• Journal of the Ergonomics Society of Korea
• /
• v.36 no.4
• /
• pp.343-353
• /
• 2017

Objective: This study aims to evaluate the efficiency of two representative subway map design types, namely a diagram type and a geographical type using physiological metrics, performance metrics, and self-reported metrics, which are representative usability metrics. Background: Subway maps need to be designed in order for users to quickly search and recognize subway line information. Although most cities' subway maps currently use the diagram type designed by Henry Beck, New York City's subway map has recently been changed to the subway map type combined with the geographical type designed by Michael Hertz. However, not many studies on its efficiency are found, and the studies that are available mainly depend on questionnaire surveys or take on a subjective behavioral study type based on experts' experiences. In this regard, evaluation through a more objective method is needed. Method: This study employed usability metrics as a method to evaluate the efficiency of information search targeting the diagram type and geographical type subway maps used mostly as subway maps. To this end, physiological metrics obtained through eye tracking, task completion time, representative metric of task performance, and subjective evaluation metrics were used for the suitability evaluation of subway map designs. Results: In the result of gaze movement distance analysis, no significant difference was shown in the two design types in terms of a process finding a departure station from the starting point and a process finding a transfer station between the departure station and arrival station (destination). However, the gaze movement distance in the process finding the arrival station at the departure station was significantly shorter in the geographical type, rather than in the diagram type. The analysis of task completion time showed a result similar to the gaze movement distance analysis result. Task completion time was significantly shorter in the geographical type, rather than in the diagram type, which is in the process finding the arrival station at the departure station. In other information search processes, no significant difference was shown. As a result of subjective evaluation metrics analysis, no significant difference was revealed in the two design types. Conclusion: An analysis on the two representative subway map design types was carried out via the adoption of usability metrics. As a result, although no significant difference was shown in some information search processes, it was revealed that information search was easier in the geographical type overall. Also, it was found that usability metrics can be effectively used to evaluate the design types of subway maps. Application: The study results can be used to set design direction to offer ease in information search on subway lines. The study also can be used as a method to evaluate a subway map's design type.

• Journal of the Korean earth science society
• /
• v.39 no.6
• /
• pp.593-599
• /
• 2018

The onset times of P- and S-waves are important information to have reliable earthquake locations, 1D or 3D subsurface velocity structures, and other related studies in seismology. As the number of seismic stations increases significantly in recent years, it becomes a formidable task for network operators to pick phase arrivals manually. This study used a simple method to estimate additional P- and S-wave arrival times for local earthquakes when a priori information (event location and time) is available using the Akaike Information Criterion (AIC). We applied the AIC program to the earthquake data recorded at the seismic station located in Gyeongsan (DAG2). The comparisons of automatically estimated phase arrival times with manually picked onset times showed that 95.1% and 93.7% of P-wave and S-wave arrival time estimations, respectively, are less than 0.1 second difference. The higher percentage of agreement presented the method which can be successfully applied to large data sets recorded by high-density seismic arrays.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.4
• /
• pp.708-717
• /
• 2017

Tracking of sound-location is widely used in various area such as intelligent CCTV, video conference and voice commander. In this paper we introduce the real-time sound-location tracking method for smart lecture system using TDoA(Time Difference of Arrival) with orthogonal microphone array on the ceiling. Through discussion on some models of TDoA detection, cross correlation method using linear microphone array is proposed. Orthogonal array with 5 microphone could detect omni direction of sound-location. For real-time detection we adopt the threshold of received energy for eliminating no-voice interval, signed cross correlation for reducing computational complexity. The detected azimuth angles are processed using median filter for lowering the angle deviation. The proposed system is implemented with high performance MCU of TMS320F379D and MEMs microphone module and shows the accuracy of 0.5 and 6.5 in degree for white noise and lectured voice, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.11
• /
• pp.4503-4508
• /
• 2010

A direction finding(DF) technology of a signal is very important for electronic warfare and has studied for a long time. The method of TDOA(time difference of arrival) is one of good DF methods in this time, and that is to receive an emitter signal with two antennas, to measure the time difference of a signal at two antennas, and converse the time difference to direction of the signal. For small DF error, high time resolution receiver and long baseline are needed. In this paper we suggest a good baseline with adaptive antenna arrangement into 10m*10m area.

• Korean Journal of Social Welfare
• /
• v.47
• /
• pp.243-271
• /
• 2001

This study examines family relationship among North Korean migrant families in early adaptation (approximately, up to $5{\sim}6$ years after arrival in the South). Family cohesion, communication, power relationship, and conflicts and domestic violence among family members were examined by the perceptions of 67 male and female householders and their spouses. In the four areas of family relationship, the subjects have quite positive perceptions and shows no critically significant difference on the perceptions between before and after arrival. However, positive perception on family relationship gradually decreases as the length of time of in the South increases with linear or nonlinear patterns according to subcategories of family relationship. These findings suggest several social work practice implications in resettlement assistance for the North Korean migrant families.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.11 no.2
• /
• pp.27-37
• /
• 1991

The behavior of a negative buoyant flow flowing into a small reservoir is analysed by experiments and dimensional analysis. The nondimensional plunge point, head velocity, head travel distance and the dilution of density current are dependent on the inflow densimetric Froude number, Fre. The thickness of density current, flow pattern and density difference are different from two cases as follows; before the front of head arrive at the downstream end and after. Before the arrival, the thickness of density current is dependent on Fre and after the arrival, time and Fre. It was found that they can be expressed as power laws.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.12 no.5
• /
• pp.267-275
• /
• 2017

Time of difference of arrival (TDOA) method using passive sonar sensor array has normally been used to estimate the location of a concealed moving target in underwater environment. Particle filter has been introduced for effective target estimation for non-Gaussian and nonlinear systems. In this paper, we propose a GPU-based acceleration of target position estimation using particle filter and propose efficient embedded system and software architecture. For the TDOA measurement from the passive sonar sensor, we use the generalized cross correlation phase transform (GCC-PHAT) method to obtain the correlation coefficient of the signal using FFT and we try to accelerate the calculation of GCC-PHAT based TDOA measurements using FFT with GPU CUDA. We also propose parallelization method of the target position estimation algorithm using the GPU CUDA to update the state of each particle for the target position estimation using the measured values. The target estimation algorithm was verified using Matlab and implemented using GPU CUDA. Then, we realized the proposed signal processing acceleration system using NVIDIA Jetson TX1 as the target board to analyze in terms of the execution time. The execution time of the algorithm is reduced by 55% to the CPU standalone-operation on the target board. Experiment results show that the proposed architecture is a feasible solution in terms of high-performance and area-efficient architecture.

• Korean Parent-Child Health Journal
• /
• v.13 no.1
• /
• pp.35-43
• /
• 2010

Purpose: This study was a descriptive research to provide fundamental data in ensuring a high quality of nursing service needed by children's parent according to perception of uncertainty and care satisfaction of them between pediatric outpatient department and emergency room. Methods: For this study, 192 children's parents were questioned in a general hospital located in Busan from August 1 to 31. 2009. The collected data were scored by use of frequencies, $x^2$ test, t-test, AONVA, Pearson's correlation coefficient via SPSS/WIN 17.0. Results: With the compare of characteristics related to children's parents visiting emergency room and pediatric outpatient department, there were statistically significant difference in relation and age of parent, main caregiver, cause of arrival, and waiting time from arrival to procedure. The perception of uncertainty for parent in the emergency room showed significant difference to outpatient department. In nursing service, the highest score was category of professional skill and technic. In addition, overall parents' perceptions on providing information showed lower than any other nursing service. Last but not least, a significant correlation indicated between the perception of uncertainty and satisfaction of nursing service. Conclusion: Efforts to improve parent satisfaction for nursing service are needed to decrease their perception of uncertainty. Providing information and communication by nurses are necessary to improve quality of nursing service.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.4
• /
• pp.315-330
• /
• 2017

Halo coronal mass ejections (CMEs) originating from solar activities give rise to geomagnetic storms when they reach the Earth. Variations in the geomagnetic field during a geomagnetic storm can damage satellites, communication systems, electrical power grids, and power systems, and induce currents. Therefore, automated techniques for detecting and analyzing halo CMEs have been eliciting increasing attention for the monitoring and prediction of the space weather environment. In this study, we developed an algorithm to sense and detect halo CMEs using large angle and spectrometric coronagraph (LASCO) C3 coronagraph images from the solar and heliospheric observatory (SOHO) satellite. In addition, we developed an image processing technique to derive the morphological and dynamical characteristics of halo CMEs, namely, the source location, width, actual CME speed, and arrival time at a 21.5 solar radius. The proposed halo CME automatic analysis model was validated using a model of the past three halo CME events. As a result, a solar event that occurred at 03:38 UT on Mar. 23, 2014 was predicted to arrive at Earth at 23:00 UT on Mar. 25, whereas the actual arrival time was at 04:30 UT on Mar. 26, which is a difference of 5 hr and 30 min. In addition, a solar event that occurred at 12:55 UT on Apr. 18, 2014 was estimated to arrive at Earth at 16:00 UT on Apr. 20, which is 4 hr ahead of the actual arrival time of 20:00 UT on the same day. However, the estimation error was reduced significantly compared to the ENLIL model. As a further study, the model will be applied to many more events for validation and testing, and after such tests are completed, on-line service will be provided at the Korean Space Weather Center to detect halo CMEs and derive the model parameters.

• Journal of KIISE:Information Networking
• /
• v.34 no.5
• /
• pp.389-395
• /
• 2007

It is necessary to research on wireless position determination technology that enables location based services on Portable Internet. In this paper, I consider the position determination technology based on TDOA belong to trilateration method. That is using the difference of relative distance between base stations and terminal due to the time difference of arrival of downlink signal. In order to design the positioning server, This paper reviews the related research on current status of wireless position determination technology based on TDOA on Portable Internet. And then, it is suggested that system architecture, network interface, the calculation model for position determination, which are adapted to circumstance of portable Internet. Through this research on the positioning server, it is expected to guarantee that low cost and high efficiency of wireless positioning server on Portable Internet will be developed.