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Intermittent or periodic signals with undulating amplitudes of mobile devices cause interference noise at audible frequency to the sound system which is installed nearby. In this regard, it is recently issued that the intermittently transmissions of LTE mobile phones cause the interference noises with sound systems, similar to that of GSM mobile phones. For retaining the immunity to noises, a national regulation KN20 suggests a 1 kHz AM 80 % and a CDMA modulation signal as reference signals for immunity test of sound and television broadcast receiver. In this paper, the effects of interference noises of AM and CDMA are compared with those of GSM and LTE, and the improvement of reference signal for national immunity test of sound systems is suggested. It is recommended to delete the CDMA modulation signal from reference signals for immunity test because it hardly cause interference noise with sound systems. On the other hand, it is desirable to select the modulation signal of LTE instead of CDMA as a reference signal for immunity test of sound system and television broadcast receiver because many people use the LTE service and it is analysed that the LTE signal causes considerable interference noises.

Various air pollution control (APC) techniques were employed in order to reduce emissions of air pollutants produced from chemical plants, which have many different chemical production facilities. For an emission reduction of acid gases, this study employed a method to improve solubility of pollutants by decreasing the operating temperature of the scrubbers, increasing the surface area for effective contact of gas and liquid, and modifying processes in the acid scrubbers. To reduce emission of both amines and acid gases, pollutant gas components were first separated, then condensation and/or acid scrubbing, depending on the chemical and physical properties of pollutant components, were used. To reduce emission of solvents, condensation and activated carbon adsorption were employed. To reduce emission of a mixture gases containing acid gases and solvents, the mixed gases were passed into the first condenser, the acid scrubber, the second condenser, and the activated carbon adsorption tower in sequence. As a strategy to reduce emission of pollutants at the source, this study also employed the simple pollution prevention concept of modification of the previously operating APC control device. Finally, air emissions of pollutants produced from the chemical plants were much more reduced by applying proper APC methods, depending upon the types (physical or chemical properties) and the specific emission situations of pollutants.

The objective of this study was to evaluate the exposure to Asian dust by determining the number of patients of some departments in hospitals including the dermatology, otolaryngology, visceral disease, cardiovascular disease, and ophthalmology. That might be affected by the Asian dust events. There were 8 cities in Korea selected to study as follows: Seoul, Busan, Daegu, Incheon, Kwangju, Deajeon, Ulsan and Jejudo. This investigation was carried out during Asian dust and non-Asian dust periods in 2005 and the first half of 2006. This information was obtained from National Health Insurance Corporation (NHIC). The PM10 concentrations during Asian dust episode in 8 cities were collected from the monthly and annual reports of ambient air quality in Korea which were published by Korean Ministry of Environment (MOE). There were the differences of PM10 concentrations in different cities during Asian dust episode due to the origins or sources of Asian dust, the paths of Asian dust, the local wind characteristics and the difference in geological locations. The differences of PM10 between the cities during non-Asian dust periods depend on the characteristics of each region. The monthly variations of number patients in all cities generally showed a similar trend. The strong correlation between Asian dust events and the number of patients were obtained. In most cities, each kind of disease had its specific trend of variation. These variations might be affected by many factors including PM10 concentration in ambient air; weather conditions such as temperature, humidity; and human activities.

An analysis on polycyclic aromatic hydrocarbons (PAHs) deposited in road dust at downtown areas in a large city of Korea, Ulsan, was carried out in March 2006 to identify the concentrations as well as characteristics of these compounds. Road dust samples were taken at 3 sites in which 2 sites are in downtown areas and 1 site is in a typical residential area of Ulsan. Road dust samples were separated into 4 particle size categories as follow: 850 mum - 2000 mum, 180 mum - 850 mum, 75 mum -180 mum, and less than 75 mum. After being extracted by a mixture of dichloromethane and n-hexane (1:1), the extract was filtered and concentrated to 2 ml by using nitrogen evaporator. 16 PAHs included in USEPA list were analyzed by high performance liquid chromatography (HPLC) method. At downtown areas, individual PAHs concentrations in road dust ranged from 0.06 ng.g-1 to 146.43 ng.g-1; the total PAHs concentrations ranged from 39.23 ng.g-1 to 309.70 ng.g-1, depended on particle size of road dust samples. Based on size fractions of road dust in each area, PAHs contents in a weight unit of road dust were estimated. PAHs contents in road dust at 2 downtown areas were 52.46 ng.g-1 and 245.12 ng.g-1, respectively. The concentrations of PAHs in road dust in 2 downtown areas were quite different because of the differences in vehicle density and speed. When compared with road dust in a typical residential area, the concentrations 0/ PAHs in road dust at downtown areas were much higher, from 2.7 times to 12.4 times.

This study identified emission sources and emissions of air pollutants such as volatile organic compounds (VOCs), solvents, and acid gases produced from chemical plants. We collected air samples from various processes, reactors and facilities using VOC detectors and workers' experience. We identified chemical structures and emission concentrations of air pollutants. We analyzed total emissions of air pollutants emitted from the chemical plants. Also, we developed some emission reduction technologies based on chemical types and emission situations of the identified air pollutants. For reduction of air emissions of acid gases, we employed a method improving solubility of pollutants by reducing scrubber operation temperature, increasing surface area for effective contact of gas and liquid, and modifying or changing chemicals used in the acid scrubbers. In order to reduce air emissions of both amines and acid gases, which have had different emission sources each other but treated by one scrubber, we first could separate gas components. And then different control techniques based on components of pollutants were applied to the emission sources. That is, we first applied condensation and then acid scrubbing method using H2SO4 solution for amine treatment. However, we only used an acid scrubbing method using H2O and NaOH solution for acid gas treatment. In order to reduce air emissions of solvents such as dimethylformamide and toluene, we applied condensation and activated carbon adsorption. In order to reduce air emissions of mixture gases containing acid gases and slovents, which could not be separated in the processes, we employed a combination of various air pollution control devices. That is, the mixture gases were passed into the first condenser, the acid scrubber, the second condenser, and the activated carbon adsorption tower in sequence. In addition, for improvement of condensation efficiency of VOCs, we changed the type of the condensers attached in the reactors as a control device modification. Finally, we could successfully reduce air emissions of pollutants produced from various chenmical processes or facilities by use of proper control methods according to the types and specific emission situations of pollutants.