Particle Swarm Optimization Using Adaptive Boundary Correction for Human Activity Recognition

( Yongjin Kwon ),( Seonguk Heo ),( Kyuchang Kang ),( Changseok Bae ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.6

As a kind of personal lifelog data, activity data have been considered as one of the most compelling information to understand the user`s habits and to calibrate diagnoses. In this paper, we proposed a robust algorithm to sampling rates for human activity recognition, which identifies a user`s activity using accelerations from a triaxial accelerometer in a smartphone. Although a high sampling rate is required for high accuracy, it is not desirable for actual smartphone usage, battery consumption, or storage occupancy. Activity recognitions with well-known algorithms, including MLP, C4.5, or SVM, suffer from a loss of accuracy when a sampling rate of accelerometers decreases. Thus, we start from particle swarm optimization (PSO), which has relatively better tolerance to declines in sampling rates, and we propose PSO with an adaptive boundary correction (ABC) approach. PSO with ABC is tolerant of various sampling rate in that it identifies all data by adjusting the classification boundaries of each activity. The experimental results show that PSO with ABC has better tolerance to changes of sampling rates of an accelerometer than PSO without ABC and other methods. In particular, PSO with ABC is 6%, 25%, and 35% better than PSO without ABC for sitting, standing, and walking, respectively, at a sampling period of 32 seconds. PSO with ABC is the only algorithm that guarantees at least 80% accuracy for every activity at a sampling period of smaller than or equal to 8 seconds.

이동 객체 위치 추정을 위한 저조도 환경에서의 특징점 매칭 방법론

권용진(Yongjin Kwon),윤준희(Junhee Youn),최강혁(Kanghyuk Choi) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.10

최근 스마트시티, 도시계획, 로봇 공학, 공간정보 등 다양한 분야에서 이동 객체의 위치 추정 기술은 핵심 알고리즘으로 사용될 수 있다는 점에서 다양한 연구가 진행되고 있다. 영상 기반의 위치추정 방법은 비교적 구현이 간편하고 안정적이지만, 저조도 환경에서는 대비 저하와 노이즈로 인해 객체의 특징점을 정확하게 추출 및 매칭 하는 것에 한계가 존재한다. 따라서 본 논문에서는 저조도 환경에서 영상 기반의 위치추정을 위한 특징점 매칭 성능을 향상시키는 방법론을 제안하였다. 본 연구에서는 대표적인 특징점 매칭 알고리즘 KAZE, ORB, SIFT 그리고 SURF를 이용하여 저조도 환경에서 특징점 매칭을 수행하고 그 결과에 대해 비교 분석한다. 다음으로 CLAHE, 미디안 필터 그리고 다운 샘플링의 영상 전처리 기법을 이용하여 특징점 매칭 알고리즘과 함께 조합하여 성능을 비교 분석하였다. 분석 결과 ORB 알고리즘과 다운 샘플링의 조합이 평균 92% 이상의 정확도와 최대 0.287초 이하의 처리 시간을 보였다. 이는 다른 전처리 기법 및 특징점 매칭 알고리즘 조합 대비 가장 높은 정확도와 함께 우수한 성능을 보여준다. Technology for estimating the position of moving objects has been the subject of extensive research due to its potential in diverse fields, such as smart cities, urban planning, robotics, and spatial information. Image-based location-estimation methods are relatively simple to implement and stable. However, in low-light environments, there are limitations in accurately extracting and matching feature points of objects due to reduced contrast and noise. This paper presents a framework to enhance feature-matching performance for image-based position estimation in low-light environments. We employed well-known feature matching algorithms such as KAZE, ORB, SIFT, and SURF to perform feature-point matching in low-light environments and analyzed the results. We then combined these algorithms with image-processing techniques like CLAHE, a median filter, and down-sampling to compare their performance. The combination of the ORB algorithm and down-sampling showed an average accuracy of more than 92% and a maximum processing time of less than 0.287 seconds. This combination showed excellent performance with the highest accuracy compared to other combinations of image-processing techniques and feature-point matching algorithms.

건강보험 청구자료를 활용한 약물관련 악골괴사의 국내 현황 및 비용 분석

권용진(Yongjin Kwon),박미혜(Mi-Hai Park) 대한약학회 2020 약학회지 Vol.64 No.4

Although Medication-Related Osteonecrosis of the Jaw (MRONJ) does not usually occur, the use of drugs that may cause MRONJ is increasing and there is no research reported about its cost and the perception of MRONJ is low in Korea. So here we analyzed the current disease status, such as occurrence and duration, and the cost of treatment of MRONJ in Korea. It was analyzed by the National Health Insurance Service sample cohort 2.0DB data. Patients were included who diagnosed and treated with ‘Osteonecrosis due to drugs (ICD-10: M87.1)’ or ‘Inflammatory conditions of jaws (ICD-10: K10.2)’ after the less than three years from the last dose of drugs. A total of 183 MRONJ patients were identified. The most frequently administered Bone-Modifying Agents were Alendronate, Risedronate, and Ibandronate. From 2002 to 2015, the proportion of MRONJ in the total number of prescribed patients was between 0.2% and 0.9%. The billing costs for MRONJ per patient was KRW 934,422. The highest cost claim was Surgery of Osteomyelitis of Mandible or Maxilla. The total cost of medical, non-medical and indirect costs was KRW 1,891,808 per patient. Through this research, it was found that the cost of treatment of MRONJ was high, and it was possible to analyze the current status and characteristics of MRONJ in Korea.

실제 의료 데이터 분석을 통한 데이터 익명화 방법 제시

권용진(Yongjin Kwon),연종흠(Jongheum Yeon),이상구(Sang-goo Lee) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.1C

정부, 병원, 공공기관, 기업 등에서 많은 양의 개인 정보를 수집하고, 다양한 목적으로 수집한 데이터를 공개하기도 한다. 프라이버시 보호를 위해 공개할 데이터를 어떻게 익명화를 할 것인지 많이 연구가 되었지만, 알고리즘 적용의 어려움과 데이터에 대한 비현실적인 가정 때문에 실제 데이터에 적용되는 사례는 찾아보기 힘들다. 본 논문에서는 먼저 다양한 익명화 방법에 대한 분류를 하고, 장단점을 살펴본다. 그리고 의료 기관에서 의료 데이터를 공개하는 경우를 고려하여 실제 의료 데이터가 갖는 특징을 파악하고, 의료 데이터에 적용할 수 있는 프라이버시 모델(privacy model)과 알고리즘에 적용하기 위한 의료 데이터의 기본 형태에 대해 제시한다.

두 개의 수신안테나를 사용한 채널적응형 임의접근의 포착성능 시뮬레이션

권용진(Yongjin Kwon),문희찬(Hichan Moon) 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.11

Deep learning-based scalable and robust channel estimator for wireless cellular networks

Anseok Lee(Anseok Lee),Yongjin Kwon(Yongjin Kwon),Hanjun Park(Hanjun Park),Heesoo Lee(Heesoo Lee) 한국전자통신연구원 2022 ETRI Journal Vol.44 No.6

In this paper, we present a two-stage scalable channel estimator (TSCE), a deep learning (DL)-based scalable, and robust channel estimator for wireless cellular networks, which is made up of two DL networks to efficiently support different resource allocation sizes and reference signal configurations. Both networks use the transformer, one of cutting-edge neural network architecture, as a backbone for accurate estimation. For computation-efficient global feature extractions, we propose using window and window averaging-based self-attentions. Our results show that TSCE learns wireless propagation channels correctly and outperforms both traditional estimators and baseline DL-based estimators. Additionally, scalability and robustness evaluations are performed, revealing that TSCE is more robust in various environments than the baseline DL-based estimators.

The Spillover Effects of Health Information Technology Implementation on Healthcare Quality

Yongjin Park,Youngsok Bang,Juhee Kwon 한국경영정보학회 2018 한국경영정보학회 학술대회논문집 Vol.2018 No.11

U.S. government subsidies under the HITECH Act of 2009 have boosted hospitals’ IT investments, which are expected to improve the quality of care as well as the effectiveness of healthcare management. Given the rush to adopt health information technology (HIT) throughout the continuum of care across healthcare providers, this study tries to identify the spillover effects of HIT adoption on quality of care. Using 1,965 U.S. hospital data in 232 health referral regions (HRRs), we examine how a hospital’s and its neighboring hospitals’ HIT adoptions interact with each other and how they impact readmission rates. We find that a hospital’s readmission rate is reduced by both its own and neighbors’ HIT adoption. Such effects become greater along with the focal hospital’s own adoption. We further investigate how spillover effects vary with HRRs’ different market structures and hospitals’ meaningful-use status. Our findings offer theoretical and managerial insights for both healthcare researchers and practitioners.

GIS와 Web을 통합한 모바일 지역정보 검색 시스템

강용진(Yongjin Kang),Yutaka Kidawara(Yutaka Kidawara),권용진(Yong-Jin Kwon),Katusmi Tanaka(Katusmi Tanaka) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.1

인터넷 기술의 발전과 웹 사용자의 증가로 웹에는 매우 많은 정보들이 축적되고 있으며, 여기에는 또한 매우 많은 지역정보가 존재한다. 일반적으로 웹 정보라고 하는 것은 웹의 컨텐츠, 사용이력, 구조를 중심으로 한 정보이며, 이러한 정보를 하나의 중요한 공간 정보원으로 취급하여 웹으로부터 특정 지역에 관한 컨텐츠를 수집하고 이를 분석하여 사용자의 공간 정보원으로서 사용할 수 있다. 또한 인터넷, 무선통신, 지리정보시스템(GIS), 위치기반서비스(LBS) 등의 기술들이 모바일기기에 복합적으로 접목되면서 모바일기기에서의 새로운 형태의 정보에 대한 응용이 요구되고 있다. 본 논문에서는 이러한 웹 환경을 활용하고, 모바일 환경을 고려하여 GIS와 Web을 통합한 모바일 지역정보 검색 시스템을 제안한다.

Glucose biofuel cells using bi-enzyme catalysts including glucose oxidase, horseradish peroxidase and terephthalaldehyde crosslinker

Chung, Yongjin,Tannia, Daniel Chris,Kwon, Yongchai Elsevier 2018 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.334 No.-

<P><B>Abstract</B></P> <P>Biocatalysts consisting of bi-enzyme of glucose oxidase (GOx) and horseradish peroxidase (HRP) and terephthalaldehyde (TPA) as cross-linker ([(TPA/HRP/GOx)]/PEI/CNT) that have different GOx and HRP mass ratio are developed and their catalytic activity about glucose oxidation reaction and electrical performance evaluated via biofuel cell are characterized. To gain the optimal catalytic structure, current density peak of flavin adenine dinucleotide redox reaction, electron transfer rate, Michaelis-Menten constants, sensitivity and catalytic stability are measured. As a result, [(TPA/HRP/GOx)]/PEI/CNT whose HRP and GOx ratio is 2:5 is determined as the best catalyst. It is ascribed to superior catalytic activity of GOx and H<SUB>2</SUB>O<SUB>2</SUB> reduction reaction ability of HRP. Regarding electrical performance, polarization curves of enzymatic biofuel cells (EBCs) using the associated catalysts indicate that maximum power density (MPD) of EBC using [(TPA/HRP/GOx)]/PEI/CNT (HRP and GOx ratio of 2:5) is 2.0 ± 0.1 mW·cm<SUP>−2</SUP>, which is the highest of all the tested EBCs. Based on that, it is obvious that the optimal [(TPA/HRP/GOx)]/PEI/CNT induces improvements in catalytic activity and EBC performance due to proper removal of toxic H<SUB>2</SUB>O<SUB>2</SUB> molecules by HRP, excellent glucose reactivity by GOx and stable bonding of the catalytic structure by TPA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> [(TPA/HRP/GOx)]/PEI/CNT catalyst is suggested as anodic catalyst of EBC. </LI> <LI> Optimal GOx and HRP mass ratio determines catalytic activity of the catalyst. </LI> <LI> TPA leads to stable bonding of the catalytic structure. </LI> <LI> There are effects of H<SUB>2</SUB>O<SUB>2</SUB> removal by HRP and excellent glucose reactivity by GOx. </LI> <LI> EBC employing [(TPA/HRP/GOx)]/PEI/CNT catalyst indicates excellent performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

亞共晶 Al-Si合金의 鑄造時 抵動效果에 關한 硏究

朴龍鎭,權赫茂 弘益大學校 1976 弘大論叢 Vol.8 No.-

This paper deals with some of the effects of change of the vibrative condition that was forced to mold on grain refining of the primary crystal, hardness, tensile strength and elongation. The melt of AI-Si alloy was poured into the metallic mold and it was solidified while vibrating by air vibrator. The reults obtained can be summarized as followls: (1) When the compressed air pressure was higher than 2.5㎏/㎤ the method of casting by vibration was not suitable, because of bulk growth of the castings surface of AI-5.6% Si alloy. (2) the castings of the hypo-eutectic AI-Si alloy by the vibrational method under the air pressure of higher than 2.5㎏/㎤ should have more than 0.8㎜ of cutting tolerance. (3) It was found that the grains of α-solid solution of the primary crystal were finer when the casting was prepared by the vibrational methd than that of static method. (4) Neither the micro-graphic grain size nor the mechanical properties of the vibrational casting were proportional to the change of the vibrational modes. However they were found to vary pery periodically with respect to the change of the vibrational modes. (5) In the case of the vibrational method, the casting temperature was almost same as in the case of the general metallic mould casting. (6) It was found that the tensile strength of the vibrational casting was not inversely proportional to the elongation of the casting.