This research was performed with the subject of 111 offices in a chemical plant of Korea. Airborne concentration level of carbon dioxide, carbon monoxide, formaldehyde and total suspended particulates in the office rooms were measured along with temperature and relative humidity. Simultaneously, general characteristics and subjective health symptoms of 500 office workers were investigated through a questionnaire consisting of the five point weighting method : 0 = not at all, 1 = a little bit, 2 = moderately, 3 = quite a bit and 4 = extremely. Results showed that the mean values for temperature and relative humidity in investigated office rooms were 22.2℃ and 34.3%, respectively. The concentrations of formaldehyde, PM10, carbon dioxide and carbon monoxide were 0.17 ppb, 28.8 ㎍/㎥, 0.95 ppm and 424 ppm, respectively. 56.4% of all the workers investigated replied with a sense of fatigue or weariness (mean=2.23), drowsiness or languidness (mean=2.22), sneezing (mean=2.11) and ophthalmia oreye fatigue (mean=2.07). Female workers, non-smokers, non-drinkers, workers who do shift more than nine hours a day, and workers in poor health experienced more subjective symptoms than other workers (p<0.05). Subjective symptoms of office workers were significantly associated with the following items of office characteristics: the purchase date of office equipment, the change of office furniture, the use of paint, smoking in the office, ventilation condition, the use of an individual air-conditioner, the use of a fax machine, the degree of office repair, the proportion of workers per office, the degree of satisfaction in office environment, and the operation hours of the air-conditioner. Also, subjective symptoms were positively correlated with indoor environmental factors such as relative humidity, carbon dioxide level, level of PM10, and formaldehyde (p<0.05). In conclusion, office characteristics and air quality in a chemical plant affected subjective health symptoms of office workers. Thus, in order to improve the health of workers, to enhance work efficiency, and to establish a better office environment, air quality control in office rooms by optimal ventilation, adequately occupied number of workers in one office, and maintenance of office equipment should be fulfilled thoroughly. keywords：Air quality, Subjective health symptom, Formaldehyde, PM10, Carbon monoxide, Carbon dioxide

석유화학, 발전 플랜트와 같이 대단위 면적에 대해서 효율적인 비용으로 고위험 시설물 및 설비에 대한 지속적인 모니터링을 위해 서는 무선통신기술에 대한 요구가 증가되고 있다. 그러나 현재의 지그비(Zigbee), 블루투스(Bluetooth) 와 같은 USN기술은 신뢰성 및 보안성 이 취약하여 대규모 플랜트 환경에 적용이 불가하다. 따라서 플랜트 현장에 무선기술을 도입하기 위해서는 ISA(International Society of Automation)과 같은 공신력 있는 표준화 기구에서 제안한 새로운 무선 표준기술의 적용이 필요하다. 본 연구에서는 무선 트랜스미터 기반의 석 유화학 플랜트 안전관리 시스템을 개발하였다. 이를 위해 ISA100.11a 통신모듈 및 LTE 통신모듈을 탑재한 방폭형 무선 트랜스미터를 개발하 였다. 그리고 개발 된 무선트랜스미터를 기반으로 IoT기술을 적용한 석유화학 플랜트 안전관리 시스템을 구축하였다.개발된 시스템은 다양한 방법의 테스트 및 테스트베드 구축을 통해 현장적용성을 검증하였다.

The purpose of this study was to evaluate the partial oxidation of the biological treatment plant effluents using Fenton`s reagent as a pretreatment step prior to a tertiary biological oxidation of these effluents. Fenton`s reagent was evaluated as a pretreatment process for inhibitory or refractory organics. Based on the Fenton oxidation system, the petrochemical wastewater treatment plant effluent was shown to have significant improvement in toxicity after oxidation with hydrogen peroxide. For example, at range of 42∼184 ㎎/L COD of petrochemical plant effluents, the COD removal efficiencies were from 38.2% to 60.1% after reaction with hydrogen peroxide 200 ㎎/L and Fe^2+ 100 ㎎/L and reaction time was 30 minutes. The total TOC reduction were about 15.8∼22.4% with same test condition and difference between the overall removal rate and BOD/COD ratio after Fenton`s oxidation estabilished in the biodegradation and otherwise meets the discharge standard or reuse for cooling tower make-up water.

Reuse of industrial effluents through the cooling systems in a petrochemical complex was described. The partial oxidation of the effluents from the biological treatment plant was examined, using Fenton`s reagent as a pretreatment step prior to a next treatment of the effluents. Next tertiary treatment using fixed-film reactor resulted in marked reductions in COD and suspended solids. The continuous fixed-film process with Fenton oxidation pretreatment showed a 23% increase in the COD removal efficiency when compared to that without pretreatment of Fenton oxidation under the volumetric organic loading rate of 0.1 ㎏ COD/㎥/day. The Fenton oxidation treatment seemed to be a possible method for tertiary biological treatment to reduce the residual toxicity with the enhanced biodegradation of the effluents.