• Journal of the Korean GEO-environmental Society
• /
• v.8 no.3
• /
• pp.19-25
• /
• 2007

Stone columns is the ground improvement method which composed of compacted gravel or crushed stone inserted into the soft ground consisting of loose sand and clay. There are many difficulties in quantitative analysis of soil-pile interaction because settlement behavior of stone columns is affected by various parameters. In this study, various parameters of behavior of end-bearing group piles are investigated by load tests. Finally, the improved characteristics of soft ground and the influence of design parameters are investigated in this study using PR (performance ratio) value. From the PR value calculation and test results, we know that settlement behavior of stone columns is affected by area replacement ratio of composite ground, diameter of column rather than embedment ratio and mat.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.71.1-71.1
• /
• 2010

본 연구는 1.3 MW급 태양광 발전소에서 기온 및 일사량에 따른 발전성능이 유지 보수 및 사후관리에 따라 성능이 향상될 수 있음을 실측자료를 통해 입증하는데 목적이 있다. 실측자료는 2008년 5월 전북 부안에 설치된 태양광 발전소에서 측정된 기온 및 일사량에 따른 발전량을 이용하였으며, 측정기간은 2009년 1월~2009년 12월까지 1년간 모니터링을 한 데이터를 기반으로 분석하였고, 발전소 성능 지표인 PR(Performance Ratio)을 계산하여 자료로 활용하였다. 또한, 실측자료는 PVSYST를 이용하여 실측자료와 동일한 조건에서 예측된 시뮬레이션 발전량 및 PR값과 비교 분석하였다. 실측자료와 해석결과의 비교에서 월단위로 측정된 실측 발전량과 예측 발전량은 유사한 경향을 나타냈으며, 실측 발전량은 예측 발전량 대비 약 5% 낮게 나타났다. 또한, 실측 PR값은 예측 PR값보다 약 4.97% 높게 나타났는데, 이는 해석을 위해 적용되는 일사량(기상청)과 실측 일사량이 다르고, Team Function 방식으로 구동되는 인버터와 시뮬레이션에서의 인버터 구동방식의 차이 때문인 것으로 판단된다. 한편, 일조량의 증가에 따른 1.3MW급 태양광 발전소의 발전량은 비례적으로 증가하는 경향을 나타냈으며, 7월의 경우 기후특성으로 인하여 국부적으로 감소하는 특성을 나타낸다.

• Membrane Journal
• /
• v.23 no.5
• /
• pp.343-351
• /
• 2013

This study is to investigate the effects of the draw solution concentration on forward osmosis desalination performance using blended fertilizer as draw solution. As the concentration of blended fertilizer solution (draw solution) increased, the water permeate flux increased nearly linearly, but PR (performance ratio) was reduced. Using sea water and deionized water as the feed solution, respectively, at the blended fertilizer solution of 600 g/L $H_2O$, the PR obtained were 5.39 and 6.50, respectively. And as the concentration of blended fertilizer solution increased, the reverse solute flux for nitrogen (N), phosphorus (P), and potassium (K) increased nearly linearly, but specific reverse solute flux for them was reduced. The reverse solute flux and specific reverse solute flux became higher in the order of N > K > P.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.7
• /
• pp.1012-1018
• /
• 2015

The studies on the operating performance analysis or design about the fixed tilt angle flat-plate photovoltaic (PV) system are still lively going off. However the operating property analysis about the arch type PV system which means PV array were designed as round type is dissatisfied. In this paper, we theoretically established the factors which are cause of the deterioration in performance of arch type PV system. In addition, we use the Solar Pro simulation tools to design both flat-plate type and arch type 30kW PV systems. The simulations about arch type PV system applied two ways such as central inverter and string inverter were conducted. The performance ratio (PR) of the PV system with flat-plate type shows the highest value 74[%] when the tilt angle is 30°. In case of arch type, when applying central inverter method, PR value shows approximately 73[%] and no more difference with arch type of the PV array. This value shows 1[%] decrease compare with the flat-plate type. However when applying string inverter methods, the average PR value shows 80 % and 6% improved than the central inverter method.

• Journal of Animal Science and Technology
• /
• v.62 no.1
• /
• pp.21-30
• /
• 2020

This study was conducted to evaluate effects of dietary protease (PR) on growth performance, nutrient digestibility, and intestinal morphology of weaned pigs. A total of 75 weaned pigs [7.06 ± 0.18 kg of average body weight (BW); 28 day old] were randomly allotted to 3 dietary treatments in a randomized complete block design (blocks = BW and sex): a diet based on corn and soybean meal to meet the requirement of crude protein (CP) as a positive control (PC; CP = 24.49%), a low protein diet as a negative control (NC; CP = 22.51%), and NC + 0.02% PR. The PR used in this study was a commercial product containing 75,000 protease units/g derived from Nocardiopsis prasina produced in Bacillus licheniformis. Pigs were fed the dietary treatments for 6 weeks and the diets containing 0.2% chromic oxide for the last week of this study. Blood, feces, ileal digesta, and ileum samples were collected from randomly selected two pigs in each pen on respective time points. Measurements were growth performance, apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of dry matter (DM), CP, and energy, frequency of diarrhea, packed cell volume (PCV), and ileal morphology of weaned pigs. Pigs fed PC and PR had higher (p < 0.05) final BW, average daily gain (ADG), and gain to feed ratio (G:F) during overall experimental period than those fed NC. Pigs fed PC and PR had higher (p < 0.05) AID or ATTD of DM, CP, or energy than those fed NC. Moreover, pigs fed PR had higher ratio between villus height and crypt depth (p < 0.05) and number of goblet cells (p < 0.05) than those fed NC. Addition of PR decreased (p < 0.05) frequency of diarrhea for the first two weeks after weaning compared with PC and NC. In addition, pigs fed PR had lower (p < 0.05) PCV on d 14 after weaning than those fed PC and NC. In conclusion, addition of PR in nursery diets with a low protein level significantly improved growth performance, nutrient digestibility, and intestinal morphology of weaned pigs.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.6
• /
• pp.602-608
• /
• 2014

Hydrogen energy, a field of low-carbon substitute energy, can be produced by fossile fuel reforming and electrolysis of water etc. We developed 1kW class flat type reformer for PEM Fuel Cells. The PEMFC is highly sensitive to carbon monoxide because CO has detrimental effects on the performance of the fuel cell. Thus, reformed gas supplied to Fuel cell system, which maintained CO concentration below 10ppm. After applying optimum drive condition, reformed gas was measured with gas chromatography and could find out about each experimental condition of $H_2$ and CO concentration. As a results, The 1kW class plate type hydrogen generation system's optimum condition is A/F ratio ${\alpha}=1.3$, STR temperature 1023K, S/C ratio 3, and $PrOx1{\cdot}2$ 30cc/min. It turns out that installation of PrOx 2 stage is more efficient for reducing CO concentration.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.12
• /
• pp.1742-1750
• /
• 2015

As a novel approach for disease control and prevention, nutritional modulation of the intestinal health has been proved. However, It is still unknown whether branched-chain amino acid (BCAA) is needed to maintain intestinal immune-related function. The objective of this study was to determine whether BCAA supplementation in protein restricted diet affects growth performance, intestinal barrier function and modulates post-weaning gut disorders. One hundred and eight weaned piglets ($7.96{\pm}0.26kg$) were randomly fed one of the three diets including a control diet (21% crude protein [CP], CON), a protein restricted diet (17% CP, PR) and a BCAA diet (BCAA supplementation in the PR diet) for 14 d. The growth performance, plasma amino acid concentrations, small intestinal morphology and intestinal immunoglobulins were tested. First, average daily gain (ADG) (p<0.05) and average daily feed intake (ADFI) (p<0.05) of weaned pigs in PR group were lower, while gain:feed ratio was lower than the CON group (p<0.05). Compared with PR group, BCAA group improved ADG (p<0.05), ADFI (p<0.05) and feed:gain ratio (p<0.05) of piglets. The growth performance data between CON and BCAA groups was not different (p>0.05). The PR and BCAA treatments had a higher (p<0.05) plasma concentration of methionine and threonine than the CON treatment. The level of some essential and functional amino acids (such as arginine, phenylalanine, histidine, glutamine etc.) in plasma of the PR group was lower (p<0.05) than that of the CON group. Compared with CON group, BCAA supplementation significantly increased BCAA concentrations (p<0.01) and decreased urea concentration (p<0.01) in pig plasma indicating that the efficiency of dietary nitrogen utilization was increased. Compared with CON group, the small intestine of piglets fed PR diet showed villous atrophy, increasing of intra-epithelial lymphocytes (IELs) number (p<0.05) and declining of the immunoglobulin concentration, including jejunal immunoglobulin A (IgA) (p = 0.04), secreted IgA (sIgA) (p = 0.03) and immunoglobulin M (p = 0.08), and ileal IgA (p = 0.01) and immunoglobulin G (p = 0.08). The BCAA supplementation increased villous height in the duodenum (p<0.01), reversed the trend of an increasing IELs number. Notably, BCAA supplementation increased levels of jejunal and ileal immunoglobulin mentioned above. In conclusion, BCAA supplementation to protein restricted diet improved intestinal immune defense function by protecting villous morphology and by increasing levels of intestinal immunoglobulins in weaned piglets. Our finding has the important implication that BCAA may be used to reduce the negative effects of a protein restricted diet on growth performance and intestinal immunity in weaned piglets.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.1
• /
• pp.63-76
• /
• 1996

In this paper, we propose a new dynamic spatial index structure, called PR -file, for handling spatial objects and the modified hierarchical variance which measures the degree of spatial locality at each level. Under the assumption that a multidimensional search space has a circular domain, PR-file uses the modified hierarchical variance for clustering spatially adjacent objects. The insertion and splitting algorithms of PR_file preserve and index which has a low hierarchical variance regardless of object distributions. The simulation result shows that PR- file has a high hit ratio during a retrieval of objects by using an index with low hierarchical variance. And it shows a characteristic that the larger the bucket capacity, the higher the bucket utilization.

• Journal of Korea Multimedia Society
• /
• v.10 no.3
• /
• pp.401-410
• /
• 2007

Multimedia streams transmitted through the Internet have a strict playback delay time. Multimedia data arriving aster the playback time cannot be played in the receiver and are discarded. Thus, this paper proposed a protocol, in which the multimedia stream server determines whether data can be played in the receiver before sending the data. The proposed model has a PSCTP sub-layer on top of existing PR-SCTP and decides whether to send data messages, which have come from the multimedia applicationserver, and which PR-SCTP stream the data will be sent to. In addition, the proposed model uses the differentiated retransmission function of PR-SCTP. We evaluated the performance of SCTP, PR-SCTP and PSCTP using NS2 simulator. According to the results of the evaluation, the PSCTP protocol decreased the volume of transmission and increased the video decodable ratio compared to other protocols.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.1
• /
• pp.18-23
• /
• 2009

We intend to describe a 12kW building-integrated photovoltaic system which was applied into the south wall of a new building. This study showed the results that were appeared from describing the PV module manufacture and installation process, and performing generation performance analysis of BIPV system. From the result we confirmed that the generation performance of the BIPV system was changed by season. The performance ratio(PR) was about 83.6% in winter and it means that performance of this BIPV system was so good in that season. On the other hand, the PR in summer was about 75.0% dropped about 8%. It was believed that the change was influenced by the reduction of solar radiation irradiated into the PV modules by installation position and rainy spell in summer. And we also confirmed that low irradiation condition is cause of the additional loss in the total PV system. In this case, the efficiency ratio of PCS drops significantly at low input loads and the average conversion efficiency of PCS in summer was 76.4% decreased about 10% from 86% in winter.