하둡 시스템 정보의 이상탐지를 위한 시각화

양석우 ( Seokwoo Yang ),손시운 ( Siwoon Son ),길명선 ( Myeong-seon Gil ),문양세 ( Yang-sae Moon ),원희선 ( Hee-sun Won ) 한국정보처리학회 2015 한국정보처리학회 학술대회논문집 Vol.22 No.1

본 논문에서는 하둡 환경에서 시스템 정보의 이상탐지를 위한 시각화 기능을 설계 및 구현한다. 제안한 이상탐지 시각화 기능은 크게 세 단계로 구분된다. 먼저, 각 노드로부터 시스템 로그 데이터(캐시 및 메인 메모리)를 수집하여 하이브(Hive)에 저장한다. 그리고 저장한 데이터에 3-시그마 규칙을 적용하여 이상탐지를 수행한 후 관계형 데이터베이스에 적합하도록 재가공한다. 마지막으로, 스쿱(Sqoop)을 통해 RDBMS(MariaDB)에 이상탐지 결과를 저장하고, DHTMLX 차트 라이브러리를 사용하여 이를 시각화한다. 시각화 결과, 로그 데이터의 이상탐지와 데이터간의 상관관계를 직관적으로 이해할 수 있게 되었다.

InfiniBand RDMA 통신을 위한 Apache Storm의 재구성

양석우 ( Seokwoo Yang ),손시운 ( Siwoon Son ),문양세 ( Yang-sae Moon ) 한국정보처리학회 2018 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.7 No.8

본 논문에서는 분산 스트림 처리 프레임워크인 Apache Storm을 고성능 통신 장비인 InfiniBand에 적용하는 방안을 다룬다. InfiniBand 상에서 Storm을 동작시키는 쉬운 방법은 IPoIB (IP over InfiniBand)를 사용하는 것이다. 그러나 이 방법은 노드에 심각한 CPU 부하를 발생시키는데, 이는 잦은 문맥 전환과 버퍼 복사에서 기인하는 것으로 나타났다. 이를 해결하기 위해, Storm에서 InfiniBand의 RDMA (Remote Direct Memory Access) 기능을 사용하는 새로운 통신 방식을 제안한다. 첫째, Storm에서 RDMA 기능을 이용하기 위해, 기존 통신 프레임워크인 Netty를 대체하는 새로운 프레임워크인 RJ-Netty (RDMA/JXIO Netty)를 설계 및 구현한다. 둘째, Storm이 기존 Netty와 RJ-Netty를 모두 사용할 수 있도록 관련 클래스들을 개선한다. 셋째, RJ-Netty의 성능을 최대화하기 위해 멀티스레드를 지원하도록 JXIO 서버 기능을 개선한다. 실험 결과, 제안한 RJ-Netty는 Ethernet은 물론 IPoIB에 비해서 메시지 처리량을 향상시키면서도 CPU 부하를 크게 줄인 것으로 나타났다. 본 논문은 Apache Storm을 InfiniBand 상에서 동작시킨 최초의 시도로, 고성능의 InfiniBand RDMA를 사용하여 Storm의 처리 성능을 향상시킨 우수한 연구 결과라 사료된다. In this paper, we address how to apply Apache Storm, a distributed stream processing framework, to InfiniBand, a high performance communication device. An easy way to run Storm on InfiniBand is to simply use IPoIP (IP over InfiniBand). However, this method causes a serious CPU load on the node, which is caused by frequent context switches and buffer copies. To solve this problem, we propose a new communication method using InfiniBand's Remote Direct Memory Access (RDMA) function in Storm. First, we design and implement RJ-Netty (RDMA/JXIO Netty), a new framework that replaces Netty, the legacy framework, to exploit RDMA functionality. Second, we reimplement the related classes so that Storm can use both existing Netty and new RJ-Netty. Third, we extend the JXIO server functionality so as to support multi-threading to maximize the performance of RJ-Netty. Experimental results show that the proposed RJ-Netty significantly reduces CPU load while improving message throughput compared to IPoIB as well as Ethernet. This paper is the first attempt to run Apache Storm on InfiniBand, and we believe that it is an excellent research result that improves the performance of Storm by using InfiniBand RDMA.

Rider Scheduling In Last-mile Delivery: Incorporating The Fluctuating Demand And Show-up Rate Dynamics

Yuin Moon,Seokwoo Kim,Dong Gu Choi 대한산업공학회 2023 대한산업공학회 추계학술대회논문집 Vol.2023 No.11

InfiniBand RDMA 기반 Apache Storm의 네트워크 구조 설계

양석우 ( Seokwoo Yang ),손시운 ( Siwoon Son ),최성윤 ( Seong-yun Choi ),최미정 ( Mi-jung Choi ),문양세 ( Yang-sae Moon ) 한국정보처리학회 2017 한국정보처리학회 학술대회논문집 Vol.24 No.2

Apache Storm은 대용량 데이터 스트림을 처리하기 위한 실시간 분산 병렬 처리 프레임워크이며, 이를 사용해 다수의 프로세스 및 스레드를 동시에 동작시킬 수 있다. 하지만, 이러한 멀티 프로세스 및 스레드 환경을 제공하는 Storm은 많은 네트워크 시스템 호출을 수행하고, 이는 잦은 문맥 전환(context switch), 운영체제로의 버퍼 복사, 운영체제 내의 버퍼 복사 등으로 인해 CPU 과부하 문제를 발생시킬 수 있다. 이러한 문제는 고성능 네트워크 장비인 InfiniBand의 IPoIB(IP over InfiniBand) 통신을 사용할 때, InfiniBand가 지원하는 대역폭(bandwidth) 대비 저용량 데이터의 송수신으로 인해 더 잦은 문맥 전환과 버퍼 복사가 발생하여 CPU 과부하 문제가 더욱 심각해진다. 따라서, 본 논문에서는 InfiniBand의 RDMA(Remote Direct Memory Access)를 Storm에 적용하는 설계안을 제시함으로써 CPU 과부하 문제를 해결한다.

Compositional engineering of solution-processed BiVO₄ photoanodes toward highly efficient photoelectrochemical water oxidation

Byun, Segi,Jung, Gihun,Moon, Song-Yi,Kim, Bumsoo,Park, Jeong Young,Jeon, Seokwoo,Nam, Sung-Wook,Shin, Byungha Elsevier 2018 Nano energy Vol.43 No.-

<P><B>Abstract</B></P> <P>While BiVO<SUB>4</SUB> is a promising photoanode for solar-driven photoelectrochemical (PEC) water splitting, fine control of its chemical composition (Bi/V ratio) and modification of its electrical properties via extrinsic doping are necessary to improve its PEC performance. Here, we performed compositional engineering of BVO—varying Bi/V ratio and inclusion of different concentrations of Mo dopants. Through physical and chemical analyses, we found that the materials properties of BiVO<SUB>4</SUB> and its PEC performance were highly sensitive to the chemical composition. Our optimized BiVO<SUB>4</SUB>-based photoanode exhibited the highest photocurrent density among the state-of-the-art SnO<SUB>2</SUB>/BiVO<SUB>4</SUB> heterojunction photoanodes reported in the literature: 2.62 and 4.20mAcm<SUP>−2</SUP> measured at 1.23V vs. a reversible hydrogen electrode for the oxygen evolution reaction and sulfite oxidation reaction, respectively. A complete picture explaining various PEC performances with different chemical compositions via the band structure of BiVO<SUB>4</SUB> has emerged. This work points to the importance of specific control of the chemical composition in achieving highly efficient BiVO<SUB>4</SUB>-based photoanodes, which will guide future research directions in the fabrication of other high performance photoelectrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient SnO<SUB>2</SUB>/BiVO<SUB>4</SUB> photoanodes are achieved by engineering its composition. </LI> <LI> The material and PEC properties of BiVO<SUB>4</SUB> are affected by its chemical composition. </LI> <LI> The improved PEC performance is correlated with band alignments of SnO<SUB>2</SUB>/BiVO<SUB>4</SUB>. </LI> <LI> Our optimized sample exhibits superior performance in PEC water oxidation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Self-Assembly-InducedFormation of High-Density SiliconOxide Memristor Nanostructures on Graphene and Metal Electrodes

Park, Woon Ik,Yoon, Jong Moon,Park, Moonkyu,Lee, Jinsup,Kim, Sung Kyu,Jeong, Jae Won,Kim, Kyungho,Jeong, Hu Young,Jeon, Seokwoo,No, Kwang Soo,Lee, Jeong Yong,Jung, Yeon Sik American ChemicalSociety 2012 Nano letters Vol.12 No.3

<P>We report the direct formation of ordered memristor nanostructureson metal and graphene electrodes by a block copolymer self-assemblyprocess. Optimized surface functionalization provides stacking structuresof Si-containing block copolymer thin films to generate uniform memristordevice structures. Both the silicon oxide film and nanodot memristors,which were formed by the plasma oxidation of the self-assembled blockcopolymer thin films, presented unipolar switching behaviors withappropriate set and reset voltages for resistive memory applications.This approach offers a very convenient pathway to fabricate ultrahigh-densityresistive memory devices without relying on high-cost lithographyand pattern-transfer processes.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2012/nalefd.2012.12.issue-3/nl203597d/production/images/medium/nl-2011-03597d_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl203597d'>ACS Electronic Supporting Info</A></P>

Incidence and Course of Depression in Patients with Alzheimer’s Disease

SeungHo Ryu,HanYong Jung,KangJoon Lee,SeokWoo Moon,DongWoo Lee,Narei Hong,BaikSeok Kee,DoHoon Kim,Changsu Han,ChangUk Lee 대한신경정신의학회 2017 PSYCHIATRY INVESTIGATION Vol.14 No.3

Objective-Depressive symptoms are common in Alzheimer’s disease (AD) and they might influence the course and prognosis of AD. Depression could appear anytime in the course of the disease, and could either last considerably long or disappear easily. This study is intended to investigate the occurrence of depression in the course of AD and the risk factors of incidence. Methods-This study targeted 1,272 AD patients without depressive symptoms at the start of this study in Korea. A total of 775 subjects completed the study, and the occurrence of depression was assessed after 12 months. Demographic information of subjects was collected and cognitive functions, overall functions, and depression severity were assessed at the start of this study and after 12 months. Results-Among the 775 subjects, 103 subjects (13.29%) developed depression 12 months later. The MMSE-KC scores showed significant changes in both groups that developed depression and did not. In the univariate analysis, significant differences in the incidence of depression were found in terms of gender, the administration of the antidepressant at the baseline, the SGDS-K score, and the GDS score. The multiple logistic regression analysis showed that the increase in the incidence of depression was associated with a female, in the increase in SGDS-K score and the GDS score. Conclusion-The incidence of depression in the subjects who completed the 12-month follow-up observation was 13.29%. Moreover, in the multivariate analysis, a female gender and the severity of dementia, including the overall functions, seemed associated with the occurrence of depression.

Contrast-Induced Nephropathy After Computed Tomography in Stable CKD Patients With Proper Prophylaxis : 8-Year Experience of Outpatient Prophylaxis Program

Park, Sehoon,Kim, Myoung-Hee,Kang, Eunjeong,Park, Seokwoo,Jo, Hyung Ah.,Lee, Hajeong,Kim, Sun Moon.,Lee, Jung Pyo.,Oh, Kook-Hwan,Joo, Kwon Wook.,Kim, Yon Su.,Kim, Dong Ki. Wolters Kluwer Health 2016 Medicine Vol.95 No.18

<P><B>Abstract</B></P><P>Conflicting data have been reported on the clinical significance of contrast-induced nephropathy after CT scan (CT-CIN). In addition, the epidemiologic characteristics and clinical outcomes of CT-CIN following proper prophylactic intervention remain elusive.</P><P>We examined the incidence, risk factors, and outcomes of CT-CIN in stable chronic kidney disease (CKD) patients using data collected from our outpatient CT-CIN prophylaxis program conducted between 2007 and 2014. The program recruited patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m<SUP>2</SUP> using an electronic health record-based pop-up alert system and provided an identical protocol of CIN prophylaxis to all patients.</P><P>A total of 1666 subjects were included in this study, and 61 of the 1666 subjects (3.7%) developed CT-CIN. Multivariate analysis showed that baseline eGFR, diabetes mellitus, and low serum albumin were significant risk factors for CT-CIN. The generalized additive model analysis revealed a nonlinear relationship between the baseline eGFR and the risk of CT-CIN. In this analysis, the risk of CT-CIN began to increase below an eGFR threshold of 36.8 mL/min/1.73 m<SUP>2</SUP>. To assess the outcomes of CT-CIN, patients with and without CT-CIN were compared after propensity score-based 1:2 matching. CT-CIN did not increase the mortality rate of patients. However, patients with CT-CIN were significantly more likely to start dialysis within 6 months of follow-up, but not after those initial 6 months.</P><P>CT-CIN developed in only a small number of stable CKD patients who received proper prophylactic intervention, and the risk of CT-CIN was increased in patients with more advanced CKD. Despite the low incidence, CT-CIN conferred a non-negligible risk for the initiation of dialysis in the acute period, even after prophylaxis.</P>