On-Site Corrosion Behavior of Water-Treated Boiler Tube Steel

Seo, Junghwa,Choi, Mihwa,He, Yinsheng,Yang, Seok-Ran,Lee, Je-Hyun,Shin, Keesam Korean Society of Microscopy 2015 Applied microscopy Vol.20 No.1

The boiler tubes of X20CrMoV12.1 used in fossil-fired power plants were obtained and analyzed for the effect of water treatment on the steam corrosion-induced oxide scale in an effort to better understand the oxide formation mechanism, as well as pertinent method of maintenance and lifetime extension. The specimens were analyzed using various microscopy and microanalysis techniques, with focuses on the effect of water treatment on the characters of scale. X-ray diffraction analysis showed that the scales of specimens were composed of hematite ($Fe_2O_3$), magnetite ($Fe_3O_4$), and chromite ($FeCr_2O_4$). Electron backscatter diffraction analysis showed that the oxides were present in the following order on the matrix: outer $Fe_2O_3$, intermediate $Fe_3O_4$, and inner $FeCr_2O_4$. After all volatile treatment or oxygenated treatment, a dense protective $Fe_2O_3$ layer was formed on the $Fe_3O_4$ layer of the specimen, retarding further progression of corrosion.

O-GlcNAc Modification of MAVS Regulates Antiviral Signaling by Modulating Its Activity

Junghwa Seo,Tae Hyun Kweon,Jingu Kang,Seonjin Son,Jinju Song,Won Ho Yang,Jin Won Cho 한국당과학회 2021 한국당과학회 학술대회 Vol.2021 No.01

Post-translational modifications, including O-GlcNAcylation, play fundamental roles in modulating cellular events, including transcription, signal transduction, and immune signaling. Several molecular targets of O-GlcNAcylation associated with pathogen-induced innate immune responses have been identified; however, the direct regulatory mechanisms linking O-GlcNAcylation with antiviral RIG-I-like receptor signaling are not fully understood. In this study, we found that cellular levels of O-GlcNAcylation decline in response to infection with Sendai virus. We identified a heavily O-GlcNAcylated serine-rich region between amino acids 249–257 of the mitochondrial antiviral signaling protein (MAVS); modification at this site disrupts MAVS aggregation and prevents MAVS-mediated activation and signaling. O-GlcNAcylation of the serine-rich region of MAVS also suppresses its interaction with TRAF3; this prevents IRF3 activation and production of interferon-β. Taken together, these results suggest that O-GlcNAcylation of MAVS may be a master regulatory event that promotes host defense against RNA viruses.

Role of O-GlcNAcylation of RIP3 kinase in Necroptotic cell death

Junghwa Seo,HanByeol Kim,Jin won Cho 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01

Cell death which is very important in mammals, is orchestrated by two types of death signaling: the Apoptosis (Programmed cell death) and Necroptosis (Programmed necrosis). Apoptosis and Necroptosis share common proteins such as FADD, Caspase-8 and RIP1 kinase in their molecular mechanism. However, only Necroptosis includes RIP3 Kinase dependent signaling. Therefore, RIP3 Kinase is a key determinator of necroptotic cell death. RIP3 kinase which is most important protein in necroptosis is strongly down-regulated their expression in most cancer cell. It's known that DNMT1 (DNA methyltransferase 1) plays an important roles in this process. RIP3 promoter is methylated by DNMT1 in most cancer cell. On the other hand, O-GlcNAc modification is a single sugar modification occurs in cytosol and nucleus. This modification has many roles in cellular responses including nutrient sensing. Here, we identified that cellular global O-GlcNAcylation change affects to RIP3 kinase expression by real time RT-PCR. In cancer HeLa and HepG2, mRNA level of RIP3 kinase is largely increase when OGA inhibitor Thiamet-G was treated. We also confirm that OGA inhibitor Thiamet-G induced the increase of endogenouse RIP3 kinase protein level in HEK293 and HeLa cell by Western blotting. And we will confirm the O-GlcNAcylation of RIP3 kinase using immunoprecipitation and succinylated wheat germ agglutinin (sWGA) precipitation. Ultimately we aim to find the physiological functions of cellular O-GlcNAcylation change in RIP3-mediated necroptosis.

Cell fate determination through regulation of protein O-GlcNAcylation in pathogen infections

Junghwa Seo,Won Ho Yang,Jin Won Cho 한국당과학회 2022 한국당과학회 학술대회 Vol.2022 No.07

Post-translational modifications, including O-GlcNAcylation, play fundamental roles in modulating cellular events, including transcription, signal transduction, and immune signaling. O-GlcNAcylation is PTMs on proteins that rapidly respond to extracellular stimuli. Although several molecular targets of O-GlcNAcylation associated with pathogen-induced innate immune responses have been reported, it is poorly understood how a host modulates intracellular O-GlcNAcylation to optimize pathogen-induced innate immune response and necroptotic cell death. Here we show that RNA virus infection or gram-negative bacterial infection induces a decrease in O-GlcNAcylation levels in several types of cells. Especially, we show that epithelial cells reduce OGT expression during the late phases of Sendai virus infection via RIG-I-like receptor activation. Downregulation of OGT expression led to a decrease in O-GlcNAcylation of MAVS during RNA virus infection. Moreover, we identified a heavily O-GlcNAcylated serine-rich region between amino acids 249-257 of the mitochondrial antiviral signaling protein (MAVS) and that it inhibits the formation of MAVS aggregates which are crucial for activating MAVS. O-GlcNAcylation of the serine-rich region of MAVS also suppresses its interaction with TRAF3; this prevents IRF3 activation and production of interferon-β. On the other hand, host cells suffer from sepsis, a serious inflammatory disease in response to pathogenic infection with Escherichia coli or staphylococcus. In this study, we demonstrate that O-GlcNAcylation suppresses sepsis-induced blood cell dysfunction. Moreover, we observe that the host accelerates its own immune response by reducing cellular O-GlcNAcylation in order to fight pathogen infections. Taken together, we suggest that it is essential to maintain host O-GlcNAc homeostasis in order to avoid excessive or abnormal immune responses.

온톨로지 기반 개인 미디어 메타데이터 자동 생성

최정화(Junghwa Choi),서희철(HeeCheol Seo),박영택(Youngtack Park) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.2B

개인 디지털 콘텐츠 증가에 따른 개인 미디어의 관리를 위해 대량의 메타데이터를 자동으로 생성하는 연구가 반드시 필요하다. 본 논문에서는 온톨로지 기반의 추론을 이용하여 개인 미디어 메타데이터를 자동으로 생성하는 방법을 제안한다. 제안한 방법은 부족한 정보로부터 적합한 의미를 추출하여 메타데이터를 자동 생성하므로 콘텐츠관리의 어려운 문제점을 해결한다. 본 논문에서 제안하는 방법을 사용자가 메모를 부착하기만 하면, 온톨로지 기반 추론을 통해 메타데이터를 자동 생성하는 방법으로 다음과 같은 세가지 기술과 특징을 갖는다. 첫째, 개인 미디어 온톨로지를 정의한다. 둘째, 미디어 메타데이터 표준을 정의한다. 미디어의 종류가 다르더라도 정의한 표준의 키워드만 추출할 수 있다면 미디어의 통합관리가 가능하다. 셋째, 메타데이터 자동 생성 기술을 연구한다. 단순히 온톨로지에 정의된 키워드의 의미만을 보지 않고, 온톨로지 기반의 추론엔진을 이용하여 사용자를 중심으로 관련 키워드의 관계를 고려한 메타데이터 생성의 정확성을 높인다. 이러한 기술을 기반으로 시맨틱 검색도 가능하며, 기존의 메타데이터 저작도구와 비교하여 보다 정확한 메타데이터 자동생성과 검색이 가능하다.

‘지방’정치학 확립을 위한 시론

황정화(Junghwa Hwang),김현준(Kim Hyeon Jun),서정민(Seo Jungmin) 21세기정치학회 2014 21세기 정치학회보 Vol.24 No.2

In spite of increasing academic works of local self-governance in South Korea, 'local' space has been insufficiently explored by political scientists, while leaving much of discussions to scholars of public administration, sociology and anthropology. This preliminary study aims to evaluate current status of research on local politics in Korea through examinations of articles published in Korean Political Science Review and the 21st Century Political Science Review for the last fourteen years. We found that topics of existing research on local self governance have excessively inclined to problem solving methods, conceptual demarcation between locality and state, normative attitude, predominant interests in local political institutions and non-contextualized analyses on regionalism. Instead, authors suggest that research on local self-governance should be expanded toward contextualizing locality in the overall changes of the nature of state, while being attentive to changing state's strategy to maintain its governmentality in the post-developmentalist era.

용인 독바위 줄다리기 연구

송미숙 ( Misook Song ),서정화 ( Junghwa Seo ) 아시아문화학술원 2019 인문사회 21 Vol.10 No.3

본 연구는 용인 민속축제의 활성화를 위해 독바위 줄다리기 중심으로 연구하였으며, 독바위 줄다리기의 실제 및 현황을 검토하는데 그 목적이 있다. 연구방법은 용인문화재단 문헌자료, 보존회 회장 인터뷰자료, 영상자료, 용인시청 자료집, 신문자료, 서적 등을 통한 문헌연구기법을 사용하였으며, 연구의 결과는 다음과 같다. 첫째, 마을의 질병이나 흉사에 줄다리기가 사용되었으며, 마을 공동체의 단합과 화합을 하는 데에도 그 역할이 있는 것을 알 수 있다. 둘째, 독바위 줄다리기의 특색으로는 다른 지역은 줄을 당산나무에 감거나 잘라서 바다에 뿌리는데 독바위 줄다리기에서는 줄을 불에 태움으로서 차별성을 갖는다. 셋째, 독바위 줄다리기는 1990년대 중반 이후 전승활동 및 민속축제가 이루어지지 못하였으나 광교 신도시 개발사업 추진 시 백만인 서명 운동을 전개하여 전수관과 역사공원을 건립할 수 있었다. 추후 독바위 줄다리기의 민속적 가치 등 후속연구가 계속 이루어지길 바란다. The purpose of this study, which focuses on Dokbawi Tug-of-war for the vitalization of folk festivals in Yongin, is to examine the actual condition and current state of Dokbawi Tug-of-war. This study, based on the review of literature including literature data from Yongin Cultural Foundation, an interview with the president of the association for conservation, visuals, Yongin City sourcebook, newspapers, publications, etc., found the following: First, the tug-of-war has not only been used when a disease or misfortune occurs in a village, but also played a role for the unity and harmony of the village. Second, how a rope is disposed of features Dokbawi Tug-of-war. A rope is generally coiled around the guardian tree of a village or scattered in the sea in other regions, while the rope used for Dokbawi Tug-of-war is burned, which differentiates itself from others. Third, though there had been no traditional activities or folk festivals for Dokbawi Tug-of-war since the mid of 1990s, a million's signature campaign at the time of Gwanggyo New Town Development Project led to the establishment of the transmission hall and the history park be builded. It is hoped that follow-up studies on the traditional values of Dokbawi Tug-of-war as well as further could be carried out.

베어링 선정이 소형 고속전동기의 회전체 동역학적 성능 설계에 미치는 영향

문형욱(HyeongWook Mun),서정화(JungHwa Seo),김태호(TaeHo Kim) 한국트라이볼로지학회 2019 한국트라이볼로지학회 학술대회 Vol.2019 No.10

볼 베어링 및 가스 포일 베어링으로 지지되는 고속 전동기의 회전체 관성정지 및 가속 성능 연구

문형욱(HyeongWook Mun),서정화(JungHwa Seo),김태호(TaeHo Kim) 한국트라이볼로지학회 2019 한국윤활학회지(윤활학회지) Vol.35 No.2

This study characterizes the coastdown performances of two small electric motors supported on high-speed ball bearings (BBs) and gas foil bearings (GFBs), and it predicts their acceleration performances. The two motors have identical permanent magnetic rotors and mating stators. However, the shaft of the GFBs has a larger mass and polar/transverse moments of inertia than that of the BBs. Motor coastdown tests demonstrate that the rotor speed decreases linearly with the BBs and nonlinearly with the GFBs. A simple model for the BBs predicts a constant drag torque and linear decay of speed with time. The test data validate the model predictions. For the GFBs, the hydrodynamic lubrication model predictions reveal that the drag torque increases linearly with speed, and the speed decreases exponentially with time. The predictions agree very well with the test data in the speed range of 100–30 krpm. The boundary lubrication model predicts a constant drag torque and linear decay of speed with time. The predictions agree well with the test data below 15 krpm. Mixed lubrication occurs in the speed range of 30–15 krpm. Rotor acceleration performances are predicted based on the characteristics of deceleration performances. The GFBs require more time to reach 100,000 krpm than the BBs because of their larger shaft polar moment of inertia. However, predictions for the assumed identical polar moment of inertia reveal that the GFBs have a nearly identical acceleration performance to that of the BBs with a motor torque greater than 0.03 N·m.

The Antecedents and Consequences of Effective Brand Positioning

Changju Kim,Eunji Seo,Junghwa Hong,Sangmin Kang,Stephen J. Newell 한국마케팅학회 2015 ASIA MARKETING JOURNAL Vol.17 No.3

This study investigates which variables most effectively influence the positioning strategy of a brand. In addition, we test the connection between the positioning strategy of the brand and loyalty. Finally, we explore how brand experience effects the relationship between brand position and brand loyalty. To this end, this study employs the street-intercept method to collect data on consumers’ perception of home appliances in Japan and conducts structural equation modeling analysis to test our hypotheses. Specifically, we find that assessments of product, service, and image have a significant impact on a brand’s position which, in turn, drives brand loyalty. In addition, brand experience seems to moderate the relationship between service and brand positioning effectiveness. We also find that price promotions negatively affect brand loyalty. The research provides a consumer-centered, experiential view of how firms can develop strategies to more effectively position brands and increase loyalty among their customers. These results help both academics and practitioners to better understand how consumers assess a brand’s position in the marketplace.