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        검색결과 60

        41.
        2007.09 구독 인증기관 무료, 개인회원 유료
        Furnace slag powder used currently in Korea needs to add special functions in response to the increase of large-scale projects. In addition, it is advantageous in that it has a lower hydration heat emission rate than ordinary Portland cement and improves properties such as the inhibition of alkali aggregate reaction, watertightness, salt proofness, seawater resistance and chemical resistance. However, furnace slag powder is not self-hardening, and requires activators such as alkali for hydration. Accordingly, if recycled fine aggregate, from which calcium hydroxide is generated, and furnace slag, which requires alkali stimulation, are used together they play mutually complementary roles, so we expect to use the mixture as a resource-recycling construction material. Thus the present study purposed to examine the properties and characteristics of furnace slag powder and recycled aggregate, to manufacture recycled fine aggregate mortar using furnace slag and analyze its performance based on the results of an experiment, to provide materials on mortar using furnace slag as a cement additive and recycled fine aggregate as a substitute of aggregate, and ultimately to provide basic materials on the manufacturing of resource-recycled construction materials using binder and fine aggregate as recycled resources.
        4,000원
        42.
        2007.09 구독 인증기관 무료, 개인회원 유료
        Carbonized concrete structure becomes superannuated gradually and its accelerated subsequent deterioration process leads to corrosion of steel while it ages. Recently economical and environmental concern about remodeling such superannuated concrete, including the basic structure of concrete, has been rapidly growing. Alkali restorative, which restores alkalinity in carbonized concrete structure, is used in the field of remodeling in order to improve the property of concrete structure. There have been many different kinds of materials which restore alkalinity in carbonized concrete. They can be classified according to their structural elements. This study focuses on the alkali restorative which mainly consists of silicic lithium metallic salt while examining the durable effectiveness of the factors (such as water permeation, surface erosion, elution of alkali, etc.), which will continuously affect concrete as deteriorating factors even after the restoration of alkali. The result shows that the alkali restorative consisting mainly of silicic lithium contributes to water-resistance, surface strength, and long term durability of alkali due to water permeation in carbonized concrete.
        4,000원
        43.
        2007.09 구독 인증기관 무료, 개인회원 유료
        Carbonation in concrete structures has been handled as the most fundamental and critical factor related to the durability of reinforced concrete. As a result, there have been efforts to develop repair materials to control carbonation As one of these efforts, alkali recovery agents have been presented as materials for increasing the re-alkalization and durability of carbonated concrete structures. However, in applying them in the field, the performance and quality of concrete recovered after an alkali recovery agent is applied has not been fully assessed. Therefore, to examine the recovered performance of concrete structures resulting from the application of an alkali recovery agent, the present study assessed the depth of carbonation and the degree of deterioration of 20 years or older reinforced concrete structures, and analyzed the quality of concrete after applying an alkali recovery agent to the structures. This study aimed at providing basic information for the application of alkali recovery agents in the field. In this experiment, alkali recovery agents of the lithium silicate line, which are most common in Korea, were applied and cured using concrete of the same size. The degree of recovery was investigated according to the length of time in the initial curing stage, and based on the investigation, the maintenance performance of the alkali recovery agent was assessed according to the age of exposure to the open air. For these tasks, this experiment sampled concrete of different degrees of deterioration, applied alkali recovery agents to them, and observed re-alkalization and changes in the internal texture of the concrete.
        4,000원
        44.
        2007.03 구독 인증기관 무료, 개인회원 유료
        Recently Ultra high strength concrete is actively being developed and studied, and this trend is explained with the following effects. Technological effects expected from the application of Ultra high strength concrete include the reduction of section, the decrease of structure mass and the improvement of workability. As for the reduction of section, the use of Ultra high strength concrete is effective for plane and height, and the effect is even higher when it is applied to high-rise buildings. The decrease of concrete mass resulting from high strength is advantageous for earthquake resistance, reduces the use of earthquake-resistant members, and brings resource substitution effects. In addition, forms can be removed early thanks to self-fillability and early expression of strength resulting from the high fluidity, and this increases construction efficiency and shortens construction period. Recently there is increasing interest and investment in high-rise buildings throughout the world, and countries are competing for higher buildings in order to display national status and technological power through high-rise buildings. In addition, the use of concrete materials in steel-frame building is increasing as residential buildings are growing higher. Currently the application of Ultra high strength concrete is limited to high-rise buildings and protective buildings for special purposes. However, its application is expected to expand to attain the effects of Ultra high strength concrete. For this purpose, we tested the field applicability of Ultra high strength concrete using simulated members. Mixture ratios derived from basic experiment were tested using reduced simulated members. Using the obtained results, the decrease of hydration heat and the increase of compression strength were compared and the optimal mixture ratio was selected. Concrete of the selected mixture ratio was produced at a ready-mixed concrete factory and placed at a construction site using a pump car. Through the experiment on field applicability, we presented basic materials on the construction-related and mechanical characteristics of Ultra high strength concrete.
        4,000원
        45.
        2007.03 구독 인증기관 무료, 개인회원 유료
        Ordinary concrete uses aggregate sufficiently soaked with water, and is weighed, mixed with other materials and placed in accord with performances required in the construction field. Recently special concrete with high fluidity and durability is required but it is difficult to use top-quality concrete due to lack of high-quality aggregate, delayed transportation because of traffic jam, etc. In addition, sometimes the use of a remicon is inevitable just for small-sized concrete constructions or it is difficult for a remicon to reach remote construction places such as mountainous areas. To solve these problems, this study attempted to pack concrete materials. In other words, it is to instantize concrete. This study dried aggregate, a material of concrete, and compared the change of absorption phase of the aggregate in water and in paste in order to examine the effect of the dryness of aggregate on its absorption rate and, based on the absorption rate, decided water addition ratio necessary for the reduction of unit quantity caused by the use of dry aggregate in designing concrete mixture, and analyzed the properties of unhardened concrete according to water addition ratio in manufacturing concrete using aggregate in the state of absolute dryness and in the state of surface dryness.
        4,000원
        46.
        2006.09 구독 인증기관 무료, 개인회원 유료
        Most concrete is recently made of an aggregate which is properly absorbed, and carried in it in order to do capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore, For solving the problems we apply to a packing method for using dried materials. That is to say that it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate’s absorption following the rate of adding water, for using existing materials.
        4,000원
        47.
        2006.09 구독 인증기관 무료, 개인회원 유료
        This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressivε strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.
        4,000원
        48.
        2006.02 구독 인증기관 무료, 개인회원 유료
        Exterior tile setting can be divided into two types: post-bonding method, and pre-bonding method. Pre-bonding method. In pre-bonding method, different from the post-bonding method, the process of background mortaring is eliminated, saving cost of materials, work hour, and labor expenses, and it doesn’t require time for curing. It is proved that pre-bonding method of manufactured PC tile is economical in terms of Life Cycle Cost, because it method is high in stability and reduces a term of work, and cost low in maintaining and repairing. There are many problems in applying pre-bonding method to real construction work, including the efflux of cement pastes during the process of vibration tampering, and the falling off or breaking of PC tile caused by the contact of vibrator, the cost increase that results from manufacturing overly strength-revealing concrete regardless of the strength of concrete used in the manufacturing of PC cotton wall. The purpose of this study, therefore, is to present ways to resolve above problems by using fluidized concrete in PC manufacturing, and, to find out an appropriate mixture of high fluidized concrete used for PC manufacturing, targeting 280kgf/cm² of specified concrete strength by conducting fundamental experiments, and to provide basic data for bringing pre-bonding method of high fluidized concrete tile into practical use. For this purpose, this study compares adhesive strengh between tiles attached on mock experimental structure, with different mixture rate and curing method, and review and compares marginal concrete deformation rate with the drying shrinkage of concrete by imposing vertical compressive loading until the falling-off of concrete
        4,000원
        49.
        2006.02 구독 인증기관 무료, 개인회원 유료
        Because of building higher story and larger buildings, and because current concrete, a basic construction material, needs higher strength rather than normal strength, the use of high-strength concrete becomes more widely spread. High-strength concrete shows very high temperature increase due to inside heat of hydration different from normal-strength concrete, and because mass concrete under low temperature shows temperature stress due to temperature difference between inner and outer parts, it is known or reported that there is a significant difference between the compressive strength of srtucture and that of specimen for management, and between the compressivestrength of circular specimen made by standard underwater curing and structure concrete Therefore, in this research, an adiabatic curing box was manufactured which can provide hydration heat hysteresis of high strength mass concrete members and similar hydration heat hysteresis, using insulating materials, as a easy and exact method to manage compressive strength of rnass concrete member under low temperature, and the features of concrete member and those of specimen for management were compared.
        4,000원
        51.
        1998.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        고정발생원으로 부터 배출되고 있는 이산화탄소를 분리하여 회수 및 재이용하는 기술개발이 에너지 보전 측면에서 뿐만 아니라 환경오염 문제 등을 해결할 수 있는 중요한 과제이다. 특히 내열성, 내식성 및 기계적 강도가 뛰어난 세라믹의 특성을 이용한 기체분리막을 응용한다면 고온으로부터 저온까지의 폭넓은 온도, 압력, 가스조성의 배기가스로부터 이산화탄소를 분리하는 것이 가능해 진다. 따라서 본 총설에서는 현재 일본에서 국책과제로 진행되고 있는 이산화탄소의 고온분리에 대한 연구개발(이하, 'CO2 프로젝트'로 약칭) 현황을 소개하고자 한다.
        4,000원
        52.
        1996.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,000원
        53.
        1995.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,600원
        55.
        1991.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A study of eating behavior was conducted among 274 children of Nan Hyang elementary school, located in low income area of Seoul, where a school lunch program is not operated. During weekdays, 19.6% of children ate breakfast and 18.4% ate supper alone or with their siblings. The school provided boxed lunches for 10.5% of the children with governmental funds, who were chosen by the school based on their household income. But the percentage of the children skipping breakfast was 14.6%, lunch 10.3% and supper 8.0%. The results of nutritional analysis of the children who had three meals a day and those of children skipped one of the regular meals were compared. The group who had three meals consumed more nutrients except vitamin C than the group skipped meal (p〈0.01). Most common meal pattern was consisted of cooked rice, Kimchi and side dishes. When the children didn't have afternoon classes, 10.0% of the children ate Ramen only at home without any side dishes. Among the protein sources, the beans and bean products were the most common items. When we studied the three different lunches such as A) the boxed lunches provided by school, B) the boxed lunches from home and C) the lunches ate at home, the A) lunches provided the most common items. When we studied the three different lunches such as A) the boxed lunches provided by school, B) the boxed lunches from home and C) the lunches ate at home, the A) lunches provided the milk products, fruits, ice cakes·setc. Their favorite foods were fruits, yoghurt, Chinese black noodle, and sweet potatoes whereas being not prefered foods, were aromatic vegetables. It seemed that the increasing rate of working mothers and the overflooding of instant foods have caused to neglect children's meal management. To solve these problems, nutrition education and extend of school lunch programs should be emphasized.
        4,300원
        56.
        1991.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 부페식당 이용자의 식생활 태도를 알아보기 위해 설문조사를 실시하였는데 결과는 다음과 같다. 1) 조사대상자의 일반환경 조사대상자의 연령은 6세부터 70세까지로 20대, 30대, 40대가 주를 이루었고, 여자가 65.1%로 여성들이 많이 찾는 조사대상 부페식당의 특색을 보였다. 직업은 가정주부가 27.2%, 사무직이 19.3%, 전문직이 17.3%였고, 학생이 30.3%였다. 2) 평소 부페음식에 대한 견해에 관한 조사 평소 부페식당 이용이 '한 주에 1~2회'가 1.6%, '한 달에 1~2회'가 13.7%, '서너달에 1~2회'가 43.9%, '일년에 1~2회'가 36.9%, '처음'이 2.7%였다. 대상자들은 부페음식에 대해 음식의 가지수가 많고 마음대로 선택할 수 있고 음식의 모양, 진열 및 정갈함, 많이 먹을 수 있는 점 등에 대해서는 좋다고 생각하는 반면, 음식을 가지러 왔다 갔다 하는 점, 가격 등에 대해서는 부정적인 반응을 보였다. 3) 부페식당에서의 식사행동 부페식당에 온 이유는 '가족파티'가 31.3%였고, 동행인은 평균 9.3±4.3명이며 주로 가족 및 친척, 직장 동료였다. 식사에 소요된 시간은 1시간 32분±26분이었고, 음식을 가져온 첫수는 평균 3.7±1.2회였으며, 최고 10회가 있었다. 만복감 후 식사첫수는 평균 1.2±0.8회였다. 부페식사시 가장 먼저 먹은 음식은 스프 23.9%, 샐러드 23.9%였는데, 여자는 스프, 샐러드의 비율이 높은 반면, 남자는 육류, 어패류의 비율이 높았으며, 음식 선택시 기준은 '내가 좋아하는 음식'이 70.7%로 가장 높게 나타나 부페식당 이용자들이 바람직한 식사순서 및 음식선택에 대한 인식이 낮음을 알 수 있었다. 부페식당에서 가장 좋아하는 음식의 국적은 54.4%가 한국음식으로 나타났다. 부페식사에서 '약간' 또는 ‘대단히 과식했다'고 응답한 경우가 64.0%로 많은 대상자들이 과식하는 것으로 나타났는데 이로 인한 건강 및 영양문제에 대한 교육이 필요하고 운영면에서는 이러한 일종의 음식의 낭비를 줄일 수 있는 방안에 대한 연구가 필요하다고 사료되었다. 5) 향후 부페식당의 발전방향에 대한 의견 부페식당의 발전방향에 대해 '가지수를 줄여서라도 가격을 짜게 하자'는 의견이 82.9%로 대부분 조사 대상자들이 현재 부페가격에 대해 부정적인 반응을 보였다. '한국음식을 더 많이 해서 전통음식과 친밀한 장소로 발전시키자', '계절식품을 이용하고 비슷한 종류의 음식은 빼서 가격을 낮추자', '연령에 따라서, 또, 성인에서는 성별에 따라 가격 차이를 두자'는 의견 등이 있었다.
        4,000원
        58.
        2007.08 KCI 등재 서비스 종료(열람 제한)
        Passive sampler is a simple and cost-effective measuring equipment for ambient and indoor air pollution. We studied the performance of a short term (1 hour mean concentration) ozone passive sampler which was coated with a colorant (indigo carmine) to a filter substrate. Acetone and sulfamic acid added ozone passive sampler was investigated to measure short term mean ozone concentration. Ozone response and interference of criteria air pollutant(SO2, NO2, CO) on a short term ozone passive sampler was tested through experimental chamber. The results show sulfamic acid added passive ozone sampler have good response in ozone exposure. Interference of NO2 gas is larger than other two criteria gases.
        59.
        2003.12 KCI 등재 서비스 종료(열람 제한)
        본 연구에서 8종의 생약 추출물이 A. parasiticus의 배양시 aflatoxin B1 생성에 미치는 효과를 조사하였다. 배지의 pH는 배양 3일 후에 모든 생약 추출물이 pH 4 이하를 나타냈으며 구기자, 오매, 계피, 두충은 배양 6일에 다시 pH 4 이상으로 상승하였고 이중 대추가 배양 기간 중 가장 낮은 pH를 나타냈다. 균체 생성량은 모든 실험군이 대조군보다 높았으며 갈근, 두충, 오미자, 대추, 오매,구기자, 목과의 순으로 나타났다. 이중 갈근이 최대 생성량을 나타냈으며 목과가 가장 낮은 생성량을 나타냈다. Aflatoxin B1은 갈근과 대추 추출물을 제외한 모든 실험군에서 생성이 억제되었다. 특히 계피, 오매, 두충 구기자, 오미자 추출물 에서 aflatoxin B1 생성이 현저히 저하되었으며 계피가 가장 큰 억제 효과를 나타냈다. 균체량이 많이 생성되면 aflatoxin B1 생성이 적어지고 균체량이 적게 생성되면 aflatoxin B1의 생성이 많아졌다. Aspergillus parasiticus에 의해 aflatoxin B1을 가장 적게 생성하는 계피와 가장 많이 생성하는 갈근 추출물의 총단백질 생성량은 계피는 3일째 (34.5%), 갈근 ext ract는 4일째 (36.4%) 총단백질의 함량이 최대가 되어 균체 내의 총단백질의 함량은 계피와 갈근 추출물을 첨가한 시험군이 게조군의 총단백질 함량 (32.7%)보다 약간 많았으며 aflatoxin B1 생성 및 축적이 최대가 되는 시기는 총단백질량이 최대가 되는 시기보다 대체로 1일 정도 늦게 나타났다.
        60.
        2003.07 KCI 등재 서비스 종료(열람 제한)
        The short-term version of Industrial Source Complex Model(ISCST3) was evaluated for estimating short-term concentrations using criteria pollutant(SO2, NO2, CO, PM10) data form emission inventory of Young Tong area in Suwon for the year 2002. The contribution of pollutant concentration from point, line, area sources was found 21.8, 76.5 and 1.6%. Statistical parameters, such as correlation coefficient, index of agreement(IA), normalized mean square error(NMSE) and fractional bias(FB) were calculated for each pollutants. The model performance were found good for PM10(82%) and NO2(69%), but poor for SO2(34%) and CO(13%).
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