• 한국자동차공학회논문집
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• 제12권1호
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• pp.91-98
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• 2004

This paper is concerned with crash analysis for an auto-body member with the forming effect. Auto-body members such as a front frame assembly are fabricated with sheet metal forming processes that induce forming histories such as the plastic work hardening and non-uniform thickness distribution. Numerical simulation is carried out with LS-DYNA3D in order to identify the forming effect on the crashworthiness. The crash analysis of the front frame assembly with the forming effect leads to a different result from that without the forming effect. Crashworthiness such as the load-carrying capacity, the crash mode and the energy absorption are calculated to investigate and identify the forming effect. It is fully demonstrated that the design of auto-body members needs to consider the forming effect for accurate assessment of the load-carrying capacity and the deformation mechanism of the formed members.

• 한국ITS학회 논문지
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• 제23권1호
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• pp.134-145
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• 2024

본 연구의 목적은 조건부 운전면허 발급에 필요한 평가 시나리오 개발 프레임워크를 제안하는 것이다. 이를 위해 프레임워크는 5단계로 구성하였다. 1단계에서는 고령 운전자에 의한 충돌사고의 주요 요인을 사고빈도와 심각도 측면에서 교통사고 특성에 대한 문헌을 검토하였다. 2단계는 도로교통공단 교통사고분석시스템 사고 자료를 활용하여 비고령, 초기 고령, 후기 고령 집단별 교통사고 특성에 대한 분석을 수행하였다. 이를 통해 고령 운전자 등 고위험군 교통사고 유형을 도출하였다. 3단계는 고위험군 교통사고 유형에 해당하는 블랙박스 영상을 분석하여 사고가 발생한 상황에 대해 기술한 교통사고 스토리를 도출하였다. 4단계는 다양한 시나리오 개발을 위해 도출된 사고 스토리의 유형을 분류하여 여러 가지 사고 상황을 구분하였다. 5단계는 최근 다양한 자율주행차량 평가 시나리오 개발에 활용되고 있는 PEGASUS 5-Layer 형식을 적용하여 시나리오를 제시하였다. 본 연구의 결과는 향후 조건부 운전면허 발급을 위한 운전능력 평가시나리오 개발의 기반으로 활용될 것으로 기대된다.

• 대한교통학회지
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• 제32권3호
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• pp.198-206
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• 2014

경찰청 통계에 따르면, 우리나라에서 신호위반사고는 심각한 안전문제로 대두되고 있다. 본 연구에서는 청주시 신호교차로에서의 신호위반사고를 다루고 있으며, 연구 목적은 신호위반사고와 비신호위반사고의 특성을 비교분석하고 이항 로지스틱 모형을 이용하여 영향요인을 파악하기 위함이다. 이를 위해 본 연구에서는 2007-2011년간 청주에서 발생한 2천246건의 신호위반사고와 3천884건의 비신호위반사고 자료를 이용하여 두 집단 간의 차이를 검증하고자 한다. 주요 연구결과는 다음과 같다. 첫째, 신호위반사고는 야간시간대 및 직진상태에서 많이 발생하였다. 둘째, 신호위반사고와 비신호위반사고에 영향을 주는 변수로는 충돌형태, 충돌전 진행방향, 운전자 연령대(30대, 50대), 음주운전 및 사고유형 등으로 나타났다. 마지막으로, 이항 로지스틱 회귀분석에 의해 통계적으로 유의한 모형식이 개발되었다(Hosmer and Lemeshow test: 7.052, p-value:0.531).

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.401-407
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• 1998

Recently, as the railway vehicles become speedy and massive, the collision is being regarded as an important factor for the assessment of safety for passenger. And the study of collision is being in progress more actively in advanced nations. In this study, the collision analysis is performed by using non-linear dynamic finite element program PAM-CRASH. The carbody used in analysis is made of Aluminum AL6005A to realize lightweight, and designed and manufactured by DHI (Daewoo Heavy Industry) lately. For the accuracy of the result in the practical collision, the experiment of material properties has been performed. The result of the analysis shows the underframe of rolling stock is the most important part as a collision energy absorbing structure. Further study is needed for optimal design which enables the carbody shell structure to disperse absorbing energy adequately.

• 한국항공운항학회지
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• 제18권1호
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• pp.58-63
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• 2010

Introduction : Head trauma is the main cause of death in aircraft crash. In a Michigan study of structurally survivable, fatal accidents, 80% of the fatally injured had received head trauma. We tried to develop a new helmet for passengers, and perform its efficiency test. Methods : An aircraft helmet requires an excellent protection against head trauma, lightness, and small volumes. In addition, it must be wearable, fire resistant, and non toxic when it is burning. We developed two new helmets made from silicone foam which met all theses requirements. One was thin (2.5cm), and the other was thick (6.3cm). These looked like a motorcycle helmet and had only a soft silicone as liner material without an outer hard shell. Therefore we can carry them easily inside aircrafts. The standard test for helmet is Snell's drop test. It measures the impact acceleration of head shaped metal wearing helmet during we drop it at certain heights. Impact sites were total 5 sites (front, back, right, left and top) for each helmet. All these sites were impacted twice. Results : The thickness of impact sites varied from 2.5cm to 6.3cm. The impact acceleration of 2.5cm thickness site when it was dropped from 1.0 meter was 379g. But, that of 6.3cm thickness site when it was dropped from 1.5 meter was only 163g. Unfortunately, both helmets didn't meet the Snell Standard for motorcycle helmets. Discussion : If we add suitable outer hard shell, and change its thickness and design, the efficiency will be increased. A study indicated that helmet could reduce the risk of head trauma up to 85%. We made helmet for passengers in aircraft crash for the first time. If we improve its weak points, it will decrease the frequency of head trauma in aircraft craft.

• 한국도로학회논문집
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• 제15권5호
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• pp.203-215
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• 2013

PURPOSES : This study deals with first traffic violations occurred by novice drivers, which may be associated with traffic accidents. The objective of this study is to identify what kinds of drivers' characteristics influence on duration till the first traffic violation. METHODS : For the study, Survival Analysis and Cox proportional hazard model, that are usually used in the medical field, were employed. Survival Analysis was conducted to investigate whether there exist differences in survival duration by each covariate, whereas Cox proportional hazard model was used to identify significant factors that affect survival duration till novice drivers violate traffic regulations for the first time after getting a driver license. RESULTS : The results of Survival Analysis indicate that female, age (less than 21), low-frequency examinee of written exam, and non-crash involved drivers have longer duration till the first violation compared to male, greater than 21 years old, high-frequency examinee of written exam, and crash involved drivers, respectively. For the Cox proportional hazard model, license class 1 acquisitor was found to increase the survival duration till the first traffic violation was made, while male, age of 21-24, age of 25-34, age of 45-54, and crash involved drivers were more likely to reduce the survival duration. CONCLUSIONS : Absolutely, traffic violation is closely related to traffic accidents and all of the drivers should keep the traffic regulations to enhance highway safety. The results of this study might provide some insights to construct safe road environments by controlling the factors that reduce the traffic violation duration of novice drivers.

• 한국도로학회논문집
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• 제19권6호
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• pp.201-212
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• 2017

PURPOSES : The objective of this study is to identify the characteristics affecting traffic accidents that have occurred in 564 industrial complexes nationwide from 2011 to 2015. METHODS : The traffic accidents were specified using various factors such as industrial complex type (national VS. general), industrial complex degradation (old VS. non-old), location of complex (capital VS. non-capital), and traffic law violation (speeding, signal violation, and median invasion). The average number of crashes and accident ratio (fatal, severe, and both) in terms of characteristics of industrial complexes were calculated. With a sample of crashes of the industrial complexes for 5 years, statistical significances were tested to analyze and compare the differences based on industrial complex and traffic law characteristics using parametric and non-parametric methods. RESULTS : From statistical results, it is observed that the crash frequency occurring in old industrial complexes is three times higher than that in non-old industrial complexes. Old industrial complexes located in a capital area, old national industrial complexes, and old general industrial complexes are considerably related to higher crash frequency, but the fatal accident ratio appeared to have no statistical difference across industrial complex characteristics. Severe crashes are more likely to occur in non-old industrial complexes on an average. CONCLUSIONS : It is necessary to eliminate potential threats to roads and traffic in the same manner as illegal parking in industrial complexes through the restoration of old industrial complexes. To improve the efficiency of road infrastructure, efforts should be made to improve traffic safety in accordance with industrial characteristics such as planning and operation of relevant local government programs.

• 한국콘텐츠학회논문지
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• 제21권7호
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• pp.157-163
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• 2021

파일 시스템에서 하나의 쓰기 연산은 여러 데이터를 수정할 수 있지만, 이러한 파일 시스템의 변경들은 원자적으로 디스크에 써지지 않는다. 따라서 파일 시스템의 일관성을 위해 기존의 저널링 기법은 시스템 성능을 저하시키는 대신 충돌 일관성을 보장한다. 비휘발성 메모리를 저널 공간으로 사용하면 비휘발성 메모리의 낮은 지연 시간과 바이트 수준 접근성으로 성능 저하를 완화시킬 수 있다고 알려졌다. 그러나 비휘발성 메모리를 고려한 저널링 기법 중에서 확장성을 제공하는 것은 없다. 본 논문에서는 확장적 저널링을 위해 비휘발성 메모리상의 저널 공간을 여러 영역으로 분할하여 한 영역에 집중된 연산을 분산시킨다. 또한, 저널 영역별로 입출력 쓰레드를 두어 저장 장치에 데이터 쓰기 연산을 가속화한다. 제안된 기법을 JFS에 적용하여 고성능 저장장치를 탑재한 멀티코어 서버에서 이를 평가한다. 평가 결과는 제안된 기법이 기존의 NVM 기반 저널링 파일 시스템의 기법보다 성능이 우수함을 보여준다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.326-330
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• 2005

Crahworthy design of trains is now indispensable procedure in modern railway vehicle design for ensuring the safety of passengers and crew. It is now widely recognized that a more strategic approach is needed in order to absorb higher level energy in a controlled manner and minimize passenger injuries effectively. The first design step in this strategic approach is the design of the front end structure(so called HE extremities) to absorb a large part of total impact energy and then the structure of passengers non-accommodation zones(so called HE extremities) is designed to absorb the rest of impact energy. In this paper, the passengers entrance door area is selected as the LE(low energy) extremities and the design of the LEE was carried out. The main part of LEE design procedures is the design of energy absorbing tubes. For this purpose, the several tube candidates are introduced and compared to each others with numerical crash simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.40-44
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• 1998

In this study, the subframe of passenger car is developed by typical analysis and carsh simulations. According this results, energy absorption and barrier froce is very important to control passenger safety and deformation shape. For that purpose, it is most effective to absorb energy more tailor welded blanks(TWB) subframe than non-TWB. The subframe with TWB is simulated, in which reduced stamping parts, weight reduction and cost down.