• Journal of the Korean Society of Radiology
• /
• v.13 no.7
• /
• pp.1035-1043
• /
• 2019

The object of is this research is to find out the optimal Tesla by evaluating SNR and CNR, after testing 1.5 T and 3.0 T. The randomly selected patients tested by nasopharynx MRI transmitted in PACS were applied to the research. Two MRI units(1.5 T, 3.0 T) was used for analyzing the data. As a method of analysis, in T1W highlighting and T1 fat removal images, we set up a certain area of interest and evaluated the SNR and CNR on tongue, spinal cord, masseter muscle, fat, parotid gland, and tumor tissue. We evaluated the SNR and CNR by quantitative analysis of six tissue, measuring the quality of images for uniform fat removal, magnetic sensitivity artifact on a four-point scale by qualitative analysis. The statistical significance of this date analysis was based on independent sample verification and was accepted when the P value was less than 0.05. As a result of analysis of both devices, 3.0 T was high in the quantitative evaluation, while 1.5 T was high in the qualitative evaluation. Considering the advantages and disadvantages of each device, and if the device is selected complementarily and applied to patients, it is believed that it will provide the optimal information.

• Journal of Soil and Groundwater Environment
• /
• v.10 no.1
• /
• pp.65-74
• /
• 2005

National groundwater monitoring stations have been managed throughout the country by Korea Water Resources Corporation (KOWACO) in order to monitor variations in quantity and quality of groundwater resources. A multi-sensor installed in each monitoring station well measures groundwater level, water temperature and electrical conductivity every six hours and the logged data are automatically transmitted to a host computer in KOWACO. Meanwhile despite regular station inspection and replacement of deteriorate or broken devices, abnormal values or outliers often occur due to intrinsic limitations of automatic monitoring and transmission. Thus prompt recognition and measures to these values are essentially required to reduce disturbance and missing period of the data. In this study, time and frequency of outlier occurrence were analyzed for the water level data obtained from national groundwater monitoring stations within the Han river basin in 2000. The analysis results indicated that the most prominent patterns of the outliers were rapid decline for water level, no variation for temperature and steep decline for electrical conductivity. This study provided a sample criterion for determining the outlier for each parameter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.1
• /
• pp.125-131
• /
• 2006

The existing X-ray generators are either ones which are settled at fixed places or ones which are movable to sick rum. Movable generators can be very useful according to the circumstances of patients, but there remains a restraint that AC220[V] in the hospitals must be provided. When examining a first-aid patient who stays distant from the hospital or when grouping patients caused by disaster, the services of doctors at emergency centers should be very restrictive. Hence, this study developed a portable digital X-ray power supply unit that are utilizable at the accident spot or in a moving ambulance. By using the nit, the information of patients can be transmitted to the emergency center on the spot and thereby doctors can make a correct diagnosis. The properties of the unit are as follows: First, portable batteries(DCl2[V]) are utilized as electric source for the wit. Second PIC16F84A is utilized as control circuit in order to guarantee considerable reliance and to provide various functions. This portable digital X-ray power supply unit is expected to contribute to the emergency medical service system to be more advanced.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5843-5848
• /
• 2011

To improve the efficiency of the channel spectrum and to reduce the power consumption of the system in EVRC, the voice signal is compressed and transmitted only when the user speaks to. In addition to this, voice frames are divided into three rates 1, 1/2 and 1/8 and each frame is handled differently. For example, we assumed that the input is silence region if the 1/8 rate is used. In this paper, the sections are firstly separated into the voiced speech signal region, unvoiced speech signal region, and silence region by using distribution characteristics of LSP parameters. Then the paper suggested to encode 1 rate for the voiced speech signal, 1/2 rate for the unvoiced speech signal region, 1/8 rate for the silence region. In other words, traditional way of transmission is used when sending full rate in the EVRC. However, when sending half rate, the voice is firstly distinguished between voiced and unvoiced. If the voice is distinguished as voiced, voice is converted into full rate before the transmission. If it is distinguished as silence, EVRC's basic rate is applied. In the experimental results with SNR, ASDM, transmission bit rate measurement, we have demonstrated that voice quality was improved by using the proposed algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.5
• /
• pp.1154-1163
• /
• 2008

DAS and SCADA system are main systems, which operate and manage the power system by using computer and communication technology. But DAS and SCADA have been operated independently in Korea, so there was some time delay in the fault handling and live-line work. To improve that problems, studies on the interface between DAS and SCADA have been needed. From November 2005 to December 2007, the pilot project has been performed in KEPCO's branch offices, as a result, direct method will be applied widely all over the country until 2010 because the operation information of substation users want can be transmitted fast and it is possible to control 43RC directly although the expense for direct method is about 1.3 times larger than that for web method. To improve problems revealed during the pilot project, substation object to object communication method is proposed and interface database automatic generation and interface system diagnosis and logging functions are developed. Interface data point and communication data type are defined, substation single line diagram automatic generation or manual editing function, SCADA monitoring and controlling function, log data managing function are developed in SCADA HMI program. It is expecting to reduce the average time for each outage about 33% and to improve the reliability, efficiency of operation, execution of DAS from automatic load transfer under a fault, and to contribute to export project.

• KIISE Transactions on Computing Practices
• /
• v.21 no.6
• /
• pp.430-435
• /
• 2015

IP-based, next generation digital broadcast systems transmit DASH segment files. Designed by the DASH system, DASH segment files provide variable quality of contents, while the size of DASH segment files varies even if the file has the same quality. Delays and inefficient use of resources are major challenges in the transmission of variable size DASH segment files in broadcasting systems. Traditional broadcasting transmission systems are designed according to characteristics of physical layer of broadcast, and thus, delay and inefficient resources use is difficult to find. Yet, transmission content quantities continue to rise in the next-generation broadcasting systems (e.g. FHD, UHD (4k, 8k)) with variability of the segments file size as well. Resources for next-generation broadcast are more abundant than traditional broadcast with recent development, but continue to be limited and fixed. Resource delay and inefficiency are important but has not been extensively studied. We propose a transmission structure solution to analyze the delay and efficiency of the resource as each DASH segment file is transmitted, and have further performed simulation studies.

• Journal of Satellite, Information and Communications
• /
• v.7 no.3
• /
• pp.99-104
• /
• 2012

The United States will proceed with the effort to modernize the GPS system, and one of its main content is to provide L5 signal. L5 will be transmitted in a radio band reserved exclusively for aviation safety services. And, L5, in combination with L1, will improve the position accuracy via ionospheric correction and robustness via signal redundancy. However, The acquisition processing time of L5 takes longer than that of L1 as the code length of L5 is 10 times longer than that of L1. To reduce this acquisition processing time, a higher number of correlators in the aquisition module should be used. However, there is a problem that this causes increase in the complexity of the correlator configuration and the computation power. So, in this paper, we propose L5 signal tracking scheme using tracking results in the GPS L1/L5 receiver. The proposed scheme could reduce the hardware complexity as the GPS L5 signal acquisition module is not needed, and provide fast and stable tracking of L5 signal by aiding L1 tracking results such as PRN, the code phase synchronization, and the Doppler frequency. The feasibility of the proposed scheme is demonstrated through simulation results.

• Journal of Biomedical Engineering Research
• /
• v.24 no.5
• /
• pp.411-419
• /
• 2003

This paper aims at developing 'gyro-mouse' which provides decent and comfortable human-computer interface that supports the usage of such software as an internet-browser in PC for the people paralyzed in upper limbs. This interface operates on information collected from head movement to get the cursor control. The interface is composed of two modules. One is hardware module in which the head horizontal and vertical angular velocities are detected and transmitted into PC. The other is a PC software that translates the received data into movement and click signals of the mouse. The ANN (artificial neural network) learns the quick nodding pattern of each user as click input so that it can provide user-friendly interface. The performance of the system was evaluated by three indices that are click recognition rate. error in cursor position control. and click rate of the moving target box. The performance result of the gyro-mouse was compared with that of the optical-mouse to assess the efficiency of the gyro-mouse. The average click recognition rate was 93%, average error in cursor position control was 1.4∼5 times of optical mouse. and the click rate with 50 pixels target box was 40%(30 clicks/min) to that of optical mouse. The click rate increased monotonously with the number of trial from 35% to 44%. The suggested system is expected to provide a new possibility to communicate with the society.

• The KIPS Transactions:PartC
• /
• v.13C no.6 s.109
• /
• pp.709-716
• /
• 2006

According to the increase of various AV media devices and contents in the digital home, the DLNA becomes to play an important role as the interoperability standard between then Since this guideline only focuses on the interoperability among home networked devices, media players, and media contents existing inside of the homenetwork, there is no retrieval and transmission method for sharing multimedia contents located over several homes via Internet. Additionally, this guideline lets device-detection and notification messages to be transmitted using W multicast methods, and current Internet environment cannot guarantee consistent IP multicast services, it has the limitation that it cannot retrieve and control DLNA devices in other digital homes remotely via the Internet. Therefore, in this paper, we propose the IHM(Inter-Home Media) proxy system and its operating mechanism to provide a way of sharing media contents distributed over multiple DLNA-based homes, through analyzing these limitations and building up a sharing method for A/V media contents distributed over the DLNA homes based on the dynamic or private IP networks. Our method removes the limitation on the user locations through sharing distributed media contents, and also makes cost-downs for storing media contents, from the view point of individual residents.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.327-332
• /
• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.