• 공업화학
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• 제5권6호
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• pp.1036-1043
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• 1994

폴리에칠렌을 가교시키는 방법으로서 silane에 의한 가교를 행하였다. Silane 가교는 압출기를 이용하여 $200{\sim}210^{\circ}C$ 용융온도에서 반응압출시켜 vinyltrimethoxysilane(VTMOS)를 PE 주쇄에 그라프트시킨 후, 3가지 silane 가교조건($80^{\circ}C$ 온수가교, $80^{\circ}C$ air oven 가교, 상온대기방치 가교)으로써 물 또는 수분에 노출시켜 가교를 완성하였다. Silane 가교된 폴리에칠렌의 결정 용융온도(Tm)의 변화, 밀도의 변화, 가교의 속도 거동을 측정하여 수지의 silane 가교조건에 따른 열적특성 변화를 연구하였다. Silane 가교는 용융상태의 고온에서 가교시키는 과산화물 가교와는 달리 고체상태에서 가교가 일어나기 때문에 그 가교조건에 따라 결정용융온도, 결정도 및 결정성장, 가교속도, 밀도의 변화가 다르고 수지의 종류도 열적특성에 영향을 미침을 알았다. 상온대기방치 가교된 silane 가교 linear low density polyehylene(LLDPE)은 결정이 성장되면서 서서히 가교반응이 진행됨에 따라 DSC에서 2차 용융 피크가 생성되지 않았으며, 재결정화하면 결합된 가교 site의 결정화 방해현상에 의해 결정용융온도가 낮아지는 거동을 나타내었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.124-124
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• 2017

Cadmium (Cd) is of particular concern because of its widespread occurrence and high toxicity and may cause serious morpho-physiological and molecular abnormalities in in plants. The present study was performed to explore Cd-induced morpho-physiological alterations and their potentiality associated mechanisms in Sorghum bicolor leaves at the protein level. Ten-day-old sorghum seedlings were exposed to different concentrations (0, 100, and $150{\mu}M$) of $CdCl_2$, and different morpho-physiological responses were recorded. The effects of Cd exposure on protein expression patterns in S. bicolor were investigated using two-dimensional gel electrophoresis (2-DE) in samples derived from the leaves of both control and Cd-treated seedlings. The observed morphological changes revealed that the plants treated with Cd displayed dramatically altered shoot lengths, fresh weights, and relative water content. In addition, the concentration of Cd was markedly increased by treatment with Cd, and the amount of Cd taken up by the shoots was significantly and directly correlated with the applied level of Cd. Using the 2-DE method, a total of 33 differentially expressed protein spots were analyzed using MALDI-TOF/TOF MS. Of these, treatment with Cd resulted in significant increases in 15 proteins and decreases in 18 proteins. Significant changes were absorbed in the levels of proteins known to be involved in carbohydrate metabolism, transcriptional regulation, translation and stress responses. Proteomic results revealed that Cd stress had an inhibitory effect on carbon fixation, ATP production and the regulation of protein synthesis. In addition, the up-regulation of glutathione S-transferase and cytochrome P450 may play a significant role in Cd-related toxicity and stress responses. Our study provides insights into the integrated molecular mechanisms involved in response to Cd and the effects of Cd on the growth and physiological characteristics of sorghum seedlings. The upregulation of these stress-related genes may be candidates for further research and use in genetic manipulation of sorghum tolerance to Cd stress.

• 공업화학
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• 제19권6호
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• pp.674-679
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• 2008

수처리에 있어서 분말 $TiO_2$ 광촉매가 안고 있는 문제점을 극복하기 위하여 스테인리스 강 섬유를 지지체로 한 $TiO_2$ 담지 광촉매($TiO_2/SSF$)를 제조하였다. 초음파 세척기를 이용하여 담지된 $TiO_2$의 부착강도를 살펴보았으며, 메틸렌블루와 포름산 분해실험을 통하여 광촉매 활성을 평가하였고, 대장균과 비브리오균에 대한 살균실험을 통하여 살균능력을 평가하였다. 담지된 $TiO_2$는 30 min간의 초음파 처리 후에도 95% 이상이 남아 있을 정도로 강한 부착력을 보였으며, UV 하에서 60%의 메틸렌블루와 38%의 포름산을 1 h 만에 각각 분해시키는 광촉매 활성을 보였고, 대장균과 비브리오균에 대하여 99.9% 이상의 높은 살균능력을 보였다. 포름산 분해의 경우에는 산화제를 첨가하면 분해율이 증가하였으며, 특히 과산화수소를 첨가할 경우에는 분해율이 1 h 만에 80%로 증가하였다.

• 공업화학
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• 제29권2호
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• pp.225-228
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• 2018

열가소성고분자에 첨가되는 가소제는 외부로의 용출로 인해 제품의 수명을 단축시키고, 일부는 환경, 인체에 유해한 영향을 미치는 것으로 알려져 있다. 발암물질로 의심되는 프탈레이트계 가소제의 사용이 점차 금지됨에 따라 이를 대체할 수 있는 친환경 가소제에 대한 필요성이 요구되며 대부분의 물질은 수지와의 상용성이 다소 떨어지거나 단가가 높으며 구체적인 안전성 검증이 부족한 문제가 있다. 따라서, 본 연구에서는 대체 가소제 후보물질로서 우수한 물리적 물성과 독성 평가에서 안전한 화합물로 보고되어진 노보넨 다이알킬에스터 화합물 4종을 PVC 수지에 첨가하여 용출에 의한 인체 노출 가능성을 평가하고 상용가소제 DEHP, DINCH, DOTP와 비교 분석하여 대체 물질로서의 가능성을 평가하고자 하였다. 시험은 american standard test method (ASTM) 규격에 준하여 시행하였으며 결과에 따르면, 수성 용매에서 di-2-ethylhexyl-5-norbornene-2,3-dicarboxylate (DEHN), 유성용매에서 diisopentyl-5-norbornene-2,3-dicarboxylate (DIPN) 화합물이 DEHP 대비 우수하거나 동등한 수치를 나타내었다. 또한 4종의 노보넨 화합물 모두 환경에 영향을 미칠 수 있는 수준으로 평가되는 100 ppm보다 낮은 수치를 나타내었으며 이는 극성부인 노보넨 구조가 용출성에 영향을 미친 것으로 보여진다.

• 공업화학
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• 제29권4호
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• pp.413-418
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• 2018

붕산, 5붕산암모늄, 붕산/5붕산암모늄 첨가제로 처리한 편백목재 시험편의 연소가스 발생에 관한 시험을 하였다. 4 wt%의 붕소 화합물 수용액으로 각각 편백목재 시험편에 붓으로 3회 칠하였다. 실온에서 건조시킨 후, 콘칼로리미터(ISO 5660-1)를 이용하여 연소가스를 분석하였다. 그 결과, 붕소 화합물로 처리한 시험편의 두 번째_최대산소 소모율은 0.1067~0.1246 g/s로서 공시험편보다 5.3~18.9% 감소했다. 붕산, 5붕산암모늄으로 처리한 시험편의 비소화면적은 2.0~19.0% 감소하였다. 그러나, 붕산/5붕산암모늄으로 처리된 경우 비감쇠면적이 공시험편보다 21.2% 증가하였다. 붕소 화합물로 처리한 시험편의 최대일산화탄소 농도는 0~25% 감소되었다. 이것은 직업안전위생관리국(Occupational Safety and Health Administration, OSHA) 허용기준의 1.6~2.2배의 치명적인 독성을 발생하는 것으로 측정되었다. 붕소화합물은 일산화탄소 감소에는 효과적이었으나 OSHA의 허용기준에는 미치지 못하였다. 붕소화합물은 편백나무의 연소성을 두 번째_최대산소 소모율에 대하여 5.3~18.9%, 최대일산화탄소 발생에 대하여 0~25% 억제하였다.

• 공업화학
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• 제30권6호
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• pp.731-736
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• 2019

본 연구에서는 Pt/TiO₂를 파우더 및 허니컴 형태로 제조하고, 촉매의 피독 물질인 SO₂에 대한 영향과 재생 방안을 연구하였다. 이에 따라 Pt/TiO₂의 SO₂ 노출 전·후 촉매 활성을 비교하였다. Pt/TiO₂의 초기 활성은 주입되는 H₂ 농도(1~5%)에 비례하며, 촉매의 온도와 H₂ 전환율이 각각 최대 183 ℃와 95%로 나타났다. 2,800 ppm SO₂를 파우더 및 허니컴 Pt/TiO₂에 노출시켰고, 이때 성능이 나타나지 않았고 촉매 표면에 0.69%의 황(S)이 잔류함을 확인하였다. 피독 촉매에 대한 세척 및 열처리 결과, 파우더 촉매는 세척에 의해 96% 이상의 H₂ 전환율을 나타냈고 허니컴 촉매는 H₂ 또는 air 분위기의 열처리를 통해 촉매 활성이 재생되어 95% 이상의 H₂ 전환율이 확인되었다.

• 한국산업보건학회지
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• 제16권1호
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• pp.36-43
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• 2006

The principal aim of this field study was to determine the concentrations and emissions of gaseous contaminants such as ammonia and hydrogen sulfide in the different types of pig buildings in Korea and allow objective comparison between Korea and the other countries in terms of pig housing types. This field study was performed from May to June and from September to October in 2002. Pig buildings investigated in this research were selected in terms of three criteria; manure removal system, ventilation mode and growth stage of pig. Measurements of concentration and emission of ammonia and hydrogen sulfide in the pig buildings were done in 5 housing types and the visited farms were 15 sites per each housing type. Concentrations of ammonia and hydrogen sulfide were measured at three locations of the central alley in the pig building and emission rates of them were estimated by multiplying the average concentration($mg/m^3$) measured near the air outlet by the mean ventilation rate($m^3/h$) and expressed either per pig of liveweight 75kg(mg/h/pig) or per area($mg/h/m^2$). Concentrations of ammonia and hydrogen sulfide in the pig buildings were averaged to 7.5 ppm and 286.5 ppb and ranged from 0.8 to 21.4 ppm and from 45.8 to 1,235 ppb, respectively. The highest concentrations of ammonia and hydrogen sulfide were found in the mechanically ventilated buildings with slats; 12.1 ppm and 612.8 ppb, while the lowest concentrations of ammonia and hydrogen sulfide were found in the pig buildings with deep-litter bed system(2.2 ppm) and the naturally ventilated pig buildings with manure removal system by scraper(115.2 ppb), respectively(p<0.05). All the pig buildings were investigated not to exceed the threshold limit values(TLVs) of ammonia(25 ppm) and hydrogen sulfide(10 ppm). The mean emissions of ammonia and hydrogen sulfide per pig(75kg in terms of liveweight) and area($m^2$) from pig buildings were 250.2 mg/h/pig and 37.8 mg/h/pig and $336.3mg/h/m^2$ and $50.9mg/h/m^2$, respectively. The pig buildings with deep-litter bed system showed the lowest emissions of ammonia and hydrogen sulfide(p<0.05). However, the emissions of ammonia and hydrogen sulfide from the other pig buildings were not significantly different(p>0.05). Concentrations and emissions of ammonia and hydrogen sulfide were relatively higher in the pig buildings managed with deep-pit manure system with slats and mechanical ventilation mode than the different pig housing types. In order to prevent pig farm workers from adverse health effect caused by exposure to ammonia and hydrogen sulfide in pig buildings, they should wear the respirators during shift and be educated sustainably for the guideline related to occupational safety.

• 한국산업보건학회지
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• 제1권2호
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• pp.181-191
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• 1991

The present study determined the overall noise level and the distribution of sound pressure level over audible frequency range of noise produced at various work sites. Work-related noise greater than 80dBA produced from 98 separate work sites at 37 manufacturing companies and machine shops were analysed for the overall sound level (dBA) and frequency distribution. In addition, to determine the possible hearing loss related to work site noise, a hearing test was also conducted on 1,374 workers in these work sites. The results of the study were as follows ; 1. Of the total 98 work sites, 57 work sites(58.2%) produced noise exceeding threshold limit value (${\geq}90dBA$) set by the Ministry 01 Labor. In terms of different manufacturing industries the proportion of work sites which exceeded 90dBA was the highest for the cut-stone products industry with 6/6 work sites and lowest for the commercial printing industry with 1/13 work sites. 2. The percentage of workers who were exposed to noise greater than 90dBA was 19.8% (1,040 workers) 01 the total 5,261 workers. In terms of different industries, cut-stone products industry had the most workers exposed to noise exceeding 90dBA with 82.8%, textile bleaching and dyeing industry was next at 30.6% followed by fabricated metal products industry with 27.9%, plastic products manufacturing industry had the lowest percentage of workers exposed to 90dBA exceeding noise with 4.5%. 3. There was a statistically significant correlation between the frequency of noise-induced hearing loss and the percentage of workers exposed to noise exceeding 90dBA (P<0.05). 4. The frequency analysis of noise produced at the 98 work sites revealed that 44 work sites (44.9%) had the maximum sound pressure level at high-frequencies greater than 2KHz. In addition, significantly higher sound pressure level was detected at the high-frequencies at 90dBA exceeding work sites as compared to below 90dBA work sites (P<0.01). 5. The differences in sound level meter's A-and C-weighted sound pressure levels were analysed by frequencies. Of the 28 work sites which showed 0-1 dB difference in the two weighted sound levels, 20 work sites (71.4%) had significantly higher sound pressure levels at high-frequencies greater than 2KHz (P<0.01). Furthermore, there was a tendency for higher sound pressure levels to occur in the high-frequency range as the differences in the two weighted sound levels decreased.

• 한국산업보건학회지
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• 제8권1호
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• pp.115-123
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• 1998

Vinyl chloride monomer exists as gas phase at normal temperature and reacts with oxygen and strong oxidant in the air to form oxidized materials. Because of being easily synthesized, it is used as a main source at the synthetic reaction process of PVC synthesis factories. Ministry of Labor regulates its usage as a carcinogen and its exposure level as 1 ppm. But the amount of VCM production in PVC and VCM production process hasn't been exactly estimated. In addition, facilities of this factory are located in outdoor. Therefore, this study was designed to investigate effects of temperature on breakthrough of charcoal tube at a fixed concentration and temperature during VCM sampling based on NIOSH and OSHA methods which were used as methods of occupational environment measuring and analysis. During the sampling of VCM, methods of OSHA and NIOSH require flow rate of 0.05 lpm and sampling volume of $3{\ell}$, $5{\ell}$ respectively, at this time carbon molecular sieve tube and coconut shell charcoal tube are used to observe the breakthrough along with concentration and temperature. As a result, significant difference between average adsorbed amounts of OSHA methods but that of NIOSH methods cannot be found. NIOSH method is likely to be effected by high temperature and normal temperature in high concentration. Breakthrough is not found in the method of OSHA at different conditions of temperature and concentration. As the result of this study we could verify that breakthrough occurred in the process of sampling VCM with NIOSH methods. Therefor in summer time, breakthrough should be considered and research on the breakthrough volume should be done. It is considered the research about the specificity of the coconut shell charcoal and carbon molecular sieve sorbent should be done when sampling VCM in comming days.

• 한국산업보건학회지
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• 제8권1호
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• pp.76-87
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• 1998

The concentration of welding fume was measured by 221 welders themselves in chassis frame workplace of the manufactory from February, 1, 1996 to May, 31, 1997. Welding parameters were the welding current and the distance between helmet and arc. Those two optimum conditions were proposed by excess probability analysis using logistic regression, so the best position in the workplace was proposed considering two factors to control the welding fume. The results are as followings; 1) The excess proability of welding fume TLV was over 99% in above 260 Amperes of welding current and also in below 30cm of distanced between helmet and arc. 2) The equation from logistic regression analysis using SPSS/PC+5.02 had the welding current as a independent variable and the excess of welding fume TLV as a dependent variable (p<0.05). Logit(welding fume TLV) = 0.1296 ${\times}$ wlding currnet - 28.8750 3) The equation from logistic regression analysis using SPSS/PC+5.02 had the distance between helmet and arc as a independent variable and the excess of welding fume threshold limit value a, a dependent variable (p<0.05). Logit (welding fume TLV) = -0.6809 ${\times}$ distance between helmet and arc +25.1665 4) Considering both cases or 2) and 3). the result equation is following. (p<0.05). Logit (welding fume TLV) = 0.1346 ${\times}$ welding current -0.3859 ${\times}$ distance between helmet and arc -15.7382 5) The excess probability of welding fume threshold limit value was 100% in above 240 Ampere of welding current. Thus, below 220 Ampere can be suggested to reduce the 40% number of welders who have a excess welding fume threshold limit value. 6) The excess probability of welding fume TLV was 100% in below 34cm of distance between helmet and arc. Thus, over 38cm can be suggested to reduce the 33% number of welders who have a excess welding fume TLV. 7) Considering both 5) and 6) cases, first of all, the best welding current can be 200 Ampere to have a below 15% of welding fume excess probability for the welders who works in distance of 34-37cm. Secondly, to have a below 30% excess probability of welding fume TLV, the working distance must be over 38cm in 220 Ampere and 32cm in 200 Ampere. 8) To reduce the average exposure concentration of welding fume ($8.21{\pm}5.83mg/m^3$), the movable local exhaust system equipped with flexible hoods can be used.