• Tunnel and Underground Space
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• v.32 no.5
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• pp.285-297
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• 2022

We report results of Extended Leak-Off Test (XLOT) conducted in a large diameter borehole, which is drilled for installation of deep borehole geophysical monitoring system to monitor micro-earthquakes and fault behavior of major fault zones in the southeastern Korean Peninsula. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depth. We drilled first the 12" borehole to approximately 504 m deep and installed American Petroleum Institute standard 8-5/8" casing, then annulus between the casing and bedrock was fully cemented. XLOT was carried out for several purposes such as confirming casing and cementing integrity, measuring rock stress states. To that end, we drilled additional 4 m long open hole interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, flow rates and interval pressures were recorded in real time. Based on the logs we tried to analyze hydraulic conductivity of the test interval.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.260-267
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• 1995

In temperate zone planting rice at different date subjects the Crop to different climatic condition. The present study aimed at comparison of the change in source-sink relationship of the Japonica(J) and that of IndicaxJaponica(I$\times$J) type rice cultivars caused by shift of heading date. Two J- and two I$\times$J-type cultivars were made to head on August 16, August 26, and September 5. Sink capacity was changed by shift of heading date in different mode between the types of cultivars. In both types major determinant of sink capacity was number of effective tillers, and the number of spikelets per panicle was the minor. In J-type earlier planting/heading was beneficial to increased panicle numbers and this was due mainly to a larger diurnal difference in temperature. I$\times$J-type cultivars favored a higher daily mean temperature to increase the sink capacity. The ability of source at heading, in terms of leaf area per panicle, chlorophyll content per spiklet, photosynthetic ability of leaves per unit area at 25$\^{\circ}C$, carbohydrate and N contents of leaves, was not so different among different heading dates in both types. However, the source activity was governed principally by temperature during grain filling. The J-type cultivars headed on Sept. 5 and I$\times$J-type cultivars headed later than August 16 could not have had sufficient source activity in grain filling due to lower temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.2
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• pp.165-170
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• 1994

High quality rapeseed cultivars including Nojeokchae, Yeongsanyuchae Halla-yuchae and Tamrayuchae have been released and recommended as a zero erucic acid variety to Cheju farmers for 13 years, where is a major rapeseed production area in korea. However, rapeseeds produced in Cheju island in 1992 and 1993 contained 47.7% and 37.0% of erucic acid respectively resulting in poor quality oil being not adequate for edible oil. It was considered that the zero erucic acid varieties did not have an opportunity to be cultivated in Cheju island by farmers living in the Island. Thus, the new rapeseed varieties without erucic acid should be bred and recommended to the farmers of southern area of Korea as a multiple cropping crop just after rice harvest, and for large scale mechanized and labour-serving rapeseed culture. The change of rapeseed breeding goal would be desirable for fatty acid composition improvement of rapeseed to develop varieties adaptable to southern part of Korea, and to produce rapeseed oil directly used as an edible oil safely.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.5
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• pp.413-423
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• 1990

Corn proteins have been known as nutritionally poor, being deficient in the essential amino acids. lysine and tryptophan. Improving the quality of protein in the corn grain would be a great benefit to the farmer. This study was conducted to evaluate the variation of the protein content and the protein constitution of the maize germplasms in the Crop Experiment Station in 1989. The average protein content of 101 germplasms was 11.5% with range from 8.0% to 17.3%. Elite hybrid field corns and table corns possessed 9.1-13.9% protein for the dried whole kernel. Major amino acids were glutamic acid and leucine. Lysine and methionine were limited. Varietal differences were observed in the amino acid composition. Qpm, a modified opaque-2 mutant had 1.4-1.7 times higher lysine content than Suwon 19, a dent corn and Suwon SS-21, a sweet corn. Suwon SS-21 had high threonine content. Maize seed protein gave three fractions. an alchol-soluble fraction (zein), an alkali-soluble fraction (glutelin), and a salt-soluble fraction (globulin) by the Osborne method. The zein fraction accounted respectively for 50.7% and 41.7% of the total protein is Suwon 19 and Suwon SS-21. The nonzein fractions increased in percentage of total protein in Qpm kernels. The amino acid composition of zein fraction from three types maize endoperms of dent, sweet and opaque-2 was essentially identical. Zein contained the high contents of glutamic acid and leucine but low content of lysine. The glutelin fractions of three types maize endosperms were mainly similar in overall amino acid composition. The lysine content of glutelin was higher than that of zein. The amino acid composition of globulin fraction was some different from those of zein and glutelin In Qpm it had higher levels of histidine and lysine than both of zein and glutelin. The increased lysine content in Qpm was resulted from changing the proportions of proteins which contained different levels of lysine.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.104-115
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• 1992

The rice culture techniques included 'Jodosukyungbeob'(旱稻水耕法 : culture techniques of early-ripening paddy rice), 'Mandosukyungbeob' (晩稻水耕法) : culture techniques of late-Ripening paddy rice 'Handobeob'(旱稻＆lt;山稻＆gt;法 : culture techniques of upland rice), 'Myojongbeob'(苗種法 : culture techniques of paddy rice by transplanting), 'Kunangbeob'(乾秧法 : culture techniques of rice by transplanting which rears seeding in dry paddy) and 'Sudogunpanongbeob'(水稻乾播農法 : culture techniques of paddy rice seeding in dry field). Especially, 'Kunangbeob' and 'Sudogunpanongbeob' were originally developed in Korea as seen in 1600s(Kyoungje : 經濟) and early 1800s (Yoji : 要旨). In 'Jodosukyungbeob' it took 9 days for seed dipping, water-sprouting and prevent damage by birds, each for 3 days in China, but in Korea seed dipping in water took 3 days and the rest of the procedures were flexibly established. In matured soils, practices were fall plowing right after harvest, recognition of effective tillering and additional fertilization use of human manure, and stimulation of sprouting by lime application. The unique culture techniques adequate for Korean situations were practiced, which included weed control after draining accurately for 3 to 4 times, draining at mid season for improving wind and drought tolerance, rice harvesting at appropriate time for preventing grain shattering, and seeding in rows. 'Mandosukyungbeob' was improved techniques contrast to those of China, and the major contents were selection of proper varieties, good stand establishment by seeding high rates, induction of vigorous tillers, and adoption of 'Jokjongbeob'(足種法 : seeding method by foot). Also, one of the most prominent rice cultures by our ancestors was 'Kunpanongbeob' that was systemized form habitual practice of Pyongan Province. The unique technique actualized was 'Hando [旱稻(山稻)]' culture technique which was the combinations of 'Jokjongbeob', root stimulation method, and disaster-tolerant mixture cropping with adoptation of variety theory, although it was originated from China. The transplanting techniques has come before 'Jikseol'($\ulcorner$直說$\lrcorner$) and its merits were sufficiently realized. However, this method was basically prohibited from the early Chosun dynasty because extremely bad harvest was expected under drought conditions and insufficient conditions of water storage. But, it was permitted in the areas that contained water all the times and in case of large-scale farming especially. Most of rice culture was transplanted in the end of the Chosun dynasty because transplanting was continuously spreaded in the three southern provinces of Korea. Under these circumstances, transplanting technique was improved from the early to the end of the Chosun dynasty by weed control, fertilizing, water management, and quadratic transplanting. Based on these techniques, agricultural productivity was improved 5 times by that time. 'Kunpanongbeob' was created and developed properly for Korean conditions that is dry in early season and flooding in late season. This was successively developed and established into transplanting technique of nursery seedling.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.38-39
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• 2001

The seasonal changes in pH, Fe, Al and SO$_4$$\^$2-/ contents of acid drainage released from coal mine dumps play a major role in precipitation of metal hydroxides in the Taebaek coal field area, southeastern Korea. Precipitates in the creeks underwent a cycle of the color change showing white, reddish brown and brownish yellow, which depends on geochemical factors of the creek waters. White precipitates consist of Al-sulfate (basaluminite and hydrobasaluminite) and reddish brown ones are composed of ferrihydrite and brownish yellow ones are of schwertmannite. Goethite coprecipitates with ferrihydrite and schwertmannite. Ferrihydrite formed at higher values than pH 5.3 and schwertmannite precipitated below pH 4.3, and goethite formed at the intermediate pH range between the two minerals. With the pH being increased from acid to intermediate regions, Fe is present both as schwertmannite and goethite. From the present observation, the most favorable pH that basauluminte can precipitate is in the range of pH 4.45-5.95. SEM examination of precipitates at stream bottom shows that they basically consist of agglomerates of spheroid and rod-shape bacteria. Bacteria species are remarkably different among bottom precipitates and, to a less extent, there are slightly different chemical compositions even within the same bacteria. The speciation and calculation of the mineral saturation index were made using MINTEQA2. In waters associated with yellowish brown precipitates mainly composed of schwertmannite, So$_4$ species is mostly free So$_4$$\^$2-/ ion with less AlSo$_4$$\^$+/, CaSo$\sub$(aq)/, and MgSo$\sub$4(aq)/. Ferrous iron is present mostly as free Fe$\^$2+/, and FeSo$\sub$4(aq)/ and ferric iron exists predominantly as Fe(OH)$_2$$\^$+/, with less FeSo$\sub$4(aq)/, Fe(OH)$_2$$\^$-/, FeSo$_4$$\^$-/ and Fe$\^$3+/, respectively Al exists as free Al$\^$3+/, AlOH$_2$$\^$-/, (AlSo$_4$)$\^$+/, and Al(So$_4$)$\^$2-/. Fe is generally saturated with respect to hematite, magnetite, and goethite, with nearly saturation with lepidocrocite. Aluminum and sulfate are supersaturated with respect to predominant alunite and less jubanite, and they approach a saturation state with respect to diaspore, gibbsite, boehmite and gypsum. In the case of waters associated with whitish precipitates mainly composed of basaluminite, Al is present as predominant Al$\^$3+/ and Al(SO$_4$)$\^$+/, with less Al(OH)$\^$2+/, Al(OH)$_2$$\^$+/ and Al(SO$_4$)$\^$2-/. According to calculation for the mineral saturation, aluminum and sulfate are greatly supersaturated with respect to basaluminite and alunite. Diaspore is flirty well supersaturated while jubanite, gibbsite, and boehmite are already supersaturated, and gypsum approaches its saturation state. The observation that the only mineral phase we can easily detect in the whitish precipitate is basaluminite suggests that growth rate of alunite is much slower than that of basaluminite. Neutralization of acid mine drainage due to the dilution caused by the dilution effect due to mixing of unpolluted waters prevails over the buffering effect by the dissolution of carbonate or aluminosilicates. The main factors to affect color change are variations in aqueous geochemistry, which are controlled by dilution effect due to rainfall, water mixng from adjacent creeks, and the extent to which water-rock interaction takes place with seasons. pH, Fe, Al and SO$_4$ contents of the creek water are the most important factors leading to color changes in the precipitates. A geochemical cycle showing color variations in the precipitates provides the potential control on acid mine drainage and can be applied as a reclamation tool in a temperate region with four seasons.

• Journal of the Korean Electrochemical Society
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• v.26 no.1
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• pp.1-10
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• 2023

The cathode, which is one of the four major components of a lithium secondary battery, is an important component responsible for the energy density of the battery. The mixing process of active material, conductive material, and polymer binder is very essential in the commonly used wet manufacturing process of the cathode. However, in the case of mixing conditions of the cathode, since there is no systematic method, in most cases, differences in performance occur depending on the manufacturer. Therefore, LiMn₂O₄ (LMO) cathodes were prepared using a commonly used THINKY mixer and homogenizer to optimize the mixing method in the cathode slurry preparation step, and their characteristics were compared. Each mixing condition was performed at 2000 RPM and 7 min, and to determine only the difference in the mixing method during the manufacture of the cathode other experiment conditions (mixing time, material input order, etc.) were kept constant. Among the manufactured THINKY mixer LMO (TLMO) and homogenizer LMO (HLMO), HLMO has more uniform particle dispersion than TLMO, and thus shows higher adhesive strength. Also, the result of the electrochemical evaluation reveals that HLMO cathode showed improved performance with a more stable life cycle compared to TLMO. The initial discharge capacity retention rate of HLMO at 69 cycles was 88%, which is about 4.4 times higher than that of TLMO, and in the case of rate capability, HLMO exhibited a better capacity retention even at high C-rates of 10, 15, and 20 C and the capacity recovery at 1 C was higher than that of TLMO. It's postulated that the use of a homogenizer improves the characteristics of the slurry containing the active material, the conductive material, and the polymer binder creating an electrically conductive network formed by uniformly dispersing the conductive material suppressing its strong electrostatic properties thus avoiding aggregation. As a result, surface contact between the active material and the conductive material increases, electrons move more smoothly, changes in lattice volume during charging and discharging are more reversible and contact resistance between the active material and the conductive material is suppressed.

• Journal of Ginseng Culture
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• v.5
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• pp.52-76
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• 2023

This article focuses on changes in the ginseng industry in the 1930s in areas other than the Government Contract Cultivation (GCC) zones. A major characteristic of the ginseng industry in the 1930s was the rapid increase in the area covered by ginseng gardens: the area was about 212 ha in 1929 and 252 ha in 1930 and 1931 but soared to around 441 ha in 1938. This occurred because the non-GCC areas increased significantly during this period. Until the early 1930s, the ratio of GCC to non-GCC areas was 70:30. By the late 1930s, however, the ratio had changed to 53:47. The reason for this change was that the area of the newly established ginseng gardens in the GCC zones had decreased, while that of the non-GCC ginseng gardens had steadily increased. Due to the Japanese invasion of China, China boycotted red ginseng, and exports were sluggish, so the GCC areas were reduced. On the other hand, the non-GCC ginseng gardens were not affected, and the area they covered steadily increased. As a result, in the 1930s, the ginseng industry outside of the GCC areas grew rapidly. The region that led the growth of the ginseng industry outside of the GCC zone was Jeonbuk. By the late 1930s, Jeonbuk dominated the other provinces and accounted for more than 50% of the non-GCC farming zone. Gyeongbuk and Gangwon-do followed Jeonbuk in terms of ginseng cultivation areas. While Gyeonggi-do, Gyeongnam, and Chungbuk were also active in ginseng cultivation, Jeonnam and Chungnam were not active. In the 1930s, the growth of the ginseng industry outside of the GCC zones was driven by the efforts of ginseng farmers and the support of local governments. An examination of Yecheon-gun in Gyeongbuk, Ganghwa-gun in Gyeonggi, and Jecheon-gun in Chungcheongbuk-do showed that ginseng farmers organized cooperatives as the ginseng industry steadily developed in these regions, and these cooperatives worked systematically to cultivate and sell ginseng. In the case of Ganghwa-gun, activities were carried out to incorporate the GCC zone. The Deoksan Ginseng Association in Jecheon-gun determined that financing for cultivation was key and requested subsidies from the provincial government. Administrative authorities also supported the activities of the ginseng farmers. The activities of the farmers and the support of the administrative authorities together led to the growth of the ginseng industry during this period.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.19-40
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• 2023

To investigate the role of water masses in the Jeju Strait in summer on the shallow coastal region and the characteristics of water properties in the strait, temperature and salinity were observed across the Jeju Strait in June, July, and August 2019. The cold water pool, whose temperature is lower than 15℃, was observed in the mid-depths of the central Jeju Strait and on the northern bottom slope of the strait. The cold water pools have the lowest temperature in the strait. To identify water masses comprising the cold water pool in the Jeju Strait, mixing ratios of water masses were calculated. The mid-depth cold water pool of the Jeju Strait consists of 54% of the Kuroshio Subsurface Water (KSSW) and 33% of the Yellow Sea Bottom Cold Water (YSBCW). Although the cold water pool is dominantly affected by the KSSW, the YSBCW plays a major role to make the cold water pool maintain the lowest temperature in the Jeju Strait. To find origin of the cold water pool, temperature and salinity data from the Yellow Sea, East China Sea, and Korea Strait in the summer of 2019 were analyzed. The cold water pool was generated along the thermohaline frontal zone between the KSSW and YSBCW in the East China Sea where intrusion and mixing of water masses are active below the seasonal thermocline. The cold water in the thermohaline frontal zone had similar mixing ratio to the cold water pool in the Jeju Strait and it advected toward the Korea Strait and shallow coastal region off the south coast of Korea. Intrusion of the mid-depth cold water pool made temperature inversion in the Jeju Strait and affected sea surface temperature variations at the coastal region off the south coast of Korea.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.185-200
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• 2022

The risk of various hazardous substances in aquatic environment comprises not only the concentration of substances in the environmental medium but also their accumulation in fish through complex food web and the health risks to humans through the fish. In Korea, the monitoring of residual toxicant in aquatic ecosystems began in 2016 following the enforcement of the Acts on registration and evaluation for the management of chemicals used in daily life (consumer chemical products), and attention has been paid to potentially hazardous substances attributed to them. Recently, studies have been carried out to investigate the distribution of these hazardous substances in the ecosystem and calculate their emission factors. These include the accumulation and transport of substances, such as detergents, dyes, fragrances, cosmetics, and disinfectants, within trophic levels. This study summarizes the results of recently published research on the inflow and distribution of hazardous substances from consumer chemical products to the aquatic environment and presents the scientific implication. Based on studies on aquatic environment monitoring techniques, this study suggests research directions for monitoring the residual concentration and distribution of harmful chemical substances in aquatic ecosystems. In particular, this study introduces the directions for research on trophic position analysis using compound specific isotope analysis and trophic magnification factors, which are needed to fulfill the contemporary requirements of selecting target fish based on the survey of major fish that inhabit domestic waters and assessment of associated health risk. In addition, this study provides suggestions for future biota monitoring and chemical research in Korea.