단일 구형 기포의 수학적 모델에 대한 수치적 해석 모델

강동근,양현익,Kang, Dong-Keun,Yang, Hyun-Ik 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.1

Cavitation is described by formation and collapse of the bubbles in a liquid when the ambient pressure decreases. Formed bubbles grow and collapse by change of pressure, and when they collapse, shockwave by high pressure is generated. In general, bubble behavior can be described by Rayleigh-Plesset equation under adiabatic or isothermal condition and hence, phase shift by the pressure change in a bubble cannot be considered in the equation. In our study, a numerical model is developed from the mathematical model considering the phase shift from the previous study. In the developed numerical model, size of single spherical bubble is calculated by the change of mass calculated from the change of the ambient pressure in a liquid. The developed numerical model is verified by a case of liquid flow in a narrow channel.

옐로카펫 설치효과에 대한 조사연구 - 어린이 횡단대기 행동을 중심으로 -

강동근 ( Kang Dong-keun ) 한국도로교통공단 2017 교통안전연구 Vol.36 No.-

Domestic traffic accidents in children have been steadily declining but are still insufficient. In this study, we conducted a questionnaire survey and a field survey of the Yellow Carpet for the purpose of verifying the installation effect of Yellow Carpet, which is one of the measures to reduce children's traffic accidents. As a result of the questionnaire survey, the overall effect of the Yellow Carpet was evaluated positively. Especially, the evaluation of the person who knew the Yellow Carpet in advance was more positive than the case of not. As a result of the field survey, the rate of waiting in the Yellow Carpet of the crosswalk where the Yellow Carpet was installed was high, and the rate of waiting in the Yellow Carpet of the children was higher than that of the middle school student and above. This is a result of showing the feasibility of installing the carpet. The results of this study have demonstrated the necessity and effectiveness of Yellow Carpet for children's traffic safety, especially crossing accident prevention. In particular, considering the positive result of the Yellow Carpet awareness and the waiting behavior of the children on the crosswalk, it is believed that the installation of the Yellow Carpet is secured.

고속도로 개방형 적재불량 화물차 위험성 실태조사

강동근 ( Kang Dong-keun ),이세원 ( Lee Se-won ) 한국도로교통공단 2020 교통안전연구 Vol.39 No.-

This study evaluated the risks associated with the use of open loaded box trucks using a field investigation and survey. Results showed that less than 30% of loads on open box trucks are securely fixed and operated on the highway, and approximately 70% of truck drivers experienced cases of falling or overhanging loads during transportation, which were found to have caused or almost caused traffic accidents. Moreover, the risk of accidents increased due to the driving behavior exhibited by other non-truck drivers trying to avoid poorly loaded open loaded trucks. Both non-truck drivers and truck drivers recognized the dangers associated with open loaded box trucks and the high risk of traffic accidents with such trucks on the highway.

세계화와 기업 간 생산성 불균등도

강동근(Kang, Dong Keun),김종일(Kim, Jong Il) 동국대학교 사회과학연구원 2015 사회과학연구 Vol.22 No.1

본 연구에서는 소득불평등 지수인 지니계수를 이용하여 제조업부문에서 산업별 기업 간 생산성 뷸균등도의 추이를 분석하고, 이러한 기업 간 생산성 불균등도에 세계화, 자본자유화, 기술혁신 등이 미치는 영향을 분석하였다. 분석의 주요 결과는 다음과 같다. 첫째, 기업 간 생산성불균등도의 전체적인 추이는 꾸준히 상승하는 형태였으며, 경제위기 시에 기업 간 생산성 불균등도가 더 심화되고 있었다. 둘째, 산업에 관계없이 전 산업에서 기업 간 생산성 불균등도가 확대되고 있었으며, 경공업에 속하는 산업에서의 불균등도 심화가 두드러지게 나타나고 있었다. 셋째, 기업 간 생산성 불균등도에 미치는 영향을 분석한 결과, 세계화가 기업 간 생산성 불균등도 심화에 유의한 영향을 미치는 것으로 확인되었다. This paper applies the measures of income distribution to the case of productivity distribution of firms to investigate the productivity dispersion of firms in Korea from 1990 to 2013. This paper estimates Gini coefficient by using the firm-level data from KIS VALUE and examines the effects of globalization on productivity inequality using panel data. The main findings are as follows. First, the productivity dispersion of firms has been widened in terms of Gini coefficient since the 1990s. Second, the productivity dispersion of firms has been widened regardless of industry. Third, the empirical results show that export, outward direct investment and R&D variables may play an important role for productivity dispersion.

화물차의 적재물 고정방법 개선방안에 관한 조사 연구

강동근 ( Kang Dong-keun ) 한국도로교통공단 2016 교통안전연구 Vol.35 No.-

This study is to show the present road traffic law for the suggestion improvement plan of the truck' load fixation way. Therefore, It is investigated the legal status of domestic and abroad, Due to the stacking bad traffic accident and enforcement status, The truck faulty in actual road vehicles Survey, Truck and regular driver's targets carried out the survey, The following improvement plan showed the contents, and which are as follows : First, It must be required by all means some plan to use the cover for the load to be spreaded gravel and sand by windy altogether. Second, It is the plan to be mandatory use only in the case of a typical truck cover. Third, It is the plan to be mandatory a cover of the truck in the driving of the highway. Since, The improvement is that it's been suggested to be embodiment the safety measure proposed to many driver in the present road traffic law for the truck' load fixation way. The traffic accident itself due to the load of the truck is not usual but it's been occurred by the poor fixation, but these accidents in that safety measures are preventive case certainly done possible for the load to prevent accidents caused by the truck load faulty. It is expected to be contributed in the traffic safety of the future.

옐로카펫이 차량 속도에 미치는 영향에 관한 조사연구

강동근 ( Kang Dong-keun ) 한국도로교통공단 2019 교통안전연구 Vol.38 No.-

This study verified the speed reduction effect due to the installation of a yellow carpet through a practical experiment. The effect of deceleration on the crosswalk wherein the yellow carpet was installed has also been studied. Analysis of the speed and the opposite side of the crosswalk wherein the yellow carpet was installed and the speed of the crosswalk wherein the yellow carpet was not installed revealed a high deceleration rate and low passing speed. Although yellow carpets are usually installed around school areas, it cannot be concluded that they are the only effective tool in cases where the results of actual driving tests are expected to be evaluated positively.

기대이론을 이용한 고령자 교통사고 예측모형개발

강동근 ( Kang Dong-keun ) 한국도로교통공단 2015 교통안전연구 Vol.34 No.-

The purpose of this study is to predict the number of traffic accidents and driver's license holders of older drivers using rational expectation theory. The results are as follows: First, look at the elderly driver's accidents can predict the results, the proportion of accident 65-68 years old group & 69-72 years old group was expected to decrease, the proportion of accident 73-year-older group was expected to increase rapidly. Second, look at the elderly driver's license holders can predict the results, the proportion of 73-year-older group was expected to be increased significantly, especially the proportion of 73-year-older group was expected to rise to 431,404(10.5%) in 2020 in 2014 86,332(4.2%).

온도효과를 고려한 탄소나노튜브 공진기의 비선형 동적 특성 분석

강동근(Dong-Keun Kang),마이 덕 다이(Mai Duc Dai),김상훈(S. H. Kim),김유찬(Y. C. Kim),양현익(H. k Yang),김창완(Chang-Wan Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-2

경증치매노인의 기능적 체력 및 인지기능 향상을 위한 복합 수중운동프로그램 개발

강동근 ( Dong Keun Kang ),박정연 ( Jeong Yeon Park ),정주하 ( Joo Ha Jung ),박정준 ( Jung Jun Park ) 한국운동생리학회 2015 운동과학 Vol.24 No.4

PURPOSE: Aquatic exercise is popular among the elderly because its stress on joint is less compared to other exercises. The purpose of this research was to determine the effect of combined aquatic exercise with music therapy, art therapy and learning therapy on improvements of functional fitness and cognitive function in elderly with mild dementia. METHODS: Twenty two women, aged 65 to 74, participated in this study. They were randomly divided into combined aquatic exercise group(CAEG, n=12) or normal aquatic exercise group(NAEG, n=10). Both group performed exercise 60 min/day, 3 days/week, for 16 weeks at the intensity of 10-13 RPE. The variables of funcional fitness test and CERAD-K``s 10 task tests were used to measureed all the subjects. All data was analyzed by independent t-test, two-way repeated ANOVA and paired t-test by using SPSS 22.0. RESULTS: In the case of functional fitness, the CAEG improved significantly in 2 kg dumbbell curl, 2.44 m up-and go, 6-min walk and the NAEG improved 2 kg dumbbell curl, 2.44 m up-and go. In the case of cognitive function improved significantly all 10 task tests, while NAEG was no significant difference all 10 task tests. CONCLUSIONS: It is concluded that the effect of CAEG is superior to NAEG in improvements of functional fitness and cognitive function by increasing sense of sight, hearing, touching, memorizing. Thus, it suggests that combined aquatic exercise is an appropriate exercise, especially for elderly with mild dementia.

단일 구형 기포의 수학적 모델에 대한 수치적 해석 모델

강동근(Dong-Keun Kang),양현익(Hyun-Ik Yang) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.6

Cavitation is described by formation and collapse of the bubbles in a liquid when the ambient pressure decreases. Formed bubbles grow and collapse by change of pressure, and when they collapse, shockwave by high pressure is generated. In general, bubble behavior can be described by Rayleigh-Plesset equation under adiabatic or isothermal condition and hence, phase shift by the pressure change in a bubble cannot be considered in the equation. In our study, a numerical model is developed from the mathematical model considering the phase shift from the previous study. In the developed numerical model, size of single spherical bubble is calculated by the change of mass calculated from the change of the ambient pressure in a liquid. The developed numerical model is verified by a case of liquid flow in a narrow channel.