이기종 IoT 기기간 협력을 통한 네트워크 성능 향상

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 박세웅.The Internet of Things (IoT) has become a daily life by pioneering applications in various fields. In this dissertation, we consider increasing transmission data rate with energy efficiency, extending transmission coverage with low power, and improving reliability in congested frequency bands as three challenges to expanding IoT applications. We address two issues to overcome these challenges. First, we design a layered network system with a new structure that combines Bluetooth Low Energy (BLE) and Wi-Fi networks in a multi-hop network. Based on the system, we propose methods to increase data rate with energy efficiency and extend transmission coverage in a low-power situation. We implement the proposed system in the Linux kernel and evaluate the performance through an indoor testbed. As a result, we confirmed that the proposed system supports high data traffic and reduces average power consumption in the testbed compared to the existing single BLE/Wi-Fi ad-hoc network in a multi-hop situation. Second, we tackle the adaptive frequency hopping (AFH) problem of BLE through cross-technology communication (CTC) and channel weighting. We design the AFH scheme that weights the channels used by BLE devices with improving reliability in the congested bands of both Wi-Fi and BLE devices. We evaluate the proposed scheme through prototype experiments and simulations, confirming that the proposed scheme increases the packet reception rate of BLE in the congested ISM band compared to the existing AFH algorithm.사물인터넷은 현재 다양한 영역에서 application을 개척하여 생활화되어 왔다. 이 학위 논문에서는 사물인터넷의 응용 사례 확장을 위해 에너지 효율적인 전송 속도 향상, 저전력 상황에서의 전송 범위 확장, 혼잡한 대역에서의 신뢰성 향상을 새로운 도전 과제로 삼고, 이러한 도전 과제를 극복할 두 가지 주제를 다룬다. 첫째, 다중 홉 네트워크 상황에서의 블루투스 저전력과 Wi-Fi 네트워크를 결합 한 새로운 구조의 계층적 네트워크 시스템을 설계하고 이에 기반한 에너지 효율적인 전송 속도 향상 및 저전력 상황에서의 전송 범위확장을 제안한다. 제안된 시스템은 Linux 커널에 구현하여 실내 테스트베드를 통해 성능을 평가한다. 결과적으로 제안 한 기법이 다중 홉 상황에서 기존 블루투스 저전력/Wi-Fi 단일 ad-hoc 네트워크와 비교하여 높은 데이터 트래픽을 지원하며, 테스트베드에서의 평균 전력 소비를 줄 이는 것을 확인한다. 둘째, Cross-technology Communication (CTC)과 채널 가중치를 통한 블루투스 저전력의 Adaptive Frequency Hopping (AFH) 문제를 해결한다. 최종적으로 블루투스 저전력 기기가 사용하는 채널에 가중치를 두는 AFH 기법을 설계하여 Wi-Fi 와 블루투스 저전력 기기가 모두 혼잡한 대역에서의 신뢰성을 향상한다. 프로토타입 실험과 시뮬레이션을 통해 제안한 기법이 기존의 AFH 기법과 비교하여 혼잡한 ISM 대역에서 블루투스 저전력의 패킷 수신율을 증가시키는 것을 확인한다.1 Introduction 1 1.1 Motivation 1 1.2 Contributions and Outline 2 2 Wi-BLE: On Cooperative Operation of Wi-Fi and Bluetooth Low Energy under IPv6 4 2.1 Introduction 4 2.2 Related Work 7 2.2.1 Multihop Connectivity for Wi-Fi or BLE 7 2.2.2 Multi-radio Operation 11 2.3 System Overview 13 2.3.1 Control Plane 13 2.3.2 Data Plane 16 2.3.3 Overall Procedure 16 2.4 MABLE: AODV Routing over BLE 17 2.4.1 BLE Channel Utilization 17 2.4.2 Joint Establishment of Route and Connection 20 2.4.3 Link Quality Metric for BLE Data Channels 22 2.4.4 Bi-directional Route Error Propagation 25 2.5 Wi-BLE: Wi-Fi Ad-hoc over BLE 27 2.5.1 Radio Selection 27 2.5.2 Routing and Radio Wake-up for Wi-Fi 30 2.6 Evaluation 32 2.6.1 BLE Routing 33 2.6.2 Wi-Fi Routing over BLE 35 2.6.3 Radio Selection 38 2.7 Summary 40 3 WBC-AFH: Direct Wi-Fi to BLE Communication based AFH 41 3.1 Introduction 41 3.2 Background 45 3.2.1 Frequency hopping in BLE 45 3.2.2 Cross Technology Communication 47 3.3 Proposed AFH 49 3.3.1 CTC based informing 50 3.3.2 Weighted channel select 51 3.3.3 Hopping set size optimization 52 3.3.4 WBC-AFH 54 3.4 Evaluation 57 3.4.1 Setup 57 3.4.2 Robustness 60 3.4.3 Reliability 61 3.5 Future Work 65 3.6 Summary 66 4 Conclusion 67박

Insulin Requirement and Complications Associated With Serum C-Peptide Decline in Patients With Type 1 Diabetes Mellitus During 15 Years After Diagnosis

Objective: C-peptide is conventionally used in assessing pancreatic function in patients with diabetes mellitus. The clinical significance of this molecule during the course of type 1 diabetes mellitus (T1DM) has been recently revisited. This study aimed to investigate the natural course of C-peptide in T1DM patients over the period of 15 years and analyze the association between the residual C-peptide and diabetes complications. Methods: This retrospective study included a total of 234 children and adolescents with T1DM. Patient data including sex, age at diagnosis, anthropometric measures, daily insulin dose, serum HbA1c, post-prandial serum C-peptide levels, lipid profiles, and diabetic complications at the time of diagnosis and 1, 3, 5, 10, and 15 years after diagnosis were retrospectively collected. Results: Among the 234 patients, 101 were men and 133 were women, and the mean patient age at initial diagnosis was 8.3 years. Serum C-peptide decreased constantly since the initial diagnosis, and showed a significant decline at 3 years after diagnosis. At 15 years after diagnosis, only 26.2% of patients had detectable serum C-peptide levels. The subgroup with older patients and patients with higher BMI standard deviation score showed higher mean serum C-peptide, but the group-by-time results were not significant, respectively. Patients with higher serum C-peptide required lower doses of insulin and had fewer events of diabetic ketoacidosis. Conclusion: Serum C-peptide decreased consistently since diagnosis of T1DM, showing a significant decline after 3 years. Patients with residual C-peptide required a lower dose of insulin and had a lower risk for diabetic ketoacidosis.ope

Changes in the Prevalences of Obesity, Abdominal Obesity, and Non-Alcoholic Fatty Liver Disease among Korean Children during the COVID-19 Outbreak

Purpose: We aimed to investigate the prevalences of obesity, abdominal obesity, and non-alcoholic fatty liver disease (NAFLD) among children and adolescents during the coronavirus disease 2019 (COVID-19) outbreak. Materials and Methods: This population-based study investigated the prevalences of obesity, abdominal obesity, and NAFLD among 1428 children and adolescents between 2018–2019 and 2020. We assessed the prevalences of obesity, abdominal obesity, and NAFLD according to body mass index, age, sex, and residential district. Logistic regression analyses were performed to deter mine the relationships among obesity, abdominal obesity, and NAFLD. Results: In the obese group, the prevalence of abdominal obesity increased from 75.55% to 92.68%, and that of NAFLD increased from 40.68% to 57.82%. In age-specific analysis, the prevalence of abdominal obesity increased from 8.25% to 14.11% among par ticipants aged 10–12 years and from 11.70% to 19.88% among children aged 13–15 years. In residential district-specific analysis, the prevalence of both abdominal obesity and NAFLD increased from 6.96% to 15.74% in rural areas. In logistic regression analy sis, the odds ratio of abdominal obesity for NAFLD was 11.82. Conclusion: Our results demonstrated that the prevalences of abdominal obesity and NAFLD increased among obese Korean chil dren and adolescents and in rural areas during the COVID-19 outbreak. Additionally, the prevalence of abdominal obesity in creased among young children. These findings suggest the importance of closely monitoring abdominal obesity and NAFLD among children during COVID-19, focusing particularly on obese young children and individuals in rural areas.ope

Trends in Prediabetes and Non-Alcoholic Fatty Liver Disease Associated with Abdominal Obesity among Korean Children and Adolescents: Based on the Korea National Health and Nutrition Examination Survey between 2009 and 2018

Investigations on the trends of prediabetes and non-alcoholic fatty liver disease (NAFLD) among children are scarce. We aimed to analyze the trends of prediabetes and NAFLD, as well as their association, among Korean children and adolescents from 2009 to 2018. This study investigated the prevalence of prediabetes, NAFLD, and abdominal obesity among 6327 children and adolescents aged 10-18 years according to age, sex, and body mass index (BMI) using a nationally representative survey. The prevalence of prediabetes, NAFLD, and abdominal obesity increased from 5.14%, 8.17%, and 5.97% respectively, in 2009 to 10.46%, 12.05%, and 10.51% respectively, in 2018. In age-specific analyses, an adverse trend in NAFLD was significant only in participants aged 16-18 years while the prevalence of prediabetes worsened significantly in all age groups. In BMI-specific analyses, the prevalence of prediabetes and NAFLD increased significantly only in participants with normal BMI. In logistic regression analysis, the odds ratio of prediabetes for NAFLD was 1.85 and those of abdominal obesity for prediabetes and NAFLD was 1.85 and 9.34, respectively. Our results demonstrated that the prevalence of prediabetes and NAFLD was increasing in association with abdominal obesity in Korean children and adolescents.ope

Comparison of the Modified TyG Indices and Other Parameters to Predict Non-Alcoholic Fatty Liver Disease in Youth

We investigated the modified triglycerides-glucose (TyG) indices and other markers for non-alcoholic fatty liver disease (NAFLD) in 225 participants aged 10-19 years, and the participants were divided into subgroups according to their NAFLD grade. We performed logistic regression analysis and calculated the odds ratios (ORs) with 95% confidence intervals (CIs) of tertiles 2 and 3 for each parameter, with those of tertile 1 as a reference. The area under the receiver operating characteristic (ROC) curve was calculated to compare the parameters for identifying NAFLD. TyG and modified indices, aspartate transaminase-to-platelet ratio index (APRI)-body mass index (BMI), APRI-BMI standard deviation score (SDS), APRI waist-to-hip ratio, fibrosis-4 index (FIB)-4, and hepatic steatosis index (HSI) were higher in participants with NAFLD than in those without NAFLD. The ORs and 95% CIs for NAFLD progressively increased across tertiles of each parameter. TyG and modified TyG indices, FIB-4, HSI, and modified APRIs, except APRI waist-to-height ratio, predicted NAFLD significantly through ROC curves. Modified TyG indices, APRI-BMI SDS, and HSI were superior to the other markers for NAFLD prediction. Modified TyG indices, APRI-BMI SDS, and HSI appear to be useful for assessing NAFLD in youths.ope

The Genotype-Phenotype Correlation in Human 5α-Reductase Type 2 Deficiency: Classified and Analyzed from a SRD5A2 Structural Perspective

The phenotype of the 5α-reductase type 2 deficiency (5αRD2) by the SRD5A2 gene mutation varies, and although there have been many attempts, the genotype-phenotype correlation still has not yet been adequately evaluated. Recently, the crystal structure of the 5α-reductase type 2 isozyme (SRD5A2) has been determined. Therefore, the present study retrospectively evaluated the genotype-phenotype correlation from a structural perspective in 19 Korean patients with 5αRD2. Additionally, variants were classified according to structural categories, and phenotypic severity was compared with previously published data. The p.R227Q variant, which belongs to the NADPH-binding residue mutation category, exhibited a more masculine phenotype (higher external masculinization score) than other variants. Furthermore, compound heterozygous mutations with p.R227Q mitigated phenotypic severity. Similarly, other mutations in this category showed mild to moderate phenotypes. Conversely, the variants categorized as structure-destabilizing and small to bulky residue mutations showed moderate to severe phenotypes, and those categorized as catalytic site and helix-breaking mutations exhibited severe phenotypes. Therefore, the SRD5A2 structural approach suggested that a genotype-phenotype correlation does exist in 5αRD2. Furthermore, the categorization of SRD5A2 gene variants according to the SRD5A2 structure facilitates the prediction of the severity of 5αRD2 and the management and genetic counseling of patients affected by it.ope

합성에스트로젠이 체외에서의 착상전 생쥐 배아의 발달과 사람 자궁내막 상피세포의 성장에 미치는 영향에 관한 연구

Thesis (doctoral)--서울대학교 대학원 :농생명공학부 동물자원과학과 동물생식학전공,2002.Docto

H-Y 항원의 boosting 방법이 H-Y 항혈청 생산율과 역가에 미치는 효과와 H-Y 항혈청에 의한 토끼 수정란의 성판별에 관한 연구

Thesis (master`s)--서울대학교 대학원 :동물자원과학과 동물번식생리학전공,1996.Maste

비쑥의 휘발성물질에 의한 KB 세포의 세포사멸 유도

Artemisia scoparia (A. scoparia), perennial herb is indigenous to Korea and has been traditionally used in liver damage. We investigated the effect of the essential oil obtained from A. scoparia on apoptosis of KB cells. Cytotoxicity and cellular DNA content were analyzed by MTT assay and flow cytometry, agarose gel electrophoresis, and Hoechst 33258 staining. The caspase-3 and poly (ADP-ribose) polymerase (PARP) proteins were estimated by Western blotting method. We found that the essential oil induced the apoptosis of the KB cells by concentrations of 0.4 to 0.2 mg/ml which was verified by DNA fragmentation, apoptotic bodies, and the sub-G0/G1 ratio. The essential oil also transient caspase-9 and caspase-3 activity and cleavage of PARP in KB cells for 24 h. The essential oil-induced apoptotic cell death was accompanied by up-regulation of Bax and down-regulation of Bcl-2. In conclusion, we demonstrated that the essential oil of A. scoparia induces apoptosis in KB cells.ope

Buffer Policy based on High-capacity Hybrid Memories for Latency Reduction of Read/Write Operations in High-performance SSD Systems

Recently, an SSD with hybrid buffer memories is actively researching to reduce the overall latency in server computing systems. However, existing hybrid buffer policies caused many swapping operations in pages because it did not consider the overall latency such as read/write operations of flash chips in the SSD. This paper proposes the clock with hybrid buffer memories (CLOCK-HBM) for a new hybrid buffer policy in the SSD with server computing systems. The CLOCK-HBM constructs new policies based on unique characteristics in both DRAM buffer and NVMs buffer for reducing the number of swapping operations in the SSD. In experimental results, the CLOCK-HBM reduced the number of swapping operations in the SSD by 43.5% on average, compared with LRU, CLOCK, and CLOCK-DNV.2