• Title/Summary/Keyword: 습윤-건조

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A Simulation Model for the Intermittent Hydrologic Process (II) - Markov Chain and Continuous Probability Distribution - (간헐(間歇) 수문과정(水文過程)의 모의발생(模擬發生) 모형(模型)(II) - Markov 연쇄와 연속확률분포(連續確率分布) -)

  • Lee, Jae Joon;Lee, Jung Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.3
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    • pp.523-534
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    • 1994
  • The purpose of this study is to develop computer simulation model that produce precipitation patterns from stochastic model. In the paper(I) of this study, the alternate renewal process(ARP) is used for the daily precipitation series. In this paper(Il), stochastic simulation models for the daily precipitation series are developed by combining Markov chain for the precipitation occurrence process and continuous probability distribution for the precipitation amounts on the wet days. The precipitation occurrence is determined by first order Markov chain with two states(dry and wet). The amounts of precipitation, given that precipitation has occurred, are described by a Gamma, Pearson Type-III, Extremal Type-III, and 3 parameter Weibull distribution. Since the daily precipitation series shows seasonal variation, models are identified for each month of the year separately. To illustrate the application of the simulation models, daily precipitation data were taken from records at the seven locations of the Nakdong and Seomjin river basin. Simulated data were similar to actual data in terms of distribution for wet and dry spells, seasonal variability, and precipitation amounts.

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The Improvement of Wet Strength Properties of Sheet by N-Chlorocarbamoylethylation (N-chlorocarbamoylethyl화에 의한 sheet의 습윤강도 향상효과)

  • Jeong, Myung-Joon;Jo, Byoung-Muk;Oh, Jung-Soo
    • Journal of the Korean Wood Science and Technology
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    • v.27 no.3
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    • pp.63-72
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    • 1999
  • For the purpose of improving the wet strength properties of paper, cellulosic fibers were modified by the processes of carbarmoylethylation and N-chlorocarbamoylethylation. Carbamoylethylated cellulose was prepared by the reaction of acrylamide with cellulosic fibers under the alkali catalyst, and N-chlorocarbamoylethylated cellulose was prepared by the addition of sodium hypochlorite into the carbamoylethylated cellulose. In carbamoylethylation reaction, the conditions of NaOH concentration, temperature and acrylamide addition rate were considered to be important factors. An initial reactivity and degree of substitution(DS) in carbamoylethylation of cellulosic fibers were effective according to increasing the addition rates of alkali, acrylamide and the temperature condition of $40^{\circ}C$. The effective wet strength properties by N-chlorocarbamoylethylation of cellulosic fibers were indicated under the conditions of DS 0.06. The wet strength of sheet was improved to 85% at the 100% basis of dry strength. From the photograph of scanning electron microscopy, fiber cuttings on the edge of sheet sample used in tensile strength testing were found in the N-chlorocarbamoylethylated sheet, due to the improvement of fiber bonding strength. The hypochlorite treatment was effective in the recycling of N-chlorocarbamoylethylated sheet, and was reduced the wet strength of sheet to be able to reslush.

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A Study of Skid Resistance Characteristics by Deicing Chemicals (제설제 사용으로 인한 노면 미끄럼저항 특성 연구)

  • Lee, Seung Woo;Woo, Chang Wan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5D
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    • pp.813-819
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    • 2006
  • Skid Resistance is a index to represent the friction between tire and road surface, which influences driving safety. Skid resistance varies with the conditions of tire, abrasion of road surface, vehicle speed, drying, wet and freezing condition of road surfaces. Especially, freezing occurs when temperature drops below $0^{\circ}C$ followed by snow or rain causes decrease of skid resistance. To recover the decreased skid resistance deicing work is applied. As a results of deicing works, freezing condition is changed into wet condition. However the wet road surfaces containing the remaining deicings agents may not show the skid resistance of normal wet condition. In this study, skid resistances in the condition of freezing, deicing process and deicing agents remained after snow-removal are evaluated. The test results, skid resistance recover quickly when Pre-wetted salt spreading and NaCl was used as deicing method. Skid resistance of Deicing agents remained on the road surface showed that concrete is higher than asphalt. superior effect. Recovery rate of skid resistance by comparison wet condition is 54~80%.

Characteristics of Seed Germination and Promotion of Germination Rate in Pollia japonica Thunb. (나도생강의 종자 발아 특성과 발아율 향상)

  • Ro, Na-Young;Song, Eun-Young;Kim, Seong-Cheol;Jang, Ki-Chang;Moon, Doo-Young;Kang, Kyeung-Hee
    • Korean Journal of Plant Resources
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    • v.21 no.2
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    • pp.144-147
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    • 2008
  • This study was conducted to clarify the characteristics of seed germination and to promote the germination rate in Pollia japonica Thunb. that was pointed to protect by the Office of Forestry in 1997. It was better the germination rate and the growth of in the light than those of in the darkness. The seed germination of Pollia japonica showed the highest germination rate at $20^{\circ}C$ any other treated temperature. To increase the germination rate of Pollia japonica, it was conducted priming treatments and storage treatments at $4^{\circ}C$. Priming treatments using 1% NaOH, 1% KOH for 30min were effective compared to control, but soaking of 100mg/L GA3 for 24 hours, 1% NaOCl for 30min were not useful. It was higher in wet storage than in dry storage. Wet storage of seeds showed a germination rate with 95.3% in 90-day treatment, which improved 55.3% than dry storage in 90-day.

Soil Water Characteristic Curve Using Volumetric Pressure Plate Extractor Incorporated with TDR System (TDR 측정시스템이 도입된 압력판 추출 시험기를 이용한 흙-함수특성곡선 연구)

  • Jung, Young-Seok;Sa, Hee-Dong;Kang, Seonghun;Oh, Se-Boong;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.31 no.8
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    • pp.17-28
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    • 2015
  • The purpose of this study is to measure the volumetric water content of unsaturated soils during drying and wetting process by using volumetric pressure plate extractor (VPPE) incorporated with time domain reflectometry (TDR). The VPPE consists of a pressure cell, a pressure regulator, a burette system and a TDR probe. Two samples with different initial void ratios were prepared in the pressure cell, and the air pressure at the range of 0.1 kPa - 50 kPa was applied to adjust the matric suction by the pressure regulator. The burette system was used to measure the volumetric water content change of the sample according to the matric suction. In addition, the TDR probe, installed in the cell, was used to evaluate the dielectric constant from the reflected signal of the electromagnetic wave at the probe. The volumetric water content of specimen was estimated by the empirical equation between the volumetric water content and dielectric constant, which was calibrated with the Jumunjin sand. The test results show that the volumetric water content calculated by TDR probe is strongly correlated to the measured value by burette system. The hysteresis occurs during drying and wetting process. Furthermore, the degree of hysteresis reduces in the repeated process. This study suggests that TDR may be effectively used to evaluate the water content soil for the determination of water characteristic curve of unsaturated soils.

Phytolith Analysis of Sediments in the Lake Gyeongpo, Gangneung, Korea and Climatic Change in the Holocene (경포호의 식물규소체(phytolith) 분석과 Holocene 기후변화)

  • Yoon, Soon-Ock;Kim, Hyo-Seon;Hwang, Sang-Ill
    • Journal of the Korean Geographical Society
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    • v.44 no.6
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    • pp.691-705
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    • 2009
  • Phytolith analysis was made on a 660cm core from Lake Gyeongpo in the East Sea of Korean Peninsula to clarify the environmental change including climate and agricultural characteristics during the Holocene. From the results of phytolith analysis, six phytoliths assemblage zone(PAZ) were recognized from the base to the surface. PAZ I around 5,000 yr BP suggests the transition from the warm and dry to the cool and wet climatic conditions. The climate of PAZ II(ca. 4,000-2,000 BP) was kept on warm, but repeated between dry and wet conditions. PAZ III(2,000~1,000 yr BP) suggests the expansion of agricultural activities under the warm and humid climatic conditions due to the significant phytoliths production of Paniceae and Oryza sativa. While PAZ IV(1,000~500 yr BP) indicates very cool and dry conditions, PAZ V and IV suggest the warm-dry and cool-humid climatic conditions, respectively. Similar to the results of pollen analysis in the lake, the agricultural activities were recognized by PAZ III around 2,000 yr BP from the results of phytolith analysis, and the rice cultivations such as Oryza sativa have been expanded since 2,000 yr BP or later.

Estimation on Unsaturated Characteristic Curves of Tailings obtained from Waste Dump of Imgi Mine in Busan (부산 임기광산 폐석적치장 광미의 불포화 특성곡선 산정)

  • Song, Young-Suk;Kim, Kyeong-Su;Jeong, Sueng-Won;Lee, Choon-Oh
    • Journal of the Korean Geotechnical Society
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    • v.30 no.3
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    • pp.47-58
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    • 2014
  • To investigate the unsaturated characteristics of the tailings obtained from the waste dump at Imgi mine, matric suction and volumetric water content were measured in both drying and wetting processes using Automated Soil-Water Characteristics Curve Apparatus. Based on the measured result, Soil Water Characteristic Curves (SWCC) were estimated by van Genuchten model. According to the unsaturated soil classification method, the tailings of the waste dump correspond to clayey sand. As a result of Suction Stress Characteristic Curve (SSCC) by Lu and Likos model, SSCC has a shape of S which is similar to SWCC. The hysteresis phenomenon occurred in SSCCs, which means the suction stress of drying path is larger than that of wetting path in the same effective degree of saturation. The effective stress of unsaturated soil is equal to that of saturated soil when matric suction is less than Air Entry Value (AEV). However, the effective stress of unsaturated soil is larger than that of saturated soil when matic suction is more than AEV. Meanwhile, unsaturated hydraulic conductivity by van Genuchten model decreased with increasing matric suction, and the hydraulic conductivity of drying path is larger than that of wetting path.

An analysis of runoff characteristic by using soil moisture in Sulma basin (설마천 연구지역에서의 토양수분량을 활용한 유출 발생 특성분석)

  • Kim, Kiyoung;Lee, Yongjun;Jung, Sungwon;Lee, Yeongil
    • Journal of Korea Water Resources Association
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    • v.52 no.9
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    • pp.615-626
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    • 2019
  • Soil moisture and runoff have very close relationship. Especially the water retention capacity and drainage characteristics of the soil are determined by various factors of the soil. In this study, a total of 40 rainfall events were identified from the entire rainfall events of Sulma basin in 2016 and 2017. For each selected events, the constant-K method was used to separate direct runoff and baseflow from total flow and calculate the runoff coefficient which shows positive exponential curve with Antecedent Soil Moisture (ASM). In addition to that, the threshold of soil moisture was determined at the point where the runoff coefficient starts increasing dramatically. The threshold of soil moisture shows great correlation with runoff and depth to water table. It was founded that not only ASM but also various factors, such as Initial Soil Moisture (ISM), storage capacity of soil and precipitation, affect the results of runoff response. Furthermore, wet condition and dry condition are separated by ASM threshold and the start and peak response are analyzed. And the results show that the response under wet condition occurred more quickly than that of dry condition. In most events occurred in dry condition, factors reached peak in order of soil moisture, depth to water table and runoff. However, in wet condition, they reached peak in order of depth to water table, runoff and soil moisture. These results will help identify the interaction among factors which affect the runoff, and it will help establish the relationship between various soil conditions and runoff.

Soil-Water Characteristic Curves for Drying and Wetting Processes in Granite-Weathered Soil Based on Variations in Fine Contents (세립분 함량을 고려한 국내 화강풍화토의 건조 및 습윤 함수특성곡선 분석)

  • Lee, Sangbeen;Ryou, Jae-Eun;Seo, Jinuk;Jung, Jongwon
    • Journal of the Korean Geotechnical Society
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    • v.40 no.1
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    • pp.47-54
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    • 2024
  • In current slope stability analysis techniques, slope stability is evaluated based on the saturated-soil theory. However, soil-water characteristics change frequently depending on the climate. Therefore, because the saturated soil theory has limitations, the application of the unsaturated soil theory is necessary for slope stability. It is also important to evaluate the engineering properties of unsaturated soil because the capillary absorption capacity is reduced due to heavy rain, thereby causing a reduction in slope stability. In this study, soil-water characteristic tests were performed using four samples with different fine contents (0%, 10%, 20%, and 30%) using granite-weathered soil in domestic production areas. In particular, to consider the previously conducted drying process as well as the evaluation of stability due to heavy rain on the actual slope, a wetting process was conducted, in which the water content was increased. In addition, the van Genuchten (1980) model, which is the most consistent theoretical equation for the experiment, was used with various theoretical equations, and the parameters were analyzed according to the fine content of the granite-weathered soil for the drying and wetting processes.

A Study on the Fashion Accessary Product Development by Use of Korean Traditional Hanji (Part I) -Physical Properties of the Korean Traditional Paper(Hanji) Treated with Silcone resin- (전통한지를 활용한 패션 악세서리 상품개발 (제1보) -실리콘 수지로 처리된 한지의 물성변화-)

  • Kim Eun-Ah;Ryu Hyo-Seon;Kim Yong-Sook
    • Journal of the Korean Society of Clothing and Textiles
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    • v.30 no.3 s.151
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    • pp.481-486
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    • 2006
  • There are attempts to utilize Hanji for apparel material, but, the reason that the strength and durability of Hanji decrease to a great extent in the wet condition, restricts the usability of Hanji. In order to improve the resistance against water, Hanji was treated with silicone type water repellent agents. The treatment was carried out by conventional pad-dry-cure method. The optimum treatment condition was obtained by varying the concentration of repellent agent, curing temperature and time. Water repellency was tested by spray rating method. Wet and dry tensile strength, tearing resistance and abrasion resistance were examined after the treatment. Flexural stiffness and wrinkle recovery angles of hanji were also measured. In result, the optimum condition of treatment was at resin concentration of 40g/l, catalyst concentration of 20g/l(half of resin concentration), curing temperature of 160$^{circ}C$, curing time of 120 sec. Flexural stiffness of Hanji was hardly increased and wrinkle recovery angle of Hanji was improved a little by resin treatment. After the treatment, in dry condition, tensile strength and tearing resistance were little changed but abrasion resistance was improved. In wet condition, tensile strength, tearing strength and abrasion resistance were improved.