• Title/Summary/Keyword: Disinfection

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A Study on Characterization of Formation and Reduction of THMs in Water Treatment Process (정수처리공정별 THMs 발생특성과 저감방안에 대한 연구)

  • Ka, Gil-Hyun;Bae, Min-Ho;Lee, Jun-Ho;Ahn, Chi-Hwa;Han, Ihn-Sup;Min, Byung-Dae
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.7
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    • pp.721-728
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    • 2008
  • DBPs(Disinfection By-Products) are most formed through the reactions between chlorine and NOM(Natural Organic Matter) in water treatment. In this study, occurrence of DBPs including THMs(Trihalomethanes) is evaluated. Also, influencing factors by the seasons and raw water quality were investigated for correlation among them and the characteristics of THMs formation by prechlorination process. This study investigated the operation condition for THMs removal depending on raw water quality. Water treatment plant from intake station to gauging well flows for about 10 hours in Y Water Supply Office. It is limited to control of THMs formation because of excessive reaction time between chlorine and THMs precursors in the intake station. Therefore, as multi-points prechlorination from intake station to gauging well, THMs formation was decreased in the water treatment, and it was willing to prevent overdosage of chlorine. The concentration of THMs was 0.021 mg/L in the summer, 0.015 mg/L in the winter, respectively. Also, THMs formation showed that 0.013 mg/L in the water of gauging well after prechlorination, 0.014 mg/L in the flocculation/sedimentation/filtration, 0.016 mg/L in the water after postchlorination, respectively. THMFP(Trihalomethane Formation Potential) removed 42.7% and 50% through the flocculation/sedimentation and filtration, respectively, and it is similar TOC removal efficiency. In this study, multi-points prechlorination from intake station to gauging well decreases in contact time and concencrations of NOM and chlorine. Also, it decreases in THMs and amount of chlorine uesd. In the result of multi-points prechlorination in the summer, the concentration of THMs was 0.013mg/L in the treated water. In view of these facts, THMs formation can be decreased approximately 50%.

Effects of Some Environmental Factors on Japanese Yew (Taxus cuspidata Sieb. et Zucc.) (몇 발근환경인자(發根環境因子)가 주목삽수(揷穗) 발근(發根)에 미치는 효과(効果))

  • Kim, Chang Ho;Nam, Jung Chil
    • Journal of Korean Society of Forest Science
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    • v.70 no.1
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    • pp.1-6
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    • 1985
  • The purpose of this experiment lies in finding the most appropriate cutting condition of Taxus cuspidata Sieb. et Zucc. which has been considered valuable tree species in gardening. Statistical analysis was focused on the comparison of the average ratios of rooting between greenhouses and fields, based on the observation rooted autogenis. To conduct this survey, hardwood cutting of Taxus cuspidata Sieb. et Zucc. were performed at both places of experiment above on April 20, 1982 with rooting results calculated on October 31, 1982. After formation of cuttings, it was soaked in IBA 200 ppm for 12 hours and than put in a bed. A summary of the result is presented as follows; 1) Cutting at the greenhouse showed higher average rate of rooting than at fields. Same tendency was found regardless of the differences in treatment. 2) It was clear that IBA-treatment contributed remarkably to causing higher average rooting rate. As an evidence, when twenty centimeter cuttings were inserted sandy media, IBA-treated area resulted in eighty six percent of average rooting rate, as compared with only twenty three percent in nontreatment case. In case of field cutting, IBA-treatment brought about fifty three percent of rooting in comparison with eleven percent nontreatment. 3) When sandy soil, loam and brown soil were separately used as cutting media, the highest rooting rate was found in case of sandy soil, without any difference between the two experimental places above. 4) As a result of the analysis to seek the impact of the length of cuttings on rooting, the range of length form fifteen to twenty centimeter was apparently most appropriate. It was also found that the rate of rooting declined beyond twenty five centimeter. 5) Two kinds of rooting pattern were observed. One was the case that callus cell lump was created on the lower cut side of cuttings. Importantly, root radical were formed inside the lump to influence the germination of root system. The other relates to the case that adventitious root which look like lateral roots appeared at the stem region. In abstract, first, sandy soil was effectively recommended in case of hardwood cutting in April. Second, the most appropriate length of cuttings ranged between fifteen and twenty centimeters. Third, high density IBA treatment was clearly effective. Forth, for proper environmental management, both pre-disinfection of sail by sterilizer and maintenance of high relative humidity were essentially required.

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Production of Organic Rice (Oryza sativa L.) using Organic Cultivation Manual (유기재배매뉴얼을 활용한 유기쌀 생산)

  • Cha, Kwang-Hong;Oh, Hwan-Jung;Seo, Dong-Jun;Song, Yong-Su;Ahn, Joon-Seob;An, Kyu-Nam;Jung, Woo-Jin
    • Korean Journal of Organic Agriculture
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    • v.22 no.1
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    • pp.97-113
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    • 2014
  • An actual proof experiment was carried out to establish the production of high quality organic rice at farm household in Gwangjin, Junnam, Korea 2011. Experimental plot was designed with conventional organic cultivation and manual organic cultivation in both Hopeongbyeo and Onnuri varities. Experimental field was consisted with suitable drainage loam soil, anryong series, and normal paddy field. Chemical characteristics of the soil were investigated from initial soil and soil after harvest in experimental sites. Seed disinfection was treated with hot water dipping method at $60^{\circ}C$ for 10 min. Rice transplanting was carried out at 17 June with 25 days seedling using machine transplanting. Golden apple snail was used to prevent weed growth as middle size (1.5~1.7 kg/10a) at one week after rice transplanting. Amount of applied fertilizer in experimental plot was supplied with organic fertilizer for the shortage after harvest of hairy vetch (1,100 kg/10a). Bordeaux mixture was used to control of sheath blight and neck blast disease in all experimental plot at 19 Aug. Application of chitin culture solution was treated in manual organic cultivation at 2 and 15 Aug. At late growth stage, incidence rate of neck blast was the highest level at Hopyeongbyeo in conventional organic cultivation. Incidence rate of sheath blight in both Hopyeongbyeo and Onnuri was higher in conventional organic cultivation than in manual organic cultivation. Incidence of rice leaf folder was the highest level at Onnuri in conventional organic cultivation. Yield index in manual organic cultivation was increased by 13% and 38% at Onnuri and Hopyeongbyeo, respectively, compared with conventional organic cultivation. Head rice percentage in both Hopyeongbyeo and Onnuri was slightly increased in manual organic cultivation. These results indicate that high quality production of rice organic cultivation could be depending on management of safe fertilization with nutrient content in soil.

The Effects of Catheter Revision and Mupirocin on Exit Site Infection/Peritonitis in CAPD Patients (복막 투석 환자에서 도관 관련 감염 및 복막염에 대한 Mupirocin과 도관 전환술(Catheter revision)의 효과)

  • Park, Jun-Beom;Kim, Jung-Mee;Choi, Jun-Hyuk;Jo, Kyu-Hyang;Jung, Hang-Jae;Kim, Yeung-Jin;Do, Jun-Yeung;Yoon, Kyung-Woo
    • Journal of Yeungnam Medical Science
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    • v.16 no.2
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    • pp.347-356
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    • 1999
  • Background: Exit site/tunnel infection causes considerable morbidity and technique failure in CAPD patients. We presently use a unique revision method for the treatment of refractory ESI/TI in CAPD patients and mupirocin prophylaxis for high risk patients. Materials and Methods: We reviewed 139 CAPD patients about the ESI/TI from October 1993 to February 1999 at Yeungnam University Hospital. At the beginning of the ESI. we usually started medications with rifampicin and ciprofloxacin and then changed the antibiotics according to the sensitivity test. If the ESI had persisted and there were TI symptoms (purulent discharge, abscess lesion around exit site). we performed catheter revision(external cuff shaving, disinfection around tunnel and new exit site on opposit direction) with a combination of proper antibiotics. We applied local mupirocin ointment at the exit site three times per week to the 34 patients who had the risk of ESI starting from October 1998. Results: The total follow-up was 2401 patient months(pt. mon). ESI occurred on 105 occasions in 36 out of 139 patients, and peritonitis occurred on 112 occasions in 67 out of 139 patients. The total number of incidences of ESI and peritonitis was 1 per 23.0 pt. mon and 1 per 2l.6 pt.mon. The most common organism responsible for ESI was Staphylococcus aureus (26 of 54 isolated cases, 48%), followed by the Methicillin resistant S. aureus(MRSA) (13 cases, 24%). Seven patients(5: MRSA. 2: Pseudomonas) had to be treated with a revision to control infection. Three patients experienced ESI relapse after revision. One of them improved with antibiotics, while another needed a second revision and the remaining required catheter removal due to persistent MRSA infection with re-insertion at the same time. But, there was no more ESI in these 3 patients who were received management to relapse (The mean duration: 14.0 months). The rates of ESI were significantly reduced after using mupirocin than before(1 per 12.7 vs 34.0 pt.mon, P<0.01). Conclusions: In summary, revision technique can be regarded as an effective method for refractory ESI/TI before catheter removal. Also local mupirocin ointment can play a significant role in the prevention of ESI.

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A Study on the Health Care Satisfaction and Attitude of Elementary School Students - by the presence or absence of nurse teacher - (초등학생의 보건관리 만족도와 태도에 관한 연구 - 양호교사 유무를 중심으로 -)

  • Park, Dong-Kwon;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.1 no.2
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    • pp.49-71
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    • 2000
  • The purpose of this study was to serve as a basis for school health care of better quality, by making a comparative analysis of the health care satisfaction and attitude of elementary school students in consideration of their general characteristics and the presence or absence of nurse teacher. The subjects in this study were 919 selected six graders in 16 elementary schools in the city of Tongduchun, Koyang and Euijungbu, Yangju-kun and Yeunchun-kun. A survey was conducted with questionnaire designed for measurement of health care satisfaction and attitude. As a result of analyzing the data collected from June 1 through 15, 2000, the conclusions were as follows. 1) As for the general characteristics of the students investigated, the subjects included 513 boys(55.8%) and 406 girls(44.2%). The schools where 390(42.4%) students attended were located in municipal area, and the schools where 529(57.6%) students attended were located in kun area. 608(66.2%) students had a nurse teacher at their schools, while 311(33.8%) students had no nurse teacher. 498(54.2%) had an experience to use the health room this year, but 421(45.8%) had no such an experience. Their mean school life satisfaction was scored $3.42{\pm}.71$, above the average. And their health condition was rated $3.81{\pm}.87$, which implied they tended to be in good health. 2) The mean satisfaction at the health room operation was scored $3.33{\pm}.71$, above the medium level. What they were most satisfied with($4.02{\pm}1.08$) was, among the health room facilities, that there were beds. But they expressed the least satisfaction($2.83{\pm}1.17$) at the location of health room. The presence or absence of nurse teacher made a significant difference to their satisfactionat health room operation, because the students in schools with nurse teacher showed greater satisfaction($3.42{\pm}.72$) than the others in schools with no nurse teacher did($3.15{\pm}.66$). 3) Concerning their attitude to use the health room in case of disease or accident occurrence, a lot of students in schools with a nurse teacher, who had ever suffered from indigestion, headache or traumatic injury, used the health room. In schools with no nurse teacher, there was a tendency to talk to their class teachers(p<.001). The recognition of the necessity for health counseling was generally on a medium level. The counselor whom they wanted to discuss health problem with was family or friend in the largest cases. Few students discussed with class teachers in case there was a nurse teacher in school. Instead, some of them discussed with friend, family or nurse teacher, and there was a significant difference between them(p<.001). 4) The mean satisfaction at health, sanitation and environmental management was rated $3.20{\pm}.90$, above the average. The classroom lighting gave them the best satisfaction with $3.67{\pm}1.07$, but the satisfaction at toilet cleanness and disinfection was not good with $2.83{\pm}1.19$. By the presence or absence of nurse teacher, those who had a nurse teacher expressed better satisfaction at water supply facilities including hot water than the others who had no nurse teacher did(p<.001). But no significant difference was observed in the other items. 5) The health education satisfaction was rated $3.19{\pm}.99$, which was on a medium level. By item, the mean satisfaction level was $3.36{\pm}1.19$ at nurse teacher's explanation about treatment, $3.13{\pm}1.15$ at the frequency of health education, and $3.08{\pm}1.16$ at the explanation on the cause of disease. By the presence or absence of nurse teacher, the students with nurse teacher showed significantly better satisfaction at every factor0(p<.001). 6) Regarding health education attitude, their recognition of the need for school health education was scored $3.89{\pm}.96$. Those who had a nurse teacher felt it more necessary($3.96{\pm}.92$), yet the others who had no nurse teacher felt its necessity a little less($3.74{\pm}1.01$). The most preferred thing for them to learn in health education was first aid, followed by sex education, obesity prevention, safety accident prevention in school and outdoors, smoking-related health, good use of leisure time, and environmental pollution cause in the order named. According to the presence or absence of nurse teacher, there was a significant difference in sex education(p<.01), but no significant disparities were found in the other factors. The most preferred person who would offer health education was a lecturer from the outside(45.8%) and nurse teacher(45.4%). Their preference for class teacher as a person in charge of health education was just 8.8%. But the presence or absence of nurse teacher didn't produce any differences to their preference for a person in charge of health education.

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Analysis of Microbiological Hazards to Determine S. aureus Contamination Levels at School Foodservice Operations in Gyeonggi Province (경기지역 학교급식에서의 S. aureus 오염도 파악을 위한 미생물 위해분석)

  • Kim, Eun-Jung;Choi, Jung-Hwa;Kwak, Tong-Kyung
    • Korean journal of food and cookery science
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    • v.25 no.3
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    • pp.365-378
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    • 2009
  • This study performed microbiological hazards analysis in raw food materials, cooking processes, kitchen staff, utensils, and the environment in order to obtain contamination levels of S. aureus in school foodservice operations. S. aureus was not detected in cooked foods offered by the foodservice operations; however, it was found in raw food materials prior to cooking. In the case of vegetables, S. aureus was detected in washed mung bean sprouts, parboiled mung bean sprouts, and bellflower roots both before and after disinfection, at levels of 2.2, 1.0, 1.0, and 1.0 log CFU/g, respectively. For processed foods, S. aureus was detected in one sample of packaged bean curd as well as in mung bean jelly cake at the level of 1.5 log CFU/g. For meat products, S. aureus was detected in beef brisket and chicken at levels of 2.3 and 1.3 log CFU/g, respectively. To determine microbiological hazard data for the hands and gloves of cooking personnel, the staff members were divided into two groups: a group presenting Enterobacteriaceae or coliforms, and another group presenting neither Enterobacteriaceae nor coliforms. The results showed that S. aureus was detected on the hands of staff in each group at levels of 2.0 and 2.1 log CFU/hand, respectively, and at 1.8 and 0.0 log CFU/hand on the gloves of staff in each group, respectively. Among kitchen utensils, as an environmental factor in school foodservice operations, S. aureus was detected on meat knives, mixing bowls, and dish cloths at levels exceeding 1.0 log CFU/hand.

A Study on Third-trimester Gravidas' Konwledge of Infant Care Activity (임신 말기 임신부의 영아 돌보기 지식에 관한 연구)

  • Lee, Su-Yeon
    • The Korean Nurse
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    • v.29 no.3
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    • pp.64-78
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    • 1990
  • The purpose of this study was to measure the degree of gravidas' knowledge of infant care activity, and to identify the factors influencing the difference of gravidas' knowledge. The subjects of this study consisted of 159 gravida visited 2 general hospitals, 2 OB/GY clinics and 2 midwives' clinics in J city for anenatal care. The data were collected from December 1 to 30, J.989. The instrument used for this study was true false type question which was developed by investigator through literature review. Data were analyzed by percentage, mean, t-test and ANOVA on significant difference with SPSS program. The results of this study were, summarized as follow: 1) The degree of gravidas' knowledge of infant care activity was 36.75, the degree of gravidas' know ledge of physical care activicy was 16.70, and the degree of gravidas' knowledge of psychosocial care activity was 20.00. 2) Among the physical care activity knowledge items, the diaper should be changed whenever it is soiled, $\lceil$shortly after feeding is over, bathing is bad$\rfloor$, $\lceil$gently patted or stroked on the back when bubbling$\rfloor$, $\lceil$10 minutes time in bathing is appropriate$\rfloor$, $\lceil$infant is crying whenever he is hungry per 3-4 hours$\rfloor$, and "room humidity controled 60 percent, more or less> were over a' percentage of 80 of right answer. Among the physical care, accivity knowledge items. $\lceil$a reason for burping was the air' he has swallowed will rise to the top of his stomach and be eructated$\rfloor$, $\lceil$burping is advisable after the feeding$\rfloor$, $\lceil$dressing of umbilical area is not necessary$\rfloor$, $\lceil$the thermometer should not be boiled for disinfection$\rfloor$, $\lceil$it is important chat the infant grasp the whole nipple within his mouth$\rfloor$, $\lceil$using alcohol sponge is bad whenever diaper is soiled", and $\lceil$when temperature is taken by the rectal method, infant legs shoud be grasped firmly_! were less than a percentage of 60 of right answer. 3) Among the psychosocial care activity knowledge items, $\lceil$it is nice, mother smile at bady frequently$\rfloor$, $\lceil$it is nice, mother praise a bady frequently$\rfloor$, $\lceil$it is nice, mother express bady's behavior$\rfloor$, $\lceil$talk frequently to the bady, the bady :should not be disturbed while feeding$\rfloor$, $\lceil$it is nice, mother see a baby face to face , $\lceil$it is nice, mother concentrate one's attention on her baby while playing$\rfloor$, $\lceil$it is nice, mother pat one's baby while he is feeding$\rfloor$, $\lceil$it is advisable, the baby is allowed to touch mother's breast while he is feeding$\rfloor$, $\lceil$it is advisable to stop feeding, if the baby protrudes one's tongue or cries while feeding$\rfloor$, $\lceil$baby is able to hear, see and smell$\rfloor$, $\lceil$it is nice, mother Concentrate one's attention on her baby while feeding$\rfloor$, and $\lceil$it is not advisable for mother to scold baby while he is crying out> were over a percentage of 80 of right answer. Among the psychosocial care activity knowledge items, $\lceil$Using' baby talks is bad when mother talks to baby> and $\lceil$it is nice, mother soothes the baby as soon as possible when he is crying I were less than a percentage of 60 of right answer. 4) There was statistically significant relationship between the degree of gravidas' knowledge of infant care activity and the demographic variables of gravida such as the age(p<0.01) and education level(p<0.01). From these results, it may be concluded that gravidas' knowledge of infant care activity is moderate level, and gravidas' knowledge of psychosocial care activity is greater than that of physical care activity. Also prenatal nursing educations should focus on subjects who have lower percentage of right answer in infant care activity knowledge items.dge items.

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Objectives and Contents of Basic Medical Sciences in Nursing Education (간호학 교육에서 기초의과학 교과목별 목표와 내용에 대한 연구)

  • 최명애;신기수
    • Journal of Korean Academy of Nursing
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    • v.29 no.6
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    • pp.1455-1468
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    • 1999
  • The purpose of this study was to investigate the objectives and contents of basic medical sciences at department of nursing in college of nursing, and junior college of nursing, thus ultimately providing the basic data to standardize the curriculum of the basic medical sciences in nursing education. Seventy eight professors who were in charge of teaching basic medical sciences to at 22 colleges of nursing/ department of nursing, and 20 junior colleges of nursing responded to the questionnaires that consisted of the questions regarding objectives and contents, of basic medical sciences. Based on the description of objectives, the description related to nursing, nurse, nursing science was cathegorized as on objective applicable to nursing science, the description related to medicine or clinical medicine as medical model, the description without description related to medicine was cathegorized as knowledge acquisition. The number of schools corresponding to each category were summerized in descending order. The objectives of basic medical sciences were categorized by concepts and number of schools corresponding to the categorized concept. The findings of the study are as follows ; 1. The subjects of basic medical science identified were physiology, anatomy, biochemistry, pathology, microbiology, and pharmacology in most colleges of nursing and junior colleges. Two colleges of nursing/department of nursing (9.1%) and 19 junior colleges of nursing(95%) did not offer biochemistry, 1 college of nursing /department of nursing(5%) did not offer pathology & pharmacology. 2 junior colleges of nursing (10%) did not offer pharmacology, 1 junior college of nursing(5%) did not offer pathology. The other 1 junior college of nursing did not offer microbiology. 2. Objectives of physiology were to acquire knowledge and understanding on human function in both 6 (50%) colleges and 5 junior colleges. Objectives of anatomy were to acquire knowledge on human structure in both 4 (57%) colleges and 2 (50%) junior colleges; knowledge applicable to nursing sciences in both 3 (42.8%) colleges and 2 (50%) junior colleges. Objectives of biochemistry was to obtain knowledge and understanding on biochemistry, and understanding of basic concepts about biochemistry. Objectives of pathology were to obtain knowledge and understanding on pathology in both 4 (57.1%) colleges and 5(62.5%) junior colleges. Objectives of microbiology were to acquire knowledge and understanding on microbiology in both 5(83.8%) colleges and 6(85.7%) junior colleges. Objectives of pharmacology were to acquire knowledge on pharmacology in both 7(100%) colleges and 8(100%) junior colleges. 3. Contents of physiology in 19 (100%) schools were membrane transport, digestion, circulation, nervous system and respiration. In 16(84.2%) were kidney and muscle, that in 13(68.4%) were endocrine physiology. In 11(57.9%) were introduction and that in 9(47.4%) were structure and function of cells. Contents of anatomy in 11(100%) schools were skeletal system, muscle system, digestive system, circulatory system, concepts regarding human structure. In 10(90.9%) schools were endocrine system and nervous system, and in 5(45.5%) schools were blood, urinary system and cell. Contents of biochemistry in 6(100%) schools were history of biochemistry, body regulating factor, bioenergy, health and nutrition, nutrition of cell, energy production system. In 5(83.3%) schools were metabolism of protein and carbohydrate and enzyme, and in 3(50%) schools were metabolism of energy and fat. Contents of microbiology in 13(100%) schools were environment and influenc of bacteria, virus, G(-) rods, purulent cocci, G(+) rods. In 10 (76.9%) were immunity, diphtheria, enterobacteria, and in 9(69.2%) were spirochete, rickettsia and clamydia, and that in 6(46.2%) were sterilization and disinfection. Contents of pathology in 14(100%) schools were cell injury and adaptation, inflammation, respiratory diseases, circulatory diseases. In 10(71.4%) were neurological disorders, in 8(57.1%) were immunity and disease, and in 7 (50%) were tumor and progressive changes. Contents of pharmacology in 15(100%) were cardivascular drugs, introduction to pharmacology, hypnotics, analgesics, local anesthetics, an ticonvulsants. In 12(80%) were drugs activity on sympathetic and parasympathetic nervous system, and in 11(73%) were sulfa drugs, antibiotics, drug abuse and addiction.

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A Study on the Lime Stabilization of Livestock Waste (축산폐기물의 안정화 처리에 대한 연구)

  • Kim, Hyun-Chul;Choi, Yong-Su
    • Analytical Science and Technology
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    • v.8 no.1
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    • pp.91-99
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    • 1995
  • One of alternative conventional technologies used for treatment of livestock wastes is composting process, and recently some mechanical composting processes are being practiced. It is, however, recognized the composting process also has its own limitations such as longer time requirement, and difficulties to estimate the degree of decomposition, etc. The incomplete compost contains potentially harmful materials to crops and public health due to instabilized organic contents and pathogenic organisms. The purpose of this investigation is to develop an innovative system whereby anxious livestock wastes are thoroughly stabilized and disinfected. Thus the overall management scheme should meet the following requirements. 1. A system should be in a cost-effective and environmentally sound manner. 2. Sludges must be chemically stabilized and bacteriologically safe. 3. Odor-free by product should be applied to crop land. 4. Sludges are sources of fertilizer nutrients and/or soil amendments to enhance crop production. 5. And they can be used as potential pH adjusting agent of the acidified soils. Overall effectiveness of the developed system is experimentally tested to satisfy the preset criteria and requirements. Major experiments are divided into four categories: they are 1. chemical stability test, 2. optimal condition test of stabilization process, 3. bacteriological examination and disinfection tests, and 4. deodorization tests The stabilization process is consisted of the stabilizing reaction process and the drying process. Stabilized wastes is dried by both sun dryer and rotary dryer. It is shown that an additive dosage of about g/kg solid in wastes with a minimum of 5-minutes reaction would be necessary for effective stabilization reaction. The stabilization process is consisted of the stabilizing reaction process and drying process. Stabilized wastes are dried by both sun dryer and rotary dryer. It is shown that an additive dosage of about 300g/kg solid in wastes with a minimum of 5-minutes reaction would be necessary for effective stabilization reaction. In the stabilization reaction process, the pH of wastes is lowered from initial values of 12.3 to 8.6. High pH prevents odor production and kills pathogenic organisms. Organic matter contents in the stabilized wastes are about 50% and the sum of contents of fertilizer elements such as total nitrogen, $P_2O_5$ and $K_2O$ are about 5.3%. The livestock wastes that are stabilized chemically and hygienically can be used as a good soil conditioner and/or organic fertilizer.

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Microbial Risk Assessment in Treated Wastewater Irrigation on Paddy Rice Plot (하수처리수를 관개한 후 벼재배 시험구에 대한 미생물 위해성 평가)

  • Jung, Kwang-Wook;An, Youn-Joo;Jang, Jae-Ho;Jeon, Ji-Hong;Yoon, Chun-Gyeong
    • Korean Journal of Ecology and Environment
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    • v.38 no.2 s.112
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    • pp.225-236
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    • 2005
  • The protection of public health In wastewater reclamation and reuse is one of the most important issues. Monitoring data of Escherichia coli were collected from paddy rice plots in 2003 and 2004 experiments. Five treatments were used and each one was triplicated to evaluate the changes of E. coli: surface water, biofilter effluent (secondary level), UV-disinfected water and pond treatment. Microbial risk was quantified to assess human health risk by exposure to E. coli in paddy rice plots, which were irrigated with reclaimed wastewater. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion that may occur to farmer and neighbor children. Monte-Carlo analysis (10,000 trials) was used to estimate the risk characterization of uncertainty. In the following analysis, two scenarios were related to the reduction of risk against direct ingestion and exposure times. Scenarios A and B were assumed that the risk was 1,000 and 10,000 times lower than direct ingestion.'Golfers were assumed to be 0.001 L of reclaimed water by contact with balls and their cloths. Opportunity of contact in paddy rice field with pathogens was more frequent than handing golf balls, because of agricultural activity was practiced in ponded water in paddy rice culture. As a result of microbial risk assessment using total data of experimental period, risk value of E. coli in 2003 and 2004 experiment ranged from $10^{-5}$ to $10^{-8}$ and $10^{-4}$ to $10^{-8}$, respectively. The risk values in biofilter effluent irrigation was the highest, which is $10^{-4}$ in 2003 and $10^{-5}$ in 2004 experiments with scenario A. Ranges of $10^{-6}$ to $10^{-8}$ were considered at reasonable levels of risk for communicable disease transmission from environmental exposure and the risk value above $10^{-4}$ was considered to be attributable to the risk of infection. Irrigation with UV-disinfected water in the paddy field during the agricultural Period showed significantly lower microbial risk than others, and their levels of risk value were within the range of actual paddy rice field with surface water.