DP590 고장력 강판 성형을 위한 굽힘 금형 설계에 관한 연구

천정필,안동규 한국소성∙가공학회 2024 소성가공 : 한국소성가공학회지 Vol.33 No.1

A high strength steel sheet (HSSS) has widely used to improve the specific rigidity of parts and the safety of the passenger in automotive industries. However, the HSSS is difficult to manufacture precise parts through a forming process due to the reduced elongation and the increased elastic recovery. The goal of the paper is to investigate the improved design of bending dies for DP590 HSSS. The over forming type bending dies with cam systems added to the side of the formed part is proposed to improve the quality of the part. The effects of the die design and the forming parameter on formability and elastic recovery characteristics is examined using finite element analyses (FEAs). From the results of FEAs, proper die design and forming parameters are predicted.

기혼 여성의 스포츠센터 이용과 가정생활만족의 관계

천정필 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.6

The purpose of this paper is to identify the relationship between the use of the sports center and family life satisfaction in the case of married women, To fulfil this purpose, married women, residing in Seoul as of 2004, were chosen to be a population and then, among all of them, 200 women were selected by the stratified cluster random sampling method and the final date for this paper were 191 out of 200. The statistical method for this paper were one-way ANOVA, for the degree of the use of the sports center by married women and family life satisfaction discrepancies, and multiple regression analysis, for the degree of the use of the sports center by the married women and family life satisfaction relationship. As a result of this study, the following has been concluded by the analysis of the relationship between the use of the sports center and family life satisfaction. First, according to the demographic feature variable, there are some partial differences between the degree of the use of the sports center by married women and family life satisfaction. With close examination of this, the satisfaction of family life is different in regards to age and income. Second, there are some partial relationships between the degree of the use of the sports center by married women and family life satisfaction.

12주간의 운동 트레이닝이 비만청소년의 신체구성 지표와 심혈관 질환 위험 지표에 미치는 영향

천정필 한국스포츠리서치 2005 한국 스포츠 리서치 Vol.16 No.6

운동형태가 비만청소년의 대사호르몬에 미치는 영향

천정필(Cheon Jeong-Pil),이상호(Lee Sang-Ho),한상철(Han Sang-Chul) 한국체육과학회 2006 한국체육과학회지 Vol.15 No.4

This study was performed to investigate the effect of 12 weeks exercise training which divided aerobic and resistance exercise on the metabolic hormone in obese adolescents. The subjects were 30 who were divided into control group(n=10), aerobic exercise group(n=10) and resistance exercise group(n=10) according to the presence of training. The components of the metabolic hormone were assessed insulin. cortisol. leptin, growth hormone twice, prior to and after the 12 week training period. Aerobic exercise training consisted of treadmill walking. running at 60-70% of HRR(80 minutesㆍday-1, 3 daysㆍweek-1) and resistance training performed three sets of lifts using 60-70% of 1RM to complete each of 12 rep/3set (3 daysㆍweek-1) during 12 weeks. The results of the present study were as follows: the components of the metabolic hormone. insulin(p<.01), cortisol(p<.01), leptin(p<.001), GH(p<.001) significantly decreased in the aerobic and resistance exercise group. and all other components showed positive changes as well. On the other hand. in the control group, most of the components did not change significantly. And there was significantly differences of training effect on insulin(p<.001). leptin(p<.001). GH(p<.001) between those three groups and there was no differences of training effect on cortisol between those three groups. In conclusion, when applying aerobic. resistance training appeared positive effects on metabolic hormone.

탄성회복이 감소되는 굽힘 성형 금형 설계

천정필(J. P. Cheon),안동규(D.-G. Ahn) Korean Society for Precision Engineering 2022 한국정밀공학회 학술발표대회 논문집 Vol.2022 No.10

임용시험의 교과내용학 문항 출제경향 분석

천정필(Jeong Pil Cheon),권문호(Munho Kwon),최호명(Ho-Meoyng Choi) 한국물리학회 2022 새물리 Vol.72 No.4

본 연구에서는 중등학교교사 임용후보자 선정경쟁시험(이하 임용시험)의 물리 임용시험 문항 중 교과내용학 문항에 대한 출제 경향을 분석하였다. 임용시험에 포함된 기본이수 과목은 역학, 전자기학, 양자역학, 파동 및 광학, 열 및 통계물리, 그리고 현대물리학이다. 먼저 2002학년도부터 2021학년도까지 임용시험에 출제된 384개 문항을 한국교육과정평가원이 개발한 ‘평가 영역 및 평가 내용 요소’ 기준에 따라 분류하여 출제 경향을 분석하였다. 또한 임용시험과 2015 개정 과학과 교육과정 및 임용시험과 사범대학의 교육과정을 각각 비교분석 하였다. 주요 연구 결과는 다음과 같다. 첫째, 임용시험의 교과내용학에서 역학이 가장 많이 출제되었고, 현대물리학이 가장 적게 출제되었다. 둘째, 2015 개정교육과정의 영역별 성취기준 비율과 임용시험 출제 비율에 차이가 났다. 셋째, 임용시험과 사범대학 교사양성 교육과정의 영역별 편성 비중이 일치하지 않았다.<br/> A trend analysis was conducted on content knowledge problems in the Secondary School Physics Teacher Selection Test (SSPTST). The basic completion subjects in the SSPTST comprised classical mechanics, electromagnetism, quantum mechanics, wave and optics, thermal and statistical physics, and modern physics. We analyzed 384 problems during the academic period 2002–2021 based on the “Evaluation Areas and Evaluation Content Elements” developed by the Korean Institute of Curriculum and Evaluation. Furthermore, comparative analyses between the SSPTST and 2015 Revised National Science Curriculum (RNSC) as well as the SSPTST and curricula of Colleges of Education were conducted. The main results are as follows. (1) The most and least frequently tested subjects in the SSPTST are classical mechanics and modern physics, respectively. (2) There are some differences between the proportion of achievement standards for each subject in the 2015 RNSC and problems for the corresponding subject in the SSPTST. (3) The proportion of problems for each subject in the SSPTST is not in line with the number of credits for the corresponding subject offered in teachers’ colleges.

스프링 백이 최소화되는 차량용 U-굽힘 금형 설계에 관한 연구

천정필(Jeong Pil Cheon),안동규(Dong Gyu Ahn) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.6

현재 급변하는 자동차 산업 시장에서는 빠른 제작 및 납기, 낮은 단가와 품질의 우수성을 요구하고 있다. 차체의 강성을 보강하기 위한 구조물 중 U 자 형태의 판넬은 대표적으로 Member, Reinf 및 Dash 등이 있으며 차체의 강성 보강에 매우 중요한 구조물 중 하나로 특히 안전과 밀접한 관계를 갖는 차량용 차체 부품이다. 기존방식의 U-굽힘 금형의 경우 제품에 미리 스프링 백(Spring back) 을 예상하여 상,하 펀치에 보정 각도(θ)를 적용하고 실제 제품보다 Go상태로 되게끔 하여 스프링 백을 방지하는게 전부였다. 하지만 제품의 정도에 문제가 발생 할 경우 품질 육성 등의 여러 가지 문제가 발생한다. 본 연구에서는 스프링 백을 최소화시키고 품질 육성에 들어가는 비용 및 시간을 절감시키기 위한 스프링 백 개선 금형을 설계하고 U자형 판넬의 스프링 백을 유한요소 해석을 통하여 예측하고자 한다. 금형 설계는 NX UG 7.5 CAD 프로그램을 이용하였으며 기존에 사용되는 U-굽힘 금형 구조에 각도(θ) 45°에 stroke 5mm 인 수평 캠을 적용하였다. 45°수평 캠 은 Stroke block 이란 부품과 서로 연동이 되며 부품의 높이 값을 조절하고 캠의 Stroke를 제어 하여 금형 자체에서 스프링 백을 수정할 수 있도록 설계되었다. 완성된 제품의 검증은 상용 해석 프로그램인 AUTO FORM R7을 이용하였다. 판넬의 소재는 차량용 차체에 사용되고 있는 고장력 강판인 DP590 물성 데이터를 해석모델에 적용하였다. 판넬의 두께 4t 를 적용하여 해석을 진행한 결과 설계수치인 캠 stroke 5mm 보다 0.5mm 덜 진입한 상태인 4.5mm 상태에서 허용오차 ±0.5 mm 이내에 결과치가 도출되었다. 또한 소재의 두께가 스프링 백에 미치는 영향을 알아보기 위해 판넬의 두께에 따른 해석을 진행하였으며, 소재의 두께가 증가할 경우 Stroke 의 진입량을 감소 시켜야 허용 오차를 만족하는 결과가 도출되었다. 이러한 결과를 통해 Stroke block 의 높이 값 조절 및 캠 Storke 제어가 가능한 금형을 사용할 경우 U 자형태의 차체 판넬의 스프링 백에 대한 오차를 해소할 수 있을 것으로 사료된다. [그림 본문 참조]

고등학교 태권도선수의 운동경력에 따른 운동상해 분석

한상철,천정필 한국스포츠리서치 2005 한국 스포츠 리서치 Vol.16 No.1

12주간의 유,무산소성 운동이 비만중학생의 체력요소에 미치는 영향

이상호(Sang Ho Lee),천정필(Jeong Pil Cheon) 한국사회체육학회 2007 한국사회체육학회지 Vol.0 No.30

This study was performed to investigate the effect of 12 weeks exercise training which divided aerobic and resistance exercise on the physical fitness in obese adolescents. The subjects were 30 who were divided into control group(n=10), aerobic exercise group(n=10) and resistance exercise group(n=10) according to the presence of training. The Datas were measured, as were the physical fitness components including maximal aerobic power, muscular strength, muscular endurance, flexibility, and power which were assessed twice, prior to and after the 12 week training period. Aerobic exercise training consisted of treadmill walking, running at 60-70% of HRR(90 minutes·day-1, 3 days·week-1) and anaerobic training performed three sets of lifts using 60-70% of 1RM to complete each of 12 rep/3set (3 days week-1) during 12 weeks. The results of the present study were as follows: as for the components of the physical fitness, maximal aerobic power,(p<.001) muscular strength(p<.001), muscular endurance(p<.001), flexibility(p<.001), and power(p=.002) significantly increased in the aerobic and resistance exercise group, especially muscular endurance and flexibility and all other components showed positive changes as well. On the other hand, in the control group, most of the components did not change significantly. And there was significantly differences of training effect on all other physical fitness factors between those three groups. These results support that long term exercise training program which divided aerobic and anaerobic training can be effective regimen to prevent cardiovascular disease in obese adolescents. In conclusion, the data from this study reveals that exercise for those who have the metabolic syndrome is beneficial for the treatment of the metabolic syndrome. Furthermore one can say that lifestyle modification included exercise and diet education is an important consideration for someone who has the metabolic syndrome.

운동유형이 대사증후군 구성요소에 미치는 영향

한상철(Sang Chul Han),천정필(Jeong Pil Cheon),이상호(Sang Ho Lee) 한국발육발달학회 2007 한국발육발달학회지 Vol.15 No.2

This study was performed to investigate the effect of 12 weeks exercise training which divided aerobic and resistance exercise on the components of the metabolic syndrome in obese adolescents. The subjects were 30 who were divided into control group(n = 10), aerobic exercise group(n = 10) and resistance exercise group (n = 10) according to the presence of training. The components of the metabolic syndrome consisting of plasma glucose, blood pressure, triglyceride, HDL-cholesterol, and waist circumference were measured twice, prior to and after the 12 week training period. Aerobic exercise training consisted of treadmill walking, running at 60-70% of HRR(90 minutesday-1, 3 daysweek-1) and resistance training performed three sets of lifts using 60-70% of 1RM to complete each of 12 rep/3set (3 daysweek-1) during 12 weeks. The results of the present study were as follows: As for the components of the metabolic syndrome, waist circumference(p<.01), systolic blood pressure(p<.001), diastolic blood pressure(p<.001), triglyceride(p<.05) significantly decreased and HDL-cholesterol (p<.001) significantly increased in the aerobic and resistance exercise group, and all other components showed positive changes as well. On the other hand, in the control group, most of the components did not change significantly. And there was significantly differences of training effect on waist circumference, diastolic blood pressure, triglyceride, and HDL-C between those three groups but systolic blood pressure, HDL-cholesterol did not significant. These results support that long term exercise training program which divided aerobic and resistance training can be effective regimen to prevent cardiovascular disease in obese adolescents. In conclusion the data from this study reveals that exercise for those who have the metabolic syndrome is beneficial for the treatment of the metabolic syndrome. Furthermore one can say that lifestyle modification included exercise and diet education is an important consideration for someone who has the metabolic syndrome.