• 한국환경과학회지
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• 제18권11호
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• pp.1215-1224
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• 2009

This study evaluated the applicability of visible-light-driven N- and S-doped titanium dioxide($TiO_2$) for the control of low-level dimethyl sulfide(DMS) and dimethyl disulfide(DMDS). In addition, a photocatalytic unit(PU)-adsorption hybrid was evaluated in order to examine the removal of DMS and DMDS which exited the PU and a gaseous photocatalytic byproduct($SO_2$) which was generated during the photocatalytic processes. Fourier-Tranform-Infrared(FTIR) spectrum exhibited different surface characteristics among the three-types of catalysts. For the N- and S-doped $TiO_2$ powders, a shift of the absorbance spectrum towards the visible-light region was observed. The absorption edge for both the N- and S-doped $TiO_2$ was shifted to $\lambda$ 720 nm. The N-doped $TiO_2$ was superior to the S-doped $TiO_2$ in regards to DMS degradation. Under low input concentration(IC) conditions(0.039 and 0.027 ppm for DMS and DMDS, respectively), the N-doped $TiO_2$ revealed a high DMS removal efficiency(above 95%), but a gradual decreasing removal efficiency under high IC conditions(7.8 and 5.4 ppm for DMS and DMDS, respectively). Although the hybrid system exhibited a superior characteristic to PU alone regarding the removal efficiencies of both DMS and DMDS, this capability decreased during the course of a photocatalytic process under the high IC conditions. The present study identified the generation of sulfate ion on the catalyst surface and sulfur dioxide(maximum concentrations of 0.0019 and 0.0074 ppm for the photocatalytic processes of DMS and DMDS, respectively) in effluent gas of PU. However, this generation of $TiO_2$ would be an insignificant addition to indoor air quality levels.

• 한국가구학회지
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• 제20권2호
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• pp.115-121
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• 2009

This study examined the emission characteristics and psychological effects of volatile organic compounds (VOCs) emitted from wooden boards made of Pinus densiflora and Chamaecyparis obtusa, conifer commonly found in korean forests. Boards made of those species were used to decorate interior of a test room. Different proportions of interior (20%, 40%, 60%, 80% and 100% against the entire interior of the room) were decorated. Electroencephalogram and VOCs in the test room were measured 24 hours after interior decorated. As the results, when 40% of interior of the room decorated with both species of boards, the largest amount of alpha wave was detected. For board made of P. densiflora, as the proportion of interior decorated increased both natural VOCs(NVOCs) and anthropogenic VOCs(AVOCs) were increased. on the other hand, When interior decorated with board made of C, obtusa, little differences in VOCs with different area of interior decorated was detected. Board made of P. densiflor emitted a slightly higher amount of AVOCs than boards made of C. obtusa. NVOCs emitted from board made of P. densiflora was three to fifteen times more than NVOCs emitted from board made of C. obtusa.

• 한국환경보건학회지
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• 제36권4호
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• pp.288-293
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• 2010

In this study, exposure to secondhand smoke (SHS) was evaluated in commercial personal computer (PC) rooms with different separation types of non-smoking areas. The particulate matter less than 2.5 ${\mu}m$ ($PM_{2.5}$) level was simultaneously measured by aerosol spectrometers in the non-smoking and smoking areas of these commercial PC rooms. Average $PM_{2.5}$ concentrations in non-smoking and smoking areas were $75\;{\mu}g/m^3$ and $136\;{\mu}g/m^3$, respectively. Although the $PM_{2.5}$ concentrations in non-smoking areas were significantly less than those in smoking areas (p<0.01), the levels still exceeded the US National Ambient Air Quality Standard of $35\;{\mu}g/m^3$. Average $PM_{2.5}$ concentrations in non-smoking areas were not significantly different with regard to area separation type, with $73\;{\mu}g/m^3$ in the no-wall type, $83\;{\mu}g/m^3$ in the wall-type, and $39\;{\mu}g/m^3$ in the separated-floor-type areas (p>0.1). Separation of the non-smoking area thus did not eliminate SHS exposure in commercial PC rooms, regardless of the type of area separation. This study demonstrates that simple separation of non-smoking areas in commercial PC rooms does not protect users from SHS.

• 한국대기환경학회지
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• 제28권1호
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• pp.59-67
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• 2012

Platform screen doors (PSD) installed at 289 stations in Seoul metropolitan subway from November 2005 to December 2009, are expected to prevent death from a fall and improve air quality. In this study, we systematically surveyed changes in radon concentrations before and after PSD installation in Seoul metropolitan subway stations. By solid-state nuclear track detectors (SSNTD), the radon concentrations before and after the PSD installation were measured at 54 stations of 6 lines from 2 to 7 reported to have relatively high radon concentrations. Mean radon concentrations at platforms were decreased by approximately 56% from 121.7 Bq/$m^3$ to 54.0 Bq/$m^3$. Before PSD installation, mean radon concentrations were in the decreasing order for subway lines 7, 5, 6, 3, 4 and 2. On the other hand, after PSD installation the order was changed to 5, 6, 7, 3, 4 and 2. According to a radon map of Seoul metropolitan subway, the number of platforms where radon concentration over was 74 Bq/$m^3$ decreased from 38 to 12 after PSD installation.

• 한국화재소방학회논문지
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• 제28권6호
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• pp.108-113
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• 2014

유해물질처리를 효율적으로 개선하기 위해 슬라이딩아크방전(sliding arc plasma)과 corona dielectric barrier discharge(CDBD공정)의 복합공정을 이용하였다. 이장치는 OH 라디칼과 음이온을 생성하여 강력한 산화력으로 탈취 및 살균 효과를 가진다. 실험결과 SAP 반응기의 크기를 80 A를 50 A로 축소하여도 유해물질의 농도는 큰 변화가 없는 것으로 나타나 반응기의 규모를 최소화할 수 있을 것으로 판단된다. 그리고 CDBD 반응기에서 생성된 음이온과 오존은 유해물질과 반응한 후 음이온은 510,000 ppb에서 470 ppb, 오존은 98 ppb에서 22 ppb로 낮아짐을 확인하였다. 또한 플라즈마 발생장치의 안정성 및 내구성이 우수한 것으로 판단되었다. 따라서 본 연구를 통하여 향후 플라즈마복합공정을 이용하여 실내공기중에 존재하는 유해물질 제거를 효율적으로 할 수 있을 것으로 생각된다.

• 한국산업보건학회지
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• 제24권3호
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• pp.300-309
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• 2014

Objectives: The objective of this study is to evaluate microbial exposure hazards in the metal-working fluids(MWF) handling industry. Methods: Air quality parameters(airborne bacteria, fungi, endotoxin and oil mist) and bulk MWF in storage tanks were evaluated at 54 points at nine sites in South Korea. Results: The geometric means(GM) of culturable airborne bacteria, fungi, endotoxin and oil mist concentration were $133CFU/m^3$(n=376, range $7{\sim}6,510CFU/m^3$), $159CFU/m^3$(n=381, range $7{\sim}8,469CFU/m^3$), $8.06EU/m^3$(n=103, range $0.34{\sim}280.4EU/m^3$) and $0.20mg/m^3$(n=104, range $0.01{\sim}2.87mg/m^3$), respectively. The ratio of indoor to outdoor concentration was 2.7 for bacteria, 6.1 for endotoxin, and 4.8 for oil mist. Even though average airborne bacteria concentration did not exceed recommended exposure limits($1,000CFU/m^3$), MWF in the storage tanks was highly contaminated with bacteria(arithmetic mean $2.1{\times}10^6CFU/ml$) and exceeded recommended bacteria limits($10^5CFU/ml$). Conclusions: It is necessary for MWF handling workplaces to conduct periodical biohazard inspection of MWF storage tanks. Additionally, further research may be necessary to establish biological occupational exposure limits.

• 한국산업보건학회지
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• 제28권2호
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• pp.200-210
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• 2018

Objectives: The purpose of this study is to assess the exposure to ozone and total volatile organic compounds(TVOCs) generated during welding work at a shipyard and recommend respiratory protective equipment(RPE) adequate against these hazards. Method: Ozone was collected for about 30 minutes at two-minutes intervals using a direct reading instrument, specifically an ozone analyzer(Serinus 10, Ecotech, Australia). TVOCs were collected for about 30 minutes at three-minute intervals using a portable GC (Alpha 115, Synspec BV, the Netherlands), and were determined simultaneously by area sampling at the welding plume closest to the welder's breathing zone. The total measurements were 162 for ozone($CO_2$ welding 47, TIG 60, stick 55), and 136 for TVOCs($CO_2$ 65, TIG 50, stick 21). Based on these measurements, a literature survey was conducted to assess the adequacy of RPE. Results: Relative to Korean OEL, measurements above STEL 0.2 ppm were 23.4% for $CO_2$, 63.3% for TIG and 14.5% for stick welding. There were significant differences(p=<0.0001) among welding types. Compared with ACGIH peak exposure of 0.4 ppm for ozone, which is not applied in Korea, $CO_2$ welding exceeded it by 10.6%, TIG by 40.0% and stick by 7.3%. Although it was not feasible to compare them directly since there are no Korean OEL, TVOCs had very high levels similar to the concentrations before moving into a new apartment and about 10-20 times the indoor air quality recommendations for some individual measurements. Conclusions: As ozone removal RPE has been recommended in welding environments for a long time(Lunau, 1967), this fact was demonstrated based on the results of the on-site work environment measurements(ozone and TVOCs). In conclusion, for all welding at a shipyard, gas/vapor and particulate combination RPE are recommended. If this is not possible, it should at least be present for TIG welding.

• 한국가구학회지
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• 제26권2호
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• pp.122-129
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• 2015

In previous study, VOC emission characteristics of coating materials for wood finishing were conducted and results showed that eco-friendly products has about 15~46% lower TVOC emission than typical products. In this study, lower TVOC emitted coating materials were applied on pine and then changes of VOC emission characteristics from pine with treatments were determined. Non-treated pine emitted $604.7{\mu}g/m^2h$ of TVOC that contained 66% of NVOC ($399.7{\mu}g/m^2h$). However, $V_2$ finished pine showed no NVOC emission rather than AVOC emission that consisted of Toluene, Ethylbenzene, m,p-Xylene, o-Xylene, 1,2,4- Trimethylbenzene. All coating materials inhibited ${\alpha}$-Pinene emission which originally from pine, but waterborne stain ($W_1$ and $W_3$) showed lower disruption of that emission. Moreover, $W_3$/wood showed higher NVOC emission such as ${\alpha}$-Terpinol, Terpinen-4-ol which are known as antioxidant substrates. Based on results, VOC emission characteristic of pine was significantly affected by coating materials with negatively in terms of ${\alpha}$-Pinene emission or positively in terms of NVOC emission. Therefore, coating material is important factor for indoor air quality when it would apply on wood products. For the future study, VOC emission characteristic of coated wood will be conducted continuously.

• 대한영양사협회학술지
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• 제23권4호
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• pp.350-362
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• 2017

The study examined evaluated the sanitation management state of the high school foodservice operations, as measured by temperature, humidity and airborne bacteria concentration in functional areas and further identified their relationships. Data were collected from 26 high school foodservices in Gyeonggi Province. Statistical analyses were conducted with the SPSS program using descriptive analysis and spearman's correlation. The sanitation management performances in high school foodservice scored 86.85 out of 100 points and showed higher scores in the dimensions of preparation and storing management (17.85/20 points), operation management (17.78/20 points), and cooking utensil management (17.62/20 points), while the dimensions of cross contamination management as well as personal hygiene management needed action plans for prompt improvement. The airborne bacteria concentration was highest in the dining area (179.2 CFU/plate), and requiring action plans for improvement. The relative humidity in functional areas ranged from 66.5% in the receiving area to 74.4% (dish-washing area) and the temperature of the preparation area showed an average of $25.1^{\circ}C$ with the highest of $35.4^{\circ}C$ in the dish-washing area. In terms of the relationships among airborne bacteria, temperature, and humidity, the concentration of airborne bacteria was negatively correlated with and temperature in the dish-washing area (r= -0.693, P<0.05), and no other significances were shown in the other areas.

• 한국환경보건학회지
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• 제40권5호
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• pp.425-434
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• 2014

Objectives: The purpose of this study is to introduce the establishment process and results of the Seoul Metropolitan Government's road map on environmental health policy. Methods: The process consisted of expert group meetings, civic participation, research, and questionnaire survey for priority environmental health policy agenda items in Seoul. Results: The announced vision for the environmental health policy was "a healthy environment, safety in Seoul". This policy was established in order to define environment health policy initiatives for a period of five years with an aim to protect Seoul citizens' health from hazardous environmental factors. The resulting Seoul environmental health policy consisted of four areas and 16 key agenda items. The four areas were "Protection for children against hazardous materials", "Enhancement of health and safety of all", "Carcinogen-free and endocrine-disrupting chemical-free Seoul (reducing environmental exposure to hazardous materials), and "Establish the foundation of environmental health policy". Sixteen key agenda items include the enhancement of management of spaces for children, certification of environmental health status at schools, establishment of a unit responsible for the environmental health of children, strengthening environmental health management for susceptible populations (children, the aged, and the socioeconomically vulnerable), management of hazardous materials, physical hazardous factors (noise, radiation, etc.), indoor air quality, and the enhancement of monitoring, research, and regulation of environment health. Conclusion: The Seoul Metropolitan Government established an environmental health policy road map for a five-year period (2013-2017). To implement this environmental health policy, budget allocation, and detailed execution plans are required.