• Title/Summary/Keyword: The Characteristics of Change

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Trend analysis of rainfall characteristics and its impact on stormwater runoff quality from urban and agricultural catchment

  • Salim, Imran;Paule-Mercado, Ma. Cristina;Sajjad, Raja Umer;Memon, Sheeraz Ahmed;Lee, Bum-Yeon;Sukhbaatar, Chinzorig;Lee, Chang-Hee
    • Membrane and Water Treatment
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    • v.10 no.1
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    • pp.45-55
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    • 2019
  • Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt's test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.

Analysis of the Change in the Area of Haeundae Beach Based on Wave Characteristics (파랑특성을 고려한 해운대 해수욕장의 해빈면적 변화에 관한 연구)

  • Kim, Jong-Beom;Kim, Jong-Kyu;Kang, Tae-Soon
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.2
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    • pp.324-339
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    • 2021
  • In this study, we determined the correlation between the wave characteristics and the change in the area of Haeundae Beach, conducted regression analysis between the wave characteristics and the change in beach area, and derived a formula for calculating the change in beach area. The change in beach area was calculated by applying the derived formula to wave observation data corresponding to a period of approximately 10 months, and the formula was subsequently validated by comparing the obtained results with the observed area. It is found that the error associated with the formula for calculating the change in beach area ranges from 1.5 m to 2.7 m based on the average beach width, and the correlation coefficient corresponding to the observed area ranges from 0.91 to 0.94. Furthermore, it is observed that the change in beach area is af ected by the wave direction in the western zone, wave height in the central zone, and wave height and wave period in the eastern zone. These results can contribute to understanding the impact of a coastal improvement project on the beach area fluctuation characteristics of Haeundae Beach and the ef ectiveness of such a coastal improvement project. By applying the aforementioned derived formula to highly accurate wave prediction data, the change in beach area can be calculated and incorporated for predicting significant long-term changes in beach areas. Furthermore, such a prediction can be considered as the basis for making decisions while establishing preemptive countermeasure policies to prevent coastal erosion.

Breakdown Characteristics for Imitation Air and $SF_6$ with Pressure Variation under Uniform and Non-Uniform Field (평등/불평등 전계하에서 제조공기(I-Air)와 $SF_6$에 대한 압력별 절연파괴특성)

  • Lee, Chang-Uk;Lee, Chang-Hun;Choi, Eun-Hyuck;Jang, Seung-Ho;Lee, Kwang-Sik
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2007.11a
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    • pp.259-262
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    • 2007
  • In this paper approves AC high voltage by experimental GIS(Gas Insulated Switchgear) chamber and AC 300[kV] power source to study breakdown characteristics by pressure(P) change and change of electrode distance(d) at AC high voltage of Imitation Air(I-Air, $N_2$ : $O_2$ = 79(%) : 21[%]) to alternate $SF_6$ and achieved research. Gave P change of I-Air to study I-Air's breakdown characteristics using uniform(Sphere-Sphere electrode) and non-uniform fields(Needle-Plane electrode) and studied relations breakdown voltage($V_B$) by each P different d.

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Breakdown Characteristics of Imitation Air under Uniform Fields and Non-Uniform (평등/불평등 전계 하에서의 제조공기(I-Air) 절연파괴특성)

  • Lee, Chang-Uk;Lee, Chang-Hun;Choi, Eun-Hyuck;Kim, Jung-Bae;Lee, Kwang-Sik
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1424-1425
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    • 2007
  • In this paper approves AC high voltage by experimental GIS(Gas Insulated Switchgear) chamber and AC 300[kV] power source to study breakdown characteristics by pressure(P) change and change of electrode distance(d) at AC high voltage of Imitation Air(I-Air, $N_2$ : $O_2$ = 79[%] : 21[%]) to alternate $SF_6$ and achieved research. Gave P change of I-Air to study I-Air's breakdown characteristics using niform fields(Sphere-Sphere electrode) and non-uniform fields(Needle-Plane electrode) and studied relations breakdown voltage ($V_B$) by each P different d.

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An Analysis of Concrete Characteristics by Admixing Agent and Additive Contents According to the Change of Unit-Water (단위수량 변화에 따른 혼화제 종류 및 첨가량별 콘크리트의 특성 분석)

  • Ryu, Hyun-Gi;Woo, Jong-Kwon;Cho, Myeong-Ken
    • Journal of the Korea Institute of Building Construction
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    • v.7 no.4
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    • pp.139-144
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    • 2007
  • The purpose of this study is to analyze concrete characteristics by admixing agent and additive contents according to the change of unit-water to identify its effect on compressive strength. First of all, as for flesh concrete, overall unit-water showed a tendency to decrease as component inclusion rate of admixing agent was increased. In addition, air content showed a tendency to increase by increasing WR, WB, NP series admixing agent contents, on the other hand, the change of air content was gentle by around $1.5{\pm}0.5%$ for S, T, M series agents. Bulk density showed an inverse proportion to the change of air content. As for hardened concrete, expression rate of 3-day age compressive strength was generally decreased for S, T, WR, WB, NP, M series admixing agent component. Also, expression rate of 7-day age compressive strength showed an excellent record for S, M series agents, and expression rate of 28-day age compressive strength showed a tendency to increase more than plain on the whole.

Review of Trends in Recent Climate Research by Korean Climatologists (최근 한국의 기후학 연구 동향)

  • Lee, Eun-Gul;Lee, Kyoung-Mi;Lee, Seung-Ho
    • Journal of the Korean Geographical Society
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    • v.47 no.4
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    • pp.490-513
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    • 2012
  • This study reviewed recent trends in climate research by Korean climatologists. We analyzed six domestic journals listed in the Korean Citation Index and four international journals listed in the Science Citation Index during 2001-2011. Research on climate change has rapidly increased during the study period and studies on precipitation variability have been given continual attentions among Korean climatologists. In climate change research, meteorologists focused on characteristics, prediction, and causes while geographers were more interested in characteristics and impacts of climate change. In applied climatology and bioclimatology, research on the impacts of climate change on agriculture, livestock, vegetation, and human health has increased under recent climate change. While there has been steady interest in climatography by Korean climatologists, the number of papers has generally decreased over the recent period.

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A Study on Trends and Perceptions of Spatial Changes in University Libraries (대학도서관 공간변화 동향 및 인식에 관한 연구)

  • Chung, Jae-Young;Kim, Hee-Jeon
    • Journal of the Korean BIBLIA Society for library and Information Science
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    • v.33 no.3
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    • pp.31-54
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    • 2022
  • This study is to suggest the direction of the spatial change of the university library based on the trend of the spatial change in the university libraries and a survey on the perception of the librarians. For this purpose, the characteristics of the spatial change of the university libraries from 2000 to 2020 were analyzed, and the problems of the spatial change of the university libraries were identified through a survey. As a result of the survey, there was a total of 99 spatial changes in the university libraries nationwide over the past 20 years, including new construction, extension and remodeling. In recent years, it was found that due to the university's budget tightening policy, the university libraries focus on remodeling rather than new construction or extension. The characteristics of the spatial change were analyzed as follows. First, the resting areas have been expanded in the libraries. Second, The libraries are in pursuit of pleasant and comfortable atmosphere. Third, the libraries aim to establish an innovative and creative space. All these changes have been made in order to accommodate the requests of users and increase the number of users. It was also found that spatial change has advantages in these two points: providing various spaces and increasing the number of library visitors. On the other hand, spatial change has the problems such as the increased cost of maintaining the facility and the lack of management manpower. Additionally, a few more problems of spatial change are pointed out: first, spatial change only reflects the trend of the times without making a big change in the services and the actual value of the university library. Second, it has made university libraries standardized losing each library's own characteristics. This study suggests that the spatial change of the university library should secure the distinctiveness of the university library, accommodate various changes, and aim for the symbolism that can prove the value and existence of the university library.

The Relationship of Developmental Change of Temperament and Problem Behaviors During Infancy: Early Characteristic of Temperament and Developmental Patterns (영아기 기질의 발달적 변화와 영아기 사회적 부적응 행동 간의 관계 : 초기 기질 특성과 기질의 변화 패턴을 중심으로)

  • Kim, Su-chung;Kwak, Keumjoo
    • Korean Journal of Child Studies
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    • v.28 no.6
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    • pp.183-199
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    • 2007
  • This longitudinal study investigated developmental changes in temperament and examined social adjustment problems by early temperamental characteristics and developmental patterns of temperamental change during infancy. Subjects were 153 six-month-old infants and their mothers. Infant temperament and toddler's problem behavior were measured by the Infant Behavior Questionnaire-Revised (Garstein & Rothbart, 2003) and the Toddler Behavior Checklist (Larzelere et al., 1989), respectively. Results showed that distress to limitations, high pleasure, perceptual sensitivity, and approach increased with age, while activity level, cuddliness, and vocal reactivity decreased. Infants with high scores in activity level, fear, sadness, and approach at 6 months showed more problem behaviors at 18 months. Infants showing abrupt developmental change of high pleasure and perceptual sensitivity developed more negative behavior.

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Characteristics Improvement of Hydraulic Servosystem by Using Generalized Minimum Variance Adaptive Control (일반화최소분산 적응제어를 이용한 유압 서보계의 특성개선에 관한 연구)

  • 박용호;김기홍;이진걸
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.3
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    • pp.388-394
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    • 2003
  • Hydraulic system is difficult to obtain a suitable performance due to the nonlinearity load pressure change and system parameter variation. The requirement of control a1gorithm has been complex in order to satisfy the performance. The adaptive control is a control method which is suggested to achieve the control object under the plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp. the adaptive control could keep the characteristics of closed-loop system generally. In this study. a method of combined generalized minimum variance adaptive control (GMVAC) and output error feedback is proposed, in order to solve the problem of non-minimum phase of plant and the vibration and overshoot in initial response. The control performance according to the variation of characteristics of plant is evaluated by changing the supply pressure. The experimental results show the effectiveness of the proposed scheme.

The Aging Characteristics of Polymer Electrical Insulation Materials bv UV Radiation and Salt Water Spray (옥외용 고분자 전기절연재료의 염수 및 UV조사에 의한 열화 특성)

  • 최남호;한상일;한상옥;박강식;김종석;박양범
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.11a
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    • pp.221-224
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    • 1997
  • In this study we investigated the acting characteristics of Polymers for electrical insulation by UV radiation and salt water spray treatment. We used the Polymers such as EPDM, SR. PTFE. EVA. We measured contact angle and surface resistance to know the aging characteristic of Polymer surface. And we use SEM to observe the change of the surface shape. Dry flashover voltage test impulse voltage test were carried for the polymer insulator(EVA) . Through this experiment and the analysis we could know the polymers have a good resistance to weathering conditions like as salt spray UV irradiation and mix of them. And we can compare the aging characteristics between Polymers. As a result, we could know that the surface characteristics of PTFE is better than the other. And the degree, electrical characteristics is affected by change of surface shape is not big.

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