• Journal of Korean Society of Transportation
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• v.18 no.6
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• pp.19-32
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• 2000

우리나라 비신호 교차로의 운영방법은 미국과는 다르게 대부분 완전 비제어식 운영(Totally Uncontrol)방법으로 되어있다. 본 연구에서는 우리나라 비신호 교차로들 중 미국 HCM의 TWSC 교차로에 관한 분석방법이 적용 가능하다고 판단되는 비신호 교차로들을 대상으로 임계간격과 추종시간의 기준을 분석하였다. 본 연구에서는 수도권을 중심으로 총 11개의 4-지 비신호 교차로들을 대상으로 이동류별, 차량의 종류별에 따른 차량들의 임계간격과 추종시간을 조사 및 분석하였다. 그 결과 임계간격은 3.8초 - 5.4 초로 나타났으며, 추종시간은 2.4초- 2.7초 범위를 나타내었다. 또한, 임계간격의 경우 차량의 종류별에 따른 차이는 나타나지 않았으나, 이동류별로는 차이를 나타내었다. 이에 반하여, 추종시간은 이동류별에 따른 차이가 없으며, 차량의 종류별에 따라 차이가 존재하는 것으로 분석되었다. 본 연구의 분석 결과인 임계간격과 추종시간의 기준치를 국외 나라들의 연구결과와 비교 분석한 결과는 국외보다 낮게 분석되었으며, 이는 우리나라와 국외의 운전자 운전특성과 비신호 교차로의 운영방식의 차이에서 나타난 결과로 판단된다. 본 연구에서 제안한 임계간격과 추종시간의 기준은 수도권 지역의 4-지 비신호 교차로들 중 주도로와 부도로의 교통량과 속도 등의 현저한 차이가 있는 교차로 분석시 이 기준으로 적용할 수 있고, 우리 나라의 TWSC 방법을 갖는 비신호 교차로에 관한 용량과 지체시간의 이론적 모형 개발과 용량 및 지체시간의 분석을 위한 기초 자료로 활용할 수 있을 것으로 판단된다.

• Journal of Korean Society of Transportation
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• v.30 no.2
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• pp.93-100
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• 2012

This study dealt with the critical gap of roundabouts in Korea. The objective was to develop a model to derive critical gaps by analyzing gap acceptance patterns. In this context, the present study had a particular emphasis on collecting the data for accepted or rejected gaps. The main contributions of the study were as follows. First, accepted or rejected gaps were counted and measured through video frame analysis on the traffic patterns of 20 roundabouts in Korea. Based on the data, a gap acceptance model, guaranteeing the statistical significant in their parameters, was developed in the framework of the Logit model. Second, the critical gap calculated from the developed model was evaluated to be 2.584 seconds as a whole. Also, the critical gap in urban areas was estimated to be 2.744 seconds, whilst the critical gap in rural areas was estimated to be 2.416 seconds. Finally, critical gaps of roundabout in Korea were found to be smaller than those in foreign countries by about 1.5~2.5 seconds.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.33-40
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• 2009

The critical lag of crosswalk pedestrians is an important parameter in analyzing traffic operation at unsignalized crosswalks, however there is few research in this field in Korea. The purpose of this study is to develop a model to estimate the critical lag. Among the elements which influence the critical lag, the age of pedestrians and the length of crosswalks, which have fuzzy characteristics, and the each lag which is rejected or accepted are collected on crosswalks of which lengths range from 3.5 m to 10.5 m. The values of the critical lag range from 2.56 sec. to 5.56 sec. The age and the length are divided to the 3 fuzzy variables each, and the critical lag of each case is estimated according to Raff's technique, so a total of 9 fuzzy rules are established. Based on the rules, an ANFIS (Adaptive Neuro-Fuzzy Inference System) model to estimate the critical lag is built. The predictability of the model is evaluated comparing the observed with the estimated critical lags by the model. Statistics of $R^2$, MAE, MSE are 0.96, 0.097, 0.015 respectively. Therefore, the model is evaluated to explain the result well. During this study, it is found that the critical lag increases rapidly over the pedestrian's age of 40 years.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.400-409
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• 2013

In this paper, considering the characteristics of the driver at roundabouts by investigating the critical gap acceptance on various traffic conditions, multi-legged roundabouts were evaluated. The gap acceptance and rejection of 4-legged, 5-legged, 6-legged, and 7-legged roundabout were surveyed on real fields, and the critical gap acceptance was estimated using Raff's methods. Derived the critical gap acceptance was processed calibration and validation for micro-simulation, and then multi-legged roundabouts under variable conditions such as variations of traffic volume, turning ratio, and size of inscribed circle diameter were evaluated to verify operating conditions of roundabouts. As the results, according to the operating traffic volume and turning ratio, the inscribed circle diameters were proposed at each level of service. These inscribed circle diameters were able to reflect the guideline of geometric design for multi-legged roundabouts.

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.195-205
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• 2001

The objective of the paper is to analyze the traffic characteristics for freeway merging area. Freeway merging area is different from basic section due to ramp vehicles. Therefore, to understand the traffic characteristics of (leeway merging area, this study focused on two factors including critical time headway required in merging maneuver and maximum possible merging volume. In this paper, new model that adopts critical time headway instead of critical time gap in calculating the maximum possible merging volume based on probability function was developed In previous studies, for calculating the maximum possible merging volume, it was considered that merging vehicles could merge freely if a given time gap was greater than the critical time gap. Also, the critical time gap was used as the same value in all traffic flow conditions. But, a time gap required in merging maneuver could be changed, even to the same driver, because difference of relative speed varies in different traffic flow conditions. So, in some cases, the critical time gap could be insufficient value in merging maneuver. Therefore, in this study. a calculating procedure for critical time headway in all traffic flow conditions was presented. Also, the maximum possible merging volume and capacity for freeway merging area were calculated by using the previously found critical time headway.

• Journal of the Korean Geographical Society
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• v.33 no.2
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• pp.325-338
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• 1998

본 연구에서는 시.공 복합적인 선형 점 자료를 대상으로 시간과 공간을 함께 고려했을 때 자료 내에 군집(cluster)-시.공 복합 군집(space-time cluster)-이 존재하는 가를 검증하는 방법에 대해 논의하고, 실제 교통사고지점의 분포자료를 분석하여 군집의 유무를 통계적으로 검증하였다. 통계 분석의 결과 다음과 같은 사실이 확인되었다. 첫째, Knox의 분할표 방법과 Mantel의 역수 변환을 이용한 일반화된 회귀분석방법 모두 임계 거리 및 임계 시간 간격의 선택이 분석결과에 영향을 미친다. 둘째, 이러한 임의성을 극복하기 위해 다양한 임계 거리 및 임계 시간 간격(혹은 부가 상수)에 대해 반복 실험한 결과, 일부 임계값의 조합에서 시간과 공간이 서로 독립적이라는 귀무가설을 기각할 수 있는 증거가 발견되었다. 셋째, 시.공 복합 군집의 파악에 가장 적합한 임계 거리와 임계 시간 간격은 공간적으로는 7000m, 시간적으로는 14일 혹은 21일이다. 마지막으로, 통계 분석과정에서 자료에 존재하는 중복 기록 사고들의 존재가 밝혀짐으로써 시.공 복합군집 검증이 탐험적 자료 분석(exploratory data analysis)의 도구로서 가지는 가치를 확인할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.302-309
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• 2017

The influence of the pile diameter, center to center pile spacing, internal friction angle of embankment soil, and height of embankment on the arching efficacy of the embankment pile was investigated. The arching efficacy, which was derived by the arch model developed in the embankment soil was calculated using two methods, one that considers crown failure of the arch and the other that considers load on the pile cap and critical relative spacing ratio for which the arching efficacy calculated by the two methods are the same. According to the computed results in this study, the arching efficacy calculated from a consideration of the load on pile cap governs when the relative spacing ratio becomes smaller and that calculated from the theory of crown failure governs when the relative spacing ratio becomes larger. The critical relative spacing ratio below which the arching efficacy calculated from a consideration of the load on pile cap governs the design decreases with increasing value, which is defined by the ratio of the pile diameter to the pile center to center spacing. Critical relative spacing ratios, which correspond to the values of 0.5 and 0.2 were 0.35 and 0.85, respectively. Considering the computed results, the critical relative spacing ratio decreases with increasing Rankine passive earth pressure coefficient and critical relative spacing ratios, which correspond to values of 5 and 2, were 0.23 and 0.85, respectively. The arching efficacy, which corresponds to the area ratio of 9%, was 54% and the one that corresponds to the value of 3 was 61%; the critical relative spacing ratios, which correspond to those arching efficacies, were greater than 0.5.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2828-2835
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• 1996

In this paper we propose a new shaping algorithm which can control the shaping delay and the output buffer size based on the leaky bucket counter with a threshold value. This paper assumes that input traffic of the proposed shaping algorithm is the worst case traffic tolerated by the continuous leaky bucket algorithm and claracterizes traffic patterns that can depart from our shaping algorithm. We also compare shaping delay and output buffer size of the proposed algorithm with the existing shaping algorithm without a threshold value. Our results show that the proposed shaping algorithm can easily manage the shaping delay and output buffer size than any other mechanism.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.10a
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• pp.134-135
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• 2009

선박에서 주로 채택되는 열교환기는 쉘튜브형과 판형열교환기로 분류된다. 이 연구에서는 소형쉘튜브형 열교환기의 설계에서 중요한 요소인 냉각튜브와 벽면과의 간격에 따른 유동특성을 입자영상유속계를 이용하여 계측하였다. 연구 결과 벽면과의 거리변화에 따른 임계간격비는 0.25전후로 추정되었으며 벽면효과에 따른 정량적 데이터를 확보하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.262-267
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• 1997

금속형 사용후핵연료 관리모형으로 직경 3 cm, 길이 248.5cm인 금속봉을 19개 장전한 캐니스터가 x-y 방향으로 무한 격자배열된 경우에 대해 캐니스터의 두께, 간격 및 외부의 공기중 수분농도의 변화에 따른 핵임계도 분석을 수행하였다. 미임계한계치(k$_{eff}$=0.95) 근방에서 최대 핵임계도를 나타내는 각 인자값을 구하고, 미임계 상태를 유지하는 조건을 제시했다. 그 결과, 캐니스터의 두께가 7mm인 경우의 최대 핵임계도 값은 0.94401 $\pm$ 0.00050으로서, 공기중 수분농도가 0.34 g/㎤이고 간격이 4.8 cm인 경우에 나타났다. 8 mm인 경우의 최대 핵임계도 값은 0.91182 $\pm$0.00050이며, 캐니스터간의 간격이 4.4cm이고 공기중 수분농도가 0.35 g/㎤일 때 나타났다. 8 mm 캐니스터의 금속저장체 저장은 미임계 상태를 유지할 것으로 추정되었다.