• 제목/요약/키워드: Critical Strain

검색결과 848건 처리시간 0.026초

Facial Paralysis and Myositis Following the H3N2 Influenza Vaccine in a Dog

  • Ju-Hyun An;Ye-In Oh;So-Hee Kim;Su-Min Park;Jeong-Hwa Lee;Ga-Hyun Lim;Kyung-Won Seo;Hwa-Young Youn
    • 한국임상수의학회지
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    • 제40권5호
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    • pp.336-340
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    • 2023
  • A dog (2-year old, female, Shih-Tzu) presented with hyperthermia and right-sided facial paralysis characterized by the inability to close the right eye and drooling from the right side of the mouth after H3N2 influenza vaccination [A/Canine/Korea/01/07(H3N2) strain; Caniflu-Max, Bionote, Hwaseong, Gyeonggi-do, ROK]. To determine the cause of the fever and neurological symptoms, physical examination, ophthalmic examination, thoracic and abdominal radiography, abdominal ultrasonography, complete blood counts, serum chemistry values, and electrolyte levels were determined. In addition, Cerebrospinal fluid analysis, antinuclear antibody test, fever of unknown origin polymerase chain reaction (PCR) panel, tick-borne pathogen PCR panel were performed. As a result, hyperthermia, leukocytosis, and elevated C-reactive protein were confirmed. In addition, neurological examination revealed decreased right eyelid reflexes, corneal reflexes, threat response, and facial sensation, it was possible to suspect problems with the trigeminal and facial nerves of the cranial nerve. Magnetic resonance imaging revealed a lesion suggestive of myositis in the right muscular lesion at atlanto-occipital junction level on site of vaccine injection. Therefore, right-sided facial paralysis was tentatively determined to be a secondary cause of nerve damage caused by myositis. The patient was treated with immunosuppressants such as prednisolone and mycophenolate mofetil. After 3 months of immunosuppressant therapy, the patient's symptoms improved.

Beak Trimming Methods - Review -

  • Glatz, P.C.
    • Asian-Australasian Journal of Animal Sciences
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    • 제13권11호
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    • pp.1619-1637
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    • 2000
  • A review was undertaken to obtain information on the range of beak-trimming methods available or under development. Beak-trimming of commercial layer replacement pullets is a common yet critical management tool that can affect the performance for the life of the flock. The most obvious advantage of beak-trimming is a reduction in cannibalism although the extent of the reduction in cannibalism depends on the strain, season, and type of housing, flock health and other factors. Beak-trimming also improves feed conversion by reducing food wastage. A further advantage of beak-trimming is a reduction in the chronic stress associated with dominance interactions in the flock. Beak-trimming of birds at 7-10 days is favoured by Industry but research over last 10 years has shown that beak-trimming at day-old causes the least stress on birds and efforts are needed to encourage Industry to adopt the practice of beak-trimming birds at day-old. Proper beak-trimming can result in greatly improved layer performance but improper beak-trimming can ruin an other wise good flock of hens. Re-trimming is practiced in most flocks, although there are some flocks that only need one trimming. Given the continuing welfare scrutiny of using a hot blade to cut the beak, attempts have been made to develop more welfare friendly methods of beak-trimming. Despite the developments in design of hot blade beak-trimmers the process has remained largely unchanged. That is, a red-hot blade cuts and cauterises the beak. The variables in the process are blade temperature, cauterisation time, operator ability, severity of trimming, age of trimming, strain of bird and beak length. This method of beak-trimming is still overwhelmingly favoured in Industry and there appears to be no other alternative procedures that are more effective. Sharp secateurs have been used trim the upper beak of both layers and turkeys. Bleeding from the upper mandible ceases shortly after the operation, and despite the regrowth of the beak a reduction of cannibalism has been reported. Very few differences have been noted between behaviour and production of the hot blade and cold blade cut chickens. This method has not been used on a large scale in Industry. There are anecdotal reports of cannibalism outbreaks in birds with regrown beaks. A robotic beak-trimming machine was developed in France, which permitted simultaneous, automated beak-trimming and vaccination of day-old chicks of up to 4,500 chickens per hour. Use of the machine was not successful because if the chicks were not loaded correctly they could drop off the line, receive excessive beak-trimming or very light trimming. Robotic beak-trimming was not effective if there was a variation in the weight or size of chickens. Capsaicin can cause degeneration of sensory nerves in mammals and decreases the rate of beak regrowth by its action on the sensory nerves. Capsaicin is a cheap, non-toxic substance that can be readily applied at the time of less severe beak-trimming. It suffers the disadvantage of causing an extreme burning sensation in operators who come in contact with the substance during its application to the bird. Methods of applying the substance to minimise the risk to operators of coming in contact with capsaicin need to be explored. A method was reported which cuts the beaks with a laser beam in day-old chickens. No details were provided on the type of laser used, or the severity of beak-trimming, but by 16 weeks the beaks of laser trimmed birds resembled the untrimmed beaks, but without the bill tip. Feather pecking and cannibalism during the laying period were highest among the laser trimmed hens. Currently laser machines are available that are transportable and research to investigate the effectiveness of beak-trimming using ablasive and coagulative lasers used in human medicine should be explored. Liquid nitrogen was used to declaw emu toes but was not effective. There was regrowth of the claws and the time and cost involved in the procedure limit the potential of using this process to beak-trim birds.

한국에 있어서의 벼흰빛잎마름병의 발생생태와 방제에 관한 연구 (Studies on the Epidemiology and Control of Bacterial Leaf Blight of Rice in Korea)

  • 이경휘
    • 한국응용곤충학회지
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    • 제14권3호
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    • pp.111-131
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    • 1975
  • 한국에 있어서 벼 흰빛잎마름병의 방제 대책을 강구하기 위하여 피해, 병원균의 성질, 발병환경, 품종의 저항성, Bacteriophage에 의한 발생예찰 및 약제방제에 관하여 1965년부터 1975년까지 얻은 시험 결과를 요약하면 다음과 같다. 1. 피해 우리나라에 있어서 흰빛잎마름병은 거이 전국적으로 분포하여 피해를 주고 있으며 매년 발생이 증가하는 경향이다. 본병발생면적과 이병성품종인 진흥 및 전남풍의 재배면적 증가 사이에는 $5\%$ 수준의 유의성이 있었다. 지역별 피해상황은 남해안지대인 전남, 경남을 비롯하여 서해안지대에서 심하며 또 지대 별로 보면 저위 침수지역이 심하다. 피해 해석 결과 출수기의 병반 면적율과 수량과는 고도의 부(일)의 상관이 있었으며 병반면적율이 $20\%$ 이하에서는 수량에 미치는 영향이 적었으나 $60\%$이상되면 약 $50\%$ 내외의 감수를 초래하였다. 2. 병원균 공시한 10균주 모두 glucose, galactose를 분해하였고 lactose, dextrin, starch는 분해하지 못하였으며 saccharose, raffinose, manitol, manitol, esculin, salicin등의 탄소원에 대하여는 균주 간에 다소 차이가 있었다. 또 균주에 따라 gelatin 액화 정도에 차이가 있었다. 전국 72개 지역에서 채집 분리한 106균주를 4가지 Bacteriophage의 용균 반응에 따라 분류한 결과 1965년의 2계통에서 1971년에서 9계통으로 점차 다양화되었다. 또 진흥에서는 주로 A, B, C, I등이 분리되었고 김남풍에서는 A, B, H, I가 분리되었으며 통일에서는 D, E를 제외한 거의 모든 계통이 분리된 반면 E계통은 아끼바레에서만 분리되었다. 3. 발생환경 7-8월 중에 평년보다 기온이 낫고 습도가 높으며 강우량이 많고 일조시수가 적을 때 발병이 많았다. 출수기를 전후하여 태풍과 침수는 본병을 유발 및 만연시키는 가장 큰 원인이 되었고 이앙기가 빠를수록 발병이 많았다. 4. 저항성 검정 흰빛잎마름병에 대한 저항성 검정방법 가운데서 가위 접종법이 발병 진전이 빠르고 가장 효율적이었다. 우리나라 주요 장려 품종 중에서는 저항성 품종은 없었고 백금, 농림 6호가 중도 저항성이었다. 5. 발생예찰 전년에 발병했던 논에 설치한 못자리에서 병원균이 검출되었고, 관계수중의 Bacteriophage의 발생량과 병발생과는 높은 상관이 있었다. 관계수 1cc당 50개 내외의 Phage가 검출되면 초발을 예견할 수 있었고 Phage의 발생소장 곡선과 15일후의 발병 곡선이 거의 일치됨에 따라 관개수중의 Phage. 발생소장을 조사함으로서 2주일 앞서 발생예찰이 가능하였다. 6. 약제방제 발병 초기부터 1주간격으로 3회 약제 살포하였을 때 훼나진, 상케루 수화제 살포구는 발병율이 떨어졌으며 수량도 $20\%$ 정도 증수되었다. Bacteriophage 발생소장을 이용해서 약제방제할 때에는 Phage가 50개 내외 정도 나타날 때 살포하는 것이 가장 효과적이다.

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전처리 나물류 및 구근류에서 병원성 미생물의 성장예측모델 개발 및 검증 (Development and Validation of Predictive Model for Foodborne Pathogens in Preprocessed Namuls and Wild Root Vegetables)

  • 엔크자갈 라왁사르나이;민경진;윤기선
    • 한국식품영양과학회지
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    • 제42권10호
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    • pp.1690-1700
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    • 2013
  • 본 연구에서 사용한 전처리 나물류 중 고사리 경우 $13^{\circ}C$에서 B. cereus 영양세포 및 포자가, $8^{\circ}C$에서 S. aureus는 성장하지 않았다. 전처리 나물류 및 구근류에서 B. cereus 영양세포 및 포자의 성장특성을 비교한 결과, 도라지와 취나물에서 LT, SGR 및 MPD는 B. cereus 영양세포와 포자사이에 유의적인 차이를 보이지 않았다. 반면 우엉은 $13^{\circ}C$에 저장한 경우 B. cereus 영양세포와 포자의 유도기는 유의적인 차이를 보였으며 고사리의 경우, 17, 24, $35^{\circ}C$ 온도에서 B. cereus 포자의 유도기는 영양세포의 유도기 값보다 2배 연장된 것으로 유의적인 차이를 나타내었다(P<0.05). $24^{\circ}C$$35^{\circ}C$의 상온에서는 모든 나물류 및 구근류에서 B. cereus 포자 유도기는 영양세포의 유도기보다 연장되었고, SGR 값은 포자가 빠른 것으로 나타났다. 한편, $13^{\circ}C$$17^{\circ}C$에서는 B. cereus 영양세포와 포자의 유도기가 고온에 비하여 연장되어 B. cereus 영양세포와 포자의 성장을 억제하기 위해서는 $13^{\circ}C$ 이하의 온도 관리가 중요하다. 또한 B. cereus와 S. aureus 영양세포의 성장특성 비교 결과, $13^{\circ}C$ 이하에서는 B. cereus 성장이 관찰되지 않았으나 S. aureus는 $8^{\circ}C$에서도 성장하였다. 전반적으로 $13^{\circ}C$에서 모든 나물류 및 구근류는 B. cereus의 유도기가 S. aureus 의 유도기보다 3배 이상 연장되었다. 전처리 나물류 및 구근류에서 개발된 설사형 B. cereus 영양세포 및 포자 성장예측모델을 구토형 B. cereus 영양세포 및 포자의 실험값으로 검증한 결과, 도라지와 고사리의 LT 모델과 고사리의 SGR 모델을 제외한 모든 모델에서 Bf 값이 허용범위(0.07~1.15)에 속하여 설사형 B. cereus 영양세포, 포자 성장모델이 구토형 B. cereus 영양세포, 포자의 성장을 예측하는데 적합한 것으로 나타났다. 또한 전처리 나물류 및 구근류에서 $8{\sim}35^{\circ}C$ 사이에 개발된 S. aureus의 성장예측 모델을 실험에 사용하지 않은 온도(18, $30^{\circ}C$)로 적합성을 검증한 결과, 도라지의 SGR 모델을 제외한 모든 모델에서 Bf와 Af 값이 가장 이상적인 1에 가까운 값으로 나타나 실험값과 예측값 사이의 일치성을 보였다. 본 연구 결과 개발된 전처리 나물류 및 구근류의 성장예측 모델은 병원성 미생물의 증식을 억제하는 기준과 규격 설정 시 활용 가능할 것이며, 전처리 나물류의 HACCP 공정의 CCP(critical control point) 및 CL(critical limit)을 설정하는데 유용한 자료로 활용될 수 있을 것으로 사료된다.

인문지리학 방법론의 새로운 지평 (New horizon of geographical method)

  • 최병두
    • 대한지리학회지
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    • 제38권
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    • pp.15-36
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    • 1988
  • In this paper, I consider the development of methods in contemporary human geography in terms of a dialectical relation of action and structure, and try to draw a new horizon of method toward which geographical research and spatial theory would develop. The positivist geography which was dominent during 1960s has been faced both with serious internal reflections and strong external criticisms in the 1970s. The internal reflections that pointed out its ignorance of spatial behavior of decision-makers and its simplication of complex spatial relations have developed behavioural geography and systems-theoretical approach. Yet this kinds of alternatives have still standed on the positivist, geography, even though they have seemed to be more real and complicate than the previous one, The external criticisms that have argued against the positivist method as phenomenalism and instrumentalism suggest some alternatives: humanistic geography which emphasizes intention and action of human subject and meaning-understanding, and structuralist geography which stresses on social structure as a totality which would produce spatial phenomena, and a theoretical formulation. Human geography today can be characterized by a strain and conflict between these methods, and hence rezuires a synthetic integration between them. Philosophy and social theory in general are in the same in which theories of action and structural analysis have been complementary or conflict with each other. Human geography has fallen into a further problematic with the introduction of a method based on so-called political ecnomy. This method has been suggested not merely as analternative to the positivist geography, but also as a theoretical foundation for critical analysis of space. The political economy of space with has analyzed the capitalist space and tried to theorize its transformation may be seen either as following humanistic(or Hegelian) Marxism, such as represented in Lefebvre's work, or as following structuralist Marxism, such as developed in Castelles's or Harvey's work. The spatial theory following humanistic Marxism has argued for a dialectic relation between 'the spatial' and 'the social', and given more attention to practicing human agents than to explaining social structures. on the contray, that based on structuralist Marxism has argued for social structures producing spatial phenomena, and focused on theorising the totality of structures, Even though these two perspectives tend more recently to be convergent in a way that structuralist-Marxist. geographers relate the domain of economic and political structures with that of action in their studies of urban culture and experience under capitalism, the political ecnomy of space needs an integrated method with which one can overcome difficulties of orthhodox Marxism. Some novel works in philosophy and social theory have been developed since the end of 1970s which have oriented towards an integrated method relating a series of concepts of action and structure, and reconstructing historical materialism. They include Giddens's theory of structuration, foucault's geneological analysis of power-knowledge, and Habermas's theory of communicative action. Ther are, of course, some fundamental differences between these works. Giddens develops a theory which relates explicitly the domain of action and that of structure in terms of what he calls the 'duality of structure', and wants to bring time-space relations into the core of social theory. Foucault writes a history in which strategically intentional but nonsubjective power relations have emerged and operated by virtue of multiple forms of constrainst wihthin specific spaces, while refusing to elaborate any theory which would underlie a political rationalization. Habermas analyzes how the Western rationalization of ecnomic and political systems has colonized the lifeworld in which we communicate each other, and wants to formulate a new normative foundation for critical theory of society which highlights communicatie reason (without any consideration of spatial concepts). On the basis of the above consideration, this paper draws a new norizon of method in human geography and spatial theory, some essential ideas of which can be summarized as follows: (1) the concept of space especially in terms of its relation to sociery. Space is not an ontological entity whch is independent of society and has its own laws of constitution and transformation, but it can be produced and reproduced only by virtue of its relation to society. Yet space is not merlely a material product of society, but also a place and medium in and through which socety can be maintained or transformed.(2) the constitution of space in terms of the relation between action and structure. Spatial actors who are always knowledgeable under conditions of socio-spatial structure produce and reproduce their context of action, that is, structure; and spatial structures as results of human action enable as well as constrain it. Spatial actions can be distinguished between instrumental-strategicaction oriented to success and communicative action oriented to understanding, which (re)produce respectively two different spheres of spatial structure in different ways: the material structure of economic and political systems-space in an unknowledged and unitended way, and the symbolic structure of social and cultural life-space in an acknowledged and intended way. (3) the capitalist space in terms of its rationalization. The ideal development of space would balance the rationalizations of system space and life-space in a way that system space providers material conditions for the maintainance of the life-space, and the life-space for its further development. But the development of capitalist space in reality is paradoxical and hence crisis-ridden. The economic and poltical system-space, propelled with the steering media like money, and power, has outstriped the significance of communicative action, and colonized the life-space. That is, we no longer live in a space mediated communicative action, but one created for and by money and power. But no matter how seriously our everyday life-space has been monetalrized and bureaucratised, here lies nevertheless the practical potential which would rehabilitate the meaning of space, the meaning of our life on the Earth.

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삼축압축 하에서 지중연속벽 주변 방콕 연약 점토의 거동 (Behaviors of Soft Bangkok Clay behind Diaphragm Wall Under Unloading Compression Triaxial Test)

  • Le, Nghia Trong;Teparaksa, Wanchai;Mitachi, Toshiyuki;Kawaguchi, Takayuki
    • 한국지반공학회논문집
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    • 제23권9호
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    • pp.5-16
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    • 2007
  • 비배수 상태에서의 변수 $S_u,\;E_u$, n의 함수로 표현되는 단순한 선형 완전점탄성 모델은 굴착 중에 연성 토양에 시공되는 지중연속벽의 변위를 예측하는데 사용된다. 그러나 유한요소해석에서의 이러한 모델은 굴착이 잠시 중단되었거나 완료된 후 지중연속벽의 측방향 변위를 연속적으로 예측하는 데 한계가 있다. 굴착이 이루어지지 않는 동안의 지중연속벽 주변 토양의 변형 거동특성을 연구하기 위하여, 지중연속벽 주변 토양에 작용하는 응력상태를 가정한 '방콕 연약 점토'에 대한 일련의 삼축압축시험이 모사되었다. 본 연구에서는 세 가지 다른 조건에서의 삼축압축시험이 실시되었는바, 압밀 비배수 조건에서의 재하($CK_0UC$), 압밀 배수 및 비배수 조건에서의 재하 및 제하($CK_0DUC$$CK_0UUC$)의 조건에서 시험이 실시되었다. 시험으로부터 일련의 $CK_0DUC$ 시험에서 얻은 전단강도는 $CK_0UC$ 시험에서의 잔류강도와 같음을 알 수 있었다. $CK_0DUC$ 시험에서 시험편에 가해지는 수평압력을 점진적으로 감소시키면서 측정한 탄성계수는 편차응력의 증가와 더불어 감소함을 알 수 있었다. 또한 $CK_0UC$$CK_0DUC$시험에서 한계상태 관계의 기울기가 동일하게 나타났다. 더욱이, $CK_0DUC$시험에서 수평압력을 점진적으로 감소시킬 경우의, 축방향 및 반경방향 변형율 증가율을 시간, 한계상태 관계의 기울기, 편차응력과 평균 유호응력의 비의 함수로 표현할 수 있었다. 이 연구는 삼축압축시험의 제하 과정에서 얻은 시험 결과가 굴착 중 지중연속벽의 변형을 예측하는데 사용될 수 있음을 보였다.AFM)과 Scanning Electron Microscopy(SEM)을 통해 관찰한 GST 다층박막시료의 고온 열처리 전후 표면미시거칠기 변화도 PRAM 기록기를 사용할 때에는 in-situ 타원계를 사용할 때보다 1/10 정도의 크기를 보여주어 PRAM 기록기와 분광타원계를 사용하여 결정한 GST의 고온광학물성의 신뢰성을 확인하여 주었다.>, 여자 $179.1{\pm}37.2%$이었다. 평균필요량에 비해 가장 낮은 양을 섭취한 영양소는 엽산으로서 남자 $60.1{\pm}10.8%$, 여자 $54.6{\pm}9.9%$로 조사되었다. 칼슘의 섭취량은 평균필요량에 비해 전체 $74.9{\pm}31.9%$로 나타났다. 에너지 섭취량에 있어서 남자 노인들은 모두가 필요추정량의 75% 미만을 섭취하고 있었고 여자 노인의 경우에도 97%가 필요추정량의 75% 미만을 섭취하여 에너지 섭취량이 매우 낮았다 반면에 단백질 섭취량에 있어서는 남자 노인의 경우 100%가 평균필요량의 125%를 초과하였고, 여자 노인의 경우에는 91%가 평균필요량의 125%를 초과하여 대조적이었다. 비타민 A와 E는 각각 평균필요량과 충분섭취량의 125%를 초과하는 비율이 높게 나타난 반면에 비타민 $B_2$는 특히 남자 노인에서 평균필요량의 75%미만을 섭취한 비율이 높게 나타났다. 엽산 섭취량에 있어서는 평균필요량의 75% 미만을 섭취한 비율이 전체 96%로 나타나 심각한 부족상태로 조사되었다 반면에 철의 섭취량은 남녀 모두 100%가 평균필요량의 125%를 초과하여 섭취한 것으로 나타났다. 아연의 섭취량은 남자 17%,여자 15%가 평균필요량의 75% 미만을 섭취한 것으로 조사되었다. 에너지와 엽산은 모든 노인들에서 평균필요량에 미달되게 섭취한

종이 첨가제가 종이의 노화에 미치는 영향 (Effect of Additives on Paper Aging)

  • 윤병호;이명구;최경화
    • 임산에너지
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    • 제21권2호
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    • pp.25-33
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    • 2002
  • 도서관이나 문서보관소에서 책이나 서류를 보존하는데 있어 중요한 문제점 중의 하나는 종이의 열화이다. 그러므로 이러한 문제를 해결하기 위해서는 종이의 열화의 주요 원인을 규명할 필요가 있다. 몇몇의 학자들이 이에 대한 연구를 수행한 결과 종이 열화의 주요 원인으로서 종이 섬유내 셀룰로오스의 산 촉매 가수분해로 밝혀졌다. 일반적으로 종이제조시 첨가되는 첨가제로 인해 산성지의 노화율이 중성지의 노화율에 비해 더 높다. 따라서 종이내 존재하는 산을 제거해 줄 필요가 있다. 종이의 탈산화 처리는 열화속도를 감소시켜 산성지의 수명을 3, 4배정도 늘릴 수 있다고 한다. 최근에는 기존의 탈산화 처리방법과는달리 대량의 책과 서류의 탈산화를 위한 효과적인 탈산화 방법의 필요성이 인식되어져 왔다. 따라서 본 논문에서는 종이 제조시 사용되는 첨가제가 노화에 미치는 영향을 알아보고,효과적인 종이의 노화 방지를 위해 산성지에 가스상 에탄올아민류(모노에탄올아민, 디에탄올아민, 트리에탄올아민)를 사용하여 탈산처리를 시도하여 보았다. 첨가제가 종이의 노화에미치는 영향을 실험한 결과, 종이의 노화율이 알럼+로진>알럼>AKD> 무처리 순으로 나타났다. 또한 가스상 에탄올아민류 탈산처리 실험결과, 탈산처리율이 모노에탄올아민>디에탄올아민>트리에탄올아민 순으로 나타났다. 그러나 처리 후 종이에 약간의 백색도와 내절도의 감소가 나타났다. 이러한 문제를 해결하기 위해 가스상 에탄올아민류들을 조합 처리하여 탈산처리를 시도해 본 결과, 백색도와 내절도의 감소없이 효과적인 탈산처리 효과를 얻을 수 있었다.ird limit" is characterized by the production of reduction of $H_2O$$_2$, which is reduced by wall effect. Strain rate substantially affects ignition temperature because key reaction rates of $H_2O$$_2$ are comparably with its transport rate, while the mixture temperature and the hydrogen composition do not significantly affect ignition temperature.e.성 면역 결핍증 환자가 직업을 가지면 안된다는 사람보다 된다는 사람이(P<0.001), 각각 지식이 높았다. 결론 : 지식이 높을수록 성병에 걸릴 가능성이 낮고, 태도에서도 긍정적인 결과를 보였다. 그러므로 그러므로 가능하면 중고교 시절에 이 질환에 대한 정규교육 프로그램을 만들어 학생들을 효과적으로 가르치는 것이 필요하다.와 활동성 정도(r=0.378, P<.05), 평균 통증정도와 활동성 정도가(r=.330, P<.05)가 유의한 정적상관관계가 나타난 반면, 여성에서는 활동성 정도와 통증의 중증도는 유의한 관계가 없는 것으로 나타났다. 남성은 관계를 제외한 모든 항목의 통증으로 인한 지장정도와 활동성 정도가 유의한 정적상관관계가 나타난 반만 여성에서는 보행 능력, 통상적인

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에폭시 수지 모르터의 특성에 관한 실험적 연구 (Experimental Studies on the Properties of Epoxy Resin Mortars)

  • 연규석;강신업
    • 한국농공학회지
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    • 제26권1호
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    • pp.52-72
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    • 1984
  • This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

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