• Journal of Mechanical Science and Technology
• /
• 제15권4호
• /
• pp.492-499
• /
• 2001

The characteristics of Prand시-Meyer expansion of supersonic flow with condensation along a wavy wall in a channel are investigated by means of experiments and numerical analyses. Experiments are carried out for the case of moist air flow in an intermittent indraft supersonic wind tunnel. The flow fields are visualized by a Schlieren system and the distributions of static pressure along the upper wavy wall are measured by a scanning valve system with pressure transducers. In numerical analyses, the distributions of streamlines, Mach lines, iso-pressure lines, and iso-mass fractions of liquid are obtained by the two-dimensional direct marching method of characteristics. The effects of stagnation temperature, absolute humidity, and attack angle of the upper wavy wall on the generation and the locations of generation and reflection of an oblique shock wave are clarified. Futhermore, it is confirmed that the wavy wall plays an important role in the generation of an oblique shock wave and that the effect of condensation on the flow fields is apparent.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2003년도 추계학술발표회 논문집
• /
• pp.147-152
• /
• 2003

Aerial Images are usually used to extract 3-D coordinates of various urban features. In this process, the stereo matching of images should be performed precisely to extract these information from aerial Images. In this research, we proposed a matching technique based on geometric features of lanes. We extracted lanes from aerial images and grouped into 4 lane's types. They are lane lines, dotted lines, arrow lane, safety zone. After preprocessing, We will match them by spatial relationships, for example, the distance and orientation between the extracted features. In the future, we will obtain lane coordinates and reconstruct 3-d coordinates of roads.

• Journal of Information Processing Systems
• /
• 제9권2호
• /
• pp.237-246
• /
• 2013

Maintenance Access Hatches are used to ensure urban safety and aesthetics while facilitating the management of power lines, telecommunication lines, and gas pipes. Such facilities necessitate affordable and effective surveillance. In this paper, we propose a FiCHS (Fixed Cluster head centralized Hierarchical Static clustering) routing protocol that is suitable for underground maintenance hatches using WSN (Wireless Sensor Network) technology. FiCHS is compared with three other protocols, LEACH, LEACH-C, and a simplified LEACH, based on an ns-2 simulation. FiCHS was observed to exhibit the highest levels of power and data transfer efficiency.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1572_1573
• /
• 2009

In this study electromagnetic fields generated by currents of electric wires with finite lengths were deduced and formulated to apply to the indoor distribution lines and also using the formula electromagnetic fields were calculated for various configurations of conductors and through analyzing the results mitigation of electromagnetic fields was investigated.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.1259-1265
• /
• 2004

Railway is an important transportation tool for nation's industrial development and public daily life. These days the concern about railway has remarkably been rising due to the April 2004 opening of KTX, Korea High Speed Rail, together with Trans-Continental Railways linking North Korea, China, Russia, through European countries. In the meantime, the issues of train safety and efficiency, arising from the different on-board signaling systems installed on different kinds of trains, have been raised incessantly. In this paper CTCS(Continental Train Control System) is suggested, which can accommodate such various signaling functions as ATP, ATC, ATS, etc. into one single type of on-board signaling system and operate without changing ground signaling systems on the junctions of the Trans-Continental Railways. The development of this CTCS would cause speed-up of exiting lines and possession of railway core solutions for establishing Northeast Asia logistics center bases, which could be an important cornerstone for domestic railway improvements and Korea's role of Northeast Hub.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.35-50
• /
• 2007

A contact patch between the wheel and the rail supports the train body and a traction power comes from it when rolling stocks run on the railroad. Friction force between the wheel and rail makes the train move on the rail. Whenever the train runs on the rail, the wheels and rails wear down by frictions inevitably. So it must be shaped by the lathe or changed for the safety train operation and the comfortable ride. Until now, many measures were carried out in order to prevent a wear and tear of the wheels. For example loop line railway in Kun Ja depot and Ji Chuk depot. This document reports the wheel changing data taken by maintenances department for the period before and after 1996 in the 1.2.3.4 lines in Seoul metro.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 E
• /
• pp.1804-1806
• /
• 1997

Route conditions, applied voltage and the condition of stringing conductors should be considered in determining standard types and skeleton diagrams of towers. In skeleton diagrams the necessary number of insulators and the air clearance have been decided by the results of studies on insulation coordination. Galloping, sleet-jumping, sag characteristics and the possibility of closeness of conductors should be considered according to the condition of stringing conductor and the span. After reviewing those factors, it is necessary to determine the minimum vertical and horizontal distance for the safety of transmission lines under any circumstances. Also it should be economical.

• Journal of Electrical Engineering and Technology
• /
• 제8권2호
• /
• pp.359-363
• /
• 2013

The 765kV transmission line will be maintained by live-line works for efficient operation. In order to maintain the 765kV transmission lines safely by live-line works, lineman has to know switching impulse flashover characteristics of the jumper V-strings with damaged insulators in advance. In order to know the flashover characteristics this paper carried out experimental flashover mockup tests for jumper V-string with damaged insulators in the outdoors. And it suggests flashover characteristics of the 765kV jumper V-strings also. The results will be used in estimating the safety of live working for 765kV transmission lines.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
• /
• pp.810-813
• /
• 2003

The present headway on KNR(Korea National Railway) lines varies from 6 to 10 minutes depending on the each line and by the operation of High Speed line in 2004, the bottleneck would be expected within a few sections such as Daejeon-Daejeon shunting yard which will be the common mute between KTX(Korea Train Express) and conventional trains. Therefore, KNR would like to reduce the headway of the all lines by 4 minutes with the implementation of ERTMS/ETCS on-board system. Where ETCS(European Train Control system), the subsystem of ERTMS, is Automatic Train Protection system for safety train running. This study will be analyze expected braking distance and running time depending on characteristics of conventional passenger and freight trains and high speed train will be operated within electrified conventional line for comparing the headways of ATS(Automatic Train Stop) system and ETRMS/ETCS system within the Daejeon-Daejeon shunting yard section.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2009년도 춘계학술대회
• /
• pp.79-91
• /
• 2009

The government separated and established the industrial safety and health law from the Labor Standard law since 1981 to promote the labor's working environment and to improve the conditions of laborers. The government made a lot of effort to discharge the industrial safety and health law by continuous revision of the law thereafter. it is, however, difficult to establish clear-cut lines of authority and responsibility due to the fact that the substantial application of the industrial safety and health law is adapted by enterprise's autonomous management. There are frequent industrial disasters on the small and medium enterprises which have financial difficulty and it means this causes much more social cost. Finally, for the improvement of laborer's safety, health and working environment in the small and medium enterprises we need to raise the effectiveness of the industrial safety and health law through enhancing a government-office's administration and surveillance with the changing mind of a business proprietor. On this paper, we research on the actual condition of the administration, inspection and regulation of safety and health by means of the industrial safety and health law. Thereafter we analyze how much the Korea Occupational Safety & Health Agency and vicarious businesses of safety & health management help. we used the survey method to gather data from 380 laborers directly and analysed the data by SPSS v17.0.