• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.163.1-163.1
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• 2013

플라즈마 시뮬레이션을 수행하기 전에 현 컴퓨터의 계산 능력범위 내에서 물리적으로 타당하게 설명할 수 있는 수치 해석 방법을 먼저 정한다. 예를 들면, 가스 반응이 많고 각 가스 반응 중에 중요가스 반응을 빠르고 선택적으로 선별하고자 할 때, 혹은 외부 입력 변화에 따른 플라즈마 종의 온도 또는 밀도를 대략적으로 파악하고자 할 때는 공간적인 분포를 고려하지 않는 0차원 global 모델링을 이용한다. 압력이 높고 충돌이 빈번한 경우에는 플라즈마를 유체적인 관점에서 기술이 가능하므로, 볼츠만 방정식에서 속도에 관한 0차, 1차, 2차 모멘텀을 이용하여 유도된 유체 방정식을 이용한다. 반대로 압력이 낮고 충돌이 거의 없는 경우에는 플라즈마 입자를 개별적으로 추적하는 입자 전산 모사 방법을 이용한다. 지금까지는 앞에서 언급한 예와 같이, 개별 플라즈마 상태에 맞는 시뮬레이션 코드를 각각 만들어야 했고, 각 코드를 개별적으로 유지 보수해야 했다. 하지만, 개별적으로 코드를 유지 보수를 해야 할 경우에는, 동일한 기능을 하는 함수를 반복적으로 각 코드에 입력해야 하는 불편함이 따르고, 각 수치해석 방법의 장점을 모은 하이브리드 방법과 같은 전사모사를 개발할 때 각 기능을 통합해야 하는 어려움이 따른다. 또한 지금까지 개발된 대부분의 플라즈마 코드는 외부 입력에 대해 유연하지 못한 대처로 새로운 가스 반응을 추가하거나 새로운 수치해석 방법을 추가할 경우에는 코드를 전체적으로 수정해야 하는 어려움이 있었다. 따라서 코드를 통합적으로 관리할 수 있고, 외부 입력에 대해 유연하게 대처할 수 있는 시뮬레이터가 필요했다. 여기에서는 객체 지향 언어인 C++ 언어를 이용하여, 사용자 입력에 대해 유연하게 대처할 수 있고, 복잡한 화학 반응을 특정 수치 해석 방법에 상관없이 통합적으로 관리할 수 있는 코드를 개발하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.176-190
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• 2019

The prevention of pedestrian accidents in crosswalks and intersections is very important. The C-ITS services provide a warning service for preventing accidents between cars and pedestrians. In the current pedestrian collision prevention warning service according to the C-ITS standard, however, it is difficult to provide real-time service because it detects pedestrians from a video-analysis server in the control center and sends service messages through the ITS system. This paper proposes a pedestrian collision-prevention warning system that detects pedestrians in the local field using an edge camera and sends a warning message directly to the driver through a roadside unit. An evaluation showed that the proposed system could deliver the pedestrian collision prevention-warning message to the driver satisfying the delay time within the 300 ms required by the C-ITS standard, even in the worst case.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.469-472
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• 2006

BI 및 ETABr의 농도변화에 따른 속도상수의 변화는 이 반응이 단순한 1차 및 2차 반응 속도식에 맞지 않는다. 이와 같은 현상은 용액 속에서 두 반응 시약인 p-NPDPIN 및 BI와 상전이촉매인 ETABr 사이에 많은 수의 작은 응집된 입자(aggregates)을 형성함을 의미한다. 수용액 속에서는 불용성인 p-NPDPIN과 수용성인 BI가 충돌하여 반응할 기회가 적은데 반하여 ETABr은 이 두 시약을 함께 수용하여 세 분자 사이에 응집현상이 일어남으로 p-NPDPIN과 BI가 반응하기에 충분한 거리 내에 있게 된다. 바꾸어 말하면, 이 두 반응물질이 1:1 adducts로 반응하기보다는 여러 ETABr과 함께 많은 수의 반응분자들이 회합(응집) 되어 있음을 뜻한다.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.325-330
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• 1993

실리콘 gate의 MOS 전자 턴넬링 전극을 구성하여 그 특성을 조사하였다. 전자 방출은 전 gate 영역에서 MOS diode의 전위차를 지나는 턴넬링에 의하여 일어나고 안정하였다. 측정된 전류에서 산화막과 gate에서의 열전자의 충돌을 연구하였다. 방출된 전류는 압력에 관계없이 일정하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.495-496
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• 2006

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.3
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• pp.68-83
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• 2019

The number of pedestrian traffic accident fatalities is three times the number of car accidents in South Korea. Serious accidents are caused especially at intersections when the vehicle turns to their right. Various pedestrian collision warning services have been developed, but they are insufficient to prevent dangerous pedestrians. In this study, P2CWS is developed to warn approaching vehicles based on the pedestrians' characteristics. In order to evaluate the performance of the service, actual pedestrian data were collected at the intersection of Daejeon, and comparative analysis was carried out according to pedestrian characteristics. As a result, the performance analysis showed a higher accordance when the characteristics of the pedestrian is considered. Accordingly, we can conclude that identifying pedestrian characteristics in predicting the pedestrian crossing is important.

• Journal of Korean Society of Transportation
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• v.21 no.2
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• pp.7-16
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• 2003

To minimize the death and injury by a collision, the installation of an air bag is recommended as a mandatory practice together with the wearing of the seat belt. By using simulated collision experiments, this research focused on the effect of an air bag and seat belt on the driver safety. The vehicle deceleration characteristics were obtained from impact experiment. LSDYNA, a software program for vehicle collision analysis, and MADYMO. a software program for driver motion after collision, were used for simulated experiment. Four cases such as air bag installed and seat belt wearing (case A), air bag installed but seat belt not wearing (case B), air bag not installed but seat belt wearing (case C), air bag not installed and seat belt not wearing (case D) were analyzed. The impact of acceleration on the injury of driver's head was analyzed by Head Injury Criterion (HIC) as well. It was found that having air bag and wearing seat belt effectively reduced driver's head injury about 52.9% to 70.5% compared with the case of having neither air bag nor wearing seat belt.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.9-15
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• 1999

The Analysis of spray characteristics for combined spray group are necessary to develop large rocket engine. In this study, basic effects of interaction from spray fan formed by impinging jets were investigated with respect to mass distribution, droplet velocities and diameter. Patternater and PDPA are used for experimental apparatus. Water was used as a test fluid When momentum ratio is 1, effect of interaction from collision of spray fan on mass distribution are small. Also, effect of interaction from collision of spray fan on droplet velocities and diameter are small. But, droplet diameter is smaller near collision point due to second collision. Therefor, for the same momentum ratio from spray fan formed by impinging jets, we may neglect effect of interaction on mass distribution, droplet velocities and diameter.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.199-211
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• 2008

This study deals with the side right-angle collisions of 4-legged signalized intersections in Cheongju. The goals are to analyze the characteristics of accidents and to find out the accident factors that affect severity using ordered probit model. In pursuing the above, the study uses the data of 580 side right-angle collisions occurred at the 181 intersections(2004-2005). The analyses show that more accidents were occurred in the nighttime and in going straight. The main cause was analyzed to be the red-light violation. Also, the main results of modeling are the following, First, the likelihood ratio index is 0.094 and t-ratio values that explain goodness of fit are significant. Second, minor road traffic volumes, minor road lanes, major road left-turn lanes, major road left-turn signal, major road yellow signal time, cross angle, major and minor road speed limits are significant factors affecting crash severities at signalized intersections.

• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.400-407
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• 2002

Two dimensional solitary waves are stably propagated in a saturable medium which has a saturable nonlinear index as input intensity. However, in the case of low intensity. a negative fifth-order nonlinear medium has properties of a saturable medium. So a Gaussian beam travels stably. The propagation process into the fifth order nonlinear medium of the Gaussian beam with a weak intensity is investigated by using the computer simulation of the two-dimensional nonlinear Schrodinger equation. As a result, it is confirmed that the two-dimensional spatial solitary waves are stably propagated in this medium when the incident powers are self-trapping powers. In the condition of the phase difference and collisional angle between two input beams of 180 degree and 0.05 degree, respectively, we can confirm that all optical switching is as simple as controlling the incident power of one input beam.