등속성 운동이 노인 여성의 하지근력에 미치는 영향

조재혁,이승훈 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.5

The purpose of this study is to find whether isokinetic training has a good effect on decrease of the lower limbs muscular strngth caused by aging and find the isokinetic training Speed which has a good effect on muscular strength. The subjects of this study are 16 elderly women aged from 61 to 65. The subjects were distributed into two groups, low-speed isokinetic training program group(n=8) arid high-speed isokinetic training program group(n=8) respectively. The subjects of two groups participated in lower extremities isokinetic training program three times a week for 12 weeks. Changes of the lower limbs muscular strength after training were analyzed through repeated measures anova. Results of this study are following: 1. Change of knee extension isokinetic peak torque at the 60˚/ sec in the LS group after 12 week training was significantly different form HS groups. There was no significant difference in knee flexion peak torque among groups. 2. Change of knee extension isokinetic peak torque at the 180˚/sec in the HS group after week training was significantly different form LS groups. There was no significant difference in knee flexion peak torque among groups.

Cathode 입구 상대습도에 따른 고분자 전해질 연료전지 성능분석

조재혁,김우태 한국기계기술학회 2014 한국기계기술학회지 Vol.16 No.3

PEMFC 가스채널 내의 액적-액적 상호작용에 대한 수치모사

조재혁,김우태 한국기계기술학회 2014 한국기계기술학회지 Vol.16 No.6

The dynamic interaction of liquid droplets emerging from the gas diffusion layer surface is modeled to study the behavior of liquid water inside the gas channel of a polymer electrolyte membrane fuel cell with the volume of fluid (VOF) formulation. The surface contact angle of gas diffusion layer is varied as 45, 90, and 140 degrees. The air inlet velocity in the gas channel is varied as 5, 10, and 15 m/s. The water inlet velocity from micro pores is varied as 0.5, 1, and 2 m/s. As the contact angle increases, water coverage ratio increases. As the air inlet velocity and the water inlet velocity increase, water droplets move faster toward the channel exit as evidenced from the water front location plots. In summary, the hydrophobic wall contact angle and higher air/water inlet velocities provide better water removal characteristics.

고분자 전해질 연료전지의 가스채널, 기체확산층, 촉매층 조건변화에 따른 온도특성 분석

조재혁,김우태 한국기계기술학회 2013 한국기계기술학회 학술대회논문집 Vol.2013 No.08

머신러닝 기반 고속도로 내 수소충전소 최적입지 선정 연구

조재혁,김성수,Jo, Jae-Hyeok,Kim, Sungsu 한국국토정보공사 공간정보연구원 2021 지적과 국토정보 Vol.51 No.2

대기오염, 지구온난화 문제 등 환경 문제의 심각성이 대두되면서 청정 연료의 관심이 커지고 있다. 그 중 수소는 기존 화석연료와는 달리 연소 시 부산물로 수분만이 발생하는 대표적인 친환경 에너지원으로 현재 다양한 분야에서 주목을 받고 있다. 물류 분야에서도 수소를 활용한 물류 네트워크를 구축하기 위해 다양한 정책적 노력이 활발히 이루어지고 있다. 이러한 수소 물류 네트워크의 구축에 있어 수소충전소의 입지 결정은 매우 중요한 문제이다. 최근 개발된 수소추진(수소연료전지) 화물차에 수소를 공급하는 충전소는 수소 기반 물류체계가 본격적으로 자리 잡는 데 있어 필수 불가결한 요소이다. 이러한 수소충전소의 최적 입지를 결정하는 선행연구는 대부분 수리적 모형에 기반한 최적화 기법만을 사용하여 수소충전소의 최적 입지를 결정하고자 하였다. 본 연구에서는 기존 연구의 동향과는 차별화하여 최적화 기법의 중요한 투입 변수 중 하나인 충전소 후보지에 대한 공간적 특성을 검토하는 방법으로 머신러닝 모형들을 활용하고 그 적용가능성을 확인하였다. 머신러닝은 다양한 분야에서 우수한 성과를 증명한 기법이지만 수소충전소의 최적 입지를 결정하는 연구 분야에서는 아직 적용된 바가 없다. 이를 위해 본 연구에서는 개별공시지가, 수소공급지와의 거리 등 전국 고속도로 휴게소와 고속도로의 무작위 지점들의 위치와 관련된 변수들을 독립변수로 선정하여 단일 머신러닝 모형과 앙상블 모형을 적용하고 그 성과를 비교하였다. 분석 결과, 랜덤포레스트(Random Forest) 모형이 가장 우수한 성과를 보였으며, 다른 모형들 또한 우수한 분류 성능을 보여 최적 입지 문제에 대해 공간적 특성을 예비적으로 검토하는 방법론으로써 머신러닝의 적용 가능성을 확인할 수 있었다. 따라서 머신러닝 모형은 수소충전소의 최적 입지 결정 분야에서 향후 최적화 기법을 적용한 연구의 예비적 검토 방법론으로 널리 활용할 수 있을 것으로 기대된다. Interests in clean fuels have been soaring because of environmental problems such as air pollution and global warming. Unlike fossil fuels, hydrogen obtains public attention as a eco-friendly energy source because it releases only water when burned. Various policy efforts have been made to establish a hydrogen based transportation network. The station that supplies hydrogen to hydrogen-powered trucks is essential for building the hydrogen based logistics system. Thus, determining the optimal location of refueling stations is an important topic in the network. Although previous studies have mostly applied optimization based methodologies, this paper adopts machine learning to review spatial attributes of candidate locations in selecting the optimal position of the refueling stations. Machine learning shows outstanding performance in various fields. However, it has not yet applied to an optimal location selection problem of hydrogen refueling stations. Therefore, several machine learning models are applied and compared in performance by setting variables relevant to the location of highway rest areas and random points on a highway. The results show that Random Forest model is superior in terms of F1-score. We believe that this work can be a starting point to utilize machine learning based methods as the preliminary review for the optimal sites of the stations before the optimization applies.

금속 할로겐화물 페로브스카이트 기반 전계효과 트랜지스터 소자 연구 동향

조재혁,김명길,Jo, Jae-Hyeok,Kim, Myeong-Gil 한국전기전자재료학회 2022 전기전자재료 Vol.35 No.5

A Study on the Internalization of Sensor Technology by Comparison of IT Leading Countries

조재혁 한국인터넷정보학회 2020 인터넷정보학회논문지 Vol.21 No.3

The 4th Industrial Revolution is a revolutionary change through intelligence, big fusion and personalization, and the importance of sensor technology that is the basis of core technology is emerging. This study empirically analyzes the derivation of national strategy for R&D of sensor technology, and draws out the effect of technology internalization effort through strategic R&D activities on technical performance and further on national economy. The research and development results are calculated for each type of technology internalization, and the results of the research and development are verified to establish a structure that contributes to the national economic performance. As a national technology internalization strategy, considering its own R&D investment and joint research and development, we examine the impact of each factor on patents and GDP, focusing on causality and ripple effects. For causality analysis, Grandeur causality analysis shows that R&D investment and joint research and development in all countries have mutual causal relationship with GDP. The implications are as follows. First, it is necessary to establish the policy of national economic development through the internalization of technology and knowledge. Second, it is necessary to establish policies according to the type of knowledge internalization. Third, it will be necessary to create an ecosystem environment based on a virtuous relationship between knowledge internalization and national technology and economic development.

걷기운동과 달리기운동이 염증지표에 미치는 영향

조재혁 한국스포츠학회 2021 한국스포츠학회지 Vol.19 No.1

본 연구에서는 12주 동안의 걷기운동과 달리기운동이 CRP, IL-6, CPK와 같은 염증지표에 어떠한 영향을 줄 수 있는지를 살펴보고자 S 대학교에 재학 중이며, 내과·외과적으로 특정 질환이 없고 실험 변인인 CRP, IL-6, CPK가 모두 정상범주에 있는 20대 남자 대학생 12명을 대상으로 하였다. 12명 중 6명은 걷기운동집단, 6명은 달리기운동집단으 로 나누어 운동프로그램을 진행하였으며, 걷기운동집단은 20~30% 운동강도, 달리기운동집단은 60~70% 운동강도를 적용하여 다음과 같은 결론을 도출했다. 12주간의 걷기운동과 달리기운동은 20대 남성의 CRP, IL-6, CPK 모든 항목에 서 운동전보다 통계적으로 유의하게 감소시켰으며, 달리기운동집단에서 보다 큰 유의한 감소가 나타났다. 결론적으로 12주간의 걷기운동과 달리기운동은 염증지표 개선에 긍정적인 효과를 줄 수 있는 것으로 나타났다. 추후 연구에서는 다른 연령대를 대상으로 염증지표 개선을 위한 유산소운동 강도와 운동시간 등에 대한 연구와 중년 이상의 대상자들에게 유산 소운동 실천을 높일 수 있는 다양한 형태의 운동프로그램개발이 필요할 것으로 생각한다. In this study, in order to examine how walking and running exercise for 12 weeks can affect inflammatory Markers such as CRP, IL-6, and CPK, he is currently attending S University. Twelve male college students in their twenties, whose variables CRP, IL-6, and CPK were all in the normal category, were targeted. 6 out of 12 people were divided into walking exercise group and 6 people were divided into running exercise group, and 20-30% exercise intensity was applied to the walking exercise group, and 60-70% exercise intensity was applied to the running exercise group. Derived. The 12-week walking and running exercise were statistically significantly reduced in all items of CRP, IL-6, and CPK in men in their twenties than before exercise, and significantly decreased in the running exercise group. In conclusion, it was found that walking and running exercise for 12 weeks can have a positive effect on improving inflammation index. In future studies, it is necessary to study the intensity of aerobic exercise and exercise time to improve inflammation indicators for other age groups, and to develop various types of exercise programs that can increase the practice of aerobic exercise for middle-aged and older subjects.

운동과 스트레스 호르몬

조재혁 한국스포츠학회 2019 한국스포츠학회지 Vol.17 No.3

본 연구는 선행연구들을 통해 운동이 스트레스호르몬에 어떠한 영향을 미치는지를 살펴보고 스트레스호르몬을긍정적으로 변화시킬 수 있는 운동프로그램 개발의 기초적 자료를 제시하는 데 목적이 있다. 선행연구에서 살펴봤듯이유산소운동, 저항운동, 복합운동 등 운동의 형태와는 상관없이 규칙적인 운동은 스트레스 관련 호르몬의 분비를 높여주는것으로 알려져 있다. 일부 연구에서는 운동 후 스트레스 호르몬의 분비가 유의하게 증가하지 않았다는 결과가 있지만대부분 VO2max 50% 미만의 저강도 운동에서 나타나고 있다. 스트레스와 공존해야 한다면 가급적 정상적인 심호흡반응과 대사과정을 동반할 수 있는 운동이라는 도구를 통해 비교적 중강도 이상의 높은 강도라 할 수 있는 VO2max 50%~80% 의 강도로 운동을 시행하여 스트레스 호르몬의 수준을 전반적으로 높여주는 등 스트레스 상황과 유사한 상황에 노출시키고 이에 회복하는 과정을 반복하여 훈련하는 것이 바람직할 것으로 사료된다. 향후 스트레스 호르몬의 효율적인 증가가가능한 다양한 운동프로그램 개발이 필요할 것이며 무엇보다 운동 강도에 대한 중요성을 주지시키는 노력이 필요할 것으로 생각한다. The purpose of this study is to examine the effects of exercise on stress hormones through previous studies and to present basic data on developing exercise programs that can positively change stress hormones. As precedent research has shown, regardless of the form of exercise such as aerobic exercise, resistance exercise, and combined exercise, regular exercise is known to increase stress-related hormone secretion. Though some studies have shown that after exercise, stress-related hormone secretion does not significantly increase, most of them can be found in low intensity exercise which is less than 50% of VO2max. It is difficult for human to control their stress psychologically. If we have to coexist with stress, it is advisable to train by repeatedly exposing the stress-related environment that through exercise as a tool that can accompany normal deep breath reactions and metabolic process, a high-intensity exercise which range is VO2max 50%~80% is conducted to increase stress hormone and recovering process. From now on, it will be necessary to develop various exercise programs that can increase stress hormone efficiently. Also, it will be needed to make efforts to remind human of the importance of exercise intensity as well as exercise frequency and period.

점증부하운동시 운동자각도와 심폐기능과의 관련성

조재혁,임순길,이근일 한국운동영양학회 2000 Physical Activity and Nutrition (Phys Act Nutr) Vol.4 No.2

The purpose of this research is to provide a useful data for setting the optimal level of exercise by identifying two things; relationship between ratings of perceived exertion, heart rate(HR), oxygen uptake(VO_2), respiratory exchange ratio(RER) during graded exercise test/ Whether it is possible to estimate variables of cardiorespiratory function by utilizing ratings of perceived exertion or HR during graded exercise test. The subjects were 373 middle aged men - 197 of 30's and 176 of 40's- We measured their HR, VO_2, RER, and RPE during graded exercise test. The result from analysis of correlation and analysis of regression is as below 1. There is a significant relationship between RPE and HR for middle aged men of 30's and 40's during graded exercise test. 2. There is a significant relationship between RPE and V0_2 for middle aged men of 30's and 40's during graded exercise test. 3. There is a significant relationship between RPE and RER for middle aged men of 30's and 40's during graded exercise test. 4. There is a significant relationship between HR and VO_2 for middle aged men of 30's and 40's during graded exercise test. 5. There is a significant relationship between HR and RER for middle aged men of 30's and 40's during graded exercise test. Overall, there was a close relationship between RPE and variables of cardiorespiratory function for middle aged men of 30's and 40's during graded exercise test.