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Analysis of the Changes of the Vegetated Area in an Unregulated River and Their Underlying Causes
Chanjoo Lee,Donggu Kim 응용생태공학회 2018 Ecology and resilient infrastructure Vol.5 No.4
This study aims to investigate the changes in the riparian vegetated area in the Naeseong stream, an unregulated river, in order to analyze the main factors leading to these changes. For this purpose, the land surface cover in the channel area of the Naeseong stream was classified into 9 categories using past aerial photographs collected between 1970 and 2016, which recorded the long-term changes of the Naeseong stream. The increase or decrease in the vegetated area was calculated for each category using a pair of before and after images. The changes in the vegetated area were divided into 6 periods: the unvegetated channel period (1970 - 1980), the first rapid increase (1980 - 1986), the period of decrease due to flood (1986 - 1988), the period of repetitive man-induced disturbance and vegetation increase (1988 - 2008), the period of gradual vegetation increase (2008 - 2013), and the period of second rapid increase (2013 - 2016). Multiple regression analysis was performed using independent variables representing hydrology, climate, and geomorphology. The major variables found to be involved in the changes in the vegetated area of the Naeseong stream were the discharge during June - July, channel width, and temperature during April - June. Among the three variables, discharge and temperature were respectively the main independent variables in the downstream and the upstream reaches as per a single variable model. Channel width was the variable that distinguished the upstream and downstream reaches of the stream. The implication of the long-term increase in the vegetated area in the Naeseong stream was discussed based on the result of this study.
Lee, Jungmin,Lee, Chanjoo,Kim, Byungmin Elsevier 2009 MATERIALS AND DESIGN Vol.30 No.9
<P><B>Abstract</B></P><P>This study was designed to minimize the sensitivity of the data and experimental errors and to improve the accuracy in the reverse analysis of nano-indentation. This work was accomplished by using the various representative strains in a generalization of the loading curvature <I>C</I> and adopting only <I>C</I> and <I>W<SUB>p</SUB></I>/<I>W<SUB>t</SUB></I> as the independent parameters representing <I>P–h</I> curve in establishing a series of dimensionless functions. Finite element simulations of nano-indentation were performed for 140 combinations of each parameter (<I>E</I>,<I>σ<SUB>y</SUB></I>,<I>n</I>,<I>ν</I>) expressing the elastic–plastic behaviors of the universal engineering metals. The dimensionless functions established from the computational results were examined with different materials (Al6061-T6, AISI 1010, 1045 and copper (99%)). Finally, the relation between the residual indentation profiles and the strain hardening exponents of the indented materials was briefly investigated to verify the reliability of the reverse analysis.</P>
Lee, Chanjoo,Kim, Donggu Korean Society of Ecology and Infrastructure Engin 2018 Ecology and resilient infrastructure Vol.5 No.4
This study aims to investigate the changes in the riparian vegetated area in the Naeseong stream, an unregulated river, in order to analyze the main factors leading to these changes. For this purpose, the land surface cover in the channel area of the Naeseong stream was classified into 9 categories using past aerial photographs collected between 1970 and 2016, which recorded the long-term changes of the Naeseong stream. The increase or decrease in the vegetated area was calculated for each category using a pair of before and after images. The changes in the vegetated area were divided into 6 periods: the unvegetated channel period (1970 - 1980), the first rapid increase (1980 - 1986), the period of decrease due to flood (1986 - 1988), the period of repetitive man-induced disturbance and vegetation increase (1988 - 2008), the period of gradual vegetation increase (2008 - 2013), and the period of second rapid increase (2013 - 2016). Multiple regression analysis was performed using independent variables representing hydrology, climate, and geomorphology. The major variables found to be involved in the changes in the vegetated area of the Naeseong stream were the discharge during June - July, channel width, and temperature during April - June. Among the three variables, discharge and temperature were respectively the main independent variables in the downstream and the upstream reaches as per a single variable model. Channel width was the variable that distinguished the upstream and downstream reaches of the stream. The implication of the long-term increase in the vegetated area in the Naeseong stream was discussed based on the result of this study.
중학생의 직업계고 진학 선택을 위한 경기도 직업계고 교원의 진로교육 지원 활동에 대한 업무 인식 조사
이찬주(Chanjoo Lee),김대들(Daedeul Kim) 한국기술교육학회 2021 한국기술교육학회지 Vol.21 No.3
본 연구는 직업계고 교원이 인식하는 중학교 진로교육 지원 활동에 대한 수행 실태와 직업계고 신입생 확보에 도움이 되는 정도, 그리고 지원 활동에 대한 업무 적절성과 어려움 정도를 분석하는 것이다. 이를 위해서 설문지를 개발하여 조사하였으며, 조사 대상은 경기도의 모든 직업계고(108교) 교원을 대상으로 온라인 설문지를 배부하여 수집된 778부를 분석하였으며, 연구 결과를 제시하면 다음과 같다. 첫째, 직업계고 교원 중 직업계고에서 제공하는 중학교 진로교육 지원 활동을 수행한 응답자는 706(90.8%)명이며, 이러한 지원 활동이 직업계고 신입생 확보에 도움이 되는 정도에 응답한 평균은 3.62로 나타났다. 중학교 진로교육 지원 활동별 신입생 확보에 도움이 되는 정도가 높은 내용은 ‘우리 학교 견학(실습실 투어 등)’ 3.99, ‘중학교 교실별로 찾아가는 직업계고 학교 설명회’3.96, ‘우리 학교(직업계고)에 찾아오는 전공(학과) 체험 활동’ 3.94 등의 순으로 나타났다. 둘째, 직업계고 교원은 현재 직업계고 제공 중학교 진로교육 지원 활동에 대한 업무 수행 난이도는 3.36으로 응답하였다. 진로교육 지원 활동별 업무 수행 난이도가 높은 내용은 ‘우리 학교 졸업생이 근무하는 산업체 견학’ 3.92, ‘중학교로 찾아가는 직업계고 학교 설명회’ 3.74, ‘중학교 교실별로 찾아가는 직업계고 학교 설명회’ 3.73 등의 순으로 나타났다. 셋째, 직업계고 교원은 현재 직업계고 제공 중학교 진로교육 지원 활동에 대한 업무 적절성 정도는 3.09로 응답하였다. 진로교육 지원 활동별 업무 적절성 정도가 높은 내용은 ‘우리 학교 견학(실습실 투어 등)’ 3.53, ‘우리 학교로 찾아오는 직업계고 진로 상담’ 3.49, ‘우리 학교(직업계고)에 찾아오는 전공(학과) 체험 활동’ 3.46, ‘우리 학교(직업계고)로 찾아오는 학교(학과) 설명회’ 3.46 등의 순으로 나타났다. This study aims to analyze the performance of assistant activity for middle school career education, the degree of help to secure of vocational high school freshmen and task adequacy of assistance activity and level of difficulty perceived by vocational high school teachers. For the foregoing, this study developed a survey questionnaire and distributed online to all the teachers of vocational high schools(108 schools) in Gyeonggi-do, and analyzed 778 sheets collected. Study results are as follows. First, the ratio of performance (frequency of response) of assistant activity for middle school career education by vocational high school teachers was 90.8% (706 respondents). as for the level of usefulness of assistant activity for middle school career education for attracting freshmen, vocational high school teachers replied as 3.62. ‘Visiting our school (Laboratory tour etc.)’ 3.99 placed first in the level of usefulness of assistance activities, followed by ‘Vocational high school presentation visiting middle school classrooms’ 3.96, ‘Major (department) experience activity visiting our school (vocational high school)’ 3.94. etc. appear. Second, the vocational high school teachers responded that the job performance difficulty for the middle school career education support activities currently provided by vocational high schools was 3.36. The highest degree of task difficulty among assistance activities was ‘Visiting companies where graduates of our school work’ 3.92 topped the list of the level of task performance of assistance activities, followed by ‘Vocational high school presentation visiting middle schools’ 3.74, ‘Vocational high school presentation visiting middle school classrooms’ 3.73. etc. appear. Third, vocational high school teachers answered 3.09 as to the level of task adequacy for the middle school career education support activities currently provided. The highest level of task adequacy among assistance activities was ‘Visiting our school (Laboratory tour etc.)’ 3.53, followed by ‘Vocational high school career counseling visiting our school’ 3.49, ‘Major (department) experience activity visiting our school (vocational high school)’ 3.46, ‘School (department) presentation visiting our school (vocational high school)’ 3.46. etc. appear.