• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.10a
• /
• pp.25-27
• /
• 2022

Recently, with the development of the 4th industry, environmental issues such as air pollution have become serious, and in particular, a lot of air pollutants are generated in industrial sites. There are various types of air pollutants, and among them, carbon monoxide is essential for fires occurring in industrial sites, so it should be possible to monitor in real time. In addition, there is a need for a remote monitoring system that can measure various environmental factors other than air pollutants in real time. In this paper, we propose a monitoring system using wireless communication to remotely measure the industrial environment. The proposed monitoring system collects data to the Arduino of the transmitter by using a carbon monoxide sensor, a combustible gas sensor, a temperature and humidity sensor, and a flame sensor, and then transmits it to the receiver using ZigBee. The transmitted data is stored in the database of the receiver Raspberry Pi, and the stored data can be monitored in real time through the monitoring system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.4
• /
• pp.932-939
• /
• 1998

In this paper, we analyze the performance of a multicode-CDMA system which have been proposed for the multimedia communications. The performance of a multicode-CDMA system, providing good spectrum efficiency as well as serving various bit rates, is analyzed with multipath, frequency selective, slowly fading Rayleigh channel. Also the proposed scheme adopting RAKE receiver with MRC(Maximal Ratio Combine) is advantageous to multipath channel. For a practical channel modeling, the JTC(Joint Technical Committee) recommended channel model(JTC(AIR) 23-065R6) is applied to simulation. The proposed schemehas serial-to-parallel convertor which splits input data stream of 2 Mits/s into 20 branches o 100 kbits/s. From the result of simulation, the case of RAKE receiver with 3 fingers to reduce the system complexity required the relatively large $E_{b}/N_O$ of 0 dB~1.5 dB, compared to the case of RAKE receiver with the number of path finger to keep the average error rate to be $1{\times}10^{-3}$ in channel A.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.638-643
• /
• 2011

The aluminum soundproofing panel used to the traffic noise reduction will judge with the material to improve because the CO2 emission is greater than other soundproofing panel such as plastic soundproofing panel. Also, if the air-passing soundproofing panel which can endure the fast wind velocity will be developed, it judged that it can reached to the target of low CO2 traffic technology development using the reduction of material cost and the lower consumption of steel. The objective of this study is to improve the soundproofing panel and to develop the air-passing soundproofing panel for the replacement of aluminum sound proofing panel which is more emit CO2 than other soundproofing panel. And, we tried to develop the reduction technology of CO2 emission through the development of air-passing soundproofing panel. At first, the flow and noise simulation were conducted for the purpose of the calculation of wind pressure on soundproofing wall and noise exposure level on receiver points according to the open ratio of air-passing soundproofing panel. And the 1st and 2nd mockup of air-passing soundproofing panel were made, and the design load test were conducted for these mockup.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.10 no.4
• /
• pp.220-228
• /
• 2002

The cool-down performance after soaking is very important in an automotive air-conditioning system and is considered as a key design variable. Therefore, transient characteristics of each system component are essential to the preliminary design as well as steady-state performance. The objective of this study is to develop a computer simulation model and ostinato theoretically the transient performance of an automotive air-conditioning system. To do that, the mathematical modelling of each component, such as compressor, condenser, receiver/drier, expansion valve, and evaporator, is presented first of all. The basic balance equations about mass and energy are used in modelling. For detailed calculation, condenser and evaporator are divided into many sub-sections. Each sub-section is an elemental volume for modelling. In models of expansion valve and compressor, dynamic behaviors are not considered in this analysis, but the quasisteady state ones are just considered, such as the relation between mass flow rate and pressure drop in expansion device, polytropic process in compressor, etc. Also it is assumed that there are no heat loss and no pressure drop in discharge, liquid, and suction lines. The developed simulation model is validated by comparing with the laboratory test data of an automotive air-conditioning system. The overall time-tracing properties of each component agreed well with those of test data in this case.

• Solar Energy
• /
• v.12 no.1
• /
• pp.88-94
• /
• 1992

A small-scale solar collector and tracking system, using a Fresnel lens of $0.5m^2$, and novel compact fluidized-bed solar receiver[FBR] of closed type has been developed for high temperature solar gas heating. The FBR was improved in carrying over of SiC powder and thermo-siphon effect. The maximum outlet air temperature of 1140K and the maximum thermal efficiency of 64% were obtained. The present FBR's operated efficiently at extremely high temperatures in comparison with conventional solar receivers, composed of flat or tubular solid surfaces.

• Journal of Communications and Networks
• /
• v.14 no.4
• /
• pp.410-417
• /
• 2012

One of the premier mechanisms used in extracting unobserved signals from observed mixtures in signal processing is employing a blind source separation (BSS) algorithm. Orthogonal frequency division multiplexing (OFDM) techniques are playing a prominent role in the sphere of multicarrier communication. A set of remedial solutions taken to mitigate deteriorative effects caused within the air interface of OFDM transmission with aid of BSS schemes is presented. Four energy functions are used in deriving the filter coefficients. Energy criterion functions to be optimized and the performance is justified. These functions together with iterative fixed point rule for receive signal are used in determining the filter coefficients. Time correlation properties of the channel are taken advantage for BSS. It is tried to remove colored noise and jamming components from themixture at the receiver. Themethod is tested in a slow fading channel with a receiver containing equal gain combining to treat the channel state information values. The importance is that, these are quite low computational complexity mechanisms.

• ETRI Journal
• /
• v.19 no.3
• /
• pp.116-140
• /
• 1997

The base station transceiver subsystem (BTS) of the CDMA Mobile System is interfaced to mobile stations over the air and to the wired network through a packet switched interconnection network. The potential benefits of CDMA technology are achieved when the transmitter and the receiver are properly designed and implemented. The physical layer of the interface at the base station is implemented with the CDMA ASICs and control circuits in channel card of the BTS. We present the design perspectives and structural illustration of the BTS. Base station modem ASICs and their control to implement the CDMA receiver, Baseband and RF signal processing blocks, and BTS controller are described. Elaborate power control is essential to ensure the high capacity which is one of advantages of the CDMA technology. The closed loop reverse link power control and the forward link power control operated in the BTS are described.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.05a
• /
• pp.550-551
• /
• 2021

Positioning technology is performing important functions in augmented reality, smart factory, and autonomous driving. Among the positioning techniques, the positioning method using beacons has been considered a challenging task due to the deviation of the RSSI value. In this study, the position of a moving object is predicted by training a neural network that takes the RSSI value of the receiver as an input and the distance as the target value. To do this, the measured distance versus RSSI was collected.

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.1
• /
• pp.59-67
• /
• 2013

The odor occurring in the sewage system induces the displeasure, the disgust such as the headache, the vomit, etc. and increases the spiritual stress and disturbs the pleasant life of residents. These odors occur mainly in the area of combined sewage system treatment, being created in the personal sewage treatment plant such as septic tank and are incoming to sewage pipes and emitted to the outside through the manhole and the receiver, etc.; and this causes odors to the people. The Hydrogen Sulfide, the Methyl Mercaptan, the Ammonia, etc. are materials causing the odor, the more serious issue of odor is occurring since the septic tank of degradation process is being applied. The primary cause of odor is the decomposition of human feces in the septic tanks and sewage disposal facilities. The purpose of this study is reduction of hydrogen sulfide using air supplying and SOB(Sulfur-Oxidizing Bacteria). As a result of this study of the air supply system and the SOB media equipment by air supply, in case the air is injected to SOB media compared to the injection of air only, the removal efficiency the hydrogen sulfide was average 3.4 times higher.

• Tribology and Lubricants
• /
• v.26 no.6
• /
• pp.341-345
• /
• 2010

The NAUT(Non contact Air coupled Ultrasonic Testing) is one of the ultrasonic wave inspection methods. It compensates High power ultrasound Pulser Receiver, pre-amp, air probe of high sensitivity in air to generate loss energy by NAUT methods. Generally, in case of ultrasound inspection, it applies contact methods by using couplant. However it can inspect of UT without couplant by this NAUT. The ultrasound transmission reception is composed in stable condition in NAUT. It can inspect high low material or the specimen of rough part, the narrow spot, too. The spot welding is applying the inosculation of automobile component, car body, all boards. The CFRP is necessity of NDE because of the solidity changes material according to lamella tearing. Therefore it checked on realization whether and commercialization in the spot welding and CFRP inspection that the NAUT would be applied them.