• Title, Summary, Keyword: Hysteresis

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Variation of Suspended Solid Concentration, Electrical Conductivity and pH of Stream Water in the Regrowth and Rehabilitation Forested Catchments, South Korea (개벌 재생림유역과 사방지 혼효림유역에서 강수시 계류수의 부유물질농도 및 전기전도도와 pH 변화)

  • Jun, Jaehong;Kim, Kyongha;Yoo, Jaeyun;Choi, Hyung Tae;Jeong, Yongho
    • Journal of Korean Society of Forest Science
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    • v.96 no.1
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    • pp.21-28
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    • 2007
  • This study was conducted to investigate how the qualities of the stream water vary during the event in the regrowth and rehabilitation catchments in Yangju, Gyeonggido, from June to September 2005. During the observation periods, we sampled the stream water continuously by an auto-sampler (ISCO, 6712FR). The sampled waters were analyzed for suspended solid concentration, electrical conductivity and pH. The suspended solid concentration during the event increased concurrently with the stream flow. The peak of suspended solid concentration usually precedes the peak flow. The maximum value of suspended solid concentration was 420.89 mg/l in the event 1 at the regrowth catchment. Among the events simultaneously sampled at both catchments, the maximum values of suspended solid concentration were 212.8 mg/l and 58.24 mg/l in the event 3 at the regrowth and rehabilitation catchment respectively. The maximum value of EC in each event showed in the early stage of rising limb. EC decreased during the rising limb, and then showed minimum value at peak flow. EC gradually increased to pre-event value after minimum one. pH varied in similar pattern with EC. The maximum value of suspended solid concentration during each event was 2.8 to 4.3 times higher at the regrowth catchment than at the rehabilitation catchment. And the EC during each event was higher at the regrowth catchment than at the rehabilitation catchment. This results indicate that a disturbed forest soil during clear cutting at regrowth catchment still has been unstable.

Thickness Dependence of Amorphous CoSiB/Pd Multilayer with Perpendicular Magnetic Anisotropy (비정질 강자성체 CoSiB/Pd 다층박막의 두께에 따른 수직자기이방성 변화)

  • Yim, H.I.
    • Journal of the Korean Magnetics Society
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    • v.23 no.4
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    • pp.122-125
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    • 2013
  • Perpendicular magnetic anisotropy (PMA) is the phenomenon of magnetic thin film which is preferentially magnetized in a direction perpendicular to the film's plane. Amorphous multilayer with PMA has been studied as the good candidate to realization of high density STT-MRAM (Spin Transfer Torque-Magnetic Random Access Memory). The current issue of high density STT-MRAM is a decrease in the switching current of the device and an application of amorphous materials which are most suitable devices. The amorphous ferromagnetic material has low saturated magnetization, low coercivity and high thermal stability. In this study, we presented amorphous ferromagnetic multilayer that consists of an amorphous alloy CoSiB and a nonmagnetic material Pd. We investigated the change of PMA of the $[CoSiB\;t_{CoSiB}/Pd\;1.3nm]_5$ multilayer ($t_{CoSiB}$ = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 nm, and $t_{Pd}$ = 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 nm) and $[CoSiB\;0.3nm/Pd\;1.3nm]_n$ multilayer (n = 3, 5, 7, 9, 11, 13). This multilayer is measured by VSM (Vibrating Sample Magnetometer) and analyzed magnetic properties like a coercivity ($H_c$) and a magnetization ($M_s$). The coercivity in the $[CoSiB\;t_{CoSiB}\;nm/Pd\;1.3nm]_5$ multi-layers increased with increasing $t_{CoSiB}$ to reach a maximum at $t_{CoSiB}$ = 0.3 nm and then decreased for $t_{CoSiB}$ > 0.3 nm. The lowest saturated magnetization of $0.26emu/cm^3$ was obtained in the $[CoSiB\;0.3nm/Pd\;1.3nm]_3$ multilayer whereas the highest coercivity of 0.26 kOe was obtained in the $[CoSiB\;0.3nm/Pd\;1.3nm]_5$ mutilayer. Additional Pd layers did not contribute to the perpendicular magnetic anisotropy. The single domain structure evolved in to a striped multi-domain structure as the bilayer repetition number n was increased above 7 after which (n > 7) the hysteresis loops had a bow-tie shapes.

Analysis on the Shear Behavior of Existing Reinforced Concrete Beam-Column Structures Infilled with U-Type Precast Wall Panel (U형 프리캐스트 콘크리트 벽패널로 채운 기존 철근 콘크리트 보-기둥 구조물의 전단 거동 분석)

  • Ha, Soo-Kyoung;Son, Guk-Won;Yu, Sung-Yong;Ju, Ho-Seong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.18-28
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    • 2015
  • The purpose of this study is to develop a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. The results were analyzed to find that the specimen with anchored connection experienced shear failure, while the other specimen with steel plate connection principally manifested flexural failure. The ultimate strength of the specimens was determined to be the weaker of the shear strength of top connection and flexural strength at the critical section of precast panel. In this setup of U-type panel specimens, if a push loading is applied to the reinforced concrete column on one side and push the precast concrete panel, a pull loading from upper shear connection is to be applied to the other side of the top shear connection of precast panel. Since the composite flexural behavior of the two members govern the total behavior during the push loading process, the ultimate horizontal resistance of this specimen was not directly influenced by shear strength at the top connection of precast panel. However, the RC column and PC wall panel member mainly exhibited non-composite behavior during the pull loading process. The ultimate horizontal resistance was directly influenced by the shear strength of top connection because the pull loading from the beam applied directly to the upper shear connection. The analytical result for the internal shear resistance at the connection pursuant to the anchor shear design of ACI 318M-11 Appendix-D, agreed with the experimental result based on the elastic analysis of Midas-Zen by using the largest loading from experiment.

Studies on the Physical Properties of Major Tree Barks Grown in Korea -Genus Pinus, Populus and Quercus- (한국산(韓國産) 주요(主要) 수종(樹種) 수피(樹皮)의 이학적(理學的) 성질(性質)에 관(關)한 연구(硏究) -소나무속(屬), 사시나무속(屬), 참나무속(屬)을 중심(中心)으로-)

  • Lee, Hwa Hyoung
    • Journal of Korean Society of Forest Science
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    • v.33 no.1
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    • pp.33-58
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    • 1977
  • A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potentially valuable resourses. As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Pinus, Quercus, and Populus grown in Korea can be enhanced by learning its physical and mechanical properties. However, the study of tree bark grown in Korea have never been undertaken. In the present paper, an investigative study is carried out on the bark of three genus, eleven species representing not only the major bark trees but major species currently grown in Korea. For each species 20 trees were selected, at Suweon and Kwang-neung areas, on the same basis of the diameter class at the proper harvesting age. One $200cm^2$ segment of bark was obtained from each tree at brest height. Physical properties of bark studied are: bark density, moisture content of green bark (inner-, outer-, and total-bark), fiber saturation point, hysteresis loop, shrinkage, water absorption, specific heat, heat of wetting, thermal conductivity, thermal diffusivity, heat of combustion, and differential thermal analysis. The mechanical properties are studied on bending and compression strength (radial, longitudinal, and tangential). The results may be summarized as follows: 1. The oven-dry specific gravities differ between wood and bark, further more even for a given bark sample, the difference is obersved between inner and outer bark. 2. The oven-dry specific gravity of bark is higher than that of wood. This fact is attributed to the anatomical structure whose characters are manifested by higher content of sieve fiber and sclereids. 3. Except Pinus koraiensis, the oven-dry specific gravity of inner bark is higher than that of outer bark, which results from higher shrinkage of inner bark. 4. The moisture content of bark increases with direct proportion to the composition ratio of sieve components and decreases with higher percent of sclerenchyma and periderm tissues. 5. The possibility of determining fiber saturation point is suggested by the measuring the heat of wetting. With the proposed method, the fiber saturation point of Pinus densiflora lies between 26 and 28%, that of Quercus accutissima ranges from 24 to 28%. These results need be further examined by other methods. 6. Contrary to the behavior of wood, the bark shrinkage is the highest in radial direction and the lowest in longitudinal direction. Quercus serrata and Q. variabilis do not fall in this category. 7. Bark shows the same specific heat as wood, but the heat of wetting of bark is higher than that of wood. In heat conductivity, bark is lower than wood. From the measures of oven-dry specific gravity (${\rho}d$) and moisture fraction specific gravity (${\rho}m$) is devised the following regression equation upon which heat conductivity can be calculated. The calculated heat conductivity of bark is between $0.8{\times}10^{-4}$ and $1.6{\times}10^{-4}cal/cm-sec-deg$. $$K=4.631+11.408{\rho}d+7.628{\rho}m$$ 8. The bark heat diffusivity varies from $8.03{\times}10^{-4}$ to $4.46{\times}10^{-4}cm^2/sec$. From differential thermal analysis, wood shows a higher thermogram than bark under ignition point, but the tendency is reversed above ignition point. 9. The modulus of rupture for static bending strength of bark is proportional to the density of bark which in turn gives the following regression equation. M=243.78X-12.02 The compressive strength of bark is the highest in radial direction, contrary to the behavior of wood, and the compressive strength of longitudinal direction follows the tangential one in decreasing order.

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A Study on Historicity of 《Three Purities Album (三淸帖)》 in the Kansong Art Museum (간송미술관 소장 《삼청첩(三淸帖)》의 역사성에 대한 고찰)

  • Baik, In-san
    • MUNHWAJAE Korean Journal of Cultural Heritage Studies
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    • v.46 no.2
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    • pp.186-205
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    • 2013
  • ${\ll}$Three Purities Album${\gg}$ in the Kansong Art Museum is an album of poems and pictures of apricot tree, orchids and bamboos drawn by Lee Jeong. Given that the poems and pictures in the album were drawn by Lee Jeong who has been recognized as a person who established the standards of ink bamboo drawings in the Joseon Dynasty, the album is highly valuable. Nevertheless, there are more values and meanings that Three Purities Album has. The production circumstances and transmission processes of Three Purities Album include the historical characteristics and meanings of the time so that it is also worthwhile as a historical material. During the Japanese Invasion of Korea in 1592, Lee Jeong was stabbed with a sword by Japanese invaders and got injured. After he suffered, he tried to make his masterpiece in his lifework and finally created Three Purities Album. For the work, Lee Jeong received memorial writings from Choi Rip, Cha Cheon-ro and Han Ho, and asked them writings. They were the best literary men in the poem and calligraphy fields at that time. Yu Geun, Lee An-nul, and Yu Mong-in made writings and poems to praise his work. Likewise, ${\ll}$Three Purities Album${\gg}$ is the 'treasure of the time' created through the participation of the best literary men at that time. Given the aspects, it is fair to say that ${\ll}$Three Purities Album${\gg}$ is not simply a personal artwork of Lee Jeong, but is a comprehensive artwork and also a cultural monument created through the skills and capabilities of the literary artists in the middle of the Joseon Dynasty. After the death of Lee Jeong, Three Purities Album was handed over to Hong Ju-won. But, during the second Manchu Invasion into Korea in 1636, the album was in danger of disappearance by fire. As of now, there are still signs of fire in it, which vividly shows the urgent situation at that time. After the second Manchu Invasion into Korea in 1636, Hong Ju-won recovered some damaged writings with the help of Yoon Shin-ji. Since then, the album had been handed down as a family treasure over the next 7 generations. It can be found in the writings by Song Si-yeol and Uh Yu-bong. Unlike the literary men who praised Three Purities Album in terms of its work when Lee Joeng was alive, they focused on the transmission courses of the album and involved persons. That seems to be because the stories and characters appearing in Three Purities Album impressed the later literary men and were meaningful to them rather than the album itself. It strongly reflected the positions of Hong Jung-gi and Hung Sang-han who asked for writings as the descendants of Hong Ju-won. That is because the traces of the persons involved in Three Purities Album are the causes for admiring their ancestors and enhancing their political legitimacy and family dignity. Therefore, in this aspect, it is possible to witness the fundamental causes of the unique artistic awareness by East Asian people who consider their historical meanings as well as the aesthetic value of artworks significant. Unfortunately, during the Japanese invasion at the end of the Joseon Dynasty, Three Purities Album was handed over to Japanese Tzuboikouso. But, fortunately, Jeon Hyeong-pil who made an effort to regain our cultural assets by investing his entire property during the Japanese Imperialism regained the album, which is now preserved in the Kansong Art Museum. ${\ll}$Three Purities Album${\gg}$ truly includes the whole processes to overcome national crises that Korean people experienced during the Japanese Invasion in 1592, the second Manchu Invasion of Korea in 1636, and the Japanese Imperialism, and it shows the sufferings of our cultural assets and the history of preservation. Also, the album shows that one artwork is able to accumulate its historical meanings in the process of transmission and thus enhances its meanings and values. ${\ll}$Three Purities Album${\gg}$ features accumulative and constant historical meanings and it is a typical case showing that an artwork is plenty of aesthetic and historical values. It is expected that this work will contribute to promoting more studies on finding historical meanings and hysteresis of artworks.