http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Genetic analysis of PARK2 gene in Korean patients with Parkinson's disease
박인원 忠南大學校 新藥專門大學院 2016 국내박사
Mutations in PARK2 are considered a common cause of Parkinson’s disease (PD). To assess the frequency of PARK2 mutations in the Korean population, we screened the PARK2 gene in 83 Korean PD patients: two young onset (YO, ≤49), 32 middle onset (MO, 50-69) and 49 late onset (LO, 70). Detection of the point mutations was performed by direct sequencing of the PARK2 exons, and exonic rearrangements were analyzed using multiplex ligation-dependent probe amplification (MLPA). Five known PARK2 variants were identified in 53 (63.9%) of the Korean PD patients: two missense mutations (Y267H and M458L) and three polymorphisms (S167N, L272I and V380L). We also found an increased frequency of PARK2 variants in PD patients and a lowered PD age at onset (AAO) in those having two variants, suggesting that the genetic variation in PARK2 gene might be a genetic risk factor of PD in Korean population.
공동주택 지하주차장 평면형태 및 환기구의 배치에 따른 공기유동에 관한 연구
The study on the airflow based on the array of ventilator and plan of the underground parking lot in apartment As demands of the residents have been variously changing according to the construction of the apartment house and the fast economic growth, the construction companies spurs the development of the apartment house flavored with environmental friendly factors. Also because of the multiple apartment project, the basement car park alone can not handle the rapid growth of the vehicles and the resident puts more and more emphasis on securing car park space for the freedom from the vehicles on the ground and for the safety of their children. Recently, as the interest about natural energy, the tendency minimizing the mechanical energy also appears. According to this trend, there has been growing attempts in order to apply the environmental friendly technologies to the apartment house. But the reality is that the systems doesn't virtually function well because the existing mechanical systems are applied. Consequently, the deterioration of the air and the brightness in the basement car park exacerbates the environments of the basement car park. And the study on the feasibility of the natural ventilation according to the unit-plan type of the basement car park and the performance of the skylight, is still insignificant. Thus, in this study, we intend to simulate, through the CFD, the air current by natural driving power by classifying the existing basement car parks into the unit-plan type and the direction of the vehicle traffic. Through classifying the existing basement car parks by the type of vehicle traffic that is the type of arrangement such as one-way or bidirectional traffic and deploying the ventilating openings by 3 types which enables the skylights, linked the ground for the purpose of collecting the light, play the role of ventilation at the same time, we forecast the air current of the basement car park by using CFD(Computational Fluids Dynamics) and, based on that, suggest the plan to improve the ventilating function of the basement car park by utilizing the natural ventilation. In this study, we research the general theories, that is 'the ventilation theory of underground space and the test method of ventilating performance' and interpret, through CFD, the air current of the target models according to the layout of the ventilation openings based on mean of air age and air exchange effectiveness by using computer simulation. As a result, we draw the conclusion as follows: (1) In respect of the air age according to the type of the vehicle traffic such as one way traffic and bidirectional traffic, the bidirectional traffic shows 30,405 seconds while 14,070 seconds in one way traffic indicating that the one way traffic abates by more than 50%. Therefore, the air of the basement car park with one way traffic has superior air quality because of its' shorter air age. (2) In case of the existing basement car parks, Case A' air exchange rate is 4.44 while 7.76 times/h in Case B and 1.94 times/h in Case C. It appears comparatively small in Case C. We can draw the conclusion, through this finding, that the placement of several natural ventilators in the middle and on the edge is more effective than the placement of the natural ventilator with big area in the middle when placing natural ventilator. (3) In case of Case B where the installation is in the middle and on the edge of the basement car park, it appears excellent in both the air exchange and the air age, but the effective area of the space on the ground abates. There requires a plan for the placement accordingly. (4) In case of Case C where the circular air-vent with the smallest area of air-vent is installed, the velocity of air current appears the fastest. Thus, it seems that there requires the research on the appropriate size and the layout plan of the circular air-vents for the purpose of the increase of effective space on the ground. It is also necessary to comprehend the appropriate locations in order to improve the performance of the natural ventilation, through examining the characteristic of the air current according to the type of ventilating openings installed in the basement car park, the velocity of the current, the pressure distribution and the installation of the auxiliary equipments for the natural ventilation.
Maulana, Firman 서울시립대학교 국제도시과학대학원 2018 국내석사
인도네시아에 설립된 가장 오래된 국립공원 중 하나인 구눙 게대 빵랑오 국립공원(GGPNP)은 관광 개발의 기초로 생태관광을 선택했다. 생태관광과 관련된 모든 혜택에 관계 없이 미래에 최적의 이익을 얻으려면 여전히 해결해야 할 과제가 있다. 정부기관으로서 GGPNP는 방문객에게 서비스를 제공하는 관광 활동을 지원하는 단순한 관리 이상의 또 다른 역할을 한다. 최근의 사실은 국립공원에 방문하는 관광객 수가 여전히 적다는 것을 보여주며 그 이유 중 하나는 국립공원에서 마케팅에 대한 관심이 낮기 때문이다. 국립공원은 또한 성과 중 하나인 방문 관광객 수에 대한 목표를 달성해야 하지만 GGPNP의 경영진은 서비스 마케팅을 시행하여 국립공원을 홍보하는 방법에 주목하기 시작해야 한다. 이러한 이유로 본 연구는 서비스 마케팅 관점에서 GGPNP가 서비스를 제공하는 방법을 조사하기 위해 실시되었다. 또한 이 논문은 생태관광 원리를 강조하는 경영진 측면과 인지된 서비스 성과 차원을 강조하는 방문객 관점에서 서비스 마케팅의 3가지 요소(인력, 물리적 증거, 프로세스 관리)를 탐구한다. 조사 결과에 따르면 GGPNP의 서비스 마케팅 구현은 전반적으로 중간 수준이다. 이는 GGPNP가 이미 표준 서비스 마케팅을 수행하지만 마케팅 가치를 높이기 위해 해결하고 개선해야 할 몇 가지 사항이 있다는 것을 의미한다. 인적 요소의 경우 GGPNP는 방문객에게 더 나은 서비스를 제공하기 위해 더 많은 인력을 충원하고 더 많은 교육을 제공해야 한다. 물리적 증거 요소의 경우 방문객은 GGPNP가 국립공원 지역에 머무는 동안 방문객에게 더 많은 지식과 편의를 제공하기 위해 국립공원 지역에 정보 표지판과 위생 시설을 개선하거나 추가해야 한다고 생각한다. 마지막으로, 프로세스 관리 요소에서 GGPNP는 더 많은 절차를 추가하고 고객 평가, 방문 우선순위 시민에 대한 대우(노인, 임산부, 장애인, 어린이), 방문객에게 피드백을 제공하는 방식에 대해 구체적인 사항을 추가해야 한다. GGPNP의 경영진에게 이 결과가 의미하는 바는 특히 인도네시아에서 국립공원의 서비스 마케팅에 대해 논의하는 이전 연구가 없었기 때문에 공식적인 계획 전략을 위한 마케팅 참조자료와 디딤돌을 제공하는 것이다. 또한 훌륭한 서비스 마케팅을 시행함으로써 장기적으로 국립공원을 방문하여 보존 메시지를 받고 환경에 대한 소속감을 높일 수 있는 사람들이 더 많아질 것이다. Gunung Gede Pangrango National Park (GGPNP) one of the oldest national parks established in Indonesia has chosen ecotourism as the basis of their strategy in developing tourism. Regardless of all of the benefits that come with ecotourism, there are challenges that are still need to be addressed to gain optimum benefit in the future. As a government agency, GGPNP has another role than just mere conservation which is supporting tourism activities which mainly about delivering a service to its visitors. The recent data shows that the number of tourist arrival to the national park is still low, and one of the reasons is the low interest of marketing for a national park. While the national park also needs to achieve the target for tourist arrival as one of their performance, the management of GGPNP needs to start their attention on how to market the national park through the implementation of service marketing. Due to these reasons, this research was conducted to examine how the GGPNP delivers their services from the perspective of services marketing. In particularly, this thesis explores the three elements of services marketing (personnel, physical evidence, and process management) from the perspective of management which emphasizes ecotourism principles and the perspective of visitor which emphasizes on perceived service performance dimension. The results of this survey show that as overall the implementation of service marketing in GGPNP is at a moderate level. This means that GGPNP already perform standard service marketing but there are several things that need to be addressed and improved to increase their marketing value. From the personnel element, the GGPNP need to consider adding more personnel and provide them with more training in order to deliver better services to the visitor. For the physical evidence element, the result also shows that the visitor thinks that GGPNP needs to improve or add more information signage and sanitary facilities in the national park area to give more knowledge and comfortability toward visitor during their stay in the area of national park. Lastly, from the process management element shown that GGPNP need to add more procedure and put more specific details on customer evaluation, treatment for priority citizen (elderly, pregnant woman, disabled person, and children) that come to visit, and how they provide their feedback to the visitor. This research is expected to serve as a stepping stone and reference on marketing and planning strategies of GGPNP since there was no previous research that discusses service marketing in the national park especially in Indonesia. Furthermore, by implementing good services marketing it is expected that for long-term outcome there will be more people to visit a national park to receive the message of conservation and hence increase their sense of belonging toward the environment.
First-Principles Characterization of Transition Metals on Oxide Films
Park, Jinwoo University of Seoul 2010 해외박사
Oxide-supported metal clusters and thin films have attracted a great deal of interest due to their importance in a wide range of technological applications, such as heterogeneous catalysis, gas sensors, corrosion-protective coatings, photovoltaic devices, and microelectronics. The adsorption, growth, and electronic characteristics of metal atoms adsorbed on oxides are of special interest, because these factors are supposed to help design and optimize methods for controlling processes concerning the desired chemical reaction and product. In this thesis, we performed ab initio electronic structure calculations to study the interactions of metal adatoms with ionic oxide atoms involving regular oxide surface atoms, surface oxygen defects like Fs centers, and metal supports. As an oxide, an MgO(001) surface, a prototype of an ionic oxide surface, was chosen here. All calculations were carried out using the density functional theory (DFT). First, a systematic approach was employed to investigate the adsorption geometries and electronic structures of late transition series (Cu, Ag, Au, Ni, Pd, and Pt) on ideal defect-free MgO(001) surfaces. For the above elements, the adsorption geometries, diffusion, and associated electronic structures were examined. Our calculations showed the favorable adsorption of the transition metal (TM) adatoms on top of the surface O atom. Further analysis showed that the TM-induced states formed in the gap region of MgO(001) vary significantly with the adsorption geometries. The DFT calculations have been also applied to investigate the adsorption of the TM adatoms (Cu, Ag, Au, Ni, Pd, and Pt) on defective MgO(001) surfaces with Fs centers as surface defects of oxides. The TM adatoms were found to favorably bind on the Fs centers. From the calculated adsorption structures and electronic structures, we carried out a systematic comparative analysis of the interactions of the metal adatoms with the surface oxygen vacancy and the regular surface oxygen atom of MgO(001). Finally, the adsorption of metal adatoms (Au and Pd) on Fe-supported ultrathin MgO(001) films was studied. Experimentally, it is well known that MgO films are epitaxially grown on Fe(001) due to their favorable physical properties. As such, the Fe/MgO/Fe junctions have been used as a system for magnetic tunnel junctions (MTJs) with huge tunneling-magnetoresistance (TMR) values. Interestingly, our calculations showed that the MgO/Fe(001) films we propose in this work can be used as a viable thin oxide model system. An analysis of the electronic structures in the systems reveals the negative charging even for Pd adatoms with a lower electron affinity. This indicates that the Fe substrate supporting the MgO films significantly influences charge and/or spin states of the metal adatoms. The physical origin of the negative charging of Pd was also discussed. These calculations demonstrate the importance of the interactions of the metal adatoms with underlying oxides for controlling the electronic and chemical properties of metal adatoms, such as charge and spin states.
North Korea's legal system and human rights
Park, Elisa Graduate School of International Studies, Yonsei U 2004 국내석사
In this study I will examine how the problem of human rights in North Korea runs deeper than the abuses themselves. The dilemma stems from North Korea's eschewed definition of human rights, and consequently, the political utility of it by the Kim Jong Il government to maintain unitary power. North Korea's definition of human rights is different, de jure and de facto from the universal definition, as outlined in the UN Declaration of Human Rights. I will be comparing international law with North Korean domestic law and practice. In examining domestic law there will be a focus on judicial proceedings, in particular due process. North Korea does, at least in rhetoric, attempt to follow international standards in order to avert criticism.In-depth studies, with respect to North Korean human rights violations covering prison camps, torture, execution, discriminatory ration distribution, and the refugee situation in China, have been carried out. However, these studies are based on political and sociological approaches. This study is unique because it narrows down on legal aspects of human rights violations in North Korea. It is necessary to see how the domestic legal system affects the human rights situation in North Korea. In order to understand, we must consider North Korea's view of international law and domestic law.Under international law, individuals have rights protecting their interests and survival. The International Covenant on Civil and Political Rights (ICCPR), of which the Democratic People's Republic of Korea (DPRK) is a member of, states the right of the individual in terms of various civil and political rights. Emphasized in the convention is the right to due process. Due process is defined as fairness in legal matters, including court proceedings that are guided by principles of justice and liberty. Substantive and procedural due process will be examined in application to the DPRK system. DPRK's violation of due process, a basic political right, diffuses its credibility and confidence as a state with whom other members of the international community can engage and trust. In particular, this study will examine infringement on due process as an indicator of other civil and political rights abuses and how it reflects the regime's attitude towards its people and its disregard for international laws. Domestic laws, their purpose and application will be inspected.The international trend for human rights is one of integration of values and progression of standard. The Declaration of Human Rights states that 'all human beings are born free and equal', 'free and equal in dignity', '(t)hey are endowed with reason and conscience', giving the individual 'free and equal personhood, equal dignity, equal creation and endowment, equal brotherhood, human agency' . Since the establishment of the High Commission of Human Rights, there has been an orchestration of efforts to establish a minimum standard and respect for the human spirit. In his Millenium Road Map Speech the role of the UN was redefined by the Secretary General, Kofi A. Annan . Two key points included freedom from want and freedom from fear. These are comprehensive rights that incorporate basic sustenance, social and political rights.Integration of values has been possible through the enmeshment of goals and pursuit by international organizations, NGO's and governments. Greater communication and cooperation has enabled this foundation of basic human rights. States that are party to international conventions and treaties are responsible for maintaining the standard and for ensuring accountability to other party members, so they strive for similar goals. Members have displayed a balance between taking steps to build up this standard while continuing to ensure that their national interests are met. Many of these members have come to an understanding that global interests often run parallel to national interests. The momentum towards greater integration and trust in the global system is evident in various areas, such as trade and aid.North Korea, as part of the UN and signatory to various international treaties and conventions is in a very particular situation. Even as a member to these organizations and treaties it regards international organizations and their members with a high level of suspicion. The doctrine of Juche, which acts as North Korea's guiding principle limits international effort in creating a working relationship with North Korea. The Juche ideology was created and developed by the founder of the North Korean system, Kim Il Sung. It is a concept centered in man's ability to shape his future through his own ability. The irony is that in its ideology North Korea exhorts self-reliance while in actuality it is growing more dependent on the international community for desperately needed aid.In examining the human rights abuses carried out through North Korea's penal system, violations surrounding prison camps will be explored in light of North Korean law and also a variety of laws that the international community upholds. Political human rights violations in North Korea are tantamount to crimes against humanity and the international community needs to be pro-active in finding a remedy that will end these arbitrary acts of injustice.Against the backdrop of international integration of values, North Korea faces a fork in the road. It will have to align its human rights standards to acceptable levels in order to continue to extract benefits from the international community. The alternative would be continual autarky and deterioration of its system. The international community must play an instigating role in pressuring North Korea to raise its human rights standards by imposing stricter conditions on aid.The issue of human rights abuses in North Korea has been pending for several years. It is a topic that cannot be examined in objectively verifiable detail due to its highly secretive government. The only sources of information come from non-governmental organizations and international organizations, which although restricted, are allowed to function in North Korean territory. Another source comes from the testimonies of defectors that have first hand experience of such abuses. The DPRK does not supply verifiable or refuting data on the inquiries made by international organizations or NGOs. Its defense thus far has been limited to basic denial of such accusations.Recent studies have reconfirmed the existence of gulags where thousands of prisoners are being held under conditions that drive the majority of them to illness and death. What is practiced in these prison-labor camps is clearly void of any regard for human rights, especially when the 'crimes' for which the accused were imprisoned for are disproportionate with how they are being castigated. As reported by human rights organizations, prisoners are often sentenced and executed extra-judicially. Under such conditions and practices North Korea is being pressured by the international community to make itself more transparent and to humanize its treatment of its citizens. North Korea denies such allegations and latches on sovereignty in dealing with its citizens. In doing so, North Korea excludes foreign governments and organizations from influencing its domestic policies. North Korea is in a quagmire because it realizes that it can no longer operate autonomously as its Juche ideology dictates.
Park, Jinil Sungkyunkwan university 2020 국내박사
Three-dimensional (3D) ultrashort echo-time (UTE) imaging with radial k-space acquisition is a wellknown MR imaging technique that generates comparable lung images to X-ray and computed tomography (CT), unlike conventional MR imaging technique. 3D radial UTE imaging technique is suitable for pulmonary magnetic resonance imaging because it is less sensitive to motion than conventional Cartesian MRI imaging techniques, but there is still a need to accomplish further reduction of motion artifacts through respiratory gating. The purpose of this study is to introduce a method for optimizing retrospective respiratory gating and to provide improved lung MRI. Acquiring stable breathing information is important for retrospective respiratory gating. Chapter 2 introduces a robust self-navigation method for respiratory gating in three-dimensional radial UTE lung imaging. The proposed new self-search method acquires the dual search echo successively in the direction of the superior-inferior and uses the second search echo for tracking respiratory movements. It is not influenced by k-space trajectory order, so that stable respiratory signal without baseline fluctuation can be obtained. The phantom and human experimental results showed that the proposed method successfully suppressed the baseline fluctuations of the navigating-echo signals and the resulting respiratory signals, thereby reducing the respiratory-motion artifacts like blurring in the human lung images thanks to the improved respiratory gating. In Chapter 3, we propose a 3D radial sampling strategy for maintaining uniform k-space coverage after retrospective respiratory gating by going through two steps. First, a multi-shot, interleaved sampling function is designed in a way that uniformly distributes k-space samples within each interleaf for a given number of views per interleaf. Second, an optimal number of views per interleaf is derived based on an approximate model of a respiratory pattern such that the retrospective acceptance of k-space data occurs evenly across the obtained interleaves. In conclusion, the proposed 3D radial-sampling scheme can effectively suppress the image artifacts due to non-uniform k-space sample density in retrospectively respiratory gated lung MRI by uniformly distributing gated radial views across the k-space. In addition, Chapter 4 proposes two methods to reduce streak artifacts in radial acquisition MRI. First, spectral preparation pulses were applied in UTE imaging technique to suppress fat signal increase due to short TR and short TE. Second, we suggested a method for acquiring volume-selected signals in 3D radial imaging, introducing a novel volume-selective 3D UTE sequence, termed volume-selective UTE (VS-UTE). Through this, the image quality can be improved by minimizing the streak artifact caused by under sampling in the 3D radial UTE imaging technique. In conclusion, the methods presented in this study can be used to obtain pulmonary magnetic resonance imaging stably under free breathing conditions and to reduce the scan time due to the reduction of streak artifacts in the images even under under-sampling. Therefore, it is expected that early diagnosis and continuous study will be possible in patients with lung disease. 방사형 k-공간 획득을 이용한 3차원 매우 짧은 에코 시간 (UTE) 이미징 기법은 기존의 자기공명영상 기법과 다르게 X-선 및 컴퓨터 단층 촬영(CT)과 비슷한 폐 이미지를 생성하는 잘 알려진 자기공명영상화 기법이다. 3차원 방사형 UTE 이미징 기법은 기존의 직교형 자기공명영상 기법 보다 움직임에 덜 민감하기 때문에 폐 자기공명영상에 적합하지만, 후향적 호흡 게이팅 (gating)을 통해 호흡 움직임으로 인한 아티팩트 (artifact)를 최소화 할 필요가 있다. 본 연구에서는 후향적 호흡 게이팅을 최적화 하기 위한 방법을 제시하고 이를 통하여 향상된 폐 자기공명영상을 제공하는 것을 목적으로 한다. 후향 호흡 게이팅을 위해서는 안정적인 호흡 정보를 획득하는 것이 중요하다. 2장에서는 3차원 방사형 UTE 폐 이미징에서 호흡 게이팅을 위한 안정적인 자체 탐색 (Self-navigation) 방법을 소개한다. 제안된 새로운 자체 탐색 방법은 이중 탐색 에코를 위-아래 (superior-inferior) 방향으로 연속적으로 획득하고 호흡 움직임 추적을 위해 두 번째 탐색 에코를 사용하는 것으로서 k-공간 궤적 순서에 영향을 받지 않아 베이스라인(baseline) 변동이 없는 안정적인 호흡신호를 얻을 수 있다. 3장에서는, 두 가지 단계를 거쳐서 후향 호흡 게이팅 후 균일한 k-공간 샘플 밀도를 유지할 수 있는 3차원 방사형 샘플링 전략을 제안한다. 인터리브 3차원 방사형 샘플링 기능은 각 인터리브가 k-공간을 일관되지 않은 방식으로 샘플링 하도록 궤적을 분할화 하여 설계한다. 그 다음, 인터리브 획득에 대한 최적의 분할 계수는 방사성 인터리브가 후향 게이팅 동안 균일하게 수용되도록 호흡 패턴의 대략적인 모델에 기초하여 도출되었다. 이 두 방법을 통해서, 네비게이션 에코 신호의 베이스라인 변동을 효과적으로 억제하여 정확한 호흡 정보로 개선된 호흡 게이팅을 가능하게 되었고 후향적 호흡 게이팅 후에 게이팅된 데이터가 k-공간에 균일하게 분배되어 비 균일 k-공간 샘플 밀도로 인해 발생하는 아티팩트를 효과적으로 억제 할 수 있었다. 추가적으로, 4장에서는 방사형 획득 MRI에서 줄무늬(streak) 아티팩트를 줄이기 위해 두 가지 방법을 제안한다. 먼저, UTE 영상화 기법에서 짧은 TR 및 짧은 TE로 인한 지방 신호 증가를 억제하기 위해 spectral preparation pulse가 적용 되었다. 두 번째, 3차원 방사형 영상화 기법에서 공간 선택 신호를 획득하는 방법으로 공간선택 UTE(VS-UTE)라고 하는 새로운 공간 선택 3차원 UTE 영상화 기법을 소개 한다. 이를 통해서 3차원 방사형 UTE 영상화 기법에서 언더 샘플링되어 발생하는 줄무늬 아티팩트를 최소화 시켜 영상의 질을 향상시킬 수 있었다. 결론적으로, 본 연구에서 제시한 방법들은 결합하면, 자유 호흡 상태에서 안정적으로 폐 자기공명영상 획득이 가능하게 되고 언더 샘플링에도 영상에서 줄무늬 아티팩트가 감소하게 되어 촬영시간이 단축시킬 수 있다. 따라서, 임상에서 폐 질환 환자를 대상으로 조기진단 및 지속적인 연구가 가능할 것으로 기대된다.
Park, Sulki Sungkyunkwan university 2019 국내박사
The lithium-ion based hybrid capacitors (LICs) have been already investigated to improve their performance and reveal in-depth charge storage mechanism for a long time. Relatively the advanced technologies based on LICs can be applied to the new energy storage system such as Na and Mg ions. In this paper, I have synthesized well-controlled layer structure of vanadium oxide to enhance charge storage capability. After that, I have assembled Na and Mg-ion based hybrid supercapacitors (SCs) using a synthesized vanadium oxide and carbon material as positive and negative electrode, respectively. In addition, I have studied in-depth correlation between structural evolution and electrochemistry during inserting of Na and Mg ions in vanadium oxide host. Firstly, Na-ion based hybrid capacitors (NICs) are proposed as one of the promising large-scale applications because Na is an abundant resource and NICs exhibit similar physical and chemical properties with that of LICs. The numerous identified electrode materials for LICs are limited to be used for NICs due to their non-flexible structure for inserting large Na ions. Among active materials, vanadium oxides have been extensively investigated as active material considering that their typical flexible layered structure could enable increasing theoretical capacity for Na system. In addition, vanadium oxides are characterized by various valence states, suitable voltage window and multifarious compounds, which can increase voltage window. Vanadium oxides have the different electrochemical reaction depending on electrolyte such as aqueous and organic system. However, an investigation of a systematic comparison between the organic and aqueous electrolyte in NICs is not yet employed or is in the primary stage. In this work, by taking advantage of specific potential window and flexible layer structure of vanadium oxide, the aqueous hybrid cell has been assembled using vanadium oxide and carbon material as positive and negative electrode, respectively. It has achieved high specific capacitance and fast ion diffusion with high voltage window compared to an organic system. In addition, aided by ex-situ XRD, XPS and temperature dependent impedance, I have investigated the correlation of electrochemistry and structural evolution followed by a two-electrolytes. Secondly, Mg-ion based hybrid capacitors (MICs) are prominent candidates considering that Mg is abundant source and relatively stable in air. But, MICs in organic system have remained many challenges due to low voltage window from overcharging and sluggish kinetic. Among various kinds of candidates for electrode materials, vanadium oxides were investigated for reversible Mg2+ intercalation due to flexible layer structure and the availability of variable valence state, showing the high voltage window for high electrochemical performance. In this work, I have demonstrated that as-synthesized vanadium oxides are the promising redox-active materials in Mg system. I have selected a hybrid capacitor configuration in aqueous electrolyte comprising of vanadium oxide as pseudocapacitive electrode and carbon as capacitive electrode, respectively. In addition, I have investigated an in-depth understanding of the structural evolution for redox reaction during Mg ion insertion with the electrochemistry in a vanadium oxide. Aided by in-situ XRD, ex-situ XRD, ex-situ XPS, X-ray Absorption near edge structure (XANES) and Fourier transform (FT) extended X-ray absorption fine structure (EXAFS), I have revealed the correlation between the structure and electrochemical reaction within vanadium oxide host in aqueous system.
FB-LDA : Efficient inference in full bayesian network of latent dirichlet allocation
Park, Hongju Graduate School, Yonsei University 2018 국내석사
잠재 디리슈레 할당 (Latent Dirichlet Allocation) 모델은 문서집합에서 주제를 추출하며 주제를 각각의 문서에 할당하는 데에 널리 사용되는 모델이다. 이 모델에서 활용된 접근법을 사용하면 용어-문서 행렬이 크기가 큰 희소행렬인 경우에도 문서집합을 용이하게 분석할 수 있다. 이 모델의 활용 빈도와 연구 규모에 비해 모델의 모수의 추정 방법이 충분히 개선되지 않았다. 기존의 LDA에서 모수를 추론하는 방법에는 2가지가 있는데, 첫 번째 방법은 variational EM algorithm을 이용한 방법이고 두 번째 방법은 붕괴 깁스 표집기를 이용한 방법이다. variational EM algorithm을 사용하는 방법은 불편 추정량을 보장하지 못하며 정확성이 떨어진다는 한계가 있다. 또한 붕괴 깁스 표집기를 이용한 방법은 hyperparameter를 상수로 가정하기 때문에 정확한 추론을 못할 가능성이 있다. 뿐만 아니라, hyperparameter를 단일한 것으로 가정하기 때문에 다양한 코퍼스 특성을 고려할 수 없다. 이 연구에서는 효율적이고 정밀한 MCMC 체계를 고안하기 위해 부분 붕괴 깁스 샘플러 (PCG)와 디리슈레 과정 (DP) 혼합분포를 이용하였다. 이 방법을 활용하면 불편 추정량을 보장할 수 있으며, 모든 코퍼스에 대해 유연한 모델링이 가능하다. Latent Dirichlet Allocation (LDA) is a popular model for finding topics and allocating them to documents or categorical group data. This approach allows for useful analysis of documents even when a term-document matrix is large and sparse. There have been not many extensions of its inference compared to the increasing number of uses and publications related to this method. There are two main ways to infer parameters in the LDA model, a variational inference and a collapsed Gibbs sampler. A defect of the method using variational inference is no guarantee of unbiased estimators. Also, a disadvantage of the method by the collapsed Gibbs sampler is that hyperparameters are assumed as constants which could result in bias estimators. Not only that, an unimodal assumption of Dirichlet distribution has the problem that the model cannot consider a various corpus property. In this research, by utilizing partially collapsed Gibbs sampling (PCG) and Dirichlet process (DP) mixture model to devise efficient and precise MCMC scheme, we can get the upgraded model which gives unbiased estimators and enables flexible modeling for any corpus.