PURPOSES : Speed management is essential for enhancing children’s safety in school zones. The objectives of this study are to analyze how digital-based school zone signs and newly proposed signage for increasing visibility influence speed reductions and how the new system facilitates drivers obeying the speed limits. METHODS : A before/after analysis technique with comparison groups (widely used to evaluate safety effects) was employed. To effectively capture the safety effects of the new system, two significant measures were selected as the measures of effectiveness: the rates of change in space mean speeds and speed limit compliance. RESULTS : With three target sites and three comparison sites, the mean space speeds after installing the new systems were found to be slightly reduced for all target sites (the reduction rates of the space mean speed were found to be 5% for site A, 1% for site B, and 6% for site C). The lack of a constant tendency in speed reduction effects at all sites might be owing to the fact that the speed data collection was conducted before the driver's system adaptation was sufficiently performed. Regarding the speed limit compliance rate, significant increases were observed at two sites (10% for site A and 51% for site C), but site B did not show an increasing effect. The reason for the absence of this effect is that the installation of crosswalks and speed bumps at the target site affected the driver's compliance with the speed limit. CONCLUSIONS : An insufficient amount of evaluation results was obtained for the new guidance system. However, the new guidance system method provides an alternative approach to improving children's safety, i.e., by inducing drivers to actively slow down in school zones.

PURPOSES : This study estimated an asphalt pavement internal behavior under uphill lanes considering reducing speed of heavy truck on uphill slope. METHODS : Truck performance curve which has been adapted to "Korea Highway Capacity Manual" was analyzed. And asphalt pavement internal behaviors were estimated with Multi-layered elastic analysis using KPRP(Korea Pavement Research Program) dynamic modulus prediction equations. RESULTS : As a result, it is shown that when the standard truck drives 2.0 km at a speed of 80 km/h in 8% climbing slope, it's speed reduced to 25.4 km/h, at same time frequency in asphalt layer decrease to 67.2% and it's dynamic modulus degrades to 30.9%. Based on these results, internal behavior as decreasing vehicle speed on uphill lanes were estimated. CONCLUSIONS : From the results of Multi-layered elastic analysis, internal behavior showed that when the standard truck drives 2.0 km at a speed of 80 km/h in 8% slope on uphill lanes, vertical strain was increased to 44.4% at the bottom of surface course, and lateral tensile strain was increased to 20.5% at the bottom of base course.

고속도로의 터널구간은 일반구간과는 다른 주행특성(속도, 교통량, 밀도 등)을 가지게 되고 이에 따라 고속도로 일반부에서 터널진입 전과 후에 운전자 행태가 변하는데, 가장 대표적인 예가 속도의 감소 현상이라 할 수 있다. 하지만, 이러한 다양한 요인들 중 현재까지 연구의 진행 추세는 도로의 용량, 속도감소 측면의 정량적인 부분에 초점을 맞춘 연구들 위주로 진행되고 있는 것이 현실이다. 따라서 본 연구에서는 터널의 다양한 여건을 고려할 수 있는 구간을 대상으로 설문조사와 설문결과 분석을 통해서 터널구간 속도감소에 영향을 미치는 정성적 요인들을 알아 보았다. 분석 결과 최근 증가 추세인 장대터널과 관련된 터널 자체의 형상(차로폭, 갓길폭, 터널길이)에 대한 요인이 터널 내부 속도감소에 영향을 미치는 것으로 나타났다. 또한 터널입구 보임여부와 같은 시각적 환경이 속도감소의 영향요인으로 나타났으며 터널 내부의 조명밝기에 따라 속도변화가 나타나는 것을 알 수 있었다. 본 연구결과를 활용하여 고속도로 터널부 설계관련 기술개발 및 서비스개선을 위해 지속적인 투자가 이루어질 것이라 판단된다.

Ship system can be divided into four sub-systems: hull, propeller, main engine and operation system which severely affect the characteristics of a ship. In determining ship speed in waves, two factors are considered the involuntary speed loss due to added resistance caused by wind and waves, and the voluntary speed loss by command of operation system to prevent severe ship motions. In this paper, the main function of four sub-system is analyzed for input/output relations and propulsive coefficient and a useful method to predict involuntary speed loss of a ship is presented. Two calculated examples for a high speed container ship and a passenger ship with single screw and diesel engine are given.