• Communications for Statistical Applications and Methods
• /
• v.21 no.5
• /
• pp.387-393
• /
• 2014

Recurrent gap times are analyzed with diverse methods under several assumptions such as a marginal model or a frailty model. Several resampling techniques have been recently suggested to estimate the covariate effect; however, these approaches can be applied with a time-fixed covariate. According to simulation results, these methods result in biased estimates for a time-varying covariate which is often observed in a longitudinal study. In this paper, we extend a resampling method by incorporating new weights and sampling scheme. Simulation studies are performed to compare the suggested method with previous resampling methods. The proposed method is applied to estimate the effect of an educational program on traffic conviction data where a program participation occurs in the middle of the study.

• Proceedings of the Korea Contents Association Conference
• /
• 2015.05a
• /
• pp.69-70
• /
• 2015

본 논문에서는 운행중인 차량이 수집한 위치별 교통 이벤트 (지체, 정체, 사고, 노면상태 등)를 다른 운행 차량과 실시간으로 공유하여 안전운행 서비스를 제공하기 위한 방법을 제안한다. 운행중인 차량은 차량내의 스마트 기기나 전용 기기를 이용해 수집한 교통이벤트를 실시간으로 서버로 전송하고 서버는 전송된 교통이벤트를 위치별, 시간별로 색인하고 중복된 교통이벤트를 분류하여 저장한다. 이런 모든 과정은 처리 속도 향상을 위해 Spark의 RDD를 이용해서 인-메모리에서 처리된다.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1650-1655
• /
• 2007

A lights-out detector, which helps the person in charge of maintenance make a quick judgment in the event of a failure of LED-type traffic lights, was explored/developed and installed/ tested, at Seoul Metro, after they developed a patented pilot product in 2005; and, a product improvement test was conducted to ensure reasonable maintenance of signaling facilities. Having better compatibility with existing circuit in use and displaying stable load current, the device makes the maintenance of lights-out detection and alert easier.

• Wind and Structures
• /
• v.16 no.4
• /
• pp.393-409
• /
• 2013

This paper uses ten years of on-site monitoring data for the Confederation Bridge to derive wind loads and investigate whether the bridge has experienced its design wind force effects since its completion in 1997. The load effects derived using loads from the on-site monitoring data are compared to the load effects derived using loads from the 1994 and 2009 wind tunnel aerodynamic model tests. The research shows, for the first time, that the aerodynamic model-based methodology originally developed in 1994 is a very accurate method for deriving wind loads for structural design. The research also confirms that the bridge has not experienced its specified (i.e., unfactored) wind force effects since it was opened to traffic in 1997, even during the most severe event that has occurred during this period.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2014.11a
• /
• pp.80-83
• /
• 2014

매장은 특정 구역들로 분할되어 있고, 각 구역들은 고유의 비콘을 가지고 있다. 현재 소비자가 있는 구역의 비콘이 자신의 고유 ID 를 소비자의 단말기(스마트폰)에 전송하면, 단말기는 임의의 번호를 자신의 고유 ID 로서 생성하여 [Beacon ID, 단말기 고유 ID, 현재 시간]을 서버로 보낸다. 그러면 서버쪽에선 사용자의 현재 위치를 파악하는 동시에 사용자가 그 자리에 얼마나 오래 있었는지를 계산해 저장한다. 이러한 과정의 결과로 만들어진 하나의 SEQ 가 매장 주인이 생각했던 SEQ와 얼마나 유사한지를 비교하여 그 결과를 보여준다.

• Journal of Auto-vehicle Safety Association
• /
• v.11 no.3
• /
• pp.7-12
• /
• 2019

AEB (Autonomous Emergency Braking system), a system in which vehicles automatically recognize forward objects or pedestrians and actively brake when forward collisions are expected, has been mandated by NHTSA (National Highway Traffic Safety Administration) and IIHS (Insurance Institute for Highway Safety) for all vehicles sell in the United States since 2022, and AEB research is also actively underway in korea. In this study, it can be confirmed that the passenger injury is reduced according to the AEB detection distance when it is assumed that the AEB is mounted in the actual event generated from KIDAS (Korea New Car Assessment Program) data through various analysis programs.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.06a
• /
• pp.119-120
• /
• 2020

Recently, a building fire has occurred due to various influences. Accordingly, we are developing an public safety & security unmanned aerial vehicle for fire prevention and initial response to fire. The public safety & security unmanned aerial vehicle is used to grasp the traffic route to enter the fire engine in the event of a fire in a dense structure and to determine the scale of the fire and the area of danger of collapse around the fire site. In this study, an environmental test of the public safety & security unmanned aerial vehicle's heat resistance was performed in an environment simulating a fire scene.

• Journal of the Korean Society of School Health
• /
• v.16 no.2
• /
• pp.25-34
• /
• 2003

Instroduction: The purpose of this study was to investigate safety education-related backgrounds and safety behaviors of elementary school children at a local area in Jeonbuk province. Methods: Study subjects were 308 5th and 6th graders from 6 schools located in J City and the data were collected from June 16-27, 2003. Research instrument to test safety behaviors was 4-points summated scale (Cronbach${\alpha}$= .94) composed of 54-items with three sub-categories school life safety (${\alpha}$= .88), traffic safety (${\alpha}$= .86), and daily life safety (${\alpha}$= .84), The data was analyzed by percentage, x2-test, t-test, ANOVA and Duncan test using SPSS/PC 10.0. Results: 1. Safety Education-related Characteristics: Safety education was mostly conducted during extracurricular hour as picnic (37%) and regular class (37.2%); and the instructors of safety education were school nurse (33.2%), classroom teacher (30.9%), and parents (23.4%) in order. About two third (71.0%) of the subjects have had many kinds of school event program such as essay writing, poster drawing, oratorical contest in the course of safety education According to gender, girl students was more favorable about school events as a effective safety education measure (x2=9.188, p= .010); and according to school location, nural school taught more at moming & closing session (x2=7.383, p= .025), by school nurse or classroom teacher (x2=36.574, p= .001), and had more frequent (x2=63.337, p= .001) safety education class. 2. Practice of safety behaviors: Mean scores of safety behaviors was $106.9{\pm}24.92$ out of 162 points. According gender, the scores of girl students (t=-3.296, p= .001) were significant higher than boy students. But there was not any significant difference according to school area According to safety education-related characteristics, the scores of safety behaviors was significantly higher in the group who thought that school event program was more effective on safety education (F=4.024, p= .019), and who were more interested in current safety education class (F= 10.203, p= .001) Conclusions: From the above findings, the authors concluded that school-based safety education was mainly conducted at extra-curricular and regular class, and by school nurse or classroom teacher in elementary school. Even though the mean scores of safety behaviors of elementary school children was in medium level, those. were significant higher in girl students and in rural school children. And extra-curricular activities and school event programs were suggested as more effective strategies for school-based safety education Based on the above findings, safety education class can be recommended in regular curricular basis; and various extracurricular activities and school event programs need to be developed for more effective school-based safety education. In addition, further study on gender-specific factors on safety behaviors and nationwide survey on school-based safety education should be needed.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.1
• /
• pp.35-40
• /
• 2011

In this paper, we compare and analyze data aggregation methods based on event area in wireless sensor networks. Data aggregation methods consist of two methods: the direct transmission method and the aggregation node method. The direct aggregation method has some problems that are data redundancy and increasing network traffic as all nodes transmit own data to neighbor nodes regardless of same data. On the other hand the aggregation node method which aggregate neighbor's data can prevent the data redundancy and reduce the data. This method is based on location of nodes. This means that the aggregation node can be selected the nearest node from a sink or the centered node of event area. So, we describe the benefits of data aggregation methods that make up for the weak points of direct data dissemination of sensor nodes. We measure energy consumption of the existing ways on data aggregation selection by increasing event area. To achieve this, we calculated the distance between an event node and the aggregation node and the distance between the aggregation node and a sink node. And we defined the equations for distance. Using these equations with energy model for sensor networks, we could find the energy consumption of each method.

• KIPS Transactions on Computer and Communication Systems
• /
• v.3 no.8
• /
• pp.261-270
• /
• 2014

As Internet traffic increases recently, much effort has been put on improving the performance of a web server. In addition to hardware side solutions such as replacement by high-end hardware or expansion of the number of servers, there are software side solutions to improve performance. Recent studies on these software side solutions have been actively performed. In this paper, we identify performance degradation problems occurring in a conventional TCP networking reception process and propose a way to solve them. We improve performance by combining three kinds of existing methods for Linux Networking Performance Improvement and two kinds of newly proposed methods in this paper. The three existing methods include 1) an allocation method of a packet flow to a core in a multi-core environment, 2) ITR(Interrupt Throttle Rate) method to control excessive interrupt requests, and 3) sk_buff data structure recycling. The two newly proposed methods are fd data structure recycling and epoll_event data structure recycling. Through experiments in a web server environment, we verify the effect of our two proposed methods and its combination with the three existing methods for performance improvement, respectively. We use three kinds of web servers: a simple web server, Lighttpd generally used in Linux, and Apache. In a simple web server environment, fd data structure recycling and epoll_event data structure recycling bring out performance improvement by about 7 % and 6%, respectively. If they are combined with the three existing methods, performance is improved by up to 40% in total. In a Lighttpd and an Apache web server environment, the combination of five methods brings out performance improvement by up to 36% and 20% in total, respectively.