• Korean Journal of Agricultural Science
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• v.27 no.1
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• pp.39-47
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• 2000

A large scale field test of prefabricated vertical drains is performed to analyze the effect of parameters of the very soft clay at a test site. Compression index and the coefficient of horizontal consolidation obtained by back-analysis from the settlement data were compared with those obtained by means of laboratory tests. The Hyperbolic, Asaoka's and The Curve fitting methods are used to estimate final settlements and coefficients of consolidation. 1. Final settlement predicted with the Hyperbolic method was the largest, and the settlements predicted with the Asaoka's and the Curve fitting methods were nearly the same range, and it was concluded that smear effect has to be considered on design in the case that spacing of drains is small 2. The relationships of the measured consolidation ratio (Urn) and the designed consolidation ratio($U_t$) were showed as $U_m$ = (1.13~1.17)$U_t$, $U_m$ = (1.07~1.20)$U_t$, $U_m$ = (1.13~1.17)$U_t$ on the Hyperbolic, Asaoka's and the Curve fitting methods, respectively. The relations on the Asaoka's and the Curve fitting methods were nearly the same range. 3. The relationships of the field compression index($C_{cfield}$) and virgin compression index($V_{cclab}$) were showed as $C_{cfield}$ = (1.26~1.45)$V_{cclab}$, $C_{cfield}$ = (1.08~1.15) $V_{cclab}$, $C_{cfield}$ = (1.04~1.21)$V_{cclab}$, on the Hyperbolic, Asaoka's and the Curve fitting methods, respectively. 4. The ratio ($C_h/C_v$) of the coefficient of vertical consolidation and the coefficient of horizontal consolidation that is obtained by back-analysis from the settlement data was $C_h$=(0.7~0.9)$C_v$, $C_h$=(0.9~1.5)$C_v$, $C_h$=(2.4~3.0)$C_v$ on the Hyperbolic, Asaoka's and the Curve fitting methods, respectively. 5. It was concluded that the exact consolidation coefficient must be determined after the final settlement is predicted again when the consolidation is finished, because the field consolidation coefficient is decreased as the time allowed to be alone is increased.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.433-445
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• 2021

Plasma blasting by high voltage arc discharge were performed in laboratory-scale soil samples to investigate the fluid penetration efficiency. A plasma blasting device with a large-capacity capacitor and columnar soil samples with a diameter of 80 cm and a height of 60 cm were prepared. Columnar soil samples consist of seven A-samples mixed with sand and silt by ratio of 7:3 and three B-samples by ratio of 9:1. When fluid was injected into A-sample by pressure without plasma blasting, fluid penetrated into soil only near around the borehole, and penetration area ratio was less than 5%. Fluid was injected by plasma blasting with three different discharge energies of 1 kJ, 4 kJ and 9 kJ. When plasma blasting was performed once in the A-samples, penetration area ratios of the fluid were 16-25%. Penetration area ratios were 30-48% when blastings were executed five times consecutively. The largest penetration area by plasma blasting was 9.6 times larger than that by fluid injection by pressure. This indicates that the higher discharge energy of plasma blasting and the more numbers of blasting are, the larger are fluid penetration areas. When five consecutive plasma blasting were carried out in B-sample, fluid penetration area ratios were 33-59%. Penetration areas into B-samples were 1.1-1.4 times larger than those in A-samples when test conditions were the same, indicating that the higher permeability of soil is, the larger is fluid penetration area. The fluid penetration radius was calculated to figure out fluid penetration volume. When the fluid was injected by pressure, the penetration radius was 9 cm. Whereas, the penetration radius was 27-30 cm when blasting were performed 5 times with energy of 9 kJ. The radius increased up to 333% by plasma blasting. All these results indicate that cleaning agent penetrates further and remediation efficiency of contaminated soil will be improved if plasma blasting technology is applied to in situ cleaning of contaminated soil with low permeability.

• Journal of Ginseng Culture
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• v.3
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• pp.54-73
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• 2021

The Natural Products Research Institute (NPRI, 生藥硏究所), an institution affiliated with Keijo Imperial University (京城帝國大學), was the predecessor of the NPRI at Seoul National University and a comprehensive research institute that focused on ginseng research during the Japanese colonial era. It was established under the leadership of Noriyuki Sugihara (杉原德行), a professor of the second lecture in pharmacology at the College of Medicine in Keijo Imperial University. Prof. Sugihara concentrated on studying Korean ginseng and herbal medicine beginning in 1926 when the second lecture of pharmacology was established. In addition to Prof. Sugihara, who majored in medicine and pharmacology, Kaku Tenmin (加來天民), an assistant professor who majored in pharmacy; Tsutomu Ishidoya (石戶谷勉), a lecturer who majored in agriculture and forestry; and about 36 researchers actively worked in the laboratory before the establishment of the NPRI in 1939. Among these personnel, approximately 14 Korean researchers had basic medical knowledge, derived mostly from specialized schools, such as medical, dental, and pharmaceutical institutions. As part of the initiative to explore the medicinal herbs of Joseon, the number of Korean researchers increased beginning in 1930. This increase started with Min Byung-Ki (閔丙祺) and Kim Ha-sik (金夏植). The second lecture of pharmacology presented various research results in areas covering medicinal plants in Joseon as well as pharmacological actions and component analyses of herbal medicines. It also conducted joint research with variousinstitutions. Meanwhile, in Gaesong (開城), the largest ginseng-producing area in Korea, the plan for the Pharmaceutical Industry Complex was established in 1935. This was a large-scale project aimed at generating profits through research on and the mass production of drugs and the reformation of the ginseng industry under collaboration among the Gaesong Ministry, Kwandong (關東) military forces, Keijo Imperial University, and private organizations. In 1936 and 1938, the Gyeonggi Provincial Medicinal Plant Research Institute (京畿道立 藥用植物硏究所) and the Herb Garden of Keijo Imperial University (京城帝國大學 藥草園) and Pharmaceutical Factory were established, respectively. These institutions merged to become Keijo Imperial University's NPRI, which wasthen overseen by Prof. Sugihara as director. Aside from conducting pharmacological research on ginseng, the NPRI devoted efforts to the development and sale of ginseng-based drugs, such as Sunryosam (鮮麗蔘), and the cultivation of ginseng. In 1941, the Jeju Urban Test Center (濟州島試驗場) was established, and an insecticide called Pancy (パンシ) was produced using Jeju-do medicinal herbs. However, even before research results were published in earnest, Japanese researchers, including Prof. Sugihara, hurriedly returned to Japan in 1945 because of the surrender of Japanese forces and the liberation of Korea. The NPRI was handed over to Seoul National University and led by Prof. Oh Jin-Sup (吳鎭燮), a former medical student at Keijo Imperial University. Scholars such as Woo Lin-Keun (禹麟根) and Seok Joo-Myung (石宙明) worked diligently to deal with the Korean pharmaceutical industry.