needed. Even though non-security issues have become increasingly common in almost all aspects of society, fossil fuel procurement remains an important goal of the nation-state. Furthermore, fossil fuel procurement results in geopolitics factors. This research aims to examine and explain the current state of fossil fuel procurement based on the understanding that there are overlapping perspectives regarding energy security between resource economics, international political economics, and geopolitics. First, the research attempts to provide a rationale for comparing the options for potential pipeline construction in Northeast Asia, and to explain the debate about realistic options for Northeast Asia. In addition, the proponents of pipeline natural gas (PNG) gas supply have begun to recognize the significance of non-traditional issues, which require cooperation from each state to promote regional security, although traditional security concerns still dominate the agenda of governments in terms of access through territorial borders and route decisions. To consider the linkage structure, network game and the link-based flexible allocation rule are applied to determine the benefits and bargaining power of Northeast Asian pipeline construction options. This could establish that the pipeline linkage structure comprises different values depending on which country participates in the pipeline coalition comparing the value of each route, the value allocated to each country, and their relative bargaining power. Consideration of the first mover could explain the reason for selecting the Russia–China–South Korea route or the Russia–North Korea–South Korea route in the decision on Northeast Asian pipeline. Second, this study attempts to identify the factors that determine the contract price of Europe’s long-term contract, and to figure out to what extent this would affect the contract price. Gas sales and the purchase agreement are dealt with at the firm level, even though the characteristics of natural resources primarily represent a strategic or politicized commodity of the nation-state, making the contract price an issue that should be dealt with at the national level. This study introduces LASSO analysis and double selection in order to establish the factors among potential variables that determine the long-term gas contract price. This alternative approach is motivated to figure out the price-determining factors in bilateral long-term gas supply contracts that display high-dimensional data and that underwent difficulty in conventional estimation. With respect to bargaining power, the state of a consumer country’s market structure is a pivotal factor responding to the supplier’s priority in the bilateral long-term contract. The results of our study signify that there is a room for buyers to negotiate preservation of loss arising from transportation costs. Factors that are assumed to have influence over the bargaining power of supplier and consumer countries during negotiations inherently have geopolitical characteristics. Third, this study attempts to determine the relationship between energy security and the institutional environment in the generation sector. It is an attempt to expand the security dimension to include intra-state energy delivery issues. The effect of liberalized restructuring—entry liberalization, privatization, and vertical divestiture—on the supply reliability in four separate sub-sectors of the electricity industry is evaluated empirically. This study attempts to establish how energy security is related to the restructuring of the electricity industry in the generation sector through the random effect model. Institutional change that is originally intended to enhance efficiency could depart from the initial goal in the generation sector.

(A) study on the marine prokaryotic diversity and antibiotic resistome using high-throughput sequencing and functional metagenomic analysis

장광일 Seoul National University 2016 국내박사

Prokaryotes (Bacteria and Archaea) play a significant role in global biogeochemical flux of biologically important elements in marine ecosystems. It has been firmly established that prokaryotes are major primary producers and heterotrophic consumers. Despite prokaryotes have significant roles in the biogeochemical flux in marine environmets, it has been estimated that more than 99% of the bacteria are non-culturable, leading to limited information of prokaryotic diversity because of an inability to mimic proper environmental niches. The relation between prokaryotic communities and their roles in the biogeochemical cycle is a topic of central research in environmental microbiology. Knowledge of the prokaryotic community compositions has rapidly increased due to development of molecular techniques based on amplification of the 16S rRNA gene and sequencing. This thesis includes studies on i) seasonal and spatial distribution of diversity of marine prokaryotes in the East Sea using pyrosequencing, ii) marine bacteria can be dispersed in the atmospheric environments, and iii) diversity of antibiotic resistance genes in the water column of the East Sea using the functional metagenomics approach. i) To understand in-depth prokaryotic diversity using high-throughput sequencing technique, we applied a pyrosequencing approach to study spatial and seasonal distribution of prokaryotes in the East Sea during 2011-2014. This study demonstrates that bacterial and archaeal communities varied along horizontal scale from coastal to offshore as well as vertical scale along depth, and furthermore their distribution patterns were different between seasons. Bacteroidetes, Alpha- and Gamma-proteobacteria dominated from epipelagic to mesopelagic zones in the East Sea. However, the discrepancy must be resulted from the low coverage of used primer for a major Alpha-proteobacteria group (SAR11). Thaumarchaeota and Euryarchaeota were dominant archaea in the epipelagic zone (0-100 m). Euryarchaeota decreased gradually with increasing depth. We found that dominant archaeal groups such as Nitrosopumilaceae and Halobacteria were more dynamics of distribution patterns in the epipelagic zone than in the mesopelagic zone. ii) Rainwater is an important natural resource to study airborne marine bacteria. Rainwater samples were collected during three heavy rain events at a suburban site in Seoul. Bacterial community compositions (BCCs) of rainwater samples, analyzed by using 16S rRNA gene-based pyrosequencing, differed considerably among the three rain events. Presumable marine bacterial OTUs which formed a robust clade with marine bacteria Lacinutrix spp. were at high concentrations in rainwater in April, likely reflecting origin from saline environments. Most of the Flavobacteria sequences were unusually high in April rainwater, which presumed to be of marine origin. Thus, these results suggest that some marine bacteria can be disseminated as aerosol particles and precipitated on land via rain. iii) The antibiotic resistance (AR) issue has critically increased. With the increasing use of antibiotics, resistance to antibiotics is developed by bacteria having AR mechanisms to defend themselves and survive from the antibiotic-polluted environments. Functional metagenomic approach is more useful to discover novel AR genes and resistance mechanisms rather than culture-dependent approaches, PCR and sequencing methods. We found a variety of AR genes conferring resistance to ampicillin, polymyxin B, rifampicin, fosfomycin and gentamicin in the East Sea. Among antibiotics, the majority (53.4%) of the cloned resistant genes was resistant to ampicillin, 18.8% to polymyxin B, 16.1% to rifampicin, 7.2% to fosfomycin and 4.5% to gentamicin. The source of host organisms inferred from the annotated AR genes was mainly marine bacterial taxa. This thesis suggested that bacteria might play a more significant role in marine environments. Bacterial community compositions in the East Sea varied across space and seasons. Furthermore, some marine bacteria can disperse in the atmospheric environments. Marine environments may be potentially global reservoir of AR genes.

Community-based health insurance in ethiopia : enrollment, memebrship renewal, and effects on health service utilization

Atnafu, Ayalneh Asmamaw Seoul National University 2018 국내박사

Community-Based Health Insurance in Ethiopia: Enrollment, Membership Renewal, and Effects on Health Service Utilization Ayalneh Asmamaw Atnafu Dept. of Health Care Management and Policy The Graduate School of Public Health Seoul National University Background: Community-Based Health Insurance (CBHI) received a considerable attention as a mechanism of health care financing and a potential alternative for a user fee in many low and middle-income countries. The Ethiopian government has introduced different measures to implement pre-payment schemes including CBHI as of 2010. In this dissertation, three sub-studies were designed and implemented to explore 1) The determinants of CBHI enrollment, 2) the magnitude and factors associated with CBHI membership renewal, and 3) the association between CBHI enrollment and health service utilization in Northwest Ethiopia. Methods: The main research design of the study was a case-comparison community based cross-sectional household survey linked to the health facility survey supplemented with a concurrent qualitative component. The study populations were all eligible households for CBHI in 15 selected clusters in five districts. A multi-stage cluster sampling was employed to obtain a representative sample for the three sub-studies. Applying a structured questionnaire, 2,008 households and 7 health centers were surveyed. Additionally, 8 focus group discussions (four with CBHI members and four with non-members) and 5 in-depth interviews were conducted to supplement the quantitative findings. A classical multivariate logistic regression, mixed-effect logistic regression, and bivariate-probit regression along with a thematic analysis of the qualitative data were used for the data analysis. Results: The findings from the enrollment study showed that household-related factors such as age, education, self-rated health status, perceived quality of health services, household size, knowledge and information (awareness) about CBHI were the main influential factors affecting enrollment into CBHI in the study area. Additionally, participation in informal associations, such as local credit associations, and health facility factors in terms of availability of laboratory tests significantly influence probability of enrollment. The findings from the membership renewal study showed that 36% of the participants were not willing to renew their membership for the next period. The results confirmed that once the households are enrolled in CBHI, factors related to institutional trusts, such as trust in public health facilities and trust in CBHI schemes, and inconvenience of the premium collection were the main influential factors to renew membership. Moreover, poor self-rated health status and perceived quality of healthcare services are correlated with membership renewal. Hence, there is a possibility of adverse selection with regard to CBHI enrollment and membership renewal in the study area. The third study revealed that CBHI enrollment is positively associated with adult outpatient use, inpatient care, and sick children health services visits. CBHI membership shows 0.50 (50%), 0.22 (22%), and 0.44 (44%) points higher probability of health service visits for adult outpatient, inpatient, and sick children’s health problem in the study area, respectively. Conclusion and recommendation: The study results in this thesis demonstrated important factors affecting CBHI enrollment and membership renewal. Moreover, it also revealed the link between CBHI enrollment and health service utilization. Therefore, multifaceted policy interventions need to be considered before the nationwide rollout of CBHI and implementation of Social Health Insurance (SHI) in Ethiopia. Strategies such as compulsory enrollment, differential premiums, and group enrollment are essential to tackle adverse selection. Provision of continuous education and social marketing activities to increase enrollment and maintain the sustainability of the schemes are crucial. Policy interventions that enhance the capacity of health facilities and CBHI schemes to provide the promised services to the members and build trust are also necessary. Benefit package expansion and other supply-side interventions are required to strengthen the positive effect of CBHI on health care utilization. Keywords: Adverse selection, Bivariate probit model, CBHI enrollment, Ethiopia, Health care use, Institutional trust, Membership renewal, Mixed-effect model, Mixed method Student number: 2014-31499