• Communications for Statistical Applications and Methods
• /
• v.6 no.3
• /
• pp.947-956
• /
• 1999

We define a crossing point $x_0$ such that f(x)$\geq$g(x) for x$\leq$$x_0$ and f(x)$\leq$g(x) for x>$x_0$ where f and g are probability density functions. We may encounter suchy situation when we compare two histograms from two independent observations. For example two contingency tables where initially admitted students and actually enrolled students are classified according to their high school ranking may show such situation, In this paper we consider maximum likelihood estimation of cell probabilities when a crossing point exists, We first assume a known crossing point and find an estimator. The estimation procedure for the case of unknown crossing point is just a straightforward extension. A real data is analyzed for an illustrative purpose.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1544-1549
• /
• 2004

A new collision avoidance algorithm is presented for two mobile robots in narrow corridor environments. When two robots meet each other in a narrow corridor, one should yield the way to the other robot. To solve the problem arising in this situation, they exchange their path to get information about crossing-points to check avoidance conditions, which are necessary for choosing the robot to yield. The conditions are summarized as follows. 1) If one robot blocks the path to the closest crossing-point in front of the other robot. 2) If the closest crossing-point of each robot is the same point. 3) Which robot is closer to the closest crossing-point. In this paper, we propose a path planning algorithm for the robot which yield the way. Simulation results are presented to verify the feasibility of the proposed collision avoidance algorithm.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.1-10
• /
• 2017

This paper presents a novel predictive digital control method for boundary conduction mode PFC converters without the need for detecting the inductor current. In the proposed method, the inductor current is predicted by analytical equations instead of being detected by a sensing-resistor. The predicted zero-crossing point of the inductor current is determined by the values of the input voltage, output voltage and predicted inductor current. Importantly, the prediction of zero-crossing point is achieved in just a single switching cycle. Therefore, the errors in predictive calculation caused by parameter variations can be compensated. The prediction of the zero-crossing point with the proposed method has been shown to have good accuracy. The proposed method also shows high stability towards variations in both the inductance and output power. Experimental results demonstrate the effectiveness of the proposed predictive digital control method for PFC converters.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.389-390
• /
• 2007

In this paper, we propose a modified watershed algorithm to obtain exact edge of region. The proposed method adjusts priority at zero-crossing point of gradient in order to make the point of region decision time postponed. We compare the proposed method with a previous method and prove that this method can extract more correct edge of region.

• Proceedings of the KIEE Conference
• /
• 2003.10b
• /
• pp.286-288
• /
• 2003

Accidents at level crossing where railways and roads cross cause many casualties because of collision of cars etc and it also has a risk of the 2nd accident of trains. it is the most vulnerable point in the railway safety. Fundamental solution for accidents at level crossing is making the crossings cubic. but it can't be easily progressed because of environmental and financial difficulties. every kind of anti-accident measures are being strived for. one of the strived results is level crossing obstacle detector which automatically detects obstacles like defected cars etc in the middle of level crossing and transmits the information of obstacles to the approaching train. However present level crossing obstacle auto detector needs high expenses to be installed and has difficulties that lenses of beam transmitter, beam receiver should be cleaned in snowing winter. this document reviews level crossing obstacle auto detector using ultrasonic sensor to measure these difficulties.

• Journal of Korean Society of Transportation
• /
• v.26 no.5
• /
• pp.91-100
• /
• 2008

Pedestrians are exposed to accidents as a result of the lack of understanding the meaning of a flashing green signal. This study was to designed to relate changes of pedestrians' crossing characteristics as a functions of flashing green signal timings. A field survey was conducted to collect pedestrian preference and safety and it was examined by signal operation experiment. Two versions of new pedestrian signal timings were compared to the existing pedestrian signal timings. The results indicated that the number of pedestrians who starts to cross during flashing green signals was significantly decreased when flashing green signals started at 1/2 or 2/3 point of crossing. However, the number of pedestrians who remain in the crossing during red signals was significantly increased when flashing green signals started at 2/3 point of crossing. This study concludes that starting flashing green signals at 1/2 point of crossing is the safest. Also, implication and directions for its practical relevance were discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.88-91
• /
• 2007

Turnout system is a mechanical installation enabling trains to be guided from one track to another which is consists of point blades, common crossing and guard rail etc. These structural feature causes vibration, noise and damages while railroad car wheel is passes by. A tilting train is a train with a tilting mechanism that enables increased speed on regular railroad tracks. The aim of this paper is to study a characteristics of the shock-vibration and noise of tilting and existing train passes by turnout systems. To analyze and assesment, noise and vibration measurement was carried out at the Naesu-station of Chungbuk-line which equipped with cast manganese crossing and built-up crossing and Illo-station of Honam-line which equipped with cast manganese crossing.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.724-730
• /
• 2011

A turnout serves to switch train from one line to another. The turnout consists of a Point which is switchs the rail to induce direction, and a Crossing which is cross over two line on the plane surface, and a Lead where is middle section in Point to Crossing. Point machine, consists of a turnout, is important facilities in railway signal, that is safety issue relates in derailment of the train. Recently, train delay and accident frequently occurred because of the turnout include in a point machine trouble of electrical and mechanical. So in order to prevent train accident the research is advanced, install of normal and reverse indication lamp in a point machine, development of adherence detector for sensing the status of adhesion between the stock rails and tongue rails etc. In this paper investigates the problem which is connected with a turnout trouble, include in a point machine, occurrence at the time of train accident, and then proposed to the safety system model in order to prevent the train accident in turnout.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.5
• /
• pp.879-884
• /
• 2009

A Method for detection of saturation of a current transformer(CT) is proposed. The algorithm is initiated when the end point of a saturation period is detected. This detection is achieved by checking the time interval between the adjacent zero-crossing points of the second derivative of the secondary current. Once the end point of the saturation period is detected, the beginning point of the corresponding saturation period is determined by backward examination of the sum of the secondary current from the end point. The performance of the algorithm was evaluated for a-g faults on a 345 kV 100km overhead transmission line. The Electromagnetic Transient Program(EMTP) was used to generate fault current signals for different fault inception angles and different remanent fluxes. The performance evaluation shows that the proposed algorithm successfully detects the saturation period even in the presence of a remanent flux.

• Journal of Korean Medical classics
• /
• v.32 no.1
• /
• pp.145-158
• /
• 2019

Objectives : This study attempts to identify the concept of Link meridian in previous medical books, and explore how Link meridian theory was used in a clinical practice focusing on YeTianshi. Methods : This study looked at the medical books related to acupuncture and moxibustion in the past and the part where Link meridian is mentioned in the annotations of "Huangdineijing" and "Nanjing", and examined how medical doctors prior to YeTianshi used Link meridian in a clinical practice. And then this study examined treatment cases in the medical records of YeTianshi. Results ＆ conclusions : Yang-Link meridian and Eum-Link meridian were arranged as ascending route by the majority of medical doctors. However, there are doubts because startpoints of them are not "Jeyanghoe" and "Jeeumgyo" respectively described in "Nanjing". Link meridian is thought to be a structure that connects each meridian passing through crossing points with each crossing point itself as a starting point. Thus, Link meridian can be seen as a role in strengthening the connection of crossing meridians and balancing and controlling those meridians centering on each crossing point. The point that YeTianshi's identifying that pathology of Eight extra meridians associates with liver and kidney(肝腎) to be a symptom of weakness, and his development of Link meridian's physiology and pathology through the relationship with other Eight extra meridians are thought to be more advanced than the previous medicine prior to YeTianshi.