Principal Component Regression by Principal Component Selection

Lee, Hosung,Park, Yun Mi,Lee, Seokho The Korean Statistical Society 2015 Communications for statistical applications and me Vol.22 No.2

We propose a selection procedure of principal components in principal component regression. Our method selects principal components using variable selection procedures instead of a small subset of major principal components in principal component regression. Our procedure consists of two steps to improve estimation and prediction. First, we reduce the number of principal components using the conventional principal component regression to yield the set of candidate principal components and then select principal components among the candidate set using sparse regression techniques. The performance of our proposals is demonstrated numerically and compared with the typical dimension reduction approaches (including principal component regression and partial least square regression) using synthetic and real datasets.

Die geistige Anastomose des Übersetzens – Über die Übersetzung des (kollektiven) Geistes um 1900 in Korea

Hosung Lee 한독문학번역연구소 2023 한독문학번역연구소 학술대회 Vol.2023 No.09

Tumor metastasis to lymph nodes requires YAP-dependent metabolic adaptation

Lee, Choong-kun,Jeong, Seung-hwan,Jang, Cholsoon,Bae, Hosung,Kim, Yoo Hyung,Park, Intae,Kim, Sang Kyum,Koh, Gou Young American Association for the Advancement of Scienc 2019 Science Vol.363 No.6427

<P><B>Fueling lymph node metastases</B></P><P>Metastatic cells can migrate from a primary tumor to distant organs through two routes: They can enter the bloodstream directly, or they can enter a lymph node adjacent to the primary tumor. Little is known about the biological mechanisms that allow tumor cells to survive and grow within lymph nodes. Studying mouse models, Lee <I>et al.</I> found that tumor cells adapt to the lymph node microenvironment by shifting their metabolism toward fatty acid oxidation. This occurs through activation of a signaling pathway driven by the yes-associated protein (YAP) transcription factor. Importantly, inhibition of fatty acid oxidation or YAP signaling suppressed lymph node metastasis in the mice.</P><P><I>Science</I>, this issue p. 644</P><P>In cancer patients, metastasis of tumors to sentinel lymph nodes (LNs) predicts disease progression and often guides treatment decisions. The mechanisms underlying tumor LN metastasis are poorly understood. By using comparative transcriptomics and metabolomics analyses of primary and LN-metastatic tumors in mice, we found that LN metastasis requires that tumor cells undergo a metabolic shift toward fatty acid oxidation (FAO). Transcriptional coactivator yes-associated protein (YAP) is selectively activated in LN-metastatic tumors, leading to the up-regulation of genes in the FAO signaling pathway. Pharmacological inhibition of FAO or genetic ablation of YAP suppressed LN metastasis in mice. Several bioactive bile acids accumulated to high levels in the metastatic LNs, and these bile acids activated YAP in tumor cells, likely through the nuclear vitamin D receptor. Inhibition of FAO or YAP may merit exploration as a potential therapeutic strategy for mitigating tumor metastasis to LNs.</P>

AP endonucleases process 5-methylcytosine excision intermediates during active DNA demethylation in <i>Arabidopsis</i>

Lee, Jiyoon,Jang, Hosung,Shin, Hosub,Choi, Woo Lee,Mok, Young Geun,Huh, Jin Hoe Oxford University Press 2014 Nucleic acids research Vol.42 No.18

<P>DNA methylation is a primary epigenetic modification regulating gene expression and chromatin structure in many eukaryotes. Plants have a unique DNA demethylation system in that 5-methylcytosine (5mC) is directly removed by DNA demethylases, such as DME/ROS1 family proteins, but little is known about the downstream events. During 5mC excision, DME produces 3′-phosphor-α, β-unsaturated aldehyde and 3′-phosphate by successive β- and δ-eliminations, respectively. The kinetic studies revealed that these 3′-blocking lesions persist for a significant amount of time and at least two different enzyme activities are required to immediately process them. We demonstrate that <I>Arabidopsis</I> AP endonucleases APE1L, APE2 and ARP have distinct functions to process such harmful lesions to allow nucleotide extension. <I>DME</I> expression is toxic to <I>E. coli</I> due to excessive 5mC excision, but expression of <I>APE1L</I> or <I>ARP</I> significantly reduces DME-induced cytotoxicity. Finally, we propose a model of base excision repair and DNA demethylation pathway unique to plants.</P>

A Method of Substrate Shaping to Improve Gain of Active-Element Pattern for Small Arrays

Lee, Taekki,Lee, Dae-Heon,Choo, Hosung,Byun, Gangil IEEE 2017 IEEE antennas and wireless propagation letters Vol.16 No.-

<P>This letter proposes a method of substrate subtraction to improve the gain of an active-element pattern for individual elements in a small array. The proposed method is applied to a three-element controlled reception pattern antenna array, whose radiating elements are printed on a high-dielectric ceramic substrate. Then, three identical fan-shaped areas, placed between the array elements, are subtracted from the substrate, and their shapes are adjusted to avoid unnecessary power losses caused by the fringing field effect, leakage fields, and surface currents. The effects of the subtracted areas are also investigated as parametric studies to demonstrate the effectiveness of the proposed substrate shaping method. The results show that the gain can be increased by 0.7 dB due to lower effective dielectric loss compared to the full substrate.</P>

Signal characteristic and test exploitation for intermittent nanometer-scale cracks

Lee, Hosung,Baeg, Sanghyeon Elsevier 2018 Microelectronics reliability Vol.84 No.-

<P><B>Abstract</B></P> <P>This paper analyzes signal distortion caused by nanometer-scale solder ball fractures. A solder ball fracture causes an intermittent open circuit on the transmission line. The resulting basic failure mechanism is a drop in signal voltage, due to the capacitance-induced Alternating Current (AC)-coupling effect (which is induced by the fractured solder ball). The two major contributing factors to this error are fracture height and the persisting duration of the consecutive same-logic-value signal. The required signal that induces a voltage drop, sufficient to detect nanometer-scale solder ball fractures, can be composed by repetition of certain signal patterns even for the I/O connections with run-length restrictions. The methodology is newly proposed to determine potential ranges of solder ball fractures. Test pattern generation is made by maximally exploiting the compounding effect of various sizes of same data bits to generate effective run-length that is larger than maximum run length for the purpose of detecting intermittent solder ball fractures. In DDR3 memory systems with 5-nm solder ball fractures, at least 29 bits of consecutive logic “1” or “0” signals are required to detect fractures. If the system has a maximum run-length of 10, 20, or 30 bits, the test signal—which has the equivalent voltage-dropping effect as 29-consecutive bits—can be generated with six, two, or one repetition of the test pattern, respectively; the test pattern is in the form of concatenated N-1 bits of consecutive logic “1” and 1 bit of logic “0” where N is the maximum run length. In addition, a SPICE simulation was conducted to confirm correlation between calculations and actual results. In the simulation, in order to detect a 5-nm solder ball fracture, at least 37 bits of consecutive signal were required.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The basic mechanism of the error by the nano-meter scale solder ball fracture </LI> <LI> The compounding effects of the switching signal for the fractured solder ball </LI> <LI> The methodology for selecting the target solder-ball-fracture range </LI> <LI> The methodology for generating the test pattern for the solder ball fracture </LI> </UL> </P>

Angiopoietin-2 exacerbates cardiac hypoxia and inflammation after myocardial infarction

Lee, Seung-Jun,Lee, Choong-kun,Kang, Seok,Park, Intae,Kim, Yoo Hyung,Kim, Seo Ki,Hong, Seon Pyo,Bae, Hosung,He, Yulong,Kubota, Yoshiaki,Koh, Gou Young American Society for Clinical Investigation 2018 The Journal of clinical investigation Vol.128 No.11

SW중심대학의 인공지능 교육과정 현황분석

우호성(HoSung Woo),이현정(HyunJeong Lee),김자미(JaMee Kim),이원규(WonGyu Lee) 한국컴퓨터교육학회 2020 컴퓨터교육학회 논문지 Vol.23 No.2

인공지능에 대한 관심은 기업이나 조직, 일상과 사회에 미치는 영향력의 증가에 기인한다. 이에 본 연구는 인재양성의 관점에서 Computer Science 2013의 지능형 시스템 영역을 기반으로 SW중심대학의 인공지능 관련 과목의 교수요목에 나타난 핵심요소를 분석하기 위한 목적이 있다. 분석 결과, 필수 과목을 운영하는 대학은 9개 대학 중 5개이다. 지능형 시스템의 12개 세부 지식영역을 기준으로 대학의 필수과목은 기본 검색이론, 기본 지식 표현 및 추론, 불확실성에 기반한 추론 영역에 분포되어 있다. 각 대학의 선택과목은 지능형 시스템 전체 지식영역 중 5~8개의 영역에 주제를 다루고 있었으며, 교수요목의 주제가 포함된 영역 평균 비율이 가장 높은 대학은 69.9%, 가장 낮은 대학은 46.3%이다. 본 연구는 인공지능 대학원의 진학 이전에 학부 수준에서 인공지능 관련 지식의 수준을 파악할 수 있었다는 점에 시사점이 있다. The interest in artificial intelligence is due to an increase in influence on companies, organizations, daily lives and society. The purpose of this study is to analyze the key elements in the teaching subjects of artificial intelligence-related subjects of Korean universities based on the intelligent system area of Computer Science 2013 in terms of human resources development. According to the analysis, there are five out of nine universities that run the required courses. Based on the 12 detailed knowledge domains of intelligent systems, the compulsory subjects of universities are distributed in the field of basic search theory, basic knowledge expression and reasoning, and inference based on uncertainty. The elective courses of each university covered topics in five to eight areas of the total knowledge area of the intelligent system, with 69.9 percent of universities with the highest average ratio of areas involving the subject of teaching subjects and 46.3 percent of universities with the lowest. This study has implications for the fact that prior to entering an artificial intelligence graduate school, we were able to grasp the level of knowledge about artificial intelligence at the undergraduate level.

스마트폰과 웨어러블 가속도 센서를 혼합 처리한 실시간 행위 및 자세인지 기법

이호성(Hosung Lee),이승룡(Sungyoung Lee) 한국정보과학회 2014 정보과학회논문지 : 소프트웨어 및 응용 Vol.41 No.8

최근 고성능 센서가 집적된 스마트폰과 웨어러블 디바이스 기술이 부각됨에 따라 이와 같은 플랫폼을 활용한 차세대 모바일 컴퓨팅 기술이 크게 주목받고 있다. 기존 행위인지는 지속적인 움직임에 따른 고유 패턴을 포착하는 반면, 자세인지는 급격한 순간 변화나 신체 방향의 변화를 포착하는 방법으로 접근되어 왔다. 그러나 이 두 가지의 패턴을 함께 고려하고 실제 활용 가능한 수준의 성능 확보와 그 시스템에 대한 연구는 다소 부족한 실정이다. 이에 본 논문에서는 최근 부각되는 스마트폰과 웨어러블 디바이스의 센서 데이터를 함께 고려하고 각각이 갖는 장점을 혼합한 사용자 행위 및 자세인지 기법과 스마트폰 플랫폼을 기반으로 실제 환경에서의 그 활용 방법을 제안한다. 스마트폰과 웨어러블 센서 데이터를 함께 운용하기 위한 전처리 방법을 설계하고 고유 진동 패턴과 수직, 수평 방향 패턴 특징을 혼합적으로 활용하여 인지 모델을 구축하였다. 이 과정에서 자전거 타기와 빠르게, 천천히 걷기, 뛰기와 같이 보다 다양한 행위와 서기, 앉기, 누워있기와 같은 자세 패턴을 고려하였다. 실험 결과 제안하는 기법의 성능과 타당성을 입증하였고 실제 환경에서의 적용을 통해 그 활용 가능성을 보였다. The next generation mobile computing technology is recently attracting attention that smartphone and wearable device imbedded with various sensors are being deployed in the world. Existing activity and posture recognition research can be divided into two different ways considering feature of one"s movement. While activity recognition focuses on catching distinct pattern according to continuous movement, posture recognition focuses on sudden change of posture and body orientation. There is a lack of research constructing a system mixing two separate patterns which could be applied in real world. In this paper, we propose a method to use both smartphone and wearable device to recognize activity and posture in the same time. To use smartphone and wearable sensor data together, we designed a pre-processing method and constructed recognition model mixing signal vector magnitude and orientation pattern features of vertical and horizontal. We considered cycling, fast/slow walking and running activities, and postures such as standing, sitting, and laying down. We confirmed the performance and validity by experiment, and proved the feasibility in real world.

스마트폰 가속도센서 기반 행위 및 낙상인지를 위한 특징 추출 기법

이호성(Hosung Lee),이승룡(Sungyoung Lee) 한국정보과학회 2013 한국정보과학회 학술발표논문집 Vol.2013 No.6