포스트가 배열된 마이크로 채널 내 전기 역학 및 유전 영동 흐름에 대한 수치 연구

권재성(Jae-sung Kwon),맹주성(Joo-sung Maeng),송시몬(Simon Song) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

본 논문은 마이크로 채널 내의 전기 역학 및 유전 영동 현상을 수치적으로 분석하였다. 이를 위하여 원형 post가 배열된 마이크로 채널 내에 직류 전기장을 걸어주고 두 현상을 수치적으로 해석하였다. 외부 전기장에 의해 마이크로 채널내에 전기 역학 및 유전 영동 현상이 발생할 때 전기장의 세기에 따라 세 가지 형태의 입자 움직임이 나타난다. 낮은 전기장 세기에서는 전기 역학이, 높은 전기장 세기에서는 유전 영동이 지배적으로 입자의 움직임에 영향을 준다. 그 중간세기의 전기장에서는 streaming 유전영동 현상이 관찰된다. 이 연구는 현재 진행중인 연구로서 앞으로는 전기장에 대한 post 배열 각도와 post 형상을 달리하여 전기 역학과 유전 영동 현상의 변화를 연구하고, 이를 바탕으로 칩위에서 바이오샘플을 분리, 정제, 추출할 수 있는 샘플 전처리기술을 개발하고자 한다. 또한 칩 설계에 최적화 기술을 도입하여 바이오칩 성능을 획기적으로 향상시킬 것이다. We predict electrokinetic and dielectrophoretic flows in microchannels with a uniform post array. Computational studies are performed to determine velocity of particles suspending in a fluid driven by electrokinesis and dielectrophoresis in the channel. Monte-Carlo simulations are also conducted to visualize the particle motions. At low applied electric fields, electrokinesis is the dominant transport mechanism. At moderate applied fields, dielectrophoresis are in balance with electrokinesis and diffusion to produce flowing filaments of concentrated and rarefied particles in the microchannels. At high applied fields, dielectrophoresis overwhelms, and locally traps particles. The results provide useful insight for optimizing design parameters of a microfluidic chip to carry out on-chip sample pretreatment using electrokinetic and dielectrophoretic effects.

마이크로 채널내의 전기 역학 및 유전 영동 현상에 대한 수치 해석

권재성(Jae-sung Kwon),맹주성(Joo-sung Maeng),송시몬(Simon Song) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

Electrokinesis and dielectrophoresis are two technologically important transport phenomena produced by an external electric field applied to a conductive fluid. Electrokinesis including electroosmosis and electrophoresis is transports of particle or fluid with net mobile charges and is caused by the external electric field. In contrast, dielectrophoresis is particle motions caused by an electric field gradient on an induced dipole moment of the particle and the surrounding fluid. Numerical analyses are conducted to predict the particle and fluid motions under an external electric fields in microchannels made of glass. Results provide insights into electrokinetic and dielectrophoretic behaviors of the particles and fluids and enable to optimize microchannel designs of biochips for biochemical analysis.

미세유동 칩에 배열된 원형 포스트가 전기 역학 및 유전 영동 유동에 미치는 영향

권재성(Jae-Sung Kwon),맹주성(Joo-Sung Maeng),김태호(Tae-Ho Kim),송호성(Ho-Sung Song),송시몬(Simon Song) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

Microfluidic chips are frequently used for the automation and miniaturization of the analytic processes of bio molecules such as DNA or proteins. Among physical phenomena occurred on a microfluidic chip, electrokinesis and dielectrophoresis are paid attention to as means to transport and control the bio molecules. To effectively utilize electrokinesis and dielectrophoresis, it is important to design the shape of a microchannel on a microfluidic chip. We investigate the effects of microchannel geometry with circular posts on electrokinesis and dielectrophoresis, and determine a microchannel geometry suitable for the clean-up or separation of bio molecules. In addition, we examine forces on particles exerted by electrokinesis and dielectrophoresis for various post diameters and spacings using an in-house CFD code. As a result, an optimal shape of a microchannel is suggested that is suitable for separating bio molecules with different surface charges.

메타분석을 통한 뇌졸중 환자의 인지기능에 대한 가상현실 중재 효과 연구

권재성(Kwon, Jae Sung) 대한신경계작업치료학회 2021 재활치료과학 Vol.10 No.3

목적 : 본 연구에서는 뇌졸중 환자의 손상된 인지기능 회복을 위한 가상현실 중재의 효과를 체계적인문헌고찰과 메타분석을 통하여 검증하고자 하였다. 연구방법 : 체계적 문헌고찰을 위하여 최근 10년 동안의 국내·외 무작위 대조 임상시험 연구들을 대상으로조사하였다. 검색을 위한 학술 데이터베이스로는, 영어로 작성된 연구의 검색을 위해 PubMed와MEDLINE, CINAHL을 사용하였고, 국문으로 작성된 연구의 검색을 위해서는 DBpia와 한국학술정보, 스콜라 학지사·교보문고, 학술교육원을 사용하였다. 정보의 추출은 PICO 방식으로 시행하였다. 계량적메타분석을 위하여, 결과변인의 하위그룹을 전반적인 인지기능, 집중력과 기억력, 실행기능으로 분류하여 결과변인을 합성하였다. 결과 : 최종 9편의 무작위 대조 임상시험이 선정되었고, 참여대상자의 총인원은 실험군이 140명, 대조군이131명이었다. 효과크기는 랜덤효과모델로 산출하였다. 하위그룹들에 대한 가상현실 중재의 효과크기는전반적인 인지기능이 0.422(95% CI: 0.101~0.742; p=0.010)로 중간효과크기에 가까웠고, 집중력과 기억력이 0.249(95% CI: -0.107~0.605; p=0.170)로 작은효과크기, 실행기능은 0.666(95% CI: 0.136~1.195; p=0.014)으로 중간효과크기를 나타내었다. 결론 : 가상현실 환경의 다양한 자극과 본 연구의 결과를 고려할 때, 가상현실 중재는 통합적인 인지기능에대한 중재에 적용되어야 할 것이다. 또한 전통적인 뇌졸중 인지재활 중재와 더불어 추가적인 중재로활용되는 것이 적절할 것이다. Objective : The purpose of this study was to verify the effect of virtual reality interventions (VRIs) on cognitive function in individuals with stroke through a systematic literature review and meta-analysis. Methods : We reviewed randomized controlled trials (RCTs) the last 10 years using academic databases. PubMed, MEDLINE, and CINAHL were used for international studies, and DBpia, KISS, Kyoboscholar, and e-article were used for Korean studies. For the quantitative meta-analysis, subgroups of outcomes were classified into general cognitive function (G-CF), attention and memory (A&M), and executive function (EF). Results : Nine RCTs were analyzed. The total number of participants was 271 (140 in the experimental group). The effect size (Cohen’s d) was estimated using a random effects model. The effect sizes of the outcome subgroups of were as follows: small to medium for G-CF (d=0.422; 95% CI: 0.101~0.742; p=0.010), small for A&M (d=0.249; 95% CI: -0.107~0.605; p=0.170), and medium for EF (d=0.666; 95% CI: 0.136~1.195; p=0.014). Conclusion : Considering the various stimuli provided by the virtual environment and the results from available research, virtual reality should be applied to interventions for integrated cognitive functions. In addition, it would be appropriate to be used as an additional intervention to traditional cognitive rehabilitation for stroke.

로봇 중재가 뇌졸중 환자의 상지기능에 미치는 영향: 무작위대조연구에 대한 메타분석

권재성 ( Jae-sung Kwon ) 한국보건정보통계학회(구 한국보건통계학회) 2018 보건정보통계학회지 Vol.43 No.1

Objectives: The main symptom of stroke is upper limb function deficit. Robotic intervention has been applied to treat the paretic upper limb. Through this meta-analysis, we investigated the effect of robotic intervention on upper limb function recovery of individuals with stroke. Methods: The analyzed studies were identified through electronic search engines such as PubMed, CINAHL, MEDLINE for the last 5 years. The PEDro scale was used to rate the methodological quality of included studies. Meta-analysis is performed to analyze the sample size, means, and standard deviations in selected studies. Results: Ten randomized controlled trails were included for meta-analysis. PEDro scale was more than 6 points in all studies. Three hundred twenty subjects participated in included studies. In order to statistically analyze the effect size of the robotic interventions, the outcomes of studies were classified into upper limb function (ULF) and activities of daily living (ADL). In consideration of heterogeneity of effect size, we used random effect model. Meta-analysis of 10 trials showed “small effect size”. The effect size of ULF was 0.288 and the effect size of ADL was 0.265. Conclusions: Robotic intervention was not more effective than other dose-matching conventional therapies. Therefore, it is necessary to select appropriate individual interventions reflect characteristics of the individuals with stroke and robotic interventions may be used as a complementary methods to conventional therapy.

샘플 전처리 성능 향상을 위한 원형 포스트가 배열된 마이크로 채널의 최적화

권재성(Jae-Sung Kwon),안윤호(Yun-Ho An),맹주성(Joo-Sung Maeng),송시몬(Simon Song) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

Microfluidic chips are frequently used for the automation and miniaturization of the analytic processes of bio molecules such as DNA or proteins. Among physical phenomena occurred on a microfluidic chip, electrokinesis and dielectrophoresis are paid attention to as means to transport and control the bio molecules. To effectively utilize electrokinesis and dielectrophoresis, it is important to design the shape of a microchannel on a microfluidic chip. We investigate the effects of microchannel geometry with circular posts on electrokinesis and dielectrophoresis, and determine a microchannel geometry suitable for the clean-up or separation of bio molecules. In addition, we examine forces on particles exerted by electrokinesis and dielectrophoresis for various post diameters and spacings using an in-house CFD code. As a result, an optimal shape of a microchannel is suggested that is suitable for separating bio molecules with different surface charges.

치매 인지재활에서 과정기억 기반 활동의 임상 적용 필요성

권재성 ( Kwon Jae-sung ) 대한인지재활학회 2018 대한인지재활학회지 Vol.7 No.1

본 연구의 목적은 치매 인지재활 현장에서 치매 노인들에게 익숙하고 친숙한 과정기억 기반 활동을 적용해야 할 필요성을 제시하기 위함이었다. 작업치료사는 의미 있는 작업을 치료적 도구로 사용하는 전문가이다. 본 문헌 고찰은 치매 인지재활에 관여하는 작업치료사들에게 다음과 같은 치료적 전략을 제시하였다. 첫 번째는 치료적 활동이 치매 노인들에게 질적으로 의미 있는 활동이어야 한다는 것이다. 의미 있는 활동은 친숙하고 사회적 관계를 형성할 수 있으며 가르치는 역할이 있는 활동이다. 두 번째는 과정기억 기반의 익숙한 활동을 통해 노인들의 참여를 극대화하는 것이다. 마지막으로는 작업치료사가 활동에 참여하는 치매 노인들의 경험을 질적으로 관찰하고 평가해야 한다는 것이다. 이와 같은 문헌 연구의 시도가 작업치료 현장에서 치매 인지재활의 방향성을 제시하는데 도움이 되었기를 바란다. The purpose of this study was to suggest the necessity of applying procedural memory-based activities to the elderly with dementia in cognitive rehabilitation. This literature review presented the following therapeutic strategies for occupational therapists who use meaningful occupation as a therapeutic tools. The first, activities for the elderly with dementia should be meaningful qualitatively. Meaningful activities are familiar and have social relations and teaching roles. The second is to maximize the participation of elderly people through familiar activities based on procedural memory. Finally, occupational therapists should qualitatively observe and evaluate the experience of the elderly with dementia engaged in activities.

기능적 인지의 작업치료 임상 적용 필요성

권재성 ( Kwon Jae Sung ) 대한인지재활학회 2021 대한인지재활학회지 Vol.10 No.1

본 연구의 목적은 작업치료 임상에 기능적 인지(functional cognition)의 개념을 소개하고 기능적 인지의 출현 과정을 작업치료의 역사적인 맥락과 인지 개념의 변화 과정을 토대로 설명하기 위함이었다. 또한 기능적 인지에 대한 작업치료 임상 모델들의 관점을 조망해 보고 기능적 인지의 작업치료 임상 적용 필요성을 설명하고자 하였다. 기능적 인지는 역사적으로는 전인적이고 작업 중심적인 통합주의에 기반하고 개념적으로는 상황인지의 영향을 받았다. 기능적 인지는 새로운 이론이 아니라 작업치료 영역에서 연구된 이론과 전문적 경험에 의하여 축적된 지식의 조합이다. 기능적 인지의 개념에는 다양한 작업치료 인지재활의 임상 모델과 이론의 틀이 포함된다. 기능적 인지는 인간 작업의 관점에서 통합적인 인지를 설명하고 있다는 측면에서 가장 작업치료다운 인지의 개념이다. 작업치료사는 기능적 인지 개념을 통하여 인지재활 현장에서 실제적인 작업을 통해 인지를 평가하고 클라이언트(환자) 중심의 개별적인 중재를 시행할 수 있다. 기능적 인지는 지금도 진화하고 있다. 그러므로 기능적 인지는 인지재활 전문가인 작업치료사들에 의해 지속적으로 연구되고 발전되어야 할 것이다. The aim of this study was to introduce the concept of functional cognition to the clinical field of occupational therapy and to explain the process up to the appearance of functional cognition based on the historical context of occupational therapy and the process of changing cognitive concepts. In addition, it was attempted to examine the perspectives of occupational therapy clinical models for functional cognition and to explain the necessity of clinical application of functional cognition in occupational therapy. Functional cognition is historically based on holistic and occupation-based integrationism and conceptually influenced by situated cognition. Functional cognition is not a new theory, but a combination of occupational therapy theory and knowledge accumulated by professional experience. The concept of functional cognition includes various clinical models and frame of references of cognitive rehabilitation in occupational therapy. Functional cognition is the most occupational therapy-like concept of cognition in that it describes integrative cognition from the perspective of human occupation. Occupational therapists can evaluate real tasks in daily life through functional cognitive concepts and implement client-centered intervention in cognitive rehabilitation. Functional cognition is still constantly evolving. Therefore, functional cognition should be continuously studied and developed by occupational therapists who are experts in cognitive rehabilitation.

국내 치매 노인을 위한 인지중재활동의 효과: 메타분석

권재성 ( Jae Sung Kwon ) 한국보건정보통계학회(구 한국보건통계학회) 2019 보건정보통계학회지 Vol.44 No.3

Objectives: The purpose of this meta-analysis was to investigate the effects of cognitive intervention activities (CIAs) for the elderly with dementia in Korea. We had searched for articles related to cognitive intervention for dementia over the past decade. Methods: The studies were searched through domestic search engine such as Earticle, KISS, Kyoboscholar, NDSL and RISS. The PEDro scale was used to assess the quality of the studies. The meta-analysis was implemented to analyze statistical values such as the number of samples, mean and standard deviation. Results: Nine papers were carefully selected for meta-analysis. The PEDro scales of analyzed studies were 4-5 points. The total number of subjects in identified studies was 336. We classified the dependent variables into mental function (MF) and activity and participation (A&P) based on the International Classification of Functioning, Disability and Health to compute effect sizes. The effect size of MF was 0.464 and the effect size of A&P was 0.422, both of which were “medium effect sizes”. Conclusions: The medium effect sizes for CIAs are clinically acceptable. However, it should be considered that dementia is a degenerative disease. And well designed and high quality research should be implemented continuously.

진동자극이 중추신경계 질환 환자의 신체적 기능 회복에 미치는 효과: 무작위대조연구에 대한 메타분석

권재성 ( Jae Sung Kwon ) 한국보건정보통계학회(구 한국보건통계학회) 2017 보건정보통계학회지 Vol.42 No.3

Objectives: The central nervous system (CNS) diseases cause serious damage to motor and sensory functions. The individuals with CNS disease have great limitations in activities of daily living and social participation. This meta-analysis was conducted to investigate the effect of vibratory stimulation on physical function recovery in individuals with CNS disease. Methods: Data were collected through data search engines such as PubMed, CINAHL, MEDLINE from 2005 to 2017. The PEDro scale was used to assess the quality of study. The sample size, mean and standard deviation in the studies were analyzed by meta-analysis. Results: Ten studies were selected for analysis and all studies had PEDro score of 6 points or more. Three hundred fourteen participants were included. The outcome data were categorized as physical functions focused on community participation such as “balance function” and “upper & lower function and gait function.” The effect sizes of the selected studies were statistically insignificant in heterogeneity. The effect sizes of combined outcomes and “upper & lower function and gait function” were 0.356 and 0.421 as indicated by a “medium effect size” and the effect size of “balance function” was 0.223 as indicated by a “small effect size.” Conclusions: We found that vibratory stimulation has the advantage of enhancing physical function in CNS rehabilitation field. However, there was no superior effect than other types of intervention.