• Title/Summary/Keyword: Natural Experiment

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Natural Crossing of Flue -cured Tobacco Variety (황색종 연초품종의 자연교잡율)

  • 정윤화;금완수;조명조;이승철
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.38 no.6
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    • pp.495-508
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    • 1993
  • This experiment was conducted to investigate the amount of natural crossing at varying isolation distance and various transplanting time in tobacco. Normal variety and male sterile line showed an average of 1. 6 and 29% natural crossing in the adjacent plantings, respectively. The natural crossing was highest in the adjacent planting, as expected, and less at the farther distance from pollinator plants. Plants transplanted in April 20th were higher in natural crossing than those of other transplanting time.

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The Natural Frequency of a Coaxial Cylindrical Shell with Fluid Coupling (유체 연성이 작용하는 동축 원통형 쉘의 고유진동)

  • 안병준;정경훈;이성철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.975-979
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    • 1994
  • The experimental and finite element studies of a coaxial cylindrical shell filled with liquid in the annular gap were performed to understand its vibration characteristics. Finite element analysis was achieved by using ANSYS code. Form the investigation of the changing trend of natural frequencies for the change of annular gap we know that the natural frequency of the coaxial cylindrical shell varies according to the mode shape. that is, in case of in-phase mode the natural frequency decrease as annular gap increase, but in case of out-of-phase mode the natural frequency increase. Finite element analysis results show the excellent agreement with the experimental results both in air and in water case, so that analysis on other cases with be possible without experiment.

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Study on Dynamic Stability of Cylindrical Structure in Waves (파랑 중 실린더형 구조물의 동적 안정성에 대한 연구)

  • Jang, Min-Suk;Jo, Hyo-Jae;Hwang, Jae-Hyuk;Kim, Jae-Heui;Lee, Byeong-Seong;Park, Chung-Hwan
    • Journal of Ocean Engineering and Technology
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    • v.31 no.3
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    • pp.196-201
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    • 2017
  • A cylindrical structure has a very long period of heave and pitch motion response in ocean waves. To obtain the dynamic stability of a cylindrical structure, it is necessary to obtain the suitable metacentric height (GM). However, in a structure with sufficient metacentric height, Mathieu instability can occur if the natural frequency of the heave motion is double the natural frequency of the roll and pitch motion. This study carried out numerical calculations and experiments for vertical-axis wind turbines with cylindrical floaters, which had three different centers of gravity. In the regular wave experiment, the divergence of the structure motion without yaw was observed when the natural frequency of the heave motion was double the natural frequency of the roll and pitch motion. In the irregular wave experiment, the motion spectra of the structures with the different centers of gravity were compared, and one was very high when the natural frequency of the heave motion was double the natural frequency of the roll and pitch motion.

A Study of the Visual Evaluations by Variations in the Location of the Waistline of the Basic Skirt (베이직 스커트의 로우웨이스트의 위치변화(位置變化)에 따른 시각적(視覺的) 평가(評價))

  • Lee, Jung-Soon
    • Journal of Fashion Business
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    • v.9 no.1
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    • pp.67-78
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    • 2005
  • The purpose of this study is to evaluate the differences of visual evaluatations by variations in the location of the waistline of the basic skirt. In the main experiment, we make 6 samples: the 1cm-natural waistline, the 3cm-natural waistline, the 5cm-natural waistline, the 7cm-natural waistline, the 9cm-natural waistline, the 11cm-natural waistline. The data has been obtained from 43 fashion design majors. The data has analyzed by Frequency, Factor Analysis, Anova, Scheffe's test. The results of the experiment are as follows. 1. The visual effects by the location of the waistline are composed of 4 factors: the shape of the abdomen, the shape of the pelvic, the length of the upper body, and the vertical effect of the lower body. 2. The visual effects by the location of the waistline have significant differnces all factors. The location of the waistline, which have the best visual effect, are the 3cm-waistline, the 5cm-waistline, and the 7cm-waistline. These location do not emphase the shape of the abdominal and pelvic regions, but they make the length of the lower part look slimmer and longer. 3. The visual image by the location of the waistline are corn posed of 3 factors: modesty, attractiveness, comfort. 4. The visual image by the location of the waistline have significant differnces all factors. In the visual image, the 1cm-waistline and the 5cm-waistline are evaluated badly in the aspects of modesty, attractiveness, comfort. The 9cm-waistline and the 11 cm-waistline are evaluated as having the best modesty and attraction features. The 3m-waistline are evaluated as the best comfort.

Study on Construction of Soil Structure in Creation of Man-made Tidal Flat (인공 간석지 창출에 있어서 토양조성에 관한 연구)

  • Lee, Jeoung-Gyu;Suh, Hea-Dong
    • Journal of the Korea Organic Resources Recycling Association
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    • v.8 no.2
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    • pp.85-92
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    • 2000
  • The purpose of this study was to identify the controlling factors to construct tidal flat ecosystems having similar characteristics as natural ones. We transplanted the soil in a constructed tidal flat to a natural one and vice versa. Parameters monitored after these transplantations were silt content, organic matter, bacterial population and oxidation-reduction potential. Moreover, the relationship among silt content, organic matter and bacterial population was investigated by laboratory column experiment. The silt content, organic matter, bacterial population and vortical profile of oxidation-reduction potential in the soil transplanted from the constructed tidal flat to the natural one changed to similar values to those In the natural one. On the contrary, all the parameters for the soil transplanted from the natural tidal flat to the constructed one changed to similar values as those in the constructed one. The silt contents in these two transplanted soils were in proportion to the organic carbon contents and bacterial population. Similarly, the bacterial population in laboratory column experiment increased with the increase in silt and organic matter contents. It seemed to be important to select a place to enhance accumulative of silt and/or to maintain the silt content by hydrodynamic control of seawater in order to construct a tidal flat having similar characteristics as natural one.

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Comparison of Seed Germinating Vigor, Early Germination Characteristics, Germination Speed and Germination Peak Time in New Varieties of The Third Generation of Creeping Bentgrass Under Different Growing Conditions (생육환경에 따른 제3세대 크리핑 벤트그래스 신품종의 종자 발아력, 초기 발아 특성, 발아세 및 발아 피크 기간 비교)

  • Kim, Kyoung-Nam;Jung, Ki-Wan
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.11 no.5
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    • pp.79-91
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    • 2008
  • Research was initiated to investigate germination characteristics of creeping bentgrass (CB, Agrostis palustris Huds.). Seven varieties of CB were evaluated with different experiments. An alternative environment condition requiring for a CB germination test by International Seed Testing Association (ISTA) was applied in the Experiment I, consisting of 8-hr light at $25^{\circ}C$ and 16-hr dark at $15^{\circ}C$(ISTA conditions). Experiment II was conducted under a room temperature condition of 5 to $25^{\circ}C$(natural conditions). In each experiment, data such as seed germinating vigor, early germination characteristics, germination speed and germination peak time were measured. Significant differences were observed in seed germinating vigor, early germination characteristics, germination speed and germination peak time. Seed germinating vigor was variable with different environments and varieties. It was 61.50 to 98.25% under ISTA conditions and 55.00 to 98.50% under natural conditions. There were considerable variations in early germination characteristics among CB varieties according to different conditions. Early germination characteristics indicated that all varieties were 1 to 4 days faster in germination under ISTA conditions, when compared with natural conditions. The germination speed, measured as days to seed germination of 70% and 90%, was much faster with Penn A-1, Penn A-4 and Penncross under ISTA conditions. But it was even faster with L-93 and Penncross when grown under natural conditions. Differences were also observed in germination peak time with varieties and growing conditions. It was 0.57 to 2.86 days under ISTA conditions and 0.74 to 1.74 days under natural conditions. Regardless of the environment conditions, the shortest variety was L-93 and the longest one T-1. Considering germinating vigor, early germination characteristics, germination speed and germination peak time, Penn A-1, Penn A-4 and Penncross were regarded as excellent varieties under ISTA conditions in terms of early establishment characteristics, while L-93, Penn A-1 and Penncross under natural conditions. These results suggest that an intensive germination test be needed prior to planting, for the early germinating vigor, germination speed and germination peak time. Also, a proper variety selection and comprehensive site analysis for the growing environmental conditions should be done before golf course construction.

Comparison the Initial Effects of Nerve Mobilization Techniques, Static Stretching and Contract-Relax on Hamstring Flexibility and Walking Ability in Post-Stroke Hemiplegia Patients (뇌졸중으로 인한 편마비 환자의 슬괵근 유연성과 보행능력에 대한 신경가동기법, 정적 신장기법 및 수축-이완기법의 즉각적 효과 비교)

  • Kim, Yong-Jeong;Kim, Taek-Yean;Kim, Suhn-Yeop;Oh, Duck-Won
    • Journal of the Korean Society of Physical Medicine
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    • v.6 no.4
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    • pp.369-379
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    • 2011
  • Purpose : The purpose of this study is to compare the initial effect of nerve mobilization (NM), static stretching (SS), and contract-relax (CR) techniques to find the best method in improving hamstring flexibility and gait function in patients with hemiplegia. Methods : Eleven patients with hemiplegia were included in this study. Passive knee extension (PKE) range of motion and the sit and reach (SR) test were used to measure hamstring flexibility, while timed up and go (TUG) and the 10m walking (10MW) test were used to measure the subject's gait. Measurements on each test were assessed prior to the experiment, immediately following the experiment, and 30 minutes after the experiment. Analysis of the results utilized a repeated measures analysis of variance to examine hamstring flexibility and the difference in walking ability. Results : The results suggest significant increases in NM, SS, and CR techniques as they relate to hamstring flexibility (p<.05) following (both immediate and 30 minutes post experiment) PKE range of motion and the SR test, but post-hoc showed no significant difference between the three techniques (p>.05). Additionally, the results suggest significant increases in NM, SS, and CR techniques as they relate to gait function (p<.05) following the TUG test, but found no significant difference in the 10MW test (p>.05). Post-hoc analysis between the three techniques suggests that only the NM technique significantly changed gait function. The time of TUG and 10MW test showed no significant difference between the three techniques before an experiment, just after an experiment, and 30 minutes following the experiment according to the measurement points in time (p>.05). Conclusion : This study suggests NM, SS, and CR techniques immediately improve hamstring length and flexibility while improving gait function in patients with hemiplegia.

The Lightning Impulse Properties and Breakdown Voltage of Natural Ester Fluids Near the Pour Point

  • Choi, Sun-Ho;Huh, Chang-Su
    • Journal of Electrical Engineering and Technology
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    • v.8 no.3
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    • pp.524-529
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    • 2013
  • Recently, researchers have become interested in natural ester fluids, as they are an environmentally friendly alternative to mineral oils. Natural ester fluids are a natural resource made from plants; they have higher biodegradability, flash, and fire points, and a greater permittivity compared to conventional mineral oils. However, natural ester fluids also have a higher pour point, viscosity, and water content. These characteristics can hamper circulation and impair the electrical properties of an oil-filled transformer. A large amount of data has been accumulated over the years in regards to mineral insulating oil involving dielectric breakdown voltage and lightning impulse tests. However, natural ester fluids have not had their electrical properties sufficiently characterized. In this paper, we present an investigation into the characteristics of the electrical discharge development in natural ester fluids and in an oil-filled transformer near the pour points. The experiment results show that the electrical properties decreased according to a decrease in the ambient temperature and freezing time. It was found that the pour point and water content of natural ester fluids have a significant effect on the electrical properties.