지반-구조물 경계면의 루핑 포텐셜 평가

박정만(Jeongman Park),김강현(Kanghyun Kim),신종호(Jongho Shin) 한국지반환경공학회 2018 한국지반환경공학회논문집 Vol.19 No.3

파이핑은 가장 대표적인 제방의 붕괴 유형으로 불투수성 수리구조물과 지반 경계면에서 Backward Erosion Piping인 루핑(Roofing)이 흔하게 발생한다. 루핑에 대한 검토는 주로 경험적 방법인 크립비를 이용하지만 이는 지반-구조물 경계면의 특성을 고려하지 않는 문제가 있다. 본 연구에서는 지반-구조물 경계면 특성이 루핑에 미치는 영향을 평가하기 위해 모형시험과 수치해석을 이용하여 파이핑 위험도를 고찰하였다. 모형시험에서 경계면 조도가 커질수록 파이핑 포텐셜이 감소함을 확인하였으며, 이를 수치해석에 적용하였다. 기존의 일반적인 수치해석방법은 수위차만을 고려하므로 경계면에서의 입자거동을 적절히 모사할 수 없다. 논문에서는 침투해석을 통해 침투력을 구하고, 입자해석기법을 이용해 파이핑의 입자거동을 모사한 침투-입자거동 연계해석을 수행하여 지반-구조물 경계면 조건에 따른 루핑 포텐셜을 조사하였다. 해석결과 경계면의 조도가 감소할수록 루핑 발생 확률이 증가함을 확인하였다. Piping is one of the most frequently occurring collapse type of a levee, and is often caused by roofing (backward erosion piping) at the ground-structure interface. Roofing is generally evaluated using creep ratio. However, creep ratio does not take into account the characteristics of the ground-structure interface. In this study, the roofing risk was investigated by using model test and numerical analysis considering the ground-structure interface characteristics. In the model test, it was confirmed that the piping potential decreased as the interface roughness increased, and this was applied to the numerical analysis. Existing numerical methods can not adequately simulate the particle behavior at the ground-structure interface because only the water level difference is considered. In this paper, particle behavior at the interface was investigated by performing seepage analysis and then, carrying out particle analysis technique simulating the boundary condition of the ground-structure interface. Analysis results have shown that the roofing resistance decreases as the ground-structure interface roughness decreases.

2 stage CVT 가속성능 개선 변속 제어 알고리즘 개발

박정만(Jeongman Park),지건(Jian Ji),권오은(Oheun Kwon),채민재(Minjae Chai),심장선(Jangsun Sim),임광혁(Kwanghyuk Lim),조서연(Seoyeon Cho),김현수(Hyunsoo Kim) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11

In this study, a 2 stage CVT shift control algorithm is proposed for kickdown shift to improve acceleration performance. The proposed shift control algorithm controls a desired secondary pressure to increase a variator shift speed and a release clutch pressure to shift a planetary gear smoothly. In order to evaluate acceleration performance of the control algorithm, a 2 stage CVT vehicle simulator is developed based on MATLAB/Simulink and SimDriveline. It is found from the simulation results that an acceleration performance is improved in terms of an increase of variator shift speed.

[응용논문] 급발진 추정사고에서 운전자의 페달 오조작에 관한 사례 연구

박종진(Jongjin Park),박정만(Jeongman Park?),이연섭(Yeonsub Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.11

In Korea, the suspected case of sudden unintended acceleration(SUA) of vehicles has become a social issue, according to the number of SVA cases has gradually increased. The majority of the drivers who experienced SUA accident insisted that they hardly pressed the brake pedal. However, upon inspection of the vehicle, it is found a broken acceleration pedal, a stuck acceleration pedal in the pad, and a footprint on the acceleration pedal. In America, the National Highway Traffic Safety Administration(NHTSA) announced the 49 CFR Part 563 from September 1, 2012 to recommend the installation of the Event Data Recorder(EDR) and the standard data. A similar enforcement decree with Part 563 was announced in December 19, 2015 in Korea. According to the enforcement decree of EDR, it is allowed to retrieve a record of the driver’s operation before the event triggered. In addition, the installation of the digital tachograph(DTG) is regulated for business purpose vehicles on January 1, 2014. The possibility of a driver’s incorrect pedal operation could be validated through DTG data analysis, video data record(VDR) in vehicles, and CCTV records. In the 269 cases of SUA in 6 years(2013 to 2018), 203 cases were confirmed to be the drivers pedal maloperation and 173 cases involved drivers in their 50s and older. In the 203 cases involving drivers maloperation, the broken pedal and the jammed pedal with the vehicle mat case were confirmed. Therefore, it is required to improve vehicle safety system, regulation, and advanced driver training for preventing the maloperation of the acceleration pedal.

단지공사에 있어서 고정익 드론과 회전익 드론의 위치정확도 비교

박찬석(Chanseok Park),이석배(Suk-Bae Lee),백충종(Chung-Jong Baek),박정만(Jeongman Park) 대한공간정보학회 2021 한국지형공간정보학회 학술대회 Vol.2021 No.6

급발진 추정사고에서 운전자의 페달 오조작에 관한 사례 연구

박종진(Jongjin Park),박정만(Jeongman Park),이연섭(Yeonsub Lee) 한국자동차공학회 2019 한국자동차공학회 부문종합 학술대회 Vol.2019 No.5

다중 및 연쇄 추돌사고에서의 EDR 기록정보의 활용

임상현(Sanghyeon Lim),김종혁(Jonghyuk Kim),오원택(Wontaek Oh),박정만(Jeongman Park),박종진(Jongjin Park),최지훈(Jihun Choi),박하선(Hasun Park),박종찬(Jongchan Park) 한국자동차공학회 2018 한국자동차공학회 부문종합 학술대회 Vol.2018 No.6

연료 조성에 따른 대체 연료의 공연비 산정법의 비교

박찬준,엄인용,이정만 서울産業大學校 2005 논문집 Vol.54 No.1

This paper is to compare the various Air-Fuel ratio determination methods for alternative fuels. In the previous work, expansion of Eltinge chart, unburned hydrocarbon compensation, comparison of the results from various methods were discussed. It has been also concluded that Eltinge method might be regarded as the most general equation, of AFR determination among the existing ones. In the recent years, however, increasing demand for the environmental preservation, including global warming-up protection, and energy conservation lead to introduce the alternative fuel to the internal combustion engine. Therefore, the exact calculations of AFR for these fuels are needed. Especially, for the fuel that contains oxygen, all AFR calculation equations except Eltinge have to be re-formulated. In this paper, the AFR for alternative fuel were calculated by re-formulated carbon balance, accuracy of which was already confirmed, and linear equations, which are newly proposed by statistical method for each fuel. The results show that AFRs based on carbon balance have a little more error compared with gasoline, however, the accuracy is enough for this formula to apply to various fuel. The proposed linear equation also have excellent accuracy up to X = 1.2.

투표 기반 서술형 주관식 답안 자동 채점 모델의 설계 및 구현

허정만(Jeongman Heo),박소영(So-Young Park) 한국컴퓨터정보학회 2013 韓國컴퓨터情報學會論文誌 Vol.18 No.8

본 논문에서는 투표기법을 이용하여 서술형 주관식 문제에 대한 학습자 답안을 자동으로 채점하는 모델을 제안한다. 제안하는 방법은 모델 구축 비용을 줄이기 위해서, 문제 유형별로 세분화하여 서술형 주관식 답안 자동 채점 모델을 따로 구축하지 않는다. 제안하는 방법은 서술형 주관식 답안 자동 채점에 유용한 자질을 추출하기 위해서, 모범 답안과 학습자 답안을 비교한 결과를 바탕으로 다양한 자질을 추출한다. 제안하는 방법은 답안 채점 결과의 신뢰성을 높이기 위해서, 각 학습자 답안을 여러 기계학습 기반 분류기를 이용하여 채점하고, 각 채점 결과를 투표하여 만장일치로 선택한 채점 결과를 최종 채점 결과로 결정한다. 실험결과 기계학습 기반 분류기 C4.5만 사용한 채점 결과는 정확률이 83.00%인데 반해, 기계학습 기반 분류기 C4.5, ME, SVM에서 만장일치로 선택한 채점 결과는 정확률이 90.57%까지 개선되었다. TIn this paper, we propose a model automatically scoring a student's answer for a descriptive problem by using a voting method. Considering the model construction cost, the proposed model does not separately construct the automatic scoring model per problem type. In order to utilize features useful for automatically scoring the descriptive answers, the proposed model extracts feature values from the results, generated by comparing the student's answer with the answer sheet. For the purpose of improving the precision of the scoring result, the proposed model collects the scoring results classified by a few machine learning based classifiers, and unanimously selects the scoring result as the final result. Experimental results show that the single machine learning based classifier C4.5 takes 83.00% on precision while the proposed model improve the precision up to 90.57% by using three machine learning based classifiers C4.5, ME, and SVM.

풀이 과정을 답지로 이용한 시험 방식의 학습 효과

임정만(Jeongman Lim),박주용(Jooyong Park) 한국인지과학회 2010 인지과학 Vol.21 No.4

본 연구에서는 수학 학습을 위한 평가 도구로 풀이 과정을 답지로 이용한 시험 방식이 제안되었고, 그 효과가 검증되었다. 풀이된 예제 연구에 따르면, 학생들에게 문제에 대한 단계적인 해결책인 풀이된 예제를 문제 사이에 제시할 경우, 문제만 풀 때보다 효과적으로 학습한다. 그러나 풀이된 예제의 단순한 제시는 학습 효과가 제한적이라는 최근의 발견들이 있었다. 이에 따라 본 연구에서는 학습자가 풀이된 예제를 더 적극적으로 탐구하게 하는 방법으로 풀이과정을 선다형의 답지로 제시하였다. 이 시험 방식은 컴퓨터화 시험으로 구현되었으며, 학생들이 컴퓨터에서 단답형으로 문제를 풀고 나서 답지를 요청하면 선다형 답지가 제시되었다. 이 때 실험 집단은 답지가 풀이 과정으로, 비교 집단은 전통적 선다형과 같이 최종 정답으로 구성되었다. 초등학교 6학년 학생들을 대상으로 실험이 수행되었다. 사후 검사 결과 실험집단의 평균 점수가 비교집단의 평균 점수보다 높았다. 이 결과는 풀이 과정을 답지로 이용한 시험 방식이 교실현장에서 학습을 촉진하기 위한 도구로 활용될 수 있음을 시사한다. 끝으로 후속 연구의 방향성이 논의되었다. The present study proposes and examines a new type of multiple-choice math test. In this format, the options are the intermediate derivatives of the math problem solution process rather than the final answers. This idea originates from the studies on the effect of worked-out examples. In these studies, it has been shown that students learn better when they were presented with worked-out examples than when presented with final answers by themselves. In line with these findings, we introduced the intermediate derivatives of the solution process as the options of multiple-choice items so that the test-taker will have a chance to examine the solution process. The test was implemented as a computerized test in which students can solve problems in a short answer format, and then pick a multiple-choice option which appears when requested. The experimental group had multiple-choice options which were intermediate derivatives of the solution process, and the control group had the final answers as the options as in most multiple-choice tests. The participants were 6th graders in elementary school. The posttest results revealed that the average score of the experimental group was higher than that of the control group. The results suggest that tests that use intermediate derivatives of the problem solution process as options can be used as learning tools in the classrooms. Finally, directions for further studies were discussed.

공기 유압식 브레이크 라인 파손 사례 및 파손 분석 연구

박정만,박종진,Park, Jeongman,Park, Jongjin 한국자동차안전학회 2020 자동차안전학회지 Vol.12 No.2

In this case study, the brake line failure of air over hydraulic(AOH) brake system is described. AOH brake system is applied to commercial vehicles between 5 to 8 tons. It consists of a hydraulic system using compressed air and operates the air master to form hydraulic pressure to transfer braking power to the wheels. When the brake lines of the system applied to vehicles with high load capacity are damaged, the braking force of one shaft is lost, and the braking distance increases rapidly, leading to a big accident. Failure of the brake line occurs due to various causes such as road surface fragmentation, corrosion of the line, and aged deterioration of air brake hose. The braking force could be decreased even when a very small break in the form of a pin-hole occurs. However, it is difficult to find a part where the thickness of the line is thin due to stone pecking or corrosion generated in the pin-hole formed on the brake line located under the lower part of the vehicle by the sensory evaluation or the conventional braking force test. Accordingly, it is necessary to analyze the condition and cause of the failure of the brake line more precisely when the accident investigation of the heavy vehicles, and also to examine the necessity of the advanced test for the aged brake line.