Temporal phenomena in the Korean conjunctive constructions

Kim, Dongmin UMI ProQuest LLC 2016 국내박사

Design of Provably-Secure Public Auditing Protocols in Cloud Storage

Kim, Dongmin 고려대학교 정보보호대학원 2017 국내박사

With cloud storage services, users can handle an enormous amount of data in an efficient manner. However, due to the widespread popularization of cloud storage, users have raised concerns about the integrity of outsourced data, since they no longer possess the data locally. To address these concerns, many auditing schemes have been proposed that allow users to check the integrity of their outsourced data without retrieving it in full. However, most of the schemes are not secure against active adversary as well as does not ensure an efficiency of the verification process. In this thesis, we analyze the weakness of previous schemes as well as present new schemes which could improve the security of the schems. We also define various types of adversaries and prove that our schemes are secure against these adversaries under formal security models. - We propose a provably-secure public auditing scheme with deduplication which has constant communication and computation costs. We also define two types of adversaries and prove that our scheme is secure against these adversaries under formal security models. - We propose a provably-secure public auditing scheme for the shared data. We also propose two formal security models extended from the previous security models, tag-unforgeability and proof-unforgeability, and prove the securities of our construction under the formal models. So far, there exists no public auditing scheme for the shared data which is proved in the formal security models. - We first design a provably-secure certificateless public auditing(CL-PA) scheme which has the constant computation cost in verification. The previous certificateless public auditing schemes require the linearly increasing verification time with respect to the number of the challenged message blocks. We also define the three formal security models which ensures the security against the public key replacement attack, malicious-but-passive-KGC attack, and proof forgery. Futhermore, we show that our certificateless scheme is secure against existential forgery by proving the security under the models.

Synthesis and characterization of photocurable and thermal curable polymer with cyclohexane moiety

Kim, Dongmin Sungkyunkwan University 2015 국내석사

(-)-Catechin-7-O-β-D-apiofuranoside ameliorates hepatic fibrosis by suppressing hepatic stellate cell activation via inhibition of STAT3 pathway

Kim, Dongmin Sungkyunkwan university 2020 국내석사

Hepatic fibrosis is a progressive disease, characterized by the abnormal accumulation of extracellular matrix (ECM). Hepatic stellate cells (HSCs) have been proposed as the main source of ECM production in hepatic fibrosis. When HSCs are activated by chronic injuries, HSCs show features of myofibroblast-like cells. Therefore, many therapeutic strategies are focusing on inhibition and reversion of HSCs activation. In the present study, the effects of (–)-catechin-7-O-β-D-apiofuranoside (C7A) on HSCs activation and possible mechanisms of action were investigated in vitro, in vivo. EtOH extract of Ulmus davidiana var. japonica root barks, which have been widely used as a folk medicine in Esat Asia, exerted anti-fibrotic activity in terms of collagen production in HSCs. Further, as a result of comparing anti-fibrotic activities of four catechins isolated from the EtOAc fraction of the EtOH extract, C7A was selected as the most effective single compound and consistent with the expectation, C7A significantly suppressed activation of HSCs activation in protein and mRNA levels. Then, the relationship between C7A and the signal transducer and activator of transcription 3 (STAT3) signaling pathway, involved in proliferation and activation of HSCs, was speculated as a possible mechanism. C7A noticeably inhibited phosphorylation of STAT3 and translocation of p-STAT3 to the nucleus. Expression levels of MMP-2 and MMP-9, which are downstream target genes of p-STAT3, are also decreased by C7A treatment. In order to confirm the anti-fibrotic effects of C7A, a thioacetamide (TAA)-induced liver fibrosis model was established in mice. Consequently, C7A significantly alleviated ECM accumulation and decreased serum aspartate aminotransferase (AST) and alanine transaminase (ALT) levels, which were markedly elevated by TAA injection. Moreover, C7A strongly suppressed HSCs activation- and ECM-associated proteins and mRNA expression through inhibiting STAT3 signaling in liver tissue. This is the first attempt to demonstrate the hepatoprotective effects of C7A with a possible mechanism. This study provides the experimental evidence that C7A has therapeutic potentials for hepatic fibrosis through inhibition of HSCs activation.

Dihydroergotamine loaded PEGylated human serum albumin nanoparticles for the treatment of endotoxin induced sepsis

Kim, Dongmin Sungkyunkwan university 2021 국내석사

Sepsis is a systemic inflammatory disease with high mortality caused by influx of bacterial substances into our body. Unfortunately, no pharmaceutical interventions specifically targeting the disease are not currently available in the clinics. Endeavor to find affective agent to sepsis led to the re-positioning of a conventional drug, dihydroergotamine (DHE), which acts as an agonist to the 5-hydroxytryptamine (5-HT1B and 5-HT1D) receptors to reduce migraine. The alternative ability of DHE to induce the expression of nuclear receptor 4A1 (NR4A1, Nur77) may be useful to suppress inflammatory responses by binding to p65 protein. The inactivation of NF-κB by the intervention of DHE would be effective for sepsis and cytokine storm. Self-assembled polyethylene glycol-conjugated human serum albumin (PEG-HSA) nanoparticle was employed as a vehicle for the dissolution and delivery of DHE. DHE can be readily loaded into the nanoparticles using film casting and rehydration technique using a PEG-HSA conjugate. The DHE loaded PEG-HSA(PEG-HSA/DHE) nanoparticles were characterized by determining loading efficiency, particle size, shape and cellular uptake by HPLC, DLS, TEM and FACS, respectively. The anti-inflammatory effect of PEG-HSA/DHE was assessed in murine macrophages (Raw 264.7) and endotoxin-induced sepsis animal model. The treatment of PEG-HSA/DHE on lipopolysaccharide (LPS)-treated Raw 264.7 cells and LPS-induced sepsis mouse resulted in significant down regulation of inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha. These results suggest that PEG-HSA/DHE can be considered as a potential candidate for inflammatory diseases. 패혈증은 우리 몸에 감염성 물질이 유입되어 일어나는 사망률이 높은 전신 염증성 질환이다. 안타깝게도 현재 이 질병에 효과적인 치료제가 없다. 패혈증에 대한 치료 약물을 찾기 위한 노력은 5-하이드록시 트립타민 (5-HT1B 및 5-HT1D) 수용체에 대한 작용제 역할을 하여 편두통을 줄이는 기존의 약물인 디하이드로에르고타민(DHE)의 약물재배치를 시도했다. 핵 수용체 4A1 (NR4A1, Nur77)의 발현을 유도하는 DHE 의 대체적 능력이 p65 단백질에 결합하여 염증 반응을 억제하는 데 유용할 것이다. DHE 의 작용에 의한 NF-κB 의 억제는 패혈증 및 사이토 카인 과다증에 효과적이다. 자가 조립된 폴리에틸렌 글리콜이 결합된 인간 혈청 알부민 (PEG-HSA) 나노 입자는 DHE 의 가용화 및 전달을 위한 전달체로 사용되었다. DHE 는 PEG-HSA 결합체의 필름 형성 및 재 수화 방식을 사용하여 나노 입자에 쉽게 봉입 될 수 있다. HPLC, DLS, TEM 및 FACS 를 이용해서 각각 봉입 효율, 입자 크기, 형상 및 세포 흡수율을 확인하여 DHE 가 봉입 된 PEG-HSA (PEG-HSA/DHE) 나노 입자의 특성을 파악했다. PEGHSA/DHE 의 항 염증 효과는 쥐의 대식세포 (Raw 264.7 세포) 및 내독소 유발 패혈증 동물 모델에서 평가되었다. 지질 다당류(LPS)를 처리한 Raw 264.7 세포와 LPS 로 유도된 패혈증 쥐 모델에 대한 PEG-HSA/DHE 의 처리는 염증성 사이토카인인 인터루킨-6 및 종양 괴사 인자-알파의 감소를 초래했다. 이러한 결과는 PEG-HSA/DHE 가 염증성 질환의 잠재적인 치료제 후보가 될 수 있음을 시사한다.

Development of New Earth System Model and Investigation of the Impacts of Vegetation on Hydrological Cycle Using Developed ESM

Dongmin Kim Graduate School of UNIST 2017 국내박사

This thesis is to develop a version of the earth system model (ESM) with the interactive vegetation parameterization scheme and investigate the influences and feedback processes driven by terrestrial vegetation on climate and global hydrological cycle. Previous observation and modeling studies suggested that the temporal variation of atmospheric CO2 concentration depends largely on the carbon uptake by terrestrial biosphere, compared with that by oceanic counterpart. In the state-of-the-art ESMs, the parameterization uncertainty in the carbon cycle between land and atmosphere is still large, which tend to produce a significant spread in the model simulations for the ambient CO2 amount and its secular trend. The huge spread of CO2 in turn causes a wide spread in the simulated climate through vegetation-climate feedbacks, which make their future climate projection less accurate and less reliable. One aspect of the parameterization uncertainties lies in the nitrogen process, a critical process coupled with the carbon cycle by limiting supplement of nutrients both to subsurface soil organic matter (SOM) and plants at the surface, which is either absent or represented poorly in current ESMs. A few ESMs with a primitive version of the carbon-nitrogen (C-N) coupling exhibit a significant model deficiency such as the underestimation in the carbon pools or storages in the vegetation and sub-surface soil systems and substantially weak carbon uptake, whereas the other models without C-N coupling tend to overestimate them. The interaction and feedbacks between vegetation and climate should be, therefore, understood based on a more improved understanding of the C-N cycle and its representation in the ESMs. Before developing new ESM, the model intercomparision using 11 CMIP5 ESMs has been done first to evaluate the overall representation of the terrestrial biogeochemical cycle and the model dependences. Using the MODIS satellite estimates, the study validates the simulation of gross primary production (GPP), net primary production (NPP), and the carbon use efficiency (CUE) depending on plant function types (PFTs). The models show noticeable deficiencies from MODIS in the simulation of horizontal patterns of GPP and NPP as well as large simulation differences, although their multi model ensemble (MME) mean represents realistic global mean value and the spatial distributions. Larger model spreads in GPP and NPP than those in surface temperature and precipitation suggest that the simulation difference in terrestrial carbon cycle is largely attributed to the uncertainties in the dynamic vegetation model parameterizations. The models also exhibit large differences in the simulation for CUE geographically and at the change of dominant PFTs, primarily due to the differences in parameterization. While the MME of CUE shows strong dependence on surface temperature, the observed CUE from MODIS shows more complex and non-linear sensitivity. To developing new ESM, this study uses the Geophysical Fluid Dynamics Laboratory Earth System Model version 2 (GFDL-ESM2M) as a base model for the further development. GFDL-ESM2M has a full capability of interactive vegetation parameterizations, and with decent simulations in the long-term climatology and climate variability compared with other ESMs in the Fifth Phase of the Coupled Model Intercomparison Project (CMIP5). The model has comprehensive carbon cycle both for the terrestrial and aquatic environments, yet with no C-N coupling. In order to implement the C-N cycle in the model, this study replaces the Land Model version 3 of GFDL-ESM2M with the Community Land Model version 4 (CLM4). The latter land model is the most recent version in the development suits by NCAR, with more detailed vegetation types and biogeochemistry as well as the interactive C-N parameterizations. However, the Community Earth System Model (CESM) with CLM4 has a well-known bias of the pronounced underestimation in the terrestrial carbon uptake. This is one of the major motivations in this research. The developed ESM named as UNIST-ESM shows the reasonable simulation skill for climate conditions and terrestrial carbon fluxes. The features of distribution of carbon cycle is depended onto land surface models and the features of spatial distribution of climate conditions is dominant to characteristics for atmospheric model in UNIST-ESM. In terrestrial carbon cycle, UNIST-ESM still has systematic bias for simulating GPP in the globe. The underestimation (overestimation) of GPP over high latitude region (tropics) in UNIST-ESM is major deficiencies of simulation of terrestrial carbon cycle. For improvement of deficiencies of terrestrial carbon cycle in UNIST-ESM, this study develops a new parameterization method for determining Q10 by considering the soil respiration dependence on soil temperature and moisture obtained by multiple regression. This study further investigates the impacts of the new parameterization on the global carbon cycle budget. Our results show that non-uniform spatial distribution of Q10 tends to enhance heterogeneous anomaly of soil respiration comparing with the control simulation with uniform Q10. Moreover, it tends to improve the simulation of observed relationship between soil respiration and soil temperature and moisture, particularly over cold and dry regions. The new parameterization improves the simulation of gross primary production (GPP) by reducing bias in the global mean comparing with the FLUXNET-MTE observation data. Besides, GPP over high latitudes is significant increased by about two times from the control simulation. The realistic Rs and GPP simulation induced to represent carbon balance between release at the subsurface and uptake at the surface over terrestrial biosphere reasonably. Overall, enhanced heterogeneous temperature sensitivity in the soil decomposition process in the model showed the improvement of production and respiration. For evaluation of vegetation feedback on the climate, this study investigated the vegetation-climate feedback and impacts of vegetation change on the hydrological cycle in the East Asian monsoon region using comprehensive and developed UNIST-ESM. The intensity of East Asian summer monsoon (EASM) in the future increase due to enhance moisture flux at the surface by increased vegetation in EA. However, low-level relative humidity in the future decreases due to relatively increasing temperature comparing with enhanced moisture increase over EA. This process induces to suppress the formation of low-level cloud in the future. Therefore, enhanced incoming solar radiation over China regions is occurred by suppressed low-level cloud in the future climate. On the other hand, the exception of additional anthropogenic heating in future climate, the role of increase vegetation on the variation of EASM is opposite signal from the future climate scenarios. In terms of local hydrological process, the increased vegetation induces incareasing evapotranspiration and surface moisture flux over vegetated regions. This increment of moisture source from increased vegetated area tends to increase formation of low-level cloud due to small perturbation of temperature increase in this simulation. Enhanced amount of low-level cloud tends to decrease incoming solar radiation at the surface due to reflecting by clouds. It emphasized surface cooling in the increased vegetation regions. This surface cooling also affects to depress local vertical updraft over China where has large plants. Suppressed vertical updraft makes atmosphere stabilization over land area. The convective precipitation is affected to decrease by depressed vertical updraft associated with cooling temperature. In the focus of the large-scale circulation, the cooling temperature over vegetated area tends to decrease the land-sea contrast. Thermally more uniformed land and ocean surface make weak low-level circulation and meridional moisture transport over EA regions. This study suggested that the roles of vegetation to climate variation and hydrological cycle are homogenous not only location but also environmental climate conditions.

(A) study on integrated operation of distributed generations and optimal placement and sizing of ESS in power grid

김동민 Graduate School, Yonsei University 2021 국내박사

This dissertation presents studies on the stability of Korea power system in 2030 and the operation for distributed generators, mainly energy storage system (ESS), based on the power sensitivity analysis. Due to environmental pollution and social concerns about the coal and nuclear power generators, which are major power sources of existing power systems, interest in environment-friendly power generation is growing. As a result, the facility capacity of distributed generators using renewable energy sources continues to increase worldwide, and the capacity of new installation facilities is also increasing. Not only developed countries but also many developing countries are participating in the change to an environment-friendly power generation mix. In Korea, efforts are also being made to reduce the proportion of existing coal and nuclear power generators. As part of that, Korea government announced the “Renewable Energy 2030” project in 2017. The project aims to increase the amount of distributed generators by 2030 to 20% of Korea's total power generation. To this end, large-scale offshore wind turbine (WT) farms and large-scale photovoltaic (PV) farms are planned to be newly installed. In addition, in order to translate to an environment-friendly power generation mix, the aging coal and nuclear power generators are phased out and new installations of previously planned nuclear power plants are minimized. Liquefied natural gas (LNG) generators and distributed generators are newly installed to replace coal and nuclear generators. The classical stability of the power system is determined by the synchronous generators. Coal generators, nuclear power generators, and LNG generators are all synchronous generators. On the other hand, distributed generators using renewable energy sources are converter-based generators, not synchronous generators. Synchronous generators ensure the stability of the power system by using the kinetic energy generated by the rotation of the shaft. This stabilization is achieved by the governor of the synchronous generator, and the stabilization contribution is determined by the parameters input for each generator. As a result, the overall stability of the power system can be calculated from the parameter values of the synchronous generators participating in the stabilization. Converter-based generators operate with electrical signals, and unlike synchronous generators, there is no inertia. For this reason, if the penetration of converter-based generators to the power system increases, the overall inertia and stability of the power system decrease. The following studies are needed to increase the penetration of distributed generators using renewable energy sources while ensuring stable and reliable power system operation. First, in order to simulate the distributed generators, PV generator, WTG, ESS, and converter for the distributed generators were modeling in detail, and the stability of Korea power system in 2030 was analyzed. The testbed reflecting the data of the actual power system was constructed, and the power mix was transited so that the distributed generators would generate 20% of the total power generation. The stability of the power system due to the connection of large-scale distributed generator is analyzed mathematically and verified through several simulations. Second, studies were conducted on the operation of the power system in the Korea power system connected to large-scale distributed generators. Large-scale distributed generators with proposed virtual multi-slack (VMS) control could properly adjust the generations to the power generation-load imbalance, thereby verifying the improvement of the stability of the power system. In addition, for stable distributed generator operation with VMS control, the power reserve of each distributed generator was calculated, and appropriateness was verified. Finally, in order to secure reliability in the power system, studies were conducted on ESS connection. ESS is a solution to the power reserve of DGs and over-generation of distributed generators, and studies on the optimal installation placement and sizing of ESS were essential to connect it reliably and efficiently to the power system. In this dissertation, the algorithm to determine the optimal installation placement of ESS and to determine the optimal installation sizing according to the optimal installation placement based on power sensitivity analysis was presented.

Risk of dementia in stroke-free patients diagnosed with atrial fibrillation : data from a population-based cohort

김동민 Graduate School, Yonsei University 2022 국내박사

Aims: Atrial fibrillation (AF) is generally regarded as a risk factor for dementia, though longitudinal studies assessing the association between AF and dementia have shown inconsistent results. This study aimed to determine the effect of AF on the risk of developing dementia using a longitudinal, population-based, stroke-free elderly cohort. Methods: The association of incident AF with the development of incident dementia was assessed from Jan 1, 2005 to Dec 31, 2012 in 260,638 dementia- and stroke-free participants aged ≥60 years in the Korea National Health Insurance Service-Senior cohort. Results: Incident AF was observed in 10,975 participants over an observational period of 1,613,322 person-years (0.68% per year). During the observational period, the incidence of dementia was 2.5 and 1.6 per 100 person-years in the incident AF and propensity score matched AF-free groups, respectively. After adjustment, the risk of dementia was significantly increased by incident AF with a hazard ratio (HR) of 1.84 [95% confidence interval (CI): 1.71-1.98], even after censoring for stroke (1.64, 95% CI: 1.51-1.79). Incident AF increased the risk of both Alzheimer (HR 1.63, 95% CI 1.50-1.78) and vascular dementia (HR 3.09, 95% CI 2.56-3.72). Among patients with incident AF, oral anticoagulant (OAC) use was associated with a preventive effect on dementia development (0.67, 95% CI: 0.57-0.79, p<0.001), and an increasing CHA2DS2-VASc score was associated with a higher risk of dementia. Conclusion: Incident AF was associated with an increased risk of dementia, independent of clinical stroke in an elderly population. OAC use was linked with a decreased incidence of dementia. 배경 및 목적: 심방세동은 일반적으로 치매 발생의 위험인자로 알려져 있으나 아직까지 전향적인 연구에서는 일관적인 결과를 보이고 있지는 못하다. 본 연구는 노인 인구로 구성된 전향적인 자료를 통해, 뇌경색이 없었던 인구에서도 심방세동이 치매 발생과 연관이 있는지 확인하고자 한다. 방법: 심방세동과 치매 발생과의 연관성을 확인하기 위해 건강보험관리공단의 노인코호트를 이용하였다. 2005년 1월 1일부터 2012년 12월 31일까지 등록된 환자 중 기존에 뇌경색 및 치매가 없는 260,638 명의 참가자를 분석하였다. 결과: 심방세동은 관찰 기간 1,613,322 인-년 동안 10,975 명에서 발생하였다(0.68%/년). 관찰 기간 동안 치매 발생 건수는 심방세동 군에서 2.5건/100인-년, 성향 점수 매칭 일반 인구에서 1.6건/100인-년으로 나타났다. Cox 회귀분석을 통해 기타 독립 변수를 보정한 후, 심방세동의 치매 발생 위험비는 1.84 [95% 신뢰구간: 1.71-1.98]이었으며 이는 추적관찰 중 발생한 뇌경색을 제외하고도 유의하였다(1.64, 95% 신뢰구간: 1.51-1.79). 심방세동은 알츠하이머 치매(위험비 1.63, 95% 신뢰구간 1.50-1.78) 및 혈관성 치매를(위험비 3.09, 95% 신뢰구간 2.56-3.72) 모두 증가시키는 것으로 나타났다. 심방세동 환자 중, 경구 항응고제를 사용한 경우 치매 발생이 적었다(위험비 0.67, 95% 신뢰구간: 0.57-0.79, p<0.001), 또한 높은 CHA2DS2-VASc 점수는 치매 발생의 위험도를 높이는 것으로 나타났다. 결론: 추적관찰 중 발생한 심방세동은 임상적인 뇌경색과는 독립적으로 치매 발생의 위험성을 증가시켰다. 경구 항응고제 치료를 통해 심방세동으로 인한 치매 발생을 감소시킬 수 있었다.

Theoretical study on circuit QED system based on triple-leg stripline resonator

김동민 Graduate School, Yonsei University 2019 국내박사

회로 양자전기역학 시스템에서 세 개의 다리를 가진 공진기 (TSR)에 대한 이론적 연구를 진행하였다. 기존의 직선 공진기와는 다르게, TSR은 두 개의 겹친 상태의 마이크로파 모드가 공진기 내부에 존재한다. 초전도 큐빗(qubit)이 TSR의 한 다리에 연결되어 있으면 하나의 모드만이 큐빗과 연결되고, 다른 하나는 연결되지 않는다. 이런 회로 양자전자역학 시스템에서 초전도 큐빗과 flying 마이크로파 큐빗 간의 복합 큐빗 양자 게이트 연산을 이론적으로 구현하였다. 실험적으로 가능한 변수들을 대입하여 두 혼합형 큐빗의 선택적인 양자 위상 뒤집힘 (Controlled Phase Flip, CPF)을 구상하였다. 또한, TSR로 회로 양자전기역학 시스템에서 이차원 광자 격자구조를 구성할 수 있다. 이런 이차원 광자 결정 구조는 물질의 특성을 불순물 없이 이해하는 데 도움이 된다. 그래핀과 같은 이차원 육각 구조 물질은 최근까지도 많은 관심을 받고 있다. Dirac 물질인 그래핀은 전자가 질량이 없는 것처럼 움직이기 때문에 일반적인 고체 물질과 다른 특성을 보여준다. 기존의 일반적인 초전도체 공진기들은 Kagome 격자나 Lieb 격자와 같은 광자 격자를 구성할 수 있었다. 하지만 구조적 한계로 그래핀과 같은 벌집 모양의 육각 구조를 만들어 낼 수는 없었다. 반면 TSR은 세 개의 다른 TSR들과 연결할 수 있으므로 이것을 이용하면 육각 광자 결정구조를 회로 양자전기역학 시스템에서 구성할 수 있다. 그래핀과 비교하여 광자 궤도(photonic orbital)로 생성되는 Dirac 분산을 이론적으로 예측하였다. 또한, TSR 지그재그 나노 리본의 평평한 끝머리 상태 (flat edge state)가 그래핀 지그재그 나노 리본(ZGNR)과 비교하였을 때 다른 구조를 보여주는 것을 예측하였고, 끝머리 상태를 TSR의 끝에 연결된 초전도 큐빗들로 조절할 수 있음을 보이겠다. We theoretically propose a circuit QED system implemented with triple-leg stripline resonator (TSR). Unlikely from linear stripline resonator, the fundamental intra-cavity microwave modes of the TSR are two-fold degenerate. When a superconducting qubit is placed near one of the TSR legs, one fundamental mode is directly coupled to the qubit, while the other one remains uncoupled. Using our circuit QED system, we have theoretically studied a two-qubit quantum gate operation in a hybrid qubit composed of flying microwave qubit and superconducting qubit. We have demonstrated that for the hybrid qubit, the quantum controlled phase flip (CPF) gate can be reliably implemented for the experimentally available set of parameters. And TSR can be used as building block of two-dimensional photonic lattice in circuit QED system. Implementing two-dimensional material with photonic lattice helps to understand its property without impurity. Two-dimensional hexagonal structure materials such as graphene have received much attention in recent years. In graphene, which is true Dirac material, the electrons show massless motion with different character from the ordinary solid structure. A typical resonator could produce several lattice structures including a Kagome lattice or Lieb lattice in a straight line. However, due to its structural limitations, it is not possible to create hexagonal structures like graphene. Hence, we have theoretically implemented a hexagonal optical lattice as a circuit QED using a TSR. A TSR can create a honeycomb lattice structure because each resonator can be connected to three different resonators. We have theoretically predicted Dirac dispersion produced by photonic orbital in optical lattice structure by comparing this structure with graphene. In addition, the edge flat band of zigzag TSR ribbon is shifted differently from zigzag graphene nanoribbon (ZGNR) which were difficult to observe edge state due to the impurity of the edge in the case of the actual atomic structure. We show that the edge state is controlled by superconducting qubits laterally to the end of a TSR.

Relative Navigation Algorithm Using PSD and Heterogeneous Sensor Fusion

김동민 충남대학교 대학원 2020 국내석사

본 연구는 PSD와 이종 센서 융합을 이용한 상대 항법 알고리즘에 대한 연구로써 실제 PSD 센서 시스템 구축 및 기본 특성 파악, 측정치 오차 보정 알고리즘 설계, 상대 항법 알고리즘 설계 및 수치 시뮬레이션을 통한 검증, 실제 지상 시험 환경 구축 및 이를 통한 검증을 수행하였다. 먼저, 해당 시스템의 구축을 위해 적절한 검출 거리 및 화각이 도출될 수 있도록 적외선 파장 대역, 광학계 등을 선정하여 통합하였다. 이후, 렌즈 왜곡, 제작 오차 등에 의해 발생하는 측정치 오차를 보정하기 위해 선형 보간법을 이용하는 보정 알고리즘을 설계하였다. 센서 장착 오프셋, 측정 모델 정규화, 적응 잡음 등을 고려하여 동종 및 이종 센서 융합 상대 항법 알고리즘을 각각 설계하였다. 상대 항법 알고리즘은 측정 모델의 비선형성을 고려하기 위해 확장 칼만 필터 및 무향 칼만 필터를 적용하여 설계하였으며 이를 위한 시스템 모델의 경우 등속도 모델을 사용하였다. 동종 센서 시스템의 경우 3쌍의 PSD 센서 시스템을 사용하며 이종 센서 시스템의 경우 1쌍의 PSD 센서 시스템, 3축 자이로스코프, 1차원 라이다를 사용한다. 수치 시뮬레이션을 통해 우선적으로 상대 항법 알고리즘을 검증한 뒤 이를 기반으로 지상 시험 환경을 구축하였다. 지상 시험 환경으로부터 획득된 실제 센서 데이터를 상대 항법 알고리즘에 입력하여 최종적인 검증을 수행하였다. 또한 실제 측정치를 이용한 상대 항법 수행 결과를 바탕으로 현재 운용 중인 시스템과의 비교를 통해 적용 가능성 및 한계를 확인하였다. 추가적으로 장거리 시뮬레이션을 수행하여 동종 센서 시스템 및 이종 센서 시스템에 대한 오차 분석을 통해 장단점을 파악하였다. 두 시스템이 상호보완적으로 작용할 수 있는 통합 센서 융합을 수행하여 최종적인 결과를 도출하였다.