• 제목/요약/키워드: Low-rise

검색결과 1,703건 처리시간 0.033초

비료의 조성 및 농도가 영양생장 중인 '매향' 딸기의 생장, 양분흡수 및 근권환경 변화에 미치는 영향 (Influence of the Composition and Concentration of Fertilizer Solution on Growth and Nutrient Uptake of 'Maehyang' Strawberry during Vegetative Growth)

  • 장현호;이희수;이치원;최종명
    • 원예과학기술지
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    • 제32권4호
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    • pp.484-492
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    • 2014
  • '매향' 딸기를 재배하는 동안 비료의 종류와 농도를 변화시켜 시비하고 작물 생장과 양분 흡수량 변화에 미치는 영향을 구명하여 영양진단을 위한 기초자료를 확보하고자 본 연구를 수행하였다. 증류수를 원수로 산성, 중성 및 알칼리성 비료를 조제한 후 N 농도를 기준으로 100 및 $200mg{\cdot}L^{-1}$로, pH는 6.0-6.3으로 조절하여 100일간 시비하였다. 세 종류 비료의 농도를 $100mg{\cdot}L^{-1}$로 조절하여 시비한 경우 시비 100일 후 알칼리성 비료를 시비한 처리의 생장이 우수하고 산성비료를 시비한 처리에서 가장 저조하였다. 비료 농도를 $200mg{\cdot}L^{-1}$로 조절하여 시비한 경우 중성비료를 시비한 처리의 생체중 및 건물중이 산성이나 알칼리성 비료를 시비한 처리보다 무거웠다. 식물체 무기원소 함량을 분석한 결과 N, P 및 Na 함량은 중성비료 $200mg{\cdot}L^{-1}$ 처리에서 각각 2.20, 0.51 및 0.10%로, K은 산성비료 $200mg{\cdot}L^{-1}$ 처리에서 2.60%로, Ca은 알칼리성비료 $200mg{\cdot}L^{-1}$ 처리에서 0.95%로, Mg은 알칼리성비료 $100mg{\cdot}L^{-1}$ 처리에서 0.45%로 다른 처리 보다 높았다. Fe, Mn, Zn 및 Cu 함량은 산성비료를 시비한 처리에서 높았고, 알칼리성 비료를 시비한 처리에서 뚜렷하게 낮았다. 산성비료를 100 및 $200mg{\cdot}L^{-1}$, 그리고 중성 비료 $200mg{\cdot}L^{-1}$으로 시비한 처리의 근권부 pH가 지속적으로 낮아졌다. 근권부 무기원소 농도를 분석한 결과 산성 비료 $200mg{\cdot}L^{-1}$, 중성 비료 $200mg{\cdot}L^{-1}$, 그리고 산성 비료를 $100mg{\cdot}L^{-1}$으로 시비한 처리 순으로 근권부의 $NH_4{^+}$ 농도가 낮아졌다. Ca 및 Mg 농도는 시비 84일 후까지는 알칼리성 비료를 시비한 처리의 농도가 가장 낮고 중성 비료 및 산성비료 순으로 높아지는 경향이었다. $NO_3{^-}$ 농도는 산성비료에서 낮았고, 중성 및 알칼리성 비료의 순으로 높아졌으며, 세 종류 비료를 동일한 농도로 시비한 경우 $PO_4{^3}$ 농도가 유사한 경향을 보이며 변화하였다. 이상의 결과를 고려할 때 저농도에서는 알칼리성비료, 그리고 고농도에서는 중성비료가 영양생장중인 '매향' 딸기의 관비재배를 위해 효과적이었으며, 본 연구 결과는 '매향' 딸기의 번식을 위한 시비방법 개선을 위한 기초자료로 활용될 수 있을 것이다.

우리나라 어머니의 자녀 양육의 의미 - 거제지역을 대상으로 - (An Ethnography of Child-Rearing Experiences of Korean Mothers Living on Koje Island)

  • 이수연
    • 여성건강간호학회지
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    • 제7권4호
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    • pp.518-535
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    • 2001
  • Nursing practices should be based on the understanding of human beings. In order to understand human beings, it is important to study the lifestyles and thoughts of people in their natural environment. In this sense, the cultural aspects of a society need to be studied for a culture-bound nursing service. Child care, which is an important element of nursing, is also strongly influenced by the culture of a society. Therefore, a cultural study is necessary to understand the child-rearing practices of any society. The major purpose of this dissertation is to provide basic foundations for developing a culture-based theory for nursing intervention through studying traditional cultural elements of child care in Korean society. The study examined child-rearing practices in a small village on Koje Island in the southern part of Korea. It utilized ethnographic methodologies including participatory observations and in-depth interviews. The study participants were 9 Korean mothers living on Koje Island. The average age was 52. The data were collected between July in 1998 and December in 1999. The average number of interviews per person was 7-8, and the duration of each interview was approximately 2 hours. The data were analyzed using the Spradley Analytical Method. The following 9 major child-rearing aspects of mothers on Koje Island were discovered as a result of the study: 1. Firstly, mothers on Koje Island were mostly concerned about the "Old Birth Goddess' Curse", especially during their child's early years. This concern was evidenced by their careful behavior when their child was very young and by their praying to the Old Birth Goddess not to be jealous of their babies. 2. Secondly, they wished their children to live a different and better life than themselves. It was represented by their strong motivation toward their children's education as well as their expectation for their children's success. In traditional Korean culture, Korean people think that the rise and fall of the household depend on their offsprings. Therefore, Korean mothers wish their children attain to a higher level of social status through education. 3. Third, mothers are concerned about their children's righteousness. Mothers on Koje island expect their children to live with discretion, justice, strength, respect, harmony, and to do their best in life. 4. Next was an 'anticipation of their children's happy marriage'. The attributes of this category were an 'anxiety about their children's married life', and 'an expectation of a good spouse for their children'. Because Korean people believe that only a son can continue the bloodline of a family, especially Korean mothers have a great concern of the possibility of their daughters not having a son after marriage. Also they have different expectations toward their daughter-in-laws than son-in-laws. 5. Korean mothers also derived their satisfaction from their son. It was characterized by 'excessive affection toward their son', 'dependency on their son', and 'being afraid of their married daughter having a girl like themselves'. Korean society has been a patriarchy. Therefore, a son is beloved as someone who will take care of his old parents, be in charge of ancestral rites, and provide a daughter-in-law who can conceive a son. 6. The sixth category concerned 'the differences in their expectations for their children'. The attributes in this category were 'different expectations depending on their children's gender', 'different expectations depending on their children's ability', and a 'great sympathy toward children with low abilities'. Korean mothers expect their son to become better than their daughter. 7. The seventh category was related to their 'roles in child-caring practices'. Traditionally a child was raised in an extended family system in Korea So it was not the sole duty of a mother to bring up the child. Korean mothers used to receive much help rasing children from their in-laws, and family members. On the other hand, many children grew up by themselves, because their mothers were very busy taking care of housework. Furthermore, many children also grew up in poverty. 8. Mothers also had issues related to 'conflicts in child rearing'. They were characterized by 'lack of understanding', 'rudeness of children', and 'giving vent to one's anger'. 9. Finally, mothers regretted not doing their best in child-rearing practices. It was characterized by a 'bitter feeling of repentance', 'feeling irritated', and 'feeling of unsatisfaction'.

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한국 재래 염소의 성장에 따르는 혈액상의 변동 (Blood Picture of the Korean Native Goats from Birth to Maturity)

  • 최희인
    • 대한수의학회지
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    • 제14권1호
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    • pp.115-133
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    • 1974
  • Although considerable research has been done on the changes associated with age in the blood picture of domestic and laboratory animals, little work has been made of the changes occurring at different age in the blood picture of goats. And a comprehensive survey of the bood picture of Korean native goats has not been made. The object of the present investigation was to suggest standards for the blood picture of Korean native goats at frequent intervals from birth to maturity. The goats were kept under average farming conditions in this country. Observations were made at the following ages: at birth; 2,4 and 7 days; 2, 3, 4, 5, 6, 7, 8 and 9 weeks; 2.5, 3,6 and 12 months. Blood samples were drawn from the jugular vein. It was taken between 8 and 9 a.m. except those for the at-birth period. Erythrocyte and leukocyte enumerations and, determinations of hemoglobin in blood and hematocrit value were made in the usual manner. Reticulocytes were enumerated per 1,000 erythrocytes in blood smears stained with briIliant cresyl blue and counterstained with Wright's stain. Erythrocytes counts declined from $8.7{\times}10^8/mm^3$ at birth to a low of 7.0 at 4 days of age. These values increased to 11.5 at 5 weeks and reached a maximum of 14.0 at 3 months of age; it then fell to 11.5 at 12 months of age. Concentrations of hemoglobin in blood and hematocrit values were not related to the changes of erythrocyte counts. The values at birth were higher than at any other period during the first year of life. These fell from highs of 12.3 g/100 ml and 38.0 ml/100 ml to lows of 9.2 and 29 at 4 weeks for concentration of hemoglobin in blood and hematocrit value, respectively. There was a common pattern for the hematocrit value and hemoglobin in blood which showed three phases-a fall during the first month, a rise to the third month, and a fall to the mature level at 12 months of age. Mean corpuscular volume and mean corpuscular hemoglobin showed a common pattern. The values were $44.2{\mu}m^3$ and 14.2 pg at birth and fell, at first slowly and then rapidly, to reach adult levels of 24.1 and 7.9 at 6 weeks of age for mean corpuscular volume and mean corpuscular hemoglobin, respectively. Mean corpuscular hemoglobin concentration was little affected by age. Reticulocyte was observed from birth to 4 weeks of age. Percentage of reticulocyte decreased from 0.85% at birth to 0.06% at 4 weeks of age. Total leucocyte counts increased from $5.64{\times}10^3/mm^3$ at birth to a maximum of 13.4 at 3 months; it then fell to 11.5 at 12 months of age. In differential counts myelocyte, juvenile and band form decreased with advancing age. No myelocyte and juvenile were seen after the age of 7 and 9 weeks, respectively, and band forms were rare after the age of 3 months. Percentage of mature neutrophil showed a quick decline from 52.5% at birth to reach a minimum level (34.5%) at 3 months of age; it then rose to 38% at 12 months of age. Percentage of lymphocyte increased from 39.2% at birth to maximum of 59% at 3 month of age; it then fell to 54.9% at 12 months of age. Percentage of monocyte was not affected with advance of age. Percentage of eosinophil and basophil were increased with advance of age to reach a maximum at 2 to 3 month of age. It then fell to adult level at 12 month of age.

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구멍갈파래(Ulva australis) 해조류 사멸에 미치는 여러 물리화학적 요인들의 영향 (Effects of Various Physical and Chemical Factors on the Death of Trouble Seaweed Ulva australis)

  • 김진석;곽화숙;김보관
    • Weed & Turfgrass Science
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    • 제6권3호
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    • pp.222-234
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    • 2017
  • 전세계적으로 해양녹조 대발생(green tide)은 해양생태계에 큰 위협이 되고 있으며 주로 갈파래과의 Ulva 속 식물이 대부분을 차지하고 있다. 본 연구에서는 구멍갈파래(Ulva australis, ULAUS) 사멸에 미치는 여러 물리화학적 요인들의 영향 정도를 조사하여 향후 갈파래 대발생 경감기술 확립을 위한 기초자료를 얻고자 제반 실험을 수행하였다. 순수에 8시간 침지는 아무런 영향을 받지 않았으나 염도 1.0-1.5% 수준에서 7일간의 저염화 처리는 ULAUS 포자 유출을 약 70% 경감시키는 효과가 있었다. 건조처리에 의해 초기 생체중의 40-50% 이상이 감소되면 심각한 생육 장해가 일어났다. 온도처리의 경우, ULAUS는 $30^{\circ}C$ 이상부터 생육에 심각한 영향을 받았으며 $35^{\circ}C$처리에서는 배양개시 1일만에 95% 이상 고사되었고, $40^{\circ}C$, $45^{\circ}C$, $50^{\circ}C$ 처리에서 엽절편이 90-95% 고사되는데 소요되는 처리시간은 각각 10분, 30초, 1초 이었다. pH 6 이하의 조건은 ULAUS 생육을 현저히 억제하였으며 pH 4에서는 신속히 사멸되었다. 한편 ULAUS 생육을 저해하는 10여종의 화학물질을 선발하였고 이들 중 구멍갈파래를 보다 신속히 사멸시킬 수 있는 화합물은 과산화수소를 비롯한 산화제들이었다. 이들의 결과를 종합해 볼 때, 갈파래 대발생제어에 저염화, 건조, 온도 및 화합물 처리 등이 실용화 기술개발에 동원될 수 있을 것 같았고, 이중에서 온도와 화합물 요인을 적절히 활용할 경우 보다 유용한 갈파래 발생제어 효과를 거둘 수 있을 것으로 전망되었다.

해안침식이 우세한 반폐쇄적 조간대의 퇴적작용: 한국 서해안의 함평만 (Tidal-Flat Sedimentation in a Semienclosed Bay with Erosional Shorelines: Hampyong Bay, West Coast of Korea)

  • 장진호;김여상;조영길
    • 한국해양학회지:바다
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    • 제4권2호
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    • pp.117-126
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    • 1999
  • 해안침식이 우세한 반폐쇄적 조간대의 퇴적작용을 규명하기 위해 우리 나라 서해안의 함평만 조간대에서 지형, 퇴적물, 집적율, 해안절벽의 침식율 등을 조사하였다. 함평만 조간대는 전반적으로 조류세곡(tidal creek)의 발달이 미약하고, 고조선 해빈(high-tide beach), 조간대 사주(intertidal sand shoal) 등에 의해 지형적 기복이 표시되며, 대체로 상부방향으로 오목한 지형단면을 보인다. 조간대 퇴적물은 해안절벽의 침식에 의해 공급된 육상기원의 조립 퇴적물(자갈, 모래)과 조석작용에 의해 바다로부터 공급된 세립 퇴적물(펄)이 다양하게 혼합됨으로써 복모드형 입도분포, 불량한 분급, 양의 왜도 등의 조직적 특성을 보인다. 표층 퇴적물의 퇴적상 분포는 대체로 저조선 방향과 만 입구 방향으로 세립해지는 경향을 보여, 조간대의 일반적 경향과 다르다. 조간대층은 대부분 생물교란에 의해 균질화된 상태이며, 만 입구의 펄질 조간대에서 제한적으로 렌즈상층리(lenticular bedding), 평행엽리(parallel lamination) 통이 관찰된다. 조간대의 침식은 상부 조간대와 하부 조간대를 중심으로 추로 봄철(3~5 월)과 겨울철(10~3월)에 우세하며, 침식우세 지역의 경우 연평균 침식율이 5.2 cm/yr에 이른다. 침식에 의한 해안절벽의 후퇴는 내만역의 절벽에서 최고 1.4 m/yr의 속도로 이루어지는데, 대체로 초여름(5~6 월)에 우세하여 조간대의 최대 침식시기(봄철)와 1~2 개월의 시간차를 보인다. 이렇듯 함평만과 같은 전형적인 반폐쇄적 환경 내에서 조간대와 해안절벽이 침식되는 까닭은 풍파와 지역적 해수면 상승의 상호작용 때문인 것으로 판단된다.

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Wearable Computers

  • Cho, Gil-Soo;Barfield, Woodrow;Baird, Kevin
    • 섬유기술과 산업
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    • 제2권4호
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    • pp.490-508
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    • 1998
  • One of the latest fields of research in the area of output devices is tactual display devices [13,31]. These tactual or haptic devices allow the user to receive haptic feedback output from a variety of sources. This allows the user to actually feel virtual objects and manipulate them by touch. This is an emerging technology and will be instrumental in enhancing the realism of wearable augmented environments for certain applications. Tactual displays have previously been used for scientific visualization in virtual environments by chemists and engineers to improve perception and understanding of force fields and of world models populated with the impenetrable. In addition to tactual displays, the use of wearable audio displays that allow sound to be spatialized are being developed. With wearable computers, designers will soon be able to pair spatialized sound to virtual representations of objects when appropriate to make the wearable computer experience even more realistic to the user. Furthermore, as the number and complexity of wearable computing applications continues to grow, there will be increasing needs for systems that are faster, lighter, and have higher resolution displays. Better networking technology will also need to be developed to allow all users of wearable computers to have high bandwidth connections for real time information gathering and collaboration. In addition to the technology advances that make users need to wear computers in everyday life, there is also the desire to have users want to wear their computers. In order to do this, wearable computing needs to be unobtrusive and socially acceptable. By making wearables smaller and lighter, or actually embedding them in clothing, users can conceal them easily and wear them comfortably. The military is currently working on the development of the Personal Information Carrier (PIC) or digital dog tag. The PIC is a small electronic storage device containing medical information about the wearer. While old military dog tags contained only 5 lines of information, the digital tags may contain volumes of multi-media information including medical history, X-rays, and cardiograms. Using hand held devices in the field, medics would be able to call this information up in real time for better treatment. A fully functional transmittable device is still years off, but this technology once developed in the military, could be adapted tp civilian users and provide ant information, medical or otherwise, in a portable, not obstructive, and fashionable way. Another future device that could increase safety and well being of its users is the nose on-a-chip developed by the Oak Ridge National Lab in Tennessee. This tiny digital silicon chip about the size of a dime, is capable of 'smelling' natural gas leaks in stoves, heaters, and other appliances. It can also detect dangerous levels of carbon monoxide. This device can also be configured to notify the fire department when a leak is detected. This nose chip should be commercially available within 2 years, and is inexpensive, requires low power, and is very sensitive. Along with gas detection capabilities, this device may someday also be configured to detect smoke and other harmful gases. By embedding this chip into workers uniforms, name tags, etc., this could be a lifesaving computational accessory. In addition to the future safety technology soon to be available as accessories are devices that are for entertainment and security. The LCI computer group is developing a Smartpen, that electronically verifies a user's signature. With the increase in credit card use and the rise in forgeries, is the need for commercial industries to constantly verify signatures. This Smartpen writes like a normal pen but uses sensors to detect the motion of the pen as the user signs their name to authenticate the signature. This computational accessory should be available in 1999, and would bring increased peace of mind to consumers and vendors alike. In the entertainment domain, Panasonic is creating the first portable hand-held DVD player. This device weight less than 3 pounds and has a screen about 6' across. The color LCD has the same 16:9 aspect ratio of a cinema screen and supports a high resolution of 280,000 pixels and stereo sound. The player can play standard DVD movies and has a hour battery life for mobile use. To summarize, in this paper we presented concepts related to the design and use of wearable computers with extensions to smart spaces. For some time, researchers in telerobotics have used computer graphics to enhance remote scenes. Recent advances in augmented reality displays make it possible to enhance the user's local environment with 'information'. As shown in this paper, there are many application areas for this technology such as medicine, manufacturing, training, and recreation. Wearable computers allow a much closer association of information with the user. By embedding sensors in the wearable to allow it to see what the user sees, hear what the user hears, sense the user's physical state, and analyze what the user is typing, an intelligent agent may be able to analyze what the user is doing and try to predict the resources he will need next or in the near future. Using this information, the agent may download files, reserve communications bandwidth, post reminders, or automatically send updates to colleagues to help facilitate the user's daily interactions. This intelligent wearable computer would be able to act as a personal assistant, who is always around, knows the user's personal preferences and tastes, and tries to streamline interactions with the rest of the world.

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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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U형 프리캐스트 콘크리트 벽패널로 채운 기존 철근 콘크리트 보-기둥 구조물의 전단 거동 분석 (Analysis on the Shear Behavior of Existing Reinforced Concrete Beam-Column Structures Infilled with U-Type Precast Wall Panel)

  • 하수경;손국원;유승룡;주호성
    • 한국구조물진단유지관리공학회 논문집
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    • 제19권6호
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    • pp.18-28
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    • 2015
  • 이 연구의 목표는 학교 건물과 같은 저층 보-기둥 철근콘크리트 구조 건물에서 프리캐스트 벽패널을 사용한 새로운 내진보강 방법을 개발하는데 있다. 1개의 무 보강 보-기둥 실험체와 U형 PC 패널로 보강한 2개의 보강 보-기둥 실험체에 대한 정적 이력 하중실험을 진행하였다. 앵커 접합부 실험체는 전단 파괴될 것으로 해석되었고 철판 용접 접합부 실험체는 휨 파괴할 것으로 예측되었다. 실험체의 종국 내력은 상부 접합부의 전단 내력과 PC 패널 절곡 부 휨 위험단면에서 휨 내력 중 약한 것으로 결정되었다. 이 실험체에서, 한쪽 RC기둥이 가 하중(미는 실험 하중)을 받아 PC 패널 부재를 밀게 된다면, 다른 쪽 내부 수직부재는 상부 전단 접합부로부터 부 하중(당기는 실험 하중)을 받게 되어있었다. 가 하중을 받는 2개의 부재는 합성 휨 거동이 지배적이므로 합성단면의 휨 내력이 실험체의 최종 내력을 결정하게 되지만, 이 경우 최종 내력에 대하여 상부 전단 접합부 강도의 직접적인 영향은 없다고 볼 수 있다. 그러나 부 하중(당기는 하중)을 받는 RC 기둥과 PC 패널 부재는 비합성 거동이 지배적이고 실험체의 최종 내력은 상부 전단 접합부 전단내력의 크기에서 직접 영향을 받는 것으로 파악되었다. ACI 318M-11 Appendix-D 앵커 전단설계에 기초한 전단내력 그리고 실험에서 얻은 최대하중을 적용하여 마이다스 젠 탄성설계에 의하여 계산한 전단 외력에 대한 비교 해석결과는 실험결과와 일치하는 해석결과를 보여주었다.

굽힌 후 편 철근의 겹침 이음 및 기계적 이음을 갖는 벽-슬래브 접합부의 반복하중에 대한 거동 (Cyclic Behavior of Wall-Slab Joints with Lap Splices of Coldly Straightened Re-bars and with Mechanical Splices)

  • 천성철;이진곤;하태훈
    • 콘크리트학회논문집
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    • 제24권3호
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    • pp.275-283
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    • 2012
  • 초고층 건축물의 선행 코어 후행 슬래브 접합부, 지하 연속벽과 바닥구조의 접합부, 임시 개구부 등 신구 콘크리트 접합부의 철근 이음을 위하여, 다수의 커플러를 전단키가 있는 얇은 강판에 설치한 철근 이음용 매립 강판이 최근 개발되었다. 이 공법을 사용한 접합부의 구조 성능을 검증하기 위하여, 벽체-슬래브 접합부에 대한 반복하중 실험을 실시하였다. 비교를 위해 기존에 사용되는 굽힌 철근 박스를 이용한 접합부와 이음이 없는 접합부도 함께 실험하였다. 실험 결과 철근 이음용 매립 강판을 사용한 접합부는 이음이 없는 접합부와 동일하게 [인장철근 항복]-[충분한 휨변형]-[압축 콘크리트 압괴] 후 압축 철근의 좌굴로 파괴되었다. 따라서 설계에서 가정한 충분한 연성 거동을 확인할 수 있었다. 반면, 굽힌 철근 박스를 사용한 접합부의 경우, 탄성구간에서는 철근 이음용 매립 강판과 유사하게 거동하였으나, 측면 피복 콘크리트가 빨리 탈락되었으며, 슬래브 상하부면의 겹침이음 구간에 부착 균열이 다수 발생하였다. 최종적으로 이음 없는 실험체 및 철근 이음용 매립 강판을 사용한 실험체에 비해 강도와 변형능력이 저하되었다. 또한 굽힌 후편 철근을 겹침이음한 실험체가 철근 이음용 매립 강판을 적용한 경우에 비해 강성 저하가 빠르게 진행되었다. 굽힌 후편 철근의 탄성계수는 직선 철근에 비해 낮고, 완전한 직선으로 펼 수 없기 때문에 인장력을 받으면서 일부 구간이 펴지므로 접합부의 강성을 저하시킨 것으로 판단된다. 2종류의 철근 지름(D13, D16)과 강종(SD300, SD400)에 대해, 철근이음용 매립 강판을 적용한 접합부는 공칭 강도를 충분히 상회하였다. 그러나 굽힌 후 편 철근을 사용하면 강종이 높을수록 그리고 지름이 굵을수록 휨강도가 저하되었다. 따라서 굽힌 후 편 철근의 사용에 주의가 필요하다.

구강암의 발생현황과 원인 (Literature Review on the Incidence and Risk Factor of Oral Cancer)

  • 한지형;김응권;임순환;김창희
    • 치위생과학회지
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    • 제12권5호
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    • pp.451-458
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    • 2012
  • 기존 문헌의 조사결과 우리나라의 경우 전체 암에 대한 구강암 발생률은 감소하고 있지만 발생자수는 해마다 증가하고 있었다. 외국의 경우도 발생자수는 증가하고 있고, 반면 치사율은 낮아지고 있었다. 인구학적 특성에 따라서는 전반적으로 남자가 여자보다 구강암 발생률이 높았으며, 특히 연령이 낮을수록 남자와 여자의 발생 비율의 차이가 현저히 남자가 높았다. 구강암은 연령이 높은 집단에서 발생률이 증가하였다. 연령이 높을수록 협점막에서, 연령이 낮을수록 혀에서 다발하는 것으로 보고되었으나, 전반적으로 구내암이 가장 많이 빈발하였다. 구강암의 원인을 살펴본 많은 연구에서 담배와 음주를 구강암 발생의 원인으로 꼽았다. 특히 담배와 흡연은 구강암뿐만 아니라 기타 여러 암에 영향을 미친다. 따라서 구강암을 비롯한 여러 암발생을 감소시키기 위해 제도적, 행정적, 법적으로 적극적인 금연정책이 필요하며 더불어 절주 또는 금주에 대한 홍보가 필요할 것이다. 또한 구강암의 위험요인은 국가 및 지역별, 인구학적 특성에 따른다. 즉 태양으로부터 노출된 자외선의 양이 많을수록 입술 암이 발생하는 것과 낮은 경제적 수준과 교육수준, 힘겹게 연명하는 정도의 삶의 수준은 구강암을 발생에 영향을 주게 된다. 이외에도 비타민 및 단백질 결핍과 같은 영양결핍, 구강위생정도 및 인식과 습관 등도 구강암을 발생시킨다. 따라서 사회경제적 수준에 따른 격차가 생기지 않도록 국가 내에서, 또한 국가간의 사회적 불균형의 해소가 중요하다. 암은 점점 생존율이 높아지고 있지만 아직까지 현대 질병의 사망원인으로 큰 비중을 차지하고 있으며, 계속해서 이환된 환자가 증가하고 있다. 구강암은 기타 암 발생비율에 비해 낮아지는 수치를 보이고 있지만 발생자수가 증가하고 있어 구강암 발생 동향을 파악하고 인구학적 특성과 관련된 연구가 지속적으로 시행되어야 한다. 또한 구강암과 관련된 조직학적 연구나 현재 동향의 정보는 구강암 생존과 관련된 여러 요인을 파악하는데 도움을 주며, 구강암에 관한 계속적인 연구는 효과적인 구강건강프로그램을 개선시키고 구강보건교육과 구강암 검사프로그램을 만드는데 자료로 제공될 수 있다. 이제 암의 재발기간이 5년에서 10년으로 늘어난 만큼 암은 정복 되어야 할 질병으로 구강암 발생을 줄이기 위해서는 조기진단과 공중구강보건교육 및 예방정책이 필요하다. 따라서 정부와 관련된 단체 및 3차 진료기관 등과 협력하여 치과계 직종 종사자들은 책임감을 갖고 국민의 구강건강상태를 향상시키고 구강암 발생을 감소시키는데 노력해야 할 것이다.