• Journal of Biosystems Engineering
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• v.32 no.4
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• pp.207-214
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• 2007

Based on the profiles of cone index with depth, physical properties of hardpan in selected rice fields were measured and analyzed in the study. An error correction algorithm removing a random measurement error from raw CI profile data was introduced in the study. The properties of hardpan included the shape, the thickness and the rice root growing layer. The analysis of physical properties of hardpan in the rice fields showed that the type of hardpan could be classified into 6 categories. The thickness of hardpan ranged from 6 cm up to 41 cm and the average hardness of hardpan was analyzed to be from 1.1 MPa through 3.2 MPa in Cone index.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.321-321
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• 2017

Water availability in rainfed lowlands (RFL) is strongly affected by climate change. In RFL, rice plants are exposed to soil moisture fluctuations (SMF) but rarely to simple progressive drought as widely believed. Typical RFL field is characterized by a about 5-cm thick high bulk density hardpan layer underneath the cultivated layer at about 20 cm depth that impedes deep root development. Root system has the ability to develop in response to changes in SMF, known as phenotypic plasticity. We hypothesized that genotypes that can adapt to RFL have root plasticity. The roots can sharply respond to re-wetting after drought period and thus penetrate the hardpan layer when the hardpan is wet and so becomes relatively soft, and thus access water under the hardpan. This study aimed to identify CSSLs derived from a cross between Sasanishiki and Habataki which adapted to such RFL conditions. We used 39 CSSLs together with the parent Sasanishiki, which were grown in hydroponics and pot under transient soil moisture stresses (drought and then rewatering), and compared with continuously well-watered (WW) (control) up to 14 days after sowing (DAS), and 20 DAS, respectively. Based on the results of hydroponics and pot experiments, we selected a few lines, which were grown in the soil-filled rootbox with artificial hardpan layer and without artificial hardpan. For the rootbox without artificial hardpan, plants were grown under WW and transient soil moisture stresses for 49 DAS. While the rootbox with artificial hardpan, the plants were grown under WW (control) and SMF (WW up to 21 DAS, 1st drought (22-36 DAS), rewatering (37-44 DAS), and followed by 2nd drought (45-58 DAS)). Among the 39 CSSLs, only CSSL439 (SL39) consistently showed significantly higher shoot dry weight (SDW) than Sasanishiki under transient soil moisture stress conditions as well as SMF conditions in all the experiments. Furthermore, under WW, SL39 consistently showed no significant differences from Sasanishiki in shoot and root growth in most of traits examined. SL39 showed significantly greater total root length (TRL) than Sasanishiki under transient soil moisture stress, which is considered as phenotypic plasticity in response to rewatering after drought period. Such plastic root development was the key trait that effectively contributed to root elongation and branching during the rewatering period and consequently enhanced the root to penetrate hardpan layer when the soil penetration resistance at hardpan layer reduced. In addition, using the rootbox with artificial hardpan layer ($1.7g\;cm^{-3}$, heavily compacted), SL39 showed greater root system development than Sasanishiki under SMF, which was expressed in its significantly higher TRL, total nodal RL, and total lateral RL at hardpan layer as well as at below the hardpan layer. These results prove that SL39 has plasticity that enables its root systems to penetrate hardpan layer in response to rewatering. Under SMF, such root plasticity contributed to its higher gs and Pn.

• Journal of Biosystems Engineering
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• v.24 no.4
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• pp.293-300
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• 1999

The objectives of this study were to analyze the load acting on the transmission when tractor performed rotary operations in the poorly drained paddy fields and to compare its severeness with those obtained under different operational conditions. The loads were measured at the input shaft of the transmission and the load spectrum was constructed using the rain-flow cycle counting method. The severeness of the loads was represented by the partial damage sum which was determined by suing the modified Miner's rule. In the field with a shallow hardpan PTO speed affected severeness of the rotary operations greater than the forward speed did. In the field with deep hardpan, on the other hand, the effect of the forward speed was greater. the severeness in the well drained fields did not differ significantly from that in the field with a shallow hardpan. The severest load was recorded in the field with a deep hardpan.

• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.79-88
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• 2000

Effects on tractive performance of design parameters of cage wheel as a traction aid to driving tires of tractor in wet paddy field were investigated experimentally. an experimental cage wheel was designed so that the design parameters such as wheel diameter, wheel width, lug pitch and lug angle could be varied during traction test, The traction test was conducted in two different types of wet paddy field ; shallow and deep harpan fields . Experimental results showed that tractive performance is affected by both soil conditions and the design parameters. A considerable improvement on the tractive performance was obtained by using a cage wheel with 45$^{\circ}$ lug angle in shallow hardpan and smaller lug pitch in deep hardpan. The diameter of cage wheel was mostly influential to the tractive performance both in shallow and deep hardpans.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.293-302
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• 2008

The limiting factors to determine available soil depth were studied with 390 soil series in soil profile description and physicochemical data in Korean soils. The limiting factors were coarse sandy layer, gravel and skeletal layer, hardpan layer, cat clay layer, poorly drained layer, salt accumulated layer and bed rock layer so on. The soils of having limiting factors were 332 soil series, but soils without limiting factors were 58 soil series. Soils with limiting factors were, hardpan 5, slopeness 93, immature soil 29, cinder 5, sandy 42, gravel or skeletal 47, bedrock 19, high salt content 8, poorly drained soil 22, heavy clay 32, sulfate soil 3 and ash soil 27 etc. And the orders of available soil depth were immature > slopeness > ash > heavy clay > sandy > gravel or skeletal > hardpan > cindery > poorly drained > bedrock > acid sulfate soil > salt accumulated soil etc.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.101-108
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• 2000

The torque loads were measured at the input shaft of the transmission and driving shaft of the tractor having a cage wheel attached to the driving tires as a traction aid during. a rotavating operation in wet paddy fields with deep hardpan. Their load spectra were also calculated. Effects of design parameters of the cage wheel on the load characteristics were analyzed. The torque load exerted on the input shaft decreased as diameter of the cage wheel increased and increased as the rotating speed of the rotavator increased. The torque load exerted on the driving shaft increased as the working speed of the tractor increased and decreased as the PTO speed increased. Both the torque loads with the cage wheel were greater than those without the cage wheel. The cage wheel was developed for this study.

• Journal of Biosystems Engineering
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• v.29 no.4
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• pp.301-306
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• 2004

Soil stresses were measured beneath the centerline of one new 12.4R28 radial-ply tractor tire. The tire was operated with three inflation pressures(59㎪ 108㎪ and 157㎪) and a dynamic load of 14.2 kN and 20% slip. Soil stress state transducer(SST) measured the stresses in a hardpan soil profile. The depth of the SST was 250mm from soil surface. Analysis of the original soil stress data showed that the inflation pressure of tire did significantly affect the vertical stress. The major principal stresses calculated were more when the inflation pressure was 108㎪ than when it was 157㎪. The peak stresses of the major principal stresses presented more than those of the vertical stresses.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.77-91
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• 2015

This study aims to suggest adequate soil management through the analysis of physicochemical properties of soil in the planting grounds of Incheon International Airport, which was constructed on a massive land reclamation site. Study areas were 5 sites at the international business complex, the passenger terminal, the airport support complex, the free trade zone, and the access road. Soil profile analysis showed that 9 plots out of the 27 plots were hardpan and heterospere within 80cm from the soil surface. The earth laid on the ground was categorized as gravel based soil(4 plots), dredged soil from the sea bottom and mixed reclamation materials(2 plots), clay with poor permeability(3 plots) and waste construction material(1 plot). Average soil hardness was $11.5kg/cm^2$ and soil textures were sandy soil, sandy loam and loamy sand. Average soil pH was 6.7 and average organic matter content was 0.7%. Electrical conductivity was 0.0dS/m and exchangeable cation concentrations were $Ca^{2+}$ 3.4cmol/kg, $Mg^{2+}$ 1.5cmol/kg, $K^+$ 0.3cmol/kg and $Na^+$ 1.0cmol/kg. Average cation exchange capacity was 11.0cmol/kg. Although average figures in Solum mostly meet the landscape design criteria, properties of each soil layer showed various values sometimes over the limit. Base saturations were $Ca^{2+}$ 29.9%, $Mg^{2+}$ 13.3% and $K^+$ 3.7% for lower soil, $Ca^{2+}$ 33.3%, $Mg^{2+}$ 17.0% and $K^+$ 2.7% for mid-soil and $Ca^{2+}$ 32.6%, $Mg^{2+}$ 12.2% and $K^+$ 1.9% for upper soil. Exchangeable sodium percentages were 16.4% for lower soil, 7.5% for mid-soil and 4.7% upper soil. Sodium adsorption rates were 0.8 for lower soil, 0.3 for mid-soil and 0.2 for upper soil. Factors affecting to the vegetation growth were heterogeneity and poorness of solum, disturbance of dredged soils, high soil hardness including hardpan in the subsurface soil layer and shallow effective soil depth, high soil acidity, imbalance of base contents, low organic matter content and low available phosphate levels in the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.336-340
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• 2004

The objective of this study was to establish the decision criteria of land suitability for red pepper using soil morphological and physical properties. The investigation was carried out in Jechen, Goesan, Euiseong, Andong, Gochang and Pyongchang district in Korea. The obtained results showed that factors related to the decision criteria of the land suitability for red pepper cultivation were soil texture, soil drainage class, land slope, available soil depth and stone content. The criteria of the best suitable soil for red pepper was coarse loamy, well drainage class, C-slope (7-15%), 10-20% gravel content and available soil depth deeper than 100 cm. Also in the best suitable soil, hardpan was located below 100 cm from the soil surface. Outbreak rate of phytophthora blight occurred well in the soils with high clay content, poor drainage class, low land slope and low gravel content. Database determining the decision criteria of the land suitability for red pepper in Jinchen-gun was established by Arc info GIS tool.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.137-144
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• 2012

Soil pan typically presents the problems in soil water movement or in aeration which is not appropriate for a plant root growth, In this study physico-chemical characteristics of soils and micromorphological characteristic of clay accumulated zone were investigated to identify redox characteristic and evolution of a fragipan of Gangreung series commonly developed in coastal terraces. Gangreung series is classified as Aquic Fragiudalfs according to the USDA soil taxonomy. It is known that sedimentary ocean floor results in soil pan having parallel liner soil structure due to landscape evolution around 200 to 250 million years ago. it is considered that illite, kaolinite, and vermiculite are major clay minerals contained in a fragipan of Gangreung series. Mixed gray and reddish brown colored band around soil pores was found and would be the redoxmorphic features of fragipan. It is possibly due to accumulated illuvial clay and ferriargillans in soil pores and aggregates in reducing conditions eluding ferrous material. Therefore, mixed colored band around pores in soils of Gangreung series would be developed from the eluted ferrous materials which were accumulated in fragipan during the emerged land formation.