• 한국대기환경학회지
• /
• 제31권1호
• /
• pp.54-62
• /
• 2015

Small scale paint overspray booths are being operated nationwidely, for repair of passenger car body parts. paint aerosols are emitted from the paint overspray booth in operations. In paint overspray booth operations without ventilation system and air pollutants collection unit, it may land on nearby equipment. In this study a removal of sticky paint aerosol for application of the small-scale overspray paint booth. it's cause the surface of filter bag from generated sticky paint aerosol. To remove adhesion of paint aerosol the agglomerating agents are injected and mixed with sticky paint aerosols prior to reach the filter bag. The paint spray rate was set as $10{\pm}5g/min$ from air-atomized spray guns in the spray booth, injection rate of agglomerating was $10{\pm}5g/min$ in the mixing chamber. The filtration velocity including air pollutants varied from 0.2 m/min to 0.4 m/min. Bag cleaning air pressure was set as $5.0kg_f/min$ for detaching dust cake from surface of filter bag. Bag cleaning interval at the filtration velocity of 0.2 m/min was around 3 times longer than that of the 0.4 m/min. The residual pressure drop maintained highest value at the highest filtration velocity. Fractional efficiency of 99.952%~99.971% was possible to maintain for the particle size of 2.5 microns. Total collection efficiency at the filtration velocity of 0.2 m/min was 99.42%. During this study we could confirm high collection efficiency and long cleaning intervals for the test with filtration velocity of 0.2 m/min indicating an optimal value for the given dimensions of the test unit and test operating conditions.

• 한국산업보건학회지
• /
• 제24권3호
• /
• pp.310-320
• /
• 2014

Backgrounds: Endotoxin, which found in the outer membrane of the gram-negative bacteria cell wall, makes up almost all of the lipopolysaccharide(LPS). When people are exposed to endotoxin,it can result in diverse health effects such as an airway irritation and inflammation, fever, malaise, bronchitis, allergic asthma, toxic pneumonitis, hypersensitivity lung disease. Cases among the elderly, children or pregnant can occur more frequently than a healthy adult if they are repeatedly exposed to the existing endotoxin. Therefore, we investigated and assessed the environmental characteristics associated with the airborne endotoxin concentration level in six hospital lobbies. Method: Endotoxin from indoor air in six hospital lobbies was measured by an area sampling method and analyzed according to American Society for Testing and Materials International(ASTM international) E2144-01. Total suspended particulate(TSP), carbon dioxide($CO_2$), temperature and humidity were also measured by using direct reading measurements or airborne sampling equipment at the same time. Environmental characteristics were appropriately divided into two or three groups for a statistics analysis. One-way analysis variable(one-way ANOVA) was used to examine a difference of the endotoxin concentration, depending on the environmental characteristics. In addition, only variables with p-value(p<0.25) were eventually designed to the best model by using multiple regression analysis. Results: The correlation analysis result indicated that TSP(p=0.003) and $CO_2$(p<0.0001) levels were significantly associated with endotoxin concentration levels. In contrast, temperature(p<0.068) and humidity(p<0.365) were not associated with endotoxin concentration. Levels of endotoxin concentration were statistically different among the environmental characteristics of Service time(p=0.01), Establishment of hospital(p<0.001), Scale of hospital(p=0.01), Day average people using hospital(p=0.03), Cleaning time of lobby(p=0.05), Season(p<0.001), and Cleaning of ventilation system(p<0.001) according to ANOVA. Finally, the best model(Adjusted R-square=72%) that we designed through a multiple regression test included environmental characteristics related to Service time, Area of lobby, Season, Cleaning of ventilation system, and Temperature. Conclusions: According to this study, our result showed a normal level of endotoxin concentration in the hospital lobbies and found environmental management methods to reduce the level of endotoxin concentration to a minimum. Consequently, this study recognized to be requirement for the management of ventilation systems and an indoor temperature in order to reduce the level of endotoxin concentration in the hospital lobbies.

• 한국염색가공학회지
• /
• 제21권6호
• /
• pp.1-11
• /
• 2009

Super-hydrophobic surface, with a water contact angle greater than $150^{\circ}$, has a self cleaning effect termed 'lotus effect'. We introduced super-hydrophobicity onto aramid/rayon mixture fabric with dual-scale structure by assembling silica nano-sol. Mixture fabric was treated with silica nano-sol, fluoric polymer using various parameters such as particle size, concentration. Silica nano-sol size were measured using particle size analyzer. Morphological changes by particle size were observed using field emission scanning electron microscopy(FE-SEM), contact angle measurement equipment. The contact angle of water was about $134.0^{\circ}$, $137.0^{\circ}$, $143.0^{\circ}$, $139.5^{\circ}$ and $139.0^{\circ}$ for mixture fabric coated with 100.2nm, 313.7nm, 558.2nm, 628.5nm and 965.4nm silica nano-sol, compared with about $120.0^{\circ}$ for mixture fabric coated with fluoric polymer. When we mixed particle sizes of 100.2nm and 558.2nm by 7:3 volume ratio, the contact angle of water was about $146.2^{\circ}$. And we mixed particle sizes of 313.7nm and 558.2nm by 7:3 volume ratio, the contact angle of water was about $141.8^{\circ}$. Also we mixed particle sizes of 558.2nm and 965.4nm by 7:3 volume ratio, the best super-hydrophobicity was obtained. In this paper, we fabricated the water-repellent surfaces with various surface structures by using four types of silica nano-sol, and we found that the dual-scale structure was very important for the super-hydrophobicity.

• 한국표면공학회지
• /
• 제49권6호
• /
• pp.513-520
• /
• 2016

Many surface protection methods have been developed to apply to constructional steels which have been used under severe corrosive environments. One of these methods, hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other industrial fields etc.. Recently, the cost of zinc is getting higher and higher, thus, it is considered that improvement of hot dip galvanizing process to reduce the cost of production should be developed possibly. In this study, additives such as acid cleaning solution, $NH_4OH$, $Al(OH)_3$ and $H_2O_2$ were added to flux solution, and omission of water washing treatment after acid cleaning was investigated with some types of flux solutions added with some additives mentioned above. The decrement of pH by adding the acid cleaning solution could be controlled due to neutralization reaction with addition of $NH_4OH$. The flux solution added with both $NH_4OH$ and $Al(OH)_3$ exhibited nearly the same color and pH value as those of orignal flux solution with no added, and the sample dipped to the flux solution which was added with additives mentioned above indicated a relatively good corrosion resistance compared to other samples. However, the flux solution added with $NH_4OH$, $Al(OH)_3$ and $H_2O_2$ exhibited a different color, sediment and a bad corrosion resistance. Consequently, it is considered that omission of water washing treatment may be able to perform by adding optimum additives to the original flux solution.

• 한국안전학회지
• /
• 제24권4호
• /
• pp.47-52
• /
• 2009

이 연구는 Fluorouracil(5-FU)가 병원에서 암치료제로 쓰이는 세포독성약제의 한 종류이기 때문에 병원내부에 5-FU의 폭로 정도와 그 관리를 위한 가장 효율적인 세척약제를 조사하기 위한 것이다. 이러한 세포독성 약제실이나 종약학 병동에서 근무하는 실무자들은 세포독성약제로 오염된 표면에 빈번하게 접촉하게 되면 세포유전성이나 DNA손상에 대한 위험이 높게 된다. 따라서 이러한 약제의 세척제실험을 위하여 4가지 약제로서 시행한분해시험에서 0.5%(w/v) NaClO 용액만이 5-FU를 즉시 분해시켰으므로 이 용액은 오염표면의 잔유물을 분해시키는데 사용될 수 있다. 세포독성 약제실의 오염표면에서 확인된 농도범위는 2.0에서 $13.8{\mu}g/m^2$까지이고, 종약학 병동의 오염표면에서 측정한 농도범위는 5.39에서 $11.53{\mu}g/m^2$이었다. 5-FU와 같은 세포독성약제로부터 피부오염을 피하기 위하여 작업장의 노출허용기준과 같은 법적인 조치, 완벽한 표면세척제 및 보호구사용과 같은 엄격한 관리기준이 마련되어야 할 것이다.

• 한국노년학
• /
• 제30권4호
• /
• pp.1163-1177
• /
• 2010

본 연구는 전국 복지용구사업소의 시설현황을 우편설문 및 방문을 통해 조사하고, 한국형 복지용구사업소의 적정 시설기준 수립을 위한 동선구성 및 공간구성, 면적 등의 기초적인 기준을 제시한 횡단적 조사연구이다. 이에 국내외 문헌 고찰, 전문가 의견수렴 등의 연구결과를 더하여 다음과 같은 한국형 복지용구사업소의 적정 시설기준 수립을 위한 원칙을 설정하였다. 첫째, 사업소의 유형(세정소독 여부, 대여사용 복지용구 수거 여부)에 따라 공간을 선택적으로 구성 배치한다. 둘째, 공간을 배치할 때 건물 층수, 면적은 복지용구 및 방문자의 동선이 최대한 짧고, 단순하게 구성한다. 셋째, 공간면적은 사업자가 결정한 전시체험 규모와 침대, 휠체어 등 주요한 복지용구 크기 등을 기준으로 산출한다. 넷째, 도로변 쪽으로 출입문을 내어 전시효과를 내고, 전시·체험·상담을 동시에 진행할 수 있도록 개방형 구조로 계획한다. 다섯째, 창고 및 세정소독공간은 각 출입문 및 공간을 철저히 구분하도록 하고, 동선을 구분하여 교차오염을 예방한다. 여섯째, 전시·체험·상담실은 고객 및 차량진입이 용이하도록 1층에 배치하고, 1층이 아닌 경우 휠체어를 타고 이동할 수 있는 충분한 통로를 확보하고, 엘리베이터 이용이 가능하도록 계획한다. 일곱째, 사무공간은 이용자 정보관리 중 프라이버시 보호를 위해 공간을 분리한다. 위 전제를 통해 세정소독 직접수행형 사업소는 최대 165m², 중간 150m², 최소 140m²에 전시체험실, 상담실, 세정소독실, 창고(청결, 오염), 사무실, 주차공간을 갖추도록 하고, 세정소독 위탁형 사업소는 최대 134m², 중간 119m², 최소 109m²에 전시체험실, 상담실, 사무실, 주차공간을 갖추며 복지용구 반입수거를 할 경우 창고(청결, 오염)까지 갖추도록 제시되었다.

• Preventive Nutrition and Food Science
• /
• 제12권3호
• /
• pp.167-172
• /
• 2007

This study was conducted to determine the effect of hygienic processing (HP) on the reduction of microorganisms during manufacturing of saengshik with two vegetables (carrots and cabbage) and two grains (barely and glutinous rice) compared to general processing (GP). For GP, distilled water was used for washing raw materials and equipment. For HP, aqueous ozone (3 ppm) in combination with 1% citric acid and 70% alcohol were used for washing raw materials and the equipment, respectively. In carrots, after cutting, total aerobic bacteria (TAB), yeast and mold (YM) and coliforms were significantly increased to 5.19, 8.04 and 2.08 ($log_{10}$ CFU/g), respectively (p<0.05). Washing effectively reduced the increased microorganisms from cross contamination during cutting, but cross contamination increased with subsequent GP drying and milling procedures to 8.56, 8.27 and 3.71 ($log_{10}$ CFU/g) for TAB, YM and coliforms, respectively (p<0.05). On the other hand, HP washing of carrots with 3 ppm ozone in combination with 1% citric acid showed higher antimicrobial effect than GP washing, significantly decreasing the number of microorganisms (p<0.05). Further cross contamination did not occur through drying and milling due to cleaning the equipments with 70% alcohol prior to processing. After milling, the number of TAB, YM and coliforms were significantly decreased to 3.89, 4.47 and not detectable level ($log_{10}$ CFU/g), respectively (p<0.05). Similar results were observed in cabbage and grains. During storage for two months at different temperatures (22 or $4^{\circ}C$), there were no changes in numbers of spoilage microorganisms in the packaged saengsik after either processing. This suggests the importance of HP for the reduction of microorganisms during saengsik production, and demonstrates the effectiveness of disinfection at each processing stage in minimizing contamination levels to enhance microbial safety of saengshik products.

• 한국식품조리과학회지
• /
• 제23권3호통권99호
• /
• pp.302-313
• /
• 2007

The purpose of this study was to investigate the gap in perceived importance-performance between dietitians and parents regarding school foodservice sanitation practices, to establish a plan for improving the school foodservice monitoring that is conducted by parents. A survey was given using questionnaires and was distributed to 31 school foodservice dietitians and to parents who attended sanitation education in October 2006. All statistical analyses were conducted using the SAS package program(version 8.2 for Windows) for descriptive analysis, t-test, and importance-performance analysis(IPA). The results of the IPA showed the following areas as improvement priorities: (1) contracting with a reliable suppliers, (2) securing proper refrigerator and freezer capacity and checking temperatures, (3) adequate design and construction of foodservice facilities and equipment, and (4) ensuring trays and utensils are clean, dry, and stored in a way that prevents contamination. The results of the IPA illustrated that school foodservice dietitians performed well in 8 out of the 21 sanitation management items. The perceived importance by parents was higher than by dietitians for accurate record keeping and documentation of HACCP worksheets(p<0.01), appropriate cleaning plans and practices(p<0.05), garbage management of inner kitchens (p<0.05), and garbage management of external kitchens(p<0.05). On the other hands, the perceived importance by dietitians was higher than that of parents for contracting with a reliable suppliers(p<0.05) and adequate design and construction of foodservice facilities and equipment(p<0.01). According to the performance analysis there were significant differences between dietitians and parents in six out of the twenty-one items. For these six items, the evaluated degree of performance by parents was higher than that of dietitians. In conclusion, proper education programs should be planned and regularly performed for the student's patents who take part in school foodservice monitoring in order to improve on their monitoring.

• 한국재료학회지
• /
• 제15권8호
• /
• pp.536-542
• /
• 2005

Recently European Council(EU) published the RoHS(restriction of the use of certain hazardous substances in electrical and electronic equipment) which is prohibit the use of Pb, Hg, Cd, $Cr^{+6}$, PBB or PBDE in the electrical and electronic equipments. So EU member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain 6 hazardous substances. The one of the most important in electronics manufacturing process is soldering. Soldering process use the chemical substances which are applied in fluxing and cleaning processes and it can generate the malfunction of electronics caused by corrosion in the fields conditions. Therefore this study researched on the polarization and Tafel properties of Sn40Pb and Sn3.0Ag0.5Cu(SAC) solder based on the electrochemical theory. We prepared SnPb specimens which was aged in $150^{\circ}C,\;180^{\circ}C$ for 15 minutes ana Sn3.0Ag0.5Cu specimens that was aged in $180^{\circ}C,\;220^{\circ}C$ for 10 minutes. Experimental polarization curves were measured in distilled ionized water and $3.5 wt\%$, 1 mole NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrode, respectively. To observe the electrochemical reaction, polarization test was conducted from -250 mV to +250 mV. From the polarization curves that were composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density(Icorr). In these results, corrosion rate for two specimen were compared Sn3.0Ag0.5Cu with SnPb solders

• 한국산업융합학회 논문집
• /
• 제23권4_2호
• /
• pp.617-626
• /
• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.