• 설비공학논문집
• /
• 제29권10호
• /
• pp.530-537
• /
• 2017

Scales generated inside pipes cause negative effects on heat transfer performance, pressure loss and flow rate due to increased thermal resistance and reduced flow cross-sectional area. If these scales are not prevented or eliminated, thermal-fluid performance of the facilities can be deteriorated, or in extreme cases, accidents such as explosion due to overheating can occur. There are two ways to remove the scales, physically and chemically. Removing the scales physically needs specific machines which are expensive, and removing them chemically may provoke corrosion or shorten the age of the facilities. In this study, an eco-friendly pipe scale cleaner using natural organic acid is developed by applying the concept of a limestone cave generation. The manufactured scale cleaner is applied to remove the scales in industrial, water heating and urinal pipes. The results show that this cleaner removes scales more effectively and safely compared to existing scale treatments. Scale removal efficiencies of this work is 1.2~10.7 times for industrial pipes and 1.8~15.5 times for boiler water heating pipes higher than those of conventional cleaners.

• 한국환경과학회지
• /
• 제16권7호
• /
• pp.785-791
• /
• 2007

The current study evaluated the technical feasibility of the application of titanium dioxide ($TiO_{2}$) photo-catalytic air cleaners for the disinfection of bioaerosols present in indoor air. The evaluation included both laboratory and field tests and the tests of hydraulic diameter (HD) and lamp type (LT). Disinfection efficiency of photocatalytic oxidation (PCO) technique was estimated by survival ratio of bacteria or fungi calculated from the number of viable cells which form colonies on the nutrient agar plates. It was suggested that the reactor coating with $TiO_{2}$ did not enhance the adsorption of bioaerosols, and that the UV irradiation has certain extent of disinfection efficiency. The disinfection efficiency increased as HD decreased, most likely due to the decrease in the light intensity since the distance of the catalyst from the light source increased when increasing the HD. It was further suggested that the mass transfer effects were not as important as the light intensity effects on the PCO disinfection efficiency of bioaerosols. Germicidal lamp was superior to the black lamp for the disinfection of airborne bacteria and fungi, which is supported by the finding that the disinfection efficiencies were higher when the germicidal lamp was used compared to the black lamp in the laboratory test. These findings, combined with operational attributes such as a low pressure drop across the reactor and ambient temperature operation, can make the PCO reactor a possible tool in the effort to improve indoor bioaerosol levels.

• 대한한방소아과학회지
• /
• 제24권2호
• /
• pp.112-125
• /
• 2010

Objectives The purpose of this study is to find the relationships between the allergy and weakness in children in Seong-Dong district. Methods 802 day care centers children were participated for survey on allergic disease, risk factors, and weakness. From the result, we analyzed the relationships between the aforementioned factors. Results 1. 802 children were participated for the survey. We eliminated survey answers with unclear answers, and selected 792 survey sheets as our final subject of study. The age of majority of subjects(720 children) were between one to six years old, and the others were under the age of one and over seven. 2. The prevalence rate of asthma in a lifetime was 6.69%, allergic rhinitis was 14.87%, atopic dermatitis was 28.82%, allergic conjunctivitis was 6.29%, food allergies was 9.58%, and drug allergies was 1.4%. In 2009, the prevalence rate of allergies during treatments is 6.69% for asthma, 13.41% for allergic rhinitis, 13.64% for atopic dermatitis, 4.13% for allergic conjunctivitis, 5.23% for food allergies, 0.96% for drug allergies. 3. The significant risk factors were types of dwelling, pet with fur, dirty environments without vacuum cleaners, the numbers of times bed covers were washed, frequency of air ventilation, changes in body after moving, family history. 4. The distribution of the number of children with weakness within the five visceras were respiratory weakness, digestive weakness, psychoneurologic weakness, neuromotor weakness, and urogenital weakness in the order of most to the least. More specifically, children who only has respiratory weakness were the majority, while children who have respiratory and digestive weaknesses, children who have respiratory, digestive, and psychoneurologic weaknesses, children who have respiratory and psychoneurologic were followed. 5. With the exception of children with urogenital weakness, Most of the children with respiratory weakness, digestive weakness, psychoneurologic weakness, and neuromotor weakness had been treated for allergies in 2009, while children who were diagnosed with allergic diseases at least once in their lifetime most likely had weak respiratory, digestive or psychoneurologic systems. Conclusions The results of this study showed that there was a correlation between children with weak viscera and children with allergic diseases. However, further research would be necessary.

• Parasites, Hosts and Diseases
• /
• 제35권1호
• /
• pp.9-17
• /
• 1997

1993-1994년에 걸쳐 전국 10개 지역내 주택에서 수거한 집먼지내의 진드기류를 조사하였다. 집 먼지는 평소 가정주부가 사용하는 전기진공청소기내 횔터에 모아진 집먼지 중 10 g을 채취하여 wet sieving metrod 일부 보완하여 진드기류를 분리하였다 채집된 총 7,257개체의 진드기를 동정한 결과 4아목 18과 23속 23종을 확인하였는데 그 중 Rhyzoglyphus robini, Sancossania phwllophcgianus, Cheyletus trouessarti 및 Scheloribotes lotipes의 4종은 국내 미기록 종이었다 전국적으로 가장 널리 분포되어 있고 서식밀도가 높은 종은 nemntophago릴os Jnrinae(DF)로 전체의 65.3%였고 D. Pteronvssinus(DP)가 20.6% Twrophnsus putrescentiqe(TP)가 6.5%를 차지하였는데, 이들 3종이 함께 서식하는 가정은 62개 조사대상 중 24.6%였고. 2개종이 공존하는 가정은 48 1%. 한종만 서식하는 가정은 27.3%였다. DF가 우점 종인 가정은 59개 조사 가정 중 63.5% DP가 우점종인 가정은 29.6%였고 TP가 우점종인 가정은 6.9%였다. 지역적으로는 서울. 광주 인천 전주 정주 등지에서는 DF가 우세하였으나 영광 춘천. 부산 영도 등 대기습도가 비교적 높은(> 73% RH) 지역에서는 DP가 우세한 것으로 나타났다. 집먼지진드기의 서식밀도를 보면 집먼지 10g 중 1.000개체 이상인 가정이 2.9%. 500-999 개체의 가정이 4.3%. 100-499개체의 가정이 15.7%였고 99개체 이하의 밀도를 보인 가정이 70.0%를 차지하였으며 전혀 채집되지 않은 가정은 7.1%였다. 아파트와 단독주택. 건물면적 청소횟수. 가족수. 건축년수 등과 집먼지진드기 서식밀도간에는 상관관계를 보이지 않았다.