• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2010년도 하계학술대회 논문집
• /
• pp.228-229
• /
• 2010

This paper presents an active voltage balancing approach using a forward fly-back power converter. In the proposed balancing scheme, cell with the higher voltage is selected to extract the extra energy and then a proportion of this extracted energy is distributed to other supercapacitors via the proposed circuit. A system structure consisting of five supercapacitors is built up to verify operation of the proposed scheme.

• 태양에너지
• /
• 제8권2호
• /
• pp.57-65
• /
• 1988

The coefficients of convective heat transfer were investigated when air is jetted to surface of the heated side-wall. The temperature on the side-wall was measured when the offsets changed from 1.5 to 10.5 as 7 steps at the state of fixed Reynolds numbers that were 35000, 29000 and 23000. The experimental results are as follows: 1. The mean Nusselt number is very high on the surface of reattached flow region. 2. The offset and the recirculation flow region decreased, while the mean Nusselt number increased between the outlet of nozzle and the region of reattachment flow. 3. The local Nusselt number is not concerned with Reynolds number on the recirculation flow and on the reattached flow region when the offset decrease. But the Nusselt number increased only when Reynolds numbers on the wall jet flow region increased. 4. The mean and the maximum Nusselt number decreases linearly, and in particular its values rapidly decrease in accordance with changing of the offset from 1.5 to 3 in inverse proportion.

• 한국건축시공학회지
• /
• 제8권3호
• /
• pp.111-117
• /
• 2008

This study provides the setting time prediction method of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24{\sim}35KJ/mol$ with slightly difference along with mixture proportion. This value is smaller than existing value $30{\sim}50KJ/mol$. It is Indicated that equivalent age using setting time can be a proper method to predict setting time and it also exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided setting time prediction value with super retarding agent contents and mineral admixture combination. Setting time prediction equation provided herein is possibly valid for estimating precise setting time of the super retarding concrete at the job site.

• 한국건축시공학회지
• /
• 제8권5호
• /
• pp.119-125
• /
• 2008

In this paper, the estimation of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) are studied based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24\sim35$ KJ/mol with slightly difference along with mixture proportion. This value is smaller than existing value $30\sim50$ KJ/mol. Based on strength development estimation. it exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided effective strength development prediction value with super retarding agent contents and mineral admixture combination. Strength development prediction equation provided herein is possibly valid for estimating accurate strength development of the super retarding concrete at the job site.

• 한국지열·수열에너지학회논문집
• /
• 제7권1호
• /
• pp.10-16
• /
• 2011

Performance of ground-source heat pumps (GSHPs) is mainly affected by ground heat exchangers which makes up more than 40% of construction cost. Exact construction and grout as backfill are important, because it is difficult to repair after being installed. As grout materials, bentonite grout material and cement material are used In this paper, thermal conductivity according to mix proportion of cement grout has been experimentally studied. Some variables were set to evaluate thermal conductivities according to change in cement content, unit water ratio, mass per volume of fresh mortar, and aggregate types. From the experimental analysis, high performance cement grout has been proposed.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 추계학술대회 논문집
• /
• pp.135-136
• /
• 2012

Renewable energy is getting more important due to its alternative usage of fossil fuel. This paper discusses the system using Peak-cut alagorithm of solar power which takes great proportion in renewable energy. It also proves the validity of this system by simulation and experiment.

• 대한지역사회영양학회지
• /
• 제3권4호
• /
• pp.556-564
• /
• 1998

The purpose of this study was to assess the iron nutritional status of college women residing in the Kyungin area. The anthropometric parameters, nutrient intake, and biochemical status of iron were measured for 102 college women. The mean height and weight were 160.3cm and 52.4kg, respectively. The proportion of subjects whose BMI was less than 20 was 41.3%. The proportion of subjects assessed as overweight(25$\geq$25%) assessed by the fat percent(FP) was 53.9%. The mean daily intake of iron was 13.90mg(77.1% of RDA), composed of 0.97mg of heme iron and 12.44mg(69.0% of RDA). When the sources of iron were grouped as rice(including bread), noodle, soup, side dish, and snack, noodle provided, 3.95mg of iron regarded as the highest amount. Subjects were taking 6.72mg(51.4% of RDA) of iron per day from main dishes(rice, bread and noodle). The fifty five percent of the subjects showed iron depletion(serum femitin<20ng/ml)and 33.4% showed suppressed erythropoiesis with iron deficiency(serum ferritin<10ng/ml). The anemic subjects assessed with transferrin saturation (<15%) represented 33.3% of the test population, whereas 11.8% of the subjects possessed less than 12g/dl of hemoglobin. Subjects not satisfied with their body shape were having significantly lower amount of energy intake(p<0.05) than the subjects satisfied with their body shape. College women having mothers who graduated from university had a significantly decreased amount of energy, carbohydrates, fat and vitamin C(p<0.05). The mean RBC and serum iron of the subjects who were on a diet more than one month were lower than those of the subjects who were not on a diet(p<0.05).

• 전기학회논문지P
• /
• 제61권2호
• /
• pp.97-102
• /
• 2012

CPV system in the desert areas or areas near the equator, as is suitable for high-temperature region. As compared to silicon solar cells, CPV system have a high proportion of a BOS (balance of system). Solar cells because of its low proportion when designing a module technology is applied in a variety of ways. Applied to the CPV system is classified into two kinds of optical technology. One of those using fresnel lens uses refraction of light energy. The other is a mirror reflection of the structure using sprays. Both of these two ways to condense the sun to collect solar cell is a form of light. And goals by using a small solar cell materials is to produce more energy. In this paper, suitable for a domestic environment, with the aim CPV Manufacturing Technology, built on a variety of modular process technology to the development of a prototype performance analysis was carried out. In particular, silicone coated on the glass by the method of implementation of the Fresnel lens SOG(Silicon on glass) by applying the lens to absorb the solar spectrum was broad. In addition to, for the analyze to characteristics of the CPV module, developed CPV module performance and generating characteristics studied. These related technology through research and development of high-performance multi-junction solar cells, modules, development of concentrating solar power systems to facilitate the growth of the market is considered to be.

• 대한가정학회지
• /
• 제36권7호
• /
• pp.25-38
• /
• 1998

This research was carried out to investigate the health condition, eating behavior and nutritional status of female high school students. The survey was conducted from July 5 to July 18, 1996 with 524 first grade students(15 to 17 years old) of H girl's high school using the questionnaire method. The levels of depression and anxiety were measured by CED-S and Spielburger's STAI-S, respectively. In addition, nutrient intakes were estimated by Convenience Method. The results of this study are as follows: 1. The mean depression and anxiety scores of the subjects were 22.23 and 26.00, respectively. The proportion of subjects with normal weight(BM) was 72.1%. The perceived health condition of subjects was moderate and 15.1% of subjects were anemic. The subjectiv health symptoms were feeling drowsy, tired eyesight, getting tired easily, catching cold frequently and frequent headache. 2. The irregularity of breakfast was high in the subjects. The problems of the eating behavior were irregular meals, unbalanced diets, excessive meals, skipping meals and food prejudice. Forty-nine percent of subjects had good eating behaviors. 3. The mean energy intake of subjects was 1717Kcal. The proportion of energy derived from carbohydrates, proteins and fats were 62.70%, 13.89% and 23.42%, respectively. The subjects consumed 59.59g of protein, 13.07mg iron, 637.49mg calcium, 553.64 R.E. vitamin A, 0.94mg vitamin B1, 1.08mg vitamin B2, 15.15mg niacin and 49.59mg vitamin C, respectively. Except niacin, other nutrient intakes were less than the Korean recommended dietary allowances(RDA), especially, iron. 4. Mother's occupation, subject's pocket money and perceived health condition were negatively correlated with eating behavior, And the depression and anxiety of subjects showed wrong eating behaviors. The effects of socioeconomic variables, depression, anxiety and perceived health condition on the nutrient intake were different depending on the kind of nutrient. The nutrient intakes differed significantly among the group of different eating behavior. The eating behavior was significantly correlated with the nutrient intake.

• 한국기계가공학회지
• /
• 제21권2호
• /
• pp.94-100
• /
• 2022

A study was conducted to significantly increase the heat transfer area by simultaneously burying the excel pipe in the floor and wall of a container house, thereby greatly reducing the initial heating time. In addition, a small hot water boiler suitable for the heating load of a small container house with a maximum area of 6 m² was studied. A wall-mounted hot water boiler was developed as a result of the study. When a hot water boiler is installed outdoors for heating, heat radiation energy is lost in winter from the hot water boiler and hot water pipe due to the low temperature. We propose an approach through which the energy loss was greatly reduced and the temperature of hot water increased in proportion to the operating time. Moreover, as the mass flow rate of the hot water flowing inside the excel pipe increased, the temperature of the hot water decreased. The temperature of the wall and floor surfaces of the container house increased in proportion to the increase in the mass flow rate of hot water flowing inside the excel tube. Natural convection heat transfer was realized from the wall and floor surfaces of the container house, and the heat transfer area was increased by a factor of 3 with respect to heat transfer area limited to the floor by the existing hot water panel. As a result, the initial temperature increase rate was much higher because of the larger heat transfer area.