다변량 경시적 자료에서 공분산 행렬의 AR구조와 ARMA구조의 비교

윤단비(Danbi Yun),이근백(Keunbaik Lee) 한국데이터정보과학회 2020 한국데이터정보과학회지 Vol.31 No.5

다변량 경시적 자료에서 반복 측정된 자료들 사이에는 응답변수들 간의 세 가지 형태의 상관관계가 존재한다: 다른 시점에서 다른 반응변수들 간의 상관관계, 다른 시점에서의 동일한 반응변수들 간의 상관관계, 그리고 같은 시점에서의 반응변수들 간의 상관관계. 따라서 다변량 경시적 자료분석에서는 이러한 상관관계들을 모두 가지는 공분산행렬을 고려하여 모형화하는 것이 중요하다. 하지만 이러한 공분산행렬은 양정치성 (positive definiteness)을 만족해야 하고, 때로는 이분산성 (heteroge-neous)을 가질 수 있다. 또한 반복 측정 횟수가 증가함에 따라 공분산행렬의 모수의 수는 기하급수적으로 증가하여 추정하기가 쉽지 않다. 이 어려움들을 해결하기 위해 자기회귀 (autoregressive) 구조, 자기회귀-이동평균 (autoregressive-moving average) 구조를 가지는 공분산 행렬의 모형화 방법이 제안되었다. Lee 등 (2020)과 Lee 등 (2019)은 다변량 경시적 자료분석에서 각각 자기회귀 구조와 자기회귀-이동평균 구조의 공분산 행렬을 분해방법을 제안하였고, 또한 이러한 분석방법으로 추정된 공분산행렬은 항상 양정치성을 만족하고, 이분산성을 가질 수 있다. 본 논문에서는 이 두 방법을 모의실험을 통하여 서로 비교하고자 한다. In multivariate longitudinal data, there are three correlations: correlation within separate responses over time, cross-correlation between response at different times, and correlation between responses at each time point. Therefore, it is important to model the covariance matrix with the correlations. However, the covariance matrix for multivariate longitudinal data must be positive definite and the number of parameters in the covariance matrix increases exponentially as dimension increases. In order to solve the difficulties, the modeling of the covariance matrix with an autoregressive (AR) structure and an autoregressive moving average (ARMA) structure are proposed. Lee et al. (2020) proposed decomposition method assuming covariance matrix with autoregressive structure in multivariate longitudinal data analysis. Lee et al. (2019) extended Lee et al.’s (2020) method to accommodate long series of multivariate longitudinal data using autoregressive-moving average covariance matrix. In this paper, we compare these two methods through simulations.

Budd-Chiari syndrome with antiphospholipid syndrome and systemic lupus erythematosus in a patient with Klinefelter's syndrome

Lee, Mingee,Huh, Jin-Young,Lee, Ji-Hyang,Kang, Sun-myoung,Lee, Jae-Yong,Kwon, Oh-Chan,Kim, Eun Na,Kim, Jihun,Lee, Danbi Yeungnam University College of Medicine 2017 Yeungnam University Journal of Medicine Vol.34 No.2

Klinefelter's syndrome is the most common congenital abnormality that causes primary hypogonadism. It is associated with diseases that predominantly affect women, such as systemic lupus erythematosus (SLE), and it can sometimes cause veno-occlusive disease. We experienced a case of Budd-Chiari syndrome (BCS) in a 33-year-old man with Klinefelter's syndrome presented with hematemesis and edema in both lower extremities. The clinical and laboratory findings were compatible with SLE, antiphospholipid syndrome, and BCS. To the best of our knowledge, this is the first case report to describe a simultaneous presentation of these four clinical syndromes in a single patient.

Comparison of surgical resection versus transarterial chemoembolization with additional radiation therapy in patients with hepatocellular carcinoma with portal vein invasion

Danbi Lee,Han Chu Lee,Jihyun An,Ju Hyun Shim,Kang Mo Kim,Young-Suk Lim,Young-Hwa Chung,Yung Sang Lee 대한간학회 2018 Clinical and Molecular Hepatology(대한간학회지) Vol.24 No.2

Background/Aims: Portal vein invasion (PVI) is a poor prognostic factor in patients with hepatocellular carcinoma (HCC). We intended to compare the effects of surgical resection and transarterial chemoembolization (TACE) with additional radiation therapy (RT) in HCC patients with PVI. Methods: The subjects comprised 43 patients who underwent surgical resection for HCC with PVI without previous treatment and another 43 patients who received TACE followed by RT (TACE+RT) as initial treatment who were matched for Child-Pugh class, tumor size, and extent of PVI. Disease progression and death after the treatment were examined, and progression-free survival (PFS) and overall survival (OS) were compared between groups. Predisposing factors affecting OS were analyzed using univariate and multivariate analyses in HCC patients with PVI. Results: The subjects (Age [51, 24-74; median, range], Sex [81/13; male/female], Etiology [78/1/15; hepatitis B virus {HBV}/ hepatitis C virus {HCV}/non-HBV and non-HCV]) were followed for a median of 17 (2-68) months. There were no differences in clinical or tumor characteristics between the resection and TACE+RT groups. The cumulative PFS was not significantly different between groups. The median PFS was 5.6 and 4.0 months in the resection and TACE+RT groups, respectively. However, the cumulative OS was significantly longer in patients treated with resection than in those treated with TACE+RT (P=0.04). The median OS was 26.9 and 14.2 months in the resection and TACE+RT groups, respectively. Univariate and multivariate analyses revealed that surgical resection was an independent predictive factor for better survival outcome. Conclusions: Surgical resection might be an effective treatment in HCC patients with PVI.

Budd-Chiari syndrome with antiphospholipid syndrome and systemic lupus erythematosus in a patient with Klinefelter’s syndrome

( Mingee Lee ),( Jin-young Huh ),( Ji-hyang Lee ),( Sun-myoung Kang ),( Jae-yong Lee ),( Oh-chan Kwon ),( Eun Na Kim ),( Jihun Kim ),( Danbi Lee ) 영남대학교 의과대학 2017 Yeungnam University Journal of Medicine Vol.34 No.2

Klinefelter’s syndrome is the most common congenital abnormality that causes primary hypogonadism. It is associated with diseases that predominantly affect women, such as systemic lupus erythematosus (SLE), and it can sometimes cause veno-occlusive disease. We experienced a case of Budd-Chiari syndrome (BCS) in a 33-year-old man with Klinefelter’s syndrome presented with hematemesis and edema in both lower extremities. The clinical and laboratory findings were compatible with SLE, antiphospholipid syndrome, and BCS. To the best of our knowledge, this is the first case report to describe a simultaneous presentation of these four clinical syndromes in a single patient.

Clinical features and outcomes of patients with hepatocellular carcinoma complicated with bile duct invasion

( Jihyun An ),( Kwang Sun Lee ),( Kang Mo Kim ),( Do Hyun Park ),( Sang Soo Lee ),( Danbi Lee ),( Ju Hyun Shim ),( Young-suk Lim ),( Han Chu Lee ),( Young-hwa Chung ),( Yung Sang Lee ) 대한간학회 2017 Clinical and Molecular Hepatology(대한간학회지) Vol.23 No.2

Background/Aims: Little is known about the treatment or outcomes of hepatocellular carcinoma (HCC) complicated with bile duct invasion. Methods: A total of 247 consecutive HCC patients with bile duct invasion at initial diagnosis were retrospectively included. Results: The majority of patients had Barcelona Clinic Liver Cancer (BCLC) stage C HCC (66.8%). Portal vein tumor thrombosis was present in 166 (67.2%) patients. Median survival was 4.1 months. Various modalities of treatment were initially employed including surgical resection (10.9%), repeated transarterial chemoembolization (TACE) (42.5%), and conservative management (42.9%). Among the patients with obstructive jaundice (n=88), successful biliary drainage was associated with better overall survival rate. Among the patients with BCLC stage C, overall survival differed depending on the initial treatment for HCC; surgical resection, TACE, systemic chemotherapy, and conservative management showed overall survival rates of 11.5, 6.0 ,2.4, and 1.6 months, respectively. After adjusting for confounders, surgical resection and repeated TACE were significant prognostic factors for HCC patients with bile duct invasion (hazard ratios 0.47 and 0.39, Ps <0.001, respectively). Conclusions: The survival of HCC patients with bile duct invasion at initial diagnosis is generally poor. However, aggressive treatments for HCC such as resection or biliary drainage may be beneficial therapeutic options for patients with preserved liver function. (Clin Mol Hepatol 2017;23:160-169)

ARD1/NAA10 in hepatocellular carcinoma: pathways and clinical implications

Danbi Lee,장명국,서지혜,류수형,Jeong A. Kim,정영화 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Hepatocellular carcinoma (HCC), a representative example of a malignancy with a poor prognosis, is characterized by high mortality because it is typically in an advanced stage at diagnosis and leaves very little hepatic functional reserve. Despite advances in medical and surgical techniques, there is no omnipotent tool that can diagnose HCC early and then cure it medically or surgically. Several recent studies have shown that a variety of pathways are involved in the development, growth, and even metastasis of HCC. Among a variety of cytokines or molecules, some investigators have suggested that arrest-defective 1 (ARD1), an acetyltransferase, plays a key role in the development of malignancies. Although ARD1 is thought to be centrally involved in the cell cycle, cell migration, apoptosis, differentiation, and proliferation, the role of ARD1 and its potential mechanistic involvement in HCC remain unclear. Here, we review the present literature on ARD1. First, we provide an overview of the essential structure, functions, and molecular mechanisms or pathways of ARD1 in HCC. Next, we discuss potential clinical implications and perspectives. We hope that, by providing new insights into ARD1, this review will help to guide the next steps in the development of markers for the early detection and prognosis of HCC.

Biotechnological Production of Dimethoxyflavonoids Using a Fusion Flavonoid <i>O</i>-Methyltransferase Possessing Both 3′- and 7-<i>O</i>-Methyltransferase Activities

Lee, Danbi,Park, Hye Lin,Lee, Sang-Won,Bhoo, Seong Hee,Cho, Man-Ho American Society of Pharmacognosy 2017 Journal of natural products Vol.80 No.5

<P>Although they are less abundant in nature, methoxyflavonoids have distinct physicochemical and pharmacological properties compared to common nonmethylated flavonoids. Thus, enzymatic conversion and biotransformation using genetically engineered microorganisms of flavonoids have been attempted for the efficient production of methoxyflavonoids. Because of their regiospecificity, more than two flavonoid O-methyltransferases (FOMTs) and enzyme reactions are required to biosynthesize di(or poly)methoxyflavonoids. For the one-step biotechnological production of bioactive di-O-methylflavonoids, we generated a multifunctional FOMT fusing a 3'-OMT (SIOMT3) and a 7-OMT (OsNOMT). The SlOMT3/OsNOMT fusion enzyme possessed both 3'- and 7-OMT activities to diverse flavonoid substrates, which were comparable to those of individual SlOMT3 and OsNOMT. The SlOMT3/OsNOMT enzyme also showed 3'- and 7-OMT activity for 7- or 3'-O-methylflavonoids, respectively, suggesting that the fusion enzyme can sequentially methylate flavonoids into di-O-methylflavonoids. The biotransformation of the flavonoids quercetin, luteolin, eriodictyol, and taxifolin using SlOMT3/OsNOMT-transformed Escherichia coli generated corresponding di-O-methylflavonoids, rhamnazin, velutin, 3',7-di-O-rnethyleriodictyol, and 3',7-di-O-methyltaxifolin, respectively. These results indicate that dimethoxyflavonoids may be efficiently produced from nonmethylated flavonoid precursors through a one-step biotransformation using the engineered E. coli harboring the SlOMT3/OsNOMT fusion gene.</P>

Abrupt changes in Net Primary Production

Danbi Lee,So-Won Park,Yechul Shin,Jong-Seong Kug 한국기상학회 2023 한국기상학회 학술대회 논문집 Vol.2023 No.4

Hypostatic instability of aluminum anode in acidic ionic liquid for aluminum-ion battery

Lee, Danbi,Lee, Gibaek,Tak, Yongsug IOP 2018 Nanotechnology Vol.29 No.36

<P>Aluminum-ion batteries are considered to be a promising post lithium-ion battery system in energy storage devices because aluminum is earth-abundant, has a high theoretical capacity, and is of low cost. We report on the chemical activities and stabilities of chloroaluminate anions [Al<I> <SUB>n</SUB> </I>Cl<SUB> <I>n</I>+1</SUB>]<SUP>−</SUP> with aluminum metal using a different mole ratio of AlCl<SUB>3</SUB> and 1-ethyl-3-methylimidazolium chloride. The morphological changes in the Al metal surface are investigated as a function of dipping time in electrolyte, revealing that the Al metal surface is locally attacked by chloroaluminate anions followed by the formation of a new Al oxide layer with a specific lattice plane and a craterlike surface around the cracking site. The aluminum-ion battery exhibits outstanding cycle life and capacity even at the high C-rate of 3 A g<SUP>−1</SUP>, with a high energy efficiency of 98%, regardless of the differences in the size of chloroaluminate anions.</P>

Exchange-Coupling Interaction in Zero- and One-Dimensional Sm₂Co₁₇/FeCo Core-Shell Nanomagnets

Lee, Jimin,Kim, Jiwon,Kim, Danbi,Lee, Gyutae,Oh, Yeong-Been,Hwang, Tae-Yeon,Lim, Jae-Hong,Cho, Hong-Baek,Kim, Jongryoul,Choa, Yong-Ho American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.29

<P>Rare-earth-based core-shell spring nanomagnets have been intensively studied in the permanent magnet industry. However, the inherent agglomeration characteristics of zero-dimensional (0-D) magnetic nanoparticles are an issue in practical fabrication of magnetic nanocomposites due to deterioration in exchange-coupling interactions, resulting in inferior magnetic performance. Here, with an aim to overcome the structural limitations, we report a new type of SmCo/FeCo core-shell nanomagnet with a well-dispersed one-dimensional (1-D) structure prepared by a combination of electrospinning and electroless plating processes. An FeCo layer with a tailored thickness on nanoscale SmCo was produced to achieve a sufficient exchange-coupling effect. The influence of electroless plating time on the microstructure of fibers was discussed, and comparisons were made as a function of the magnet shape. A 1-D SmCo/FeCo spring nanomagnet having a core diameter ranging from 150 to 200 nm and a shell thickness of 15-20 nm showed a potent exchange-coupling effect compared with its 0-D counterpart. This effectively reduced self-aggregation and further showed a remarkable enhancement in (<I>BH</I>)<SUB>max</SUB> (above 45.7%). We think that this novel structure marks a new era in the exchange-spring magnet industry and may overcome the limitations of traditional core-shell nanomagnets.</P> [FIG OMISSION]</BR>